Cyclic bis(β-diketonate)- and bis(β-ketoesterate)-bridged titanium and zirconium alkoxide derivatives

Reaction of Ti(OiPr)(4) with various bis(β-diketones) and bis(β-ketoesters) (LH(2)) results in the formation of dimeric complexes [Ti(OiPr)(2)L](2), where each metal centre is coordinated by two terminal OiPr ligands and two bridging β-diketonate or β-ketoesterate groups (L). Macrocycles containing two M(OiPr)(2) moieties are thus formed. Reaction of Zr(OiPr)(4) with the same bis(β-diketones) and bis(β-ketoesters) results in different compounds, depending on the organic spacer connecting the two functional groups. With shorter spacers, the compounds [ZrL(OiPr)(2)](2)·2iPrOH are obtained, with the same structures as the corresponding titanium complexes. With longer spacers, however, complexes with a higher degree of substitution are formed, such as (ZrL(2))(2) and Zr(2)L(3)(OiPr)(2)·2iPrOH. The molecular weight and structure of all compounds was elucidated by ESI-MS. MS/MS of the corresponding [M+Na](+) precursor ions confirmed the proposed structures based on structure-specific product ions. Solution NMR experiments and DFT calculations additionally supported the proposed structures.     

Crystal structure of bis(α,α′-dithio-bis(formamidinium)) bis(μ2-chloro)hexachlorodimercurate(II)

The crystal and molecular structure of bis(α,α′-dithio-bis(formamidinium)) bis(μ₂-chloro)hexachlorodimercurate(II) C₄H₁₆Hg₂Cl₈N₈S₄ (I), where α,α′-dithio-bis(formamidine) is C₂H₆N₄S₂, was solved. Crystals are monoclinic, a = 8.6417(6) Å, b = 14.648(1) Å, c = 10.2111(8) Å, β = 104.949(1)°, V = 1248.8(2) ų, space group P2₁/n, Z = 4. The crystal structure is built of HgCl ₄ ^2? ions linked via inversion centers into [Hg₂Cl₈]^4? pairs and C₂H₈N₄S ₂ ²⁺ cations. [Hg₂Cl₈]^4? anions and C₂H₈N₄S ₂ ²⁺ cations form alternating layers linked by N-H…Cl hydrogen bonds into a framework structure.     

Bis(1,8-naphthylimides) and bis(1′,8′-naphthoylene-1,2-benzimidazoles) based on new bis(naphthalic anhydrides)

The reaction of bis(naphthalic anhydrides) with aniline and o-phenylenediamine under conditions of hightemperature cyclocondensation in m-cresol in the presence of a catalyst (benzoic acid) gives bis(1,8-naphthylimides) and bis(1,8-naphthoylene-1,2-benzimidazoles) which model the elementary units of polyimides and polynaphthoylenebenzimidazoles, respectively.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 649–652, May, 1991.     

Synthesis and crystal structures of bis(cyclopentyl)gallium phenoxide dimer and bis (cyclopentyl) gallium naphthoxide dimer

Tricyclopentylgallium reacted with phenol, naphthol respectively to yield phenox-ide (or naphthoxide) of biscyclopentylgallium which have been characterized by elemental analysis, IR, 1H NMR and mass spectrometry. X-ray diffraction analysis of compound 1 indicated that it belongs to the monoclinic system, space groups P21/c, with cell constants 0=9.602(3), 6=14.365(7), c=11.256(4)A, and β=97.54(3)°, Z=2(dimers), R=0.0706. Compound 2 assigned to the triclinic system, space groups P1 with cell constants a=9.392(4), 6=9.928(7), c=11.263(7) A, a=112.48(5), β=104.74(4), γ=99.95(5)°, and Z=l(dimers), R=0.0526. The molecule of 1 or 2 contains an oxygen-bridged coplanar Ga2O2 four-membered ring respectively.     

Synthesis and crystal structure of bis[(18-crown-6)potassium] bis(μ2-bromo)tetrabromodicopper(II)

A new complex bis[(18-crown-6)potassium] bis(μ₂-bromo)tetrabromodicopper(II), [{K(18-crown-6)}₂Cu₂Br₆] (I), is synthesized and studied by X-ray diffraction analysis (space group P2₁/n, a = 9.137 Å, b = 34.860 Å, c = 13.414 Å, β = 99.53°, Z = 4). The structure is solved by a direct method and refined by the fullmatrix least-squares method in the anisotropic approximation to R = 0.083 for 5850 independent reflections (CAD-4 automated diffractometer, λMoK _α radiation). Complex molecule I consists of the central binuclear anion [Cu₂Br₆]^2? and two peripheral cations K(18-crown-6)]⁺ of the host-guest type bound to the [Cu₂Br₆]^2? anion through two and one K-Br coordination bonds. In the [Cu₂Br₆]^2? anion, the coordination polyhedra of two Cu atoms can be described as strongly flattened tetrahedra. In two [K(18-crown-6)]⁺ fragments, the coordination polyhedra of their K⁺ cations (coordination numbers 8 and 7) are distorted hexagonal pyramids with a base of six O atoms of the 18-crown-6 ligand and a bifurcated or ordinary vertex: the Br atoms of the [Cu₂Br₆]^2? anion. Two 18-crown-6 ligands have a standard crown conformation.     

