Reactivity of Labile Triosmium Complexes, [Os3(CO)10(MeCN)2] and [Os3(CO)10(µ-H)2] with Tetraethylthiuram Disulfide (Disulfiram)
摘要
Reactions of the anti-alcohol drug disulfiram (tetraethylthiuram disulphide = Et4TDS) with low valent triosmium complexes are described. Room temperature reaction with [Os3(CO)10(MeCN)2], affords three new open polynuclear clusters, [Os3(CO)10(S2CNEt2)2] (1), [Os4(CO)12{µ3-η1(C),κ2(O,O)-CO2}(S2CNEt2)(µ-S2CNEt2)] (2) and [Os3(CO)9(µ3-SCNEt2){µ-SC(O)NEt2}] (3) together with the known mononuclear complex cis-[Os(CO)2(S2CNEt2)2] (4). All result from oxidative-addition of disulfiram to the triosmium centre, with 2 also capturing CO2, while cluster 3 has undergone further C–S bond scission and partial oxidation of one of the generated thiocarboxamide ligands. With [Os3(CO)10(µ-H)2], complexes 1 and 4 are also formed along with previously reported [Os3(CO)10(µ-S2CNEt2)(µ-H)] (5), [Os3(CO)9(µ3-S2CNEt2)(µ-H)] (6), and the new cluster, [Os3(CO)9(µ-S2CNEt2)(µ-H)] (8), which is an isomer of 6. The product distribution is rationalized by completing pathways following the oxidative-addition of disulfiram. Thus, reductive-elimination of H2 affords 1, which in turn converts to 4, while reductive-elimination of the (unstable) dithiocarbamic acid, Et2NCS2H, leads to the formation of 5, which can further lose CO to afford isomers 6 and 8. Heating disulfiram with [Os3(CO)12] at 110 °C predominantly affords 4, together with smaller amounts of the novel trithiocarbamate complex, cis-[Os(CO)2(S2CNEt2)(S3CNEt2)] (9). All the compounds have been characterized by elemental analysis, IR and 1H NMR spectroscopy, together with single crystal X-ray diffraction analysis of six molecules.