Système ternaire : H2O–Fe(NO3)3–Co(NO3)2 isotherme : 30 °C

Ternary system: H₂O–Fe(NO₃)₃–Co(NO₃)₂ isotherm: 30 °C. The H₂O–Co(NO₃)₂ binary system has been investigated in the –28 to 50 °C temperature range. The solid–liquid equilibria of the ternary system H₂O–Fe(NO₃)₃–Co(NO₃)₂ were studied by using a synthetic method based on conductivity measurements. One isotherm is established at 30 °C, and the stable solid phases that appear are iron nitrate nonahydrate: Fe(NO₃)₃·9 H₂O, iron nitrate hexahydrate: Fe(NO₃)₃·6 H₂O, cobalt nitrate hexahydrate: Co(NO₃)₂·6 H₂O, and cobalt nitrate trihydrate: Co(NO₃)₂·3 H₂O. To cite this article: B. El Goundali et M. Kaddami, C. R. Chimie 9 (2006).     

Formal chromium–chromium triple bonds and bent rings in the binuclear cycloheptatrienylchromium carbonyls (C7H7)2Cr2(CO)n (n = 6, 5, 4, 3, 2, 1, 0): A density functional theory study

Binuclear cycloheptatrienylchromium carbonyls of the type (C₇H₇)₂Cr₂(CO)_n (n = 6, 5, 4, 3, 2, 1, 0) have been investigated by density functional theory. Energetically competitive structures with fully bonded heptahapto η⁷-C₇H₇ rings are not found for (C₇H₇)₂Cr₂(CO)_n structures having two or more carbonyl groups. This result stands in contrast to the related (C_nH_n)₂M₂(CO)_n (M = Mn, n = 6; M = Fe, n = 5; M = Co, n = 4) systems. Most of the predicted (C₇H₇)₂Cr₂(CO)_n structures have bent trihapto or pentahapto C₇H₇ rings and CrCr distances in the range 2.4–2.5 Å suggesting formal triple bonds. In some cases rearrangement of the heptagonal C₇H₇ ring to a tridentate cyclopropyldivinyl or tridentate bis(carbene)alkyl ligand is observed. In addition structures with CO insertion into the C₇H₇–Cr bond are predicted for (C₇H₇)₂Cr₂(CO)_n (n = 6, 4, 2). The global minima found for the (C₇H₇)₂Cr₂(CO)_n derivatives for n = 6, 5, and 4 are (η⁵-C₇H₇)(OC)₂CrCr(CO)₄(η¹-C₇H₇), (η³-C₇H₇)(OC)₂CrCr(CO)₃(η^2,1- C₇H₇), and (η⁵-C₇H₇)₂Cr₂(CO)₄, respectively. The global minima for (C₇H₇)₂Cr₂(CO)_n (n = 3, 2) have rearranged C₇H₇ groups. Singlet and triplet structures with heptahapto η⁷-C₇H₇ rings are found for the dimetallocenes (η⁷-C₇H₇)₂Cr₂(CO) and (η⁷-C₇H₇)₂Cr₂, with the singlet structures being of much lower energies in both cases.     

Synthesis, DNA-binding and photocleavage studies of [Ru(phen)2(pbtp)] and [Ru(bpy)2(pbtp)] (phen = 1,10-phenanthroline; bpy = 2,2′-bipyridine; pbtp = 4,5,9,11,14-pentaaza-benzo[b]triphenylene)

Based on the ligand dppz (dppz = dipyrido-[3,2-a:2′,3′-c]phenazine), a new ligand pbtp (pbtp = 4,5,9,11,14-pentaaza-benzo[b]triphenylene) and its polypyridyl ruthenium(II) complexes [Ru(phen)₂(pbtp)]²⁺ (1) (phen = 1,10-phenanthroline and [Ru(bpy)₂(pbtp)]²⁺ (2) (bpy = 2,2′-bipyridine) have been synthesized and characterized by elemental analysis, ES-MS and ¹H NMR spectroscopy. The DNA-binding of these complexes were investigated by spectroscopic methods and viscosity measurements. The experimental results indicate that both complexes 1 and 2 bind to CT-DNA in classical intercalation mode, and can enantioselectively interact with CT-DNA. It is interesting to note that the pbtp ruthenium(II) complexes, in contrast to the analogous dppz complexes, do not show fluorescent behavior when intercalated into DNA. When irradiated at 365 nm, both complexes promote the photocleavage of pBR 322 DNA.     

