Rhodium carbonyl complexes of bulky, anionic nitrogen-based ligands: A comparison of donating ability

Phosphinimine-imine ((C6H3i-Pr2)NC(Me)CH2PPh2(NC6H3i-Pr2))Rh(CO)2 – (1) and β-diketiminate CH(C(Me)(Ni-Pr2C6H3))2Rh(CO)2 – (2) rhodium dicarbonyl complexes were prepared as to elucidate any difference among these anionic, nitrogen-based ligands regarding donating ability to the rhodium center. Utilizing infrared spectroscopy and single crystal structural comparisons, differences in electron density donation by the ligands to the rhodium center were not observed. The carbonyl stretching frequencies of the aforementioned rhodium complexes were νCO = 2055, 1987 and 2055, 1988 for the phosphinimine-imine (1) and β-diketiminate (2) respectively.

Rhodium carbonyl complexes of sterically similar, monoanionic β-diketiminate and phosphinimine-imine ligands are prepared and the carbonyl ligands studied to elucidate possible electronic differences in the systems.Figure optionsDownload as PowerPoint slideHighlights
► Two sterically similar, but structurally different Rh carbonyl complexes are prepared.
► The complexes are compared to determine electronic donating abilities of the ligands.
► β-diketiminate and phosphinimine/iminate ligands have similar donating capabilities.