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The 14N Quadrupole Coupling In Hexamethylene Triperoxide Diamine (Hmtd), John Persons, Gerard S. Harbison
The 14N Quadrupole Coupling In Hexamethylene Triperoxide Diamine (Hmtd), John Persons, Gerard S. Harbison
Gerard Harbison Publications
Using high-field NMR, we have determined the magnitude of the nuclear quadrupole interaction in hexamethylene triperoxide diamine (HMTD), the explosive allegedly used in the London bombings of July 2005. The experimental quadrupolar coupling constant, 5.334 MHz, is in good agreement with quantum chemical calculations. The predicted single zero-field transition frequency should lie in a relatively empty part of the 14N nuclear quadrupole resonance (NQR) spectrum; the spin relaxation rate is reasonably fast.
Calculation Of 13C Chemical Shifts In Rna Nucleosides: Structure-13C Chemical Shift Relationships, Paolo Rossi, Gerard S. Harbison
Calculation Of 13C Chemical Shifts In Rna Nucleosides: Structure-13C Chemical Shift Relationships, Paolo Rossi, Gerard S. Harbison
Gerard Harbison Publications
Isotropic 13C chemical shifts of the ribose sugar in model RNA nucleosides are calculated using SCF and DFT-GIAO ab initio methods for different combinations of ribose sugar pucker, exocyclic torsion angle, and glycosidic torsion angle. Idealized conformations were obtained using structures that were fully optimized by ab initio DFT methods starting with averaged parameters from a collection of crystallographic data. Solid-state coordinates of accurate crystal or neutron diffraction structures were also examined directly without optimization. The resulting 13C chemical shifts for the two sets of calculations are then compared. The GIAO-DFT method overestimates the shifts by an average …