Kinetics and mechanism of pentacyanohydroxoferrate(III) formation from the reaction of cyanide ion with [Fe2L(OH)2]2− (L=triethylenetetraaminehexaacetate)

Summary The kinetics and mechanism of the reaction between [Fe₂L(OH)₂]^2– and cyanide ion (L = TTHA, triethylenetetraaminehexaacetate) have been studied spectrophotometrically atpH=11.0±0.1,I=0.1 M(NaClO₄) and T = 25±0.1 °C. The overall reaction consists of three distinct, observable stages. The first stage involves the dissociation of the binuclear complex into a mononuclear complex [FeL(OH)]^4– which then reacts with cyanide to form [Fe(CN)₅OH]^3–. The species [Fe(CN)₅OH]^3– reacts further with an excess of cyanide and forms [Fe(CN)₆]^3– in the second stage of reaction. The last stage involves the reduction of [Fe(CN)₆]^3– formed in the second stage by the TTHA^6– released in the first stage of reaction. The formation of [Fe(CN)₅OH]^3– in the first stage is firstorder in [Fe₂L(OH)₂]^2– and third-order in cyanide over a large range of cyanide concentrations but becomes zero-order in cyanide at [CN^–] < 4×10^–2M.These observations enable us to suggest the presence of a slow step in which [Fe₂L(OH)₂]^2– dissociates into [FeL(OH)]^4– and [FeOH]²⁺ at low cyanide concentrations and a cyanide assisted rapid dissociation of [Fe₂L(OH)₂]^2– to [FeL(OH)(CN)]^5– at higher cyanide concentrations. The species [FeL(OH)(CN)]^5– reacts further with an excess of cyanide to produce [Fe(CN)₅OH]^3– finally.The reverse reaction between [Fe(CN)₅OH]^3– and TTHA^6– follows first-order dependence in each of [Fe(CN)₅OH]^3– and TTHA^6– and inverse first-order dependence on cyanide concentration. A six-step mechanism has been proposed for the first stage of reaction in which the fifth has been identified as the rate-determining step.     

Kinetic and mechanism of pentacyanohydroxoferrate(III) formation from the reaction of [Fe2HPDTA(OH)2] with cyanide ions

Summary The kinetics and mechanism of exchange of HPDTA in [Fe₂HPDTA(OH)₂] with cyanide ion (HPDTA=2-hydroxytrimethylenediaminetetraacetic acid) was investigated spectrophotometrically by monitoring the peak at 395 nm ( _max of [Fe(CN)₅OH]^3– at pH=11.0±0.02,I=0.25m (NaClO₄) at ±0.1°C).Three distinct observable stages were identified; the first is the formation of [Fe(CN)₅OH]^3–, the second the formation of [Fe(CN)₆]^3– from it and the third the reduction of [Fe(CN)₆]^3– to [Fe(CN)₆]^4– by HPDTA^4– released in the first stage.The first stage follows first-order kinetics in [Fe₂HPDTA(OH)₂] and second-order in [CN^–] over a wide range of [CN^–], but becomes zero order at [CN^–]<5×10^–2 m. We suggest a cyanide-independent dissociation of [Fe₂HPDTA)(OH)₂] into [FeHPDTA(OH)] and [Fe(OH)]²⁺ at low cyanide concentrations and a cyanide-assisted rapid dissociation of [Fe₂HPDTA(OH)₂] to [FeHPDTA(OH)(CN)]^3– and [Fe(OH)]²⁺ at higher cyanide concentrations. The excess of cyanide reacts further with [FeHPDTA(OH)(CN)]^3– finally to form [Fe(CN)₅OH]^3–.The reverse reaction between [Fe(CN)₅OH]^3– and HPDTA^4– is first-order in [Fe(CN)₅OH]^3– and HPDTA^4–, and exhibits inverse first-order dependence on cyanide concentration.A six-step mechanism is proposed for the first stage of reaction, with the fifth step as rate determining.     

