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Undecaborates M 2 [B 11 H 11 ]: Facile Synthesis, Crystal Structure, and Reactions
Author(s) -
Volkov O.,
Dirk W.,
Englert U.,
Paetzold P.
Publication year - 1999
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/(sici)1521-3749(199907)625:7<1193::aid-zaac1193>3.0.co;2-l
Subject(s) - protonation , deprotonation , chemistry , crystal structure , crystallography , molecule , yield (engineering) , ion , stereochemistry , materials science , organic chemistry , metallurgy
closo ‐Undecaborates were synthesized by the deprotonation of B 11 H 13 (SMe 2 ) with Li t Bu in thp or K[BHEt 3 ] in thf, [Li(thp) 3 ] 2 [B 11 H 11 ] and K 2 [B 11 H 11 ] being obtained in 83 and 93% yield, respectively. K 2 [B 11 H 11 ] can be transformed into A 2 [B 11 H 11 ] with the corresponding ammonium chlorides in aqueous solution (A = [NMe 3 Ph], [NBzlEt 3 ], [N(PPh 3 ) 2 ]). The crystal structure analysis of [Li(thp) 3 ] 2 [B 11 H 11 ] (space group P 2 1 / c ) reveals a rather distorted octadecahedron for the [B 11 H 11 ] 2– anion, whereas the corresponding octadecahedron in [NBzlEt 3 ] 2 [B 11 H 11 ] (space group P 2 1 2 1 2 1 ) exhibits a structure close to C 2v symmetry, expected for the free anion. The protonation of [B 11 H 11 ] 2– at low temperature gives [B 11 H 12 ] – , whose structure could be elucidated by NMR methods; it is formed, apparently, by the opening of the B1–B4 edge of [B 11 H 11 ] 2– in the course of its known degenerate skeletal rearrangement, followed by the protonation of the B2–B4 edge. The reaction of [B 11 H 12 ] – with a second molecule of the acid HX (X = CF 3 COO) gives nido ‐[B 11 H 13 X] – . The addition of BH 3 to [B 11 H 11 ] 2– yields closo ‐[B 12 H 12 ] 2– under loss of H 2 . Two [B 11 H 11 ] 2– units are fused by the aid of FeCl 3 , with the known anion [B 22 H 22 ] 2– as the product, whose 11 B‐NMR signals could completely be assigned on the basis of C s symmetry. The compound [NBzlEt 3 ][N(PPh 3 ) 2 ][B 22 H 22 ] crystallizes in the space group Pna 2 1 .