Shi-qi Dou

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

Abstract 35Cl, 81Br, 121Sb, and 209Bi NQR of the title compounds was observed. According to the results of the temperature dependences of NQR frequencies and the DTA measurements, phase transitions take place in [N(CH3)4]3Bi2Br9 (Ttr=183K), [N(CH3)4]3Bi2Cl9 (Ttr = 155K), and (CH3NH3)3Bi2Cl3 (Ttr = 200 and 249 K). 2D NMR spectra for partially deuterated (CH3ND3)3Bi,Br9 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(CH3)4]3Sb2Cl9 is P63/mmc with a = 925.1 pm, c = 2173.4 pm, Z = 2. For (CH3NH3 ) 3Sb2Br9 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 (CH3NH3)3Bi2Br9 reveals the space group P3ml with a = 821.0, c - 1000.4 pm, Z = 1 at room temperature; the compound is isomorphous with (CH3NH3 )3Sb2Br9 . The crystal symmetries of the low-temperature phases of (CH3NH3)3Bi2Br9 and [N(CH3)4]3Bi2Br9 were deduced from the results of the NQR spectroscopy

Bromine NQR and Crystal Structures of Tetraanilinium Decabromotricadmate and 4-Methylpyridinium Tribromocadmate

Abstract The 79,81Br NQR spectra of tetraanilinium decabromotricadmate (1) and 4-methylpyridinium tribromocadmate (2 ) were studied as function of temperature and their crystal structures were determined. (C6H5NH3)4Cd3Br10 (1): Space group D1 52h - Pbca , Z = 4, a = 2507.8(7) pm, b = 1985.4(5)pm, c = 763.0(2)pm. Characteristic for the structure are trioctahedral units [Cd3Br10] condensed to planes. Within the units the octahedra are face connected and further condensed to planes via common corners. Two types of hydrogen bonds are observed. The 81Br NQR lines with frequencies (MHz, 298 K) of 62.98, 52.59, 43.39, 41.82, and 40.71 are little temperature dependent with positive and negative coefficients. The wide frequency range of the NQR lines is reflected by the wide range of the intraionic distances, 263 ≤ d(Br-Cd)/pm ≤300. (4-(CH3)C5H4NH)CdBr3 (2): C52h - P21/n, Z = 4, a = 1228.8(5}pm, b= 1168.5(5)pm, c = 758.3(3)pm, β = 95.30(1)°; the CdBr⊖3 ions are condensed to chains. The 81Br NQR spectrum is a triplet with frequencies (MHz, 298 K) of 66.01, 55.39, and 50.75. The temperature dependence is small, with positive and negative temperature coefficients. The distances d(Cd-Br) are 256 pm (Cd-Br(2)), 261 pm (Cd -Br(1)), and 284 pm (Cd-Br(3)) and in the chain [CdBr3]Br(1) and Br(3) are bridging atoms. The relations between Br-NQR and crystal structures are discussed.

Phase Diagram of the Orientationally Order-disorder Binary System 2,2-dimethyl-1,3-propanediol / 2,2-dimethyl-1,3-diaminopropane, [(CH3)2 C(CH2OH)2]x [(CH3)2C(CH2NH2)2]1-x · A Thermodynamic, X-ray, and 1H-NMR study

Abstract The phase diagram of the binary system [2,2-dimethyl-1,3-propanediol]x (1) / [2,2-dimethyl-1,3- diaminopropane]1-x (2) was studied by X-ray diffraction and DTA/DSC, for (2) also by 1H-NMR. The system is miscible over the whole concentration range 0 ≤ x ≤ 1 in the liquid state and in the plastic solid state, phase I, just below the melting point. At lower temperatures the system is demixing, and at room temperature two plastic mixed crystals coexist. The plastic phases of (1), (2), and (l)x(2)1-x crystallize face centered cubic, Fm3m, Z = 4, the lattice constants decreasing linearely with increasing x, and the lattice constants are: (1) a(327K) = 880.3 pm , (2) a(243K) = 905.6 pm. By single crystal X-ray diffraction the structure of the ordered phase II of (1) was refined at room temperature, monoclinic, P21/n, Z = 4, a = 596.9 pm, b = 1090.2 pm, c = 1011.0 pm, β = 99.74°. The results are in good agreement with the literature. The phase transition temperatures (in Kelvin) are T1→m = 399.2, TMm→1 = 399.7, T11→1 = 316.2, T1→11 = 308.2 for (1); = 300.2, = 301.7, T11→1 = 228.7, T1→n = 194.2 for (2). Strong hysteresis is observed for the transition T1→11 in (2). In the mixed systems (1)x(2)1-x, 0 < x < 1, the disordered phases do not order even by quenching to liquid nitrogen temperature. High resolution 1 H-NMR measurements are reported for phase I of (2) as a function of temperature. The “liquid” 1H-NMR spectrum is present far below the thermodynamic phase transition temperature T11-1, overlapping the wide line unresolved powder spectrum of phase II.