Photosubstitution in some cyanide complexes of chromium(III)(1)

Photosubstitution by OH^? ligand was concluded from a photochemical study of the [Cr(CN)₆]^3? and [Cr(CN)₅OH]^3? complexes in alkaline medium. Photoaccelerated aquation was found to proceed in the case of aquocyanochromates(III): [Cr(CN)₅H₂O]^2? and [Cr(CN)₃(H₂O)₃].     

Crystallization method controlled trinuclear or ion-pair Manganese(III)-porphyrin-based heterobimetallic complexes: Synthesis,spectra characterization,and crystal structure

Cyanide-bridged trinuclear heterometallic Ag(I)-Mn(III) complex {[Mn(TClPP)(H₂O)]₂[Ag(CN)₂]}₂ · 2Br · 2C₃H₆O · 3H₂O (I) and ion-pair complex {[Mn(TClPP)(CH₃OH)₂][Ag(CN)₂]} · 0.5H₂O (II) have been synthesized with [Mn(TClTPP)(H₂O)₂]Br (H₂TClTPP = meso-tetra(4-chlorophenyl)porphyrin) as assembling segment and K[Ag(CN)₂] as building block by using different crystallization method. These two complexes have been characterized by elemental analysis, IR spectroscopy and X-ray structure determination. In the trinuclear complex I, [Ag(CN)₂]^? as bidentate ligand coordinates with the two central Mn(III) atom of [Mn(TClPP)(H₂O)₂]⁺ through its two trans cyanide groups to form the complex cation of [Mn(TClPP)(H₂O)]₂[Ag(CN)₂]⁺, which further constructs the neutral complexes with the help of one Br^? as balanced anion. For the ion-pair complex II composed by free [Mn(TClPP)(CH₃OH)₂]⁺ cation and free [Ag(CN)2]^? anion, it can be linked into one-dimensional supramolecular structure with the dependence of the intermolecular O-H...N and O-H...O hydrogen bond interactions.     

Aqua cadmium cyanide coordination polymer with nitronyl nitroxide radical

A new three-dimensional diamagnetic metal nitronyl nitroxide radical coordination polymer with an aqua cadmium cyanide framework Cd(NIT4py)(H₂O)Cd(CN)₄·H₂O 1, was synthesized. X-ray crystallography reveals that the structure consists of 3D aqua cadmium cyanide built up by octahedral Cd^II coordinating to NIT4py and tetrahedral Cd^II (CN)₄ units. Magnetic measurements show that the χ_mT values are nearly constant at higher temperature. The lower χ_mT values at lower temperature are related to intermolecular antiferromagnetic interactions of the radicals, which arise due to the hydrogen bonded network (T_N = 21 K).     

A new generation of cyanide ion-selective membranes for flow injection application: Part III. A simple approach to the determination of toxic metal-cyanide complexes without preliminary separation

A new flow injection approach to total weak acid-dissociable (WAD) metal–cyanide complexes is proposed, which eliminates the need of a separation step (such as gas diffusion or pervaporation) prior to the detection. The cornerstone of the new methodology is based on the highly selective flow-injection potentiometric detection (FIPD) system that makes use of thin-layer electroplated silver chalcogenide ion-selective membranes of non-trivial composition and surface morphology: Ag_2 + δSe_1 − xTe_x and Ag_2 + δSe. An inherent feature of the FIP-detectors is their specific response to the sum of simple CN⁻ + Zn(CN)₄²⁻ + Cd(CN)₄²⁻. For total WAD cyanide determination, ligand exchange (LE) and a newly developed electrochemical pre-treatment procedure for release of the bound cyanide were used. The LE pre-treatment ensures complete recovery only when the sample does not contain Hg(CN)₄²⁻. This limitation is overcome by implementing electrochemical pre-treatment which liberates completely the bound WAD cyanide through cathodic reduction of the complexed metal ions. A complete recovery of toxic WAD cyanide is achieved in the concentration range from 156 μg L⁻¹ up to 13 mg L⁻¹. A three-step protocol for individual and group WAD cyanide speciation is proposed for the first time. The speciation protocol comprises three successive measurements: (i) of non-treated, (ii) LE-exchange pre-treated; (iii) electrochemically pre-treated sample. In the presence of all WAD complexes this procedure provides complete recovery of the total bound cyanide along with its quantitative differentiation into the following groups: (1) Hg(CN)₄²⁻; (2) CN⁻ + Cd(CN)₄²⁻ + Zn(CN)₄²⁻; (3) Cu(CN)₄³⁻ + Ni(CN)₄²⁻ + Ag(CN)₂⁻. The presence of a 100-fold excess in total of the following ions: CO₃²⁻, SCN⁻, NH₄⁺, SO₄²⁻ and Cl⁻ does not interferes. Thus the proposed approach offers a step ahead to meeting the ever increasing demand for cyanide-species-specific methods. The equipment simplicity makes the procedure a good candidate for implementing in portable devices for in-field cyanide monitoring.     

