Copper(I) complexes of neutral,deprotonated and protonated 4,6-dimethylpyrimidine-2 (1H)-thione

Summary The following copper(I) complexes of 4,6-dimethylpyrimidine-2(1H)-thione (HL), its protonated cation (H₂L⁺) and deprotonated anion (L^–) have been prepared: CuL, Cu(HL)X (X = Cl, Br or I), Cu(HL)₂X (X = C1 or Br), Cu₂(HL)₃Br₂, Cu(H₂L)X₂ (X = Cl or Br), Cu₃(HL)₂LA₂ (A = ClO₄ or BF₄ ). The i.r. spectra show that in all the HL and L^– complexes and in the Cu(H₂L)Br₂ complex, the ligands are S, N coordinated to the metal ion, while in Cu(H₂L)Cl₂ only the thiocarbonylic sulphur is coordinated, probably bridging two copper(I) atoms. Thev(CuN) (288–317 cm^–1 ) andv(CuS) (191–225 cm^–1 ) have uniform frequency values in all the complexes. The halide ions are, in all their complexes, wholly or in part coordinated giving twov(CuX) bands which may indicate an asymmetrical Cu-X Cu halide bridging bond.Author to whom all correspondence should be directed.     

Thermodynamics of complexation of lanthanides and some of transition metal ions by 5,5-dimethyl-cyclohexane-2-(2-hydroxyphenyl)-hydrazono-1,3-dione (DCPHD) and its derivatives

Summary Equilibrium betweenDCPHD,DC-4-Cl-PHD, andDC-4-Me-PHD and protons, transition, and lanthanide ions have been investigated at 30 °C by means of potentiometric titration in 75% (v/v) methanol-water mixture containing 0.10M KNO₃ as a constant ionic medium. Thermodynamic parameters (G, H and S) referring to the formation of species HL ^–,L ^––,ML ^+n–2 andML ₂ ^+n–4 (L ^–– denotes the ligand anion) have been determined in solutions. The solvent effects on the thermodynamic parameters of the complex formation are discussed in terms of differences in the donor ability of methanol and water solvents. The plots of thermodynamic parameters versus ionic potential (Z ²/r) of the lanthanide elements is not linear as expected from ionic theory. The obtained curve can be resolved in an initial group (the lighter lanthanides), an intermediate group (Sm-Dy), and a final group (the heavier ones, Tb-Lu). This behavior was explained in terms of differences in the dehydration of lighter lanthanide(III) from that of heavier ones.

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Thermodynamik der Komplexierung von Lanthaniden und einigen Übergangsmetall-Ionen mit 5,5-Dimethylcyclohexyl-2-(2-hydroxyphenyl)-hydrazono-1,3-dion (DCPHD) und seinen Derivaten

Zusammenfassung Die Gleichgewichte zwischenDCPHD,DC-4-Cl-PHD undDC-4-Me-PHD mit Protonen, Übergangsmetall- und Lanthaniden-Ionen wurden bei 30 °C mittels potentiometrischer Titration in 75% (v/v) Methanol-Wasser mit einem Gehalt an 0.10M KNO₃ als konstantem ionischem Medium untersucht. Die thermodynamischen Parameter G, H und S zur Bildung der Spezies HL ^–,L ^––,ML ^+n–2 undML ₂ ^+n–4 (L ^–– steht für das Ligandenanion) wurden in Lösung bestimmt. Die Lösungsmitteleffekte auf diese Komplexbildungsparameter werden auf Basis der Differenz im Donorvermögen von Methanol und Wasser als Solventien diskutiert. Die Diagramme der thermodynamischen Parameter gegen die ionischen Potentiale (Z ²/r) der Lanthaniden sind, wie nach der Ionentheorie zu erwarten, nicht linear. Die erhaltene Kurve läßt eine Anfangsgruppe (die leichteren Lanthaniden), eine mittlere Gruppe (Sm-Dy) und eine Endgruppe (die schwereren Lanthaniden. Tb-Lu) erkennen. Dieses Verhalten kann aus dem Unterschied im Dehydratationsverhalten erklärt werden.

