Oxidative addition chemistry of bis(4,5-dimethoxybenzo)-1,2,5,6-tetrathiocin with cyclopentadienyl metal carbonyl complexes and the mechanochemical transformation of CpCo(dmobdt) to [CpCo(dmobdt)]2

Abstract

The oxidative addition of tetramethoxy-1,25,6-dibenzotetrathiocin (1) to CpCo(CO)2, [CpFe(CO)2]2, [CpMo(CO)3]2 and CpV(CO)4in toluene under microwave irradiation (150 °C, 30 mins) afforded the complexes CpCo(dmobdt) (2), [Cp2Fe2(dmobt)(CO)2] (3), [Cp2Mo2(dmobdt)2] (4) and [(Cp)2V2(dmobdt)2] (5) [dmobdt = 4,5-dimethoxybenzene-1,2-dithiolate dianion, (MeO)2C6H2S22−]. Vacuum sublimation of 2 afforded dark blue crystals of the monomeric 16e- complex, CpCo(dmobdt) (2a), whereas recrystallisation from CH2Cl2 afforded dark blue crystals of the dimeric 18e- polymorph, [CpCo(dmodt)]2 (2b). The structures of 2a, 2b, 3, 4 and 5 were determined by X-ray diffraction. DSC studies on 2a and 2b indicated distinct melting points (206 and 216 oC respectively) and VT-PXRD revealed no thermally-induced phase change between 2a and 2b. Conversely, mechanochemical grinding of 2a revealed an irreversible phase transition to 2b.