Metal Chloride Complexes Research Articles

Spatial and temporal zoning of hydrothermal alteration and mineralization in the Sossego iron oxide–copper–gold deposit, Carajás Mineral Province, Brazil: paragenesis and stable isotope constraints

The Sossego iron oxide–copper–gold deposit (245 Mt @ 1.1% Cu, 0.28 g/t Au) in the Carajas Mineral Province of Brazil consists of two major groups of orebodies (Pista–Sequeirinho–Baiano and Sossego–Curral) with distinct alteration assemblages that are separated from each other by a major high angle fault. The deposit is located along a regional WNW–ESE-striking shear zone that defines the contact between metavolcano–sedimentary units of the ∼2.76 Ga Itacaiunas Supergroup and tonalitic to trondhjemitic gneisses and migmatites of the ∼2.8 Ga Xingu Complex. The deposit is hosted by granite, granophyric granite, gabbro, and felsic metavolcanic rocks. The Pista–Sequeirinho–Baiano orebodies have undergone regional sodic (albite–hematite) alteration and later sodic–calcic (actinolite-rich) alteration associated with the formation of massive magnetite–(apatite) bodies. Both these alteration assemblages display ductile to ductile–brittle fabrics. They are cut by spatially restricted zones of potassic (biotite and potassium feldspar) alteration that grades outward to chlorite-rich assemblages. The Sossego–Curral orebodies contain weakly developed early albitic alteration and very poorly developed subsequent calcic–sodic alteration. These orebodies contain well-developed potassic alteration assemblages that were formed during brittle deformation that resulted in the formation of breccia bodies. Breccia matrix commonly displays coarse mineral infill suggestive of growth into open space. Sulfides in both groups of deposits were precipitated first with potassic alteration and more importantly with a later assemblage of calcite–quartz–epidote–chlorite. In the Sequeirinho orebodies, sulfides range from undeformed to deformed; sulfides in the Sossego–Curral orebodies are undeformed. Very late, weakly mineralized hydrolytic alteration is present in the Sossego/Currral orebodies. The sulfide assemblage is dominated by chalcopyrite with subsidiary siegenite, and millerite. Pyrrhotite and pyrite are minor constituents of ore in the Sequerinho orebodies while pyrite is relatively abundant in the Sossego–Curral bodies. Oxygen isotope partitioning between mineral pairs constrains temperatures in the deposit spatially and through time. In the Sequeirinho orebody, the early sodic–calcic alteration stage was characterized by temperatures exceeding 500°C and $$ \delta ^{{{\text{18}}}} {\text{O}}_{{{\text{H}}_{{\text{2}}} {\text{O}}}} $$ values for the alteration fluid of 6.9 ± 0.9‰. Temperature declines outward and upward from the zone of most intense alteration. Paragenetically later copper–gold mineralization displays markedly lower temperatures (<300°C) and was characterized by the introduction of 18O-depleted hydrothermal fluids −1.8 ± 3.4‰. The calculated δDH2O and $$ \delta ^{{{\text{18}}}} {\text{O}}_{{{\text{H}}_{{\text{2}}} {\text{O}}}} $$ values suggest that the fluids that formed the early calcic–sodic alteration assemblage were of formational/metamorphic or magmatic origin. The decrease of $$ \delta ^{{{\text{18}}}} {\text{O}}_{{{\text{H}}_{{\text{2}}} {\text{O}}}} $$ values through time may reflect influx of surficially derived waters during later alteration and mineralization events. Influx of such fluids could be related to episodic fluid overpressure, resulting in dilution and cooling of the metalliferous fluid, causing deposition of metals transported as metal chloride complexes.

Synthesis, characterization and antimicrobial activity studies of N - N ′-tetracarboxydiethyloxamide ligand and its metal(II) complexes

N-N′-tetracarboxydiethyloxamide (hereafter abbreviated as H6L) was prepared by using L-aspartic acid and diethyl oxalate (DEO). A series of binuclear complexes of divalent metal chlorides viz. Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) with H6L have been prepared. Spectral studies (IR, UV and NMR) magnetic susceptibility, elemental analysis and molar conductance measurements confirm the formation of binuclear complexes, [M2H2L]/[M2H2L · 4H2O]. Electronic absorption spectra and magnetic susceptibilities suggest square-planar stereochemistry for Cu(II) and tetrahedral for Zn(II) complexes. Mn(II), Co(II), and Ni(II) coordinate two molecules of water and consequently show octahedral geometry. The in vitro antimicrobial activity of the synthesized compounds is discussed against bacterial strains such as S. aureus, S. epididermis, K. pneumonia, S. typhi, P. aerugenosa, and B. subtilis A. brasilense. The metal complexes show higher activity against all the microorganisms than the ligand.

