PREPARATION AND CHARACTERIZATION OF CLUSTERS CONTAINING THE CoMRuS (M=Mo OR W) CORE

Abstract

The reaction of (μ₃-S)RuCo₂(CO)₉ with functionally substituted cyclopentadienyl tricarbonyl metal anions M(CO)₃(C₅H₄C(O)R) (M = Mo, W; R = OEt, CH₂CH₂COOMe) in THF under reflux gave new chiral skeleton clusters (μ₃-S)RuCoM(CO)₈(C₅H₄C(O)R) [M = Mo, R = OEt (1); M = W, R = OEt (2); M = Mo, R = CH₂CH₂COOMe (3); M = W, R = CH₂CH₂COOMe (4)]. These complexes were characterized by elemental analysis, IR and ¹H NMR spectra. The molecular structure of compound (1) was determined by single-crystal X-ray diffraction methods.     

SYNTHESIS AND SOLID-STATE NMR STRUCTURAL CHARACTERIZATION OF POLYSILOXANE-IMMOBILIZED THIOL-AMINE METAL(II) COMPLEXES

Abstract

The polysiloxane-immobilized thiol, amine, and thiol-mine ligand systems P-(CH₂)₃X (where P represents the siloxane network, X[dbnd]SH,NH₂, or hybride of amine and thiol ligand groups) have been made via the sol-gel process by hydrolytic condensation of Si(OEt)₄ and (MeO)₃Si(CH₂)₃X. The immobilized polysiloxanes thiol-acetate P-(CH₂)₃SCH₂COOMe and glycinate P-(CH₂)₃NHCH₂COOMe have been prepared by the reaction of the corresponding polysiloxane system P-(CH₂)₃SH, or P-(CH₂)₃NH₃ with methylchloroacetate. The immobilized thiol-amine ligands form metal(II) complexes when treated with aqueous metal(II) ion solutions (M[dbnd]Ni²⁺, Cu²⁺, Cd²⁺. Hg²⁺). High-resolution solid state NMR studies have been used to characterize these immobilized ligand systems and their metal(II) treated samples. ²⁹Si CP-NMR spectra suggest that these ligand systems undergo some leaching(1–4%) of small oligomers when treated with aqueous acid and metal ion solutions. ¹⁵N CP-NMR results show that substantial proportion of amine groups is coordinated to metal ions.     

Mass spectra of aliphatic dicarboxylic acids and their dimethyl esters: Cyclic structures for the [M − H2O]+˙ ions from the diacids and [M − MeOH]+˙ ions from the dimethyl esters

Methyl 2-oxocycIoalkane carboxylate structures are proposed lor the [M ? MeOH]^+˙ ions from dimethyl adipate, pimelate, suberate and azelate. This proposal is based on a comparison of the metastable ion mass spectra and the kinetic energy releases for the major fragmentation reaction of these species with the same data for the molecular ions of authentic cyclic β-keto esters. The mass spectra of α,α,α′,α′-d₄-pimelic acid and its dimethyl ester indicate that the α-hydrogens are involved only to a minor extent in the formation of [M ? ROH]^+˙ and [M ? 2ROH]^+˙ ions, while these α-hydrogens are involved almost exclusively in the loss of ROH from the [M ? RO˙]⁺ ions (R = H or CH₃). The molecules XCO(CH₂)₇COOMe (X = OH, Cl) form abundant ions in their mass spectra with the same structure as the [M ? 2MeOH]^+˙ ions from dimethyl azelate.     

The preparation and properties of dicarbonyl-h5-cyclopentadienyliron h2-vinyl ether and h2-ketene acetal complexes

Metallation of >-haloacetals wth sodium dicarbonyl-h⁵-cyclopentadienyl- ferrate (Fp^-) provides a convenient point of departure for the synthesis of alhyde -iron complexes (FpCHRCHO) and of h²-vinyl alcohol and vinyl ether cations [Fp(CH₂=CHOR)]⁺. These latter complexes are shown to be best described as distorted dihapto cation. Treatment of FpCOCH₂OMe with strong acid leads to the ketene hemiacetal cation [Fp(CH₂=C(OH)OMe)]⁺ rather than to the expected ketene complex. This substance, as well as the acetal cation [Fp(CH₂=C(OMe)OEt)]⁺ prepared by alkylation of FpCH₂COOMe, may possess the structure of an h¹-metal complex incorporating a carboxonium ion. A correlation is shown to exist between the chemical shift of cyclopentadienyl protons and the average infrared carbonyl stretching frequency in a variety of Fp(olefin)⁺ FpR complexes.     

