Synthesis of supine–prone bis(diene)tungsten complexes bearing catecholate and diphenylacetylene ligands

Reaction of a mono(catecholato)tetrachlorotungsten(VI) complex, WCl4(O2-1,2-C6H4) (1a), with two equivalents of (2,3-dimethyl-2-butene-1,4-diyl)magnesium gave a new class of tungsten bis(diene) complex, W(O2C6H4)(C4H4Me2)2 (2), whose supine–prone structure was determined by NMR and X-ray analysis. The reaction of 2 with two equivalents of CF3SO3H resulted in selective removal of the prone-diene ligand to give W(O2C6H4)(C4H4Me2)(OSO2CF3)2 (3). A similar bis(diene) complex containing diphenylacetylene complex, W(PhCCPh)(C4H4Me2)2 (4), was prepared.