Mechanism of reversible spin transition with a thermal hysteresis loop in [FeIII(qsal)2][Ni(dmise)2] · 2CH3CN: Selenium analogue of the precursor of an Fe(III) spin-crossover molecular conducting system

A novel Fe(III) spin-crossover complex, [Fe(qsal)2][Ni(dmise)2] · 2CH3CN 1 [qsalH = N-(8-quinolyl)-salicylaldimine, dmise = 4,5-dithiolato-1,3-dithiole-2-selone] was prepared. The magnetic susceptibility measurements revealed 1 exhibited a cooperative spin transition with a thermal hysteresis loop of 15 K. The high and the low temperature structures of 1 indicated three-dimensional intermolecular π−π interactions play a key role in the cooperative spin transition, accompanying a reversible molecular slipping of π-dimer of Ni(dmise)2 along the molecular long axis. The transfer integral calculation for 1 suggested the π-dimer of Ni(dmise)2 is in the spin singlet state.

Graphical abstractThe cooperative spin transition of a novel Fe(III) complex with an Ni(dmise)2 anion accompanies a reversible molecular slipping of π-dimer of Ni(dmise)2 along the molecular long axis, which is due to intermolecular π−π interactions between the Fe(III) spin-crossover cation and Ni(dmise)2 anion.Figure optionsDownload full-size imageDownload as PowerPoint slide