title: Prototropic μ-H8,9and μ-H9,10Tautomers Derived from the [nido-5,6-C2B8H11]-Anion.
abstract: Reported is an unusual tautomeric behavior within the [nido-5,6-C2B8H11]-(1a-) cage that has no precedence in the whole area of carborane chemistry. Isolated were two skeletal tautomers, anions [6-Ph-nido-5,6-C2B8H10-μ8,9]-(2d-) and [5,6-Me2-nido-5,6-C2B8H9-μ9,10]-(3b-), which differ in the positioning of the open-face hydrogen bridge. Their structures have been determined by X-ray diffraction analyses. The 3b-structure is stabilized by intermolecular interaction involving Et3NH+and B8-B9 and H8 atoms in the solid phase; however, its dissolution in CD3CN causes instant conversion to the more stable [5,6-Me2-nido-5,6-C2B8H9-μ8,9]-(2b-) tautomer. The dynamic electron-correlation-based MP2/6-31G* computations suggest that the parent [nido-5,6-C2B8H11-μ8,9]-(2a-) tautomer is 3.9 kcal·mol-1more stable than the [nido-5,6-C2B8H11-μ9,10]-(3a-) counterpart and the μ8,9structure 2-is therefore the most stable tautomeric form in the solution, as was also demonstrated by multinuclear (1H,11B, and13C) NMR measurements on the whole series of C-substituted compounds.
authors.affiliation: Institute of Inorganic Chemistry, Academy of Sciences of the Czech Republic , Husinec-Řež 1001, Czech Republic.
authors.forename: Oleg L
authors.initials: OL
authors.lastname: Tok
authors.affiliation: Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice , Studentská 573, 532 10 Pardubice, Czech Republic.
authors.forename: Zdenka
authors.initials: Z
authors.lastname: Růžičková
authors.affiliation: Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice , Studentská 573, 532 10 Pardubice, Czech Republic.
authors.forename: Aleš
authors.initials: A
authors.lastname: Růžička
authors.affiliation: Institute of Inorganic Chemistry, Academy of Sciences of the Czech Republic , Husinec-Řež 1001, Czech Republic.
authors.forename: Drahomír
authors.initials: D
authors.lastname: Hnyk
authors.affiliation: Institute of Inorganic Chemistry, Academy of Sciences of the Czech Republic , Husinec-Řež 1001, Czech Republic.
authors.forename: Bohumil
authors.initials: B
authors.lastname: Štíbr