Conformation preference and related intramolecular noncovalent interaction of selected short chain chlorinated paraffins

Abstract

Short chain chlorinated paraffins (SCCPs) are not only research focus of environmental issues but also interesting model molecules for organic chemistry which exhibit diverse conformation preference and intramolecular noncovalent interactions (NCIs). A systematic study was conducted to reveal the conformation preference and the related intramolecular NCIs in two C 10 -isomers of SCCPs, 5,5,6,6-tetrachlorodecane and 4,4,6,6-tetrachlorodecane. The overall conformation profile was determined on the basis of relative energies calculated at the MP2/6-311++G(d,p) level with the geometries optimized by B3LYP/6-311++G(d,p) method. Then, quantum theory of atoms in molecules (QTAIM) has been adopted to identify the NCIs in the selected conformers of the model molecules at both B3LYP/6-311++G(d,p) and M06-2X/aug-cc-pvdz level. Different chlorine substitution modes result in varied conformation preference. No obvious gauche effect can be observed for the SCCPs with chlorination on adjacent carbon atoms. The most stable conformer of 5,5,6,6-tetrachlorodecane (tTt) has its three dihedral angles in the T configuration, and there is no intramolecular NCIs found in this molecule. On the contrary, the chlorination on interval carbon atoms favors the adoption of gauche configuration for the H-C-C-Cl axis. Not only intramolecular H···Cl contacts but also H···H interactions have been identified as driving forces to compensate the instability from steric crowding of the gauche configuration. The gggg and g′g′g′g′ conformers are the most popular ones, while the populations of tggg and tg′g′g′ conformer are second to those of the gggg and g′g′g′g′ conformers. Meanwhile, the M06-2X method with large basis sets is preferred for identification of subtle intramolecular NCIs in large molecules like SCCPs.short chain chlorinated paraffins, intramolecular noncovalent interactions, conformation preference, chlorination substitution mode Citation:Sun YZ, Pan WX, Fu JJ, Zhang AQ, Zhang QH. Conformation preference and related intramolecular noncovalent interaction of selected short chain chlorinated paraffins.

Desarrollo de potenciales de interacción de solventes orgánicos basados en la constante dieléctrica

“…En el presente trabajo, los cálculos de estructura electrónica se realizaron con este funcional ya que los mismos autores recomiendan su uso para sistemas en los cuáles existan deslocalizaciones electrónicas (como es el caso de los sistemas aromáticos o grupos carbonilo), en la obtención de propiedades termoquímicas y cinéticas, pero sobre todo en aquellos sistemas en los que las interacciones no covalentes son importantes [97,98,99]. Debido a esto, este funcional ha sido utilizado en el estudio de biomoléculas [100,101], ciclos termodinámicos [102], interacciones por puente de hidrógeno intra e intermoleculares [103,104,101], así como para en el estudio de la transferibilidad de diferentes campos de fuerza en la construcción de aminoácidos [105].…”