This study investigates sustainable approaches to designing organic cathode materials for sodium-ion batteries, aiming to replace traditional metal-based electrodes. Organic materials present a promising alternative due to their lower environmental impact, supply chain stability, and tunable electrochemical properties. In this work, the electrochemical performance of 12 commercially available amino- and hydroxy-substituted anthraquinone derivatives, including several naturally occurring compounds, was systematically evaluated in sodium-ion battery systems. By focusing on readily available commercial materials, this study identified the most stable and effective candidates for organic cathodes in sodium-ion batteries. Notably, the majority of these derivatives have never been tested in galvanostatic cycling in either lithium or other post-lithium battery systems. Through systematic testing, challenges such as high solubility and limited redox reactivity were addressed, demonstrating how careful material selection can yield high-performance, long-cycle-life organic cathodes. The performance of these materials was found to be strongly influenced by their solubility in the electrolyte as well as their structural and electronic properties, including electron-accepting capabilities and sodium coordination behavior. Among the studied materials, 1,8-dihydroxy-anthraquinone and 1,8-diamino-anthraquinone demonstrate superior cycle stability, maintaining 72% and 73% capacity retention, respectively, over 100 charge-discharge cycles, followed by 1,5-diamino-anthraquinone and 1-hydroxy-anthraquinone with 64% and 66%. These findings not only advance the development of organic cathode materials for sodium-ion batteries but also highlight the potential of sustainable material choices to enable scalable and environmentally friendly energy storage solutions, supporting the transition to a greener energy future.

From redox transmetallation/protolysis reactions of alkaline earth metals, Mg, Ca, and Sr with bispentafluorophenylmercury and N,N '-bis(2-trifluoromethylphenyl)formamidine (CF3FormH) in tetrahydrofuran (thf), the complexes [Ae(CF3Form)2(thf)2] (Ae = Mg 1, Ca 2) and [Sr(CF3Form)2] 3 have been isolated. Reaction of 3 with 18-crown-6 yielded the charge separated [Sr(CF3Form)(18-crown-6)(thf)][Sr(CF3Form)3] 3a, and from heating 3 in C6D6, crystals of [Sr4(CF3Form)4L4] (L = oxidomethyl(2-trifluoromethyl)phenylamide) 3b were obtained. The crude product 4 from a synthesis with Ba similar to those of 1-3 yielded the large cage [Ba19(CF3Form)6L6F26(diglyme)6] 4a. Complexes 1 and 2 are monomeric with chelating CF3Form ligands, six coordination of the Ae metal, and cis and trans thf ligands respectively. In 3, trans chelating CF3Form ligands are supported by -CF3-Sr coordination. Charge-separated 3a, has a nine-coordinate cation, whilst the unique nine-coordinate tris(formamidinato)strontiate(ii) anion has three -CF3-Sr interactions. In the cage 3b, each Sr atom is nine coordinate with chelating CF3Form and 2-CF3C6H4NCHO- ligands, two bridging oxygens from the latter ligands, and three -CF3-Sr interactions. The Ba19 cage 4a has a central BaF8 unit, which is linked by bridging fluorides to three different Ba atoms, which also have CF3-Ba bonds. The complexes [K2(CF3Form)2(dme)]infinity 5 and [K3(CF3Form)3]infinity 6a were obtained by deprotonation of CF3FormH with K(N(SiMe3)2) and KH respectively, and a similar treatment of N-(2,6-difluorophenyl)acetamide with the silylamide gave potassium N-acetyl-N-(2,6-difluorophenyl)amide 7. Complexes 5 and 6a are 1-D polymers with two and three differently coordinating CF3Form ligands respectively. The structures are based on chelating bridging CF3Form ligands supported by -CF3-A bonding including rare chelating CF3 groups. 7 forms a 2-D polymer sheet, based on tridentate FNO ligands.

Alkaline earth (Ae) and potassium N , N ′-bis(2-trifluoromethylphenyl)formamidinate complexes have been prepared by redox transmetallation/protolysis and deprotonation reactions. Structures of complexes of the larger metals Sr, Ba, K exhibit –CF–Ae(K).

