TRANSITION-METAL ALKYLGALLYL COMPLEXES - SYNTHESIS, STRUCTURE, AND SPECTROSCOPIC STUDIES OF (ETA(5)-C5H5)(CO)(2)FEGA(T-BU)(2), ((ETA(5)-C5H5)(CO)(2)FE)(2)GA(T-BU), AND (ETA(5)-C5H5)(CO)(2)FEGA(T-BU)(2)CENTER-DOT((ETA(5)-C5H5)(CO)(2)FE)(2)

The preparation and crystallographic and spectroscopic (H-1 and C-13 NMR and IR) characterization of three new transition metal complexes featuring terminal alkylgallyl groups are described. The compounds (eta5-C5H5)(CO)2FeGa(t-Bu)2 (1), (eta5-C5H5)(CO)2Fe}2Ga(t-Bu) (2), and (eta5-C5H5)(CO)2FeGa(t-Bu)2.{eta5-C5H5)(CO)2Fe}2 (3) were synthesized by a simple salt elimination reaction between NaFe(eta5-C5H5)(CO)2 and (t-Bu)2GaCl or t-BuGaCl2 in the appropriate ratio to give 1 or 2 in good yield. The addition of {(eta2-C5H5)(CO)2Fe}2 to 1 affords the adduct 3. In 1 and 2 the average Fe-Ga distances are 2.413(4) and 2.411(5) angstrom. In the case of 3, an oxygen from a bridging carbonyl of the dimer {(eta5-C5H5)(CO)2Fe}2 serves as a donor atom to the gallium center of (eta2-C5H5)(CO)2FeGa(t-Bu)2 (i.e. 1), and the Fe-Ga distance is slightly lengthened to 2.441 (1) angstrom. These distances, in addition to the IR spectra of the carbonyl region, suggest that any pi-interaction between the iron and the gallium p-orbital is probably very weak.