Wydział Chemii

Zuzanna Walkowiak

Anna Gągor

Saied M. Soliman

Maria Jerzykiewicz

Marcin Sarewicz

Magdalena Fitta

Robert Pełka

Agnieszka Wojciechowska

2024

Journal of Molecular Structure

1308

138094/1-138094/12

10.1016/j.molstruc.2024.138094

Naukowa

Angielski

Artykuł

A new heteroleptic [CuBr(l−Arg)(bpy)]Br·2H₂O (1) (l−Arg=l−Arginine, bpy=2,2’−bipyridine) complex has been synthesized and its molecular and supramolecular structure aspects have been discussed based on the X−ray single crystal structure and Hirshfeld analyses. In addition, the properties of complex 1 have been elucidated using different spectroscopic methods (FT−IR / FIR, Raman, NIR−Vis−UV, Q− / X− band EPR) and magnetic measurements. In this complex, the bromide anion occupies the apex of a slightly distorted square pyramid (τ = 0.12). The [CuBr(l−Arg)(bpy)]⁺ complex units exhibit a ribbon−like organization, with Cu(II) metal centers located at the corners of triangles where the shortest Cu∙∙∙Cu distance is 5.579 Å. The aromatic moieties of bpy are aligned nearly parallel leading to π···π interactions. Both, non−bonded and coordinated, Br⁻ ions act as hydrogen−bond acceptors for guanidinium groups. Hirshfeld analysis indicated the importance of the Br∙∙∙H (17.9 − 18.4 %), O∙∙∙H (14.9−15.2 %), and H∙∙∙H (42.3−43.1 %) interactions in the molecular packing of the studied complex. Atoms in molecules (AIM) calculations indicated mainly the closed shell character for the Cu−N, Cu−O and Cu−Br coordination interactions. The G value calculated using the Q−band EPR spectra parameters g_|| = 2.235 and g_⊥= 2.05 is 4.7, what indicating negligible coupling and that local tetragonal axes are aligned parallel. A negative value of Weiss temperature θ_CW = -0.32 K indicates the presence of weak antiferromagnetic coupling between the neighboring Cu(II) ions mediated through hydrogen bonds and π-π stacking of aromatic moieties of bpy. The value of g_av= 2.113 obtained from Q−band EPR spectra is consistent with that corresponding to the Curie constant (C = 0.4138 emu K mol⁻¹), i.e.g = 2.101, and that obtained from the best fitting to the Brillouin function: g = 2.139.

L−arginine, Copper(II), Structure, Hirshfeld, Spectroscopies, Antiferromagnetic, Bromide

http://doi.org/10.1016/j.molstruc.2024.138094

http://www.elsevier.com