Soft chemical routes to semiconductor nanostructures

Soft chemistry has emerged as an important means of generating nanocrystals, nanowires and other nanostructures of semiconducting materials. We describe the synthesis of CdS and other metal chalcogenide nanocrystals by a solvothermal route. We also describe the synthesis of nanocrystals of AlN, GaN and InN by the reaction of hexamethyldisilazane with the corresponding metal chloride or metal cupferronate under solvothermal conditions. Nanowires of Se and Te have been obtained by a self-seeding solution-based method. A single source precursor based on urea complexes of metal chlorides gives rise to metal nitride nanocrystals, nanowires and nanotubes. The liquidliquid interface provides an excellent medium for preparing single-crystalline films of metal chalcogenides.

Study of gold-platinum and platinum-gold surface modification and its influence on hydrogen evolution and oxygen reduction

Surface modification of the electrodes was conducted from sulfuric acid solutions containing the corresponding metal-chloride complexes using cyclic voltammeter. Comparing the charges of the hydrogen underpotential deposition region, and the corresponding oxide reduction regions, it is concluded that a platinum overlayer on gold forms 3D islands, while gold on platinum forms 2D islands. Foreign metals present in an amount of up to one monolayer exert an influence on the change in reaction rate with respect to both hydrogen evolution (HER) and oxygen reduction (ORR) reactions. Aplatinum overlayer on a gold substrate increases the activity for HER and for ORR, compared with pure gold. These results can be understood in terms of a simple model, in which the change in the H and OH binding energies are directly proportional to the shift of the d-bond center of the overlayer. On the contrary, a gold layer on platinum slightly decreases the activity for both reactions compared with pure platinum.

Syntheses and crystal structures of cobalt and nickel complexes of 2,6-bis(hydroxymethyl)pyridine

2 : 1 (L : M) Complexes of 2,6-bis(hydroxymethyl)pyridine (dhmp) with different Co(II) salts [CoCl2·6H2O, Co(SCN)2, Co(NO3)2·6H2O, CoSO4·7H2O and Co(OTos)2·6H2O] and Ni(II) salts [NiCl2·6H2O, Ni(NO3)2·6H2O, NiSO4·7H2O and Ni(OTos)2·6H2O] have been prepared (1–9) and studied by infrared spectroscopy and X-ray crystallography. Influences on the distortion of the coordination polyhedron, the arrangement of the donor atoms and the packing structure of the complexes were investigated in terms of the different kinds of anions and cations. In the metal chloride Complexes 1 and 2, water of hydration was found, while in Complex 3 the counterion (SCN–) acts as a ligand. The crystal structures of all complexes, except 3, show N2O4 hexacoordinated metal ions; in 3 the coordination environment is N4O2. Complex 1 is another exception in containing cobalt(III) instead of cobalt(II) as for the other complexes with cobalt salts. Logically, in Complex 1, one of the dhmp ligands is mono-deprotonated. In the neutral Complexes 2 and 4–9, the basal planes of the octahedra are made up of O donors and N atoms occupy the axial positions. In 1 as well as in 3, two N and two O atoms form the base, but in 1 O, and in 3 N atoms are on the axis of the coordination sphere. Moreover, the nickel Complexes 2, 5, 7 and 9 are more symmetrical in structure than the cobalt Complexes 1, 4, 6 and 8, in accordance with the Jahn–Teller effect. Packing structures of the complexes show specific interactions based on strong and weak H-bonds that involve the counterions, hydroxy groups and aromatic units, leading to extended network structures.

