Aminosubstituierte 2-azoniaallenyliden-komplexe des chroms und wolframs

The successive reaction of chromium and tungsten hexacarbonyl, (CO)₆M (M = Cr, W), with [N=C(Ph)R]⁻ and [Et₃O]BF₄ yields the alkylideneamino(ethoxy)carbene complexes (CO)₅M[C(OEt)N=C(Ph)R] (M = Cr (1), W (2); R = NMe₂ (a), ^tBu (b)). Ethoxide abstraction from 1 and 2 affords 2-azoniaallenylidene complexes, {(CO)₅M[CNC(Ph)R]}⁺BF₄⁻ (3/4). The complexes 3 and 4 are best described as resonance hybrids of several limiting structures. On the basis of the spectroscopic data of the complexes 3a and 4a the limiting structure of an iminium-substituted isocyanide complex dominates.     

Snthesis and x-ray structure of an isomeric cyclophosphazene complex containing antimony(III)

The monosilylated acyclic phosphazene ligand Me₃SiNP(NMe₂)₂NP(NMe₂)₂ NH₂ (3) has been synthesized and characterized. The reaction of 3 with antimony triacetate, Sb(OOCMe₃), in refluxing toluene forms a cyclic phosphazene derivative, [N{P(NMe₂)₂NH}₂Sb(OOCMe)₂ (4), which is characterized by elemental analyses, mass, IR and NMR spectroscopy and single-crystal X-ray structural analysis. Complex 4 crystallizes in the form of a cis and trans isomeric chain in the solid state.     

Synthesis and structure of ansa-cyclopentadienyl pyrrolyl titanium complexes: [(η-C5H4)CH2(2-C4H3N)]Ti(NMe2)2 and [1,3-{CH2(2-C4H3N)}2(η-C5H3)]Ti(NMe2)

Reaction of ansa-cyclopentadienyl pyrrolyl ligand (C₅H₅)CH₂(2-C₄H₃NH) (2) with Ti(NMe₂)₄ affords bis(dimethylamido)titanium complex [(η⁵-C₅H₄)CH₂(2-C₄H₃N)]Ti(NMe₂)₂ (3) via amine elimination. A cyclopentadiene ligand with two pendant pyrrolyl arms, a mixture of 1,3- and 1,4-{CH₂(2-C₄H₃NH)}₂C₅H₄ (4), undergoes an analogous reaction with Ti(NMe₂)₄ to give [1,3-{CH₂(2-C₄H₃N)}₂(η⁵-C₅H₃)]Ti(NMe₂) (5). Molecular structures of 3 and 5 have been determined by single crystal X-ray diffraction studies.     

Structural study of Mn2(CO)8[P(NMe2)3]2

An X-ray crystal structure determination for the bimetallic complex Mn₂(CO)₈-[P(NMe₂)₃]₂ reveals that the P(NMe₂)₃ ligands are trans to the Mn---Mn bond and the Mn---Mn bond distance is relatively long, 2.946(1) Å.     

Tetrakisdimethylamidozirconium and its dimethylamido lithium adduct: Structures of [zr(nme2)4]2 and zr(nme2)6li2(thf)2

The molecular structure of [Zr(NMe₂)₄]₂ has been determined by an x-ray study and shown to involve a central Zr₂N₈ moiety involving the fusing of two trigonal bipyramidal units along a common axial-equatorial edge. The terminal Zr---NMe₂ units have trigonal planar coordination about the nitrogen atoms: Zr---N = 2.050(5) and 2.104(5) Å, and Zr---N (bridge) = 2.224(3) and 2.453(4) Å for equatorial and axial bonds, respectively. The Zr---Zr distance is 3.704(1) Å as expected for a non-M---M bonding bridged compound. In tetrahydrofuran solution, Zr(NMe₂)₄ and LiNMe₂ react irreversibly giving Zr(NMe₂)₆ Li₂(THF)₂ which has been isolated and characterized by an X-ray study. The central ZrN₆ octahedral moiety is capped on two opposite faces by Li atoms which are also coordinated to an oxygen atom of a THF molecule. Pertinent distances are: Zr---N = 2.22(7) (av.), N---Li = 2.155(25) (av.) and Li---O = 1.915(10) Å.     

