Furuya Ari, Tsuruta Mamoru, Misaizu Fuminori, Ohno Koichi, Inokuchi Yoshiya, Judai Ken, Nishi Nobuyuki
Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
J Phys Chem A. 2007 Jul 12;111(27):5995-6002. doi: 10.1021/jp067622c. Epub 2007 Jun 15.
Infrared photodissociation spectra of Al(+)(CH(3)OH)(n) (n = 1-4) and Al(+)(CH(3)OH)(n)-Ar (n = 1-3) were measured in the OH stretching region, 3000-3800 cm(-1). For n = 1 and 2, sharp absorption bands were observed in the free OH stretching region, all of which were well reproduced by the spectra calculated for the solvated-type geometry with no hydrogen bond. For n = 3 and 4, there were broad vibrational bands in the energy region of hydrogen-bonded OH stretching vibrations, 3000-3500 cm(-1). Energies of possible isomers for the Al(+)(CH(3)OH)(3),4 ions with hydrogen bonds were calculated in order to assign these bands. It was found that the third and fourth methanol molecules form hydrogen bonds with methanol molecules in the first solvation shell, rather than a direct bonding with the Al(+) ion. For the Al(+)(CH(3)OH)(n) clusters with n = 1-4, we obtained no evidence of the insertion reaction, which occurs in Al(+)(H(2)O)(n). One possible explanation of the difference between these two systems is that the potential energy barriers between the solvated and inserted isomers in the Al(+)(CH(3)OH)(n) system is too high to form the inserted-type isomers.
在3000 - 3800厘米⁻¹的OH伸缩振动区域测量了Al⁺(CH₃OH)ₙ（n = 1 - 4）和Al⁺(CH₃OH)ₙ - Ar（n = 1 - 3）的红外光解离光谱。对于n = 1和2，在自由OH伸缩振动区域观察到尖锐的吸收带，所有这些吸收带都能很好地由无氢键的溶剂化型几何结构计算出的光谱再现。对于n = 3和4，在氢键OH伸缩振动的能量区域3000 - 3500厘米⁻¹有宽的振动带。为了归属这些谱带，计算了具有氢键的Al⁺(CH₃OH)₃,₄离子可能异构体的能量。发现第三个和第四个甲醇分子与第一溶剂化层中的甲醇分子形成氢键，而不是与Al⁺离子直接键合。对于n = 1 - 4的Al⁺(CH₃OH)ₙ团簇，我们没有获得在Al⁺(H₂O)ₙ中发生的插入反应的证据。这两个体系之间差异的一个可能解释是，Al⁺(CH₃OH)ₙ体系中溶剂化异构体和插入异构体之间的势能垒太高，无法形成插入型异构体。
