title: Unusual Cage Rearrangements in 10-Vertex nido-5,6-Dicarbaborane Derivatives: An Interplay between Theory and Experiment.
abstract: The reaction between selected X-nido-5,6-C2B8H11compounds (where X = Cl, Br, I) and "Proton Sponge" [PS; 1,8-bis(dimethylamino)naphthalene], followed by acidification, results in extensive rearrangement of all cage vertices. Specifically, deprotonation of 7-X-5,6-C2B8H11compounds with one equivalent of PS in hexane or CH2Cl2at ambient temperature led to a 7 → 10 halogen rearrangement, forming a series of PSH+[10-X-5,6-C2B8H10]-salts. Reprotonation using concentrated H2SO4in CH2Cl2generates a series of neutral carbaboranes 10-X-5,6-C2B8H11, with the overall 7 → 10 conversion being 75%, 95%, and 100% for X = Cl, Br, and I, respectively. Under similar conditions, 4-Cl-5,6-C2B8H11gave ∼66% conversion to 3-Cl-5,6-C2B8H11. Since these rearrangements could not be rationalized using the B-vertex swing mechanism, new cage rearrangement mechanisms, which are substantiated using DFT calculations, have been proposed. Experimental11B NMR chemical shifts are well reproduced by the computations; as expected δ(11B) for B(10) atoms in derivatives with X = Br and I are heavily affected by spin-orbit coupling.
authors.affiliation: Institute of Inorganic Chemistry of the ASCR, v.v.i. , CZ-250 68 Husinec-Řež, Czech Republic.
authors.forename: Bohumil
authors.initials: B
authors.lastname: Štíbr
authors.affiliation: Institute of Inorganic Chemistry of the ASCR, v.v.i. , CZ-250 68 Husinec-Řež, Czech Republic.
authors.forename: Josef
authors.initials: J
authors.lastname: Holub
authors.affiliation: Institute of Inorganic Chemistry of the ASCR, v.v.i. , CZ-250 68 Husinec-Řež, Czech Republic.
authors.forename: Mario
authors.initials: M
authors.lastname: Bakardjiev
authors.affiliation: Department of Chemistry, University of York , Heslington, York, U.K. YO10 5DD.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Lane
authors.affiliation: Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849, United States.
authors.forename: Michael L
authors.initials: ML
authors.lastname: McKee
authors.affiliation: Department of Chemistry, University of York , Heslington, York, U.K. YO10 5DD.
authors.forename: Derek A
authors.initials: DA
authors.lastname: Wann
authors.affiliation: Institute of Inorganic Chemistry of the ASCR, v.v.i. , CZ-250 68 Husinec-Řež, Czech Republic.
authors.forename: Drahomír
authors.identifier: http://orcid.org/0000-0001-8094-7509
authors.initials: D
authors.lastname: Hnyk