Kinetische und Gleichgewichtsuntersuchungen zur Aquotisierung und Halogenid-Anation an Halogeno-Aquo-Komplexen von Osmium(IV)

Kinetic and Equilibrium Studies on Aquation and Halide-Anation of Osmium(IV)- Halogeno-Aquo Complexes Complexes of type [OsI₅X]^2? (X = Cl, Br, I) undergo hydrolysis in acidic, aqueous solutions already at room temperature according to [OsI₅X]^2? + H₂O ? [OsI₅(H₂O)]^? + X^?. Rate constants of aquation and anation reactions as well as equilibrium constants are determined by spectrophotometrical measurements. The kinetic and equilibrium experimental results are giving similar thermodynamic data. Kinetic stability increases from I over Br to Cl whereas the thermodynamic stability decreases in the same order. The monoaquo complex is less stable than the hexahalo complexes by 2 kcal/mol, and is present as an intermediate product in the halogen exchange reactions carried out in dilute solutions.     

Darstellung,Kristallstrukturen, Schwingungsspektren und Normalkoordinatenanalysen der mer‐Trihalogeno‐tris‐Pyridin‐Osmium(III)Komplexe mer‐[OsX3Py3], X = Cl,Br, I

Synthesis, Crystal Structures, Vibrational Spectra, and Normal Coordinate Analyses of the mer ‐Trihalogeno‐tris‐Pyridine‐Osmium(III) Complexes mer‐[OsX₃Py₃], X = Cl, Br, I By reaction of the hexahalogenoosmates(IV) with pyridine and iso‐amylalcohol mer‐trihalogeno‐tris‐pyridine‐osmium(III) complexes are formed and purified by chromatography. X‐ray structure determinations on single crystals have been performed of mer‐[OsBr₃Py₃] (monoclinic, space group P2₁/n, a = 9.098(5), b = 12.864(5), c = 15.632(5) Å, β = 90.216(5)°, Z = 4) and mer‐[OsI₃Py₃] (monoclinic, space group P2₁/n, a = 9.0952(17), b = 13.461(4), c = 15.891(10), β = 91.569(5)°, Z = 4). The pyridine rings are twisted propeller‐like against the N₃ meridional plane with mean angles of 49° (Cl), 46° (Br), 44° (I). Based on the molecular parameters of the X‐ray structure determinations and assuming C₂ point symmetry, the IR and Raman spectra are assigned by normal coordinate analysis. Due to the stronger trans influence of pyridine as compared with the halide ligands for N'–Os–X ^· axes significantly different valence force constants are observed in comparison with symmetrically coordinated octahedron axes: f_d(OsCl) = 1.74, f_d(OsCl^·) = 1.49, f_d(OsBr) = 1.43, f_d(OsBr ^· ) = 1.18, f_d(OsI) = 0.99, f_d(OsI ^· ) = 0.96, f_d(OsN) between 1.96 and 2.07 and f_d(OsN') between 2.13 and 2.32 mdyn/Å.     

Gemischte Halogeno-Äthylendiamin-Komplexe von Osmium(III) und (IV)

Mixed Halogeno-Ethylendiamine Complexes of Osmium (III) and (IV) [OsCl₄en] or [OsBr₄en] and [OsCl₄en]- or [OsBr₄en]- are prepared by reaction of [Os(en-H)₂en]Br₂ with HCl or HBr. Whereas the chelate group behaves inert, the halogeno ligands become substituted easily, alltogether or partly. This enables the preparation of [OsI₄en], of complexes of the type [OsCl_nBr_4?en]-, n = 1–3, and of other compounds. The chemical properties and infrared spectra of the new complexes are discussed.     

Kristallstrukturen und Schwingungsspektren von Tetrahalogenoacetylacetonatoosmaten(IV), [OsX4(acac)]−, X  Cl,Br, I