The crystal and molecular structures of catena[bis(μ 2-chloro)-(μ 2-pyridazine- N,N′)]cadmium(II) and catena[bis(μ 2-chloro)-(μ 2-pyridazine- N,N′)]mercury(II) and the solid-phase 13C, 15N NMR studies of Zn(II), Cd(II), Hg(II) chloride complexes with pyridazine

The zinc triad metal chloride complexes with pyridazine of [M(pyridazine)Cl 2] n type, M=Zn(II) ( 1), Cd(II) ( 2), Hg(II) ( 3), were synthesized. The crystal and molecular structures of 2 and 3 were studied by single crystal X-ray diffraction. They are isostructural polymers of formulae catena[bis(μ 2-chloro)-(μ 2-pyridazine- N,N′)]cadmium(II) and catena[bis(μ 2-chloro)-(μ 2-pyridazine- N,N′)]mercury(II). They crystallize in the orthorhombic Imma space group ( 2: a=7.056(1), b=7.447(1), c=13.113(1) Å; 3: a=7.129(1), b=7.398(1), c=13.073(2) Å). The central atoms have the geometry of square bipyramid and are bridged by axial pyridazines and equatorial chlorides. The Cd–N and Hg–N bonds are 2.371(3) and 2.407(5) Å, the Cd–Cl and Hg–Cl being 2.6279(7) and 2.6626(12) Å, respectively. The X-ray powder diffractograms suggest 1 has a similar structure, being different from the monomeric species Zn(pyridazine) 2Cl 2 ( 4), already described by several authors as the sole product of ZnCl 2+pyridazine reaction. The 15N CPMAS-NMR measurements of 1– 3 reveal significant shielding (65–90 ppm) of nitrogen nuclei upon the formation of coordination bondings, the observed low-frequency shifts decreasing with the atomic mass of the metal.

Impedance measurements of a chalcogenide membrane iron(III)-selective electrode in contact with aqueous electrolytes

The electrochemical characterization of a chalcogenide-based iron(III)-selective electrode [Fe(III) ISE] [i.e., Fe 2.5(Se 60Ge 28Sb 12) 97.5] was achieved using impedance spectroscopy. The influence of electrolyte composition (i.e., NO 3 −, Cl −, and pH) on the membrane oxidation reaction has been examined, and a mechanism for its action is proposed. Equivalent circuit analysis was undertaken to determine the interfacial charge transfer resistance and corresponding double layer capacitance as a function of electrolyte composition and immersion time. Variations were detected in the charge transfer time constant, and this was attributed to changes in the dielectric/conduction properties of the surface layer. It was found that the Fe 2.5(Se 60Ge 28Sb 12) 97.5 oxidation kinetics depend on the pH, and the interfacial reaction is dictated by sluggish charge transfer. By contrast, chloride was shown to accelerate the rate of membrane oxidation presumably via the formation of soluble metal-chloride complexes. Electrochemical impedance spectroscopy (EIS) aging studies of the Fe 2.5(Se 60Ge 28Sb 12) 97.5 membrane in chloride electrolyte under alkaline conditions showed that the charge transfer resistance decreases with exposure time. However, extended aging revealed a change in the rate of oxidation, which was attributed to a combined diffusion/passivation effect. It is proposed that the development of a modified surface layer (MSL) and passive surface layer (PSL) are partly responsible for the electrochemical stability of the chalcogenide membrane. This paper attempts to clarify and address some of the misconceptions/issues reported previously in the literature on the chalcogenide iron(III)-selective electrode.

Bis(piperidinium)trans-dichlorobis(3,5-dinitrobenzoato)zincate(II)

Complexes of 3d transition metal chlorides with di­nitro­benzoic acids (DNBH) and secondary amines have been synthesized in order to model processes of chemisorption of organic salts by metal surfaces. A series of compounds of composition (AmH)2[MCl2(DNB)2] (where M = ZnII, CuII; AmH+ is the cation of piperidine PipH+ = C5H10NH2+ or diethyl­amine DaH+ = C4H10NH2+) have been prepared, the structure of the piperidinium salt of the Zn/3,5-DNB complex anion being authenticated by X-ray crystallography. In the title compound, (C5H12N)2[ZnCl2(C7H3N2O6)2], the Zn atom is four-coordinated. The DNB ligand behaves as a monodentate ligand via an O atom of the carboxyl­ate group, the other carboxyl­ate O atom being hydrogen bonded to one of the ammonium H atoms. The other ammonium H atom of the two cations links to the coordinated chlorides, one within the complex and the other across an inversion center, so forming a dimer.

