Department of Chemistry, University of Rajasthan, Jaipur-302 004, India E-mail : kudiwal@datainfosys.net Fax: 91-141-519221 Manuscript received 5 February 2001. revised 28 June 2001. accepted 15 September 2001 Template condensation reaction of dicarboxylic acids (malonic, succinic, glutaric, adipic or phthalic) with primary diamines 1,2· diaminoethane, 1,3-diaminopropane or diethylenetriamine in 1 : 2 : 2 molar ratio gives a new series of 16 to 26 membered tetraazamacrocyclic complexes of composition [Sn(MaCn)Cl2], All the complexes are stable and monomeric in nature. The spectral studies confirm the proposed framework of the new macrocyclic complexes and the coordination of amide nitrogen to the central tin metal. An octahedral geometry for these complexes has been proposed. Their biological activities have also been studied.