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).