The synthesis and crystal structure of thermochromic, yellow benzimidazolium tetrachlorocuprate(II), (C7H7N2)2CUCl4 (1), have been reported. The compound crystallizes in the C2/c space group and contains discrete tetrahedral CuCl42- species. It absorbs one molecule of water from humid atmosphere at room temperature to produce a hydrated green form, (C7H7N2)2 CUCl4·H2O, which upon heating loses the water molecule in two steps to form the anhydrous yellow compound 1. The role of the water molecule on the solid state, yellow⇋green thermochromic transformation is discussed.
Bibliographical noteFunding Information:
We would like to thank the University Grant Commission, India, for the financial support (Sanction No. UGC/2976/GRW(UNG) 99-00).
- Crystal structures