title: Multiple N-H···NC, C-H···NC and nitrile···π interactions in 4,4'-bipyridine-1,1'-diium bis(1,1,3,3-tetracyano-2-ethoxypropenide): structure determination and DFT calculations of anion···π cation interaction energies.
abstract: Polynitrile anions are important in both coordination chemistry and molecular materials chemistry, and are interesting for their extensive electronic delocalization. The title compound crystallizes with two symmetry-independent half 4,4'-bipyridine-1,1'-diium (bpyH2(2+)) cations and two symmetry-independent 1,1,3,3-tetracyano-2-ethoxypropenide (tcnoet(-)) anions in the asymmetric unit. One of the bpyH2(2+) ions is located on a crystallographic twofold rotation axis (canted pyridine rings) and the other is located on a crystallographic inversion center (coplanar pyridine rings). The ethyl group of one of the tcnoet(-) anions is disordered over two sites with equal populations. The extended structure exhibits two separate N-H···NC hydrogen-bonding motifs, which result in a sheet structure parallel to (010), and weak C-H···NC hydrogen bonds form joined rings. Two types of multicenter CN···π interactions are observed between the bpyH2(2+) rings and tcnoet(-) anions. An additonal CN···π interaction between adjacent tcnoet(-) anions is observed. Using density functional theory, the calculated attractive energy between cation and anion pairs in the tcnoet(-)···π(bipyridinediium) interactions were found to be 557 and 612 kJ mol(-1) for coplanar and canted bpyH2(2+) cations, respectively.
authors.affiliation: Laboratoire de Chimie, Ingénierie Moléculaire et Nanostructures (LCIMN), Université Ferhat Abbas Sétif 1, Sétif 19000, Algeria.
authors.forename: Fatima
authors.initials: F
authors.lastname: Setifi
authors.affiliation: Department of Chemistry, SUNY-College at Geneseo, Geneseo, NY 14454, USA.
authors.forename: David K
authors.initials: DK
authors.lastname: Geiger
authors.affiliation: X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia.
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Abdul Razak
authors.affiliation: Laboratoire de Chimie, Ingénierie Moléculaire et Nanostructures (LCIMN), Université Ferhat Abbas Sétif 1, Sétif 19000, Algeria.
authors.forename: Zouaoui
authors.initials: Z
authors.lastname: Setifi
keywords: 1,1,3,3-tetracyano-2-ethoxypropenide; 4,4′-bipyridine-1,1′-diium; DFT calculations; anion...π interaction; charge delocalization; crystal structure; interaction energies; nitrile hydrogen bonding; nitrile...π interaction; polynitrile anions