Halogenation and Nucleophilic Quenching: Two Routes to E-X Bond Formation in Cobalt Triple-Decker Complexes (E=As, P; X=F, Cl, Br, I).

The oxidation of [(Cp'''Co) (μ,η  : η -E ) ] (E=As (1), P (2); Cp'''=1,2,4-tri(tert-butyl)cyclopentadienyl) with halogens or halogen sources (I , PBr , PCl ) was investigated. For the arsenic derivative, the ionic compounds [(Cp'''Co) (μ,η  : η -As X)][Y] (X=I, Y=[As I ] (3 a), Y=[Co Cl I ] (n=0, 2, 4; 3 b); X=Br, Y=[Co Br ] (4); X=Cl, Y=[Co Cl ] (5)) were isolated. The oxidation of the phosphorus analogue 2 with bromine and chlorine sources yielded the ionic complexes [(Cp'''Co) (μ-PBr ) (μ-Br)][Co Br ] (6 a), [(Cp'''Co) (μ-PCl ) (μ-Cl)][Co Cl ] (6 b) and the neutral species [(Cp'''Co) (μ-PCl )(μ-PCl)(μ,η  : η -P Cl ] (7), respectively.

Halogenation of the Hexaphosphabenzene Complex [(Cp*Mo) (μ,η :η -P )]: Snapshots on the Reaction Progress.

The oxidation of [(Cp*Mo) (μ,η :η -P )] (1) with halogens or halogen sources was investigated. The iodination afforded the ionic complexes [(Cp*Mo) (μ,η :η -P )(μ,η :η :η :η -P I )][X] (X=I , I ) (2) and [(Cp*Mo) (μ,η :η -P )(μ-PI )][I ] (3), while the reaction with PBr led to the complexes [(Cp*Mo) (μ,η :η -P )(μ-Br) ][Cp*MoBr ] (4) [(Cp*MoBr) (μ,η :η -P )(μ,η -P Br )] (5) and [(Cp*Mo) (μ-PBr )(μ-PHBr)(μ-Br) ] (6). The reaction of 1 with the far stronger oxidizing agent PCl was followed via time- and temperature-dependent P{ H} NMR spectroscopy.

Halogenation of Diphosphorus Complexes.

A systematic study of diverse halogenation reactions of the tetrahedral MoP ligand complex [{CpMo(CO)}(μ,η:η-P)] () is reported. By reacting with different halogenating agents, a series of complexes such as [(CpMo)(μ-P)(μ-PI)(μ-I)(I)(I)] (), [{CpMo(CO)}(μ-PBr)] (), [{CpMo(CO)}(CpMoBr)(μ-PBr)] (), [{CpMo(CO)}(μ-PCl)] (), and [{CpMo(CO)}(CpMoCl)(μ-PCl)] () were obtained. Whereas the reaction of toward various bromine and chlorine sources leads to similar results, a different behavior is observed in the reaction with iodine in which is formed.