Synthesis and reactivity aspects of the bis(dithiolene) chalcogenide series [WIVQ(S2C2R2)2]2- (Q = O, S, Se)

An improved synthetic route to the previously reported dicarbonyl complexes [W(CO)(2)(S2C2R2)(2)] (R = Ph (1), Me (2)) has been developed via the thermal reaction of [W(CO)(3)(MeCN)(3)] and [Ni(S2C2R2)(2)] in dichloromethane (60-70%). Complexes 1 and 2 are shown to be useful synthetic precursors by means of carbonyl ligand displacement. Reactions of 1 with Et4NOH, Na2S, and Li2Se afford the previously unknown bis(dithiolene) series [W(IV)Q(S2C2Ph2)(2)](2-) (Q = O (3), S (6), Se (7), 65-76%). Complex 2 and Et4NOH give [(WO)-O-IV(S2C2Me2)(2)](2-) (5, 68%). Members of the series manifest absorption spectra that are strongly dependent on Q and odor potentials for W(IV)Q/W(V)Q couples that are independent of Q. Reaction of 3 and 5 with Mel or EtI results in mono-S-alkylation as shown by the H-1 NMR spectra of [WO(EtS2C2R2)(S2C2R2)](1-), which indicate a single: stereoisomer with a diastereotopic methylene group. S-alkylation of 3 was further confirmed by the structure of the reaction product with Mel, [WO(MeS2C2Ph2)(S2C2Ph2)](1-) (8, 65%), which reveals the exo stereoisomer with a pyramidal sulfur atom whose methyl carbon atom is displaced 1.27 Angstrom from the chelate ring plane. Treatment of 3 with hard alkylating agents caused oxidation to [(WO)-O-V(S2C2Ph2)(2)](-), independently prepared by reaction of 3 with iodine (78%). Sulfide complex 6 with soft alkylating agents such as Mel gave mixtures. Reaction of 6 with C7H7+ resulted in electron transfer rather than alkylation and the formation of binuclear [W-2(V)(mu-S)(2)(S2C2Ph2)(4)](2-) (11, 53%). No alkylated species were isolated from selenido complex 7; [W(S2C2Ph2)(3)] (13) was identified as a reaction product. Electrochemical data and X-ray structural results for 1, 2, 13 (trigonal prismatic), Et4N+ salts of 3, 5, 6 (square pyramidal), 8 (distorted square pyramidal), and 11 (distorted octahedral), and (PhCH(2)Net(3))[W(S2C2-Ph2)(3)] (distorted trigonal prismatic) are presented.