Synthesis, structure, and reactivity of mixed-sandwich zirconacarborane methyl complex (η5-C5Me5)[η1:η5-(Me2NCH2CH2)C2B9H10]ZrMe

A neutral mixed-sandwich zirconacarborane methyl complex (eta(5)-Cp*)[eta(1): eta(5)-(Me2NCH2CH2)C2B9H10]Zr(Me) (1) (Cp* = C5Me5) was prepared via methane elimination reaction of 7-Me2N(H)CH2CH2-7,8-C2B9H11 with (eta(5)-Cp*)ZrMe3. It underwent intramolecular CeH activation at 70 degrees C to afford [eta(1): sigma: eta(5-){MeN(CH2)CH2CH2}C2B9H10]Zr(eta(5)-Cp*) (2) and eliminate CH4. This complex reacted with internal alkynes to give the Zr-C sigma bond mono-insertion products, in which both electronic and steric factors played a role in controlling the regioselectivity of the insertion process. In the case of terminal alkynes, both insertion and acid-base reaction products were obtained, dependent upon the substituents. On the other hand, complex 1 reacted with alkyl nitriles at room temperature to give the mono-insertion zirconacarborane imide complexes, whereas high temperature was required to promote the insertion reaction with aryl nitrile, generating a different type of insertion product, zirconacarborane amide. All new complexes were characterized by NMR spectroscopy and elemental analyses. Most of them were further confirmed by single-crystal X-ray analyses. (C) 2016 Elsevier B.V. All rights reserved.