SYNTHESES AND CRYSTAL STRUCTURES OF THE DIMERS OF A BIS(LITHIOAMINO)- AND A TRIS(LITHIOAMINO)-SILANE CONTAINING ELECTRON-DEFICIENT Li4N4 AND Li6N6 CLUSTERS

Article abstract of DOI:10.1016/S0022-328X(00)99529-9

The syntheses of 3SiPh and <3SiPh>2 (IV) are described, and their 1H NMR, infrared and Raman spectra are reported.Crystals of <2SiMe2>2 (III) belong to the space group C2/c with a 18.799(5), b 8.963(3), c 18.672(5) Angstroem, β 112.19(2)deg, Z=4 and R=0.084.There is a Li4 bis-phenoid at the core of the dimers, the two pairs of Li3 faces being linked by the two N-Si-N bridges.The molecular symmetry is roughly 42m (D_2d) although only two-fold crystallographic symmetry is required.The dimers IV are centered on 1 symmetry sites of the space group P1 with a 10.234(2), b 10.406(2), c 11.476(3) Angstroem, α 61.43(1), β 82.16(1), γ 73.28(1)deg, Z=1 and R=0.057.Each nitrogen atom is boded to a Li3 face of a Li6 trigonal antiprism with the Si atoms over the remaining two unbridged faces.The overall symmetry approaches 3m (D_3d).Factors determining the shapes of the Li4N4 and Li6N6 clusters of III and IV, respectively, are discussed.