Synthesis and reactivity of some octacoordinated dioxouranium(VI) complexes of diacetyl bis(benzoylhydrazone) and benzil bis(benzoylhydrazone)

Abstract

Octacoordinated dioxouranium(VI) complexes of the tetradentate ONNO donors diacetyl bis(benzoylhydrazone) (H₂L) and benzil bis(benzoylhydrazone) (H₂L') are reported. At low <em>p</em>H (1.5-2.5) complexes of the formula [UO₂(H₂L/H₂L')X₂](X^- = Cl^- , Br^-, NO<img src="/image/spc_char/3_bar.gif" alt="" border="0" />, NCS^-, ClO<img src="http://www.niscair.res.in/jinfo/Subscript4.gif" alt="" border="0" />, OAc^- or 0.5SO<img src='http://www.niscair.res.in/jinfo/four1.gif' border=0>) containing the ke-to form of the ligands are isolated. At higher <em>p</em>H(6-7), the complexes [UO₂(L_/L/H₂L₂)] are obtained in which the ligand is present in its deprotonated enolate form (L^2-<em>- </em>or L'^2-). Reactions of [[UO₂(H₂L/H₂L')X₂]/ [UO₂(L/L')H₂O₂] with neutral monodentate (B) and bidentate lewis bases (AA) lead to the formation of mixed-ligand complexes of the type [UO₂(L/L')(B₂)] and [UO₂(L/L')(AA)] respectively. Results of elemental analyses, magnetic susceptibility and conductivity measurements, spectroscopic (IR, electronic etc.) and thermal decomposition studies have been utilised to characterise the complexes.