Multiple N-H center dot center dot center dot NC, C-H center dot center dot center dot NC and nitrile center dot center dot center dot pi interactions in 4,4 '-bipyridine-1,1 '-diium bis(1,1,3,3-tetracyano-2-ethoxypropenide): structure determination and DFT calculations of anion center dot center dot center dot pi cation interaction energies

作者：Setifi Fatima; Geiger David K^*; Razak Ibrahim Abdul; Setifi Zouaoui

来源：Acta Crystallographica Section C-Structural Chemistry, 2015, 71(8): 658-+.

DOI：10.1107/S2053229615012437

• nitrile center dot center dot center dot pi interaction
• nitrile hydrogen bonding
• anion center dot center dot center dot pi interaction
• interaction energies
• crystal structure
• DFT calculations
• polynitrile anions
• charge delocalization
• 1,1,3,3-tetracyano-2-ethoxypropenide
• 4,4 '-bipyridine-1,1 '-diium

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 (bpyH(2)(2+)) cations and two symmetry-independent 1,1,3,3-tetracyano-2-ethoxypropenide (tcnoet(-)) anions in the asymmetric unit. One of the bpyH(2)(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 center dot center dot center dot NC hydrogen-bonding motifs, which result in a sheet structure parallel to (010), and weak C-H center dot center dot center dot NC hydrogen bonds form joined rings. Two types of multicenter CN center dot center dot center dot pi interactions are observed between the bpyH(2)(2+) rings and tcnoet(-) anions. An additonal CN center dot center dot center dot pi interaction between adjacent tcnoet(-) anions is observed. Using density functional theory, the calculated attractive energy between cation and anion pairs in the tcnoet(-)center dot center dot center dot pi (bipyridinediium) interactions were found to be 557 and 612 kJ mol(-1) for coplanar and canted bpyH(2)(2+) cations, respectively.

• 出版日期2015-8