Anne K. McMullen

Complexation and intramolecular alkylation of bipyridyl ligands by Zr(OAr)2R2 (R = CH3, CH2Ph) compounds

Abstract Addition of the α-di-imine ligands 2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (4,4′-Me2bipy) or 1,10-phenanthroline (phen) to the bis-alkyls Zr(OAr-2,6Bu2t)2(R)2 (OAr-2,6Bu2t = 2,6-di-tert-butylphenoxide; R = CH3, CH2Ph) results in the formation of two types of product. In the case of the dimethyl substrate a simple adduct such as Zr(OAr-2,6Bu2t)2(Me)2(bipy) is generated. However, with dibenzyl the products obtained are the result of an intramolecular alkylation of the α-di-imine ligands. Spectroscopic data confirm the asymmetric nature of the ensuing alkylated heterocycles. A single crystal X-ray diffraction study on Zr(OAr-2,6Bu2t)2(Me)2(4,4′-bipy) confirmed the stoichiometry and showed a very crowded coordination sphere about the six-coordinate metal centre with the two trans methyl groups being severely bent towards the bipyridine chelate rings.