Synthesis, crystal structure, and herbicidal activity of two tetranuclear di(n-butyl)tin aryloyacetates complexes with Sn₄O₈ cluster

Two tetranuclear di(n-butyl)tin aryloyacetates [(o-R-C6H4-OCH2COOSn(n-Bu)(2))(2)O](2) (R=H (C1), Cl (C2)) have been synthesized by the reaction of phenoxyacetic acid or o-chlorophenoxyacetic acid with dibutyltin oxide, respectively. The structures were characterized by elemental analysis, IR, H-1, C-13 NMR, and X-ray crystal diffraction. There is a ladder structure formed by a four-membered central endocyclic Sn2O2 unit in the independent molecules of complexes C1 and C2, two carboxyl oxygen atoms and an Sn-O-Sn unit constituted the six-membered ring on both sides of the ladder, which constitutes the Sn4O8 configuration. Thermogravimetric analysis shows that the complexes possess good thermal stability in the air atmosphere. Herbicidal activity results show that complex C1 has good regulative effects on the growth of Cassia tora Linn., and complex C2 has better inhibitory activity against the root and stalk of Amaranthus spinosus at the concentration of 50 mol.L-1.