Temperature-independent Paramagnetism Research Articles

When van der Waals Met Kagome: A 2D Antimonide with a Vanadium-Kagome Network.

2D materials showcase unconventional properties emerging from quantum confinement effects. In this work, a "soft chemical" route allows for the deintercalation of K+ from the layered antimonide KV6Sb6, resulting in the discovery of a new metastable 2D-Kagome antimonide K0.1(1)V6Sb6 with a van der Waals gap of 3.2 Å. The structure of K0.1(1)V6Sb6 was determined via the synergistic techniques, including X-ray pair distribution function analysis, advanced transmission electron microscopy, and density functional theory calculations. The K0.1(1)V6Sb6 compound crystallizes in the monoclinic space group C2/m (a = 9.57(2) Å, b = 5.502(8) Å, c = 10.23(2) Å, β = 97.6(2)°, Z = 2). The [V6Sb6] layers in K0.1(1)V6Sb6 are retained upon deintercalation and closely resemble the layers in the parent compound, yet deintercalation results in a relative shift of the adjacent [V6Sb6] layers. The magnetic properties of the K0.1(1)V6Sb6 phase in the 2-300 K range are comparable to those of KV6Sb6 and another Kagome antimonide KV3Sb5, consistent with nearly temperature-independent paramagnetism. Electronic band structure calculation suggests a nontrivial band topology with flat bands and opening of band crossing afforded by deintercalation. Transport property measurements reveal a metallic nature for K0.1(1)V6Sb6 and a low thermal conductivity of 0.6 W K-1 m-1 at 300 K. Additionally, ion exchange in KV6Sb6 via a solvothermal route leads to a successful partial exchange of K+ with A+ (A = Na, Rb, and Cs). This study highlights the tunability of the layered structure of the KV6Sb6 compound, providing a rich playground for the realization of new 2D materials.

Pseudo Temperature Independent Paramagnetism in Co2Si5N8 Nitridosilicate

Herein, the synthesis of Co2Si5N8 nitridosilicate from α‐Ca2Si5N8 by ion exchange is described. The monoclinic structure (space group Cc) is compared with those of the related nitridosilicates Ca2Si5N8 and Fe2Si5N8 its magnetic properties are profoundly investigated. Most interestingly, polycrystalline Co2Si5N8 exhibits a quasi‐temperature‐independent paramagnetic susceptibility of about over a wide temperature range from 100 to 600 K. Two different magnetic models based on a phenomenological Hamiltonian that takes into account magnetic exchange coupling, crystal‐field interactions, and Zeeman effects within the framework of an angular momentum basis set are refined to the experimental susceptibility datasets. The results of the refinements point to the realization of a pseudo temperature independent paramagnetism for Co2Si5N8 that results from a near‐perfect cancellation of temperature‐dependent contributions to the susceptibility depending delicately on the mixing of ion levels in the electronic states, their relative energies, and the magnetic coupling between them. Additionally, performed direct current field scan, alternating current susceptibility, and heat capacity measurements complete the magnetic characterization and facilitate the identification of impurity phase contributions.

Breaking New Ground: MBene Route toward Selective Vinyl Double Bond Hydrogenation in Nitroarenes.

Doping, or incremental substitution of one element for another, is an effective way to tailor a compound's structure as well as its physical and chemical properties. Herein, we replaced up to 30% of Ni with Co in members of the family of layered LiNiB compounds, stabilizing the high-temperature polymorph of LiNiB while the room-temperature polymorph does not form. By studying this layered boride with in situ high-temperature powder diffraction, we obtained a distorted variant of LiNi0.7Co0.3B featuring a perfect interlayer placement of [Ni0.7Co0.3B] layers on top of each other─a structural motif not seen before in other borides. Because of the Co doping, LiNi0.7Co0.3B can undergo a nearly complete topochemical Li deintercalation under ambient conditions, resulting in a metastable boride with the formula Li0.04Ni0.7Co0.3B. Heating of Li0.04Ni0.7Co0.3B in anaerobic conditions led to yet another metastable boride, Li0.01Ni0.7Co0.3B, with a CoB-type crystal structure that cannot be obtained by simple annealing of Ni, Co, and B. No significant alterations of magnetic properties were detected upon Co-doping in the temperature-independent paramagnet LiNi0.7Co0.3B or its Li-deintercalated counterparts. Finally, Li0.01Ni0.7Co0.3B stands out as an exceptional catalyst for the selective hydrogenation of the vinyl C═C bond in 3-nitrostyrene, even in the presence of other competing functional groups. This research showcases an innovative approach to heterogeneous catalyst design by meticulously synthesizing metastable compounds.

