Abstract
A series of six heterobimetallic carbonyl anions containing Fe and group 6 metals have been synthesized and characterized by spectroscopic techniques, chemical reactivity, and X-ray crystallography. The structural features common to all complexes are terminal CO groups and an Fe-M (M = Cr, W) bond. This bond is viewed as an Fe: [rightward arrow] M donor-acceptor complex in which electron density from Fe^δ- is donated to an electrophilic group 6 metal pentacarbonyl moiety. These complexes have metal-metal bond lengths ranging from 2.878(2)Å for MeFeW(CO)9- to 3.012(3)Å for Ph3PAuFeW(CO)[9]- . The hydride ligand in all hydride complexes reported herein was not crystallographically located, but dimer disruption reactions, molecular orbital calculations, comparisons of isolobal compound structures, and coordination sphere variations all suggest the hydride to be in a terminal position on Fe. The series of donor-acceptor metal complexes have been studied by various spectral (IR, ^13C-NMR, ^1H-NMR, UV-Vis) and chemical characterizations. Simplified v(CO) vibrational analysis for HFeW(CO)9 - was successful using a local symmetry approach. Others in the series showed considerable band overlapping and coupling of vibrations. The conjugate base, FeM(CO)9= , obtained from the deprotonation of HFeW(CO)9- , was found to react with a variety of electrophiles to generate new and exciting complexes. A series of donor-acceptor complexes of the type XFeM(C0)8L- (M = Cr, W; X = H, Me; L = CO, P(OMe)3) were kinetically studied in the dimer disruption reactions with the scavenging reagent PPh3. Investigation of the donor-acceptor complexes found that subtle differences in their structural features are reflected in greatly altered chemical behavior.
Arndt, Larry William (1986). Transition metal complexes containing donor-acceptor metal-metal bonds. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -21186.