Chemistry of iron complexes—III. X-ray diffraction,ESR and other spectral studies of new iron(II) and iron(III) complexes with tri-p-tolylarsine oxide

Reactions of iron(II) and iron(III) salts with tri-p-tolylarsine oxide(L) in suitable organic solvents yield complexes of formulas: (i) [FeL₂Cl₂(OH₂)₂] [FeCl₄].2H₂O, [FeL₂Br₂] [FeBr₄].2H₂O; (ii) [Fe(NCS)₃L₂].H₂O; (iii) [FeL(O₂ClO₂)₂(OH₂)] (ClO₄).0.25C₆H₆; (iv) [FeL₃I] [FeI₃].H₂O and (v) [Fe(CO)₃LI]I. Characterization has been done through elemental analyses, IR, far IR, ESR, and reflectance spectra, molar conductance, magnetic moments, t.g.a. and X-ray diffraction (powder) data. The species [FeL₂Cl₂(OH₂)₂]⁺, [FeL₂Br₂]⁺, [Fe(NCS)₃L₂], [FeL(O₂ClO₂)₂OH₂]⁺, [FeL₃I]⁺ and [Fe(CO)₃LI]⁺ have been assigned trans-octahedral, trans-square planar, trans-trigonal bipyramid, trans-octahedral, tetrahedral and cis-trigonal bipyramid structures respectively.     

Cross-Coupling through Ag(I)/Ag(III) Redox Manifold

In ample variety of transformations, the presence of silver as an additive or co-catalyst is believed to be innocuous for the efficiency of the operating metal catalyst. Even though Ag additives are required often as coupling partners, oxidants or halide scavengers, its role as a catalytically competent species is widely neglected in cross-coupling reactions. Most likely, this is due to the erroneously assumed incapacity of Ag to undergo 2e⁻ redox steps. Definite proof is herein provided for the required elementary steps to accomplish the oxidative trifluoromethylation of arenes through Ag^I/Ag^III redox catalysis (i. e. CEL coupling), namely: i) easy Ag^I/Ag^III 2e⁻ oxidation mediated by air; ii) bpy/phen ligation to Ag^III; iii) boron-to-Ag^III aryl transfer; and iv) ulterior reductive elimination of benzotrifluorides from an [aryl-Ag^III-CF₃] fragment. More precisely, an ultimate entry and full characterization of organosilver(III) compounds [K]⁺[Ag^III(CF₃)₄]⁻ ( K-1 ), [(bpy)Ag^III(CF₃)₃] ( 2 ) and [(phen)Ag^III(CF₃)₃] ( 3 ), is described. The utility of 3 in cross-coupling has been showcased unambiguously, and a large variety of arylboron compounds was trifluoromethylated via [Ag^III(aryl)(CF₃)₃]⁻ intermediates. This work breaks with old stereotypes and misconceptions regarding the inability of Ag to undergo cross-coupling by itself.     

Synthesis,structure and magnetic properties of iron (II), cobalt (II) and nickel (II) complexes of 2,6-bis(pyrazol-3-yl)pyridine and paramagnetic counterions

Iron (II), cobalt (II) and nickel (II) complexes of 2,6-bis(pyrazol-3-yl)pyridine (bpp) with [Cr(C₂O₄)₃]³⁻ have been prepared. They were characterised by single-crystal X-ray diffraction, magnetic susceptibility measurements and thermal gravimetric analyses. All three compounds are isostructural and they are formed by isolated [M^II(bpp)₂]²⁺ and [Cr(C₂O₄)₃]³⁻ complexes and free ClO₄ ⁻. As expected, only the salt [Fe(bpp)₂]₂[Cr(C₂O₄)₃]ClO₄·5H₂O shows a thermal spin transition with transition temperature (T_1/2) around 375 K that is correlated to the loss of water molecules.     

