Oligomerization Of Alkynes Research Articles

Reaction of Ru 3{μ-H, μ-OCNMe 2}(CO) 10 with diarylacetylenes; synthesis and subsequent reaction of a {μ-carboxamido, μ-σ,π-vinyl}-hexacarbonyl diruthenium complex with propyne. Crystal and molecular structures of Ru 2{μ-OCNMe 2,μ-σ,π-C( p-tol)CH( p-tol)}(CO) 6, and of Ru 2{μ-OCNMe 2,μ-σ,π-C(CH 3)C(H)C( p-tolyl)CH( p-tolyl)}(CO) 6 ( p-tol = p-CH 3C 6H 4)

The complex Ru 3{μ-OCNMe 2,μ-H}(CO) 10 ( 1) is observed to react with diphenylacetylene ( 2a), di( p-tolyl)acetylene ( 2b), or di( p-anisyl)acetylene ( 2c), at 23° C in hexane solution over a period of 12 h to give Ru 2{μ-OCNMe 2,μ-σ,π-C(Ar)CH(Ar)}(CO) 6, Ar = Ph ( 3a), p-CH 3C 6H 4 ( 3b), or p-CH 3OC 6H 4 ( 3c). Principal by-products are Ru 3(CO) 12 and the acetylene oligomerization complexes {η 5-(OC) 3 RuC(Ar)C(Ar)C(Ar)C (Ar)}Ru(CO) 3, Ar = C 6H 5 ( 4a), Ar = p-tolyl, CH 3C 6H 4 ( 4b), Ar = p-anisyl, CH 3OC 6H 4 ( 4c). Variable temperature 13C NMR of 3a, 3b, and 3c indicates the presence of two rapidly interconverting isomers in solution, one with geminal and the other with vicinal bridging groups. Complex 3b is observed to react with propyne at 23° C in hexane over a period of 4 h giving as principal product Ru 2{μ-OCNMe 2,μ-σ,π-C(CH 3)C(H)C( p-tolyl)CH( p-tolyl)}(CO) 6, 5. The crystal and molecular structures of 3b and 5 have been determined using graphite-monochromatized Mo- K α radiation on a Huber four circle diffractometer under control of a VAX 11/750 computer. Complex 3b crystallizes in the monoclinic space group P2 1/ a; cell dimensions a = 20.1744(23), b = 7.3166(8), c = 18.9413(22) Å, and β = 93.2730(31)° and Z = 4, V = 2786.12 Å 3; ρ(calc.) = 1.55 g cm −3. A total of 3923 unique reflections with I > 3σ( I) were used in the refinement; final discrepancy indices, R = 0.057 and R w = 0.071. The crystal consists of discrete molecules of the complex in which the metal-metal separation Ru(1)Ru(2) = 2.739(1) Å. The two bridging groups, namely {μ-σ,π-C(50)(Ar)C(40)H(Ar)} and {O(30)C(30)NMe 2}, are seen to be attached to the two metal centers in a vicinal arrangement with a near octahedral arrangement of σ-bonded atoms around each metal. Bond distance parameters for the bridging groups are (Å): Ru(2)O(30) = 2.117(5); O(30)C(30) = 1.283(8); Ru(1)C(30) = 2.106(7); Ru(1)C(50) = 2.324(7); Ru(1)C(40) = 1.410(9); Ru(2)C(50) = 2.081(7); C(40)C(50) = 1.410(9). Complex 5 crystallizes in the monoclinic space group P2 1/ c with cell dimensions: a = 10.421(4), b = 33.157(10), c = 8.896(3) Å, β = 90.34(3)° and Z = 4, V = 3078 Å 3; ρ(calc.) = 1.49 g cm −3. The structure was solved by the heavy atom method. A total of 3159 unique reflections with I > 3σ( I) were used in the refinement; final discrepancy indices, R F = 0.085 and R wF = 0.110. Complex 5 consists of two tricarbonyl ruthenium fragments joined by a strong RuRu bond, 2.726(2) Å, accompanied by a bridging carboxamido group and a bridging σ,π-group (C(CH 3)C(H)R (R = C( p-tolyl)C(H) p-tolyl) in a sigma-geminal arrangement. This type of complex is perceived as a common intermediate to the oligomerization products 4a, 4b, 4c observed in the present and previous studies, and the complex Ru 2{μ-OCNMe 2, μ-OCC(Me)CMe(η 2-CMeCHMe)}(CO) 5, observed in a previous study.

