Metallosilicates as supports of Co catalysts for the synthesis of liquid hydrocarbons from CO and H2

The effect of the nature of the silicate support on the activity and selectivity of 10%. Co/M silicate catalysts (where M=Cu, Zn, Ce, Ti, Hf, La, Al, Zr, Co, Mg) in the synthesis of hydrocarbons from CO and H₂ has been established. Co and Zr catalysts have been shown to provide the highest catalytic efficiency. The yield of liquid hydrocarbons in their presence exceeds 120 g m^–3.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 480–482, March, 1993.     

The migratory insertion of carbon monoxide and methyl isocyanide into zirconium–carbon and titanium–carbon bonds anchored to a calix[4]arene moiety: a dynamical density functional study

The energetics and reaction mechanism of the migratory insertion of carbon monoxide and methyl isocyanide into the zirconium–carbon and titanium–carbon bonds in [calix[4](OMe)₂(O)₂–M–Me₂], (M=Zr, Ti), have been investigated by combining static and dynamic density functional calculations. Two steps have been characterized: the coordination of the incoming nucleophilic moiety leading to relatively stable facial adducts; its subsequent insertion into the M–C bond, leading to ²-bound acyl or iminoacyl complexes, providing a rationale for the different behavior of CO and MeNC towards both insertion and deinsertion reactions. Our results indicate that the rate-determining step for the overall MeNC insertion into the M–C bond is its coordination to the electron-deficient metal center, with the titanium system featuring a higher energy barrier (12.7 versus 5.5 kcal mol^–1). Ab initio molecular dynamics simulations have been performed on the Zr system by means of the Car–Parrinello method, to study the hitherto inaccessible mechanistic features of the insertion reactions.Contribution to the Björn Roos Honorary Issue     

Kinetics and mechanism of metal ion catalysis. Part III. Osmium(VIII) catalysed oxidation of m-hydroxybenzaldehyde by Fe(CN)6 3− in alkaline medium

Os^VIII-catalysed oxidation of m-hydroxybenzaldehyde by alkaline Fe(CN)₆ ^3– has been studied in the 0.01–0.05 M [OH^–] range. Higher [OH^–] concentrations were not possible as the substrate turned yellow at [OH^–] > 0.05 M. The very low solubility of the substrate in H₂O restricted the kinetic study to [OH^–] < 0.01 M. A mechanism, consistent with the results is proposed.     

Dinuclear complexes with a μ-cyano ligand. Part XI(1). Synthesis and characterization of several derivatives ofcis-[Co(NH3)(en)2(H2O)]3+

Summary The new complex double saltscw-[Co(NH₃)(en)₂(H₂O)]₂ [M(CN)₄]₃ (en = ethylenediamine; M = Ni, Pd or Pt),cis-[Co(NH₃(en)₂(H₂O)]₂[FeNO(CN)₅]₃ andcis-[Co(NH₃)(en)₂(H₂O)][Co(CN)₆] have been synthesized and by anation in the solid state the corresponding new dinuclear complexes with a cyano bridgecis- ortrans-[(NH₃)(en)₂Co-NC-M(CN)₃]₂ [M(CN)₄] (M = Ni, Pd or Pt);cis-, trans-[(NH₃)(en)₂Co-NC-FeNO(CN)₄]₂[FeNO(CN)₅] andcis-[(NH₃)(en)₂Co-NC-Co(CN)₅ have been prepared. The complexes have been characterized by chemical analysis, t.g. measurements, and by i.r. and electronic spectroscopy. With [Ni(CN)₄][^2– and [Co(CN)in]₆ ^3– only thecis-isomer is produced; with [Pd(CN)₄]^2–, [Pt(CN)₄]^2– and [FeNO(CN)₅]^2– thetrans- isomer is the dominant species. The dinuclear complex derived from [Pt(CN)₄]^2– shows strong Pt-Pt interactions both in the solid state and in solution.     

