Reactivity variations within Group 4 complexes of 1,4-di-tert-butyl-1,4-diazabuta-1,3-diene: Structures of [(C5H5)TiCl{(t-BuNCH)2}] and [(C5H5)2Zr{(t-BuNCH)2}]

The metathetical exchange reactions employed in the syntheses of the Ti and Zr 1,4-diazabuta-1,3-diene complexes follow different pathways, with elimination of Cl− and/or (C5H5)−. 1H NMR spectroscopy shows the complexes to be fluxional in solution, which is likely to involve a ring flipping process of the non-planar chelating reduced 1,4-diazabuta-1,3-diene.