Barium acylpyrazolonate derivatives stabilized by O- and N-donor ligands: synthesis, spectral and structural characterization

New Ba acylpyrazolonate derivatives of formula [Ba(Q)(2)(tetraglyme)] (HQ = HQ(tbu) = 1-Ph-3-Me-4-C(=O)CH(2)But-5-pyrazolone; tetraglyme = 2,5,8,11,14-pentaoxapentadecane), [Ba(Q)(2)(tmeda)(2)] (HQ = HQ(tbu) or HQ(piv), where HQ(piv) = 1-Ph-3-Me-4-C(=O)Bu'-5-pyrazolone; tmeda = N,N,N',N'-tetramethylethylenediamine), [Ba(Q)(2)(pmdien)(H2O)] (HQ = HQ(tbu) or HQ(piv); pmdien = N,N,N',N'',N'''-pentamethyidiethylenetriamine) and [Ba(Q)(2)(pmdien)(Meim)] (HQ = HQ(tbu) or HQ(piv); Meim = 1-methylimidazole) have been synthesized and analytically and spectroscopically characterized. They are mononuclear air and solution stable compounds containing an eight-coordinated barium atom. The X-ray crystal structures of the hydrates [Ba(Q(tbu))(2)-(pmdien)(H2O)] and [Ba(Q(piv))2(pmdien)(H2O)] show the water molecule directly bonded to Ba and involved in intermolecular H-bonding network. In the X-ray crystal structure of [Ba(Q(piv))(2)(pmdien)(Meim)], the Meim ligand substitutes the water of previous derivatives and decreases the strength of intermolecular interactions, lowering the melting point. The derivative [Ba(Q(tbu))(2)(pmdien)(NEt3)] has been prepared from interaction of [Ba(Q(tbu))(2)(pmdien)(H2O)] with excess triethylamine in acetonitrile. (c) 2004 Elsevier B.V. All rights reserved.