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The electronic structures and the character of the electron density redistribution in the palladium complexes with the redox-active ligands in the oxidized and nonoxidized forms are studied by X-ray photoelectron spectroscopy. According to the photoelectron spectroscopic data, the redox-active ligands exist in different oxidation states due to the redox process proceeding “at ligand.” It is shown that the transition from the neutral to oxidized semiquinone form (from [Pd(LMe)2]·2Cl·H2O to [Pd $$\left( {{\text{L}}_{{{\text{Ph}}}}^{{{\text{ISQ}}}}} \right)$$ 2]) occurs in the ligand and involves no palladium ions, and the oxidation state of palladium remains unchanged: Pd(II). A significant difference in the photoelectron spectroscopic characteristics obtained for the oxidized trans-complex at 298 and 153 K indicates a specific electronic lability of this complex.

The effect of bulky tridentate ligands on the geometry of carboxylate complexes was studied in relation to hexahydro-1,3,5-trimethyl-1,3,5-triazine (TACH). The reaction of [Co2Gd(NO3)(Piv)6(MeCN)2] (Piv is the pivalic acid anion) with TACH gave the complex [Co2Gd(NO3)(Piv)6(TACH)2] (I), in which the initial heterometallic moiety was retained and cobalt(II) ions coordinated the N-donor ligand to give a half-sandwich structure. The use of Cd(II) and Eu(III) pentafluorobenzoates in the reaction with TACH resulted in the isolation of only the homometallic complex [Cd(Pfb)2(TACH)2] (II) (Pfb is pentafluorobenzoic acid anion). Owing to high coordination number of cadmium(II) ion in II, a sandwich complex with two TACH molecules coordinated to the same metal ion was obtained. The structure of new complexes was determined by X-ray diffraction (CIF file CCDC nos. 2062230 (I) and 2062229 (II)). It was shown that binding of an N-donor ligand to a metal ion induces a significant distortion of the metal coordination polyhedra and a conformational change of hexahydro-1,3,5-trimethyl-1,3,5-triazine.

New zinc(II) compounds with cyclobutane-1,1-dicarboxylic acid (H2Cbdc) anions and calcium [CaZn(Cbdc)2(H2O)3]n (I) and barium [BaZn(Cbdc)2(H2O)2]n (II) cations were obtained. According to X-ray diffraction data (CIF files CCDC nos. 2055176 (I), 2055177 (II)), compounds I and II are coordination polymers in which zinc atoms are connected by bridging and chelating-bridging acid dianions to form 2D architectures with a square lattice topology. Alkaline earth metal atoms do not affect the dimensionality of compound packing.

The binuclear cadmium complexes in which the metal atoms are linked by two chelate-bridging carboxylate anions, [Cd2L2(µ2-(Рiv)2(κO,κO'-(Рiv)2] (L is 2,4-lutidine, phenanthridine, and 2,2'-bipyridine; and Рiv is pivalate anion), and the complexes with the “Chinese lantern” structure in which the cadmium atoms are linked by four bridging carboxylate anions, [Cd2L2(µ2-(Рiv)4] (L is 2,3-cyclododecenopyridine (Сdpy)) and [Cd2(L)2(µ2-(PfAc))4] (L is 1,10-phenanthroline, and PfAc is pentafluorophenylacetate anion), are considered. The two-bridge and four-bridge isomers of each binuclear [Cd2L2(Рiv)4] complex with the monodentate and chelating N-donor ligands are calculated by the density functional theory using four different approximations. The stabilities of the isomers are compared and conclusions about the factors leading to the formation of complexes of this or another structure are made on the basis of the calculation data.

The new anionic dimethylmalonate complex {Ni36(H2O)12(OH)20(HMe2Mal)(Me2Mal)29@ [Mg(H2O)6]}5– (Me2Mal2– is the dimethylmalonate anion) containing the internal aquated [Mg(H2O)6]2+ ion and the external [Mg3(OH)(H2O)10(C2H5OH)3]5+ cation was prepared by hydrothermal synthesis. The crystalline compound isolated from the reaction mixture and characterized by X-ray diffraction had the formula [Mg3(OH)(H2O)10(C2H5OH)3]{Ni36(H2O)12(OH)20(HMe2Mal)(Me2Mal)29@[Mg(H2O)6]}·25H2O (I) (CIF file CCDC no. 2038910). The new anionic complex {Ni36(H2O)12(OH)19(O)(Cbdc)30@[Na(H2O)6]}8– (Cbdc2– is the cyclobutane-1,1-dicarboxylate anion) containing the internal aquated [Na(H2O)6]+ ion and outer-sphere tetrabutylammonium cations was prepared from an ethanol–acetonitrile solution. The crystals isolated from the reaction mixture were characterized by X-ray diffraction and were described the formula (NBu4)8{Ni36(H2O)12(OH)19(O)(Cbdc)30@[Na(H2O)6]} (CIF file CCDC no. 2038909) (II). It was found that the magnetic behavior of complex I is due to competing ferro- and antifferromagnetic exchange interactions between paramagnetic nickel(II) ions.

A series of the cadmium and zinc carboxylate complexes with anions of pentafluorobenzoic (HРfbz) and 2,3,4,5-tetrafluorobenzoic (HТfbz) acids and N-donor ligands (1,10-phenanthroline (Phen) and quinoline (Quin)), [Cd(Pfbz)2(Phen)]n (I), [Cd(Рfbz)2(Рhen)2]·2MeCN (II), [Zn(H2O)-(Рfbz)2(Рhen)] (III), [Zn2Cd(Рfbz)6(Рhen)2]⋅2C6H6 (IV), [Cd2(H2O)2(Tfbz)4(Рhen)2] (V), [Cd2-(H2O)2(Tfbz)4(Quin)2] (VI), and [Cd(Tfbz)2(Phen)2]⋅HTfbz (VII), is synthesized. The structures of new complexes I–VII are determined by X-ray diffraction analysis (CIF files CCDC nos. 1871300, 2005461, 2005462, 2005464, 2005466, 2005465, and 2005459, respectively). The majority of the synthesized compounds is typical of intramolecular stacking interactions between the coordinated molecules of the aromatic N-donor ligands and fluorinated substituents of the carboxylate anions. These interactions lead to the formation of unusual compounds, which are different in the cases of pentafluorobenzoates and tetrafluorobenzoates, in particular, coordination polymer I and binuclear complexes V and VI with coordinated water molecules. The synthesized zinc and cadmium compounds differ in structure and composition.

The mononuclear complexes [M(Fur)2(Bpy)(H2O)] (M = Cu (I), Zn (II)) were prepared by the reactions of copper(II) and zinc(II) acetates with 2-furoic acid (HFur) anion and 2,2'-bipyridine (Bpy) in acetonitrile. A similar reaction with ZnCl2 used instead of Zn(OAc)2 · 2H2O gave the complex [Zn(Fur)2(Bpy)] (III). The cobalt(II) complex [Co(Fur)2(Bpy)] (IV) was obtained by the reaction of cobalt trimethylacetate with HFur and Bpy. The structure of mononuclear complexes was determined by X-ray diffraction (CIF files CCDC nos. 1993168 (I), 1993169 (II), 1993170 (III), and 1993171 (IV)). Compounds I, III, and IV were studied for the biological activity in vitro against the nonpathogenic mycobacterial strain Mycolicibacterium smegmatis. It was found that I and III have high biological activity and are promising for further studies for antituberculosis activity.