The tungsten-tungsten triple bond---18. Bridging and terminal allyl ligands in complexes of the formula W2(R)2(NMe2)4, where R = C3H5 and C4H7

The reaction between RMgCl (two equivalents) and 1,2-W₂Cl₂(NMe₂)₄ in hydrocarbon solvents affords the compounds W₂R₂(NMe₂)₄, where R = allyl and 1− and 2-methyl-allyl. In the solid state the molecular structure of W₂(C₃H₅)₂(NMe₂)₄ has C₂ symmetry with bridging allyl ligands and terminal W---NMe₂ ligands. The W---W distance 2.480(1) Å and the C---C distances, 1.47(1) Å, imply an extensive mixing of the allyl π-MOs with the WW π-MOs, and this is supported by an MO calculation on the molecule W₂(C₃H₅)₂(NH₂)₄ employing the method of Fenske and Hall. The most notable interaction is the ability of the (WW)⁶⁺ centre to donate to the allyl π^*-MO (π₃). This interaction is largely responsible for the long W---W distance, as well as the long C---C distances, in the allyl ligand. The structure of the 2-methyl-allyl derivative W₂(C₄H₇)₂(NMe₂)₄ in the solid state reveals a gauche-W₂C₂N₄ core with W---W = 2.286(1) Å and W---C = 2.18(1) Å, typical of WW and W---C triple and single bonds, respectively. In solution (toluene-d₈) ¹H and ¹³C NMR spectra over a temperature range −80°C to +60°C indicate that both anti- and gauche- W₂C₂N₄ rotamers are present for the 2-methyl-allyl derivative. In addition, there is a facile fluxional process that equilibrates both ends of the 2-methyl-allyl ligand on the NMR time-scale. This process leads to a coalescence at 100°C and is believed to take place via an η³-bound intermediate. The 1-methyl-allyl derivative also binds in an η¹ fashion in solution and temperature-dependent rotations about the W---N, W---C and C=C bonds are frozen out at low temperatures. The spectra of the allyl compound W₂(C₃H₅)₂(NMe₂)₄ revealed the presence of two isomers in solution—one of which can be readily reconciled with the presence of the bridging isomer found in the solid state while the other is proposed to be W₂(η³-C₃H₅)₂(NMe₂)₄. The compound W₂R₂(NMe₂)₄ where R = 2,4-dimethyl- pentadiene was similarly prepared and displayed dynamic NMR behaviour explainable in terms of facile η¹ = η³ interconversions.     

Intramolekulare Basenkoordination je nach Bedarf: Der 1-(Dimethylaminoethyl)-2,3,4,5-tetramethylcyclopentadienyl-Ligand in der Komplexchemie von s-, p-, d- und f-Block-Elementen

The synthesis of cyclopentadienyl complexes containing the polydentate C₅Me₄(CH₂CH₂NMe₂) ligand is described. The compounds (C₅Me₄CH₂CH₂NMe₂)₂M (M = Ca, Sm), (C₅Me₄CH₂CH₂ NMe₂)AIEt₂, [(C₅Me₄CH₂CH₂NMe₂)M(CO)₂]₂ (M = Mo, Fe) and [(C₅Me₄CH₂CH₂NMe₂)Fe(CO)₂]⁺BF₄^± are obtained by standard procedures. Except for the dimeric metal carbonyls, all cyclopentadienyl compounds are characterized by an additional intramolecular coordination of the nitrogen atom in the side chain.     

Polymerization of ethylene with (C5Me5)2Zr(NMe2)2 cocatalyzed by common alkyl aluminums

Polymerizations of ethylene have been carried out by using Cp₂^*Zr(NMe₂)₂ (Cp^*=C₅Me₅) compound combined with common alkyl aluminums (AlR₃) and methylaluminoxane (MAO) as cocatalysts. The AlMe₃ cocatalyzed system showed no activity due to the formation of stable but inactive heterodinuclear [Cp₂^*2Zr(μ-Me)₂AlMe₂]⁺ cations; however, the bulkier AlR₃ [AlEt₃, Al(i-Bu)₃ and Al(i-Bu)₂H] cocatalyzed systems showed very high activities. Especially, Cp₂^*Zr(NMe₂)₂/Al(i-Bu)₃ catalyst showed higher catalytic activity and produced higher molecular weight (MW) polymer than Cp₂^*Zr(NMe₂)₂/MAO catalyst, demonstrating both MAO and bulky AlR₃ are effective cocatalysts for Cp₂^*Zr(NMe₂)₂ compound.     

