Synthesis and Crystal Structure of the [Re2(CH3COO)2Cl4((CH3)2NCOCH3)2] Complex

Compound [Re₂(CH₃COO)₂Cl₄((CH₃)₂NCOCH₃)₂] is synthesized. The influence of parameters of the hydrothermal synthesis under elevated pressure on the yield of a target product and its molecular structure and physicochemical properties is studied. In the neutral complex with cis-arrangement of the bridging acetate and terminal chloride ligands with respect to the multiply bonded Re₂ ⁶⁺ complex-forming center, the Re–Re bond length is 2.2418(3) Å. Dimethylacetamide molecules are in the axial positions, the Re–O bond lengths being 2.304(3) and 2.321(4) Å. The influence of the donor ability of the axial substituents in analogous structures of the rhenium(III) binuclear clusters on the Re–Re and Re–L_ax bond lengths is analyzed.     

Radiolytic synthesis of Rh2(CO)4Cl2 and Rh6(CO)16 from RhCl3 in ethanol under CO atmosphere

Ethanolic solutions of Rh^III chloride exposed to γ-radiation under CO atmosphere are shown to be totally reduced into Rh^I complexes (Rh₂(CO)₄Cl₂ and Rh(CO)₂Cl^-₂) within a few hours with a radiolytic reduction yield of about 6.0 elementary reductions/100 eV (6.2·10^-7 mol·J^-1). The chloride ions freed in the medium inhibit further reduction through Rh(CO)₂Cl^-₂ formation. On addition of copper metal under the same conditions, Rh^III is transformed into Rh₆(CO)₁₆ with a conversion yield 50%. This cluster is formed via Rh₂(CO)₄Cl₂ although Rh(CO)₂Cl^-₂ is also present under these conditions. Rh₆(CO)₁₆ cluster is also formed under radiolysis by direct reduction of Rh₂(CO)₄Cl₂, but metallic rhodium and other reduced products are obtained at the same time.     

Zur solvensfreien Darstellung von Tetramethylammoniumsalzen: Synthese und Charakterisierung von [N(CH3)4]2[C2O4], [N(CH3)4][CO3(CH3)], [N(CH3)4][NO2], [N(CH3)4][CO2H] und [N(CH3)4][O2C(CH2)2CO2(CH3)]

Solvent-free Synthesis of Tetramethylammonium Salts: Synthesis and Characterization of [N(CH₃)₄]₂[C₂O₄], [N(CH₃)₄][CO₃CH₃], [N(CH₃)₄][NO₂], [N(CH₃)₄][CO₂H], and [N(CH₃)₄][O₂C(CH₂)₂CO₂CH₃] A general procedure to synthesize tetramethylammonium salts is presented. Several tetramethylammonium salts were prepared in a crystalline state by solvent-free reaction of trimethylamine and different methyl compounds at mild conditions: [N(CH₃)₄]₂[C₂O₄] (cubic; a = 1 114.8(3) pm), [N(CH₃)₄][CO₃CH₃] (P2₁/n; a = 813.64(3), b = 953.36(3), c = 1 131.3(4) pm, β = 90.03(1)°), [N(CH₃)₄][NO₂] (Pmmn; a = 821.2(4), b = 746.5(3), c = 551.5(2) pm), [N(CH₃)₄][CO₂H] (Pmmn; a = 792.8(7), b = 791.7(3), c = 563.3(4) pm) and [N(CH₃)₄][O₂C(CH₂)₂CO₂CH₃] (P2₁; a = 731.1(2), b = 826.4(3), c = 1 025.2(3) pm, β = 110.1(1)°). The tetramethylammonium salts were characterized by IR-spectroscopy and X-ray diffraction. The crystal structures of the methylcarbonate and the nitrite are described.     

Schwingungsspektren und Kraftkonstanten von Cl3SiP(CH3)2 und Cl3SiAs(CH3)2

Vibrational Spectra and Force Constants of Cl₃SiP(CH₃)₂ and Cl₃SiAs (CH₃)₂ The i.r. and Raman spectra of Cl₃SiP(CH₃)₂ and Cl₃SiAs (CH₃)₂ have been recorded and assigned. A normal coordinate analysis has been made using a modified valence force field. The SiP force constant is slightly higher than those of alkylsilylphosphines, whereas a similar effect is not found for the SiAs bond.     

Crystal structure of one of the strontium hydroacetates,Sr(H2O)2(CH3COO)2[H2(CH3COO)3]

All-Union Scientific-Research Institute for Chemical Reagents and Ultrapure Chemical Substances. Translated from Zhurnal Strukturnoi Khimii, Vol. 29, No. 1, pp. 104–108, January–February, 1988.     

