1,2-Bis-(1-{3-pyridyl-}3-methyltriazen-3-yl)ethane: Synthesis and X-ray crystal structure

Abstract

3-Aminopyridine is diazotized in the conventional manner and the diazonium salt coupled with N,N ′-dimethylethylenediamine to afford the title compound (1), which is a potential antitumour agent. The compound has been characterized by spectroscopic methods. The 1H NMR spectrum shows evidence of rotational conformerism, from the observation of broadening of the N-methyl signals in the room-temperature spectrum. Low-temperature NMR spectra (down to 223 K) show the presence of three distinct rotamers. The crystal structure of 1,2-bis-(1-{3-pyridyl-}3-methyltriazen-3-yl)ethane (1) has been determined by single crystal X-ray diffraction analysis. The bis-triazene (1) exists as the "staggered" conformation in the solid state, with an "anti–anti" configuration around the N—N bond of the triazene units. The crystal structure of 1 is compared with the closely related bis-triazene 2 and also compared with the simple mono-triazene 3. Crystal data for 1, C14H18N8: orthorhombic, space group Pbca, a = 11.2550(8) Å, b = 8.8507(6) Å, c = 15.0069(10) Å, β = 90°, and V = 1494.91(18) Å3, for Z = 4.Key words: triazene, bis-triazene, pyridine, X-ray, VT NMR, diazonium coupling.