Hydration of the carboxylate group: Anab initio molecular orbital study of acetate-water complexes

The hydration of the carboxylate group in the acetate anion has been investigated by performingab initio molecular orbital calculations on selected conformers of complexes with the form CH₃CO₂ ^– ·nH₂O·mH₂O, wheren andm denote the number of water molecules in the first and second hydration spheres around the carboxylate group, andn + m 7. The results of RHF/6–31G^* optimizations for all the complexes and MP2/6–31+G^** optimizations for several one-water complexes are reported. The primary consequence of hydration on the structure of the acetate anion is a decrease in the length of the C-C bond. Enthalpy and free energy changes calculated at the MP2/6–31+G^** and MP2/6–311+ +G^** levels are reported for the reactions CH₃CO₂ ^– + [H₂O] _P CH₃CO₂ ^– ·nH₂O ·mH₂O where [H₂O] _P is a water cluster containingp water molecules andp=n+m 7. The calculations show that conformers with the lowest enthalpy change on complex formation are often not those with the lowest free energy change, due to a greater entropic loss in complexes with tighter and more favorable enthalpic interactions. Hydrogen bonding of six water molecules directly to the carboxylate group in CH₃CO₂ ^– is found to account for approximately 40% of the enthalpy change and 37% of the free energy change associated with bulk solvation.     

Coordination of zwitterionic 8-quinolinol (oxine) to mixed oxinate-carboxylate complexes of divalent nickel,manganese, and magnesium

Three types of metal complexes containing coordinated zwitterionic 8-Quinolinol(oxine) are isolated from the reaction ofMOx ₂ (M=divalent Ni, Mn, or Mg; HO _x =oxine) and haloacetic acidsRCO₂H (R=CF₃, CCl₃, CHCl₂, or CH₂Cl) in benzene. These types are:M(O₂CR)Ox·HOx forM=Ni,R=CCl₃, CHCl₂, and CH₂Cl and forM=Mn,R=CHCl₂.MOx(HOx) (RCO₂)MOx·nH₂O forM=Ni, Mn, or Mg,R=CF₃ andn=1,1, and 4, respectively.MO _x (HOx) (RCO₂)₂ MOx forM=Mn andR=CCl₃. These types are compared with the simple mixed chelateMn(O₂CCH₂Cl)Ox. Interrelated reactions are suggested to explain the formation of these metal complexes and the contributing factors are discussed. The coordination of the zwitterion to the metal ion through its phenolate oxygen and the presence of the triatomic system⁺N–H...O in the three types of metal complexes are evidenced by typical infrared bands. Analytical and spectral data are in accordance with the suggested formulations.

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Koordination von zwitterionischem 8-Chinolinol (Oxin) an gemischten Oxinat-Carboxylat-Komplexen des divalenten Nickel, Mangan und Magnesium

Zusammenfassung Drei Typen von Metallkomplexen mit koordiniertem zwitterionischem 8-Chinolinol (Oxin) wurden aus der Reaktion vonMOx ₂ [M=Ni(II), Mn(II), Mg(II); HOx=Oxin] mit Halogen-essigsäurenRCOOH (R=CF₃, CCl₃, CHCl₂, CH₂Cl) in Benzol isoliert. Es werden Reaktionswege zur Bildung der Komplexe diskutiert. Die Koordination des Zwitterions über den phenolischen Sauerstoff und die Präsenz der Gruppierung⁺N–H...O in allen Typen der untersuchten Metallkomplexe wird auf Grund typischer IR-Banden nachgewiesen.

