Design and synthesis of copper complexes of novel ligands based on the pyridine thiolate group

Abstract

The versatile coordination properties of 2,2′-dipyridyldisulfide (dpds) enables a series of different copper complexes to be isolated in good yield, including [CuCl₂(μ-dpds)] (1) which has a one-dimensional helical structure and [Cu(μ-Cl)(μ-dpds)] (4) which has a two-dimensional sheet structure. Flexible movement of the disulfide group in the dpds ligand facilitates the formation of complexes with a diverse range of structures. Compound 1 transforms into 4 almost quantitatively on standing in contact with methanol. After prolonged standing 4 slowly converts to the stable, betain-containing product, [Cu(μ-1-(2-pyridine)pyridiniumthiolato)(μ-Cl)] (8) with the concomitant production of elemental sulfur. The bromide congener of 4 undergoes the same transformation. The free ligand, 1-(2-pyridine)pyridiniumthiolate, can be released from 8 by treatment with CN⁻. On treatment of bis(2-pyridylthio)methane (BPTM) with CuCl₂ [CuCl₂(BPTM)]_n (9) is formed. This complex has an infinite helical chain structure. Reaction between tris(2-pyridylthio)methane (TPTMH) and CuBr gave [CuBr(TPTM)] (12) and with [Cu(NCCH₃)₄]PF₆ in the presence of oxygen, the complex [Cu(CH₃CN)(TPTM)]PF₆ (14) is formed. Complex 14 is the first structurally characterised example of a complex containing a Cu(II)–C(sp³) bond.