Semi-empirical infrared spectra simulations of benzidine and its metal chloride complexes

The semi-empirical PM3 method is used to simulate the infrared spectra of the title compounds. It has been restrained that benzidine has a planar structure belonging to the symmetry point group D 2 h in the complexes. It is found that the simulated IR spectra are consistent with the proposed structures derived from the FTIR and Raman spectra. The band assignments on the basis of the three-dimensional dynamic image of the vibrations corresponding to each normal mode have also been given. Coordination effects on internal modes of benzidine, particularly on the NH 2 group vibrations are in close agreement with the observed results.

Combustion energies and standard molar enthalpies of formation for the complexes of the first-row transitional metal chlorides withL-α-histidine

Seven novel solid complexes of the first-row transitional metal withL-α-histidine were synthesized, and their compositions were determined. The constant-volume combustion energies of the complexes were measured by a precision rotation bomb calorimeter. The standard molar enthalpies of combustion and the standard molar enthalpies of formation were calculated. The results indicated that the plots of the standard enthalpies of formation against the atomic number of the metal show a regularity of zigzag.

Combustion energies and standard molar enthalpies of formation for the complexes of the first-row transitional metal chlorides with L--histidine

Combustion energies and standard molar enthalpies of formation for the complexes of the first-row transitional metal chlorides with L--histidine

Structures and properties of 6-aryl substituted tris(2-pyridylmethyl)amine transition metal complexes

A series of metal(II) complexes of [6-(2′,5′-dimethoxyphenyl)-2-pyridylmethyl]bis(2-pyridylmethyl)amine (L) have been prepared. X-Ray crystal structures have been determined for L and its metal(II) chloride complexes for Mn, Fe, Co, Ni, Cu and Zn and the results compared. The preparation and crystal structure of the unusual carbonato-bridged copper-tetramer [Cu4(L)4(CO3)2][BF4]4·5.2H2O is also described. The solution-state structures of the complexes are deduced from their physicochemical and spectroscopic properties. The Zn(II) complex, [ZnCl2(L)], shows inversion about the ligand amine group on the NMR timescale — results from a variable temperature NMR study are presented and allow estimation of the barrier to amine inversion as 56 ± 0.5 kJ mol−1. Overall, it is found that the intramolecular steric interactions introduced by substitution of the tris(2-pyridylmethyl)amine (tpa)-skeleton by a single 6-aryl group result in significant changes to the structures and properties of the resulting metal complexes: in particular the aryl-substitution in L causes (i) a weaker ligand-field compared to tpa favouring high-spin complexes, (ii) a tendency toward lower coordination numbers, and (iii) hemilability in the Ni(II) and Cu(II) complexes — the aryl-substituted leg of the ligand (L) is coordinatively labile.

Synthetic studies of hydrogen bonding in crystal structures of metal chloride complexes

Synthetic studies of hydrogen bonding in crystal structures of metal chloride complexes

Transition metal chlorides complexes with tetrahydrofuran [MtCl4(THF)2] used as precursors of ethylene polymerization catalysts

Three complexes of transition metal chlorides with tetrahydrofuran (THF), viz., [TiCl 4 (THF) 2 ] (I), [ZrCl 4 (THF) 2 ] (II), and [HfCl 4 (THF) 2 ] (III), were prepared and studied as the precursors of titanium-magnesium catalysts to be used in low-pressure polymerization (0.5 MPa, 323 K) of ethylene using AlEt 3 (most favorable), AlEt 2 Cl, or Al(i-Bu) 3 as cocatalysts. The activity of catalysts increases in the order [HfCl 4 (THF) 2 ] < [ZrCl 4 (THF) 2 ] < [TiCl 4 (THF) 2 ]. Degree of crystallinity (C), density, bulk density, M, MWD, and m.p. were determined for the resulting HDPE. Catalyst activity, found to obey the following ascending type (III) < (II) < (I), increased as the element electronegativity was raised and the partial charge on the transition metal atom in the precursor was diminished. The catalyst surface patterns visualized by a computer supported the experimental data. The uncomplexed, [MgCl 2 (THF)) 2 ]-supported tetrachlorides yielded catalysts less active than (I)-(III), but following the same general activity correlations.