Struktur und thermische Zersetzung von Bis(triethanolamin)kupfer(II)-acetat [Cu{N(CH2CH2OH)3}2](CH3COO)2

Structure and Thermal Decomposition of Bis(triethanolamine)copper(II) Acetate [Cu{N(CH₂CH₂OH)₃}₂](CH₃COO)₂ Bis(triethanolamine)copper(II) acetate [Cu{N · (CH₂CH₂OH)₃}₂](CH₃COO)₂ was prepared using the basic components; the structure was determined by single crystal X-ray diffraction. The complex crystallizes in the monoclinic space group P2₁/c with a = 9.101 Å, b = 13.136 Å, c = 9.819 Å, β = 111.63°. Details of the synthesis, X-ray data, and the thermal decomposition are reported.     

Mössbauer spectroscopic and X-ray diffraction study of the thermal decomposition of Fe(CH3COO)2 and FeOH(CH3COO)2

Thermal decomposition of iron(II) acetate, Fe(CH₃COO)₂, and iron(III) acetate hydroxide, FeOH(CH₃COO)₂, has been studied using⁵⁷Fe Mössbauer spectroscopy and X-ray diffraction. Samples were thermally treated in air atmosphere between 150°C and 1000°C. The formation of maghemite '-Fe₂O₃, and hematite, -Fe₂O₃, is discussed. Hematite appears as the final decomposition product.     

Thermal decomposition of the [Co(NH3)6]Cl3, Co[(NH3)4Cl2]Cl,K3[Fe(C2O4)3]3H2O and Fe(CH3COO)3 in argon and air atmosphere

Kinetic parameters (apparent activation energy, reaction order, pre-exponential factor (Z) in the Arrhenius equation) for thermal decomposition of the [Co(NH₃)₆]Cl₃, Co[(NH₃)₄Cl₂]Cl, K₃[Fe(C₂O₄)₃]3H₂O and Fe(CH₃COO)₃ are reported. They have been calculated on the DTA and TG data according to Coats-Redfern's model. Both, decomposition data obtained in argon and in air atmosphere have been considered and the results are compared.

---

Zusammenfassung Es werden die kinetischen Parameter (scheinbare Aktivierungsenergie, Reaktionsordnung, prÄexponentieller Faktor (Z) der Arrhenius-Gleichung) der thermischen Zersetzung von [Co(NH₃)₆]Cl₃, [Co(NH₃)₄Cl₂]Cl, K₃[Fe(C₂O₄)₃]3H₂O und Fe(CH₃COO)₃ beschrieben, die entsprechend dem Coats-Redfern-Modell auf der Basis der DTA- und TG-Daten errechnet wurden. Die Zersetzung wurde sowohl in Argon als auch in Luft durchgeführt und die erhaltenen Daten miteinander verglichen.

---

---

Helpful comments from Professor W. Wojciechowski and financial support from Institute for Low Temperatures and Structure Research Polish Academy of Sciences (CPBP 01.12) are greatefully acknowledged.     

Dissociative electron attachment to CH2Cl2, CHCH3Cl2, and C(CH3)2Cl2

We perform theoretical studies of dissociative electron attachment (DEA) for the compounds CH(2-n)(CH(3))(n)Cl(2), n = 0, 1, 2, by combining the finite-element discrete model with the resonance R-matrix theory. An unexpectedly low DEA cross section for CH(2)Cl(2) is likely due to the relatively large resonance width for this compound that confirms experimental observations. However, there are some quantitative discrepancies with the experimental results. Since DEA cross sections are very sensitive to the resonance width, a slight adjustment of its value can significantly improve agreement between theory and experiment. Our calculation of the thermal rate coefficients show that there are some inconsistencies between beam and swarm measurements and between different swarm measurements of the rate coefficients for DEA to CH(2)Cl(2). Further experimental and theoretical studies are warranted.     

Syntheses and structural study of trinuclear iron acetates [Fe3O(CH3COO)6(H2O)3]Cl· 6H2O and [Fe3O(CH3COO)6(H2O)3] [FeCl4]· 2CH3COOH

The structure of two trinuclear iron acetates [Fe₃O(CH₃COO)₆(H₂O)₃]Cl· 6H₂O (I) and [Fe₃O(CH₃COO)₆(H_2O)₃][FeCl₄] · 2CH₃COOH (II) was determined by X-ray diffraction analysis. Crystals I and II are ionic and belong to the orthorhombic system with parameters a = 13.704(3), b = 23.332(5), c = 9.167(2) Å, R = 0.0355, space goup P2₁2₁2 for I and a = 10.145(4), b = 15.323(6), c = 22.999(8) Å, R = 0.0752, space group Pbc2₁ for II. The complex cation [Fe₃O(CH₃COO)₆(H₂O)₃]⁺ has a μ₃-O-bridged structure typical for trinuclear iron (III) compounds. As shown by Mössbauer spectroscopy, the iron(III) ions are in the high-spin state. In trinuclear cations, antiferromagnetic exchange interaction takes place between the Fe(III) ions with the exchange parameter J = -26.69 cm^?1 for II (Heisenberg-Dirac-Van Vleck model for D_3h, symmetry).     

