SUBSTITUTION-REACTIONS OF DINUCLEAR ALKENYL-BRIDGED IRON-COBALT COMPLEXES WITH ALKYNYLPHOSPHINES AND DIPHOSPHINES

Reaction of [(CO)(3)Fe-Co(CO)(3)](mu-C(CO(2)Me) = CH(CO(2)Me) (1) with Ph(2)PC=CR produces: (i) mono-substituted [(Ph(2)PC=CR)(CO)(2)Fe-Co(C O)(3)](mu-C(CO(2)Me) (R=Me (4), Ph (6), (t)Bu (8)) and Fe-Co(CO)2-(Ph( 2)PC=CR)](mu-C(CO(2)Me)=CH(CO(2)Me) (R=Me (5), Ph (7), (t)Bu (9), H (1 0)) and (ii) di-substituted Fe-Co(CO)(2)(Ph(2)C=CR)](mu-C(CO(2)Me)=CH( CO(2)Me) (R=Ph (11), (t)Bu (12), H (13)) Fe-Co complexes. Alkenyl [(CO )(4)Fe-CO(CO)(3)](mu-CR'=CH2)] (R' = CO(2)Me (2) or CO(2)Et (3)) compo unds also react with phosphinoalkynes, leading to the iron-substituted [(Ph(2)PC=CR)(CO)(3)Fe-Co(CO)(3)](mu-CR'=CH2) (R'=CO(2)Me, R=Ph (14); R'=CO(2)Et, R=Ph (15); R'=CO(2)Et, R=Me (16)) compounds. The reaction of 1 with dppe gives a mixture of two types of product: (i) compounds 17 and 18 of formulae dppe[FeCo(CO)(5)(mu-(CO(2)Me)H](2), the structu re of which consists of two [FeCo(CO)(5)(mu-(CO(2)Me) = C(CO(2)Me)H] u nits bridged by a dppe ligand bonded to two Co and two Fe atoms, respe ctively, and (ii) compound 19 of formula dppe[FeCo(CO)(4)(mu-(CO(2)Me) =C(CO(2)Me)H], in which the dppe ligand bridges the Fe-Co bond. Reacti on with dppm produces dppm[FeCo(CO)(5)(mu-(CO(2)Me)=C(CO(2)Me)H](2) (2 0) and [FeCo(CO)(5)(mu-(CO(2)Me)=C(CO(2)Me)H] (21), the structures of which are similar to those of compounds 17 and 19. The monosubstituted phosphinoalkyne Fe-Co complexes react with Co-2(CO)(8) to form a new family of products 2)PC=CR))[Fe-Co(CO)(5)]((mu-(CO(2)Me)=C(CO(2)Me)H) (22-26), which contain the Co-2(CO)(6) fragment coordinated to the C=C bond of the phosphine ligand.