39475-28-0

Upstream product

• 501-65-5 diphenyl acetylene 
• 2789-88-0 1,2-bis(4-methylphenyl)acetylene 
• 113809-75-9 Ti(η4-tetraphenylcyclobutadiene){(μ-Br)2(AlBr2)}2 
• 34480-05-2 dipotassium cyclooctatetraenide 

Relevant academic research and scientific papers

CYCLOTRIMERIZATION OF SUBSTITUTED ACETYLENES TO ARENES BY TITANIUM COMPLEXES

Cyclotrimerization experiments of substituted acetylenes to arenes with (a) C8H8Ti complexes and with (b) TiCl3 are reported.A cyclotrimerization mechanism is proposed which involves the concerted trimerization of three acetylenes coordinated to a divalent titanium centre.The organometallic compounds isolated from the reaction mixtures, viz. (C8H8TiPhC2Ph)2, C8H8TiC4Ph4 in (a) and - + in (b) are shown not be intermediates in the cyclotrimerization.

Bis8-cyclooctatetraene)titanum> complex with perpendicularly bridging bis(trimethylsilyl)acetylene

The reduction of 8-C8H8)Ti(THF)(μ-Cl)>2 by magnesium in the presence of bis(trimethylsilyl)acetylene (BTMSA) afforded the diamagnetic complex 8-C8H8)Ti>22:η2-Me3SiCCSiMe3> (1) in high yield.The crystal structure of 1 revealed that BTMSA is a four-electron ligand which binds two equivalent (η8-C8H8)Ti moieties under the angle of av. 69 deg.The average C-C distance of 1.51 Angstroem in the acetylene ligand is close to that of sp3 carbon atoms, however, a high thermal stability and enormously large down-field chemical shift of the acetylenic carbon atoms (δ 292.8 ppm) points to an unusually high contribution of ?-back-bonding to the Ti-acetylene bond.An analogous reduction in the presence of diphenylacetylene afforded a tetraphenylcyclobutadiene complex (η8-C8H8)Ti(η4-C4Ph4) and hexaphenylbenzene. - Keywords: Titanium; Cyclooctatetraene dianion; Bis(trimethylsilyl)acetylene bridge; Crystal structure

Reactivity of Titanium(II) Arene Derivatives with Substituted Alkynes. Cyclooligomerization Reactions and Crystal and Molecular Structure of 4-C4(C6H5)4>Ti2

By treating Ti(η6-toluene)2 (X = Cl: 1a, X = Br: 1b) with C2R2 (R = Me, Ph) tetraorganylcyclobutadiene complexes of formula Ti(η4-C4R4)2 (R = Ph, X = Cl: 2a, X = Br: 2b; R = Me, X = Br: 3b) have been obtained in good yields.Compound 2b has been studied by X-ray diffraction methods.The titanium atom possesses an approximate square pyramidal coordination, the apical position being occupied by the symmetrically bonded tetraphenylcyclobutadiene ring, the four bridging bromides to the two AlBr2 groups forming the base of the pyramid, 0.99 Angstroem away from the titanium atom.The tetrabromoaluminato moiety of 2b can be substituted by carbocyclic anionic ligands, such as Cp and COT, and the corresponding complexes 4 and Ti(4h4-C4Ph4)(COT) were obtained.The spectroscopic study of the Ti(η6-benzene)2/diphenylacetylene (DPA) system (X = Cl: 5a, X = Br: 5b) has revealed the existence of three products, corresponding to the 1:1, 1:2, and 1:3 molar ratios.The possible role of the known AlX3 * C4R4 complexes in this reaction is discussed.The cyclotrimerization reactions of substituted acetylenes in the presence of η6-arene titanium(II) complexes as precursors have been studied.In toluene or methylcyclohexane Ti(η6-toluene)2 was found to catalyze the formation of alkyl-substituted aromatic hydrocarbons from 2-butyne, phenylacetylene, and 1-hexyne at about 80 deg C over 15 h with turnovers (moles of converted alkyne per mole titanium) of about 520, 900, and 990, respectively.The cyclooligomerization of DPA in the presence of Ti(η6-benzene)>(μ-X)2(AlX2)>2 (X = Cl, Br) was studied in detail.The activity of the chloro derivative 5a is higher than that of the bromide catalytic precursor 5b.In addition to hexaphenylbenzene and octaphenylcyclooctatetraene, other oligomerization by-products (triphenylethylene, 1,1,2,2-tetraphenylethane, 1,2,3-triphenylnaphthalene, and 1,2,3-triphenylazulene) were observed, whose formation was drastically reduced in the presence of alkyl aluminium halides. - Key Words: Titanium / Cyclooligomerization / Acetylenes, substituted / Tetraphenylcyclobutadiene, ligand