NNN‐Cobalt(II) Pincer Complexes: Paramagnetic NMR Spectroscopy in Solution and Application as Hydrosilylation Catalysts.

The tridentate, monoanionic bis(oxazolinylmethylidene)‐isoindolate pincer ligand was utilized for the synthesis of various cobalt(II) high‐spin complexes. Employing standard complexation procedures, the corresponding acetato and chlorido complexes were isolated in good yields and thoroughly characterized in the solid‐state and in solution. In particular, a density functional theory (DFT) supported paramagnetic NMR analysis revealed a strong correlation between observed 13C NMR shifts and calculated spin‐density distributions, allowing for an unambiguous signal assignment in all 1H and 13C NMR spectra. An acetato‐bridged trinuclear cobalt species as well as the hexacoordinate "homoleptic" complex [(Rboxmi)2Co] were further identified as side products generated in the complex synthesis. The chlorido complexes were applied as catalysts for the cobalt‐catalyzed hydrosilylation of acetophenone, producing the chiral secondary alcohol with moderate enantioselectivities. [ABSTRACT FROM AUTHOR]