Open platinum aggregate frameworks with overhead dithiolate bridges

Abstract

A convenient method has been developed to bring together two discrete moieties of [Pt₂(μ-S)₂(PPh₃)₄] to give an open Pt₄ aggregate of Pt₂•••(spacer)•••Pt₂, as exemplified in the isolation of [(PPh₃)₄Pt₂(μ-S)(μ-SRS)(μ-S)Pt₂(PPh₃)₄](PF₆)₂ [R = m-CH₂C₆H₄CH₂, p-CH₂C₆H₄CH₂, CH₂C₁₀H₆CH₂, and CH₂(C₆H₄)₂CH₂]. The spacer is a dithiolate with an extended skeletal backbone formed from the alkylation of sulfide with a suitable dibromo-organic compound. This synthetic methodology can tolerate a range of conformationally contrasting thiolate substituents with different chemical functionalities. Shorter or stereochemically more restrictive spacers could opt to be an intramolecular bridge over the Pt₂ core, as given in [Pt₂(μ-S-o-CH₂C₆H₄-C₆H₄CH₂S)(PPh₃)₄](PF₆)₂. A few representative complexes have been characterized by single-crystal X-ray diffraction analysis.