Preparation of cobalt(II) and zinc(II) complexes with an asymmetric thiourea ligand, N-phenylpiperidine-1-
carbothioamide, (L), was achieved. The composition and structure of the complexes, [CoL2Cl2] (1) and [ZnL2Cl2]
(2), were determined using various techniques, including single-crystal X-ray diffraction. X-ray structural
analysis revealed a distorted tetrahedral arrangement in the vicinity of the central metal atoms, with coordination
involving two thioamide (L) ligands through their sulfur atoms and two chlorido ligands. Fusarium oxysporum
is one of the most damaging phytopathogens, causing substantial economic losses. Excessive application
of commercial antifungals promotes microbial resistance, making the search for new agents essential. The
bioactivity of the free ligand, the starting metal(II) chlorides, and complexes 1 and 2 (0–200 μg/ml) against
Fusarium oxysporum was evaluated, alongside Cycloheximide as a standard. All compounds exhibited higher
activities than the standard. The complexes were the most effective anti-Fusarium oxysporum agents, with the
highest inhibitions of 46 and 37 mm for 1, and 2, respectively. Experiments on the fungal pathogenicity of wheat
seeds indicated complete inhibition by complex 1 (pathogenicity = zero %), while pathogenicity was only 6.7 %
with complex 2. The phytotoxicity of these compounds was assessed based on the percentage of wheat germination
obtained. Complex 2 demonstrated the best results, being non-toxic to wheat seeds up to 100 μg/ml, but
its phytotoxicity at 200 μg/ml resulted in only 73 % wheat germination.