Crystal Growth and Physical Properties of Hybrid CoSn-YCo6Ge6 Structure Type LnxCo3(Ge1-ySny)3 (Ln = Y, Gd).

There is an ongoing interest in kagome materials because they offer tunable platforms at the intersection of magnetism and electron correlation. Herein, we examine single crystals of new kagome materials, LnxCo3(Ge1-ySny)3 (Ln = Y, Gd; y = 0.11, 0.133), which were produced using the Sn flux-growth method. Unlike many of the related chemical analogues with the LnM6X6 formula (M = transition metal and X = Ge, Sn), the Y and Gd analogues crystallize in a hybrid YCo6Ge6/CoSn structure, with Sn substitution. While the Y analogue displays temperature-independent paramagnetism, magnetic measurements of the Gd analogue reveal a magnetic moment of 8.48 μB, indicating a contribution from both Gd and Co. Through anisotropic magnetic measurements, the direction of Co-magnetism can be inferred to be in plane with the kagome net, as the Co contribution is only along H//a. Crystal growth and structure determination of YxCo3(Ge,Sn)3 and GdxCo3(Ge,Sn)3, two new hybrid kagome materials of the CoSn and YCo6Ge6 structure types. Magnetic properties, heat capacity, and resistivity on single crystals are reported.

High-pressure hydrothermal growth and characterization of Sr3Os4O14 single crystals

Single crystals of the novel strontium osmate Sr3Os4O14 have been grown by the hydrothermal method using opposed anvil high-pressure and high-temperature technique. The reaction took place in sealed gold capsules at 3 GPa and a temperature of 1100 °C, with water acting as a solvent. The employed method yields up to 1 mm crystals with quite uncommon double-terminated morphologies. The crystal structure was identified as tetragonal by single-crystal X-ray diffraction, with lattice parameters a = 12.2909(8) Å and c = 7.2478(5) Å. The structural analysis suggests P42nm or P42/mnm as a possible space group. In general, the structure belongs to the pyrochlore type and is composed of a network of symmetrically arranged OsO6 octahedra. Resistivity measurements evidence a metallic behavior, accompanied by a temperature-independent paramagnetism. Heat capacity measurements reveal a slightly enhanced value of the Sommerfeld coefficient γ = 34 mJ/mol K2. Superconductivity has not been observed down to 2 K.

Structure and compositional trends in alkali-metal containing titanium and vanadium oxide chalcogenides and the new van der Waals phase Ti2Te2O

We report the solid-state synthesis of all eighteen layered oxide chalcogenides in the structural family AM2Q2O (A = K/Rb/Cs; M = Ti/V; Q = S/Se/Te), allowing the determination of trends in composition and reactivity within the series. All materials are isostructural, crystallising in the primitive tetragonal space group P4/mmm as reported previously for five compounds in the series. The titanium or vanadium ions have intermediate valency on a single crystallographic site, leading to temperature-independent paramagnetism and correlated electronic behaviour which is influenced by the compositional variation. Furthermore, the alkali metal ions in ▪ and ▪ can be removed by oxidative deintercalation using ▪ at room temperature to produce a new metastable van der Waals layered phase, ▪. During the deintercalation reaction the oxide chalcogenide layers undergo a relative shift by (0.5,0.5) in the ab plane such that ▪ is body-centered with space group I4/mmm.

Rapid sol-gel synthesis of honeycomb-layered Na3Ni2BiO6 and orthorhombic Na3Ca2BiO6.

The A3M2M'O6 type materials Na3Ca2BiO6 and Na3Ni2BiO6 were successfully synthesised through two sol-gel techniques - a method based on a natural deep eutectic solvent, and a biopolymer-mediated synthesis. The materials were analysed using Scanning Electron Microscopy to determine if there was a difference in final morphology between the two methods, and it was found that the natural deep eutectic solvent method resulted in a more porous morphology. For both materials, the optimum dwell temperature was found to be 800 °C, which in the case of Na3Ca2BiO6 was a much less energy-intensive synthesis process than its seminal solid-state synthesis. Magnetic susceptibility measurements were undertaken on both materials. It was found that Na3Ca2BiO6 exhibits only weak, temperature independent paramagnetism. Na3Ni2BiO6 was found to be antiferromagnetic, with a Néel temperature of 12 K, in line with previously reported results.

