Pseudohalide Ions Research Articles

Influence of Pseudohalide Ions on the Molecular Structure and Magnetic Properties of the Manganese(II)−Bipyrimidine−Pseudohalide System

The compounds [Mn2(bpm)3(NCS)4] (1), [Mn(bpm)(NCO)2] (2), and [Mn2(bpm)(N3)4] (3) (where bpm= 2,2‘-bipyrimidine) have been synthesized and characterized. Compound 1 crystallizes in the triclinic P1 space group, with a = 9.122(1) A, b = 9.229(1) A, c = 11.710(2) A, α = 74.89(1)°, β = 80.30(1)°, γ = 61.04(1)°, V = 831.7(2) A3, Z = 2, R(Fo) = 0.029, and wR(Fo2) = 0.078. Compound 2 crystallizes in the monoclinic C2/c space group, with a = 7.309(1) A, b = 14.498(2) A, c = 10.740(4) A, β = 99.93(4)°, V = 1121.0(5) A3, Z = 4, R = 0.025, and wR(Fo2) = 0.060. In the case of compound 3, the crystal parameters of the monoclinic C2/m space group are a = 6.206(2) A, b = 15.084(2) A, c = 8.909(1) A, β = 95.75(2)°, V = 829.8(3) A3, Z = 4, R = 0.029, and wR(Fo2)= 0.069. The pseudohalide ions have a dramatic influence in the molecular structures of the three compounds. Compound 1 is dinuclear, with the manganese(II) ions bridged by bpm ligands and with terminal bpm and NCS groups; compound 2 is a linear chain of manganes...

Binary and ternary complexes involving manganese(II), 2,2’-bipyridine and halide or thiocyanate ions inN,N-dimethylformamide

Ternary complexation involving the manganese(II) ion, 2,2’-bipyridine (bipy), and halide (chloride, bromide) or pseudohalide (thiocyanate) ions has been studied by precise titration calorimetry inN,N -dimethylformamide (DMF) at 298K. All the titration curves are explained well in terms of formation of mononuclear complexes of the type [MnXm(bipy)n](2-m) + (X = CI, Br or SCN), and the formation of [MnCl(bipy)]+, [MnCl2(bipy)], [MnCl(bipy)2]+ and [MnCl2(bipy)2] has been established in the chloride system, [MnBr(bipy)]+, [MnBr2(bipy)], [MnBr(bipy)2]+ in the bromide system, and [Mn(NCS)(bipy)]+, [Mn(NCS)2(bipy)], [Mn(NCS)3(bipy)]-, [Mn(NCS)(bipy)2]+, and [Mn(NCS)2(bipy)2] in the thiocyanate system. The data were analyzed on the basis of the thermodynamic parameters for the binary MnlIbipy and MnII-X (X = Cl, Br and SCN) systems, the latter being determined in previous work. The formation constants, reaction enthalpies, and entropies of the ternary complexes were extracted. The thermodynamic parameters thus obtained are discussed in comparison with those of the corresponding systems of other transition metal(II) ions.

Investigation of the vibrational properties of CN–on a Pt electrode by in situ VIS–IR sum frequency generation and functional density calculations

The vibrational properties of CN– pseudohalide ions adsorbed on a Pt(110) single-crystal electrode in aqueous neutral solution are studied using in situ VIS–IR sum frequency generation (SFG) and compared to theoretical results obtained from density functional theory (DFT) calculations on PtNC– and PtCN– molecular ions. As observed previously on a polycrystalline electrode, the adsorption behaviour of both ions depends drastically on the electrode potential and on the immersion potential in a CN–-containing solution. When the electrode is immersed at negative potential, two absorption bands are detected in the spectral range of the CN– stretching vibration modes on a surface site. The first resonance at 2070 cm–1 is already observed at –1.4 V (Ag/AgCl), in the hydrogen evolution potential region, with an initial potential tuning rate of 20 cm–1. A second narrow resonance, peaking at 2150 cm–1, starts growing at –0.6 V (Ag/AgCl). The occurrence of two resonances, corresponding to N-bound and C-bound CN– species, is clearly evidenced for a single-crystal electrode, and appears as a genuine property of the system, not a side effect induced by surface defects. The polycrystalline structure and the defects influence the shape, the position and the width of the resonances, not the basic spectroscopic properties of the system. This result is further supported by new density functional calculations of the vibrational properties of the PtCN– and PtNC– molecular ions.

