Cerium(IV) alkoxide complexes are of interest due to their recent applications in photocatalysis. While oxidation of C-H bonds by high-valent transition metal alkoxide and hydroxide complexes has been studied extensively, the oxidation chemistry of well-defined mononuclear Ce(IV) alkoxide compounds has not been well explored partly because they undergo facile ligand redistribution and oligomerization in solution. In this thesis, a convenient route to redox-active Ce(IV) alkoxide complexes [Ce(L_OEt)₂(OR)₂] (L_OEt^- = Kläui tripodal ligand [Co(η⁵-C₅H₅){P(O)(OEt)₂}₃]^-) involving the chloride abstraction of [Ce(L_OEt)₂Cl₂] with Ag₂O in ROH [(R = ⁱPr (2.1a), Et (2.1b), Me (2.1c)] has been developed. The nucleophilic and redox reactivity of 2.1a has been investigated. 2.1a is capable of...[ Read more ]

Cerium(IV) alkoxide complexes are of interest due to their recent applications in photocatalysis. While oxidation of C-H bonds by high-valent transition metal alkoxide and hydroxide complexes has been studied extensively, the oxidation chemistry of well-defined mononuclear Ce(IV) alkoxide compounds has not been well explored partly because they undergo facile ligand redistribution and oligomerization in solution. In this thesis, a convenient route to redox-active Ce(IV) alkoxide complexes [Ce(L_OEt)₂(OR)₂] (L_OEt^- = Kläui tripodal ligand [Co(η⁵-C₅H₅){P(O)(OEt)₂}₃]^-) involving the chloride abstraction of [Ce(L_OEt)₂Cl₂] with Ag₂O in ROH [(R = ⁱPr (2.1a), Et (2.1b), Me (2.1c)] has been developed. The nucleophilic and redox reactivity of 2.1a has been investigated. 2.1a is capable of oxidizing 2,4,6-tri-tert-butylphenyl to afford the Ce(III) aryloxide complex [Ce(L_OEt)₂(OC₆H₂^tBu₃-2,4,6)] along with 2,4,6-tri-tert-butylphenoxy radical, possibly via a proton-coupled electron transfer pathway.

Also of interest are lanthanide complexes containing metal-ligand multiple bonds as they have long been considered as inaccessible synthetic targets due to the “core-like” 4f orbitals of lanthanides. Although a handful of Ce terminal oxo and imido complexes have been reported recently, Ce≡N and Ce-N-M complexes remain exclusive. In an attempt to synthesize heterometallic cerium nitrido complexes, we studied the reactions of [Ce(L_OEt)₂Cl₂] with [nBu₄N][M^VI(N)(cat)₂] (cat²⁻= catecholate(2−)) which afforded the catecholate-bridged Ce(III)/M(VI) complexes [(L_OEt)₂Ce^III{(μ-cat)₂M^VI(N)}] (M = Ru, Os), instead of Ce-N-M complexes. Similarly, the catecholate-bridged Ce(III)/M oxo complexes [(L_OEt)₂Ce^III{(μ-cat)₂Re^V(O)}] and [(L_OEt)₂Ce^III(μ-DTBC)₂V(O)] (DTBC^2- = 3,5-di-tert-butylcatecholate(2-)) have been synthesized.

High-oxidation-state iridium complexes have attracted much attention owing to their involvement as reactive intermediates in Ir-catalyzed water oxidation. In this regard, we sought to synthesize high-valent iridium complexes supported by a tetradentate pyridine-carboxamide ligand, bpb^2-. The synthesis, electrochemistry and catalytic activity of Ir(bpb) phosphine complexes have been studied.