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.

两种新型四价铼（Re(IV)）化合物，化学式分别为[HBTA]₂[ReIVBr₆]（化合物1）与[HMEBTA]₂[ReIVBr₆]（化合物2）[其中BTA为1H-苯并三氮唑（1H-benzotriazole），MEBTA为1-(甲氧基甲基)-1H-苯并三氮唑（1-(methoxymethyl)-1H-benzotriazole）]，已被成功合成并完成磁学与结构表征。化合物1和2均结晶于三斜晶系，空间群为P1̅。在两种化合物中，铼离子均为六配位，与六个溴配体结合形成正八面体配位几何结构。在化合物1和2的晶格中，均存在短程Re(IV)–Br···Br–Re(IV)相互作用、π-π堆积（π–π stacking）与氢键（H-bonding）作用，由此构建出基于四价铼的新型超分子结构。化合物1与2中阳离子的不同排布方式以及分子间Br···Br相互作用，对其结构-性能关系起到关键调控作用；两种化合物的磁学性质均表明，四价铼离子之间通过分子间Br···Br相互作用存在显著的反铁磁耦合（antiferromagnetic coupling）。在化合物1中，此类相互作用使得磁化率（magnetic susceptibility）在约10 K处出现峰值。