Nitration of metal ion coordinated imidazole and the crystal structure of pentaammine(4-nitroimidazolato)cobalt(III) chloride

Abstract

The title complex, [Co(NH3)5(N02Im)]Cl2, was prepared by the action of a standard HN03-H2S04 nitrating mixture on Co(NH3)5(ImH)3+. The complex has been characterized by NMR and UV-vis spectroscopy and a single-crystal X-ray structure determination. The pH dependence of the NMR spectra has been determined, and the pXa of the coordinated N02lm is 1.66. Crystal data for [Co(NH3)5(N02Im)]Cl2 is as follows: space group Pljn•, Z = 4; a = 9.434(2), b = 13.679 (3), c = 10.457 (3) A; 0 = 93.65 (2)°; V-1346.7 (5) A3; R = 4.5% for 2135 reflections.

Octahedral Co(III) complexes of 2-(phenylimino)pyrrolyl ligands: Synthesis and structural characterisation

“…1 and the corresponding selected bond distances (Å) and angles (°) are listed in Table 1. All of them show the cobalt atom coordinated to three iminopyrrolyl chelating ligands, in which the metal-pyrrole Co1-N1 bond distances are always shorter than the metal-imine Co1-N2 ones (see Table 1), the corresponding values being in agreement with those found for the single Co(III) aryliminopyrrolyl complex structure reported in the literature [6] and for other six-coordinated Co(III) complexes containing other anionic N-heterocyclic five-membered ring ligands [11]. All the complexes 2a-c can be described as fac (facial) isomers, since they display always the Co1-N pyrrole bonds trans to the Co1-N imine ones, likely reflecting a better stereochemical arrangement.…”

In situ facile nitration in hydrothermal reaction generating novel metal-organic coordination polymer

“…Nitration substitution is a quite common reaction in the organic synthesis [6], while the nitration reactions through coordination are sparse. Storm and co-workers found that the nitration in HNO 3 /H 2 SO 4 in the presence of metal ions is much more rapid and milder in synthesis conditions than the reaction of free imidazole [7]. Here we present the first nitration reaction achieved only by nitrate salt rather than HNO 3 / H 2 SO 4 under hydrothermal conditions, which displays that the coordination can remarkably activate the nitration, and the hydrothermal synthesis can be widely used to construct novel architectures.…”

Synthesis, structure and fluxionality of Co(III) complexes containing chelated sulfate

“…However, the stability of the starting material in the strongly acidic H 2 SO 4 and HNO 3 solutions is impressive, attesting to the truly substitution-inert nature of Co(III) complexes. [27]…”