Boron nuclear quadrupole couplings and localized electronic wave functions in the boron clusters o-carborane and o-silaborane

Abstract

Articles you may be interested inBoron quadrupole coupling in o r t h ocarborane. NMR study of an oriented liquid sample J. Chem. Phys. 85, 3217 (1986); 10.1063/1.450990 Local space approximation for configuration interaction and coupled cluster wave functions J. Chem. Phys. 85, 2791 (1986); 10.1063/1.451036 Boron nuclear quadrupole coupling in o and mcarborane (B1 0C2H1 2) J. Chem. Phys. 85, 3136 (1986); 10.1063/1.450980 Molecular reorientation and boron nuclear quadrupole interaction in crystalline o r t h ocarboraneThe 11 B nuclear quadrupole couplings in ''o-silaborane'' ͓1,2-dimethyl-1,2disila-closo-dodeca-borane͑12͒, B 10 Si 2 ͑CH 3 ) 2 H 10 ] were measured at 77 K with a nuclear quadrupole double resonance spectrometer with rapidly switched magnet. Three 11 B transitions were found which were assigned by comparison with ab initio calculations of the electric field gradients. The surprising difference in the order of the quadrupole couplings of equivalent borons in o-silaborane and the corresponding carbon compound o-carborane ͑B 10 C 2 H 12 ) is explained by the different valence bond structures of the two boron clusters which were obtained by localization of the electronic wave functions.

Detection of Anisotropic Hyperfine Transitions in Zero Magnetic Field Using Field-Cycling Techniques

“…The experiment was carried out with our homebuilt fieldcycling spectrometer (12). The main part of the spectrometer is a rapidly switched solenoid coil into which the tail of a liquid helium cryostat fits.…”

Resonance and structural assignment in (car)borane clusters using 11B residual quadrupolar couplings

“…The quadrupolar nature of the 11 B nucleus can provide valuable information due to its coupling to the electric field gradient (EFG) which is highly sensitive to the closest coordination environment of the boron atom. 8 Quadrupole coupling constants are most commonly derived from standard solid state NMR measurements, but very difficult to extract if more than 1–2 chemically distinct boron atoms are present in the cluster. Here, we present a strategy to obtain the correct structure and 11 B resonance assignment for two closo -carboranes (B 10 C 2 H 12 ), a derivative thereof and the nido -borane B 10 H 14 (Scheme 1), using 11 B residual quadrupolar couplings (RQCs), and/or one-bond 11 B– 1 H and 13 C– 1 H residual dipolar couplings (RDCs) obtained under weakly aligned conditions.…”

“…The EFGs correspond to quadrupole coupling constants between 1.4 and 2.1 MHz, which is in agreement with previous calculations or experimental data based on 11 B relaxation or nuclear quadrupole resonance. 8…”