2 D NMR spectra for partially deuterated (CH 3 ND 3 ) 3 Bi,Br 9 showed that the phase transitions in this compound are related to the motion of the methylammonium cations. Single-crystal X-ray work at room temperature shows that the space group for [N(CH 3 ) 4 ] 3 Sb 2 Cl 9 is_P6 3 /mmc with a = 925.1 pm, c = 2173.4 pm, Z = 2. For (CH 3 NH 3 ) 3 Sb 2 Br 9 the space group is P3ml with a = 818.8 pm, c = 992.7 pm, Z = 1; in both cases the cations show dynamical disorder. The Rietveld analysis of the powder X-ray diffraction for (CH 3 NH 3 ) 3 Bi 2 Br 9 reveals the space group P3ml with a = 821.0, c -1000.4 pm, Z = 1 at room temperature; the compound is isomorphous with (CH 3 NH 3 ) 3 Sb 2 Br 9 . The crystal symmetries of the low-temperature phases of (CH 3 NH 3 ) 3 Bi 2 Br 9 and [N(CH 3 ) 4 ] 3 Bi 2 Br 9 were deduced from the results of the NQR spectroscopy.

The influence of the cations on the condensation of anions CdBr

No abstract

The crystal structures at room temperature of the N-chloro-N-(2,6-dichlorophenyl)-chloroacetamides 2,6-Cl 2 C 6 H 3 NClCOCCl 3 (1) and 2,6-Cl 2 C 6 H 3 NClCOCH 2 Cl (2) have been determined.(1): orthorhombic, Pbca. Z = 8, a = 2051.7(8) pm, b= 1134.8(4) pm, c = 1089.0(4) pm. (2): orthorhombic, Pbca, Z = S, a = 2078.7 (4) pm, b= 1487.9(4) pm, c = 694.0 (2) pm. The "CI NQR spectrum of (1) There is no problem in assigning in both compounds, on the basis of the known 35 C1 NQR frequency scale, the line Vj to the CI atom attached to the nitrogen atom and the lines v 5 and v 6 to the ring chlorines (Cl <2) and Cl (6) ). The crystal structures and NQR spectra of (1) and (2) are discussed together with literature data for 2,6-Cl 2 C 6 H 3 NHCOR, C 6 H 5 NC1C0R (where R = CC1 3 , CClH 2 fand other substituted acetamides.

The(4-(CHThe relations between Br-NQR and crystal structures are discussed.