1051897-89-2Relevant academic research and scientific papers
H2 Evolution from a Thiolate-Bound Ni(III) Hydride
Gu, Nina X.,Oyala, Paul H.,Peters, Jonas C.
supporting information, p. 7827 - 7835 (2020/05/27)
Terminal NiIII hydrides are proposed intermediates in proton reduction catalyzed by both molecular electrocatalysts and metalloenzymes, but well-defined examples of paramagnetic nickel hydride complexes are largely limited to bridging hydrides. Herein, we report the synthesis of an S = 1/2, terminally bound thiolate-NiIII-H complex. This species and its terminal hydride ligand in particular have been thoroughly characterized by vibrational and EPR techniques, including pulse EPR studies. Corresponding DFT calculations suggest appreciable spin leakage onto the thiolate ligand. The hyperfine coupling to the terminal hydride ligand of the thiolate-NiIII-H species is comparable to that of the hydride ligand proposed for the Ni-C hydrogenase intermediate (NiIII-H-FeII). Upon warming, the featured thiolate-NiIII-H species undergoes bimolecular reductive elimination of H2. Associated kinetic studies are discussed and compared with a structurally related FeIII-H species that has also recently been reported to undergo bimolecular H-H coupling.
Mononuclear nickel(III) complexes [NiIII(OR)(P(C 6H3-3-SiMe3-2-S)3)]- (R = Me, Ph) containing the terminal alkoxide ligand: Relevance to the nickel site of oxidized-form [NiFe] hydrogenases
Chiou, Tzung-Wen,Liaw, Wen-Feng
, p. 7908 - 7913 (2009/02/08)
The unprecedented nickel(III) thiolate [NiIII(OR)(P(C 6H3-3-SiMe3-2-S)3)- [R = Ph (1), Me (3)] containing the terminal NiIII-OR bond, characterized by UV-vis, electron paramagnetic resonance, cyclic voltammetry, and single-crystal X-ray diffraction, were isolated from the reaction of [Ni III(Cl)(P(C6H3-3-SiMe3-2-S) 3)]_ with 3 equiv of [Na][OPh] in tetrahydrofuran (THF)-CH3CN and the reaction of complex 1 with 1 equiv of [Bu 4N][OMe] in THF-CH3OH, respectively. Interestingly, the addition of complex 1 into the THF-CH3OH solution of [Me 4N][OH] also yielded complex 3. In contrast to the inertness of complex [NiIII(Cl)(P(C6H3-3-SiMe 3-2-S)3)]- toward 1 equiv of [Na][OPh], the addition of 1 equiv of [Na][OMe] into a THF-CH3CN solution of [NiIII(Cl)(P(C6H3-3-SiMe3-2-S) 3)]- yielded the known [NiIII(CH 2CN)(P(C6H3-3-SiMe3-2-S) 3)]- (4). At 77 K, complexes 1 and 3 exhibit a rhombic signal with g values of 2.31, 2.09, and 2.00 and of 2.28, 2.04, and 2.00, respectively, the characteristic g values of the known trigonal-bipyramidal NiIII [NiIII(L)(P(C6H3-3-SiMe 3-2-S)3)]- (L = SePh, SEt, Cl) complexes. Compared to complexes [NiIII(EPh)(P(C6H 3-3-SiMe3-2-S)3)]- [E = S (2), Se] dominated by one intense absorption band at 592 and 590 nm, respectively, the electronic spectrum of complex 1 coordinated by the less electron-donating phenoxide ligand displays a red shift to 603 nm. In a comparison of the Ni III-OMe bond length of 1.885(2) A found in complex 3, the longer NiIII-OPh bond distance of 1.910(3) A found in complex 1 may be attributed to the absence of σ and π donation from the [OPh]-coordinated ligand to the NiIII center.
