Ligand substitution in cis-bis(acetonitrile)tetrachlororhenium(IV) complex with N,N-dimethylformamide and N,N-dimethylacetamide

The preparation, crystal structures, and magnetic properties of two novel mononuclear Re-IV complexes of formula cis-[(ReCl4)-Cl-IV(dmf)(2)] (1) and cis-[(ReCl4)-Cl-IV(dma)(2)] (2) (dmf = N,N-dimethylformamide and dma = N,N-dimethylacetamide) have been studied. Both Re-IV systems were synthesized through ligand substitution reactions from the cis-[(ReCl4)-Cl-IV(MeCN)(2)] precursor, upon heating in the employed solvent. 1 and 2 crystallize in the monoclinic crystal system with space group C2/c. Each Re-IV ion exhibits a distorted octahedral environment, being bonded by two oxygen atoms from two dmf (1) and dma (2) molecules and four chloride ions. In the crystal lattice of 1 and 2, the mononuclear Re-IV complexes are placed generating short intermolecular Re-IV-Cl center dot center dot center dot Cl-Re-IV contacts. The magnetic properties of 1 and 2 were investigated through variable-temperature magnetic susceptibility measurements, which reveal significant antiferromagnetic exchange interactions between neighboring Re-IV ions. In 1, these interactions account for a maximum in the magnetic susceptibility curve at ca. 5.0 K. (C) 2018 Elsevier Ltd. All rights reserved.