Studies of 2,5;6,10;8,10-tri-μ-hydro-nonahydro-nido-nonaborate(1-) [B9H12]- have involved new syntheses, which have led to crystals suitable for the determination of the X-ray crystal and molecular structure, through reactions of B9H13(SMe2) with [OCN]- or other bases. Crystallographic study of [N(PPh3)2] [B9H12] reveals the structure of the anion to be that of a nido-nine-vertex cage, based on the parent bicapped square antiprism with one 5-connected vertex removed. The pentagonal open face is symmetrically bridged by three (μ-H) atoms (two involving the lowest connected boron), conferring effective Cs symmetry upon the polyhedron. Crystals are monoclinic, space group P21/n, with a = 26.759(10), b = 10.340(4), c = 27.044(5) Å, β = 103.47(2)°, and Z = 8. Using 6 777 diffracted intensities recorded at 185 K on an Enraf-Nonius CAD4 diffractometer, the structure has been refined to R 0.0847, R′ 0.1216. The 11B, two-dimensional 11B(COSY), and 1H n.m.r. parameters all confirm the structural assignment and the n.m.r. spectra have been assigned unambiguously. Cyclic and a.c. voltammetry and coulometry of [B9H12]- in several solvents at Pt led to the electrochemical parameters and to an isomer-specific electrochemical synthesis of anti-[B18H21]-. Chemically, the [N(PPh3)2]+ salt of [B9H12]- reacted with HCl to give [B9H13Cl]-, whereas the [NBun4]+ salt yielded anti- B18H22; reactions with CF3CO2H gave primarily anti-[B18H21]-.
|Number of pages||10|
|Journal||Journal of the Chemical Society, Dalton Transactions|
|Publication status||Published - 1985|
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