Komplexe mit kohlenstoffsulfiden und -seleniden als liganden : X. Synthese und kristallstruktur von C5H5(PMe3)Co(μ-CS)2CoC5H5: Ein zweikernkomplex mit unsymmetrischen Co(CS)Co-brückenbindungen

The complex C₅H₅(PMe₃)Co(μ-CS)₂CoC₅H₅ (I) is formed by the reaction of C₅H₅Co(PMe₃)CS and CH₂I₂. The X-ray structure analysis shows an unsymmetrical non-planar Co₂C₂-skeleton with different Co---C bond lengths. The Co---Co distance is 239.2 pm. Compound I thus represents a new example of binuclear (18 + 16)-electron complexes in which the more electron-rich metal atom forms a donor bond to the more electron-poor counterpart. The reaction of I with ligands such as P(NMe₂)₃ does not lead to bridge cleavage indicating the stability of the Co(CS)₂Co-framework.     

锡(Ⅳ)、钯(Ⅱ)、金(Ⅲ)与二(2-乙基己基)亚砜配合物的研究

合成了长碳链的二(2-乙基己基)亚砜与锡(Ⅳ)、钯(Ⅱ)、金(Ⅲ)的配合物,通过组成分析、摩尔电导的测定及红外、紫外图谱的研究,确定了配合物的组成,推断了配合物的结构。     

Synthesis and SpectroscOpic Charcterization of Di-and Triphenyltin Derivatives of Dithiocarbomatic Acid

A series of triphenyltin dithiocarbamates Ph₃SnS₂CNR₂, where NR₂=NMe₂,-NEt₂, N(pr-n)₂,-N(CH₂CH₂OH)₂, and diphenyltin derivatives of dithiocarbamatic acid Ph₂Sn(S₂CNR₂)₂,where NR₂=NMe₂,-NEt₂,-N(Pr-n)₂,N(Bu-n)₂, N(CH₂CH₂OH),were synthesiced by the action of the correspending phenyltin (Ⅳ) chlorides with dithiocarbamates in dichloromethane. Their structure were characterized by elemental analysis, IR, HNMR and MS.     

A new synthetic route to aminophosphines

The reactions of R₂PPR₂ (R = Me, Et, Ph) and (MeP)₅ with Me_3−nAs(NMe₂)_n (n = 1, 2, 3) and of Me₂PPMe₂ with Me₂AsNR′₂ (R′ = Et, Prⁿ, and Prⁱ) were investigated as a function of time at room temperature using ¹H and ³¹P NMR spectroscopy. For the diphosphine/Me₂AsNR′₂ reactions, the NMR spectral data suggest a reaction pathway involving the initial formation of R₂PAsMe₂ and the respective acyclic dialkylaminophosphine, R₂PNR′₂. The P---As intermediate then symmetrizes to R₂PPR₂ and Me₂AsAsMe₂, the parent aminoarsine is completely consumed, and additional R₂PNR′ is formed. The relative rate of aminophosphine production is dependent upon the nature of the substituent on the phosphorus and nitrogen atoms. For systems involving MeAs(NMe₂)₂ and As(NMe₂)₃ as reactants, the intermediates could not be characterized, but the products were the expected aminophosphine and (MeAs)₅ or elemental arsenic, respectively. (MeP)₅ reacts to give MeP(NMe₂)₂ and the expected As---As bonded species. A comparison of the reactivity of these systems with analogous diarsine/aminoarsine systems is discussed. The results of the NMR study were utilized in designing a convenient, high yield, synthetic route to acyclic aminophosphines.     

Contribution á l''étude des tris(dialcoylamino)stibines : II. Étude des réactions avec les dérivés carbonylés et les dérivés bifonctionnels

The reaction of Sb(NMe₂)₃ with aldehydes and ketones leads to enamines or diamines according to the degree of substitution of the carbonyl compound. With acids Sb(NMe₂)₃ gives amides, and with β-diketones and β-keto esters it gives enamines. With bifunctional compounds such as diols, secondary diamines or aminoalcohols, different heterocyclic compounds are formed according to the ratio of bifunctional compound to antimony.     

