Crystal structure and IR spectroscopic study of the products of iodinationof the [B12H11(SCN)](2-) anion

The iodination of Cs-2[B12H11(SCN)] in a water-propanol solution followed b y ion exchange yields the compounds [(C6H5)(4)P](2)[B12H10(I, SCN)(2)] (I) and [(C6H5)(4)P]I(II) The compounds are characterized by IR spectroscopy an d X-ray crystallography. Crystals of I are monoclinic: a = 9.924(2) Angstro m, b = 11.196(3) Angstrom, c = 12.656(3) Angstrom, alpha = 76.69(3)degrees, beta = 73.23 degrees, gamma = 66.82(3)degrees, Z = 1, space group P (1) ov er bar. Crystals of II are tetragonal: a = 11.967(2) Angstrom, c = 6.974(2) Angstrom, Z = 2, space group I (4) over bar. Compounds I and II are ionic. The P-C bond length in cations I and II is 1.79 +/- 0.01 Angstrom. The [B1 2H10(I, SCN)(2)](2-) anion in I is an icosahedron of boron atoms. The I ato ms and SCN groups in the ratio 2 :3 randomly substitute for the hydrogen at oms in the 1- and 12-positions. The following bond lengths are found: B-B(a v), 1.78(2) Angstrom; B-I, 2.33(2) Angstrom; B-S, 1.91(3) Angstrom.