22 research outputs found
Complexes heptacoordinés de Fe(II) chiraux de géométrie bipyramide pentagonale : vers des aimants moléculaires combinant propriétés magnétiques et optiques
L'Ă©tude dĂ©crite dans ce mĂ©moire concerne la synthĂšse et la caractĂ©risation de complexes chiraux de FeII de gĂ©omĂ©trie bipyramide pentagonale. La chiralitĂ© est introduite par un ligand macrocyclique azotĂ© en interaction pentadente en position Ă©quatoriale de la sphĂšre de coordination du FeII. Les propriĂ©tĂ©s magnĂ©tiques des deux Ă©nantiomĂšres d'une sĂ©rie de complexes de formulations [Fe(LN5RR/SS)(MeOH)Cl]Cl et [Fe(LN5RR/SS)(MeCN)2] (PF6)2 ont Ă©tĂ© Ă©tudiĂ©es. Leur anisotropie magnĂ©tique est caractĂ©risĂ©e par un paramĂštre de ZFS D de -6 et -8 cm-1 respectivement. Ces complexes de FeII ont Ă©tĂ© utilisĂ©s comme source d'anisotropie magnĂ©tique de polymĂšres de coordination 1D hĂ©tĂ©ronuclĂ©aires par association avec des cyanomĂ©tallates. Une chaine [FeNi] obtenue avec la brique diamagnĂ©tique [Ni(CN)4]2- nous a permis de sonder l'anisotropie magnĂ©tique locale du FeII ; elle est caractĂ©risĂ©e par un paramĂštre axial de ZFS D = -10.2 cm-1. La chaine [FeCr], formĂ©e avec le mĂ©tallo-ligand paramagnĂ©tique [Cr(LN3O2Ph)(CN)2]-, constitue le premier exemple de SCM chirale Ă base de complexes PBP. Elle est caractĂ©risĂ©e par des interactions ferromagnĂ©tiques JFeCr = 2.82 cm-1 et une barriĂšre Ă©nergĂ©tique de renversements de spins Ueff/kB = 22 K. Par ailleurs, ces chaines ont Ă©galement montrĂ© que la chiralitĂ© locale est Ă©tendue au niveau supramolĂ©culaire sous la forme d'une organisation hĂ©licoĂŻdale. Leur puretĂ© Ă©nantiomĂ©rique a Ă©tĂ© validĂ©e par des mesures de dichroĂŻsme circulaire. Une seconde partie est consacrĂ©e Ă un nouveau ligand pentadente de formulation H2LN3O2NMe2 et une sĂ©rie de complexes de gĂ©omĂ©trie bipyramide pentagonale, [M(H2LN3O2NMe2)XY]Zn avec M = CoII, NiII, MnII et FeII, X = H2O, MeOH et MeCN ; Y = H2O, Br, I et MeCN ; Z = ClO4, Br, I et PF6 ont Ă©tĂ© obtenus et caractĂ©risĂ©s. Les propriĂ©tĂ©s magnĂ©tiques de ces composĂ©s ont Ă©tĂ© Ă©tudieĂ©s pour Ă©valuer l'impact de ce nouveau ligand sur l'anisotropie magnĂ©tique. Ce ligand aussi Ă©tĂ© mis en Ćuvre pour l'Ă©laboration d'un dĂ©rivĂ© di-cyanido de CrIII, Cat[Cr(LN3O2NMe2)(CN)2] avec Cat = K+ et PNP+ (PNP = Bis(triphĂ©nylphosphine)iminium). Le groupements NMe2 conduisent Ă de meilleurs solubilitĂ©s dans les solvants organiques, ce qui devrait permettre une plus grande versatilitĂ© dans l'utilisation de ces complexes.Synthesis and characterization of chiral FeII complexes with pentagonal bipyramid coordination sphere are described. The chirality is introduced in the complexes through a pentadentate nitrogen macrocyclic ligand complexed in the equatorial position of the FeII. The enantiomers of two derivatives, [Fe(LN5RR/SS)(MeOH)Cl]Cl and [Fe(LN5RR/SS)(MeCN)2](PF6)2, were studied. Their were found to exhibit magnetic anisotropy characterized by an axial ZFS D parameter of -6 and -8 cm-1 respectively. These FeII complexes were involved in the synthesis of heteronuclear 1D coordination polymers in association with cyanometallates. An [FeNi] chain, obtained with the diamagnetic [Ni(CN)4]2- allowed us to probe the local magnetic anisotropy of the FeII in such a surrounding; a ZFS parameter D = -10.2 cm-1 was obtained. A [FeCr] chain, formed with the paramagnetic metallo-ligand [Cr(LN3O2Ph)(CN)2]-, is the first example of chiral SCM composed of PBP complexes. It is characterized by ferromagnetic Fe-Cr interactions of JFeCr = 2.82 cm-1 and an energy barrier of spin reversal of Ueff/kB = 22 K. These chains have also shown that local chirality is extended to the supramolecular level in the form of a helical organization. The circular dichroism spectra confirmed their enantiomeric purity. A second part concerns a novel pentadente ligand of formulation H2LN3O2NMe2 and a series of pentagonal bipyramid geometry complexes, [M(H2LN3O2NMe2)XY]Zn with M = CoII, NiII, MnII and FeII, X = H2O, MeOH and MeCN, Y = H2O, Br, I and MeCN and Z = ClO4, Br, I and PF6. Magnetic properties of these compounds were studied to assess the impact of this new ligand on magnetic anisotropy. This ligand was then implemented for the synthesis of a dicyanido Cr complexe Cat[Cr(LN3O2NMe2)(CN)2]- with Cat = K and PNP (PNP = Bis(triphenylphosphine)iminium). The NMe2 groups of the ligand leads to overall better solubilities in organic solvents, which should allow greater versatility in the design of c polynuclear systems
Complexes heptacoordinés de Fe(II) chiraux de géométrie bipyramide pentagonale : vers des aimants moléculaires combinant propriétés magnétiques et optiques
Synthesis and characterization of chiral FeII complexes with pentagonal bipyramid coordination sphere are described. The chirality is introduced in the complexes through a pentadentate nitrogen macrocyclic ligand complexed in the equatorial position of the FeII. The enantiomers of two derivatives, [Fe(LN5RR/SS)(MeOH)Cl]Cl and [Fe(LN5RR/SS)(MeCN)2](PF6)2, were studied. Their were found to exhibit magnetic anisotropy characterized by an axial ZFS D parameter of -6 and -8 cm-1 respectively. These FeII complexes were involved in the synthesis of heteronuclear 1D coordination polymers in association with cyanometallates. An [FeNi] chain, obtained with the diamagnetic [Ni(CN)4]2- allowed us to probe the local magnetic anisotropy of the FeII in such a surrounding; a ZFS parameter D = -10.2 cm-1 was obtained. A [FeCr] chain, formed with the paramagnetic metallo-ligand [Cr(LN3O2Ph)(CN)2]-, is the first example of chiral SCM composed of PBP complexes. It is characterized by ferromagnetic Fe-Cr interactions of JFeCr = 2.82 cm-1 and an energy barrier of spin reversal of Ueff/kB = 22 K. These chains have also shown that local chirality is extended to the supramolecular level in the form of a helical organization. The circular dichroism spectra confirmed their enantiomeric purity. A second part concerns a novel pentadente ligand of formulation H2LN3O2NMe2 and a series of pentagonal bipyramid geometry complexes, [M(H2LN3O2NMe2)XY]Zn with M = CoII, NiII, MnII and FeII, X = H2O, MeOH and MeCN, Y = H2O, Br, I and MeCN and Z = ClO4, Br, I and PF6. Magnetic properties of these compounds were studied to assess the impact of this new ligand on magnetic anisotropy. This ligand was then implemented for the synthesis of a dicyanido Cr complexe Cat[Cr(LN3O2NMe2)(CN)2]- with Cat = K and PNP (PNP = Bis(triphenylphosphine)iminium). The NMe2 groups of the ligand leads to overall better solubilities in organic solvents, which should allow greater versatility in the design of c polynuclear systems.L'Ă©tude dĂ©crite dans ce mĂ©moire concerne la synthĂšse et la caractĂ©risation de complexes chiraux de FeII de gĂ©omĂ©trie bipyramide