Pasinszki Tibor
Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, H-1521 Budapest, 4 Gellért tér, Hungary.
Phys Chem Chem Phys. 2008 Mar 14;10(10):1411-8. doi: 10.1039/b713832f. Epub 2008 Jan 21.
The equilibrium geometries, stability, and isomerisation of pseudohalogen isomers, C(2)N(2)O(2), have been investigated by DFT calculations at the B3LYP level and by ab initio calculations at the CCSD(T) level of theory using the 6-311+G(2d) and cc-pVTZ basis sets, as well as at the CBS-QB3 level. Minimum energy structures and their interconnecting transition states, as well as transition states for bond dissociations have been calculated, and possible isomerisation and decomposition pathways are suggested. Calculations have predicted that four isomers, OCNNCO, ONCCNO, ONCOCN, and ONCNCO are kinetically stable toward unimolecular isomerisation or dissociation at room temperature with the lowest kinetic energy barrier of 209, 232, 159, and 95 kJ mol(-1), respectively (CCSD(T)//B3LYP), and other isomers, like NCONCO, CNONCO, and CNOCNO are unstable. Calculations have also predicted that valence formulations like NCOOCN, CNOOCN, and CNOONC do not represent existing molecules. The gas-phase generation of OCNNCO has been attempted by thermolysing Me(3)SiON(Me(3)SiO)CC(OSiMe(3))NOSiMe(3), synthesised by a novel method from oxalyl chloride and N,O-bis(trimethylsilyl)hydroxylamine; the thermolysis, however, have not produced OCNNCO, but trimethylsilylisocyanate and hexamethyldisiloxane.
通过在B3LYP水平上的密度泛函理论（DFT）计算以及在CCSD(T)理论水平上使用6-311+G(2d)和cc-pVTZ基组并结合CBS-QB3水平的从头算，对拟卤素异构体C₂N₂O₂的平衡几何结构、稳定性和异构化进行了研究。计算了最低能量结构及其相互连接的过渡态以及键解离的过渡态，并提出了可能的异构化和分解途径。计算预测，四种异构体OCNNCO、ONCCNO、ONCOCN和ONCNCO在室温下对单分子异构化或解离具有动力学稳定性，其最低动力学能垒分别为209、232、159和95 kJ mol⁻¹（CCSD(T)//B3LYP），而其他异构体，如NCONCO、CNONCO和CNOCNO则不稳定。计算还预测，像NCOOCN、CNOOCN和CNOONC这样的价键结构并不代表现有的分子。通过热解由草酰氯和N,O-双（三甲基硅基）羟胺通过一种新方法合成的Me₃SiON(Me₃SiO)CC(OSiMe₃)NOSiMe₃来尝试气相生成OCNNCO；然而，热解并未产生OCNNCO，而是生成了三甲基硅基异氰酸酯和六甲基二硅氧烷。
