Synergism in cationic gemini – additive systems

A series of dicationic gemini surfactants with the general formula C₁₆H₃₃(CH₃)₂N⁺?(CH₂)_s?N⁺(CH₃)₂C₁₆H₃₃, 2Br^? (where s?=?4–6), designated as 16-s-16, were synthesised. Their interaction with organic additives: n-alcohols (C₃H₇OH, C₇H₁₅OH, C₈H₁₇OH) and the corresponding amines (C₃H₇NH₂, C₇H₁₅NH₂, C₈H₁₇NH₂) in the absence and presence of KNO₃ at 30°C was studied viscometrically to observe their effect on assembly formation and micellar transition. The simultaneous presence of KNO₃ and organics induced rich aggregates morphologies in the gemini micellar systems by giving high viscosity values. On comparing the behaviour of the gemini surfactant series for a given alkyl chain length of the organic additive, the spacer is found to markedly influence the behaviour; shorter the spacer, earlier the sphere-to-rod transition. In the case of the conventional surfactant, CTAB, the concentration of KNO₃ used with the geminis was insufficient to induce any transition.     

Micellization of monomeric and dimeric (gemini) surfactants in polar nonaqueous-water-mixed solvents

Dimeric or gemini surfactants are novel surfactants that are finding a great deal of discussion in the academic and industrial arena. They consist of two hydrophobic chains and two polar head groups covalently linked by a spacer. Data on critical micelle concentration (cmc) and degree of counterion dissociation (α) are reported on bis-cationic C₁₆H₃₃N⁺(CH₃)₂–(CH₂)_s–N⁺(CH₃)₂C₁₆H₃₃, 2Br⁻, referred to as 16-s-16, for spacer lengths s=4, 5, 6 in aqueous and in polar nonaqueous (1-propanol, 2-methoxyethanol or methyl cellosolve, dimethyl sulfoxide, acetonitrile)-water-mixed solvents. The behavior is compared with conventional monomeric surfactant cetyltrimethylammonium bromide (CTAB). Thermodynamic parameters are obtained from the temperature dependence of the cmc values. It is observed that micellization tendency of the surfactants decreases in the presence of polar nonaqueous solvents. However, detailed studies with dimethylsulfoxide (DMSO) show that the geminis nearly outclass the micellization-arresting property of this solvent. Also, within geminis, higher spacer length is found suitable for showing micellization even with high DMSO content (50% v/v). The implications of these results of gemini micellization may be useful in micellar catalysis in polar nonaqueous solvents.     

Growth of Gemini Surfactant Micelles Under the Influence of Additives: DLS Studies

Results are presented on the first extensive study on the influence of additives on the growth of gemini; alkanediyl α, ω - bis(dimethylcetylammonium bromide) surfactant micelles (16-s-16, with s = 5, 6); as measured by dynamic light scattering technique at 30°C. The effect of adding n-butanol, n-pentanol, n-hexanol, and n-hexylamine in the absence or presence of general ionic salt potassium bromide on 0.03 M gemini solutions were observed. The tendency for micelles to grow from spherical to rodlike structures is decisively influenced by the spacer length s. At 30°C, the micellar growth was more for s being 5, which has been interpreted in terms of short spacer having strong propensity for micellar growth. Addition of KBr plays a role in screening of the electrostatic interactions, thus promoting a change of morphology of the aggregates and giving rise to high hydrodynamic diameter (D _h ) values. The micellar growth in presence of alcohols is interpreted in terms of the formation of the gemini–alcohol mixed micelles which followed the pattern C₆OH>C₅OH>C₄OH. For equal chain length additives C₆OH and C₆NH₂, the growth was more pronounced in case of alcohol. Also, in case of C₆NH₂, the value of D _h reached to almost constancy or decreased to some extent, which is discussed in terms of its partitioning in aqueous phase. A combined presence of KBr and n-alcohols or n-hexylamine produced favorable conditions for micellar growth due to synergistic effect.     

An ab initio molecular orbital study of the deprotonation of amines

The geometries of the amines NH₂X and amido anions NHX^?, where X = H, CH₃, NH₂, OH, F, C₂H, CHO, and CN have been optimized using ab initio molecular orbital calculations with a 4-31G basis set. The profiles to rotation about the N? X bonds in CH₃NH^?, NH₂NH^?, and HONH^? are very similar to those for the isoprotic and isoelectronic neutral compounds CH₃OH, NH₂OH, and HOOH. The amines with unsaturated bonds adjacent to the nitrogen atoms undergo considerable skeletal rearrangement on deprotonation such that most of the negative charge of the anion is on the substituent. The computed order of acidity for the amines NH₂X is X = CN > HCO > F ≈ C₂H > OH > NH₂ > CH₃ > H and for the reaction NHX^? + H⁺ → NH₂X the computed energies vary over the range 373–438 kcal/mol.     

