Short communication: A thermochromism study in the ferrocenyl‐benzopyran series

The synthesis and the photochromic behaviour of a series of benzopyrans (otherwise called 2H‐chromenes), substituted in the 2‐position by a metallocene, have been previously described. Some of these compounds also present thermochromic properties. As the thermochromism has been scarcely studied in the benzopyran series, we describe here a study of the thermochromic properties of ferrocenyl benzopyrans. The correlations between the structure of the compounds investigated and their thermochromic properties are discussed. Copyright © 2004 John Wiley & Sons, Ltd.