Synthesis and electrochemistry of heterobridged gold(I) and gold(II) complexes of pyridine-2-thiolate. Crystal structures of [Au2{µ-(CH2)2PPh2}(µ-C5H4NS)] and [Au2{µ-(CH2)2PPh2}(µ-C5H4NS)Br2

The reaction of [Au2{µ-(CH2)2PPh2}2] or [Au2(µ-L–L)2][ClO4]2[L–L = dppm (Ph2PCH2PPh2) or dppe (Ph2PCH2CH2PPh2)] with [Aun(µ-C5H4NS)n] led to the heterobridged dinuclear complexes [Au2{µ-(CH2)2PPh2}(µ-C5H4NS)] or [Au2(µ-C5H4NS)(µ-L–L)]ClO4. The structure of [Au2{µ-(CH2)2PPh2}(µ-C5H4NS)] has been established by X-ray crystallography and exhibits a short intermolecular gold–gold distance of 2.8623(7)Å, whereas the shortest intermolecular distance is 3.984 Å. The complex crystallized in the monoclinic space group P21/n with a= 9.430(2), b= 8.819(2), c= 22.786(5)Å, β= 99.08(3)°, Z= 4. Cyclic voltammograms showed that this complex is irreversibly oxidised at a platinum electrode; chemical oxidation with the ferrocenium ion in the presence of halide or pseudohalide ions gave the gold(II) complexes [Au2{µ-(CH2)2PPh2}(µ-C5H4NS)X2](X = Cl, Br, I or SCN). The same derivatives can be obtained by oxidative addition of halogen and/or by subsequent substitution with other halogens or pseudohalogens. The complex [Au2{µ-(CH2)2PPh2}(µ-C5H4NS)Br2] crystallized in the triclinic space group P with a= 14.810(10), b= 14.908(10), c= 17.041(12)Å, α= 70.20(5), β= 69.77(5), γ= 89.19(5)°, Z= 6 (at –100 °C). The Au–Au bond lengths in the three independent molecules are 2.564(4), 2.548(4) and 2.547(4)Å.

Mechanism of the Gif-Barton type alkane functionalization by halide and pseudohalide ions

The functionalization of alkanes by halide ions under the conditions of a Gif system can be explained by free-radical redox processes. The evidence is provided by trapping the intermediate alkyl radical by protonated heteroaromatic bases.

Interaction of halide and pseudohalide ions with triplet benzophenone-4-carboxylate: kinetics and radical yields

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInteraction of halide and pseudohalide ions with triplet benzophenone-4-carboxylate: kinetics and radical yieldsJohn K. Hurley, Henry Linschitz, and Avner TreininCite this: J. Phys. Chem. 1988, 92, 18, 5151–5159Publication Date (Print):September 1, 1988Publication History Published online1 May 2002Published inissue 1 September 1988https://doi.org/10.1021/j100329a019RIGHTS & PERMISSIONSArticle Views341Altmetric-Citations83LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts

Nitrosyl complexes of cobalt with hybrid bidentate ligands containing phosphorus and sulfur donor atoms

Nitric oxide reacts with [Co(PSR) 2](BF 4) 2 (PSR  1-(thioalkyl)-2-(diphenylphosphino)ethane) to form five-coordinate mononitrosyl {CoNO} 8 complexes. On the basis of infrared and NMR data the [Co(NO)(PSR) 2] 2+ cations are believed to have a trigonal–bipyramidal geometry, with a linear Co–NO linkage. The mononitrosyl derivatives disproportionate in solution giving [Co(NO) 2(PSR) 2] + species, and probably Co(III) compounds. The stoichiometry of this reaction was examined in different solvents and in the presence of added halide or pseudohalide ions by NMR and IR techniques. The cobalt(III) complex [Co(NCS) 2(PSEt) 2]BF 4 has been isolated and characterized.

