Date of Award
Fall 12-6-2019
Track
Chemistry
Degree Type
Thesis
Degree Name
Master of Science in Chemical Sciences (MSCB)
Department
Chemistry
Committee Chair/First Advisor
Michael Stollenz
Committee Member
Mark Mitchell
Committee Member
Daniela Tapu
Abstract
A new series of hexadentate flexible bis(amidine) ligands (L1–6H2) and the multinuclear coinage metal complexes 1–5 of L4H2 were synthesized and characterized. The synthesis of L1–6H2 followed a 3-step protocol: first, the bis(amide) precursor is formed by reacting ethylene diamine with pivaloyl chloride; second, the bis(amide) is chlorinated with PCl5 to produce the corresponding bis(imidoyl chloride); finally, the bis(imidoyl chloride) is reacted with the primary arylamine (L1–6H2 yields: 62, 54, 56, 61, 63, and 58%). L2–6H2 were found to exhibit fluorescence when reacted with n-BuLi, NaHMDS, and KHMDS.
The coordination behavior of L4H2 towards CuCl, [(Me2S)AuCl], AgCl, and AgNO3, a series of Group 11 metal precursors, has been investigated. This has resulted in bimetallic-dichloro complexes [L4H2(AuCl)2] (1) and [L4H2(CuCl)2] (2) (1: 84% and 2: 95%) and the coordination polymer [L4H2(py)2(AgCl)3]n (3) (3: 52%). The reactivity of the M–Cl was investigated by reacting 1 with MesMgBr to generate the organometallic complex [L4H2(AuMes)2] (5) (5: 80%).
X-ray crystallography revealed that complexes 1 and 2 exhibit linear coordination at the metal centers while complex 3 shows both tetrahedral and trigonal planar coordination spheres at the Ag+ ions. Complex 5 retains the linear coordination of the Au+ centers. Additionally, complexes 1–3 also exhibit unique NH···Cl–M–N' hydrogen bridges that are generated by formal insertion of the M–Cl fragments into the intramolecular NH···N' hydrogen bonds of L4H2. These hydrogen bonds can be observed in the solid state and 1H NMR spectroscopy. Accompanying low-temperature VT-NMR studies of 1 and 2 indicate that the NH···Cl–M–N' hydrogen bonds are retained in solution. The free energies of activation of the hydrogen bonds/molecular motion (1, 2, and 5) were calculated: 1: 12.9 kcal/mol, 2: 11.1 kcal/mol, 5: 13.0 kcal/mol.
ABSTRACT
A new series of hexadentate flexible bis(amidine) ligands (L1–6H2) and the multinuclear coinage metal complexes 1–5 of L4H2 were synthesized and characterized. The synthesis of L1–6H2 followed a 3-step protocol: first, the bis(amide) precursor is formed by reacting ethylene diamine with pivaloyl chloride; second, the bis(amide) is chlorinated with PCl5 to produce the corresponding bis(imidoyl chloride); finally, the bis(imidoyl chloride) is reacted with the primary arylamine (L1–6H2 yields: 62, 54, 56, 61, 63, and 58%). L2–6H2 were found to exhibit fluorescence when reacted with n-BuLi, NaHMDS, and KHMDS.
The coordination behavior of L4H2 towards CuCl, [(Me2S)AuCl], AgCl, and AgNO3, a series of Group 11 metal precursors, has been investigated. This has resulted in bimetallic-dichloro complexes [L4H2(AuCl)2] (1) and [L4H2(CuCl)2] (2) (1: 84% and 2: 95%) and the coordination polymer [L4H2(py)2(AgCl)3]n (3) (3: 52%). The reactivity of the M–Cl was investigated by reacting 1 with MesMgBr to generate the organometallic complex [L4H2(AuMes)2] (5) (5: 80%).
X-ray crystallography revealed that complexes 1 and 2 exhibit linear coordination at the metal centers while complex 3 shows both tetrahedral and trigonal planar coordination spheres at the Ag+ ions. Complex 5 retains the linear coordination of the Au+ centers. Additionally, complexes 1–3 also exhibit unique NH···Cl–M–N' hydrogen bridges that are generated by formal insertion of the M–Cl fragments into the intramolecular NH···N' hydrogen bonds of L4H2. These hydrogen bonds can be observed in the solid state and 1H NMR spectroscopy. Accompanying low-temperature VT-NMR studies of 1 and 2 indicate that the NH···Cl–M–N' hydrogen bonds are retained in solution. The free energies of activation of the hydrogen bonds/molecular motion (1, 2, and 5) were calculated: 1: 12.9 kcal/mol, 2: 11.1 kcal/mol, 5: 13.0 kcal/mol.