Inner-sphere oxidation of iron(II) by tris(malonato)cobaltate(III)

The kinetics of oxidation of Fe²⁺ by [Co(C₃H₂O₄)₃]^3? in acidic solutions at 605 nm showed a simple first-order dependence in each reactant concentration. The second-order rate constant dependence on [H⁺] is in accordance with eqn (i) k₂ = k′₂ + k₃[H⁺] (i) where k′₂ and k₃ have values of 73.4 ± 14.0 M ^?1 s^?1 and 353 ± 41 M^?2 s^?1, respectively, at 1.0 M ionic strength (NaClO₄) and 25°C. At 310 nm the formation and decomposition of an intermediate, believed to be [FeC₃H₂O₄]⁺, was observed. The increase in the rate of oxidation with increasing [H⁺] was interpreted in terms of a “one-ended” dissociation mechanism which facilitates chelation of Fe₂₊ by the carbonyl oxygens of malonate in the transition state.     

Trifluoromethylselenato(0) and trifluoromethyltellurato(0) complexes of platinum(II)

The series of cis/trans-trifluoromethylselenato complexes [Pt(SeCF₃)_2 − xCl_x(PPh₃)₂] (x = 0, 1) was identified by NMR spectroscopic methods. While in acetonitrile solution spectra are dominated by the resonances of the cis derivatives, those of pure cis-[Pt(SeCF₃)₂(PPh₃)₂] indicate cis-trans-isomerisation in CH₂Cl₂ solution. In contrast, exchange reactions of cis-[PtCl₂(PPh₃)₂] and [NMe₄]TeCF₃ only gave evidence for cis isomers. Molecular structures of cis- and trans-[Pt(SeCF₃)₂(PPh₃)₂] and cis-[Pt(TeCF₃)₂(PPh₃)₂] are discussed in comparison with related compounds.     

Complexation of trimeric copper(i) and silver(i) 3,5-bis(trifluoromethyl)pyrazolates with amine-borane

A complexation of trimeric copper(i) and silver(i) 3,5-bis(trifluoromethyl)pyrazolates ((ML)₃) with BH₃NEt₃ was studied by IR spectroscopy in hexane and dichloromethane solutions. In hexane, two complexes [(ML)₃][BH₃NEt₃]₂ (1) and [(ML)₃][BH₃NEt₃] (2) were formed depending on the ratio of reagents. In dichloromethane, only one complex [(ML)₃][BH₃NEt₃] (2) was found. The thermodynamic parameters (ΔH ^○, ΔS ^○) of complex 1 in hexane and complex 2 in dichloromethane were obtained. The complex [(AgL)₃][BH₃NEt₃] was isolated in the solid state, its structure was established by X-ray diffraction. The complex is formed due to two bridges B-H-Ag, one BH group is not involved in the complexation. In crystal, molecules 2 form supramolecular dimers due to the intermolecular interactions between metals of two macrocycles.     

Trimethylphosphine complexes of tungsten(O) and (IV). X-ray crystal structures of trimethylphosphine tris (phenylacetylene) tungsten(O); bis(trimethylphosphine) tetrakis (methylisocyanide) tungsten(O), and oxodichlorotris (trimethylphosphine) tungsten (IV)

The reduction of WCl₄(PMe₃)₃ by sodium amalgam in presence of phenylacetylene gives W(PMe₃)(PhCCH)₃ (A). Reduction in presence of methylisocyanide gives W(PMe₃)₂(MeNC)₄ (B), while in presence of excess PMe₃ in tetrahydrofuran under hydrogen, WH₂Cl₂(PMe₃)₄ (C) is formed. The reaction of WCl₂(PMe₃)₄ with methanol in tetrahydrofuran gives mixtures of WH₂Cl₂(PMe₃)₄ and WOC1₂(PMe₃)₃ (D).The structures of A, B, and D have been determined by X-ray diffraction.     