Structural determination of glucosylceramides isolated from marine sponge by fast atom bombardment collision‐induced dissociation linked scan at constant B/E

Five glucosylceramides (GlcCers) were isolated by reversed phase high‐performance liquid chromatography from the MeOH extracts of a marine sponge, Haliclona (Reniera) sp., collected from the coast of Ulleung Island, Korea, and analyzed by fast atom bombardment mass spectrometry (FAB–MS) in positive‐ion mode. FAB‐mass spectra of these compounds included protonated molecules [M + H]⁺ and abundant sodiated molecules [M + Na]⁺ from a mixture of m‐NBA and NaI. The structures of these GlcCers, which were similar, were elucidated by FAB‐linked scan at constant B/E. To find diagnostic ions for their characterization, the GlcCers were analyzed by collision‐induced dissociation (CID) linked scan at constant B/E. The CID‐linked scan at constant B/E of [M + H]⁺ and [M + Na]⁺ precursor ions resulted in the formation of numerous characteristic product ions via a series of dissociative processes. The product ions formed by charge‐remote fragmentation provided important information for the characterization of the fatty N‐acyl chain moiety and the sphingoid base, commonly referred to as the long‐chain base. The product ions at m/z 203 and 502 were diagnostic for the presence of a sodiated sugar ring and β‐D ‐glucosylsphinganine, respectively. For further confirmation of the structure of the fatty N‐acyl chain moiety in each GlcCer, fatty acid methyl esters were obtained from the five GlcCers by methanolysis and analyzed by FAB–MS in positive‐ion mode. On the basis of these dissociation patterns, the structures of the five GlcCers from marine sponge were elucidated. In addition, the accurate mass measurement was performed to obtain the elemental composition of the GlcCers isolated from marine sponge. Copyright © 2009 John Wiley & Sons, Ltd.     

Mass spectra of some (Z)-α-Phenyl-β-(2-thienyl)acrylonitriles

The mass spectra of some (Z)α-(4-R′-phenyl)-β-(2-thienyl-5-R)acrylonitriles (R = H, CH₃, Br; R′ = H, CH₃O, CH₃, Cl, NO₂) at 70 eV are reported. Mass spectra exhibit pronounced molecular ions. The compound's where R = H, and CH₃ are characterized by the occurrence of a strong [M - H]⁺ peak. Moreover, in all the compounds a m/z 177 peak occurs. In the compounds where R = H, [M - HS]* and [M - CHS]* ions are present except the nitroderivatives. Where R = CH₃, [M - HS]⁺ ion occurs.     

Gallium alkoxides: Synthesis and properties

Compounds Ga(OR)₃ (R = Me, Et, Prⁱ, Buⁿ, C₂H₄OMe) were synthesized by exchange reactions between gallium chloride and alkali metal alkoxides, the reetherefication of Ga(OPrⁱ)₃ and Ga(OC₂H₄OMe)₃ by other ROH (R = Me, Et), and anodic dissolution of metallic gallium in the presence of a electroconductive additive (LiCl, Bu₄NBr). When solid GaCl₃ is introduced into an alcoholic solution of NaOEt, stable soluble gallium oxoalkoxyhalides are formed. The same reaction with a GaCl₃ solution in toluene or electrochemical synthesis produces nonvolatile Ga(OEt)₃ samples, which have the polymer zigzag configuration [Ga(OR)_4/2(OR)]_∞. Mass spectrometry shows that only Ga(OPrⁱ)₃ and freshly prepared X-ray amorphous Ga(OEt)₃ samples (produced by reetherefication) are transferred to the gas phase. The spectra of the latter contain ions generated by penta-and hexanuclear oxoalkoxide molecules, along with fragments of orthospecies [Ga(OEt)₃]_2?4. IR spectra are described for all compounds synthesized.     

N,N-Bis[ethoxy(methyl)silylmethyl]methylamines MeN[CH2SiMem(OEt)3-m]2 (m = 0-2). Synthesis and Reactions with Phenol

Previously unknown N,N-bis[ethoxy(methyl)silylmethyl]amines MeN[CH₂SiMe_m(OEt)_3-m ]2 (m = 0-2) were synthesized. According to UV spectral data, only MeN[CH₂SiMe₂(OEt)]₂ form hydrogen bond with phenol in a heptane solution. The amines with m = 0 and 1 fail to forms hydrogen bond with phenol [under the same conditions, N-(triethoxysilylmethyl)dimethylamine Me₂NCH₂Si(OEt)₃ forms a strong hydrogen bond with phenol]. All the amines (m = 0-2) enter transetherification with phenol to give compounds of the general formula MeN[CH₂SiMe_m m(OPh) _n (OEt)3-m-n]₂ (m = 0-2, n = 1-3). Refluxing of N,N-bis[ethoxy(methyl) silylmethyl]amines with excess phenol results in cleavage of the Si-C bond by phenol, providing phenoxysilanes Me_mmSi(OPh)4-m (m = 0-2) and trimethylamine.     

