UC San Diego

In coordination chemistry, sterically encumbering ligands are often used to control the coordination number, geometry, and electronic structure of transition-metal complexes. The m-terphenyl ligand scaffold is particularly effective in isolating reactive, low-coordinate metal complexes due to its sterically encumbering nature. In past years, we have employed monotopic m-terphenyl isocyanide ligands to isolate low coordinate, highly reactive organometallic complexes. The isolation of these species is possible not only due to the steric pressure of the m-terphenyl backbone, but also due to the synergistic bonding occurring between electron-rich metal and isocyanide ligand molecular orbitals. Indeed, isocyanides are isolobal to carbon monoxide (CO), and both ligands function as both σ-donors and π-acceptors with strong π-backbonding interactions. However, unlike CO, isocyanide ligands can be functionalized, allowing for the formation of multitopic m-terphenyl isocyanide ligands. By capitalizing on this tunability, we reported the synthesis of multitopic m-terphenyl isocyanide ligands for the formation of isocyanide coordination networks (ISOCNs). While isocyanide ligands have been studied extensively in organometallic chemistry, the study of isocyanide ligands in nano- and materials science remains underdeveloped. This dissertation will be split into two parts, where chapters 1 through 4 will discuss the history of low-valent metal-organic frameworks (MOFs) and the impact the multitopic m-terphenyl isocyanide ligands have in the generation of new low-valent materials. In addition, while the isolation of novel m-terphenyl-based ISOCNs will be discussed, their reactivity will also be detailed. In the second portion of this dissertation, collaborative work with University of California, San Diego’s department of nanoengineering will be highlighted. The use of monotopic m-terphenyl isocyanide ligands as capping reagents on nanomaterial surfaces will be discussed in detail, as well as the synthesis and isolation of new functionalized ligand scaffolds to characterize their binding on gold (Au) and silver (Ag) surfaces.