A Co16 cluster and a 1-D Mn chain complex supported by benzohydroxamic acid

Abstract

The syntheses, crystal structures and magnetic properties are described for a {Co₁₆} cluster [Co^II₁₆O(OH)₂(bha)₁₂(PhCO₂)₄(Phen)₂(MeOH)₄]·2MeOH (1) and a 1-D Mn^II chain complex [Mn(Hbha)₂]_n·(2MeOH)_n (2) (H₂bha = benzohydroxamic acid; Phen = 1,10-phenanthroline). The 1 : 1 : 0.5 reaction of Co(O₂CMe)₂·4H₂O, H₂bha and 1,10-phenanthroline in MeOH at 100 °C under autogenous pressure gave cluster 1. Complex 2 was obtained from the 1 : 1 reaction mixture of Mn(O₂CMe)₂·2H₂O and H₂bha in MeOH under solvothermal conditions. The {Co₁₆} cluster can be thought as a face-centered cube with two wings. The H₂bha ligands show hydroximic form in 1 and exhibit hydroxamic mode in 2. The hydroximate ligands in 1 display three distinct binding modes, one of which is novel. Variable-temperature solid-state dc magnetic susceptibility studies have been performed in the 2.0–300 K range for complexes 1 and 2. Antiferromagnetic M^II⋯M^II exchange interactions were found for both 1 and 2. This work also demonstrates that solvothermal method is a potential synthetic approach for the design and growth of high nuclearity clusters or chain complexes of the H₂bha ligand.