     

The crystal structure of bis(1,4-dithioniumdicyclo-[2,2,2]-octane) μ-oxo-bis[tetracyanooxorhenate(V)]tetrahydrate

Summary The structure of [S(CH₂CH₂)₃S]₂[Re₂O₃(CN)₈]·4H₂O has been determined from three-dimensional x-ray diffraction data. The blue crystals are monoclinic, space group P2₁/c, with cell dimensionsa=9.431(2),b=10.879(2),c=16.217(3)Å, =110.84(2)°,Z=2 andD _m=2.11 gcm^–3. Anisotropic refinement by least-squares methods of 2483 observed reflections converged toR=0.050.The centrosymmetric binuclear anion has a linear O=Re–O–Re=O grouping with an eclipsed configuration for the cyano ligands. Bond distances: Re–O (terminal)=1.69(1), Re–O (bridging)=1.921(1) and Re–C_av=2.12(2)Å. Each Re atom is displaced by 0.11(2)Å towards the terminal oxygen atom giving a slight square-pyramidal distortion of the octahedral environment. The ring-constrained cation has C–S_av=1.82(2)Å with averaged bond angles C–S–C=101(1) and S–C–C=113(1)°.     

Reaktion von primären Alkylhydroperoxiden mit Amidoschwefelsäurechlorid: Alkyl(amidosulfonyl)peroxide

The novel peroxides H₂NSO₂OOCH₂ R (1 a:R=CH₂CH₃;1 b:R=CH₂CH₂CH₃) are obtained by reaction of sulphamoyl chloride with the appropriate hydroperoxides in the presence of pyridine (temperature below –30 °C, solvent diethyl ether). The solvent-free liquids1 deflagrate at ca. 0 °C. Hydrolysis or ammonolysis of1 generates the hydroperoxide and sulphamic acid or sulphamide, respectively. Controlled thermolysis of1 affords sulphamic acid and carbonyl compounds, i.e. propanal andn-propyl propanoate from1 a, butanal, 2-methylpropanal andn-butyln-butyrate from1 b. These products suggest a nonradical cyclic decomposition path-way.

     

Synthesis and study of binuclear vanadyl complexes with acyldihydrazones of salicylaldehyde and dicarboxylic acids

The binuclear vanadyl(ii) complexes [(VO)₂·2Py·2EtOH]·mH₂O with acyldihydrazones of salicylaldehyde (H₄L) and dicarboxylic acids were synthesized and studied. In these complexes, two chelate vanadyl(ii) complexes with the tridentate bicyclic ligands are linked to each other by the polymethylene bridges —(CH₂) _n — of different lengths varying from one to four units. The ESR spectra of solutions of these complexes, unlike those of analogous copper(ii) complexes, have an isotropic signal with an eight-line hyperfine structure (g = 1.972, a _V = 93·10^–4 cm^–1) typical of monomeric vanadyl complexes, which indicates that no exchange interactions occur between the paramagnetic centers through the polymethylene chain.     

Thermal analysis of oxathioamidate complexes

Oxathioamidates (CSNR₁ R ₂COOKR ₁=R ₂=H (A),R ₁=H andR ₂=CH₃ (B),R ₁,=R ₂=CH₃ (C)) can act as O, S donors and form pentaatomic ring systems with divalent metals (M(II)=Mn, Fe, Co, Ni, Cu, Zn). Vibrational spectra and thermal analysis provide information on the amount and nature of associated water molecules. The dehydration of MA₂(H₂O)₂ (M=Mn, Fe, Co, Ni) can be very well explained by the C.F.S.E. (crystal field stabilization energy) for weak field octahedral complexes. The complexes with ligand A and B decompose to form polymers by deprotonation on the thioamide group. The proposed structures are confirmed by the vibrational spectra. For ligand C no stable intermediates are formed during heating, degradation proceeds until metal sulphide remains.The N.F.W.O. is thanked for the financial support towards the spectroscopic and thermal equipment. The authors are very grateful to Ing. J. Janssens for the TG/DTA measurements.     