Oligomerization of alkynes by the RhCl 3-aliquat 336 catalyst system : Part 1. Formation of benzene derivatives

The cyclo-oligomerization of several terminal and internal alkynes under phase transfer conditions by the RhCl 3-Aliquat® 336 catalyst is described. The kinetics of 1-heptyne cyclotrimerization at 90 °C in 1,1,2,2-tetrachloroethane/water were found to follow the second-order rate law d[arene]/d t = − k[alkyne][RhCl 3] when the molar ratio of substrate:rhodium chloride:quat was approximately 25:1:1. The activation energy of E a = 12.5 kcal mol −1 suggests that the catalysis is both chemically and diffusion controlled. Product analysis is compatible with a mechanism that involves rhodacyclopentadiene rather than metal cyclobutadiene intermediates.

Oligomerization of alkynes by the RhCl 3-aliquat 336 catalyst system : Part 2. formation of 2,3-disubstituted 1-phenylnaphthalenes by cyclodimerization of phenylalkynes

The RhCl 3-Aliquat® 336 ion pair in 1,1,2,2-tetrachloroethane was shown to catalyze both cyclodimerization and trimerization of internal phenyl-alkynes in a highly regioselective manner. Thus, 1-phenyl-1-propyne, 1-phenyl-1-butyne and 4-phenyl-3-butyn-2-one result in the corresponding 2,3-disubstituted 1-phenylnaphthalenes, in addition to the respective 3,5,6-trisubstituted 1,2,4-triphenylbenzenes as the only cyclotrimerization products. Diphenylacetylene yields 1,2,3-triphenylnaphthalene and hexaphenyl-benzene. Formation of small amounts of 1-chloro-2,3-dimethyl-4-phenylnaphthalene and 1-(2-chlorophenyl)-2,3-dimethylnaphthalene, in the cyclo-oligomerization of 1-phenyl-1-propyne, supports a mechanism in which initial oxidative coupling of the alkyne functions produces a 2,5-diphenylrhodacyclopentadiene capable of subsequent ortho-metallation of the phenyl substituents, followed by metal hydride transfer and reductive elimination of the resultant benzometallacycloheptatriene intermediate.

Activation of alkynes by the dinitrogen complex [CoH(N2)(PPh 3)3] towards catalytic oligomerization and cyclization reactions

The complex [CoH(N2)(PPh 3)3] catalyses oligomerization and cyclization reactions of alkynes under mild conditions. Hence, alkyne cocyclotrimerization to benzene derivatives was mainly observed for ethyl propiolate, affording the three possible isomers of tricarbethoxybenzene; phenylacetylene undergoes mainly linear dimerization totrans-PhC≡CCH=CHPh and trimerization; linear dimers are also the predominant products from 3-hexyne, but 1-octyne (with a long chain) undergoes mainly isomerization to 2-octyne; higher oligomers are also usually formed. Except for ethyl propiolate, hydrogenated dimers are detected in low yields (e.g.trans,trans-PhCH=CHCH=CHPh from phenylacetylene), whereas 3-hexene is formed in considerable yield from 3-hexyne. A novel type of cocyclization reaction with a nitrile (NCMe) appears to occur with phenylacetylene to give (although in low yield) 4,6-dimethyl-5-phenyl-pyrimidine. Alkynols are unreactive under the chosen conditions.

Oligomerization of alkynes by hafnocene dichloride/ethylaluminum dichloride

The Cp2HfCl2/C2H5AlCl2 system (Cp = η5-cyclopentadienyl) was found to be an active homogeneous catalyst for the Oligomerization of both terminal and internal alkynes. Apparently, the mechanism of Oligomerization occurs by successive insertion of the alkyne into the hafnium-carbon bond of a cationic intermediate, as evidenced by the interception of the highly substituted, sterically bulky, 1-trimethylsily1-1-propyne.

The nature of alkyne oligomerization on the face of a mixed-metal trinuclear cluster

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe nature of alkyne oligomerization on the face of a mixed-metal trinuclear clusterRichard D. Adams, James E. Babin, and Miklos. TasiCite this: Organometallics 1987, 6, 10, 2247–2248Publication Date (Print):October 1, 1987Publication History Published online1 May 2002Published inissue 1 October 1987https://doi.org/10.1021/om00153a036RIGHTS & PERMISSIONSArticle Views38Altmetric-Citations14LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (288 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

ChemInform Abstract: Organic Chemistry of Subvalent Transition Metal Complexes. Part 11. Oxidative Additions of Nickel(0) Complexes to Carbon‐Carbon Bonds in Alkynes: Nickelirenes and Nickeloles as Catalytic Carriers in the Oligomerization of Alkynes.

