Ion-molecule reactions of cyclopentadienyl- tricarbonylmanganese derivatives with 18-crown-6 in the gas phase

The ion-molecule reactions of 18-crown-6 (L) with ions produced from cymantrene and its derivatives under electron impact are studied. It is shown that RXC₅H₄MnL⁺ ions (RX = the substituent in the cyclopentadienyl ring) can be produced by two reaction pathways: (i) by the addition of RXC₅H₄Mn⁺ to crown ether; and (ii) by the exchange of carbonyl ligands in RXC₅H₄MnCO)_x⁺ ions (x = 1-2) for the macrocyclic molecule. The formation of RMnL⁺ ions, where R = H, Me, Ph, OH, NMe₂, proceeds via the substitution of C₅H₄X in the isomerized form of the decarbonylated ions (RMn⁺C₅H₄X) for L. The relative abundances of the RXC₅H₄MnL⁺ and RMnL⁺ ions provide information about the structure of the RXC₅H₄Mn⁺ ions. The probability of synthesizing stable “sandwich” species of the C₅H₄Mn⁺ type in the condensed phase is predicted.