278 ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2017, Vol. 43, No. 5, pp. 278–285. © Pleiades Publishing, Ltd., 2017. Original Russian Text © E.B. Coropceanu, L. Croitor, A.A. Ciloci, Zh.P. Tyurina, E.G. Dvornina, C.Z. Codreanu, M.S. Fonari, 2017, published in Koordinatsionnaya Khimiya, 2017, Vol. 43, No. 5, pp. 268–274. Synthesis and Structure of Mononuclear Zinc Complexes with Pyridine-2-Aldoxime E. B. Coropceanu a, b, *, L. Croitor c , A. A. Ciloci d , Zh. P. Tyurina d , E. G. Dvornina d , C. Z. Codreanu b , and M. S. Fonari c a Institute of Chemistry, Academy of Sciences of Moldova, Chisinau, Moldova b Tiraspol State University, Chisinau, Moldova c Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau, Moldova d Institute of Microbiology and Biotechnology, Academy of Sciences of Moldova, Chisinau, Moldova *e-mail: ecoropceanu@yahoo.com Received July 25, 2016 Abstract—Three mononuclear different-ligand Zn(II) complexes, [Zn(CH 3 COO) 2 (PaoH) 2 ] (I), [Zn(PaoH) 2 (DMSO) 2 ][BF 4 ] 2 (II), and [Zn(NCS) 2 (PaoH) 2 ] (III) (DMSO = dimethylsulfoxide) were pre- pared by the reaction of zinc acetate and tetrafluoroborate with pyridine-2-aldoxime (PaoH). The composi- tion and structure of the complexes were confirmed by IR spectroscopy and X-ray diffraction. All compounds crystallize in the monoclinic system, compounds I and II have space group P2 1 /n, while compound III has space group C2/c. In all compounds, the Zn coordination polyhedron is a distorted octahedron, which is formed by the N 4 O 2 sets of donor atoms in I and II and by N 6 in III. Complex I in the optimal concentration of 5–10 mg/L was found to stimulate the biosynthesis of standard (pH 4.7) amylases by the micromycete Aspergillus niger CNMN FD 06. Keywords: coordination compounds, crystal structure, zinc cation, pyridine-2-aldoxime, stimulation of bio- synthesis, amylolytic activity DOI: 10.1134/S1070328417050025 INTRODUCTION The last decades are characterized by vigorous progress in the synthesis and studies of complexes based on pyridine-n-aldoxime ligands (n = 2, 3, 4) [1]. Of particular interest is the manufacture of new mate- rials with useful properties: molecular magnets [2–6], photoluminescent materials [7], catalysts for cleavage of carboxylic acid esters [8], stimulatory agents for biological processes [9] and so on. Both homo- and heterometallic coordination compounds with pyri- dine-n-aldoximes are known [10–12]. Previously, we studied some discrete complexes and coordination polymers of zinc, cadmium, manganese(II), and cop- per(II) with pyridine-4-aldoxime and pyridine-2- aldoxime [13–16]. The advantage of pyridine-2- aldoxime (PaoH) over the two other positional iso- mers is the possibility to form strong metal chelates via simultaneous coordination of both the pyridine nitro- gen and oxime nitrogen/oxygen atoms to the metal. The literature contains data for mono- [13, 17, 18], bis- [19, 20], and tris-oxime [21–23] mononuclear complexes based on pyridine-2-aldoxime and polynu- clear homo- and heterometallic [24, 25] clusters with magnetic properties [2–6, 26] induced by the bridging coordination of this ligand to metal cations. The vari- ous possible coordination modes of the ligand, coor- dination capacities of transition metals, and condi- tions of synthesis and the addition of other chelating ligands may increase the structural diversity of the resulting complexes [27]. A bridging coordination of the PaoH ligand to the metal is also possible [20, 28]. This communication describes the synthesis and structure of three mononuclear zinc complexes with pyridine-2-aldoxime, [Zn(CH 3 COO) 2 (PaoH) 2 ] (I), [Zn(PaoH) 2 (DMSO) 2 ][BF 4 ] 2 (II), and [Zn(NCS) 2 (PaoH) 2 ] (III), and presents data on the biological activity of compound I. EXPERIMENTAL Synthesis of I. Pyridine-2-aldoxime (24.00 mg, 0.2 mmol) was added to a solution of Zn(CH 3 COO) 2 · 2H 2 O (21.9 mg, 0.1 mmol) in 30 mL of a CH 3 OH– DMF mixture (5 : 1), where DMF is dimethylforma- N N OH PaoH