The temperature-independent paramagnetic susceptibility peak at zero magnetic field in non-topological WSe2 single crystal

The temperature-independent paramagnetic susceptibility peaks were observed in the non-topological WSe2 single crystal. This is contrary to the proposed explanation that the temperature-independent paramagnetic peak in topological materials originates from the spin texture of the topological surface state. Weak ferromagnetic characteristic was observed from magnetization measurement from 300 to 5 K. The high resolution transmission electron microscope images combined with no detectable magnetic impurity was found in our sample indicate that the ferromagnetism originates from lattice dislocations at different layer planes and axes. The temperature-independent paramagnetism susceptibility peak should originate from the ferromagnetism induced by lattice dislocation.

Phase relations, structure, properties and DFT study of compounds in the Sc-rich part of the systems Sc-{Mn,Fe,Co,Ni}-Ga

Phase relations, structure, properties and DFT study of compounds in the Sc-rich part of the systems Sc-{Mn,Fe,Co,Ni}-Ga

Formation of dimethoxy bridged dinuclear iron(III) complex of pyridoxal Schiff base with iron-catalyzed oxidative C[sbnd]N bond cleavage – Structure, magnetic properties, and DFT calculations

Mononuclear Fe(III) complex [FeL(N3)]·CH3OH, where L2– is the dianion of an unsymmetrical propyl-ethyl pentadentate Schiff base ligand condensed from pyridoxal and N-(2-aminoethyl)propane-1,3-diamine, and dinuclear Fe(III) complex [{FeL’}2(μ-OCH3)2]·2.5CH3OH·H2O, where L’2– is the dianion of tetradentate Schiff base ligand based on pyridoxal and ethylenediamine, have been synthesized and characterized by elemental analysis, X-ray structural analysis, FT-IR and mass spectrometry. Tetradentate pyridoxal Schiff base ligand L’2– of the dinuclear complex was generated in situ via iron-catalyzed oxidative CN bond cleavage of the pentadentate Schiff base. The coordination geometry around the iron(III) centers of the complexes can be described as adistorted octahedron. Magnetic investigations of [FeL(N3)]·CH3OH complex revealed that the octahedral Fe(III) center retains high-spin in the entire temperature range (2–300 K) and enabled the evaluation of the axial zero-field splitting (ZFS) parameter D = –1.78 cm−1, intermolecular exchange parameter zj́ = –1.35 cm−1 and temperature-independent paramagnetism χTIM = 0.00029 cm3mol−1. Magnetic investigations of [{FeL’}2(μ-OCH3)2]·2.5CH3OH·H2O showed that Fe(III) centers are coupled by a strong antiferromagnetic interaction (J = –94.5 cm−1). The experimental magnetic properties of the complexes were compared with the data obtained from the density functional theory (DFT) calculations.

Energy Levels in Pentacoordinate d5 to d9 Complexes

Energy levels of pentacoordinate d5 to d9 complexes were evaluated according to the generalized crystal field theory at three levels of sophistication for two limiting cases of pentacoordination: trigonal bipyramid and tetragonal pyramid. The electronic crystal field terms involve the interelectron repulsion and the crystal field potential; crystal field multiplets account for the spin–orbit interaction; and magnetic energy levels involve the orbital– and spin–Zeeman interactions with the magnetic field. The crystal field terms are labelled according to the irreducible representations of point groups D3h and C4v using Mulliken notation. The crystal field multiplets are labelled with the Bethe notations for the respective double groups D’3 and C’4. The magnetic functions, such as the temperature dependence of the effective magnetic moment and the field dependence of the magnetization, are evaluated by employing the apparatus of statistical thermodynamics as derivatives of the field-dependent partition function. When appropriate, the formalism of the spin Hamiltonian is applied, giving rise to a set of magnetic parameters, such as the zero-field splitting D and E, magnetogyric ratio tensor, and temperature-independent paramagnetism. The data calculated using GCFT were compared with the ab initio calculations at the CASSCF+NEVPT2 level and those involving the spin–orbit interaction.

