Die Reaktionen von Eisen(III)-chlorid mit Trithiazylchlorid. Die Kristallstruktur von [S4N4Cl]+[FeCl4]⊖

Reactions of Iron Trichloride with Trithyazyl Chloride. Crystal Structure of [S₄N₄Cl]⁺[FeCl₄]^? Iron trichloride reacts with (NSCl)₃ yielding S₄N₄[FeCl₄]₂, S₃N₃Cl₂[FeCl₄] or S₄N₄Cl[FeCl₄], depending on the reaction conditions. The i.r. spectra prove the presence of [FeCl₄]^? ions for all three compounds. The ⁵⁷Fe-Mössbauer spectra show a slight quadrupole splitting at 80 K for S₃N₃Cl₂[FeCl₄] (ΔE^Q = 0.42 mm · s^?1) and S₄N₄Cl[FeCl₄] (ΔE^Q = 0.23 mm · s^?1), which indicates a slight deformation of the FeCl₄^? tetrahedra. The crystal structure of S₄N₄Cl[FeCl₄] was determined and refined with X-ray diffraction data (2549 independent reflexions, R = 0.026). S₄N₄Cl[FeCl₄] crystallizes in the triclinic space group P1 with two formula units per unit cell. The lattice constants are a = 712, b = 911, c = 1006 pm, α = 76.5°, β = 83.8° and γ = 80.5°. The structure consists of the so far unknown [S₄N₄Cl]^⊕ cations and slightly deformed FeCl₄^? ions. The [S₄N₄Cl]^⊕ ion consists of a S₄N₄ ring built up of two nearly planar S₃N₂ fragments having a dihedral angle of 136°. The average SN bond length is 157 pm, the SCI bond length 214 pm.     

A novel group of alkaline earth metal amides: syntheses and characterization of M[N(2,6-(i)Pr(2)C(6)H(3))(SiMe(3))](2)(THF)(2) (M = Mg,Ca, Sr,Ba) and the linear,two-coordinate Mg[N(2,6-(i)Pr(2)C(6)H(3))(SiMe(3))](2)

Novel alkaline earth metal aryl-substituted silylamides were prepared using alkane (Mg) and salt elimination reactions (Mg, Ca, Sr, and Ba). The salt elimination regime involved the treatment of the alkaline earth metal iodides with 2 equiv of the respective potassium amide KNDiip(SiMe(3)), (Diip = 2,6-i-Pr(2)C(6)H(3)). The organomagnesium source for the alkane elimination was ((n)()Bu/(s)()Bu)(2)Mg. All compounds were characterized using (1)H, (13)C NMR, and IR spectroscopy, in addition to X-ray crystallography (except Mg[NDiip(SiMe(3))](2)THF(2)). Crystal data with Mo Kalpha (lambda = 0.710 73 A) are as follows: Mg[NDiip(SiMe(3))](2), 1, a = 9.4687(6) A, b = 9.6818(6) A, c = 17.9296(1) A, alpha = 96.487(1) degrees, beta = 94.537(1) degrees, gamma = 89.222(1) degrees, V = 1608.8(2) A(3), Z = 2 (two independent molecules), triclinic, space group P(-)1, R1 (all data) = 0.0508; (n)()BuMg[NDiip(SiMe(3))]THF(2), 2, a = 9.5413(1) A, b = 16.493(2) A, c = 9.8218(1) A, beta = 108.149(2) degrees, V = 1468.7(4) A(3), Z = 2, monoclinic, space group P2(1), R1(all data) = 0.1232; Ca[NDiip(SiMe(3))](2)THF(2), 4, a = 9.7074(1) A, b = 20.9466(4) A, c = 21.6242(3) A, alpha = 73.573(1) degrees, beta = 78.632(1) degrees, gamma = 89.621(1) degrees, V = 4129.1(1) A(3), Z = 4 (two independent molecules), triclinic, space group P(-)1, R1 (all data) = 0.0902; Sr[NDiip(SiMe(3))](2)THF(2), 5, a = 20.5874(5) A, b = 9.8785(2) A, c = 20.8522(5) A, beta = 102.035(2) degrees, V = 4147.6(2) A(3), Z = 4 (two independent molecules), monoclinic, space group P2/n, R1 (all data) = 0.0756; Ba[NDiip(SiMe(3))](2)THF(2), 6, a = 20.5476(2) A, b = 10.0353(2) A, c = 20.9020(4) A, beta = 101.657(1) degrees, V = 4221.0(1) A(3), Z = 4 (two independent molecules), monoclinic, space group P2/n, R1 (all data) = 0.0573.     

