There were obtained and investigated the coordination compounds of two types: homo- and heterotrinuclear μ3-oxo clusters [FeIII3O(CH3COO)6L3]X and [FeIII2MIIO(CH3COO)6L3] (MII=Co, Mn; L= nicotinamide (vitamine PP), diethylnicotinamide (cordiamine), water; X=NO3-) and Co(III) dioximates. In the trinuclear clusters metal ions form an almost equilateral triangle with oxygen ion O2- in the center connecting the vertexes of three octahedrons, the other three being occupied by three molecules L. In the equatorial plan octaedrons are linked together by two acetate anions. Cobalt(III) dioximates have the octahedral structure, the base of which forms two monoanions of dimethylglyoxime with two cementing hydrogen bonds of O-H···O type. Axial coordinate is occupied by twomolecules L (in trans position). The compounds were investigated by IR- and Mössbauer spectroscopy and X-ray diffraction. As subjects for research of biological activity there served Zea mays L. plants, hybrids M 291 and P 459; Phaseolus vulgaris L., variety Porumbita, Glycine max, Merr. (L.), variety Bucuria, Cucumis sativus L., varieties Concurent and Mirabella, hybrids Rodnicioc F1 Concurent and Mirabella and F1 Icar F; Lycopersicon esculentum L. cv. Leader; Arachis hypogeae (L.), variety Fazenda 2, beet plants (Beta vulgaris L. var. Conditiva Alef ..); sugar beet (Beta vulgaris L., var. Baracuda), garlic (Allium sativum L. variety Izumrud), and other. Treatment of seeds before seeding and foliage during the vegetation season with aqueous solutions of studied complexes has provided optimal functional status, growth and development of plants. Coordination compounds used have been able to activate vital processes already at the initial stages of the development of individual plants, stimulate the growth of root and shoot systems and provides homeostating of the water status under hydric suboptimal regime, increase productivity of plants, strengthen the protective functions of the organism, increase tolerance to suboptimal factors. Under moisture deficiency the complexes of cobalt (III) have the mitigation impact of drought effects on forming the assimilative capacity, accumulation of plant biomass and harvest. Using physiologically active substances, containing in their molecule the nutrient elements, ensure stabilization of the production process of the plant. Coordination compounds of iron and cobalt containing nicotinamide, N, N-diethynicotinamide and thiourea possessed antioxidant properties that have been showed by increasing the capacity of antioxidant protection of treated plants as a result of the intensification of the activity of antioxidant enzymes with positive impact on plants productivity.