The rise of carbon dioxide (CO2) in the atmosphere is closely linked to global climate change, driving the need for efficient carbon capture technologies. This study investigates the electrochemical carbon capture capabilities of the polymer poly-1-aminoanthraquinone (p-1-AAQ) when coated onto glassy carbon and carbon paper electrodes. This polymer is synthesized from cheap materials using facile, oxidative electropolymerization and provides high cyclic stability. Cyclic voltammetry and potentiostatic "electroswing" methods were employed together with infrared spectroscopy detection to study CO2 capture and evaluate Faradaic efficiency under acidic, neutral, and alkaline conditions. These results indicate that coated glassy carbon electrodes offer significantly higher Faradaic efficiencies than carbon paper (CP). However, carbon paper electrodes still displayed an exemplary maximum capture efficiency of 76%, showing that 2 CO2 molecules were captured per polymeric anthraquinone repeating unit. With a low loading of electroactive polymer on the overall electrode, a good CO2 uptake capacity of 0.17 mmolCO2 gp-1-AAQ+CP-1 based on the whole immersed electrode mass was achieved. Electrochemical impedance spectroscopy revealed that differences in interface resistance between the polymer and the electrolyte contribute to this disparity, particularly at lower potentials where glassy carbon shows suppressed unwanted side reactions.

This study investigates the redox potential tunability of hydroxy- and amino-substituted anthraquinones (AQs) for their potential application in sodium-ion batteries (SIBs). As hydroxy-AQs are naturally occurring pigments and amino-AQs are commonly used in toners and inks, AQ and its derivatives have the potential to be a costeffective, abundant, and environmentally friendly cathode material for SIBs. A comparative analysis of ten distinct (di)hydroxy- and (di)amino-substituted AQs revealed substantial redox potential shifts of up to 700 mV in solution and 440 mV in a half-cell battery setup, depending on the substitution pattern. The most positive reduction potential in solution was observed for 1,5-dihydroxyanthraquinone (1,5OH-AQ), while 2,6-diaminoanthraquinone (2,6-NHS-AQ) exhibited the most negative value. OH-substituted AQs demonstrate anodic shifts, whereas NHS-substituted AQs induce cathodic shifts, which can be attributed to the combined effects of inductive (-I) and mesomeric (+M) influences, as well as intramolecular hydrogen bonding. To further understand the electronic and structural impact of these functional groups, ATR-FTIR analysis was conducted, revealing that the substitution position significantly affects the strength of the carbonyl bonds, leading to shifts in the C = O stretching vibration. Detailed electrochemical investigations, including cyclic voltammetry (CV) and galvanostatic charge/discharge cycling demonstrate that 1,5-OH-AQ and 2,6-NHS-AQ exhibit distinct and complementary redox properties. Their pronounced potential differences suggest a viable pathway for an all-organic AQ-based SIB, offering a promising alternative for sustainable energy storage.

The complexes, [RE(CF(3)Form)(3)] (RE = Ce, 1, or Pr, 2) and [Y(CF(3)Form)(3)(thf)] 3, have been prepared by protolysis of the corresponding RE[N(SiMe3)(2)](3) complexes with N,N '-bis(2-trifluoromethylphenyl)formamidine (CF(3)FormH) in tetrahydrofuran (1-3) or by redox transmetallation/protolysis between the RE metal, bis(pentafluorophenyl)mercury (Hg(C6F5)(2)), and CF(3)FormH in tetrahydrofuran (1, 2), and are characterized by H-1 NMR and F-19 NMR spectroscopy. X-ray crystallography established 1 and 2 to contain 12-coordinate RE metals with three tetradentate F,N,N ',F '-CF(3)Form ligands, whereas 3 has an eight coordinate Y atom with two bidentate N,N '- and one tridentate N,N ',F-CF(3)Form ligands and coordinated thf, and with a further F atom within the sum of Y and F van der Waals radii but >0.25 angstrom more distant from Y. In 1 and 2, every CF3 group forms a F2C-F-RE bond, and the extensive F-RE bonding is preferred over coordination of thf.

