Two novel macrocyclic organotin (IV) carboxylates based on bipyrazoledicarboxylic acid derivatives: Syntheses, crystal structures and antifungal activities

Abstract

Two new organotin (IV) bipyrazole-dicarboxylate macrocyclic complexes, C1 (C58H100N8O10Sn4) and C2 (C58H100N8O12Sn4, 4 H2O), are synthesized by reaction of the bipyrazole-dicarboxylic acids L1 = 1,1′-(propane-1,3-diyl)bis(5-methyl-1H-pyrazole-3-carboxylic acid) and L2 = 1,1′-(2-hydroxypropane-1,3-diyl)bis(5-methyl-1H-pyrazole-3-carboxylic acid) with oxide di-(n-butyl)tin. The structure of these complexes is characterized using NMR, IR and UV-visible spectroscopies as well as single crystal X-ray diffraction. Compound C1 crystallizes within the triclinic symmetry in space group P1¯ with a = 12.9410(5), b = 13.6143(5), c = 22.7675(8) Å, α = 92.981(1), β = 91.180(1), γ = 116.966(1) °, while C2 crystallizes within the rhombohedral symmetry in space group R3 with a = b = 29.4419(5), c = 23.0326(5) Å, α = β = 90 and γ = 120 °. The analysis by X-ray crystallography diffraction reveals that both complexes are centrosymmetric macrocycles and contain a tetra-nuclear four-fold ladder-like organo-oxotin cluster. Two Sn atoms are found to be five-coordinated while the two others are four-coordinated. The antifungal activity of these metal-cyclic compounds C1 and C2 is examined and compared to that of the corresponding ligands against the pathogenic strain Fusarium oxysporum f. sp. albedinis. The complexes C1 and C2 possess an interesting fungicidal power even higher than the ligands L1 and L2.