Synthesis and characterization of Fe2O3/SiO2 nanocomposites

Fe₂O₃/SiO₂ nanocomposites based on fumed silica A-300 (S_BET = 337 m²/g) with iron oxide deposits at different content were synthesized using Fe(III) acetylacetonate (Fe(acac)₃) dissolved in isopropyl alcohol or carbon tetrachloride for impregnation of the nanosilica powder at different amounts of Fe(acac)₃ then oxidized in air at 400–900 °C. Samples with Fe(acac)₃ adsorbed onto nanosilica and samples with Fe₂O₃/SiO₂ including 6–17 wt% of Fe₂O₃ were investigated using XRD, XPS, TG/DTA, TPD MS, FTIR, AFM, nitrogen adsorption, Mössbauer spectroscopy, and quantum chemistry methods. The structural characteristics and phase composition of Fe₂O₃ deposits depend on reaction conditions, solvent type, content of grafted iron oxide, and post-reaction treatments. The iron oxide deposits on A-300 (impregnated by the Fe(acac)₃ solution in isopropanol) treated at 500–600 °C include several phases characterized by different nanoparticle size distributions; however, in the case of impregnation of A-300 by the Fe(acac)₃ solution in carbon tetrachloride only α-Fe₂O₃ phase is formed in addition to amorphous Fe₂O₃. The Fe₂O₃/SiO₂ materials remain loose (similar to the A-300 matrix) at the bulk density of 0.12–0.15 g/cm³ and S_BET = 265–310 m²/g.     

Competitive sorption of Cu(II), Eu(III) and U(VI) ions on TiO2 in aqueous solutions—A potentiometric study

The competitive sorption of Cu(II), Eu(III) and U(VI) ions in aqueous solutions by TiO₂, has been investigated by potentiometry at I = 0.1 M NaClO₄, 25 °C and under atmospheric conditions. For Cu(II) ions the investigation was performed directly by means of a Cu²⁺ ion selective electrode, whereas for the Eu(III) and U(VI) ions indirectly based on competition reactions between the Cu(II) ion and the Eu(III) and U(VI) ions. Numerical analysis of the experimental data supports the formation of inner-sphere surface complexes and allows the evaluation of the formation constant of the (TiO)₂Cu, which is found to amount to log β* = 4.3 ± 0.4. Addition of competing Eu(III) and U(VI) ions in the aqueous system leads to replacement of the Cu(II) by the competitor metal ion. Evaluation of the potentiometric data obtained from competition experiments indicates on an ion exchange mechanism. The formation constant of the Eu(III) and U(VI) species adsorbed on TiO₂ is found to be log β* = 4.4 ± 0.7 and 4.8 ± 0.8, respectively. The relative affinity of the TiO₂ surface for the metal ions under investigation is U(VI) > Eu(III) > Cu(II).     

Kinetics of the CCl2 + Br2 and CCl2 + NO2 reactions in the temperature range 266−365 K and reactivity of the CCl2 biradical

The kinetics of the CCl₂ + Br₂ and CCl₂ + NO₂ reactions have been studied at temperatures between 266 and 365 K using laser photolysis/photoionization mass spectrometry. Dichloromethylene biradicals were produced by the pulsed laser photolysis of CCl₄. The bimolecular rate coefficients of the CCl₂ + Br₂ reaction can be described by the Arrhenius expression k₁ = (7.05 ± 1.75) × 10⁻¹² exp[(3.52 ± 0.63) kJ mol⁻¹/RT] cm³ molecule⁻¹ s⁻¹. CCl₂Br was observed as a primary product of this reaction. Interestingly, the bimolecular rate coefficients of the CCl₂ + NO₂ reaction were observed to depend weakly on the bath gas density and to possess a negative temperature dependence.     

