Dinuclear Praseodymium(III) Complex with N,N′-Bis(2-hydroxy-3,5-dimethylbenzyl)-N,N′-dimethyl-1,2-ethanediamine

Abstract

N,N′-Bis(2-hydroxy-3,5-dimethylbenzyl)-N,N′-dimethyl-1,2ethanediamine (H2hdde) is a tetradentate N2O2 ligand similar to the famous tetradentate Schiff-base, N,N′-ethylenebis(salicylideneimine), H2salen, but with two saturated C–N bonds, being different from the H2salen ligand.1 So far, mononuclear vanadium,2 manganese,3 iron,4 and molybdenum5 complexes, dinuclear vanadium,2 dinuclear iron,6 trinuclear manganese,3,7 tetranuclear manganese,3 tetranuclear zinc,8 tetranuclear cadmium,8 tetranuclear nickel,9 hexanuclear nickel,9 and heptanuclear nickel10 complexes were reported concerning the H2hdde ligand. In our laboratory, we have aimed to extend the coordination chemistry of this ligand to the rare-earth elements. In this study, we successfully synthesized a praseodymium complex with hdde2– and determined the crystal structure in order to elucidate the dinuclear molecule (Fig. 1). The ligand H2hdde was synthesized by a method described in the literature.11 The complex was prepared by a reaction of H2hdde and praseodymium(III) salt. To a methanol solution (5 cm3) of H2hdde (53.9 mg, 0.15 mmol) was added 35.9 mg (0.1 mmol) of praseodymium(III) acetate dihydrate, and then six drops of triethylamine were added into the reaction mixture to obtain a pale-green precipitate. The precipitate was collected and dried under a vacuum. Yield, 51.2 mg (84.6%). Anal. Found: C, 49.21; H, 6.35; N, 4.25%. Calcd for C50H78N4O12Pr2[Pr2(hdde)2(CH3COO)2(CH3OH)2]·2H2O: C, 49.67; H, 6.50; N, 4.63%. IR (KBr, cm–1): 3320 ν(OH), 2980 νas(CH3), 2916 νas(CH2), 2854 νs(CH3), 2808 νs(CH2), 1556 νas(COO), 1476 δ(CH3), 1425 νs(COO). X-ray quality crystals were grown by recrystallization from methanol–dichloromethane. 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 intrinsic phasing method and refined by full-matrix least-squares methods. The hydrogen atoms were inserted at their calculated positions, and fixed there, except for the hydrogen atom attached to the O5 atom of the coordinated methanol molecule, which was located from a D-Fourier map. All of the calculations were carried out on a Windows 7 Core i5 computer utilizing the SHELXT-201412 and SHELXL-2014.13 Crystallographic data have been deposited with Cambridge Crystallographic Data Centre (Deposit number CCDC-2091175). Copies of the data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/ retrieving.html (or from the Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge, CB2 1EZ, UK; Fax, +44 1223 336033; e-mail, deposit@ccdc.cam.ac.uk). A single-crystal X-ray structure analysis revealed that the molecule is a centrosymmetric dinuclear praseodymium complex. The asymmetric unit consists of one half of a [Pr2(hdde)2(CH3COO)2(CH3OH)2] complex and one dichloromethane molecule. The molecular structure, drawn by ORTEP, is shown 2021 © The Japan Society for Analytical Chemistry