Molybdenum Tricarbonyl Complexes of 1-Substituted Borepins

Abstract

The reaction of 1-substituted borepins C6H6BX, where X = Me, Ph, and Cl, with Py3Mo(CO)3 and BF3·OEt2 affords the corresponding borepin molybdenum tricarbonyl complexes. Similar reaction of 1-methoxyborepin affords (C6H6BF)Mo(CO)3. The reaction of (C6H6BCl)Mo(CO)3 with appropriate nucleophiles affords the boron-substituted complexes (C6H6BX)Mo(CO)3, where X = H, OCH3, OH, O1/2, N(iPr)2, N(CH2)5, N(c-C6H11)2, and NBnMe. All complexes (C6H6BX)Mo(CO)3 have been compared using 1H NMR, 11B NMR, and 13C NMR spectroscopies. The X-ray structure of (C6H6BN(iPr)2)Mo(CO)3 shows that Mo is η6-coordinated to the ring carbon atoms but not to B. Rates of rotation about the B−N bonds of (C6H6BN(iPr)2)Mo(CO)3 and (C6H6BNBnMe)Mo(CO)3 have been measured using variable-temperature NMR spectroscopy.