A Novel Route to Formaldehyde and Thioformaldehyde Rhodium Complexes

Abstract

The acetoxymethyl rhodium compounds [(η5‐C5R5)Rh(CH2OAc)(L)I] (4, 13–16) which were prepared from the chloromethyl derivatives [(η5‐C5R5)Rh(CH2Cl)(L)I] and sodium acetate in benzene/acetic acid as solvent, reacted with AgPF6 to give the chelate complexes [(η5‐C5R5)Rh{ĸ2‐C,O‐CH2OC(Me)O}(L)]PF6 (19–23) in excellent yields. Treatment of these complexes with KOH in methanol led to the elimination of the acetyl group and to the formation of the formaldehyde compounds [(η5‐C5R5)Rh(η2‐CH2O)(L)] (24–27). The related thioformaldehyde complexes [(η5‐C5Me5)Rh(η2‐CH2S)(L)] (46, 47) and [(η5‐C5H5)Rh(η2‐CH2S)(PMe3)] (50) were obtained on a similar route. Studies on the reactivity of the formaldehyde derivatives revealed that the Rh–CH2O bond is rather labile and the CH2O ligand easily converted to a CO group.