Synthesis and characterization of chromium-isothiocyanate-4-methylpyridine complexes

The synthesis and single crystal X-ray structure of trans-[HNC6H7][Cr(NCS)(4)(NC6H7)(2)] (1) and mer[Cr(NCS)(3)(NC6H7)(3)] (2) are reported. Compound 1 was synthesized by refluxing chromium powder and thiourea in 4-methylpyridine. The isothiocyanate ligand is believed to be generated from the isomerization of thiourea to ammonium thiocyanate during synthesis. Compound 2 was prepared from CrCl3 and KSCN in 4-methylpyridine. The reaction conditions for both compounds yielded a mixture of [Cr(NCS)(x)(NC6H7)(6) (x)](3) (x) isomers (x = 0-6), which were analyzed by HPLC. The thermal properties of trans-[HNC6H7][Cr(NCS)(4)(NC6H7)(2)] were analyzed by thermogravimetric analysis/differential scanning calorimetry-mass spectroscopy (TGA/DSC-MS), and the compound was found to oxidize to CrO2 in three major weight loss steps when heated to 1000 degrees C in dry air. (C) 2011 Elsevier B. V. All rights reserved.