High energy photoelectron spectroscopy of transition metal complexes. Part 4.—Bis(arene) and related complexes of chromium, manganese and iron

The X-ray photoelectron (ESCA) spectra of a series of bis(arene)- and arene(tricarbonyl)-metal complexes have been measured in the solid state. The binding energies have been interpreted as far as possible with the aid of ab initio SCF MO calculations of [(η-C6H6)Cr(CO)3] and [(η-C6H6)2Cr] and semi-empirical molecular orbital calculations on most of the other compounds. The arene ring bears a small negative charge in neutral bis(arene) complexes. The arene ring in an arene(tricarbonyl) complex has a lower electron density than in a comparable bis(arene) complex. There is no experimental evidence for the dependence of charge density upon the size of an arene ring.