pentagonale. La chiralitĂ© est introduite par un ligand macrocyclique azotĂ© en interaction pentadente en position Ă©quatoriale de la sphĂšre de coordination du FeII. Les propriĂ©tĂ©s magnĂ©tiques des deux Ă©nantiomĂšres d'une sĂ©rie de complexes de formulations [Fe(LN5RR/SS)(MeOH)Cl]Cl et [Fe(LN5RR/SS)(MeCN)2] (PF6)2 ont Ă©tĂ© Ă©tudiĂ©es. Leur anisotropie magnĂ©tique est caractĂ©risĂ©e par un paramĂštre de ZFS D de -6 et -8 cm-1 respectivement. Ces complexes de FeII ont Ă©tĂ© utilisĂ©s comme source d'anisotropie magnĂ©tique de polymĂšres de coordination 1D hĂ©tĂ©ronuclĂ©aires par association avec des cyanomĂ©tallates. Une chaine [FeNi] obtenue avec la brique diamagnĂ©tique [Ni(CN)4]2- nous a permis de sonder l'anisotropie magnĂ©tique locale du FeII ; elle est caractĂ©risĂ©e par un paramĂštre axial de ZFS D = -10.2 cm-1. La chaine [FeCr], formĂ©e avec le mĂ©tallo-ligand paramagnĂ©tique [Cr(LN3O2Ph)(CN)2]-, constitue le premier exemple de SCM chirale Ă base de complexes PBP. Elle est caractĂ©risĂ©e par des interactions ferromagnĂ©tiques JFeCr = 2.82 cm-1 et une barriĂšre Ă©nergĂ©tique de renversements de spins Ueff/kB = 22 K. Par ailleurs, ces chaines ont Ă©galement montrĂ© que la chiralitĂ© locale est Ă©tendue au niveau supramolĂ©culaire sous la forme d'une organisation hĂ©licoĂŻdale. Leur puretĂ© Ă©nantiomĂ©rique a Ă©tĂ© validĂ©e par des mesures de dichroĂŻsme circulaire. Une seconde partie est consacrĂ©e Ă un nouveau ligand pentadente de formulation H2LN3O2NMe2 et une sĂ©rie de complexes de gĂ©omĂ©trie bipyramide pentagonale, [M(H2LN3O2NMe2)XY]Zn avec M = CoII, NiII, MnII et FeII, X = H2O, MeOH et MeCN ; Y = H2O, Br, I et MeCN ; Z = ClO4, Br, I et PF6 ont Ă©tĂ© obtenus et caractĂ©risĂ©s. Les propriĂ©tĂ©s magnĂ©tiques de ces composĂ©s ont Ă©tĂ© Ă©tudieĂ©s pour Ă©valuer l'impact de ce nouveau ligand sur l'anisotropie magnĂ©tique. Ce ligand aussi Ă©tĂ© mis en Ćuvre pour l'Ă©laboration d'un dĂ©rivĂ© di-cyanido de CrIII, Cat[Cr(LN3O2NMe2)(CN)2] avec Cat = K+ et PNP+ (PNP = Bis(triphĂ©nylphosphine)iminium). Le groupements NMe2 conduisent Ă de meilleurs solubilitĂ©s dans les solvants organiques, ce qui devrait permettre une plus grande versatilitĂ© dans l'utilisation de ces complexes
Heptacoordinated chiral Fe(II) complexes with pentagonal bipyramid geometry : Towards molecular magnets combining magnetic and optic propertiers
L'Ă©tude dĂ©crite dans ce mĂ©moire concerne la synthĂšse et la caractĂ©risation de complexes chiraux de FeII de gĂ©omĂ©trie bipyramide pentagonale. La chiralitĂ© est introduite par un ligand macrocyclique azotĂ© en interaction pentadente en position Ă©quatoriale de la sphĂšre de coordination du FeII. Les propriĂ©tĂ©s magnĂ©tiques des deux Ă©nantiomĂšres d'une sĂ©rie de complexes de formulations [Fe(LN5RR/SS)(MeOH)Cl]Cl et [Fe(LN5RR/SS)(MeCN)2] (PF6)2 ont Ă©tĂ© Ă©tudiĂ©es. Leur anisotropie magnĂ©tique est caractĂ©risĂ©e par un paramĂštre de ZFS D de -6 et -8 cm-1 respectivement. Ces complexes de FeII ont Ă©tĂ© utilisĂ©s comme source d'anisotropie magnĂ©tique de polymĂšres de coordination 1D hĂ©tĂ©ronuclĂ©aires par association avec des cyanomĂ©tallates. Une chaine [FeNi] obtenue avec la brique diamagnĂ©tique [Ni(CN)4]2- nous a permis de sonder l'anisotropie magnĂ©tique locale du FeII ; elle est caractĂ©risĂ©e par un paramĂštre axial de ZFS D = -10.2 cm-1. La chaine [FeCr], formĂ©e avec le mĂ©tallo-ligand paramagnĂ©tique [Cr(LN3O2Ph)(CN)2]-, constitue le premier exemple de SCM chirale Ă base de complexes PBP. Elle est caractĂ©risĂ©e par des interactions ferromagnĂ©tiques JFeCr = 2.82 cm-1 et une barriĂšre Ă©nergĂ©tique de renversements de spins Ueff/kB = 22 K. Par ailleurs, ces chaines ont Ă©galement montrĂ© que la chiralitĂ© locale est Ă©tendue au niveau supramolĂ©culaire sous la forme d'une organisation hĂ©licoĂŻdale. Leur puretĂ© Ă©nantiomĂ©rique a Ă©tĂ© validĂ©e par des mesures de dichroĂŻsme circulaire. Une seconde partie est consacrĂ©e Ă un nouveau ligand pentadente de formulation H2LN3O2NMe2 et une sĂ©rie de complexes de gĂ©omĂ©trie bipyramide pentagonale, [M(H2LN3O2NMe2)XY]Zn avec M = CoII, NiII, MnII et FeII, X = H2O, MeOH et MeCN ; Y = H2O, Br, I et MeCN ; Z = ClO4, Br, I et PF6 ont Ă©tĂ© obtenus et caractĂ©risĂ©s. Les propriĂ©tĂ©s magnĂ©tiques de ces composĂ©s ont Ă©tĂ© Ă©tudieĂ©s pour Ă©valuer l'impact de ce nouveau ligand sur l'anisotropie magnĂ©tique. Ce ligand aussi Ă©tĂ© mis en Ćuvre pour l'Ă©laboration d'un dĂ©rivĂ© di-cyanido de CrIII, Cat[Cr(LN3O2NMe2)(CN)2] avec Cat = K+ et PNP+ (PNP = Bis(triphĂ©nylphosphine)iminium). Le groupements NMe2 conduisent Ă de meilleurs solubilitĂ©s dans les solvants organiques, ce qui devrait permettre une plus grande versatilitĂ© dans l'utilisation de ces complexes.Synthesis and characterization of chiral FeII complexes with pentagonal bipyramid coordination sphere are described. The chirality is introduced in the complexes through a pentadentate nitrogen macrocyclic ligand complexed in the equatorial position of the FeII. The enantiomers of two derivatives, [Fe(LN5RR/SS)(MeOH)Cl]Cl and [Fe(LN5RR/SS)(MeCN)2](PF6)2, were studied. Their were found to exhibit magnetic anisotropy characterized by an axial ZFS D parameter of -6 and -8 cm-1 respectively. These FeII complexes were involved in the synthesis of heteronuclear 1D coordination polymers in association with cyanometallates. An [FeNi] chain, obtained with the diamagnetic [Ni(CN)4]2- allowed us to probe the local magnetic anisotropy of the FeII in such a surrounding; a ZFS parameter D = -10.2 cm-1 was obtained. A [FeCr] chain, formed with the paramagnetic metallo-ligand [Cr(LN3O2Ph)(CN)2]-, is the first example of chiral SCM composed of PBP complexes. It is characterized by ferromagnetic Fe-Cr interactions of JFeCr = 2.82 cm-1 and an energy barrier of spin reversal of Ueff/kB = 22 K. These chains have also shown that local chirality is extended to the supramolecular level in the form of a helical organization. The circular dichroism spectra confirmed their enantiomeric purity. A second part concerns a novel pentadente ligand of formulation H2LN3O2NMe2 and a series of pentagonal bipyramid geometry complexes, [M(H2LN3O2NMe2)XY]Zn with M = CoII, NiII, MnII and FeII, X = H2O, MeOH and MeCN, Y = H2O, Br, I and MeCN and Z = ClO4, Br, I and PF6. Magnetic properties of these compounds were studied to assess the impact of this new ligand on magnetic anisotropy. This ligand was then implemented for the synthesis of a dicyanido Cr complexe Cat[Cr(LN3O2NMe2)(CN)2]- with Cat = K and PNP (PNP = Bis(triphenylphosphine)iminium). The NMe2 groups of the ligand leads to overall better solubilities in organic solvents, which should allow greater versatility in the design of c polynuclear systems
Complexes heptacoordinés de Fe(II) chiraux de géométrie bipyramide pentagonale : vers des aimants moléculaires combinant propriétés magnétiques et optiques
