The Valence Structure of the Boron Hydrides

Abstract

A set of extended valence postulates is presented including the concept of the localized three-center bond. These postulates are applied systematically to the boron hydrides and account for their unusual geometry, their unexpected dipole moments, and the fact that they are not ``electron-deficient.''

The Structure Chemistry of Boron-Rich Solids of the Alkali Metals

“…This point is very important for the discussion of the bonding in boron-rich solids. It should help to decide whether Lipscomb's bonding concept [29,30] developed for boron-rich molecules is applicable for non-molecular structures.…”

The crystal structure of a simple rhombohedral form of boron

“…Since reflections at the limit of observable data were still quite strong, there is a fair amount of background variation on the map. Atom positions taken from this section are Crawford & Lipscomb (1954). In the present boron structure, half of the atoms in an icosahedron are bound by conventional single bonds to atoms of other icosahedra.…”

Carboranes as model hypercarbon systems; structural and bonding patterns in selected isoelectronic closo-borane and carborane systems; [BnHn]2−, [1-CBn−1Hn]− and 1,n-C2Bn−2Hn (n = 5, 6, 7, 10 or 12)

“…The parent dianion [B 5 H 5 ] 2-, though as yet unknown, has been the subject of earlier calculations [3,19,20,29] which have shown the bonding between the axial and equatorial boron atoms to be far stronger than that between the equatorial atoms, as revealed again here, reinforcing the simplistic picture given by a localized bond description in which three 2c2e BB bonds along axial-equatorial edges in one hemisphere, and three 3c2e BBB bonds in adjacent faces in the other hemisphere, but resonating between the two hemispheres, imply bond orders of 0.833′ and 0.333′ for the axial-equatorial and equatorial-equatorial bonds respectively. [13,30] A description of the bonding in terms of six axial-equatorial 2c2e bonds, and no bonding around the equator, with the equatorial boron atoms using only three AOs (one for the exo hydrogen, one each for the axial boron neighbours), can be ruled out. ).…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Less familiar is how these skeletal electrons are distributed around the vertices, edges or faces of the deltahedra, though many calculations have been carried out to establish relative stabilities, probing group charges and showing the importance of skeletal connectivities. [17][18][19][20][21][22][23] Limited insight is provided by resonating localized 2-center 2-electron (2c2e) and 3-center 2-electron (3c2e) bond networks.…”