The kinetics and mechanism of reaction between ethylenediaminetetraacetomanganate(III) and cyanide ion

Summary The title reaction has been followed spectrophotometrically at 325 nm (_max of [Mn(CN)₆]^3–) under pseudo-first order conditions with cyanide in a large excess at pH=10.0, I=0.1M (NaClO₄) and 25°C. The reaction follows first-order kinetics in [MnEDTA(OH)]^2– and exhibits variable-order dependence in [CN^–] one at high cyanide concentration, and two at low cyanide concentration. The product of above reaction has been identified as [Mn(CN)₆]^3–.The kinetics of the reverse reaction,i.e., the reaction of [Mn(CN)₆]^3- with EDTA^4– have also been followed spectrophotometrically. This reactions is first-order with respect to both [Mn(CN) ₆ ^3– ] and [EDTA^4–] and exhibits an inverse first-order dependence on [CN^–]. A six-step mechanism has been proposed in which the penultimate step is rate-determining. The activation parameters have been obtained and support the postulated mechanism.     

Equilibria in complexes ofN-heterocyclic molecules,Part XV+. Intermediates in the reaction of cyanide with transition metal tris complexes of 1,10-phenanthroline, 5-nitro-1,10-phenanthroline and 2,2'-bipyridyl

Summary The Ru(phen)₃(CN)₂ · 6 H₂O, Ru(bipy)₃(CN)₂ · 6H₂O, Fe(phen)₃(CN)₂ · H₂O and Ru(5-NO₂P)₃(CN)₂ · 2 H₂O compounds have been isolated during the reaction of the parent cations with aqueous cyanide solutions. It is evident, that in each case, attack at the ligand has taken placevia the cyanide nucleophile, though the equilibrium constant for the formation of the Reissert-type species are widely different. The implications of the findings with respect to the known reaction kinetics of the parent ions in aqueous cyanide solution are discussed.Part 14: R.D. Gillard and P.A. Williams,Transition Met. Chem., 2, 109(1977)     

Controlled Synthesis of Heterotrimetallic Single‐Chain Magnets from Anisotropic High‐Spin 3 d–4 f Nodes and Paramagnetic Spacers

