title: X-ray crystal structure, vibrational spectra and DFT calculations of 3-chloro-7-azaindole: a case of dual N-H⋯N hydrogen bonds in dimers.
abstract: 3-Chloro-7-azaindole (3Cl7AI) is the carrier ligand in a new anticancer platinum(II) agent cis-[PtCl2(3Cl7AI)2]. In this work 3Cl7AI has been studied by a single crystal X-ray diffraction, infrared and Raman spectroscopy and density functional calculations. The compound crystallizes in the monoclinic system, space group P21/n, with a=12.3438(3), b=3.85964(11), c=14.4698(4)Å, β=100.739(2)°, V=677.31(3)Å(3) and Z=4. In the crystal, a pair of 3Cl7AI molecules forms a centrosymmetric dimer linked by the moderately strong dual N-H⋯N hydrogen bonds. The nitrogen atom in the pyrrole ring acts as the proton donor, while the nitrogen atom in the pyridine ring is the proton acceptor. The FT-IR and FT-Raman spectra (3500-60 cm(-1)) have been recorded. The theoretical studies on the molecular structures and vibrational spectra of the monomeric and dimeric forms of 3Cl7AI and its N-deuterated derivative were performed using the B3LYP method with 6-311++G(d,p) basis set. The theoretically predicted Raman spectrum for the dimer shows very good agreement with experiment. Detailed vibrational assignments for the two isotopomers have been made on the basis of the calculated potential energy distributions (PEDs). The dual N-H⋯N hydrogen bonds in 3Cl7AI dimer are characterized by a very broad and complicated structure of the absorption band between 3300 and 2500 cm(-1), which is caused by multiple Fermi resonances between the N-H stretching vibration and various combinations bands.
authors.affiliation: Institute of Chemistry, Environmental Protection and Biotechnology, Jan Długosz University, Armii Krajowej 13/15 Ave., 42-200 Częstochowa, Poland. Electronic address: bmorzyk-ociepa@o2.pl.
authors.forename: Barbara
authors.initials: B
authors.lastname: Morzyk-Ociepa
authors.affiliation: Institute of Chemistry, Environmental Protection and Biotechnology, Jan Długosz University, Armii Krajowej 13/15 Ave., 42-200 Częstochowa, Poland.
authors.forename: Karolina
authors.initials: K
authors.lastname: Dysz
authors.affiliation: Faculty of Chemistry, Wrocław University of Technology, Smoluchowskiego 23, 50-370 Wrocław, Poland.
authors.forename: Ilona
authors.initials: I
authors.lastname: Turowska-Tyrk
authors.affiliation: Faculty of Chemistry, Wrocław University of Technology, Smoluchowskiego 23, 50-370 Wrocław, Poland.
authors.forename: Danuta
authors.initials: D
authors.lastname: Michalska
mesh_terms: D018360:Crystallography, X-Ray; D019281:Dimerization; D006860:Hydrogen Bonding; D007211:Indoles / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D011789:Quantum Theory; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D014732:Vibration
chemical_list: D007211:Indoles
keywords: 3-Chloro-7-azaindole; Crystal and molecular structure; Density functional theory; Dual hydrogen bonds; Infrared and Raman spectra