Electronic structure of bis(imino)pyridyl ruthenium complexes and reactivity toward alkyne coupling and insertion / Noah L. Wieder.

Format:

Book

Manuscript

Microformat

Thesis/Dissertation

Author/Creator:

Wieder, Noah L.

Contributor:

Berry, Donald H., advisor.

University of Pennsylvania.

Language:

English

Subjects (All):

Penn dissertations--Chemistry.

Chemistry--Penn dissertations.

Local Subjects:

Penn dissertations--Chemistry.

Chemistry--Penn dissertations.

Physical Description:

xi, 296 pages : illustrations ; 29 cm

Production:

2009.

Summary:

This dissertation addresses three principal topics: (1) the insertion of acetylene into the Ru-Si bonds of chloro(organosilyl)ruthenium complexes, (2) the electronic structure, reactivity, and solution behavior of dimeric, formally ruthenium(I) hydride and ruthenium(0) complexes, and (3) the reactivity of alkynes with low-valent ruthenium complexes bearing bis(imino)pyridyl, [N3] ligands.

Acetylene inserts into the Ru-Si bond of ruthenium silyl chloride complexes [N3]RuCl(SiMe2Cl) and [N3]RuCl(SiMeCl 2) to give beta-silylvinyl complexes. A kinetic distribution of ( Z)- and (E)-beta-silylvinyl products is formed initially upon reaction of acetylene with [N3]RuCl(SiMe2Cl). The thermodynamic (E)-silylvinyl product is formed by both a "fast" process involving either direct anti insertion or rapid Z/E isomerization from an (unobserved) intermediate form of a (Z)-beta-silylvinyl complex and a "slow" isomerization of the observed kinetic isomer. Experimental and computational evidence indicates that C=C bond rotation via a zwitterionic transition state with Ru=C character is an accessible pathway for Z to E isomerization of the beta-silylvinyl complexes.

Dimeric, formally Ru(0) complexes {[N3]Ru}2(mu-eta 1:eta1-N2) react with H2 to generate the formally Ru(I) hydride complexes {[N3]Ru(H)} 2(mu-eta1:eta1-N2). Calculated and experimental ligand metrical parameters for both the Ru(0) and Ru(I) complexes, as well as DFT calculations, are consistent with one-electron reduction of the bis(imino)pyridine ligand. The resultant metalloradical for the formally Ru(0) dimers may in part explain the propensity these complexes to react with H2 to add only a single H-atom to each metal center. Crossover experiments demonstrate that dimeric Ru(I) and Ru(0) split into monomers and recombine, and confirm that the Ru(0) complexes remain dimeric in solution and that facile hydride transfer occurs between Ru(0) and Ru(I) hydride monomers.

The reaction of the low-valent complex [kappa2-N 3]Ru(eta6-MeC6H5) with acetylene generates the formally zerovalent ruthenium acetylene complex [N3]Ru(C 2H2), which catalyzes cyclotrimerization of acetylene to benzene. Spectroscopic and structural data for [N3]Ru(C2H 2) are consistent with significant participation of the acetylenic orbitals orthogonal to the RuC2 plane (pi⊥) in metal-ligand bonding. Reaction of [kappa2-N3]Ru(eta 6-MeC6H5) with diphenylacetylene generates the metallacyclopentadiene complex [N3]Ru(1,2,3,4-tetraphenylruthenacyclopenta-2,4-diene), an analogue for cyclotrimerization and linear coupling intermediates.

Notes:

Adviser: Donald H. Berry.

Thesis (Ph.D. in Chemistry) -- University of Pennsylvania, 2009.

Includes bibliographical references.

Local Notes:

University Microfilms order no.: 3363686.