Abstract
As part of an investigation of the solid-state intermolecular contacts in which the nitrile group participates, the crystal structures of
p
-cyano-
N
-(
p
-cyanobenzylideneaniline), C
15
H
9
N
3
(CN/CN) and 4,4′-(azinodimethylidyne)
bis
-benzonitrile, C
16
H
10
N
4
(CN//CN) have been determined at −100 °C. Cell parameters for CN/CN: a = 4.7270(9) Å, b = 10.443(2) Å, c = 11.943(2) Å; α = 90°, β = 98.70(3)°, γ = 90°; monoclinic, space group
P
2
1
/c. Cell parameters for CN//CN: a = 3.8008(8) Å, b = 7.9627(16) Å, c = 11.181(2) Å; α = 70.23(3)°, β = 84.66(3)°, γ = 81.93(3)°; triclinic, space group
. Both molecules occupy crystallographic inversion centers, which requires that (CN/CN) be disordered. Both molecules assume nearly planar conformations in the solid state. Neither (CN/CN) nor (CN//CN) is isostructural with its halogen-nitrile substituted analogues, although (CN/CN) is found to be isostructural with the corresponding stilbene. Both (CN/CN) and (CN//CN) engage in centrosymmetric H-bonding interactions that define an
R
2
2
(10) motif. This motif is also observed in many related structures, although noteworthy exceptions can be found.
Graphical Abstract
In the crystal structures of
p
-cyano-
N
-(
p
-cyanobenzylideneaniline), C
15
H
9
N
3
(CN/CN) (a disordered structure) and 4,4′-(azinodimethylidyne)
bis
-benzonitrile, C
16
H
10
N
4
(CN//CN), nitrile groups are found to engage in centrosymmetric H-bonding interactions with aromatic ring hydrogen atoms, defining an
R
2
2
(10) motif in each case.