AC conductance of (Co0.45Fe0.45Zr0.10)X(Al2O3)1 − X nanocomposites

The influence of the composition on the AC carrier transport of the composite films containing ferromagnetic CoFeZr nanoparticles in amorphous aluminium oxide matrix has been investigated. The films 3–5 μm in thicknesses and with variable composition 30 at.% < X < 60 at.% were sputtered on a single substrate from the compound target in the chamber with argon–oxygen gas mixture. TEM and SEM measurements and Mössbauer spectroscopy data have shown that all the studied films of (Co_0.45Fe_0.45Zr_0.10)_X(Al₂O₃)_1 − X with 30 at.% < X < 65 at.% have revealed the structure with crystalline granular metallic alloy (with particles of a few nanometers in size) and amorphous alumina. AC conductance measurements were performed over the frequency range 10²–10⁶ Hz at temperatures from 80 to 330 K. DC conductance measurements have been carried out for this temperature region also. The presence of two critical regions for the metallic fraction (X₁ = 33–40% and X₂ = 50–55%), where diagram “electric property–composition” exhibited pronounced peculiarities, has been confirmed. A qualitative structural model of nanocomposite was offered to explain this behavior. In accordance with the model, the first critical region at X₁ is associated with a shift of percolation threshold due to the formation of oxide layer on metallic nanoparticles, owing to the presence of oxygen in gas ambient during the sputtering process. The second critical region of the composition at X₂ is ascribed to the formation of percolation net of magnetic metallic nanoparticles in the dielectric amorphous alumina matrix.     

1-Allyl derivatives: Synthesis and crystal structures for [(NH2C5H4N(C3H5))2Cu3Cl3(NO3)2] and [C9H7N(C3H5)Cu(NO3)2]

1-Allyl-4-aminopyridinium chloride reacts with Cu(NO₃)₂ · 3H₂O in an ethanolic solution under the conditions of ac electrochemical synthesis at copper electrodes to form crystals of compound [(NH₂C₅H₄N(C₃H₅))₂Cu₃Cl₃(NO₃)₂] (I). The crystals of compound I are monoclinic: space group P2₁/c, Z = 4, a = 25.770(7), b = 7.230(4), c = 12.505(5) ?, β = 92.58(3)°, V = 2328(2) ?³. The direct interaction of 1-allylquinolinium nitrate with Cu(NO₃)₂ · 3H₂O in a methanolic solution in the presence of metallic copper yields crystals of compound [C₉H₇N(C₃H₅)Cu(NO₃)₂] (II). The crystals of compound II are triclinic: space group P , a = 6.756(3), b = 8.391(4), c = 12.489(5) ?, α = 77.18(3)°, β = 89.48(4)°, γ = 73.32(3)°, V = 662.0(5) ?³. The structure of compound I is built of infinite linear anions: polymeric fragments {(NH₂C₅H₄N(C₃H₅))₂Cu₃Cl₃(NO₃)₂} _n . Each of two copper atoms (Cu(1) and Cu(2)) π-coordinates the C=C bonds of the allyl groups of the 1-allyl-4-aminopyridinium cations, the oxygen atom of the nitrate ions, and two chlorine atoms. The third copper atom Cu(3) is linearly linked with two chlorine atoms. Particular polymeric fragments are additionally joined by the N-H…O, C-H…O, C-H…Cl hydrogen bonds. The crystal structure of compound II is built-up of the isolated L₂Cu₂(NO₃)₄ fragments (L is the 1-allylquinolinium cation). The metal atom is localized in the trigonal pyramidal coordination environment of three oxygen atoms of the nitrate ions and of the C=C bond of the allyl group of the cation. The particular L₂Cu₂(NO₃)₄ fragments are additionally joined by the C-H…O hydrogen bonds. Original Russian Text ? A.V. Pavlyuk, T. Lis, M.G. Mys’kiv, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 6, pp. 458–462.     

