A study of the sequential acid-catalyzed hydroxylation of dodecahydro-closo-dodecaborate(2-)
The closo-[B{sub 12}H{sub 12{minus}n}(OH){sub n}]{sup 2{minus}} (n = 1-4) ions have been synthesized by the reaction of cesium dodecahydro-closo-dodecaborate(2-), Cs{sub 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 a B-OH vertex. The closo-[B{sub 12}H{sub 12{minus}n}(OH){sub n}]{sup 2{minus}} (n = 1-4) species, designated 2-5, respectively, are characterized by one- and two-dimensional {sup 11}B 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-[B{sub 12}H{sub 11}(OH)]{sup 2{minus}}, 2, and closo-1,7-[B{sub 12}H{sub 10}(OH){sub 2}]{sup 2{minus}}, 3, are determined by X-ray diffraction. Crystallographic data are as follows: for [MePPh{sub 3}]{sub 2} 2, monoclinic, space group P2{sub 1}/n, a = 89.1(5) pm, b = 1,814(1) pm, c = 1,270.5(7) pm, {beta} = 101.66(2){degree}, Z = 2, R = 0.055; for [MePPh{sub 3}]{sub 2} 3, monoclinic, space group P2{sub 1}/n, a = 887.6(4) pm, b = 1,847.2(8) pm, c = 1,271.1(5) pm, {beta} = 101.17(1){degree}, Z = 2, R = 0.065. In addition, synthetic routes to O-derivatized species of the anions 2--5 such as closo-[B{sub 12}H{sub 11}(OTiCpCl{sub 2})]{sup 2{minus}}, 7, closo-1,7-[B{sub 12}H{sub 10}(OTiCpCl{sub 2}){sub 2}]{sup 2{minus}}, 8, closo-1,7,9-[B{sub 12}H{sub 9}(OTiCpCl{sub 2}){sub 3}]{sup 2{minus}}, 9, closo-[B{sub 12}H{sub 11}(OCONHPh)]{sup 2{minus}}, 10, and closo-1,7-[B{sub 12}H{sub 10}(OSO{sub 2}Me){sub 2}]{sup 2{minus}}, 11, are described. The crystal structures of 7 and 11 are determined by single-crystal X-ray diffraction. Crystallographic data are as follows: for [MePPh{sub 3}]{sub 2} 7, monoclinic, space group Cc, a = 2,530.5(2) pm, b = 1,653.3(1) pm, c = 1,281.3(1) pm, {beta} = 118.79(2){degree}, Z = 4, R = 0.085; for [HPy]{sub 2}11, monoclinic, space group P2{sub 1}/n, a = 1,550.9(8) pm, b = 993.1(5) pm, c = 1,726.5(9) pm, {beta} = 112.36(2){degree}, Z = 4, R = 0.061.
- Research Organization:
- Univ. of California, Los Angeles, CA (US)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG03-95ER61975
- OSTI ID:
- 20023359
- Journal Information:
- Inorganic Chemistry, Vol. 39, Issue 6; Other Information: PBD: 20 Mar 2000; ISSN 0020-1669
- Country of Publication:
- United States
- Language:
- English
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