Several complexes of the type RuTp(L)(L H )Cl (L, L H P, N, O donors) were 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 being the most ef®cient pre-catalyst. In the absence of a phosphine ligand, polymerization takes place with RuTp(COD)Cl as the most effective pre-catalyst. Both product distribution and conversion depend strongly on the substituent of the alkyne and to a lesser extent on the co-ligands of the ruthenium complex. The catalytically active species is the 16e À alkynyl complex RuTp(L)(±C:C±R) which in case of L PCy 3 and R Bu n could be trapped as RuTp(PCy 3 )(±C:CBu n )(CO).
The synthesis and characterization of RuTp complexes containing the chelating ligands, acetylacetonate (acac), and tetramethylethylenediamine (tmeda) is described. While with NN, N-crab, acac, and tmeda mononuclear complexes are formed, a dimeric species is obtained with NS. X-ray structures of some complexes are given. The complexes featuring NN, acac, and tmeda react readily with terminal acetylenes to give vinylidene complexes.
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.
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