Synthesis and crystal structures of cyclopentadienyl dimolybdenum carbonyl complexes

Reactions of the fulvenes C₅H₄C(R ₁ R ₂) [(R ₁ = CH₂CH₃, R ₂ = CH₃ (1); R ₁ = R ₂ = C₂H₅ (2); R ₁, R ₂ = (CH₂)₄ (3), R ₁,R ₂ = (CH₂)₅ (4)] with Mo(CO)₆ in refluxing xylene gave the corresponding cyclopentadienyl dimolybdenum carbonyl complexes [(η⁵-C₅H₄CR₁′R₂′Mo(CO)₃]₂ [(R ₁′ = CH₂CH₃, R ₂′ = CH₃ (5); R ₁′ = R ₂′ = C₂H₅ (6); R ₁′, R ₂′ = CH(CH₂)₃ (7); R ₁′, R ₂′ = CH(CH₂)₄ (8)], which were characterized by elemental analysis, IR and ¹H NMR spectra. The molecular structures were determined by single-crystal X-ray diffraction. The results indicated the exocyclic double bond of the ligands 1 and 2 changed into a single bond and the exocyclic double bond of the ligands 3 and 4 underwent a double-bond isomerization process.     

Neutral molecule/crown ether interactions 5. Comparison of the C−H acidic interactions of nitromethane and acetonitrile with 18-crown-6 and dibenzo-18-crown-6. Crystal structures of dibenzo-18-crown-6·2 CH3NO2 and dibenzo-18-crown-6·2 CH3CN

Complete structural characterization of dibenzo-18-crown-6·2 CH₃NO₂ and dibenzo-18-crown-6·2 CH₃CN have been carried out, including location and refinement of the methyl hydrogen atoms. Dibenzo-18-crown-6·2 CH₃NO₂ is monoclinic,P2₁/c, with (at –150°C)a=9.573(2),b=14.636(2),c=33.471(7) Å, =93.77(2)°, andD _calc=1.37 g cm^–3 forZ=8. Interactions between the solvent methyl groups and the crown ethers and other solvent nitro groups associate the 1 : 2 complexes into polymeric chains alongb. The acetonitrile adduct exists as discreet 1 : 2 complexes in the solid state with C–H...O interactions exlusively to the ether. This complex is triclinic,P 1, with (at –150°C)a=9.458(6),b=9.570(5),c=14.404(5) Å, =73.18(4), =79.85(5), =66.82(6)°, andD _calc=1.28 g cm^–3 forZ=2. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82070 (22 pages).For part 4, see reference [1].     

Nitrogen-containing organosilicon compounds

Fifteen previously unknown piperidinosilanes of the type R_4–m Si[(CH₂) _n NC₅H₁₀] _m (m=1–3; n=0–3). have been synthesized by the reaction of piperidine with diethylaminotrimethylsilane, bis(diethylamino)dimethylsilane, chlorobis(dimethylamino)methylsilane, trichloro(methyl)silane, trialkyl(chloromethyl)silanes, dialkoxy(alkyl)(chloromethyl)silanes, trialkylvinylsilanes, trialkyl(3-chloropropyl)silanes, and 3-chloropropyl(diethoxy)methylsilane. The piperidinosilanes (n>0) have been converted into the corresponding hydrochlorides and methiodides.For part VIII, see [1].     

Oxidative homolysis of organochromium(III) macrocyclic complexes

Summary Organochromium complexes, [CrRL(H₂O)]²⁺] (L = 1,4,8,12-tetraazacyclopentadecane; R = 1°- or 2°-alkyl, or para-substituted benzyl), are oxidized to [CrRL(H₂O)]³⁺, which rapidly decomposes (k ₃ > 10² s^–1) by homolysis of the Cr-C bond. Rate constants of the oxidation of these complexes by [IrCl₆]^2– range from 2.20 × 10^–1 (R = Me) to 4.60 × 10⁵ (R = 4-MeC₆H₄CH₂)dm³ mol^–1 s^–1. A very negative reaction constant (–4.3) is found for the oxidation of para-substituted benzlchromium(III) complexes which, in conjunction with the results of product analysis, indicates a [Cr^III/R^.] type transition state.     

