title: Dicarbaheteroborane Chemistry. Representatives of Two Eleven-Vertex Dicarbaazaundecaborane Families: nido-10,7,8-NC(2)B(8)H(11), Its N-Substituted Derivatives, and arachno-1,8,11-NC(2)B(8)H(13).
abstract: Treatment of an acidified solution of the [nido-7,8-C(2)B(9)H(12)](-) anion (1(-)) with NaNO(2) at 0 degrees C in the presence of benzene resulted in the formation of two eleven-vertex azadicarbaboranes, nido-10,7,8-NC(2)B(8)H(11) (2) and arachno-1,8,11-NC(2)B(8)H(13)( )()(3), isolated in yields of 15 and 35%, respectively, together with a small amount (0.9%) of 5-Ph-nido-7,8,10-C(2)NB(8)H(10) (5-Ph-2). Compound 3 was converted in 68% yield into 2 by reaction with PS (PS = "proton sponge"; 1,8-(dimethylamino)naphthalene and acetone. Deprotonation of 2 at the N(10)H vertex gave the [nido-10,7,8-NC(2)B(8)H(10)](-) anion (2(-)), which was easily alkylated with Me(2)SO(4) or PhCH(2)Br to produce the N-alkylated derivatives of 2, 10-R-nido-10,7,8-NC(2)B(8)H(10), where R = Me (10-Me-2, 86%) and PhCH(2) (10-PhCH(2)-2, 69%). The geometries of the parent dicarbazaboranes 2 and 3 were optimized at the MP2(fc)/6-31G level, and the structures of all compounds were thence confirmed by the excellent agreement between experimental data and IGLO/NMR calculations of the (11)B chemical shifts for the parent compounds at the DZ//6-31G, DZ//MP2/6-31G, and II'//MP2/6-31G levels.
authors.affiliation: Institute of Inorganic Chemistry, Academy of Sciences of the Czech Republic, 250 68 Rez, The Czech Republic, School of Chemistry, University of Leeds, Leeds LS2 9JT, England, and Computer Chemistry Center, Institute of Organic Chemistry, University Erlangen-Nürnberg, Nägelbachstrasse 25, D-91052 Erlangen, Germany.
authors.forename: Jaromír
authors.initials: J
authors.lastname: Plesek
authors.forename: Bohumil
authors.initials: B
authors.lastname: Stíbr
authors.forename: Drahomír
authors.initials: D
authors.lastname: Hnyk
authors.forename: Tomás
authors.initials: T
authors.lastname: Jelínek
authors.forename: Stanislav
authors.initials: S
authors.lastname: Hermánek
authors.forename: John D.
authors.initials: JD
authors.lastname: Kennedy
authors.forename: Matthias
authors.initials: M
authors.lastname: Hofmann
authors.forename: Paul v. R.
authors.initials: PR
authors.lastname: Schleyer