Cheng-Qi Jiao

A Series of Linear {FeIII2FeII} Complexes with Paramagnetic Building‐Block‐Modified Spin Crossover Behaviors

Tuning of the spin crossover (SCO) behavior through paramagnetic building blocks with different steric hindrance effects is of great interest in terms of the synergy between SCO and magnetic interactions. Herein, the steric effect of specified FeIII building blocks is modified, from the large Tp* (hydridotris(3,5-dimethylpyrazol-1-yl)borate) analogue to a small Tp (hydrotris(pyrazolyl)borate) derivative; the FeII SCO unit and FeIII paramagnetic ions are incorporated into three well isolated trinuclear complexes featuring thermally induced and light-induced SCO properties. Reanalysis of the structures reveals that π-π stacking interactions play a key role in the thermal hysteresis and anomalous octahedral distortion parameter Σ around the FeII ion. The Tp* ligand showing the largest steric hindrance induces elongated FeII -N bond lengths and bending of the C≡N-FeII angle in 1, as well as having a relatively large electron donor effect, which leads to the lowest thermal transition temperature among the three compounds.

Coexistence of metamagnetism and single chain magnet behavior in a Fe III 2 Co II layer compound

A cyanide-bridged FeIII2CoII double zigzag chain, {[FeIII(bipy)(CN)4]2CoII(btab)2}n [bipy=2,2′-bipyridine, btab=4,4′-(1,3-phenylene)-bis-4H-1,2,4-triazole] (1), was obtained with tetracyanometalate precursors and CoII ions. The chains were further linked by the ditopic btab ligands to a layer. Magnetic property studies demonstrate that 1 shows both metamagnetism with a critical field Hc=400 Oe and single-chain magnet behavior.

Syntheses, structures, and magnetic properties of three new cyano-bridged heterobimetallic chains based on [Fe(Tp*)(CN)3]−

With the use of the tailored cyanometalate precursor, Bu4N[Fe(Tp*)(CN)3] (Tp* = hydridotris(3,5-dimethylpyrazol-1yl)borate), as the building block to react with fully solvated MII cations, three new one-dimensional (1D) heterobimetallic cyano-bridged chain complexes of squares, {[Fe(Tp*)(CN)3]2M (CH3CH2OH)2}·4H2O (M = Mn(1), Fe(2), Co(3)), have been prepared. In these compounds, the MII ions have slightly distorted octahedral coordination geometries, and they were bridged by [Fe(Tp*)(CN)3]− to form similar 1D chains of squares. The magnetic studies demonstrated that compound 1 exhibited weak ferromagnetism due to spin canting, compound 2 showed ferrimagnetic behavior in a low temperature region, whereas compound 3 indicated the presence of typical antiferromagnetic coupling.

Tuning Assembly and Magnetic Interactions of Cyano-bridged Fe(III)-Mn(II) Bimetallic Chains

Two cyano-bridged Fe(Ⅲ)-Mn(Ⅱ) chains were synthesized via using bidentate ligands and cyanometallate building blocks with different steric hindrance. The magnetic interactions were adjusted by the structural distortions of the two compounds. Compound {[Fe(Ⅲ)(PzTp)(CN) 3 ][Mn(Ⅱ)(5,5′-dmbpy) 2 ]ClO 4 } n ( 1 ; PzTp=tetrakis(pyrazolyl)borate; 5,5′-dmbpy=5,5′-dimethyl-2, 2′-bipyridine) shows a 1D 2, 2- CC chain-like structure with a left-and right-handed helices chains and exhibits the ferrimagnetic behavior. Compound {[Fe(Ⅲ)(Tp * )(CN) 3 ] 2 [Mn(Ⅱ)(dpqc)]·CH 3 OH·H 2 O} n ( 2 ; Tp * =hydridotris(3, 5-dimethylpyrazolyl)borate; dpqc=dipyrido[ 3 , 2- a :2′, 3′- c ]-(6, 7, 8, 9-tetrahydro)phenazine) has a novel 1D 4, 2-ribbon double chain-like structure with dominant antiferromagnetic interactions. CCDC: 1449127, 1 ; 1449128, 2 .