Substitution reactions of dinuclear alkenyl-bridged iron-cobalt complexes with alkynylphosphines and diphosphines

Abstract

Reaction of [(CO) 3FeCo(CO) 3]( μ-C(CO 2Me= = CH(CO 2Me) ( 1) with Ph 2PCCR produces: (i) mono-substituted [(Ph 2PCCR)(CO) 2FeCo(CO) 3]( μ-C(CO 2Me)=CH(CO 2Me (R=Me ( 4), Ph ( 6), tBu (8)) and [(CO) 3FeCo(CO) 2-(Ph 2PCCR)]( μ-C(CO) 2Me) =CH(CO 2Me) (R=Me ( 5), Ph ( 7), tBu ( 9), H ( 10)) and (ii) di-substituted [Ph 2CCR)(CO) 2-FeCo(CO) 2(Ph 2CCR)]( μ-C(CO 2Me)= CH(CO 2Me) (R=Ph ( 11), tBu ( 12), H ( 13) FeCo complexes. Alkenyl [(CO 4FeCo(CO) 3]( μ-CR′=CH 2] (R′=CO 2Me ( 2) or CO 2Et ( 3)) compounds also react with phosphinoalkynes, leading to the iron-substituted [(Ph 2PCCR)(CO) 3FeCo(CO) 3]( μ-CR′=CH 2) (R′=CO 2Me, R=Ph ( 14); R′=CO 2Et, R=Ph ( 14); R′=CO 2Et, R=Me ( 15)) R′=CO 2Et, 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( μ-(C(CO) 2Me)H] 2, the structure of which consists of two [FeCo(CO) 5( μ-(CO 2Me)=C(CO) 2MeH] units bridged by a dppe ligand bonded to two Co and two Fe atoms, respectively, and (ii) compound 19 of formula dppe[FeCo(CO) 4( μ-(CO 2Me)=C(CO 2Me)H], in which the dppe ligand bridges the FeCo bond. Reaction with dppm produces dppm[FeCo(CO) 5( μ-(CO 2Me)H] 2 ( 20) and [FeCo(CO) 5( μ-(CO 2Me= C(CO) 2MeH] ( 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 [(Co) 2(CO) 6( μ-Ph 2PCCR)) [FeCo(CO) 5(( μ-(CO 2Me=C(CO 2Me)H) ( 22– 26), which contain the Co 2(CO) 6 fragment coordinated to the CC bond of the phosphine ligand.