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}oxovanadiu m(IV) crystallized in two different forms, green (from chlorinated sol vents) and orange (from acetonitrile). X-ray structure analyses reveal ed 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 chl oroform vapor, and the green crystals turn orange when exposed to acet onitrile vapor. The orange complex shows piezochromism (mechanochromis m); its color changes to green on grinding.