Synthesis, Structures and Chemical Reactivity of Dithiolato-Bridged Ni-Fe Complexes as Biomimetics for the Active Site of [NiFe]-Hydrogenases

To develop the structural and functional modeling chemistry of [NiFe]-H2ases, we have carried out a study regarding synthesis, characterization reactivity new series [NiFe]-H2ase model complexes. Thus, treatment diphosphine dppb-chelated Ni complex (dppb)NiCl2 (dppb = 1,2-(Ph2P)2C6H4) with (dppv)Fe(CO)2(pdt) (dppv 1,2-(Ph2P)2C2H2, pdt 1,3-propanedithiolate) NaBF4 gave dicarbonyl [(dppb)Ni(pdt)Fe(CO)2(dppv)](BF4)2 ([A](BF4)2). Further [A](BF4)2 Me3NO Bu4NCN or KSCN afforded t-cyanido t-isothiocyanato complexes [(dppb)Ni(pdt)Fe(CO)(t-R)(dppv)]BF4 ([1]BF4, R CN; [2]BF4, NCS), respectively. While azadiphosphine MeN(CH2PPh2)2-chelated t-hydride [MeN(CH2PPh2)2Ni(pdt)Fe(CO)(t-H)(dppv)]BF4 ([3]BF4) was prepared by [MeN(CH2PPh2)2Ni(pdt)Fe(CO)2(dppv)](BF4)2 ([B](BF4)2) 1.5 MPa H2, [B](BF4)2 (without H2) in pyridine resulted formation novel monocarbonyl [MeN(CH2PPh2)2Ni(SCHCH2CH2S)Fe(CO)(dppv)]BF4 ([4]BF4) via unexpected sp3 C-H bond activation reaction. Furthermore, PhN(CH2PPh2)2-chelated µ-mercapto [PhN(CH2PPh2)2Ni(pdt)Fe(CO)(µ-SH)(dppv)]BF4 ([5]BF4) [PhN(CH2PPh2)2Ni(pdt)Fe(CO)2(dppv)](BF4)2 ([C](BF4)2) H2S gas, whereas Ph2CHN(CH2PPh2)2-chelated [Ph2CHN(CH2PPh2)2Ni(pdt)Fe(CO)2(dppe)](BF4)2 ([D](BF4)2, dppe 1,2-(Ph2P)2C2H4) Me3NO?2H2O rise to µ-hydroxo [Ph2CHN(CH2PPh2)2Ni(pdt)Fe(CO)(µ-OH)(dppe)]BF4 ([6]BF4). All possible pathways for are briefly discussed, their structures were fully characterized various spectroscopic techniques six them X-ray crystallography.