Complex formation of iron (III) with chrome azurol s

The complex formation of iron(IIl) with 3”-sulpho-2”,6”-dichloro-3,3'-dimethyl-4'-hydroxy-fuchson-5,5'-dicarboxylic acid (chrome azurol S) was studied by spectrophotometric, conductometric and potentiometric methods. The pure tetrabasic acid of the ligand was prepared from the impure trisodium salt (commercially availalile), and the dissociation constants of the ligand were redetermined. At 20° ± 1° and in the presence of 0.10 M potassium chloride the dissociation constants were: pk₁ < 0.0, pk₂ = 2.25 ± 0.05, pk₃ = 4.71 ± 0.03 and pk₄ = 11.81 ± 0.03.In the pH range 2–4, four complexes were detected (the absolute stability constants at 20° ± 5° and at an ionic strength of 0.10 M are given in parentheses) : a ring-formed dimer complex [Fe(H₂O)₂]₂Ch₂^2- (log k_2,2 = 36.2); a monomer of composition [Fe(H₂O)₄]HCh or [Fe(H₂O)₄]HCh^- (the absolute stability constant was calculated as log k_1,1 = 15.6 for the latter composition); a complex [Fe(H₂O)₄]₂Ch²⁺ (log k_3.1=20.2) and, finally, a complex of composition [Fe(H₂O)₂]H_xCh₂^x-5 (the value of x being unknown). In addition, hydroxo complexes of the dimer were formed at higher pH values.     

Reactivity of fac-[PPN][Fe(CO)3(TePh)3]: Structure of Fe2(μTePh)2(NO)4

Addition of NOBF₄ to fac-[PPN][Fe(CO)₃(TePh)₃] in THF at ambient temperature results in formation of Fe₂(μ-TePh)₂(NO)_4l Fe₂(?TePh)₂(CO)₆ and organic products. Methylation of fac-[PPN][Fe(CO)₃- (TePh)₃] by Mel or [Me₃O][BF₄] leads to the known dimer Fe₂(μ.-TePh)₂(CO)₆ and organic products. Fe₂(μ-TePh)₂(NO)₄ crystallizes in the orthorhombic space group P bca, with a = 12.701(5) Å, b = 6.7935(16) Å, c = 21.299(9) Å, V = 1837.8(11) ų, and Z = 4. The core geometry of Fe₂(μ-TePh)₂(NO)₄ is best described as a Fe₂Te₂ planar rhombus with Te-Fe-Te bond angle 112.09(4)°. A Fe-Fe bond (length 2.827(2) Å) is proposed for Fe₂(μ-TePh)₂(NO)₄ on the basis of the 18-electron rule. The iron atom adopts a distorted tetrahedral geometry with acute bridge Fe-Te-Fe angles 67.91(3)°, and bridging Fe-Te bond of length 2.53(1) Å.     

Synthesis and electrochemistry of phenyl-functionalized diiron propanedithiolate complexes with bidentate phosphine ligands

Carbonyl substitution reactions of [μ-(SCH₂)₂CHC₆H₅]Fe₂(CO)₆ with bidentate phosphine ligands, cis-1,2-bis(diphenylphosphine)ethylene (cis-dppv) and N,N-bis(diphenylphosphine)propylamine [(Ph₂P)₂N-Pr-n], yielded an asymmetrically substituted chelated complex [(μ-SCH₂)₂CHC₆H₅]Fe₂(CO)₄(k ²-dppv) and a symmetrically substituted bridging complex [(μ-SCH₂)₂CHC₆H₅]Fe₂(CO)₄[μ-(PPh₂)₂N-Pr-n] under different reaction conditions. Both complexes were fully characterized by spectroscopic methods and by X-ray crystallography. Their electrochemical behaviors were observed by cyclic voltammetry, and the catalytic electrochemical reduction of protons from acetic or trifluoroacetic acid to give dihydrogen mediated by complex [(μ-SCH₂)₂CHC₆H₅]Fe₂(CO)₄(k ²-dppv) was investigated.     

