Two dinuclear iron(ii) complexes K[Fe2(L1)(SCN)4]·2(C3H8O) and [Fe2(L1)(SeCN)3(C5H5N)]·H2O are stabilised in the ‘[HS–LS]’ state by a bis-tetradentate pyrazolate-based ligand

Abstract

Two air-sensitive dinuclear iron(II) complexes, K[Fe^II₂(L¹)(SCN)₄]·2(C₃H₈O) (1) and [Fe^II₂(L¹)(SeCN)₃(C₅H₅N)]·H₂O (2), of 3,5-bis[N,N-bis(2-pyridylmethyl)aminomethyl]-1H-pyrazolate [(L¹)⁻] have been prepared. Interestingly, complex 1 is anionic, featuring four coordinated SCN⁻ anions and a potassium counterion whereas complex 2 is neutral, containing a coordinated pyridine molecule and only three coordinated SeCN⁻ anions. These are the first iron complexes reported for this type of ligand. Magnetic measurements and Mössbauer spectra show that both 1 and 2 are in a ‘[HS–LS]’ mixed spin state between 300 and 2 K.