Darstellung und Eigenschaften von W(CH3COO)2

Synthesis and Properties of W(CH₃COO)₂. W(Ac)₂ is reported for the first time. IR- and UV-spectroscopic investigations give indications concerning the structure of the compound. The IR-spectrum shows the bridging function of the acetate group. From the UV-spectrum the presence of a W? W bond is derived. Investigations of vapourization (mass spectrometer) and the behaviour in solution are explained by a polymeric structure     

Synthese und Kristallstruktur von Praseodympropionat-trihydrat,Pr(CH3CH2COO)3(H2O)3

Synthesis and Crystal Structure of Praseodymium Propionate Trihydrate, Pr(CH₃CH₂COO)₃(H₂O)₃ Single crystals of Pr(CH₃CH₂COO)₃(H₂O)₃ were obtained by dissolving freshly prepared praseodymium hydroxide in diluted propionic acid. The crystal structure (monoclinic, P2₁/c, Z = 4, a = 1034.2(2) pm, b = 1521.2(3) pm, c = 2086.3(7) pm, β = 102.87(2)°, R1 = 0.0864, wR2 = 0.1196) consists of one-dimensional infinite chains parallel [010]. Pr1 and Pr2 are coordinated by four tridentate-bridging propionate groups. Additionally, Pr1 is coordinated by three “coordination water” molecules, Pr2 by two bidentate propionate groups. There are, in addition, three “crystal water” molecules so that praseodymium propionate trihydrate should be formulated as [(H₂O)₃Pr1(CH₃CH₂COO)₄Pr2(CH₃CH₂COO)₂] (H₂O)₃.     

Intercluster reactions show that (CH3)2S(+)CH2CO2H is a better methyl cation donor than (CH3)3N(+)CH2CO2H

The intrinsic methylating abilities of the known biological methylating zwitterionic agents, dimethylsulfonioacetate (DMSA), (CH(3))(2)S?CH(2)CO(2)(-) (1) and glycine betaine (GB), (CH(3))(3)N?CH(2)CO(2)(-) (2), have been examined via a range of gas phase experiments involving collision-induced dissociation (CID) of their proton-bound homo- and heterodimers, including those containing the amino acid arginine. The relative yields of the products of methyl cation transfer are consistent in all cases and show that protonated DMSA is a more potent methylating agent than protonated GB. Since methylation can occur at more than one site in arginine, the [M+CH(3)](+) ion of arginine, formed from the heterocluster [DMSA+Arg+H](+), was subject to an additional stage of CID. The resultant CID spectrum is virtually identical to that of an authentic sample of protonated arginine-O-methyl ester but is significantly different to that of an authentic sample of protonated N(G)-methyl arginine. This suggests that methylation has occurred within a salt bridge complex of [DMSA+Arg+H](+), in which the arginine exists in the zwitterionic form. Finally, density functional theory calculations on the model salts, (CH(3)CO(2)(-))[(CH(3))(3)S(+)] and (CH(3)CO(2)(-))[(CH(3))(4)N(+)], show that methylation of CH(3)CO(2)(-) by (CH(3))(3)S(+) is both kinetically and thermodynamically preferred over methylation by (CH(3))(4)N(+).     

Preparation,characterization, crystal and molecular structure of Na2[N(CH2COO)3 99Tc(IV) (μ-O)2 99Tc(IV)N(CH2COO)3] · 6H2O

The title compound and its potassium analog have been prepared from corresponding aqueous solutions of ⁹⁹TcO at pH ≈? 2 with SO₂ as a reducing agent. An X-ray structure determination of the Na-salt showed Tc coordinated to the tetradentate N(CH₂COO) ligand (NTA). Two Tc-NTA moieties are joined via two bridging O-atoms into a four-membered Tc₂O₂ ring. The observed diamagnetism, a strong absorption band at 19 950 cm^?1, and a short Tc-Tc distance of 2.363 Å are typical for the Tc₂O₂-fragment with its strong metal-metal interaction. The structural trans-influence at Tc and the network of H-bonds are consistent with Tc in oxidation state IV.