By using the node‐and‐spacer approach in suitable solvents, four new heterotrimetallic 1D chain‐like compounds (that is, containing 3d–3d′–4f metal ions), {[Ni(L)Ln(NO₃)₂(H₂O)Fe(Tp*)(CN)₃] ? 2 CH₃CN ? CH₃OH}_n (H₂L=N,N′‐bis(3‐methoxysalicylidene)‐1,3‐diaminopropane, Tp*=hydridotris(3,5‐dimethylpyrazol‐1‐yl)borate; Ln=Gd ( 1 ), Dy ( 2 ), Tb ( 3 ), Nd ( 4 )), have been synthesized and structurally characterized. All of these compounds are made up of a neutral cyanide‐ and phenolate‐bridged heterotrimetallic chain, with a {? Fe? C?N? Ni(? O? Ln)? N?C? }_n repeat unit. Within these chains, each [(Tp*)Fe(CN)₃]^? entity binds to the Ni^II ion of the [Ni(L)Ln(NO₃)₂(H₂O)]⁺ motif through two of its three cyanide groups in a cis mode, whereas each [Ni(L)Ln(NO₃)₂(H₂O)]⁺ unit is linked to two [(Tp*)Fe(CN)₃]^? ions through the Ni^II ion in a trans mode. In the [Ni(L)Ln(NO₃)₂(H₂O)]⁺ unit, the Ni^II and Ln^III ions are bridged to one other through two phenolic oxygen atoms of the ligand (L). Compounds 1 – 4 are rare examples of 1D cyanide‐ and phenolate‐bridged 3d–3d′–4f helical chain compounds. As expected, strong ferromagnetic interactions are observed between neighboring Fe^III and Ni^II ions through a cyanide bridge and between neighboring Ni^II and Ln^III (except for Nd^III) ions through two phenolate bridges. Further magnetic studies show that all of these compounds exhibit single‐chain magnetic behavior. Compound 2 exhibits the highest effective energy barrier (58.2 K) for the reversal of magnetization in 3d/4d/5d–4f heterotrimetallic single‐chain magnets.     

Structure of Aqueous Lithium Tetraborate Solution

The structure of aqueous lithium tetraborate solutions was investigated by species distribution calculation and synchrotron X-ray scattering. It shows that the dominant species in supersaturated solution at 298.15 K is B₄O₅(OH) ₄ ^2? and the minor species are B₃O₃(OH) ₅ ^2? , B₃O₃(OH) ₄ ^? and B(OH)₃. The ‘intramolecular’ structural parameters of B₄O₅(OH) ₄ ^2? , such as bond length and coordination number, were gives out using density function theory calculation. X-ray scattering study shows that the distance Li–O(H₂O)_I of [Li(H₂O)₄]⁺ is about 0.1983 nm with the coordination number(CN) 4 in tetrahedral configuration. The B–O(H₂O) distance in hydrated anion B₄O₅(OH)₄(OH₂) ₈ ^2? is 0.3662 nm with the CN 12. The Li⁺–B distance is about 0.3364 nm with a coordination number ~1.0. The temperature effect on solution structure was also discussed.     

The adsorption of Na2[Cu(CN)3] onto alumina: The existence of both crystalline and solvated forms on the surface

The sodium cuprous cyanide salt, Na₂[Cu(CN)₃], has been adsorbed onto alumina, and the i.r. spectra, fast atom bombardment mass spectra and scanning electron micrographs of the reagent over a range of Na₂[Cu(CN)₃] loadings have been obtained. These show that, at high loadings, Na₂[Cu(CN)₃] is present on the surface in a crystalline form. At low loadings Na₂[Cu(CN)₃] is dispersed over the alumina surface, with the i.r. spectrum corresponding to that of aqueous [Cu(CN)₃]⁻². There appears to be good correlation in the mass spectrum between the percentage intensity of the sodium (m/z 23) peak relative to the sum of the Na⁺ and Al⁺ intensities, and the loading of Na₂ [Cu(CN)₃]. The scanning electron micrographs of the reagent at high loading clearly show crystalline material; at low loadings there is no difference in appearance between the reagent and uncoated alumina.     