Synthesis and characterization of chiral FeII complexes with pentagonal bipyramid coordination sphere are described. The chirality is introduced in the complexes through a pentadentate nitrogen macrocyclic ligand complexed in the equatorial position of the FeII. The enantiomers of two derivatives, [Fe(LN5RR/SS)(MeOH)Cl]Cl and [Fe(LN5RR/SS)(MeCN)2](PF6)2, were studied. Their were found to exhibit magnetic anisotropy characterized by an axial ZFS D parameter of -6 and -8 cm-1 respectively. These FeII complexes were involved in the synthesis of heteronuclear 1D coordination polymers in association with cyanometallates. An [FeNi] chain, obtained with the diamagnetic [Ni(CN)4]2- allowed us to probe the local magnetic anisotropy of the FeII in such a surrounding; a ZFS parameter D = -10.2 cm-1 was obtained. A [FeCr] chain, formed with the paramagnetic metallo-ligand [Cr(LN3O2Ph)(CN)2]-, is the first example of chiral SCM composed of PBP complexes. It is characterized by ferromagnetic Fe-Cr interactions of JFeCr = 2.82 cm-1 and an energy barrier of spin reversal of Ueff/kB = 22 K. These chains have also shown that local chirality is extended to the supramolecular level in the form of a helical organization. The circular dichroism spectra confirmed their enantiomeric purity. A second part concerns a novel pentadente ligand of formulation H2LN3O2NMe2 and a series of pentagonal bipyramid geometry complexes, [M(H2LN3O2NMe2)XY]Zn with M = CoII, NiII, MnII and FeII, X = H2O, MeOH and MeCN, Y = H2O, Br, I and MeCN and Z = ClO4, Br, I and PF6. Magnetic properties of these compounds were studied to assess the impact of this new ligand on magnetic anisotropy. This ligand was then implemented for the synthesis of a dicyanido Cr complexe Cat[Cr(LN3O2NMe2)(CN)2]- with Cat = K and PNP (PNP = Bis(triphenylphosphine)iminium). The NMe2 groups of the ligand leads to overall better solubilities in organic solvents, which should allow greater versatility in the design of c polynuclear systems.L'Ă©tude dĂ©crite dans ce mĂ©moire concerne la synthĂšse et la caractĂ©risation de complexes chiraux de FeII de gĂ©omĂ©trie bipyramide pentagonale. La chiralitĂ© est introduite par un ligand macrocyclique azotĂ© en interaction pentadente en position Ă©quatoriale de la sphĂšre de coordination du FeII. Les propriĂ©tĂ©s magnĂ©tiques des deux Ă©nantiomĂšres d'une sĂ©rie de complexes de formulations [Fe(LN5RR/SS)(MeOH)Cl]Cl et [Fe(LN5RR/SS)(MeCN)2] (PF6)2 ont Ă©tĂ© Ă©tudiĂ©es. Leur anisotropie magnĂ©tique est caractĂ©risĂ©e par un paramĂštre de ZFS D de -6 et -8 cm-1 respectivement. Ces complexes de FeII ont Ă©tĂ© utilisĂ©s comme source d'anisotropie magnĂ©tique de polymĂšres de coordination 1D hĂ©tĂ©ronuclĂ©aires par association avec des cyanomĂ©tallates. Une chaine [FeNi] obtenue avec la brique diamagnĂ©tique [Ni(CN)4]2- nous a permis de sonder l'anisotropie magnĂ©tique locale du FeII ; elle est caractĂ©risĂ©e par un paramĂštre axial de ZFS D = -10.2 cm-1. La chaine [FeCr], formĂ©e avec le mĂ©tallo-ligand paramagnĂ©tique [Cr(LN3O2Ph)(CN)2]-, constitue le premier exemple de SCM chirale Ă base de complexes PBP. Elle est caractĂ©risĂ©e par des interactions ferromagnĂ©tiques JFeCr = 2.82 cm-1 et une barriĂšre Ă©nergĂ©tique de renversements de spins Ueff/kB = 22 K. Par ailleurs, ces chaines ont Ă©galement montrĂ© que la chiralitĂ© locale est