Product Diversity in the Reactions of TpW(S2CNEt2)(CO)2 with Alkynes:  Novel η2-Alkyne and Tungstathiaenone Complexes

The reactions of Tp*W(S2CNEt2)(CO)2 [Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate] with phenylacetylene, 2-butyne-1,4-diol, and dimethyl acetylenedicarboxylate (DMAC) in chlorinated solvents produce Tp*W(S2CNEt2 -κS)(η2-PhC⋮CH)(CO) (1), Tp*WCl(η2-HOCH2C⋮CCH2OH)(CO) (2), and Tp*W{OCC(CO2Me)C(CO2Me)S-κ3 O,C,S)}(SCNEt2-κ2 C,S) (3), respectively. The complexes have been characterized by microanalysis, IR and 1H and 13C NMR spectroscopy, mass spectrometry, and X-ray diffraction. Complexes 1 and 2 possess octahedral structures with aligned carbonyl and η2-alkyne ligands (the latter occupying one coordination site) and a tridentate fac-Tp* ligand; the coordination spheres are completed by monodentate dithiocarbamate (W−S(1) 2.397(2) Å, W···S(2) 3.999(2) Å) and chloro ligands, respectively. Complex 3 contains a novel heterometallacycle incorporating acyl-κ2 O,C [ν(CO) 1585 cm-1; δC (CO) 269.2, 1 J CW 18 Hz] and enethiolate units, a thiocarboxamido ligand [ν(CN) 1525 cm-1; δC 250.3, 1 J CW 81 Hz], and a tridentate fac-Tp* ligand. The complex exhibits an octahedral structure with planar, orthogonal acyl-enethiolate and thiocarboxamide ligands (the acyl and thiocarboxamide units each occupy one coordination site).