WO2022025054A1

WO2022025054A1 - Ammonia production method

Info

Publication number: WO2022025054A1
Application number: PCT/JP2021/027734
Authority: WO
Inventors: 仁昭西林; 和也荒芝; 裕也芦田; 章一近藤; 隆正菊池
Original assignee: 国立大学法人東京大学; 日産化学株式会社
Priority date: 2020-07-27
Filing date: 2021-07-27
Publication date: 2022-02-03
Also published as: JP2023126983A

Abstract

[Problem] To provide an ammonia production method using a molybdenum complex. [Solution] This ammonia production method comprises a step for generating ammonia from a nitrogen molecule in the presence of a molybdenum complex, a reducing agent, and a proton source, wherein: the proton source is alcohol or water; the molybdenum complex is a molybdenum complex represented by formula (1) (in formula (1), R¹ and R² each independently represent a C3-C6 alkyl group, X is an iodine atom, a bromine atom, or a chlorine atom, and R³ and R⁴ each independently represent a hydrogen atom or an electron-withdrawing group); and in a selenium adduct of a pincer-type ligand represented by formula (2) (in formula (2), R¹, R², R³, and R⁴ are the same as above), which is a selenium adduct in which selenium atoms are bonded to three bonding sites of a pincer-type ligand having the three bonding sites including two phosphines and carbene carbon of a benzimidazole ring in a molecule derived from the molybdenum complex, the ⁷⁷SeNMR chemical shift value of selenium on the carbene carbon of the benzimidazole ring is a value of a magnetic field lower than 170 ppm.

Description

Ammonia production method

The present invention relates to a method for producing ammonia.

There is a report example on the production of ammonia using a molybdenum complex as a catalyst and water as a proton source in a method for producing ammonia from nitrogen molecules (Non-Patent Document 1). Furthermore, there is a report on the production of ammonia using a molybdenum complex as a catalyst, samarium (II) iodide as a reducing agent, and alcohols or water as a proton source (Non-Patent Document 2).

In the method of producing ammonia from nitrogen molecules, when a molybdenum complex is used as a catalyst, it is also an important point of view that ammonia can be obtained immediately when necessary from the viewpoint of practical use, and the reaction is carried out at high speed from the initial stage of the reaction start. A catalyst that can be produced is desired.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to create a molybdenum complex capable of reacting at high speed from the initial stage of reaction initiation.

As a result of diligent studies to solve the above problems, the present inventors have found a pincer-type ligand having three bond sites of two phosphines and carben carbon of a benzoimidazole ring in a molecule derived from a molybdenum complex. It was found that there is a correlation between the chemical shift value of selenium on the carben carbon of ⁷⁷ SeNMR of the selenium adduct in which the selenium atom is bonded to the three bonding sites and the catalytic activity, and the chemical shift value is lower than 170 ppm. A selenium adduct of a pincer-type ligand indicating a magnetic field value is molecularly designed or synthesized, and the catalyst rotation frequency (Turnover Chemistry (hereinafter abbreviated as TOF)), which is the amount of substance conversion performed by one catalyst molecule per unit time, is determined. We have found more than 200 (1 / min) molybdenum complexes and have completed the present invention.

That is, the present invention is, as a first aspect, a production method including a step of producing ammonia from nitrogen molecules in the presence of a molybdenum complex, a reducing agent and a proton source.
The proton source is alcohol or water.
The molybdenum complex has the formula (1):

(In the formula (1), R ¹ and R ² each independently represent an alkyl group having 3 to 6 carbon atoms.
X is an iodine atom, a bromine atom or a chlorine atom,
R ³ and R ⁴ each independently represent a hydrogen atom or an electron-withdrawing group. )
It is a molybdenum complex represented by
A formula that is a selenium adduct in which a selenium atom is bonded to the three bonding sites of a pincer-type ligand having three bonding sites of two phosphines and carbene carbon of a benzimidazole ring in a molecule derived from the molybdenum complex. 2):

(In equation (2), R ¹ , R ² , R ³ and R ⁴ are the same as above.)
In the selenium adduct of the pincer-type ligand represented by, the chemical shift value of ⁷⁷ SeNMR of selenium on the carbene carbon of the benzimidazole ring is a value in a magnetic field lower than 170 ppm.
Regarding the method of producing ammonia.
The second aspect is a method for evaluating the catalytic performance of a molybdenum complex when producing ammonia from nitrogen molecules in the presence of a molybdenum complex, a reducing agent and a proton source.
The molybdenum complex has the formula (1):

(In equation (2), R ¹ , R ² , R ³ and R ⁴ are the same as above.)
A step of preparing a selenium adduct of a pincer-type ligand represented by the above, and a step of measuring ⁷⁷ SeNMR of the selenium adduct of the pincer-type ligand.
In a molybdenum complex having a Turnover Frequency of more than 200 (1 / min), depending on whether the chemical shift value of ⁷⁷ SeNMR of selenium on the carbene carbon of the benzimidazole ring is a value in a magnetic field lower than 170 ppm. Regarding the method of determining whether or not there is.
As a third viewpoint, it is a molybdenum complex represented by the following formula (1).

(In the formula (1), R ¹ and R ² each independently represent an alkyl group having 3 to 6 carbon atoms.
X is an iodine atom, a bromine atom or a chlorine atom,
R ³ and R ⁴ each independently represent a hydrogen atom or an electron-withdrawing group.
However, when R ³ is a fluorine atom, R ⁴ is not a fluorine atom, and when R ³ is a hydrogen atom, R ⁴ is not a trifluoromethyl group. )
A formula that is a selenium adduct in which a selenium atom is bonded to the three bonding sites of a pincer-type ligand having three bonding sites of two phosphines and carbene carbon of a benzimidazole ring in a molecule derived from the molybdenum complex. 2):

(In equation (2), R ¹ , R ² , R ³ and R ⁴ are the same as above.)
It relates to a molybdenum complex in which the chemical shift value of ⁷⁷ SeNMR of selenium on the carbene carbon of the benzimidazole ring is a value in a magnetic field lower than 170 ppm in the selenium adduct of the pincer type ligand represented by.

According to the method for producing ammonia of the present invention, a method capable of producing ammonia from the initial stage of reaction initiation is provided by using a molybdenum complex capable of reacting at high speed.
In addition, ⁷⁷ of the selenium adduct in which a selenium atom is bonded to the three bonding sites of a pincer-type ligand having three bonding sites of two phosphines and carbene carbon of the benzoimidazole ring in the molecule derived from the molybdenum complex. Provided is a method capable of evaluating the catalytic performance of the molybdenum complex by measuring SeNMR.

For the ⁷⁷ SeNMR chemical shift value of selenium on the carbene carbon of the benzoimidazole ring of the selenium adduct of the pincer-type ligand having various substituents introduced into R ³ and R ⁴ represented by the formula (6'). , Is a graph plotting the TOF (1 / min) value of ammonia synthesis catalyzed by the molybdenum complex represented by the formula (1') corresponding to the selenium adduct of each pincer-type ligand.