     

Voltammetry of carbocations stabilized by coordination with tetrahedral molybdenum- and tungsten-carbon clusters. [Cp2M2(CO)4-μ-η2:η3-(HCCCR1R2)]+BF4 −(M = Mo,W; R1, R2 = H,Me, and Pri) complexes

The electrochemical reduction of the carbocationic complexes [Cp₂M₂(CO)₄--₂:₃(HCCCR¹R²)]+BF₄ ^–, where M/R¹, R² = Mo/H, H (¹⁺), Mo/H, Me (2 ⁺), Mo/Me, Me (3⁺), Mo/H, Prⁱ (4⁺), has been studied by polarography and cyclic voltammetry on a Hg-electrode in THF solution. It has been suggested that carbocationic center-directed reversible two-electron reduction of1 ⁺–4 ⁺ takes place according to an ECE-mechanism and results in the carbanionic complexes [Cp₂M₂(CO)₄--²:³-(HCCCR¹R²)] (1 ^––4 ^–) as final productsvia carbon-centered radicals as intermediates. Anions1 ^–-4 ^– are capable of irreversible two-electron reduction at more negative potentials or protonation resulting in their transformation into the corresponding acetylene complexes [Cp₂M₂(CO)₄(HCCCHR¹R²)], which are also capable of irreversible two-electron reduction. Anions1 ^––4 ^– and their protonated forms are reduced with cleavage of the Mo-Mo bond. The reduction pathways of complexes1 ⁺,2 ⁺, and4 ⁺ with C-H bonds at the carbon atom of the carbocationic center are different on a Pt-electrode. It is suggested that this difference is due to the abstraction of a H-atom from the intermediate radical species by platinum.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 417–422, March, 1994.     

IR study of the peculiarities of the stabilization of the NH4Na-Y zeolite structure during its hydrothermal dealumination

The variations in the structure of deep-level calcinated NH₄Na-Y zeolite (68 % NH₄ ⁺, Si/Al = 2.56) at 873 K (stage I of the hydrothermal dealumination) as a result of ammonation and subsequent calcination in water vapor at 973 and 1023 K (stageII) were studied using the IR spectra of zeolite framework vibrations. It was shown that ammonation of the product of stageI promotes the formation of linear disiloxane bonds and extra-framework =Al^VI-OH species identified by absorption at 482, 1196 cm^–1, and 524, 612, 829 cm^–1. The ammonation is also accompanied by an increase in the excessive negative framework charge (ENFC), which is manifested in the high-frequency (HF) shift of the bands that have maxima in thev _as (TO₄) region and equals 10 cm^–1, and also by a decrease in the unit cell parameter (a ₀) by 0.14 Å. The decrease in both the ENFC anda ₀ for the products of stageII, v _as (TO₄) = 10–20 cm^–1 and a ₀ = 0.07–0.14 Å, is due to the formation of nonlinear disiloxane bonds and non-framework aluminum hydroxide species identified by the absorption bands at 478, 1173 cm^–1 and 530, 615, 835 cm^–1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 660–664, April, 1993.     

Heteronuclear diatomic transition-metal cluster ions in the gas phase: Reactivity and thermochemistry of AgFe+

The gas-phase chemistry of AgFe⁺ was studied by using Fourier transform ion cyclotron resonance mass spectrometry. AgFe⁺ is unreactive with alkanes but reacts with cyclic and linear (C4–C8) alkenes. The primary reactions are dominated by dehydrogenation and condensation. In addition, cluster splitting is observed in the reaction of AgFe⁺ with benzene. Secondary reactions generally involve cluster splitting with the loss of Ag, although AgFeC₅H ₆ ⁺ is observed to dehydrogenate cyclopentene to yield AgFeC₁₀H ₁₂ ⁺ . Ion-molecule reactions, collision-induced dissociation, and photodissociation experiments were used to determine the bond energiesD°(Fe⁺–Ag)=53±7 kcal/mol andD°(Ag⁺–Fe)=46±7 kcal/mol. These values in turn were used to calculateH _f (AgFe⁺)=296±7 kcal/mol andIP(AgFe)=6.5±0.3 eV. Related chemical and physical properties of CuFe⁺ are presented for comparison.     