A New Mixed‐Valent Copper Cyanido Complex and a New Copper(II) Acetato Complex,Prepared with an Ionic Liquid

When copper(II) acetate is treated with the ionic liquid n‐butylmethylimidazolium cyanide (BMIm‐CN), in ethanol solution, two new copper coordination compounds are obtained. (BMIm)₂[Cu₄(CN)₇] comprises a 3D coordination polymer of cyanide bridged copper ions. This anionic coordination polymer contains Cu^I as well as Cu^II ions, i.e. it is a mixed‐valent compound. The polymer can be described as honeycomb structure with the BMIm⁺ cation being located in the cages. The second compound obtained from the chemical reaction is (BMIm)[Cu₂(OAc)₅][Cu(OAc)₂(H₂O)]₂ · C₂H₅OH, which can be described as double‐salt. The first unit (BMIm)[Cu₂(OAc)₅] contains paddle wheel copper(II) acetato moieties, which are bridged by additional acetato ligands and form infinite chains. The second part of the double salt is the neutral, [Cu(OAc)₂(H₂O)]₂ complex. These two parts as well as the co‐crystallized ethanol molecule are connected through a network of hydrogen bridges.     

Synthesis and properties of sulfur cyanide trifluoride,SF3CN,sulfur dicyanide difluoride,SF2(CN)2, and sulfinyl cyanide fluoride,FS(O)CN

Sulfur cyanide trifluoride, SF₃CN, and sulfur dicyanide difluoride, SF₂(CN)₂, have been prepared by metathesis between sulfur tetrafluoride, SF₄, and trimethyl silyl cyanide, (CH₃)₃SiCN, at – 30°C. Treatment of SF₃CN with freshly sublimed selenium dioxide, SeO₂, lead to sulfinyl cyanide fluoride, FS(O)CN. IR, Raman, ¹⁹F-NMR, uv and mass spectra of the novel compounds are presented as well as some physical and chemical properties.     

Photosubstitution reactions in potassium octacyanomolybdate(IV) and octacyanotungstate(IV) in the presence of 1,10-phenanthroline and 2,2-́bipyridyl

Substitution reactions take place following the photonic excitation of aqueous K₄M(CN)₈ (where M = Mo or W) in the presence of 1,10-phenanthroline and 2,2$\text{-}\text{?}$bipyridyl. Changes in absorbance with time show that the overall reaction is dependent on photochemical activation of potassium octacyanomolybdate(IV) and -tungstate(IV). The species [K₂Mo(CN)₄(OH)₂(phen)], [K₂W(CN)₄(OH)₂(phen)], [K₂Mo(CN)₄(OH)₂(bipy)] and [K₂W(CN)₄(OH)₂(bipy)] exist in solution. The final photosubstitution products [Mo(OH)₃(CN)(phen)₂] · 2H₂O], [Mo(OH)₃(CN)(bipy)₂] · 3H₂O, [W(OH)₃(CN)(phen)₂] · 2H₂O and [W(OH)₃(CN)(bipy)₂] · H₂O have been isolated in the solid state. Their IR spectra have been discussed. The quantum yield of the photosubstitution reactions has been determined and its variation with change of concentration of the complex as well as the H⁺ ion concentration has been studied.     

Chemical ionization of phenyl n-propyl ether and methyl substituted analogs: Propene loss initiated by competing proton transfer to the oxygen atom and the aromatic ring

The mechanism of propene loss from protonated phenyl n-propyl ether and a series of mono-, di-, and trimethylphenyl n-propyl ethers has been examined by chemical ionization (CI) mass spectrometry in combination with tandem mass spectrometry experiments. The role of initial proton transfer to the oxygen atom and the aromatic ring, respectively, has been probed with the use of deuterated CI reagents, D₂O, CD₃OD, and CD₃CN (given in order of increasing proton affinity), in combination with deuterium labeling of the β position of the n-propyl group or the phenyl ring. The metastable [M + D]⁺ ions of phenyl n-propyl ether—formed with D₂O as the CI reagent—eliminate C₃H₅D and C₃H₆ in a ratio of 10:90, which indicates that the added deuteron is incorporated to a minor extent in the expelled neutral species. In the experiments with CD₃OD as the CI reagent, the ratio between the losses of C₃H₅D and C₃H₆ from the metastable [M + D]⁺ ions of phenyl n-propyl ether is 18:82, whereas the ratio becomes 27:73 with CD₃CN as the reagent. A similar trend in the tendency to expel a propene molecule that contains the added deuteron is observed for the metastable [M + D]⁺ ions of phenyl n-propyl ether labeled at the β position of the alkyl group. Incorporation of a hydrogen atom that originates from the aromatic ring in the expelled propene molecule is of negligible importance as revealed by the minor loss of C₃H₅D from the metastable [M + H]⁺ ions of C₆D₅OCH₂CH₂CH₃ irrespective of whether H₂O, CH₃OH, or CH₃CN is the CI reagent. The combined results for the [M + D]⁺ ions of phenyl n-propyl ether and deuterium-labeled analogs are suggested to be in line with a model that assumes that propene loss occurs not only from species formed by deuteron transfer to the oxygen atom, but also from ions generated by deuteron transfer to the ring. This is substantiated by the results for the methyl-substituted ethers, which reveal that the position as well as the number of methyl groups bonded to the ring exert a marked effect on the relative importances of the losses of C₃H₅D and C₃H₆ from the metastable [M + D]⁺ ions of the unlabeled methyl-substituted species.     

