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A mononuclear cobalt(ii) complex [C 5 H 8 N 3 ] 2 [CoCl 4 (C 5 H 7 N 3 ) 2 ] (I) was synthesized and structurally characterized. Single crystal X-ray diffraction analysis indicates that monometallic Co(ii) ions acted as coordination nodes in a distorted octahedral geometry, giving rise to a supramolecular architecture. The latter is made up of a ½ unit form composed of an anionic element [Co 0.5 Cl 2 (C 5 H 7 N 3 )] - and one 2-amino-4-methylpyrimidinium cation [C 5 H 8 N 3 ] + . The crystalline arrangement of this compound adopts the sandwich form where inorganic parts are sandwiched between the organic sheets following the [100] direction. More information regarding the structure hierarchy has been supplied based on Hirshfeld surface analysis; the X⋯H (X = N, Cl) interactions play a crucial role in stabilizing the self-assembly process of I, complemented by the intervention of π⋯π electrostatic interaction created between organic entities. Thermal analyses were carried out to study the thermal behavior process. Static magnetic measurements and ab initio calculations of compound I revealed the easy-axis anisotropy character of the central Co(ii) ion. Two-channel field-induced slow-magnetic relaxation was observed; the high-frequency channel is characterized by underbarrier relaxation with U eff = 16.5 cm -1 , and the low-frequency channel involves a direct relaxation process affected by the phonon-bottleneck effect., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

Detailed structural information is essential for understanding the properties of TCNQ and TCNQF 4 compounds (TCNQ = 7,7,8,8-tetracyanoquinodimethane; TCNQF 4 = 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane). The ineludible requirement of obtaining crystals of a size and quality sufficient to yield a successful X-ray diffraction analysis has been challenging to satisfy because of the instability of many of these compounds in solution. Crystals of two new complexes of TCNQ, [ trans -M(2 ampy ) 2 (TCNQ) 2 ] [M = Ni ( 1 ), Zn ( 2 ); 2ampy = 2-aminomethylpyridine], as well as unstable [Li 2 (TCNQF 4 )(CH 3 CN) 4 ]·CH 3 CN ( 3 ), can be prepared in minutes by a horizontal diffusion technique and can be harvested easily for X-ray structural studies. Compound 3 , previously described as "Li 2 TCNQF 4 ," forms a one-dimensional (1D) ribbon. Compounds 1 and 2 can also be obtained as microcrystalline solids from methanolic solutions of MCl 2 /LiTCNQ/2 ampy . Their variable-temperature magnetic studies confirmed a contribution of strongly antiferromagnetically coupled pairs of TCNQ •- anion radicals at higher temperatures with exchange coupling J / k B = -1206 K and J / k B = -1369 K for 1 and 2 , respectively, estimated using a spin dimer model. The presence of magnetically active anisotropic Ni(II) atoms with S = 1 in 1 was confirmed, and the magnetic behavior of 1 , representing an infinite chain of alternating S = 1 sites and S = 1/2 dimers, was described by a spin-ring model suggesting ferromagnetic exchange coupling between Ni(II) sites and anion radicals., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)