Reaktionen mit phosphororganischen Verbindungen, 17. Mitt.: Zur Oxydation von β-Oxophosphoniumrhodaniden mit Bleitetraacetat

Zusammenfassung Die Oxydation von Phosphoniumrhodaniden (C₆H₅)₃P–CH (Alkyl) CO–CHR₁R₂ SCN mitPbTA liefert in Abhängigkeit von den Resten R₁ und R₂ Verbindungen des Typs R₁R₂C=C=C (SCN) (Alkyl) und die daraus durch 1,3-Umlagerung resultierenden Senföle R₁R₂C(NCS)–CC-Alkyl. Für R₁=R₂=H und R₁=Cl, R₂=C₂H₅ entsteht fast nur die Allenverbindung. Für R₁=H und R₂=Alkyl isoliert man ein Gemisch aus Allenrhodanid und Acetylenverbindung. Wenn R₁=R₂=(–CH₂–CH₂–CH₂–) oder CH₃ darstellen, kommt es zur ausschließlichen Bildung des Acetylensenföls.Aus -Methoxyphosphoniumrhodaniden (C₆H₅)₃P–CH (OCH₃)CH–CHR₁R₂ SCN erhält man bei der Umsetzung mitPbTA R₁R₂CH–CO–CH(OCH₃) (NCS) und R₁R₂CH–CO–CH(OCH₃) (S–CO–CH₃).

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The oxidation of phosphoniumrhodanides (C₆H₅)₃P–CH (Alkyl)CO–CHR₁R₂ SCN with lead tetraacetate results in the formation of R₁R₂C=C=C=(SCN) (alkyl) type compounds, dependent on the substituents R₁ and R₂ sometimes followed by a 1,3-rearrangement to mustard oils R₁R₂C(NCS)–CC–alkyl. The case R₁=R₂=H and R₁=Cl, R₂=C₂H₅ yields almost exclusively the allenic compound. With R₁=H and R₂-alkyla mixture of allene rhodanide and the acetylenic compound is isolated. If R₁ and R₂ stand for –CH₂–CH₂CH₂– or CH₃, only the mustard oil with an acetylenic group is produced.Upon the oxidation of (C₆H₅)₃P–CH(OCH₃)CO–CHR₁R₂ SCN^– we observed formation of R₁R₂CH–CO–CH(OCH₃) (NCS) and R₁R₂CH–CO–CH(OCH₃) (S–CO–CH₃).

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Mit 5 Abbildungen

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Herrn Prof. Dr.L. Schmid zum 70. Geburtstag gewidmet.

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16. Mitt.:Elisabeth Werner undE. Zbiral, Angew. Chem.79, 899 (1967).     

Synthesis and physico-chemical studies of some polynuclear mixed carboxylate complexes of nickel(II)

A number of polynuclear mixed carboxylates of nickel(II) with the general composition [Ni(OOCCH₃)_2–n (OOCR) _n ] _x (whereR=C₁₃H₂₇, C₁₅H₃₁, C₁₇H₃₅ and C₂₁H₄₃ andn=1 or 2) have been synthesized by the transacylation reactions of anhydrous nickel acetate with higher carboxylic acids in refluxing toluene. On recrystallization from benzene-alcohol mixtures, mono-alcoholate complexes, Ni(OOCCH₃)_2–n (OOCR) _n ·ROH (whereR=CH₃ and C₂H₅) have been isolated. All these derivatives have been characterized by the molecular weight determinations, infra-red and electronic reflectance spectra and magnetic susceptibility measurements.

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Synthese und Eigenschaften einiger gemischter Carboxylat-Komplexe von Nickel(II)

Zusammenfassung Komplexe des Typs [Ni(OOCCH₃)_2–n (OOCR) _n ] _x (mitR=C₁₃H₂₇, C₁₅H₃₁, C₁₇H₃₅ und C₂₁H₄₃,n=1 oder 2) wurden aus wasserfreiem Nickelacetat mit höheren Carbonsäuren in siedendem Toluol erhalten. Bei der Kristallisation aus Benzol-Alkohol-Mischungen wurden Monoalkoholate Ni(OOCCH₃)_2–n (OOCR) _n ·ROH (mitR=CH₃ und C₂H₅) isoliert. Die Charakterisierung der Komplexe erfolgte mittels Molekulargewichtsbestimmung, Infrarot- und Elektronenspektren und der Messung der magnetischen Susceptibilität.