Ă©tendue au niveau supramolĂ©culaire sous la forme d'une organisation hĂ©licoĂŻdale. Leur puretĂ© Ă©nantiomĂ©rique a Ă©tĂ© validĂ©e par des mesures de dichroĂŻsme circulaire. Une seconde partie est consacrĂ©e Ă un nouveau ligand pentadente de formulation H2LN3O2NMe2 et une sĂ©rie de complexes de gĂ©omĂ©trie bipyramide pentagonale, [M(H2LN3O2NMe2)XY]Zn avec M = CoII, NiII, MnII et FeII, X = H2O, MeOH et MeCN ; Y = H2O, Br, I et MeCN ; Z = ClO4, Br, I et PF6 ont Ă©tĂ© obtenus et caractĂ©risĂ©s. Les propriĂ©tĂ©s magnĂ©tiques de ces composĂ©s ont Ă©tĂ© Ă©tudieĂ©s pour Ă©valuer l'impact de ce nouveau ligand sur l'anisotropie magnĂ©tique. Ce ligand aussi Ă©tĂ© mis en Ćuvre pour l'Ă©laboration d'un dĂ©rivĂ© di-cyanido de CrIII, Cat[Cr(LN3O2NMe2)(CN)2] avec Cat = K+ et PNP+ (PNP = Bis(triphĂ©nylphosphine)iminium). Le groupements NMe2 conduisent Ă de meilleurs solubilitĂ©s dans les solvants organiques, ce qui devrait permettre une plus grande versatilitĂ© dans l'utilisation de ces complexes
Trinuclear Cyanido-Bridged [Cr2Fe] Complexes: To Be or not to Be a Single-Molecule Magnet, a Matter of Straightness
International audienceTrinuclear systems of formula [{Cr(LN3O2Ph)(CN)2}2M(H2LN3O2R)] (M=MnII and FeII, LN3O2R stands for pentadentate ligands) were prepared in order to assess the influence of the bending of the apical MâNâĄC linkages on the magnetic anisotropy of the FeII derivatives and in turn on their Single-Molecule Magnet (SMM) behaviors. The cyanido-bridged [Cr2M] derivatives were obtained by assembling trans-dicyanido CrIII complex [Cr(LN3O2Ph)(CN)2]â and divalent pentagonal bipyramid complexes [MII(H2LN3O2R)]2+ with various R substituents (R=NH2, cyclohexyl, S,S-mandelic) imparting different steric demand to the central moiety of the complexes. A comparative examination of the structural and magnetic properties showed an obvious effect of the deviation from straightness of the MâNâĄC alignment on the slow relaxation of the magnetization exhibited by the [Cr2Fe] complexes. Theoretical calculations have highlighted important effects of the bending of the apical CâNâFe linkages on both the magnetic anisotropy of the FeII center and the exchange interactions with the CrIII units
Magnetic anisotropy of transition metal and lanthanide ions in pentagonal bipyramidal geometry
International audienceThe magnetic anisotropy associated with a pentagonal bipyramidal (PBP) coordination sphere is examined on the basis of experimental and theoretical investigations. The origin and the characteristics of this anisotropy are discussed in relation to the electronic configuration of the metal ions. The effects of crystal field, structural distortion, and a second-coordination sphere on the observed anisotropies for transition meal and lanthanide ions are outlined. For the Ln derivatives, we focus on compounds showing SMM-like behavior (i.e. slow relaxation of their magnetization) in order to highlight the essential chemical and structural parameters for achieving strong axial anisotropy. The use of PBP complexes to impart controlled magnetic anisotropy in polynuclear species such as SMMs or SCMs is also addressed. This review of the magnetic anisotropies associated with a pentagonal bipyramidal coordination sphere for transition metal and lanthanide ions is intended to highlight some general trends that can guide chemists towards designing a compound with specific properties