Stable free-radical complexing reagents in applications of electron spin resonance to the determination of metals

Metals can be determined by electron spin resonance (e.s.r.) by using stable free radicals in which the molecules include complexing groups. Such reagents form complexes with metal ions which retain the properties of the free radicals producing the e.s.r. signal. The complexes formed can be separated from the excess of reagent and the metal concentrations measured from the signal intensity. This approach markedly expands the potential of e.s.r. as an analytical technique, because it is not limited to paramagnetic metals. The relatively high sensitivity of free radical determination by the e.s.r. method is an additional advantage. The properties of the spin-labelled β-diketone, 4-acetoacetyl-2,2,5,5-tetramethyl-3-imidazoline-1-oxyl, are described. Dissociation constants are reported for the enol form (pK_a^T = 6.56 ± 0.02) and for the protonated (at the imidazolyl nitrogen) form (pK_a^T = 1.91 ± 0.02), as well as partition constants for the hexane—water (log k_D(C₆H₁₄) = 0.96 ± 0.02) and chloroform—water (log K_D(CHCl₃) = 3.36 ± 0.04) systems. The reagent extracts Cu, Pb, Cd, Hg and Er readily; in the presence of caproic acid iron(III) is also extracted. Copper is extracted as a CuA₂, complex (log K_D = 2.5 ± 0.5; log K_ex = -2.80 ± 0.13; log β₂ = 14.3 ± 1.5). CuA₂ does not give an e.s.r. signal. Iron is extracted as a mixed complex with β-diketone and caproic acid. An extraction—e.s.r. method is reported for the determination of mercury with a detection limit of 2 × 10^-7 M.     

Fragmentation reactions ofN-sulfinylaniline PhNSO by the dinuclear complex [Fe2(CO)7{μ-C(R)C(NEt2)}]: Nitrene and sulfur insertions into iron carbene bonds. Synthesis and x-ray structures of [Fe2(CO)6{μ-N(Ph)C(NEt2)C(Me)S}] [Fe2(CO)6{μ-N(Ph)C(NEt2)C(Ph)S}] · 0.5C6H14 and [Fe2(CO)6{μ-C(C3H5)C(NEt2)N(Ph)SO}] · 0.5CH2Cl2

The diiron ynamine complexes [Fe₂(CO)₇{μ-C(R)C(NEt₂)}] (1) (R=Me, Ph, C₃H₅, SiMe₃) react with theN-sulfinylaniline, PhNSO, in refluxing hexane to yield the complexes [Fe₂(CO)₆{μ-N(Ph)C(Me)S}] (2), [Fe₂(CO)₆{μ-N(Ph)C(NEt₂)C(Ph)S}] · 0.5C₆H₁₂ (3), [Fe₂(CO)₆{μ-C(C₃H₅)C(NEt₂)N(Ph)SO}] · 0.5CH₂Cl₂ (4), and [Fe₂(CO)₆{μ-C(SiMe₃)C(NEt₂)S)}] (5). Compound 5 was found to be identical to the previously reported product obtained from the reaction of 1 with sulfur. Compounds 2, 3, and 4 were characterized by single crystal X-ray diffraction analyses. Crystal data: for 2: space group = P2₁/n,a=9.533(1) Å,b=18.830(4) Å,c=12.705(4) Å, β=107.01(2)°,Z=4, 2687 reflections,R=0.027; for 3: space group=P2₁/n,a=13.660(2) Å,b=19.096(8) Å,c=10.972(2) Å, β=90.62(1)°,Z=4, 2821 reflections,R=0.036; for 4: space group=P2₁/a,a=18.098(5) Å,b=16.564(4) Å,c=18.548(2) Å, β=115.44(2)°,Z=4, 3569 reflections,R=0.041. Complexes 2 and 3 result from fragmentation of theN-sulfinylaniline ligand and insertion of the nitrene grouping into the Fe=C(aminocarbene) bond, whereas the sulfur atom inserts into one Fe-C bond of the bridging carbene. Compound 4 is formed by insertion of the entireN-sulfinyl aniline ligand into the Fe=C(aminocarbene) bond. All three complexes have basket-like arachno structure isolobal to the benzvalene one.     

