scholarly journals In Search of the Perfect Triple BB Bond: Mechanical Tuning of the Host Molecular Trap for the Triple Bond B≡B Fragment

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6428
Author(s):  
Shmuel Zilberg ◽  
Michael Zinigrad

The coordination of the B2 fragment by two σ-donor ligands L: could lead to a diboryne compound with a formal triple bond L:→B≡B←:L. σ-Type coordination L:→B leads to an excess of electrons around the B2 central fragment, whereas π-back-donation from the B≡B moiety to ligand L has a compensation effect. Coordination of the σ-donor and π-acceptor ligand is accompanied by the lowering of the BB bond order. Here, we propose a new approach to obtain the perfect triple BB bond through the incorporation of the BB unit into a rigid molecular capsule. The idea is the replacement of π-back-donation, as the principal stabilization factor in the linear NBBN structure, with the mechanical stabilization of the BB fragment in the inert molecular capsule, thus preserving the perfect B≡B triple bond. Quantum-chemical calculations show that the rigid molecular capsule provided a linear NBBN structure and an unusually short BB bond of 1.36 Å. Quantum-chemical calculations of the proposed diboryne adducts show a perfect triple bond B≡B without π-back-donation from the B2 unit to the host molecule. Two mechanisms were tested for the molecular design of a diboryne adduct with a perfect B≡B triple bond: the elimination of π-back-donation and the construction of a suitable molecular trap for the encapsulation of the B2 unit. The second factor that could lead to the strengthening or stretching of a selected chemical bond is molecular strain produced by the rigid molecular host capsule, as was shown for B≡B and for C≡C triple bonds. Different derivatives of icosane host molecules exhibited variation in BB bond length and the corresponding frequency of the BB stretch. On the other hand, this group of molecules shows a perfect triple BB bond character and they all possess a similar level of HOMO.

Author(s):  
Kunqi Gao ◽  
Rui Zhao ◽  
Li Sheng

The noble gas compound containing a triple bond of xenon and transition metal Os (i.e. F4XeOsF4, isomer A) is predicted using quantum-chemical calculations. At the MP2 level of theory, the...


2018 ◽  
Vol 67 (6) ◽  
pp. 1100-1103 ◽  
Author(s):  
N. A. Anikin ◽  
A. M. Andreev ◽  
M. B. Kuz’minskii ◽  
A. S. Mendkovich

2004 ◽  
Vol 59 (11-12) ◽  
pp. 1512-1518 ◽  
Author(s):  
K. Koch ◽  
H. Schnöckel

The cation Al2Cp*+ descending from the tetrahedral Al4Cp*4 Cluster after using LDI as ionisation method in an FT-ICR mass spectrometer reacts with Cl2 in the gas phase. The investigation of this reaction together with quantum chemical calculations gives a new approach to the question of existence and stability of an aluminum-aluminum double bond.


2014 ◽  
Vol 50 (62) ◽  
pp. 8522-8525 ◽  
Author(s):  
Amrita Pal ◽  
Kumar Vanka

Full quantum chemical calculations with density functional theory (DFT) show that bond-strengthening back-donation to a π-diborene, recently discovered for transition metal systems (Braunschweig and co-workers, Nat. Chem., 2013, 5, 115–121), would be just as favored for Main Group silylene complexes.


Nukleonika ◽  
2015 ◽  
Vol 60 (4) ◽  
pp. 847-851 ◽  
Author(s):  
Michael Trumm ◽  
Bernd Schimmelpfennig ◽  
Andreas Geist

Abstract Although BTP (2,6-di(1,2,4-triazin-3-yl)pyridine) has been proven to be a highly effective N-donor ligand for the selective An(III)/Ln(III) separation, the origin of its selectivity is still under discussion. We present in this paper quantum-chemical calculations at the density functional theory (DFT) and MP2 level which highlight the role of the aquo ions in the separation process. Furthermore these data will be the reference for future force-field development to investigate the differences in An(III) complexation reactions compared to their Ln(III) counterparts.


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