Showing papers in "Russian Journal of Coordination Chemistry in 2003"

Complexes of Copper in Unstable Oxidation States

Abstract: The review covers methods of synthesis, structures, and stabilities of copper(IV), copper(III), and copper(I) complexes with inorganic and organic ligands.

1 A 1 ⇄ 5 T 2 Spin Transition in New Thermochromic Iron(II) Complexes with 1,2,4-Triazole and 4-Amino-1,2,4-Triazole

Abstract: New complexes of iron(II) chloride and bromide with 1,2,4-triazole (Htrz) and 4-amino-1,2,4-tri-azole (NH2trz) of composition Fe(Htrz)3Cl2 · 1.5H2O, Fe(NH2trz)3Cl2 · 2H2O, Fe(Htrz)3Br2 · 2H2O, and the Fe(NH2trz)3SO4 · H2O complex were synthesized and studied by magnetochemical, electronic, IR and Mossbauer spectroscopy methods. Magnetochemical studies showed that these complexes exhibit 1 A 1 ⇄ 5 T 2 spin transition accompanied by thermochromism (a reversible pink ⇄ white change of color).

Solid-Phase Solvate-Free Formation of Magnesium Hydroaluminates Mg(AlH4)2and MgAlH5upon Mechanochemical Activation or Heating of Magnesium Hydride and Aluminum Chloride Mixtures

Abstract: It is shown that vibromechanically activated or heated magnesium hydride is capable of solid-phase interacting with aluminum chloride to form magnesium tetra- and pentahydroaluminates (Mg(AlH4)2and MgAlH5). When heated above 100°C, Mg(AlH4)2undergoes thermolysis (or mechanolysis upon mechanical activation) to form MgAlH5and AlH3. The latter liberates aluminum and hydrogen in the moment of isolation. In the 230 to 280°C interval, MgAlH5also loses reactive AlH3⊙. On further heating, the obtained active aluminum and MgH2give intermetallide Al2Mg. The ability of Mg(AlH4)2to transform into MgAlH5by the addition of excessive activated MgH2, as in the case of Sr(AlH4)2, is revealed.

Prediction of Stability Constants for Cr(III) and Cr(II) Complexes

Abstract: Regression analysis was used to derive equations for estimaing thermodynamic stability constants for complexes of Cr2+ (logβ° 1[Cr2+L] = 0.53logβ° n [H n L]) and Cr3+ (logβ° 1[Cr3+L] = 0.88logβ° n [H n L]) from the known protonation constants of H n L ligands and for determining stability constants of Cr2+ and Cr3+ complexes from the available stability constants of Cu2+ complexes (logβ° 1[Cr2+L] = 0.76logβ° 1[Cu2+L] and logβ° 1[Cr2+L] = 0.60logβ° 1[Cr3+L], respectively). Parameters of the Panteleon–Ecka equation for calculating stability constants of Cr2+ complexes (λ = 0.57) and Cr3+ complexes (λ = 0.69) with two and three bidentate ligands were also determined. The ratio of logarithmic stability constants for complexes with the same metals but with different metal ionic charges was found to be approximately equal to the ratio of charges on the central ions. The stability constant of Cr(II) sulfate complex was calculated.

Orthophosphoric Acid-;N,N-Dimethylformamide System: IR Study

Abstract: Interactions in the orthophosphoric acid (H3PO4)-;N,N-dimethylformamide (DMF) system are studied by IR Fourier spectroscopy. A mechanism of interaction between the H3PO4 and DMF molecules was proposed on the basis of the results and the earlier reported viscosimetry data for this system.