Interaction of tris(2,2′-bipyrazine)ruthenium(2+) ion with radiolytically-generated radicals in aqueous solution. Reactivity of Ru(bpz)+3 toward electron relays

The one-electron reduction of Ru(bpz)²⁺₃ by (CH₃)₂ḢOH is rapid (k = 3.5 × 10⁹ M^-1 s^-1) and quantitative. The product of the reaction, which possesses a ligand-radical coordinated to a Ru(II) center, can be written generically as Ru(bpz)⁺₃, and represented as Ru(bpz)₂(^.bpz^-)⁺ in alkaline solution and its conjugate acid [Ru(bpz)₂(^.bpzH)²⁺; pK_a = 7.1] in acidic solution. The reaction of Ru(bpz)²⁺₃ with ^.OH (k = 5.5 × 10⁹ M^-1 s^-1) yields the OH-adduct to the ring system of the ligands; Ru(bpz)₂(^.bpzOH)²⁺ is unstable toward bimolecular decay (k ∼4× 10⁸ M^-1 s^-1). Reaction with H^. (k = 3 × 10⁹ M^-1 s^-1) results in hydrogenation at a ring-carbon; this product is unstable in the time frame of seconds. No reaction is observed between Ru(bpz)²⁺₃ and Cl^-.₂. Ru(bpz)₂(^.bpz^-)⁺ reduces Co(sep)³⁺ (k = 3.3 × 10⁵ M^-1 s^-1) at pH 10, but there is no reaction at pH 4. However, Ru(bpz)₂(^.bpzH)²⁺ establishes an electron-transfer equilibrium (K_eq = 7) with Cr(bpy)³⁺₃ at pH 3.     

Iron(III)‐Complexes Engaged in the Biochemical Processes in Seawater. II. Voltammetry of Fe(III)‐Malate Complexes in Model Aqueous Solution

Characteristics of iron(III) complexes with malic acid in 0.55 mol L^?1 NaCl were investigated by voltammetric techniques. Three iron(III)‐malate redox processes were detected in the pH range from 4.5 to 11: first one at ?0.11 V, second at ?0.35 V and third at ?0.60 V. First process was reversible, so stability constants of iron(III) and iron(II) complexes were calculated: log K₁(Fe^III(mal))=12.66±0.33, log β₂(Fe^III(mal)₂)=15.21±0.25, log K₁(Fe^II(mal))=2.25±0.36, and log β₂(Fe^II(mal)₂)=3.18±0.32. In the case of second and third reduction process, conditional cumulative stability constants of the involved complexes were determined using the competition method: log β(Fe(mal)₂(OH)_x)=15.28±0.10 and log β(Fe(mal)₂(OH)_y)=27.20±0.09.     

Ligand substitution of FeRu2(CO)12 and Fe2Ru(CO)12 with tertiary phosphines and phosphites