Isothiocyanatooxomolybdenum(V) dithiocarbamates

Summary Isothiocyanatooxomolybdenum(V) complexes, [MoO-(NCS)(R₂dtc)₂] (R=ethyl or dibenzyl; R₂=piperidinyl or 4-morpholinyl) have been prepared and characterized. The i.r. spectral bands at 2020 cm^–1 are assigned tov(CN) which suggest that thiocyanate coordinates through nitrogen. The bands at 930, 1500 and 960 cm^–1 are attributed tov(MoO),v(CN) andv(CS), respectively, and indicate the presence of the MoO³⁺ moiety and a bidentate dithiocarbamate group. The e.p.r. and electronic spectral data together with magnetic moment values (1.69 B.M.) suggest the presence of one unpaired electron. The complexes are monomeric. The thermal decomposition behaviour of the complexes is reported.     

Crystal structure refinement of basic tellurium nitrate: A reformulation as (Te2O4H)+(NO3)−

Basic tellurium nitrate crystallizes in the space group Pnma witha=14.607 (1),b=8.801 (1), andc=4.4633 (4) Å. Full-matrix least-squares refinement of automatic diffractometer data converged to a residualR=0.036 (R _w =0.046) for 899 independent reflections. A detailed analysis of the structural data leads us to reformulate this compound as (Te₂O₄H)⁺(NO₃)^– with a basic structural element consisting of a charged two-dimensional puckered Te₂O₄H⁺ network with discrete NO₃ ^– anions, an example of apositively-charged network structure.

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Verfeinerung der Kristallstruktur von basischem Telluriumnitrat. Eine Umformulierung in (Te₂O₄H)⁺(NO₃)^–

Zusammenfassung Basisches Telluriumnitrat kristallisiert in der Raumgruppe Pnma mita=14,607 (1),b=8,801 (1) undc=4,4633 (4) Å. Die verfeinernde Auswertung der Diffraktometerdaten konvergierte zuR=0,036 (R _w =0.046) für 899 unabhängige Reflexe. Eine detaillierte Analyse der Strukturdaten führte zu einer Umformulierung dieser Verbindung als (Te₂O₄H)⁺(NO₃)^–, wobei die Basisstruktur aus einem geladenen, zweidimensionalen, gefalteten Te₂O₄H⁺ Netzwerk mit getrennten NO₃ ^– Anionen besteht. Es stellt dies ein Beispiel einerpositiv geladenen Netzstruktur dar.

     

X-Ray Diffraction Study of Cs5(HSO4)3(H2PO4)2, a New Solid Acid with a Unique Hydrogen-Bond Network

Solid solution investigations in the CsHSO₄–CsH₂PO₄system, carried out as part of an ongoing effort to elucidate the relationship between proton conduction, hydrogen bonding, and phase transitions, yielded the new compound Cs₅(HSO₄)₃(H₂PO₄)₂. Single-crystal X-ray diffraction methods revealed that Cs₅(HSO₄)₃(H₂PO₄)₂crystallizes in space groupC2/c(or possiblyCc), has lattice parametersa=34.066(19) Å,b=7.661(4) Å,c=9.158(6) Å, andβ=90.44(6)°, a unit cell volume of 2389.9(24) ų, a density of 3.198 Mg m⁻³, and four formula units in the unit cell. Sixteen non-hydrogen atoms and five hydrogen sites were located in the asymmetric unit, the latter on the basis of geometric considerations rather than from Fourier difference maps. Refinement using anisotropic temperature factors for all non-hydrogen atoms and fixed isotropic temperature factors for all hydrogen atoms yielded residuals based onF²(weighted) andFvalues, respectively, of 0.0767 and 0.0340 for observed reflections [F²>2σ(F²)]. The structure contains layers of (CsH₂XO₄)₂that alternate with layers of (CsHXO₄)₃, whereXis P or S. The arrangement of Cs, H, andXO₄groups within the two types of layers is almost identical to that in the end-member compounds, CsH₂PO₄and CsHSO₄-II, respectively. Although P and S each reside on two of the threeXatom sites in Cs₅(HSO₄)₃(H₂PO₄)₂, the number of protons in the structure appears fixed. In addition, the correlation of S–O and S–OH bond distances with O···O distances, where the latter represents the distance between two hydrogen-bonded oxygen atoms, was determined from a review of literature data.     

