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.