Self-Assembly of the Hexabromorhenate(IV) Anion with Protonated Benzotriazoles: X-ray Structure and Magnetic Properties

Two novel ReIV compounds of formulas [HBTA]2[ReIVBr6] (1) and [HMEBTA]2[ReIVBr6] (2) [BTA = 1H-benzotriazole and MEBTA = 1-(methoxymethyl)-1H-benzotriazole] have been synthesized and magneto-structurally characterized. 1 and 2 crystallize in the triclinic system with space group P1̅. In both compounds, the rhenium ion is six-coordinate, bonded to six bromo ligands in a regular octahedral geometry. Short ReIV–Br···Br–ReIV contacts, π–π stacking, and H-bonding interactions occur in the crystal lattice of both 1 and 2, generating novel supramolecular structures based on the ReIV. The different dispositions of the cations and the intermolecular Br···Br contacts in 1 and 2 play an important structure–property role, with the magnetic properties of 1 and 2 revealing a significant antiferromagnetic coupling between ReIV ions through intermolecular Br···Br interactions. In 1, these interactions account for a maximum in the magnetic susceptibility at ca. 10 K.