Synthesis and characterization of cyclometallated palladium(II) and platinum(II) complexes with amide-thiolate ligands

The redox reaction of bis(2-benzamidophenyl) disulfide (H₂L-LH₂) with [Pd(PPh₃)₄] in a 1:1 ratio gave mononuclear and dinuclear palladium(II) complexes with 2-benzamidobenzenethiolate (H₂L⁻), [Pd(H₂L-S)₂(PPh₃)₂] (1) and [Pd₂(H₂L-S)₂ (μ-H₂L-S)₂(PPh₃)₂] (2). A similar reaction with [Pt(PPh₃)₄] produced only the corresponding mononuclear platinum(II) complex, [Pt(H₂L-S)₂(PPh₃)₂] (3). Treatment of these complexes with KOH led to the formation of cyclometallated palladium(II) and platinum(II) complexes, [Pd(L-C,N,S)(PPh₃)]⁻ ([4]⁻) and [Pt(L-C,N,S) (PPh₃)]⁻ ([5]⁻). The molecular structures of 2, 3 and [4]⁻ were determined by X-ray crystallography.     

Monomere und polymere Dimethylaminothioquadratato‐Komplexe: Die Kristallstrukturen von Nickel(II)‐, Cobalt(II)‐, Silber(I)‐, Platin(II)‐, Gold(I)‐, Quecksilber(II)‐ und Blei(II)‐Dimethylaminothioquadrataten

Monomeric and Polymeric Dimethylaminothiosquarato Complexes: The Crystal Structures of Nickel(II), Cobalt(II), Silver(I), Platinum(II), Gold(I), Mercury(II) and Lead(II) Dimethylaminothiosquarates The ligand 2‐dimethylamino‐3, 4‐dioxo‐cyclobut‐1‐en‐thiolate, Me₂N‐C₄O₂S⁻ (L) forms neutral and anionic complexes with nickel(II), cobalt(II)‐, silver(I)‐, platinum(II)‐, gold(I)‐, mercury(II)‐ and lead(II). According to the crystal structures of seven complexes the ligand is O, S‐chelating in [Ni(L)₂(H₂O)₂]·2 H₂O, [Co(L)₂(CH₃OH)₂] and (with limitations) in [Pb(L)₂·DMF]. In the remaining compounds the ligand behaves essentially as a thiolate ligand. The platinum, gold and mercury complexes [TMA]₂[Pt(L)₄], [TMA] [Au(L)₂] and [Hg(L)₂] are monomeric. In [TMA][Ag₂(L)₃]·5.5 H₂O a chain‐like structure was found. In the asymmetric unit of this structure eight silver ions, with mutual distances in the range 2.8949(4) to 3.1660(3)Å, are coordinated by twelve thiosquarato ligands. [Pb(L)₂·DMF] has also a polymeric structure. It contains a core of edge‐bridged, irregular PbS₄ polyhedra. TMA[Au(H₂NC₄O₂S)₂] has also been prepared and its structure elucidated.     

The 3[ndσ*(n+1)pσ] Emissions of Linear Silver(I) and Gold(I) Chains with Bridging Phosphine Ligands

The complexes [Au₃(dcmp)₂][X]₃ {dcmp=bis(dicyclohexylphosphinomethyl)cyclohexylphosphine; X=Cl^? ( 1 ), ClO₄^? ( 2 ), OTf^? ( 3 ), PF₆^? ( 4 ), SCN^?( 5 )}, [Ag₃(dcmp)₂][ClO₄]₃ ( 6 ), and [Ag₃(dcmp)₂Cl₂][ClO₄] ( 7 ) were prepared and their structures were determined by X‐ray crystallography. Complexes 2 – 4 display a high‐energy emission band with λ_max at 442–452 nm, whereas 1 and 5 display a low‐energy emission with λ_max at 558–634 nm in both solid state and in dichloromethane at 298 K. The former is assigned to the ³[5dσ*6pσ] excited state of [Au₃(dcmp)₂]³⁺, whereas the latter is attributed to an exciplex formed between the ³[5dσ*6pσ] excited state of [Au₃(dcmp)₂]³⁺ and the counterions. In solid state, complex [Ag₃(dcmp)₂][ClO₄]₃ ( 6 ) displays an intense emission band at 375 nm with a Stokes shift of ≈7200 cm^?1 from the ¹[4dσ*→5pσ] absorption band at 295 nm. The 375 nm emission band is assigned to the emission directly from the ³[4dσ^*5pσ] excited state of 6 . Density functional theory (DFT) calculations revealed that the absorption and emission energies are inversely proportional to the number of metal ions (n) in polynuclear Au^I and Ag^I linear chain complexes without close metal???anion contacts. The emission energies are extrapolated to be 715 and 446 nm for the infinite linear Au^I and Ag^I chains, respectively, at metal???metal distances of about 2.93–3.02 Å. A QM/MM calculation on the model [Au₃(dcmp)₂Cl₂]⁺ system, with Au???Cl contacts of 2.90–3.10 Å, gave optimized Au???Au distances of 2.99–3.11 Å in its lowest triplet excited state and the emission energies were calculated to be at approximately 600–690 nm, which are assigned to a three‐coordinate Au^I site with its spectroscopic properties affected by Au^I???Au^I interactions.     

