Zirconium and hafnium complexes containing bidentate diarylamido-phosphine ligands

The first examples of mononuclear, structurally characterized triarylphosphine complexes of zirconium and hafnium are reported. The metathetical reactions of MCl4(THF)2 (M = Zr, Hf) with iPrNP]Li(THF)2 (iPrNP]- = N-(2-(diphenylphosphino)phenyl)-2,6-diisopropylanilide) or MeNP]Li(THF)2 (MeNP]- = N-(2-(diphenylphosphino)phenyl)-2,6-dimethylanilide) in toluene at -35 degrees C produced the corresponding iPrNP]MCl3(THF) and MeNP]2MCl2, respectively, in high yield. In contrast, attempts to prepare MeNP]MCl3(THF) and iPrNP]2MCl2 led to the concomitant formation of mono- and bis-ligated complexes, from which purification proved rather ineffective. The solution and solid-state structures of iPrNP]MCl3(THF) and MeNP]2MCl2 were studied by multinuclear NMR spectroscopy and X-ray crystallography. The geometry of these six-coordinate complexes is best described as a distorted octahedron in which the chloride ligands in iPrNP]MCl3(THF) adopt a virtually meridional coordination mode whereas those in MeNP]2MCl2 are trans to each other.