N-Trichloro- and dichloroacetyl amino acids and compounds of amino acids with halogeno acetic acids: 35Cl nuclear quadrupole resonance spectroscopy; crystal structure of N-trichloroacetyl-glycine, -dl-alanine, and -l-alanine

Abstract The crystal structures of N - trichloroacetyl - glycine ( N - TCA - G ), N-trichloroacetyl-dl -alanine ( N-TCA- dl -A ), and N-trichloroacetyl- l -alanine ( N-TCA- l -A ) were determined. In addition, the 35 Cl NQR spectra of these n -trichloroacetyl amino acids, of N-trichloroacetyl- l -valine ( N-TCA- l -V ), and of N - dichloroacetyl - glycine and - l -alanine were measured, mostly as a function of temperature. Compounds of glycine and l -alanine with chlorodifluoroacetic acid, of glycine and l -leucine with monochloroacetic acid, of glycine and l -leucine with dichloroacetic acid, and of glycine and l -leucine with trichloroacetic acid were also studied using 35 Cl NQR. The structures (in picometres and degrees) were found to be as follows. N - TCA - G : Pna2 1 , Z = 8, a = 1641, b = 1002, c = 1018. N-TCA- dl -A : C2 c , Z = 8, a = 3280, b = 556, c = 1031, β = 96.68. N-TCA- l -A: P1 , Z = 2, a = 967, b = 949, c = 619, α = 74.97, β = 74.20, γ = 61.20. The 35 Cl NQR frequencies (ν) were observed in the range 35–41 MHz, and decrease with increasing temperature. Some of the resonances bleach out at a temperature ( T b ) far below the melting temperature; this provides information about the crystal structures at 77 K. No phase transitions were observed by differential thermal analysis between 77 and 295 K. The crystal structures are discussed in connection with the NQR results, and conclusions are drawn about the structures of the compounds for which only 35 Cl NQR data are available.

Bond distances and bond angles of the C10 skeleton in naphthalene derivatives as hard bond parameters:35Cl NQR and structure of 1,8-diaminonaphthalene · Cl2HCCOOH, 1,8-diaminonaphthalene · Cl3CCOOH, 1-aminonaphthalene · Cl3CCOOH, and 1,8-diaminonaphthalene

The structures of several naphthalene derivatives and their35Cl NQR spectra have been investigated. 1,8-Diaminonaphthalene,C2v9-Pna21, Z = 8,a (in pm) = 881,b = 1577,c = 1213; 1,8-diaminonaphthalene monodichloroacetate,C2h6-C2/c, Z = 8,a = 2050,b = 584,c = 2333,β (in degrees) = 110.1; 1,8-diaminonaphthalene monotrichloroacetate,C11-P¯1, Z=2,a=1211,b=1062,c=589,α=74.8,β=80.1,γ=70.9; 1-aminonaphthalene trichloroacetate,D2h15-Pbca, Z=8,a=2347,b=1289,c=889. The35Cl NQR spectrum of 1,8-diaminonaphthalene monodichloroacetate is a doublet, the frequencies decreasing with increasing temperature from 77 to 217 K at which temperatureTb the NQR signals bleach out. A35Cl NQR triplet is found for 1,8-diaminonaphthalene monotrichloracetate in the range 77 ≤ 77K ≤ 207 (=Tb). 1-Amino-naphthalene trichloroacetate shows a35Cl NQR triplet, too, withTb = 136 K. Characteristic for the intermolecular interactions are hydrogen bonds in the chloroacetic acid salts; each NH3 group forms three hydrogen bonds, and of the two oxygens one is involved in two such bonds, one in one bond. Thereby units of two cations and two anions are formed, and these dirners are connected to strings by hydrogen bonds. Additional van der Waals interactions between the chlorine atoms and the naphthalene ring system are observed. Comparison of the intramolecular bond distances C(i)-C(j) of the C10 naphthalene skeleton for 41 naphthalene derivatives (present data and literature) shows that the bond distances C(i)-C(j)are little influenced by substitution, as is the mean bond length. Shorter and longer distances prove a partial localization of charge at C(1)-C(2), C(3)-C(4), C(5)-C(6), and C(7)-C(8). Regularities within the bond angles and characteristic influences of 1,8-disubstitution on it are discussed.

