Supramolecules with dimolybdenum or chiral dirhodium units

Abstract

This dissertation concerns the syntheses and characterization of supramolecules with quadruply bonded Mo2 4+ units, Mo2(DAniF)3 + (DAniF = N,N'-di-p-anisylformamidinate) or cis- Mo2(DAniF)2 2+, and chiral organometallic Rh2 4+ units, including racemic cis-Rh2(C6H4PPh2)2 2+ and pure enantiomers of cis-Rh2(C6H4PPh2)2 2+. Molecular pairs of dimolybdenum units in which Mo2(DAniF)3 + units are linked by cyclic diamidate anions or dioxolene anions have been investigated. Linkers impact the electronic communication between the dimetal units in various ways. The symmetry and the energy of the frontier orbitals of the linker are among the factors which influence significantly the properties of the molecular pairs. Nature has provided us a great opportunity to study quantitatively the equilibrium between neutral supramolecules with cis-Mo2(DAniF)2 2+ units. Studies of the concentrationdependent and temperature-dependent equilibria between a molecular triangle and square as well as a molecular loop and triangle using 1H and 19F NMR spectra provide quantitative values for the thermodynamic equilibrium constant K, as well as ∆Hº, and ∆Sº for the equilibria. The synthesis and characterization supramolecular compounds containing chiral cis- Rh2(C6H4PPh2)2 2+ units, including three racemic triangles and pure enantiomers of three triangles, a carceplex with T symmetry and two loops are also presented.