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.