Organometallic Complexes of Bulky, Optically Active, <i>C</i>₃‑Symmetric Tris(4<i>S</i>‑isopropyl-5,5-dimethyl-2-oxazolinyl)phenylborate (To^P*)

A bulky, optically active monoanionic scorpionate ligand, tris­(4<i>S</i>-isopropyl-5,5-dimethyl-2-oxazolinyl)­phenylborate (To^P*), is synthesized from the naturally occurring amino acid l-valine as its lithium salt, Li­[To^P*] (<b>1</b>). That compound is readily converted to the thallium complex Tl­[To^P*] (<b>2</b>) and to the acid derivative H­[To^P*] (<b>3</b>). Group 7 tricarbonyl complexes To^P*M­(CO)₃ (M = Mn (<b>4</b>), Re (<b>5</b>)) are synthesized by the reaction of MBr­(CO)₅ and Li­[To^P*] and are crystallographically characterized. The ν_CO bands in their infrared spectra indicate that π back-donation in the rhenium compounds is greater with To^P* than with non-methylated tris­(4<i>S</i>-isopropyl-2-oxazolinyl)­phenylborate (To^P). The reaction of H­[To^P*] and ZnEt₂ gives To^P*ZnEt (<b>6</b>), while To^P*ZnCl (<b>7</b>) is synthesized from Li­[To^P*] and ZnCl₂. The reaction of To^P*ZnCl and KO<i>t</i>Bu followed by addition of PhSiH₃ provides the zinc hydride complex To^P*ZnH (<b>8</b>). Compound <b>8</b> is the first example of a crystallographically characterized optically active zinc hydride. We tested its catalytic reactivity in the cross-dehydrocoupling of silanes and alcohols, which provided Si-chiral silanes with moderate enantioselectivity