Synthesis And Heteroallene Reactivity Of Bis(aldimino)pyridine Nickel Complexes In Four Different Oxidation States

SYNTHESIS AND HETEROALLENE REACTIVITY OF BIS(ALDIMINO)PYRIDINE NICKEL COMPLEXESIN FOUR DIFFERENT OXIDATION STATESbyBLAKE R. REED August 2016Advisor: Dr. Stanislav Groysman Major: ChemistryDegree: Doctor of PhilosophyA series of redox non-innocent bis(aldimino)pyridine ligands were synthesized. Thesewere then reacted with nickel(II) salts to form Ni[NNN]X2 complexes. Cyclic voltammograms ofthese nickel(II) complexes suggest that more reduced states can be achieved. Reduction of these nickel(II) complexes lead to distorted square planar complexes with the halide bent ~20° out of the plane. EPR suggests that spin density is located on the metal as g-values of >2.01were obtained. This differs from previously reported analogous bis(ketimino)pyridinecomplexes, which show a ligand-based radical and nickel(II). DFT confirms that as the Npyr-Ni-Xangle decreases, spin density on the nickel increases. Because of the imino proton as opposedto the imino methyl group, the halide can distort out of the plane and put the spin density onthe nickel. Reaction with PhSSPh leads to the formation of (Ni(SPh)2)11. This is the first exampleof nickel(I) reductively splitting PhSSPh to form this product. Reaction with CS2 results in freeligand, suggesting that CS2 replaces [NNN]. No reactivity with CO2 was observed.[NNN] was reacted with Ni(COD)2. [NNN] a formed a mixture of Ni[NNN](COD) andNi[NNN]2. [NNN] b forms only Ni[NNN]2. In both cases, [NNN] ligand binds in a bidentate fashion