New Cobalt(II) and Copper(II) Thiocyanate Complexes of 2,5‐Bis(pyridin‐2‐yl)‐1,3,4‐oxadiazole Ligand: Synthesis, Crystal Structures, Spectral Properties and Hirshfeld Surface Analysis

Abstract

The synthesis and characterization of two new mononuclear coordination complexes based on 2,5-bis(pyridin-2-yl)-1,3,4oxadiazole (bpox) and thiocyanate ion as coligand, [M (bpox) 2 (SCN) 2 ]nH 2 O (M = Co, n = 1 for complex 1; M = Cu, n = 0 for complex 2), are described. The obtained complexes crystallize in the monoclinic crystal system with space group C 2/c for complex 1 and P 2 1 /n for complex 2. UV/Vis, FTIR and Raman data indicated the presence of bpox and thiocyanate groups, in isolated compounds. This finding has been confirmed by crystallographic studies, which shows that the two metals Co(II) and Cu(II), have an octahedral environment in complex 1 and complex 2, respectively, with both bpox ligands in equatorial sites and terminal SCN À in axial positions. The crystal structure cohesion of each compound is ensured by intramolecular metal-nitrogen M-N (M = Co, Cu) interactions, by π-π stacking interactions and by different intermolecularhydrogen bonds, such as C-H⋯π, O-H⋯N, O-H⋯O, C-H⋯N, and/or C-H⋯S. The three-dimensional Hirshfeld surface analysis and the two-dimensional fingerprint plots reveal that the structure is dominated by C⋯H/H⋯C contacts.[a] Dr.

Cobalt(II) coordination complex with 2,5-bis(pyridine-2-yl)-1,3,4-thiadiazole and thiocyanate as co-ligand: Synthesis, crystal structure, Hirshfeld surface analysis, spectroscopic, thermal and magnetic properties

“…In this crystal structure each independent centrosymmetric cationic entity [CoL 2 ] 2+ is connected apically to two axial thiocyanate anions SCNto build CoL 2 (SCN) 2 complex, as indicated in the Fig.1, where the both 2,5-bis(pyridin-2-yl)-1,3,4-thiadiazole ligands (L) adopt a trans configuration. The same configuration was previously observed in other cobalt complexes with the thiocyanate ion as coligand[17,26,[40][41][42]. Indeed, the 2,5-bis(pyridine-3-yl)-1…”

“…[43]. [41]. The trans behaviour was also found in the case of Co(II) coordination complex with the same investigated ligand (L) without thiocyanate ion as coligand [17,26,42].…”

“…Therefore, the CoN 6 octahedra are slightly axially compressed. This structural feature is typical for related compounds [17,26,[40][41][42], and isostructural to iron complex FeL 2 (NCS) 2 described by Klingele el al. [43].…”

A new homobimetallic cobalt(II) complex based on the tetradentate 3,5-bis(2-pyridyl)-1H-1,2,4-triazole ligand: Synthesis, crystal structure, Hirshfeld analysis, spectroscopic characterization, magnetic properties and antimicrobial activities

“…By analogy with the Hbpt proligand spectrum, these bands were attributed to 𝜋→𝜋* ligand transitions, characteristic of their 𝜋-electronic system [40,43]. The significant red shift of the transitions attributed to the ligand in the complex (Table 5) can be due to the stabilization of the 𝜋* orbitals and to a better electronic delocalization along the conjugated system [44]. The d-d transitions of the Co complex appear in the visible domain as three low-intensity bands at 479 (λ1), 509 (λ2) and 785 nm (λ3).…”

First divalent copper complex of a terdentate thiosemicarbazido-pyrazoline derived from 2,4-pentanedione bis(thiosemicarbazone): Synthesis, structural characterisation and antimicrobial in vitro activity assessment

“…S2), only 3 bands and one shoulder were observed for the N-H vibrations, which means that ligand has been deprotonated and is coordinated in anionic form. Comparison between the spectra of H 2 L 2 ligand and [(L 2• )Cu(SCN)] complex showed also a new sharp and strong signal at 2115 cm -1 attributed to the stretching vibration υ(CN) of thiocyanate group; a similar frequency was observed in a Cu complexes with SCNion coordinated to the metal via N atom [60,61].…”