9,10-Dimetallatriptycenes of Group 14 are readily accessable by a nove
l synthetic approach: reaction of ortho-phenylenemagnesium (1) with RM
Cl(3) afforded 9,10-dimethyl-9,10-dimetallatriptycenes (3; M = Si, Ge,
Sn) or 9,10-dimethyl-9-germa-10-stannatriptycene (11). The reaction c
an even be tuned to afford unsymmetrically substituted triptycenes suc
h as 9-methyl-10-phenyl-9,10-digermatriptycene (8); in some of these r
eactions, strong indications were obtained for the intermediacy of tri
-Grignard reagents RM(2-C6H4MgCl)(3) (5, 10). The new triptycenes were
characterised by their spectral data and in the case of 3c (M = Sn) b
y an X-ray crystal structure determination.