In the present specification, "n" stands for normal, "i" stands for iso, "s" stands for secondary, "t" stands for tertiary, "c" stands for cyclo, "o" stands for ortho, and "m". "" Represents meta, and "p" represents para. “Me” represents a methyl group, “Et” represents an ethyl group, “ ^tBu ” represents a tertiary butyl group, “TMS” represents a trimethylsilyl group, and “thf” represents a tetrahydrofuran.
The method for producing ammonia of the present invention and the preferred embodiment of the molybdenum complex represented by the formula (1) used in the production method are shown below.
Suitable embodiments of the method and apparatus for producing ammonia of the present invention are shown below.

In the molybdenum complex represented by the formula (1)
R ¹ and R ² each independently represent an alkyl group having 3 to 6 carbon atoms. Here, examples of the alkyl group having 3 to 6 carbon atoms include an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, an n-pentyl group, and an isopentyl group. , Neopentyl group, t-pentyl group, 1,1-dimethylpropyl group, n-hexyl group, isohexyl group, cyclohexyl group and the like, and t-butyl group is preferable.
X represents an iodine atom, a bromine atom or a chlorine atom. Here, X is preferably an iodine atom or a chlorine atom.

R ³ and R ⁴ each independently represent an electron-withdrawing group. An electron-withdrawing group is also called an electron-withdrawing group or an electron-accepting group. In.), It represents a substituent that attracts an electron from the bonded electron side as compared with a hydrogen atom due to a mesomeric effect or an induced effect.

In the method for producing ammonia of the present embodiment, R ³ and R ⁴ have two bonding sites of phosphine and carbene carbon of the benzoimidazole ring in the molecule derived from the molybdenum complex represented by the formula (2). In a selenium adduct in which a selenium atom is bonded to the three bonds of a pincer-type ligand, the chemical shift value of ⁷⁷ SeNMR of selenium on the carbene carbon of the benzoimidazole ring is a substitution showing a value of a magnetic field lower than 170 ppm. It may be a basis. If the combination of R ³ and R ⁴ satisfies the above chemical shift value, R ³ and R ⁴ may be electron-withdrawing groups, and if R ³ is an electron-withdrawing group, R ⁴ is a hydrogen atom. It may be.

In the method for producing ammonia of the present embodiment, examples of the electron-withdrawing group include a substituent whose mesomeric effect is electron-donating but the inductive effect has a large contribution to the electron-withdrawing property, and more specifically. , Fluorine atom, chlorine atom, bromine atom, iodine atom, -CH ₂ Cl or -CH = CHNO ₂ . Examples of the electron-attracting group include substituents whose mesomeric effect and induced effect are electron-attracting, and more specifically, a quaternary ammonium group having an anion as a counter ion, trifluoromethyl. Group, perfluoroalkyl group, trichloromethyl group, cyano group, nitro group, formyl group, carboxylic acid group, carbonyl (C _1-6 alkyl) group, carbonyl (C _1-6 alkoxy) group, carbonyl (Ar _6-10 ) Aryl) group, carbonylamino group, carbonyl (C _1-6 alkyl) amino group, carbonyl di (C _1-6 alkyl) amino group, sulfonic acid group, sulfonyl amino group, sulfonyl (C _1-6 alkyl) amino group, Examples thereof include a sulfonyldi (C _1-6 alkyl) amino group and an Ar _6-10 aryl group.

C _1-6 alkyl represents an alkyl group having 1 to 6 carbon atoms. Here, specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, a trifluoromethyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and an s-butyl group. Examples thereof include t-butyl group, n-pentyl group, isopentyl group, neopentyl group, t-pentyl group, 1,1-dimethylpropyl group, n-hexyl group, isohexyl group and cyclohexyl group.

C _1-6 alkoxy represents a monovalent group in which the above C _1-6 alkyl is bonded to oxygen. Here, specific examples of the alkoxy group having 1 to 6 carbon atoms include a methoxy group, a trifluoromethoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group and an s-butoxy group. , T-butoxy group, n-pentoxy group, isopentoxy group, neopentoxy group, t-pentoxy group, 1,1-dimethylpropoxy group, n-hexoxy group, isohexoxy group, cyclohexoxy group and the like.