A MALDI mass spectrometry investigation of the compositions of the products of the partial acidolysis of MeSi(OMe)3

The molecular-mass compositions of the products of partial acidohydrolytic polycondensation that are formed during the interaction of MeSi(OMe)₃ with CH₃COOH have been studied via MALDI mass spectrometry. It has been shown that, depending on the molar ratio of MeSi(OMe)₃ and CH₃COOH (m/n), a wide range of oligomethylmethoxysiloxanes with the average composition [MeSiO _n/m (OMe)_{(3 ? 2n/m)}] _p are formed. The analysis of molecular masses and ²⁹Si NMR spectra of the products has revealed various types of molecular structures, which change from linear, branched, and cyclic to polycyclic clusters with condensed cycles after a change in the degree of polycondensation α = 100 × [2n/3m] from 66.67 to 83.33%. At a degree of polycondensation of α = 86.67% or higher, the polycyclic clusters form a spatially crosslinked structure (gel).     

Rate constants for addition of the OP·(OPri)2, Me3C·, and Me(CH2)3 ·CH2 radicals to methano[60]fullerenes C60CX1X2 (X1 = X2 = CO2Et; X1 = CO2Me,X2 = OP(OMe)2; X1 = X2 = OP(OEt)2)

The rate constants for the addition of the OP^·(OPrⁱ)₂, Me₃C^·, and Me(CH₂)₃ ^·CH₂ radicals to the methano[60]fullerenes C₆₀CX¹X² (X¹ = X² = CO₂Et; X¹ = CO₂Me, X² = OP(OMe)2; X¹ = X² = OP(OEt)₂) were determined by ESR spectroscopy. Methanofullerenes are more reactive toward these radicals than C₆₀ fullerene.     

Ion-molecule reactions observed for nitroaromatic compounds in negative ion fast atom bombardment mass spectrometry

Analyses of a series of nitroaromatic compounds using fast atom bombardment (FAB) mass spectrometry are discussed. An interesting ion-molecule reaction leading to [M + O ? H]^? ions is observed in the negative ion FAB spectra. Evidence from linked-scan and collision-induced dissociation spectra proved that [M + O ? H]^? ions are produced by the following reaction: M + NO₂^? → [M + NO₂]^? → [M + O ? H]^?. These experiments also showed that M^?˙ ions are produced in part by the exchange of an electron between M and NO₂^? species. All samples showed M^?˙, [M ? H]^? or both ions in their negative ion FAB spectra. Not all analytes studied showed either [M + H]⁺ and/or M⁺˙ in the positive ion FAB spectra. No M⁺˙ ions were observed for ions having ionization energies above ～9 eV.     

Mass spectra of organometallic compounds—XIII: Metal carbonyl complexes of tris(dimethylamino)arsine

The mass spectra of the tris(dimethylamino)arsine metal carbonyl complexes [(CH₃)₂N]₃-AsM(CO)₅ (M = Cr, Mo and W), trans-[(CH₃)₂N]₃AsCr(CO)₄As[N(CH₃)₂]₃ and [(CH₃)₂N]₃-AsFe(CO)₄ were examined and compared with those of the corresponding tris(dimethylamino)-phosphine complexes. The molecular ions in the mass spectra of the tris(dimethylamino)arsine complexes have a greater tendency to eliminate a (CH₃)₂N fragment than the molecular ions in the mass spectra of the corresponding tris(dimethylamino)phosphine complexes. The mass spectrum of the tungsten derivative [(CH₃)₂N]₃AsW(CO)₅ exhibits not only the usual series of ions [(CH₃)₂N]₃-AsW(CO)n+ and [(CH₃)₂N]₂AsW(CO)n[+ but also the series of ions (CH₃)₂NAsW(CO)n]+ (n = 5, 4, 3, 2, 1 and 0) and even the nitrogen-free ions [AsW(CO)_n]+ (n = 2, 1 and 0). Metastable ion evidence was obtained for arsine (AsH₃) elimination from the [(CH₃)₂N]₂AsFeH⁺ ion in the mass spectrum of [(CH₃)₂N]₃AsFe(CO)₄.     