Catalytic role of gemini surfactant micelles in the ninhydrin-L-isoleucine reaction

Effect of dicationic gemini surfactants C₁₆H₃₃(CH₃)₂N⁺-(CH₂) _s -N⁺(CH₃)₂C₁₆H₃₃, 2Br⁻ (where s = 4, 5, 6) on the reaction of ninhydrin with L-isoleucine has been investigated spectrophotometrically as a function of [gemini], [L-isoleucine], [ninhydrin], and pH. The reaction follows first- and fractional-order kinetics, respectively, in [L-isoleucine] and [ninhydrin]. The gemini surfactant micellar media are found more effective for the reaction than their conventional monomeric counterpart CTAB. Furthermore, whereas typical rate constant (k _ψ) increase and leveling-off regions are observed with CTAB and geminis, the latter produce a third region of increasing k _ψ at concentrations ≥ 60 cmc’s. ¹H NMR studies reveal that this unusual third-region effect of the geminis is due to changes in their micellar morphologies. Quantitative kinetic analysis has been performed on the basis of modified pseudo-phase model.     

Salt effects on the aggregation behavior of tripolar zwitterionic surfactants with different inter-charge spacers in aqueous solution

Salt effects on the aggregation behavior of tripolar zwitterionic surfactants in aqueous solutions have been investigated using surface tension, dynamic light scattering (DLS), freeze-fracture transmission electron microscopy (FF-TEM), and ¹H NMR. The tripolar zwitterionic surfactants with different inter-charge spacers are [C₁₄H₂₉(CH₃)₂N⁺C_sN⁺(CH₃)₂CH₂CH₂CH₂SO₃ ^?]Br^? (C₁₄C_sTri, C_s?=?–(CH₂)₂–, –(CH₂)₆–, –(CH₂)₁₀–, and p-xylyl). It is found that the critical micelle concentration (CMC) values of the corresponding traditional zwitterionic surfactant C₁₄H₂₉(CH₃)₂N⁺CH₂CH₂CH₂SO₃ ^? (TPS) are almost constant with the increase of the NaBr concentration. However, the CMC values of C₁₄C_sTri decrease sharply at a lower NaBr concentration and then level off at a higher NaBr concentration. Moreover, the decreasing extents of the CMC values for C₁₄C₂Tri, C₁₄C₆Tri, and C₁₄C_pxTri are very close, but more significant than that for C₁₄C₁₀Tri, suggesting that the self-assembly ability of the tripolar zwitterionic surfactants with a longer inter-charge spacer is less sensitive to NaBr. The DLS and FF-TEM results reveal that C₁₄C₂Tri, C₁₄C₆Tri, and C₁₄C_pxTri form micelles without NaBr and that the size slightly increases with the increase of NaBr concentration, whereas micelles and vesicles coexist for C₁₄C₁₀Tri and TPS without NaBr and then transfer to micelles upon the addition of NaBr. The salt-induced morphological transition for C₁₄C₁₀Tri is further studied using ¹H NMR. The addition of NaBr reduces both the electrostatic repulsion between the same charged ammoniums and the electrostatic attraction between the oppositely charged ammonium and sulfonate. Thus, the longer inter-charge spacer of C₁₄C₁₀Tri tends to be more bended and the sulfonate group becomes available to contact the ammonium, which promotes micellization.     

Effect of dicationic gemini surfactants 16–s‐16 (s = 4, 5, 6) on the ninhydrin‐dipeptide (glycyl‐tyrosine) reaction

The effect of dicationic gemini surfactants H₃₃C₁₆(CH₃)₂N⁺‐(CH₂)_s‐N⁺(CH₃)₂ C₁₆H₃₃, 2Br^? (s= 4, 5, 6) on the reaction of a dipeptide glycyl–tyrosine (Gly–Tyr) with ninhydrin has been studied spectrophotometrically at 70°C and pH 5.0. The reaction follows first‐ and fractional‐order kinetics, respectively, in [Gly–Tyr] and [ninhydrin]. The gemini surfactant micellar media are comparatively more effective than their single chain–single head counterpart cetyltrimethylammonium bromide (CTAB) micelles. Whereas typical rate constant (k_Ψ) increase and leveling‐off regions, just like CTAB, are observed with geminis, the latter produces a third region of increasing k_Ψ at higher concentrations. This subsequent increase is ascribed to the change in the micellar morphology of the geminis. The pseudophase model of micelles was used to quantitatively analyze the k_Ψ ? [gemini] data, wherein the micellar‐binding constants K_S for [Gly–Tyr] and K_N for ninhydrin were evaluated. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 800–809, 2012     

