Reactivity of Coordinatively Unsaturated Trivalent Chromium Complexes with Sulfur: Preparation of Novel Sulfide-bridged Dinuclear CrIV Derivatives

The homoleptic CrIII amide complexes [(RR′N)3Cr] [R = R′ = cyclohexyl (1a); R = adamantyl, R′ = 3,5-Me2Ph (1 b)] were prepared and characterized. Reactions with elemental sulfur produced the corresponding dinuclear complexes [{(RR′N)2Cr}2(μ-S)2] (2) through loss of one amide group. These two new dinuclear CrIV species are paramagnetic with magnetic moments lower than expected for the d2 electronic configuration of CrIV. Magnetic measurements and ab initio calculations were carried out to elucidate the nature of magnetic interactions in these dinuclear systems. The molecular structures of 1a and 2a were elucidated by X-ray crystal structures.

New dimeric CrIV sulfide derivatives [{(R2N)2Cr}2(μ-S)2] were obtained by reaction of the coordinatively unsaturated triangular CrIIIcomp1exes [(R2N)3Cr] with S8 (see scheme, R = R′ = cyclohexyl; R = adamantyl, R′ = 3,5-Me2Ph). Magnetic measurements, EPR spectroscopy, and ab initio calculations were used in an attempt to elucidate the nature of the magnetic interactions associated with these dinuclear CrIV complexes.