Synthesis of Dinuclear Mo−Fe Hydride Complexes and Catalytic Silylation of N2. Issue 43 (20th July 2020)

• Record Type: Journal Article
• Authors: Ishihara, Kodai; Araki, Yuna; Tada, Mizuki; Takayama, Tsutomu; Sakai, Yoichi; Sameera, W. M. C.; Ohki, Yasuhiro
• Is Part Of: Chemistry. Volume 26:Issue 43(2020)
• Page Start: 9537
• Page End: 9546
• Publication Date: 2020-07-20
• Subjects: dinuclear complex -- hydrides -- iron -- molybdenum -- silylamine; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202000104
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Two transition‐metal atoms bridged by hydrides may represent a useful structural motif for N2 activation by molecular complexes and the enzyme active site. In this study, dinuclear Mo IV ‐Fe II complexes with bridging hydrides, Cp R Mo(PMe3 )(H)(μ‐H)3 FeCp* (2 a ; Cp R =Cp*=C5 Me5, 2 b ; Cp R =C5 Me4 H), were synthesized via deprotonation of Cp R Mo(PMe3 )H5 (1 a ; Cp R =Cp*, 1 b ; Cp R =C5 Me4 H) by Cp*FeN(SiMe3 )2, and they were characterized by spectroscopy and crystallography. These Mo−Fe complexes reveal the shortest Mo−Fe distances ever reported (2.4005(3) Å for 2 a and 2.3952(3) Å for 2 b ), and the Mo−Fe interactions were analyzed by computational studies. Removal of the terminal Mo−H hydride in 2 a –2 b by [Ph3 C] + in THF led to the formation of cationic THF adducts [Cp R Mo(PMe3 )(THF)(μ‐H)3 FeCp*] + (3 a ; Cp R =Cp*, 3 b ; Cp R =C5 Me4 H). Further reaction of 3 a with LiPPh2 gave rise to a phosphido‐bridged complex Cp*Mo(PMe3 )(μ‐H)(μ‐PPh2 )FeCp* (4 ). A series of Mo−Fe complexes were subjected to catalytic silylation of N2 in the presence of Na and Me3 SiCl, furnishing up to 129±20 equiv of N(SiMe3 )3 per molecule of 2 b . Mechanism of the catalytic cycle was analyzed by DFT calculations. Abstract : Dinuclear Mo−Fe complexes supported by bridging hydrides were synthesized and fully characterized. These dinuclear complexes served as good catalyst precursors for the reduction of N2 into N(SiMe3 )3 . Mechanism of catalytic cycle was rationalized by DFT calculations.