There were developed the novel methods for the synthesis of six mixed- metal and mixed-ligand complexes of germanium and rare earth metals (Pr, Nd, Dy, Ho, Tm, Lu) with 1-hydroxyethylidenediphosphonic acid and 2,2´-bipyridine. The compounds have been characterized using various research methods: elemental analysis, mass spectrometry, electrical conductivity, thermogravimetry, IR spectroscopy. It has proved that all complexes are crystal hydrates, belong to heterometallic mixed ligand compounds [Ln(H2O)4(bipy)2]2 [Ge(m-hedp) (m- OH)]6⸱nH2O, Ln=Pr (1); Nd (2); Dy (3); Ho (4); Tm (5); Lu (6); n = 22 (1, 2), 21 (3), 20 (4, 5), 19 (6). Their formation occurs due to the electrostatic interaction of complex cations [Ln(H2O)4(bipy)2]3+ with hexanuclear anions [Ge(m-hedp)(m- OH)]66-. According to the results of measuring the electrical conductivity of dimethylformamide solutions 1–6, it has been established that they belong to triionic electrolytes: λ (in Ohm-1∙сm2∙mol-1) for 1 = 131,3; 2 = 138,8; 3 = 145,8; 4 = 151,1; 5 = 158,3; 6 = 162,7. The cation-anionic type of complexes 1–6 has been confirmed as a result of the analysis of their mass spectrum. The analysis of the mass spectrum showed that the main decomposition direction of the complex is related to the formation of the complex cation fragment [Ln(H2O)4(bipy)2]3+, which corresponds to the most intense peak (m/z = 136, I = 55%). The thermal decomposition of compounds 1–6 includes dehydration, deaquatation, oxidative thermal destruction and the formation of final products as a mixture of Ln2O3 and GeP2O7. On the DTA curves in the interval 70–200 °C the first endothermic effect can be traced, which is accompanied by the removal of a certain number of crystallization and coordination water molecules into the gas phase. Absorption bands of the P-O bond have been detected at ~1053 and ~970 сm-1, that indicates the presence of the fully deprotonated PO32- groups in the composition of complexes. Furthermore, n(OH), ν(Ge–O), d(Ge–OH) bands characteristic for all the previously synthesized compounds with [Ge6(m-OH)6(m-hedp)6]6- anion have been detected in the IR spectra of 1–6. A set of the bands usual for the aromatic molecules n(C–C), das(CH3), ds(CH3), n(Сar=N) has been assigned with 2,2`-bipyridine in the structure of all compounds.

Authors have developed optimal conditions and synthetic methods in water-organic solutions for ten heterometallic – mixed-ligand complexes of germanium(IV) and 3d-metals with gallic acid (Н2Gal) and 1,10-phenanthroline (phen), their composition and structure [M(phen)3][Ge(H2O)(HGal)2]∙nH2O (M = Mn (1), Co (2), Ni (3), Zn(5)); [CuCl(phen)2]2[Ge(H2O)(HGal)2]∙2H2O (4). Comparative analysis of their IR-spectra and spectra gallic acid and 1,10-phenanthroline with involvement diffuse reflection spectra allowed to establish coordination sphere of germanium and 3-metals. IR-spectra of complexes 1-5 are similar, therefore coordination of ligands in them is the same. Comparatively to the IR-spectrum of gallic acid, there are absent valence absorption bands of free carboxylic groups while two bands of asymmetric and symmetric oscillation of C-O groups in carboxylate ions CОО- appear in the spectra of complexes. Deformation bands d(Сarom-О-Н) are shifted to the low-frequency region for 50-40 cm-1, which indicates deprotonation and binding to the complexing agent of OH-groups from gallic acid. Appearance of deformation bands d(H2О) at 1625 сm-1 is characteristic for the coordination water in composition of complexes. Presence of coordination and crystalline water as well as unbonded OH-group are confirmed with the band n(Ge-О) at 620 сm-1. Thermal decomposition of mixed-metal complexes starts with an endothermic effect in the temperature range 80-160°С where elimination of certain number of water molecules takes place: two – for 1 and 4, three – for 2 and 5, four – for 3. On the thermogravigrams of all compounds one more endoeffect in the temperature range 160-220°С is presented, where removal of one coordination water molecule happens. It was established, that coordination polyhedron of germanium was formed by five oxygen atoms of deprotonated hydroxyl groups from two molecules of gallic acid and one water molecule in all compounds. Second ligand – 1,10-phenanthroline is coordinated to 3d-metal through heterocyclic nitrogen atoms with formation of cations with different composition [M(phen)3]2+ (M = Mn, Co, Ni, Zn) та [CuCl(phen)2]+.

