Complexes of the Early Transition Metals with o-Mercaptophenol and 1,2-Dihydroxybenzene

A novel synthetic approach, based on the reactivity of amido derivatives of the transition metals, M(NR2)x, towards protic reagents, for the synthesis of complexes of Ti, Zr, Hf, Nb, and Ta with o-mercaptophenol and 1,2-dihydroxybenzene is reported. The complexes, isolated as their tetraalkylammonium and tetraphenylarsonium salts, are moderately air stable, well behaved 2:1 (Ti, Zr, Hf) and 1:1 (Nb, Ta) electrolytes. The u. v.–visible spectra of the complexes, which are somewhat reminiscent of the corresponding benzene-1,2-dithiolates, are dominated by ligand-to-metal charge transfer bands. The band positions change in the expected manner, hypsochromic shifts in the order C6H4S22− < C6H4SO2− < C6H4O22− for a given metal and Ti < Zr ∼ Hf, Nb < Ta, Nb < Zr for a given ligand. lt is argued that these spectral resemblances could be a possible indication of variations in coordination geometry of the reported complexes similar to the ones found in compounds of benzene-1,2-dithiol.