Mehrfachbindungen zwischen hauptgruppenelementen und übergangsmetallen: VII. Oxidative decarbonylierungsprozessein der photochemie von tricarbonyl(η5-pentamethylcyclopentadienyl)rhenium: Neue oxo—rhenium-komplexe

Short-wavelength photolysis of tricarbonyl(η⁵-pentamethylcyclopentadienyl)rhenium (1) (λ < 300 nm, quartz-glass) in tetrahydrofuran yields under partial or complete decarbonylation three novel organorhenium compounds, with the relative yields depending upon the irradiation time. Formed by exhaustive oxidative decarbonylation, the complex trioxo(η⁵-pentamethylcyclopentadienyl)rhenium(VII) (5) represents the first example of the new class of oxo half-sandwich complexes. The derivatives (μ-O)[(η⁵-C₅Me₅)Re(CO)₂]₂ (2; Me = CH₃) and (η⁵-C₅Me₅)₂Re₂(CO)₂O₂ (3; Me = CH₃) containing both oxo and carbonyl ligands are formed from 1 at shorter irradiation times. Both compounds are isolable intermediates along the mechanistically not yet fully established sequence 1 → → 5 as they are degraded to 5 under CO₂ elimination in the presence of air and/or light. The mixed oxo carbonyl complex 2 has been characterized by means of single-crystal X-ray diffraction techniques (triclinic, space group P$\text{1}$-C_i¹; a 907.4(2), b 1040.2(3), c 1414.3(4) pm; α 79.99(2), β 88.42(2), γ 66.18(2)°; R_iso = 0.068, R_aniso = 0.037, R_w = 0.031). The molecular structure centres around an isosceles Re₂O triangle whose metal centres exhibit a strongly distorted square-pyramidal geometry; the metal-metal distance recorded at 281.7(1) pm is in agreement with a single bond by the EAN rule. The centrically coordinated, planar five-membered ring ligands are parallel to each other (interplanar angle 2°) and occupy trans-positions with respect to the central Re₂O geometry.     

Tricarbonyl Complexes of Rhenium(I) with Acetylpyridine Benzoylhydrazone and Related Ligands

Novel rhenium(I) tricarbonyl complexes have been prepared by reactions of (Et₄N)₂[Re(CO)₃Br₃] with acetylpyridine benzoylhydrazone, Hapbhyd, di(2‐pyridyl)ketone benzoylhydrazone, Hpy₂bhyd, bis(2‐pyridine)ketone, py₂CO, and pyridinealdehyde terephtalaldehydebishydrazone, pytehyd. The ligands remain protonated when no supporting base is added and the following complexes have been isolated: [Re(CO)₃Br(Hapbhyd)], [Re(CO)₃Br(Hpy₂bhyd‐py, hyd)], [Re(CO)₃Br(Hpy₂bhyd‐py¹, py²)], [Re(CO)₃Br(py₂CO‐N, N)] and [Re(CO)₃Br(pytehyd)]. Addition of triethyl amine results in deprotonation of Hapbhyd and the formation of [Re(CO)₃(OH₂)(apbhyd)], whereas Hpy₂bhyd is hydrolysed and a rhenium complex with the monoanionic bis(2‐pyridyl)hydroxymethanolato ligand, {py₂C(OH)O}^‐, is formed. The same compound, [Re(CO)₃{py₂C(OH)O}], is obtained when triethyl amine and water are added to a mixture of (Et₄N)₂[Re(CO)₃Br₃] and py₂CO. The air‐stable products have been studied by spectroscopic methods and X‐ray crystallography.     

Conformational analysis3̄CXXIV: The conformation of ring A in the 4,4-dimethyl-3-androstanone system. The crystal structure of 4,4-dimethylandrostan-3-on-17β-yl benzoate

Molecular mechanics calculations indicate that the deformed chair and twisted-boat conformations are similar in energy for a 4,4-dimethyl-3-keto steroid. Earlier dipole moment work on such compounds is discussed. The crystal structure of 4,4-dimethylandrostan-3-on-17β-yl benzoate has been determined. The crystals are orthorhombic, P2₁2₁2₁, a = 17.096 (2), b = 22.136 (e), c = 6.217 (1) A. The structure was solved by direct methods and refined by least squares to R ? 0.039, R_XXX = 0.038, based on 2168 observed reflections. Ring A is shown to exist in a chair form, deformed as indicated by the calculations.     

Size and pH effect on electrical and conformational behavior of poly(acrylic acid): Simulation and experiment

Monte Carlo simulations, experimental titrations and fluorescence correlation spectroscopy experiments were used to investigate the conformational and electrical properties of polyacrylic acids (PAA). On the one hand, titration curves were calculated to get an insight into the role of pH on the degree of ionization and conformation of PAA chains. On the other hand, experimental potentiometric titrations of PAA were also achieved for different PAA molecular weights and compared to the calculated titration curves obtained by Monte Carlo coarse grained simulations. It was found that for a large range at intermediate PAA ionizations, a good correlation is obtained between experimental and simulations data thanks to the prominence of electrostatic interactions in this domain. The effect of ionic concentration and PAA molecular weight on the titration curves was also investigated. In order to get a better understanding of PAA conformational behavior, we also investigated PAA diffusion properties in aqueous solutions as a function of pH and ionic strength by fluorescence correlation spectroscopy (FCS), thanks to its high sensitivity to measure diffusion coefficients of tracer solutes. Good qualitative agreements were observed between experimental diffusivities and polymer properties calculated from MC simulations. It was shown that the high molecular weight PAA chains display more significant changes in diffusivity in agreement with the ionization degrees and conformational changes observed in the simulations.