π-Pimer, π-Dimer, π-Trimer, and 1D π-Stacks in a Series of Benzene Triimide Radical Anions: Substituent-Modulated π Interactions and Physical Properties in Crystalline State

π-Pimer, π-Dimer, π-Trimer, and 1D π-Stacks in a Series of Benzene Triimide Radical Anions: Substituent-Modulated π Interactions and Physical Properties in Crystalline State

Radical Cation Salts of N‐Methylpyridone Azines with Halogenido Cuprate Anions

AbstractBis(N‐methylpyridone)azine (MPA) and its derivative bis(N‐methyl‐5‐trifluoromethyl‐pyridone)azine (p‐CF3MPA) are investigated concerning their redox behavior. Reactions with copper(II) halides afford via one electron transfer reactions the radical cation salts MPA[CuCl2], MPA[CuBr2] and p‐CF3MPA[CuBr2], all crystallizing as air‐stable dark needles. Cu(II) is reduced to the corresponding cuprate(I) anions [CuX2]− (X=Cl, Br). In the crystal structures, the planar radical cations form stacks with equidistantly arranged molecules. Low temperature data show a significant lattice parameter contraction resulting in denser packing of the radical cations in the stacking direction. MPA[CuBr2] can be further oxidized by CuBr2 to MPA[Cu2Br4] with MPA2+ in the dicationic state. The oxidation states 0, +1, and +2 of the cations are clearly distinguishable by the bond lengths in the central CNNC azine moiety. All compounds are semiconductors with small band gaps between 0.95 and 1.34 eV. The magnetic properties of MPA[CuX2] are dominated by reduced momenta. At temperatures below 50 K, a small magnetic momentum of about 1/3 of one unpaired electron is observed, which probably arise from paramagnetic impurity in form of Cu2+. For T >50 K magnetic momenta turn into a nearly temperature independent paramagnetism. p‐CF3MPA[CuBr2] is mainly paramagnetic with weak antiferromagnetic exchange (TNéel=6 K, J=−2.1 cm−1).

Osmium(IV) pyrophosphate: Synthesis, Crystallization, and Ligand‐Field Analysis of the [OsIVO6] Chromophore

AbstractTwo polymorphs of burgundy‐red OsP2O7, with cubic (ZrP2O7 structure type, Z=4, a=7.8276(4) Å, 3×3×3 superstructure with a’=3a=23.484(2) Å) and triclinic symmetry (ruby‐red crystals, single‐crystal X‐ray structure determination, GeP2O7 structure type, (no. 2), Z=2, a=4.8072(7) Å, b=6.8993(13) Å, c=8.050(1) Å, α=91.82(2)°, β=92.92(1)°, γ=107.42(2)°, 98 parameters, R1=0.045, wR2=0.144, 3006 unique reflections with |Fo|>4σ(Fo)) have been obtained reducing OsO4 by phosphorus in sealed silica ampoules followed by subsequent chemical vapour transport. Reaction with the wall led to mixed SiIV/OsIV silicophosphates (Os1−xSix)3[Si2O(PO4)6] {x=0.84, pale orange, SiIV3[Si2O(PO4)6] structure type, , Z=3, a=7.893(1) Å, c=24.409(5) Å, 59 parameters, R1=0.058, wR2=0.160, 1311 unique reflections with 1033 |Fo|>4σ(Fo); x=0.47, orange, GeIV3[Si2O(PO4)6] structure type, , Z=2, a=7.9979(3) Å, c=16.4625(5) Å, 59 parameters, R1=0.040, wR2=0.094, 902 unique reflections with 749 |Fo|>4σ(Fo)}. Both structures were refined from single‐crystal data. Above 25 K triclinic OsP2O7 shows temperature independent paramagnetism with a strong temperature dependence of pointing to as electronic ground state for Os4+ (d4) with strong spin‐orbit coupling leading to =0 and the non‐magnetic ground state of the octahedral [OsIVO6] chromophore.. Optical spectra of both polymorphs of OsP2O7 show similar combinations of intense sharp and broad absorption bands typical for dn electronic systems systems with both, spin‐orbit coupling and ligand field splitting, being strong. The observations are consistent with the ligand‐field parameters Δo=20000 cm−1, B=704 cm−1, and ζ=3454 cm−1 for the octahedral [OsIVO6] chromophore.

