bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intercalation of γ‐Butyrolactone into Vanadyl Phosphate and Niobyl Arsenate
Authors: Zima Vítězslav , Melánová Klára , Beneš Ludvík , Trchová Miroslava , Dybal Jiří 
Published: January 2004

AbstractIntercalation compounds of vanadyl phosphate and isostructural niobyl arsenate with γ‐butyrolactone, VOPO4·C4H6O2 and NbOAsO4·C4H6O2, respectively, were prepared from corresponding propanol intercalates by molecular exchange in a microwave field. The prepared intercalates were characterized using powder X‐ray diffraction, density measurements, and thermogravimetric analysis. Infrared and Raman spectra indicate a coordination of the carbonyl oxygen atom of the γ‐butyrolactone molecule to the vanadium or niobium atom of the host structure. Quantum mechanical calculations at the ab initio level confirm the proposed structure in which the γ‐butyrolactone guest molecules are arranged with the plane of the ring perpendicular to the host layers and are anchored to the layers through the carbonyl oxygen atom coordinated to the transition metal atom of the host. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Glycosyl‐Curcuminoids as Potential New Chelating Agents in Iron Overload Chelation Therapy
Authors: Arezzini Beatrice , Ferrali Marco , Ferrari Erika , Grandi Romano , Monti Stefano , Saladini Monica 
Published: January 2004

AbstractThe iron(III) chelating ability of some glycosyl derivatives of curcuminoids is tested by means of UV, potentiometric and NMR studies. The pKa of the ligands and the stability constants of their Fe3+ and Ga3+ complexes are evaluated by UV spectroscopy. The only metal binding site of the ligand is the β‐dioxo moiety; the glycosyl moiety does not interact with the metal ion at acidic pH values but it helps to stabilise metal/ligand (1:2) complexes by means of hydrophilic interactions. By comparing the pFe3+ of our ligands with those reported for other chelating agents we suggest using these molecules as pro‐drugs in iron overload treatment. Some of the more water‐soluble derivatives are also tested for their antioxidant properties “in vitro” in biological systems and proved to act as free‐radical scavengers inhibiting the iron redox cycle. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A Series of Vinylidene‐, Vinyl‐, Carbene‐ and Carbyneruthenium(II) Complexes with [Ru(PCy3)2] and [Ru(PiPr3)2] as Molecular Building Blocks
Authors: Jung Stefan , Ilg Kerstin , Brandt Carsten D. , Wolf Justin , Werner Helmut 
Published: January 2004

AbstractThe hydrido(vinylidene) complexes [RuHCl(=C=CHR)(L)2] (R = H, tBu, Ph; L = PCy3, PiPr3) undergo metathesis reactions in the presence of KX (X = I, NCO, OPh, CH3CO2, CF3CO2) to give the substitution products [RuHX(=C=CHR)(L)2] (6−15) in good to excellent yields. Treatment of [RuHX(=C=CHR)(L)2] with HBF4 in diethyl ether affords the cationic carbyneruthenium(II) derivatives [RuHX(≡CCH2R)(OEt2)(L)2]BF4 (17, 18, 20, 21) and [RuH(κ2‐O2CCH3)(≡CCH2R)(L)2]BF4 (19, 22). The reactions of [RuHCl(=C=CHR)(L)2] with MX [X = BF4, PF6, BPh4, B(Arf)4] in acetonitrile lead to the formation of cationic five‐ and six‐coordinate vinylruthenium(II) compounds 26a−d and 27a−d of which [Ru(CH=CH2)(CH3CN)2(PCy3)2]BPh4 (26c) has been characterized by X‐ray crystallography. The starting material [RuHCl(=C=CHPh)(PiPr3)2] reacts with CO to give [RuCl(CH=CHPh)(CO)2(PiPr3)2] (28) and with N2 to produce [RuCl(CH=CHPh)(N2)(PiPr3)2] (29). The molecular structure of 29 has been determined. Protonation of [Ru(CH=CH2)(CH3CN)2(PCy3)2]X and [Ru(CH=CHPh)(CH3CN)3(PiPr3)2]X with HBF4 and HB(Arf)4 yields the dicationic carbeneruthenium(II) complexes [Ru(=CHCH3)(CH3CN)2(PCy3)2]X2 (30a,b) and [Ru(=CHCH2Ph)(CH3CN)3(PiPr3)2][B(Arf)4]2 (31), the latter of which eliminates styrene to give [Ru(CH3CN)3(PiPr3)2][B(Arf)4]2 (32). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Electrochemical and Spectroelectrochemical Investigations of Mono‐ and Binuclear Cobalt(II) Complexes of “Figure‐Eight” Octapyrrolic Macrocycles
Authors: Bley‐Escrich Jordi , Gisselbrecht Jean‐Paul , Michels Martin , Zander Lars , Vogel Emanuel , Gross Maurice 
Published: January 2004

