Indian Journal of Chemistry Vol. ... Sandeep Nayyar, Inderraj Trehan & lasamrit Kaur* Department of Chemistry, Panjab University, Chandigarh 1 60 01 4, India E-mail: jasllayyar@yahoo.co.UK Received 20 June 200 I .. accepted ... 2344 INDIAN J. CHEM., SEC B, NOVEMBER 2002 ...