Crystal Structures and Vibrational Spectra of Tetrahalogenoacetylacetonatoosmates(IV), [OsX₄(acac)]^?, X ? Cl, Br, I By reaction of the hexahalogenoosmates(IV) with acetylacetone the tetrahalogenoacetylacetonatoosmates(IV) [OsX₄(acac)]^? (X = Cl, Br, I) are formed, which have been purified by chromatography and precipitated from aqueous solution as tetraphenylphosphonium (Ph₄P) or cesium salts. X-ray structure determinations on single crystals have been performed of (Ph₄P)[OsCl₄(acac)] ( 1 ) (triclinic, space group P1 , a = 9.9661(6), b = 11.208(2), c = 13.4943(7) Å, α = 101.130(9), β = 91.948(6), γ = 96.348(8)°, Z = 2), (Ph₄P)[OsBr₄(acac)] ( 2 ) (monoclinic, space group P2₁/n, a = 9.0251(8), b = 12.423(2), c = 27.834(2) Å, β = 94.259(7)°, Z = 4) and (Ph₄P)[OsI₄(acac)] ( 3 ) (monoclinic, space group P2₁/c, a = 18.294(3), b = 10.664(2), c = 18.333(3) Å, β = 117.68(2)°, Z = 4). Due to the increasing trans influence in the series O < Cl < Br < I the Os? O^. distances of O^.? Cl? X′ axes are lengthened and the OsO^. stretching vibrations are shifted to lower frequencies. The Os? X′ bond lenghts are shorter as compared with symmetrically coordinated X? Os? X axes.     

Characterization of a Ferryl Flip in Electronically Tuned Nonheme Complexes. Consequences in Hydrogen Atom Transfer Reactivity

Two oxoiron(IV) isomers ( ^R 2a and ^R 2b ) of general formula [Fe^IV(O)(^RPyNMe₃)(CH₃CN)]²⁺ are obtained by reaction of their iron(II) precursor with NBu₄IO₄. The two isomers differ in the position of the oxo ligand, cis and trans to the pyridine donor. The mechanism of isomerization between ^R 2a and ^R 2b has been determined by kinetic and computational analyses uncovering an unprecedented path for interconversion of geometrical oxoiron(IV) isomers. The activity of the two oxoiron(IV) isomers in hydrogen atom transfer (HAT) reactions shows that ^R 2a reacts one order of magnitude faster than ^R 2b , which is explained by a repulsive noncovalent interaction between the ligand and the substrate in ^R 2b . Interestingly, the electronic properties of the R substituent in the ligand pyridine ring do not have a significant effect on reaction rates. Overall, the intrinsic structural aspects of each isomer define their relative HAT reactivity, overcoming changes in electronic properties of the ligand.     

Synthesis,Structure and Raman Data of the New Binuclear Zirconium Complex [Ph4P]2[(ZrCl4Py)2O], with a Zr‐O‐Zr Bridge

The new Zirconium(IV) coordination compound [Ph₄P]₂[(ZrCl₄Py)₂O] (Ph = phenyl, Py = pyridine) was synthesized by dissolving ZrCl₄, [Ph₄P]Cl and a stoichiometric amount of NaOH/Na mixture in pyridine or pyridine/organic solvent mixtures. The title phase was obtained as colourless crystals. The crystal structure of [Ph₄P]₂[(ZrCl₄Py)₂O] was determined. It crystallizes monoclinic, P2₁/c, Z = 4, a = 13.412(2), b = 13.461(2), c = 16.442(3) Å, β = 102.72(1)°. The structure consists of isolated tetraphenylphosphonium cations and [(ZrCl₄Py)₂O]^2? complex anions. The centrosymmetric complex anion contains a linear Zr–O–Zr bridge. Each Zr atom is coordinated by one oxygen dianion, the N atom of one pyridine ring and four chloro ligands in a distorted octahedral geometry. The Raman spectrum of [Ph₄P]₂[(ZrCl₄Py)₂O] is also reported. Most of the observed frequencies can be assigned to vibrations of the tetraphenylphosphonium cations and the pyridine rings.     

Synthesis,Characterization, and Antibacterial Activities of Organotin(IV) Complexes with 2‐Acetylpyridine‐N(4)‐cyclohexylthiosemicarbazone (HAPCT)

The reaction of 2‐acetylpyridine‐N(4)‐cyclohexylthiosemicarbazone [(HAPCT), ( 1 )] ligand with organotin(IV) chloride(s) afforded the five new organotin(IV) complexes: [MeSnCl₂(APCT)] ( 2 ), [BuSnCl₂(APCT)] ( 3 ), [PhSnCl₂(APCT)] ( 4 ), [Me₂SnCl(APCT)] ( 5 ), and [Ph₂SnCl(APCT)] ( 6 ). The ligand ( 1 ) and its organotin(IV) complexes ( 2–6 ) have been synthesized and characterized by CHN analyses, molar conductivity, UV–vis, FT IR, ¹H, ¹³C, and ¹¹⁹Sn NMR spectral studies. The single crystal X‐ray diffraction studies indicated that [PhSnCl₂(APCT)] ( 4 ) is six coordinated and strongly adopts a distorted octahedral configuration with the coordination through pyridine‐N, azomethine‐N, and thiolato‐S atoms of the ligand. The compound crystallizes into a monoclinic lattice with the space group P21/n. The ligand ( 1 ) and its organotin(IV) complexes ( 2–6 ) were assayed for in vitro antibacterial activity against Staphylococcus aureus, Escherichia coli, Enterobacter aerogenes, and Salmonella typhi. The screening results have shown that the organotin(IV) complexes ( 2–6 ) have better antibacterial activity than the free ligand. Furthermore, it has been shown that the diphenyltin(IV) derivative ( 6 ) exhibits significantly better activities than the other organotin(IV) derivatives ( 2–5 ). © 2012 Wiley Periodicals, Inc. Heteroatom Chem 24:43–52, 2013; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21061     