Preparation,Characterization and Standard enthalpy of formation of Sr2CeO4.

Sr₂CeO₄ has been prepared by sol-combustion and co-precipitate routes and the resulting products have been characterized by XRD analysis. The molar enthalpies of solution of Sr₂CeO₄(s), Sr(NO₃)₂(s) and Ce(NO₃)₃·6H₂O(s) in 0.150 dm^–3 of (4.41 mol dm–3 H₂O₂+4.23 mol dm^–3 of HNO₃) solvent as well as the molar enthalpies of solution of Sr₂CeO₄(s), SrCl₂(s) and CeCl₃(s) in 0.150 dm³ of (1.47 mol dm^–3 H₂O₂+3.05 mol dm^–3 of HClO₄) solvent have been measured using an isoperibol type calorimeter. From these results and other auxiliary data, the standard molar enthalpy of formation of Sr₂CeO₄ has been derived to be –2277.3±3.1 kJ mol^–1 at 298.15 K. This is the first reported thermodynamic data on this compound.     

Spectroscopic Study of the Interaction of the Pd(acac)(C3-acac)PPh3Complex with BF3OEt2 in the Presence of PPh3

The interaction between the components of a catalytic system Pd(acac)(C³-acac)PPh₃+nPPh₃+ mBF₃OEt₂(where n= 1–4, m= 0.25–4, and acac is the acetylacetonate ligand) in benzene is examined by UV and IR spectroscopy. With a relative excess of PPh₃(n> m), acacH and [Pd(acac)(PPh₃)₂]⁺BF^– ₄were the main products, whereas BF₂acac and a polynuclear complex of PdF₂with PPh₃also containing Pd²⁺(BF^– ₄)₂units were formed with a relative excess of BF₃OEt₂(n< m).     

Hexamethylphosphorsäuretriamid als Ligand, 3. Mitt.: Umsetzungen von [Co(HMPT)4]2+ mit Rhodanid-, Cyanid- und Azidionen

Zusammenfassung Auf Grund spektrophotometrischer, potentiometrischer und konduktometrischer Befunde entstehen aus [Co(HMPT)₄]²⁺ in Hexamethylphosphorsäuretriamid (HMPT) bei Zusatz von Pseudohalogenidionen folgende Koordinationsformen: [Co(HMPT)₃N₃]⁺, [Co(HMPT)₂(N₃)₂], [Co(HMPT)(N₃)₃]^–, [Co(N₃)₄]^2–, [Co(HMPT)₃NCS]⁺, [Co(HMPT)₂(NCS)₂], [Co(HMPT)(NCS)₃]^–, [Co(NCS)₄]^2–, [Co(HMPT)₂(CN)₂], [Co(HMPT)(CN)₃]^–, [Co(HMPT)(CN)₅]^3–.

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Hexamethyl phosphoric triamide as a ligand, III: Reactions of [Co(HMPT)₄]²⁺ with rhodanide, cyanide, and azide ions, resp

Spectrophotometric, potentiometric and conductometric results indicate that addition of pseudohalide ions to [Co(HMPT)₄]²⁺ in hexamethylphosphoramide (HMPT) leads to the following coordination forms: [Co(HMPT)₃N₃]⁺, [Co(HMPT)₂(N₃)₂], [Co(HMPT)(N₃)₃]^–, [Co(N₃)₄]^2–, [Co(HMPT)₃NCS]⁺, [Co(HMPT)₂(NCS)₂], [Co(HMPT)(NCS)₃]^–, [Co(NCS)₄]^2–, [Co(HMPT)₂(CN)₂], [Co(HMPT)(CN)₃]^–, [Co(HMPT)(CN)₅]^3–.

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Mit 7 Abbildungen

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2. Mitt.:V. Gutmann undA. Weisz, Mh. Chem.100, 2104 (1969).     