Charge transfer complexes of diquat and paraquat with halide anions

The association of methylviologen, 1,1′-dimethyl-4,4′-bipyridynium (PQ2+), with halide and pseudo-halide ions was studied in water at 25 °C by ultraviolet spectrophotometry. A charge transfer band could be observed in the region around 300 nm. From difference absorption measurements the first association constant (K1,) was obtained as 1.7 (Cl−), 3.3 (Br−), 3.9 (I−), 0.7 (CN−), and 2.0(SCN−) M−1. Similar results were obtained for the dication, 6,7-dihydrodipyrido[1,2-a:2′,1′-c]pyrazinium (DQ2+), with first association constants 3.3 (Cl−), 4.1 (Br−) and 4.6 (I−) M−1. First and second (K2) association constants were also determined by a potentiometric technique using ion selective electrodes: K1 = 2.0 M−1; K2 = 0.4 M−1 for the system PQ2+–Cl− and K1 = 5.3 M−1; K2 = 0.3 M−1 for DQ2+Br−.

ChemInform Abstract: The Redox Potential of the Azide/Azidyl Couple

Abstracthas been studied by direct pulse radiolysis experiments with halide and pseudohalide (Br, I, SCN) ions and radicals and by cyclic voltammetry.

Determination of stability constants of some cadmium complexes by polarographic techniques in the presence of electrode adsorption

The reduction of cadmium ion in the presence of several halide or pseudohalide ions is studied by means of dc, DP, ac 1, and ac 2, polarography, using a dropping mercury electrode, in order to evaluate the effects of adsorption on the apparent stability constants of cadmium complexes as calculated from the polarographic parameters measured by the four different techniques. A graphical procedure for solving the DeFord and Hume equation and a computer program by Leggett are used for the calculation. Ligand adsorption and cadmium-ion induced adsorption affect differently the polarograms obtained from each technique and the stability constants evaluated therefrom. In the presence of adsorption it is not possible to reach a coherent set of values for the stability constants in any one of the systems under study. The stronger is the adsorption the more the values obtained differ from those obtained from potentiometric measurements.

Effect of Growth Conditions on Halomethane Production by Phellinus Species: Biological and Environmental Implications

Production of the gaseous secondary metabolite chloromethane (CH,Cl) by the fungus Phellinus pomaceus has been measured on a variety of media using headspace techniques. On glucosebased media, CH3C1 production was linearly related to the logarithm of chloride ion concentration. At concentrations less than 4 mM, over 90% of the chloride ion in the medium was converted to CH3C1. Bromide and iodide, but not fluoride, were substrates for the methylating system. The pH range 5 to 7 was optimal for CH3C1 biosynthesis and the presence of ammonium ions stimulated the process. Supplementation of the medium with methionine, serine or folic acid did not affect overall CH3CI production. With cellulosic media, CH3C1 yields based on chloride ion present in the medium were high, ranging from 75% at 0.4 mM to 90% at 50m~. Bromomethane yields from bromide averaged 70% between 0.5 and 25 mM. Iodomethane yields of approximately 60% were obtained with up to 1 mM-iodide but declined sharply above this concentration. When equimolar concentrations of the three halide ions were present, the different halides were methylated sequentially, iodide being the most preferred substrate and chloride the least. Gas chromatography/mass spectrometry of other headspace volatiles from P. pomaceus mycelia revealed, amongst the main components, methyl esters of 2-furoic, benzoic and salicylic acids. The pseudohalide ion thiocyanate acted as a specific inhibitor of not only halomethane biosynthesis but also methyl benzoate formation, suggesting that methylation of halide and benzoate may be mediated by the same biochemical system. Of five other species of Phellinus previously reported to produce CH,Cl, only P. ribis and P. occidentalis exhibited high efficiency conversion of chloride ion to CH3Cl. P. robiniae converted only a small proportion of available chloride to CH3Cl, whilst no CH3Cl production by P. conchatus or P. vinosus could be demonstrated on any of the media employed. The biochemical, ecological and environmental significance of fungal halomethane biosynthesis is discussed.

