Reduction reactions of a 1,3,5-triphosphabenzene

摘要

The reactions of the triphosphabenzene, 1,3,5-P_3C_3Bu~t_3, with LiMH_4, M = Al or Ga, lead to the triphosphabicyclo[3.1.0]hexanediyl metallate complexes, [{[Li(OEt_2)][MH_2(P_3C_3Bu~t_3H_2)]}_2], which give exo- and endo-isomers of a triphosphabicyclo[3.1.0]hexane, P_3C_3Bu~t_3H_4 upon quenching. The related reaction of [AlH_3(NMe_3)] with 1,3,5-P_3C_3Bu~t_3 affords three identifiable products, viz. a triphosphabicyclo[3.1.0]hexenyl complex, [AlH_2(P_3C_3Bu~t_3H)(NMe_3)], and two triphosphabicyclo[3.1.0]hexanediyl complexes, [AlH(P_3C_3Bu~t_3H_2)(NMe_3)] and [Al_2H_4(P_3C_3Bu~t_3H_2)(NMe_3)]. In contrast, the reactions of 1,3,5-P_3C_3Bu~t_3 with either [GaH_3(quin)], quin = quinuclidine, or Me_3SnH lead only to the triphosphabicyclo[3.1.0]hexenyl complexes, [GaH_2(P_3C_3Bu~t_3H)(quin)] and [Me_3Sn(P_3C_3Bu~t_3H)]. Quenching of the former affords a triphosphabicyclo[3.1.0]hexene, P_3C_3Bu~t_3H_2, while quenching the latter gives its triphosphacyclohexa-1,4-diene valence isomer. Treatment of 1,3,5-P_3C_3Bu~t_3 with GaI yields a GaI_3 complex of the triphosphahexa-1,4-diene, [GaI_3(P_3C_3Bu~t_3H_2)], whilst treatment with the anionic Ga(I) heterocycle, [:Ga{N(Ar)C(H)}_2]~-, Ar = C_6H_3Pri_2-2,6, affords the known diphospholyl anion, [1,3-P2C_3Bu~t_3]~- via a P-abstraction from the triphosphabenzene. Finally, reaction of the 1,3,5-triphosphacyclohexane, {P(OEt)C(H)(But)}_3, with thionyl chloride yields the unusual 5,5,5-1,3,5-triphosphacyclohexane, {P(O)(Cl)C(H)(Bu~t)}_2{P(OEt)(S)C(H)(Bu~t)}. Suggestions as to the mechanisms of a number of these reduction reactions are made and the crystal structures of seven compounds are reported.