AbstractIn this paper, electrochemical investigations of a set of three cyclooctaphyrin complexes containing divalent cobalt are reported. These complexes are the homodinuclear cobalt‐cobalt complex Co2L1 with the ligand H4L1, the mononuclear cobalt complex CoH2L2 and the heterodinuclear copper(II)‐cobalt complex CoCuL2 with the ligand H4L2. All of these species undergo two reduction and three oxidation processes, all of which are reversible one‐electron transfers. The two reduction and first two oxidation steps are ligand‐centered, as confirmed by spectroelectrochemical investigations. In contrast, the third oxidation corresponds to a metal‐centered reversible one‐electron transfer. The metal‐centered oxidation steps occur at lower potentials than the third oxidation steps of the free bases. UV/Visible spectral changes observed during oxidation confirm a metal‐centered oxidation generating a cobalt(III) cation, which is rather unusual when compared with cobalt porphyrin complexes, in which the oxidation of the metal usually occurs before the oxidation of the ligand. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Comparative Electrochemical Study of Unsubstituted and Substituted Bis(phthalocyaninato) Rare Earth(III) Complexes
Authors: Zhu Peihua , Lu Fanli , Pan Na , Arnold Dennis P. , Zhang Shuyong , Jiang Jianzhuang 
Published: January 2004

AbstractThe electrochemistry of homoleptic substituted phthalocyaninato rare earth double‐decker complexes M(TBPc)2and M(OOPc)2[M = Y, La...Lu except Pm; H2TBPc = 3(4),12(13),21(22),30(31)‐tetra‐tert‐butylphthalocyanine, H2OOPc = 3,4,12,13,21,22,30,31‐octakis(octyloxy)phthalocyanine] has been comparatively studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in CH2Cl2containing 0.1Mtetra‐n‐butylammonium perchlorate (TBAP). Two quasi‐reversible one‐electron oxidations and three or four quasi‐reversible one‐electron reductions have been revealed for these neutral double‐deckers of two series of substituted complexes, respectively. For comparison, unsubstituted bis(phthalocyaninato) rare earth analogues M(Pc)2(M = Y, La...Lu except Pm; H2Pc = phthalocyanine) have also been electrochemically investigated. Two quasi‐reversible one‐electron oxidations and up to five quasi‐reversible one‐electron reductions have been revealed for these neutral double‐decker compounds. The three bis(phthalocyaninato)cerium compounds display one cerium‐centered redox wave between the first ligand‐based oxidation and reduction. The half‐wave potentials of the first and second oxidations and first reduction for double‐deckers of the tervalent rare earths depend on the size of the metal center. The difference between the redox potentials of the second and third reductions for MIII(Pc)2, which represents the potential difference between the first oxidation and first reduction of [MIII(Pc)2]−, lies in the range 1.08−1.37 V and also gradually diminishes along with the lanthanide contraction, indicating enhanced π−π interactions in the double‐deckers connected by the smaller, lanthanides. This corresponds well with the red‐shift of the lowest energy band observed in the electronic absorption spectra of reduced double‐decker [MIII(Pc′)2]−(Pc′ = Pc, TBPc, OOPc). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Electrochemistry of Heteroleptic Tris(phthalocyaninato) Rare Earth(III) Complexes
Authors: Zhu Peihua , Pan Na , Ma Changqin , Sun Xuan , Arnold Dennis P. , Jiang Jianzhuang 
Published: January 2004

