Synthesis, crystal structure, magnetic properties and reactivity of a Ni-Ru model of NiFe hydrogenases with a pentacoordinated triplet (S = 1) NiII center

Abstract The reaction of Ni(xbsms) (H 2 xbsms = 1,2-bis(4-mercapto-3,3-dimethyl-2-thiabutyl)benzene) with [Ru(CO) 3 Cl 2 (thf)] yields green crystals of [NiCl(xbsms)Ru(CO) 3 Cl]. The structure of this structural model of the active site of NiFe hydrogenase reveals a pentacoordinated nickel(II) center with bound chloride anion. It therefore adopts a paramagnetic (S = 1) electronic configuration as shown by magnetic susceptibility measurements. In DMF, this compound is converted into a red ionic-salt [NiL(xbsms)Ru(CO) 3 Cl]Cl (L = water or DMF) that catalyzes hydrogen electro-evolution from Et 3 NHCl at −1.52 V vs. Ag/AgCl (−2.05 V vs. Fc 0/+ ).