Synthesis and Characterization of Chromium-Isothiocyanate-4-Methylpyridine Complexes

Jennifer L. Young, Northwest Nazarene University
Jerry D. Harris, Northwest Nazarene University
Joshua A. Benjamin, Northwest Nazarene University
Jannah E. Fitch, Northwest Nazarene University
Daniel F. Nogales, Northwest Nazarene University
Joanna R. Walker, Northwest Nazarene University
Brian J. Frost, University of Nevada - Reno
Aaron Thurber, Boise State University
Alex Punnoose, Boise State University

Abstract

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 °C in dry air.