64 research outputs found
Hexa-ÎŒ-chlorido-hexaÂchlorido(η6-hexaÂmethylÂbenzene)trialuminium(III)lanthanum(III) benzene solvate
In the title compound, [Al3LaCl12(C12H18)]·C6H6, all molÂecules are located on a mirror plane. Three chloridoaluminate groups and a hexaÂmethylÂbenzene molÂecule are bound to the central lanthanum(III) ion, forming a distorted pentaÂgonal bipyramid with the η6-coordinated arene located at the apical position. The hexaÂmethylÂbenzene ligand disordered between two orientations in a 1:1 ratio is also involved in parallel-slipped ÏâÏ stacking interÂmolecular interÂactions with a benzene solvent molÂecule [centroidâcentroid distance 3.612â
(4)â
Ă
]
Orbital Nature of Carboionic Monoradicals Made from Diradicals
The electronic, optical, and solid state properties of a series of monoradicals, anions and cations obtained from starting neutral diradicals have been studied. Diradicals based on s-indacene and indenoacenes, with benzothiophenes fused and in different orientations, feature a varying degree of diradical character in the neutral state, which is here related with the properties of the radical redox forms. The analysis of their optical features in the polymethine monoradicals has been carried out in the framework of the molecular orbital and valence bond theories. Electronic UVVis-NIR absorption, X-ray solid-state diffraction and quantum
chemical calculations have been carried out. Studies of the different positive-/negative-charged species, both residing in the same skeletal Ï-conjugated backbone, are rare for organic molecules. The key factor for the dual stabilization is the presence of the starting diradical character that enables to indistinctively accommodate a pseudo-hole and a pseudoelectron defect with certainly small reorganization energies for ambipolar charge transport.The authors thank the Spanish Ministry of Science and Innovation (projects MINECO/FEDER PGC2018-098533-B-100
and PID2021-127127NB-I00) and the Junta de AndalucĂa, Spain (UMA18FEDERJA057 and Proyecto de Excelencia PROYEXCEL- 00328). We also thank the Research Central Services (SCAI) of the University of MĂĄlaga and the US National Science Foundation (CHE-1954389 to M.M.H., CHE-2003411 to M.A. P.). F.N and Y.D. acknowledge support from âValutazione della Ricerca di Ateneoâ (VRA)-University of Bologna. Y.D. acknowledges Ministero dellâUniversitĂ e della Ricerca (MUR) for her
Ph.D. fellowship.
Funding for open access charge: Universidad de MĂĄlaga / CBU
Chem. Sci.
The synthesis of a novel family of homoleptic COT-based heterotrimetallic self-assemblies bearing the formula [LnKCa(COT)3(THF)3] (Ln(III) = Gd, Tb, Dy, Ho, Er, Tm, and Yb) is reported followed by their X-ray crystallographic and magnetic characterization. All crystals conform to the monoclinic P21/c space group with a slight compression of the unit cell from 3396.4(2) Ă
3 to 3373.2(4) Ă
3 along the series. All complexes exhibit a triple-decker structure having the Ln(III) and K(I) ions sandwiched by three COT2â ligands with an end-bound {Ca2+(THF)3} moiety to form a non-linear (153.5°) arrangement of three different metals. The COT2â ligands act in a η8-mode with respect to all metal centers. A detailed structural comparison of this unique set of heterotrimetallic complexes has revealed consistent trends along the series. From Gd to Yb, the Ln to ring-centroid distance decreases from 1.961(3) Ă
to 1.827(2) Ă
. In contrast, the separation of K(I) and Ca(II) ions from the COT-centroid (2.443(3) and 1.914(3) Ă
, respectively) is not affected by the change of Ln(III) ions. The magnetic property investigation of the [LnKCa(COT)3(THF)3] series (Ln(III) = Gd, Tb, Dy, Ho, Er, and Tm) reveals that the Dy, Er, and Tm complexes display slow relaxation of their magnetization, in other words, single-molecule magnet (SMM) properties. This behaviour is dominated by thermally activated (Orbach-like) and quantum tunneling processes for [DyKCa(COT)3(THF)3] in contrast to [ErKCa(COT)3(THF)3], in which the thermally activated and Raman processes appear to be relevant. Details of the electronic structures and magnetic properties of these complexes are further clarified with the help of DFT and ab initio theoretical calculation
A Biradical Balancing Act: Redox Amphoterism in a Diindenoanthracene Derivative Results from Quinoidal Acceptor and Aromatic Donor Motifs
The
reduced and oxidized states of an open-shell diindenoÂ[<i>b,i</i>]Âanthracene (<b>DIAn</b>) derivative have been
investigated by experimental and theoretical techniques. As a result
of moderate biradical character and the ability of cyclopenta-fused
scaffolds to stabilize both positive and negative charges, <b>DIAn</b> exhibits rich redox chemistry with four observable and isolable
charged states. Structural and electronic properties of the <b>DIAn</b> system are brought to light by UVâvisâNIR
and Raman spectroelectrochemical measurements. Aromatization of the
diindeno-fused anthracene core upon successive single-electron injections
is revealed through single-crystal X-ray diffraction of radical anion
and dianion salts. We present a rare case where the pseudoaromatic/quinoidal
ground state of a neutral biradical polycyclic hydrocarbon leads to
a stable cascade of five redox states. Our detailed investigation
of the transformation of molecular structure along all four redox
events provides a clearer understanding of the nature of charge carriers
in ambipolar organic field-effect transistors
Mixed Chloride/Phosphine Complexes of the Dirhenium Core. 2. New Reactions Involving Dimethylphenylphosphine
Mixed Chloride/Phosphine Complexes of the Dirhenium Core. 3. Novel Structures with Diethylphosphido-bridges and Terminal Diethylphosphines
Syntheses and Crystal Structures of âUnligatedâ Copper(I) and Copper(II) Trifluoroacetates
Mixed Chloride/Phosphine Complexes of the Dirhenium Core. 6. Rare or Unprecedented Isomers of [Re 2
Mixed Chloride/Phosphine Complexes of the Dirhenium Core. 10. Redox Reactions of an Edge-Sharing Dirhenium(III) Non-metalâMetal-Bonded Complex, Re 2
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