1, 1-Dithiolato-bridged heterobimetallic complexes containing a transition metal ion and oxouranium(VI)

Summary Anionic complexes [UO₂(1, 1-dithiolate)₂]^2– interact strongly with transition metal ions to yield a new class of dithiolato-bridged heterobimetallic complexes MUO₂(1, 1-dithiolate)₂ (M=Co^II, Ni^II, Cu^II, Zn^II or Pb^II, 1, 1-dithiolate = isomaleonitrile dithiolate (i-MNT^2–) and trithiocarbonate (CS ₃ ^2– )). (Et₄N)₂[UO₂(i-MNT)₂] and (Et₄N)₂[UO₂(CS₃)₂] have also been prepared. The complexes have been characterized by elemental analysis, i.r., u.v.-vis. and e.s.r. spectral studies. The heterobimetallic complexes are non-electrolytic, whereas (Et₄N)₂-[UO₂ (i-MNT)₂] and (Et₄N)₂[UO₂(CS₃)₂] are 21 electrolytes. The i.r. data indicate symmetrical bidentate bridging behaviour for the dithiolate ligands. Magnetic moments, electronic spectra and e.s.r. studies are commensurate with a square planar environment around Co^II, Ni^II and Cu^II.     

Two new [Ni(tren)2]2+ complexes: [Ni(tren)2]Cl2 and [Ni(tren)2]WS4

Both title compounds, bis­[tris(2‐amino­ethyl)­amine]­nickel(II) dichloride, [Ni(tren)₂]Cl₂, (I), and bis­[tris(2‐amino­ethyl)­amine]­nickel(II) tetra­thio­tungstate, [Ni(tren)₂]WS₄, (II), contain the [Ni(tren)₂]²⁺ cation [tren is tris(2‐amino­ethyl)­amine, C₆H₁₈N₄]. The tren mol­ecule acts as a tridentate ligand around the central Ni atom, with the remaining primary amine group not bound to the central atom. In (I), Ni²⁺ is located on a centre of inversion surrounded by one crystallographically independent tren mol­ecule. In the [Ni(tren)₂]²⁺ cation of (II), the Ni atom is bound to two crystallographically independent tren mol­ecules. The Ni atoms in the [Ni(tren)₂]²⁺ complexes are in a distorted octahedral environment consisting of six N atoms from the chelating tren mol­ecules. The counter‐ions are chloride anions in (I) and the tetrahedral [WS₄]^2? anion in (II). Hydro­gen bonding is observed in both compounds.     

Influence of the chloride counterion on the redox reactivity of tetraammineplatinum(II) cation with octacyanotungstate(V) anion: Crystal structure of [Pt(NH3)4]2[W(CN)8]

The redox reaction between [Pt(NH₃)₄]²⁺ and [W(CN)₈]³⁻ in the presence of Cl⁻ anions in aqueous solution affords single crystals of [Pt^II(NH₃)₄]₂[W^IV(CN)₈] and [Pt^IV(NH₃)₄Cl₂]Cl₂. Trapped cyano ligands of [W(CN)₈]⁴⁻ rectangular antiprisms of D₂ point symmetry between parallel Pt(II) square planes show that the inner-sphere redox pathway is prohibited. The presence of Cl⁻ counterions enables the formation of [Pt(NH₃)₄Cl₂]Cl₂ as the product of the rare outer-sphere pathway of the oxidation of Pt(II) by [W(CN)₈]³⁻.     