EPR on bis(1,2-dithiosquarato)cuprate(II) in the bis(1,2-dithiosquarato)nickelate(II) host lattice — structure and spectroscopy‡

EPR spectroscopy is a well suited analytical tool to monitor the electronic situation around paramagnetic metal centres as copper(II) and therefore the structural influences on the paramagnetic ion. 1,2-Dithiosquaratometalates are available by direct synthesis from metal salts with dipotassium-1,2-dithiosquarate and the appropriate counter cations. Synthesis and characterisation of bis(benzyltributylammonium)1,2-dithiosquaratonickelate(II), (BzlBu₃N)₂[Ni(dtsq)₂], and bis(benzyltributylammonium)1,2-dithiosquaratocuprate(II), (BzlBu₃N)₂[Cu(dtsq)₂], with benzyltributylammonium as the counter ion is reported and the X-ray structures of two complexes, (BzlBu₃N)₂[Ni(dtsq)₂] and (BzlBu₃N)₂[Cu(dtsq)₂], are presented. Both complexes, crystallising in the monoclinic space group P2₁/c, are isostructural with only small differences in the coordination sphere due to the different metal ions. The diamagnetic nickel complex is therefore well suited as a host lattice for the paramagnetic Cu(II) complex to measure EPR for additional structural information.     

Unusual supramolecular donor—acceptor complexes of bis(crown)stilbenes and bis(crown)azobenzene with viologen analogs

The results of the comprehensive study of novel supramolecular donor-acceptor complexes of bis(crown)stilbenes and bis(crown)azobenzene with viologen analogs are generalized. The original methodology for self-assembling of the organic donor-acceptor complexes possessing a very high thermodynamic stability is described. The hydrogen bonds between the peripheral fragments of the donor and acceptor play the key role in the self-assembling. The influence of different structural factors on the thermodynamic stability of the supramolecular donor-acceptor complexes and the efficiency of charge-transfer interactions between the donor and acceptor are discussed. The driving forces of the reaction leading to exotic trimolecular charge-transfer complexes are considered. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 779–787, April, 2008.     

Reactions of bis(cyclopentadienyl)titanium(IV) and zirconium(IV) chlorides with 1,1′-diacetylferrocenyl bis(hydrazones). Formation of trimetallic derivatives

Bis(cyclopentadienyl)titanium(IV) and zirconium(IV) chlorides react with bis(hydrazones) derived from 1,1-diacetylferrocene in anhydrous THF in the presence of base to give complexes of the type [(Cp₂MCl)₂L] [M = Ti or Zr; LH₂ = ferrocenyl bis(hydrazones)]. Tentative structures are proposed for these complexes based upon elemental analyses, electrical conductance, magnetic moment and spectroscopic data.     

Kinetic study on the ligand exchange reactions between bis(alkylxanthato)palladium(II)and bis(N,N-dialkyldithiocarbamato)palladium(II)by high-performance liquid chromatography

The rate constants and equilibrium constants of ligand exchange reactions between his(alkylxanthato)palladium(Ⅱ),Pd(S_2COR)_2(R=Am,n-Hex,Bz),and bis(N,N-dialkyldithiocarbamato)palladium(Ⅱ),Pd(S_2CNR_2)_2(K=Et,n-Pr,n-Bu),in chloroform solution have been determined ina temperature range of 20—50°C by means of high-performance liquid chromatography.It was foundthat both the forward and reverse reactions are of second order.All of the equilibrium constants Kdetermined are 10.3±1.0,much greater than the value(K=4)calculated statistically which indicatesthat the ternary complexes are more stable than the binary complexes.The experimental resultsrevealed that the reaction rate decreases with the increase in the size of R and R~1 groups and the latterare more remarkable,consistent with the deduction of steric effect.The activation parameters ofthe reactions have been calculated.In reaction series(11)and(12)(in the text)the isokinetic tempera-tures B=390±8K and β=346±15 K have been observed respectively.A plausiblemechanism in-volving an eight-membered ring intermediate has been proposed on the basis of experimental results.     