Ar _6-10 aryl represents a substituent obtained by removing one hydrogen atom from the aromatic ring of an aromatic hydrocarbon having 6 to 10 carbon atoms, and is substituted with, for example, at least one of a phenyl group and a 2-position to a 6-position. A phenyl group having a group, a 1-naphthyl group, a 1-naphthyl group having a substituent at at least one of the 2-position to 8-position, a 2-naphthyl group and a substituent at at least one of the 1-position and 3-position to 8-position. 2-naphthyl group having is mentioned. Substituents on the aromatic ring of Ar _6-10 aryl include fluoro groups, chloro groups, bromo groups and iodo groups, which are halogen atoms, as well as methyl groups, trifluoromethyl groups, ethyl groups, n-propyl groups and isopropyl. Examples thereof include a group, an n-butyl group, an isobutyl group, an s-butyl group and a t-butyl group. Specific examples of Ar _6-10 aryl include phenyl group, o-fluorophenyl group, m-fluorophenyl group, p-fluorophenyl group, o-trifluoromethylphenyl group, m-trifluoromethylphenyl group and p-. Trifluoromethylphenyl group, o-chlorophenyl group, m-chlorophenyl group, p-chlorophenyl group, o-bromophenyl group, m-bromophenyl group, p-bromophenyl group, o-tolyl group, m-tolyl group, p -Trill group, o-ethylphenyl group, m-ethylphenyl group, p-ethylphenyl group, o- (t-butyl) phenyl group, m- (t-butyl) phenyl group, p- (t-butyl) phenyl Group, 3,5-dimethylphenyl group, 3,5-bistrifluoromethylphenyl group, 3,4,5-trifluorophenyl group, o-methoxyphenyl group, m-methoxyphenyl group, p-methoxyphenyl group, 1 -Naphenyl group, 2-naphthyl group, 2-fluoronaphthalene-1-yl group, 3-fluoronaphthalene-1-yl group, 4-fluoronaphthalene-1-yl group, 5-fluoronaphthalene-1-yl group, 6 -Fluoronaphthalene-1-yl group, 7-fluoronaphthalene-1-yl group, 8-fluoronaphthalene-1-yl group, 2-chloronaphthalene-1-yl group, 3-chloronaphthalene-1-yl group, 4 -Chloronaphthalene-1-yl group, 5-chloronaphthalene-1-yl group, 6-chloronaphthalene-1-yl group, 7-chloronaphthalene-1-yl group, 8-chloronaphthalene-1-yl group, 2 -Bromonaphthalene-1-yl group, 3-bromonaphthalene-1-yl group, 4-bromonaphthalene-1-yl group, 5-bromonaphthalene-1-yl group, 6-bromonaphthalene-1-yl group, 7 -Bromonaphthalene-1-yl group, 8-bromonaphthalen-1-yl group, 2-iodonaphthalene-1-yl group, 3-iodonaphthalene-1-yl group, 4-iodonaphthalene-1-yl group, 5 -Iodonaphthalen-1-yl group, 6-iodonaphthalene-1-yl group, 7-iodonaphthalene-1-yl group, 8-iodonaphthalene-1-yl group, 2-methylnaphthalen-1-yl group, 3 -Methylnaphthalen-1-yl group, 4-methylnaphthalen-1-yl group, 5-methylnaphthalen-1-yl group, 6-methylnaphthalen-1-yl group, 7-methylnaphthalen-1-yl group, 8 -Methylnaphthalen-1-yl group, 2-ethylnaphthalen-1-yl Group, 3-ethylnaphthalen-1-yl group, 4-ethylnaphthalen-1-yl group, 5-ethylnaphthalen-1-yl group, 6-ethylnaphthalen-1-yl group, 7-ethylnaphthalen-1-yl group Group, 8-ethylnaphthalen-1-yl group, 2-n-propylnaphthalene-1-yl group, 3-n-propylnaphthalene-1-yl group, 4-n-propylnaphthalen-1-yl group, 5- n-propylnaphthalen-1-yl group, 6-n-propylnaphthalen-1-yl group, 7-n-propylnaphthalen-1-yl group, 8-n-propylnaphthalen-1-yl group, 2-i- Propylnaphthalen-1-yl group, 3-i-propylnaphthalen-1-yl group, 4-i-propylnaphthalen-1-yl group, 5-i-propylnaphthalen-1-yl group, 6-i-propylnaphthalene -1-yl group, 7-i-propylnaphthalene-1-yl group, 8-i-propylnaphthalene-1-yl group, 2-c-propylnaphthalene-1-yl group, 3-c-propylnaphthalene-1 -Il group, 4-c-propylnaphthalene-1-yl group, 5-c-propylnaphthalen-1-yl group, 6-c-propylnaphthalen-1-yl group, 7-c-propylnaphthalene-1-yl group Group, 8-c-propylnaphthalene-1-yl group, 2-n-butylnaphthalene-1-yl group, 3-n-butylnaphthalene-1-yl group, 4-n-butylnaphthalene-1-yl group, 5-n-butylnaphthalene-1-yl group, 6-n-butylnaphthalene-1-yl group, 7-n-butylnaphthalene-1-yl group, 8-n-butylnaphthalene-1-yl group, 1- Fluoronaphthalene-2-yl group, 3-fluoronaphthalen-2-yl group, 4-fluoronaphthalene-2-yl group, 5-fluoronaphthalen-2-yl group, 6-fluoronaphthalene-2-yl group, 7- Fluoronaphthalene-2-yl group, 8-fluoronaphthalen-2-yl group, 1-chloronaphthalene-2-yl group, 3-chloronaphthalen-2-yl group, 4-chloronaphthalene-2-yl group, 5- Chloronaphthalene-2-yl group, 6-chloronaphthalen-2-yl group, 7-chloronaphthalen-2-yl group, 8-chloronaphthalen-2-yl group, 1-bromonaphthalene-2-yl group, 3- Bromonaphthalene-2-yl group, 4-bromonaphthalen-2-yl group, 5-bromonaphthalene-2-yl group, 6-bromonaphthalen-2-yl group, 7-bromonaphthalene-2-yl Il group, 8-bromonaphthalen-2-yl group, 1-iodonaphthalene-2-yl group, 3-iodonaphthalene-2-yl group, 4-iodonaphthalene-2-yl group, 5-iodonaphthalene-2- Ill Group, 6-Idonaphthalen-2-yl Group, 7-Idonaphthalen-2-yl Group, 8-Iodonaphthalen-2-yl Group, 1-Methylnaphthalen-2-yl Group, 3-Methylnaphthalen-2- Il group, 4-methylnaphthalen-2-yl group, 5-methylnaphthalen-2-yl group, 6-methylnaphthalen-2-yl group, 7-methylnaphthalen-2-yl group, 8-methylnaphthalen-2- Il group, 1-ethylnaphthalen-2-yl group, 3-ethylnaphthalen-2-yl group, 4-ethylnaphthalen-2-yl group, 5-ethylnaphthalen-2-yl group, 6-ethylnaphthalen-2- Il group, 7-ethylnaphthalen-2-yl group, 8-ethylnaphthalen-2-yl group, 1-n-propylnaphthalen-2-yl group, 3-n-propylnaphthalen-2-yl group, 4-n -Propylnaphthalen-2-yl group, 5-n-propylnaphthalen-2-yl group, 6-n-propylnaphthalen-2-yl group, 7-n-propylnaphthalen-2-yl group, 8-n-propyl Naphthalene-2-yl group, 1-i-propylnaphthalen-2-yl group, 3-i-propylnaphthalene-2-yl group, 4-i-propylnaphthalen-2-yl group, 5-i-propylnaphthalene- 2-yl group, 6-i-propylnaphthalen-2-yl group, 7-i-propylnaphthalene-2-yl group, 8-i-propylnaphthalen-2-yl group, 1-c-propylnaphthalen-2- Il group, 3-c-propylnaphthalen-2-yl group, 4-c-propylnaphthalen-2-yl group, 5-c-propylnaphthalen-2-yl group, 6-c-propylnaphthalene-2-yl group , 7-c-Propylnaphthalen-2-yl group, 8-c-propylnaphthalen-2-yl group, 1-n-butylnaphthalen-2-yl group, 3-n-butylnaphthalene-2-yl group, 4 -N-butylnaphthalen-2-yl group, 5-n-butylnaphthalene-2-yl group, 6-n-butylnaphthalen-2-yl group, 7-n-butylnaphthalen-2-yl group and 8-n -Butylnaphthalene-2-yl group and the like can be mentioned.

In the electron attractant of the present embodiment, examples of the anion which is the counter ion of the quaternary ammonium group include hexafluorophosphate ion, hexachloroantimonate ion, trifluoromethanesulfonate ion, tetrafluoroborate ion, and phosphate. Ions, ammonium ions, chlorides, bromides, iodides, hydroxydos and the like can be mentioned.

In the electron attracting group of the present embodiment, the ammonium cation of the quaternary ammonium group includes, for example, -NH ₃ cation, -N mono (C _1-12 alkyl) H ₂ cation, and -N di (C _1-12 ). Alkyl) H cation, -N tri (C _1-12 alkyl) cation, -N mono (Ar _6-10 aryl) H ₂ cation, -N di (Ar _6-10 aryl) H cation, -N tri (Ar ₆ ) _-10 aryl) cations, -N (C _1-12 alkyl) (Ar _6-10 aryl) H cations, -N di (C _1-12 alkyl) mono (Ar _6-10 aryl) cations, or -N mono (Ar 6-10 aryl) cations. C _1-12 alkyl) di (Ar _6-10 aryl) cations are mentioned, where the "-" above represents a bond.