Ligand substitution of the mixed-metal clusters FeRu₂(CO)₁₂ and Fe₂Ru(CO)₁₂ with triphenylphosphine and trimethylphosphite has been studied. Mono- and di-substituted derivatives have been synthesized and characterized structurally. The following crystal and molecular structures are reported: Fe₂Ru(CO)₁₁PPh₃: triclinic, space group P$\text{1}$, a 9.203(2), b 11.903(3), c 15.117(4) Å, α 81.54(2), β 87.28(2), γ 66.72(2)°, Z = 2; Fe₂Ru(CO)₁₁P(OMe)₃: orthorhombic, space group Pna2₁, a 17.220(5), b 14.572(4), c 8.708(6) Å, Z = 4, FeRu₂(CO)₁₁PPh₃: monoclinic, space group P2₁/n, a 11.435(3), b 16.034(5), c 16.642(4) Å, β 93.35(2)°, Z = 4; FeRu₂(CO)₁₀(PPh₃)₂: orthorhombic, space group Pccm, a 14.854(4), b 17.180(7), c 16.786(12) Å, Z = 4.Ligand substitution is found to occur preferentially at the ruthenium centers of the FeRu₂ and Fe₂Ru clusters. Monosubstitution causes expansion of both of the clusters while the overall geometry is practically unchanged. Disubstitution of FeRu₂(CO)₁₂ causes contraction of the cluster and leads to a formation of carbonyl bridges. The structural trends have been interpreted in terms of electronic and packing effects of ligand substitution. The X-ray structures of Fe₂Ru(CO)₁₂ and FeRu₂(CO)₁₂ are not known; the ligand substitution studies indicate that Fe₂Ru(CO)₁₂ has the same structure as Fe₃(CO)₁₂, and that FeRu₃(CO)₁₂ does not have a Ru₃(CO)₁₂ structure as postulated previously from the IR studies.     

The retro-aldol mechanism in the pyrolysis kinetics of primary,secondary, and tertiary β-hydroxy ketones in the gas phase

The pyrolysis kinetics of primary, secondary, and tertiary β-hydroxy ketones have been studied in static seasoned vessels over the pressure range of 21–152 torr and the temperature range of 190°–260°C. These eliminations are homogeneous, unimolecular, and follow a first-order rate law. The rate coefficients are expressed by the following equations: for 1-hydroxy-3-butanone, log k₁(s^?1) = (12.18 ± 0.39) ? (150.0 ± 3.9) kJ mol^?1 (2.303RT)^?1; for 4-hydroxy-2-pentanone, log k₁(s^?1) = (11.64 ± 0.28) ? (142.1 ± 2.7) kJ mol^?1 (2.303RT)^?1; and for 4-hydroxy-4-methyl-2-pentanone, log k₁(s^?1) = (11.36 ± 0.52) ? (133.4 ± 4.9) kJ mol^?1 (2.303RT)^?1. The acid nature of the hydroxyl hydrogen is not determinant in rate enhancement, but important in assistance during elimination. However, methyl substitution at the hydroxyl carbon causes a small but significant increase in rates and, thus, appears to be the limiting factor in a retroaldol type of mechanism in these decompositions. © John Wiley & Sons, Inc.     

Thermal investigations of nickel–zinc ferrites formation from malate coordination compounds

Nickel–zinc ferrites have been synthesized via thermal decomposition of polynuclear coordination compounds containing as ligand the anion of malic acid, namely (NH₄)[Fe₂NixZn_1–x(C₄H₄O₅)(OH)₃]·nH₂O (x =0.25, 0.5 and 0.75, n=3 and 5). A comparison between the thermal behaviour of the studied polynuclear coordination compounds is inferred. Fe₂NixZn_1–xO₄ (n=0.25, 0.5 and 0.75) ferrites with mean particle sizes of 65–85 Å and free from other phases are formed after a heating treatment of only one hour at 500°C.     

The question of a pressure effect in the reaction OH + HNO3. A laser flash-photolysis resonance-absorption study

Absolute rate constants, k, of the reaction OH + HNO₃ were determined using a pulsed laser photolysis-resonance absorption technique. The measured values, in cm³ mol^-1 s^-1 at ±3σ, 10^-10k(1–16 Torr HNO₃) = 7.57 ± 0.64, k(500 Torr N₂) = 7.20 ± 0.66 and k(600 Torr SF₆) = 8.37 ± 0.45, indicate that any pressure effect on k at 297 K is less than the experimental uncertainty of 10%.     

