Density Functional Theory/Finite Perturbation Theory Calculations of Nuclear Spin−Spin Coupling Constants for Polyhedral Carboranes and Boron Hydrides

Autor:	Michael Barfield, Thomas Onak, and Jojo Jaballas
Rok vydání:	1999
Předmět:	Coupling constant Fermi contact interaction Geminal Chemistry Boranes General Chemistry Biochemistry Molecular physics Catalysis Colloid and Surface Chemistry Computational chemistry Density functional theory Perturbation theory Spin (physics) Vicinal
Zdroj:	Journal of the American Chemical Society. 121:2850-2856
ISSN:	1520-5126 0002-7863
DOI:	10.1021/ja9841097
Popis:	An extensive study is presented of nuclear spin−spin coupling constants in 25 polyhedral boranes using density functional theory/finite perturbation theory (DFT/FPT) methods to determine the Fermi contact term. Scalar couplings were obtained at either the UB3LYP/6-311G** or the UB3LYP/6-311++G** level, with molecular structures fully optimized at the B3LYP/6-31G* DFT level. The calculated results are in good agreement with the solution experimental data for a wide range of directly bonded, geminal, vicinal, and long-range coupling constants. The largest disparities occur for 1J(11B−1H) and 1J(13C−1H) values greater than 120 Hz. These are underestimated on average by about 5%, a value close to that expected (4%) from the effects of motional averaging on directly bonded coupling constants. The accurate prediction of coupling constants in polyhedral boron compounds will be extremely helpful in their detailed NMR spectral analyses.
Databáze:	OpenAIRE
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