Homochiral SCM Built of Tetrahedral and Pentagonal Bipyramidal Fe(II) Units Bridged by Chlorine
International audienceEach enantiomer of a chiral pentagonal bipyramidal (PBP) FeII complex ([FeLN5R,RCl(MeOH)]Cl·H2O, 1R, or [FeLN5S,SCl(MeOH)]Cl·H2O, 1S) has been obtained using either the R or the S stereoisomer of the macrocyclic pentadentate ligand formed in a template-condensation reaction of the tetraamine N,NâČ-Bis-{(1R,2R)-[2-(amino)]cyclohexyl}-1,2-diaminoethane, or its (1S,2S) enantiomer, and 2,5-diacetylpyridine, respectively LN5R,R and LN5S,S. Subsequently, the 1-D coordination polymers [FeLN5R,R{FeCl4}], 2R, and [FeLN5S,S{FeCl4}], 2S, were formed by reacting respectively 1R or 1S with 1 equiv of FeCl2(H2O)4. These chain compounds consist of an alternation of PBP and tetrahedral FeII units sharing a Cl atom. Theoretical calculations reveal large magnetic anisotropy for each Fe center but of different type with axial zero-field splitting parameter D of respectively â30 cmâ1 and 15 cmâ1. The magnetic behavior for the 1-D compound revealed canted antiferromagnetic FeâFe interactions (J = â6 cmâ1) and SCM behavior characterized by Î/kB = 42 K with pre-exponential factor Ï0 = 2.17 Ă 10â10 s. It was noted that this SCM behavior was accompanied by a magnetic order leading to a weak ferromagnet (i.e., canted antiferromagnet). The preparations, crystal structures (CCDC references 2214580â2214583), spectroscopic data, magnetic behaviors, and theoretical investigations are reported
Homochiral SCM Built of Tetrahedral and Pentagonal Bipyramidal Fe(II) Units Bridged by Chlorine
International audienceEach enantiomer of a chiral pentagonal bipyramidal (PBP) FeII complex ([FeLN5R,RCl(MeOH)]Cl·H2O, 1R, or [FeLN5S,SCl(MeOH)]Cl·H2O, 1S) has been obtained using either the R or the S stereoisomer of the macrocyclic pentadentate ligand formed in a template-condensation reaction of the tetraamine N,NâČ-Bis-{(1R,2R)-[2-(amino)]cyclohexyl}-1,2-diaminoethane, or its (1S,2S) enantiomer, and 2,5-diacetylpyridine, respectively LN5R,R and LN5S,S. Subsequently, the 1-D coordination polymers [FeLN5R,R{FeCl4}], 2R, and [FeLN5S,S{FeCl4}], 2S, were formed by reacting respectively 1R or 1S with 1 equiv of FeCl2(H2O)4. These chain compounds consist of an alternation of PBP and tetrahedral FeII units sharing a Cl atom. Theoretical calculations reveal large magnetic anisotropy for each Fe center but of different type with axial zero-field splitting parameter D of respectively â30 cmâ1 and 15 cmâ1. The magnetic behavior for the 1-D compound revealed canted antiferromagnetic FeâFe interactions (J = â6 cmâ1) and SCM behavior characterized by Î/kB = 42 K with pre-exponential factor Ï0 = 2.17 Ă 10â10 s. It was noted that this SCM behavior was accompanied by a magnetic order leading to a weak ferromagnet (i.e., canted antiferromagnet). The preparations, crystal structures (CCDC references 2214580â2214583), spectroscopic data, magnetic behaviors, and theoretical investigations are reported
Analysis of Cu(In,Ga) Se 2 grading evolution during low deposition temperature co-evaporation process by GD-OES and XPS measurements. Impact on solar cell performances and modelling
International audienc
Analysis of Cu(In,Ga)Se2 grading evolution during low deposition temperature co-evaporation process by GD-OES and XPS measurements. Impact on solar cell performances and modelling
International audienc