Strained and Unstrained Sandwich Compounds: From Small Molecules to Polymers
The synthesis and characterization of aluminum, gallium, and indium dichlorides decorated with the bulky Mamx [Mamx = 2,4-tBu2-6-(Me2NCH2)C6H2] ligand are described. The salt-metathesis reaction of (Mamx)ECl2 (E = Al, Ga) with dilithioferrocene and dilithioruthenocene yielded strained ferrocenophanes (FCPs) and ruthenocenophanes (RCPs), respectively, with aluminum and gallium as bridging elements. Gallaruthenocenophane was isolated from the reaction mixture, while other aluminum- and gallium-bridged FCPs and RCPs spontaneously ring-open polymerized under conditions of their formation reactions and produced metallopolymers. Gallaruthenocenophane was polymerized using Karstedt’s catalyst, which yielded poly(ruthenocenylgallane). Aluminum- and gallium-bridged bis(ferrocenyl) species were prepared by reacting lithioferrocene with respective dichlorides. DFT calculations were performed to study the structure and reactivity of these new metallocenophanes. Particularly, the role of the bulky Mamx ligand and its influence on the high reactivity of these strained sandwich species was investigated. (Mamx)InCl2 was reacted with dilithioferrocene and resulted in indium-bridged FCP, [1.1]FCP and oligomers. However, the reaction of (Mamx)InCl2 with dilithioferrocene, substituted with two isopropyl groups ortho to lithium atoms, resulted in indaferrocenophane selectively. However, this indaferrocenophane could not be isolated as it spontaneously polymerized under conditions of its formation reaction. The synthesis and characterization of aluminum and gallium dichlorides decorated with the slim p-SiMe3Ar′ [p-SiMe3Ar′ =5-Me3Si-2-(Me2NCH2)C6H3] and Mpysm [Mpysm = (2-C5H4N)Me2SiCH2] ligands are described. These dichlorides were utilized to synthesize group-13-bridged [1.1]FCPs and bis(ferrocenyl) species. Bis(ferrocenyl) species with SiMe2- and SiEt2-bridges were described as well. Two similar species, bis(1'-bromoferrocenyl)dialkylsilane (alkyl = Me, Et) were also prepared. The reaction of bis(1'-lithioferrocenyl)dialkylsilane with tin and gallium dichlorides resulted in unsymmetrically bridged [1.1]FCPs as well as poly(ferrocene)s with two different elements as altering bridges. These poly(ferrocene)s consist of a series of linear and cyclic species. Using either crystallization or column chromatography, some species were isolated. The reactions of dilithioferrocene with dialkyltin dichlorides also yielded polymers that contained a mixture of linear and cyclic species. Some species were isolated by column chromatography. These [1.1]FCPs, bis(ferrocenyl) species and other isolated species with heavier group 13 and/or group 14 element bridges contained two or more iron redox centers. The electronic communication between these redox centers were investigated using several electrochemical methods.
DegreeDoctor of Philosophy (Ph.D.)
CommitteeBurgess, Ian; Foley, Stephen; Tse, John
Copyright DateOctober 2012
Metallacyclophane, Metallocenophane, Ferrocenophane, Ruthenocenophane, Aluminum, Gallium, Indium, Silicon, Tin, Ring-Opening Polymerization, Metallopolymer, Macrocycle, Electrochemistry