Synthesis and Crystal Structure of a Dinuclear Cu(II) Complex with <i>N,N,N</i>′,<i>N</i>′-Tetrakis(2-pyridylmethyl)-1,6-hexanediamine

Abstract

65Many dinuclear complexes linked by a bridging oxo/hydroxo ion and two carboxylate have been reported as biomimetic models for metalloenzymes. 1,2 Recently, hexadentate ligands that contain two terminal tridentate coordination sites connected by flexible linkers are often used for this purpose to prepare such complexes. 3,4 N, N,N′, X-Ray difraction measurements were made on a Rigaku VariMax Saturn CCD 724+ diffractometer with graphite monochromated Mo Kα radiation at 113 K. The structure was solved by direct methods (SIR92) and expanded using Fourier techniques. The non-hydrogen atoms were refined anisotropically. Hydrogen atoms (H5A and H5B) involved in hydrogen bonds were located in difference Fourier maps and refined with an isotropic displacement parameter. Other hydrogen atoms were located on the calculated positions, and refined using the riding model. The final cycle of full-matrix least-squares refinement on F 2 using SHELXL2016/6 was based on observed reflections and variable parameters, and converged with unweighted and weighted agreement factors of R and Rw. 7Details of the X-ray structure determination are listed in Table 1.An ORTEP drawing for the complex cation of 1 is shown in Fig. 2, and the selected bond lengths and angles are listed in Table S1. The complex 1 cation has a dinuclear structure, but two Cu(II) ions are separated by a hexamethylene linker chain. Each Cu(II) ion is bound by tphn, CH3COO -, and H2O/BF4 -. The geometrical environments for two oxygen atoms in each acetate anion are quite different. The Cu1-O1 and Cu2-O3 distances are 1.940(3) and 1.954(3)Å, respectively. Those values are in the range for common Cu-O bonds. On the other hand, the Cu1···O2 and Cu2···O4 distances, 2.780(4) and 2.662(4)Å, are too long to define the coordination bond. In addition, the bonds C31-O1 [1.285 (6)