Carbon-13 nuclear magnetic resonance study of some alkoxides of titanium

Abstract

Variable-temperature ¹³C n.m.r. studies of niobium pentaethoxide, and titanium tetraethoxide, tetra-n-propoxide, tetra-n-butoxide, tetraisopropoxide, tetraisobutoxide, tetraneopentyl oxide, and tetra-t-butoxide have been obtained. The coexistence of trimers and trimer aggregates is suggested for the straight-chain alkoxides of titanium. For the branched-chain derivatives, monomer–dimer–trimer equilibria are proposed for the isobutoxide, and monomer–dimer equilibria for the isopropoxide and neopentyl oxide. Use of previously published ¹H n.m.r. data permits estimation of the enthalpy and entropy of dimerization for the ispropoxide and neopentyl oxide as ca. –14 kcal mol^–1 and –50 cal K^–1 mol^–1 respectively.