161377-86-2Relevant articles and documents
Derivatives of Aza-nido-tetraborane and Diaza-arachno-pentaborane from Tri-tert-butylazadiboriridine
Mueller, Matthias,Wagner, Trixie,Englert, Ulli,Paetzold, Peter
, p. 1 - 10 (2007/10/02)
The Lewis acids RBH2 are added to the basis B-B bond of tri-tert-butylazadiboriridine, NB2tBu3 (1a), to give 5-alkyl-1,2,3-tri-tert-butyl-1-aza-nido-tetraboranes of type 3 (two endo-H atoms at B5) or type 4 (one H atom in a B2-B5 bridging position, one exo-H atom at B5), either as a mixture of 3 and 4 (3, 4b-d: R = Me, tBu, CMe2iPr) or with the isomer 4 in high excess (4e, f: R = Ph, sBu).The reaction of dialkylboranes R2BH with 1a yields 5,5-dialkyl-1,2,3-tri-tert-butyl-1-aza-nido-tetraboranes of type 4 (one H atom in a B2-B5 bridging position; 4g, h: R2 = Et2, cycloocta-1,5-diyl).In boiling THF, trialkylboranes BR3 transform 1a into NB2tBu2R which, expectedly, dimerizes spontaneously to give a dialkyl-tetra-tert-butyl-2,5-diaza-nido-hexaborane of type 2 (2a, b: R = Me, Et).The products of the addition of aminoboranes H2B=NRR' to 1a are identified as alkyl derivatives of 2,5-diaza-arachno-pentaborane, N2B3H2tBu3RR' (5a-d, R/R' = H/Pr, H/tBu, Me/Me, Et/Et).The aminoborane H2B=NiPr2 with a sterically more demanding amino group hydroborates the B-B bond of 1a to give the acyclic product iPr2N=BH-B(tBu)-N(tBu)=B(tBu)H (6).In contrast to the B atoms, the N atoms in the electron-deficient cluster skeletons of 2-5 need not take part in (3c, 2e) bonds of the ? type.The molecular structures of 4c, 5d, and 6 are confirmed by X-ray structural analyses. - Key Words: 1-Aza-nido-tetraboranes / 2,5-Diaza-arachno-pentaboranes / 2,5-Diaza-nido-hexaboranes / Borylamine