AbstractThe electrochemical characteristics of a series of heteroleptic tris(phthalocyaninato) complexes with identical rare earths or mixed rare earths (Pc)M(OOPc)M(OOPc) [M = Eu...Lu, Y; H2Pc = unsubstituted phthalocyanine, H2(OOPc) = 3,4,12,13,21,22,30,31‐octakis(octyloxy)phthalocyanine] and (Pc)Eu(OOPc)Er(OOPc) have been recorded and studied comparatively by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in CH2Cl2 containing 0.1 M tetrabutylammonium perchlorate (TBAP). Up to five quasi‐reversible one‐electron oxidations and four one‐electron reductions have been revealed. The half‐wave potentials of the first, second and fifth oxidations depend on the size of the metal center, but the fifth changes in the opposite direction to that of the first two. Moreover, the difference in redox potentials of the first oxidation and first reduction for (Pc)M(OOPc)M(OOPc), 0.85−0.98 V, also decreases linearly along with decreasing rare earth ion radius, clearly showing the rare earth ion size effect and indicating enhanced π−π interactions in the triple‐deckers connected by smaller lanthanides. This order follows the red‐shift seen in the lowest energy band of triple‐decker compounds. The electronic differences between the lanthanides and yttrium are more apparent for triple‐decker sandwich complexes than for the analogous double‐deckers. By comparing triple‐decker, double‐decker and mononuclear [ZnII] complexes containing the OOPc ligand, the HOMO−LUMO gap has been shown to contract approximately linearly with the number of stacked phthalocyanine ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Cyclopentadienyl RuII Complexes as Highly Efficient Catalysts for the N‐Methylation of Alkylamines by Methanol
Authors: Del Zotto Alessandro , Baratta Walter , Sandri Mauro , Verardo Giancarlo , Rigo Pierluigi 
Published: January 2004

AbstractThe ruthenium(II) half‐sandwich complex [RuCl(η5‐C5H5)(PPh3)2] (1) catalyses the reaction between methanol and alkylamines RNH2 or R1R2NH to afford RN(CH3)2 and R1R2NCH3 products, respectively. The reaction is quantitative and generally fast, at the methanol reflux temperature, for a wide spectrum of substrates. Starting from primary amines, the stepwise formation of RN=CH2, RNHCH3, and RN(CH3)2 has been observed. Both PPh3 and Cl− dissociation from 1 are key‐steps in forming the effective catalytic species. The catalytic activity of several half‐sandwich neutral or cationic complexes (2−15) related to 1 is also discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
New Pentadentate Carboxylate‐Derivatized Sulfur Ligands Affording Water Soluble Iron Complexes with [Fe(NS4)] Cores that Bind Small Molecules (CO, NO, PMe3) as Co‐Ligands
Authors: Sellmann Dieter , Peters Kai P. , Heinemann Frank W. 
Published: January 2004

AbstractIn the search for polydentate sulfur ligands that are able to form water‐soluble iron complexes which can bind nitrogenase relevant molecules, the new pentadentate ligands pyCO2MeS4−H2 [2,6‐bis[2‐mercapto‐3‐(methoxycarbonyl)phenylthio]dimethylpyridine] (1) and pyCO2HS4−H2 [2,6‐bis(2‐mercapto‐3‐carboxyphenylthio)dimethylpyridine] (2) having NS4 donor atom sets and terminal thiolate donors have been synthesized. The starting material was CO2MeS2−H2 (2,3‐dimercapto benzoic acid methyl ester) which was alkylated with 2,6‐bis[(tosyloxy)methyl]pyridine. The problem of specifically achieving regioselective mono‐alkylation of this 1,2‐benzene‐dithiol derivative was solved by carrying out the alkylation of CO2MeS2−H2 at −78 °C in the presence of stoichiometric amounts of a base. Saponification of 1 afforded the carboxylic acid derivative. Coordination of pyCO2MeS42− to FeII in the presence of co‐ligands (L = CO, PMe3) yielded the complexes [Fe(L)(pyCO2MeS4)] where L = CO (5) or PMe3 (4). Upon treatment with NOBF4, complex 5 afforded [Fe(NO)(pyCO2MeS4)]BF4 (7) which could be subsequently converted to the isolable 19 valence electron species [Fe(NO)(pyCO2MeS4)] (8) upon reduction with N2H4. In the absence of potential co‐ligands, coordination of pyCO2MeS42− to FeII afforded the dinuclear complex [Fe(pyCO2MeS4)]2 (6) whilst coordination to NiII gave [Ni(pyCO2MeS4)]x (3). Solubility of these complexes in water could be achieved by replacing the CO2Me groups with CO2H substituents. The ligand pyCO2HS42− afforded the iron complexes [Fe(L)(pyCO2HS4)] [L = CO (10) and PMe3 (12)] and [Fe(NO)(pyCO2HS4)]BF4 (11). Both 10 and 12 could be reversibly deprotonated to give the corresponding water‐soluble salts (NMe4)2[Fe(L)(pyCO2S4)] with L = CO {(NMe4)2 [9]} and PMe3 {(NMe4)2 [13]}. The complexes were characterized by elemental analysis, spectroscopic methods and X‐ray structural determinations. The molecular structure of [Fe(PMe3)(pyCO2HS4)] (12) was found to exhibit inter‐ and intramolecular O−H···O and O−H···S hydrogen bonds which serve as models for proton transfer steps from external sources to the active sites of metal sulfur enzymes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
On the Reactivity of the Iminodiphosphane C6H4(o‐CN)N=PPh2−PPh2: Fragmentation Versus Isomerisation
Authors: Fei Zhaofu , Scopelliti Rosario , Dyson Paul J. 
Published: January 2004

