Synthesis, crystal structure and magnetic properties of the complex [ReCl3(tppz)]·MeCNElectronic supplementary information (ESI) available: Magneto-structural data for Re(iii) complexes (Table S1), IR (Fig. S1), 1H and 13C NMR spectra (Fig. S3), and XPRD (Fig. S2) for 1, Appendix [energy levels for six-coordinate Re(iii)] and X-ray crystallographic tables (CIF for 1). CCDC 1431249. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5ra21466a

• Main Authors: Palion-Gazda, J, Gryca, I, Machura, B, Lloret, Francesc, Julve, Miguel
• Format: Journal Article
• Language: English
• Published: 25.11.2015
• ISSN: 2046-2069
• DOI: 10.1039/c5ra21466a

The reaction of the starting materials [Re III Cl 3 (MeCN)(PPh 3 ) 2 ] or [Re V OCl 3 (PPh 3 ) 2 ] with 2,3,5,6-tetrakis(2-pyridyl)pyrazine (tppz) in acetonitrile yielded the Re( iii ) complex [ReCl 3 (tppz)]·MeCN ( 1 ). This complex crystallizes in the monoclinic space group P 2 1 / n and its crystal structure consists of neutral mononuclear entities with meridional geometry of the chloride ligands, and the six-coordination of the Re( iii ) ion being completed by the tridentate tppz ligand. Each metal centre exhibits a highly distorted octahedral coordination with Re-Cl and Re-N tppz bond lengths covering the ranges 2.3590(9)-2.3606(8) and 1.971(2)-2.096(2) Å, respectively. The magnetic properties of 1 have been investigated in the temperature range 1.9-290 K. They are characteristic of a six-coordinate Re( iii ) mononuclear complex with d 4 low-spin ( 3 T 1 ground state). The magnetic data of 1 are discussed through a deep analysis of the influence of the ligand-field, spin-orbit coupling, tetragonal distortion and covalency effects. The second-order Zeeman effect between the non-magnetic ground state ( M J = 0) and higher energy levels ( M J ≠ 0) determines the magnetic susceptibility of 1 , the value of the temperature-independent paramagnetic susceptibility being 3378 × 10 −6 cm 3 mol −1 . This value compares well with those reported for other structurally characterized Re( iii ) complexes. The paper reports the synthesis, X-ray structure and a deep analysis of the variable-temperature magnetic data of the new complex [ReCl 3 (tppz)]·MeCN being a very scarce example of mononuclear Re( iii ) complexes incorporating nitrogen donor ligands.