Self‐Assembly of High‐Nuclearity Copper Cages: Tricorne Cu21 and Saddlelike Cyclic Cu16

Copper clusters: Two high‐nuclearity copper cages, tricorne Cu21 and saddlelike cyclic Cu16 (see pictures), were synthesized. Magnetic studies and Monte Carlo calculations were also performed to show the overall antiferromagnetic properties of the two compounds. magnified image Reaction of cupric salts with H2Rppz (R=H, Me; H2ppz=3‐(2‐hydroxyphenyl)pyrazole; H2Meppz=3‐(2‐hydroxy‐5‐methylphenyl)pyrazole) in the presence of sodium azide and triethylamine as bases gave two high‐nuclearity copper cage compounds [HNEt3]2⋅[Cu21(CH3CN)2(H2O)(μ2‐N3)6(μ3‐N3)2(ppz)18]⋅(H2O)3⋅(EtOH)2 (1) and [Cu16(EtOH)2(H2O)2(Meppz)16]⋅9.5 H2O (2), respectively. X‐ray crystallographic studies revealed that molecular skeletons of 1 and 2 are unique tricorne Cu21 and saddlelike cyclic Cu16 aggregates, respectively. The magnetic properties studies showed overall antiferromagnetic interactions in 1 and 2. Quantum Monte Carlo simulations by using a 3‐J model for 1 and a 2‐J model for 2 were performed, which indicated that the magnetic couplings within the triangular copper units in 1 are ferromagnetic and those between other copper ions are antiferromagnetic, whereas in 2 all magnetic couplings between adjacent copper ions are exclusively antiferromagnetic.