Structures and Stabilities of B₂H_2n²⁺ Dications (n = 1—4)

Abstract

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Theoretical Predictions of C3v Symmetric Three-H-Bridged Noble Gas Compounds NgBeH3BeR, NgBeH3BR+, and NgBH3BR2+

“…52 More interestingly, B 2 H 4 (C 3v ) contains a B−H 2c-2e bond and three B−H−B 3c-2e hydrogen-bridged bonds. 53 On the terminal B atom, there is a lone pair electrons. So it can act as a Lewis base to bond with a Lewis acid.…”

Activation of H2 and Et3SiH by the Borinium Cation [Mes2B]+: Avenues to Cations [MesB(μ-H)2(μ-Mes)BMes]+ and [H2B(μ-H)(μ-Mes)B(μ-Mes)(μ-H)BH2]+

“…The question of B–B bonding in polyboron compounds featuring 3c–2e bonds is of interest. , In 2 + , the B···B distance of 1.604(6) Å falls within the sum of covalent radii (Σ COV (B–B) = 1.68 Å) which is shorter than that reported by Himmel et al (2.229 Å) for the cationic diboron species [B 2 H 3 (hpp) 2 ]­[I] (hpp = 1,3,4,6,7,8-hexahydro-2 H -pyrimido-[1,2- a -pyrimidinate) . Nonetheless, it is also longer than that predicted for [B 2 H 5 ] + (1.518 Å) at the QCISD­(T)/6-311G** level . The DFT-computed fractional Wiberg bond indices for the central B–C, B–H, B′–H and B′–B pairs are 0.70, 0.43, 0.34 and 0.80, consistent with two B–H–B and one B–C–B 3c, 2e bonds in 2 + rather than a B–B single bond.…”

“…The parent diboranium cation [B 2 H 5 ] + was first observed in ion cyclotron resonance and pyrolysis mass spectrometry studies of B 2 H 6 . − Olah subsequently generated diboranium transiently via treatment of B 2 H 6 with magic acid. Computational studies have predicted varying geometries, − although a trihydride-bridged D 3h structure is supported by photoionization mass spectrometry studies…”

“…69 Nonetheless, it is also longer than that predicted for [B 2 H 5 ] + (1.518 Å) at the QCISD(T)/6-311G** level. 65 Efforts to prepare bulk 2 from 1 and HSiEt 3 were unsuccessful as 11 In summary, the borinium cation 1 + is shown to react with H 2 and HSiEt 3 , affecting hydride delivery to boron and protonation or silylation of a mesityl group. In the latter case, the diboranium salt 2 is obtained.…”