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

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 44; no. 39; pp. 17118 - 17128
• Main Authors: Gryca, I, Palion-Gazda, J, Machura, B, Penkala, M, Kruszynski, R, Cano, J, Lloret, F, Julve, M
• Format: Journal Article
• Language: English
• Published: 01.09.2015
• Subjects: Bridges (structures); Cations; Crystal structure; Direct current; Ferromagnetism; Oxalates; Splitting; Unit cell
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c5dt02522b

Two new Re(iv) compounds of formulae H sub(2)tppz[ReCl sub(6)] (1) and [Cu(bpzm) sub(2)( mu -Cl)ReCl sub(3)( mu -ox)Cu(bpzm) sub(2)( mu -ox)ReC l sub(3)( mu -Cl)] sub(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 sub(2)tppz super(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) sub(2)] super(2+) and [(ox)ReCl sub(3)( mu -Cl)Cu(2)(bpzm) sub(2)( mu -Cl)ReCl sub(3)(ox)] super(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 super(-1)] accounting for the variation of chi sub(M)T in the low temperature range. Weak intrachain ferromagnetic interactions between Re(iv) and Cu(ii) through oxalate (J sub(1) = +0.15 cm super(-1)) and single chloro (J sub(2) = +4.9 cm super(-1)) bridges occur in 2 which are obscured by the large zero-field splitting of the Re(iv) ion (D sub(Re) = 42 cm super(-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 sub(c)) being 20 kOe.