The HNO donor ability of hydroxamic acids upon oxidation with cyanoferrates(III)

The hydroxamic acids (RC(O)NHOH, HA) exhibit diverse biological activity, including hypotensive properties associated with formation of nitroxyl (HNO) or nitric oxide (NO). Oxidation of two HAs, benzohydroxamic and acetohydroxamic acids (BHA, AHA) by [Fe(CN)₅NH₃]^2? or [Fe(CN)₆]^3? was analyzed by spectroscopic, mass spectrometric techniques, and flow EPR measurements. Mixing BHA with both Fe(III) reactants at pH 11 allowed detecting the hydroxamate radical, (C₆H₅)C(O)NO˙^?, as a one-electron oxidation product, as well as N₂O as a final product. Successive UV–vis spectra of mixtures containing [Fe(CN)₅NH₃]^2? (though not [Fe(CN)₆]^3?) at pH 11 and 7 revealed an intermediate acylnitroso-complex, [Fe(CN)₅NOC(O)(C₆H₅)]^3? (λ_max, 465 nm, very stable at pH 7), formed through ligand interchange in the initially formed reduction product, [Fe(CN)₅NH₃]^3?, and characterized by FTIR spectra through the stretching vibrations ν_(CN), ν_(CO), and ν_(NO). Free acylnitroso derivatives, formed by alternative reaction paths of the hydroxamate radicals, hydrolyze forming RC(O)OH and HNO, postulated as precursor of N₂O. Minor quantities of NO are formed only with an excess of oxidant. The intermediacy of HNO was confirmed through its identification as [Fe(CN)₅(HNO)]^3? (λ_max, 445 nm) as a result of hydrolysis of [Fe(CN)₅(NOC(O)(C₆H₅)]^3? at pH 11. The results demonstrate that hydroxamic acids behave predominantly as HNO donors.     

Kinetics and mechanism of pentacyanohydroxoferrate(III) formation from [FeL(OH)2]− complex, (L=N-(2-hydroxyethyl) iminodiacetate anion

Summary The kinetics and mechanism of the system [FeHIDA-(OH)₂]^–+5CN^–[Fe(CN)₅OH^–+HIDA^2–+OH^– (HIDA=N-(2-hydroxyethyl) (iminodiacetate) at pH=9.5±0.02, I=0.1 M and at 25±0.1°C have been studied spectrophotometrically at 395 nm ( _max of [Fe(CN)₅OH]^3–]. The reaction has three distinguishable stages; the first is formation of [Fe(CN)₅OH]^3–, the second is conversion of [Fe(CN)₅OH]^3– into [Fe(CN)₆]^3–, and last is the reduction of [Fe(CN)₆]^3– to [Fe(CN)₆]^4– by the HIDA^2– released in the first stage. The first stage shows variable-order dependence on cyanide concentration, unity at high cyanide concentration and zero at low cyanide concentration. The second stage exhibits first-order dependence on the concentration of [Fe(CN)₅OH]^3– as well as on cyanide. The reverse reaction between [Fe(CN)₅OH]^3– and HIDA^2– is first-order in each of these species and inverse first-order in cyanide. On the basis of forward and reverse rate studies, a five-step mechanism has been proposed for the first stage. The first step involves a slow loss of one OH^–, by a cyanide-independent path.     