Synthesis and characterisation of a novel polymeric Cd complex,catena-(μ-thio)[bis(N-phenylthiourea] bis(dimethylsulphoxide)dichlorocadmium(II)

A new Cd(II) complex, [CdL(DMSO)₂Cl₂] _n , L?=?bis(N-phenylthiourea), has been synthesized and its crystal structure determined from single-crystal diffraction data. The compound is orthorhombic, space group Pna2₁, with a?=?18.728(1), b?=?12.2601(8), c?=?22.879(1)?Å, V?=?5253.3(6)?ų. L acts as an exobidentate neutral ligand and Cd is octahedral, being bonded to two S atoms, two terminal Cl ions and two DMSO solvent molecules. The structure is that of a one-dimensional polymer, with chains running parallel to the b axis. Polymeric chains are stabilized by N–H…Cl hydrogen bonding, while intermolecular S…O contacts connect the chains. Thermal decomposition of the complex starts at 120°C by desolvation and is continuous over the recorded temperature range.     

Crystal structure of bis[Ba(Aet)(OH2)5]bis(Aet)·4H2O

An X-ray crystallographic study is conducted of single crystals with the composition [Ba₂(Aet^?)₂·10(H₂O)]²⁺·2(Aet^?)·4H₂O, where Aet^? = (C₁₀H₁₁N₄O₂S₂)^? is the ethazole (2-(para-aminobenzenesulfamido)-5-ethyl-1,3,4-tiadiazole) anion. The crystals are monoclinic; the space group is P2₁/c, Z = 2; a = 9.793(2) Å, b = 15.408(4) Å, and c = 22.553(6) Å; β = 94.98(2)°; and R = 0.047. The independent part of the compound’s structural formula, [Ba(Aet)(OH₂)₅](Aet)·2H₂O, is isostructural with the analogous compound with the Sr atom. The ethazole anion is coordinated to the complexing metal atom by oxygen and nitrogen atoms to form a four-membered ring.     

Preparation and reaction of bis (perfluoroalkanesulfonyl) methyl halides

Halogenation of the potassium or silver salts of bis(trifluoromethanesulfonyl)methane (CF3SO2)2CH2 and its cyclo analogues 1 with N-fluoro-bis(trifluoromethanesulfonyl)imine [(CF3SO2)2-NF], chlorine or bromine gave good yields of the corresponding α-halo disulfone (CF3SO2)2CHX and cyclo analogues 9, 10. The chemical transformation of these fluorinated α-halo-disulfones are described.     

Chromotropism in halo-bridged dimers. Structural characterization of bis(μ-halo)bis(halo N-(pyridin-2-ylmethyl)cyclohexanamine copper(II))

Two dinuclear copper(II) complexes, [LCu(μ-Cl)Cl]₂ (DMF) (1) and [LCu(μ-Br)Br]₂ (2), with the bidentate ligand N-(pyridin-2-ylmethyl)cyclohexanamine, L, were synthesized and characterized by physicochemical and spectroscopic (IR, UV–vis) data. The crystal structural analysis of 1 shows that both copper(II) ions are in a distorted square pyramidal N₂Cl₃ environment with the apical position of the copper(II) being occupied by the bridging chloride anion which is equatorial to the other copper ion, forming a dimeric copper(II) complex. The chromotropic properties of both complexes, including solvato-, thermo-, and halochromism, were investigated. The complexes show reversible thermochromism in solution which is irreversible in the solid state. It was found that the solvatochromism is due to structural change followed by solvation of the vacant sites of the complexes. Their halochromic properties were studied in pH range of 1–11 by visible absorption spectroscopy. The color changes from blue to green and to colorless are due to deprotonation and protonation of the ligands.     

Formation constants and oxidation of bis(1,10-phenanthroline)-copper(I) perchlorate and bis(2,2′-bipyridine)copper(I) perchlorate by molecular oxygen in formamide

Summary A study was made of the slow oxidation with molecular oxygen in formamide of the cuprous complexes Cu(1,10-phenanthroline)₂ ⁺ and Cu(2,2-bipyridine)₂ ⁺, and of Cu(MeCN)₄ClO₄ with and without complexing agents. The two formation constants were calculated from the kinetic data. Both complexes reacted with a rate constant of 0.001 with respect to the value obtained in solvent water. A catalytic effect of the water molecules is proposed to explain this difference. The cupric complexes formed were isolated and identified as [CuL₂ formate]ClO₄ and [CuL₂ cyanate]ClO₄.     

Condensation of bis(β-alaninato)copper(II) with formaldehyde and ammonia

Various complexes have been prepared by the template condensation of -amino acids with formaldehyde or acetaldehyde in the presence of metal ions(^1–5). In particular, glycine has received much attention(^1–4). For example, (3N, 7N-1,3,5,7-tetraazabicyclo[3.3.1]nonyl)-diacetato nickel(II) (1) has been prepared by condensing bis(glycinato)nickel(II) dihydrate with formaldehyde and ammonia at pH 8.5⁴. More recently⁵, complex (2) has been prepared by condensing bis(L-alaninato)copper(II) with formaldehyde and ammonia. These reactions are interesting for the following reasons:

Synthesis of bis(indolyl) methanes catalyzed by Schiff base-Cu(Ⅱ) complex

Schiff base-Cu(Ⅱ) complex is found to be an effective catalyst for the condensation reaction of indole with aldehydes using ethanol as the solvent.The characterization of the catalysts was carried out using XRD and FT-IR.     