Antiferromagnetic complexes involving metal---metal bonds IV. Synthesis, molecular structure and magnetic properties of the heterotrinuclear cluster, (C5H5Cr)2(μ-SCMe3)(μ-S)2Fe(CO)3, with direct and indirect exchange between Cr and Fe centers

The photochemical reaction between the antiferromagnetic complex (C₅H₅-CrSCMe₃)₂S (I) (containing a Cr---Cr bond 2.689 Å long) and Fe(CO)₅ results in the elimination of two carbonyl groups and one tert-butyl radical to give (C₅H₅Cr)₂(μ²-SCMe₃)(μ³-S)₂ · Fe(CO)₃ (III). As determined by X-ray diffraction, III contains a Cr---Cr bond of almost the same length as in I (2.707 Å), together with one thiolate and two sulphide bridges. The latter are also linked with the Fe atom of the Fe(CO)₃ moiety (average Fe---S bond length 2.300 Å). Fe also forms a direct bond, 2.726 Å long, with one of the Cr atoms, whereas its distance from the other Cr atom (3.110 Å) is characteristic for non-bonded interactions. Complex III is antiferromagnetic, the exchange parameter, −2J, values for Cr---Cr, Cr(1)---Fe and Cr(2)…Fe are 380, 2600 and 170 cm⁻¹, respectively. The magnetic properties of III are discussed in terms of the “exchange channel model”. The contributions from indirect interactions through bridging ligands are shown to be insignificant compared with direct exchange involving metal---metal bonds. The effects of steric factors and of the nature of the M(CO)_n fragments on the chemical transformations of (C₅H₅CrSCMe₃)₂S · M(CO)_n are discussed.     

Synthesis, characterization and thermal properties of cobalt(II), nickel(II) and copper(II) complexes of 2,6-bis(3,4,5-trimethyl-N-pyrazolyl)pyridine): the crystal structure of [Co(btmpp)(H2O)2(NO3)]NO3

Co(II), Ni(II) and Cu(II) nitrate complexes with btmpp, namely ([Co(btmpp)(H₂O)₂(NO₃)]NO₃ (1), [Ni(btmpp)(H₂O)(NO₃)]NO₃ (2) and [Cu(btmpp)(MeOH)(NO₃)]NO₃ (3), where btmpp = 2,6-bis(3,4,5-trimethyl-N-pyrazolyl)pyridine), have been synthesized and characterized by physicochemical and spectroscopic methods. The crystal structure of complex 1 has been determined by single crystal diffraction at 100K. In all the complexes, btmpp is coordinated in a tridentate mode through its nitrogen atoms. One of the nitrates in complex 1 is terminally bonded to the metal center through the oxygen atom, whereas the other one is out of the coordination sphere. The Co(II) atom in complex 1 is hexa-coordinated with a CoN₃O₃ distorted octahedral environment. Decomposition of three complexes was analyzed thermogravimetrically. All three complexes decompose similar to explosive material.     

Temperature dependence vapour pressure measurements of Mg(tmhd)2(tmeda) [(tmhd = 2,2,6,6-tetramethyl-3,5-heptanedione, tmeda = N,N,N′,N′-tetramethylethylenediamine]

The reaction between the magnesium β-diketonate complex Mg(tmhd)₂(H₂O)₂ and 1 equiv. of N,N,N′,N′-tetramethylethylenediamine (tmeda = Me₂NCH₂CH₂NMe₂) in hexane at room temperature yielded Mg(tmhd)₂(tmeda). The standard enthalpy of sublimation (83.2 ± 2.3 kJ mol⁻¹) and entropy of sublimation (263 ± 6.3 J mol⁻¹ K⁻¹) of Mg(tmhd)₂(tmeda) were obtained from the temperature dependence vapour pressure, determined by adopting a horizontal dual arm single furnace thermogravimetric analyser as a transpiration apparatus. From the observed melting point depression DTA, the standard enthalpy of fusion (58.3 ± 5.2 kJ mol⁻¹) was evaluated, using the ideal eutectic behaviour of Mg(tmhd)₂(tmeda) as a solvent with bis(2,4-pentanedionato)magnesium(II), Mg(acac)₂ as a non-volatile solute.     