The reactivity of dimethylaluminum hydride with the aminoarsines Me2AsNMe2, MeAs(NMe2)2, and As(NMe2)3

The reactions of (Me₂AlH)₃ with Me₂AsNMe₂, MeAs(NMe₂)₂, and As(NMe₂)₃ were investigated as a function of time at room temperature and over the temperature range −90 to 24°C by use of ¹H and ¹³C NMR spectroscopy. (Me₂AlH)₃ was found to be very reactive toward the aminoarsines, even at −90°C, and no stable Me₂AlH-aminoarsine adducts were observed. Instead, the initial stages of the reactions involved AS---N bond cleavage with the generation of highly reactive AlN- and AsH-bonded species. The subsequent course of each reaction and the final arsenic-containing product distribution depended upon the original AL:N stoichiometric ratio and the respective aminoarsine. When the Al:N ratio was 1:1, the reactions were straightforward for each aminoarsine. However, in every case, [Me₂AlNMe₂]₂ was the final AlN-containing product. Independent reactions were carried out to verify many of the proposed decomposition pathways that lead to thermodynamically stable products. The results of this study are compared with those of the analogous, previously reported (Me₃Al)₂-aminoarsine systems. Additionally, a new synthetic route to [Me₂AlAsMe₂]₃ has been established from the reaction of (Me₂AlH)₃ with Me₂AsH.     

Interaction of antitumor drug Sn(CH3)2Cl2 with DNA and RNA

Sn(CH₃)₂Cl₂ exerts its antitumor activity in a specific way. Unlike anticancer cis-Pt(NH₃)₂Cl₂ drug which binds strongly to the nitrogen atoms of DNA bases, Sn(CH₃)₂Cl₂ shows no major affinity towards base binding. Thus, the mechanism of action by which tinorganometallic compounds exert antitumor activity would be different from that of the cisplatin drug. The aim of this study was to examine the binding of Sn(CH₃)₂Cl₂ with calf thymus DNA and yeast RNA in aqueous solutions at pH 7.1–6.6 with constant concentrations of DNA and RNA and various molar ratios of Sn(CH₃)₂Cl₂/DNA (phosphate) and Sn(CH₃)₂Cl₂/RNA of 1/40, 1/20, 1/10, 1/5. Fourier transform infrared (FTIR) and UV–visible difference spectroscopic methods were used to determine the Sn(CH₃)₂Cl₂ binding mode, binding constant, sequence selectivity and structural variations of Sn(CH₃)₂Cl₂/DNA and Sn(CH₃)₂Cl₂/RNA complexes in aqueous solution. Sn(CH₃)₂Cl₂ hydrolyzes in water to give Sn(CH₃)₂(OH)₂ and [Sn(CH₃)₂(OH)(H₂O)_n]⁺ species. Spectroscopic evidence showed that interaction occurred mainly through (CH₃)₂Sn(IV) hydroxide and polynucleotide backbone phosphate group with overall binding constant of K(Sn(CH₃)₂Cl₂–DNA)=1.47×10⁵ M⁻¹ and K(Sn(CH₃)₂Cl₂–RNA)=7.33×10⁵ M⁻¹. Sn(CH₃)₂Cl₂ induced no biopolymer conformational changes with DNA remaining in the B-family structure and RNA in A-conformation upon drug complexation.     

A new dirbenium complex with an unsupported bridging hydride ligand

The reaction of Re₂(CO)₈(μ-H)2 with CH₂(NMe₂)₂ in chloroform at 25°C yielded the new compound Re₂(CO)₈(NHMe₂)(Cl)(μ-H) (1) in 31% yield. Compound 1 was characterized by IR, ¹H NMR and a single-crystal X-ray diffraction analysis. Crystal data: orthorhombic, Pbca, a = 13.787(4), b = 19.884(5), c = 12.296(2) Å. Solution by direct methods (MITHRIL), R = 0.035 for 1800 reflections. The complex contains two rhenium atoms linked by an unsupported hydride bridge, Re Re = 3.362(1) Å, Re(1)---H = 1.8(1) Å and Re(2)---H = 2.0(1) Å. A chloride ligand abstracted from the solvent is terminally bonded to Re(1), and a dimethylamine ligand abstracted from the CH₂(NMe₂)₂ is coordinated to Re(2). When heated to 68°C, the dimethylamine ligand was eliminated and the chloride ligand became a bridge in the new compound Re₂(CO)₈(μ-H)(μ-Cl) (2), yield 76%.     

