A half-sandwich 1,2-azaborolyl (Ab) ruthenium complex, (Ab–CCPh)RuCl(PPh3)2 (1), has been synthesized by treating RuCl2(PPh3)3 with lithium 1,2-azaborolide L-1, or by treating either RuCl2(PPh3)3 or RuHCl(PPh3)3 directly with 1,2-azaborole LH-1. It is evaluated as a suitable precatalyst in [2 + 2] cycloadditions of norbornene derivatives with DMAD and in atom transfer radical additions of halogenated compounds with olefins.
Electron and energy transfer within dyads involving polypyridyl-ruthenium(II) and -osmium(II) centres separated by rigid alicyclic bridges
作者:Laurence S. Kelso、Trevor A. Smith、Austin C. Schultz、Peter C. Junk、Ronald N. Warrener、Kenneth P. Ghiggino、F. Richard Keene
DOI:10.1039/b003174g
日期:——
Rigid alicyclic frameworks (often referred to as molracs, relating to the molecular rack nature of the frame) have been used to vary the separation between organic electron-acceptor (quinone) moieties and chromophoric polypyridylruthenium(II) centres, and between metal centres in Ru–Ru and Ru–Os dinuclear complexes. Photophysical studies have allowed a preliminary insight into the effectiveness of such alicyclic structures in mediating intramolecular photoinduced energy and electron transfer. In the chromophore–spacer–quinone dyads, solvent-dependent quenching of the ruthenium(II) MLCT emission was observed and attributed to electron transfer processes. Distance and stereochemical dependencies of the quenching suggested that through-bond coupling was a factor in these systems. In the heterodinuclear systems, the photo-excited ruthenium(II) chromophore underwent intramolecular energy transfer to the osmium(II) component. A through-space Förster dipole–dipole mechanism could adequately account for the rate of the energy transfer process observed.