In the electron-withdrawing group of the present embodiment, the above-mentioned C _1-12 alkyl in the ammonium cation of the quaternary ammonium group independently represents an alkyl group having 1 to 12 carbon atoms. Here, examples of the alkyl group having 1 to 12 carbon atoms include a methyl group, a trifluoromethyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, and t. -Butyl group, n-pentyl group, isopentyl group, neopentyl group, t-pentyl group, 1,1-dimethylpropyl group, n-hexyl group, isohexyl group, cyclohexyl group, 1-methylhexyl group, n-heptyl group, Isoheptyl group, 1,1,3,3-tetramethylbutyl group, 1-methylheptyl group, 3-methylheptyl group, n-octyl group, 2-ethylhexyl group, 1,1,3-trimethylhexyl group, 1, Examples thereof include 1,3,3-tetramethylpentyl group, n-nonyl group, n-decyl group, n-undecyl group, 1-methylundecyl group, n-dodecyl group, and methyl group, trifluoromethyl group, and the like. Ethyl group, n-propyl group, isopropyl group, n-butyl group, t-butyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group , N-Undecyl group, n-dodecyl group are preferable.

In the electron attracting group of the present embodiment, the above-mentioned Ar _6-10 aryl in the ammonium cation of the quaternary ammonium group includes the same as the above-mentioned description, and a phenyl group, an o-trifluoromethylphenyl group, and the like. Preferably, m-trifluoromethylphenyl group, p-trifluoromethylphenyl group, 3,5-bistrifluoromethylphenyl group, 3,4,5-trifluorophenyl group, 1-naphthyl group and 2-naphthyl group.

In the electron attracting group of the present embodiment, as the ammonium cation of the quaternary ammonium group, for example, -NH ₃ cation, -N trimethyl cation, -N triethyl cation, and -N dimethyl phenyl cation are preferable.

In the electron-withdrawing group of the present embodiment, examples of the perfluoroalkyl group include −CF ₂ CF ₃ , − (CF ₂ ) ₂ CF ₃ , − (CF ₂ ) ₃ CF ₃ , − (CF ₂ ) ₄ CF. ₃ ,-(CF ₂ ) ₅ CF ₃ ,-(CF ₂ ) ₆ CF ₃ ,-(CF ₂ ) ₇ CF ₃ ,-(CF ₂ ) ₈ CF ₃ ,-(CF ₂ ) ₉ CF ₃ ,-(CF 2) ₂ ) ₁₀ CF ₃ , − (CF ₂ ) ₁₁ CF ₃ and the like can be mentioned, with − (CF ₂ ) ₉ CF ₃ and − (CF ₂ ) ₁₁ CF ₃ being preferred.

In the electron attracting group of the present embodiment, the C _1-6 alkyl in the carbonyl (C _1-6 alkyl) group may be the same as described above, and specific examples of the carbonyl (C _1-6 alkyl) group include the same as described above. Is preferably a carbonylmethyl group, a carbonyltrifluoromethyl group, a carbonylethyl group, a carbonyl n-propyl group, a carbonylisopropyl group, a carbonyl n-butyl group, a carbonylisobutyl group, a carbonyls-butyl group, or a carbonyl t-butyl group.

In the electron-withdrawing group of the present embodiment, the C _1-6 alkoxy in the carbonyl (C _1-6 alkoxy) group is the same as described above, and specific examples of the carbonyl (C _1-6 alkoxy) group include the same as described above. Is a carbonyl methoxy group, a carbonyl trifluoromethoxy group, a carbonyl ethoxy group, a carbonyl n-propoxy group, a carbonyl isopropoxy group, a carbonyl n-butoxy group, a carbonyl isobutoxy group, a carbonyl s-butoxy group, and a carbonyl t-butoxy group. preferable.

In the electron-withdrawing group of the present embodiment, the Ar _6-10 aryl in the carbonyl (Ar _6-10 aryl) group may be the same as described above, and as a specific example of the carbonyl (Ar _6-10 aryl) group. Is a carbonyl phenyl group, a carbonyl o-trifluoromethyl phenyl group, a carbonyl m-trifluoromethyl phenyl group, a carbonyl p-trifluoromethyl phenyl group, a carbonyl 3,5-bistrifluoromethyl phenyl group, a carbonyl 3, 4, 5 -Trifluorophenyl group, carbonyl1-naphthyl group and carbonyl2-naphthyl group are preferred.

In the electron attracting group of the present embodiment, the C _1-6 alkyl in the carbonyl (C _1-6 alkyl) amino group may be the same as described above, and the specific of the carbonyl (C _1-6 alkyl) amino group may be mentioned. Examples include carbonylmethylamino group, carbonyltrifluoromethylamino group, carbonylethylamino group, carbonyl n-propylamino group, carbonylisopropylamino group, carbonyl n-butylamino group, carbonylisobutylamino group, carbonyls-butylamino. A group, a carbonyl t-butylamino group, is preferable.

In the electron attracting group of the present embodiment, the C _1-6 alkyl in the carbonyl di (C _1-6 alkyl) amino group includes the same as described above, and the carbonyl di (C _1-6 alkyl) amino group is mentioned. Specific examples of the above include a carbonyldimethylamino group, a carbonylbis (trifluoromethyl) amino group, a carbonyldiethylamino group, a carbonyldi n-propylamino group, a carbonyldiisopropylamino group, a carbonyldin-butylamino group, and a carbonyldiisobutylamino group. , Carbonyldi s-butylamino group, carbonyldi t-butylamino group are preferred.

In the electron attracting group of the present embodiment, the C _1-6 alkyl in the sulfonyl (C _1-6 alkyl) amino group includes the same as the above description, and the specific of the sulfonyl (C _1-6 alkyl) amino group. Examples include sulfonylmethylamino group, sulfonyltrifluoromethylamino group, sulfonylethylamino group, sulfonyln-propylamino group, sulfonylisopropylamino group, sulfonyln-butylamino group, sulfonylisobutylamino group, sulfonyls-butylamino. Groups, sulfonylt-butylamino groups are preferred.

In the electron attracting group of the present embodiment, the C _1-6 alkyl in the sulfonyl di (C _1-6 alkyl) amino group includes the same as described above, and the sulfonyl di (C _1-6 alkyl) amino group can be mentioned. Specific examples of the above include a sulfonyldimethylamino group, a sulfonylbis (trifluoromethyl) amino group, a sulfonyldiethylamino group, a sulfonyldin-propylamino group, a sulfonyldiisopropylamino group, a sulfonyldin-butylamino group, and a sulfonyldiisobutylamino group. , Ssulfonyldi s-butylamino group, sulfonyldi t-butylamino group are preferred.

In the electron attracting group of the present embodiment, the Ar _6-10 aryl group includes the same as described above, and specific examples of the Ar _6-10 aryl group include a phenyl group and an o-trifluoromethylphenyl group. , M-trifluoromethylphenyl group, p-trifluoromethylphenyl group, 3,5-bistrifluoromethylphenyl group, 3,4,5-trifluorophenyl group, 1-naphthyl group and 2-naphthyl group are preferable.

In the method for producing ammonia of the present embodiment, more preferable electron attracting groups are -NH ₃ cation, -N trimethyl cation, -N triethyl cation, -N dimethylphenyl cation,-(CF ₂ ) ₉ CF ₃ and-(. CF ₂ ) ₁₁ CF ₃ , a fluorine atom, a chlorine atom and a trifluoromethyl group, and particularly preferable electron-electron attracting groups are a fluorine atom, a chlorine atom and a trifluoromethyl group.