AbstractTetraphenylbutadiene (Ia) reacts via its dilithio compound (Ib) with the Ni complexes (II) to give the nickeloles (III) which can also be obtained from the cyclobutadienyl complex (V).

Studies on the mechanism of oligomerization of alkynes by group IVB catalysts

AbstractThe homogeneous catalyst systems Cp2MCl2/C2H5AlCl2 (Cp = cyclopentadienyl; M = Ti, Zr) were found to promote homooligomerization of internal and terminal alkynes. Studies using titana‐ and zirconacyclopentadienes without cocatalysts revealed that these molecules were likely formed in the reactions and were active catalytic intermediates. Isolation of expanded metallacycles indicated that the mechanism of oligomerization proceeded by successive insertion reactions to produce larger metallacycles, eventually giving linear oligomers of low molecular weight.

Organic chemistry of subvalent transition metal complexes: XI. Oxidative additions of nickel(0) complexes to carbon-carbon bonds in alkynes: Nickelirenes and nickeloles as catalytic carriers in the oligomerization of alkynes

The formation of 2,3,4,5-tetraphenylnickelole-bis(triphenylphosphine) (IIIa) and 2,3,4,5-tetraphenylnickelole-bis(1,2-diphenylphosphino)ethane (IIIb), either from ( E, E)-1,2,3,4-tetraphenyl-1,3-butadien-1,4-ylidenedilithium (I) and the corresponding nickel(II) chloride-phosphine complexes (II) or from the reduction of η 4-tetraphenylcyclobutadienenickel(II) bromide dimer (XII) in the presence of phosphines, proceeds in good yields. Nickelole IIIa displays physical and chemical properties consistent with its structure and is a catalyst for the trimerization of diphenylacetylene. Nickelole IIIb is a highly associated structure but in its chemical response to alkynes, HOAc, O 2, Br 2, NaAlEt 2H 2 and heat displays the properties of a nickelole, rather than a cyclobutadienenickel(0) complex. Attempts to generate IIIb photochemically from η 4-1,5-cyclooctadiene(η 4-tetraphenylcyclopentadienone)nickel and diphos failed, but it was shown that structural types, such as η 4-tetraphenyl-cyclopentadienone(diphos)nickel (a model for the structure suggested by Hoberg and Richter for IIIb), are unstable. Oligomerizations of diphenylacetylene by bis(1,5-cyclooctadiene)nickel were retarded by conducting the reaction in THF or in the presence of diphos. This retardation permitted the interception of products ( cis-stilbene and ( E, E)-1,2,3,4-tetraphenyl-1,3-butadiene) diagnostic for the intermediacy of nickelirenes and nickeloles. Deuterium labeling verified the presence of carbon-nickel bonds. These trapping experiments, together with findings on the thermal behavior of nickeloles, are combined into a comprehensive view of the cyclotrimerization, cyclotetramerization and linear polymerization of alkynes by nickel(0).

Alkine und Cumulene, XVIII. Zur Acetylen‐Oligomerisierung nach Nieuwland: Struktur der Tetrameren

Alkynes and Cumulenes, XVIII. On the Nieuwland Acetylene Oligomerization: Structure of the TetramersThe tetramers formed during the Nieuwland acetylene oligomerization are shown to be (E)‐ and (Z)‐1,3,7‐octatrien‐5‐yne [(E)‐ and (Z)‐5] by their 1H and 13C NMR spectra as well as by chemical structure proof.

Die oxidative Addition von NickeI(0)-KompIexen an Kohlenstoff-Kohlenstoff-Bindungen im Cyclobutadien. Zur Frage der Überführbarkeit von Cyclobutadien-Nickel(O)-Komplexen in Nickelaringe / Oxidative Addition of Nickel(O) Complexes to Carbon-Carbon Bonds in Cyclobutadiene. The Question of the Interconvertibility of Cyclobutadiene-nickel(O) Complexes and the Nickelaring Systems

