Synthesis, crystal structure and magnetic properties of H 2 tppz[ReCl 6 ] and [Cu(bpzm) 2 (μ-Cl)ReCl 3 (μ-ox)Cu(bpzm) 2 (μ-ox)ReCl 3 (μ-Cl)] n

• Published in: Dalton transactions : an international journal of inorganic chemistry 2015, Vol.44 (39), p.17118-17128
• Main Authors: Gryca, I., Palion-Gazda, J., Machura, B., Penkala, M., Kruszyński, R., Cano, J., Lloret, F., Julve, M.
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/C5DT02522B

Two new Re( iv ) compounds of formulae H 2 tppz[ReCl 6 ] ( 1 ) and [Cu(bpzm) 2 (μ-Cl)ReCl 3 (μ-ox)Cu(bpzm) 2 (μ-ox)ReCl 3 (μ-Cl)] n ( 2 ) [tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine and bpzm = bis(pyrazolyl-1-yl)methane] have been prepared and their crystal structures determined by X-ray diffraction on single crystals. Compound 1 is a mononuclear species whose structure consists of octahedral hexachlororhenate( iv ) anions and diprotonated H 2 tppz 2+ cations which are arranged in the unit cell as alternating anionic and cationic layers, held together by electrostatic forces. The structure of 2 is made up of alternating [Cu(1)(bpzm) 2 ] 2+ and [(ox)ReCl 3 (μ-Cl)Cu(2)(bpzm) 2 (μ-Cl)ReCl 3 (ox)] 2− entities interlinked by oxalate bridges to afford a neutral heterobimetallic chain. The oxalate group adopts the didentate (at Re)/monodentate (at Cu) bridging mode. The magnetic behavior of 1 and 2 has been investigated over the temperature range 1.9–295 K. 1 is a magnetically diluted Re( iv ) complex, the relatively large value of the zero-field splitting of the ground level [ D = −15.8(2) cm −1 ] accounting for the variation of χ M T in the low temperature range. Weak intrachain ferromagnetic interactions between Re( iv ) and Cu( ii ) through oxalate ( J 1 = +0.15 cm −1 ) and single chloro ( J 2 = +4.9 cm −1 ) bridges occur in 2 which are obscured by the large zero-field splitting of the Re( iv ) ion ( D Re = 42 cm −1 ). In addition, interchain antiferromagnetic interactions are also involved in 2 which are responsible for the metamagnetic behavior observed, the value of the critical dc magnetic field ( H c ) being 20 kOe.