Field‐Induced Single‐Ion Magnetism Based on Spin‐Phonon Relaxation in a Distorted Octahedral High‐Spin Cobalt(II) Complex

The six-coordinate mononuclear high-spin cobalt(II) complex [Co(bpy)2(ClAn)]·EtOH (1; bpy = 2,2′-bipyridine, ClAn2– = chloranilate) and its magnetically diluted analogue [Co0.1Zn0.9(bpy)2(ClAn)]·EtOH (3), in which the CoII centres of 1 are partially diluted with the magnetically inactive ZnII centres of [Zn(bpy)2(ClAn)]·EtOH (2) as a diamagnetic matrix, exhibited slow magnetic relaxation in applied direct-current (DC) magnetic fields. Fits of the DC magnetic data indicate that this new field-induced single-ion magnet possesses large positive axial and significant rhombic zero-field splittings. The results of temperature-dependent and DC-magnetic-field-dependent alternating-current magnetic measurements on 1 and 3, which is a field-induced single-ion magnet, agree with those from theoretical studies, and spin relaxation occurs through two-phonon Raman and direct spin-phonon bottleneck processes of Kramers ions.