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Abstract:
The syntheses and molecular and electronic structures of the following complexes have been established by single crystal X-ray crystallography and UV-vis-NIR spectroscopy, and verified by density functional theory calculations (DFT B3LYP): [(eta(5)-Cp)(2)Zr-IV(tpy(2-))](0) (S = 0) 1, [(eta(5)-Cp)(2)Zr-IV-((OMe)pdi(2-))](0) (S = 0) 2, [Co-II((OMe)pdi(center dot))(eta(2)-BH4)](0) (S = 0) 4, [Ru-II((OMe)pdi-H)Cl(PPh3)(2)](0) (S = 0) 5, cis-[Ru-II((OMe)pdi(0))Cl-2(PPh3)](0) (S = 0) 6, and [Run(II)(eta(2)-(OMe)pdi(0))(eta(2)-(OMe)pdi-H)(2)](0) (S = 0) 7, with (tpy(0)) being neutral 2,2':6',2'-terpyridine, (tpy(center dot))(1-) its pi radical anion, (tpy(2-))(2-) its dianion; ((OMe)pdi(0)) neutral 2,6-bis(4-methoxyphenylmethylimine)pyridine, ((OMe)pdi(center dot))(1-) its radical anion and ((OMe)pdi(2-))(2-) its dianion; ((OMe)pdi-H)(1-) represents the deprotonated form of the ((OMe)pdi(0)) ligand where deprotonation takes place at the meta-position of the pyridine ring. Density functional theory calculations using the B3LYP functional were performed, establishing geometry optimized molecular and electronic structures. The structural parameter Delta = [(average distance C-py-C-imine) - (av. distance C-py - N-py + av. distance C-imine-N-imime)] is introduced for the characterization of the oxidation level of pdi (and analogously of tpy) ligands of M(pdi) (or M(tpy)) motifs for first row transition metals. The M(L-0) unit in second and third row low-valent transition metal ion complexes may exhibit significant pi-backdonation M -> L-0 structural effects.