Reactions of M3Te7 (M = Mo, W) clusters with electrophilic reagents: Chalcogen exchange in the Te2 ligand and the first complexes of (TeS)

Reactions of triangular telluride-bridged Mo and W clusters [M₃(μ₃-Te)(μ₂-Te₂)₃(dtp)₃]⁺ (M = Mo, W; dtp = (EtO)₂PS₂) with S₂Cl₂ or Br₂ lead to Te/S exchange in the Te₂ ligands, with the formation of complexes with a novel TeS²⁻ ligand. Reaction of [W₃(μ₃-Te)(μ₂-Te₂)₃(dtp)₃]⁺ with Br₂ or S₂Cl₂ gives a mixture of complexes formulated as [W₃Te_4.25S_2.75(dtp)₃]⁺ and [W₃Te_4.30S_2.70(dtp)₃]⁺, respectively, on the basis of X-ray structural analysis. Reaction of the Mo homolog, namely [Mo₃(μ₃-Te)(μ₂-Te₂)₃(dtp)₃]⁺, with S₂Cl₂ gives rise to [Мо₃Te_4.74S_2.26((EtO)₂PS₂)₃]⁺. Electrospray ionization mass spectrometry (ESI-MS) complements the information gathered from X-ray analysis regarding the degree of Te by S substitution; moreover, detailed insights on the regioselectivity of such replacement are also obtained from ESI-MS analysis. These experimental evidences indicate that Te by S replacement in W complexes display high regioselectivity (as evidenced by the exclusive formation of a W₃Te₄S₃⁴⁺ core), the equatorial Te ligands being preferentially replaced over the Te_ax and μ₃-Te ligands. Conversely, for the Mo homologs, a broad distribution of Mo₃Te_7−xS_x⁴⁺ cluster species ranging from x = 0 to 6 is observed. Bond distance analysis as well as crystal packing trends as a function of the cluster core M₃Te_7−xS_x⁴⁺ (M = Mo, W; x = 0–6) composition are also reported.     

[As(V)As(III)O6]: An uncommon anion group in the crystal structure of K2Cu3(As2O6)2

The crystal structure of K₂Cu₃(As₂O₆)₂ was determined from single-crystal X-ray data by a direct method strategy and Fourier summations [a = 10.359(4) Å, B = 5.388(2)Å, C = 11.234(4) Å, β = 110.48(2)°; space group C2/m; Z = 2; R_w = 0.025 for 1199 reflections up to sin /λ = 0.81 Å⁻¹]. In detail, the structure consists of As(V)O₄ tetrahedra and As(III)O₃ pyramids linked by a common O corner atom to [As(V)As(III)O₆]⁴⁻ groups with symmetry m. The bridging bonds As(V)---O [1.749(3) Å] and As(III)---O [1.838(2) Å] are definitely longer than the other As(V)---O bonds [mean 1.669 Å] and As(III)---O bonds [1.764(2) Å, 2×]. The angle As(V)---O---As(III) is 123.0(1)°. The Cu atoms are [4 + 2]- and [4 + 1]-, and the K atom is [9]-coordinated to oxygen atoms. The As₂O₆ groups and the Cu coordination polyhedra are linked to sheets parallel to (001). These sheets are connected by the K atoms. Single crystals of K₂Cu₃(As₂O₆)₂ suitable for X-ray work were synthesized under hydrothermal conditions.     

Energetics of copper diphosphates – Cu2P2O7 and Cu3(P2O6OH)2

Differential scanning calorimetry and high temperature oxide melt solution calorimetry are used to study enthalpy of phase transition and enthalpies of formation of Cu₂P₂O₇ and Cu₃(P₂O₆OH)₂. α-Cu₂P₂O₇ is reversibly transformed to β-Cu₂P₂O₇ at 338–363 K with an enthalpy of phase transition of 0.15 ± 0.03 kJ mol⁻¹. Enthalpies of formation from oxides of α-Cu₂P₂O₇ and Cu₃(P₂O₆OH)₂ are −279.0 ± 1.4 kJ mol⁻¹ and −538.8 ± 2.7 kJ mol⁻¹, and their standard enthalpies of formation (enthalpy of formation from elements) are −2096.1 ± 4.3 kJ mol⁻¹ and −4302.7 ± 6.7 kJ mol⁻¹, respectively. The presence of hydrogen in diphosphate groups changes the geometry of Cu(II) and decreases acid–base interaction between oxide components in Cu₃(P₂O₆OH)₂, thus decreasing its thermodynamic stability.     