In the method for producing ammonia of the present embodiment, examples of the reducing agent include a halogenated product (II) of a lanthanoid-based metal, and examples of the lanthanoid-based metal include La, Ce, Pr, Nd, Pm, Sm, Eu, and Gd. Examples thereof include Tb, Dy, Ho, Er, Tm, Yb and Lu, of which Sm is preferable, and examples of the halogen include chlorine, bromine and iodine, of which iodine is preferable.
Therefore, as the halide (II) of the lanthanoid-based metal, samarium halide (II) is preferable, and samarium iodide (II) is more preferable.

In the method for producing ammonia of the present embodiment, examples of the proton source include alcohol and water. As the alcohol to be used, glycol may be used, or ROH (R may be a chain, cyclic or branched alkyl group having 1 to 6 carbon atoms in which a hydrogen atom may be replaced with a fluorine atom, or an alkyl. A phenyl group which may have a group) may be used.
Examples of the glycol include ethylene glycol, propylene glycol and diethylene glycol.
Examples of the ROH include methanol, ethanol, propanol, isopropanol, n-butyl alcohol, s-butyl alcohol, isobutyl alcohol, t-butyl alcohol and the like as chain or branched alkyl alcohols, and examples of the cyclic alcohol alcohol include cyclic alcohols. Examples thereof include cyclopropanol, cyclopentanol, cyclohexanol and the like, and examples of the alcohol containing a fluorine atom include trifluoroethyl alcohol and tetrafluoroethyl alcohol, and a phenyl group which may have an alkyl group. Examples of the alcohol contained include phenol, cresol, xylenol and the like.

In the method for producing ammonia of the present embodiment, preferable proton sources are water and ethylene glycol, and water is more preferable.

In the method for producing ammonia of the present embodiment, when producing ammonia from nitrogen molecules, it may be carried out in a solvent. The solvent is not particularly limited, and examples thereof include a cyclic ether solvent, a chain ether solvent, a nitrile solvent, a hydrocarbon solvent, and a halogen-containing hydrocarbon solvent. Examples of the cyclic ether solvent include tetrahydrofuran, 1,4-dioxane and the like. Examples of the chain ether solvent include diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, cyclopentyl methyl ether and the like. Examples of the nitrile-based solvent include acetonitrile, propionitrile and the like. Examples of the hydrocarbon solvent include aromatic hydrocarbons such as toluene and o-xylene, and saturated hydrocarbons such as hexane, heptane and petroleum ether. Examples of the halogen-containing hydrocarbon solvent include dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,1-trichloroethane, trichlorethylene, tetrachlorethylene and the like. In the method for producing ammonia of the present embodiment, a preferred solvent is tetrahydrofuran. Further, in the method for producing ammonia of the present embodiment, dichloromethane is a preferable solvent when the molybdenum complex used as a catalyst is added.

The yield of produced ammonia can be measured by a known method. Ammonia in an aqueous sulfuric acid solution can be quantified using, for example, a known Indophenol method (Analytical Chemistry, 1967, Vol. 39, pp. 971-974).

In the present specification, a pincer-type ligand having three bonding sites of two phosphines and carbene carbon of a benzimidazole ring in a molecule derived from a molybdenum complex is a ligand represented by the following formula (4). show.

R ¹ , R ² , R ³ and R ⁴ in the equation are the same as those described in the equation (1).

A selenium atom is bonded to the three bonding sites of a pincer-type ligand having three bonding sites of two phosphines and a carbene carbon of a benzimidazole ring in a molecule derived from the molybdenum complex represented by the formula (2). Selenium adduct

In, R ¹ , R ² , R ³ and R ⁴ in the formula are the same as those described in the formula (1). In the present specification, selenium in which a selenium atom is bonded to the three bonding sites of a pincer-type ligand having three bonding sites of two phosphines and carbene carbon of a benzoimidazole ring in a molecule derived from a molybdenum complex. The adduct is also referred to as a selenium adduct of a pincer-type ligand.

As shown in Examples described later, in the selenium adduct of the pincer-type ligand represented by the formula (2), the chemical shift value and catalyst of ⁷⁷ SeNMR of selenium on the carbene carbon of the benzimidazole ring in the structure. There is a correlation between rotation frequency (TOF). The selenium of the pincer-type ligand such that the chemical shift value of ⁷⁷ SeNMR of the selenium atom bonded to the carbene carbon of the benzoimidazole ring in the structure of the selenium adduct of the pincer-type ligand shows a value of a magnetic field lower than 170 ppm. A molybdenum complex having a pincer-type ligand corresponding to an adduct is a molybdenum complex having a TOF of more than 200 (1 / min).

Estimating the catalytic activity of the complex from the structure and electronic state of the complex is very useful because it saves materials and time when verifying the catalytic activity.

However, in the case of the molybdenum complex described in the present invention, it is not very useful to evaluate the complex itself because the preparation of the complex is complicated and the handling of the complex requires a special environment and technique. I can not say.

On the other hand, the selenium adduct of the pincer-type ligand can be prepared as a very stable compound and is easy to handle. Further, compared to molybdenum, ⁷⁷ Se has better sensitivity to NMR and is superior in that the electronic state of the molybdenum complex can be quantitatively estimated.

It is needless to say that the present invention is not limited to the above-described embodiment and can be carried out in various embodiments as long as it belongs to the technical scope of the present invention.

Hereinafter, examples of the present invention will be described. The following examples do not limit the present invention in any way.

[Example 1]
Molybdenum complex (1a) as a catalyst

Was used to produce ammonia from nitrogen molecules. A 0.05 mmol / L dichloromethane solution of the molybdenum complex (1a) was prepared in a Schlenk reaction vessel. Under normal pressure nitrogen atmosphere, a dichloromethane solution (500 μL, 25 nmol) of the molybdenum complex (1a) as a catalyst and diiodobis (tetrahydrofuran) samarium (II) (397.6 mg, 0.725 mmol) as a reducing agent were placed in a reaction vessel. Add a solution of tetrahydrofuran (5 mL) to the number of moles of the molybdenum complex (29000 eq) and then a solution of water (13.1 mg, 0.725 mmol, 29000 eq to the number of moles of the molybdenum complex) as a proton source. (1 mL) was added, and the mixture was stirred at room temperature of 20 ° C to 25 ° C for 30 minutes. Then, in order to stop the reaction, an aqueous potassium hydroxide solution (30% by mass, 5 mL) was added to the reaction vessel. Next, in order to quantify the amount of ammonia generated in this reaction, the reaction vessel was distilled under reduced pressure and the distillate was recovered with a sulfuric acid aqueous solution (0.5 M, 10 mL). The amount of ammonia in the aqueous sulfuric acid solution was determined by the indophenol method. As a result, 8000 equivalents of ammonia was produced per catalyst (molybdenum complex). The TOF, which is the catalyst rotation frequency, was 267 (1 / min).

