Mononuclear NiIII alkyl complexes (Alkyl = Me and Et)

Mononuclear, distorted trigonal bipyramidal [PPN][NiIII(R)- (P(C6H3-3-SiMe3-2-S)3)] (R) Me (1); R) =Et (2)) were prepared by reaction of [PPN][NiIIICl(P(C 6H3-3-SiMe3-2-S)3)] and CH 3MgCl/C2H5MgCl, individually. EPR, SQUID studies as well as DFT computations Reveal that the NiIII in 1 has a low-spin d7 electronic configuration in a distorted trigonal bipyramidal ligand field. The Ni-C bond lengths of 1.994(3) å in 1 and 2.015(3) å in 2 are comparable to that in the NiIII-methyl state of MCR (̃2.04 å) (Sarangi, R.; Dey, M.; Ragsdale, S. W. Biochemistry 2009, 48, 3146). Under a CO atmosphere, CO triggers homolytic cleavage of the NiIII-CH3 bond in 1 to produce Ni II-thiolate carbonyl [PPN][NiII(CO)(P(C6H 3-3-SiMe3-2-S)3)] (3). Additionally, protonation of 1 with phenylthiol generates NiIII-thiolate [PPN][NiIII(SPh)-(P(C6H3-3-SiMe 3-2-S)3)] (4).