AbstractThe reactivity of the iminodiphosphane C6H4(o‐CN)N=PPh2−PPh2, which contains an N=P−P unit, has been investigated. Reaction with small molecules, [viz. H2O/O2, H2O2, CH3OH, C6H4(o‐CN)NH2] and elemental sulfur result in cleavage of the P−P bond to give aminophosphane‐derivatised compounds. The products from these reactions have been characterized spectroscopically, including two by single‐crystal X‐ray diffraction. The reactivity of the iminodiphosphane towards the transition metal complexes [M(cod)Cl2] (M = Pd or Pt) has also been investigated. In the reactions, the iminodiphosphane rearranges to form the more common diphosphonylamine (P−N−P) unit which chelates to the metal centres. Three different compounds were isolated from these reactions and they have all been fully characterised by spectroscopy and single‐crystal X‐ray diffraction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Mono‐ and Dinuclear Rhodium and Iridium Complexes with Chiral Phospholanes as Ligands
Authors: Krüger Peter , Werner Helmut 
Published: January 2004

AbstractThe dinuclear complexes [RhCl(L)2]2 (1, 2) with L = 1‐isopropyl‐(2S,5S)‐2,5‐dimethylphospholane (Isophos) and (2S,5S)‐2,5‐dimethyl‐1‐phenylphospholane (Phephos), respectively, prepared from [RhCl(C8H14)2]2 and four equivalents of L, react with Lewis bases such as L, CO, ethene and diphenylacetylene by cleavage of the chloride bridges. Mononuclear compounds of the general composition [RhCl(L)3] (3, 4) and trans‐[RhCl(L′)(L)2] (5−9; L′ = CO, C2H4, C2Ph2) were obtained, of which 4 (L = Phephos) and 8 (L′ = C2H4; L = Phephos) are in equilibrium with the precursors. Oxidative addition of H2 to 1 (L = Isophos) and [RhCl(PiPr2Ph)2]2 (10) affords the mononuclear dihydrido complexes [RhH2Cl(L)2] (13) and [RhH2Cl(PiPr2Ph)2] (14), respectively, via the unsymmetrical compounds [RhH2(L)2(μ‐Cl)2Rh(L)2] (11) and [RhH2(PiPr2Ph)2(μ‐Cl)2Rh(PiPr2Ph)2] (12) as intermediates. These intermediates can be isolated by treatment of 13 and 14 with one half equivalent of 1 or 10, respectively. The hydrogenation of the η3‐allyl and η3‐benzyl complexes [(η3‐2‐RC3H4)Rh(L)2] (16−18) and [(η3‐CH2Ph)Rh(L)2] (19, 20), which were prepared from 1 or 2 and the corresponding Grignard reagent, leads to the dinuclear RhIIIRhI products [RhH2(L)2(μ‐H)2Rh(L)2] (21, 22), which are structurally related to the dichloro(dihydrido) derivatives 11 and 12. Compound 21 (L = Isophos) reacts with CO to give trans‐[RhH(CO)(L)2] (23). While treatment of 1 with phenylacetylene yields the vinylidene complex trans‐[RhCl(=C=CHPh)(Isophos)2] (26), via η2‐alkyne and alkynyl(hydrido) intermediates, the reaction of 2 with PhC≡CH affords the labile enyne compound trans‐[RhCl{η2‐(E)‐PhC≡CCH=CHPh}(Phephos)2] (27). Reaction of 27 with CO gives 6 and the free enyne. The carbene complexes trans‐[RhCl(=CPh2)(L)2] (30, 31), obtained from trans‐[RhCl(=CPh2)(SbiPr3)2] (29) and L, react with ethene not by olefin metathesis but by formation of the isomeric olefins Ph2C=CHCH3 (32) and CH2=CHCHPh2 (33) in different ratios. With iridium as the metal center, carbonyl, dihydrido, and dihydrido(carbonyl) compounds with [IrCl(Isophos)2] as the building block have been prepared. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Syntheses, Crystal Structures and Magnetic Properties of Four CuII‐HgII Mixed‐Metal Halide Oligomers
Authors: Song Jun‐Ling , Mao Jiang‐Gao , Zeng Hui‐Yi , Dong Zhen‐Chao 
Published: January 2004

