Synthesis,stability and reactivity of cationic carbonyl complexes of rhodium(I)

Summary Trans-[RhCl(CO)L₂] (L = PPh₃, AsPh₃ or PCy₃) react with AgBF₄ in CH₂Cl₂ to give the novel species [Rh-(CO)L₂]⁺ [BF₄]^–.nCH₂Cl₂ (n = 1/2 or 1 1/2) (1–3), which we believe to be stabilised by weak solvent interaction. The corresponding stibine compound cannot be isolated by the same process, instead [Rh(CO)₂(SbPh₃)₃]⁺ [BF₄]^– (7) is formed when the reaction is carried out in the presence of CO. When reactions designed to prepare [Rh(CO)L₂]⁺ [BF₄]^– are performed in the presence of CO, or [Rh(CO)L₂]⁺ [BF₄]^– complexes are reacted with CO, [Rh(CO)₂L₂]⁺ [BF₄]^– (L = PPh₃, AsPh₃ or PCy₃) (4–6) are formed. If Me₂CO is used as solvent in the preparation of [Rh(CO)L₂]⁺ [BF₄]^– (L = PPh₃ or AsPh₃), then the products are the four-coordinate [Rh(CO)L₂-(Me₂CO)]⁺ [BF₄]^– (8,9) species. The complexes have been characterised by i.r., ³¹P and ¹H n.m.r. spectroscopy and elemental analyses.     

Spectrophotometric study of thiocyanato complexation of cobalt(II) and nickel(II) ions in micellar solutions of a nonionic surfactant triton X-100

Complexation of cobalt(II) and nickel(II) with thiocyanate ions has been studied by precise spectrophotometry in aqueous and micellar solutions of a nonionic surfactant Triton X-100 of varying concentrations (20–100 mmol-dm^–3). With regard to cobalt(II), the formation of [Co(NCS)]⁺, [Co(NCS)₂], and [Co(NCS)₄]^2– was established. The formation constant of [Co(NCS)₄]^2–, is increased with increasing concentration of the surfactant, suggesting that the [Co(NCS)₄]^2– complex is formed in micelles. In contrast, the formation constants of [Co(NCS)]⁺ and [Co(NCS)₂] are remained practically unchanged. On the other hand, with nickel(II), the formation of sole [Ni(NCS)]⁺ and [Ni(NCS)₂] was established in both aqueous and micellar solutions examined, their formation constants being also remained unchanged. Interestingly, no higher complex was confirmed in the nickel(II) system, unlike cobalt(II). The unusual affinity of the [Co(NCS)₄]^2– complex with micelles will be discussed from thermodynamic and structural points of view.     

Effect of coordination with rhodium on the selectivity of the mass spectral fragmentation of 4,4-disubstituted 2,5-cyclohexadien-1-ones

Conclusion A comparative study was carried out on the electron impact fragmentation of 4,4-disubstituted 1-oxo-2,5-cyclohexadienes and their rhodium acetylacetonate complexes. The coordination of the diene ligands with rhodium leads to an increase in the selectivity of the decomposition of the molecular ions, which occurs exclusively with loss of the most stable radical located at the geminal unit of the hydrocarbon -ligand and leads to (4-methyl-1-oxocyclohexadienyl) acetylacetonatorhodium cations.2. 15-, 16-, 17-, and 18-Electron complexes containing 4,4-dialkyl-1-oxo-2,5-cyclohexadiene (L) or 4-methyl-1-oxocyclohexadienyl ligands are obtained in the reaction of [acacRh · (CO)_n]⁺ and [(C₅H₅)Rh(CO)_n]⁺ ions (n=0–2) with 4,4-disubstituted 1-oxo-2,5-cyclohexadienes in the gas phase. The formation of [acacRh(CO)L]⁺ and [(C₅H₅)Rh(CO)L]⁺ ions indicated the reduced -donor capacity of 1-oxo-2,5-cyclohexadienes relative to 1-alkylidene-2,5-cyclohexadienes in reactions with rhodium-containing cations.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1088–1093, May, 1986.     