Silver(I) ions-enhanced electrochemiluminescence of tris(2,2-bipyridyl)ruthenium(II)

In this paper, we demonstrate an electrochemiluminescence (ECL) enhancement of tris(2,2-bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺) by the addition of silver(I) ions. The maximum enhancement factor of about 5 was obtained on a glassy carbon electrode in the absence of co-reactant. The enhancement of ECL intensity was possibly attributed to the unique catalytic activity of Ag⁺ for reactions between Ru(bpy)₃³⁺ with OH. The higher enhancement was observed in phosphate buffer solutions compared with that from borate buffer solutions. This resulted from the fact that formation of nanoparticles with large surface area in the phosphate buffer solution exhibited high catalytic activity. The amount of Ag⁺, solution pH and working electrode materials played important roles for the ECL enhancement. We also studied the effects of Ag⁺ on Ru(bpy)₃²⁺/tripropylamine and Ru(bpy)₃²⁺/C₂O₄²⁻ ECL systems.     

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

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.     

Die Kristallstruktur von p-Tolylbis(diethyldithiocarbamato)-thallium(III) und Phenylbis(methylxanthogenato)bismut(III)

Crystal Structure of p-Tolylbis (diethyldithiocarbamato)thallium(III) and Phenylbis-(methylxanthogenato)bismut(III) The crystal structure of 4-CH₃(C₆H₄)? Tl(S₂CN(C₂H₅)₂)₂ (P2₁/c, a = 11.973(3), b = 10.692(3), c = 19.232(4) Å, β = 114.02(2)°, Z = 4) and C₆H₅-Bi(S₂COCH₃)₂ (P2₁/c, a = 6.395(2), b = 24.684(8), c = 9.732(3) Å, β = 101.38(3)°, Z = 4) was solved from X-ray diffraction data of single crystals. From the interatomic distances follows that the dithiocarbamate and xanthogenate ligands coordinate asymmetrically bidentate to the metal as presumed and exclusively through the sulfur atoms. Differences in the coordination sphere of bismut and thallium give evidence for a “stereochemically active lone pair” on the bismut atom.     

Preparation of the First Manganese(III) and Manganese(IV) Azides

Fluoride‐azide exchange reactions of Me₃SiN₃ with MnF₂ and MnF₃ in acetonitrile resulted in the isolation of Mn(N₃)₂ and Mn(N₃)₃?CH₃CN, respectively. While Mn(N₃)₂ forms [PPh₄]₂[Mn(N₃)₄] and (bipy)₂Mn(N₃)₂ upon reaction with PPh₄N₃ and 2,2′‐bipyridine (bipy), respectively, the manganese(III) azide undergoes disproportionation and forms mixtures of [PPh₄]₂[Mn(N₃)₄] and [PPh₄]₂[Mn(N₃)₆], as well as (bipy)₂Mn(N₃)₂ and (bipy)Mn(N₃)₄. Neat and highly sensitive Cs₂[Mn(N₃)₆] was obtained through the reaction of Cs₂MnF₆ with Me₃SiN₃ in CH₃CN.     

Lead(II) and cadmium(II) compounds with 2,4-dichlorophenoxyacetic acid (2,4D) and 2-(2,4-dichlorophenoxy)-propionic acid (2,4DP): Synthesis and properties

The paper presents the conditions under which compounds of the commercial herbicides, 2,4-dichlorophenoxyacetic acid (2,4D; C₈H₆O₃Cl₂) and 2-(2,4-dichlorophenoxy)-propionic acid (2,4DP; C₉H₈O₃Cl₂), with lead(II) and cadmium(II) are formed and the results of the examination of their properties.On the basis of the elemental analysis and Pb and Cd determination, the following molecular formulae for the obtained compounds were proposed: Pb(C₈H₅O₃Cl₂)₂.H₂O, Cd(C₈H₅O₃Cl₂)₂.₂H₂O, Pb(C₉H₇O₃Cl₂)2·H₂O and Cd(C₉H₇O₃Cl₂)₂·H₂O. Water solubility of the synthesized complexes at room temperature was examined. X-ray powder analysis was carried out. The discussion of IR spectra and conductivity data is presented. Thermal decomposition of these compounds in air was studied by TG/MS methods.This revised version was published online in November 2005 with corrections to the Cover Date.     

