文摘
The synthesis, and the structural and magnetic properties, of the following new iron(III) Schiff base complexes with the {O鈥?N,O鈥硙-chelating ligand H2L (2-hydroxyphenylsalicylaldimine) are reported: K[FeL2]路H2O (1), (Pr3NH)[FeL2]路2CH3OH (2), [FeL(bpyO2) (CH3OH)][FeL2]路CH3OH (3), [Fe2L3(CH3OH)]路2CH3OH路H2O (4), and [{Fe2L2}(渭鈥揙H)2{FeL(bpyO2)}2][BPh4]2路2H2O (5), where Pr3NH+ represents the tripropylammonium cation and bpyO2 stands for 2,2鈥?bipyridine-N-dioxide. A thorough density functional theory (DFT) study of magnetic interactions (the isotropic exchange) at the B3LYP/def-TZVP level of theory was employed, and calculations have revealed superexchange pathways through intramolecular/intermolecular noncovalent contacts (蟺鈥撓€ stacking, C鈥揌路路路O and O鈥揌路路路O hydrogen bonds, diamagnetic metal cations) and/or covalent bonds ((渭-OPh, 渭-OH) or bis(渭-OPh) bridging modes), which helped us to postulate trustworthy spin Hamiltonians for magnetic analysis of experimental data. Within the reported family of compounds 1鈥?b>5, the mediators of the antiferromagnetic exchange can be sorted by their increasing strength as follows: 蟺鈥撓€ stacking (JDFT = 鈭?.022 cm鈥?/Jmag = 鈭?.025(4) cm鈥? in 2) < C鈥揌路路路O contacts and 蟺鈥撓€ stacking (JDFT = 鈭?.19 cm鈥?/Jmag = 鈭?.347(9)cm鈥? in 1) < O鈥揌路路路O hydrogen bonds (JDFT = 鈭?.53 cm鈥?/Jmag = 鈭?.41(1) cm鈥? in 3) < bis(渭-OPh) bridge (JDFT = 鈭?3.8 cm鈥?/Jmag = 鈭?2.3(9) cm鈥? in 4) < (渭-OPh, 渭-OH) bridge (JDFT = 鈭?8.0 cm鈥?/Jmag = 鈭?7.1(2) cm鈥? in 5), where JDFT and Jmag are the isotropic exchange parameters derived from DFT calculations, and analysis of the experimental magnetic data, respectively. The good agreement between theoretically calculated and experimentally derived isotropic exchange parameters suggests that this procedure is applicable also for other chemical and structural systems to interpret magnetic data properly.