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

Thermodynamics of complexation of zinc(II) with chloride,bromide and iodide ions in hexamethylphosphoric triamide

The complexation of zinc(II) with chloride, bromide and iodide ions has been studied by calorimetry in hexamethylphosphoric triamide (HMPA) containing 0.1 mol-dm^–3 (n-C₄H₉)₄NClO₄ as a constant ionic medium at 25°C. The formation of [ZnX_n]^(2–n)+ (n=1,2,3,4 for X=Cl; n=1,2 for X=Br, I) is revealed, and their formation constants, enthalpies and entropies were determined. It is proposed that the zinc(II) ion is fourcoordinated in HMPA and the coordinating HMPA molecules are stepwise replaced with halide ions to form [ZnX_n(hmpa)_4–n]^(2–n)+ (n=1–4), as is the case for the cobalt(II) ion. Furthermore, the formation of [ZnClI], [ZnBrI], [ZnBrCl] and [ZnBrCl₂]^– is revealed in the relevant ternary systems. It is found that the affinity of a given halide ion X^– to [ZnCl]⁺, [ZnBr]⁺ and [Znl]⁺ is practically the same.     

Hexamethylphosphorsäuretriamid als Ligand, 2. Mitt.: Umsetzungen von [Co(HMPT)4]2+ mit Chlorid-, Bromid- und Jodidionen

Zusammenfassung Folgende Koordinationsformen entstehen aus [Co(HMPT)₄]²⁺ bei Zusatz von Halogenidionen in Hexamethylphosphorsäuretriamid (HMPT): [Co(HMPT)₃Cl]⁺, [Co(HMPT)₂Cl₂], [Co(HMPT)Cl₃]^–, [CoCl₄]^2–, [Co(HMPT)₃Br]⁺, [Co(HMPT)₂Br₂] und [Co(HMPT)₃J]⁺.

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Hexamethylphosphoric triamide as a ligand II: Reactions of Co(HMPT)₄ ²⁺ with chloride, bromide, and iodide ions

The following coordination species are formed from [Co(HMPT)₄]²⁺, by addition of halide ions in hexamethylphosphoric triamide (HMPT): [Co(HMPT)₃Cl]⁺, [Co(HMPT)₂Cl₂], [Co(HMPT)Cl₃]^–, [CoCl₄]^2–, [Co(HMPT)₃Br]⁺, [Co(HMPT)₂Br₂] and [Co(HMPT)₃J]⁺.

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V. Gutmann, A. Weisz undW. Kerber, 1. Mitt., Mh. Chem.100, 2096 (1969).     

Structure determination of zinc iodide complexes formed in aqueous solution

Structures of the complexes formed in aqueous solutions between zinc(II) and iodide ions have been determined from large-angle X-ray scattering, Raman and far-IR measurements. The coordination in the hydrated Zn²⁺ hexaaqua ion and the first iodide complex, [ZnI]⁺, is octahedral, but is changed into tetrahedral in the higher complexes, [ZnI₂(H₂O)₂], [ZnI₃(H₂O)]^– and [ZnI₄]^2–. The Zn-I bond length is 2.635(4)Å in the [ZnI₄]^2– ion and slightly shorter, 2.592(6)Å, in the two lower tetrahedral complexes. In the octahedral [ZnI(H₂O)₅]⁺ complex the Zn-I bond length is 2.90(1)Å. The Zn-O bonding distances in the complexes are approximately the same as that in the hydrated Zn²⁺ ion, 2.10(1)Å.     

Synthesis,crystal structure,and properties of [Cu(LH)]2[M(mnt)2] [M = Ni or Cu; H2L = 3,3′-(1,3-propanediyldinitrilo)-bis(2-butanone oxime); mnt2− = maleonitriledithiolate] complexes containing bridging cyano groups

Interesting complexes containing a mnt^2– bridge, based on the reaction of [M(mnt)₂]^2– [M = Ni or Cu] with [Cu(LH)]⁺, have been prepared and characterized by e.s.m.s., i.r and u.v–vis. spectroscopic techniques and by electrochemistry. The complexes show weak antiferromagnetic interactions between magnetic centers. The X-ray analysis of the molecular structure of [Cu(LH)]₂[Ni(mnt)₂] has been completed. It structurally features the CN group of mnt^2– which can act as a bridging ligand between two transition metals.     

