Synthesis of 1,2-Dihydro-1,2-azaborines and Their Conversion to Tricarbonyl Chromium and Molybdenum Complexes

1,2-Dihydro-1,2-azaborines (<b>1c</b>, <b>1d</b>, and <b>1e</b>) have been prepared by the reaction of the corresponding 2,3-dihydro-1<i>H</i>-1,2-azaborol-3-yllithium reagents (<b>1c</b>, <b>1d</b>, and <b>1e</b>). The reaction of <b>1e</b> with Py<sub>3</sub>Mo(CO)<sub>3</sub> and BF<sub>3</sub>·OEt<sub>2</sub> affords Mo(CO)<sub>3</sub> complex <b>5e</b>, while the reaction of <b>1c</b> with Cr(CH<sub>3</sub>CN)<sub>3</sub>(CO)<sub>3</sub> affords Cr(CO)<sub>3</sub> complex <b>6c</b>. X-ray structures of <b>5e</b> and <b>6c</b> show that the metals are η<sup>6</sup>-bound to the 1,2-dihydro-1,2-azaborine rings.