A Planar, Aromaticbicyclo-Tetraborane(4)

Abstract

The reduction of dimethylaminodichloroborane and dimethylaminodichlorodiborane(4) with NaK2.8 alloy provides the new tetraborane(4) 1 (see scheme). The unusual bonding situation in 1 is explained on the basis of molecular‐orbital calculations.

The Surprising Structures of B8F12 and B10F12

“…Organic derivatives of B 4 H 4 (m-H) 2 of type B 4 R 4 (m-H) 2 have been reported [16,17] and while the structures were not established by X-ray crystallography, there seems little doubt that they have a similar B 4 core to B 10 F 12 but with bridging H atoms across opposite edges of the tetrahedron. Nevertheless, such organoboron compounds and related derivatives of tetrabor-ane (6) [18,19] are much more electron rich and thus more stable than B 10 F 12 , which depends on relatively weak F À B pbonding to compensate for its electron deficiency.…”

Four Boron Atoms, Four Positive Charges, and Four Skeletal Electrons: A Fluorescent σ‐Aromatic Tetraborane(4)

“…Siebert et al reported 1984 ad erivative of the isoelectronic neutral C 2 B 2 H 4 ,w ith amino groups in place for hydrides at the boron atoms. [7,8] Scheme 1shows the derivative [B 4 [B(NMe 2 ) 2 ] 2 (NMe) 2 ]. [6] Formal two-electron oxidation of [B 4 H 4 ] 2À leads to neutral B 4 H 4 with aplanar rhomboid B 4 core and delocalized s-and p-systems.…”

“…[3] TheB 2 C 2 core of this compound is not planar, but puckered, in line with the results of quantum-chemical calculations by Schleyer et al [4] Berndt et al synthesized some more derivatives [5] and eventually also the first derivative of [B 4 H 4 ] 2À . [8] Formal removal of two further electrons leads to [B 4 H 4 ] 2+ with an SE number of 6. [7,8] Scheme 1shows the derivative [B 4 [B(NMe 2 ) 2 ] 2 (NMe) 2 ].…”

Vier Boratome, vier positive Ladungen und vier Gerüstelektronen: ein fluoreszierendes σ‐aromatisches Tetraboran(4)

“…Siebert et al berichteten bereits 1984 von einem Derivat des isoelektronischen, neutralen C 2 B 2 H 4 mit Aminogruppen anstelle der borgebundenen Hydride. [7,8] (6) mit einem planaren, rhomboiden B 4 -Gerüst und 6GE. [6] Eine Zwei-Elektronen-Oxidation von [B 4 H 4 ] 2À führt formal zu neutralem B 4 H 4 mit einem planaren rhomboiden B 4 -Gerüst und delokalisierten s-u nd p-Systemen.…”

“…[6] Eine Zwei-Elektronen-Oxidation von [B 4 H 4 ] 2À führt formal zu neutralem B 4 H 4 mit einem planaren rhomboiden B 4 -Gerüst und delokalisierten s-u nd p-Systemen. Dagegen isolierten Timms et al das neutrale Tetraboran (8) [B 4 F 4 (BF 2 ) 4 ]mit einem gefalteten B 4 -Ring und 4GE(verteilt auf zwei (3c,2e)-Bindungen). [9] Das weitere Entfernen von zwei Elektronen würde letztlich das Te trakation [B 4 H 4 ] 4+ mit nur 4GE ergeben.…”