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

The versatile coordination properties of 2,2'-dipyridyldisulfide (dpds) enables a series of different copper complexes to be isolated in good yield, including [CuCl2(mu-dpds)] (1) which has a one-dimensional helical structure and [Cu(mu-Cl)(mu-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(mu-1-(2-pyridine) pyridiniumthiolato)(mu-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(sp(3)) bond.