Mechanism of the reaction of 1,1-dimethylhydrazine with copper(II) and palladium(II) chloride complexes containing poly-(N-2-alcoxycarbonylethyl)-ethyleneimine

The mechanism of the sorption of 1,1-dimethylhydrazine vapors with metal chloride complexes of poly-(N-2-R-oxycarbonylethyl)-ethyleneimines (R = –n-C4H9, –n-C10H21) was studied by Fourier transform IR spectroscopy (FTIR) and piezoelectric resonance. The structure of the products was determined. This allowed for the optimization of the chemical composition and structure of poly-(N-2-R-oxycarbonylethyl)-ethyleneimine-based complexes in their use as sensitive coatings of piezoelectric sensors for determining 1,1-dimethylhydrazine vapors in air.

Immobilization of metal chloride complexes of titanium, zirconium, and hafnium on a cyclopentadienyl surface of silica for ethylene polymerization

Metal chloride complexes, MCl 4(THF) 2 (M=Zr, Hf) and (Cp″)MCl 3 (M=Ti, Zr, Hf, Cp″=η 5-C 5H 5, or η 5-C 5(CH 3) 5), were immobilized on a cyclopentadienyl surface of silica with a help of n-BuLi. Before this, the silica was modified with silane coupling agent, (EtO) 3Si(CH 2) 3Cp, by applying saturating gas–solid reactions using atomic layer chemical vapor deposition (ALCVD) technique. The heterogeneous catalysts were characterized by FTIR, 13 C and 29 Si solid state NMR spectroscopies and elemental analyses. The prepared catalysts were tested in the polymerization of ethylene using methylaluminoxane (MAO) cocatalyst. Heterogeneous catalysts CpZrCl 3/S and CpHfCl 3/S (S=(EtO) 3Si(CH 2) 3Cp modified silica carrier) exhibited high activities and produced polyethylene with a narrow molar mass distribution. However, the corresponding titanium catalyst, CpTiCl 3/S, exhibited low activity in ethylene polymerization and it dimerized and oligomerized ethylene. The activities of heterogeneous MCl 4(THF) 2/S (M=Zr, Hf) and [η 5-C 5(CH 3) 5]MCl 3/S (M=Ti, Zr, Hf) catalysts were low and they all, except HfCl 4(THF) 2/S catalyst, produced polyethylene with a broad molar mass distribution. Catalyst leaching from the carrier was studied by treating the heterogeneous CpZrCl 3/S catalyst with MAO.

Fourier transform infrared and Raman spectroscopic study of 3-chloro-4-methylaniline metal(II) tetracyanonickelate and chloride complexes

The results of an infrared (IR) and Raman spectroscopic study are presented for two new di(3-chloro-4-methylaniline) metal tetracyanonickelate complexes, ML 2Ni(CN) 4 and an IR spectroscopic study are given for two new metal chloride complexes, ML 2Cl 2 (M=Cd(II) or Ni(II); L=3-chloro-4-methylaniline). The proposed structure of tetracyanonickelate complexes consists of polymeric layers of |M–Ni(CN) 4| ∞ with the 3-chloro-4-methylaniline molecules bound directly to metal (M). The effective magnetic moments of the complexes are also given.

Thermal and structural studies of amide complexes of transition metal(II) chlorides. I: Stoichiometry

A series of aliphatic amide complexes of nickel(II), cobalt(II) and copper(II) chlorides has been prepared. These complexes have the general formulae: NiL 2Cl 2·2H 2O, NiL 2Cl 2, Ni 3L 2Cl 6, Ni 3LCl 6, CoL 2Cl 2 and CuL 2Cl 2, where L is the amide ligand. Ligands ranging from formamide to butyramide, both with and without N-methyl and N-ethyl substituents, were used. The complexes were found, from the absorption spectra, to be octahedral or distorted-octahedral, except for some of the cobalt complexes with dimethyl substituted ligands which are tetrahedral. Infrared spectra confirm that coordination to the metal ion is through the carbonyl oxygen. The effects of the structure and the nature of the different amide ligands on the thermal stabilities of the complexes have been investigated by thermal analysis. As indicators of the stability of the metal–amide binding, thermal decomposition onset temperatures ( T e), peak temperatures ( T max) and enthalpies (Δ H L) were compared for complexes with similar composition, geometrical structure and decomposition stoichiometry. Results do not support the enhancement of thermal quantities with increasing basicity of the amides. Instead, steric factors appear to play a more important role in determining the magnitudes of Δ H L, T e and T max

