The ¹⁴N quadrupole coupling in hexamethylene triperoxide diamine (HMTD)

Abstract

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 (14)N nuclear quadrupole resonance (NQR) spectrum; the spin relaxation rate is reasonably fast.

Solid-state NMR of quadrupolar halogen nuclei

“…The two most recent examples were reported in a 2007 paper by Persons and Harbison, in which they used samples of leucine HBr and tyrosine HBr to demonstrate their STREAQI method, as described in Section 3.1 (Fig. 18) [63]. Bromine-79 C Q values of 49.0 and 11.26 MHz were reported for L-leucine HBr and L-tyrosine HBr, respectively.…”

“…Variable-offset approaches will likely be required to make progress. Potential alternatives include the STREAQI and WURST approaches [58,59,63]. Regardless of the method used, there is still work to be done to build a better understanding of the structural and electronic factors which influence the quadrupolar and shielding interactions for 79/81 Br and 127 I.…”

“…Satellite-transition spectroscopy (SATRAS), where the MAS NMR spectrum of the satellite transitions is collected and analyzed [60][61][62], was used by Trill et al on a series of halide-containing sodalites [46]. More recently, Persons and Harbison collected 79 Br SSNMR spectra of several samples using their ''slow turning reveals enormous anisotropic quadrupolar interactions" (STREAQI) method [63]. The STREAQI method was shown to characterize the quadrupolar parameters of sites with moderately large QIs (10-50 MHz) using very slow MAS rates (e.g., 300 Hz), although the current analysis method does not take into account CSA.…”

Solid-State 79/81Br NMR and Gauge-Including Projector-Augmented Wave Study of Structure, Symmetry, and Hydration State in Alkaline Earth Metal Bromides

“…[22][23][24][25] Studies using single crystals have characterized bromide environments with more substantial QIs, such as in K 2 Pt(CN) 4 Br 0.3 • 3.2H 2 O, 26,27 tris-sarcosine CaBr 2 , 28,29 and deuterated glycyl-L-alanine HBr • H 2 O. 30 Recently, the "STREAQI" method was applied to measure the bromine QIs in L-leucine HBr and L-tyrosine HBr, 31 and 14 N and 81 Br SSNMR was used to study several polycrystalline C x H 2x+1 (CH 3 ) 3 NBr samples. 32 Current reviews pertaining to the NMR-active quadrupolar halogen nuclides 5,6,33 underscore the significant ongoing ad-vances in 35/37 Cl SSNMR spectroscopy.…”

“…For example, studies on microcrystalline samples include perbromates, – oxygen-doped BaFBr, and bromide-containing sodalites. – Studies using single crystals have characterized bromide environments with more substantial QIs, such as in K 2 Pt(CN) 4 Br 0.3 ·3.2H 2 O, , tris -sarcosine CaBr 2 , , and deuterated glycyl- l -alanine HBr·H 2 O . Recently, the “STREAQI” method was applied to measure the bromine QIs in l -leucine HBr and l -tyrosine HBr, and 14 N and 81 Br SSNMR was used to study several polycrystalline C x H 2 x +1 (CH 3 ) 3 NBr samples …”