Reactions of the phosphinidene-bridged complexes [Fe_2(η ~5-C_5H_5)_2(μ-PR)(μ-CO)(CO) _2] (R = Cy, Ph) with electrophiles based on p-block elements

摘要

The title complexes reacted readily with the methylating agents MeI and CF_3SO_3Me, chalcogens (O_2, S_8) and borane adducts BH_3·L (L = THF, N~tBu_3, PPh_3) to initially give the corresponding neutral or cationic derivatives of the type [Fe_2Cp_2{μ-P(E)R}(μ-CO)(CO) _2]~n (Cp = η~5-C_5H_5; n = 0, E = O, S, BH_3; n = +1, E = Me), which could be further functionalized through additional reactions. Thus, the oxophosphinidene complex [Fe_2Cp_2{μ-P(O)Cy}(μ-CO)(CO)_2] could be protonated or alkylated with HBF_4·OEt_2 or CF _3SO_3Me, to give the complexes [Fe_2Cp _2{μ-P(OR′)Cy}(μ-CO)(CO)_2]+ (R′ = H, Me) respectively, while the photochemical treatment of compounds [Fe_2Cp_2{μ-P(BH_3)R}(μ-CO)(CO) _2] gave the dicarbonyl derivatives [Fe_2Cp _2{μ-κ~1:κ~1,η~2- P(BH_3)R}(μ-CO)(CO)], with a phosphinidene-borane ligand displaying coordination of a B-H bond to one of the iron atoms in a side-on fashion (Fe-H = 1.78(4) ?, Fe-B = 2.351(5) ? for the PCy compound). The title complexes also reacted readily with 3,5-di-tert-butyl-o-benzoquinone or benzyl azide. The first reaction gave the phosphonite complex [Fe_2Cp _2(μ-CO)_2(CO){P(O_2C_6H _2 ~tBu_2)R}], while the second reaction yielded initially the corresponding 1:1 adducts [Fe_2Cp_2{μ- P(N_3CH_2Ph)R}(μ-CO)(CO)_2], with a P:P-bound phosphatriazadiene ligand. The PCy compound underwent clean denitrogenation in toluene at 368 K to give the iminophosphinidene complex [Fe_2Cp _2{μ-P(NCH_2Ph)Cy}(μ-CO)(CO)_2], which in turn could be protonated selectively with [NH_4]PF_6 at the P-bound nitrogen atom, to yield the aminophosphide derivative [Fe _2Cp_2{μ-P(NHCH_2Ph)Cy}(μ-CO)(CO) _2]PF_6 (Fe-Fe = 2.6362(8) ?). Denitrogenation could be also induced photochemically on the phosphatriazadiene complex, but this also caused fragmentation and recombination of different bonds to give the trinuclear compound [Fe_3Cp_3(μ_3-PCy){μ- κ~1:κ~1-C(O)(NHCH_2Ph)}(μ-CO) _2], having phosphinidene and C:O-bound aminoacyl ligands bridging the metal atoms.