Synthesis, characterization and X-ray crystal structures of seven-coordinate pentagonal-bipyramidal zinc(II), cadmium(II) and tin(IV) complexes of a pentadentate N3S2 thiosemicarbazone

New complexes of the general formula, [M(H₂dap⁴NMetsc)(H₂O)₂](NO₃)₂·H₂O (M = Zn²⁺, Cd²⁺; H₂dap⁴NMetsc = 2,6-diacetylpyridinebis(⁴N-methylthiosemicarbazone) and [Sn((dap⁴NMetsc)X₂] (X = Ph, Cl and I) (dap⁴NMetsc = the doubly deprotonated form of 2,6-diacetylpyridine bis(⁴N-methylthiosemicarbazone) have been synthesized and structurally characterized by a variety of physico-chemical techniques. X-ray crystallographic structure determination shows that in the zinc and cadmium complexes, the bis(thiosemicarbazone) ligand coordinates as a neutral N₃S₂ pentadentate chelating agent through the two azomethine nitrogen atoms, the pyridine nitrogen atom and the two thione sulfur atoms. The N₃S₂ donors of the ligand occupy the equatorial plane and the two aqua ligands occupy the sixth and seventh axial positions of the seven-coordinated cadmium(II) and zinc(II) ions. In the tin(IV) complexes, however, the thiosemicarbazone is coordinated to the tin(IV) ion as a dinegatively charged pentadentate chelating agent via the pyridine nitrogen atom, the two azomethine nitrogen atoms and the two thiolate sulfur atoms. The two apical positions of the seven-coordinate tin(IV) ion are occupied by either phenyl, chlorido or iodido ligands. In each of the complexes, the overall geometry adopted by the metal ion may be considered as a distorted pentagonal-bipyramid.     

Organic amines reduce trans-dichlorotetrakis(pyridine)cobalt(III) chloride to cobalt(II)

Summary The reaction of dichlorotetrakis(pyridine)cobalt(III) chloride. [CoCl₂(Py)₄]Cl, with alkyl- or arylamines in EtOH or i-PrOH yielded [CoCl₂(Py)₂] in all cases. This reduction of Co^III to Co^II takes place only in the presence of the amines. [CoCl₂(Py)₂] in EtOH is oxidized by Cl₂ gas and in the presence of pyridine gives [CoCl₂(Py)₄] ⁺, while in pyridine alone [CoCl₂(Py)₄] is formed.     

Schwingungs-Raman-Spektren von Hexahalogenokomplexen von OsIV (X = Cl,I) und IrIV (X = Cl,Br) bei 80 K

Vibrational Raman Spectra of Hexahalo Complexes of Os^IV (X = Cl, I) and Ir^IV (X = Cl, Br) at 80 K The Resonance-Raman (RR) spectra of the tetrabutyl- resp. tetraethylammonium salts of [OsCl₆]^2?, [OsI₆]^2?, [IrCl₆]^2?, and [IrBr₆]^2? have been investigated with the excitation-lines of an Ar⁺ and Kr⁺ laser. Devices with a movable sample holder for low-temperature experiments (80 K) are described. The anormal intensities of some of the Ra-active fundamentals are attributed to the RR effect. As a rule the deformation vibration υ₅(T_2g) is RR enhanced if excited within a π—π*(dt_2g)-CT-transition and the stretching vibration υ₂(E_g) is RR-enhanced within a π—σ*(de_g)-CT-transition. The dispersion of the degree of depolarisation of the three Ra-active fundamentals of [IrBr₆]^2? demonstrates, that this rule cannot only be applicated to the symmetrical but also to the antisymmetrical part of the scattering tensor.     

TG and DTA investigations on hexaiodometallates

K₂ThI₆, Rb₂ThI₆, Cs₂ThI₆ and Cs₂TiI₆ could be prepared from the reactions of alkali metal iodides with ThI₄ and TiI₄. By precipitation with an excess of alkali metal iodide, Rb₂OsI₆, Cs₂OsI₆, K₂PtI₆ and Rb₂PtI₆ were obtained from acid solutions of the hexaiodometallate(IV) anions, Rb₂OsBr₆ was synthesized in a similar way from the corresponding bromine compounds.The formation of the 4th group hexaiodometallates was investigated by DTA. The thermal stability of the complex salts was determined.     

