Preparation and characterization of pyridinium- n-carboxylate trioxochromate (VI) ( n=3, 4) and pyridinium-4-carboxylic pyridine-4 carboxylate trioxochromate (VI) hemihydrate

• Published in: Inorganica Chimica Acta Vol. 258; no. 1; pp. 53 - 63
• Main Authors: Martin-Zarza, Pedro, Gili, Pedro, Ruiz-Perez, Catalina, Rodriguez-Romero, Fernando V., Lotter, German, Arrieta, Juan M., Torrent, Maricel, Mestres, Jordi, Solà, Miquel, Duran, Miquel
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.05.1997
• Subjects: Chromium complexes; Crystal structures; Oxide complexes; Pyridinium carboxyllic acids complexes; Chromium complexes; Crystal structures; Pyridinium carboxyllic acids complexes; Oxide complexes
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/S0020-1693(96)05512-0

Three chromium (VI) compounds have been synthesized at room temperature by reaction of CrO 3 with pyridinium carboxylic acids in water. An X-ray diffraction study of pyridinium-3-carboxylate trioxochromate, [3-HNicCrO 3] ( 1), indicates crystallization in the triclinic system, space group P l (No. 2) with Z = 2 and lattice parameters a = 7.548(3) A ̊ , b = 6.593(3) A ̊ , c = 7.820(3) α = 90.01(2)°, β = 91.65(2)°, γ = 89.91(2)° and V = 389.0(3) A ̊ 3 at 25(2)°C. The chromium atom presents a distorted tetrahedral coordination, with the three CrO (terminal oxygen) bond lengths ranging from 1.588(6) Å to 1.603(6) Å, and the fourth CrO bond being 1.881(4) Å long. The symmetry is C 81 all atoms lying in the same plane with the exception of two terminal oxygens. 3-HNicCrO 3 molecules interact by hydrogen bonds. This experimental work has been complemented with a theoretical study to discuss geometries, relative energies for the two possible isomers of compound 1, IR and UV-visible spectroscopic data, and electronic analyses. Powder data for pyridinium-4-carboxylic pyridine-4- carboxylate trioxochromate hemihydrate, [4-HNic][4-NicCrO 3] ( 2), and pyridinium-4-carboxylate trioxochromate, [4-HNicCrO 3] ( 3), are also reported.