This article is dedicated to the investigation of crystalline structure in the complex cation-anionic compounds Cu(Phen)2Cl]2[Ge(HCit)2]⋅6H2O (I), [Cu(Phen)3]2[Ge2(OH)(HTart)(μ-Tart)2]·11H2O (II), [CuCl(Phen)2]4[{Ge2(OH)2(μ-Tart)2}Cl2]·4Н2О (III), [Cu(Phen)3]2[(OH)2Ge2(μ-HXylar)4Ge2(μ-OH)2]·8H2O (IV), [CuCl(Phen)2]4[(OH)2Ge2(μ-HXylar)4Ge2(μ-OH)2]·8H2O (V) using Hirshfeld surface analysis. This method has showed itself as an effective tool for analysis of intermolecular interactions, such as hydrogen bonds or weaker C…H and С…Н…p connections. Three-dimensional picture of close interactions in the crystal was built for each of the compounds I–V, where short connections are red-colored, while others – weaker and shorter – are light areas and small spots. It was established that in the structures of all compounds different types of hydrogen bonds are presented: bifurcate connections, symmetrical О-Н…О, С-Н…С and asymmetrical ones with water molecules. Two-dimensional histograms – 2D-fingerprint plots, allowed to evaluate quantitively connections in the crystals and establish that H…O/O…H and H…H interactions make the biggest contribution to the total surface area. The presence of the big number of crystallization water molecules is determinant for the formation of complex system of hydrogen bonds and strengthening of the structure, that otherwise would be unstable because of the big size of cations and anions. Due to the fact, that all compounds have the same complexing agent Ge(IV), structure of the anion is determined by polydentate ligand. Obtained results are important for the further development of the water role in the processes of crystallization, crystal formation, electrical dissociation and, especially, dissolving of coordination compounds in biological systems.

There have been developed a novel synthetic method that allowed to obtain raw of mixed-ligand heterometallic binuclear complexes of Ge(IV)-M2+ (Mn, Fe, Co, Ni, Zn) with 1,3-diamino‑2-hydroxypropane N, N, N’, N’-tetraacetic acid (H5hpdta). Compounds have been characterized by the set of methods: elemental analysis, thermogravimetry, IR‑spectroscopy, spectrum of diffuse reflection, magnetic suspensibility. According to the elemental analysis, the molar ratio Ge: M: H5hpdta: bipy= 1:1:1:1 in the obtained compounds 1‑5 corresponds to the formula [(H2O)(OH)Ge(m-hpdta)M(bipy)]·nН2О (M=Mn n=3 (1), Fe n=2 (2), Co n=4 (3), Ni n=4 (4), Zn n=3 (5). Complexes have yellow (1), red (2), orange (3), violet (4) and pink (5) colors and are stable on air. Compounds 1‑5 exist in the form of crystal hydrates, that contain certain amount of water molecules, that are eliminated into the gas phase while heating in the wide range of temperatures (t=80‑250 °C), which is accompanied with the low-temperature endothermic effect. This indicates the presence of a system of stable hydrogen bonds in their crystal structure. Analysis of the IR‑spectra 1‑5 revealed that form and coordination of ligands is similar. Deprotonation of all carboxylic groups in the ligands (H5hpdta) and their bonding to germanium and d-metal is confirmed with the absence in the IR‑spectra 1‑5 absorption bands characteristic for the free СООН H5hpdta (1716 сm‑1) and nas(СОО-) і ns(СОО-) bands. Disappearance of the ν(С-OН)-1210 сm‑1 and appearance of the ν(С-O)alk., νas(Ge-O-M), νs(Ge-O- M) absorption band indicates that OH‑group of H5hpdta is deprotonated and performs bridging function. 2,2`-bipyridine bidentatly coordinates to the d-metal, binds to the O, N‑atoms of hpdta5- ligand and reaches coordination number 6. The last ligand plays the bringing role between Ge-dmetal, shows itself as ditopic, octadentate in total. According to the magnetic moments of 3, 4 and their diffuse reflection spectra, polyhedrons of Co (II), Ni (II) are octahedrons, which are realized due to the bidentate coordination of bipyridine and four bonds with nitrogen and oxygen of hpdta5-. Structure of heterometallic binuclear complexes 1‑5 is similar. Ligand hpdta5- shows itself as octadentate ditopic, all carboxylate groups monodentatly coordinate to metals, oxygen atom of the deprotonated OH‑group performs the bridging function.