[Examples 2 to 5]
In Examples 2 to 5, the molybdenum complex (1a) as a catalyst is changed, the molybdenum complex (1c) is changed in Example 2, the molybdenum complex (1d) is used in Example 3, and the molybdenum complex (1d) is used in Example 4. 1e), molybdenum complex (1f) in Example 5

The experimental operations other than those used were the same as in Example 1 to produce ammonia from nitrogen molecules. Table 1 shows the amount of ammonia per molybdenum complex used as a catalyst and the results of TOF.

[Synthesis Example 1]
The synthetic route of the molybdenum complex (1a) used as a catalyst will be described below.

Synthesis of compound (2a)

The synthesis of compound (2a) is shown below. Di-tert-butylphosphine (2.25 g, 14.9 mmol) and paraformaldehyde (450 mg, 15.0 mmol) were added to the reaction vessel, and the mixture was stirred at 60 ° C. for 16 hours under a nitrogen atmosphere. Then, dichloroethane (150 mL) and 1,2-diamino-4,5-dichlorobenzene (1.07 g, 6.02 mmol) represented by the formula (5a) are added to the reaction vessel at 60 ° C. under a nitrogen atmosphere. The mixture was stirred for 24 hours. Next, selenium (1.26 g, 16.0 mmol) was added, and the mixture was stirred at room temperature of 20 ° C to 25 ° C under a nitrogen atmosphere for 24 hours. The reaction was concentrated and the resulting solid was separated by silica gel column chromatography (dichloromethane: hexane = 1/1). The recovered fraction was concentrated and dried under vacuum to isolate compound (2a) as a white solid in 2.58 g (3.97 mmol, 66% yield).
Melting point: 195.4 ° C to 196.5 ° C
¹ H NNR (CDCl ₃ ): δ6.66 (s, 2H), 4.85 (br, 2H), 3.30 (d, J = 7.2Hz, 4H), 1.42 (d, J = 15) .2Hz, 36H).
¹³ C NNR (CDCl ₃ ): δ137.2 (s), 121.7 (s), 112.4 (s), 37.1 (d, J = 32.6Hz), 34.6 (d, J = 40.3Hz), 28.0 (s).
³¹ P NMR (CDCl ₃ ): δ79.7 (s with Se satellites, J = 706.1 Hz).

Synthesis of compound (3a)

The synthesis of compound (3a) is shown below. After adding compound (2a) (2.48 g, 3.81 mmol), triethyl orthoformate (10 mL) and ammonium hexafluorophosphate (629 mg, 3.86 mmol) to the reaction vessel, the mixture was added to the reaction vessel at 120 ° C. for 3 hours under air. Stirred. The mixture was then concentrated, washed twice with a mixed solution of dichloromethane (4 mL) and diethyl ether (8 mL), and further washed once with diethyl ether (10 mL). The reaction mixture was dried under vacuum and the compound (3a) was isolated as a white solid in 2.49 g (3.09 mmol, 81% yield).
¹ H NNR (Acetone-d ₆ ): δ10.69 (s, 1H), 8.69 (s, 2H), 5.57 (d, J = 2.8Hz, 4H), 1.50 (d, J) = 16.4Hz, 36H).
¹³ C NNR (Acetone-d ₆ ): δ144.6 (s), 132.1 (s), 131.7 (s), 117.0 (s), 40.8 (d, J = 26.8Hz) , 39.2 (d, J = 30.7Hz), 28.0 (s).
³¹ P NMR (Acetone-d ₆ ): δ-143.9 (seq, J = 708.3 Hz), 83.1 (s with Se satellites, J = 732.3 Hz).

Synthesis of compound (4a)

The synthesis of compound (4a) is shown below. After adding compound (3a) (2.58 g, 3.20 mmol), tris (dimethylamino) phosphine (1.5 mL) and dichloromethane (40 mL) to the reaction vessel, the temperature is 20 ° C to 25 at room temperature under a nitrogen atmosphere. The mixture was stirred at ° C. for 4 hours. The mixture was then concentrated, washed 3 times with toluene (7 mL) and dried under vacuum to give compound (4a) 1.83 g (2.81 mmol, 88% yield) as a white solid. ).
¹ H NNR (THF-d ₈ ): δ9.87 (s, 1H), 8.42 (s, 2H), 4.81 (s, 4H), 1.23 (d, J = 12.0Hz, 36H) ).
¹³ C NNR (THF-d ₈ ): δ145.8 (t, J = 12.0 Hz), 132.5 (s), 131.7 (s), 117.1 (d, J = 6.7 Hz), 43.6 (d, J = 28.7 Hz), 32.8 (d, J = 20.1 Hz), 29.5 (d, J = 13.5 Hz).
³¹ P NMR (THF-d ₈ ): δ-146.0 (seq, J = 711.9 Hz), 24.7 (s).

Synthesis of molybdenum complex (1a)

The synthesis of the molybdenum complex (1a) is shown below. After adding compound (4a) (1.30 g, 2.00 mmol), potassium bis (trimethylsilyl) amide (561 mg, 2.81 mmol) and toluene (45 mL) to the reaction vessel, the temperature is 20 ° C. to room temperature under an argon atmosphere. The mixture was stirred at 25 ° C. for 1 hour. Next, the reaction mixture was filtered through Celite, trichlorotris (tetrahydrofuran) molybdenum (III) (756 mg, 1.81 mmol) was added, and the mixture was stirred at 80 ° C. for 26 hours. Further, the reaction mixture was concentrated to 5 mL, filtered through a filter paper, and then dried under vacuum. The obtained solid was washed twice with toluene (5 mL), and then the solution dissolved in dichloromethane (20 mL) was filtered through Celite. Hexane (30 mL) was gently added to the filtered filtrate and then allowed to stand for 5 days to generate crystals. The supernatant liquid that produced the crystals was removed, washed with hexane (5 mL) three times, and then dried under vacuum to turn the molybdenum complex (1a) into brown crystals in 166.3 mg (0.24 mmol, 13% yield). ).
Anal.
Calcd. for C ₂₅ H ₄₂ C _l5 MoN ₂ P ₂ :
C, 42.55; H, 6.00; N, 3.97,
Found:
C, 41.66; H, 5.68; N, 3.20.

[Synthesis Example 2 to Synthesis Example 5]
The synthesis of the molybdenum complexes (1c) to (1f) can be synthesized with reference to the description of the non-patent paper Nature 2019, Vol. 568, pp. 536-540 and the description of [Synthesis Example 1] of the present specification.

Regarding the synthesis of each molybdenum complex, instead of 1,2-diamino-4,5-dichlorobenzene represented by the formula (5a) used in [Synthesis Example 1],
The synthesis of the molybdenum complex (1c) was carried out using 1,2-diamino-4,5-dimethylbenzene.
The synthesis of the molybdenum complex (1d) was carried out using 1,2-diaminobenzene.
The synthesis of the molybdenum complex (1e) was carried out using 1,2-diamino-4,5-difluorobenzene.
The synthesis of the molybdenum complex (1f) was carried out using 1,2-diamino-4-trifluoromethylbenzene.
Can be synthesized.

[Synthesis Example 6]
The synthetic route of the selenium adduct of the pincer-type ligand represented by the formula (6a) will be described below.

