Synthesis, crystal structure and spectroscopic investigations of heteronuclear Co(III)/Cu(II), Co(III)/Cd(II) and Fe(III)/Cd(II) 3D coordination polymers with 4-(2-aminoethyl)pyridine

The cyanide complexes of transition metals with 4-(2-aminoethyl)pyridine (4aepy) of {[Cu(H2O)(mu-4aepy)Cu(mu-4aepy) 2Cu(mu-4aepy)Co2(mu-CN)6(CN)6]middot3H2O}n ( 1 ), (NH4 )[Cd(mu-4aepy)2Co(mu-CN)2 (CN)4 ] n ( 2 ) and (NH4 )[Cd(mu-4aepy)2Fe(mu-CN)2(CN)4]n ( 3 ) were synthesized and investigated by vibrational (FT-IR and Raman), powder X-ray diffraction (PXRD), elemental and thermal analysis techniques. The crystal struc-tures of the complexes have been determined by the single crystal X-ray diffraction (SC-XRD) patterns. The crystallographic analysis reveals that complex 1 crystallizes in the monoclinic system, space group P2 1 , whereas; complexes 2 and 3 crystallize in the tetragonal system, space group P42/ncm. The asym-metric unit of heterometallic complex 1 consists of three Cu(II) ions, two Co(III) ions, four 4aepy ligands, twelve cyanide ligands, one aqua ligand and three non-coordinated water molecules. The asymmetric unit of heterometallic complexes 2 -3 consists of one Cd(II) ion, one M ion [M = Co(III) in 2 and Fe(III) in 3 ], two cyanide ligands, half 4aepy ligand and one ammonium ion. Each Cd(II) ion is located at a center of symmetry and is coordinated by two nitrogen atoms by the cyanide ligands and by four nitrogen atoms by the 4aepy ligands. As a result, they show distorted octahedral coordination geometries. In complex 1 , the intermolecular O-H center dot center dot center dot N, N-H center dot center dot center dot N, N-H center dot center dot center dot O and C-H center dot center dot center dot N hydrogen bonds and C equivalent to N center dot center dot center dot pi and pi center dot center dot center dot pi in-teractions play a crucial role in the architecture of 3D network. The intermolecular C equivalent to N middotmiddotmiddot pi interaction between cyanide ligand and pyridine ring of the 4aepy ligand is the most striking feature of complex 1 . Heterometallic complexes 2-3 have 3D coordination polymers.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, cyanide complexes of transition metals with 4-(2-aminoethyl)pyridine were synthesized and investigated. The crystal structures of the complexes were determined using single crystal X-ray diffraction. Complex 1 crystallizes in the monoclinic system, while complexes 2 and 3 crystallize in the tetragonal system. The complexes exhibit various coordination geometries and form 3D networks through hydrogen bonds and π interactions. Complexes 2-3 are 3D coordination polymers.