Crystal Structure of Bis(2-methoxy-6-((Z)-(p-tolylimino)methyl)phenoxy)palladium

Schiff-base complexes are being continuously studied concerning catalyst,1–3 biomedical4,5 and material applications for their structural fundamental and theoretical understanding. Pd(II) Schiff-base complexes have remarkable properties, such as high selectivity and activity by manipulating the ligand environment.6 The complex C30H28N2O4Pd was synthesized according to previous studies7 with slight modification. A 0.2mmol (Z)-2-methoxy-6-((p-tolylimino)methyl)phenol was added to a stirred solution of 0.1 mmol of palladium(II) acetate in 5 mL of ethanol. The solution was refluxed for 6 h, and cooled to the room temperature. The precipitate was filtered off and air-dried. The product was recrystallized in ethanol:chloroform (1:1) through a slow evaporation method to produce an orange crystal. Yield, 62.0%; m.p. 558 – 561 K. Anal. Calc. for C30H28N2O4Pd: C, 61.8; H, 4.4; N, 10.3%; Found: C, 61.6; H, 4.5; N, 10.7%. The IR spectrum was obtained as a KBr disc on a Perkin Elmer Spectrum One FTIR Spectrometer from 450 – 4000 cm–1. The peaks at 1596, 1327, 1258, 1542, 580 and 449 cm–1 were assigned to ν(C=N), ν(C–N), ν(C–O), ν(C=C aromatic), ν(Pd–O) and ν(Pd–N), respectively. The infrared data obtained are nearly similar based on a previous study reported.8 The NMR spectrum was obtained as a CDCl3 solution on Jeol 400 MHz spectrometer. The 1H NMR chemical shifts, δ, observed are (ppm): 2.42 (s, 3H, CH3), 3.36 (s, 3H, OCH3), 6.39 – 7.29 (m, 7H, aromatic, JHH = 1 – 3 and 6 – 9 Hz), 7.66 (s, 1H, HC=N). The coupling constant indicates the presence of meta and ortho aromatic protons. The crystal and structure-refinement data are summarized in Table 1 and selected bond distances and angles in Table 2. H atoms were positioned geometrically and allowed to ride on the parent C atom, with C–H = 0.95 – 0.98 Å, and with Uiso(H) = 1.2 (1.5 for methyl groups) times Ueq(C). Figure 1 represents the chemical diagram whereas Fig. 2 shows the ORTEP structure of the title compound. In this centrosymmetric complex, the two ligands are symmetrically related to each other and have the same bond angles and distances. The ligand was coordinated to the metal center through ONNO atoms, forming a square-planar complex, yielding two six-membered rings surrounding the metal center. 2019 © The Japan Society for Analytical Chemistry