New xylatogermanates with the same homogermanate complex anion and various phenanthrolinecopper(II) cations, namely, [Cu(Phen)3]2[(OH)2Ge2(µ-HXylar)4Ge2(µ-OH)2] · 8H2O (I), [Cu(H2O)(Phen)2]2[(OH)2Ge2(µ-HXylar)4Ge2(µ-OH)2] · 8H2O (II), and [CuCl(Phen)2]4[(OH)2Ge2(µ-HXylar)4Ge2(µ-OH)2] · 8H2O (III), have been synthesized by the developed method and studied by IR spectroscopy and thermogravimetry. According to X-ray diffraction data, they represent ionic type complexes with the [(OH)2Ge2(μ-HXylar)4Ge2(μ-OH)2]4– tetranuclear germanium-containing complex anion and three complex cations: [Cu(Phen)3]2+ (I), [Cu(H2O)(Phen)2]2+ (II), and [CuCl(Phen)]+ (III). The Ge atoms in the complex anion have two types of coordination: they are five- or six-coordinated. Each Ge atom is linked to the deprotonated carboxylic and hydroxyl groups of two xylaric acid molecules. The five-coordinated Ge atom is additionally linked to one terminal hydroxyl ligand, and the six-coordinated Ge atom is linked to two bridging hydroxyl groups. In crystal structures I and II, cations and anions form alternating layers, which are interchangeably composed of cations and anions. In crystal structure III, cations form “porous” layers, whose cavities accommodate chains of anions. The layers of cations are linked by weak stacking-interactions between the π-systems of Phen.

New heteronuclear Germanium(IV)‑ Thulium (III) complex with 1,3‑diamino‑2‑propanoltetraacetic acid (H5hpdta) was synthesized for the first time. Comparative analysis of IR‑spectrum of complex and ligand proved the absence of free COOH‑groups in the structure of compound – there are no ν(СООН) absorption bands in the IR‑spectra of complex. The significant shift of the ν(С‑N) absorption band (about 45 cm-1), ν(СН) (about 5 cm-1) and presence of ν(Ge‑N) and ν(Tm‑N) bands evidences that protonized nitrogen atoms form coordination bonds with metals. Two pairs of νas(СОО) and νs(СОО) absorption bands of carboxylate ions together with stretching vibrations of Ge‑O and Tm‑O bonds confirm their coordination to metals. There are also presented νas(Ge‑O‑Tm), νs(Ge‑O‑Tm), δ(OH) and δ(Ge‑OH) absorption bands in the IR‑spectrum of complex that indicates the bridging nature of deprotonated hydroxy and hydroxyl group of ligand and also hydrolyzed form of germanium in the structure of compound. During thermal decomposition of the complex in the temperature range of 90‑150 °С as a result of the endothermic effect, two molecules of crystallization water are removed into the gas phase. The further endoeffects at around 150‑220° C are seen with the removal of three coordinated water molecules. The oxidative destruction of the complexes is accompanied by the three exoeffects in temperature range 220‑800 °С. The products of final thermal destruction at 1000°C are GeO2 and Tm2O3. According to the X‑Ray diffraction data of complex [Ge(ОН)(μ‑hpdta)(μ‑OH) Tm(H2O)3]*2H2O, the six‑coordinated atom of Germany and octa‑coordinated atom of Thulium are bound by the bridging oxygen atom of hydroxyl group and hydroxyl-anion. Thecoordination polyhedron of Ge(1) atom is a distorted octahedron formed by three O atoms of deprotonated carboxyl and hydroxyl groups, the nitrogen atom of the hpdta5– and two O atoms of two hydroxyl-anions. The coordination polyhedron of octa-coordinated atom of Thulium is formed by of the O atoms of deprotonated carboxyl, deprotonated hydroxyl groups of the hpdta5–, the bridging oxygen atom of hydroxyl‑anion, three O atoms of coordinated water molecules and one N‑atom of the hpdta5–.

