Synthesis and Reactivity of Ru(PPh₃)₃(CO)HF and the N-Heterocyclic Carbene Derivatives Ru(NHC)(PPh₃)₂(CO)HF

Abstract

The reaction of Ru(PPh 3 ) 3 (CO)H 2 with excess Et 3 N·3HF at elevated temperature affords the hydride fluoride complex Ru(PPh 3 ) 3 (CO)HF ( 1) . This reacts with a series of N-heterocyclic carbenes (NHCs) at ambient temperature to form the mono-NHC products Ru(NHC)(PPh 3 ) 2 (CO)HF (NHC = IMe 4 ( 2 ), IEt 2 Me 2 ( 3 ), ICy ( 4), I i Pr 2 Me 2 ( 5 )). Complexes 2 − 4 convert from the trans- to cis-phosphine isomers in solution over weeks (relative rates 2 > 3 ≫ 4), while 5 undergoes both isomerization and disproportionation to yield cis -Ru(I i Pr 2 Me 2 )(PPh 3 ) 2 (CO)HF ( 6 ), 1, and Ru(I i Pr 2 Me 2 ) 2 (PPh 3 )(CO)HF ( 7 ) in a matter of hours. The molecular structures of compounds 1 − 4 have been determined by X-ray crystallography.