The kinetics of reductions of some chloropentakis(alkylamine)cobalt(III), aquapentakis(alkylamine)cobalt(III), and trans(O,Cl)-chloroaminoacidatodiethylenetriaminecobalt(III) ions by aquavanadium(II), or aquachromium(II)

The rate of the reduction of chloropentakis(alkylamine)cobalt(III) ions, Co(Cl)(A)₅^staggered2+, (A₅ = (NH₃)₅, trans-(NH₂CH₃)(NH₃)₄, (NH₂CH₃)₅ and (n-NH₂C₃H₇)₅) by vanadium(II) decreases in the following order: (n-NH₂C₃H₇)₅ > (NH₂CH₃)₅ >trans-(NH₂CH₃)(NH₃)₄ > (NH₃)₅. The similar result on the effect of alkylamines on the rate of the reductions of aquapentakis(alkylamine)cobalt(III) ions, Co(H₂O)(A)₅^staggered3+ by vanadium(II) and chromium(II) was obtained. The rate constants of reductions of Co(Cl)(A)₅^staggered2+ by vanadium(II) could be correlated with the rate constants of the reaction of Co(Cl)(A)₅^staggered2+ with iron(II) by the equation of log k_V = 1.3 log k_Fe + 3.6, where k_V and k_Fe are the second-order rate constant of reductions by vanadium(II) and iron(II) respectively. The steric effect of the coordinated alkylamines on the rates of reductions of Co(Cl)(A)₅^staggered2+ and Co(H₂O)(A)₅^staggered3+ by vanadium(II) and the reduction of Co(H₂O)(A)₅^staggered2+ by chromium(II) is relatively small. The effects of concentrations of perchloric acid and N,N-dimethylformamide were examined for the reduction of trans-(O,Cl)Co(Cl)(gly)(dien)⁺ by vanadium(II), where gly and dien represent glycinate ion and diethylenetriamine respectively. An outer-sphere mechanism was suggested for the reductions of Co(Cl)(A)₅^staggered2+ and trans(O,Cl)Co(Cl)(gly)(dien)⁺ by vanadium(II) based on the experimental results obtained.     

Beitrag zum Reaktionsmechanismus der Synthese von Seychellen [1]

New Mechanistical Details Concerning the Synthesis of Seychellen [1] In the last step of our synthesis of Seychellen ( 2 ) [1], the solvolysis of 1 , only one side-product was formed, namely 3 (Scheme 1). Now the structure of 3 has been elucidated, mainly by spectroscopic studies of its derivatives 7 and 9 (Scheme 2). In order to differentiate between two different solvolytic pathways from 1 to 3 (see Scheme 1 and 3) d₃- 1 was prepared. Solvolysis of d₃- 1 proved the mechanism shown in Scheme 1. Solvolysis of 1 and of 2-epi- 1 , respectively, furnished the same product distribution, which makes a common intermediate a very probable. In both cases 10 is an intermediate, which is slowly converted into 2 and 3 . 2-epi- 1 was prepared from 1 (Scheme 5). Kinetic measurements with 1 , d₃- 1 and 2-epi- 1 are also in agreement with the mechanism drawn in Scheme 4: k₁(72°) = (5,2±0,5) · 10^?5 sec^?1, k₁(H)/k₁(D)(72°) = 1,4±0,15; k₂(H)/k₄(H) = 0,66 and k₂(H)/k₂(D) = 2,2 if k₄(H) ≈ k₄(D) is assumed.     

The kinetics and mechanisms of the gas-phase unimolecular eliminations of halogeno esters. Participation of the carbomethoxy group

The kinetics of the gas-phase elimination of several chloroesters were determined in a static system over the temperature range of 410–490°C and the pressure range of 47–236 torr. The reactions in seasoned vessels, and in the presence of a free-radical inhibitor, are homogeneous, unimolecular, and follow a first-order law. The temperature dependence of the rate coefficients is given by the following Arrhenius equations: for methyl 3-chloropropionate, log k₁(s^?1) = (13.22 ± 0.07) - (231.5 ± 1.0) kJ/mol/2.303RT; for methyl 4-chlorobutyrate, log k₁(s^?1) = (13.31 ± 0.25) - (221.5 ± 3.4) kJ/mol/2.303RT; and for methyl 5-chlorovalerate, log k₁(s^?1) = (13.12 ± 0.25) - (221.7 ± 3.2) kJ/mol/2.303RT. Rate enhancements and lactone formation reveal the participation of carbonyl oxygen of the carbomethoxy group. The order COOCH₃-5 > COOCH₃-6 > COOCH₃-4 in assistance is similar to the sequence of group participation in solvolysis reactions. The partial rates for the parallel eliminations to normal dehydrohalogenation products and lactones have been estimated and reported. The present results lead us to consider that an intimate ion-pair mechanism through participation of the carbomethoxy group may well be operating in some of these reactions.     

