A Boron‐Carbon Double Bond

Abstract

tri-cis 3 ZEZZ X= Me, Et, Ph all-cis 4 zzzz di-cis 5 EZZE tri-cis 3' ZZEZ allcis' 4' di-cis' 5'between the degenerate conformers di-cis(EZZE) 5 and dicis'-(EZZE) 5', which is frozen at -96°C.The ' H-NMR spectroscopic findings were corroborated by X-ray structure analyses of l b , Id, and 2d. In the crys-The structure of 3 follows from 'H-, I3C-and "B-NMR spectral2'. Signals for the two C-atoms of the C2B2 skeleton appear below -40°C at 6 = 115.2 and 25.0 in the region for sp2 and sp3 C-atoms; both signals show line-broadening characteristic of a C-atom bound to boron. Hence the structure of a 2,3-diboramethylenecyclopropane'3' for 2 can be ruled out. Below -11 "C the B atoms give rise to [**I This work was supported by the Fonds der Chemischen Industrie. We thank Dr. P. H. M. Budzelaar and Dr. S. M. van der Kerk. Utrecht, for the first hints on the structure of the compound 3, and Prof. K. Dehnicke, Marburg, and Prof. P. u. R . Schleyer, Erlangen, for valuable discussions.

Isomerization and rearrangement of boriranes: from chemical rarities to functional materials

“…[26][27][28]. In fact, free boriranes remain extremely rare [29,30]. One method of stabilizing such systems is the use of Lewis bases (LBs) which can coordinate to Lewis acidic boron, thereby suppressing some of its reactivity.…”

Reversible Photothermal Isomerization of Carborane‐Fused Azaborole to Borirane: Synthesis and Reactivity of Carbene‐Stabilized Carborane‐Fused Borirane

“…[12] Several examples of base-free boriranes have also been reported. [13] We are interested in the preparation of carborane-fused borirane 1,2-BR-1,2-C 2 B 10 H 10 because of the very rich reaction chemistry of the corresponding three-membered metallacycles 1,2-[M]-1,2-C 2 B 10 H 10 (M = transition metals). [14,15] However,m any attempts to prepare 1,2-BR-1,2-C 2 B 10 H 10 through the reaction of Li 2 C 2 B 10 H 10 or 1,2-[M]-1,2-C 2 B 10 H 10 with 1equiv of RBX 2 failed.…”

Prediction of Boron–Boron Triple‐Bond Polymers Stabilized by Janus‐Type Bis(N‐heterocyclic) Carbenes

“…Boron is ac hemical element that exhibits av ery rich chemistry with av ariety of bondingp atterns, such as boranes, [1][2][3] carboranes, [4,5] borates, [6,7] boroles, [8,9] azaborines, [10] azaborinines, [11] boron halidesa nd nitrides, [12,13] as well as severala llotropic forms in the solid state. [14] Boron is also remarkably known to have an electron deficient nature.D espite this intrinsic property,anumber of compounds with double and triple BÀB [15][16][17][18][19][20][21][22][23][24] and BÀX( X=C, [25][26][27] P, [28] O, [29] and N [30] )b onds have been synthesized in the last decades. In 1992, Power and collaborators have shown that the reduction of B 2 R 4 precursors couldl ead to B 2 R 4 2À dianions presenting an unprecedented B-B double bond.…”