121Sb, 57Fe and 127I Mössbauer spectroscopic study on antimony-transition metal bond in metal carbonyl derivatives of tertiary stibines

Antimony-transition metal bonds in five- or six-coordinate [M(CO)n(SbR3)] (M=Fe, Ru; n=4, M=Cr, Mo, W; n=5, R=Me, Ph), seven-coordinate [MI2(CO)3(SbPh3)L]− (M=Mo, W, L=PPh3, AsPh3) and [MI3(CO)3(SbPh3)]− (M=Mo, W) have been investigated using the 121Sb, 57Fe and 127I Mössbauer spectroscopy. Coordination of SbR3 to the transition metal atom results in the increase in the values of isomer shift and the decrease in the values of quadrupole coupling constant of the 121Sb Mössbauer spectra. This indicates that the lone pair electron of the stibine is transferred to the transition metal atom. The degree of the transfer increases in the order of Mo