Applications of 14N NMR Data in the Study of Inorganic Molecules

Probing Platinum Azido Complexes by 14N and 15N NMR Spectroscopy

“…In this work, we report precursors. These studies provide the first 15 N NMR data for azido groups in coordination complexes. We discuss one-and three-bond J( 15 N, 195 Pt) couplings for azido and am(m)ine ligands.…”

“…Pt) coupling constants provides a powerful method for identifying the ligands in the coordination spheres of both Pt II and Pt IV complexes. [16] 15 N has a spin quantum number I = 1 = 2 , but being only 0.37 % naturally abundant and possessing a low gyromagnetic ratio, it exhibits a receptivity approximately 50-times less than 13 C. The sensitivity of detection can be enhanced through the use of inverse ( 1 H-detected) methods by a factor of (j g1 H j / j g15 N j) 15 N nucleus have been determined to be about 53 s (303 K). [17] As a consequence of these long relaxation times (and perhaps the expense of 15 Nlabelling), there appear to be no previous reports of azide 15 N NMR resonances for metal azido complexes.…”

“…[16] 15 N has a spin quantum number I = 1 = 2 , but being only 0.37 % naturally abundant and possessing a low gyromagnetic ratio, it exhibits a receptivity approximately 50-times less than 13 C. The sensitivity of detection can be enhanced through the use of inverse ( 1 H-detected) methods by a factor of (j g1 H j / j g15 N j) 15 N nucleus have been determined to be about 53 s (303 K). [17] As a consequence of these long relaxation times (and perhaps the expense of 15 Nlabelling), there appear to be no previous reports of azide 15 N NMR resonances for metal azido complexes. Here, for the first time, we demonstrate that such experiments are indeed possible for Pt complexes with 15 N-enriched samples within reasonable acquisition times and furthermore, that information concerning the 1,3 J( 15 N, 195 Pt) scalar couplings may be readily determined, which can be related to trans influences and reactivity.…”

“…However, 14 N peaks are often broad due to the large quadrupole moment. [15] In addition, the low resonance frequency of 14 N (i.e., 43.3 MHz at 14.1 T, vs. 600 MHz for 1 H) can result in "ringing" or acoustic resonance within the probe, a consequence of which is rolling baselines in the spectra, making broad signals even harder to detect. We show here that the use of anti-ringing pulse sequences can greatly improve baselines and dramatically reduce the time needed for acquisition of good quality spectra.…”

“…[13,14] Pt azido comAbstract: Metal azido complexes are of general interest due to their high energetic properties, and platinum azido complexes in particular because of their potential as photoactivatable anticancer prodrugs. However, azido ligands are difficult to probe by NMR spectroscopy due to the quadrupolar nature of 14 N and the lack of scalar 1 H coupling to enhance the sensitivity of the less abundant 15 N by using polarisation transfer. In this work, we report precursors.…”