     

Schiff base complexes of dioxouranium(VI), III. Commun.: Dioxouranium(VI) complexes of bibasic tetradentateSchiff bases

Bibasic tetradentateSchiff bases having the donor system OH–NX–NX–OH have been shown to form UO₂(NO₃)₂(SBH₂) type of derivatives [SBH₂ is the molecule of the bibasic tetradentateSchiff bases such as HOC₆H₄C(R) N(CH₂) _n NC(R)C₆H₄OH (where R=H or CH₃ andn=2 or 3) and HOC(R)CHC(CH₃)N(CH₂) _n NC(CH₃)CH C(R)OH (where R=CH₃ or C₆H₅ andn=2 or 3)]. The 11 stoichiometry of these complexes is shown by elemental analysis and conductometric titrations. The molar conductence values in nitrobenzene indicate the non-electrolytic behaviour and the magnetic susceptibility measurements by the Gouy method show these complexes to be diamagnetic.With 1 Figure     

Synthesis of amidine complexes by metal-mediated addition of amino acid esters to coordinated nitriles

The reaction of the nitrile platinum(IV) complex trans-[PtCl₄(EtCN)₂] with amino acid esters H₂NC(R¹)(R²)CO₂Me (R¹ = R² = H, H-Me, Me-Me, H-Ph) and H₂NCH₂CH₂CO₂Me in CH₂Cl₂ produces the amidine complexes trans-[PtCl₄{ Z-NH=C(Et)NHC(R¹)(R²)CO₂Me}₂] and trans-[PtCl₄{ Z-NH=C(Et)NHCH₂CH₂CO₂Me}₂], which were isolated in 70–80% yields and characterized by elemental analysis, mass spectrometry, IR spectroscopy, and ¹H and ¹³C{¹H} NMR spectroscopy. The structures of the complexes with R¹ = R² = H (1), R¹ = H, R² = Me (2), and R¹ = H, R² = Ph (4) were established by X-ray diffraction analysis.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 601–605, March, 2005.     

New Layered Materials in the K–In–Ge–As System: K8In8Ge5As17and K5In5Ge5As14

Exploratory synthesis in the K–In–Ge–As system has yielded the unusual layered compounds K₈In₈Ge₅As₁₇(1) and K₅In₅Ge₅As₁₄(2), both of which contain In–Ge–As layers with interleaved potassium ions, Ge–Ge bonds, InAs₄tetrahedra, As–As bonds, and rows of Ge₂As₆dimers. Compound 1 has As₃groups, while compound 2 has infinite As ribbons on both faces of each layer. Unlike compound 1, compound 2 has substitutional defects where indium partially occupies each of the three independent germanium sites in the ratio of 1:5 for In:Ge. This partial occupancy makes 2 an electron-precise compound. The Ge(In)–Ge(In) bond of 2 is longer than the Ge–Ge bond of 1, and this bond lengthening effect was confirmed by performing DFT-MO calculations on the model compounds H₃Ge–GeH₃and H₃Ge–InH⁻₃. Possible implications of electron imprecise formulas determined by X-ray crystal structure determinations are discussed. Compound 1: space groupP2₁/cwitha=18.394 (8) Å,b=19.087 (7) Å,c=25.360 (3) Å,β=105.71 (2)°,V=8571 (4) ų, andD_calcd=4.45g/cm³forZ=4. Refinement on 4455 reflections yieldedR(R_w)=6.8%(7.8%). Compound 2: space groupC2/mwitha=40.00 (1) Å,b=3.925 (2) Å,c=10.299 (3),β=99.97 (2)°,V=1592 (1) ų, andD_calcd= 4.55g/cm³forZ=8. Refinement on 1206 reflections yieldedR(R_w)=5.6% (5.7%).     

