Structural re-arrangement in two hexanuclear CuII complexes: from a spin frustrated trigonal prism to a strongly coupled antiferromagnetic soluble ring complex with a porous tubular structure

Abstract

The addition of water to a chloroform solution of the Cu₆ trigonal prism complex [Cu₆(μ₆F)(μ₂OH)(μ₃OCH₃)₂(μ₂OCH₃)₂(3,5-Me₂pz)₆] (1) (3,5-Me₂pz⁻ = 3,5-dimethylpyrazolate) results in the formation of the Cu₆ planar hexagonal ring complex [Cu₆(μ₂OH)₆(3,5-Me₂pz)₆]·CH₃CN·CHCl₃ (2). A simple mechanism for this structural re-arrangement is proposed, in which 2 can be viewed as a hydrolysis product of 1. This process is clearly noticeable in the magnetic properties, which change from spin frustrated with a weak antiferromagnetic coupling in 1, to strongly antiferromagnetic in 2. Interestingly, the hexagonal ring complex 2 self-assembles in the solid state to form a porous hexagonal tubular structure containing guest solvent molecules that can be removed and CO₂-exchanged without loss of crystallinity.