Theoretical studies on ferromagnetic behavior of [Cr(C5(CH3)5)2]+[TCNE]− and [Mn(C5(CH3)5)2]+[TCNQ]−

By using broken-symmetry hybrid-DFT (UB3LYP and UB2LYP) calculation, the effective exchange integrals (J values) of [Cr(C₅(CH₃)₅)₂]⁺[TCNE]⁻[Cr(C₅(CH₃)₅)₂]⁺ and [Mn(C₅(CH₃)₅)₂]⁺[TCNQ]⁻[Mn(C₅(CH₃)₅)₂]⁺ were determined theoretically. Those calculated models were reduced to 3-spin-sites models from X-ray crystallographic data of charge transfer 3D crystal. The calculated results showed that effective exchange integrals were positive and the signs of spin densities on the cyclopentadienyl rings were negative. These results supported the so-called McConnell I mechanism for ferromagnetism proposed by Kollmar et al. and our previous calculations. Natural orbital analysis made it clear that the orbital overlap between SOMO on metals and SOMO on TCNE or TCNQ cations was nearly zero. These results indicated that orbital orthogonality was an important key factor for explaining the ferromagnetism of those systems.     

Syntheses,solid state electronic and infrared spectra of the Ni(II), Pd(II) and Cu(II) complexes of N-(2-hydroxyethyl) and N-(3-hydroxypropyl) oxamide

The new complexes K₂[Ni(Hheo)₂], K₂[Cu(Hheo)₂]·H₂O, K₂[Ni(Hhpo)₂]·H₂O, K₂[M(Hhpo)₂]·0.5H₂O (M = Cu, Pd) and K₂[Cu₂(hpo)₂·0.5H₂O, where H₃heo = N-(2-hydroxyethyl)oxamide and H₃hpo = N-(3-hydroxypropyl)oxamide, have been prepared. Several synthetic routes were investigated and the complexes were characterized by analyses, conductivity measurements, thermogravimetry, magnetic susceptibility and spectroscopy (i.r. and far i.r., diffuse reflectance u.v.). Monomeric square planar structures are found for the [M(Hheo)₂]²⁻ and [M(Hhpo)₂]²⁻ complex anions, while the hpo³⁻ Cu(II) complex appears to be a square planar dimer. The doubly deprotonated Hheo²⁻ and Hhpo²⁻ ions exhibit a bidentate N(secondary amide), N′(tertiary amide)-coordination with the OH-group remaining uncoordinated, while the triply deprotonated hpo³⁻ ion behaves as a bridging N(secondary amide), N′(tertiary amide), O(deprotonated) ligand, while two Cu(II) centres are bridged by two alkoxide-O atoms. The vibrational analysis of the dehydrated complexes is carried out, using NH/ND, OH/OD, ⁵⁸Ni/⁶²Ni and ⁶³Cu/⁶⁵Cu substitutions.     

Kinetics and mechanism of oxidation of ethylenediamine and related compounds by diperiodatoargentate (III) ion

The oxidation of ethylenediamine by diperiodatoargentate (III) ion has been studied by stopped‐flow spectrophotometry. Kinetics of this reaction involves two steps. The first step is the complexation of silver (III) with the substrate and is over in about 10 ms. This is followed by a redox reaction in the second step that occurs intramolecularly from the substrate to the silver (III) center. The rate of reduction of silver (III) species by ethylenediamine, ethanolamine, and 1,2‐ethanediol were observed to be 1.2 × 10⁴, 1.1 × 10², and 0.14 dm³ mol⁻¹ s⁻¹, respectively, at 20°C. The reaction rate shows an inverse dependence on [IO] and [OH⁻] in the low concentration range (≤1 × 10^‐3 mol dm⁻³). At higher [OH⁻] (>1 × 10⁻³ mol dm⁻³) the rate of reaction starts increasing and attains a limiting value at very high [OH⁻]. The rate of deamination of ethylenediamine is enhanced by its complexation with silver (III). The involvement of [Ag^III(H₂IO₆) (H₂O)₂] and [Ag^III(H₂IO₆) (OH)₂]²⁻ are suggested as the reactive silver (III) species kinetically in mild basic and basic conditions, respectively. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 286–293, 2000     