The single-crystal electron spin resonance spectra of bis chloro bis(N,N′-substituted urea)oxovanadium(IV) compounds diluted in the corresponding tris-chloro bis(N,N′-substituted)urea indium(III) compounds

Single crystal ESR spectra of VOCl₂L₂ (where L = N, N, N′, N′-tetramethyl urea (tmu), N, N′-dimethylethyleneurea, N, N′-dimethylpropyleneurea, tris(dimethylamino)phosphincoxide) diluted in the corresponding Inøcl₃L₂, at Q-band frequencies are reported. The ESR data are consitent with C₂ point symmetry for VOCl₂(tmu)₂ whilst the other compounds approximate very closely to this point symmetry. A rotation of the g and A tensor axes in the plane perpendicular to the terminal VO vector fall in the range 8–15° for the four compounds studied. The spin Hamiltonian parameters for VOCl₂(tmu)₂, in conjunction with the published polarized electronic absorption spectra, have been analysed via angular overlap calculations. For VOCl₂(tmu)₂ unusual ligand hyperfine splittings were observed. These were analysed by spectrum simulation in terms of two equivalent chlorine atoms where the chlorine hyperfine and nuclear quadrupole tensors are of comparable magnitude.     

Two modifications of bis(μ2-chloro)tetrachlorodicuprate(II) bis[(18-crown-6)potassium]: Synthesis and crystal structure

Two crystal modifications of a novel complex bis(μ₂-chloro)tetrachlorodicuprate(II) bis[(18-crown-6)potassium, [K{(18-crown-6)}₂Cu₂Cl₆] were synthesized and studied by X-ray diffraction. The structures of two monoclinic modifications—Iα (space group P2₁/n, a = 9.053, b = 33.815, c = 13.469 Å, β = 101.29°, Z = 4) and Iβ (space group P2₁/c, a = 10.991, b = 8.187, c = 22.542 Å, β = 98.15°, Z = 2) were solved by the direct method and refined by the full-matrix least-squares method in anisotropic approximation to R = 0.073 (Iα) and 0.068 (Iβ) for 4883 (Iα) and 3525 (Iβ) independent reflections (CAD-4 automated diffractometer, λMoK _α). The molecules of Iα and Iβ consist of the central binuclear complex anion [Cu₂Cl₆]^2? and two peripheral host-guest cationic fragments [K(18-crown-6)]⁺, each linked with the [Cu₂Cl₆]^2? anions through the K-Cl bonds. The molecule of Iα and centrosymmetric Iβ molecule have different structures, since they have different orientation of the [K(18-crown-6)]⁺ fragments relative to the central [Cu₂Cl₆]^2? anion. The coordination polyhedron of the Cu²⁺ cation in the latter anion in Iα and Iβ is intermediate between flattened tetrahedron and square. In the [K(18-crown-6)]⁺ ions of Iα and Iβ, the K⁺ cation has the distorted hexagonal pyramidal coordination polyhedron with six O atoms of the 18-crown-6 ligand in a base and bifurcate vertex at two Cl atoms of the [Cu₂Cl₆]^2? anion. The 18-crown-6 ligands of Iα and Iβ have standard crown conformation.     

Three new dinuclear manganese(II) complexes with bis(μ-phosphinato)-bridges

A new series of dinuclear phosphinato-bridged manganese(II) complexes [Mn(μ-bmp)(bpy)(NO₃)]₂ (1), [Mn(μ-bmp)(phen)(NO₃)]₂·4CH₂Cl₂ (2) and [Mn₂(μ-bmp)₂(5-dmbpy)₂(NO₃)]₂ (3) where Hbmp is bis(4-methoxyphenyl)phosphinic acid, bpy = 2,2′-bipyridyl, phen = 1,10-phenanthroline and 5-dmbpy = 5,5′-dimethyl-2,2′-dipyridyl, have been synthesized and structurally characterized by X-ray crystallography. In this series, the structures consist in bis(4-methoxyphenyl)phosphinato anions (bmp) bridging the two Mn(II) centers in a syn-syn coordination mode. The coordination geometry around the Mn(II) ions in 1-3 is six-coordinate with distorted octahedral environment. The magnetic behavior of these complexes is reported. The complexes show weak antiferromagnetic coupling with |J| in the range 0.1-0.6 cm⁻¹. The magnetic properties are discussed in relation to the structural data.