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 cobalt 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) or pentamethylcyclopentadienyl (Cp*) 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 tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBArF), and both iodides can be exchanged with silver(I) or cesium acetate. The latter reaction with acetate results in either [Co(CpR)(X-DPEN)(OH2)](OAc)2, [Co(CpR)(X-DPEN)(OAc)](OAc), or [Co(Cp*)(1S,2S-DPEN)(OAc)](I) depending on the solvent and the source of acetate (Ag or Cs). 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), [Co(Cp)(1S,2S-DPEN)(I)](BArF), [Co(Cp*)(1S,2S-DPEN)(I)](I), and [Co(Cp*)(1S,2S-DPEN)(OAc)](I) 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 presented.

Preparation of organometallic cobalt(III) complexes containing bidentate chiral amine ligands as potential transfer hydrogenation catalysts

2019 Spring National Meeting

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