Novel organosilicon monomer for preparing transparent matrices doped with lanthanide complexes

Perfluoroadipic bis(trialkoxysilylpropyl)amide was synthesized as a mixture of five compounds with the general formula (EtO) _n (MeO)_3-n Si(CH₂)₃NHC(O)(CF₂)₄C(O)NH(CH₂)₃-Si(OMe) _n (OEt)_3-n (1, n = 1, 2). Hydrolysis of this product by a specified amount of water (1: 4) gave oligomers EtO[(HO)(EtO)Si(CH₂)₃NH(O)C(CF₂)₄C(O)NH(CH₂)₃Si(OEt)₂O]_nH ( _n = 7–9). From oligomer solutions, transparent glassy thermally stable films were obtained. The film material was studied by IR spectroscopy, atomic force microscopy, transmission electron microscopy, and powder X-ray diffraction. Compound 1 and oligomers can efficiently solvate lanthanide diketonate complexes. They displace water from the metal coordination sphere, and this water is then spent for hydrolysis of trialkoxysilyl groups. The luminescence intensity of matrix films based on the oligomers depends on the concentration of lanthanide complexes and is very low at 7n_exc = 330 nm, whereas the luminescence intensity of the Eu³⁺ cation is very high.     

Ruthenium-Catalyzed Cross-Metathesis of Trisubstituted Vinylsilanes with Light Alkenes

In the cross-metathesis reaction of tri(methyl, ethoxy)vinylsilanes with propene and/or 1-butene catalyzed by RuCl₂(PPh₃)₃ activated in benzene at 115–130 °C, a series of l-alkenylsilanes of general formula CH₃(CH₂)_mCH = CHSiMe_3−n(OEt)_n, where m=0, 1, and n=0–3 (1-silyl-1-alkenes), as well as of formula CH₂=C(Me)SiMe_3−n(OEt)_n, where n=1, 2 (2-silyl-1-alkenes), were obtained. Additional products determined were allysilanes of general formula CH₂=CHCH₂SiMe_3−n(OEt)_n and CH₃CH= CHCH₂SiMe_3−n(OEt)_n, where n=1–3. © 1997 John Wiley & Sons, Ltd.     

Formation and stability of gaseous tolyl ions

Collisional activation mass spectra confirm that tolyl ions can be produced from a variety of CH₃C₆H₄Y compounds. High purity o-, m- and p-tolyl ions are prepared by chemical ionization of the corresponding fluorides (Y=F) as proposed by Harrison. In electron ionization of CH₃C₆H₄Y formation of the more stable tropylium and benzyl ionic isomers usually accompanies that of the o-, m- and p-tolyl ions. Isomerization of low energy [CH₃C₆H₄Y]⁺? to [Y–methylenecyclohexadiene]⁺? is proposed to account for most [benzyl]⁺ formation, while the tropylium ion appears to arise from the isomerization of tolyl ions formed with higher internal energies, [o-, m-, p-tolyl]⁺→ [benzyl]⁺→ [tropylium]⁺, consistent with Dewar's predictions from MINDO/3 calculations.     

Novel D- and T-functionalized Polysiloxane Matrices for Reactions in Interphases

New hydrocarbon bridged co-condensation agents of the type RSi(OMe)₂(CH₂)_zC₆H₄(CH₂)_z(OMe)₂SiR { 3[Ph(1,4-C₃D⁰)₂] , z = 3, R = Me; 3[Ph(1,4-C₃T⁰)₂] , z = 3, R = OMe; 4[Ph(1,4-C₃D⁰)₂] , z = 4, R = Me} were synthesized by hydrosilylation of the corresponding α,ω-dienes CH₂=CH–(CH₂)_z–2–C₆H₄–(CH₂)_z–2–CH=CH₂ [z = 3 ( 1 ), 4 ( 2 )] with HSiR(OMe)₂ (R = Me, OMe). These silane monomers were sol-gel processed, partially with MeSi(OMe)₃ ( T ⁰) to give the polysiloxanes 3 a , 3 b , 4 c , 3 d , 3 e , 4 f , and 3 ab (Table 1, Schemes 2 and 3); D = D type silicon atom (two oxygen neighbors), T = T type of silicon atom (three oxygen neighbors). The relative amounts of T and D silyl species and the degrees of condensation were determined by ²⁹Si and ¹³C CP/MAS NMR spectroscopic investigations. ²⁹Si and ¹³C CP/MAS NMR relaxation time studies (T_SiH, T_CH, T_1ρH), and 2 D WISE NMR experiments were applied to get knowledge about the polymer dynamics. For the first time protons of such polysiloxane systems were detected by ¹H SPE/MAS NMR measurements in suspension. Mobility studies were carried out in different solvents. Furthermore the swelling capacities of the polymers 3 a , 3 b , and 4 c in different solvents and the BET surface areas of all materials were investigated. SEM micrographs show the morphology of 3 a and 3 b .     

