Role of anagostic interactions in cycloplatination of telluroethers: Synthesis and structural characterization

•The role of anagostic interactions in cyclometallation has been demonstrated.•Compounds including cycloplatination of tellurium ligand have been isolated.•Structural evidences for these complexes have also been provided.•Diastereoisomerism in complexes with asymmetric telluroether ligand is observed.

Reactions of K2PtCl4 with TeRRʹ gave complexes of composition [PtCl2(TeRRʹ)2] (R/Rʹ = Ph2(1a), o-tol2 (1b), Mes2(1c), Ph/Mes (1d), o-tol/Mes (1e)). The complex [PtCl2(TeMes2)2] in refluxing THF afforded a mononuclear cyclometalated complex [PtCl{(CH2C6H2Me2-4,6)TeMes}(TeMes2)] (2). It tends to remain in equilibrium with a binuclear derivative [Pt(μ-Cl){(CH2C6H2Me2-4,6)TeMes}]2 (3) in CDCl3 solution. The complexes 1d and 1e did not undergo cyclometalation reaction under similar reaction conditions. The 2 on treatment with PPh3 gave [PtCl{(CH2C6H2Me2-4,6)TeMes}(PPh3)] (4). All the complexes have been characterized by elemental analysis and NMR (1H, 31P, 125Te, 195Pt) spectroscopy. Anagostic interactions have been recognised for facilitation of cyclometalation reactions. The molecular structures of trans-[PtCl2(TeMes2)2] (1c), trans-[PtCl2(PhTeMes)2] (1d), trans-[PtCl2(o-tolTeMes)2] (1e), [PtCl{(CH2C6H2Me2-4,6)TeMes}(TeMes2)] (2) and [PtCl{(CH2C6H2Me2-4,6)TeMes}(PPh3)] (4) have been established unambiguously by single crystal X-ray diffraction analyses.

Graphical abstractTelluroether complexes of the type trans-[PtCl2(TeRRʹ)2] (R/Rʹ = Ph2, o-tol2, Mes2, Ph/Mes, o-tol/Mes), cycloplatinated complex [PtCl{(CH2C6H2Me2-4,6)TeMes}(TeMes2)] and [PtCl{(CH2C6H2Me2-4,6)TeMes}(PPh3)] have been isolated and characterized. Role of anagostic interaction in the cyclometalation of telluroether ligands has been demonstrated.Figure optionsDownload full-size imageDownload as PowerPoint slide