C−H⋯Pd interactions and cyano-bridged heteronuclear polymeric complexes

Three new heterometallic complexes, [Cu(N-Meim)4Pd(μ-CN)2(CN)2]n (1), [Zn(N-Meim)3Pd(μ-CN)2(CN)2]n (2) and [Cd(N-Meim)2Pd(μ-CN)4]n (3), have been isolated from the reactions of M[Pd(CN)4] (M = Cu(II), Zn(II) or Cd(II)) and N-Meim (N-methylimidazole) with in different molar ratios. All complexes have been characterized by X-ray analyses, vibrational (FT-IR and Raman) spectra, thermal and elemental analyses. The crystallographic analysis reveals that the crystal structures of 1 and 2 are 1D coordination polymer, while 3 presents a 2D network. In the Cu(II) and Zn(II) complexes, two cyanide groups of [Pd(CN)4]2− coordinated to the adjacent M(II) ions and distorted octahedral and square pyramidal geometries of complexes are completed by four and three nitrogen atoms of N-Meim ligands, respectively. The Cd(II) ion is six-coordinate, completed with the two nitrogen atoms of N-Meim ligands in the axial positions and the four nitrogen atoms from bridging cyano groups in the equatorial plane. The most striking features of complexes 1–3 are the presence of obvious C–H⋯Pd hydrogen-bonding interactions between the Pd(II) and hydrogen atoms of N-Meim ligand. This weak hydrogen bonding plays a crucial role in the architecture of the network polymers. The adjacent chains are held together by C–H⋯Pd, C–H⋯π or π⋯π interactions, forming three-dimensional network.

Three new heterometallic complexes, [Cu(N-Meim)4Pd(μ-CN)2(CN)2]n (1), [Zn(N-Meim)3Pd(μ-CN)2(CN)2]n (2) and [Cd(N-Meim)2Pd(μ-CN)4]n (3), have been isolated from the reactions of M[Pd(CN)4] (M = Cu(II), Zn(II) or Cd(II)) and N-Meim (N-methylimidazole) with in different molar ratios. The most striking features of complexes are the presence of obvious C−H···Pd hydrogen-bonding interactions between the Pd(II) and hydrogen atoms of N-Meim ligand. This weak hydrogen bonding plays a crucial role in the architecture of the network polymers. The adjacent chains are held together by C–H⋯Pd, C–H⋯π or π⋯π interactions, forming three-dimensional network.Figure optionsDownload as PowerPoint slide