The preparation and x-ray structure of [P(C2H5)4]+[N3]− and the attempted preparation of [PH4]+[N3]−

Tetraethylphosphonium azide, [P(C₂H₅)₄ ]⁺[N₃ ]⁻, was prepared from tetraethyl phosphonium bromide and silver azide. Single crystals of [P(C₂H₅)₄ ]⁺[N₃ ]⁻ were grown from dichloromethane/THF (10:1) solution. The structure was determined by single-crystal X-ray diffraction analysis. [P(C₂H₅)₄ ]⁺[N₃ ]⁻ crystallizes in the monoclinic space group C 2/c with Z = 4 and unit cell dimensions a = 12.961(6), b = 6.835(3), c = 12.378(6) Å, and β = 100.57(4)°. The attempted preparation of phosphonium azide [PH₄]⁺[N₃]⁻ from phosphonium iodide and silver azide lead instead to the formation of PH₃ and HN₃. The instability of [PH₄]⁺[N₃]⁻ with respect to PH₃ and HN₃ is in accord with thermodynamic considerations according to which the reaction PH₃(g) and HN₃(g) to yield [PH₄ ]⁺[N₃ ]⁻ is thermodynamically unfavorable. (Non SI units employed: kcal ≈ 4.184 J, Å = 10⁻¹⁰ m.) © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:129–132, 1998     

Synthesis,spectroscopy and thermal analysis of nickel(II), palladium(II) and copper(II) complexes with N,N′-bis(2-hydroxyethyl)-oxamide

Summary The new complexes K₂[Ni(H₂heo)₂]·3H₂O, K₂[Pd-(H₂heo)₂], K₂[Cu(heo)]·3H₂O and [Cu₂(heo)·2H₂O] {heo = [(CONCH₂CH₂O)₂]^4-} were prepared and characterized by chemical analyses, conductivity measurements, thermogravimetry, magnetic susceptibility and i.r. and u.v. spectroscopy.Monomeric square planar structures with MN₄ coordination spheres are found for the nickel and palladium complex anions.For copper, two different complexes were identified. In slightly alkaline media, a green insoluble nonelectrolyte [Cu₂(heo)·2H₂O] was prepared; the two copper(II) centres are bridged by the tetra-deprotonated ligand in a trans-planar configuration with the H₂O molecules strongly coordinated to the copper(II). The copper(II) monomer has been prepared in strong alkaline media, this anion also contains the tetra-deprotonated ligand in a planar trans form.     

Metal-phenoxyalkanoic acid interactions—XXIII. Complexes of copper(II) with the phenoxyisobutyric acids. The crystal structures of tetra-μ-[2-methyl-2-(4-chlorophenoxy)propanoato-O,O′)]-bis[(2-aminopyrimidine)copper(II)] and two polyaquacopper(II) tri-μ-[2-methyl-2-phenoxypropanoato-O,O′]-bis[(2-methyl-2-phenoxypropanoato)copper(II)] polymorphs

The crystal structures of three copper(II) complexes with phenoxyisobutyric acid (PIBAH) and p-chlorophenoxyisobutyric acid (PCIBAH) have been determined by X-ray diffraction. Tetra-μ-[2-methyl-2-(4-chlorophenoxy)-propanoato-O,O′]-bis[2-amino-pyrimidine)copper(II)], [Cu₂(PCIBA)₄(2-aminopyrimidine)₂]₂ (1) is a centrosymmetric tetracar☐ylate bridged dimer [Cu⋯Cu, 2.689(2)Å] with the nitrogens of the 2-aminopyrimidine molecules occupying the axial positions [CuN, 2.198(7)Å]. Tetraaquacopper(II) tri-μ-[2-methyl-2-phenoxypropanoato-O,O′]-bis[(2-methyl-2-phenoxypropanoato(copper(II)], [Cu(H₂O)₄]²⁺] {[Cu₂(PIBA)₅]⁻}₂, (2), is a disordered precursor of the stable structure (3), [Cu(H₂O)₅]²⁺ {[Cu₂(PIBA)₅]⁻·4H₂O, consisting of centrosymmetric square planar [Cu(H₂O)₄]²⁺ cations and tris(car☐ylate)-bridged dimer anions [Cu⋯Cu, 2.85(1)Å] (2). The fourth position of each square planar dimer ‘end’ is occupied by a car☐ylate oxygen of a PIBA molecule which also provides the ether oxygen capping each axial dimer site [CuO, 2.15(4), 2.19(5)Å]. This completes a five-membered chelate ring. A symmetrical array of eight hydrogen bonds link the four waters of the [Cu(H₂O)₄]²⁺ cation to the car☐yl oxygens of both the capping PIBA ligands of the two dimeric anions. Structure (3) has essentially identical [Cu₂(PIBA)₅]⁻ dimer anions [Cu⋯Cu, 2.929(1)Å] and hydrogen-bonding interactions with the tetraaquacopper(II) cations. However, water molecules partially occupy the octahedral sites of these cations [CuO, 2.46(1)Å], as well as a number of lattice sites in the crystal.     

