Complexes of ligands providing endogenous bridges. Part 6. The X-ray crystal structure and magnetic properties of a hexanuclear copper(II) aggregate bearing µ3-Cu3(OH) cores supported by 4-nitro-2,6-bis[(salicylideneamino)methyl]phenolate ligands

Abstract

The adventitious self-assembly of a hexanuclear copper(II) aggregate [{Cu₃L(OH)(dmf)}₂(µ-Cl)(µ-L)]·2dmf (dmf = dimethylformamide) during the recrystallisation of a dinuclear copper(II) hydroxo-complex derived from 4-nitro-2,6-bis[(salicylideneamino)methyl)]phenol (H₃L) is reported together with an account of the magnetic properties of the aggregate. The crystal structure of the aggregate consists of two µ₃-Cu₃(OH) cores held by three peripheral bridging ligands and a µ-chloro bridge. The compound crystallises in the triclinic space group P(C_i, no. 2) and has unit-cell dimensions a= 13.288(10), b= 14.678(7), c= 22.591(23)Å, α= 102.96(6), β= 89.07(7), γ= 113.15(5)°, and Z= 2. Antiferromagnetic coupling is observed with J values of –51, –70, and –72 cm^–1 noted for the three dicopper pairings. The complexity of the system however leaves an uncertainty in the interpretation of the magnetic data, illustrating an inherent weakness in the capability of the technique to deal with high-nuclearity clusters.