[RhCl(CO)(PPh3)]2. A precursor for the synthesis of cationic rhodium complexes with nitrogen donor ligands

Summary The use of [RhCl(CO)(PPh₃)]₂ as a precursor for the synthesis of complexes of the types [Rh(CO)L₂(PPh₃)]A (A = [ClO₄]^– or [BPh₄]^–; L = pyridine type ligand) and [Rh(CO)(L-L)(PPh₃)]A (A = [ClO₄]^– or [BPh₄]^–; L-L = bidentate nitrogen donor) and the preparation of several complexes of the types [Rh(CO)L(PPh₃){P(p-RC₆H₄)₃}]BPh₄ and [Rh(CO)(phen)(PPh₃){P(p-RC₆H₄)₃}]A (A = [ClO₄]^– or [BPh₄]^–; R = H or Me) is described.Author to whom all correspondence should be directed.     

Hydrogendifluorokobaltate(II)

Zusammenfassung Aus Kobalt(II)perchlorat und Piperidiniumhydrogendifluorid entstehen in nichtwäßrigen Lösungsmitteln (L) Komplexe, welche HF₂-Einheiten als Liganden enthalten, nämlich [Co(HF₂)L ₅]⁺, [Co(HF₂)₂ L ₄], [Co(HF₂)₃ L ₃]^–, [Co(HF₂)₄ L ₂]^2– und [Co(HF₂)₆]^4–.

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Hydrogendifluorocobaltates(II)

Cobalt(II)perchlorate and piperidinium hydrogendifluoride in non-aqueous solvents (L) yield complex compounds containing an HF₂-group as ligand, e.g. [Co(HF₂)L ₅]⁺, [Co(HF₂)₂ L ₄], [Co(HF₂)₃ L ₃]^–, [Co(HF₂)₄ L ₂]^2– and [Co(HF₂)₆]^4–.

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Azido-, Rhodano-, Cyano- und Fluorokomplexe des Fe(III)-Ions in Dimethylsulfoxid

Zusammenfassung Auf Grund spektrophotometrischer und konduktometrischer Messungen wurden folgende Koordinationsformen des Eisen(III)-ions mit Azid-, Rhodanid-, Cyanid- und Fluoridionen in Dimethylsulfoxid festgestellt: [Fe(N₃)₄]^–, [Fe(SCN)₆]^3–, [Fe(CN)₂]⁺, Fe(CN)₃, [Fe(CN)₄]^–, [FeF₂]⁺, [FeF₄]^–.

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By means of spectrophotometric and conductometric measurements the following coordination forms of iron(III) with azide-, thiocyanate-, cyanide- and fluoride ions were found in dimethyl sulfoxide: [Fe(N₃)₄]^–, [Fe(SCN)₆]^3–, [Fe(CN)₂]⁺, Fe(CN)₃, [Fe(CN)₄]^–, [FeF₂]⁺, [FeF₄]^–.

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Co-catalysis by transition metal ions in the hydrogen ion catalysed oxidation of iodide ions. A kinetic study

The reaction between KI and [Fe(CN)₆]^3– ion, catalysed by hydrogen ions, was found to be catalysed further by PdCl₂. Separate reactions under similar conditions, studied in the absence as well as in the presence of PdCl₂ catalyst, were found to follow first order kinetics w.r. to [Fe(CN)₆]^3– and [H⁺], while the order was two w.r. to [I^–]. [Fe(CN)₆]^4– ions were found to have a negative effect while changes in ionic strength of the medium do not effect the reaction velocity. Reaction in the presence of PdCl₂ showed direct proportionality w.r. to [PdCl₂]. The rate and extent of the reaction, which takes place even at zero [PdCl₂] in the co-catalysed reaction, was calculated and was found to be in accordance with the rate values of the separately studied reaction at similar concentrations without adding PdCl₂.     

