SOLID-STATE AND SOLUTION STRUCTURES OF SOME LITHIUM-SALTS OF TETRAPHENYLDISILOXANEDIOLATE(2-) AND THE LITHIUM-BRIDGED COMPOUNDS LI2[M(OSIPH2OSIPH2O)3.3PY] (PY = PYRIDINE, M = ZR OR HF)

The compound [{Si2Ph4O(OLi)2}2.3(C4H8O2)]infinity was formed in a 2:1 reaction between n-butyllithium and tetraphenyldisiloxanediol in dioxa ne and its solid-state structure was determined by single-crystal X-ra y diffraction. Variable-temperature Li-71 and ambient temperature Si-2 9 NMR studies on [H-8(2)]toluene solutions of this and the related pyr idine (py) adduct (Si2Ph4O(OLi)2.2py] were carried out. The cyclic haf nasiloxane Li2[Hf (OSiPh2OSiPh2O)3].3py.3C6H6 was isolated from a 3:1 reaction between [Si2Ph4O(OLi)2.2thf]2 (thf = tetrahydrofuran) and HfC l4 and its structure determined by single-crystal X-ray diffraction. T he variable-temperature Li-7 NMR spectra of this and the related zirco nium compound show that there is rapid exchange between non-equivalent lithium environments. Lithium hopping between available equivalent en vironments is inferred by the equilibration of the three distinct sili con environments in the structure as seen by Si-29M R studies.