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Secondary interactions in N-(chloromethyl)pyridinium chlorides (n = 2, 3, 4)
Peter G Jones1, Fabiola Vancea, Regine Herbst-Irmer
1Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Postfach 3329, 38023 Braunschweig, Germany. jones@xray36.anchem.nat.tu-bs.de
Abstract:
In the isomeric title compounds, viz. 2-, 3- and 4-(chloromethyl)pyridinium chloride, C(6)H(7)ClN(+).Cl(-), the secondary interactions have been established as follows. Classical N-H.Cl(-) hydrogen bonds are observed in the 2- and 3-isomers, whereas the 4-isomer forms inversion-symmetric N-H(.Cl(-).)(2)H-N dimers involving three-centre hydrogen bonds. Short Cl.Cl contacts are formed in both the 2-isomer (C-Cl.Cl(-), approximately linear at the central Cl) and the 4-isomer (C-Cl.Cl-C, angles at Cl of ca 75 degrees ). Additionally, each compound displays contacts of the form C-H.Cl, mainly to the Cl(-) anion. The net effect is to create either a layer structure (3-isomer) or a three-dimensional packing with easily identifiable layer substructures (2- and 4-isomers).