A bis-calix[4]arene-supported [CuII16] cage.

Reaction of 2,2'-bis- p - t Bu-calix[4]arene (H 8 L) with Cu(NO 3 ) 2 ·3H 2 O and N -methyldiethanolamine (Me-deaH 2 ) in a basic dmf/MeOH mixture affords [CuII16(L) 2 (Me-dea) 4 (μ 4 -NO 3 ) 2 (μ-OH) 4 (dmf) 3.5 (MeOH) 0.5 (H 2 O) 2 ](H 6 L)·16dmf·4H 2 O (4), following slow evaporation of the mother liquor. The central core of the metallic skeleton describes a tetracapped square prism, [Cu 12 ], in which the four capping metal ions are the Cu II ions housed in the calix[4]arene polyphenolic pockets. The [CuII8] square prism is held together "internally" by a combination of hydroxide and nitrate anions, with the N -methyldiethanolamine co-ligands forming dimeric [CuII2] units which edge-cap above and below the upper and lower square faces of the prism. Charge balance is maintained through the presence of one doubly deprotonated H 6 L 2- ligand per [Cu 16 ] cluster. Magnetic susceptibility measurements reveal the predominance of strong antiferromagnetic exchange interactions and an S = 1 ground state, while EPR is consistent with a large zero-field splitting.