The organic semiconductor 3,4,9,10-perylenetetracarboxylic diimide (PTCDI), a widely used industrial pigment, has been identified as a diffusion-less Na-ion storage material, allowing for exceptionally fast charging/discharging rates. The elimination of diffusion effects in electrochemical measurements enables the assessment of interaction energies from simple cyclic voltammetry experiments through the theoretical work of Laviron and Tokuda. In this work, the two N-substituted perylenes, N,N'-dimethyl-3,4,9,10-perylenetetracarboxylic diimide (Me2PTCDI) and N,N'-diphenyl-3,4,9,10-perylenetetracarboxylic diimide (Ph2PTCDI), as well as the parent molecule 3,4,9,10-perylenetetracarboxylic diimide (H2PTCDI) are investigated as thin-film composite electrodes on carbon fibers for sodium-ion batteries. The composite electrodes are analyzed with Raman spectroscopy. Interaction parameters are extracted from cyclic voltammetry measurements. The stability and rate capability of the three PTCDI derivatives are examined through galvanostatic measurements in sodium-ion half-cell batteries and the influence of the interactions on those parameters is evaluated. In addition, self-consistent charge density function tight binding calculations of the different PTCDI systems interacting with graphite have been carried out. The results show that the binding motif displays notable deviations from an ideal ABA stacking, especially for the neutral state. In addition, data obtained for the electron-transfer integrals show that the difference in performance between different PTCDI thin-film batteries cannot be solely explained by the electron-transfer properties and other factors such as H-bonding have to be considered.

Solid oxide cell technologies play a crucial role in climate change mitigation by enabling the reversible storage of renewable energy. Understanding the electrochemical high-temperature reaction mechanisms and the catalytic role of the electrode and electrolyte materials is essential for advancing power-to-H2 technologies. Despite its significance, limited in situ spectroscopic research focusing on nickel and yttria-stabilized zirconia (Ni/YSZ) is available. We employ near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) to investigate 2D porous Ni/YSZ model electrodes with variable YSZ domain sizes and triple phase boundary (TPB) lengths. Focusing on the hydrogen evolution reaction (HER), we provide a mechanistic explanation for why surface hydroxylation and electrochemical activity are correlated with the YSZ surface area and YSZ domain size and unravel the specific mechanistic role of the YSZ surface. A direct comparison of normalization of the measured total electrolysis current to the purely geometrical length of the TPB vs an electrified "catchment area" next to the TPB, exhibiting strong enough electric fields, is the key to a correct quantitative description of the individual elementary steps of water electrolysis on Ni/YSZ. By combining electrochemical impedance spectroscopy, NAP-XPS, and electric field modeling, the local water reduction process near the TPB can be described, indicating optimized structural parameters for improved HER performance.

Reaction of lanthanoid tris(3,5-dimethylpyrazolate) compounds, [Ln(Me2pz)3(thf)]2 (Ln=La 1 a, Ce, Pr, Dy 1 b, Yb, Lu) with potassium or lithium bistrimethylsilylamide and with or without added 3,5-dimethylpyrazole, or of lanthanoid tris(bistrimethylsilyl)amide complexes with potassium bistrimethylsilylamide and 3,5-dimethylpyrazole have yielded a variety of oxide centred Ln3 or Ln4/(K or Li)1-3 multinuclear cages, namely, [La4O(Me2pz)11 K(thf)2] (2 a), [La4O(Me2pz)11Li(Me2pzH)]⋅0.5Hexane (2 b), [La4O(Me2pz)10(Me2pzH)] (2 c) (from heating 1 a in toluene), [Ce3O(Me2pz)9K2(dme)2] (3 a), [Ce3O(Me2pz)9Li2(thf)2]⋅0.5Hexane (3 b) and [Ce(Me2pz)5Li2(thf)3] (3 c), which crystallized together, [Ce3O(Me2pz)10K3(thf)3] (3 d), [Pr3O(Me2pz)10K3(thf)3] (4), [Dy3O(Me2pz)9K2(thf)2]⋅THF (5), [Yb3O(Me2pz)9K2(thf)2]⋅THF (6), and [Lu3O(Me2pz)9K2(thf)2]⋅THF (7). Crystals of {[K8(Me2pz)8(thf)2]⋅THF}∞ (8) were also obtained from the preparation of 7. From reaction of [Ce(Me2pz)3(thf)]2 with potassium tert-butoxide in toluene, the cerium(IV) heterobimetallic polymer [Ce2(Me2pz)6(OtBu)4K2]∞ (9) was isolated. In the Ln3O and the Ln4O cages, the Ln atoms have triangular and distorted tetrahedral arrangements about the central oxygen, respectively. The relationship of the alkali metals to the central oxygen varies considerably. Thus in 2 a, 2 b, there is no bonding, in 3 a, both K atoms interact weakly, in 3 b one of the two Li atom is bound, in 3 d, 4, one of three K atoms in bound, whilst in 5-7, both K atoms are bound. All metals are bound to the cages by a variety of pyrazolate binding modes, with up to five different exhibited in some structures, and a new coordination mode, μ4-1κ(N):2κ(N'):η5:η5, was observed in two complexes. In the structure of 2 c, the coordinated Me2pzH ligand binds to two metals through a single nitrogen, the first time this has been observed for a pyrazole donor. The complex 9 is polymeric with all metals bridged by butoxide donors as well as by Me2pz groups.

