Joshi Ravi, Ghanty Tapan K, Naumov Sergej, Mukherjee Tulsi
Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
J Phys Chem A. 2007 Dec 27;111(51):13590-4. doi: 10.1021/jp074194h. Epub 2007 Dec 4.
Ab initio molecular orbital calculations have been employed to characterize the structure and bonding of the (HO2-H2O)+ radical cation system. Geometry optimization of this system was carried out using unrestricted density functional theory in conjunction with the BHHLYP functional and 6-311++G(2df,2p) as well as 6-311++G(3df,3p) basis sets, the second-order Møller-Plesset perturbation (MP2) method with the 6-311++G(3df,3p) basis set, and the couple cluster (CCSD) method with the aug-cc-pVTZ basis set. The effect of spin multiplicity on the stability of the (HO2-H2O)+ system has been studied and also compared with that of oxygen. The calculated results suggest a proton-transferred hydrogen bond between HO2 and H2O in H3O3+ wherein a proton is partially transferred to H2O producing the O2...H3O+ structure. The basis set superposition error and zero-point energy corrected results indicate that the H3O3+ system is energetically more stable in the triplet state; however, the singlet state of H3O3+ is more stable with respect to its dissociation into H3O+ and singlet O2. Since the resulting proton-transferred hydrogen-bonded complex (O2...H3O+) consists of weakly bound molecular oxygen, it might have important implications in various chemical processes and aquatic life systems.
从头算分子轨道计算已被用于表征(HO2-H2O)+自由基阳离子体系的结构和键合。该体系的几何优化是使用无限制密度泛函理论结合BHHLYP泛函以及6-311++G(2df,2p)和6-311++G(3df,3p)基组、采用6-311++G(3df,3p)基组的二阶Møller-Plesset微扰(MP2)方法以及采用aug-cc-pVTZ基组的耦合簇(CCSD)方法进行的。研究了自旋多重性对(HO2-H2O)+体系稳定性的影响，并与氧的影响进行了比较。计算结果表明，在H3O3+中，HO2与H2O之间存在质子转移氢键，其中一个质子部分转移到H2O上，形成O2...H3O+结构。基组叠加误差和零点能校正结果表明，H3O3+体系在三重态下能量更稳定；然而，H3O3+的单重态相对于其分解为H3O+和单重态O2更稳定。由于形成的质子转移氢键复合物(O2...H3O+)由弱结合的分子氧组成，它可能在各种化学过程和水生生物系统中具有重要意义。
