ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Interactions in Crystals: The Dimorphism of (2-Pyridyl)(2-pyrimidyl)aminePreceding structural studies of 2-aminopyridine derivatives prove that they form polymorphic H-pair-bonded dimmers, and, therefore, (2-pyrimidyl)amine has been crystallized under different conditions. Two different monoclinic modifications are characterized by their crystal structures of the same space group P21/c: form I exhibits the well known herringbone motif and form II the sandwich-herringbone one. Both modifications contain almost identical planar, H-pair-bridged molecular dimmers. Crystals of form I are readily obtained from any solvent, whereas those of form II result either on fast evaporation of a Et2O solution or by resolidification of the melt. Differential thermal analysis (DTA) and crystallization experiments at different temperatures prove, for both modifications, no transitions in the temperature range between -25° and the melting point at 152° and, therefore the system should be monotropic. The structural and thermodynamic aspects of the (2-pyridyl)(2-pyrimidyl)amine dimorphism are discussed in comparison to those of the trimorphism observed for di(2-pyridyl)amine.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19970800222
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