THERMALLY AND PHOTOCHEMICALLY INDUCED COORDINATION CHANGES IN RUTHENIUM(II) BIS(2,2'-BIPYRIDINE) COMPLEXES CONTAINING PYRIDYLTRIAZOLE LIGANDS

A series of Ru(II)(bipy), complexes (bipy = 2,2'-bipyridine) containing monodentate co-ordinated pyridyltriazole ligands has been prepared and characterised. The species are obtained by either thermal or photochemical methods. The co-ordination mode of the products obtained has been investigated using spectroscopic techniques. The molecular structure of one of the products, bis(2,2'-bipyridine)chloro-[3-methyl-1-(pyridin-2-yl)-1,2,4-triaz ole]ruthenium(II) hexafluorophosphate, has been determined. The compound crystallises in the triclinic space group P1BAR with unit-cell parameters a = 8.599(12), b = 1 3.503(16), c = 16.526(16) angstrom, alpha = 89.88(9), beta = 117.22(8), gamma = 111.08(10)-degrees and Z = 2. The pyridyltriazole is co-ordinated via the N4 nitrogen atom. In the compounds containing monodentate 4-methyl-3-(pyridin-2-yl)-1,2,4-triazole the ligand is most likely co-ordinated via the N1 atom. The conversion of the photoproduct acetonitrilebis(2,2'-bipyridine)[4-methyl-3-(pyridin-2-yl)-1,2,4-triazole]ruthenium(II) into the parent complex containing the chelating pyridyltriazole ligand by thermal as well as photochemical methods is reported.