Co-ordination properties of 1,10-phenanthroline-5,6-dione towards group 4 and 5 metals in low and high oxidation states †

The molecular structure of 1,10-phenanthroline-5,6-dione has been determined by X-ray diffraction analysis. The compound reacts with the tetrachlorides of Group 4 metals affording adducts of general formula [MCl4(C12H6N2O2)] (M = Ti, Zr or Hf) and [(MCl4)2(C12H6N2O2)] (M = Ti or Hf), N,N′- and N,N′,O,O′-co-ordinated respectively. The compound [HfCl4(C12H6N2O2)] is reactive towards TiCl4 affording the bimetallic compound [Cl4Hf(C12H6N2O2)TiCl4]. The reaction of the dione with bis-cyclopentadienyl derivatives of titanium(II), zirconium(II), [MCp2(CO)2], and vanadium(II), VCp2, affords derivatives O,O′-co-ordinated to the MCp2 moiety. By reaction of [TiCp2(C12H6N2O2)] with [TiCp2(CO)2] the bimetallic derivative [(TiCp2)2(C12H6N2O2)] is obtained, which is suggested to contain two TiCp2 fragments, O,O′- and N,N′-co-ordinated to 1,10-phenanthroline-5,6-dione. The [MCp2(C12H6N2O2)] (M = Ti, Zr or V) derivatives react with M′Cl4 (M′ = Ti or Hf) to give [Cp2M(C12H6N2O2)M′Cl4] bimetallics.