Fe-57 Mossbauer spectroscopic studies on M(CO)(5)(azaferrocene) complexes (M=Cr, Mo, W). The crystal structures of W(CO)(5)(azaferrocene) and W(CO)(5)(2,5-dimethylazaferrocene)

Fe-57 Mossbauer spectroscopic studies on M(CO)(5)(azaferrocene) complexes (M = Cr, Mo, W) as well as the crystal structures of W(CO)(5)(azaferrocene) and W(CO)(5)(2,5-dimethylazaferrocene) are reported. The complexation of azaferrocene to the M(CO)(5) moiety brings about only a small change in the quadrupole splitting. The structures of both tungsten complexes reveal a significant shortening of the W-C bonds trans to the nitrogen. These data indicate that azaferrocene behaves as a relatively strong sigma-donor and there is no evidence for any pi-acceptor properties. (C) 1997 Published by Elsevier Science S.A.