SUBSTITUTION AND ADDITION-REACTIONS OF TRICARBONYL(ETA-1,5-CYCLOHEXADIENYLIUM)IRON AND TRICARBONYL(ETA-1,5-CYCLOHEPTADIENYLIUM)IRON CATIONSWITH TERTIARY DIPHOSPHINES

A new series of metal diphosphine complexes formed by the reaction of the diphosphines, PPh2(CH2)nPPh2, n = 2-6, with the tricarbonyl(eta-1, 5-cyclohexadienylium)- and tricarbonyl-(eta-1,5-cycloheptadienylium)ir on cations are described. The first series, formed by dppm (n = 1) onl y, comprise 5-exo ring adducts involving the bonding of only one phosp horus atom of the diphosphine to ring carbon atom 5 of the tricarbonyl cyclodienyliron cation. The second series are diphosphine ring linked dimers, e.g. 5'-exo-PPh2(CH2)3PPh2{(eta4-C6H7)Fe(CO)3}2](BF4)2. The st ructures of the members of both series are fully consistent with their spectroscopic properties, and in one case, the ring adduct [(eta4-C7H 9-5-exo-eta1-dppm)Fe(CO)3]BF4, the structure was confirmed by X-ray cr ystallography.