Studies on mixed beta-diketonate/isopropoxide compounds of zirconium and hafnium, the X-ray single-crystal structures of [M-2(OPri)(6)(tmhd)(2)] (M =Zr, Hf): Some chemistry important in the MOCVD of oxides

Reactions of the homoleptic alkoxides [M(OPri)(4).((PrOH)-O-i)] (M = Zr or Hf) with different stoichiometric amounts of the beta-diketone ligand tmhd- H (2,2,6,6-tetramethylheptane-3,5-dione) have been investigated. Crystallin e, but powdery, materials with a stoichiometry close to [M(OPri)(2)(tmhd)(2 )] have been isolated by reacting 2 mol of the beta-diketone with 1 mol of the metal all;oxide; we present a full explanation based on the H-1 NMR res ults for their behavior in solution. The compounds [M-2(OPri)(6)(tmhd)(2)] [M = Zr (1b), and Hf (2b)] have been obtained from the exhaustive recrystal lization of the above reaction mixture or as the products of the 3:1 stoich iometric reaction between [M(OPri)(4).((PrOH)-O-i)](2) and tmhd-T. Compound s 1b and 2b have been shown by X-ray crystallography to be isomorphous and are useful precursors for the deposition of the metal oxides by methods suc h as Liquid injection CVD. The symmetrical, dimeric structure of the compou nds, with one beta-diketonate attached to each half of the dimer, may expla in why the compounds show little or no tendency toward adventitious homogen eous reaction in MOCVD studies.