Synthesis and some properties of furylacrylates of aluminium(III) and titanium(IV)

Summary Compounds of the type [M(OPrⁱ)_m–n(FA)_n] (where m = 3 and n = 1 to 3 when M = Al; and m = 4 and n = 1 to 4 when M = Ti) have been synthesised by the reactions of aluminium and titanium isopropoxides with furylacrylic acid (HFA) in benzene. The corresponding tertiary butoxide derivatives, [M(OBu^t)_m–n(FA)_n], were also obtained by the alcohol-interchange technique. These compounds have been characterised by elemental analysis, and i.r. and p.m.r. spectra.     

Hydrogenation of schiff bases with group 6 metal carbonyls and sodium methoxide as catalyst precursors

Summary Schiff bases are hydrogenated to secondary amines by H₂ in the presence of [M(CO)₆](M=Cr, Mo or W) and NaOMe in methanol solution at 60–160 °C andca. 100 bar H₂ pressure. The reaction is significantly slower in the absence of NaOMe. In a stoichiometric reaction, [HCr(CO)₅]^– hydrogenatesN- benzylidene-aniline at 75 °C toN-benzylaniline forming [Cr₂(CO)₁₀]^2–.     

Syntheses,crystal structures and magnetic properties of two cyano-bridged two-dimensional assemblies [Fe(salpn)]2 [Fe(CN)5NO] and [Fe(salpn)]2[Ni(CN)4]

Two cyano-bridged assemblies, [Fe^III(salpn)]₂[Fe^II(CN)₅NO] (1) and [Fe^III (salpn)]₂[Ni^II(CN)₄] (2) [salpn = N, N-1,2-propylenebis(salicylideneiminato)dianion], have been prepared and structurally and magnetically characterized. In each complex, [Fe(CN)₅NO]^2– or [Ni(CN)₄]^2– coordinates with four [Fe(salpn)]⁺ cations using four co-planar CN^– ligands, whereas each [Fe(salpn)]⁺ links two [Fe(CN)₅NO]^2– or [Ni(CN)₄]^2– ions in the trans form, which results in a two-dimensional (2D) network consisting of pillow-like octanuclear [—M^II—CN—Fe^III—NC—]₄ units (M = Fe or Ni). In complex (1), the NO group of [Fe(CN)₅NO]^2– remains monodentate and the bond angle of Fe^II—N—O is 180.0°. The variable temperature magnetic susceptibilities, measured in the 5–300 K range, show weak intralayer antiferromagnetic interactions in both complexes with the intramolecular iron(III)iron(III) exchange integrals of –0.017 cm^–1 for (1) and –0.020 cm^–1 for (2), respectively.     

The infrared spectra (600-140 cm−1 of the imidazole,pyrazine and pyrimidine adducts of cobalt(II), nickel(II) and zinc(II) acetylacetonates

Summary The complexes M(acac)₂(imidazole)₂ (M = Co or NO and [M(acac)₂B]_n (M = Co, Ni or Zn; B = pyrazine or pyrimidine) have been prepared and their i.r. spectra determined over the 600–140 cm^–1. range. The metal-oxygen and metal-nitrogen stretching frequencies, (M-O) and v(M-N), are assigned on the basis of the band shifts induced by deuteriation of the adducted base and by substitution of the metal ion. Three or fourv(M-O) bands are observed within the 600-200 cm^–1 range. The twov(M-O) bands of higher frequency are considered to the coupled with internal ligand modes. TwovM-N) bands are observed within the 280–170 cm^–1. range. The metal-ligand stretching frequencies are in good agreement with the values previously established for these vibrations in the [M(imidazole)₆]²⁺ and Ni(acac)₂(pyridine)₂ complexes.     