Structural Features of Triorganylantimony Dicarboxylates R3Sb[OC(O)R′)]2

Abstract: Triphenylantimony dibenzoate Ph3Sb(O2CPh)2, triphenylantimony bis(methylbenzoates) Ph3Sb(O2CC6H4Me-n)2 (n = 2, 4), and tri-p-tolylantimony bis(trichloacetate) p-Tol3Sb(O2CCCl3)2, whose Sb atoms have trigonal bipyramidal coordination, were studied using X-ray diffraction analysis. The Sb–O bond lengths are equal to 2.119(2) and 2.144(2); 2.115(2); 2.118(2) and 2.127(2); 2.133(2) A, the Sb···O(=C) intramolecular contacts are equal to 2.797(2) and 2.698(2); 2.845(2); 2.814(2) and 3.030(2); 3.119(2) A, respectively. The following correlation was found in the structures of triorganylantimony dicarboxylates: the shorter the Sb···O(=C) distances, the greater the equatorial angle on the side of the intramolecular contacts.

Ru(II) Chloro-Bis(bipyridyl) Complexes with Substituted Pyridine Ligands: Interpretation of Their Electronic Absorption Spectra

Abstract: A number of complexes were synthesized with the general formula cis-[Ru(Bipy)2(L)(Cl)](BF4), where Bipy is 2,2"-bipyridine, L is pyridyne (Py), 4-aminopyridine (4-NH2py), 4-picoline (4-Mepy), nicotin-amide (3-CONH2py), isonicotinamide (4-CONH2py), 3- and 4-cyanopyridine (3-CNpy, 4-CNpy), 4,4"-bipyridine (4,4"-Bipy), trans-1,2-bis(4-pyridyl)ethylene (Bpe), 4,4"-azopyridine (Azpy), pyrazine (Pyz), imidazole (Imid), and NH3. The semiempirical CINDO-CI method was used to calculate the energies and intensities of transitions in the electronic absorption spectra. The differences observed in the spectra of these compounds are mainly due to the positions of the charge-transfer transitions d π(Ru) → π*(L). Depending on the positions of these transitions, ligands L can be divided into three groups: 1) transitions Ru → L lie in the region of the first long-wavelength band d π(Ru) → π*(Bipy) (L = Azpy, Pyz); 2) transitions Ru → L lie between the first and second bands due to the charge transfer to Bipy (L = 3-CONH2py, 4-CONH2py, 4,4"-Bipy, Bpe, 4-CNpy), and 3) transitions Ru → L lie in the region of the second band d π(Ru) → π*(Bipy) (L = Py, 4-Mepy, 3-CNPy, 4-NH2py, Imid).

Kinetics of the Dissociation of Transition Metal Complexes with α,α-Dipyrrolylmethene in Acetic Acid–Benzene as a Binary Proton-Donating Solvent

Abstract: The kinetics of the dissociation of Co(II), Ni(II), and Zn(II) complexes with 4,4′-dibutyl-3,3′,5,5′-tetramethyldipyrrol-2,2′-ylmethene was studied in acetic acid–benzene as a binary proton-donating solvent. The metal nature was found to affect the kinetic parameters of the process. Assumptions were made about the limiting step of the process and the effectiveness of d metal ions in the template synthesis of porphyrins from dipyrrolylmethenes.

Binuclear Cadmium Dithiophosphate Crystals: 13C, 31P, and 113Cd CP/MAS NMR Studies

Abstract: Binuclear diisopropyl and dicyclohexyl dithiophosphate cadmium complexes, namely, [Cd2{S2P(OR)2}4], were studied by high-resolution heteronuclear (13C, 31P, and 113Cd) NMR spectroscopy in the solid state in a temperature range from 295 to 378 K. 31P NMR signals for the terminal and bridging ligands of the complexes were differentiated. The experimental NMR spectra show 31Р–111,113Cd and 113Cd–31Р spin–spin couplings only for the terminal ligands. The chemical shift anisotropy δaniso and the asymmetry parameter η were calculated for 31P and 113Cd NMR signals. It was found that the 31P chemical shifts for the terminal and bridging dithiophosphato groups differ in anisotropy character.