Chronopotentiometric determination of the outer-sphere association constants of substitution-inert metal complexes

Summary A new method for the determination of association constants by the measurement of chronopotentiometric transition time has been developed and applied to the study on the outer-sphere association of some substitution-inert complex cations with sulphate ions. The association constants were determined from the change in transition time as function of the concentration of sulphate ions at ionic strength 0.1 (NaClO₄) and 25° C: 93 ±8 for [Co(NH₃)₆]³⁺SO₄ ^2–, 99 ±15 for [Co(en)₃]³⁺SO₄ ^2–, 61 ±7 for [Cr(NH₃)₆]³⁺SO₄ ^2– and 58 ±8 for [Cr(en)₃]³⁺SO₄ ^2–. The ratios of the diffusion coefficients of the univalent ion-pairs and tervalent substitution-inert complex cations were also obtained. From these ratios the diffusion coefficients of the univalent ion-pairs were calculated, which were found to differ not greatly from those of univalent complex ions with similar structures.

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Zusammenfassung Eine neue Methode zur Bestimmung von Assoziationskonstanten aus den Transitionszeiten chronopotentiometrischer Messungen wurde entwickelt. Sie wurde zur Untersuchung der Assoziation von Sulfationen in zweiter Sphäre an koordinativ abgesättigten Komplex-Kationen herangezogen. Die Assoziationskonstanten wurden aus der Abhängigkeit der Transitionszeit von der Sulfatkonzentration in Medien der Ionenstärke 0,1 (NaClO₄) und bei 25° C bestimmt. Man erhält folgende Werte: 93±8 für [Co(NH₃)₆]³⁺SO₄ ^2–, 99±15 für [Co(en)₃]³⁺SO₄ ^2–, 61±7 für [Cr(NH₃)₆]³⁺SO₄ ^2– und 58±8 für [Cr(en)₃]³⁺SO₄ ^2–. Die Verhältnisse der Diffusionskoeffizienten der einwertigen Ionenpaare zu denen der dreiwertigen Komplex-Kationen wurden ebenfalls bestimmt. Aus diesen Verhältnissen lassen sich die Diffusionskoeffizienten der Ionenpaare berechnen. Man erhält eine gute Übereinstimmung mit den Werten für einwertige Komplexionen mit ähnlicher Struktur.

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Dedicated to Prof. Dr. M. von Stackelberg on his 70th birthday.     

Coordination chemistry of poly(1-pyrazolyl)alkanes Part V: Preparation and characterization of cobalt(II) complexes with bis(1-pyrazolyl)methane and bis(3-methylpyrazolyl)propane

Summary Bis(1-pyrazolyl)methane, H₂Cbpz, and bis(3-methylpyrazolyl)propane, Me₂Cbmpz, react with cobalt(II) salts to give the solid complexes: [Co(H₂Cbpz)₂X₂] ·2H₂O (X=Cl^–, Br^–, I^–, NO ₃ ^– or ClO ₄ ^– ) and [Co(Me₂-Cbmpz)X₂] (X=Cl^–, Br^–, or I^–), which were isolated and characterised by elemental analysis, i.r. and electronic spectra and conductance measurements. From spectral data, octahedral and tetrahedral structures have been proposed for the H₂Cbpz and Me₂Cbmpz complexes respectively. The molar conductance of the complexes indicates that they are non-ionic.     

Cobalt(II) complexes of 1,2-(diimino-4′-antipyrinyl)ethane and 4-N-(4′-antipyrylmethylidene)aminoantipyrine

Cobalt(II) complexes of the Schiff bases 1,2-(diimino-4-antipyrinyl)ethane (GA) and 4-N-(4-antipyrylmethylidene)aminoantipyrine (AA) have been prepared and characterised by elemental analysis, electrical conductance in non-aqueous solvents, i.r. and electronic spectra, as well as by magnetic susceptibility measurements. The complexes have the general formulae [Co(GA)X]X (X = ClO^– ₄ or NO₃ ^–), [Co(GA)X₂] (X = Cl^–, Br^– or I^–), [Co(AA)₂]X₂ (X = ClO₄ ^–, NO₃ ^–, Br^– or I^–) and [Co(AA)Cl₂]. GA acts as a neutral tetradentate ligand, coordinating through both carbonyl oxygens and both azomethine nitrogens. In the perchlorate and nitrate complexes of GA one anion is coordinated in a bidentate fashion, whereas in the halide complexes both anions are coordinated to the metal, generating an octahedral geometry around the Co ion. AA acts as a neutral bidentate ligand, coordinating through the carbonyl oxygen derived from the aldehydic moiety and the azomethine nitrogen. Both anions remain ionic in the perchlorate, nitrate, bromide and iodide complexes of AA, whereas both anions are coordinated to the metal ion in the chloride complex, resulting tetrahedral geometry around the Co ion.     

