Synthesis, Crystal Structure, Spectroscopic, and Herbicidal Activity Studies of a Series of Designed Fluoro-Functionalized Phenylimido Derivatives of Hexametalate Cluster

Four novel fluoro-functionalized arylimido-substituted hexamolybadates, (n-Bu4N)2[Mo6O18(NAr)] (Ar = 2-CH3-4-FC6H3 (1), 3-CH3-4-FC6H3 (2), 4-FC6H4 (3), or 2-FC6H4 (4)), in which fluorinated phenylimido group linked to an Mo of hexamolybdate by a Mo−N triple bond, have been prepared via the DCC (N,N′-dicyclohexylcarbodiimide) dehydrating protocol of the reaction of α-octamolybdate ion with 2-methyl-4-fluoroaniline hydrochloride, 3-methyl-4-fluoroaniline hydrochloride, 4-fluoroaniline hydrochloride, or 2-fluoroaniline hydrochloride in anhydrous acetonitrile. All these compounds have been characterized by elemental analysis, UV−vis, IR, 1H NMR, and single-crystal X-ray diffraction analyses. The preliminary biological activity test indicated that these compounds display potent herbicidal activity, in particular against the roots of some tested plants (such as Brassica campestris L., Eclipta prostrata L., Echinochloa crusgallis L., and Cirsium japonicum DC.).