9,10-Dimetallatriptycenes of Group 14: A novel synthetic approach from ortho-phenylenemagnesium

9,10-Dimetallatriptycenes of Group 14 are readily accessable by a novel synthetic approach: reaction of ortho-phenylenemagnesium (1) with RMCl(3) afforded 9,10-dimethyl-9,10-dimetallatriptycenes (3; M = Si, Ge, Sn) or 9,10-dimethyl-9-germa-10-stannatriptycene (11). The reaction can even be tuned to afford unsymmetrically substituted triptycenes such as 9-methyl-10-phenyl-9,10-digermatriptycene (8); in some of these reactions, 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) by an X-ray crystal structure determination.