Reduction reactions of a 1,3,5-triphosphabenzene

The reactions of the triphosphabenzene, 1,3,5-P3C3But3, with LiMH4, M = Al or Ga, lead to the triphosphabicyclo3.1.0]hexanediyl metallate complexes, Li(OEt2)]MH2(P3C3But3H2)]]2], which give exo- and endo-isomers of a triphosphabicyclo3.1.0]hexane, P3C3But3H4 upon quenching. The related reaction of AlH3(NMe3)] with 1,3,5-P3C3But3 affords three identifiable products, viz. a triphosphabicyclo3.1.0]hexenyl complex, AlH2(P3C3But3H)(NMe3)], and two triphosphabicyclo3.1.0]hexanediyl complexes, AlH(P3C3But3H2)(NMe3)] and Al2H4(P3C3But3H2)(NMe3)]. In contrast, the reactions of 1,3,5-P3C3But3 with either GaH3(quin)], quin = quinuclidine, or Me3SnH lead only to the triphosphabicyclo3.1.0]hexenyl complexes, GaH2(P3C3But3H)(quin)] and Me3Sn(P3C3But3H)]. Quenching of the former affords a triphosphabicyclo3.1.0]hexene, P3C3But3H2, while quenching the latter gives its triphosphacyclohexa-1,4-diene valence isomer. Treatment of 1,3,5-P3C3But3 with "GaI" yields a GaI3 complex of the triphosphahexa-1,4-diene, GaI3(P3C3But3H2)], whilst treatment with the anionic Ga(I) heterocycle, :GaN(Ar)C(H)]2]-, Ar = C6H3Pri2-2,6, affords the known diphospholyl anion, 1,3-P2C3But3]- 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 lambda5, lambda5, lambda5-1,3,5-triphosphacyclohexane, P(O)(Cl)C(H)(But)]2P(OEt)(S)C(H)(But)]. Suggestions as to the mechanisms of a number of these reduction reactions are made and the crystal structures of seven compounds are reported.