Tetranuclear mixed-valence Co(II/III) and binuclear Ni(II) complexes incorporating hydroxyl-rich ligand: Syntheses, structures and magnetic properties

Three complexes of composition [Co2IICo2III(H2hbhpd)2(H4hbhpd)2(H2O)2]Cl2(CH3OH)4 (1), [Co2IICo2III(H2hbhpd)2(H4hbhpd)2(H2O)2](NO3)2(CH3OH)4 (2) and [Ni2(H4hbhpd)2(NO3)](NO3)(CH3OH)1.5 (3) (H5hbhpd = 2-(2-hydroxy-benzylamino)-2-hydroxymethyl-propane-1,3-diol) have been synthesized and their structures have been characterized. Complexes 1 and 2 are mixed-valence cobalt clusters and display face-sharing monovacant dicubane structures. In the complexes 1 and 2, one of the three alkyl hydroxyl groups of H5hbhpd ligand is deprotonated instead of deprotonation of phenyl hydroxyl group; thus monoanionic H4hbhpd− ligand displays novel η3, η1, η1, μ3 coordination mode. Complex 3 is binuclear, and the two metal centers of 3 are bridged by two deprotonated phenyl hydroxyl oxygen atoms and iso-orthogonalized by a nitrato group in η1η1-O,O′ coordination fashion. Variable-temperature solid-state dc magnetization studies have been performed in the temperature range 2–300 K for compounds 1 and 3. Antiferromagnetic interactions were determined for 1 and ferromagnetic couplings were found for 3.