First examples of nickel–Aluminum mixed chalcogenides based on the AuCu3-type fragments: Breaking a robust intermetallic bond system in Ni3Al

Three new mixed nickel-aluminum chalcogenides, Ni6.07AlS2, Ni5.61AlSe2, and Ni5.70AlTe2, have been synthesized by a high-temperature ampoule route using the addition LiCl and KCl. The former compound was characterized from single-crystal synchrotron and powder diffraction data, and the latter two by powder diffraction data. All compounds crystallize in the tetragonal system with I4/mmm space group and belong to the relatively uncommon Ni7-xMQ2 structure type (M ​− ​main-group metal). The compounds Ni5.61AlSe2 and Ni5.70AlTe2 represent first ternaries discovered in the respective systems. The main heterometallic structural units of all three compounds are aluminum-centered [Ni12Al] cuboctahedra of the AuCu3-type, single-stacked along the c axis, alternating with [Ni4-xQ2] (Q ​= ​S, Se, Te) along the c axis with either nickel-sulfur fragments of the Li2O and defective Cu2Sb/NaCl type, or with nickel-selenium/nickel-tellurium fragments of the defective Cu2Sb/NaCl type respectively. According to the DFT calculations, electronic structures of these ternary compounds are directly related to their parent intermetallic Ni3Al. Non-zero density of states (DOS) at the Fermi level for all compounds indicates metallic conductivity. The ELF topological analysis has shown four-center 3Ni ​+ ​Al bonds both in Ni3Al and ternary nickel-aluminum chalcogenides, with additional pairwise nickel-chalcogen interactions in the latter. Magnetic measurements on Ni6.07AlS2 show the temperature-independent Pauli-like paramagnetism, predicted by DFT calculations for all three chalcogenides, which is in contrast with ferromagnetic behavior of its parent intermetallic.

Anomalous magnetism of uranium(IV)-oxo and -imido complexes reveals unusual doubly degenerate electronic ground states

Anomalous magnetism of uranium(IV)-oxo and -imido complexes reveals unusual doubly degenerate electronic ground states

Experimental and Theoretical Evidence for an Unusual Almost Triply Degenerate Electronic Ground State of Ferrous Tetraphenylporphyrin.

Iron porphyrins exhibit unrivalled catalytic activity for electrochemical CO2-to-CO conversion. Despite intensive experimental and computational studies in the last 4 decades, the exact nature of the prototypical square-planar [FeII(TPP)] complex (1; TPP2- = tetraphenylporphyrinate dianion) remained highly debated. Specifically, its intermediate-spin (S = 1) ground state was contradictorily assigned to either a nondegenerate 3A2g state with a (dxy)2(dz2)2(dxz,yz)2 configuration or a degenerate 3Egθ state with a (dxy)2(dxz,yz)3(dz2)1/(dz2)2(dxy)1(dxz,yz)3 configuration. To address this question, we present herein a comprehensive, spectroscopy-based theoretical and experimental electronic-structure investigation on complex 1. Highly correlated wave-function-based computations predicted that 3A2g and 3Egθ are well-isolated from other triplet states by ca. 4000 cm-1, whereas their splitting ΔA-E is on par with the effective spin-orbit coupling (SOC) constant of iron(II) (≈400 cm-1). Therfore, we invoked an effective Hamiltonian (EH) operating on the nine magnetic sublevels arising from SOC between the 3A2g and 3Egθ states. This approach enabled us to successfully simulate all spectroscopic data of 1 obtained by variable-temperature and variable-field magnetization, applied-field 57Fe Mössbauer, and terahertz electron paramagnetic resonance measurements. Remarkably, the EH contains only three adjustable parameters, namely, the energy gap without SOC, ΔA-E, an angle θ that describes the mixing of (dxy)2(dxz,yz)3(dz2)1 and (dz2)2(dxy)1(dxz,yz)3 configurations, and the ⟨rd-3⟩ expectation value of the iron d orbitals that is necessary to estimate the 57Fe magnetic hyperfine coupling tensor. The EH simulations revealed that the triplet ground state of 1 is genuinely multiconfigurational with substantial parentages of both 3A2g (<88%) and 3Eg (>12%), owing to their accidental near-triple degeneracy with ΔA-E = +950 cm-1. As a consequence of this peculiar electronic structure, 1 exhibits a huge effective magnetic moment (4.2 μB at 300 K), large temperature-independent paramagnetism, a large and positive axial zero-field splitting, strong easy-plane magnetization (g⊥ ≈ 3 and g∥ ≈ 1.7) and a large and positive internal field at the 57Fe nucleus aligned in the xy plane. Further in-depth analyses suggested that g⊥ ≫ g∥ is a general spectroscopic signature of near-triple orbital degeneracy with more than half-filled pseudodegenerate orbital sets. Implications of the unusual electronic structure of 1 for CO2 reduction are discussed.

