Synthesis and Coordination Chemistry of Azulene- and Ferrocene-Based Isocyanide Ligands

Abstract

Nonbenzenoid aromatic isocyanides feature attractive structural and electronic properties for the potential design of optoelectronic devices. Prior to the work of Barybin and coworkers, examples of nonbenzenoid isocyanides were limited to isocyanoferrocene and 1,1'-diisocyanoferrocene. This thesis describes the design of nonbenzenoid isocyanides featuring ferrocene and/or azulene moieties. The first nonbenzenoid aromatic isocyanide featuring both azulene and ferrocene in one molecule is described. Electrochemical results indicate stable redox activity leading to the potential use in the design of redox-addressable materials. A new bis-iridium complex of 1,1'-diisocyanoferrocene was synthesized and showed the possible existence of two isomeric forms when in solution. Redox properties indicate reversibility which is likely iron-based. Preliminary crystallographic data for this complex features a symmetrical structure with C-N-C angles of approximately 176°. A synthetic pathway for the formation of 2,2'-diisocyano-6,6'-biazulenylacetylene π-linker is documented. This diisocyanide exhibits a relatively stable stepwise two-electron reduction process on the electrochemical time scale indicating the likelihood of a closed shell dianion. Coordination chemistry of the mono and dinuclear tungsten diisocyanide complexes illustrates evidence for a metal-to-bridge charge-transfer. A self assembled monolayer of the ligand coordinated to Au(111) indicates an upright orientation when on the surface. Synthesis of a tetranuclear(I) gold rectangle featuring the 2,2'-diisocyano-6,6'-biazulenyl linker is presented and its interesting luminescent properties will be compared to relevant complexes. A crystallographically defined half gold ring featuring the 2-isocyanoazulenyl moiety exhibits an aurophilic interaction between two Au(I) centers. An optimized regioselective amination of 2,2'-biazuene is presented in good yield. This ligand undergoes a stepwise, reversible two-electron reduction according to an electrochemical study . This ligand acts as a precursor to the targeted 6-isocyano-2,2'-biazulene. The formation of a self assembled monolayer featuring 6-isocyano-2,2'-biazulene coordinated in an upright fashion on a Au(111) surface is mentioned. The first accessible planar-chiral isocyanide ligand is presented in high enantiomerically purity. This ligand exhibits robust redox activity upon coordination on the electrochemical time scale. Results from the electrochemical studies in addition to the other spectroscopic evidence will be presented.