TY - JOUR

T1 - Structural, electrochemical and UV/VIS/NIR spectroelectrochemical properties of diastereomerically pure dinuclear ruthenium complexes based on the bridging ligand phenanthroline-5,6-diimine, and a mononuclear by-product with a peripheral isoimidazole group

AU - Fletcher, Nicholas C.

AU - Robinson, Toby C.

AU - Behrendt, Andreas

AU - Jeffery, John C.

AU - Reeves, Zoe R.

AU - Ward, Michael D.

PY - 1999/9/7

Y1 - 1999/9/7

N2 - Mono- and di-nuclear ruthenium(II) complexes derived from the potentially bridging ligand 5,6-diamino-phenanthroline (dap) have been prepared and investigated. Reaction of dap (which has one 'bipyridyl-like' and one diamine co-ordination site) with [Ru(bipy)2Cl2] afforded [{Ru(bipy)2}2(μ-pdi)]4+, where pdi = phenanthroline-5,6-diimine, in which the diamine site has undergone a two-electron oxidation to give a quinone diimine site. The complex (as its hexafluorophosphate salt) could be separated chromatographically into its two diastereoisomers which were fully characterised independently, including the crystal structure of the homochiral diastereoisomer as its perchlorate salt. Electrochemical studies revealed six reversible reductions, of which the first two were shown by spectroelectrochemical studies to be centred on the bridging ligand (diimine/diiminosemiquinone and diiminosemiquinone/diamide couples), and the rest based on the terminal bipyridyl ligands. Although these six reductions occurred at identical potentials for both diastereoisomers, the separation between the two closely spaced RuII-RuIII couples varied slightly between the diastereoisomers indicating some sensitivity of delocalisation in the RuII-RuIII mixed-valence state to the optical configuration of the metal centres. The mononuclear complex [Ru(bipy)2(dap)]2+, in which the metal is co-ordinated at the bipyridyl site of dap with the diamine site vacant, easily reacts with acetone to give [Ru(bipy)2L]2+ where L is a phenanthroline derivative with a peripheral isoimidazole ring derived from condensation of one equivalent of acetone with the o-diamine group. The electrochemical, spectroscopic and luminescence properties of [Ru(bipy)2L]2+ are only slightly perturbed from those of [Ru(bipy)3]2+.

AB - Mono- and di-nuclear ruthenium(II) complexes derived from the potentially bridging ligand 5,6-diamino-phenanthroline (dap) have been prepared and investigated. Reaction of dap (which has one 'bipyridyl-like' and one diamine co-ordination site) with [Ru(bipy)2Cl2] afforded [{Ru(bipy)2}2(μ-pdi)]4+, where pdi = phenanthroline-5,6-diimine, in which the diamine site has undergone a two-electron oxidation to give a quinone diimine site. The complex (as its hexafluorophosphate salt) could be separated chromatographically into its two diastereoisomers which were fully characterised independently, including the crystal structure of the homochiral diastereoisomer as its perchlorate salt. Electrochemical studies revealed six reversible reductions, of which the first two were shown by spectroelectrochemical studies to be centred on the bridging ligand (diimine/diiminosemiquinone and diiminosemiquinone/diamide couples), and the rest based on the terminal bipyridyl ligands. Although these six reductions occurred at identical potentials for both diastereoisomers, the separation between the two closely spaced RuII-RuIII couples varied slightly between the diastereoisomers indicating some sensitivity of delocalisation in the RuII-RuIII mixed-valence state to the optical configuration of the metal centres. The mononuclear complex [Ru(bipy)2(dap)]2+, in which the metal is co-ordinated at the bipyridyl site of dap with the diamine site vacant, easily reacts with acetone to give [Ru(bipy)2L]2+ where L is a phenanthroline derivative with a peripheral isoimidazole ring derived from condensation of one equivalent of acetone with the o-diamine group. The electrochemical, spectroscopic and luminescence properties of [Ru(bipy)2L]2+ are only slightly perturbed from those of [Ru(bipy)3]2+.

U2 - 10.1039/a903556g

DO - 10.1039/a903556g

M3 - Journal article

AN - SCOPUS:33749102068

VL - 1999

SP - 2999

EP - 3006

JO - Journal of the Chemical Society - Dalton Transactions

JF - Journal of the Chemical Society - Dalton Transactions

SN - 0300-9246

IS - 17

ER -