Diboron molecule

Holliday, A. K F. J. Marsden, and A. G. Massey The Reactions of Diboron Tetrachloride with Some Nitrogen-Containing Donor Molecules. J. Chem. Soc. 3348 (1961). 

In Chapter 2, the use of a bonds for one special bonding that occurs in one particular boron compound, which was called "diborane", was introduced. An examination of other boron compounds and the nomenclature associated with them is now undertaken. First of all, it should be noted that despite that boron has three electrons in its outer shell and that a trigonal planar bonding pattern is common in molecules such as BF3, etc., the simplest hydride of boron that is normally encountered is not BH3. To the contrary, under normal conditions of temperature and pressure, not only is the smallest boron hydride a dimer, but also two distinct diboron hydride molecules are encountered. 

Structural data refer to the diboron tetrahalides. X-Ray diffraction studies of B2CI4 (5) and B2F4 100) indicate a planar, centrosymmetric structure (Djji) i the solid. Electron diffraction (47) and infrared and Raman studies (65) suggest that the B2CI4 molecule has a skewed (Z>2d) structure in the gas and liquid. The infrared spectrum of B2F4 (37,42) indicates it to be skewed or undergoing essentially free rotation in the gaseous state. 

There is no clear evidence for formation of stable bis(boryl) derivatives from the interaction of diboron tetrahalides with molecules containing multiple bonds other than C=C or Cr C. Such reactions as occur may in some cases involve initial diboration, but as they are of limited interest from the organometallic viewpoint, they will be mentioned only briefly. 

Receptors containing diboronic acids can precisely recognize saccharide molecules. 

Diboronic acid, B2(OH)4, can be obtained by hydrolysis of B2CI4. Like boric acid, diboronic acid crystallizes with a layer structure, each layer consisting of hydrogen-bonded molecules (Figure 13.18). 

Structure-directing elements. The size of the cages was varied by changing the diboronic acid building block. The authors used these complex structures to encapsulate polyaromatic molecules such as triphenylene or coronene. 

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