Chalcogenolato-bridged cyclometallated binuclear palladium complexes: Synthesis, spectroscopy, structures of [Pd2(μ-Cl)(μ-SMes)(C10H6NMe2–C,N)2] and [Pd2(μ-SePh)2(C10H6NMe2–C,N)2]

Reactions of orthometallated binuclear palladium complexes with NaER, obtained by NaBH4 reduction of R2E2 in methanol, gave complexes, [Pd2(μ-ER)2(C∩Y)2] (HC∩Y = N,N-dimethylbenzylamine (C6H5CH2NMe2), N,N-dimethylnaphthylamine (C10H7NMe2), tri-o-tolylphosphine {P(tol-o)3}; ER=SePh, SeMes, TePh, TeMes (Mes = 2,4,6-Me3C6H2). Similar reactions of [Pd2(μ-Cl)2(C10H6NMe2–C,N)2] with Pb(SMes)2 or MesSH in the presence of NaHCO3 gave chloro/thiolato-bridged complex [Pd2(μ-Cl)(μ-SMes)(C10H6NMe2–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 [Pd2(μ-Cl)(μ-SMes)(C10H6NMe2–C,N)2] (1) and [Pd2(μ-SePh)2(C10H6NMe2–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)(C10H6NMe2–C,N)]2 (10) in a furnace gave Pd7Te3 whereas thermolysis in TOPO afforded primarily PdTe2.

Graphical abstractChalcogenolato-bridged cyclometallated binuclear palladium complexes of the type [Pd2(μ-ER)2(C∩Y)2] (HC∩Y = N,N-dimethylbenzylamine (C6H5CH2NMe2), N,N-dimethylnaphthylamine (C10H7NMe2), tri-o-tolylphosphine {P(tol-o)3}; ER = SePh, SeMes, TePh, TeMes) and [Pd2(μ-Cl)(μ-SMes)(C10H6NMe2–C,N)2] have been prepared and characterized by elemental analysis, UV–Vis and NMR spectroscopy. A LLCT band has been identified from chalcogenolate centers to an empty π∗ orbital of the cyclometallated ligand. In the molecular structure of [Pd2(μ-SePh)2(C10H6NMe2–C,N)2] two phenylselenolate ligands bridge two palladium atoms. The pyrolysis of [Pd(μ-TeMes)(C10H6NMe2–C,N)]2 in a furnace yields Pd7Te3.Figure optionsDownload full-size imageDownload as PowerPoint slide