Synthesis of 4-Dicyclohexylaminomethyl Antipyrine and Its Metal Complexes: Spectral Characterization and Evaluation of Thermodynamic Parameters

Abstract: Complexes of Fe(III), Co(II), Ni(II), and Cu(II) with 4-dicyclohexylaminomethyl antipyrine (DCHAMA, L) were prepared and characterized by elemental and chemical analyses, IR, electronic absorption, 1H NMR and EPR spectroscopies, thermal analysis, and magnetic susceptibility measurements. The stoichiometry of the complexes was found to be MLX2 , MLX3 , or MLX2(H2O)2 where X = Cl or NO3. The ligand exhibits a bidentate mode of coordination. Thermal analysis of the chloro complexes shows a three stage decomposition pattern for the Cu(II) complex and a two stage decomposition pattern for Fe(III) and Co(II) complexes to yield the respective metal oxides as the end product. Kinetic and thermodynamic parameters such as n, Ea, ΔH#, ΔS#, and ΔG# were calculated using Coats–Redfern and Madhusudhanan–Krishnan–Ninan integral methods. The coordination number of the metal atom is found to influence the thermal stability of the complexes. The antimicrobial screening shows that the four-coordinated complexes are more active than the five- and six-coordinated ones and DCHAMA.

Crystal Structure of the Mixed-Valence Neptunium Compound Na6[(NpVO2)2(NpVIO2)(MoO4)5] · 13H2O

Abstract: The crystal structure of the mixed-valence Np(V) and Np(VI) compound Na6[(NpVO2)2(NpVIO2)(MoO4)5] · 13H2O was determined. The structure is built of the anionic layers [(NpVO2)2(NpVIO2)(MoO4)5] 6n- n with the Na+ cations and crystal water molecules between them. The Np(V) and Np(VI) atoms in the anionic layers are ordered. The motif of the anionic layer is close to that found in Mg2[(UO2)3(SeO4)5] · 16H2O. The isostructural mixed-valence Np(V) and U(VI) compound was also synthesized.

Triarylantimony Dicaroxylates Ar3Sb[OC(O)R]2 (Ar = Ph, p-Tol; R = 2-C4H3O, 3-C5H4N): Synthesis and Structure

Abstract: Bis(2-furoinate)triphenyl- and tri-p-tolylantimony and bis(3-niacinate)triphenylanitmony were synthesized by reacting triarylantimony (Ar3Sb; Ar = Ph, p-Tol) with 2-furancarboxylic and 3-pyridinecarboxylic acids in the presence of hydrogen peroxide. According to X-ray diffraction data, Sb atoms have trigonal bipyramidal coordination polyhedra. The Sb–O distances are 2.117(4), 2.137(4) A; 2.136(2), 2.158(2) A, and 2.112(1), 2.101(2) A, the Sb···O distances are 2.866(4), 2.798(4) A; 2.816(2), 2.774(2) A, and 3.054(2), 3.168(2) A, respectively.

Phenylation of Antimony(V) Organic Compounds with Pentaphenylantimony. The Structure of Tetraphenylantimony Chloride

Abstract: Tetraphenylantimony chloride and bromide were synthesized through the reaction of pentaphenylantimony with diphenylantimony trichloride or tribromide taken at a molar ratio of 2 : 1 in toluene. When the initial compounds were taken at a molar ratio of 1 : 1, triphenylantimony dichloride or dibromide was formed. The phenylation of triphenylantimony sulfate with pentaphenylantimony yielded tetraphenylantimony sulfate. According to the X-ray diffraction data, the antimony atom in the tetraphenylantimony chloride molecule has a distorted trigonal bipyramidal configuration with the chlorine atom in the axial position. The Sb–Cl distance is equal to 2.686(1) and Sb–C distances are equal to 2.113(4) and 2.165(4) A (av. 2.130 A).