AbstractFour heteronuclear CuII−HgII halides containing 2,2‐bipyridine (bipy) ligands have been synthesized and structurally characterised by single‐crystal X‐ray diffraction studies. The dinuclear complex [Cu(bipy)2HgCl2Br2] (1) contains a five‐coordinate copper(II) ion and a four‐coordinate HgII ion, in which the two different types of metal ions are bridged by a pair of chloride anions. [Cu2(bipy)4HgBr4][Hg2Br6] (2) contains a trinuclear [Cu2(bipy)4HgBr4]2+ cation in which the two copper(II) ions are bridged by an [HgBr4]2− tetrahedron via two Cu−Br bonds, and an edge‐sharing tetrahedral [Hg2Br6]2− anion. The structure of [Cu2(bipy)4Hg2Br6][Hg4Br10] (3) features a 1‐D chain along the diagonal of the a and c axes constructed from tetranuclear [Cu2(bipy)4Hg2Br6]2+ cations interconnected by [Hg4Br10]2− tetramers via elongated Hg−Br contacts (3.185 Å). Within the tetranuclear cationic unit, two [Cu(bipy)2]2+ units are bridged by an edge‐sharing dimeric tetrahedral [Hg2Br6]2− anion. In the trinuclear complex [Cu(bipy)2Hg2Cl6] (4), each [Hg2Cl6]2− dimer bridges with a [Cu(bipy)2]2+ ion to form a trinuclear [Cu(bipy)2Hg2Cl6] unit, and each pair of such units is bridged by a pair of elongated Hg−Cl bonds [3.043(5) Å] to form a dimeric unit. The magnetic properties of 1, 2, and 4 have also been investigated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Unusual CuII and MnII Complexes of Phenol‐Based Ligands Containing Amine, Pyridine and Formyl Functions: Unexpected Structural Features and Solution Studies
Authors: Koval Iryna A. , Huisman Mieke , Stassen Arno F. , Gamez Patrick , Lutz Martin , Spek Anthony L. , Reedijk Jan 
Published: January 2004

AbstractThe phenol‐based ligand Hpy2ald containing formyl, amine and pyridine functions reacts with copper(II) nitrate, copper(II) bromide and manganese(II) chloride to yield complexes with unexpected structures. In contrast to previously reported coordination compounds with similar ligands, the carbonyl group of the ligand in all complexes does not coordinate to the metal ions. The metal‐to‐ligand ratio is 2:1 in the case of the copper(II) nitrate complex and 1:1 in the case of the copper(II) bromide and manganese(II) chloride complexes. The copper(II) nitrate complex exhibits both donor‐atom and coordination number asymmetry, as one copper ion is pentacoordinate with an N3O2 donor set, and the other one is hexacoordinate with an O6 donor set. In the latter two complexes, the phenol group of the ligand remains protonated and fails to bridge the two metal ions; instead it is semi‐coordinated to only one metal ion. This results in the formation of mononuclear complexes in which copper(II) or manganese(II) ions have a distorted square‐pyramidal surrounding. All complexes were structurally, spectroscopically and magnetically investigated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Novel Thiotetraazapentalene Complexes from the Reaction of a Ruthenium Azide Complex with Alkyl Isothiocyanates
Authors: Hsu Sheng‐Chin , Lin Ying‐Chih , Huang Shou‐Ling , Liu Yi‐Hung , Wang Yu , Liu Hwang 
Published: January 2004

