ChemInform Abstract: Ruthenium Catalyzed Homocoupling of Terminal Alkynes.

Abstract

Ruthenium Catalyzed Homocoupling of Terminal Alkynes.-Several complexes of the type RuTp(L)(L')Cl (Tp: hydridotris(pyrazolyl)borate) are tested with respect to their ability of promoting catalytic C-C coupling reactions of terminal acetylenes.When L: tertiary phosphine, predominantly dimerization occurs. RuTp(PPh 3 ) 2 H proves to be the most efficient pre-catalyst. Product distribution and yields strongly depend on the substitution pattern of the alkyne, and to a lesser extent on the co-ligands of the Ru-complex. In the absence of a phosphine ligand, polymerization takes place.-(SLUGOVC, C.; DOBERER, D.; GEMEL, C.; SCHMID, R.; KIRCHNER, K.; WINKLER, B.; STELZER, F.; Monatsh.

ChemInform Abstract: Ruthenium Tris(pyrazolyl)borate Complexes. Part 12. Cross Coupling of Acetylenes with Olefins — Formation of η3‐Butadienyl and η2‐Butadiene Complexes via a Metallacyclobutane Intermediate.

“…A polar medium has been chosen to allow for better ionization of the chloride to facilitate the opening of a coordination site. However, no such complex was formed and basically unchanged 1 was obtained, A rather rare example of CϪC bond formation within a together with polymeric materials [9] and a small amount of vinylidene complex is the cycloaddition of alkynes and olea new complex identified as [Ru(tp){(1,2-η;5,6-η)-1-[(Z)-3fins to the MϭC bond giving metallacyclobutene and metphenyl-1-ethenyl]cyclooctadiene}Cl] (3). Formation and common modes of reaction of vinylidene complexes favor cationic vinylidene complexes.…”

“…Reaction of 1 with HCϵCPh in the presence of excess 13 C{ 1 H}-NMR spectroscopy. Vinylidene mechanism (ii) In the absence of base only polyacetylenes [9] were ob-voids of about 40 Å 3 per unit cell. In the 13 C{ 1 H}-NMR spectrum, the enynyl carbon atoms exhibit a characteristic resonance at δ ϭ 171Ϫ181.…”

“…, J ϭ 1 9. Hz, 1 H, tp), 6.22 (dd, J ϭ 2.4 Hz, J ϭ 1 9. Hz, 1 C of COD), 88.5 (olefinic C of COD), 85.8 (olefinic C of COD),38.4 (aliphatic C of COD), 32.5 (aliphatic C of COD), 30.1 (ali-H, tp), 5.86 (vt, J ϭ 2.4 Hz, 1 H, tp), 3.73 (m, 1 H, olefinic H of COD), 3.48 (m, 1 H, olefinic H of COD), 3.01Ϫ2.02 (m, 7 H), 1.20 phatic C of COD), 27.8 (aliphatic C of COD).…”