CHARACTERIZATION OF MONOMERIC GREEN AND POLYMERIC ORANGE FORMS OF A SCHIFF-BASE OXOVANADIUM(IV) COMPLEX AND INTERCONVERSION BETWEEN THESE SPECIES

{N,N'-Disalicylidene-(R,R)-1, 2-diphenyl-1, 2-ethanediamine}oxovanadium(IV) crystallized in two different forms, green (from chlorinated solvents) and orange (from acetonitrile). X-ray structure analyses revealed that the green form contains mononuclear square pyramidal molecules of the complex, while the orange form has a polynuclear linear chain structure. The green crystals turn orange when heated at 120 degrees C for a few minutes. The orange crystals turn green When exposed to chloroform vapor, and the green crystals turn orange when exposed to acetonitrile vapor. The orange complex shows piezochromism (mechanochromism); its color changes to green on grinding.