Treatment of cryptand L-1 with Cu(II) generates a H3O2--bridged dicopper(II) cryptate, 2, where the guest anion has responded to steric constraint by a significant shortening of the 0-0 distance to 2.325(9) angstrom; computational optimization at the B3LYP/6-31(d) level suggests that the bridging O-H center dot center dot center dot O H-bond is bent (approximate to 157 degrees) but that the barrier to interchange of the bridging H atom is low (< 4 W mol(-1)). This cryptate, rather than the [Cu(2)L(1)mu CN](3+) species recently claimed to derive from cleavage of the C-C bond of the solvent, is the product of acetonitrile recrystallization of the initially formed reaction product, 1.