Single‐Molecule Magnet Behavior in Two Tetranuclear Cyanide‐bridged FeIII2NiII2 Compounds

Two tetranuclear cyanide‐bridged Fe^III₂Ni^II₂ compounds [Ni₂(L1)₄Fe₂(μ‐CN)₄(CN)₂(L2)₂] · 2ClO₄ · CH₃OH · 4H₂O ( 1 ) and [Ni₂(L1)₄Fe₂(μ‐CN)₄(CN)₂(L3)₂] · 2ClO₄ ( 2 ) [L1 = 4,4′‐dichloro‐2,2′‐bipyridine; L2 = hydrotris(pyrazolyl)borate; L3 = tetrakis(pyrazolyl)borate] were synthesized. Magnetic measurements indicated that both two compounds showed single‐molecule magnet (SMM) behaviors with the relaxation energy barrier of Δ/k_B = 68.9(8) K for 1 and 12.6(1) K for 2 . Magneto‐structural analysis indicated that the intermolecular interactions played an important part in the slow magnetic relaxation behaviors.     

Kinetics and mechanism of base hydrolysis of cis-(ammine) bis (ethylenediamine) (substituted salicylato) cobalt(III) complexes

The kinetics of base hydrolysis of cis-(ammine) bis (ethylenediamine) (substituted salicylato) cobalt(III) complexes, [Co{CO₂C₆H₃(X)(OH)}(NH₃)(en)₂]²⁺ (X = H, 5-SO₃⁻, 5-Br, 5-NO₂ and 3-NO₂), have been investigated in aqueous medium of I = 1.0 M. The phenate species, [Co{CO₂C₆H₃(X)(0)}(NH₃)(en)₂]⁺, have been found to undergo base hydrolysis via two path ways, i.e. one zero order in [OH⁻] (k₁ path) and another first order in [OH⁻] (k₂ path). The alkali independent rate constant (k₁) increases with the basicity of the phenate group and the plot of log k₁ against pK_OH of the complexes is a straight line with a positive gradient of 0.98±0.03. In contrast to this the plot of log k₂ against pK_OH has a gradient of −0.15±0.02. The latter correlation indicates that the electron withdrawing substituents in the salicylate moiety enhance the rate of base hydrolysis in the alkali dependent path. The reaction is not subject to imidazole catalysis in both k₁ and k₂ paths. Substantially high positive values of ΔS^≠ for both the paths are observed. Several mechanistic possibilities have been considered. SN₁CB mechanism involving the rate limiting CoO bond fission in the triagonal bipyramidal transition state appears to be best suited for both the paths. For the alkali independent path the unbound phenate group is suggested to generate the reactive conjugate base by abstracting the NH proton from the coordinated amine.     

Mössbauer study of some Fe-containing M6 and M5 clusters

Isomer shift (δ) and quadrupole splitting (Δ) parameters have been assigned to the iron sites in [FeRh₅(CO)₁₆]⁻, trans- and cis-[Fe₂Rh₄(CO)₁₆]²⁻, [Fe₃-Rh₃(CO)₁₇]³⁻, [FeRh₄(CO)₁₅]²⁻, [Fe₃Pt₃(CO)₁₅]²⁻ and [Fe₄M(CO)₁₆]²⁻ (M = Pd or Pt) from ⁵⁷Fe Mössbauer spectra recorded at 78 K. The data for the closo compounds [FeRh₅(CO)₁₆]⁻ and [Fe₂Rh₄(CO)₁₆]²⁻ are compared with those for [Fe₆(CO)₁₆C]²⁻. In [Fe₃Rh₃(CO)₁₇]³⁻, the three major Fe sites were identified. For both [Fe₄M(CO)₁₆]²⁻ compounds two isomers were shown to be present in the solid state.     

