Ni₉Te₆(PEt₃)₈C₆₀Is a Superatomic Superalkali Superparamagnetic Cluster Assembled Material (S³-CAM)

Abstract

First-principles theoretical studies enable an electronic and magnetic characterization of the recently synthesized Ni9Te6(PEt3)8C60 ionic material consisting of Ni9Te6(PEt3)8 superatoms and C60. The PEt3 ligands are shown to create an internal coulomb well that lifts the quantum states of the Ni9Te6 cluster, lowering its ionization potential to 3.39 eV thus creating a superalkali motif. The metallic core has a spin magnetic moment of 5.3 μB in agreement with experiment. The clusters are marked by low magnetic anisotropy energy (MAE) of 2.72 meV and a larger intra-exchange coupling exceeding 0.2 eV, indicating that the observed paramagnetic behavior around 10K is due to superparamagnetic relaxations. The magnetic motifs separated by C60 experience a weak superexchange that stabilizes a ferromagnetic ground state as observed around 2 K. The calculated MAE is sensitive to the charged state that could account for the observed change in magnetic transition temperature with size of the ligands or anion.

Magnetic behavior of superatomic-fullerene assemblies

“…In a recent work we undertook an investigation of the magnetic moment and anisotropy in a Ni9Te6(PEt3)8 cluster using a first-principles approach. 15 The theoretical studies indicate that the individual clusters have a spin magnetic moment of 5.3 μB in agreement with experiment. Further, the clusters are marked by low magnetic anisotropy energy (MAE) of 2.72 meV and a larger intraexchange coupling exceeding 0.2 eV indicating that the observed paramagnetic behavior around 10K is likely due to superparamagnetic relaxations.…”

Dimerization of Endohedral Fullerene in a Superatomic Crystal

“…This presents an additional challenge for their assembly into superatomic crystals via charge transfer. To overcome this challenge, our initial plan was to react Lu 3 N@C 80 with Ni 9 Te 6 (PEt 3 ) 8 , a building block with a high ionization energy …”

“…Refinement of the crystallographic data indicates that Lu 3 N@C 80 forms dimers and the stoichiometry of the compound is [Ni 12 Te 12 (PEt 3 ) 8 ] 2 [(Lu 3 N@C 80 ) 2 ]. Based on previous work on superatomic crystals, fullerene dimers and endohedral fullerene dimers, we can assign the following charges to the building blocks: [Ni 12 Te 12 (PEt 3 ) 8 ] and the dimer [(Lu 3 N@C 80 ) 2 ] bear 1+ and 2− charges, respectively. DFT calculations presented below agree with this assignment.…”

Recent Progress on the Design, Characterization, and Application of Superalkalis

“…Nowadays, although tremendous achievements have been made for the potential application of superalkalis, their practical application still remains a challenge. For example, although some superalkalis have been experimentally detected in the gas phase, scarce solid salts with superalkalis as building blocks have been synthesized to date . In this regard, more efforts are expected to be devoted to synthesizing superalkali‐assembled materials, such as supersalts and superatomic crystals.…”

“…They also suggested a kind of organo‐Zintl superalkalis P 7 R 4 by decorating a Zintl core P 7 3− with organic ligands R [Me, CH 2 Me, CH(Me) 2 , and C(Me) 3 ] . Chauhan et al . proved the synthesized Ni 9 Te 6 (PEt 3 ) 8 C 60 to be a superatomic superalkali superparamagnetic cluster assembled material, consisting of Ni 9 Te 6 (PEt 3 ) 8 and C 60 subunits.…”