Neptunium(VI) Chromate Complex with 1,2-Diammoniopropane {H3NCH2CH(NH3)CH3}[(NpO2)2(CrO4)3(H2O)] · 3H2O: Synthesis, Crystal Structure and Properties

Abstract: New neptunium(VI) complex {H3NCH2CH(NH3)CH3}[(NpO2)2(CrO4)3(H2O)] · 3H2O is synthesized; its crystal structure is determined and IR and near-IR absorption spectra are recorded. The crystallographic data are: a = 10.805(2) A, b = 11.238(2) A, c = 17.615(8) A, space group P212121, Z = 4, V = 2139(1) A3, R = 0.051, wR(F 2) = 0.109. The crystal structure of the compound is built of the anionic layers of [(NpO2)2(CrO4)3(H2O)]2n– n . The {H3NCH2CH(NH3)CH3}2+ cations and crystallization water molecules are arranged between the layers. Coordination polyhedron of two crystallographically independent Np atoms has the shape of a pentagonal bipyramid. The equatorial plane in one Np polyhedron is formed by the oxygen atoms of four chromate ions and water molecule and by the oxygen atoms of five chromate ions in the other one.

Synthesis and Crystal Structure of Supramolecular Adducts of Macrocyclic Cavitand Cucurbituril with Chromium(III) and Nickel(II) Aqua Complexes

Abstract: Supramolecular compounds {[Cr(H2O)6](C36H36N24O12)}(NO3)3 · 13H2O (I) and {[Ni(H2O)6]2(C36H36N24O12)}(SO4)2 · 16H2O (II) were obtained from aqueous solutions of chromium nitrate or nickel sulfate and the macrocyclic cavitand cucurbituril. According to X-ray diffraction analysis data, the cucurbituril molecule is closed from both sides by metal aqua complexes due to the formation of hydrogen bonding between the cucurbituril CO groups and aqua ligands. Compound I has a chain structure, while the structure of compound II is layered. Modes of cucurbituril coordination, depending on the size and charge of the metal cation, are discussed.

Coordination Numbers of Central Atoms in Coordination Compounds

Abstract: A sample of structurally characterized 10000 complexes (X-ray diffraction data) was carefully selected from available databases for analysis of coordination numbers (CNs) of their central atoms (complexing agents). The coordination numbers of various chemical elements are tabulated for their different oxidation numbers (ONs). Variations in CN with the ordinal number of an element in the Periodic Table were followed. A general distribution of the sample complexes over the CNs of the central atom, as well as their distributions for particular ONs, is displayed. References to particular coordination compounds are given for extreme and very uncommon CNs of a central atom with different ONs. A general pattern of the observed variations in the CN of chemical elements can be useful for predicting the properties of complexes, constructing their stability models, designing compounds with rich and unique properties, and developing retrieval and graphic tools for chemical databases.

Mono- and Binuclear Copper(II) Metal Chelates with 3,5-Di(tert-butyl)salicylaldehyde Acylhydrazones

Abstract: Some new mono- and binuclear complexes of copper(II) acetate, nitrate, and perchlorate with acylhydrazones of substituted salicylaldehyde derivatives containing bulky tert-butyl substituents are synthesized. The structure and properties of the complexes isolated are shown to be determined by both the structural features of the ligand systems and by the nature of the acido ligands. The exchange parameters 2J ranging from –108 to –125 cm–1 are calculated for the binuclear copper(II) metal chelates.

Reaction of Plutonium(VI) with Orthosilicic Acid Si(OH)4

Abstract: Reaction of Pu(VI) with Si(OH)4 (at concentration 0.004–0.025 mol l–1) in a 0.2 M NaClO4 solution at pH 3–8 is studied by spectrophotometric method. In the range of pH 4.5–5.5, PuO2(H2O)4OSi(OH)3+ complex is formed, while at pH > 6, PuO2(H2O)3O2Si(OH)2 or hydroxosilicate complex PuO2(H2O)3(OH)OSi(OH)3 is recorded. The equilibrium constants are calculated for the reactions of formation of PuO2(H2O)4OSi(OH)3+ and PuO2(H2O)3O2Si(OH)2 and their concentration stability constants: log K1 = –3.91 ± 0.17 and log K2≈ –10.5; log β1= 5.90 ± 0.17 and log β2≈ 12.6. The PuO2(H2O)4OSi(OH)3+ complex is significantly less stable than analogous complex of U(VI). Calculations of the forms of Pu(VI) occurrence at the Si(OH)4 concentration equal to 0.002 mol l–1 showed that the maximum fraction of the PuO2(H2O)4OSi(OH)3+ complex is ∼10% (pH 6.5), while the fraction of PuO2(H2O)3O2Si(OH)2 is almost 40% (pH 8).

