Microwave Determination of the Structure of Borine Carbonyl and of the Nuclear Moments of the Stable Boron Isotopes

Gordy, Walter; Ring, Harold; Burg, Anton B.

doi:10.1103/physrev.78.512

Cited by 64 publications

(10 citation statements)

References 17 publications

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“…. On the fully relaxed surface, the obtained C−B and C−O bond distances and the shifts in ν CO are in reasonable agreement with the previous theoretical studies and experimental values 16,[70][71][72]. The non-CT binding forces (frozen interaction and polarization) yield only a weakly bound adduct with the C−B distance, r(CB), being over 3 Å, and r(CB) is only shortened by ∼0.2 Å upon moving from the Frz to Pol surface.…”

supporting

confidence: 90%

Variational Forward–Backward Charge Transfer Analysis Based on Absolutely Localized Molecular Orbitals: Energetics and Molecular Properties

Loipersberger

Mao

Head‐Gordon

2020

J. Chem. Theory Comput.

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To facilitate the understanding of charge transfer (CT) effects in dative complexes, we propose a variational forward-backward (VFB) approach to decompose the overall CT stabilization energy into contributions from forward and backward donation in the framework of energy decomposition analysis based on absolutely localized molecular orbitals (ALMO-EDA). Such a decomposition is achieved by introducing two additional constrained intermediate states in which only one direction of CT is permitted. These two "one-way" CT states are variationally relaxed such that the associated nuclear forces can be readily obtained. This allows for a facile integration into the previously developed adiabatic EDA scheme so that the molecular property changes arising from 1 forward and back donation can be separately assigned. Using ALMO-EDA augmented by this VFB model, we investigate the energetic, geometric, and vibrational features of complexes composed of CO and main group Lewis acids (BH 3 , BeO/BeCO 3), and complexes of the N 2 , CO, and BF isoelectronic series with [Ru(II)(NH 3) 5 ] 2+. We identify that the shift in the stretching frequency of a diatomic π-acidic ligand (XY), such as CO, results from a superposition of the shifts induced by permanent electrostatics and backward CT: permanent electrostatics can cause an either red or blue shift depending on the alignment of the XY dipole in the dative complex, and this effect becomes more pronounced with a more polar XY ligand; the back-donation to the antibonding π orbital of XY always lowers the X−Y bond order and thus red-shifts its stretching frequency, and the strength of this interaction decays rapidly with the intermolecular distance. We also reveal that while σ forward donation contributes significantly to energetic stabilization, it affects the vibrational feature of XY mainly by shortening the intermolecular distance, which enhances both the electrostatic interaction and backward CT but in different rates. The synergistic effect of the forward and backward donations appears to be more significant in the transition metal complexes, where the forward CT plays an essential role in overcoming the strong Pauli repulsion. These findings highlight that the shift in the XY stretching frequency is not a reliable metric for the strength of π back-donation. Overall, the VFB-augmented EDA scheme that we propose and apply in this work provides a useful tool to characterize the role played by each physical component that all together lead to the frequency shift observed.

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supporting

confidence: 90%

Variational Forward–Backward Charge Transfer Analysis Based on Absolutely Localized Molecular Orbitals: Energetics and Molecular Properties

Loipersberger

Mao

Head‐Gordon

2020

J. Chem. Theory Comput.

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“…These gave a dipole moment of 1.698 f 0.02 D. This value is ca. 6% lower than that reported previously [2] but probably within the uncertainties of that determination.…”

Section: Dipole Momentsupporting

confidence: 58%

Microwave spectrum, structure, quadrupole coupling constants and dipole moment of carbon monoxide-borane

Venkatachar

Taylor

Kuczkowski

1977

Journal of Molecular Structure

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TheJ=O-landJ=l-2 transitions of thirteen isotopic species of carbon monoxideborane (BH,CO) have been measured. The heavy atom rq structural parameters have been calculated in several ways so as to minimize the effects of the small carbon coordinate. The structural parameters found are: d(B-C) = 1.534 * 0.01 A,d(C-O)= 1.135 f 0.01 A. d(B-H)= 1.221 * 0.001 A, LHBC= 103.79 + 0.06", andLHBH = 114.50 * 0.15". In addition, a complete r, structure has been calculated by least-squares fitting the moments of inertia of all the isotopic species. A dipole moment of 1.698 f 0.02 D was determined.

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“…Perhaps some will be reluctant to accept relation (22) on the basis that it seems to require too much formal charge on certain atoms in polyatomic molecules. That molecules have a way of avoiding excessive charges without violating this relation can be seen from an examination of table 5.…”

Section: For Ngc-mentioning

confidence: 99%

Microwave spectroscopy. Introductory paper: quadrupole couplings, dipole moments and the chemical bond

Gordy¹

1955

Discuss. Faraday Soc.

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110

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Microwave Determination of the Structure of Borine Carbonyl and of the Nuclear Moments of the Stable Boron Isotopes

Cited by 64 publications

References 17 publications

Variational Forward–Backward Charge Transfer Analysis Based on Absolutely Localized Molecular Orbitals: Energetics and Molecular Properties

Variational Forward–Backward Charge Transfer Analysis Based on Absolutely Localized Molecular Orbitals: Energetics and Molecular Properties

Microwave spectrum, structure, quadrupole coupling constants and dipole moment of carbon monoxide-borane

Microwave spectroscopy. Introductory paper: quadrupole couplings, dipole moments and the chemical bond

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