Rhodium(1) carbonyl complexes with alkyl sulphoxides and sulphides

Summary Rhodium(I) carbonyl complexes, namely Rh(CO)X(R₂SO)₂ (R = Me, n-Pr or n-Bu) and Rh(CO)X(R₂S)₂ (R = Me, Et or i-Pr) and X = CI or Br, have been prepared and characterized. The compounds Rh(CO)X[P(OPh)₃]₂ X = Cl or Br, have also been isolated. In the R₂SO and R₂S complexes, the carbonyl stretching frequencies occur atca. 2020–2025 cm^–1 andca. 1950–1980 cm^–1 respectively. In the R₂SO ligand containing complexes v(S-O) occurs atca. 1100–1125 cm^–1 indicative of metal-sulphur coordination. In presence of HBF₄, the addition of an excess of Me₂SO to (OC)₂Rh(-Cl)₂Rh(CO)₂ gives [Rh(Me₂SO)₆]³⁺ in which the central metal atom undergoes spontaneous oxidation from Rh¹(d⁸) to Rh^III(d⁶). The complexes have been characterized additionally by u.v.vis. spectra, conductivity measurements and by elemental analyses.     

Rhenium(V) complexes with vinyl amides

Summary The reactions oftrans-ReOCl₃(PPh₃)₂ with vinyl amides such as RCOCH=C(R)NH₂, where R = CH₂CH₂CO₂H and R = Ph and C₆H₁₃; or R = Me, CH₂CH₂CO₂Me and R = Ph, give complexes of the type ReOCl₂-[RC(O^–)=CHC(R)=NH]PPh₃, the coordination geometry of which have been deduced from i.r. and¹H n.m.r. spectroscopic data.     

Synthesis and molecular structures of dialkylselenonium methylide complexes of indium tribromide

The reaction of bromomethyl-dibromo-indium(III), Br₂InCH₂Br with dialkylselenides, R¹SeR² (R¹ = CH₃, R² = CH₂C₆H₅; R¹ = C₂H₅, R² = CH₂C₆H₅; R¹ = R² = CH₂C₆H₅) afforded the corresponding dialkylselenonium methylide complexes of indium tribromide, Br₃InCH₂SeR¹R², which were fully characterized by NMR spectroscopy and single crystal X-ray diffraction studies.     

Free radical copolymerization of 1-vinyl naphthalene with styrene,methyl methacrylate,and acrylonitrile

Investigations on free radical copolymerization of 1-vinyl naphthalene (1-VNph, monomerM ₂) with styrene (St), methyl methacrylate (MMA) and acrylonitrile (AN) (monomersm ₁) in bulk at 60°C with AIBN as initiator are presented. Relative reactivity ratios were calculated by the Kelen-Tüdös method yielding:r _st=0.70 ±0.23 andr _1–VNph=2.02 ±0.40 for system St/1-VNph;r _MMA=0.32 ±0.10 andr _1–VNph=0.57 ±0.07 for system MMA/1-VNph andr _AN=0.11 ±0.03 andr _1–VNph=0.45 ±0.09 for system AN/1-VNph.Q, e values for 1-VNph according to Alfrey, Price scheme were calculated toQ _1–VNph=1.02,e ₁–VNph=–0.62.     

Cyclopentadienyl diruthenium metal carbonyl complexes bearing pendant thienyl ligands

Abstract  

Reactions of the thienyl side chain functionalized cyclopentadienyls (C₄H₃S)C(R₁R₂)C₅H₅[R₁, R₂ = CH₃ (1); R₁, R₂ = (CH₂)₅ (2); R₁, R₂ = C₂H₅ (3)] with Ru₃(CO)₁₂ in refluxing xylene gave the corresponding cyclopentadienyl diruthenium carbonyl complexes [(η ⁵-C₄H₃S)CR₁R₂(C₅H₄)Ru(CO)₂]₂ (R₁, R₂ = CH₃ (4); R₁, R₂ = (CH₂)₅ (5); R₁, R₂ = C₂H₅ (6)), which were characterized by elemental analysis, IR and ¹H NMR spectra. The molecular structures of 4, 5 and 6 were determined by single crystal X-ray diffraction.