【摘要】 利用量子化学从头算方法,采用RHF/6-31G*和RHF/6-311G*方法,分别研究了六水氯化镁的分子结构与电子结构。计算结果表明,不同的计算方法,所得的结论基本一致,在六水氯化镁模型分子中,两个水分子与氯化镁结合松弛,以RHF/6-311G*计算为例,R[O-Mg]键长分别为0.3972nm和0.3839nm,这两个水分子游离在氯化镁的最外层,结合呈松散状态,极易脱除;另两个水分子与氯化镁结合适中,R[O-Mg]键长分别为0.2142nm和0.2152nm,最后两个水分子与氯化镁结合较牢,R[O-Mg]键长均为0.2081nm,这两个水分子最难脱除。本研究从理论化学的角度合理地解释了六水氯化镁脱水过程的实质,并由此深化对六水氯化镁的内部结构的认识,这种量子化学的计算方法是对现有的六水氯化镁实验研究方法的有益补充。更多还原

【Abstract】 Ab initio method was used to study the molecular and electronic structure of MgCl2·6H2O at RHF/6-31G*and RHF/6-311G* basis set. Results show that different computational methods obtain the same conclusion. In model MgCl2 · 6H2O, two H2O molecules combine loose with central MgCl2, (set method RHF/6-311G* as an example) , the bond lengths of R [ O- Mg] are 0. 397 2 nm, 0. 383 9 nm, respectively. The two H2O molecules exist at the outer sphere of MgCl2, thus can be easily removed. The other two H2O molecules combine moderately with central MgCl2 , the bond lengths of R[ O-Mg] are 0. 214 2 nm, 0. 215 2 nm, respectively. The last two H2O molecules combine tightly with central MgCl2, the bond lengths of R [O-Mg] are both 0. 208 1 nm, which means it is hard to be removed. From theoretical chemistry point of view, this study properly explains the mechanism of the dehydration process of MgCl2 · 6H2O, and thus is significant for further knowledge of inside structure of MgCl2·6H2O. The quantum chemistry method is a useful supplement for experimental study of MgCl2· 6H2O.更多还原