Chemical transformations of a SiO2-supported [Fe5RhC(CO)16]− cluster and catalysis of propylene hydroformylation

Chemical transformations of SiO₂-supported [Fe₅RhC(CO)₁₆]^– and [Fe₄RhC(CO)₁₄]^– clusters in Ar, CO, and synthesis gas are studied by IR spectroscopy, Mössbauer spectroscopy, and transmission electron microscopy. It is shown that partial transformation of the [Fe₅RhC(CO)₁₆]^– cluster to the [Fe₄RhC(CO)₁₄]^– cluster occurs immediately after its deposition on the substrate surface with the simultaneous formation of Fe²⁺ ions. The complete conversion of the supported [Fe₅RhC(CO)₁₆]^– cluster to [Fe₄RhC(CO)₁₄]^– is observed at 323 K in the synthesis gas. At 373 to 423 K [Fe₅RhC(CO)₁₆]^– transforms into a mixture of Fe₄Rh₂C(CO)₁₆, [Fe₄RhC(CO)₁₄]^–, and [Fe₅₃Rh₃C(CO)₁₅]^– clusters. In the 523 to 623 K range, the supported [Fe₅RhC(CO)₁₆]^– cluster decarbonylates completely to form bimetallic species Å 5 Å in size. Silica-supported FeRh clusters are active in propylene hydroformylation at 423 to 473 K and form a mixture of butyl alcohols and butyraldehydes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 632–641, April, 1995.This work was financially supported by the Krasnoyarsk Region Scince Foundation (Grant No. 1F0020).     

Solvent and chelation effects on the photoreduction of cobalt(III)–amine complexes in aqueous–organic solvent media

The photoreduction of trans-[Co(NH₃)₄Cl₂]⁺, trans-[Co(en)₂Cl₂]⁺, [Co(dien)Cl₃], [Co(trien)Cl₂]⁺, and [Co(tetren)Cl]²⁺, ions has been studied using a low pressure Hg vapour lamp as light source (254 nm) in aqueous–organic solvents [0–30% (v/v) MeOH or 1,4-dioxane]. Quantum yields for Co^II production by redox decomposition have been determined in all the cases, and increase considerably with the increase in concentration of MeOH or 1,4-dioxane in the binary solvent mixtures under investigation. A plot of log(quantum yield) versus the Grunwald–Winstein Parameter, Y, which is a measure of solvent ionizing power, shows that a different blend of general and specific solvent interacts with the solute. This kind of specific solvent interaction on the reactant/excited state has been analysed using multiple regression: viz. Krygowski–Fawcett and Kamlet–Taft equations. Reasons for the difference in reactivity with chelation are also discussed.     

Electrochemical synthesis and magnetic studies of neutral transition metal imidazolates and pyrazolates

Summary The single-step electrochemical synthesis of neutral transition metal complexes of imidazole, pyrazole and their derivatives has been achieved at ambient temperature. The metal was oxidized in an Me₂CO solution of the diazole to yield complexes of the general formula: [M(Iz)₂] (where M = Co, Ni, Cu, Zn; Iz = imidazolate); [M(MeIz)₂] (where M = Co, Ni, Cu, Zn; MeIz = 4-methylimidazolate); [M(PrⁱIz)₂] (where M = Co, Ni, Cu, Zn; PrⁱIz = 2-isopropylimidazolate); [M(pyIz)_n] (where M = Co^III, Cu^II, Zn^II; pyIz = 2-(2-pyridyl)imidazolate); [M(Pz)_n] (where M = Co^III, Ni^II, Cu^II, Zn^II; Pz = pyrazolate); [M(ClPz)_n] and [M(IPz)_n] (where M = Co^III, Ni^II, Cu^II, Zn^II; ClPz = 4-chloropyrazolate; IPz = 4-iodopyrazolate); [M(Me₂Pz)_n] (where M = Co^II, Cu^I, Zn^II; Me₂Pz = 3,5-dimethylpyrazolate) and [M(BrMe₂Pz)_n] (where M = Co^II, Ni^II, Cu^I, Zn^II; BrMe₂Pz = 3,5-dimethyl-4-bromopyrazolate). Vibrational spectra verified the presence of the anionic diazole and electronic spectra confirmed the stereochemistry about the metal centre. Variable temperature (360-90 K) magnetic measurements of the cobalt and copper chelates revealed strong antiferromagnetic interaction between the metal ions in the lattice. Data for the copper complexes were fitted to a Heisenberg (S= ) model for an infinite one-dimensional linear chain, yielding best fit values of J=–62––65cm^–1 andg = 2.02–2.18. Data for the cobalt complexes were fitted to an Ising (S= ) model with J=–4.62––11.7cm^–1 andg = 2.06–2.49.     

