Coordination chemistry of di-2-pyridylmethane and related bridging ligands with silver(i), copper(ii), palladium(ii) and zinc(ii)

Abstract

Di-2-pyridylmethane (1) and the bridging ligands 1,1,2,2-tetra(2-pyridyl)ethane (2), 1,1,2,2-tetra(2-pyridyl)ethan-2-ol (3) and tetra(2-pyridyl)ethene (4) chelate to metal atoms with the formation of 6-membered chelate rings. The utility of these ligands in coordination chemistry and as metallosupramolecular synthons was probed by reaction with silver, copper, palladium and zinc salts. On reaction with AgNO₃ the model ligand, 1, formed a 1-D coordination polymer with an unusual bridging mode and with Cu(NO₃)₂ underwent oxidation to produce a Cu₆(L)₄ (L = 5, di-2-pyridylmethanediol) complex. The bridging ligands 2 and 4 formed several discrete dinuclear complexes, a [2 + 2]-dimetallomacrocycle and a 1-D coordination polymer. Ligand 3 was demonstrated to be less stable and underwent three different solvolysis reactions to give a range of products that were characterised by X-ray crystallography.