Design and Preparation of Molybdenum–Dinitrogen Complexes with Ferrocenyldiphosphine and Pentamethylcyclopentadienyl Moieties as Auxiliary Ligands

Miyazaki, Takamasa; Tanabe, Yasuhiro; Yuki, Masahiro; Miyake, Yoshihiro; Nakajima, Kazunari; Nishibayashi, Yoshiaki

doi:10.1002/chem.201302700

Cited by 37 publications

(18 citation statements)

References 46 publications

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“…5,14 The crystal structure of trans-CpMo(CO)(P Ph N Me P Ph )H also shows four-legged piano-stool coordination geometry and an unusual trans-geometry of the two phosphines. The P−Mo−P bond angle in trans-CpMo(CO)(P Ph N Me P Ph )H is 97.540(17)°, which is larger than the P−Mo−P bond angle of 90.70(4)°in trans-Cp*Mo(depp)Cl 2 (depp = Et 2 PCH 2 CH 2 CH 2 PEt 2 ), 15 80.283(10)°in cis-CpMo(CO)(P Et N Me P Et )H and 80.60(3)°i n trans-Cp*Mo(dppe)Cl 2 , 12 probably due to less ring strain in the larger six-membered Mo-PNP ring than the five-membered Mo-dppe ring. To the best of our knowledge, trans-Mo diphosphine complexes are rare.…”

Section: ■ Results and Discussionmentioning

confidence: 98%

Molybdenum Hydride and Dihydride Complexes Bearing Diphosphine Ligands with a Pendant Amine: Formation of Complexes with Bound Amines

Zhang

Bullock

2015

Inorg. Chem.

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CpMo(CO)(PNP)H complexes (PNP = (R2PCH2)2NMe, R = Et or Ph) were synthesized by displacement of two CO ligands of CpMo(CO)3H by the PNP ligand; these complexes were characterized by IR and variable temperature (1)H and (31)P NMR spectroscopy. CpMo(CO)(PNP)H complexes are formed as mixture of cis- and trans-isomers. The structures of both cis-CpMo(CO)(P(Et)N(Me)P(Et))H and trans-CpMo(CO)(P(Ph)N(Me)P(Ph))H were determined by single crystal X-ray diffraction. Electrochemical oxidation of CpMo(CO)(P(Et)N(Me)P(Et))H and CpMo(CO)(P(Ph)N(Me)P(Ph))H in CH3CN are both irreversible at slow scan rates and quasireversible at higher scan rates, with E1/2 = -0.36 V (vs Cp2Fe(+/0)) for CpMo(CO)(P(Et)N(Me)P(Et))H and E1/2 = -0.18 V for CpMo(CO)(P(Ph)N(Me)P(Ph))H. Hydride abstraction from CpMo(CO)(PNP)H with [Ph3C](+)[A](-) (A = B(C6F5)4 or BAr(F)4; [Ar(F) = 3,5-bis(trifluoromethyl)phenyl]) afforded "tuck-in" [CpMo(CO)(κ(3)-PNP)](+) complexes that feature the amine bound to the metal. Displacement of the κ(3) Mo-N bond by CD3CN gives [CpMo(CO)(PNP)(CD3CN)](+). The kinetics of this reaction were studied by (31)P{(1)H} NMR spectroscopy for [CpMo(CO)(κ(3)-P(Et)N(Me)P(Et))](+), providing the activation parameters ΔH(⧧) = 21.6 ± 2.8 kcal/mol, ΔS(⧧) = -0.3 ± 9.8 cal/(mol K), Ea = 22.1 ± 2.8 kcal/mol. Protonation of CpMo(CO)(P(Et)N(Me)P(Et))H affords the Mo dihydride complex [CpMo(CO)(κ(2)-P(Et)N(Me)P(Et))(H)2](+), which loses H2 to generate [CpMo(CO)(κ(3)-P(Et)N(Me)P(Et))](+) at room temperature. Our results show that the pendant amine has a strong driving force to form stable "tuck-in" [CpMo(CO)(κ(3)-PNP)](+) complexes, and also promotes hydrogen elimination from [CpMo(CO)(PNP)(H)2](+) complexes by formation of a Mo-N dative bond. CpMo(CO)(dppp)H (dppp = 1,3-bis(diphenylphosphino)propane) was studied as a Mo diphosphine analogue without a pendant amine, and the product of protonation of this complex gives [CpMo(CO)(dppp)(H)2](+).