A New Synthetic Methodology in the Preparation of Bimetallic Chalcogenide Clusters via Cluster-to-Cluster Transformations

A decanuclear silver chalcogenide cluster, [Ag₁₀(Se){Se₂P(OⁱPr)₂}₈] (2) was isolated from a hydride-encapsulated silver diisopropyl diselenophosphates, [Ag₇(H){Se₂P(OⁱPr)₂}₆], under thermal condition. The time-dependent NMR spectroscopy showed that 2 was generated at the first three hours and the hydrido silver cluster was completely consumed after thirty-six hours. This method illustrated as cluster-to-cluster transformations can be applied to prepare selenide-centered decanuclear bimetallic clusters, [Cu_xAg_10-x(Se){Se₂P(OⁱPr)₂}₈] (x = 0–7, 3), via heating [Cu_xAg_7−x(H){Se₂P(OⁱPr)₂}₆] (x = 1–6) at 60 °C. Compositions of 3 were accurately confirmed by the ESI mass spectrometry. While the crystal 2 revealed two un-identical [Ag₁₀(Se){Se₂P(OⁱPr)₂}₈] structures in the asymmetric unit, a co-crystal of [Cu₃Ag₇(Se){Se₂P(OⁱPr)₂}₈]_0.6[Cu₄Ag₆(Se){Se₂P(OⁱPr)₂}₈]_0.4 ([3a]_0.6[3b]_0.4) was eventually characterized by single-crystal X-ray diffraction. Even though compositions of 2, [3a]_0.6[3b]_0.4 and the previous published [Ag₁₀(Se){Se₂P(OEt)₂}₈] (1) are quite similar (10 metals, 1 Se²⁻, 8 ligands), their metal core arrangements are completely different. These results show that different synthetic methods by using different starting reagents can affect the structure of the resulting products, leading to polymorphism.     

Solvent extraction study on the hydrolysis of tracer concentration of Po(IV) in chloride solutions

The hydrolysis and chlorocomplex formation of Po(IV) was investigated through solvent extraction with dithizone-carbon tetrachloride solutions. In a 1.0 M (H,Na)Cl solution, a tracer concentration of Po(IV) (about 10⁻¹² M) was found to exist as; Po(OH)₂Cl₄²⁻, Po(OH)₂Cl_3.7^1.7−, Po(OH)₂Cl_3.5^1.5−, Po(OH)_2.1Cl_2.0⁻ and Po(OH)₄ for −log[H⁺] = 0, 1, 2, 3 and 6, respectively. The constants of successive hydrolysis, β₁ = [Po(OH)₃Cl_n¹⁻ⁿ][Po(OH₄]⁻¹[H⁺]⁻¹[Cl⁻¹]⁻ⁿ and β₂ = [Po(OH)₂Cl_n²⁻ⁿ][Po(OH)₄]⁻¹[H⁺]⁻²[Cl⁻]⁻ⁿ were calculated from the distribution ratios obtained, giving the results; log β₁ = 4.6 ± 0.3 and log β₂ = 8.7 ± 0.3. The chemical composition of extracted species was probably PoCl₂(HDz)₂, Po(OH)Cl(HDz)₂ and Po(OH)₂(HDz)₂.     