Novel glucose derived non-ionic gemini surfactants as reverse micellar systems for encapsulation of d- and l-enantiomers of some aromatic α-amino acids in n-hexane

Novel glucose-based non-ionic gemini amphiphiles comprising two sugar head groups, two hydrophobic tails having chain length of C₁₂, C₁₄, and C₁₈ and a –CH₂–Ar–CH₂– spacer have been synthesized. The head groups of the geminis consist of glucose entities (with reducing function blocked in cyclic acetal group) connected through C-6 to tertiary amines. These amphiphiles were explored as reverse micellar systems, for the encapsulation of d- and l-enantiomers of ultraviolet-absorbing aromatic α-amino acids histidine (H), phenylalanine (F), tyrosine (Y) and tryptophan (W) in n-hexane, without any added water. Reverse micellar studies revealed that aromatic α-amino acids were encapsulated in the sequence H?>?F?>?Y?>?W. In most cases, specifically for F, d-enantiomer was found better encapsulated than l-enantiomer in the reverse micellar probes of the gemini surfactants.     

The effect of twin‐tailed sidearms on sodium cation transport in synthetic hydraphile cation channels

The preparation of novel tris(macrocycle)s that transport Na⁺ through phospholipid bilayers is reported. All of the reported structures have the following structural elements: sidechain‐macrocycle‐spacer‐macro‐cycle‐spacer‐macrocycle‐sidechain. The overall extension of the channel system is defined by the lengths of the spacer chains. The flexible sidearms are thought to be aligned with the lipid axis and opposite to the spacer chains. To the extent the spacer chains contribute to organization of the structure and isolation of the cation‐containing pore from the surrounding lipid chains, more hydrophobic chains are expected to enhance cation transport. A comparison of C₁₂H₂₅<N18N>(CH₂)₁₂<N18N>(CH₂)₁₂<N18N> C₁₂H₂₅, 1, with (C₁₂H₂₅)₂N(CH₂)₂<N18N>(CH₂)₁₂<N18N>(CH₂)₁₂<N18N>(CH₂)2N(C₁₂H₂₅)₂, 11, shows that the Na⁺ transport is, indeed, enhanced.     

Effect of mixed thiols on the adsorption,capacitive and hybridization performance of DNA self-assembled monolayers on gold

In this article, we investigated the effect of mixed thiols (HS(CH₂)₅CH₃, HS(CH₂)₆OH and HS(CH₂)₂NH₂) on the adsorption, capacitive and hybridization performance of thiol-modified probe DNA self-assembled monolayers on gold by chronocoulometry (CC) and cyclic voltammetry (CV). Co-assembly of HS(CH₂)₅CH₃ with probe DNA availed DNA surface adsorption on gold more than HS(CH₂)₆OH and HS(CH₂)₂NH₂. With the increase of the assembly concentration ratio of probe DNA and mixed thiols (C _DNA/C _thiols), DNA surface coverage (Γ _m) was almost constant for DNA/HS(CH₂)₅CH₃ mixed SAMs and increased gradually for DNA/HS(CH₂)₆OH or DNA/HS(CH₂)₂NH₂ mixed SAMs. Interfacial capacitance (C _d) value of DNA/thiol-mixed SAMs on gold mainly depended on the capacitance of thiols SAMs. DNA hybridization almost did not change the capacitance value of DNA/thiol-mixed SAMs on gold. Hybridization experiments indicated that the maximal DNA hybridization density (H _D) was 1.2 × 10^?11 and 1.1 × 10^?11 mol cm^?2 with HS(CH₂)₅CH₃ or HS(CH₂)₆OH as mixed thiols respectively, much bigger than that with short-chain thiols (HS(CH₂)₂NH₂). The size fitting coefficient d _c/d _t values for the optimal hybridization of DNA/HS(CH₂)₅CH₃ and DNA/HS(CH₂)₆OH mixed SAMs were 0.70 and 0.93, respectively. This indicated that probe DNA with much bigger Γ _m should be co-assembled with HS(CH₂)₅CH₃ on gold to obtain the biggest H _D than with HS(CH₂)₆OH. These conclusions provided the important reference for optimally designing DNA sensor.     