This review article summarizes the results of the study of the composition, structure and pharmacological activity of related different-metal cation-anionic complexes with bis(citrato) germanate(stannate) anion and hexaquacation of the second metal M(H2O)6][Ge(HCit)2]·nH2O and [M(H2O)6][Sn(HCit)2]·nH2O, де М = Mg, Mn, Fe, Co, Ni, Cu, Zn, n=2-4. The inspire for this study were the features of citric acid as an intermediate product of the metabolic cycle of tricarboxylic acids, which plays a major role in the system of biochemical reactions of cellular respiration. Authors defined the conditions for the formation of heterometallic complexes in the systems GeО2 (GeCl4, SnCl4) – citric acid (H4Cit) – M(CH3COO)2 (FeSO4, AgNO3) – H2O (М=Mg2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+), obtained their complete physicochemical characteristics, and also established their molecular and crystalline structures. All compounds have low toxicity. They were proved to have a wide range of pharmacological activity (neurotropic, antistaphylococcal, antiviral, antihypoxic, cerebroprotective. The level and characteristics of a particular type of pharmacological action of the studied drugs is determined by the metal ions – parts of the complex cations and anions, as well as their synergetic effect. The relationship between the composition, structure and pharmacological activity of the complexes was established. The novelty of the approach allowed to obtain supramolecular salts with the structural blocks of opposite charges – complex cations and anions of different metals. Therefore, they do not compete with each other for binding to biosubstrates, but potentiate or enhance each other’s action.

The mixed-ligand [Ge(HMal)2(bipy)]·bipy·2H2O (1) and mixed-ligand-heterometallic [Ni(phen)3][Ge(OH)(HMal)2]2·12H2O (2), [Ni(bipy)3][Ge(OH)(HMal)2]2·12H2O (3) germanium complexes with malic acid (H3Mal) and heterocyclic amines 2,2'-bipyridine (bipy), 1,10-phenanthroline (phen) were obtained for the first time. It was established that in the IR-spectra of 1-3 stretching vibrations of aromatic rings n(C-CАr) ~ 1598-1493 cm-1, ν(C-N) ~ 1315 cm-1, ν(C-N) ~ 1315сm-1, and also n(Ge-N) = 655 сm-1 (for 1), n(Ni-N) = 420 сm-1 (for 2, 3) are presented. This evidences about the presence of bipy or phen in the molecules of compounds. The absorption bands n(C=O) ~ 1708 сm-1, νas(СOО-) ~ 1671 сm-1, νs(СOО-) ~ 1448 сm-1 are specific for the vacant carboxylic and monodentate protonated carboxylate groups (Dn = νas(СOО-) – νs(СOО-) ~ 220 сm-1). The absorption bands ν(C-O) ~ 1130 сm-1 of the alcoholic group ν(Ge-O) ~ 778-725 сm-1 have been also detected in the IR-spectra of 1-3. The feature of heterometalic complexes 2, 3 is presence of deformation vibrations band of the bond Ge-O-Н ~ 855 сm-1. In the mass-spectra of anions 2 and 3 the formation of same fragmentation ions [Ge(OH)(HMal)]·H2O and [Ge(HMal)2] with m/z ~ 243 and 337. In the compounds 1-3 malic acid coordinates in the monoprotonated form, one hydroxyl and one carboxyl groups take part in the formation of bonds with Ge(IV) atom, the second carboxyl group stays vacant. In the complex 1 the octahedral coordination polyhedron of Ge is formed through the bidentate coordination of 2,2'-bipyridine (bipy). Complexes 2,3 are of cationanionic type with the electrostatic interaction between their cations and anions. In 2,3 Germanium has coordination number 5 and saturates its coordination sphere by binding to the OH-group, and as the result similar complex anion with the composition [Ge(OH)(HMal)2]- is formed. Cations [Ni(bipy/рhen)3]2+ are formed through the coordination three molecules of 2,2'-bipyridine (bipy), 1,10-phenanthroline (phen) by nickel atom.The mixed-ligand [Ge(HMal)2(bipy)]·bipy·2H2O (1) and mixed-ligand-heterometallic [Ni(phen)3][Ge(OH)(HMal)2]2·12H2O (2), [Ni(bipy)3][Ge(OH)(HMal)2]2·12H2O (3) germanium complexes with malic acid (H3Mal) and heterocyclic amines 2,2'-bipyridine (bipy), 1,10-phenanthroline (phen) were obtained for the first time. It was established that in the IR-spectra of 1-3 stretching vibrations of aromatic rings n(C-CАr) ~ 1598-1493 cm-1, ν(C-N) ~ 1315 cm-1, ν(C-N) ~ 1315сm-1, and also n(Ge-N) = 655 сm-1 (for 1), n(Ni-N) = 420 сm-1 (for 2, 3) are presented. This evidences about the presence of bipy or phen in the molecules of compounds. The absorption bands n(C=O) ~ 1708 сm-1, νas(СOО-) ~ 1671 сm-1, νs(СOО-) ~ 1448 сm-1 are specific for the vacant carboxylic and monodentate protonated carboxylate groups (Dn = νas(СOО-) – νs(СOО-) ~ 220 сm-1). The absorption bands ν(C-O) ~ 1130 сm-1 of the alcoholic group ν(Ge-O) ~ 778-725 сm-1 have been also detected in the IR-spectra of 1-3. The feature of heterometalic complexes 2, 3 is presence of deformation vibrations band of the bond Ge-O-Н ~ 855 сm-1. In the mass-spectra of anions 2 and 3 the formation of same fragmentation ions [Ge(OH)(HMal)]·H2O and [Ge(HMal)2] with m/z ~ 243 and 337. In the compounds 1-3 malic acid coordinates in the monoprotonated form, one hydroxyl and one carboxyl groups take part in the formation of bonds with Ge(IV) atom, the second carboxyl group stays vacant. In the complex 1 the octahedral coordination polyhedron of Ge is formed through the bidentate coordination of 2,2'-bipyridine (bipy). Complexes 2,3 are of cationanionic type with the electrostatic interaction between their cations and anions. In 2,3 Germanium has coordination number 5 and saturates its coordination sphere by binding to the OH-group, and as the result similar complex anion with the composition [Ge(OH)(HMal)2]- is formed. Cations [Ni(bipy/рhen)3]2+ are formed through the coordination three molecules of 2,2'-bipyridine (bipy), 1,10-phenanthroline (phen) by nickel atom.

