Synthesis and Characterization of η⁵-1,2,4-Diazaphospholide Complexes of Ruthenium^†

Treatment of the 1,2,4-diazaphospholide anions [3,5-tBu2dp]- (1) and [3,5-Ph2dp]- (2) with [Cp*RuCl]4 affords the two complexes [(η5-3,5-tBu2dp)RuCp*] (3) and [(η5-3,5-Ph2dp)RuCp*] (4) (dp = 1,2,4-diazaphospholide), which are the first examples of sandwich complexes derived from 1,2,4-diazaphospholide ligands. The X-ray crystal structure analysis of 3 reveals that the metal atom is π-bonded to the 1,2,4-diazaphospholide ligand. The bonding was rationalized by DFT calculations.