Syntheses and pharmacological characterization of achiral and chiral enantiopure C/Si/Ge-analogous derivatives of the muscarinic antagonist cycrimine: a study on C/Si/Ge bioisosterism

The C/Si/Ge-analogous compounds rac-Ph(c-C₅H₉)El(CH₂OH)CH₂CH₂NR₂ (NR₂=piperidino; El=C, rac-3a; El=Si, rac-3b; El=Ge, rac-3c) and (c-C₅H₉)₂El(CH₂OH)CH₂CH₂NR₂ (NR₂=piperidino; El=C, 5a; El=Si, 5b; El=Ge, 5c) were prepared in multi-step syntheses. The (R)- and (S)-enantiomers of 3a–c were obtained by resolution of the respective racemates using the antipodes of O,O′-dibenzoyltartaric acid (resolution of rac-3a), O,O′-di-p-toluoyltartaric acid (resolution of rac-3b), or 1,1′-binaphthyl-2,2′-diyl hydrogen phosphate (resolution of rac-3c). The enantiomeric purities of (R)-3a–c and (S)-3a–c were ≥98% ee (determined by ¹H-NMR spectroscopy using a chiral solvating agent). Reaction of rac-3a–c, (R)-3a–c, (S)-3a–c, and 5a–c with methyl iodide gave the corresponding methylammonium iodides rac-4a–c, (R)-4a–c, (S)-4a–c, and 6a–c (3a–c→4a–c; 5a–c→6a–c). The absolute configuration of (S)-3a was determined by a single-crystal X-ray diffraction analysis of its (R,R)-O,O′-dibenzoyltartrate. The absolute configurations of the silicon analog (R)-4b and germanium analog (R)-4c were also determined by single-crystal X-ray diffraction. The chiroptical properties of the (R)- and (S)-enantiomers of 3a–c, 3a–c·HCl, and 4a–c were studied by ORD measurements. In addition, the C/Si/Ge analogs (R)-3a–c, (S)-3a–c, (R)-4a–c, (S)-4a–c, 5a–c, and 6a–c were studied for their affinities at recombinant human muscarinic M₁, M₂, M₃, M₄, and M₅ receptors stably expressed in CHO-K1 cells (radioligand binding experiments with [³H]N-methylscopolamine as the radioligand). For reasons of comparison, the known C/Si/Ge analogs Ph₂El(CH₂OH)CH₂CH₂NR₂ (NR₂=piperidino; El=C, 7a; El=Si, 7b; El=Ge, 7c) and the corresponding methylammonium iodides 8a–c were included in these studies. According to these experiments, all the C/Si/Ge analogs behaved as simple competitive antagonists at M₁–M₅ receptors. The receptor subtype affinities of the individual carbon, silicon, and germanium analogs 3a–8a, 3b–8b, and 3c–8c were similar, indicating a strongly pronounced C/Si/Ge bioisosterism. The (R)-enantiomers (eutomers) of 3a–c and 4a–c exhibited higher affinities (up to 22.4 fold) for M₁–M₅ receptors than their corresponding (S)-antipodes (distomers), the stereoselectivity ratios being higher at M₁, M₃, M₄, and M₅ than at M₂ receptors, and higher for the methylammonium compounds (4a–c) than for the amines (3a–c). With a few exceptions, compounds 5a–c, 6a–c, 7a–c, and 8a–c displayed lower affinities for M₁–M₅ receptors than the related (R)-enantiomers of 3a–c and 4a–c. The stereoselective interaction of the enantiomers of 3a–c and 4a–c with M₁–M₅ receptors is best explained in terms of opposite binding of the phenyl and cyclopentyl ring of the (R)- and (S)-enantiomers. The highest receptor subtype selectivity was observed for the germanium compound (R)-4c at M₁/M₂ receptors (12.9-fold).     

