A spectroscopic, electrochemical and structural study of polarizable, dipolar ruthenium(II) arsine complexes as models for chromophores with large quadratic non-linear optical responses

Autor:	Coe, Benjamin J., Beyer, Tim, Jeffery, John C., Coles, Simon J., Gelbrich, Thomas, Hursthouse, Michael B., Light, Mark E.
Zdroj:	Journal of the Chemical Society, Dalton Transactions; March 7, 2000, Vol. 2000 Issue: 5 p797-803, 7p
Abstrakt:	The new series of complex salts trans-[RuIICl(pdma)2L][PF6]2 [pdma = 1,2-phenylenebis(dimethylarsine); L = N-methyl-4,4'-bipyridinium (MeQ+) 2, N-phenyl-4,4'-bipyridinium (PhQ+) 3, N-(4-acetylphenyl)-4,4'-bipyridinium (4-AcPhQ+) 4, N-(2,4-dinitrophenyl)-4,4'-bipyridinium (2,4-DNPhQ+) 5 or N-(2-pyrimidyl)-4,4'-bipyridinium (2-PymQ+) 6] have been prepared. The known complex salt trans-[RuIICl(pdma)2(4,4'-bpy)]PF6 (4,4'-bpy = 4,4'-bipyridine) 1 exhibits an intense dπ(RuII)→π*(4,4'-bpy) metal-to-ligand charge-transfer (MLCT) absorption with λmax at 418 nm in acetonitrile, whilst 2–6 display dπ(RuII)→π*(L) MLCT bands with λmax values in the region 486–544 nm. The MLCT energy decreases as the electron-accepting ability of L increases, in the order L = MeQ+ < PhQ+ < 4-AcPhQ+ < 2,4-DNPhQ+ < 2-PymQ+. Cyclic voltammetric studies show that within the series 2–6, the energy of the Ru-based HOMO is almost constant, whilst that of the L-based LUMO decreases by ca. 0.4 eV moving from 2 to 6. Single-crystal structures of the complete series 1·DMF, 2, 3·MeCN, 4·Me2CO, 5·MeCN and 6 have been determined. Analysis of bond lengths and dihedral angles provides no evidence for ground state charge-transfer, despite the strongly dipolar, polarizable nature of these complexes.
Databáze:	Supplemental Index
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