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

1,2-Dihydro-1,2-azaborines (1c, 1d, and 1e) have been prepared by the reaction of the corresponding 2,3-dihydro-1H-1,2-azaborol-3-yllithium reagents (1c, 1d, and 1e). The reaction of 1e with Py₃Mo(CO)₃ and BF₃·OEt₂ affords Mo(CO)₃ complex 5e, while the reaction of 1c with Cr(CH₃CN)₃(CO)₃ affords Cr(CO)₃ complex 6c. X-ray structures of 5e and 6c show that the metals are η⁶-bound to the 1,2-dihydro-1,2-azaborine rings.