Synthesis, Structure, and Properties of Nickel(II) and Cobalt(II) Coordination Compounds with Optically Active Diaminodioxime (H2L) Derived from 3-Carene. Molecular and Crystal Structures of the [Ni(H2L)(NO3)]NO3 and [Ni(HL)]ClO4 · H2O Complexes

Abstract: Nickel(II) and cobalt(II) complexes with optically active diaminodioxime (H2L, the derivative of 3-carene) of the compositions [Ni(H2L)NO3]NO3 (I), Ni(H2L)Cl2 (II), [Ni(HL)]ClO4 · H2O (III), and Co(H2L)Cl2 (IV), were synthesized. According to X-ray diffraction data, the structures of the paramagnetic compound I and diamagnetic complex III are ionic. In the cation of I, the distorted NiN4O2 octahedron is formed by the N atoms of the tetradentate cyclic ligand (H2L molecule) and by the O atoms of NO3–; anion functioning as bidentate cyclic ligands. In the cation of III, the NiN4 coordination unit is a distorted square formed upon coordination of the tetradentate cyclic ligand, HL–; anion. The data of magnetochemistry and UV-Vis, IR, and Raman spectroscopy suggest that paramagnetic complexes II and IV contain a distorted octahedral polyhedron MCl2N4 (M = Ni, Co).

Ruthenium(IV) and Osmium(II) Tetraphenylporphine Complexes: Synthesis and Oxidation Reactions

Abstract: The Ru(IV) and Os(II) complexes (PhO)2RuTPP and OsTPP were synthesized from tetraphenylporphine (H2TPP) and K2RuO4 or K2OsO4 (taken in the molar ratio of 1 : 30) in boiling phenol. The kinetics of oxidation reactions of these complexes in solutions of HOAc (acetic), H2SO4, and HOAc–H2SO4 acids was studied. It was found that in the aerated HOAc–H2SO4 mixture heated above 340 K, these complexes are oxidized with participation of different reaction sites: the Ru(IV) complex is oxidized at macrocycle to give the π-radical-cation (PhO)2RuТPP•+, while in the Os(II) complex, the metal atom is oxidized to form the Os(III) complex. In the first case, the reaction follows the activation mechanism, whereas in the second case, the activation energy of the reaction is zero.

Metal Isotrithionedithiolates as Synthetic Metals

Abstract: Isotrithionedithiolate complexes Ct n [M(Dmit)2] (Ct = Li, Na, K, Rb, Cs; M = Mn, Fe, Co, Cu, Hg; Dmit2–= isotrithionedithiolate ion; n= 2 for nonoxidized complexes and n≤ 1 for complexes oxidized with excess iodine) were synthesized for the first time by a peculiar method. IR data revealed that the structure and electronic configuration of the complexes are determined by the nature of the outer-sphere cation, the central atom, and by the oxidation number. Experimental data and quantum-chemical calculations (SW Xαin the relativistic approximation) suggest that isotrithionedithiolatoferrates and -cobaltates can be used to produce new synthetic metals. It was shown for the first time that, unlike the known zincates and cadmiates, isotrithionedithiolatomercurates are oxidized without decomposition to give Ct[Hg(Dmit)2] complexes.

