Proton Magnetic Resonance and internal motions in tetramethyl ammonium halides

NQR and X-ray Studies of [N(CH3)4]3M2X9 and (CH3NH3)3M2X9 (M = Sb,Bi; X = Cl,Br)

“…Such NMR results are known in literature e.g. for [N(CH 3 ) 4 ]X (X = CI, Br, I [16]; X = CdCl 3 [17]). The disappearance of 81 Br NQR lines around 100 K is due to the onset of these cation reorientations.…”

“…in Cs 3 Bi 2 Br 9 , [3], and the third one is built up of isolated M 2 X| e anions as found in [N(CH 3 ) 4 ] 3 Sb 2 Br 9 [4]. We tried to investigate the structures of A 3 M 2 X 9 in more detailed X-ray diffraction experiments and by observing NQR * Presented at the Xlth International Symposium on Nuclear Quadrupole Resonance Spectroscopy, London, United Kingdom, July [15][16][17][18][19]1991. Reprint requests to Dr. H. Ishihara, Dept.…”

14N and 81Br Quadrupolar Nuclei as Sensitive NMR Probes of n-Alkyltrimethylammonium Bromide Crystal Structures. An Experimental and Theoretical Study

“…Internal mobilities involving the TMA + cations inside TMAX salts have been reported in the past. [87][88][89][90][91][92] Several types of movements occur: rotation of the methyl groups around the C-N C 3 axes, rotation of TMA + cations by site jumps around the C-N C 3 and C 2 axes, and isotropic tumbling of TMA + cations. From 1 H and 2 H NMR data, 89,91,92 it has been shown that the first type (methyl rotation) starts at low temperature (T around 150-170 K) and it is not expected to strongly modify the EFG at the N site.…”

“…[87][88][89][90][91][92] Several types of movements occur: rotation of the methyl groups around the C-N C 3 axes, rotation of TMA + cations by site jumps around the C-N C 3 and C 2 axes, and isotropic tumbling of TMA + cations. From 1 H and 2 H NMR data, 89,91,92 it has been shown that the first type (methyl rotation) starts at low temperature (T around 150-170 K) and it is not expected to strongly modify the EFG at the N site. The other types of movement start at slightly higher temperatures and can be combined together and possibly modify the 14 N quadrupolar coupling interaction.…”

Conductivity, NMR and crystallographic study of N,N,N,N-tetramethylammonium dicyanamide plastic crystal phases: an archetypal ambient temperature plastic electrolyte material

“…15,[36][37][38][39][40] However, in common with the DCA À system investigated here, in the SCN À , 15 MBr 6 À39 and MCl 6 À (M ¼ Pt, Te, Sn) 40 compounds, the second moment is observed to decrease smoothly over a range of 50-100 C from that of the rigid state, indicating that the anion has a strong role to play in facilitating the onset of these motions. In other, less symmetric alkylammonium-based systems, both rapid 19,37,38,[41][42][43][44][45][46][47] and gradual [48][49][50][51][52][53] decreases in 1 H second moment from the rigid state have been observed. It is worth noting that in all of the above systems only one state is described at any temperature.…”