(Arene)Ru(II) Complexes of P-N Ligands

Abstract

Ligands containing both phosphorus and nitrogen donors have shown excellent catalytic properties. We have set out to synthesize a series of P-N ligands known as "phosphino hydrazones". Some of these ligands, for example, Z-PPh₂CH₂C(Bu^t)=NNMe₂ I and Z-PPh₂CH₂C(Bu^t)=NNH₂ II have shown interesting coordination chemistry with transition metals such as Cr, Mo, W, Rh, Ir, Pd and Pt. Here we report the synthesis of novel η⁶-arene complexes of I and II with ruthenium. Treatment of 0.5 equivalent of [(η⁶-p-cymene)RuCl₂]₂ with I in refluxing benzene gave the ruthenium (II) complex (1). The chelating complex [(η⁶-p-cymene)RuCl {Z-PPh₂CH₂C(Bu^t)=NNMe₂}]PF₆ (2) with a 6-membered ring was made by treating (1) with NH₄PF₆ in methanol. Treatment of II with 0.5 equiv. of [(η⁶-p-cymene)RuCl₂]₂ gave the chelating complex [(η⁶-p-cymene)RuCl {Z-PPh₂CH₂C(Bu^t)= NNH₂}]Cl (3). We have found that the ligand I has the potential to act as either a modentate ligand or a bidentate ligand. The ligand II forms chelating complexes as the NH₂ group is sterically less demanding.

doi:10.4038/ouslj.v4i0.339

OUSL Journal (2007) Vol.4, (pp.72-77)