Abstract
The coordinatively unsatd. compds. AlR3, GaR3 and ZnR2, R = iso-Pr, were reacted with linearly bridging pyrazine, tetramethylpyrazine or 4,4'-bipyridine ligands and with potentially chelating 2,2'-bipyridine. The primary reaction products are diamagnetic dinuclear complexes (bis-adducts) which are characterized by intense long-wavelength ligand-to-ligand charge transfer (LLCT) transitions s(M-R)$\rightarrow$ p*(L) and which may yield radical complexes after loss of R.bul.. The latter reaction is assumed to have a strong single electron transfer (SET) component. An isolable Al(II) species (bpy)AlCH(SiMe3)22 has been characterized unambiguously by ESR, UV-Vis and cyclic voltammetry as an Al(III) complex of the bpy radical anion. Irradn. into the fairly intense LLCT absorption bands (e \textgreater 3000 M-1 cm-1) of the dinuclear complexes between pyrazine and AliPr3 or GaiPr3 resulted in bleaching and formation of a mixt. of non-arom. products. Attempts are made to correlate charge transfer properties and radical formation with the geometrical and electronic structures of the precursor complexes. on SciFinder(R)
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