A liquid membrane ammonium-selective electrode based on the tris(2-nitroso-4-chlorophenol)iron(II) anion

Liquid membrane electrodes based on ion-association extraction systems responding to the ammonium ion are described. The tris(2-nitroso-4-chlorophenol)iron(II) anion in a nitrobenzene solution gives an electrode exhibiting Nernstian response in the range 1–10^-4 M ammonium ion (slope, 60 mV) in solutions of pH 4–9. The order of the selectivity coefficients (K_ij) is N(CH₃)⁺₄ > NH(CH₃)⁺₃ > NH₂(CH₃)⁺₂ > NH₃CH⁺₃ > K⁺ > NH⁺₄ > Na⁺ > Li⁺.     

Stabilisation of reactive intermediates in molecular sieves

This paper presents studies on paramagnetic intermediates, free atoms and radicals produced in γ-irradiated molecular sieves and their reactions with adsorbate molecules or exchangeable cations. Four different systems have been investigated using EPR spectroscopy, Na-A/CH₄, AgNa-A/CH₃OH, Ag-SAPO-11/C₂H₄ and AgCs-rho/NH₃. It was found that methyl radicals are formed in two different sites in Na-A/CH₄ and in one of them they are stable at room temperature. The formation of Ag·CH₂OH⁺ radical cation with one-electron bond between silver and carbon has been established in AgNa-A/CH₃OH by EPR experiments with [¹³C]CH₃OH and DFT calculations. In Ag-SAPO-11/C₂H₄ the stabilisation of biligand silver/ethylene complex, Ag⁰(C₂H₄)₂ was postulated based on EPR and DFT results. Tetrameric silver clusters (Ag ₄ ³⁺ ) produced radiolytically in AgCs-rho/NH₃ strongly interact with two ammonia molecules as was deduced from the changes in superhyperfine structure of high-field EPR line of Ag ₄ ³⁺ pentet for zeolite exposed to [¹⁴N]NH₃ and [¹⁵N]NH₃. The presented examples clearly show that the combination of radiation methods with EPR technique is very useful to study the structure and reactivity of paramagnetic intermediates.     

Kinetics and mechanism of atmospheric reactions of partially fluorinated alcohols

Gas-phase reactions typical of the Earth’s atmosphere have been studied for a number of partially fluorinated alcohols (PFAs). The rate constants of the reactions of CF₃CH₂OH, CH₂FCH₂OH, and CHF₂CH₂OH with fluorine atoms have been determined by the relative measurement method. The rate constant for CF₃CH₂OH has been measured in the temperature range 258–358 K (k = (3.4 ± 2.0) × 10¹³exp(?E/RT) cm³ mol^?1 s^?1, where E = ?(1.5 ± 1.3) kJ/mol). The rate constants for CH₂FCH₂OH and CHF₂CH₂OH have been determined at room temperature to be (8.3 ± 2.9) × 10¹³ (T = 295 K) and (6.4 ± 0.6) × 10¹³ (T = 296 K) cm³ mol^?1 s^?1, respectively. The rate constants of the reactions between dioxygen and primary radicals resulting from PFA + F reactions have been determined by the relative measurement method. The reaction between O₂ and the radicals of the general formula C₂H₂F₃O (CF₃CH₂? and CF₃?HOH) have been investigated in the temperature range 258–358 K to obtain k = (3.8 ± 2.0) × 10⁸exp(?E/RT) cm³ mol^?1 s^?1, where E = ?(10.2 ± 1.5) kJ/mol. For the reaction between O₂ and the radicals of the general formula C₂H₄FO (? HFCH₂O, CH₂F?HOH, and CH₂FCH₂?) at T = 258–358 K, k = (1.3 ± 0.6) × 10¹¹exp(?E/RT) cm³ mol^?1 s^?1, where E = ?(5.3 ± 1.4) kJ/mol. The rate constant of the reaction between O₂ and the radicals with the general formula C₂H₃F₂O (?F₂CH₂O, CHF₂?HOH, and CHF₂CH₂?) at T = 300 K is k = 1.32 × 10¹¹ cm³ mol^?1 s^?1. For the reaction between NO and the primary radicals with the general formula C₂H₂F₃O (CF₃CH₂? and CF₃?HOH), which result from the reaction CF₃CH₂OH + F, the rate constant at 298 K is k = 9.7 × 10⁹ cm³ mol^?1 s^?1. The experiments were carried out in a flow reactor, and the reaction mixture was analyzed mass-spectrometrically. A mechanism based on the results of our studies and on the literature data has been suggested for the atmospheric degradation of PFAs.     

