title: Non-covalent C-Cl…π interaction in acetylene-carbon tetrachloride adducts: Matrix isolation infrared and ab initio computational studies.
abstract: Non-covalent halogen-bonding interactions between π cloud of acetylene (C2H2) and chlorine atom of carbon tetrachloride (CCl4) have been investigated using matrix isolation infrared spectroscopy and quantum chemical computations. The structure and the energies of the 1:1 C2H2-CCl4 adducts were computed at the B3LYP, MP2 and M05-2X levels of theory using 6-311++G(d,p) basis set. The computations indicated two minima for the 1:1 C2H2-CCl4 adducts; with the C-Cl…π adduct being the global minimum, where π cloud of C2H2 is the electron donor. The second minimum corresponded to a C-H…Cl adduct, in which C2H2 is the proton donor. The interaction energies for the adducts A and B were found to be nearly identical. Experimentally, both C-Cl…π and C-H…Cl adducts were generated in Ar and N2 matrixes and characterized using infrared spectroscopy. This is the first report on halogen bonded adduct, stabilized through C-Cl…π interaction being identified at low temperatures using matrix isolation infrared spectroscopy. Atoms in Molecules (AIM) and Natural Bond Orbital (NBO) analyses were performed to support the experimental results. The structures of 2:1 ((C2H2)2-CCl4) and 1:2 (C2H2-(CCl4)2) multimers and their identification in the low temperature matrixes were also discussed.
authors.affiliation: Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India.
authors.forename: N
authors.initials: N
authors.lastname: Ramanathan
authors.affiliation: Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India. Electronic address: sundar@igcar.gov.in.
authors.forename: K
authors.initials: K
authors.lastname: Sundararajan
authors.affiliation: School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695016, India.
authors.forename: K
authors.initials: K
authors.lastname: Vidya
authors.affiliation: Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India. Electronic address: jemmis@ipc.iisc.ernet.in.
authors.forename: Eluvathingal D
authors.initials: ED
authors.lastname: Jemmis
keywords: AIM and NBO analyses; Halogen bonding; Non-covalent interaction; infrared; matrix isolation