Topochemical Deintercalation of Li from Layered LiNiB: toward 2D MBene.

The pursuit of two-dimensional (2D) borides, MBenes, has proven to be challenging, not the least because of the lack of a suitable precursor prone to the deintercalation. Here, we studied room-temperature topochemical deintercalation of lithium from the layered polymorphs of the LiNiB compound with a considerable amount of Li stored in between [NiB] layers (33 at. % Li). Deintercalation of Li leads to novel metastable borides (Li∼0.5NiB) with unique crystal structures. Partial removal of Li is accomplished by exposing the parent phases to air, water, or dilute HCl under ambient conditions. Scanning transmission electron microscopy and solid-state 7Li and 11B NMR spectroscopy, combined with X-ray pair distribution function (PDF) analysis and DFT calculations, were utilized to elucidate the novel structures of Li∼0.5NiB and the mechanism of Li-deintercalation. We have shown that the deintercalation of Li proceeds via a "zip-lock" mechanism, leading to the condensation of single [NiB] layers into double or triple layers bound via covalent bonds, resulting in structural fragments with Li[NiB]2 and Li[NiB]3 compositions. The crystal structure of Li∼0.5NiB is best described as an intergrowth of the ordered single [NiB], double [NiB]2, or triple [NiB]3 layers alternating with single Li layers; this explains its structural complexity. The formation of double or triple [NiB] layers induces a change in the magnetic behavior from temperature-independent paramagnets in the parent LiNiB compounds to the spin-glassiness in the deintercalated Li∼0.5NiB counterparts. LiNiB compounds showcase the potential to access a plethora of unique materials, including 2D MBenes (NiB).

Iron(III) and cobalt(III) complexes with pentadentate pyridoxal Schiff base ligand – structure, spectral, electrochemical, magnetic properties and DFT calculations

Three complexes, [FeLCl]Cl·H2O, [Co2L2H3O2]Cl·4.8H2O, and [CoLN3], where L2– is the dianion of an asymmetric propyl-ethyl pentadentate Schiff base ligand condensed from pyridoxal and N-(2-aminoethyl)propane-1,3-diamine, have been synthesized and characterized by elemental analysis, FT-IR and mass spectroscopy. Crystal structures of the complexes along with the Schiff base were determined by X-ray diffraction. 1HNMR spectrum of the Schiff base has been obtained. The coordination polyhedra of all three complexes can be expressed as distorted octahedra. Magnetic investigations of [FeLCl]Cl·H2O complex confirmed high-spin state over the whole temperature range (5–300 K) and allowed the evaluation of the axial zero-field splitting (ZFS) parameter D = –0.97 cm−1, intermolecular exchange parameter zj́ = –0.88 cm−1 and temperature-independent paramagnetism χTIM = 0.00025 cm3mol−1. The low-spin state of Co(III) was stabilized in diamagnetic [Co2L2H3O2]Cl·4.8H2O and [CoLN3] complexes. Redox potentials of the Schiff base and the complexes were investigated by cycling voltammetry on the GC electrode in dry acetonitrile. The experimental magnetic properties of the complexes [FeLCl]Cl·H2O and [CoLN3] were compared with the theoretical ones calculated using density functional theory (DFT).

Experimental evaluation of the stabilization of the COT orbitals by 4f orbitals in COT2Ce using a Hubbard model.

Significant orbital mixing is rare in lanthanide complexes because of the limited radial extent of the 4f orbitals, which results in a generally small stabilization due to 4f orbital interactions. Nevertheless, even a small amount of additional stabilization could enhance lanthanide separations. One lanthanide complex in which orbital mixing has been extensively studied both experimentally and computationally is cerocene, COT2Ce, where COT is cyclooctatetraene. This compound has a singlet ground state with a low-lying, triplet excited state. Previous fluorescence studies on trimethylsilyl-substituted cerocenes indicate the triplet state is 0.4 eV higher in energy than the singlet state. In addition, computational studies predict that the triplet is 0.3 to 1 eV higher in energy than the singlet. The synthesis of highly pure COT2Ce by Walter and Andersen allowed its physical properties to be accurately measured. Using these measurements, we evaluate the stabilization of the 4f orbitals using two, independent approaches. A Hubbard model is used to evaluate the stabilization of the ground state due to orbital mixing. This stabilization, which is also the singlet-triplet gap, is -0.29 eV using this model. This gap was also from the temperature independent paramagnetism of COT2Ce, which yielded a value of -0.32 eV.