Coordination,oligomerisation and transfer hydrogenation of acetylenes by some ruthenium and osmium carboxylates: Crystal and molecular structures of bis(trifluoroacetato)carbonyl-(methanol) bis(triphenylphosphine)ruthenium(II) and (1,4-diphenylbut-1-en-3-yn-2-yl)trifluoroacetato-(carbonyl) bis(triphenylphosphine)ruthenium(II)

The hydrides [MH(O₂CCF₃)(CO)(PPh₃)₂] (M = Ru or Os) react with disubstituted acetylenes PhCCPh and PhCCMe to afford vinylic products [M{C(Ph)CHPh}(O₂CCF₃)(CO)(PPh₃)₂] and [M{C(Ph)CHMe}(O₂CCF₃)(CO) (PPh₃)₂]/[M{C(Me)CHPh}(O₂CCF₃)(CO)(PPh₃)₂] respectively. Acidolysis of these products with trifluoroacetic acid in cold ethanol liberates cis-stilbene and cis-PhHCCHMe respectively thus establishing the cis-stereochemistry of the vinylic ligands. The complexes [M(O₂CCF₃)₂(CO)(PPh₃)₂] formed during the acidolysis step undergo facile alcoholysis followed by β-elimination of aldehyde to regenerate the parent hydrides [MH(O₂CCF₃)(CO)(PPh₃)₂] and thereby complete a catalytic cycle for the transfer hydrogenation of acetylenes. The molecular structure of the methanol-adduct intermediate, [Ru(O₂CCF₃)₂(MeOH)(CO)(PPh₃)₂] has been determined by X-ray methods and shows that the coordinated methanol is involved in H-bonding with the monodentate trifluoroacetate ligand [MEO-H---OC(O)CF₃; O...O = 2.54 Å]. The hydrides [MH(O₂CCF₃)(CO) (PPh₃)₂]react with 1,4-diphenylbutadiyne to afford the complexes [M{C(CCPh)CHPh} (O₂CCF₃)(CO)(PPh₃)₂]. The ruthenium product, which has also been obtained by treatment of [RuH(O₂CCF₃)(CO)(PPh₃)₂] with phenylacetylene, has been shown by X-ray diffraction methods to contain a 1,4-diphenylbut-1-en-3-yn-2-yl ligand. The osmium complexes [Os(O₂CCF₃)₂(CO)(PPh₃)₂], [OsH(O₂CCF₃)(CO)(PPh₃)₂] and [Os{C(CCPh)CHPh}(O₂CCF₃)(CO)(PPh₃)₂] all serve as catalysts for the oligomerisation of phenylacetylene. Acetylene reacts with [Ru(O₂CCF₃)₂(CO)(PPh₃)₂] in ethanol to afford the vinyl complex [Ru(CHCH₂)(O₂CCF₃)(CO)(PPh₃)₂].     

The Vanadium(V) Oxoazides [VO(N3)3], [(bipy)VO(N3)3], and [VO(N3)5]2−

Vanadium(V) oxoazide [VO(N₃)₃] was prepared through a fluoride–azide exchange reaction between [VOF₃] and Me₃SiN₃ in acetonitrile solution. When the highly impact‐ and friction‐sensitive compound [VO(N₃)₃] was reacted with 2,2′‐bipyridine, the adduct [(bipy)VO(N₃)₃] was isolated. The reaction of [VO(N₃)₃] with [PPh₄]N₃ resulted in the formation and isolation of the salt [PPh₄]₂[VO(N₃)₅]. The adduct [(bipy)VO(N₃)₃] and the salt [PPh₄]₂₃[VO(N₃)₅] were characterized by vibrational spectroscopy and single‐crystal X‐ray structure determination, making these compounds the first structurally characterized vanadium(V) azides.     

