Novel Linear Trinuclear Cu II Compound with Trapped Chiral Hemiaminal Ligand: Magnetostructural Study

A new trinuclear Cu II compound {[Cu 3 (HL′) 2 (H 2 O) 2 ](ClO 4 ) 4 }·(H 2 O) 4 ( 1 ) was obtained and presented a trapped chiral hemiaminal (HL 2′ = [(5-amino-4H-1,2,4-triazol-3-yl)amino](1H-imidazol-4-yl)methanol)). Compound 1 shows an almost flat cationic structure [Cu 3 (HL′) 2 (H 2 O) 2 ] 4+ with a Cu 3 linear core reached by the double Cu-OR/NN-Cu triazole/alkoxo bridge of the hemiaminal molecule. The Cu II spin carriers are antiferromagnetically coupled, presenting a spin doublet ground state (S = 1/2) with a magnetic coupling constant of −179 cm −1 . Moreover, DTF calculations show that the planarity of the compound permits a sigma-type overlapping between the unpaired electrons of the spin carriers and the p -type orbitals of the coordinated N and O atoms producing an electronic delocalization through the bridging ligand responsible for the strong antiferromagnetic interactions observed experimentally.