The synthesis of the selenium adduct of the pincer-type ligand represented by the formula (6a) is shown below. After adding compound (3a) (80.7 mg, 0.10 mmol), selenium (39.5 mg, 0.50 mmol), sodium bis (trimethylsilyl) amide (560 mg, 2.81 mmol) and toluene (5 mL) to the reaction vessel. The mixture was stirred at room temperature of 20 ° C. to 25 ° C. for 18 hours under an argon atmosphere. Next, the solvent of the reaction mixture was distilled off, dichloromethane was added to the reaction vessel, and the filtrate filtered through Celite was dried under vacuum. The obtained solid was washed twice with hexane (5 mL) and then dried under vacuum to obtain 56.3 mg (0) of the selenium adduct of the pincer-type ligand represented by the formula (6a) as white crystals. Isolated at 0.76 mmol (76% yield).
Melting point: 226.3 ° C to 227.8 ° C
¹ H NNR (THF-d ₈ ): δ8.84 (br, 2H), 5.68 (br, 4H), 1.47 (d, J = 15.2 Hz, 36H).
¹³ C NNR (THF-d ₈ ): δ173.2 (s), 134.2 (s), 127.3 (s), 116.9 (s), 47.9 (d, J = 30.8Hz) , 39.5 (d, J = 29.7 Hz), 28.5 (s).
³¹ P NMR (THF-d ₈ ): δ71.6 (s with Se satellites, J = 732.8 Hz).
⁷⁷ Se NMR (THF-d ₈ ): δ177.3 (s), 383.2 (d, J = 732.8 Hz).

[Synthesis Example 7]
The synthetic route of the selenium adduct of the pincer-type ligand represented by the formula (6b) will be described below.

The synthesis of the selenium adduct of the pincer-type ligand represented by the formula (6b) is shown below. After adding compound (3b) (80.7 mg, 0.10 mmol), selenium (39.5 mg, 0.50 mmol), sodium bis (trimethylsilyl) amide (560 mg, 2.81 mmol) and toluene (5 mL) to the reaction vessel. The mixture was stirred at room temperature of 20 ° C. to 25 ° C. for 18 hours under an argon atmosphere. Next, the solvent of the reaction mixture was distilled off, dichloromethane was added to the reaction vessel, and the filtrate filtered through Celite was dried under vacuum. The obtained solid was washed twice with hexane (5 mL) and then dried under vacuum to obtain 56.3 mg (0) of the selenium adduct of the pincer-type ligand represented by the formula (6b) as white crystals. Isolated at 0.76 mmol (76% yield).
Melting point: Decomposes at 170 ° C
¹ H NNR (THF-d ₈ ): δ9.11 (s, 2H), 5.72 (br, 4H), 1.49 (d, J = 14.8 Hz, 36H).
¹³ C NNR (THF-d ₈ ): δ175.0 (s), 136.4 (s), 124.1 (q, J = 282.3Hz), 121.9-122.2 (m), 116. 3 (s), 46.6 (d, J = 30.7 Hz), 39.5 (d, J = 30.7 Hz), 28.4 (s).
¹⁹ F NNR (THF-d ₈ ): δ-60.8 (s).
³¹ P NMR (THF-d ₈ ): δ72.8 (s with Se satellites, J = 732.8 Hz).
⁷⁷ Se NMR (THF-d ₈ ): δ196.9 (s), -390.9 (d, J = 732.8 Hz).
HRMS (FAB)
Calcd. for C ₂₇ H ₄₂ N ₂ F ₆ P ₂ Se ₃ [M] ⁺ : 810.0223.
Found: 810.199.
[Synthesis Example 8 to Synthesis Example 11]
The selenium adduct of the pincer-type ligand represented by the formulas (6c) to (6f) can be synthesized with reference to the above description of [Synthesis Example 1] and [Synthesis Example 6].

Instead of 1,2-diamino-4,5-dichlorobenzene represented by the formula (5a) used in [Synthesis Example 1],
The synthesis of the selenium adduct (6c) was carried out using 1,2-diamino-4,5-dimethylbenzene.
The synthesis of the selenium adduct (6d) was carried out using 1,2-diaminobenzene.
The synthesis of the selenium adduct (6e) was carried out using 1,2-diamino-4,5-difluorobenzene.
The synthesis of the selenium adduct (6f) was carried out using 1,2-diamino-4-trifluoromethylbenzene.
The compounds represented by the formulas (3c) to (3f) can be synthesized with reference to the description of [Synthesis Example 1], and the formulas (6c) to 6c can be synthesized with reference to the description of [Synthesis Example 6]. A selenium adduct of a pincer-type ligand represented by the formula (6f) can be synthesized.

A selenium adduct of a pincer-type ligand represented by the formula (6c)

Melting point: 239.5 ° C to 240.7 ° C
¹ H NNR (THF-d ₈ ): δ8.44 (s, 2H), 5.78 (br, 4H), 2.33 (s, 6H), 1.46 (d, J = 15.6Hz, 36H) ).
¹³ C NNR (THF-d ₈ ): δ170.3 (s), 133.4 (s), 132.6 (s), 116.0 (s), 49.2 (d, J = 31.7Hz) , 39.4 (d, J = 30.8Hz), 28.7 (s), 20.0 (s).
³¹ P NMR (THF-d ₈ ): δ71.2. (S with Se satellites, J = 732.6 Hz).
⁷⁷ Se NMR (THF-d ₈ ): δ135.2 (s), -381.0 (d, J = 732.6 Hz).
HRMS (FAB)
Calcd. for C ₂₇ H ₄₈ N ₂ P ₂ Se ₃ [M] ⁺ : 702.0788.
Found: 702.0809.

A selenium adduct of a pincer-type ligand represented by the formula (6d)

Melting point: 230.5 ° C to 232.0 ° C
¹ H NNR (THF-d ₈ ): δ8.60-8.56 (m, 2H), 7.19-7.22 (m, 2H), 5.72 (br, 4H), 1.47 (d) , J = 15.2 Hz, 36H).
¹³ C NNR (THF-d ₈ ): δ171.6 (s), 135.0 (s), 125.6 (s), 115.6 (s), 48.8 (d, J = 31.6Hz) , 39.4 (d, J = 30.7Hz), 28.6 (s).
³¹ P NMR (THF-d ₈ ): δ71.6 (s with Se satellites, J = 732.7 Hz).
⁷⁷ Se NMR (THF-d ₈ ): δ147.1 (s), -384.5 (d, J = 732.7 Hz).
HRMS (FAB)
Calcd. for C ₂₅ H ₄₄ N ₂ P ₂ Se ₃ [M] ⁺ : 674.0475.
Found: 674.0488.

