A family of [Cu2], [Cu4] and [Cu5] aggregates : alteration of reaction conditions, ancillary bridges and capping anions

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Das, Manisha and Craig, Gavin A. and Escudero, Daniel and Murrie, Mark and Frontera, Antonio and Ray, Debashis (2018) A family of [Cu2], [Cu4] and [Cu5] aggregates : alteration of reaction conditions, ancillary bridges and capping anions. New Journal of Chemistry, 42 (17). pp. 14349-14364. ISSN 1144-0546 (https://doi.org/10.1039/C8NJ02131G)

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Abstract

The phenoxido-bridged [Cu2] complex [Cu2(μ-H4L1)(μ-OH)(μ1,3-NO3)(NO3)(OH2)]·H2O (1) and its hierarchical [Cu4] and [Cu5] assemblies [Cu4(μ-H4L1)2(μ-OH)2(μ1,3-ClO4)(OH2)2](ClO4)3·2H2O (2) and [Cu5(μ-H4L1)2(μ3-OH)2(μ1,3-O2CCF3)2(O2CCF3)2](CF3COO)2 (3) were obtained from the reactions of H5L1 (2,6-bis-{(1,3-dihydroxy-2-methylpropan-2-ylimino)methyl}-4-methylphenol) with three copper(ii) salts. The available NO3−, ClO4− and CF3COO− ions have been trapped for ‘spontaneous’ anion-directed ‘self-assembly’ reactions. All the synthesized complexes contain the [Cu2(μ-H4L1)(μ-OH)]2+ fragment, prone to assemble and crystallize [Cu4] and [Cu5] complexes under varying reaction conditions. They were characterized by UV-vis and IR spectroscopy, X-ray diffraction analysis and magnetic studies. A change from NO3− to ClO4− and CF3COO− results in different courses of reactions based on Cu2(μ-H4L1) fragments. Binding of NO3− provided 1 as an isolated [Cu2] complex by trapping the reactive fragment. In 2 a perchlorate ligand, in the μ1,3-binding mode, has been realized as a solitary support for the condensation of two Cu2(μ-H4L1) fragments. The {Cu5(μ3-OH)2(μ1,3-O2CCF3)2}6+ constellation in 3 contains five CuII centers with a unique Z-in distorted octahedral one at the central position. Binding of different anions to the copper(ii) centers controls the nuclearity of the reaction products and tuning of the self-aggregation process within the same ligand environment (μ-H4L1−). The magnetic properties of the compounds have been studied both experimentally and using DFT calculations, revealing moderate to strong antiferromagnetic coupling in all aggregates.

ORCID iDs

Das, Manisha, Craig, Gavin A. ORCID logoORCID: https://orcid.org/0000-0003-3542-4850, Escudero, Daniel, Murrie, Mark, Frontera, Antonio and Ray, Debashis;
CORE (COnnecting REpositories)