REACTIONS OF DITERTIARY PHOSPHINES WITH ETA-6-ARENETRICARBONYLMANGANESE CATIONS

Ditertiaryphosphines PPh2(CH2)nPPh2 (n = 1-3) react at room temperature with the eta-6-arenetricarbonylmanganese cations [(eta-6-XYC6H4)Mn(CO)3]+ (Ia, X = Y = H; Ib, X = Me, Y = H) by monocarbonyl substitution and formation of [(eta-6-XYC6H4)Mn(CO)2(eta-1-PPh2(CH2)nPPh2)]+. Prolonged refluxing results in metal-ring bond breaking and formation of cis- and trans-[Mn(CO)2(eta-2-PPh2CH2PPh2)2]+ and trans-[Mn(CO)2(eta-2-PPh2(CH2)2PPh2)2]+. Activation of a carbonyl group in [(eta-6-XYC6H4Mn(CO),(eta-1-PPh2(CH2)nPPh2)]+ by TMNO gives the series of chelate complexes [(eta-6-XYC6H4Mn(CO)(eta-2-PPh2(CH2)nPPh2)]+ (n = 1-3). The X-ray structure of the chelate with n = 3 is reported. In the case of [(eta-6-XYC6H4)Mn(CO)3]+ (Ic, X = Cl, Y = H); Id, X = Cl, Y = Me), formation of fac-Mn(CO)3(eta-2-PPh2(CH2)nPPh2)Cl (n = 1, 2) occurs, in a reaction analogous to that with monophosphines, see D.A. Brown, W.K. Glass and K.M. Kreddan, J. Organomet. Chem., 413 (1991) 233, but there was no evidence for ring adducts as intermediates.