Theoretical study of [Hg3(o-C6F4)3]n · {benzene} (n = 1, 2) complexes

The electronic structure and spectroscopic properties of [Hg₃(o-C₆F₄)₃]_n · {benzene} (n = 1, 2) were studied at the HF, MP2 and PBE levels. The interaction between [Hg₃(o-C₆F₄)₃] and benzene at the HF and MP2 levels was analyzed. Secondary π-interactions (Hg–benzene) were found to be the main contribution short-range stability in the [Hg₃(o-C₆F₄)₃] · {benzene} complex. At the MP2 and PBE levels equilibrium Hg–C distances of 338.4 and 361.4 pm; and interaction energies of 46.6 and 29.2 kJ/mol were found, respectively. The absorption spectra of these complexes were calculated by the single excitation time-dependent method at PBE level.     

Theoretical study of the stereodynamics of the reactions O(D) + H2, D2 and HD

Calculations of the dynamics of the reactions O(¹D) + H₂ → OH + H, O(¹D) + HD → OH + D, O(¹D) + HD → OD + H and O(¹D) + D₂ → OD + D have been performed using the quasi-classical trajectory (QCT) method with symplectic integration. The theoretical calculations were carried out on the ground state 1A′ potential energy surfaces (PES) by Dobbyn and Knowles. The distributions of the dihedral angle P(_r), the angle between k and j′, P(θ_r), and the product vibrational state are presented. The results show that the intermediate geometrical structures and lifetimes of the reactive collisions play a vital role in these reactions.     

Olefin epoxidation catalyzed by [Ru(TDL)(tmeda)H2O] complexes (TDL = tridentate Schiff-base ligand; tmeda = tetramethylethylenediamine)

Mixed-chelate complexes of ruthenium have been synthesized using tridentate Schiff-base ligands (TDLs) derived from condensation of 2-aminophenol or 2-aminobenzoic acid with aldehydes (salicyldehyde, 2-pyridinecarboxaldehyde), and tmeda (tetramethylethylenediamine). [Ru^III(hpsd)(tmeda)(H₂O)]⁺ (1), [Ru^III(hppc)(tmeda)(H₂O)]²⁺ (2), [Ru^III(cpsd)(tmeda)(H₂O)]⁺ (3) and [Ru^III(cppc)(tmeda)(H₂O)]²⁺ (4) complexes (where hpsd²⁻ = N-(hydroxyphenyl)salicylaldiminato); hppc⁻ = N-(2-hydroxyphenylpyridine-2-carboxaldiminato); cpsd²⁻ = (N-(2-carboxyphenyl)salicylaldiminato); cppc⁻ = N-2-carboxyphenylpyridine-2-carboxaldiminato) were characterized by microanalysis, spectral (IR and UV–vis), conductance, magnetic moment and electrochemical studies. Complexes 1–4 catalyzed the epoxidation of cyclohexene, styrene, 4-chlorostyrene, 4-methylstyrene, 4-methoxystyrene, 4-nitrostyrene, cis- and trans-stilbenes effectively at ambient temperature using tert-butylhydroperoxide (t-BuOOH) as terminal oxidant. On the basis of Hammett correlation (log k_rel vs. σ⁺) and product analysis, a mechanism involving intermediacy of a [Ru–O–OBu^t] radicaloid species is proposed for the catalytic epoxidation process.     

