Stereochemical Consequences of a Parity Restriction on Dynamic Gearing in Tris(9-triptycyl)germanium Chloride and Tris(9-triptycyl)cyclopropenium Perchlorate.

Crystal and molecular structures of tris(9-triptycyl)germanium chloride (1) and tris(9-triptycyl)cyclopropenium (2) perchlorate were determined. Crystals of 1 are trigonal, space group R3c (No. 161), with a=b=13.090 (3) A, c=43.58 (1) A, Z=6. Crystals of 2 perchlorate are hexagonal, space group P6 3 /m (No. 176), with a=b=15.145 (5) A, c=13.617 (4) A, Z=2. Both 1 and 2 are located on crystallographic 3-fold rotation axes, with site symmetries C 3 for 1 and C 3h for 2. The same symmetries are maintained in solution at room temperature on the NMR time scale