AbstractReactions of the ruthenium azide complex 1 with alkyl isothiocyanates give novel ruthenium thiotetraazapentalenedithione complexes 3a−c containing a hypervalent sulfur atom. The ligand, bound through one sulfur atom, is derived from three isothiocyanate molecules and one nitrogen atom from an azide ion. The synthesis and structural determination of 3a−c, as well as a possible mechanism for their formation is described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Design and Structural Analysis of Metallamacrocycles Based on a Combination of Ethylene Glycol Bearing Pyridine Units with Zinc, Cobalt and Mercury
Authors: Grosshans Philippe , Jouaiti Abdelaziz , Bulach Véronique , Planeix Jean‐Marc , Hosseini Mir Wais , Kyritsakas Nathalie 
Published: January 2004

AbstractIn the presence of MX2 salts, ligand 1 (in a M/L ratio of 2:2, M = Zn, Hg, Co, X = Cl or I), based on the ethylene glycol fragment bearing two pyridine units as monodentate coordination sites, leads to isostructural square‐shaped neutral metallamacrocycles as demonstrated by X‐ray diffraction on single crystals. For all dinuclear complexes generated, the dicationic metal centre adopts a distorted tetrahedral coordination geometry and its coordination sphere is composed of the X2N2 set of coordinating atoms. For all complexes, the parallel packing of the cyclic structures generates channels which are occupied by solvent molecules. The solvent molecules, which behave as substrates, are positioned within the cavity of the metallamacrocycles. Control of the dimension of the macrocycles, by varying the size of the connecting metal centre, has also been demonstrated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Diorganotin Salicylaldoximate Clusters: Their Fascinating Chemistry and Structures
Authors: Gielen Marcel , Biesemans Monique , Willem Rudolph , Tiekink Edward R. T. 
Published: January 2004

AbstractA large variety of small oxotin clusters, characterised as stable crystalline products or solution transients, has been obtained by the reaction of various diorganotin oxides and salicylaldoxime. The structures were investigated by high resolution multinuclear NMR methods and X‐ray crystallography. The predominant trinuclear clusters contain one seven‐ and two five‐coordinate tin atoms and undergo a series of reversible substitution reactions, including those leading to clusters of differing nuclearity, in solution at room temperature. Such a variety of structures is rather unusual in organotin chemistry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Kinetics and Mechanism of Axial Ligand Substitution of Alkyl Cobaloximes by Substituted Pyridines in Different Solvents
Authors: Alzoubi Basam M. , Hamza Mohamed S. A. , Felluga Alessandro , Randaccio Lucio , Tauzher Giovanni , van Eldik Rudi 
Published: January 2004

AbstractLigand‐substitution reactions of trans‐RCo(Hdmg)2S (where R = PhCH2 or CF3CH2, Hdmg = dimethylglyoximate, and S = H2O or MeOH) were studied for the nucleophiles 4‐aminopyridine (4‐NH2Py), pyridine (Py) and 4‐cyanopyridine (4‐CNPy). From the pressure and temperature dependence of the substitution of methanol by 4‐NH2Py, Py, and 4‐CNPy, the activation parameters ΔH≠, ΔS≠, and ΔV≠ were estimated for the cases where R = PhCH2 and CF3CH2. The activation parameters for the substitution of H2O by Py and 4‐CNPy in the case where R = CF3CH2 were also found. The kinetic data and activation parameters show that the dissociative character of the reaction decreases on changing the R group from PhCH2 to CF3CH2 and the solvent from MeOH to H2O. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Cover Picture: Kinetics and Mechanism of Axial Ligand Substitution of Alkyl Cobaloximes by Substituted Pyridines in Different Solvents (Eur. J. Inorg. Chem. 3/2004)
Authors: Alzoubi Basam M. , Hamza Mohamed S. A. , Felluga Alessandro , Randaccio Lucio , Tauzher Giovanni , van Eldik Rudi 
Published: January 2004

AbstractThe cover picture shows the dissociative character of the displacement of a coordinated solvent molecule trans to the alkyl group in cobalt(III) complexes. Details are discussed in the article by R. van Eldik et al. on p. 653 ff. The work has benefited greatly from an international collaboration.