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 1H and 19F 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)° (cf. the corresponding angle of 117.1(1)° 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) Å (cf. 1.711(1) and 1.7113(1) Å 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.