Nucleophilic addition to η6-arenetricarbonylmanganese cations - the role of intermediates in the reactions with phosphines

Article abstract of DOI:10.1016/0022-328X(91)80052-L

The structures of adducts of phosphines (e.g.PEt3) with the η⁶-arenetricarbonylmanganese cations <(η⁶-XYC6H4)Mn(CO)3>⁺ (Ia, X = Y = H; Ib, X = Me, Y = H; Ic, X = Cl, Y = H; Id, X = Cl, Y = p-Me) in acetone have been determined by low-temperature 1H and 13C NMR spectroscopy.In all cases regiospecific exo addition occur at the arene ring with formation of η⁵-cyclohexadienylphosphoniumtricarbonylmanganese cations <(η⁵-XYC6H4PEt3)Mn(CO)3>⁺ with Ib giving meta addition only (IIb) and Ic and Id forming both meta and ortho adducts (IIc, IIIc and IId, IIId, respectively).Increase in temperature reverses the equilibria for IIa and IIb with formation of <(arene)Mn(CO)2(PEt3)>⁺ whereas IIc, IIIc and IId, IIId form fac-Mn(CO)3(PEt3)2Cl involving direct attack by the PEt3 at the chlorine-bearing ring carbon atom rather than through a metal-hydride intermediate.

Full text of DOI:10.1016/0022-328X(91)80052-L

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