Palladium acetate complexes bearing chelating N-heterocyclic carbene (NHC) ligands: Synthesis and catalytic oxidative homocoupling of terminal alkynes

The imidazolium salts 1,1′-dibenzyl-3,3′-propylenediimidazolium dichloride and 1,1′-bis(1-naphthalenemethyl)-3,3′-propylenediimidazolium dichloride have been synthesized and transformed into the corresponding bis(NHC) ligands 1,1′-dibenzyl-3,3′-propylenediimidazol-2-ylidene (L₁) and 1,1′-bis(1-naphthalenemethyl)-3,3′-propylenediimidazol-2-ylidene (L₂) that have been employed to stabilize the Pd^II complexes PdCl₂(κ²-C,C-L₁) (2a) and PdCl₂(κ²-C,C-L₂) (2b). Both latter complexes together with their known homologous counterparts PdCl₂(κ²-C,C-L₃) (1a) (L₃ = 1,1′-dibenzyl-3,3′-ethylenediimidazol-2-ylidene) and PdCl₂(κ²-C,C-L₄) (1b) (L₄ = 1,1′-bis(1-naphthalenemethyl)-3,3′-ethylenediimidazol-2-ylidene) have been straightforwardly converted into the corresponding palladium acetate compounds Pd(κ¹-O-OAc)₂(κ²-C,C-L₃) (3a) (OAc = acetate), Pd(κ¹-O-OAc)₂(κ²-C,C-L₄) (3b), Pd(κ¹-O-OAc)₂(κ²-C,C-L₁) (4a), and Pd(κ¹-O-OAc)₂(κ²-C,C-L₂) (4b). In addition, the phosphanyl-NHC-modified palladium acetate complex Pd(κ¹-O-OAc)₂ (κ²-P,C-L₅) (6) (L₅ = 1-((2-diphenylphosphanyl)methylphenyl)-3-methyl-imidazol-2-ylidene) has been synthesized from corresponding palladium iodide complex PdI₂(κ²-P,C-L₅) (5). The reaction of the former complex with p-toluenesulfonic acid (p-TsOH) gave the corresponding bis-tosylate complex Pd(OTs)₂(κ²-P,C-L₅) (7). All new complexes have been characterized by multinuclear NMR spectroscopy and elemental analyses. In addition the solid-state structures of 1b·DMF, 2b·2DMF, 3a, 3b·DMF, 4a, 4b, and 6·CHCl₃·2H₂O have been determined by single crystal X-ray structure analyses. The palladium acetate complexes 3a/b, 4a/b, and 6 have been employed to catalyze the oxidative homocoupling reaction of terminal alkynes in acetonitrile chemoselectively yielding the corresponding 1,4-di-substituted 1,3-diyne in the presence of p-benzoquinone (BQ). The highest catalytic activity in the presence of BQ has been obtained with 6, while within the series of palladium-bis(NHC) complexes, 4b, featured with a n-propylene-bridge and the bulky N-1-naphthalenemethyl substituents, revealed as the most active compound. Hence, this latter precursor has been employed for analogous coupling reaction carried out in the presence of air pressure instead of BQ, yielding lower substrate conversion when compared to reaction performed in the presence of BQ. The important role of the ancillary ligand acetate in the course of the catalytic coupling reaction has been proved by variable-temperature NMR studies carried out with 6 and 7′ under catalytic reaction conditions.     

Formation of various polymeric frameworks by dicarboxylate-like ligands: Synthesis and crystal structures of polymeric complexes of sodium perchlorate with flexible double betaines

Three crystalline complexes of sodium perchlorate with different flexible double betaines [Na ₂(L¹)(ClO₄)(H₂O) _n ](ClO₄) _n (1), [Na ₃(L²)(ClO₄)₃(H₂O)_{2 n} ] (2), and [Na(L ³)(CH₃OH)_n]-(ClO₄) _n ·xnH₂O (x=0.25) (3) [^–O₂CCH₂N⁺Me₂–(CH₂) _n -N⁺Me₂CH₂CO₂ ^–,n=2 L¹;n=3 L²;n=4 L³] have been synthesized and characterized by single-crystal X-ray structure analysis. Complex (1) comprises tetranuclear sodium units consolidated by betaine and aqua ligands, which are bridged by half of the ClO₄ ^– anions to form layers matching the (200) planes, the remaining uncoordinated ClO₄ ^– anions being accommodated between adjacent layers. Complex (2) possesses a double-layer polymeric structure with the sodium atoms bridged by ligand oxygen atoms to form columns running parallel to thea axis, which are interconnected by double-betaine ligands lying parallel to theac plane. All of the ClO₄ ^– groups and water molecules are coordinated to the metal atoms. In complex (3) the chains composed of alternating eight-membered and four-membered metallocycles are cross-linked by the betaine ligands, which lie in the (020) and (01/1) families of planes, to yield a three-dimensional network. All of the ClO₄ ^– groups and water molcules fill the resulting infinite channels running parallel to thea axis. Two unusual carboxylate coordination modes are identified, namely ₃-O andhapto-3-O plushapto-2-O in (1) and (2), respectively.     

