Conformational polymorphs of 22-cyano-N-methyl-5-phenylpent-2-en-4-ynamide.
Although the two polymorphic modifications, (I) and (II), of the title compound, C(13)H(10)N(2)O, crystallize in the same space group (P2(1)/c), their asymmetric units have Z' values of 1 and 2, respectively. These are conformational polymorphs, since the molecules in phases (I) and (II) adopt different rotations of the phenyl ring with respect the central 2-cyanocarboxyaminoprop-2-enyl fragment. Calculations of crystal packing using Cerius(2) [Molecular Simulations (1999). 9685 Scranton Road, San Diego, CA 92121, USA] have shown that (I) is more stable than (II), by 1.3 kcal mol(-1) for the crystallographically determined structures and by 1.56 kcal mol(-1) for the optimized structures (1 kcal mol(-1) = 4.184 kJ mol(-1)). This difference is mainly attributed to the different strengths of the hydrogen bonding in the two forms.
Borbulevych
O Y
OY
Department of Chemistry, New Mexico Highlands University, Las Vegas, NM 87701, USA. oleg@xrlab.ineos.ac.ru
Golding
I R
IR
Shchegolikhin
A N
AN
Klemenkova
Z S
ZS
Antipin
M Y
MY
D000480:Alkynes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D009570:Nitriles / Q000737:chemistry*
C435296:22-cyano-N-methyl-5-phenylpent-2-en-4-ynamide; D000480:Alkynes; D009570:Nitriles