Syntheses and structures of three macrocyclic supramolecular complexes and one ZnII‐containing coordination polymer generated from a semi‐rigid multidentate N‐containing ligand

Semirigid organic ligands can adopt different conformations to construct coordination polymers with more diverse structures when compared to those constructed from rigid ligands. A new asymmetric semirigid organic ligand, 4‐{2‐[(pyridin‐3‐yl)methyl]‐2H‐tetrazol‐5‐yl}pyridine ( L ), has been prepared and used to synthesize three bimetallic macrocyclic complexes and one coordination polymer, namely, bis(μ‐4‐{2‐[(pyridin‐3‐yl)methyl]‐2H‐tetrazol‐5‐yl}pyridine)bis[dichloridozinc(II)] dichloromethane disolvate, [Zn₂Cl₄(C₁₂H₁₀N₆)₂]·2CH₂Cl₂, ( I ), the analogous chloroform monosolvate, [Zn₂Cl₄(C₁₂H₁₀N₆)₂]·CHCl₃, ( II ), bis(μ‐4‐{2‐[(pyridin‐3‐yl)methyl]‐2H‐tetrazol‐5‐yl}pyridine)bis[diiodidozinc(II)] dichloromethane disolvate, [Zn₂I₄(C₁₂H₁₀N₆)₂]·2CH₂Cl₂, ( III ), and catena‐poly[[[diiodidozinc(II)]‐μ‐4‐{2‐[(pyridin‐3‐yl)methyl]‐2H‐tetrazol‐5‐yl}pyridine] chloroform monosolvate], {[ZnI₂(C₁₂H₁₀N₆)]·CHCl₃}_n, ( IV ), by solution reaction with ZnX₂ (X = Cl and I) in a CH₂Cl₂/CH₃OH or CHCl₃/CH₃OH mixed solvent system at room temperature. Complex ( I ) is isomorphic with complex ( III ) and has a bimetallic ring possessing similar coordination environments for both of the Zn^II cations. Although complex ( II ) also contains a bimetallic ring, the two Zn^II cations have different coordination environments. Under the influence of the I^? anion and guest CHCl₃ molecule, complex ( IV ) displays a significantly different structure with respect to complexes ( I )–( III ). C—H…Cl and C—H…N hydrogen bonds, and π–π stacking or C—Cl…π interactions exist in complexes ( I )–( IV ), and these weak interactions play an important role in the three‐dimensional structures of ( I )–( IV ) in the solid state. In addition, the fluorescence properties of L and complexes ( I )–( IV ) were investigated.     

Dihalodimethyltin(IV) complexes of 2‐(pyrazol‐1‐ylmethyl)pyridine

Reaction of dichloro‐ and dibromodimethyltin(IV) with 2‐(pyrazol‐1‐ylmethyl)pyridine (PMP) afforded [SnMe₂Cl₂(PMP)] and [SnMe₂Br₂(PMP)] respectively. The new complexes were characterized by elemental analysis and mass spectrometry and by IR, Raman and NMR (¹H, ¹³C) spectroscopies. Structural studies by X‐ray diffraction techniques show that the compounds consist of discrete units with the tin atom octahedrally coordinated to the carbon atoms of the two methyl groups in a trans disposition (Sn? C = 2.097(5), 2.120(5) Å and 2.110(6), 2.121(6) Å in the chloro and in the bromo compounds respectively), two cis halogen atoms (Sn? Cl = 2.4908(16), 2.5447(17) Å; Sn? Br = 2.6875(11), 2.7464(9) Å) and the two donor atoms of the ligand (Sn? N = 2.407(4), 2.471(4) Å and 2.360(5), 2.455(5) Å). In both cases, the Sn? N(pyridine) bond length is markedly longer than the Sn? N(pyrazole) distance. Copyright © 2003 John Wiley & Sons, Ltd.     

trans‐Bis­[ethane‐1,2‐di­thiol­ato(2–)‐S,S′]­bis(2‐mer­cap­to­pyri­dine‐S)­tin(IV)

The title compound, [Sn(C₅H₅NS)₂(C₂H₄S₂)₂], was obtained from a 1:2 mixture of bis­(ethane‐1,2‐di­thiol­ato)­tin(IV) and 2‐mercapto­pyridine. The mol­ecules are discrete monomeric trans‐octahedral units, with the Sn^IV atom at the centre of symmetry, planar 2‐mercapto­pyridine zwitterions and SnS₂C₂ groups in twist–envelope conformations. The 2‐mercapto­pyridine ligands are monodentate and are bonded through the S atoms. The S—Sn distances between the S atom of edt (edt is ethane‐1,2‐di­thiol­ate) and the Sn atom are 2.473 (1) and 2.505 (1) Å, which are slightly longer than the S—Sn distance in Sn(edt)₂ of 2.390 (1) Å. The bond between the 2‐mercapto­pyridine S atom and the Sn atom are, remarkably, weaker than the S—Sn bond involving edt.     

