Binuclear Orthometalated N,N-Dimethylbenzylamine Complexes of Palladium(II): Synthesis, Structures and Thermal Behavior

Organochalcogenolate-bridged cyclometalated palladium(II) complexes of the formulae, [Pd-2(mu-Epy)(2)(Me2NCH2C6H4-C,N)(2)] (2) (E = S (2a), Se (2b)), [Pd-2(mu-SAr)(mu-Cl)(Me2NCH2C6H4-C,N)(2)] (3) (Ar = Ph (3a), Mes (Mes = 2,4,6-Me3C6H2) (3b)) and [Pd-2(mu-SeAr)(2)(Me2NCH2C6H4-C,N)(2)] (4) (Ar = Ph (4a), Mes (4b)), have been synthesized by the reactions of [Pd-2(-Cl)(2)(Me2NCH2C6H4-C,N)(2)] with lead or sodium salts of the chalcogenolate ligand. These complexes have been characterized by elemental analysis, mass spectral data, and NMR (H-1 and Se-77{H-1}) spectroscopy. The molecular structure of 2, determined by single crystal X-ray diffraction analysis, revealed a Epy-bridged head-to-tail arrangement in which the eight-membered "(PdECN)(2") ring adopts a distorted twist boat conformation. The Pd center dot center dot center dot center dot Pd separation in 2a is within the van-der-Waals interaction but in 2b it is too large to support the presence of any metal-metal interaction. The thermal behavior of these complexes has been studied by thermogravimetric analysis.