Studies on transition-metal nitrido and oxo complexes. Part VII(1). Substituted nitrido complexes of osmium and ruthenium

Summary Addition reactions of [MNCl₄]^– (M = Os or Ru) with ligands L or L to give [MNCl₄ · L]^– or [(MNCl₄)₂L]^2– (L = pyridine, pyridine-N-oxide,iso-quinoline or DMSO; L = hexamethylenetetramine, pyrazine or dioxan) are described. With NCO^–, [OsNCl₅]^– gives [OsN(NCO)₅]^2– but NCS^– gives a thionitrosyl complex, [Os(NS)(NCS)₅]^2–. Reactions of OsNCl₃(AsPh₃)₂ with pyridine, 1,10-phenanthroline and tertiary phosphites and phosphinites have been studied, as have reactions of triphenylphosphine with OsOCl₄ andtrans- [MO₂Cl₄]^2– (M = Os or Ru). The nitrido-iodo complexes [OsNI₄]^– and OsNI₃, (SbPh₃)₂ are also reported.     

Electrochemical synthesis and magnetic studies of neutral transition metal imidazolates and pyrazolates

Summary The single-step electrochemical synthesis of neutral transition metal complexes of imidazole, pyrazole and their derivatives has been achieved at ambient temperature. The metal was oxidized in an Me₂CO solution of the diazole to yield complexes of the general formula: [M(Iz)₂] (where M = Co, Ni, Cu, Zn; Iz = imidazolate); [M(MeIz)₂] (where M = Co, Ni, Cu, Zn; MeIz = 4-methylimidazolate); [M(PrⁱIz)₂] (where M = Co, Ni, Cu, Zn; PrⁱIz = 2-isopropylimidazolate); [M(pyIz)_n] (where M = Co^III, Cu^II, Zn^II; pyIz = 2-(2-pyridyl)imidazolate); [M(Pz)_n] (where M = Co^III, Ni^II, Cu^II, Zn^II; Pz = pyrazolate); [M(ClPz)_n] and [M(IPz)_n] (where M = Co^III, Ni^II, Cu^II, Zn^II; ClPz = 4-chloropyrazolate; IPz = 4-iodopyrazolate); [M(Me₂Pz)_n] (where M = Co^II, Cu^I, Zn^II; Me₂Pz = 3,5-dimethylpyrazolate) and [M(BrMe₂Pz)_n] (where M = Co^II, Ni^II, Cu^I, Zn^II; BrMe₂Pz = 3,5-dimethyl-4-bromopyrazolate). Vibrational spectra verified the presence of the anionic diazole and electronic spectra confirmed the stereochemistry about the metal centre. Variable temperature (360-90 K) magnetic measurements of the cobalt and copper chelates revealed strong antiferromagnetic interaction between the metal ions in the lattice. Data for the copper complexes were fitted to a Heisenberg (S= ) model for an infinite one-dimensional linear chain, yielding best fit values of J=–62––65cm^–1 andg = 2.02–2.18. Data for the cobalt complexes were fitted to an Ising (S= ) model with J=–4.62––11.7cm^–1 andg = 2.06–2.49.     

Electrospray Mass Spectrometry of Aqueous Solutions of Isopolyoxotungstates

Electrospray mass spectrometry (ESMS) has been conducted on aqueous solutions of isopolyoxotungstate systems. There is direct evidence that the desorption process in the ESMS technique has resulted in significant chemical effects, resulting in the detection of many new anions and cations. For the ammonium polyoxotungstate system, negative-ion ESMS yields ions of the form [HW _m O_3m+1]^–, [W _m O_3m+1]^2–, and [HW _m O_3m+2]^3– (with the latter being better formulated as [H₂W_2m O_6m+4]^6–). For the alkali metal polyoxotungstate systems ions of the form [W _m O_3m+1A]^– and [W _m O_4m A_2m–2]^2– (where A=Li⁺, Na⁺, K⁺) were observed. For positive-ion ESMS two series were observed, namely, the [W _m O_4m A_2m+1]⁺ and [W _m O_4m A_2m+2]²⁺ ions. In the ammonium polyoxotungstate system, aggregates of both the [HW _m O_3m+1]^– and the [W _m O_3m+1]^2– series can be classified as open-chained structures of tetrahedra that are corner shared, whereas the more highly charged anions [H₂W_2m O_6m+4]^6– are consistent with closed-packed structures which are based on the structure of paratungstate-B [H₂W₁₂O₄₂]^10–. For the alkali metal tungstate systems, the ESMS spectra are consistent with open-chained structures of octahedral units that are edge shared, with a terminating tetrahedral unit. Linear correlations suggest that the assembly of these aggregates occurs via an additive polymerization mechanism for which the additive moieties (WO₃, WO²⁺ ₂, and W₂O₈A₄) in aqueous solution can be identified.     

