and Mössbauer spectroscopy studies corroborate the intrinsic nature of SCM behavior regardless of weak interchain magnetic interactions, which lead to the coexistence of metamagnetism but not long-range magneticordering. Moreover, detailed magnetic investigations indicate that the system is not only within the “Ising limit” but also in the “finite-size” regime.
conformation of the COO·HOH species. The O(3W)···O hydrogen bond in the optimised half of a dimer structures is shorter in comparison with that in the crystal. In optimised structures of dimer the hydrogen bond lengths vary with the applied method and they are longer than those in the crystal. The O(3W)···O distances in dimer calculated by the B3LYP/6-31G(d,p) method are comparable (2.868 and 2.854 A) but in
摘要 通过 X 射线衍射、MP2 和 B3LYP 计算、FT-IR、拉曼、1H 和 13C NMR 光谱研究了 1-甲基吡啶鎓-4-羧酸盐一水合物的结构。晶体为三斜晶系,空间群 Pī,a = 6.747(1), b = 7.6164(8), c = 7.709(1) A, α = 72.30(1)°, β = 72.26(2)°, γ = 89.81(1)°,V = 357.7(1) A3,Z = 2。两个 1-methylpyridinium-4-carboxylate 一水合物分子通过晶体对称中心相关联,由一对水分子通过两个 O 连接成二聚体(3W)–H...O 氢键长度为 2.786(2) 和 2.957(1) A. 计算的分子几何与 X 射线数据非常吻合,除了 COO·HOH 物种的构象。与晶体中的氢键相比,优化的二聚体结构的一半中的O(3W)...O氢键较短。在二聚体的优化结构中
Meyer,H., Monatshefte fur Chemie, 1903, vol. 24, p. 199,200
作者:Meyer,H.
DOI:——
日期:——
Hydrogen bonds and conformational analysis of bis(1-methylisonicotinate) hydrochloride monohydrate by X-ray diffraction, vibrational spectra and B3LYP calculations
作者:M. Szafran、A. Katrusiak、Z. Dega-Szafran
DOI:10.1016/j.molstruc.2006.01.033
日期:2006.8
In the crystal structure of bis(1-methylisonicotinate) hydrochloride monohydrate, (MIN)(2)H.Cl-H2O, 1-methylisonicotinate betaines are hemiprotonated and form a homoconjugated cation through a short asymmetric O . H . O hydrogen bond of length 2.456(3) angstrom. Water molecules and Cl- anions are linked alternatively by hydrogen bonds of lengths 3.202(3) and 3.282(2) angstrom into planar zigzag chains along the [c] direction. The Cl- anion additionally interacts electrostatically with two positively charged nitrogen atoms of the neighboring MIN molecules. The most stable conformers of (MIN)(2)H . Cl . H2O, (MIN)(2)H . Cl, (MIN)(2)H . H2O and (MIN)(2)H have been analyzed by the B3LYP/6-31G(d,p) calculations in order to determine the influence of the anion and water molecule on the hydrogen bond in the homoconjugated MIN . H . MIN unit. The FTIR spectrum of (MIN)(2)H . Cl . H2O shows a broad and intense absorption in the 1500-400 cm(-1) region, typical for short hydrogen bonds. The bands at 3416 and 3378 cm(-1) confirm the presence of medium-strong hydrogen bonds between water molecules and Cl- anions. (c) 2006 Elsevier B.V. All rights reserved.