Andreas Kunze, Rolf Gleiter and Frank Rominger
X-Ray structure analysis of the diprotonated cage of 3 and its silver(I) and copper(I) complexes reveals in all three cases the in,in conformation and a significant shortening of the intrabridgehead distance from 5.05 Å in 3 to 4.85 Å for 3·2H+, 4.23 Å for 3·Cu+ and 4.61 Å for 3·Ag+.