HOMOLEPTIC HYDROXYLAMIDES OF TITANIUM, ZIRCONIUM AND HAFNIUM

The homoleptic N,N-dimethylhydroxylamides of titanium (1), zirconium ( 2) and hafnium (3), M(ONMe(2))(4), have been prepared in high yield by the reactions of the corresponding metal tetrakis(dimethylamides) and N,N-dimethylhydroxylamine in diethyl ether. The compounds have been c haracterised by 1(H) and C-13 NMR and IR spectroscopy as well as by no minal and high-resolution mass spectrometry and elemental analysis. Co mpounds 1 and 2 are crystalline solids, which dissolve in ethers and h ydrocarbons. They can be sublimed at 90 and 100 degrees C (0.1 mbar) r espectively. These volatility data are discussed in comparison to thos e of the isoelectronic titanium and zirconium tetra(isopropoxides) and Ti(ONEt(2))(4) and in the context of their molecular complexities and structures. Compounds 1 and 2 are monomeric both in benzene solution and in the solid state, as shown by cryoscopy and single-crystal X-ray diffraction, respectively. The Ti and Zr atoms occupy an eight-co-ord inate environment with the ONMe(2) ligands co-ordinated in a bidentate fashion. Crystallographic C-2 axes pass through the metal atoms in 1 and 2. The non-equivalent ONMe(2) ligands in one molecule have been fo und to exhibit markedly different geometries, which are discussed in t he context of the molecular geometry of free Me(2)NOH.