Synthesis of Alkynyl-Substituted 9,10-Dimetallatriptycenes of Group 14 and Their Application in the Preparation of a Novel Class of Organometallic Oligomers

The preparation of
((trimethylsilyl)ethynyl)germanium trichloride (4)
allowed the synthesis
of various alkynyl-substituted 9,10-dimetallatriptycenes via a
simple one-pot synthetic
procedure. For example, reaction of 4 with
o-phenylenemagnesium (1) gave access to
9,10-(RC⋮C)2-9,10-digermatriptycenes (5, R
= SiMe3; 6, R = H), while reaction of
4 with tris(o-(chloromagnesio)phenyl)phenylgermane
(2a) furnished
9-(RC⋮C)-10-phenyl-9,10-digermatriptycenes (7, R = SiMe3; 8, R
= H). The synthetic potential of these compounds in
the
preparation of rigid organometallic oligomers with conjugated spacers
was demonstrated
by the oxidative coupling of 8, which furnished
1,4-bis(9-(10-phenyl-9,10-digermatriptycyl))buta-1,3-diyne (9), whose X-ray crystal structure was
determined, and the hydrosilylation
of 8 with 10-phenyl-10-germa-9-silatriptycene
(3a), which yielded
trans-1-(9-(10-phenyl-9,10-digermatriptycyl))-2-(9-(10-phenyl-9-sila-10-germatriptycyl))ethene
(10).