Diarsatriptycene, skeleton

Diaquabis(diimine)metaI(IU) complexes, acid dissociation constants, 37 394-395 cis-Diaqua cobalt complexes, 45 290 Diarsatriptycene, skeleton, 33 33 Diarsenatophosphates, 4 61-62 Diarsine... 

The 1,6-, or bridgehead, carbon atoms in the beautifully symmetric molecule (I) can theoretically be substituted with any elements capable of (roughly) tetrahedral coordination, the most likely candidates being in Groups III, IV, V, and VI of the periodic table (see Fig. 1). The problem of their study is almost entirely one of synthesis, not stability. Although the first member of the series, 1,6-diazatriptycene (II), was apparently synthesized more than 100 years ago, (J) progress has been slow because only the 1,-6-diarsatriptycene skeleton can be built up in a stepwise fashion from stable intermediates (2). Special techniques must be devised for the other triptycenes and thus far, with one exception, only Group V derivatives have been synthesized. 

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