Hauchecorne Dieter, Szostak Roman, Herrebout Wouter A, van der Veken Benjamin J
Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
Chemphyschem. 2009 Aug 24;10(12):2105-15. doi: 10.1002/cphc.200900125.
The formation of weakly bound molecular complexes between dimethyl ether (DME) and the trifluoromethyl halides CF(3)Cl, CF(3)Br and CF(3)I dissolved in liquid argon and in liquid krypton is investigated, using Raman and FTIR spectroscopy. For all halides evidence is found for the formation of C-X...O halogen-bonded 1:1 complexes. At higher concentrations of CF(3)Br, a weak absorption due to a 1:2 complex is also observed. Using spectra recorded at temperatures between 87 and 125 K, the complexation enthalpies for the complexes are determined to be -6.8(3) kJ mol(-1) (DME x CF(3)Cl), -10.2(1) kJ mol(-1) (DME x CF(3)Br), -15.5(1) kJ mol(-1) (DME x CF(3)I), and -17.8(5) kJ mol(-1) [DME(x CF(3)Br)(2)]. Structural and spectral information on the complexes is obtained from ab initio calculations at the MP2/6-311++G(d,p) and MP2/6-311++G(d,p)+LanL2DZ* levels. By applying Monte Carlo free energy perturbation calculations to account for the solvent influences, and statistical thermodynamics to estimate the zero-point vibrational and thermal influences, the ab initio complexation energies are converted into complexation enthalpies for the solutions in liquid argon. The resulting values are compared with the experimental data deduced from the cryosolutions.
利用拉曼光谱和傅里叶变换红外光谱，研究了溶解于液氩和液氪中的二甲醚（DME）与三氟甲基卤化物CF(3)Cl、CF(3)Br和CF(3)I之间弱键合分子复合物的形成。对于所有卤化物，均发现形成了C-X...O卤键合的1:1复合物。在CF(3)Br浓度较高时，还观察到了由于1:2复合物产生的弱吸收。利用在87至125 K温度下记录的光谱，确定复合物的络合焓为-6.8(3) kJ mol(-1) （DME x CF(3)Cl）、-10.2(1) kJ mol(-1) （DME x CF(3)Br）、-15.5(1) kJ mol(-1) （DME x CF(3)I）和-17.8(5) kJ mol(-1) [DME(x CF(3)Br)(2)]。通过在MP2/6-311++G(d,p)和MP2/6-311++G(d,p)+LanL2DZ*水平上进行从头算计算，获得了复合物的结构和光谱信息。通过应用蒙特卡罗自由能微扰计算来考虑溶剂影响，并利用统计热力学来估计零点振动和热影响，将从头算络合能转换为液氩溶液中的络合焓。将所得值与从低温溶液推导的实验数据进行比较。
