Manganese(iii) hexadentate Schiff base complexes ([Mn(sal-N-1,5,8,12)]Y·S, Y = AsF (1); Y = SbF (2); Y = NO, S = CHOH (3) and Y = Cl (4)) have been investigated to determine the impact of anion effects, intramolecular ligand distortions, and intermolecular supramolecular structures on the spin crossover (SCO) behavior. The crystal structure of [Mn(sal-N-1,5,8,12)]PF, a complex known to exhibit an abrupt SCO behavior with an 8 K hysteresis window, reveals that this complex has a temperature-dependent anion order-disorder transition that disrupts the hydrogen-bonding chain upon SCO, indicating that hydrogen bonds between cations and anions greatly influence the magnetic properties. The SCO in 1 is mediated by intermolecular hydrogen-bonding interactions. The subtle balance of these hydrogen bonds induces a cooperative SCO process with a hysteresis width of 18 K, which is the largest one reported in the d SCO chemistry. For 2, crystal structural analysis indicates that changing the anion from AsF to SbF led to close stackings between phenyl groups from ligands. These stackings preclude the spin transition of the [Mn(sal-N-1,5,8,12)] cations. With NO and Cl as counterions, the [Mn(sal-N-1,5,8,12)] cations are arranged more loosely and exhibit gradual SCO in the temperature range of 300-100 K. Careful evaluation of the supramolecular structures of these complexes and similar complexes reported previously revealed strong correlation between the supramolecular packing forces and their magnetic properties.
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Angew Chem Int Ed Engl
January 2025
IISER Kolkata: Indian Institute of Science Education and Research Kolkata, Department of Chemical Sciences, Mohanpur, 741246, Nadia, INDIA.
Chiral allyl amines are important structural components in natural products, pharmaceuticals, and chiral catalysts. Herein, we report a cobalt-catalyzed enantioselective reductive coupling of imines with internal alkynes to synthesize chiral allyl amines. The reaction is catalyzed by a cobalt complex derived from commercially available bisphosphine ligand utilizing zinc as the electron donor.
View Article and Find Full Text PDFInorg Chem
January 2025
School of Chemistry, University of Melbourne, Parkville 3010, Victoria, Australia.
A search for switchable molecules has afforded a family of cobalt complexes featuring derivatives of 2-aminophenol: 4,6-di--butyl aminophenol (HL) and 2-anilino-4,6-di--butyl aminophenol (HL). The heteroleptic cobalt complexes incorporate a Metpa ligand (tpa = tris(2-pyridylmethyl)amine; = 0-3), which involves the methylation of the 6-position of the pyridine ring). Eight members of this family have been synthesized and characterized: [Co(HL)(tpa)](BPh) (), [Co(HL)(Metpa)](BPh) (), [Co(L)(Metpa)](BPh) (), [Co(HL)(Metpa)](BPh) (), [Co(L)(Metpa)](BPh) (), [Co(HL)(tpa)] (BPh)(ClO) (), [Co(L)(tpa)](BPh)(ClO) () and [Co(HL)(Metpa)](BPh) (), where the aminophenol-derived ligands are monoanionic in either the open shell radical iminosemiquinonate (L) or the closed shell protonated aminophenolate (HL).
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, 01187 Dresden, Germany.
Superdiffusion is surprisingly easily observed even in systems without the integrability underpinning this phenomenon. Indeed, the classical Heisenberg chain-one of the simplest many-body systems, and firmly believed to be nonintegrable-evinces a long-lived regime of anomalous, superdiffusive spin dynamics at finite temperature. Similarly, superdiffusion persists for long timescales, even at high temperature, for small perturbations around a related integrable model.
View Article and Find Full Text PDFNat Commun
January 2025
Institute for Quantum Computing, University of Waterloo, Waterloo, ON, Canada.
Landau-Zener tunneling, which describes the transition in a two-level system during a sweep through an anti-crossing, is a model applicable to a wide range of physical phenomena. Realistic quantum systems are affected by dissipation due to coupling to their environments. An important aspect of understanding such open quantum systems is the relative energy scales of the system itself and the system-environment coupling, which distinguishes the weak- and strong-coupling regimes.
View Article and Find Full Text PDFAdv Mater
January 2025
Department of Materials Science and Engineering, Yonsei University, Seoul, 03722, Republic of Korea.
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