Synthesis, crystal structure and magnetic properties of the complex [ReCl3(tppz)]·MeCN. Issue 123 (25th November 2015) - Palion-Gazda, J.
Abstract : The paper reports the synthesis, X-ray structure and a deep analysis of the variable-temperature magnetic data of the new complex [ReCl3 (tppz)]·MeCN being a very scarce example of mononuclear Re(iii ) complexes incorporating nitrogen donor ligands. Abstract : The reaction of the starting materials [Re III Cl3 (MeCN)(PPh3 )2 ] or [Re V OCl3 (PPh3 )2 ] with 2, 3, 5, 6-tetrakis(2-pyridyl)pyrazine (tppz) in acetonitrile yielded the Re(iii ) complex [ReCl3 (tppz)]·MeCN (1 ). This complex crystallizes in the monoclinic space group P 21 / 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–Ntppz bond lengths covering the ranges 2.3590(9)–2.3606(8) and 1.971(2)–2.096(2) Å, respectively. The magnetic properties of1 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 T1 ground state). The magnetic data of1 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 of1, 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.