Composition and structure of zirconium complexes in tributyl phosphate extracts of Zr from concentrated nitric acid solutions

Using quantitative difference IR spectroscopy we have found that the tibutyl phosphate & acts of zirconium from 12–15 M HN03 contain ionic associates [(TBP)₂H⁺]Zr(NO₃)₅ ^– (I) and [TBP· H₃0⁺ (H₂0)_n]Zr(N0₃)₅ ^– (II), where n = 1, 2, as well as the Zr(N0₃)₄(TBP)₂ complex at a lower concentration than (I) and (I.). The equilibrium I II is shifted toward II at higher C_{HNo 3} ⁰ and lower c_Zr ⁰. The structure of associates I and II is discussed.Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, D. I. Mendeleev Moscow Chemical Technological Institute. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 5, pp. 80–89, September–October, 1993.Translated by L. Smolina     

Synthesis,crystal structures and physical properties of two terephthalate-bridged copper(II) and nickel(II) complexes

Two ₂-terephthalate (tp) bridged complexes, [Cu₂(tp)(pren)₄](ClO₄)₂ (pren = 1,3-diaminopropane) (1) and [Ni₂(tp)(pren)₄(Him)₂](ClO₄)₂ (Him = imidazole) (2), have been synthesized and characterized by X-ray single-crystal structural analysis. In the discrete dinuclear [Cu₂(tp)(pren)₄]²⁺ cation of complex (1), each Cu^II atom has a square-pyramidal geometry, being coordinated by four nitrogen atoms (avg. 2.031 Å) from two pren ligands at the basal plane and one oxygen atom [2.259(3) Å] from a bis-monodentate tp group at the axial position. In the discrete dinuclear [Ni₂(tp)(pren)₄(Him)₂]²⁺ cation of complex (2), each Ni^II center is coordinated by five nitrogen atoms [Ni—N 2.069(3)–2.109(2) Å] from one Him group and two pren groups, and completed by one oxygen atom [Ni—O 2.138(3) Å] from a bis-monodentate tp group to furnish a distorted octahedron. Magnetic susceptibility studies show that the pair of metal atoms, although being separated by >11.5 Å, exhibit weak intramolecular antiferromagnetic interactions in complexes (1) (g = 2.07 and J = –3.4 cm^–1) and (2) (g = 2.10 and J = –0.7 cm^–1). The electrochemical behaviors of the complexes have also been studied by cyclic voltammogram processes.     

Free Energy Relationships for the Outer-Sphere Anion–Anion and Anion–Cation Optical Electron Transitions Involving Common Cyanometalate (II) and (IV) Donors: Evidence for the Frequency-Distorted Reorganization Dynamics

This work is an extension of the research project on the outer-sphere optical charge transfer (CT) initiated by Prof. R.R. Dogonadze at the Laboratory founded by him in Tbilisi, Georgia. We report the band deconvolution procedures and accomplished free energy relationships for recently observed novel outer-sphere anion–anion and anion–cation optical electron transitions involving common cyanometalate II and IV ions, viz. [M(CN) _x ]^4–, M = Fe, Ru, Os (x = 6) and M = Mo, W (n = 8) as electron donors, and [Fe^III(CN)₆]^3– and [Ru^III(NH₃)₆]³⁺ as electron acceptors, respectively. The CT band maximum vs. the redox asymmetry free energy relationships, constructed through the consideration of spin-orbit splitting effects, exhibit linear character with slopes close to unity as predicted theoretically, and fully confirm the assignment of these transitions to outer-sphere optical electron transitions as outlined in the preceding works. The preliminary comparative analysis of presented relationships based on the contemporary charge transfer theory and recent differential DO-D stretching overtone data strongly suggests the essential redox asymmetry for the reorganization free energy increments attributed to first solvating shells of cyanometalate ions involved.     

