Asymmetric catalysis is one of the most effective ways to control a target molecule’s stereochemistry. Through the development of a wide variety of chiral transition metal complexes, synthetic chemists are given the tools they need to synthesize the desired enantiomer of numerous compounds. This work focuses on exploiting the non-innocent ligand reactivity of metal bis-dithiolenes with multiple conjugated π systems in order to synthesize chiral ligands. Recent work has shown that platinum bis-dithiolene reacts with dienes stereoselectively to form a racemic mix of C2 -chiral thioether ligands. The present contribution will show approaches to synthesizing chiral dienes and organometallic complexes with potential applications for asymmetric allylic substitution reactions. Dienes with various chiral auxiliaries were reacted with platinum dithiolene and monitored through NMR spectroscopy. Attempts to synthesis palladium bis-dithiolene complexes, not previously seen in the literature were made, and the reaction of α-β unsaturated ketones with metal bis-dithiolenes was explored.

Asymmetric catalysis is one of the most effective ways to control a target molecule’s stereochemistry. Through the development of a wide variety of chiral transition metal complexes, synthetic chemists are given the tools they need to synthesize the desired enantiomer of numerous compounds. This work focuses on exploiting the non-innocent ligand reactivity of metal bis-dithiolenes with multiple conjugated π systems in order to synthesize chiral ligands. Recent work has shown that platinum bis-dithiolene reacts with dienes stereoselectively to form a racemic mix of C2 -chiral thioether ligands. The present contribution will show approaches to synthesizing chiral dienes and organometallic complexes with potential applications for asymmetric allylic substitution reactions. Dienes with various chiral auxiliaries were reacted with platinum dithiolene and monitored through NMR spectroscopy. Attempts to synthesis palladium bis-dithiolene complexes, not previously seen in the literature were made, and the reaction of α-β unsaturated ketones with metal bis-dithiolenes was explored.

The chemistry of late first row transition metals supported by dipyrromethane and dipyrromethene ligands bearing sterically bulky substituents was explored. Transition metal complexes (Mn, Fe, Co, Ni, Zn) of the dipyrromethane ligand 1,9-dimesityl-5,5-dimethyldipyrromethane (dpma) were prepared. Structural and magnetic characterization (SQUID, EPR) of the bis-pyridine adducts \((dpma)Mn(py)_2\), \((dpma)Fe(py)_2\), and \((dpma)Co(py)_2\) showed each tetrahedral divalent ion to be high-spin, while square planar \((dpma)Ni^{II}(py)_2\) and tetrahedral \((dpma)Zn(py)_2\) were shown to be diamagnetic. Electrochemical experiments revealed oxidative events at common potentials independent of metal identity or spin state, consistent with ligand-based oxidation. Dipyrromethene ligand scaffolds were synthesized bearing large aryl \((Ar = 2,4,6-Ph_{3}C_{6}H_{2}, Mes = 2,4,6-Me_{3}C_{6}H_{2})\) or alkyl \((^{t}Bu = CMe_3, Ad = 1-adamantyl)\) flanking groups to afford three new disubstituted ligands \((^{R}dpme, 1, 9-R_2-5-mesityldipyrromethene, R = Ar, Mes, ^{t}Bu, Ad)\). While high-spin \((S=2)\), four-coordinate iron complexes of the type \((^{R}dpme)FeCl(solv)\) were obtained when R was Mes, tBu, or Ad, use of the sterically encumbered aryl-substituted ligand gave a three-coordinate high-spin \((S=2)\) complex \((^{Ar}dpme)FeCl\). Intramolecular C−H amination was discovered in the reaction of organic azides with \((^{Mes}dpme)FeCl(thf)\), though no intermediate was observed by UV/Vis, IR, or \(^{1}H\) VT-NMR experiments. Reaction of \((^{Ad}dpme)FeCl(OEt_2)\) with alkyl azides resulted in the catalytic amination of C–H bonds or aziridination of olefins at room temperature. Reaction of \(p-^{t}BuC_{6}H_{4}N_{3}\) with \((^{Ar}dpme)FeCl\) permitted isolation of a high-spin \((S=2)\) iron complex \((^{Ar}dpme)FeCl(N(p-^{t}BuC_6H_4))\), featuring a terminal imidyl radical antiferromagnetically coupled to high-spin \(Fe^{III}\), as determined by \(^{1}H\) NMR, X-ray crystallography, and \(^{57}Fe\) Mössbauer. A three-coordinate CoI complex \((^{Ar}dpme)Co(py)\) was synthesized and characterized by \(^{1}H\) NMR, SQUID magnetometry, and X-ray crystallography. Reaction of \((^{Ar}dpme)Co(py)\) with \(^{t}BuN_3\) afforded an isolable three-coordinate Co imide complex \((^{Ar}dpme)Co(N^{t}Bu)\) that exhibits spin crossover from a singlet to a quintet. Reaction of \((^{Ar}dpme)Co(py)\) with mesityl azide produces a spectroscopically observed intermediate, consistent with an \(S=1\) terminal imide complex, that converted via benzylic C–H activation into the metallacycloindoline \((^{Ar}dome)Co(\kappa^{2}-NHC_{6}H_{2}-2,4-Me_{2}-6-CH_2)\). / Chemistry and Chemical Biology