Coordination of niobium and tantalum oxides by Ar, Xe and O2: Matrix isolation infrared spectroscopic and theoretical study of NbO2(Ng)2 (Ng = Ar, Xe) and MO4(X) (M = Nb, Ta; X = Ar, Xe, O2) in solid argon

The combination of matrix isolation infrared spectroscopic and quantum chemical calculation results indicate that the NbO₂ molecule is coordinated by two noble gas atoms in forming the NbO₂(Ng)₂ (Ng = Ar, Xe) complexes in solid noble gas matrixes. In contrast, the TaO₂ molecule is not able to form similar noble gas complex. The niobium and tantalum dioxides further react with dioxygen to form the side-on bonded superoxo-dioxide complexes MO₄ (M = Nb, Ta), which are coordinated by one argon atom in solid argon matrix. The coordinated Ar atom in MO₄(Ar) can be replaced by O₂ or Xe in forming the MO₆ and MO₄(Xe) complexes. The results indicate that the NbO₂, NbO₄ and TaO₄ molecules trapped in solid noble gas matrixes should be regarded as the NbO₂(Ng)₂ and MO₄(Ng) (Ng = Ar, Xe; M = Nb, Ta) complexes instead of “isolated” metal oxide species.     

Rhodium(I) carbonyl complexes of chalcogen functionalized tripodal phosphines, [CH3C(CH2P(X)Ph2)3] {X = O, S, Se} and their reactivity

The reaction of dimeric rhodium precursor [Rh(CO)₂Cl]₂ with two molar equivalent of 1,1,1-tris(diphenylphosphinomethyl)ethane trichalcogenide ligands, [CH₃C(CH₂P(X)Ph₂)₃](L), where X = O(a), S(b) and Se(c) affords the complexes of the type [Rh(CO)₂Cl(L)] (1a–1c). The complexes 1a–1c have been characterized by elemental analyses, mass spectrometry, IR and NMR (¹H, ³¹P and ¹³C) spectroscopy and the ligands a–c are structurally determined by single crystal X-ray diffraction. 1a–1c undergo oxidative addition (OA) reactions with different electrophiles such as CH₃I, C₂H₅I and C₆H₅CH₂Cl to give Rh(III) complexes of the types [Rh(CO)(COR)ClXL] {R = –CH₃ (2a–2c), –C₂H₅ (3a–3c); X = I and R = –CH₂C₆H₅ (4a–4c); X = Cl}. Kinetic data for the reaction of a–c with CH₃I indicate a first-order reaction. The catalytic activity of 1a–1c for the carbonylation of methanol to acetic acid and its ester is evaluated and a higher turn over number (TON = 1564–1723) is obtained compared to that of the well-known commercial species [Rh(CO)₂I₂]⁻ (TON = 1000) under the reaction conditions: temperature 130 ± 2 °C, pressure 30 ± 2 bar and time 1 h.     

Ferromagnetic exchange coupling in phosphonato-bridged dinuclear copper(II) compound with monoethyl (pyridyn-2-ylmethyl)phosphonate ligand (2-mpmpe): Cu2(2-mpmpe)2(H2O)2(NO3)2

The interaction of diethyl (pyridyn-2-ylmethyl)phosphonate (2-pmpe) with Cu(NO₃)₂ · 6H₂O leads to a partial hydrolysis of the starting ligand and formation of the compound of the formula Cu₂(2-mpmpe)₂(H₂O)₂(NO₃)₂, where 2-mpmpe = monoethyl (pyridyn-2-ylmethyl)phosphonate. The crystal and molecular structure of a copper(II) compound was determined by single X-ray diffraction method. Its structure consists of five-coordinated in distorted square planar geometry (CuNO₄ chromophore) copper(II) ions doubly bridged by OPO from phosphonate. The Cu?Cu distance is 4.69 Å. The crystal packing is determined by the interdinuclear hydrogen bond system, which leads to a three-dimensional (3D) H-bonds network. The compound was characterized by infrared, ligand field, EPR spectroscopy, and magnetic studies. The magnetic properties of the title compound investigated over the 1.8–300 K, revealed the occurrence of a weak ferromagnetic coupling through phosphonate bridge (J = 1.86 cm⁻¹) and interdimer superexchange coupling through H-bond network (zJ′ = −0.17 cm⁻¹). Spectroscopic and magnetic properties are presented in the light of crystal structure.