Reduction reactions of a 1,3,5-triphosphabenzene

The reactions of the triphosphabenzene, 1,3,5-P3C3Bu3t, with LiMH4, M = Al or Ga, lead to the triphosphabicyclo[3.1.0]hexanediyl metallate complexes, [{[Li(OEt2)][MH2((P3C3Bu3H2)-H-t)]}(2)], which give exo- and endo-isomers of a triphosphabicyclo[3.1.0]hexane, (P3C3Bu3H4)-H-t upon quenching. The related reaction of [AlH3(NMe3)]with 1,3,5-P3C3Bu3t affords three identifiable products, viz. a triphosphabicyclo[3.1.0]hexenyl complex, [AlH2((P3C3Bu3H)-H-t)(NMe3)], and two triphosphabicyclo[ 3.1.0] hexanediyl complexes, [AlH((P3C3Bu3H2)-H-t)(NMe3)] and [Al2H4((P3C3Bu3H2)-H-t)(NMe3)]. In contrast, the reactions of 1,3,5-P3C3Bu3t with either [GaH3(quin)], quin = quinuclidine, or Me3SnH lead only to the triphosphabicyclo[3.1.0] hexenyl complexes, [GaH2((P3C3Bu3H)-H-t)(quin)] and [Me3Sn((P3C3Bu3H)-H-t)]. Quenching of the former affords a triphosphabicyclo[3.1.0] hexene, (P3C3Bu3H2)-H-t, while quenching the latter gives its triphosphacyclohexa-1,4-diene valence isomer. Treatment of 1,3,5-P3C3Bu3t with GaI yields a GaI3 complex of the triphosphahexa-1,4-diene, [GaI3((P3C3Bu3H2)-H-t)], whilst treatment with the anionic Ga(I) heterocycle, [:Ga{N(Ar)C(H)}(2)](-), Ar = C6H3Pr2i-2,6, affords the known diphospholyl anion, [1,3-P2C3Bu3t](-) via a P-abstraction from the triphosphabenzene. Finally, reaction of the 1,3,5-triphosphacyclohexane, {P(OEt)C(H)(Bu-t)}(3), with thionyl chloride yields the unusual lambda(5),lambda(5),lambda(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.