Triorganotin(IV) derivatives of umbelliferone (7-hydroxycoumarin) and their adducts with 1,10-phenanthroline: synthesis, structural and biological studies

New triorganotin(IV) derivatives of the general formula R3Sn(Umb) (where, R = Me, n-Bu and Ph; Umb = umbelliferone anion) have been synthesized using sodium salt method. Further, the adducts of the general formula R3Sn(Umb) · phen (where R = Me and Ph; phen = 1,10-phenanthroline) have also been synthesized by the interaction of the triorganotin(IV) derivatives of umbelliferone with 1,10-phenanthroline. The bonding and coordination behavior of these derivatives are discussed on the basis of IR, NMR (1H, 13C and 119Sn), and 119Sn Mössbauer spectroscopic studies. These investigations indicate that umbelliferone acts as a monoanionic bidentate ligand in R3Sn(Umb) coordinating through O(7) and O(1) in the solid-state. These polymeric R3Sn(Umb) derivatives (where R = Me and n-Bu) have been proposed to have a trans-trigonal bipyramidal geometry with the three R groups in equatorial positions, while the axial positions are occupied by a phenolic oxygen and the O(1) atom from the adjacent molecule. A pseudotetrahedral geometry has been suggested for Ph3Sn(Umb). A distorted octahedral geometry around tin has been proposed for R3Sn(Umb) · phen, in which umbelliferone anion acts as a monodentate ligand coordinating through phenolic oxygen O(7). The newly synthesized derivatives have been assayed for their anti-inflammatory, cardiovascular and anti-microbial activities. The average LD50 values >1000 mg kg−1 of these derivatives indicate their safety margin. Among all the compounds tested, Ph3Sn(Umb) · phen has been found to show potent anti-inflammatory activity with low mammalian toxicity and mild hypotensive activity.