Hydrothermal synthesis and structural characterization of three inorganic–organic composite sandwich-type phosphotungstates

Three inorganic–organic composite sandwich-type phosphotungstates [Ni(tepa)(H₂O)]₄H₂[Ni₄(H₂O)₂(α-B-PW₉O₃₄)₂]·8H₂O (1), (enH₂)₃[Ni₂(H₂O)₁₀][Ni₄(H₂O)₂(α-B-PW₉O₃₄)₂]·en·8H₂O (2) and (enH₂)₁₀[Mn₄(H₂O)₂(α-B-PW₉O₃₄)₂]₂·20H₂O (3) (tepa=tetraethylenepentamine and en=ethylenediamine) have been synthesized by the hydrothermal reaction of the trivacant Keggin polyoxoanion [α-A-PW₉O₃₄]⁹⁻ with Ni²⁺ or Mn²⁺ ions in the presence of tepa or en and structurally characterized by IR spectra, elemental analysis, thermogravimetric analysis and variable temperature magnetic susceptibility. X-ray crystallographic analyses indicate that they all contain the classical tetra-M sandwiched polyoxoanions [M₄(H₂O)₂(α-B-PW₉O₃₄)₂]¹⁰⁻ (M=Ni²⁺ or Mn²⁺) and nickel-organoamine cations or organoamine cations work as the charge balance ions. The tetra-M clusters in 1, 2 and 3 exhibit the familiar structural type of a β-junction at the sites of metal incorporation. The study of magnetic property of 1 is indicative of a typical ferromagnetic coupling between Ni²⁺ cations.     

Effect of the Supporting-Electrolyte Cation on the Chloroplatinite Ion Reduction at a Dropping Mercury Electrode

The effect of nature and concentration of supporting-electrolyte cations (Li⁺, Na⁺, Cs⁺, (CH₃)₄N⁺, Ca²⁺, Ba²⁺) on electroreduction kinetics of PtCl^2- ₄at a dropping mercury electrode is studied. The electroreduction wave for PtCl^2- ₄is complicated by a polarographic maximum of first kind followed by a pronounced plateau of limiting current, after which the current passes through a minimum. The electroreduction occurs probably via two different mechanisms and presumably involves the same species, because the charge z _iof discharging species, determined by the Frumkin–Petrii method, remains virtually constant (z _i –1) on both descending (E= –0.6 to –1.0 V vs. SCE) and ascending (–1.3 to –1.6 V) branches of polarization curves and is independent of the nature of the supporting-electrolyte cation. The mechanism is presumably changed by a changed orientation of discharging species relative to the electrode surface.     

Adduct of nonamethylferrocenecarbaldehyde with HBF4 and its transformations

Some reactions of the adduct of nonaniethylferrocenecarbaldehyde with HBF₄, [Me₅C₅FeC₅Me₄CH⁺(OH)]BF₄ ^–, and its transformation into the paramagnetic complex [Me₅C₅Fe^+-C₅Me₄CH=O]BF₄ ^– were studied. The structure of the complex was established from the chemical properties, the data from IR spectroscopy, mass spectrometry, and¹H,¹³C, and¹⁹F NMR spectroscopy and confirmed by independent synthesis.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp, 2979–2983, December, 1996.     