Crystal structure and 35Cl NQR of (±) β- (trichloromethyl) -β-propiolactone

Abstract The crystal structure of (±) β- (trichloromethyl) -β-propiolactone, C 4 H 3 Cl 3 0 2 , is reported ( T =294 K); space group C 5 2h P 2 l / c , a =1002(1) pm, b =565.O(5) pm, c=1225(l) pm, β=9397 (3)∮ Z =4, V =691.85(2)×10 6 pm 3 . A weak hydrogen bond is observed between H (C(3)) and the carbonyl oxygen 0(2). The 35 Cl NQR spectrum shows three lines in the range 77≤ T (K)≤310. At 77K the resonance frequencies are observed at 39.822(5) MHz, 38.905(5) MHz and 38.322(5) MHz.

Crystal structure and halogen NQR of diammoniumalkane halides

Abstract The crystal structures of the isomorphous compounds 1,3-diammoniumpropyl dibromide and diiodide are reported. The structure was found to be: monoclinic, C 4 2 h − P2 n , Z = 4 . The lattice constants of [H 3 N(CH 2 ) 3 NH 3 ] 2+ . 2Br − are a = 1343.8 pm, b = 457.9 pm, c = 1347.1 pm and β = 109.14°; those for [H 3 N(CH 2 ) 3 NH 3 ] 2+ . 2I − are a = 1421.3 pm, b = 478.0 pm, c = 1419.6 pm and β = 110.10°. The diammoniumpropyl cations are centrosymmetric and there are two formula units in the asymmetric unit. Hydrogen bonds NH ... X − (X = Br or I) were observed. The discrepancy in the 79 Br and 127 I NQR spectra which showed no isomorphism, is removed by reinvestigation of the 79,81 Br NQR spectra. At 77 K, ν 1 ( 79 Br ) = 24.432 MHz and ν 2 ( 79 Br ) = 14.042 MHz . The structures and the NQR spectra are compared and discussed.

Tetraguanidium Hexabromocadmate, [C(NH2)3]4[CdBr6]. Crystal Structure and Bromine Nuclear Quadrupole Resonance

Abstract The 79, 81Br NQR spectra of tetraguanidinium hexabromocadmate, [C(NH2)3]4[CdBr6] have been studied as a function of temperature from 77 K to 390 K and the crystal structure of the compound was determined at room temperature. The title compound crystallizes monoclinic, P21/c, with four formula units in the unit cell, a = 839.2(3) pm, b = 1895.8(6) pm, c= 1527.4(5) pm, β= 108.14(1)°. The anion [CdBr6]4⊖ is an isolated octahedron, with bond lengths 275≤d(Cd-Br)/pm ≤ 281, and bond angles 88 ≤(Br-Cd-Br)/° ≤95, slightly distorted by hydrogen bonds N -H ··· Br. The 81Br NQR sextet, in dependence from temperature, shows positive and negative temperature coefficients. At 77 K the 81Br NQR frequencies have been found between 42.42 MHz and 31.99 MHz; the 79Br NQR at the frequencies expected from the nuclear quadrupole moment ratio Q(79Br)/Q(81Br). Relations between the 81Br NQR spectrum, the crystal structure, and the hydrogen bonds are discussed.