A different-ligand complex of Germanium (IV) and Magnesium with 1-hydroxyethylidenediphosphonic acid (H4hedp) [Mg(H2O)6]3[Ge6(m-OH)6(m-hedp)6]∙20Н2О (I) was synthesized. Its composition and structure was established with the methods of elemental__is crystallohydrate, this is confirmed with the band n(Н2О) in the IR-spectrum at 3433 cm-1 and clear band d(Н2О)=1661 сm-1 of the coordinated water molecules. In the IR-spectra of I there are presented stretching vibration band of the bond Ge-O (589 сm-1) and deformation vibration band of Ge-О-Н (821 см-1), which means that Ge is in the hydrolyzed form. Hydroxyl group is a bridging ligand, this is confirmed with presence of the deformation vibration bands at 1010 сm-1. There also appear absorption bands at 1197, 1058 and 980 сm-1, which are typical for nas(PO3) and ns(PO3). This shows that only completely deprotonated phosphoric groups PO32- are presented in the compound I.On the thermogram I two low-temperature effects are presented at 70-110 °С and 110-170 °С. According to the temperature of elimination, 20 water molecules in the calculation for one formula unit are crystallization and 18 – are coordination. It was established, that application of this compound for the secondary tillage of the seeds of winter wheat promotes the increasing of its effective germination (75%), intensive increasing of the overland mass of the plant (17 cm) and primary root system (7.5 cm). These rates are much higher comparatively to the control and etalon – complex fertilizer Novalon. The application of new compound increases chances to obtain friendly and well-developed seedlings of wheat, that are able to ensure the frost resistance and receiving of high harvest. The obtained results indicate the perspective of future studies of the synthesized compound on the different plants with the aim of its implementation it in the planting practice as an effective simulator of growth.