A spectroscopic study of the hydrolysis products of aryltellurium trihalides

The hydrolysis of aryltellurium trihalides to aryltellurium oxide halides in neutral aqueous media is considered to proceed in a stepwise manner in which the first stage involves the formation of a monomeric species. In alkaline media the initially isolated hydrolysis product analyses as (p-EtOC₆H₄)TeO(OH) and on treatment with dilute acid, affords the known (p-EtOC₆H₄TeO)₂O.The infrared spectra are assigned in the low frequency region for the compounds RTe(O)X (X = halogen), RTeO(OH) and (RTeO)₂O. It is argued that the probable coordination number for tellurium in RTe(O)X is four, and that a ring structure is likely. The preparation of the salts(C₅H₅NH⁺)(RTeCl₄^?) is reported and the anions are considered to have square-based pyramidal structures of approximately C_4v symmetry. The reaction of (C₅H₅NH⁺)(PhTeCl₄^?) with acetone affords Ph(CH₃COCH₂)TeCl₂.     

Jahn—Teller effects in the mindo approximation: structures of the molecular cations of methane and the chloromethanes

The MINDO/3 technique gives geometries for (CH₄)⁺, (CCl₄)⁺ and the intermediate ions (CH_nCl_{4 ? n})⁺ (n = 1, 2, 3) which have symmetries in precise accord with the predictions of the Jahn—Teller effect. The ground state of (CH₄)⁺ has D_2d symmetry, with a C_3v structure ca. 45.6 kJ mol^?1 higher. (CCl₄)⁺ has a C_2v ground state, with a D_2d structure ca. 144 kJ mol^?1 higher: no bound state of C_3v symmetry could be found. (CH₃Cl)⁺ and (CHCl₃)⁺ both have C_s symmetry, and (CH₂Cl₂)⁺ has C_2v symmetry. The analogous fluoro ions are discussed briefly.     

Past,present and future of the clathrate inclusion compounds built of cyanometallate hosts

One-, two- and three-dimensional CN-bridged metal complex structures made up of building blocks such as linear [Ag(CN)₂]^–, square planar [Ni(CN)₄]^2– or tetrahedral [Cd(CN)₄]^2–, and of the complementary ligands such as ammonia, water, unidentate amine, bidentate a,w- diaminoalkane, etc., are reviewed with an emphasis on their behaviour as hosts to afford clathrate inclusion compounds with guest molecules and as self-assemblies to form supramolecular structures with or without guests. The historical background is explained for Prussian blue and Hofmann's benzene clathrate based on their single crystal structure determinations. The strategies the author and coworkers have been applying to develop varieties of clathrate inclusion compounds from the Hofmann-type are demonstrated with the features observed for the developed structures determined by single crystal X-ray diffraction methods.Abbreviations for Ligands and Guests mma NMeH₂ - dma NMe₂H - tma NMe₃ - mea NH₂(CH₂)₂OH - en NH₂(CH₂)₂NH₂ - pn NH₂CHMeCH₂NH₂ - tn NH₂(CH₂)₃NH₂ - dabtn NH₂(CH₂)₄NH₂ - daptn NH₂(CH₂)₅NH₂ - dahxn NH₂(CH₂)₆NH₂ - dahpn NH₂(CH₂)₇NH₂ - daotn NH₂(CH₂)₈NH₂ - danon NH₂(CH₂)₉NH₂ - dadcn NH₂(CH₂)₁₀NH₂ - mtn NMeH(CH₂)₃NH₂ - dmtn NMe₂(CH₂)₃NH₂ - detn NEt₂(CH₂)₃NH₂ - temtn NMe₂(CH₂)₃NMe₂ - dien NH₂(CH₂)₂NH(CH₂)₂NH₂ - pXdam p-C₆H₄(NH₂CH₂)₂ - rnXdam m-C₆H₄(NH₂CH₂)₂ - py C₅H₅N pyridine - ampy NH₂C₅H₄N aminopyridine - Clpy CIC₅H₄N chloropyridine - Mepy MeC₅H₄N methylpyridine - dmpy Me₂C₅H₃N dimethylpyridine - bpy NC₅H₄C₅H₄N bipyridine - quin C₇H₉N quinoline - iquin iso-C₇H₉N isoquinoline - qxln C₈H₆N₂ quinoxaline - Pe C₅H₁₁-pentyl imH: C₃N₂H₄ imidazole - pyrz N(CHCH)₂N pyrazine - Mequin MeC₇H₈N methylquinoline - bppn C₁₃H₁₄N₂ 1,3-bis(4-pyridyl)propane - bpb C₁₄H₈N₂ 1,4-bis(4-pyridyl)butadiyne - N-Meim C₃N₂H₃Me N-methylimidazole - 2-MeimH C₃N₂H₃Me 2-methylimidazole - dmf HOCNMe₂ dimethylformamide - hmta C₆H₁₂N₄ hexamethylenetetramine - o-phen C₁₂H₈N₂ 1,10-phenanthroline - den HN(CH₂CH₂)₂NH piperazine - morph HN(CH₂CH₂)₂O morpholine - ten N(CH₂CH₂)₃N 1,4-diazabicyclo[2.2.2]octane - ameden NH₂(CH₂)₂N(CH₂CH₂)₂NH N-(2-aminoethyl)piperazine Presented at the Sixth International Seminar on Inclusion Compounds, Istanbul, Turkey, 27–31 August, 1995.     

