Deborah Whalen

Fungicidal and spectral studies of some triphenyltin compounds

In the interest of developing a more effective fungicide to combat Dutch elm disease, our laboratories have synthesized several triphenyltin carboxylates and some 1:1 addition compounds of triphenyltin chloride using 2,3-disubstituted thiazolidin-4-ones as the ligand and screened them in vitro against Ceratocystis ulmi, the causative agent of Dutch elm disease, using a shake culture method. Elemental analyses and spectroscopic data indicate that the structures of the carboxylates in the solid state are monomeric with a tetrahedral tin atom with the exception of the furan-2-carboxylic acid derivative, which was found to be polymeric. The triphenyltin chloride adducts are trigonal-bipyramidal with the three phenyl groups in the equatorial plane. Far-infrared data indicate that the three phenyl groups are not co-planar. Screening results for both series of organotins indicate that these two classes of compounds are effective inhibitors of Ceratocystis ulmi, with the adducts having a higher activity. The furan-2-carboxylic acid derivative has a markedly decreased activity compared with the other carboxylates and this is attributed to its polymeric structure.

Fungicidal activity of some organotin compounds against ceratocystis ulmi

Three series of organotin compounds were screened in vitro against Ceratocystis ulmi, the causative agent of Dutch elm disease. The series that were most active against this deadly fungus were those that contained the triphenyltin moiety. In addition, the fungicidal activity of the triphenyltin compounds were found to be independent of the anionic group attached to the tin atom. However, there was a marked increase in the activity of the triphenyltins when a biologically active group which did not dissociate upon dissolution was incorporated into the overall molecule.

The synthesis, structural characterization and biocidal properties of some triorganotin(IV) esters of N-arylidene-ω-amino acids.

The methods of synthesis, elemental analysis, IR and NMR spectroscopic data and fungicidal activity against Ceratocystis ulmi are reported for a series of triorganotin esters of N-arylidene-ω-amino acids of general formula R 3 SnO-CO(CH 2 ) n N = CHAr (R = Ph, n-Bu; Ar = 2-HOC 6 H 4 , 2-HOC 10 H 6 ; n = 1, 2, 3 and 5). The crystal structures for two of the compounds, tributyltin N-2-hydroxynaphthalidene glycinate (1) and tributyltin N-2-hydroxynaphthalidene-β-alaninate (2), have been determined. Although both of these compounds have a trans-R 3 SnO 2 structure, in compound 1 the carboxylate group is monodentate and the fifth coordination position around the tin atom is taken up by a coordinated phenolic group, whereas in 2 the carboxylate group is bridging. These two examples thus correspond to the two different structures reported for trans-R 3 SnO 2 complexes. Both compounds were found to be active against Ceratocystis ulmi, but there was no significant difference in their levels of biological activity against this particular fungus. Apart from compound 1, the other tributyltin compounds reported are believed to adopt the carboxylate bridging mode shown by compound (2). Crystal data: for 1, crystals monoclinic, space group P2 1 /c, a = 12.9435(11) A, b = 13.5769(10) A, c = 15.7715(12) A, β = 108.919(6)°, Z = 4, R f = 0.046 and R w = 0.058 for 1448 significant reflections; for 2, crystals monoclinic, space group C 2/c, a = 24.588(14) A, b = 9.733(3) A, c = 27.611(12) A, β = 113.49(4)°, Z = 8, R f = 0.053 and R w = 0.069 for 3822 significant reflections.

Molecular Structure and Fungicidal Activity against Ceratocystis ulmi of the 1:1 Adducts of Triphenyltin Chloride and 2,3‐Disubstituted Thiazolidin‐4‐ones

Several 1 : 1 addition compounds between triphenyltin chloride and 2,3-disubstituted thiazolidin-4-one ligands have been synthesized. Their molecular structure has been deduced using far IR and Mossbauer spectroscopies. In addition, molecular modeling of several of the complexes was used to explain the variation of the quadrupole splitting values in the Mossbauer spectra. The structures of the complexes were determined to be trigonal-bipyramidal with the three phenyl groups in the equatorial plane. However, the phenyl groups are not co-planar, on the basis of the observation of both the Sn-C (phenyl) symmetric and asymmetric stretching vibrations. The adducts were screened against the fungus Ceratocystis ulmi, the agent responsible for Dutch elm disease, and found to be effective in the inhibition of this fungus. The toxicity of the adducts varied with the hydrophobicity of the molecule. A direct correlation between substitution on the phenyl group on the thiazolidine ring and the toxicity of the compound was not observed.

Triphenyltin esters of N-(2-carboxybenzylidene)anilines : Synthesis, spectroscopic characterization, X-ray structure analysis and fungicidal activity

Four triphenyltin carboxylates formulated as o-Ph 3 SnOCOC 6 H 4 CH=N-Ar (Ar=C 6 H 5 ; p-CH 3 C 6 H 4 ; o-CH 3 C 6 H 4 ; o-HOC 6 H 4 ) were prepared and spectroscopically characterized. The crystal structure of o-Ph 3 SnOCOC 6 H 4 CH=NC 6 ,H 5 indicates that the tin atom, in each of the two molecules comprising the asymmetric unit, exists in a distorted tetrahedral geometry owing to an intramolecular acyl O...Sn contact. These new triphenyltin carboxylates display marked toxicity against the fungus Ceratocystis ulmi