Magnetic anisotropy and slow magnetic relaxation of seven-coordinate cobalt(II)–nitrate complexes.

Graphical abstract The static and dynamic magnetic properties of two seven-coordinate Co(II)–nitrate complexes adopting the distorted pentagonal bipyramid geometry have been studied. Their easy-plane magnetic anisotropies have been revealed by static magnetic data and theoretical calculations. They display slow magnetic relaxation under a 0.1 T applied dc field. Abstract Two seven-coordinate cobalt(II) complexes with the molecular formulae [Co(L)(NO 3) 2 (CH 3 CN)] (L = 2,2′-bipyridine, 1 ; L = 1,10-phenanthroline, 2) were prepared and magnetically characterized. X-ray single crystal diffraction shows that 1 exhibit the distorted pentagonal bipyramidal geometry around the central Co(II) ion, similar to 2. Magnetic anisotropies and single-molecule magnet behaviors of 1 and 2 have been studied by direct and alternating current magnetic measurements. The static magnetic data show the easy-plane magnetic anisotropies with positive zero-field splitting D value of 32.9(2) cm−1 for 1 and 31.4(2) cm−1 for 2 , which are confirmed by theoretical calculations by CASPT2 and DDCI3 methods. Both 1 and 2 display the field-induced slow magnetic relaxation under 0.1 T applied dc field. [ABSTRACT FROM AUTHOR]