Trends in the Spectrochemical Series and 31 P Chemical Shifts of Five-coordinated Cyclopentadienylnickel(II) Complexes

Abstract

The electronic spectra and 31 P n.m.r. spectra of the complexes π-C 5 H 5 NiPPh 3 X (X = Cl, Br, I, NCO, NCS, NO 2 , CN, SnCl 3 , SnPh 3 , PbPh 3 , alkyl, and aryl) have been obtained and interpreted. The "common" anions form a spectrochemical series which is identical with that reported for many octahedral systems, while the carbon, tin, and lead donors lie relatively high in the series. Currently accepted theory for the chemical shifts of ligand donor atoms fails to satisfactorily rationalize the 31 P chemical shifts.