Interaction of poly(vinyl acetate) radical with iron (III) complexes

The polymerization of vinyl acetate in N,N-dimethylformamide (DMF) at 60°C initiated by AIBN in the presence of [Fe(DMF)₆](ClO₄)₃ and Fe(N₃)₃ had been studied. Fe(N₃)₃ was produced in situ by mixing solid sodium azide (NaN₃) and hexakis(N,N-dimethylformamide) iron (III) perchlorate, [Fe(DMF)₆](ClO₄)₃, in the ratio of 3:1. The velocity constant k_x for the interaction of poly(vinyl acetate) radical with [Fe(DMF)₆]³⁺ was found to be 1.44 × 10³L mol^?1 s^?1 and that for the interaction of poly(vinyl acetate) radical with Fe(N₃)₃ to be 3.44 × 10⁵ L mol^?1 s^?1 at 60°C.     

Solvent and Temperature Dependence of 59Co NMR Chemical Shifts of Tris(acetylacetonato)cobaIt(III) and Tris(dipivaloylmethanato)cobalt(III)

Cobalt-59 NMR chemical shifts of Co(acac)₃, and Co(dpm)₃ (acac^– = acetylacetonate ion and dpm^– = dipivaloylmethanate ion) in 14 organic solvents, C₆H₁₄, C₆H₆, CH₂Cl₂, CHCl₃, CCl₄, CH₃CN, CH₃OH, C₂H₅OH, CH₃CH(OH)CH₃, (C₂H₅)₂O, (CH₃)₂CO, (CH₃)₂SO, (CH₃)₂NCHO and C₆H₅NO₂, were measured at five temperatures ranging from 289 to 329 K. The observed chemical shift (_obs) was linearly correlated to the maximum absorption wavelength in the visible spectra (_max) corresponding to the d-d electronic transition energy between the ground ¹A_1g and excited ¹T_1g states. The _obs-_max relation was explained by the ligand field theory. The temperature coefficients of _obs, of each complex showed a negative correlation with _obs. The _obs, of Co(acac)₃ decreased with the increasing electrophilic ability of the solvent (Mayer's acceptor number), whereas no tendency was observed in the case of Co(dpm)₃.     

Structural features of copper(II) and lanthanide(III) tartratogermanate(IV) complexes

Four heterometallic tartratogermanate complexes, namely [Cu₂Ge₂(Tart)₃(H₂O)₁₀] _n · 3nH₂O and (H₃O)[LnGe₂(Tart)₃(H₂O)₆] · nH₂O (Ln³⁺ = Gd, n = 3.5; Tm, n = 3; Yb, n = 3), have been prepared via the reaction between germanium tetrachloride and D-tartaric acid (H₄Tart) in aqueous acetic acid. All complexes contain {Ge₂(Tart)₃} _n ^4n- polymer chains. The Cu²⁺ and Ln³⁺ atoms coordinate only Tart carbonyl oxygen atoms.     

Trichloro(Dinitrogen)Platinate(II)

Zeise's salt, [PtCl₃(H₂C=CH₂)]⁻_, is the oldest known organometallic complex, featuring ethylene strongly bound to a platinum salt. Many derivatives are known, but none involving dinitrogen, and indeed dinitrogen complexes are unknown for both platinum and palladium. Electrospray ionization mass spectrometry of K₂[PtCl₄] solutions generate strong ions corresponding to [PtCl₃(N₂)]⁻, the identity of which was confirmed through ion-mobility spectrometry and MS/MS experiments that proved it to be distinct from its isobaric counterparts [PtCl₃(C₂H₄)]⁻ and [PtCl₃(CO)]⁻. Computational analysis established a gas-phase platinum–dinitrogen bond strength of 116 kJ mol⁻¹, substantially weaker than the ethylene and carbon monoxide analogues but stronger than for polar solvents such as water, methanol and dimethylformamide, and strong enough that the calculated N−N bond length of 1.119 Å represents weakening to a degree typical of isolated dinitrogen complexes.     