Potassium thiocyanate argentates: K3[Ag(SCN)4], K4[Ag2(SCN)6] and K[Ag(SCN)2]

The anions of the title compounds contain [Ag(SCN)₄] units, with the S atoms coordinating to Ag⁺ in a tetrahedral arrangement. Whereas in the isolated anions of tripotassium tetra­thio­cyanatoargentate(I), K₃[Ag(SCN)₄], (I), all SCN^? groups are bonded as terminal ligands, in tetrapotassium di‐μ‐thio­cyanato‐S:S‐bis­[dithio­cyanato­argentate(I)], K₄[Ag₂(SCN)₆], (II), two AgS₄ tetrahedra share one common edge. In poly[potassium [argentate(I)‐di‐μ‐thio­cyanato‐S:S]], K[Ag(SCN)₂], (III), edge‐ and vertex‐sharing of AgS₄ tetrahedra results in infinite [Ag(SCN)₂]^? layers.     

Kinetics of the Fe(II) reduction of trans-halogenopyridinebis(dimethylglyoximato)Co(III) complexes

The kinetics of the Fe(II) reduction of trans-chloro, bromo and iodopyridinebis(dimethylglyoximato)Co(III) have been studied at 30.0±0.1°C and I = 1.0 mol. dm⁻³(NaClO₄) in the [H⁺] range 0.0043–0.115 mol. dm⁻³. The reaction showed an inverse dependence on [H⁺]. The second order rate constant could be expressed in the form k_II = k₁ + k₂(1 + K_B[H⁺])^{−1. The kinetic data were found to be:} Co(DH)₂(py)Cl−k₁ = 0.051 ±0.003 dm³ mol⁻¹s⁻¹, 0.051±0.003 dm³ mol⁻¹ s⁻¹,k₂ = 0.76±0.04 dm³ mol⁻¹ s⁻¹ K_B = 325±8 dm³ mol⁻¹;Co(DH)₂(py)Br-k₁ = 0.071±0.004 dm³mol⁻¹ s⁻¹,k₂ = 1.21±0.04 dm³ mol⁻¹ s⁻¹ K_B = 460±15 dm³ mol⁻¹; Co(DH)₂(py)I-k₁ = 0.075±0.006 dm³ mol⁻¹ s⁻¹,k₂ = 1.91±0.09 dm³ mol⁻¹ s⁻¹ K_B = 625±30 dm³ mol⁻¹. The inverse dependence on [H⁺] suggests an inner-sphere mechanism involving protonated and unprotonated species of the complex. The order of rates for the three complexes was found to be Co(DH)₂(py)I > Co(DH)₂(py)Br > Co(DH)₂(py)Cl.     

Electrical conductivities of bis(1,3-dithiole-2-thione-4,5-dithiolato)rhodate anion salts

RhCl₃·3H₂O reacted with Na₂dmit (dmit²⁻; 1,3-dithiole-2-thione-4,5-dithiolate anion) and [NBu₄ⁿOH in methanol to afford [NBu₄ⁿ][Rh(dmit)₂] (1) and [NBu₄ⁿ]_1.5[Rh(dmit)₂] (2). Salt 1 was oxidized electrochemically in acetonitrile to afford [NBu₄ⁿ]_0.4[Rh(dmit)₂] (3). Suspended powders of 1 or 2 reacted with iodine in hexane to afford [NBu₄ⁿ][Rh(dmit)₂][I₃]_1.3 (4) or [NBu₄ⁿ]_1.5[Rh(dmit)₂[I₃]_0.4 (5). On the other hand, 1 dissolved in acetonitrile, reacted with bromine and iodine to yield [NBu₄ⁿ]_0.25[Rh(dmit)₂Br] (6) and [NBu₄ⁿ]_0.35[Rh(dmit)₂I] (7), respectively. All the salts behave as semi-conductors with electrical conductivities of 1 x (10⁻⁵ − 10⁻⁸) S cm⁻¹ at 25°C measured for compacted pellets. Electronic absorption, ESR and X-ray photoelectron spectra of the salts are discussed.