Group 6 carbene complexes derived from lithiated azoles and the crystal structure of a molybdenum thiazolinylidene complex

Fischer-type (alkoxy)azolyl carbene complexes and Öfele–Lappert-type azolylinylidene complexes were synthesised by reaction of 1-phenylpyrazol-3-yllithium, 4-methylthiazol-2-yllithium, benzothiazol-2-yllithium, 1-methylimidazol-2-yllithium with M(CO)₅L (L=CO, THF or Cl⁻; M=Cr, Mo or W) and subsequent alkylation with CF₃SO₃CH₃. The alkylation of Fischer-type carbene complexes containing an azolyl as the organic substituent proceeded via ring opening of tetrahydrofuran. When the alkylation is carried out in THF, the carbocation CH₃O(CH₂)₄⁺ acts as an electrophile. Protonation rather than alkylation of coordinated imidazolyl furnished cyclic imine complexes. Changing the donor atom of a coordinated thiazole from N to C by deprotonation and alkylation afforded a carbene complex.     

Immobilization of η-cyclopentadienyltris(dimethylamido)zirconium polymerization catalysts on a chlorosilane- and HMDS-modified mesoporous silica surface: a new concept for supporting metallocene amides towards heterogeneous single-site-catalysts

The modification of a mesoporous silica surface with Si(Ind)(CH₃)₂Cl and the immobilization of CpZr(NMe₂)₃ on this surface was studied via IR-spectroscopy. To reduce side reactions, the indenyl-modified silica was reacted with hexamethyldisilazane (HMDS) under IR-control before the CpZr(NMe₂)₃-immobilization. The role of the hydroxyl group protection with HMDS is discussed. The surface modifications have been repeated via Schlenk technique at the same conditions and the surface modifications were studied with ¹³C CP MAS–NMR, ¹H MAS–NMR, elemental-, SEM- and BET-analysis. The surface species of the resulting catalysts are discussed. The precatalysts have been treated with methylaluminoxane (MAO) (Al:Zr (mol:mol)=500:1) and the resulting Zr contents (leaching-effect) are discussed. All catalysts have been tested in ethylene and propylene polymerization.     

Synthesis and X-ray structure of (η-C5H5)2W2Ir2(CO)7(CHCO2Et)2, a tetrahedral heterometal cluster with two different environments for ethylcarboxylatocarbene ligands

The tetrahedral heteronuclear cluster complex (η⁵-C₅H₅)₂W₂Ir₂(CO)₁₀ reacts with N₂CHCO₂R (R = Et, Me) at room temperature to form the dicarbene species (η⁵-C₅H₅)₂W₂Ir₂(CO)₇(CHCO₂R)₂. An X-ray diffraction study (R = Et) shows an intact tetrahedral metal framework with two distinct sites for the CHCO₂Et ligands. The first uses its carbon atom to bridge the Ir---Ir bond; the second uses its carbon atom to bridge an Ir---W bond and, additionally, forms a donor bond from a carbonyl oxygen atom to the second tungsten atom.     

Syntheses of complexes containing substituted 4-ethynylquinolines or 1-azabuta-1,3-dienes by addition of imines to a cationic butatrienylidene-ruthenium complex

Reactions of [Ru(=C=C=C=CH₂)(PR₃)₂Cp]⁺ (R=Ph or OMe) with arylimines ArN=CH(C₆H₄R) afford either substituted quinolines, Ru{CCC₉H₄RN(Ar)}(PR₃)₂Cp, by attack of the terminal carbon of the butatrienylidene ligand at the imine carbon, followed by C---C bond formation between the ortho carbon of the N-aryl group and C_γ of the unsaturated carbene, or 1-azabuta-1,3-dienyl complexes, formed by cycloaddition of the N=CH group to C_γ=C_δ of the carbene, followed by opening of the resulting four-membered ring. Some product dependence on the nature of the substituents in the N- and C-aryl groups is found. The N atoms in the products are strongly basic, being readily protonated, methylated or aurated. The molecular structures of nine complexes are reported, together with that of a new modification of RuCl{P(OMe)₃}₂Cp.