An official website of the United States government
Abstract The copper(I), silver(I), and gold(I) metals bind π‐ligands by σ‐bonding and π‐back bonding interactions. These interactions were investigated using bidentate ancillary ligands with electron donating and withdrawing substituents. The π‐ligands span from ethylene to larger terminal and internal alkenes and alkynes. Results of X‐ray crystallography, NMR, and IR spectroscopy and gas phase experiments show that the binding energies increase in the order Ag
more »
« less
This content will become publicly available on July 22, 2026
Interstitial Atoms and the Frustrated and Allowed Structural Transitions Principle: Tunability in the Electronic Structure of AuCu3‐type Frameworks in Dy4T1−xGa12 (T = Ag, Ir)
In this Article, we explore how the chemical pressure (CP) features of an intermetallic phase may provide opportunities to couple perturbations in electron count with the stabilization of the underlying geometrical structure. AuCu3‐type LnGa3 (Ln = lanthanide or group 3 metal) phases contain octahedral cavities of negative CP held open by overly compressed Ln–Ga interactions, leading to a series of transition metal‐stuffed derivatives. We present new additions to this family with the synthesis and crystal structures of Dy4T1−xGa12 with (T, x) = (Ag, 0.29) and (Ir, 0.15), adopting Y4PdGa12‐type superstructures of the AuCu3‐type. Density Functional Theory (DFT)‐CP calculations, when adjusted to avoid dipolar CP features, affirm that T atom incorporation provides a mechanism for the relief of packing tensions, while electronic density of states distributions illustrate that the T atoms serve largely as electron or hole donors to the band structure, as needed for them to attain d10 configurations. The maximum obtainable value for x may be limited by a mismatch between the Fermi energy and pseudogap, in line with the balance of factors envisioned by the frustrated and allowed structural transitions principle. Trends in resistivity measurements on T = Ir, Pd, and Ag compounds are interpretable in terms of the varying degrees of disorder arising from x< 1.0.
more »
« less
- PAR ID:
- 10637623
- Publisher / Repository:
- Wiley-VCH
- Date Published:
- Journal Name:
- Zeitschrift für anorganische und allgemeine Chemie
- Volume:
- 651
- Issue:
- 11
- ISSN:
- 0044-2313
- Page Range / eLocation ID:
- e202500079
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
A series of multinuclear metallocenes composed of a t Bu salophen dianion bound to two rare earth metal ions, where each is encased in a bis-pentamethylcyclopentadienyl scaffold, was realized. The isolated molecules (Cp* 2 RE) 2 (μ- t Bu salophen), where RE = Gd (1), Dy (2), and Y (3), constitute the first salophen-bridged metallocene complexes for any metal ion. 1–3 were characterised by X-ray crystallography, cyclic voltammetry, IR, NMR, and UV-Vis-NIR spectroscopy. Cyclic voltammograms of 1–3 excitingly exhibit quasi-reversable features attributed to the ( t Bu salophen 2− / t Bu salophen 3− ˙) redox couple. DFT calculations on 3 uncovered the highest occupied molecular orbital to be primarily localized on the metallocene and phenolate moieties of the t Bu salophen ligand. Furthermore, the nuclear spin I = ½ for yttrium allowed the collection of 89 Y NMR spectra for 3. Magnetic studies revealed slow magnetic relaxation, placing 2 among dysprosocenium-based single-molecule magnets containing a doubly anionic ligand in the equatorial plane.more » « less
-
Abstract The high critical superconducting temperatures (Tcs) of metal hydride phases with clathrate‐like hydrogen networks have generated great interest. Herein, we employ the Density Functional Theory‐Chemical Pressure (DFT‐CP) method to explain why certain electropositive elements adopt these structure types, whereas others distort the hydrogenic lattice, thereby decreasing theTc. The progressive opening of the H24polyhedra in MH6phases is shown to arise from internal pressures exerted by large metal atoms, some of which may favor an even higher hydrogen content that loosens the metal atom coordination environments. The stability of the LaH10and LaBH8phases is tied to stuffing of their shared hydrogen network with either additional hydrogen or boron atoms. The predictive capabilities of DFT‐CP are finally applied to the Y−X−H system to identify possible ternary additions yielding a superconducting phase stable to low pressures.more » « less
-
Metal-metal bonding interactions can engender outstanding magnetic properties in bulk materials and molecules, and examples abound for the transition metals. Extending this paradigm to the lanthanides, herein we report mixed-valence dilanthanide complexes (Cp iPr5 ) 2 Ln 2 I 3 (Ln is Gd, Tb, or Dy; Cp i Pr5 , pentaisopropylcyclopentadienyl), which feature a singly occupied lanthanide-lanthanide σ-bonding orbital of 5 d z 2 parentage, as determined by structural, spectroscopic, and computational analyses. Valence delocalization, wherein the d electron is equally shared by the two lanthanide centers, imparts strong parallel alignment of the σ-bonding and f electrons on both lanthanides according to Hund’s rules. The combination of a well-isolated high-spin ground state and large magnetic anisotropy in (Cp iPr5 ) 2 Dy 2 I 3 gives rise to an enormous coercive magnetic field with a lower bound of 14 tesla at temperatures as high as 60 kelvin.more » « less
-
We report here the characterization in solution (NMR, luminescence, MS) and the solid-state (X-ray crystallography, IR) of complexes between phenacyldiphenylphosphine oxide and five Ln( iii ) ions (Sm, Eu, Gd, Tb, Dy). Four single crystal X-ray structures are described here showing a 1 : 2 ratio between the Ln 3+ ions Eu, Dy, Sm and Gd and the ligand, where the phosphine oxide ligands are bound in a monodentate manner to the metal center. A fifth structure is reported for the 1 : 2 Eu(NO 3 ) 3 -ligand complex showing bidentate binding between the two ligands and the metal center. The solution coordination chemistry of these metal complexes was probed by 1 H, 13 C and 31 P NMR, mass spectrometry, and luminescence experiments. The title ligand has the capability to sensitize Tb 3+ , Dy 3+ , Eu 3+ and Sm 3+ leading to metal-centered emission in solutions of acetonitrile and methanol and in the solid state.more » « less