Easily available niobium(V) mixed chloro‐alkoxide complexes as catalytic precursors for ethylene polymerization

The dinuclear [NbCl_n(OR)_(5‐n)]₂ (n = 4, R = Et, 1 ; n = 4, R = CH₂Ph, 2 ; n = 3, R = Et, 3 ; n = 2, R = Et, 4 ; n = 2, R = , 5 ), and [Nb(OEt)₅]₂, 6 , and the mononuclear niobium compounds NbCl₄[κ²? OCH₂CH(R′)OR] (R = Me, R′ = H, 7 ; R = Et, R′ = H, 8 ; R = CH₂Cl, R′ = H, 9 ; R = CH₂CH₂OMe, R′ = H, 10 ; R = R′ = Me, 11 ), NbBr₄[κ²? OCH₂CH₂OMe], 12 , and NbCl₃(κ²? OCH₂CH₂OMe)(κ¹? OCH₂CH₂OMe), 13 , were tested in ethylene polymerization. Optimized reaction conditions included the use of D‐MAO as co‐catalyst and chlorobenzene as solvent at 50 °C. Complex 7 , whose X‐Ray structure is described here for the first time, exhibited the highest activity ever reported for a niobium catalyst in alkene polymerization [151 kg_polymer × mol_Nb^?1 × h^?1 × bar^?1]. Compounds 1 , 3‐5 , 8 , 13 showed activities similar to that of 7 . Linear polyethylenes (characterized by FT‐IR, NMR, GPC, and DSC analyses) with a broad polydispersivity were obtained. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis,crystal structures,and biological activity of oxovanadium(V) complexes with similar tridentate hydrazone ligands

Two new oxovanadium(V) complexes, [VOL¹(OEt)(EtOH)] (1) and [VOL²(OMe)(MeOH)] (2), were prepared by reaction of [VO(acac)₂] (where acac?=?acetylacetonate) with N′-(3-bromo-2-hydroxybenzylidene)-4-methylbenzohydrazide (H₂L¹) in ethanol and N′-(3-bromo-2-hydroxybenzylidene)-4-methoxybenzohydrazide (H₂L²) in methanol, respectively. Crystal and molecular structures of the complexes were determined by elemental analysis, infrared spectra, and single-crystal X-ray diffraction. The V ions have octahedral coordination. Thermal stability and the inhibition of urease of the complexes were studied.     

Matrix effects on the fast atom bombardment mass spectra of palladium complexes

In an attempt to identify and characterize the intermediates involved in multi-step palladium catalyzed coupling reactions, under fast atom bombardment (FAB) conditions, the selection of a matrix to enhance ion formation without degrading the palladium complex is critical. In general, it is observed that the analysis of tetrakis(triphenylphosphine)palladiurn(0) using glycerol, m-nitrobenzyl alcohol or o-nitrophenyl octyl ether as the FAB matrix compound produces several ions which correspond to complexes of the type Pd_xL_yO_z⁺ (L = PPh₃; x = 1-4; y = 1-4; z = 0-2), in addition to clusters containing one or more matrix molecules. FAB mass spectra generated using triethanolamine- or tetramethylene sulfone (sulfolane) are observed to contain ions related to the palladium(0) complex with little or no interference from ions related to the oxidation or reduction processes.     

Structural studies of polyhydroxybis(tetrahydrofuran)acetogenins from Annona squamosa using the combination of chemical derivatization and precursor-ion scanning mass spectrometry

The structure of squamocin polyhydroxybis(tetrahydrofuran)acetogenin from Annona squamosa L., was characterized by a combination of the chemical derivatization and precursor-ion scanning mass spectrometry. The lactone part of squamocin was modified with N,N-dimethylethylenediamine in the vapour phase to afford a strong positive charge at one end of the skeleton. The derivative was ionized by fast atom bombardment (FAB), and the product ion spectrum from [M + H]⁺ and the precursor ion spectrum from the m/z 72 ion [CH₂?CHN⁺H(CH₃)₂] generated by low-energy collision were acquired. The structure of the derivative could be characterized by the precursor-ion spetrum from the m/z 72 ion, but little structural information could be obtained from the production spectrum from [M + H]⁺ of the derivative. By the attachment of a tertiary amino group to one end of the skeleton, charge-remote fragmentation was facilitated and abundant and unique fragment ions were observed in the precursor-ion spectrum. Structural characterization of six other isolated compounds was also carried out, and two novel compounds were found by this technique. A similar derivatization was applied in the peptide leu-enkephalin, and full sequencing from the C-terminus using precursor-ion scanning from m/z 72 could be achieved.