35Cl NQR and Crystal Structure Studies of Salts of Chlorodifluoro- and Dichloroacetic Acid

Abstract The 35Cl NQR spectra of several chlorodifluoroacetates were studied as a function of temperature, including the acid ClF2CCOOH. The cations were: Ammonium, guanidinium, paramethylanilinium. Also some acid salts M⊕ClF2CCOO⊖ • n - ClF2CCOOH ( n > l ) were studied by 35Cl NQR. The bleaching temperatures of the NQR signals were determined. In the para-methylanilinium salt and in the guanidinium salt a phase transition has been observed. The crystal structure of guanidinium chlorodifluoroacetate has been determined at room temperature (a = 1089 pm, 6 = 845 pm, c = 832 pm, space group Pnma, Z = 4). For comparison, guanidinium dichloroacetate was studied by 35Cl NQR and by X-ray diffraction, too: P21/c, Z = 4 , a = 804pm, b = 1202 pm, c = 1080 pm, ß = 131.58°. For guanidinium chlorodifluoroacetate and chlorodifluoroacetic acid, the 35Cl spin lattice relaxation time T1 and the line width have been followed up as a function of temperature. Therefrom, the activation energies of the reorientation motion of the group -CF2C1 have been determined to be 14 kJ • mol-1 (from T1) and 12.5 kJ • mol- 1 (from Δv) for the pure acid and 9.2 kJ • mol-1 and 8.8 kJ • mol-1 , respectively, for the guanidinium salt.

Structure and Bonding of Tribromocadmates, ACdBr3, A = NH4, Rb, Cs, CH3NH3, (CH3)2NH2, (CH3)4N], [H2NNH3, and (H2N)3C. An X-ray Diffraction and 79-81Br NQR Study

Abstract The 79-81Br NQR spectra of tribromocadmates with the cations K⊕, NH4⊕, Rb⊕, Cs⊕, CH3NH3⊕, (CH3)2NH2⊕, (CH3)4N⊕, H2NNH3⊕, and C(NH2)3⊕ were studied as functions of temperature from 77 K on up to T>300 K. CsCdBr3 shows a singlet 81Br NQR spectrum over the whole temperature range studied. [CH3NH3]CdBr3, with one 81Br NQR line spectrum at room temperature, experiences a phase transition at 167 K; below this temperature an 18-line spectrum is observed. In [(CH3)4N]CdBr3 (phase II), at 290 K, a singlet 81Br NQR is present as is in the high temperature phase III (TII.1 , = 390 K); the low temperature phase III (TII,m, = 160 K has a triplet 81Br NQR spectrum. KCdBr3 shows an 81Br NQR doublet spectrum, as do RbCdBr3, [H2NNH3]CdBr3, and [C(NH2)3]CdBr3. 81Br NQR triplets are observed for [(CH3)2NH2]CdBr3 and NH4CdBr3. Several crystal structures were determined (at room temperature). [(CH3)4N]CdBr3: P63/m, Z = 2, a - 940 pm, c = 700 pm, disordered cation, single chain Perovskite with face connected [CdBr6]- octahedra (nearly CsNiCl3-type). [(CH3)2NH2]CdBr3: P21/c, Z = 4, a = 898 pm, 6 = 1377 pm, c = 698 pm, ß = 91.2°, face connected [CdBr3-octahedra single chain Perovskite. NH4CdBr3: Pnma, Z = 4, a = 950 pm, b = 417 pm, c= 1557 pm, with a double chain of condensed [CdBr6]-octahedra, NH4CdCl3-type. [N2H5]CdBr3: P2,/c, Z = 4, a = 395 pm, 6 = 1749 pm,c = 997 pm,ß = 94.2°, double chain polyanion similar to NH4CdBr3. [C(NH2)3]CdBr3: C2/c, Z = 4, a = 778 pm, 6 = 1598 pm, c = 746 pm, ß = 110.2°, a single chain Perovskite with a chain of condensed trigonal bipyramids [CdBr5]. Three types of anion chains of CdBr3 have been observed: Single octahedral chains, face connected; double octahedral chains, edge connected; a trigonal-bipyramidal chain, edge connected. The relation between the crystal structure and the Br NQR is discussed