Spectrophotometric determination of trace amounts of cadmium and lead with iodide and Rhodamine B

Summary Highly sensitive spectrophotometric methods have been developed for determination of cadmium and lead, based on the CdI₄ ^2– or PbI₄ ^–2 anionic complexes with Rhodamine B in the presence of polyvinyl alcohol to form ion-association complexes. The molar absorptivity is 4.2×10⁵l·mole^–1·cm^–1 at 600 nm for cadmium and 5.7×10⁵l·mole^–1·cm^–1 at 610 nm for lead. The complexes have the composition [CdI₄ ^2–]·[RhB⁺]₂ and [PbI₄ ^2–]·[RhB⁺]₂ as established by Job's method of continuous variations and the molarratio method. The colour reaction selectivity is fairly good and the method can be applied for direct spectrophotometric determination of cadmium or lead in some pure metals. A species [PbI₃ ^–]·[RhB⁺] can also be formed, and extracted into toluene or a toluene/diethyl ether mixture.

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Spektrophotometriscbe Bestimmung von Spuren Cadmium und Blei mit Jodid und Rhodamin B

Zusammenfassung Hochempfindliche spektrophotometrische Methoden für die Bestimmung von Cadmium und Blei wurden entwickelt; sie beruhen auf der Reaktion von CdJ₄ ^2– bzw. PbJ₄ ^2– mit Rhodamin B in Gegenwart von Polyvinylalkohol unter Bildung von Ionenassoziat-Komplexen. Die molare Absorptivität für Cadmium beträgt 4,2×10⁵l·mol^–1·cm^–1 bei 600 nm und für Blei 5,7×10⁵l·mol^–1·cm^–1 bei 610 nm. Wie nach der Methode der kontinuierlichen Variation nach Job bzw. mittels Molarverhältnis ermittelt wurde, lautet die Formel [CdJ₄] [RhB]₂ bzw. [PbJ₄] [RhB]₂. Die Selektivität der Farbreaktion ist gut. Das Verfahren kann zur direkten spektrophotometrischen Bestimmung von Cadmium bzw. Blei in verschiedenen reinen Metallen verwendet werden. Auch eine Verbindung [PbJ₃ ^–] [RhB⁺] kann hergestellt werden, die sich mit Toluol oder mit einem Gemisch aus Toluol und Diethylether extrahieren läßt.

     

Plasma desorption mass spectrometry of transition metal complexes of thio- and selenosemicarbazones of 2-acetylpyridines

Summary Californium-252 plasma desorption mass spectra were recorded for complexes of the anions of various thio-and seleno-semicarbazones of 3-acetylpyridines(1–4) with the transition metal ions iron(III) and cobalt(II). Positive ion spectra gave clear evidence of the cation present and fragmentation with loss of ligands or parts of ligands was straightforward. Negative ion spectra likewise provided evidence of the intact anion except with tetracoordinate metal halide systems [MX₄]^– which lost one or more halide atoms. Evidence of fragmentation of the ligand and recombination of the fragments with the metal ion was also observed in the negative ion mode. Spectra were used to revise the structure of a complex previously reported as [FeLCl₂]⁽¹⁾ to [FeL₂]⁺[FeCl₄]^–.