The short-range mechanism of surface enhanced raman scattering

Abstract In addition to the electromagnetic influences which increase the local field at the surface of suitably rough free-electron-like metals, molecule and site specific electronic resonances are also frequently operative. This leads to enhanced scattering beyond that caused by the electromagnetic mechanism alone. The electronic resonances involve charge-transfer excitation between members of an active complex MwAgxCly(H2O)z which involves the probe molecule M and, in the electrochemical environment, the constituents of the solution. These complexes allow the resonance to be communicated to Raman transitions in all members of the complex. The stability of the complexes are sensitive to changes in the environment, such as the applied voltage and to the presence of foreign metal ions, through induced changes in y, the number of halide or pseudo-halide ions in the complex. Through analysis of the vibrational signature of the probe molecule under various environmental influences we are able to observe subtle changes in the character of the bonding between that molecule and the rest of the complex. These changes can also be interpreted as indirect results of changes in the value of y.

The short-range mechanism of surface enhanced raman scattering

In addition to the electromagnetic influences which increase the local field at the surface of suitably rough free-electron-like metals, molecule and site specific electronic resonances are also frequently operative. This leads to enhanced scattering beyond that caused by the electromagnetic mechanism alone. The electronic resonances involve charge-transfer excitation between members of an active complex M w Ag x Cl y (H 2O) z which involves the probe molecule M and, in the electrochemical environment, the constituents of the solution. These complexes allow the resonance to be communicated to Raman transitions in all members of the complex. The stability of the complexes are sensitive to changes in the environment, such as the applied voltage and to the presence of foreign metal ions, through induced changes in y, the number of halide or pseudo-halide ions in the complex. Through analysis of the vibrational signature of the probe molecule under various environmental influences we are able to observe subtle changes in the character of the bonding between that molecule and the rest of the complex. These changes can also be interpreted as indirect results of changes in the value of y.

REACTIONS OF DI(1-PYRAZOLYL)PROPANE-COPPER(II) COMPLEXES WITH VARIOUS ANIONS

Abstract The reactivity of some di(1-pyrazolyl)propanecopper (II) complexes with various anions in aqueous solutions has been studied. Di(1-pyrazolyl)propanecopper (II) chloride, Cu(Me2CpZ2)Cl2, reacts readily with pseudohalide ions to give complexes of the type, Cu(Me2Cpz2)Z2 (Z=SCN−, NCO−, N3 −). With PF6 − and BPh4 − anions, complexes of the type [Cu(Me2Cpz2)2X] Y (Y=PF6 −, X=Cl−, Br− and NO3 −; Y=BPh4 −, X=Cl−) are formed. However, the reaction of Cu(Me2Cpz2)Cl2 with acetylacetonate (acac), dialkyldithiocarbamate (S2CNMe2, S2CNEt2), or poly(1-pyrazolyl)borate (H2BPz2 −, HBpz3 −) anions leads to the displacement of Me2CPz2 and the subsequent formation of neutral Cu(acac)2, Cu(S2CNR2)2, Cu(H2Bpz2)2 and Cu(HBpz3)2 complexes. Reaction products have been characterised by elemental analysis, magnetic moments and infrared spectral measurements.

Thermodynamic Studies on the Complexation Reactions of Copper(II) Complex of o2n2-Donor Macrocycle with Halide and Pseudohalide Ions

Complexation reactions of 5,6,7,8,9,10,16,17-octahydrodibenzo[e, m][1, 4]dioxa-[8, 11]diazacyclotetradecine-copper(II) complex with halide and pseudohalide ions have been studied at 25.0° in three water-methanol mixed solvents by spectro-photometric method. It is found that the equilibrium constants increases in the order of 50 vol.% CH3OH<75 vol.% CH3OH<95 vol.% CH3OH for solvents and I-<Br−<CI−<SCN−, N−3 for anions.

