Electric field gradients and Sternheimer-type properties of the BrCl molecule: correlated, relativistic, ab initio calculations and modelling of nuclear quadrupole coupling constants in complexes B ⋯ BrCl

Abstract We present ab initio Hartree-Fock calculations of electric field gradients, which are related to experimental determinations of nuclear quadrupole coupling constants. The nucleus of special interest is 17O but other nuclei in the molecules, especially 14N, 2H and 33S are included. The calculations were performed (a) as single molecules either at the SCF and MP2 correlated levels, (b) as clusters of molecules about a test site, or (c) as lattice calculations computed in the unit cell environment. The basis sets are triple zeta valence plus polarisation in (a). Because of limitations in exponent range in (c), the bases in both (b) and (c), where comparison was sought, are DZ at the SCF level.

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14N Nuclear Quadrupole Coupling in Heterocyclic Compounds, Part 2. A Comparison of ab initio Calculations and Experimental Results for the Azoles and Azines

Zeitschrift für Naturforschung A ◽

10.1515/zna-1981-0107 ◽

1981 ◽

Vol 36 (1) ◽

pp. 34-50

Author(s):

Michael H. Palmer ◽

Isobel Simpson ◽

Robert H. Findlay

Keyword(s):

Ab Initio Calculations ◽

Ab Initio ◽

Coupling Constants ◽

Electric Field Gradients ◽

Field Gradients ◽

Double Zeta ◽

Quadrupole Coupling ◽

Quadrupole Resonance ◽

Nuclear Quadrupole ◽

Comparison Of The Results

Ab initio calculations of double zeta quality have been reported for the conjugated 5- and 6- membered ring heterocycles containing NH and NMe groups. The electric field gradients were calculated and the derived nuclear quadrupole coupling constants (NQCC) compared, both in magnitude and direction, with those obtained by microwave spectroscopy and by nuclear quadrupole resonance. A comparison of the results with those of the corresponding O- and S-heterocycles, and with acyclic compounds has been given, and it was shown that aromaticity considerations were of no relevance to the NQCC values at pyridine-like N; planarity of the N atom at N-1 in the systems 2 c-9 c is responsible for the very low magnitude of Xπ, and this is clearly associated with the level of π-donation from N-1; this is a function of position of the other ring N atoms, and appears to become saturated as the ring positions become predominantly N. In particular three contiguous N atoms seem to have less effect than two N atoms

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The ab initio Calculation of Nuclear Quadrupole Coupling Constants and their Comparison with Experiment

Zeitschrift für Naturforschung A ◽

10.1515/zna-1990-3-425 ◽

1990 ◽

Vol 45 (3-4) ◽

pp. 357-367 ◽

Cited By ~ 2

Author(s):

Michael H. Palmer

Keyword(s):

Ab Initio ◽

Single Molecule ◽

Ab Initio Calculation ◽

Coupling Constants ◽

Structural Variations ◽

Electric Field Gradients ◽

Field Gradients ◽

Comparison With Experiment ◽

Quadrupole Coupling ◽

Nuclear Quadrupole

Abstract Ab initio calculations of electric field gradients (EFG) and conversion to nuclear quadrupole coupling constants (NQCC) are described, with particular reference to 14 N and 10,11B. The correlation of EFG and NQCC for a series of boranes leads to the value 8.32 MHz/a.u. (0.0354 barn) for Q(11B). The structural variations of these microwave and single molecule calculations of 10,11 B NQCC are discussed.

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