Arce Valeria B, Della Védova Carlos O, Downs Anthony J, Parsons Simon, Romano Rosana M
CEQUINOR (CONICET), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 esq. 115, (1900) La Plata, República Argentina.
J Org Chem. 2006 Apr 28;71(9):3423-8. doi: 10.1021/jo052260a.
The conformational properties of gaseous trichloromethyl chloroformate (or "diphosgene"), ClC(O)OCCl3, have been studied by vibrational spectroscopy [IR (gas), IR (matrix), and Raman (liquid)] and quantum chemical calculations (MP2 and B3LYP with 6-311G basis sets); in addition, the structure of a single crystal at low temperature has been determined by X-ray diffraction. ClC(O)OCCl3 exhibits only one conformational form having Cs symmetry with a synperiplanar orientation of the C-O single bond relative to the C=O double bond. The calculated energy difference between the syn and anti forms, 5.73 kcal mol(-1) (B3LYP) or 7.06 kcal mol(-1) (MP2), is consistent with the experimental findings for the gas and liquid phases. The crystalline solid at 150 K [monoclinic, P2(1)/n, a = 5.5578(5) angstroms, b = 14.2895(12) angstroms, c = 8.6246(7) angstroms, beta = 102.443(2) degrees, Z = 4] likewise consists only of molecules in the syn form.
通过振动光谱法[红外光谱（气体）、红外光谱（基质）和拉曼光谱（液体）]以及量子化学计算（采用6-311G基组的MP2和B3LYP方法）研究了气态氯甲酸三氯甲酯（或“双光气”，ClC(O)OCCl3）的构象性质；此外，通过X射线衍射确定了低温下单晶的结构。ClC(O)OCCl3仅呈现一种具有Cs对称性的构象形式，其中C-O单键相对于C=O双键呈顺式共平面取向。顺式和反式构象之间的计算能量差为5.73 kcal mol-1（B3LYP方法）或7.06 kcal mol-1（MP2方法），这与气相和液相的实验结果一致。150 K时的晶体固体[单斜晶系，P2(1)/n，a = 5.5578(5)埃，b = 14.2895(12)埃，c = 8.6246(7)埃，β = 102.443(2)°，Z = 4]同样仅由顺式构象的分子组成。
