Kim, Jisook; Potts, Gretchen
University of Tennessee at Chattanooga
Place of Publication
Mixed coordination sphere cobalt(III) complexes containing a chiral bidentate amine ligand and an organic carbocyclic ligand have been prepared and characterized. The integration of this mixed ligand environment involving an organometallic and Werner-type ligand along with the earth abundant metal in a high oxidation state has the potential for interesting reactivity. Complexes of the type [Co(CpR)(X-DPEN)(I)](I), where CpR = cyclopentadienyl (Cp, R = H) or pentamethylcyclopentadienyl (Cp*, R = Me) and X = meso-1,2-, 1R,2R-, and 1S,2S-, have been prepared by ligand substitution from [Co(CpR)(I)2(CO)] with 1,2-diphenyletheylenediamine (DPEN). The outer sphere iodide is readily exchangeable with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBArF) or cesium acetate (CsOAc), and both iodides can be exchanged with silver(I) acetate (AgOAc). The latter reactions with AgOAc results in either [Co(CpR)(X-DPEN)(OH2)](OAc)2 or [Co(CpR)(X-DPEN)(OAc)](OAc) depending on the solvent profile, and partial iodide removal to produce [Co(Cp*)(1S,2S-DPEN)(OAc)](I) in the presence of CsOAc. The complexes are isolated as diamagnetic black, dark purple, or, in the case of acetate complexes, pink solids and characterized by 1H-NMR, 13C-NMR and UV-vis spectroscopy as well as either elemental analysis or mass spectrometry. Four complexes, [Co(Cp)(1R,2R-DPEN)(I)](I) (1), [Co(Cp)(1S,2S-DPEN)(I)](BArF) (2a), [Co(Cp*)(1S,2S-DPEN)(I)](I) (4), and [Co(Cp*)(1S,2S-DPEN)(OAc)](I) (13) have been characterized by single-crystal X-ray diffraction. The preparation, characterization, and initial reactivity of these complexes as potential catalysts for aqueous hydrogen transfer as well as the extension to the substituted chiral amine (R,R)-N-(2-amino-1,2-diphenylethyl)-p-toluenesulfonamide (Ts-DPEN) will be discussed.
UTC Chemistry & Physics Department, UTC Honors College, Dr. John Lee, Dr. Jisook Kim, Dr. Gretchen Potts, Dr. Jared Pienkos, Connor Frye, Trevor Paratore, Chelsey Mertens, Cintly Guzman, Kevin Lee, Olivia Gregerson, Mary Nie, Grote Chemistry Fund, SEARCH Grant, Westbrook Scholarship.
B. S.; An honors thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Bachelor of Science.
Cobalt compounds -- Synthesis; Ligands
Do Carmo, Luccas C., "Preparation of organometallic cobalt(III) complexes containing bidentate chiral amine ligands as potential transfer hydrogenation catalysts" (2019). Honors Theses.