Dioxouranium(VI) and oxouranium(IV) fluorosulphates and double fluorosulphates of uranium(IV)

UO₂(SO₃F)₂, UO(SO₃F)₂, U(SO₃F)₄ and MU(SO₃F)₆, MMg, Zn have been prepared by reacting UO₂(O₂CCH₃)₂, U(O₂CCH₃)₄, U(O₂CCF₃)₄ and MU(O₂CCH₃)₆ with HSO₃F. The analysis of i.r. spectral data of UO₂(SO₃F)₂, UO(SO₃F)₂ and MU(SO₃F)₆ shows the presence of only one type of SO₃F group with reduced symmetry C_s. In U(SO₃F)₄, two SO₃F groups are bidentate, while the other two are monodentate. A sharp band at 925 cm^?1 in UO₂(SO₃F)₂ is diagnostic of UO₂²⁺. The diffuse reflectance spectra of UO(SO₃F)₂, U(SO₃F)₄ and MU(SO₃F)₆ reveal hexacoordination of U(IV), while the magnetic moments of these compounds support the existence of U(IV). UO₂(SO₃F)₂ and UO(SO₃F)₂ decompose thermally in a single step with the evolution of SO₂F₂ and formation of their respective sulphates.     

A structural investigation of tris(ethyl acetoacetate)aluminium (III)

Aluminium tris(ethyl acetoacetate), Al(C₆H₉O₃)₃ has been prepared and characterized by means of ¹H and ¹³C nuclear magnetic resonance spectroscopy, scanning electron microscopy and X-ray powder diffraction (XRPD). It was determined that two stereoisomeric complexes can be distinguished in the solution: meridional and facial. The crystal structure of Al(C₆H₉O₃)₃ has been determined from XRPD data. The compound crystallizes in the monoclinic space group P2₁/n.     

The Synthesis and Structure of (1-(Diphenylphosphino)-1 - (Phenylthio)Ferrocene)Tricarbonyliron(O) (ptppf)Fe(CO)3

The complex (ptppf)Fe(CO)₃ has been prepared in high yield by the reaction of ptppf, l-(diphenyl-phosphino)-l'-(phenylthio)ferrocene, with (cis-cyclooctene)₂-Fe(CO)₃ in THF at ?60°C. The complex has been characterized by IR, ³¹P NMR, mass spectrometry and single-crystal X-ray diffraction. This compound is the first example of a ferrocenyl ligand having both sulfur and phosphorus donor atoms bound to a Fe(CO)₃ moiety. X-ray crystallography shows that the two cyclopentadienyl rings are approximately eclipsed, a rotation of 13° from exactly eclipsed conformation. The tricarbonyl iron center has a trigonal bipyramidal geometry with sulfur occupying the equatorial site and phosphorus the axial site. Crystals of (ptppf)Fe(CO)₃ are monoclinic, with a = 11.645(2), b = 14.304(1), c = 17.075(2) Å,β = 109.23(3)°, Z = 4, and space group P 2₁/n. The structure was solved according to the heavy-atom method and refined by full-matrix least-squares procedures to R = 0.037 for 2098 reflections with I ≥ 2.5σ(I).     

Synthesis and Thermal Decomposition of Cobalt(II) bis (Tartrato) Cobaltate(II) Trihydrate

The paper describes the synthesis and characterization of cobalt(II) bis (tartrato) cobaltate(II) trihydrate Co[Co[C₄O₆H₄)₂]·3H₂O. The complex was characterized on the basis of elemental analysis, infrared, electronic, e.s.r. spectra and X-ray powder diffraction studies. The thermal decomposition of the complex led to a mixture of Co₂O₃and Co₃O₄in air at about 400°C, whereas in nitrogen it was decomposed to a mixture of CoO and C at about 384°C. A tentative reaction mechanism is suggested for the thermal decomposition of the complex in air and nitrogen. This revised version was published online in July 2006 with corrections to the Cover Date.     

(Chloromethyl)thallium(III) compounds

Aryl(chloromethyl)thallium chlorides, Ar(ClCH₂)TlCl (Ar=C₆H₅, p-CH₃C₆H₄) have been prepared by treatment of arylthallium dichlorides with diazomethane. The derived carboxylates, Ar(ClCH₂)TlX, react with HgX₂ to give the dicarboxylates, (ClCH₂)TlX₂ (X = OCOCH₃, OCOC₃H₇-i) and with tetramethyltin to give CH₃(ClCH₂)TlX compounds. R(ClCH₂)TIX compounds (R = CH₃, C₆H₅, p-CH₃C₆H₄) undergo disproportionation in methanol to R₂TlX and (ClCH₂)₂TlX compounds.