A new refinement of the crystal structure of the inverse weberite Fe2F5(H2O)2

Fe₂F₅(H₂O)₂ is related to the weberite structure, whose space group is not clearly defined. A careful reexamination of the structure confirms and refines the previous results: Fe₂F₅(H₂O)₂ belongs to the space group Imma with cell parameters a = 7.477(1) Å, b = 10.862(2) Å, c = 6.652(1) Å (Z = 4). The structure has been refined from 379 reflections to R = 0.029 (R_w = 0.034). Fe₂F₅(H₂O)₂ must be considered as an antiweberite structure since M²⁺ and M³⁺ positions are inverse of those of the weberite structure.     

Hydrothermal synthesis,thermal decomposition and optical properties of Fe2F5(H2O)(Htaz)(taz)(Hdma)

Crystal structure of Fe₂F₅(H₂O)(Htaz)(taz)(Hdma) which crystallizes in the triclinic system space group $\text{P}\overline{1}$ with unit cell parameters a = 8.8392(5) Å, b = 9.1948(5) Å, c = 9.5877(5) Å, α = 82.070(3)°, β = 63.699(3)°, γ = 89.202(3)°, Z = 2, and V = 690.91(7) ų, was synthesized under hydrothermal conditions at 393 K for 72 h, by a mixture of FeF₂/FeF₃, 1,2,4-triazole molecule (Htaz), and hydrofluoric acid solution (HF 4%) in dimethylformamide solvent (DMF). The main feature of this material is the coexistence of two oxidation states for iron atoms (Fe²⁺, Fe³⁺) in the unit cell, which associate by opposite fluorine corners of FeF₅N and FeF₂N₄ octahedra, and/or triazole molecule which originates the 2D produces material. The structure determination, performed from single crystal X-ray diffraction data, lead to the R₁/_WR₂ reliability factors 0.031/0.087. Thermal stability studies (TG/DTG/DTA) show that the decomposition provides in the temperature range 473–773 K and no mass loss was detected before 473 K. Mass spectrometry (MS) has been used. The optical absorption of the solid was measured at the corresponding λ_max using UV–vis diffuse-reflectance spectrum.     

Reaction of iron pentacarbonyl with N,N-diethyl-S-ethylcarbamate; crystal structure of [{Fe(CO)6}3(μ4-S)2(μ-CNEt2)2]3(feFe), a compound containing three butterfly units

Reaction of iron pentacarboynl with N,N-diethyl-S-ethylcarbamate {SC-(NEt₂)SEt} gave [{Fe₂(CO)₆}{Fe₃(CO)₉(μ₄-S)(μ-CNEt₂(μ-SEt)}](FeFe)3-(FeFe) (I) and [{Fe₂(CO)₆}₃(μ₄-S)₂(μ-CNEt₂3(FeFe) (II). The structure of complex II has been determined by single crystal X-ray crystallography. It crystallizes from methylene chloride as C₂₆H₂₀O₁₈N₂S₂Fe₆·1/2CH₂Cl₂ in the monoclinic space group C2/c with a 46.754(2), b 9.268(1), c 19.628(2) Å, β 100.7(1)°, Z = 8, V 8358.6 ų, D_c 1.77 g cm⁻³, D_m 1.77 gm cm⁻³. The strucutre was solved by direct methods and refined to R = 0.0819 (R_w = 0.0469) for 3017 relfections. It consists of three metalmetal bonded Fe₂(CO)₆ units linearly linked in butterfly configuration by two bridging sulphur athoms, and terminated on both sides by bridging diethylimoniocarbene (CNEt₂) ligands.