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.