A selenium adduct of a pincer-type ligand represented by the formula (6e)

Melting point: 239.7 ° C to 240.4 ° C
¹ H NNR (THF-d ₈ ): δ8.65 (t, 2H), 5.68 (br, 4H), 1.47 (d, J = 15.6Hz, 36H).
¹³ C NNR (THF-d ₈ ): δ171.6 (s), 147.8 (dd, J = 245.3, 16.3 Hz), 130.7 (s), 104.7 (dd, J = 16) .7.7, 9.1 Hz), 48.4 (d, J = 31.6 Hz), 39.5 (d, J = 30.6 Hz), 28.5 (s).
¹⁹ F NNR (THF-d ₈ ): δ-145.5 (d, J = 17.3 Hz).
³¹ P NMR (THF-d ₈ ): δ71.3. (S with Se satellites, J = 727.6 Hz).
⁷⁷ Se NMR (THF-d ₈ ): δ170.2 (s), -382.0 (d, J = 727.6 Hz).
HRMS (FAB)
Calcd. for C ₂₅ H ₄₃ N ₂ F ₂ P ₂ Se ₃ [M] ⁺ : 711.0365.
Found: 711.0358.

A selenium adduct of a pincer-type ligand represented by the formula (6f)

Melting point: 182.0-183.0 ° C
¹ H NNR (THF-d ₈ ): δ8.96 (br, H), 8.68 (br, H), 7.51 (br, H), 5.72 (br, 4H), 1.47- 1.50 (m, 36H).
¹³ C NNR (THF-d ₈ ): δ173.8 (s), 137.3 (s), 134.9 (s), 125.5 (q, J = 271.8Hz), 125.4 (q, J = 32.6Hz), 120.4 (s), 116.2 (s), 113.5 (s), 48.0 (d, J = 31.7Hz), 47.8 (d, J = 31) .7Hz), 39.6 (d, J = 30.7Hz), 28.6 (s).
¹⁹ F NNR (THF-d ₈ ): δ-64.0 (s).
³¹ P NMR (THF-d ₈ ): δ71.9 (s with Se satellites, J = 727.6 Hz).
⁷⁷ Se NMR (THF-d ₈ ): δ174.3 (s), -387.2 (d, J = 732.6 Hz), -387.8 (d, J = 732.7 Hz).
HRMS (FAB)
Calcd. for C ₂₆ H ₄₃ N ₂ F ₃ P ₂ Se ₃ [M] ⁺ : 742.0349.
Found: 742.0351.

The horizontal axis is the chemical shift value of ⁷⁷ SeNMR of selenium on the carbene carbon of the benzoimidazole ring of the selenium adduct of the pincer-type ligand represented by the formulas (6a) to (6f), and each pincer-type ligand. FIG. 1 is a diagram in which the measured value of TOF, which is the amount of substance conversion performed by one molecule of the catalyst of the molybdenum complex represented by the formulas (1a) to (1f) corresponding to the selenium adduct, is plotted on the vertical axis. Shown in.

As shown in FIG. 1, selenium in which a selenium atom is bonded to the three bonding sites of a pincer-type ligand having three bonding sites of two phosphines and carbene carbon of a benzoimidazole ring in a molecule derived from a molybdenum complex. It was confirmed that there is a correlation between the chemical shift value of ⁷⁷ SeNMR of selenium on the carbene carbon of the adduct and the TOF showing the catalytic activity of the molybdenum complex. The pincer-type ligand having an electron-withdrawing group introduced into R ³ and R ⁴ or the molybdenum complex coordinated with the pincer-type ligand having an electron-withdrawing group introduced into R ³ is affected by the electron-withdrawing group. It was confirmed that the catalytic activity of the molybdenum complex was improved. One of the reasons for this is considered to be that the π-acceptability of the benzimidazole ring in the partial structure of the pincer-type ligand becomes stronger. Further, in particular, in the selenium adduct of the pincer-type ligand having an electron-withdrawing group introduced into R3 and ^R4 ^, the chemical shift value of ⁷⁷ SeNMR of selenium on the carbene carbon of the benzimidazole ring is lower than 170 ppm. It can be inferred that the catalytic activity of the molybdenum complex in which an electron-withdrawing group is introduced into R ³ and R ⁴ corresponding to the above is a molybdenum complex having a TOF of more than 200 (1 / min). ..

The present invention can be used as a method for producing ammonia.

Claims

A production method comprising the step of producing ammonia from nitrogen molecules in the presence of a molybdenum complex, a reducing agent and a proton source.
The proton source is alcohol or water.
The molybdenum complex has the formula (1):

(In the formula (1), R 1 and R 2 each independently represent an alkyl group having 3 to 6 carbon atoms.
X is an iodine atom, a bromine atom or a chlorine atom,
R 3 and R 4 each independently represent a hydrogen atom or an electron-withdrawing group. )
It is a molybdenum complex represented by
A formula that is a selenium adduct in which a selenium atom is bonded to the three bonding sites of a pincer-type ligand having three bonding sites of two phosphines and carbene carbon of a benzimidazole ring in a molecule derived from the molybdenum complex. 2):

(In equation (2), R 1 , R 2 , R 3 and R 4 are the same as above.)
In the selenium adduct of the pincer-type ligand represented by, the chemical shift value of 77 SeNMR of selenium on the carbene carbon of the benzimidazole ring is a value in a magnetic field lower than 170 ppm.
Ammonia production method.
A method for evaluating the catalytic performance of a molybdenum complex when producing ammonia from nitrogen molecules in the presence of a molybdenum complex, a reducing agent and a proton source.
The molybdenum complex has the formula (1):

(In the formula (1), R 1 and R 2 each independently represent an alkyl group having 3 to 6 carbon atoms.
X is an iodine atom, a bromine atom or a chlorine atom,
R 3 and R 4 each independently represent a hydrogen atom or an electron-withdrawing group. )
It is a molybdenum complex represented by
A formula that is a selenium adduct in which a selenium atom is bonded to the three bonding sites of a pincer-type ligand having three bonding sites of two phosphines and carbene carbon of a benzimidazole ring in a molecule derived from the molybdenum complex. 2):

(In equation (2), R 1 , R 2 , R 3 and R 4 are the same as above.)
A step of preparing a selenium adduct of a pincer-type ligand represented by the above, and a step of measuring 77 SeNMR of the selenium adduct of the pincer-type ligand.
In a molybdenum complex having a Turnover Frequency of more than 200 (1 / min), depending on whether the chemical shift value of 77 SeNMR of selenium on the carbene carbon of the benzimidazole ring is a value in a magnetic field lower than 170 ppm. A way to determine if there is one.
It is a molybdenum complex represented by the following formula (1).

(In the formula (1), R 1 and R 2 each independently represent an alkyl group having 3 to 6 carbon atoms.
X is an iodine atom, a bromine atom or a chlorine atom,
R 3 and R 4 each independently represent a hydrogen atom or an electron-withdrawing group.
However, when R 3 is a fluorine atom, R 4 is not a fluorine atom, and when R 3 is a hydrogen atom, R 4 is not a trifluoromethyl group. )
A formula that is a selenium adduct in which a selenium atom is bonded to the three bonding sites of a pincer-type ligand having three bonding sites of two phosphines and carbene carbon of a benzimidazole ring in a molecule derived from the molybdenum complex. 2):

(In equation (2), R 1 , R 2 , R 3 and R 4 are the same as above.)
A molybdenum complex in which the chemical shift value of 77 SeNMR of selenium on the carbene carbon of the benzimidazole ring is a value in a magnetic field lower than 170 ppm in the selenium adduct of the pincer type ligand represented by.