Positive and negative methanol cluster ions using a direct fast atom bombardment technique

Positive and negative cluster ions in methanol have been examined using a direct fast atom bombardment (FAB) probe technique. Positive ion (CH₃OH)_IIH ⁺ clusters with n = 1-28 have been observed and their clusters are the dominant ions in the low-mass region. Cluster-ion reaction products (CH₃OH)_II(H₂O)H⁺ and (CH₃OH)_II(CH₃OCH₃)H⁺ are observed for a wide range of n and the abundances of these ions decrease with increasing n. The negative ion (CH₃OH)_II(CH₃O)^? clusters are also readily observed with n = 0-24 and these form the most-abundant negative ion series at low n. The (CH₃OH)_II(CH₂O)^?, (CH₃OH)_II(H_IIO)(CH₂O)^? and (CH₃OH)_II(H₂OXCH₃O)^? cluster ions are formed and the abundances of these ions approach those of the (CH₃OH)_II(CH₃O)^? ion series at high n. Cluster-ion structures and energetics have been examined using semi-empirical molecular orbital methods.     

Mixed-ligand cyanide cobalt(III) complexes with 1,2-cyclohexanediaminetetraacetic acid: Synthesis and photochemical properties

[Co(CN)₂(H₃Cdta)] · 2H₂O (I) and Na₂[Co(CN)(Cdta)] · 3H₂O (II) (Cdta⁴⁻ is the 1,2-cyclohexanediaminetetraacetate) were synthesized. In I, the two cyanide ions and the Cdta nitrogen atoms are located in the equatorial plane, the carboxyl groups connected to different N atoms are in axial positions; in addition one of them, like two other uncoordinated carboxyl groups, is protonated. In II, Cdta is a pentadentate ligand coordinated in the cis-equatorial mode. UV excitation of the dicyano complexes at the ligand-to-metal charge transfer band gives organic derivatives of cobalt(III) stable enough for chromatographic isolation. Photolysis of II in neutral medium gives aqua(cyclohexanediaminetriacetato)cobalt (III) complexes as the final products.     

Double collision experiments

A variety of double collision experiments, whereby fast species undergo collisional interactions in two distinct regions of a mass spectrometer, are described. These include two-stage charge reversal of negative ions, two-stage double electron transfer from targets to cations, neutralization-reionization experiments as well as delayed analysis of organic cations formed in a one-step charge reversal of anions. Experiments have been performed on a number of systems of current interest in gas-phase ion chemistry. It is concluded that autoelectron detachment of benzyl anions leads to benzyl radicals, whereas the collisionally induced electron detachment produces a mixture of benzyl and tropyl radicals. By contrast, electron detachment from [H₃CNH]^? is not a metastable process and occurs only after excitation to produce H₃CNH˙ radicals, which do not rearrange into the thermodynamically more stable H₂CNH₂˙. It is shown that in the double electron transfer reactions H⁺ + Xe→H˙ + Xe⁺˙ and H˙ + Xe→H^? + Xe⁺˙, excited states are produced. From double collision experiments on methyl formate ions, it is concluded that the non-decomposing ions have undergone rearrangement on the time-scale of 10 μs into the distonic isomer, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm H} - \mathop {\rm C}\limits^ + ({\rm OH}){\rm O}\mathop {\rm C}\limits^. {\rm H}_2 $\end{document}. Finally, it is shown that short-lived (<0.2 μs) [H₂, C, N]⁺ ions generated by charge-reversal of [H₂CN]^? have the [H₂CN]⁺ structure, whereas most of the long-lived (10 μs) ions have the [HCNH]⁺ structure.