New cyclometalated palladium(II) complexes with iminophosphines: Crystal structures of [Pd(C^N)( o-Ph 2PC 6H 4–CH=NR)][PF 6] (C^N=azobenzene, R=Et; C^N=2-phenylpyridine, R=Me)

Abstract

The synthesis of new cyclometalated compounds of palladium(II) with the mixed-donor bidentate ligands o-Ph 2 PC 6H 4–CH= NR is described. Two series of complexes [Pd(C^N)( o-Ph 2PC 6H 4–CH=NR)][PF 6] have been prepared using either azobenzene or 2-phenylpyridine as cyclometalated ligands [C^N=azobenzene (azb); R=Me ( 1a), Et ( 2a), n Pr ( 3a), i Pr ( 4a), t Bu ( 5a), Ph ( 6a), NH–Me ( 7a); C^N=2-phenylpyridine (phpy); R=Me ( 1b), Et ( 2b), n Pr ( 3b), i Pr ( 4b), t Bu ( 5b), Ph ( 6b), NH–Me ( 7b)]. The new complexes were characterized by partial elemental analyses and spectroscopic methods (IR, FAB, 1H and 31P NMR). The molecular structures of compounds 2a (monoclinic, P 2 1/ n) and 1b (monoclinic, C 2/ c) have been determined by a single-crystal diffraction study. In both cases this technique revealed the relative trans configuration between the phosphorus atom and the nitrogen atom of the ortho-metalated ligand.