Inorganic Geobiochemical Implications of the Oxic-Anoxic Transition in Ancient Earth Oceans

The development of free dioxygen in the Earth's atmosphere around 2.2Ga led to considerable biological changes. In particular, the early Earth biota was dominated by anaerobic prokaryotes including archaebacteria, possibly the most primitive life forms. Subsequent to the development of an oxic environment, aerobic bacteria and eventually prokaryotes developed. The inorganic biochemistry of the two groups are characterized in part by the relative dominance of nickel and cobalt proteins in the primitive anoxic group and the appearance of copper proteins in aerobic bacteria and multicellular organisms (Frausto di Silva and Williams 1996). Nickel and cobalt proteins are less important in aerobic organisms and copper is insignificant in the primitive anaerobes. Iron and zinc appear equally important throughout, although their dominant biochemical functions change. It is well established that base metal concentrations constitute limiting growth factors for present-day aerobic and anaerobic communities. For example, increasing oceanic iron concentrations enhances the growth of planktonic algae (Martin et al 1991). Iron has long been known as a limiting factor for the development of anaerobic sulphate reducing bacteria because of its importance to cytochrome c 3. (Postgate 1965). The present paper presents the results of a study of thermodynamic of oxic and anoxic ocean models based on the recent definition and discovery of a large number of base metal sulphide and polysulphide complexes (Luther et al. 1996; Chadwell et al. in prep). I assume that biological availability potentially embraces any soluble metal species and not only free metal aquo ions. The chemica l models were made using Geochemists Workbench | version 3.4 (GWB). The GWB seawater model has been discussed by Bethke (1996). The input thermodynamic database is a modified selection of the Lawrence Livermore National Labora tory thermodynamic dataset THERMO.COM.V8.R6.FULL. based on a compilation by Thomas Wolery and co-workers which is in turn largely based on Helgeson et al.(1978). The composition of early Earth oceans is not rigorously constrained and both acid and alkaline oceans have been proposed. I take a conservative view in this study, assuming that ocean composition is currently buffered by reaction with oceanic lithosphere and that this effect is likely to have been enhanced in the higher heat flow regimes of the ancient Earth. As a starting point, I therefore take the composition of the modem oxic oceans, which is fairly well defined. I then reduce it through the GWB reaction progress algorithm, basically by titrating electrons. During this process, the total major element concentration (excluding dioxygen) of the oceans remains constant. The pH remains around 8.0. In oxic oceans, inorganic base metal chemistry is dominated by free metal aquo ions, hydroxide, oxyhydroxide and chloride complexes. The database includes a number of simple base metal organic complexes, but these do not appear to affect the model and their stability constants may not be wellconstrained. In a n o x i c oceans , base metal speciation is simplified and their chemistry is largely controlled by sulphide and bisulphide complexes. The introduction of base metals (bi)sulphide complexes into the anoxic ocean model increases the relative dissolved concentrations of all base metals except Mn. The enhancement is approximately 2 magnitudes or more. This relative enhancement is independent of the sulphide mineral substrate. The total dissolved metal concentrations decrease markedly with peak concentrations around -200mV. The concentrations increase from around -300mV through -400mV. A feature of the anoxic ocean is the diminution of the free metal aquo ion concentrations. I took a computed dissolved metal concentration of 10 -15 M as being a limiting value for the presence of the metal in solution. The absolute concentrations of base metals in anoxic systems is not well constrained because of the lack of information about the nature of the metastable mineral sulphides. The increase in solubility of metastable compared with stable iron sulphides is better known. The first precipitated FeS

Preparation, characterization and thermal reactivity of N, N-dimethylformamide complexes of some transition metal chlorides

The coordination adducts of MnCl 2, FeCl 3, CoCl 2, NiCl 2 and CuCl 2 with DMF were isolated and characterized by elemental analysis, magnetic moments, UV-VIS spectroscopy, IR spectroscopy and thermal analysis techniques. The shift of the CO stretching vibration to low frequency indicated that DMF is bonded through oxygen to the metals. On the basis of spectral and elemental analysis data, the complexes have dimeric and trimeric structures achieved by the chlorine bridges. The complexes do not have melting points and undergo decomposition after dehydration. The decomposition of DMF in the complexes occurs in several stages and the last stages of decomposition always corresponds to decomposition or sublimation of the respective metal chlorides to produce the respective metal.