Synthesis and Crystal Structure of Bis[2-(2-imidazolinyl)phenolato]zinc(II)

Cobalt(II) complexes have been extensively investigated in the last two decades owing to potential application to singlemolecule magnets.1 To precisely understand the static and dynamic magnetic properties, the synthesis and crystallization of an analogous complex with a diamagnetic transition metal ion is important. Recently, we have reported on the crystal structure and single-ion magnet (SIM) behavior of the bis[2-(2imidazolinyl)phenolato]cobalt(II) complex.2 This complex is a rare example of 3d SIM, which shows slow magnetic relaxation under zero field. The origin of the zero-field SIM behavior was suggested to be intermolecular magnetic interactions arising from the hydrogen-bonded chain structure of the complex. To investigate the effect of intermolecular interactions on the static and dynamic magnetic property, the crystallization of an isomorphous complex with a diamagnetic ion is necessary. In this study, we report on the synthesis, crystal structure and hydrogen-bonded interactions of a zinc(II) analogue, bis[2-(2imidazolinyl)phenolato]zinc(II) (Fig. 1). The ligand precursor, 2-(2-imidazolinyl)phenol (H2imn), was synthesized by a previously reported procedure.3 A zinc(II) complex analogous to the title compound was reported by He, although this compound includes a methanol molecule as a solvent of crystallization.4 To obtain a zinc(II) complex isomorphous to [Co(Himn)2], we employed the same synthetic procedure, except for the reaction condition.2 Colorless crystals of [Zn(Himn)2] were immediately formed upon mixing a 10-mL methanol solution of KOtBu (45.4 mg) and H2imn (65.7 mg) and a 10-mL methanol solution of ZnCl2 (27.9 mg) in air, while the cobalt(II) analogue was synthesized under an Ar atmosphere. Yield: 63.3 mg (80%). The crystal data are included in Table 1. X-ray crystallographic data were collected on a Bruker smart APEX CCD diffractometer at 90 K. The integrated and scaled data were empirically corrected with SADABS.5 The initial structure was solved by an intrinsic phasing method with SHELXT-2014,6 and refined using the full-matrix least-squares method on F2 utilizing SHELXL-2014.7 The non-hydrogen atoms were refined 2019 © The Japan Society for Analytical Chemistry