Determination of Intermolecular Potentials from Crystal Data. II. Crystal Packing with Applications to Poly(amino acids)

1971 ◽  
Vol 4 (1) ◽  
pp. 112-124 ◽  
Author(s):  
R. F. McGuire ◽  
G. Vanderkooi ◽  
F. A. Momany ◽  
R. T. Ingwall ◽  
G. M. Crippen ◽  
...  
Keyword(s):  
Amino Acids ◽  
Crystal Packing ◽  
Crystal Data ◽  
Intermolecular Potentials

Low-temperature crystallization and structure determination of N-(trifluoromethyl)formamide, N-(2,2,2-trifluoroethyl)formamide and 2,2,2-trifluoroethyl isocyanide

1999 ◽  
Vol 55 (1) ◽  
pp. 70-77 ◽  
Author(s):  
G. J. Perpétuo ◽  
J. Buschmann ◽  
P. Luger ◽  
D. Lentz ◽  
D. Dreissig
Keyword(s):  
Crystal Structure ◽  
Low Temperatures ◽  
Crystal Packing ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Low Temperature Crystallization ◽  
Temperature Crystallization

Crystals of N-(trifluoromethyl)formamide, C2H2F3NO, (I), N-(2,2,2-trifluoroethyl)formamide, C3H4F3NO, (II), and 2,2,2-trifluoroethyl isocyanide, C3H2F3N, (III), were grown in situ on an X-ray diffractometer and analysed by single-crystal X-ray diffraction methods at low temperatures. Crystal data: (I) orthorhombic, P212121, a = 4.547 (2) Å, b = 5.947 (3) Å, c = 14.731 (9) Å, V = 398.3 (4) Å3, Z = 4, M r = 113.05, T = 143 K, D x = 1.885 Mg m−3; (II) monoclinic, P21/n, a = 4.807 (1) Å, b = 16.707 (3) Å, c = 6.708 (1) Å, β = 109.90 (1)°, V = 506.6 (2) Å3, Z = 4, M r = 127.07, T = 141 K, D x = 1.666 Mg m−3; (III) orthorhombic, P212121, a = 5.668 (2) Å, b = 9.266 (3) Å, c = 8.626 (2) Å, V = 453.0 (2) Å3, Z = 4, M r = 109.06, T = 163 K, D x = 1.599 Mg m−3. The results showed that in the crystal both formamides (I) and (II) are exclusively present in the form of the Z isomer, although measurements of solutions of (I) have shown that the E isomer prevails [Lentz et al. (1987). Angew. Chem. 99, 951–953]. In addition ab initio calculations for (I) predicted the E isomer to be the more stable one. In compound (III) the isocyanide group is staggered with respect to the trifluoroethyl group. In the crystal packing of (I) and (II) intermolecular N—H\cdotsO hydrogen bonds generate infinite chains. In (I), these chains are linked to form sheets by C—H\cdotsO contacts. In the crystal structure of (III) each isocyanide dipole is surrounded by four electronegative F atoms with intermolecular C\cdotsF contacts between 3.4 and 3.5 Å.

Intermolecular Potentials from Crystal Data. V. Crystal Packing of Poly[β-(p-chlorobenzyl)-L-aspartate

1974 ◽  
Vol 7 (4) ◽  
pp. 468-480 ◽  
Author(s):  
Yi-Chang Fu ◽  
Robert F. McGuire ◽  
Harold A. Scheraga
Keyword(s):  
Crystal Packing ◽  
Crystal Data ◽  
Intermolecular Potentials
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