Coordination compounds with complex cations of Co2+ with 1,10-phenanthroline, 2,2’-bipyridine and tetrameric xylaratogermanate anion were obtained. Their composition and structure were established by the methods of elemental analysis, IR-spectroscopy and thermogravimetric analysis. In the IR-spectrum of I, II bands of asymmetric υas(COO–) (~1686 cm-1) and symmetric υs(COO–) (~ 1442 cm-1) valence vibrations of carboxylate groups are presented. The presence of υ(C-O) (~ 1069 cm-1) band (alcoholic type) and d(C-OH) (~1144 cm-1) band, which is typical for the xylaric acid, indicates that not all hydroxyl groupsof the H5Xylar ligand are deprotonated. Absorption bands υ(Ge-O) (~737 cm-1), υas(GeOGe) (~851 cm-1) are also detected. They indicate the binding of germanium to xylaric acid and formation of the Ge-O-Ge bridge. The deformation vibration band of the Ge-О-Н (~821 cm-1) indicates the implementation of the hydrolyzed form of germanium. There also appear n(ОН)H2O, ns(C–Harom.), ν(C-Carom.), n(C-Narom.), δ(С-H) bands, that are typical for crystallization water molecules and 1,10-phenanthroline (I), 2,2’-bipyridine (II). The thermal destructions of the both compounds are similar. On the thermograms of both compounds one low-temperature effect is presented at 80-270 °С(for I) and 80-260 °С (for II) respectively. According to the temperature of elimination and the weight loss (8,75% for I and 14,5% for II), crystallization water molecules were calculated (I – 12, II – 20). Due to the mass loss along the thermogravimetric curve at 900 °C, the final products of thermal destruction is a mixture of CoO + GeO2. The molecular formulas of complexes I, II are proposed in the accordance of the results of elemental analysis, IR spectroscopy and thermogravimetric analysis: [Сo(phen)3]2[(OH)2Ge2(m-HXylar)4Ge2(m-OH)2]∙12Н2О (I), [Сo(bipy)3]2[(OH)2Ge2(m-HXylar)4Ge2(m-OH)2]∙20Н2О (II). Their scheme of structure were suggested.

The new coordination polymer silver bis(citrato)germanate was synthesized and exhibited pronounced antiviral activity against human influenza virus strains A/Hong Kong/1/68 (H3N2) and A/Puerto Rico/34 (H1N1). Its effective dose was five times lower than that of the reference drug oseltamivir, which made this compound promising for further studies in animal models.

Synthesis procedures have been developed for new supramolecular xylaratogermanate salts with different cations: (HPhen)4[(OH)2Ge2(µ-HXylar)4Ge2(µ-OH)2] · 13H2O (I), [Fe(Phen)3]2[(OH)2Ge2(µ-HXylar)4Ge2(µ-OH)2] · 6H2O · C2H5OH (II), [Ni(Phen)3]2[(OH)2Ge2(µ-HXylar)4Ge2(µ-OH)2] · 8H2O (III). The compounds have been studied by X-ray diffraction, IR spectroscopy, and thermogravimetry. Their molecular and crystal structure has been determined. Compounds I–III include the same tetrameric μ-dihydroxyxylaratogermanate anion [(OH)2Ge2(µ-HXylar)4Ge2(µ-OH)2]4– with ditopic ligand, in which one of three hydroxyl groups does not coordinate to germanium(IV) but forms intramolecular hydrogen bond.

A synthesis technique was developed and a new complex [Fe(рhen)3][Sn(HCit)2]∙2H2O (I) (phen is 1,10-phenanthroline and Н4Сit is citric acid) was obtained. Based on the data of elemental analysis, the molar ratio Sn: citrate: Fe: phen = 1:2:1:3 is realized in complex I. The presence of a vacant carboxyl group –COOH in molecule I is confirmed with the band in the IR-spectra ν(С=О) = 1708 сm–1. Unlike the IR-spectrum of citric acid, νas(СОО–), νs(СОО–), ν(С–О) bands of the alcoholate type in the region of 1083 сm–1 and stretching vibrations of the Sn – O bond appear in the IR-spectrum of I. The presence of the stretching vibrations in the range of 1300–1600 сm–1, 1000–1500 сm–1 and 700–1200 сm–1, which is specific for an aromatic molecules, confirms the presence of 1,10-phenanthroline in I. X-Ray analysis showed that I is a coordination compound of the cation-anionic type with the [Fe(phen)3]2+ as cation and the [Sn(HCit)2]2- as anion. The coordination polyhedron of Sn(IV) in the complex anion is a distorted octahedron formed by three pairs of oxygen atoms of two tridentate chelating ligands НCit3-. In cations, Fe atoms are coordinated by three phen molecules. In one of the cations, one phen molecule is disordered in two positions with the same occupation. This leads to the formation of two types of cation: A (without disordering of phen molecules) and B (with disordering of phen molecules). The coordination polyhedron of Fe(II) in both types is a distorted octahedron. Anions, cations, and also water molecules form alternating layers parallel to the crystallographic plane bc. Layers can be divided into three types: layers, which contain only anions and water molecules connected with intermolecular hydrogen bonds; and ones which contain only type A cations or only type B cations.