Synthesis and Characterization of Mono- and Diruthenium Compounds

This thesis will focus on two broad topics: the synthesis and characterization of various diruthenium aryl compounds and of mono- and bis-alkynyl unsymmetric compounds based on Ru(II)(dppm)₂ and Ru(II)(dppe)₂ bridges (dppm = 1,2-bis(diphenylphosphino)methane; dppe = 1,2-bis(diphenylphophino)ethane).

Chapters 1–3 focus on multiply bonded metal–metal compounds, utilizing four different ‘paddlewheel’ motifs (dinuclear ruthenium units that are supported by four bidentate ligands). These highly stable mono- and bis-aryl diruthenium compounds are readily prepared using lithium-halogen exchange reactions. Two different oxidation states have been accessed, Ru₂(II,III) and Ru₂(III,III), through modification of the paddlewheel ligands or coordination of a small, π-accepting ligand at the vacant ruthenium site in Ru₂(ap)₄(Ar) compounds (ap = 2-anilinopyridinate; Ar = aryl). Chapter 1 discusses the modification of the bidentate ligand to yield two unique Ru₂(ap')₄(Ar) series, which both exhibit improved solubility over the previously reported un-modified Ru₂(ap)₄(Ar) series, and the structural, electronic, and optical characterizations of the compounds within these two new Ru₂(II,III) series. Chapter 2 builds upon our lab’s previous studies on electron transfer between the two ruthenium centers in [Ru₂(ap)₄]₂(μ-C≡C)_x compounds and applies this towards synthesizing and characterizing mixed-valency within a Ru₂(III,III) phenylene bridged compound [(NC)Ru₂(ap)₄]₂(μ-1,4-C₆H₄). Chapter 3 highlights the synthesis and characterization of bis-aryl and bis-alkynyl Ru2(III,III) compounds, Ru₂(amtfmp)₄(Y)₂ (Y = -C≡CPh, -Ph), supported with the electron-withdrawing paddlewheel ligand amtfmp (amtfmp = 2-amino-3-(trifluoromethyl)pyridinate). 

Chapters 4 and 5 are focused on the synthesis and characterization of both mono- and bis-alkynyl unsymmetric compounds to study photo-induced electron transfer (PET) processes. Chapter 4 features as an introduction to the synthesis of these Ru(II)(dppm)₂ and Ru(II)(dppe)₂ alkynyl compounds along with some material applications. Chapter 5 discusses the mono- and bis-alkynyl compounds based on Ru(II)(dppm)₂ and Ru(II)(dppe)₂ bridges that utilized a highly electron-withdrawing chromophore ‘acceptor’ ligand, NAP^R (R = isopropyl, mesityl), to generate the B-A (mono-alkynyl) and D-B-A (unsymmetric bis-alkynyl) compounds.