Solvent-Induced Structural Diversity and Magnetic Research of Two Cobalt(II) Complexes

The solvent-induced topological and structural diversities of two
Co­(II) complexes, namely, [Co­(L)2(SCN)2] (Co1) and [Co2(L)2(SCN)­(OAc)3] (Co2) (L = 8-methoxyquinoline), were comparatively
analyzed. Certain proportions of L, Co­(OAc)2·4H2O, and NaSCN were mixed and dissolved in CH3OH
at 60 °C to obtain complex Co1. Complex Co2, an asymmetric dinuclear compound, was obtained by simply replacing
CH3OH with CH3CN as the solvent. The Co­(II)
ion in complex Co1 was coordinated by the N4O2 mode provided by two L ligands and two SCN– anions. The two Co­(II) ions in Co2 were in the N2O4 and NO5 coordination environment
and were linked by two μ2-OAc– bridges
and one rare μ3-OAc– bridge. Weak
interaction analysis revealed that complexes Co1 and Co2 exhibited 6-connected shp and 14-connected fcu nets, respectively.
Magnetic studies showed that Co1 demonstrated single-ion
magnet behavior under 2000 Oe. These behaviors are indicative of clearly
field-induced single-ion magnetic behavior with Ueff = 34.7(2) K and τ0 = 2.7(2) ×
10–7 s under 2000 Oe dc field, respectively. By
contrast, Co2 lacked frequency dependence under zero-field
conditions. Electrospray ionization mass spectrometry indicated that
two complexes were stable in N,N-dimethylformamide.