Comment on the positron reactions with pseudo-halides in water

Comments are made on the data reported by Mogensen, Pedersen and Andersen on positron reactions with pseudo-halide ions in water and on their interpretation. Although some of our previous experimental curves are in agreement with theirs, there is a major discrepancy with some of their semi-empirical data, pointing to internal inconsistencies in their results. The possibility of another interpretation of the data is suggested.

Specific adsorption of halide and pseudohalide ions at electrochemically roughened versus smooth silver-aqueous interfaces

The differential capacitance of electrochemically roughened silver surfaces in mixed perchlorate electrolytes containing chloride, bromide, iodide, thiocyanate, or azide anions has been measured as a function of electrode potential and anion concentration. These results are compared with corresponding data for electropolished silver in order to ascertain the influence of surface roughening on the double-layer structure and composition of polycrystalline silver-aqueous interfaces. The surface concentrations of specifically adsorbed anions were obtained from these capacitance-potential data using a “Hurwitz-Parsons” type of analysis. Although electrochemical roughening by means of a conventional oxidation-reduction cycle in chloride media is a prerequisite to the appearance of Surface-Enhanced Raman Scattering (SERS) for these adsorbates, it yields only moderate (ca. 1.5- to 2-fold) increases in the actual surface area and has a relatively minor effect on their average surface concentration. However, roughening does induce noticeable changes in the morphology of the capacitance-potential curves which are traced to alterations in the surface-crystallite structure. Comparisons between the potential dependence of SERS with corresponding capacitance-potential data indicate that anion coverages close to a monolayer are necessary for stable SERS. This is attributed to the stabilization of Raman-active silver clusters by surrounding adsorbed anions.

Solvated positron chemistry. Positron reactions with pseudo-halide ions in water

The hydrated positron e + aq reactions with SCN −, OCN −, CN −, S 2− were studied by means of the angular correlation technique. The positron forms bound states with SCN −, CN −, and S 2− but not with OCN −. Apparently, the e + aq reaction with SH − results in a positron bound state with S 2−. It was difficult to determine the shapes of the bound-state angular correlation curves. Only in the SCN − case could a very rough estimate of the rate constant be obtained. Estimates of the binding energies relative to those of the corresponding halide ion states could be determined for SCN − and S 2−.

ChemInform Abstract: COMPLEXES OF RHODIUM(I) WITH CARBON MONOXIDE, BIS(DIPHENYLPHOSPHINO)METHANE, OR BIS(DIPHENYLARSINO)METHANE, AND VARIOUS ANIONIC LIGANDS

AbstractDie Rh(I)‐Komplexe (II), (V), (VIIb) und (VIII) mit CO, Bis‐[diphenylphosphino bzw. ‐arsino]‐methan und anionischen Liganden ausgehend vom Cyclooctadien‐Dimeren (I) werden dargestellt, ihre Strukturen und Eigenschaften verglichen mit bekannten Komplexen, die terminale oder brückenbildende Chlorid‐Liganden enthalten, und diskutiert.

Complexes of rhodium(I) with carbon monoxide, bis(diphenylphosphino)methane, or bis(diphenylarsino)methane, and various anionic ligands

Complexes of rhodium(I) with carbon monoxide, bis(diphenylphosphino)methane (dppm), or the arsine analogue (dpam), and a variety of anionic ligands are described, and the natures of each of the novel complexes are compared with those of known complexes containing terminal or bridging chloro-ligands. In solution in acetone–methanol and in the presence of halide ions (X = Cl–, Br–, or I–) cationic dinuclear ‘A-frame’ complexes [Rh2(µ-X)(CO)2L2]+ and [Rh2(µ-X)(µ-CO)(CO)2L2]+(L = dppm or dpam) are readily formed. In the presence of the pseudohalide ions (Z = CN– or SCN–) the neutral complexes [Rh2Z2(CO)4L2] are initially formed. The cyano-complexes readily dissociate one (dppm) or two (dpam) moles of CO respectively. When Z is OCN– or N3– the products are dinuclear dicarbonyl complexes [Rh2Z2(CO)2L2].