Anhydrous yttrium acetylacetonate and the course of thermal dehydration' of Y(acac)[sub 3][center dot]3H[sub 2]O

Hydrocarbon-soluble [Y(acac)[sub 3]][sub n] (acac = acetylacetonate) is produced in high yield by treatment of Y[N(SiMe[sub 3])[sub 2]][sub 3] with 3 equiv of Hacac in hydrocarbon solvent. Variable-temperature [sup 1]H and [sup 89]Y NMR studies suggest that the degree of aggregation, n, of this compound is four. Attempted slow crystallization of this compound from hexanes gives, as the least-soluble material, the product of adventitious partial hydrolysis: Y[sub 4](OH)[sub 2](acac)[sub 10]. Its structure was established by X-ray diffraction as Y[sub 4]([mu][sub 3]-OH)[sub 2]([mu]-acac)[sub 6](acac)[sub 4]. This centrosymmetric aggregate has a diamond-shaped Y[sub 4] core, with [mu][sub 3]-OH groups lying above and below the Y[sub 4] plane. The aggregation is further enforced by six acac ligands which have one oxygen terminal and the second bridging two yttrium atoms. Each of the remaining four acac ligands are fully terminal on a different yttrium such that every metal achieves coordination number eight. Various methods to produce this compound in high yield are discussed, including controlled vacuum thermolysis of bulk solid Y(acac)[sub 3][center dot]3H[sub 2]O, which gives, after recrystallization from benzene, Y[sub 4](OH)[sub 2](acac)[sub 10][center dot]4C[sub 6]H[sub 6]. This solid contains the same molecules isolated earlier, packed together in the lattice with benzene molecules. Themore » loss of Hacac on vacuum thermolysis is suggested to be initiated by the hydrogen bonding to acac oxygen which exists in solid Y(acac)[sub 3][center dot]H[sub 2]O. 13 refs., 2 figs., 3 tabs.« less