Carbonyl Boron and Related Systems:  An ab Initio Study of B−X and YB⋮BY (¹Σ_g⁺), Where X = He, Ne, Ar, Kr, CO, CS, N₂ and Y = Ar, Kr, CO, CS, N₂

Abstract

Using the coupled-cluster methodology and large correlation consistent basis sets, we have examined the BX and YBBY (1Σg +) molecules, where X = He, Ne, Ar, Kr, CO, CS, and N2 and Y = Ar, Kr, CO, CS, and N2. For the B−X series we have constructed full potential energy curves reporting total energies, equilibrium geometries, binding energies, and also spectroscopic constants for the diatomic sequence. The B−CO, B−CS, and B−N2 ground states are of 4Σ- and 2Π symmetries, respectively, with the 4Σ- states having remarkably strong binding energies with respect to their adiabatic fragments. For all the triatomics the first excited 4P state of B plays an instrumental role in the binding process, while the bonding mechanism in either the 2Π or 4Σ- symmetries is due to charge transfer to the empty 2p z orbital of the B atom. The YBBY series results by singlet coupling two B−Y 4Σ- moieties, leading to acetylene-like YB⋮BY systems of 1Σg + symmetry.

A (U)MP2(full) and (U)CCSD(T) theoretical investigation into the substituent effects on the intermolecular T-shaped F–H…π interactions between HF and LBBL (L = −H, ∶CO, :NN, –Cl, –CN and –NC)

“…It is noteworthy that, although the electronegativity of the C, O and N atoms is higher than that of the B atom, and the electrons should transfer from BB to ∶CO and ∶NN, the electrons shift conversely, perhaps due to that these substituents have lone-pair electrons and the boron atom is electron-deficient. Thus, the substituents might offer the lone-pair electrons to the electron-deficient boron atom, as is in accordance with the investigation by Papakondylis et al [12].…”

“…Recently we have found that the investigation on the monomer and T-shaped X-H…π hydrogen-bonded complex involving the BB multiplebond has always been of the interesting topic, accompanied by the unusual "phenomenon" [11][12][13]. For example, the electron-deficient BB bond in LBBL shows the double-bond and triple-bond characteristic with the single-electron donating/withdrawing (L = −H, -CN, -F, etc.)…”

“…and lone-pair-electron donating (L = ∶CO, :NN, etc.) substituent, respectively [11,12,14], as is just opposite to the electron-rich CC bond in LCCL [15][16][17][18][19]. Knight and Jouany et al have found the valence molecular orbitals of HBBH were (2σ g ) 2 (2σ u ) 2 (3σ g ) 2 (1π u ) 2 where the two paired electrons occupied degenerate boron 2p bonding orbitals, indicating that HBBH contained one B-B π bonding orbital [10,11].…”

“…Papakondylis et al examined the OCBBCO and NNBBNN molecules using the coupledcluster methodology and large correlation consistent basis sets. They found that the bonding mechanism of BCO or BN 2 was due to charge transfer from L to the empty 2p z orbital of the B atom and the LBBL series resulted by singlet coupling two B-Y 4 P À moieties, leading to acetylene-like LBBL systems of the 1 P þ g symmetry [12]. In the investigation on the T-shaped X-H…π hydrogen-bonded complexes involved with the B ≡ B bond, we have found that the B ≡ B triple bond underwent contraction [13], as is not consistent with the accepted notion that the multiple bond should be elongated as a result of H…π interaction [20][21][22][23][24].…”

Einfach‐, Doppel‐, Dreifachbindungen und Ketten: Knüpfung elektronenpräziser B‐B‐Bindungen

“…2À in der Gasphase, das einen berechneten B-B-Abstand zwischen 1.481 und 1.504 aufweist. [43] Diese Berichte wurden von theoretischen Studien der Gruppen von Mavridis [44] und Frenking [43b] begleitet, die eine Reihe von Donoren wie Edelgasatome, CO, CS und N 2 zur Stabilisierung der B 2 -Einheit untersuchten und diese kurzen B-B-Abstände bestä-tigten.…”