Heterobimetallic (Imido)antimony/Lithium Cages Containing [Sb(NR)₃]^3- Trianions

The reactions of [Sb(NMe2)3] with the primary (amido)lithiums [PhCH2CH2N(H)Li]n, [CyN(H)Li]n (Cy = C6H11), [2,4-dmpN(H)Li]n [2,4-dmp = 2,4-(MeO)2C6H3], and [tBuN(H)HLi]n give the heterobimetallic cage complexes [{Sb(NCH2CH2Ph)3}2Li6·2THF] (1), [{Sb(NCy)3}2Li6·2HNMe2]·2C6H5CH3 (2), [Sb{N(2,4-dmp)}3]2Li6·2THF·2C6H5CH3 (3), and [{Sb(NBut)3}2Li6] (4), respectively. The low-temperature X-ray structures of 1−4 show that they are composed of 14-membered polyhedral cages constructed from the association of two [Sb(NR)3]3- trianions with six Li+ cations. Crystal data; 2, triclinic, P1̄, a = 12.775(6) Å, b = 13.191(9) Å, c = 11.015(5) Å, α = 111.55(4)°, β = 95.39(4)°, γ = 115.26(4)°; 3, triclinic P1̄, a = 10.435(4) Å, b = 12.654(5) Å, c = 14.278(6) Å, α = 75.31(4)°, β = 79.33(4)°, γ = 84.33(4)°; 4, monoclinic P21/c, a = 9.994(1) Å, b = 17.421(2) Å, c = 10.680(2) Å, β = 111.33(1)° (the structure of 1 being reported previously). Lewis base solvation of the N6Li6 substructures of 1−3 results in distortion and deformation of the Li frameworks. The structural variations in the cores of 1−4 indicate that the bonding in these species is dominated by the valence and bonding demands of the p block metal centers.