Synthesis of Silver Complexes in DMSO–HX and DMSO–HX–Ketone Systems

Comparative analysis of the oxidizing and complexing properties of the DMSO–HX (X = Cl, Br, I) and DMSO–HX–ketone (X = Br, I; the ketone is acetone, acetylacetone, or acetophenone) systems toward silver was performed. The reaction products are AgX (X = Cl, Br, I), [Me₃S⁺]Ag _n X^– _m (n= 1, 2; m= 2, 3; X = Br, I) and [Me₂S⁺CH₂COR]AgX^– ₂(R = Me, Ph; X = Br, I). The composition of the obtained complexes depends on both the DMSO : HX ratio and the nature of HX, as well as on the methods used to isolate solid products from the solution. It was noted that the formation of the [Me₂S⁺CH₂COMe]AgBr^– ₂complex in the Ag⁰–DMSO–HBr–acetylacetone system occurs with cleavage of the acetylacetone C–C bond and follows a specific reaction course. The optimum conditions for production of the silver compounds in the title systems are determined.     

Study of the equilibrium of formation of arsenic(iii) lacunar heteropolytungstates by Raman spectroscopy

The formation of lacunar heteropolyanions (HPA): [AsW₉O₃₃]^9–, [As₂W₁₉O₆₇(H₂O)]^14–, and [As₂W₂₀O₆₈(H₂O)]^10– in aqueous solutions was investigated by Raman spectroscopy at [Na₂HAsO₃]₀ = 0.1, [Na₂WO₄]₀ = 0.9 mol L^–1 and pH 9.4–1.6. The [AsW₉O₃₃]^9– HPA is characterized by the most intense band ns (W=O) at 948 cm^–1 retaining its position in the pH range from 8.9 to 7.5. Under these conditions, the equilibrium constant of [AsW₉O₃₃]^9– formation from H₂AsO₃ ^– and WO₄ ^2– ions was estimated (logK = 87.0±1.0). The asymmetrical band at 952 cm^–1 corresponding to H_x[As₂W₁₉O₆₇(H₂O)]^(14–x)– shifts to 960 cm^–1 as the pH decreases from 6.5 to 5.5, which is due to the change in HPA protonation. The [As₂W₂₀O₆₈(H₂O)]^10– HPA is formed at pH 3.1—1.6; it is characterized by a band at 972 cm^–1.     

Telluro- and seleno-bridged TiIV-MII (M = Ni,Pd, Pt) heterobimetallic complexes

Summary Heterobimetallic complexes of the types [Cp₂Ti(-EAr)₂-M(dppe)] (ClO₄)₂ [(1)–(4); M, E = Ni, Te (1); Ni, Se (2); Pt, Te (3); Pt, Se (4); Ar = Ph (a), C₆H₄-4-Me (b), C₆H₄-4-OMe (c), C₆H₄-4-OEt (d)] and [Cp₂Ti(-TeAr)₂-MCl ₂] [M = Pd (5), Pt (6)] were obtained by the reactions of Cp₂Ti(EAr)₂ with M(dppe)(ClO₄)₂ and M(PhCN)₂Cl₂, respectively. While (1), (5) and (6) are stable in the solid state as well as in solution, (2)–(4) undergo dissociation to M(dppe)(EAr)₂ and Cp₂Ti(ClO₄)₂ in solution, as shown by multinuclear (³¹P{¹H},¹⁹⁵Pt{¹H}, ¹²⁵Te{¹H}) n.m.r. studies. The reaction of Cp₂Ti(SeAr)₂ with M(PhCN)₂Cl₂, however, leads to the formation of Cp₂TiCl₂ and a polymeric material [M(SeAr)₂] _n .     

