Contributions to the Chemistry of Boron, LXXXII. The Crystal and Molecular Structure of B,B′ -bis(1,3-dimethyl-1,3,2-diazaborolidin-2-yl)

Abstract

The title compound 2 crystallizes monoclinic, and the space group was determined to be C 2/c. The unit cell contains 16 molecules grouped in two sets of crystallographic independent molecules. The structure was solved by direct methods. Full matrix refinement led to R = 0.09. The molecules have C2 symmetry. The compound is composed of two five membered diazaborolidine rings joined by a boron-boron bond. The two nearly planar rings are twisted to one another by 61.6° and 56.8° respectively

Activation of diboron reagents: The development of mild conditions for the synthesis of unique organoboron compounds

“…is, not surprisingly, similar to the structures in compounds of the type R-B(deaH) (deaH = (OCH 2 CH 2 ) 2 NH, R = C 6 H 5 , C 10 H 7 , C 3 H 5 , C 8 H 11 , C 8 H 7 , C 12 H 9 , C 13 H 17 O 3 ) 119. Complexation of N1 to B2 pyramidalizes B2 with an N1-B2 bond length of 1.6743(19) Å, which is longer than in related trigonal tetraaminodiboranes,[120][121][122] and similar to those in R-B(deaH)…”

Diborane(4) compounds with bidentate diamino groups

“…Thus, lithiation of 2a with four equivalents of Bu n Li in thf followed by reaction with an excess of MeI afforded the expected tetramethyl derivative of 2a, namely 1,1-B 2 {1,2-(NMe) 2 C 6 H 4 } 2 (4), in reasonable yield. A similar reaction but using SnClMe 3 afforded the trimethyltin derivative 1,1-B 2 {1,2-(NSnMe 3 ) 2 C 6 H 4 } 2 (5). Compound 4 was also prepared directly from the reaction between 1 and 1,2-(NHMe) 2 C 6 H 4 .…”

Molecular Mechanics Study of the Cyclic and Unsymmetric Diborane(4) Compounds

“…Derivatives of diborane (4) are an important class of compound in boron chemistry, part of their interest deriving from the presence of an unsupported two-center, two-electron B-B bond [1]. Knowledge of the chemistry of boron compounds has accelerated rapidly in recent years, and a variety of new boron compounds have been prepared and studied in detail.…”

“…Actually, the 1,1-vs. 1,2-isomers issue was raised long ago and was first discussed by Shore et al [2,3] and later by Nöth et al [4,5]. Recently, some experimental papers have been published dealing with this topic and some preliminary electronic structure calculations have been reported to complement those studies [6,7].…”

“…Besides, derivatives of diborane(4) are essentially planar, but there exist structural data for some molecules showing a slight twist around the B-B bond. TheScientificWorldJOURNAL (2003) 3,[636][637][638][639] This diversity of experimental information is worthy of a systematic theoretical analysis in order to gain some understanding of the basic reasons determining the molecular structure of the different derivatives of diborane (4). This paper deals with a theoretical structural study on the basis of an empirical theoretical procedure of some diborane(4) compounds and it may be considered as a first step in such a direction.…”