Synthesis and structural characterization of acetatobis(triphenylphosphine)dicarbonylrhenium(I). new car☐ylato derivatives of rhenium(I)

Acetatobis(triphenylphosphine)dicarbonylrhenium (I), (PPh3)2(CO)2Re(O2CCH3), has been prepared in a novel way by treating (PPh3)2(CO)2Re(NHCOR) (R = C6H5, p-MeC6H4) with triethylamine and water in the presence of air. Oxidation of the ethyl group of the tertiary amine is presumably involved in the formation of the acetate ligand. Three-dimensional single-crystal X-ray diffraction analysis shows that the complex is octahedral with the phosphines in transpositions and the acetate ion acting as a chelating ligand. The complex crystallizes in theP21/c space group with cell dimensions a= 17.63(2), b= 9.72(1), c= 20.95(2)Å, β = 104°38'(6'), Z= 4. The mean values of bond lengths observed are Re-P 2.415, Re-O 2.21 and Re-(CO) 1.85Å. The same acetate derivative and a series of car☐ylato complexes (PPh3)2(CO)2Re(O2CR') have been obtained from reactions of Re(CO)2(PPh3)3H with car☐ylic acids R'COOH (R' = H, CH3, CH2Cl, CH2CH3, C6H5). When trifluoroacetic acid is used, a product of formula (PPh3)2(CO)3Re(OC(O)CF3) is isolated. The action of neutral ligands L on some of these products gave rise to derivatives of formula (PPh3)2(CO)2(L)Re(OC(O)R') (L = CO, R' = H, CH3, C6H5; L = pMeC6H4NC, R' = CH3), having monodentate car☐ylato moieties.