Publication in Dalton Transactions

The aim of the work was to prepare a structurally new cross-bridged cyclam derivative containing two 2-pyridylmethyl pendant arms (L) and to study its Fe(II) complexes [Fe(L)][FeCl₄]·H₂O (1·H₂O), [Fe(L)]Cl₂·4H₂O (2·4H₂O), [Fe(L)](BF₄)₂·0.5CH₃CN (3·0.5CH₃CN), [Fe(L)](BPh₄)₂·CH₃OH (4·CH₃OH). Cis-V configuration with a distorted octahedral geometry for [Fe(L)]²⁺ cation was confirmed by X-ray diffraction analysis in all studied complexes. The magnetic measurements revealed the spin crossover (SCO) behaviour for all the complexes with the transition temperature increasing with the counter anion in the order BF₄^– (3) < [FeCl₄]^2– (1) < BPh₄^– (4) and depending on the presence/absence of co-crystallized solvent molecule (only for 3·0.5CH₃CN).