Investigations on the Spin States of Two Mononuclear Iron(II) Complexes Based on N-Donor Tridentate Schiff Base Ligands Derived from Pyridine-2,6-Dicarboxaldehyde

Iron(II)-Schiff base complexes are a well-studied class of spin-crossover (SCO) active species due to their ability to interconvert between a paramagnetic high spin-state (HS, S = 2, $^{5}$T$_{2}$) and a diamagnetic low spin-state (LS, S = 0, $^{1}$A$_{1}$) by external stimuli under an appropriate ligand field. We have synthesized two mononuclear FeII complexes, viz., [Fe(L$^{1}$)$_{2}$](ClO$_{4}$)$_{2}$.CH$_{3}$OH (1) and [Fe(L$^{2}$)$_{2}$](ClO$_{4}$)$_{2}$.2CH$_{3}$CN (2), from two N$_{6}$–coordinating tridentate Schiff bases derived from 2,6-bis[(benzylimino)methyl]pyridine. The complexes have been characterized by elemental analysis, electrospray ionization–mass spectrometry (ESI-MS), Fourier-transform infrared spectroscopy (FTIR), solution state nuclear magnetic resonance spectroscopy, $^{1}$H and $_{13}$C NMR (both theoretically and experimentally), single-crystal diffraction and magnetic susceptibility studies. The structural, spectroscopic and magnetic investigations revealed that 1 and 2 are with Fe–N$_{6}$ distorted octahedral coordination geometry and remain locked in LS state throughout the measured temperature range from 5–350 K

A series of four novel alkaline earth metal–organic frameworks constructed of Ca( ii ), Sr( ii ), Ba( ii ) ions and tetrahedral MTB linker: structural diversity, stability study and low/high-pressure gas adsorption properties

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CCDC 144311: Experimental Crystal Structure Determination

Related Article: R.Gyepes, P.T.Witte, M.Horacek, I.Cisarova, K.Mach|1998|J.Organomet.Chem.|551|207|doi:10.1016/S0022-328X(97)00430-0,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 144310: Experimental Crystal Structure Determination

Related Article: R.Gyepes, P.T.Witte, M.Horacek, I.Cisarova, K.Mach|1998|J.Organomet.Chem.|551|207|doi:10.1016/S0022-328X(97)00430-0,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 144312: Experimental Crystal Structure Determination

Related Article: R.Gyepes, P.T.Witte, M.Horacek, I.Cisarova, K.Mach|1998|J.Organomet.Chem.|551|207|doi:10.1016/S0022-328X(97)00430-0,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Spin state of two mononuclear iron(II) complexes of a tridentate bis(imino)pyridine N-donor ligand: Experimental and theoretical investigations

Investigations on the spin states of octahedral Fe(II) complexes have received special attention due to their clear discrimination in the spin states of the d-orbitals. As a means to further understand the factors that influence the spin-crossover (SCO) phenomenon in Fe(II) systems, we herein report two mononuclear Fe(II) complexes, [FeL2](ClO4)2·2CH3OH (1) and [FeL2](BF4)2·CH3CN·CH3OH (2), derived from a novel N3-donor Schiff base ligand, 2,6-bis[(3-methylbenzylimino)methyl]pyridine (L) with varying counteranion and the diamagnetic [ZnL2](BF4)2 congener for a comparative investigation. The complexes have been synthesized and characterized by electrospray-ionization mass spectrometry (ESI-MS), Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy, single-crystal X-ray diffraction (XRD) and magnetic susceptibility studies. Structural and magnetic investigations reveal that both 1 and 2 show Fe__N6 distorted octahedral geometry and are locked in the diamagnetic LS state throughout the entire explored temperature range from 1.8 to 400 K. The LS state of [FeL2]2+ is also confirmed by comparing the experimentally found structural parameters, NMR chemical shifts and excitation energies in the visible region with density functional theory (DFT) calculations

Stereoselective Cyclopropanation of Boron Dipyrromethene (BODIPY) derivatives by an organocascade reaction

The synthesis of enantiopure chiral boron dipyrromethenes (BODIPYs) is of importance due the intrinsic properties of BODIPYs as fluorophores that could be used as probes for molecular sensing. The present study reports an asymmetric organocatalytic cascade reaction of meso-chloromethyl BODIPY derivatives with α,β-unsaturated aldehydes catalyzed by a chiral secondary amine. The corresponding BODIPY-derived cyclopropanes were produced in isolated yields 66–98%, and with diastereomeric ratios 3/2->20/1, and 92–99% ee for major diastereomer. The synthetic utility of the protocol was exemplified on a set of additional transformations of the corresponding optically pure compounds. In addition, a study explaining the reaction mechanism (DFT computations) and photophysical characterization of all enantioenriched products were accomplished