Aromatic Polyhedral Hydroxyborates: Bridging Boron Oxides and Boron Hydrides

Abstract

No explosion, but per-B-hydroxylation occurs if the icosahedral boron hydrides [closo-B12 H12 ](2-) (see picture), [closo-CB11 H12 ](-) , or closo-1,12-(CH2 OH)2 -1,12-C2 B10 H10 are refluxed in 30 % hydrogen peroxide. Thus, the three isoelectronic species [closo-B12 (OH)12 ](2-) , [closo-1-H-1-CB11 (OH)11 ](-) , and closo-1,12-H2 -1,12-C2 B10 (OH)10 were obtained. ○=BH, ○=BOH.

Substitution at boron in molybdaborane frameworks: Synthesis and characterization of isomeric (η5-C5Me5Mo)2B5HnXm (when X=Cl: n=5, 7, 8; m=4, 2, 1 and X=Me: n=6, 7; m=3, 2)

“…Electrophilic substitution of cage B-H terminal bonds in polyhedral boranes and carboranes have been elegantly demonstrated by Hawthorne [1][2][3][4][5]. Such studies, [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] including those leading to peralkylation, perhydroxylation, or perhalogenation, continue to be of significant interest as the persubstitued borane or carborane clusters bear potential applicability in several areas as targets for anti tumor activity [22], weekly coordinating anion [23], components of radioimaging reagent [24], space-controlling drug component, [25].…”

“…However, availability of good synthetic routes to metallaboranes of group 5-9 [28][29][30] and a recent study by Hawthorne's group on exo-cluster substitution, [3,4,31,32] led us to explore the development of routes of B-functionalized metallaborane species. Introduction of substituents on the boron in metallaboranes is important if one wishes to make complexes that are resistant to deboronation (decapitation) by electrophiles [33][34][35][36].…”

New Discoveries at the Interface of Boron and Carbon Chemistries

“…Species 4 is colorless, paramagnetic 5 is reddish-purple, and yellow 6 is diamagnetic. Redox reactions which interconvert 4, 5, and 6 are conveniently conducted with Fe 3+ and BH 4 -as oxidant and reductant, respectively. X-ray diffraction studies using the dodecabenzyl ether system proved that 4 and 5 were isostructural within experimental error although 5 in I h symmetry has a degenerate HOMO array.…”

“…This chemistry is richly endowed with opportunities for further discovery and unique technological applications unavailable elsewhere in the periodic table. The recently described discovery [4,5] of [closo-B 12 (OH) 12 ] 2-, 1, provides such an advance in polyhedral borane chemistry. 10 , 3, apparently involves the oxidation of the -CH 2 OH substituents to -COOH followed by decarboxylation.…”

“…The structures of 1, 2, and 3 were determined by X-ray diffraction studies, and the unusual water solubilities of the alkali metal, NH 4 + and H 3 O + salts of 1 have been reported [5] along with their structures. Such simple salts of 1 are aggregated by coordination of the many oxygen atoms of the -OH substituents with the alkali metal cations and by similar hydrogen-bonding interactions with NH 4 + and H 3 O + cations. The cesium cation provides the most water-soluble salt of 1 known, to date.…”