Original scientific paper

https://doi.org/10.5562/cca2224

Effect of Hydrogen Bonding on the Pyramidalization of the Amino Group: Structure of 3,4-diaminobenzamidinium Chloride

Ivana Stolić ; Department of Chemistry and Biochemistry, Faculty of Veterinary Medicine, University of Zagreb, Heinzelova 55, HR-10000 Zagreb, Croatia
Miroslav Bajić ; Department of Chemistry and Biochemistry, Faculty of Veterinary Medicine, University of Zagreb, Heinzelova 55, HR-10000 Zagreb, Croatia
Dubravka Matković-Čalogović orcid.org/0000-0003-4909-8312 ; Division of General and Inorganic Chemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia

Abstract

3,4-diaminobenzamidinium was synthesized and spectroscopically and structurally characterized,
both at room temperature and at 150 K. The crystal structure consists of two 3,4-
diaminobenzamidinium cations and two chloride anions. The planar amidinium group is inclined by
35.35(5)° and 28.96(7)° in respect to the diaminobenzene moiety in the two crystallographically independent
cations. The ions are interconnected by a large network of hydrogen bonds into a threedimensional
structure. Pyramidalization of the amino group in relation to the hydrogen bond length in
which the amino group is an acceptor is analized. Two amino groups are acceptors of N–H···N hydrogen
bonds of 2.9565(14) Å and 2.9654(15) Å resulting in pyramidalization of 340(1)° and 337(1)°, respectively
(the sum of the amino group bond angles is given as a measure of pyramidalization). A very weak
hydrogen bond to one amino group results in a very flat pyramid (351(1)°), while one amino group is not
acceptor of a hydrogen bonds and it is planar. The resonance effect has influence on the planar amino
groups resulting in a shorter C–N(amino group) bond length than in the pyramidalized ones. (doi:
10.5562/cca2224)

Keywords

pyramidalization of the amino group; 3,4-diaminobenzamidinium chloride; X-ray single crystal structure analysis

Hrčak ID:

105585

URI

https://hrcak.srce.hr/105585

Publication date:

1.7.2013.

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