The rate constants of the elementary reactions of NH3 with O and OH

Two sets of discordant rate constants reported recently for the high-temperature reactions of NH₃ with O and OH were examined by comparing the calculated concentration profiles of NH₃ and OH with experiments by the shock tube technique forNH₃-N₂O-Ar mixtures. The rate constants were confirmed tobe: k₄ = 3.1 × 10¹²exp(−25.5 kJ/RT) cm³ mol⁻¹ s⁻¹ for NH₃ + O → NH₂ + OH and k₅ = 3.2×10¹² exp(−8.4 kJ/RT) for NH₃ + OH → NH₂ + H₂O.     

Infrared spectra of the ammonium ion in ammonium hexavanadate (NH4)2V6O16

The infrared bands of the NH⁺₄ and ND⁺₄ groups in (NH₄)₂V₆O₁₆ and its deuterated analogue can be assigned with a fair amount of certainty at 90 K under the space group P2₁/m(C²_2h). The ND stretching modes of isotopically dilute NH₃D⁺ ions in the crystal are in agreement with the predicted splitting into C_s, C_s and C₁(2) components. The frequencies, shapes and temperature dependence of these modes suggest that both normal and bifurcated hydrogen bonds are formed. The latter closely resembles corresponding bonds in NH₄VO₃, but the normal hydrogen bonds are not as strong as the similar bonds in NH₄VO₃. This can be expected as NH⁺₄ ions are dynamic in character in (NH₄)₂V₆O₁₆ and remain so down to temperatures of 90 K.     

A thermodynamic study of the protonation of some sulphur-containing α,ω-diamines in aqueous solution

The protonation equilibria in aqueous solution of α,ω-thiadiamines of general formula (R)(R′)N(CH₂)_n,S(CH₂)_mNH₂ (R,R′= CH₃ or H) have been investigated potentiometrically and calorimetrically at 25° C in 0.5 mole dm^?3 KNO₃ solution. The enthalpy and entropy changes are discussed in terms of intrinsic proton affinities and solvation effects.     

Über μ-Carboxylato-μ-hydroxo-bis(triamminkobalt(III))-Komplexe

Report of the preparation, chemical properties, and the infrared-to-ultra-violet spectra of the perchlorates and bromides of the two complex cations [Co₂{ac(OH)₂}(NH₃)₆]³⁺ (where ac = HCO₂, CH₃CO₂; CH₂ClCO₂, CHCl₂CO₂, CCl₃CO₂, CHFCO₂, CHF₂CO₂ und CF₃CO₂) and [Co₂{ac₂(OH)}(NH₃)₆]³⁺ (where ac = CH₂ClCO₂, CHClCO₂ und CCl₃CO₂). The perchlorate, nitrate, bromide and dithionate salts of the tetranuclear complex [Co₄{C₂O₄(OH)₄}(NH₃)₁₂]⁶⁺ are described. The complex reported by WERNER as [Co₂{OH}₂(CH₃CO₂)H₂O(NH₃)₆]Br₃ actually has the formula [Co₂{CH₃CO₂(OH)₂}(NH₃)₆]Br₃ · CH₃COOH.