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Section: ■ Results and Discussionmentioning

confidence: 98%

Molybdenum Hydride and Dihydride Complexes Bearing Diphosphine Ligands with a Pendant Amine: Formation of Complexes with Bound Amines

Zhang

Bullock

2015

Inorg. Chem.

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“…When the monocationic dinitrogen‐bridged dimolybdenum complex chelated by 1,1′‐bis(diethylphosphino)ferrocene (depf)6a ( 1 ), which was prepared by the reaction of molybdenum(II)‐dinitrogen hydride complex ( 2 )6c with the trityl cation, was reduced with KC 8 in dark or oxidized with FcBAr F 4 (Fc=Fe(η 5 ‐C 5 H 5 ) 2 , Ar F =3,5‐(CF 3 ) 2 C 6 H 3 ), the neutral dinitrogen‐bridged dimolybdenum complex ( 3 ) or the dicationic dinitrogen‐bridged dimolybdenum complex ( 4 ) was obtained in 34 % or 96 % yield, respectively (Scheme ). A cyclic voltammetric study of 4 has revealed two consecutive one‐electron reversible processes, leading us to examine the direct back‐and‐forth transformations between 3 and 4 .…”

Section: Methodsmentioning

confidence: 99%

Cleavage and Formation of Molecular Dinitrogen in a Single System Assisted by Molybdenum Complexes Bearing Ferrocenyldiphosphine

Miyazaki,

Tanaka,

Tanabe

et al. 2014

Angew Chem Int Ed

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126

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The N≡N bond of molecular dinitrogen bridging two molybdenum atoms in the pentamethylcyclopentadienyl molybdenum complexes that bear ferrocenyldiphosphine as an auxiliary ligand is homolytically cleaved under visible light irradiation at room temperature to afford two molar molybdenum nitride complexes. Conversely, the bridging molecular dinitrogen is reformed by the oxidation of the molybdenum nitride complex at room temperature. This result provides a successful example of the cleavage and formation of molecular dinitrogen induced by a pair of two different external stimuli using a single system assisted by molybdenum complexes bearing ferrocenyldiphosphine under ambient conditions.

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“…A more recent system described by Miyazaki et al employs a Mo complex with strongly donating ferrocenyldiphosphine and pentamethylcyclopentadienyl supporting ligands [68]. Reduction of the dimer [Cp*MoCl 4 ] 2 (μ-1,1’-[PEt 2 ] 2 Fc) with excess Na/Hg under N 2 gives [{1,1’-(PEt 2 ) 2 Fc}(Cp*)Mo](μ-N 2 )Na(THF) x as the major product, with Na + interacting end-on to the N 2 ligand.…”

Section: Effects Of Alkali Cations On N2 Activation By Transition mentioning

confidence: 99%

Coordination chemistry insights into the role of alkali metal promoters in dinitrogen reduction

Connor

Holland

2017

Catalysis Today

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The Haber-Bosch process is a major contributor to fixed nitrogen that supports the world's nutritional needs and is one of the largest-scale industrial processes known. It has also served as a testing ground for chemists’ understanding of surface chemistry. Thus, it is significant that the most thoroughly developed catalysts for N2 reduction use potassium as an electronic promoter. In this review, we discuss the literature on alkali metal cations as promoters for N2 reduction, in the context of the growing knowledge about cooperative interactions between N2, transition metals, and alkali metals in coordination compounds. Because the structures and properties are easier to characterize in these compounds, they give useful information on alkali metal interactions with N2. Here, we review a variety of interactions, with emphasis on recent work on iron complexes by the authors. Finally, we draw conclusions about the nature of these interactions and areas for future research.

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Design and Preparation of Molybdenum–Dinitrogen Complexes with Ferrocenyldiphosphine and Pentamethylcyclopentadienyl Moieties as Auxiliary Ligands

Cited by 37 publications

References 46 publications

Molybdenum Hydride and Dihydride Complexes Bearing Diphosphine Ligands with a Pendant Amine: Formation of Complexes with Bound Amines

Molybdenum Hydride and Dihydride Complexes Bearing Diphosphine Ligands with a Pendant Amine: Formation of Complexes with Bound Amines

Cleavage and Formation of Molecular Dinitrogen in a Single System Assisted by Molybdenum Complexes Bearing Ferrocenyldiphosphine

Coordination chemistry insights into the role of alkali metal promoters in dinitrogen reduction

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