Complexation of N-Allyl Derivatives of Morpholinium with Copper(I) Halides: Synthesis and Crystal Structure of [C4H8ON(C3H5)2]+[Cu4Cl5]–, [C4H8ONH(C3H5)]+[CuBr2]–, and [C4H8ONH(C3H5)]+[CuBr1.41Cl0.59]–

Abstract: The compounds [C4H8ON(C3H5)2]+[Cu4Cl5]– (I), [C4H8ONH(C3H5)]+[CuBr2]– (II), and [C4H8ONH(C3H5)]+[CuBr1.41Cl0.59]– (III) were prepared for the first time by ac electrochemical synthesis from mono- and di-N-allyl derivatives of morpholinium and copper(I) halides in ethanol solution and structurally characterized. In the structure of I π-complex, the centrosymmetric Cu8Cl10 fragments are associated into layers perpendicular to the b axis. The N,N"-diallylmorpholinium cation functions as a bridge, which coordinates two copper atom of the adjacent inorganic fragments by both allyl groups. The trigonal-pyramidal surrounding of the Cu(I) atom, as well as the distorted tetrahedral coordination sphere of Cu(2), involves three chlorine atoms and the C=C bond, whereas the planar trigonal surrounding of the Cu(3) atom and trigonal-pyramidal surrounding of the Cu(4) atom involve only chlorine atoms. In the isostructural II and III σ-complexes, the edge-shared CuX4 tetrahedra form the infinite copper-halide chains running along the a axis. The inorganic fragments and organic N-allylmorpholinium cations are united into the three-dimensional crystal structures by N–H···X and C–H···X (X = Cl, Br) hydrogen bonds.

Reactions of Aluminium Tribromide with Tetrakis(triphenylphosphine)nickel(0) and Tetrakis(triethylphosphite)nickel(0) Complexes

Abstract: Reactions of aluminium tribromide with the Ni(0) phosphine and phosphite complexes are studied by EPR method. AlBr3was found to cause the oxidation of the transition metal in the (PPh3)4Ni complex to the univalent state with the formation of the tetracoordinated (PPh3)3NiBr complex. With an excess of AlBr3, the phosphine ligands are eliminated from the coordination sphere of Ni(I), and the coordinatively unsaturated complexes are destroyed to give the colloidal nickel. In the reaction of (P(OEt)3)4Ni with AlBr3, Ni(0) is also oxidized to Ni(I), but the acido ligand is not eliminated even with a 15-fold excess of the Lewis acid. The activity of catalytic systems on the basis of the Ni(0) phosphine complexes and the Lewis acids in the low-molecular oligomerization reactions of olefines is determined by the cationic coordinatively unsaturated Ni(I) complexes formed in these systems.

Synthesis and Structure of μ-Peroxo-bis(4-bromophenoxotri-p-tolylantimony)

Abstract: μ-Peroxo-bis(4-bromophenoxotri-p-tolylantimony) was synthesized by reacting 4-bromophenol with tri-p-tolylstibine in the presence of hydrogen peroxide. According to X-ray diffraction data, the Sb atoms have trigonal bipyramidal coordination. In the centrosymmetric molecule, the two Sb atoms are joined via bridging peroxo group disordered over two sites. The Sb–O(1,2') bond lengths are equal to 1.999(6) and 2.03(1) A, the Sb···O(2,1') distances are equal to 2.605(9) and 2.626(5) A, respectively. The lengths of the terminal Sb–O(3) bonds are 2.093(3) A.

Cubane Chalcogenide Complexes of Group IV–VI Metals: Synthesis, Structure, and Properties

Abstract: This paper generalizes data on the methods of synthesizing the cubane chalcogenide complexes of group IV–VI transition metals. The regularities of their structures, the physicochemical properties and reactivities (reactions of the ligand substitution and redox transformations) are discussed in detail.

Stability Constants of Cu(II) Hydroxypropylenediaminetetraacetates

Abstract: Equilibrium of complexation between 2-hydroxypropylene-1,3-diamine-N,N,N′,N′-tetraethanoic acid (H4L) and Сu2+ ions was studied by potentiometric and spectrophotometric methods. Stability constants of CuL2– and CuHL– complexes were determined at 298.15 K and I = 0.5 М (KNO3).

