Journal
INORGANIC CHEMISTRY
Volume 39, Issue 6, Pages 1163-1170Publisher
AMER CHEMICAL SOC
DOI: 10.1021/ic991105+
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The closo-[B12H12-(n)(OH)(n)](2-) (n = 1-4) ions have been synthesized by the reaction of cesium dodecahydrocloso-dodecaborate(2-), Cs(2)1, with aqueous sulfuric acid. Variation of the reaction temperature, time, and acid concentration results in the stepwise introduction of from one to four hydroxyl groups. Each individual hydroxylation step proceeds regioselectively, affording only one isomer per step. Further substitution of the hydroxylated cluster preferentially takes place at a B-H vertex meta to st B-OH vertex. The Closo-[B12H12-n(OH)(n)](2-) (n = 1-4) species, designated 2-5, respectively, are characterized by one- and two-dimensional B-11 NMR spectroscopy, IR spectroscopy, and high-resolution fast atom bombardment (FAB) mass spectrometry. A rationale that qualitatively explains the influence of the hydroxyl group on the chemical shifts of the individual boron vertices is developed. Furthermore, the solid state structures of closo-[B12H11(OH)](2-), 2, and closo-1,7-[B12H10(OH)(2)](2-), 3, are determined by X-ray diffraction. Crystallographic data are as follows: For [MePPh3](2)2, monoclinic, space group P2(1)/n, a = 890.1 (5) pm, b = 1814(1) pm, c = 1270.5(7) pm, beta = 101.66(2)degrees, Z= 2, R = 0.055; for [MePPh3](2)3, monoclinic, space group P2(1)/n, a = 887.6(4) pm, b = 1847.2(8) pm, c = 1271.1(5) pm, beta = 101.17(1)degrees Z = 2, R = 0.065. In addition, synthetic routes to O-derivatized species of the anions 2-5 such as closo-[B12H11(OTiCpCl2)](2-), 7, closo-1,7-[B12H10(OTiCpCL2)(2)](2-), 8, closo-1,7,9-[B12H9(OTiCPCl2)(3)](2-), 9, closo-[B12H11(OTiCPCl20)](2-), 10, and closo-1,7-[B12H10(OSO2Me)(2)](2-), 11 are described. The crystal structures of 7 and 11 are determined by single-crystal X-ray diffraction. Crystallographic data are as follows: For [MePPh3](2)7, monoclinic, space group Cc, a = 2530.5(2) pm, b = 1653.3(1) pm, c = 1281.3(1) pm, beta = 118.79(2)degrees, Z = 4, R = 0.085; for [HPy](2)11, monoclinic, space group P2(1)/n, a = 1550.9(8) pm, b = 993.1(5) pm, c = 1726.5(9) pm, beta = 112.36(2)degrees, Z = 4, R = 0.061.
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