Organometallic radical-initiated carbon-sulfur bond cleavage and carbon-carbon coupling in dithiocarbamate and thiocarbenoid cyclopentadienylchromium complexes

Abstract

Cothermolysis of the dithiocarbamate complex CpCr(CO)2(S2CNEt2) (2b) with [CpCr(CO)3]2 (1) in toluene at 110 °C for 2 h led to the isolation of a yellowish red low-melting solid of CpCr(CO)2(CNEt2) (3b; 6%), a dark red viscous liquid of CpCr(CO)2(SCNEt2) (4b; 19%), dark red crystalline solids of CpCr(CO)2(η2(C,O)-C(O)C(NEt2)CH(NEt2 )) (5b; 4%), dark green solids of Cp4Cr4S4 (30%), dark brown solids of the double cubane Cp6Cr8S8(C(S)NEt2)2 (6b; 13%), and blue solids of Cr(S2CNEt2)3 (8b; 9% yield). Except for 5b, the same product composition (3b, 11%; 4b, 14%; 6b, 37%; Cp4Cr4S4, 20%) was obtained from a similar thermal treatment of 8b with 1. A similar reaction of the thiocarbenoid complex CpCr(CO)2(SCNMe2) (4a) yielded yellow crystalline solids of CpCr(CO)2(CNMe2) (3a, 16%), a dark brown solid of Cp4Cr4S2-(CO)(CNMe2) (7a, 36%), Cp4Cr4C4 (10% yield), and Cp2Cr2(CO)4 (17%). Complexes 3a, 5b, and 7a have been characterized by single-crystal X-ray diffraction analysis. The structures of 3a and 5b possess a metal - carbyne and a metal-alkenylacyl moiety, respectively. Complex 7a is a μ3-aminocarbyne cubane complex.