Protonolysis reactions between dimethylamido titanium(IV) catecholate [Ti(CAT)(NMe2)2]2 and neopentanol or tris(tert-butoxy)silanol gave catecholato-bridged dimers [(Ti(CAT)(OCH2tBu)2)(HNMe2)]2 and [Ti(CAT){OSi(OtBu)3}2(HNMe2)2]2, respectively. Analogous reactions using the dimeric dimethylamido titanium(IV) (3,6-di-tert-butyl)catecholate [Ti(CATtBu2-3,6)(NMe2)2]2 yielded the monomeric Ti(CATtBu2-3,6)(OCH2tBu)2(HNMe2)2 and Ti(CATtBu2-3,6)[OSi(OtBu)3]2(HNMe2)2. The neopentoxide complex Ti(CATtBu2-3,6)(OCH2tBu)2(HNMe2)2 engaged in further protonolysis reactions with Si-OH groups and was consequentially used for grafting onto mesoporous silica KIT-6. Upon immobilization, the surface complex [Ti(CATtBu2-3,6)(OCH2tBu)2(HNMe2)2]@[KIT-6] retained the bidentate chelating geometry of the catecholato ligand. This convergent grafting strategy was compared with a sequential and an aqueous approach, which gave either a mixture of bidentate chelating species with a bipodally anchored Ti(IV) center along with other physisorbed surface species or not clearly identifiable surface species. Extension of the convergent and aqueous approaches to anatase mesoporous titania (m-TiO2) enabled optical and electronic investigations of the corresponding surface species, revealing that the band-gap reduction is more pronounced for the bidentate chelating species (convergent approach) than for that obtained via the aqueous approach. The applied methods include X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and solid-state UV/vis spectroscopy. The energy-level alignment for the surface species from the aqueous approach, calculated from experimental data, accounts for the well-known type II excitation mechanism, whereas the findings indicate a distinct excitation mechanism for the bidentate chelating surface species of the material [Ti(CATtBu2-3,6)(OCH2tBu)2(HNMe2)2]@[m-TiO2].

For the direct reduction of CO2 and H2O in solid oxide electrolysis cells (SOECs) with cermet electrodes toward methane, a fundamental understanding of the role of elemental carbon as a key intermediate within the reaction pathway is of eminent interest. The present synchrotron-based in situ near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) study shows that alloying of Ni/yttria-stabilized-zirconia (YSZ) cermet electrodes with Cu can be used to control the electrochemical accumulation of interfacial carbon, and to optimize its reactivity toward CO2. In the presence of syngas, sufficiently high cathodic potentials induce excess methane on the studied Ni/yttria stabilized zirconia (YSZ)-, NiCu/YSZ- and Pt/gadolinium doped ceria (GDC) cermet systems. The hydrogenation of carbon resulting from CO activation at the triple-phase boundary of Pt/GDC is most efficient.

NaTi2(PO4)3 (NTP) is known as a promising insertion-type anode material for aqueous and non-aqueous sodium-ion batteries (SIBs), due to its NASICON-type open 3D framework which makes a zero-strain insertion mechanism possible. NTP is considered to be an environmentally friendly, low-cost and high safety material. However, the electrochemical performance of NTP is limited due to its poor electrical conductivity. In this work a solvothermal synthesis method is used to synthesize NTP with a nanocube (NC) morphology. In a one-step synthesis rutile titanium dioxide (TiO2) and carbon coating of NTP are achieved (NTP/C-RT), simultaneously, which significantly improves the poor electrical conductivity of NTP. Additional rutile coating is used to further improve the electrochemical performance compared to simple carbon coating. Rate capabilities of 301 mAh/g are achieved for NTP/C-RT compared to 248 mAh/g for NTP/C at 0.1 C. That is, to the best of our knowledge, the highest gravimetric capacity reported for SIBs using NTP as anode material up to now. The results prove that NTP, which is itself already a promising anode material for SIBs, can be further enhanced with a combined approach of NC morphology, carbon and rutile coating, leading to superior capacities, higher than anywhere else reported in literature.