Photochemical reactions of molybdenum and tungsten octacyanometallates(IV) in acidic aqueous media containing 2,2′-bipyridyl or 1,10-phenanthroline

Summary The reaction scheme of acidic photolysis of [M(CN)₈]^4– (M = Mo or W) in the presence of 2,2-bipyridyl (bipy) or 1,10-phenanthroline (phen) based on previous reports, and the present results, is given. In this scheme the formation of [M(CN)₆(N-N)]^2– (M = Mo or W), postulated in the literature to be a main product of photoexcitation of [M(CN)₈]^4– in the presence of bipy or phen, has definitively been excluded. The main cyano-polypyridyl species formed are [MO(CN)₃(N-N)]^– ions which, in acidic solution, undergo further reactions. A new product, [MoO(CN)₂(N-N)₂], resulting from thermal replacement of the cyanide ligand by polypyridyl, has been detected.Author to whom all correspondence should be directed.     

Metallocene–methylaluminoxane catalysts for olefin polymerizations. IV. Active site determinations and limitation of the 14CO radiolabeling technique

The initial active site concentrations, [C^*]₀, have been determined with CH₃OT radiolabeling for the Cp₂ZrCl₂/MAO and CpZrCl₃/MAO catalysts (Cp = η⁵ : cyclopentadienyl, MAO = methyl aluminoxane). Almost all the Zr are found to be catalytically active in 70°C ethylene polymerizations; [C^*]₀ = [Zr] and [C^*]₀ = 0.8[Zr] at Al/Zr ratios of 10⁴ and 10³, respectively. Lowering the temperature to 50°C and Al/Zr to 5.5 × 10² reduces [C^*]₀ to 0.2[Zr]. The rate constant of propagation at 70°C was calculated to be 1.6 × 10³(M s)^?1 for both catalysts at Al/Zr = 1.1 × 10⁴; the values are decreased fivefold and tenfold, respectively, for the CpZrCl₃ and Cp₂ZrCl₂ systems. The usage of ¹⁴CO to determine the propagating Zr–P species was investigated. With regard to the time of reaction of ¹⁴CO with the polymerization mixture, the initial phase is attributed to reversible CO complexation and reversible migratory insertion. The second slower phase may be due to the formation of enediolate. During the course of a batch polymerization the ¹⁴C radioactivity incorporated is small compared to the number of active sites found by CH₃OT determination; it is only ca. 10% of [C^*]₀ at maximum rate of polymerization. Therefore, ¹⁴CO radiolabeling cannot be used to count C^*.     

Syntheses and Molecular Structures of [(thf)4Li] [{(thf)Li}M(C4H8)3] (M = Zr,Hf) and Their Solution Behavior

The reaction of MCl₄(thf)₂ (M = Zr, Hf) with 1,4-dilitiobutane in diethyl ether at –25 °C or at 0 °C with a molar ratio of 1 : 3 yields the homoleptic “ate” complexes [(thf)₄Li] [{(thf)Li}M(C₄H₈)₃] 1 - Zr (M = Zr) and 1 - Hf (M = Hf). The crystalline compounds form ion lattices with solvent-separated [(thf)₄Li]⁺ cations and [{(thf)Li}M(C₄H₈)₃]^– anions. The NMR spectra at –20 °C show magnetic equivalence of the M–CH₂ and of the β-CH₂ groups of the butane-1,4-diide ligands on the NMR time scale. Analogous reactions of MCl₄(thf)₂ with 1,4-dilithiobutane with a molar ratio of 1 : 2 proceed unclear. However, single crystals of [Li(thf)₄] [HfCl₅(thf)] ( 2 ) can be isolated with the hafnium atom in a distorted octahedral coordination sphere of five chloro and one thf ligand. NMR spectra allow to elucidate the time-dependent degradation of 1-Hf and 1-Zr in THF and toluene at 25 °C via THF cleavage. Addition of tmeda to a solution of 1-Zr allows the isolation of intermediately formed [{(tmeda)Li}₂Zr(nBu)₂(C₄H₈)₂] ( 3 ).