Cyclo-ruthenated and -platinated complexes bearing phosphonate substituents

Two new, potentially cyclometalating terdentate ligands bearing phosphonate substituents, Et2O3P-N^C(H)^N (5) and Et2O3P-C(H)^N^N (7), have been prepared. The corresponding ruthenium complexes, [1]+ and [2]+, respectively, were obtained by reaction with [RuCl3(tpy)]. Complexes [1]+ and [2]+ display electronic properties characteristic for cyclometalated ruthenium complexes. The platinum complex [3], of N^C(H)^N ligand 5, was also prepared and is highly phosphorescent in solution. In general, the phosphonate group electronically behaves equivalent to a carboxylate moiety.