IODIDE COMPLEXES OF DECABORANE(L4) AND 2,4-DIIODODECABORANE(14) - THEX-RAY CRYSTAL-STRUCTURE OF [P(C6H5)(3)CH3][2,4-I2B10H12I]

A yellow, solid, ion-dipole charge transfer complex, [M][B10H14I], is formed upon mixing the solids [M]I (M = [N(n-(C4H9)(4)](+), [P(C6H5)(3 )CH3](+), [(Ph(3)P)(2)N](+)) and B10H14. The [B10H14I](-) ion is stabi lized in the solid state by the presence of bulky cations; B10H14 cann ot be separated by sublimation from the solid. A Job continuous variat ions experiment establishes that the reaction stoichiometry, a 1:1 mol ar ratio of [N(n-(C4H9)(4)]I to B10H14, also occurs in CH2Cl2 solution . While there is no apparent reaction when solid alkali metal iodides are mixed with B10H14 in the absence of a solvent, addition of an appr opriate solvent to the solid mixture causes formation of the [B10H14I] (-) anion. However, removal of the solvent causes the complex to rever t to a mixture from which B10H14 can be removed by sublimation. When 2 ,4-I2B10H12 is mixed with iodide salts of the cations [N(n-C4H9)(4)]() [P(C6H5)(3)CH3](+), [(Ph(3)P)(2)N](+), Na+, and K+ in the absence of a solvent, there is no apparent reaction. However when a suitable sol vent is present, the complex anion [2,4-I2B10H12I](-) is formed. A sin gle crystal X-ray structure determination of [P(C6H5)(3)CH3][2,4-I2B10 H12I] shows the unique iodide residing on top of the four hydrogen bri dge atoms and the 6,9 boron atoms at the opening of the B-10 basket. C rystal data for [P(C6H5)(3)CH3][2,4-I2B10H12I]: monoclinic P2(1)/c, a = 12.868(4) Angstrom, b = 10.562(3) Angstrom, c = 22.007(8) Angstrom, beta = 99.40(2)degrees, Z = 4, V = 2950.7 Angstrom(3), R = 3.3%, R(w) = 3.6%.