Abstract Bis(triethylphosphine)(η4-tetraphenylcyclobutadiene)nickel (4) was synthesized by the reduction of (η4-tetraphenylcyclobutadiene)nickel(II)bromide (3) with t-butyllithium in the presence of Et3P, and its structure was determined by X-ray crystallography. Furthermore, its reactivity towards CO, CH3CO2H, PhC≡CPh, LiAlH4 and O2 were investigated. 1,1-Bis(triethylphos-phine)-2,3,4,5-tetraphenylnickelole (14) was synthesized from (E,E)-1,4-dilithio-1,2,3,4-tetraphenyl-1,3-butadiene (15) and bis(triethylphosphine)nickel(II)bromide. Since the resulting crystals of the nickelole were not suitable for X-ray structure determination, the compound was characterized by elemental analyses, spectral data and carbonylation to yield tetraphenylcyclo-pentadienone (6). Analogous reductions of (η4 -tetraphenylcyclobutadiene)nickel(II)bromide (3) in the presence of Ph3P or Ph2PCH2CH2PPh2 , followed by carbonylation, led to 6 in 40% yield, demonstrating that about half of the cyclobutadiene rings in 3 undergo cleavage upon reduction to give the nickelole. Reactions of the dilithium reagent 15 with NiBr2 complexed with Me2PCH2CH2PMe2 ,Ph3P or Et2PCH2CH2PEt2 , led to the formation of thermolabile nickeloles, as demonstrated by carbonylàtion which yielded 6. Warming of the nickeloles and subsequent treatment with CH3CO2H led to the formation of 1,2,3,4,5,6,7,8-octaphenyl-1,3,5,7-octatetraene (8) and, in one case, octaphenyl-cyclooctatetraene (5). The relevance of these findings to the mechanism of the Reppe nickel-catalyzed oligomerization of alkynes is discussed.

The mechanistic role of η2-vinyl complexes in metal-promoted alkyne oligomerisations. The crystal and molecular structures of [W{η5-C(CF3)C(CF3)C(CO2Me )C(CO2Me)C(CF3)C(CF3)SPri}(η5-C5H5)], [WF {η5-C(CF2)C(CF3)C( CO2Me)C( CO2Me)C(CF3)C(CF3)SPri}(η5-C5H5)], and [W{η4-C(CF3)C(CF3)C(Me)C(Me)SPri}(η2-CF3CCCF3)(η5-C5H5)

Reactions of Alkynes RCCR (R = CF3, CO2Me, or Me) with η2-vinyl complexes [W{η2-C(CF3)C(CF3)SR′}(CF3CCCF3)(η5-C5H5)](R′= Et, Prn, or Pri) give isomeric products [W(CF3C2CF3)2(RC2R)SR′(η5-C5H5)] resulting from insertion of the incomingalkyne into the MC bond of the η2-vinyl and thus illustrate that η2-vinyls can act as intermediates in metal-promoted alkyne oligomerisation reactions.

ChemInform Abstract: Alkyne Oligomerization and CO Activation on Ruthenium Clusters. Synthesis and Crystal Structure of Ru3(CO)5(C12H20)(C19H30O). The Stepwise Formation of a Heterocyclic Ring without Cluster Degradation.

AbstractDie beiden Isomeren des Titelkomplexes (II) entstehen bei der Reaktion von Dodecacarbonyltriruthenium (I) oder des 3,3‐Dimethylbutinyl‐hydrido‐Derivats (III) mit überschüssigem tert.‐Butylacetylen in siedendem Heptan.

Alkyne oligomerization and CO activation on ruthenium clusters. Synthesis and crystal structure of Ru 3(CO) 5(C 12H 20)(C 19H 30O). The stepwise formation of a heterocyclic ring without cluster degradation

The title complex was obtained in a reversible reaction by treating Ru 3(CO) 6(C 12H 20)(C 13H 20O) with excess t-butylacetylene in hydrocarbon solvents. From the two isomers of the starting product, the corresponding isomers of the new complex were obtained. The structure of one of the isomers has been determined by X-ray methods; crystals are triclinic, space group P 1 , with two molecules in a unit cell of dimensions a = 11.830(8), b = 17.096(7), c = 10.368(9) Å, α = 102.31(4), β = 113.61(5), γ = 96.23(5)°. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares to R = 5.0% for 2299 observed reflections. The complex consists of a nearly equilateral triangle of ruthenium atoms bonded to five terminal carbonyls; two independent organic moieties interact with all the metals of the cluster. The former is formed by two oligomerized alkynes and is responsible for the isomerism of the complex, the latter is an heterocyclic organic ring obtained by the insertion of one carbonyl into three molecules of alkyne. The formation mechanism of the complex, starting from Ru 3(CO) 12 and alkynes, is discussed on the basis of deuteration experiments and of the structures of intermediate derivatives.

