Crystal Structure of a Hydrolyzed Product of the Cobalt(III) Complex with 1-(3,5-Dichlorosalicylideneamino)-3-amino-2-propanol

Much interest has been attracted to the coordination chemistry of potential pentadentate Schiff-base ligands, 1,3-bis(salicylideneamino)-2-propanol (H3bsalpr) and its substituted derivatives, with two phenolato-oxygen, two imino-nitrogen, and one alcoholate-oxygen donor atoms, are of interest. In the crystals, these Schiff-base ligands have intramolecular hydrogen bonds between imino-nitrogen and phenolato-oxygen atoms and intermolecular hydrogen bonds between an alcohol-oxygen atom and a phenolato-oxygen atom of neighboring Schiff-base molecule.1–5 The reaction between these Schiff-base ligands and metal salts generates mononuclear copper(II),6 tetranuclear zinc(II)7 complexes with a tetradentate O, N, N, O-chelate, and dinuclear copper(II),8 nickel(II),9 manganese(III),10,11 and cobalt(III)12, and tetranuclear manganese(II,III)13,14 complexes with a tridentate O, N, O-chelate. Aiming at extending these systems, we decided to prepare a cobalt complex with 1,3-bis(3,5-dichlorosalicylideneamino)-2-propanol (H3bdcsalpr), which has not been reported so far. In this study, we performed a reaction between H3bdcsalpr and cobalt(II) chloride hexahydrate in the presence of triethylamine in acetonitrile, and determined the crystal structure of the isolated complex, which has been found to be a new mononuclear cobalt(III) complex with hydrolyzed Schiff-base ligands, 1-(3,5-dichlorosalicylideneamino)-3-amino-2-propanol (Hdcsalapr–), [Co(Hdcsalapr)2] Cl·2CH3CN·2H2O (1), as depicted in Fig. 1, is different from the expected dinuclear cobalt complexes that we prepared before.12 A Schiff-base ligand, H3bdcsalpr, was synthesized by a similar method to the previously reported one.5 1,3-Diamino-2propanol (0.703 g, 7.8 mmol) and 3,5-dichlorosalicylaldehyde (3.00 g, 15.7 mmol) were dissolved in methanol (70 cm3). The solution was refluxed for 3 h, and then left at room temperature. The resulting yellow precipitate was filtered off, washed with methanol, and dried under a vacuum. Yield, 3.16 g (93%). IR (KBr, cm–1): 3219 (ν(OH)), 3064 (ν(CH(phenyl)), 2951 (νasCH2), 2872 (νsCH2), 1626(νC=N). Single crystals of 1 were obtained as follows: H3bdcsalpr (42.5 mg, 0.1 mmol) was dissolved in acetonitrile (3 mL). To this solution, cobalt(II) chloride hexahydrate (24.0 mg, 0.1 mmol) and six drops of triethylamine were added. The resulting brown solution was filtered after standing for several days to remove a small amount of white precipitate, and then the filtrate was left at room temperature for a further several days to give reddish-brown crystals. Yield, 5.7 mg (7.8% based on the metal salt). Reflectance spectra: λmax 284, 422 (A1g→T2g), 550sh (A1g→T1g), 724 (A1g→T2g) nm. X-ray diffraction data were collected on a Bruker CCD X-ray diffractometer (SMART APEX) using graphite-monochromated Mo-Kα radiation. Crystal data and details concerning the data collection are given in Table 1. The structure was solved by an 2022 © The Japan Society for Analytical Chemistry