AbstractNaTi2(PO4)3 (NTP) and Na0.44MnO2 (NMO), and their derivatives, have emerged as the most promising materials for aqueous Na‐ion batteries. For both, NTP and NMO, avoiding the evolution of hydrogen and oxygen is found to be mandatory in order to mitigate material dissolution. Intriguingly, however, no direct determination of the hydrogen and oxygen evolution reactions (HER and OER) has yet been carried out. Using differential electrochemical mass spectrometry (DEMS) we directly identify the onset potentials for the HER and OER. Surprisingly, the potential window is found to be significantly smaller than suggested by commonly employed cyclic voltammetry measurements. CO2 evolution, upon decomposition of carbon black, is observed at an onset potential of 1.61 VRHE, which is 0.25 V more cathodic than the OER for the NMO electrode. Our results show that the state‐of‐the‐art carbon additive plays a crucial role in the stability of the positive NMO electrode in the ion battery.

Lewis base-free lanthanoid (Ln) and actinoid (An) iodides are difficult to obtain, as standard protocols describe syntheses in solutions of donor solvents which are ultimately hard to remove. We have now established a mechanochemical approach towards the synthesis of Lewis base-free f-block metal iodides with excellent yields. In particular, we describe herein the synthesis of EuI2 as an example of a divalent lanthanoid iodide, of CeI3 as an example of a trivalent lanthanoid iodide, and of UI3 as the most important actinoid iodide. Each can be obtained in high yield with minimal work-up, presenting the most efficient and simple synthetic route to access these materials to date.

The 6-membered 3,5-bis(dimethylsilyl)-2,2,4,4,6,6-hexamethyl-1,3,5,2,4,6-triazatrisilinan-1-ido ligand (dhts) was accessed in the potassium dimer [K(dhts)(thf)]2 (1thf), when treating KH with excess HN(SiHMe2)2 in the presence of THF. 1thf engaged in salt metathesis with CeCl3(thf)1.05 in THF, giving Ce(dhts)3(thf) (2thf). An attempted metathesis reaction in toluene failed, leading only to the recovery of 1thf. Attempts at generating potassium-ate complex {KCe(dhts)4} from salt metathesis between CeCl3(thf)1.05 and four equivalents of 1thf in THF, followed by crystallisation from toluene, resulted in the formation of both 2thf and [K(dhts)(toluene)]2 (1tol). Oxidation of 2thf with trityl chloride led to the isolation of the metastable tetravalent heteroleptic cerium complex Ce(dhts)3Cl (3), characterised by both 1H NMR spectroscopy and X-ray crystallography. Compound 3 is a new addition to a prominent class of cerium(IV) silylamides, and an understudied class of triazatrisilinanides.

Trivalent cerium tris-tert-butoxide, "[Ce(OtBu)(3)]", was synthesised in situ and treated with excess HgCl2. After reaction, colourless crystals were identified amongst excess HgCl2. Analysis by X-ray crystallography revealed the formation of an unusual ion separated coordination polymer consisting of two [Ce-IV(OtBu)(3)(thf)(3)](+) ions and a di-anionic chloridomercurate(II) two dimensional sheet [Hg8Cl18](2-), giving the overall formula [{Ce(OtBu)(3)(thf)(3)}(2){Hg8Cl18}](infinity) (1).

Anthraquinone (AQ) has long been identified as a highly promising lead structure for various applications in organic electronics. Considering the enormous number of possible substitution patterns of the AQ lead structure, with only a minority being commercially available, a systematic experimental screening of the associated electrochemical potentials represents a highly challenging and time consuming task, which can be greatly enhanced via suitable virtual pre-screening techniques. In this work the calculated electrochemical reduction potentials of pristine AQ and 12 hydroxy- or/and amino-substituted AQ derivatives in N,N-dimethylformamide have been correlated against newly measured experimental data. In addition to the calculations performed using density functional theory (DFT), the performance of different semi-empirical density functional tight binding (DFTB) approaches has been critically assessed. It was shown that the SCC DFTB/3ob parametrization in conjunction with the COSMO solvation model provides a highly adequate description of the electrochemical potentials also in the case of the two-fold reduced species. While the quality in the correlation against the experimental data proved to be slightly inferior compared to the employed DFT approach, the highly advantageous cost-accuracy ratio of the SCC DFTB/3ob/COSMO framework has important implications in the formulation of hierarchical screening strategies for materials associated with organic electronics. Based on the observed performance, the low-cost method provides sufficiently accurate results to execute efficient pre-screening protocols, which may then be followed by a DFT-based refinement of the best candidate structures to facilitate a systematic search for new, high-performance organic electronic materials.