Metal alkoxides: models for metal oxides. 2. Addition of ethyne, propyne, and 2-butyne to Mo2(OR)6 (M.tplbond.M) compounds (R = tert-Bu, iso-Pr, and neopentyl). Characterization of .mu.-alkyne and .mu.-C4H4 adducts and an evaluation of their role in alkyne oligomerization reactions

Rapid reactions of hydrocarbon solutions of Mo/sub 2/(OR)/sub 6/(M triple bond M) compounds where R=t-Bu, i-Pr, and CH/sub 2/CMe/sub 3/ with the alkynes C/sub 2/H/sub 2/, MeC/sub 2/H, and MeC/sub 2/Me are reported. The ..mu..-acetylene and ..mu..-C/sub 4/H/sub 4/ adducts formed with the reaction products in the presence of pyridine have been isolated and characterized. X-ray diffraction and NMR studies of the adducts are reported. (BLM)

Acetylenes and noble-metal compounds. Part 15. Reactions of dialkylacetylenes with bis(acetonitrile)dichloroplatinum(II) and tin(II) chloride to give ionic cyclobutadieneplatinum–tin complexes

Acetylenes (C2R2, R = Me or Et) react with [Pt(NCMe)2Cl2] and SnCl2 to give the ionic tetra-alkylcyclobutadiene complexes [Pt2(C4R4)2Cl3][Pt(C4R4)(SnCl3)3](2) which can be converted into the tin-feer complexes [Pt2-(C4R4)2Cl4](3) by reaction with HCl and acetone, or into the salts [N(PPh3)2][Pt(C4R4)(SnCl3)3](4) plus (3) by reaction with [N(PPh3)2]Cl. Structures are assigned on the basis of spectroscopic data, in particular the intensities of the 195Pt, 117Sn, and 119Sn satellites of the methyl resonances in the 1H n.m.r. spectra of (2 and 4; R = Me). Two new complexes of di-t-butylacetylene (2,2,4,4-tetramethylhex-3-yne), [Pt(C2But2)(NCMe)(SnCl3)-Cl] and [Pt2(C2But2)2(SnCl3)2Cl2], are also described. The mechanism of the acetylene dimerisation reaction leading to (2) is discussed by comparison with the acetylene oligomerisation reactions induced by PdII.

Reactivity of the ruthenium carbonyl hydride HRu 3(CO) 9C2C(CH 3) 3

In the products of the reaction of Ru 3(CO) 12 and 3,3-dimethyl-1-butyne, hydrogen transfer and alkyne oligomerization are observed. The behaviour of the main product, HRu 3(CO)9C 2C(CH 3) 3 towards electrophilic reagents hat been investigated. By deuterium labelling some insight has been gained into the mechanism of the reaction

The palladium(II)-induced oligomerization of acetylenes: an organometallic detective story

The palladium(II)-induced oligomerization of acetylenes: an organometallic detective story

The role of nickelole intermediates in the oligomerization of alkynes

Bis(triphenylphosphine)nickel(II) chloride reacts with E,E,-1,4-dilithio-1,2,3,4-tetraphenylbutadiene to yield a solution of a 2,3,4,5-tetraphenylnickelole complex. This compound reacts promptly with CO to yield tetracyclone, with dimethyl acetylenedicarboxylate to form dimethyl tetraphenylphthalate and catalytically with diphenylacetylene to form hexaphenylbenzene. A similar treatment of (1,2-bis(diphenylphosphino)ethane)nickel(II) chloride with the lithium reagent led to the isolation of (1,2-bis(diphenylphosphino)ethane)bis(2,3,4,5-tetraphenylnickelole), which likewise reacts with dimethyl acetylenedicarboxylate to yield dimethyl tetraphenylphthalate. These results support the interpretation that nickeloles are reactive intermediates in the cyclotrimerization of alkynes by nickel(0) catalysts.

Stereospecific alkylation of alkynes by bis(π-allyl)nickel and the mechanism of oligomerization of alkynes by nickel(0)

Bis(π-allyl)nickel effects the stereospecific cis-diallylation of methyl(phenyl)acetylene and diphenylacetylene in 30–50% yield. The former acetylene also gives minor amounts of both cis-regioisomers of monoallylated product and some (allyl)propenyl adducts. The nickel(0) generated in the diallylation causes the reductive dimerization and cyclotrimerization of the alkyne. Since deuterolytic workup either of the allylation reaction mixture or of a mixture of alkyne and (c-C 8H 12)P 2Ni leads to a 1,4-dideuterioalkadiene, it is proposed that the alkyne oligomerization proceeds via a nickelole intermediate.