- The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin.
- Spin Crossover in 3D Metal Centers Binding Halide-Containing Ligands.
- Correlations between ligand field Δo, spin crossover T1/2 and redo….
- Guest-Dependent Spin Crossover in a Nanoporous Molecular... - Science.
- Iron(II) Spin Crossover Systems with Multidentate Ligands.
- Spin crossover ligands.
- Spin‐Crossover Tuned Rotation of Pyrazolyl Rings in a 2D Iron(II.
- Spin crossover in mixed ligand iron( iii ) complexes.
- Halogen Substitution Effects on N2O Schiff Base Ligands in.
- A spin-crossover framework endowed with pore-adjustable.
- Spin Crossover Nanoparticles | Journal of Chemical Education.
- Spin-crossover in iron(II)-phenylene ethynylene-2,6-di(pyrazol-1-yl.
- (PDF) Spin-Crossover Complexes.
The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin.
A Mixed-Ligand Approach for Spin-Crossover Modulation in a Linear Fe-II Coordination Polymer Authors: Néstor Calvo Galve Eugenio Coronado University of Valencia Mónica Giménez-Marqués Ecole Normale..
Spin Crossover in 3D Metal Centers Binding Halide-Containing Ligands.
Ligand eld in spin-crossover complexes can be chemically modulated to precisely tune the crossover temperature (T 1/2), de ned as the temperature at which the low-spin and high-spin states are equally populated,13 to near 37 C. Indeed, the utility of spin-crossover in MR thermometry has been demonstrated through T* 2 modulation in Fe. We synthesized an Fe(II) [2 × 2] molecular grid with pyridyl-substituted bis-terdentate ligands. The molecular grid showed abrupt spin crossover between fully high-spin and fully low-spin states in a narrow temperature width of ∼10 K. The spin crossover event also included a first-order structural phase transition, in which the dielectric constant jumped atypically toward a low-spin state.
Correlations between ligand field Δo, spin crossover T1/2 and redo….
OSTI.GOV Journal Article: Thermal Spin Crossover Behaviour of Two-Dimensional Hofmann-Type Coordination Polymers Incorporating Photoactive Ligands.
Guest-Dependent Spin Crossover in a Nanoporous Molecular... - Science.
The influence of a coordinated π-radical on the spin crossover properties of an octahedral iron(II) complex was investigated by preparing and isolating the iron(II) complex containing the tetradentate N,N'-dimethyl-2,11-diaza[3.3](2,6)pyridinophane and the radical anion of N,N'-diphenyl-acenaphtene-1,2-diimine as ligands. This spin crossover. The current report presents a straightforward synthesis of two new air-stable Fe(II) spin-crossover complexes based on β-diimine ligands, namely [Fe(Me bik) 2 (NCS) 2], 1, and [Fe(Me bik) 2 (NCSe) 2], 2, which are reminiscent of the well-known [Fe II (phen) 2 (NCX) 2] complexes. The magnetic studies reveal the occurrence of weakly cooperative. Made available by U.S. Department of Energy Office of Scientific and Technical Information.
Iron(II) Spin Crossover Systems with Multidentate Ligands.
Variable temperature magnetic susceptibility measurements indicate that 1(+) and 2(+) undergo gradual half spin crossover, despite having cis O donors. DFT calculations reveal a small HS-LS gap in the Mn-III systems consistent with spin crossover and provide insight into the ligand design necessary for spin crossover in cis-N4O2 Mn-III compounds. State to a high-spin (S = 2) state.6 Changes in the steric and/or electronic properties of the ligands bound to the metal center are known to alter the spin-crossover behavior, which can most concisely be described by the so-called spin-crossover temperature (T 1/2), that is, the temperature at which both spin states are equally populated. In addition to the aforementioned interests, it is well known that pyrazole- and pyrazolate-derived ligands can generate iron(ii) spin crossover (sco) active complexes [9], [12], in which the paramagnetic t2g4eg2high spin state (hs) can be switched to the diamagnetic t2g6low spin state (ls) by means of an external stimulus like temperature,.
Spin crossover ligands.
Molecular design of spin‐crossover complexes relies on controlling the spin state of a transition metal ion by proper chemical modifications of the ligands. Here we report the first N,N'‐disubstituted 2,6‐bis(pyrazol‐3‐yl)pyridines (3‐bpp) that, against the common wisdom, induce a spin‐crossover in otherwise high‐spin iron(II. The magnetic studies show the presence of gradual SCO behavior for the three complexes: a one-step transition around 205 K for 1 and two step-transitions for compounds 2 and 3, centred at 245 K and 380 K for 2, and at 170 K and 298 K for 3. The magnetic behaviors of complexes 1 and 2 remain unchanged when heating up to 500 K, while complex 3. In order to explore a way to tailor thermal hysteresis behavior of spin-crossover (SCO) complexes, a series of seven Fe II (LX 2) complexes with different ligand configurations has been designed or reconstructed.These Fe II (LX 2) complexes differ in axial ligands X = Py, CNPY, NC 5 H 4 CH 3, NC 5 H 4 OCH 3, NC 5 H 4 Cl, X = NC 5 H 4 Br, and Him. Geometric structure, electronic structure, and.
