STERIC INFLUENCES ON THE RH-103 NMR CHEMICAL-SHIFTS OF RHODIUM(III) HALF-SANDWICH COMPLEXES

Rhodium-103 and phosphorus-31 chemical shifts and Rh,P coupling consta nts are reported for 59 rhodium complexes of the types RhCpX(2)(PR(3) ) (Cp = C(5)Me(5); X = Cl, Br, I; PR(3) = PMe(3), (PPr3)-Pr-i, P(n)Bu (3), PPh(3), PMePh(2), PMe(2)Ph), RhCpX(PR(3))Ph (X=Cl, Br, I, PR(3)= PMe(3), PMe(2)Ph, PMe(2)Ph(2), PPh(3)), RhCpBr(PR(3))(aryl), and of m iscellaneous mono- and dinuclear types. Rhodium shielding generally de creases as the steric requirement of the phosphine increases and a num ber of linear correlations with the Tolman cone angle of the phosphine ligand are reported. Variable para substitution on the aryl ligand ha s little effect on rhodium shielding.