Chalcogenolato-bridged cyclometallated binuclear palladium complexes: Synthesis, spectroscopy, structures of [Pd 2(μ-Cl)(μ-SMes)(C 10H 6NMe 2–C,N) 2] and [Pd 2(μ-SePh) 2(C 10H 6NMe 2–C,N) 2

Abstract

Reactions of orthometallated binuclear palladium complexes with NaER, obtained by NaBH 4 reduction of R 2E 2 in methanol, gave complexes, [Pd 2(μ-ER) 2(C ∩Y) 2] (HC ∩Y = N, N-dimethylbenzylamine (C 6H 5CH 2NMe 2), N, N-dimethylnaphthylamine (C 10H 7NMe 2), tri- o-tolylphosphine {P(tol- o) 3}; ER=SePh, SeMes, TePh, TeMes (Mes = 2,4,6-Me 3C 6H 2). Similar reactions of [Pd 2(μ-Cl) 2(C 10H 6NMe 2–C,N) 2] with Pb(SMes) 2 or MesSH in the presence of NaHCO 3 gave chloro/thiolato-bridged complex [Pd 2(μ-Cl)(μ-SMes)(C 10H 6NMe 2–C,N) 2]. The newly synthesized complexes were characterized by elemental analysis, UV–Vis, IR, NMR ( 1H, 13C, 31P, 77Se, 125Te) spectroscopy. These complexes crystallized out preferentially in sym- cis configuration. A low energy charge transfer transition has been identified from chalcogenolate centers to an emptyπ ∗ orbital of cyclometallated ligand in absorption spectroscopy in these complexes. The structures of [Pd 2(μ-Cl)(μ-SMes)(C 10H 6NMe 2–C,N) 2] ( 1) and [Pd 2(μ-SePh) 2(C 10H 6NMe 2–C,N) 2] ( 3) have been established by single crystal X-ray diffraction analyses. In the former, the two palladium atoms are held together by chloro and thiolato bridges whereas in the latter, the two phenylselenolato ligands bridge two palladium atoms. The pyrolysis of [Pd(μ-TeMes)(C 10H 6NMe 2–C,N)] 2 ( 10) in a furnace gave Pd 7Te 3 whereas thermolysis in TOPO afforded primarily PdTe 2.