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Issue 39, 2006
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The first member of the eleven-vertex azadicarbaborane series, 1,6,9-NC2B8H13, and its N-alkyl derivatives

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Abstract

Reactions between closo-1,2-C2B8H10 (1) and amines of general formulation R1R2NH (where R1, R2 = H, H; Me, H; t-Bu, H and Et, Et) resulted in a straightforward cluster expansion and formation of the 11-vertex arachno-azadicarbaboranes of the 1,1-R1,R2−1,6,9-NC2B8H11 (2) cluster constitution (where R1, R2 = H, H 2a; Me, H 2b; t-Bu, H 2c and Et, Et 2d) in yields 10–75%, depending on the nature of the amine used. The reactions are the first example of a direct closo to arachno transformation in the area of cluster-boron compounds. Compounds 2b and 2c were isolated in two isomeric forms anti- and syn- that differ in the positioning of the t-Bu substituent with respect to the bridging hydrogen site. Deprotonation of compounds 2 generally leads to removal of the bridging proton and formation of the [1,1-R1,R2−1,6,9-NC2B8H11] (2) anions that, in the case of the monoalkylated Me and t-Bu derivatives, adopt only an anti configuration. The structure of anti-2c was determined by X-ray diffraction analysis and the geometries of the parent compound and the corresponding syn and anti isomers were optimised at the RMP2/6-31G* level. The composition of all compounds is consistent with the results of mass spectrometry and multinuclear (1H and 11B) spectroscopy complemented by two-dimensional [11B–11B]-COSY and 1H{11B(selective)} NMR measurements. Experimental 11B chemical shifts generally show acceptable agreement with theoretical values calculated by GIAO methods, in particular at GIAO-MP2/II, where possible.

Graphical abstract: The first member of the eleven-vertex azadicarbaborane series, 1,6,9-NC2B8H13, and its N-alkyl derivatives

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Supplementary files

Article information


Submitted
21 Jun 2006
Accepted
19 Jul 2006
First published
08 Aug 2006

Dalton Trans., 2006, 4664-4671
Article type
Paper

The first member of the eleven-vertex azadicarbaborane series, 1,6,9-NC2B8H13, and its N-alkyl derivatives

Z. Janoušek, R. Dostál, J. Macháček, D. Hnyk and B. Štíbr, Dalton Trans., 2006, 4664
DOI: 10.1039/B608857K

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