A variable-temperature X-ray diffraction and theoretical study of conformational polymorphism in a complex organic molecule (DTC).

Two conformational crystal polymorphs of 3-diethylamino-4-(4-methoxyphenyl)-1,1-dioxo-4-1λ,2-thiazete-4-carbonitrile (DTC) have been analyzed in the 100 K-room temperature range by single crystal X-ray diffraction and high quality DFT calculations. DTC has strongly polar as well as aliphatic substituents but no hydrogen bonding groups, and thus qualifies as a test molecule for the relative importance of electrostatic dispersion-repulsion terms. The two polymorphs have the same 2/ space group and differ by a flipping of the -OCH group, the two conformations being almost equi-energetic and separated by a low barrier.

Insights on spin polarization through the spin density source function.

Understanding how spin information is transmitted from paramagnetic to non-magnetic centers is crucial in advanced materials research and calls for novel interpretive tools. Herein, we show that the spin density at a point may be seen as determined by a local source function for such density, operating at all other points of space. Integration of the local source over Bader's quantum atoms measures their contribution in determining the spin polarization at any system's location.

A new monoclinic polymorph of 3-diethyl-amino-4-(4-meth-oxy-phen-yl)-1,1-dioxo-4H-1λ,2-thia-zete-4-carbonitrile.

A new monoclinic form of the title compound, C(14)H(17)N(3)O(3)S, has been found upon slow crystallization from water. Another monoclinic form of the compound was obtained previously from a mixture of dichloro-methane and diethyl ether [Clerici et al. (2002 ▶).