Synthesis, structure, and reactivity of AlMe2(1-Me-CB11F11): An AlMe2+ cation-like species bonded to a superweak anion

Treatment of AlMe3 with [CPh3][1-Me-CB11F11] in toluene produced the dimeric compound [AlMe2(1-Me-CB11F11)](2) in 89% isolated yield. The compound was characterized by H-1 and F-19 NMR spectroscopy and by single crystal X-ray diffraction. The structure consists of a AlMe2+ cation-like species bonded to two F atoms from two 1-Me-CB11F11- superweak anions, forming an AlMe2F2 coordination unit with the unusually large H3C-Al-CH3 angle of 147.6(2)degrees (cf. the corresponding angle of 117.1(1)degrees in the AlMe2F2- anion in [N(n-Bu)(4)][AlMe2F2]). This large angle is due in part to the long Al-F distances of 1.922(3) and 1.928(3) angstrom (cf. 1.711(1) and 1.7113(1) angstrom in [N(n-Bu)(4)][AlMe2F2]), which is why the dimethylaluminum moieties in [AlMe2(1-Me-CB11F11)](2) should possess a considerable degree of positive charge and should be considered as cation-like AlMe2+ species. (C) 2012 Elsevier B.V. All rights reserved.