Host-Guest Interaction of 12-MC-4, 15-MC-5, and Fused 12-MC-4 Metallacrowns with Mononuclear and Binuclear Carboxylato Complexes: Structure and Magnetic Behavior

Interaction of manganese with salicylhydroxamic ligands leads to the formation of the 12‐membered metallacrown [MnII2(2,4‐DP)2(HCOO)2][12‐MC Mn IIIN(shi)‐4](py)6 (2) (H‐2,4‐DP =2‐(2,4‐dichlorophenoxy)propionic acid) and the 15‐membered metallacrown [MnII(2,4‐D)2][15‐MC Mn IIIN(shi)‐5](py)6 (1) (H‐2,4‐D = 2,4‐dichlorophenoxyacetic acid). The crystal structure analysis shows that mononuclear and dinuclear alkanoato complexes are accommodated in the cavity of the metallacrown ring. The magnetic behaviour of 1 and 2 and the magnetic behaviour of the fused 12‐membered metallacrown [NiII(mcpa)]2[12‐MC Ni IIN(shi) 2(pko) 2‐4][12‐MC Ni IIN(shi) 3(pko)‐4](CH3OH)3(H2O) (3) (Hmcpa=2‐methyl‐4‐chlorophenoxyacetic acid) have shown that the zero field and/or the population of many energy levels at low temperatures is the reason for the divergence of the susceptibility data at high fields. For compound 3, the ground state is S=0, with S=1 and S=2 low‐lying excited states. This leads to a non‐Brillouin behaviour of the magnetisation, since the ground state is very close to the excited states. Interaction of manganese or nickel with hydroximato ligands leads to the formation of 12‐membered metallacrown [12‐MC Mn IIIN(shi)‐4], 15‐membered metallacrown [15‐MC Mn IIIN(shi)‐5], or fused 12‐membered metallacrown [12‐MC Ni IIN(shi) 2(pko) 2‐4][12‐MC Ni IIN(shi) 3(pko)‐4] complexes. Mononuclear and dinuclear manganese (illustrated here) or nickel alkanoato complexes are accommodated in the cavity of the metallacrown ring.