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 format ion of the 12-membered metallacrown [Mn-2(II)(2A-DP)(2)(HCOO)(2)]-[12-MCMnI IIN(shi)-4](ply)(6) (2) (H-2,4-DP =2-(2,4-dichlorophenoxy)propionic acid) a nd the 15-membered metallacrown [Mn-II(2,4-D)(2)][15-MCMnIIIN(shi)-5](py)(6 ) (1) (H-2,4-D = 2,4-dichlorophenoxyacetic acid). The crystal structure ana lysis shows that mononuclear and dinuclear alkanoato complexes are accommod ated in the cavity of the metallacrown ring. The magnetic behaviour of 1 an d 2 and the magnetic behaviour of the fused 12-membered metallacrown [Ni-II (mcpa)](2-)[12 -MCNiIIN(shi)2(pko)2-4] [12-MCNiII(shi)3(pko)-4]-(CH3OH)(3)( H2O) (3) (Hmcpa=2-methyl-4-chlorophenoxyacetic acid) have shown that the ze ro 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. F or compound 3, the ground state is S = 0, with S = 1 and S = 2 low-lying ex cited states. This leads to a non-Brillouin behaviour of the magnetisation, since the ground state is very close to the excited states.