2,6‐Bis[bis(2‐pyridiniomethyl)aminomethyl]‐4‐tert‐butylphenol dichloride diperchlorate hydrate

The title compound, C₃₆H₄₄N₆O⁴⁺·2Cl^?·2ClO₄^?·0.132H₂O, is shown to be protonated at all the pyridine N atoms; the two chloride ions are hydrogen bonded to three pyridine N atoms and to the phenolic O atom of the same cation [Cl?N = 3.045 (2)–3.131 (2) Å and Cl?O = 2.938 (2) Å], and the remaining pyridine N atom is hydrogen bonded to the phenolic O atom [N?O = 2.861 (2) Å]. The mean value of the C—N—C angle of the protonated pyridine rings is 123.4 (1)°, which is significantly larger than that found for unprotonated pyridine rings.     

Quantum yield for photosubstitution of a co group in chromium hexacarbonyl by pyridine

The quantum yield of the photosubstitution of CO by pyridine in cyclohexane has a value of 0.67 ± 0.02 for [Cr(CO)₆] = 3.10^?4 mol l^? and [pyridine] = 10^? mol l^?1.     

A study of some amine,pyridine and 3,5-lutidine complexes of trimethylplatinum(IV)

The reactions of trimethylplatinum(IV) compounds with a number of amines have been examined. With ammonia and methylamine, tris-and mono(amine)species have been obtained, but no bis(amine)species apart from [pt(CH₃)₃(NH₃)₂I]. With ethylamine the bis(amine)species is formed with excess ligand. The ¹H NMR spectra of [Pt(CH₃)₃LI]₂ (L=pyridine, 3,5-lutidine) exhibit evidence for two isomers in solution and an equilibrium of these compounds with [Pt(CH₃)₃L₂I] and [Pt(CH₃)₃I]₄.     

Unusual metalloporphyrins : thorium and uranium complexes of octaethylporphyrin.

The action of thorium or uranium tetrachloride with octaethylporphyrin [(oep)H₂] affords the dichlorometal (IV) complexes [M(IV)(oep)Cl₂, L_n] (M(IV) = Th or U, L = benzonitrile, tetrahydrofuran or pyridine). Spectral properties of these complexes are in good agreement with a cis octa-coordination.     

Synthesis,structure, and catalytic activity of Keggin-type polyoxometalate coordinated Cu(I): {[Cu(py)2]4[SiW12O40]}, via hydrothermal decarboxylation

A Keggin-type polyoxometalate [SiW₁₂O₄₀]^4? supported transition metal complex, {[Cu(py)₂]₄[SiW₁₂O₄₀]} (py?=?pyridine), has been synthesized by hydrothermal decarboxylation and characterized by elemental analyses, IR spectra, thermal stability analyses, and single-crystal X-ray diffraction. The compound is a 1-D chain containing an inorganic–organic backbone with alternating [SiW₁₂O₄₀]^4? clusters and [Cu(py)₂]⁺ along the c-axis, and with both three- and four-coordinate copper. The luminescence properties indicated that the emission peak is emission of pyridine, assigned to the Cu(I) to pyridine charge transfer. This air-stable Cu(I) complex can efficiently catalyze the O-arylation of both phenols and aryl halides.     

2-{[3-(Triethoxysilyl)propyl]amino}pyridine and Derivatives

2-{[3-(Triethoxysilyl)propyl]amino}pyridine is synthesized by condensation of [3-(triethoxysilyl)propyl]amine with 2-aminopyridine. Its peretherification with triethanolamine leads to 2-[(3-silatranylpropyl)amino]pyridine and hydrolytic copolycondensation with tetraethoxysilane to cross-linked organosilicon copolymer {SiO₂·2[O1.5Si(CH₂)₃NHC₆H₄N]} _n . The latter in the medium of hydrochloric acid behaves as an anionite in respect of anionic chlorocomplexes of gold(III), platinum(IV), palladium(II) and rhodiumIII).