Spin‐Crossover Tuned Rotation of Pyrazolyl Rings in a 2D Iron(II.
Magnetic measurements reveal that complexes 1 and 2 exhibit different thermal spin-crossover behavior. Complex 1 shows a crystalline solvent effect on spin crossover (SCO). After desorption of the crystalline solvent by heating, an abrupt one-step transition with a hysteresis loop was observed for the desolvated form 1′.. Ligands from a Closed-Shell to an Open-Shell State R. DOLAI, M. GRAF, H. KELM AND H.-J. KRÜGER Department of Chemistry, University of Kaiserslautern, Kaiserslautern, Germany.... state of an organic moiety triggered by a metal-based temperature-induced spin-crossover process is documented here for the first time and opens up new ways to.
Spin crossover in mixed ligand iron( iii ) complexes.
Halogen Substitution Effects on N 2 O Schiff Base Ligands in Unprecedented Abrupt Fe II Spin Crossover Complexes Wasinee Phonsri, David S Macedo, Kuduva R. Vignesh, Gopalan Rajaraman, Casey G. Davies, Guy N L Jameson, Boujemaa Moubaraki, Jas S. Ward, Paul E Kruger, Guillaume Chastanet, Keith S Murray.
Halogen Substitution Effects on N2O Schiff Base Ligands in.
Low-spin (S = 0) states with light (i.e. the LIESST effect) 19,20,21 or heat makes spin-crossover complexes attractive targets for applications in memory, displays, sensors, and, most relevantly, switches.22 Combining spin-crossover phenomena with appropriate organic ligands is therefore a compelling strategy for generating switchable diradicals.
A spin-crossover framework endowed with pore-adjustable.
Spin crossover phenomenon. Spin crossover is defined as reversible spin change in the metal centre of coordination compound which can be triggered by external perturbation, i.e. temperature (T), pressure (p), magnetic or electric field (B and E) and by light irradiation (hυ) (Halcrow 2013).Occurrence of SCO is most likely observed in the coordination compounds with. The crystal structures of five new iron(II) complexes were determined by X-ray diffraction: those of 1, 3, and 4 and two modifications of 3 (3B) and 4 (4B). Complexes 1 and 3B display incomplete spin crossover (SCO) behavior because of a freezing-in effect, whereas 3 and 4B undergo gradual and incomplete SCO behaviors. The past decade has witnessed intense research activity in the area of Fe(II) spin crossover coordination polymers, which are structurally diverse and functionally intriguing materials. In this endeavor, a less exploited series of ligands have been selected among various N-donor triazole and tetrazole molecules.
Spin Crossover Nanoparticles | Journal of Chemical Education.
In some cases, ligands can create an energy field in which the value of the spin pairing energy (P) and the splitting energy of the ligand field (∆ o) are approximately the same (intersection point, crossover), so the influence of an external stimulus can lead to a reversible switch between HS and LS-states (Hauser 2004). Fe(III) spin crossover research field. Section 2 deals with Fe(III) spin transi-tion materials containing ligands with chalcogen donor atoms, such as the dithiocarbamates, whereas Sect. 3 focuses on the use of multidentate Schiff base-type ligands to generate Fe(III) spin crossover. Concluding remarks may be found in Sect. 4. 2. Thermal Spin Crossover Behaviour of Two-Dimensional Hofmann-Type Coordination Polymers Incorporating Photoactive Ligands Florence Ragon A, Korcan Yaksi A, Natasha F. Sciortino A, Guillaume Chastanet B, Jean-François Létard B, Deanna M. D'Alessandro A, Cameron J. Kepert A and Suzanne M. Neville A C.
Spin-crossover in iron(II)-phenylene ethynylene-2,6-di(pyrazol-1-yl.
Spin crossover (SCO) in octahedral transition metal complexes can occur in the d 4 -d 7 electron configurations.1 While systems with d 5 -d 7 electron configurations....14 Significantly, strong‐field ligands, such as phosphanes or cyclopentadienyl ligands coordinate to the Cr II ion to allow for SCO. Spin crossover (SCO) is a phenomenon seen in 3d4-3d7octa- hedral metal complexes when the ligand eld is 'just right' so that the application of an external stimulus, including temperature, pressure, light irradiation and guest molecules, causes a reversible switch of spin state, from HS to LS.1-3This.
(PDF) Spin-Crossover Complexes.
All complexes exhibit temperature-induced spin crossover (SCO), but the SCO temperature is substantially lower for complexes 1a and 1b as compared to 2a and 2b, indicating the stronger ligand field afforded by the N2S2-coordinating bpte ligand relative to the N4-coordinating tpma.
Other links: