ISSN:
0009-2940
Keywords:
1-Aza-nido-tetraboranes
;
2,5-Diaza-arachno-pentaboranes
;
2,5-Diaza-nido-hexaboranes
;
Boryl[diborane(4)yl]amine
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
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 dialkyltetra-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, N2B3tH2tBu3RR' (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 s̰ type. The molecular structures of 4c, 5d, and 6 are confirmed by X-ray structural analyses.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19951280102
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