T. Benincori et al., CHIRAL ATROPISOMERIC 5-MEMBERED BIHETEROAROMATIC DIPHOSPHINES - NEW LIGANDS OF THE BIBENZIMIDAZOLE AND BIINDOLE SERIES, Journal of organometallic chemistry, 529(1-2), 1997, pp. 445-453
Two new chiral atropisomeric biheteroaromatic diphosphines are describ
ed: 2,2'-bis(diphenylphosphino)-1,1'-bibenzimidazole (3a) and dimethyl
-1,1'-bis(diphenylphosphino)-2,2'-biindole (4a) structural characteriz
ation is given and configurational stability at room temperature demon
strated. The oxidation potential was recognized as a good tool to eval
uate the electronic availability of the phosphorus atom in the series
of biheteroaromatic diphosphines. Its value increases parallel to the
electronic demand of the heterocyclic system and also depends on the p
osition of the diphenylphosphino group. (C) 1997 Elsevier Science S.A.