Synthesis, characterisation and X-ray structures of yttrium, barium and copper(II) beta-ketoesterate complexes

beta-Ketoesterates derivatives M(mpa)(x) (M = Y, Ba, Cu; mpaH = methylpival oylacetate; x = 2 or 3) were prepared by ligand exchange reactions starting from methoxides (M = Ba, Cu) or from tristrimethylsilylamide (M = Y) deriv atives. Decomplexation of the oligomeric and non-volatile Ba and Y species was achieved by various Lewis bases. Adducts Y(mpa)(3)L [L = tmeda (N,N,N', N'-tetramethylethane- 1,2-diamine), bipy (2,2'-bipyridine)] and Ba(mpa)(2)L [L = diglyme, 18-crown-6 ether; pmdta = N,N,N',N',N"-pentamethylethylenetr iamine and [Ba(mpa)(2)(tmedta)(2)] were obtained. All compounds were synthe sised in high yield and characterised by elemental analyses, H-l NMR, FT-IR and TGA. The structures of [Ba(mpa)(2)(tmeda)(2)] and [Y(mpa)(3)(bipy)] we re established by single crystal X-ray diffraction. The metals are eight-co ordinated with a slightly distorted square antiprismatic surrounding. The y ttrium complexes sublime as adducts. The barium complexes, by contrast, are dissociated in the vapour phase. Better solubility properties in polar and non-polar with respect to the 2,2,6,6-tetramethylheptane-3,5-dionates anal ogues were observed especially for the copper species. These compounds are thus potential metal-oxide precursors for liquid injection MOCVD using solv ents such as hexane or diglyme. (C) 2000 Elsevier Science S.A. All rights r eserved.