STUDIES IN ARYLTIN CHEMISTRY .7. SPECTROSCOPIC AND FUNGICIDAL STUDIESOF SOME P-SUBSTITUTED TRI-ARYLTIN ACETATES, OXIDES AND HYDROXIDES

The fungicidal activity of a series of aryltin compounds, (p-ZC(6)H(4) )(3)SnX (X=OAc, OH, or 1/2O), where Z=F, Cl, CH3, CH3O, C2H5 or (CH3)( 3)C, and for which IR and NMR (Sn-119) data are reported, has been ass essed by radial growth assays on Aspergillus niger, Botrytis cinera, M ucor hiemalis, Fusarium solani and Penicillium chrysogenum, and the re sults compared with those for the Ph3SnOAc and Ph3SnOH archetypes, In most cases, para-substitution only slightly reduces biocidal activity, but with p-CH3O the aryltin is completely ineffective, This result co rrelates with the seemingly decreased ability of the '(p-CH3OC6H4)(3)S n' moiety to achieve a trigonal-bipyramidal five-coordinate geometry w ith oxygen atoms in the axial positions, all other Ar3SnOAc and Ar3SnO H having this geometry in the solid state, A model for fungicidal acti on is proposed based on the need for the organotin inhibitor to attain the above geometry in the active site that it occupies in the ATPase enzyme, being the required condition for its biological activity. (C) 1997 John Wiley & Sons, Ltd.