RESUMO
The self-assembly of [Co(MeTPyA)(CH3COO)]PF6 (1) and [Fe(bbp)(CN)3]2- affords a cyanido-bridged square-shaped {Fe2Co2} tetranuclear complex, [{Co(MeTPyA)(µ2-NC)2Fe(bbp)(CN)}2]·3H2O (2; MeTPyA = tris((3,5-dimethylpyrazol-1-yl)methyl)amine and H2bbp = bis(2-benzimidazolyl)pyridine). The possibility of inducing an intramolecular electron transfer coupled spin transition in 2 by employing protonation as an external stimulant is explored. UV-visible spectrophotometric measurements, electrochemical and 1H NMR studies establish that a reversible intramolecular electron transfer coupled spin transition can be triggered in 2 upon addition of either acid or base.
RESUMO
Halide double perovskites are a promising class of semiconducting materials for applications in solar cells and other optoelectronic devices. Recently, there has been a surge of interest in these materials to study phenomena beyond optoelectronics, especially magnetism. Here, we report three new Mo3+ (4d3) based chloride double perovskites: a 3-D rock-salt ordered Cs2NaMoCl6, a 1-D chain (MA)2AgMoCl6 and a Dion-Jacobson type 2-D layered (1,4-BDA)2AgMoCl8 (MA = methylammonium; 1,4-BDA = 1,4-butanediammonium). Their structures and dimensionalities can be tuned by means of the A-cation. The measured bandgaps are relatively narrow (2.0-2.1 eV) which show a blueshift on reducing the dimensionality. At low temperatures, we observe antiferromagnetic coupling between the nearest-neighbour Mo3+ ions in all these systems. Cs2NaMoCl6 shows stronger coupling with a frustration index f of 5 which we attribute to the geometrically frustrating fcc lattice of Mo3+ ions. This work expands the scope of halide double perovskites beyond main group metals and beyond optoelectronics, and we hope that it will lead to future developments in magnetic halide perovskites.
RESUMO
[This corrects the article DOI: 10.1039/D3SC00132F.].
RESUMO
The possibility to induce intra-molecular metal-to-metal charge transfer in a cyanido bridged tetranuclear square shaped {Fe2Ni2} complex by employing protonation as an external stimulant is explored. Two cyanido bridged square shaped tetranuclear complexes, [{Ni(TPA)(µ2-NC)2Ni(CN)2}2]·4H2O (2) and [{Ni(TPA)(µ2-NC)2Fe(bbp)(CN)}2]·10H2O (3) [TPA = tris(3,5-dimethylpyrazol-1-ylmethyl)amine and H2bbp = bis(2-benzimidazolyl)pyridine], are synthesized and characterized. Low temperature magnetic measurements reveal that complex 3 has dominant ferromagnetic interactions between low-spin FeIII (S = 1/2) and high-spin NiII (S = 1) ions. UV-visible spectrophotometric measurements and electrochemical studies establish that reversible intra-molecular metal-to-metal electron transfer can be triggered in 3 upon the addition of either an acid or a base.
RESUMO
A water processable cyanido bridged extended chiral heterobimetallic Co(ii)-Fe(iii) network is assembled. The unusual water processability of the coordination polymer originates from dangling hydrophilic substituents. The present approach offers a simple route to impart solution processability to cyanido bridged molecular magnetic materials.
RESUMO
The effect of subtle structural distortions on single ion magnetic anisotropy of pentagonal bipyramidal Ni(ii) complexes was probed by magnetization measurements and theoretical calculations. Reducing structural distortion on the equatorial pentagonal plane and employing strong field ligands on axial coordination sites dramatically enhance the uniaxial magnetic anisotropy in pentagonal bipyramidal Ni(ii) complexes.