| الملخص: | New complexes of manganese(II) hexafluoroacetylacetonate [Mn(hfac)<sub>2</sub>] with 2-(1-<i>R</i>-3-pyrazol-4-yl)-4,4,5,5-tetramethyl-2-imidazoline-3-oxide-1-oxyl (<i>R</i> = CHF<sub>2</sub>, CH<sub>2</sub>CH<sub>2</sub>F, CH<sub>2</sub>CHF<sub>2</sub> or CH<sub>2</sub>CF<sub>3</sub>) were synthesised and characterised structurally and magnetically. All complexes were prepared under similar conditions. Nonetheless, their crystal structures were considerably different. Depending on the structure of fluorinated alkyl substituent <i>R</i>, the complexation reaction led to complexes of three types: chain-polymeric complexes with the head-to-head or head-to-tail motif and complexes of molecular structure. All complexes show strong antiferromagnetic behaviour in a high-temperature region (150–300 K) and weak ferro- or antiferromagnetic exchange interactions at low temperatures. The stronger antiferromagnetic exchange, −101.7 ± 1.5 or −136 ± 10 cm<sup>−1</sup>, −82.3 ± 1.3 cm<sup>−1</sup> and −87.4 ± 1.3 cm<sup>−1</sup>, was attributed to the magnetic interaction in three- or two-spin clusters: {>N∸O–Mn<sup>2+</sup>–O∸N<} or {>N∸O–Mn<sup>2+</sup>}, respectively. The weaker antiferromagnetic interaction, −0.005, between three-spin clusters or ferromagnetic interactions, 0.18–0.81 cm<sup>−1</sup>, between two-spin clusters are realised through the pyrazole ring or intermolecular contacts.
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