Äthylensulfit als Lösungsmittel, 1. Mitt.: Halogenokomplexe von Kobalt (II)

Zusammenfassung Die Bildung von Chloro-, Bromo- und Jodokomplexen von Co²⁺ wurde in Äthylensulfit (ES) auf spektrophotometrischem, potentiometrischem und konduktometrischem Wege untersucht. Folgende Komplexformen dürften gebildet werden: [CoCl(ES)₅]⁺, CoCl₂(ES)₂, [CoCl₃ ES]^–, [CoCl₄]^2–, [CoBr(ES)₅]⁺, CoBr₂(ES)₂, [CoBr₄]^2– und [CoJ₄]^2–. Die Ergebnisse werden hinsichtlich der des Lösungsmittels und des sterischen Baues des Lösungsmittelmoleküles mit denen in anderen Lösungsmitteln verglichen und diskutiert.

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Reactions involving the formation of complex species of Co²⁺ with chloride, bromide and iodide ions have been investigated by spectrophotometric, potentiometric and conductometric methods using ethylene sulphite (ES) as solvent. The following complexes appear to be formed: [CoCl(ES)₅]⁺, CoCl₂(ES)₂, [CoCl₃ ES]^–, [CoCl₄]^2–, [CoBr(ES)₅]⁺, CoBr₂(ES)₂, [CoBr₄]^2– and [CoI₄]^2–. The influence of the donor number of the solvent and steric contributions by the solvent molecules are discussed.

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Mit 8 Abbildungen     

Electrocatalytic applications of a sol–gel derived cobalt phthalocyanine–dispersed carbon–ceramic electrode

The preparation and characterization of a surface renewable carbon–ceramic electrode, SiO₂/SnO₂/C-graphite/(SiPy⁺)₄CoPcTs⁻⁴, is reported. Cobalt(II) tetrasulfonated phthalocyanine (CoPcTs⁻⁴) absorbed on a 3-n-propylpyridinium chloride silsesquioxane polymer was dispersed in a stannic-silica C-graphite sol–gel matrix. The performance of SiO₂/SnO₂/C-graphite/(SiPy⁺)₄CoPcTs⁻⁴ as electrode material was investigated by cyclic voltammetry in the electrocatalytic oxidation of oxalic acid and nitrite. The modified carbon–ceramic material was characterized by X-ray fluorescence spectroscopy, BET specific surface area, thermogravimetric analysis, X-ray photoelectron spectroscopy, and scanning electron microscopy.     

Comparison of temperature,pressure and isotope effects on the proton jump between the hydroxide and oxonium ion

The limiting molar conductances ° of potassium deuteroxide KOD in D₂O and potassium hydroxide KOH in H₂O were determined at 5 and 45°C as a function of pressure to clarify the difference in the temperature, pressure and isotope effects on the proton jump between an OD^– (OH^–) and a D₃O⁺ (H₃O⁺) ion. The excess conductances of the OD^– ion in D₂O and the OH^– ion in H₂O, _E ⁰ (OD^-) and _E ⁰ (OH^-), increase with increasing temperature and pressure as in the case of the excess deuteron and proton conductances, _E ⁰ (D⁺) and _E ⁰ (H⁺). However, the temperature effect on the excess conductance is larger for the OD^–(OH^–) ion than for the D₃O⁺ (H₃O⁺) ion but the pressure effect is much smaller for the OD^– (OH^–) ion than for the D₃O⁺ (H₃O⁺) ion. These findings are correlated with larger activation energies and less negative activation volumes found for the OD^– (OH^–) ion than for the D₃O⁺ (H₃O⁺) ion. Concerning the isotope effect, the value of _E ⁰ (OH^-)/ _E ⁰ (OD^-) deviates considerably from at each temperature and pressure in contrast with that of _E ⁰ (H⁺)/ _E ⁰ (D⁺), although both of them decrease with increasing temperature and pressure. These results are discussed mainly in terms of the difference in repulsive force between the OD^– (OH^–) or the D₃O⁺ (H₃O⁺) ion and the adjacent water molecule, the difference in strength of hydrogen bonds in D₂O and H₂O, and their variations with temperature, pressure, and isotope.