REGIOSELECTIVITY IN THE GAS-PHASE REACTIONS OF THE O-CENTER-DOT- RADICAL-ANION WITH ETA-5-CYCLOPENTADIENYL)TRICARBONYLMANGANESE(I) AND A-5-METHYLCYCLOPENTADIENYL)TRICARBONYLMANGANESE(I) - FORMATION AND STRUCTURE OF C5H5MNON- AND C6H7MNON- (N=1,2) IONS

The gas-phase reactions of the O.- ion with (eta5-cyclopentadienyl)tri carbonylmanganese(I), CpMn(CO)3, and a5-methylcyclopentadienyl)tricarb onylmanganese(I), CH3CPMn(CO)3, have been studied with Fourier transfo rm ion cyclotron resonance. The main reactions are (i) proton abstract ion, (ii) loss of CO2, and (iii) expulsion of two or three CO molecule s from the collision complex. Initial attack on a CO ligand is the mai n process as indicated by experiments with O-18.- and the ion/molecule reactions of the product ions resulting from the loss of three CO mol ecules with water, aliphatic alcohols, methanethiol and SO2. The attac k on a CO ligand followed by loss of three CO molecules is suggested t o yield C5H5MnO- ions with a (cyclopentadienone)MnH- structure in the reaction with CpMn(CO)3 and (methylcyclopentadienone)MnH- ions if CH3C pMn(CO)3 is the substrate. A possible mechanism for the process leadin g to the indicated transformation of the Cp and CH3CP ligands into C5H 4O and CH3C5H3O ligands, respectively, is discussed together with the formation of (fulvene)Mn(OH)- ions following attack of O.- on CH3CpMn( CO)3. The (cyclopentadienone)MnH- and (methylcyclopentadienone)MnH- io ns react with N2O by oxygen atom abstraction to form C5H5MnO2- and C6H 7MnO2- ions, respectively.