Journal of Organomefallic Chemistry, 101(1975) 63-69 @ Elsevier Sequoia S-A., Lausanne-Printed in The Netherlands A CARBON-13 NMR STUDY OF PHOSPHINE, PHOSPHITE, ARSINE AND STIBINE LIGANDS AND THEIR LNi(CO), , LCr(CO)5 AND q-(C5HS)Mn- (CO)*L COMPLEXES

13C NMR chemical shift and J(13C31P) coupling constant data are presented for PPh3_,Me, (n = 0,l and 2), P(OPh)3, PEta, AsPh3 and SbPh3 ligands, and some corresponding LNi(CO)3, LCT(CO) ~ and q-(CSH5)Mn(C0)2L complexes. Anal-ysis of the 13C NMR chemical shift data for the C(4) resonance in these C6H5X derivatives suggests: (1) a resonance substituent parameter R = 0.005 for X = PPh, and R = 0.09 for X = (CO),CrPPh, , (2) a decrease in the resonance inter-action of the Group VA atom with the phenyl ring in EPh, derivatives in the order E = P> +s> Sb, and (3) an increase in the electron density at the phos-phorus atom in PPh,_,Me, derivatives in the order: PPh3 < PPhzMe < PPhMez. There appears to be an anomalous shielding of the C(1) resonance in these deriva-tives upon complexation, and with increasing electronegativity of the Group Va atom. The electron-withdrawing character of the metal carbonyl moiety appears to increase in the order: q-(CsHs)Mn(CO),L < LNi(CO)3 < LCI$CO)~. The mag-nitude of the 1J(‘3C31P) and 3J(‘3C31P) coupling in trialkyl and triaryl phosphines increases upon complexation, while the magnitude of the *J(13C3’P) couplin