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Synthesis, characterization and properties of rigid macromolecules with extended conjugation, using palladium-catalyzed alkynylated polyhaloarenes. (open access)

Synthesis, characterization and properties of rigid macromolecules with extended conjugation, using palladium-catalyzed alkynylated polyhaloarenes.

A synthetic approach to macromolecules of acetylenic arrays and luminescent properties is proposed and the execution of initial steps is described. Palladium-catalyzed coupling of 1,3,5-triiodobenzene with trimethylsilylbuta-1,3-diyne, trimethylsilylocta-1,3,5,7-tetrayne, and trimethylsilylhexadeca-1,3,5,7,9,11,13,15-octayne to yield the new 1,3,5-tris(trimethylsilylbuta-1,3-diynyl)benzene and the proposed 1,3,5-tris(8-(trimethylsilyl)octa-1,3,5,7-tetraynyl)benzene and 1,3,5-tris(trimethylsilyl)hexadeca-1,3,5,7,9,11,13,15-octaynyl)benzene respectively. The proposed three-coordinate Au (I) complexed macromolecules will be derived from the metallation of the aforementioned alkynylated arenes.
Date: December 2007
Creator: Akintomide, Temiloluwa
System: The UNT Digital Library
Synthesis and characterization of diphosphine ligand substituted osmium and ruthenium clusters. (open access)

Synthesis and characterization of diphosphine ligand substituted osmium and ruthenium clusters.

The kinetics for the bridge-to-chelate isomerization of the dppe ligand in H4Ru4(CO)10(dppe) have been investigated by UV-vis and NMR spectroscopies over the temperature range of 308-328 K. The isomerization of the ligand-bridged cluster 1,2-H4Ru4(CO)10(dppe) was found to be reversible by 31P NMR spectroscopy, affording a Keq = 15.7 at 323 K in favor of the chelating dppe isomer. The forward (k1) and reverse (k-1) first-order rate constants for the reaction have been measured in different solvents and in the presence of ligand trapping agents (CO and PPh3). On the basis of the activation parameters and reaction rates that are unaffected by added CO and PPh3, a sequence involving the nondissociative migration of a phosphine moiety and two CO groups between basal ruthenium centers is proposed and discussed. The substitution of the MeCN ligands in the activated cluster 1,2-Os3(CO)10(MeCN)2 by the diphosphine ligands dppbz proceeds rapidly at room temperature to furnish a mixture of bridging and chelating Os3(CO)10(dppbz) isomers and the ortho-metalated product HOs3(CO)9[μ-(PPh2)C=C{PPh(C6H4)}C4H4]. Thermolysis of the bridging isomer 1,2-Os3(CO)10(dppbz) under mild conditions gives the chelating isomer 1,1-Os3(CO)10(dppbz), molecular structure of both the isomers have been determined by X-ray crystallography. The kinetics for the ligand isomerization has been investigated by UV-vis …
Date: August 2007
Creator: Kandala, Srikanth
System: The UNT Digital Library