Fig. 3. (a) The structure of one (3a-A) of the three independent complexes present in the crystal of 3a. (b) The crystal structure of 4. Selected bond lengths (Å) and angles (°): 3 Al(a)–N1(a) 1.8809(14), Al(a)–N3(a) 1.8671(15), Al(a)–F30(a) 1.6582(11), Al(a)–C31(a) 1.9993(18), F30(a)–Al(a)–C31(a) 109.68(7), N1(a)–Al(a)–N3(a) 98.85(6). 4 Al–N1 1.885(2), Al–N3 1.890(2), Al–O31 1.7437(19), Al–C39 1.955(3), O31–Al–C39 102.18(11), N1–Al–N3 97.92(9).