B. Hong et al., LUMINESCENT AND REDOX-ACTIVE RUTHENIUM(II) AND OSMIUM(II) COMPLEXES WITH A RIGID ALLENE-BRIDGED POLYPHOSPHINE, Journal of the Chemical Society. Dalton transactions, (16), 1998, pp. 2615-2623
A series of monometallic and homo- and hetero-bimetallic Ru-II and Os-
II complexes with the polyphosphines 1,1'-bis(diphenylphosphino)ethene
(bppe) and 1,1',3,3'-tetrakis(diphenylphosphino)allene (tppa) have be
en prepared and characterized by P-31-{H-1} NMR spectroscopy elemental
analysis and fast atom bombardment mass spectral analysis. Their grou
nd-state properties (including electrochemical behavior and electronic
absorption) and excited-state properties (including luminescence, qua
ntum yields and MLCT excited state lifetimes) are reported herein. All
complexes exhibit room-temperature luminescence, with long-lived (MLC
T)-M-3 excited slates observed for monometallic and homobimetallic Os-
II complexes with both bppe and tppa ligands. In the heterobimetallic
Ru-II-Os-II complex [Ru(bpy)(2)(mu-tppa)Os(bpy)(2)][PF6] (bpy = 2,2'-b
ipyridine) the luminescence of the Ru(bpy)(2)-based unit is quenched b
y the connected Os(bpy)(2)-based unit via energy transfer across the t
ppa spacer containing the allene bridge. Two overlapping one-electron
oxidations, corresponding to the two MII-based moieties (M = Ru or Os)
bridged by the tppa spacer, are observed in the homobimetallic comple
xes.