Series of high spin mononuclear iron(iii) complexes with Schiff base ligands derived from 2-hydroxybenzophenones

Abstract

Utilization of 2-hydroxybenzophenone derivatives for the preparation of iron(iii) Schiff base complexes resulted in a series of high-spin, mostly antiferromagnetically coupled systems.

Impact of Substituent Variation on the Presence of Thermal Spin Crossover in a Series of Mononuclear Iron(III) Schiff Base Complexes with Terminal Pseudohalido Co‐ligands

“…[12] However,t he pure HS state behaviour was observed in seven corresponding mononuclear iron(III) pseudohalido complexes containing diethylenetriamineo rdipropylenetriamine moieties in the used ligands H 2 L 5 .T his is in agreement with the previously studied iron(III) complexes containing pentadentate SB ligands originating from salicylaldehyde derivatives, and the same symmetric aliphatic amines that also exhibit HS state behaviour. [12] However,t he pure HS state behaviour was observed in seven corresponding mononuclear iron(III) pseudohalido complexes containing diethylenetriamineo rdipropylenetriamine moieties in the used ligands H 2 L 5 .T his is in agreement with the previously studied iron(III) complexes containing pentadentate SB ligands originating from salicylaldehyde derivatives, and the same symmetric aliphatic amines that also exhibit HS state behaviour.…”

“…In order to raise the intermolecularc ooperativity through pp interactions, we have recently employed 2-hydroxybenzo-phenoned erivatives for the preparation of pentadentateS Bl igands. [12] However,t he pure HS state behaviour was observed in seven corresponding mononuclear iron(III) pseudohalido complexes containing diethylenetriamineo rdipropylenetriamine moieties in the used ligands H 2 L 5 .T his is in agreement with the previously studied iron(III) complexes containing pentadentate SB ligands originating from salicylaldehyde derivatives, and the same symmetric aliphatic amines that also exhibit HS state behaviour. [9][10][11] Thus, it is apparent that the symmetry and length of the aliphatic parts of the corresponding pentadentate SB ligandsp lays ac rucial role in the presence of SCO phenomenon.V ast majority of SCO activef erric compounds with pentadentate N 3 O 2 -donor ligands contains asymmetric N,N-ethylene-propyleneamine aliphatic parta nd cis-O 2 / mer-N 3 arrangement in coordination polyhedra.…”

“…Compounds 1 and 2 exhibit the above room temperature SCO with the onset around 300 K. Magnetic curves of both compounds (1 and 2)a re consistentw ithin several cooling and heatingc ycles, bellow temperatures of decomposition (468 Kf or 1 and 511Kfor 2), ( Figure S10). Since the sign of the D parameter forH So ctahedral iron(III) systemscannot be unambiguously obtained from magnetic experiments on powder samples [12,38] the alternative calculations with opposite signs of the parameter D were performed and their optimum values are presented in Ta ble4. Therefore, the characteristic temperatures T 1/2 at 441 K( compound 1)a nd 435 K( compound 2)w ered etermined according to Equation S5 (see the Supporting information for the definition of the characteristic temperature).…”

High‐Spin Mononuclear Iron(III) Complexes with Pentadentate Schiff Base Ligands: Structural Analysis and Magnetic Properties

“…Usually cheap reactants, relatively simple synthesis and versatile coordination opportunities allow preparation of various ligands as well as coordination compounds. Application potential of SB complexes containing transition metal ions is investigated in various fields of research, e. g. catalysis,, biological activity, or magnetochemical research …”

“…The pentadentate ligand occupies five of six coordination positions forming thus a N 3 O 2 ‐donor sphere which can acquire several different topological and enantiomeric configurations (Figure a–c) . The sixth position in the coordination sphere can be finally modified by replacement of chlorido ligand with miscellaneous terminal or bridging ligands, e. g. pseudohalido ligands . N‐ or O‐donor aromatic heterocyclic ligands, or metalocyanates ,,.…”