A Pyrazine-Bridged Ni(II) Coordination Polymer

Abstract

The single pyrazine-bridged polymeric complex {[Ni(pyz)(H2O)4](NO3)2.2H2O}n has been synthesised and characterised by elemental analyses, IR and UV-vis spectra, and a single-crystal X-ray diffraction study. The coordination around the Ni centre is perfectly octahedral. The Ni(H2O)4 coordination planes are bridged by pyrazine ligands forming an infinite chain structure. Two nitrate anions and two water molecules exist in the lattice and are linked by intermolecular hydrogen bonds to the coordinated water molecules.

Crystal structure ofcatena-poly[[[trans-bis(acetonitrile-κN)diaquacobalt(II)]-μ-pyrazine-κ2N:N′] dinitrate]

“…The bridging bis-monodentate pyrazine molecules link the Co II ions, forming linear chains extending parallel to the a axis. The distance between two symmetry-related Co II ions within a chain (symmetry code: 1 + x, y, z) is 7.0798 (3) Å , in good agreement with those reported for similar structures (Choudhury et al, 2002;Holman et al, 2005;Aşkin et al, 2015).…”

“…The two Co-O water bonds have a length of 2.0315 (8) Å , considerably shorter than the two Co-N acetonitrile bonds of 2.1263 (9) Å , and the two Co-N pyrazine bonds of 2.1493 (10) Å . The resulting coordination sphere is compressed octahedral with all bond lengths in good agreement with similar structures (Choudhury et al, 2002;Holman et al, 2005;Aşkin et al, 2015). In contrast to the N 2 O 4…”

“…coordination spheres observed more frequently in the structures of other Co-containing compounds (Choudhury et al, 2002;Holman et al, 2005;Hyun et al, 2011;Aşkin et al, 2015), the title structure exhibits an N 4 O 2 coordination sphere due to the inclusion of the solvent acetonitrile molecules in the coordination sphere of Co II . The bridging bis-monodentate pyrazine molecules link the Co II ions, forming linear chains extending parallel to the a axis.…”

Metal(II) Ion Complexes with 5‐(Pyrazin‐2‐yl)‐2,4‐dihydro‐3H‐1,2,4‐triazole‐3‐thione; Synthesis, Structural Characterization, Acid‐base, and Complexing Properties in Solution

“…This observation can be explained by the nitrogen atom of the triazole ring coordinating with the metal ions in complexes 1 – 4 . An intensive band that appears for the ligand at 1172 cm –1 due to the pyrazine ring, is shifted to lower wavelengths and appears in the spectra of complexes 1 , 2 , and 3 at about 1157 cm –1 , thus indicating complexation of the metal atoms via pyrazine nitrogen . However, in the spectrum of complex 4 , this band remains unshifted, suggesting that the pyrazine nitrogen is not involved in coordination…”

Dichlorotetrakis[3-(4-pyridyl)-1H-pyrazole]cobalt(II) acetonitrile tetrasolvate: an infinite hydrogen-bonded network, in an instant

“…Linear bridging ligands commonly give rise to in®nite coordination polymers (Fujita et al, 1996;Choudhury et al, 2002;Zheng et al, 2005;Subramanian & Zaworotko, 1995); bent' bridging ligands, arising here from the combination of six-and ®ve-membered rings, are less explored. As a result, we decided to explore the coordination chemistry of the 4pypz ligand.…”