Reactions of the seven-co-ordinate complexes [MI2(CO)3(NCMe)2] and [MI2(CO)3(NCMe)L](M = Mo or W; L = PPh3, AsPh3 or SbPh3) with dithiocarbamate ligands

The complexes [MI2(CO)3(NCMe)2](M = Mo or W) react with 1 equivalent of Na[S2CN(CH2Ph)2] eventually to give the iodo-bridged dimers [{M(µ-I)(CO)3[S2CN(CH2Ph)2]}2]. The reaction of [MI2(CO)3(NCMe)2] with 1 equivalent of L (L = PPh3, AsPh3 or SbPh3) gave [MI2(CO)3(NCMe)L] which when treated in situ with Na[S2CNR2](R = Me, Et or CH2Ph) afforded [Ml(CO)3L(S2CNR2)]. The complexes [Mol(CO)3L(S2CNR2)] prepared as described above when treated in situ with 1 equivalent of [S2CNR2]– generally give the mixed-ligand oxides [Mo2O3(S2CNR2)2(S2CNR'2)2]. The complexes [WI(CO)3(PPh3)(S2CNR2)](R = Me, Et or CH2Ph) when treated in situ with Na[S2CNR'2] afforded [W(CO)2(PPh3)(S2CNR2)(S2CNR'2)](R = Me, R′= Et; R = Me, R′= CH2Ph; R = Et, R′= CH2Ph), whereas reaction with the AsPh3 and SbPh3 complexes in an analogous manner gave [W(CO)3(S2CNR2)(S2CNR′2)] in low yield. Reaction of [Mol2(CO)3(NCMe)2] with 2 equivalents of Na[S2CNEt2]·3H2O gave the previously reported oxide compound [Mo2O3(S2CNEt2)4], whereas [WI2(CO)3(NCMe)2] reacts to give [W(CO)3(S2CNEt2)2]. Two equivalents of Na[S2CN(CH2Ph)2] react with [Mol2(CO)3(NCMe)L] to give for L = PPh3 and AsPh3 the oxides [Mo2O3{S2CN(CH2Ph)2}4] and the seven-co-ordinate complex [Mo(CO)2(SbPh3){S2CN(CH2Ph)2}2] for L = SbPh3. The complexes [W(CO)2L{S2CN(CH2Ph)2}2](L = PPh3, AsPh3 or SbPh3) were prepared in an analogous manner. Low-temperature 13C NMR spectra are interpreted to suggest the likely stereochemistry of several of these complexes.