Crystal and Molecular Structures of 3-Carboxypropyltriphenylphosphonium Diiodobromide

Abstract: Complexation in the 3-carboxypropyltriphenylphosphonium bromide–molecular iodine system in chloroform was studied. The maximum number of iodine molecules coordinated by 3-carboxypropyltriphenylphosphonium bromide was established by the spectrophotometric method using a function of the average-iodine number, and the stability constant of the complex was determined. The [(C6H5)3P(CH2)3COOH]BrI2 diiodobromide was studied by X-ray diffraction analysis. The characteristic feature of the crystalline salt was the formation of dimer associates: anionic associates were formed due to the Br···Br intermolecular interactions and cationic associates were formed due to the O···H–O hydrogen bonds. The data obtained were correlated to the results of quantum-chemical calculations.

Tetranuclear Bismuth Complex Bi 4 (O) 2 (O 2 CC 6 H 2 F 3 -3,4,5,) 8 · 2η 6 -C 6 H 5 Me: Synthesis and Structure

Abstract: Tetranuclear organobismuth complex Bi4(O)2(O2CC6H2F3-3,4,5)8 · 2η6-С6Н5Me with four bismuth atoms joined via the bridging carboxylate ligands and oxygen atoms was studied using X-ray diffraction analysis. The coordination sphere of either of the two terminal bismuth atoms contains the chelate carboxylate ligand and the toluene molecule. For the bridging tricoordinated oxygen atoms, the Bi–O distances are 2.083(2), 2.119(2), and 2.276(2) A. The average distance between the bismuth atom and the center of toluene molecule is equal to 3.131 A.

Crystal Structure of (2.2.2-Cryptand)lithium Perchlorate

Abstract: (2.2.2-Cryptand)lithium perchlorate [Li(2.2.2-Crypt)]+ClO– 4 (I) is prepared and characterized by X-ray structural analysis. Structure I (space group P21212, a = 10.149 A, b = 13.475 A, c = 8.580 A, Z = 2) is solved by the direct method and refined anisotropically by the full-matrix least-squares method to R = 0.056 for 2312 reflections (CAD4 automated diffractometer, λMoK α). Crystal of complex I is built of [Li(2.2.2-Crypt)]+ complex cations of the host–guest type and randomly disordered ClO– 4 anions. Both ions are located on the twofold crystallographic axes. The Li+ cation, which is also randomly disordered about the 2 axis, is coordinated by the N atom and five O atoms from eight heteroatoms (2N + 6O) of the cryptand. Two Li–O and one Li–N bonds are noticeably elongated. The Li+ cation forms irregular six-vertex coordination polyhedron.

Rhodium(III) and Iridium(III) Complexes with Octaphenyltetraazaporphine: Synthesis and Study of Their Acid Forms in Proton-Donor Media

Abstract: The Rh(III) and Ir(III) complexes with octaphenyltetraazaporphine (X)MOPTAP (M = Rh, X = HSO4, OH; M = Ir, X = HSO4) are synthesized and their specific acid–base interactions in the CF3COOH–CH2Cl2 and H2SO4–CH3COOH systems are studied. The quantitative characteristics of equilibria between the acid and basic forms are obtained. The stability constants рK 1 of the first acid forms, in which one of the meso-N atom is protonated, for hydrosulfate (HSO4)MOPTAP complexes in the H2SO4–CH3COOH mixture are equal to –0.54 (Rh) and 0.0057 (Ir). The Ir complexes have more basic meso-N atoms due to more strong π-backbonding effect of coordination and, therefore, the second protonation stage (рK 2 = –4.25) could be also observed. In the CF3COOH–CH2Cl2 mixture, the basic properties of the meso-N atoms are levelled out. For (HSO4)RhOPTAP рK 1 = 1.35, while for (HSO4)IrOPTAP рK 1 = 1.24 and рK 2 = 0.45.