Electroactive organic semiconducting pigments represent a group of very promising electrode materials for the next generation of energy conversion and storage technologies. However, most pigments suffer from high solubility in organic electrolytes and poor electrical conductivity, which have severely impeded their practical applications. Among different strategies to improve their electrochemical performance, using conductive carbon substrates to form composite electrodes is one of the most used methods to solve these problems. In this work we investigate the role of conductive carbon substrates towards their charge transfer kinetics at the solid/liquid interface with potential application for organic sodium (Na)-ion batteries. This study reveals that the role of conductive carbon is related not only to the optimal electronic path but also to the ionic path towards the electrode active material. Perylentetracarboxylicdiimide is used as the electrode active material coated on graphite/copper and carbon paper substrates. The morphology, structure, and chemical composition of our electrodes are investigated via scanning electron microscopy, X-ray photoelectron and Raman spectroscopy. A thorough kinetic analysis is systematically implemented by cyclic voltammetry and electrochemical impedance spectroscopy. We performed a quantitative analysis of the resistance and capacitive components of the composite electrodes using the theory of the transmission line model and electrochemical impedance spectroscopy with symmetric cells. Our results indicate that a decrease in pore resistance is key to achieve high charge transfer kinetics in electrochemical systems. This work will therefore contribute towards future, efficient electrode design with low pore resistance and high charge transfer kinetics. This may prove of great importance for the development of energy conversion and storage technologies, including heterojunction solar cells, electrocatalysts/photocatalysts for water splitting, carbon dioxide (CO2) reduction and lithium (Li)- and Na-ion batteries.

Electrochemical capture of carbon dioxide (CO2) using organic quinones is a promising and intensively studied alternative to the industrially established scrubbing processes. While recent studies focused only on the influence of substituents having a simple mesomeric or nucleophilicity effect, we have systematically selected six anthraquinone (AQ) derivatives (X-AQ) with amino and hydroxy substituents in order to thoroughly study the influence thereof on the properties of electrochemical CO2 capture. Experimental data from cyclic voltammetry (CV) and UV-Vis spectroelectrochemistry of solutions in acetonitrile were analyzed and compared with innovative density functional tight binding computational results. Our experimental and theoretical results provide a coherent explanation of the influence of CO2 on the CV data in terms of weak and strong binding nomenclature of the dianions. In addition to this terminology, we have identified the dihydroxy substituted AQ as a new class of molecules forming rather unstable [X-AQ-(CO2) n ]2- adducts. In contrast to the commonly used dianion consideration, the results presented herein reveal opposite trends in stability for the X-AQ-CO2•- radical species for the first time. To the best of our knowledge, this study presents theoretically calculated UV-Vis spectra for the various CO2-AQ reduction products for the first time, enabling a detailed decomposition of the spectroelectrochemical data. Thus, this work provides an extension of the existing classification with proof of the existence of X-AQ-CO2 species, which will be the basis of future studies focusing on improved materials for electrochemical CO2 capture.

In redox-transmetallation protolysis (RTP) reactions in tetrahydrofuran (thf) between excess scandium or cerium metal, Hg(C6F5)(2) and 3,5-dimethylpyrazole (Me(2)pzH) in silicone greased Schlenk flasks, formation of the 3,5-dimethyl-1-pyrazolyl(dimethyl)siloxide (Me(2)pzSiMe(2)O) ligand was observed. Thus the former reaction gave [Sc-2(Me(2)pz)(4)(Me(2)pzSiMe(2)O)(2)] 1 in good yield, whilst the latter gave a mixture of [Ce4O(Me(2)pz)(9)(Me(2)pzSiMe(2)O)(2)] 2 a, [Ce4O(Me(2)pz)(11)] 2 b, both mixed oxidation state species, and the Ce-IV complex [Ce(Me(2)pz)(4)(Me(2)pzH)] 2 c.