Synthesis, coordination chemistry and crystal structures of [2+2] macrocycles incorporating 2,6-bis(thiomethyl)pyridine sub-units

A series of potentially dinucleating [2 + 2] macrocyclic ligands with two SNS metal-binding domains separated by a variable polymethylene chain have been prepared. Two examples of these ligands have been structurally characterised. These ligands form polymeric adducts with [Rh-2(O2CCMe3)(4)] in which the ligands are thought to act as exocyclic S-donors to the axial sites of the dinuclear complex. In contrast, reaction with [(CO)(2)Rh(mu-Cl)(2)Rh(CO)(2)] resulted in the formation of dinuclear complexes in which two Rh(CO) units are bound to each macrocyclic ligand. (C) 1998 Elsevier Science Ltd. All rights reserved.