TY - JOUR

T1 - Isolated versus condensed anion structure IV

T2 - An NQR study and X-ray structure analysis of [H3N(CH2)3NH3]CdI4 · 2H2O, [H3CNH2(CH2)3NH 3]CdBr4, [(CH3)4N]2CdBr4, and [(CH3)3S]2CdBr4

AU - Ishihara, Hideta

AU - Horiuchi, Keizo

AU - Dou, Shi Qi

AU - Gesing, Thorsten M.

AU - Buhl, J. Christian

AU - Paulus, Helmut

AU - Fuess, Hartmut

N1 - Funding Information: Two of us, H. I. and K. H., are thankful to the Alexander von Humboldt-Stiftung for a fellowship. The support of the "Fonds der Chemischen Industrie" and of the Deutsche Forschungsgemeinschaft is acknowledged, too.

PY - 1998/8/1

Y1 - 1998/8/1

N2 - The phase I of [H3N(CH2)3NH3]CdI4 · 2H2O (1) crystallizes with isolated [CdI4]2- tetrahedra; monoclinic, C2/c, Z = 8, a = 1702.6 (3), b = 1459.3 (3), c = 1555.5 (3) pm, and β = 120.32 (3)° at 299 K. (1) shows a first-order phase transition at 7I↔II = 245 K. The eight 127I(v1) NQR lines in phase II change discontinuously into four lines in phase I. The transition entropy from DSC measurements, ΔS = 5.0 J K-1 mol-1, shows that this transition is probably due to order-disorder of cations. [H3CNH2(CH2)3NH 3]CdBr4 (2) crystallizes with isolated [CdBr4]2- tetrahedra; orthorhombic P212121, Z = 4, a = 1447.8 (5), b = 1280.3 (4), c = 709.7 (3) pm at 299 K. (2) shows four 81Br NQR lines between 77 and around 325 K, above which temperature the lines disappear. [(CH3)4N]2CdBr4 (3) shows a second-order phase transition at TI↔II = 271 K. Three of four 81Br NQR lines in phase II disappear below this transition point, the other line can be observed up to 315 K. The transition entropy, ΔS = 9.01 J K-1 mol-1, indicates that the transition is an order-disorder type of the cations. [(CH3)3S]2 CdBr4 (4) shows a first-order type phase transition at TI↔II = 304 K. The four lines spectrum of 81Br NQR is observed in phase II and disappears above the transition point. The transition entropy, ΔS = 46.8 J K-1 mol-1 is abnormally large. The role of the hydrogen bond and the bridging power between the halogen and cadmium atoms upon the formation of the condensed anion structure is discussed.

AB - The phase I of [H3N(CH2)3NH3]CdI4 · 2H2O (1) crystallizes with isolated [CdI4]2- tetrahedra; monoclinic, C2/c, Z = 8, a = 1702.6 (3), b = 1459.3 (3), c = 1555.5 (3) pm, and β = 120.32 (3)° at 299 K. (1) shows a first-order phase transition at 7I↔II = 245 K. The eight 127I(v1) NQR lines in phase II change discontinuously into four lines in phase I. The transition entropy from DSC measurements, ΔS = 5.0 J K-1 mol-1, shows that this transition is probably due to order-disorder of cations. [H3CNH2(CH2)3NH 3]CdBr4 (2) crystallizes with isolated [CdBr4]2- tetrahedra; orthorhombic P212121, Z = 4, a = 1447.8 (5), b = 1280.3 (4), c = 709.7 (3) pm at 299 K. (2) shows four 81Br NQR lines between 77 and around 325 K, above which temperature the lines disappear. [(CH3)4N]2CdBr4 (3) shows a second-order phase transition at TI↔II = 271 K. Three of four 81Br NQR lines in phase II disappear below this transition point, the other line can be observed up to 315 K. The transition entropy, ΔS = 9.01 J K-1 mol-1, indicates that the transition is an order-disorder type of the cations. [(CH3)3S]2 CdBr4 (4) shows a first-order type phase transition at TI↔II = 304 K. The four lines spectrum of 81Br NQR is observed in phase II and disappears above the transition point. The transition entropy, ΔS = 46.8 J K-1 mol-1 is abnormally large. The role of the hydrogen bond and the bridging power between the halogen and cadmium atoms upon the formation of the condensed anion structure is discussed.

UR - http://www.scopus.com/inward/record.url?scp=0038938246&partnerID=8YFLogxK

U2 - 10.1515/zna-1998-0813

DO - 10.1515/zna-1998-0813

M3 - Article

AN - SCOPUS:0038938246

VL - 53

SP - 717

EP - 724

JO - Zeitschrift fur Naturforschung - Section A Journal of Physical Sciences

JF - Zeitschrift fur Naturforschung - Section A Journal of Physical Sciences

SN - 0932-0784

IS - 8

ER -