[1]Ferrocenophanes, [1]Chromarenophanes, and [1]Vanadarenophanes with Aluminium and Gallium in Bridging Positions

Aluminum- and gallium-bridged [1]ferrocenophanes (4a, 4b), [1]chromarenophanes (5a, 5b), and
[1]vanadarenophanes (6a, 6b) were synthesized from the respective dilithiated sandwich compounds with
element dichlorides (Me2Ntsi)ECl2 [E = Al, Ga; Me2Ntsi = C(SiMe3)2(SiMe2NMe2)] in moderate to
high isolated yields (54−97%). The new intramolecularly stabilized aluminum compound (Me2NCH2tsi)AlCl2 (2a) was synthesized, but was proven to be unreactive with respect to [Fe(LiC5H4)2]·2/3TMEDA.
The diamagnetic species 2a, 4a, 4b, 5a, and 5b were characterized by NMR spectroscopy (1H, 13C,
27Al), CHN elemental analysis, and mass spectrometry, whereas the paramagnetic compounds 6a and 6b
were characterized by IR spectroscopy, CHN elemental analysis, and mass spectrometry. In addition, the
molecular structures of compounds 2a, 4a, 4b, 5a, 5b, 6a, and 6b were determined by single-crystal
X-ray analysis. All [1]cyclophanes are strained species, as revealed by the following tilt angles α [deg]: 
14.33(14) (4a), 15.83(19) (4b), 11.81(9) (5a), 13.24(13) (5b), 14.65(14) (6a), and 15.63(14) (6b).