Synthesis and characterization of new cyclometallated Pd(II) complexes with bridging or terminal imidato ligands. Crystal structures of [{Pd(μ-succinimide)(phpy)} 2] and [Pd(azb)(succinimide)(PPh 3)] (phpy = 2-phenylpyridine; azb=azobenzene)

Abstract

Two series of new dinuclear cyclometallated palladium complexes [{Pd(μ-NCO)(C ∧N)} 2] containing asymmetric imidato –NCO– bridging units have been synthesized [C ∧N=azobenzene (azb); –NCO–=succinimide ( 1a), phthalimide ( 2a) or maleimide ( 3a); C ∧N=2-phenylpyridine (phpy); –NCO–=succinimide ( 1b), phthalimide ( 2b) or maleimide ( 3b)]. The reaction of both succinimidato precursors with tertiary phosphines to form the mononuclear N-bonded imidato derivatives of general formula [Pd(C ∧N)(suc)(L)] [C ∧N=azb; L=PPh 3 ( 4a), PPh 2Me ( 5a), PPhMe 2 ( 6a), P(4-F–C 6H 4) 3, ( 7a), P(4-MeO–C 6H 4) 3 ( 8a); C ∧N=phpy; L=PPh 3 ( 4b), PPh 2Me ( 5b), PPhMe 2 ( 6b), P(4-F–C 6H 4) 3 ( 7b), P(4-MeO–C 6H 4) 3 ( 8b)] has been investigated. The new complexes were characterized by partial elemental analyses and spectroscopic methods (IR, FAB, 1H, 13C and 31P). The single-crystal structures of compounds 1b and 4a have been established.