Sodium Cyclopentadienide Research Articles

An aminosilyl-functionalized zincocene

Abstract A (pyrrolidinyldimethylsilyl)tetramethyl zincocene was obtained by salt elimination reaction of the corresponding sodium cyclopentadienide with zinc(II) chloride and was characterized in solution and in the solid state, including the determination of its crystal structure. Furthermore, the zinc center was shown to exhibit Lewis-acidic character by coordination of an N-heterocyclic carbene.

Synthesis and characterization of pyrrole-based group 4 PNP pincer complexes

The synthesis, characterization, and reactivity of several group 4 metal complexes featuring a central anionic pyrrole moiety connected via CH2 linkers to two phosphine donors is described. Treatment of [P(NH)P-iPr] with [MCl4(THF)2] (M = Zr, Hf) in the presence of base yields the dimeric complexes [M(PNPiPr)(μ-Cl)(Cl)2]2 featuring two bridging chloride ligands. These complexes react with sodium cyclopentadienyl and SiMe3I to give the mononuclear complexes [M(PNPiPr)(η5-Cp)(Cl)2] and [M(PNPiPr)(I)3], respectively. The latter react with MeMgBr to form the trialkyl complexes [M(PNPiPr)(Me)3]. Upon treatment of [Ti(NMe2)4] with [P(NH)P-iPr] a complex with the general formula [Ti(PNPiPr)(NMe2)3] is obtained. DFT calculations revealed that the most stable species is [Ti(κ1N- PNPiPr)(NMe2)3] featuring a κ1N-bound PNP ligand. When [P(NH)P-iPr] is reacted with [Ti(NMe2)4] in CH2Cl2 complex [Ti(PNPiPr)(Cl)2(NMe2)] is formed. Treatment of a solution of [P(NH)P-iPr] and [Zr(NMe2)4] with SiMe3Br affords the anionic seven-coordinate tetrabromo complex [Zr(PNPiPr)(Br)4][H2NMe2]. The corresponding hafnium complex [Hf(PNPiPr)(Br)4][H2NEt2] is obtained in similar fashion by utilizing [Hf(NEt2)4] as metal precursor. All complexes are characterized by means of NMR spectroscopy. Representative complexes were also characterized by X-ray crystallography.Graphical abstract

Cyclopentadienyl capped thorium(IV) porphyrinoid complex.

The reaction between Th(IV) dipyriamethyrin dichloride and sodium cyclopentadienyl (Cp) results in the formation of a cyclopentadienyl capped thorium dipyriamethyrin complex, which to our knowledge represents the first expanded porphyrin f-element Cp complex.

Studies on Preparation, Characterization and Application of Porous Functionalized Glycidyl Methacrylate-Based Microspheres.

A one-step swelling and polymerization technique was used in the synthesis of porous glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EGDMA) monodisperse polymeric microspheres. The polystyrene (PS) seed obtained in the dispersion polymerization was used as a shape template. The presence of epoxide rings in the chemical structure of microspheres enables their post-polymerization chemical modifications involving: the Diels-Alder reaction with sodium cyclopentadienide and maleic anhydride, the reaction with 4,4′-(bismaleimido)diphenylmethane, and the thiol-Michael reaction with methacryloyl chloride and 2-mercaptopropionic acid. Changing the reaction mixture composition—the amounts of crosslinking monomer and PS seed as well as the type and concentration of porogen porous microspheres of different porous structures were obtained. Their porous structures were characterized in the dry and swollen states. The copolymers obtained from the equimolar monomers mixture modified in the above way were applied as the column packing materials and tested in the reverse-phase HPLC (High-Performance Liquid Chromatography). A few factors influencing morphology and porous structure of microspheres were studied.

Investigation on fluorescence property and Hirshfeld surface analysis of a novel heterobimetallic Cd(II)—Na(I) pyridine-terminal salamo-type coordination polymer

A novel heterometallic Cd(II)—Na(I) coordination polymer (Cd(II)—Na(I) CP), [{Cd(H2L)(OAc)(μ2-OAc)Na(OAc)(MeOH)(EtOH)}2]n is self-assembled via a reaction between Cd(OAc)2·H2O, NaN(CN)2, and a salamo-type ligand H2L containing terminal pyridine. It is structurally characterized. There are two kinds of metal atoms with different coordination modes. The N2O2 cavity of H2L is not involved in coordination, while the terminal pyridine nitrogen atoms are linked to Cd(II) atoms. Two kinds of acetate groups (OAc– and μ2-OAc–) are coordinated with Cd(II) atoms in different coordination modes; two identical Cd(II) atoms are bridged by oxygen atoms of μ2-OAc– groups. The Na(I) atoms are linked to Cd(II) atoms via one oxygen atom of μ2-OAc–; one acetate group (OAc–), one undeprotonated methanol and ethanol molecules are also coordinated with Na(I) atoms. With Cd(II) atoms as the node and the undeprotonated H2L ligand molecule as the linker, a coordination polymer with a larger pore size (25.04·17.66(2) Å2) is formed. Cd(II)—Na(I) CP can emit brighter green fluorescence, hence, it can be applied to the development of fluorescent materials. Various short-range interactions on the Cd(II)—Na(I) CP surface are studied by the Hirshfeld surface analysis.

Cover Feature: Sodium Cyclopentadienide as a New Type of Electrolyte for Sodium Batteries (ChemElectroChem 2/2021)

Cover Feature: Sodium Cyclopentadienide as a New Type of Electrolyte for Sodium Batteries (ChemElectroChem 2/2021)

Sodium Cyclopentadienide as a New Type of Electrolyte for Sodium Batteries

AbstractOwing to the low cost and high abundance of sodium, sodium‐based batteries, especially those employing metallic sodium anodes, are considered for post‐lithium energy storage. In order to develop high‐performance and long‐lasting sodium‐metal batteries, however, the reversible Na‐metal stripping and plating challenge must be addressed. Most organic electrolytes suffer from non‐uniform and continuous formation of the solid electrolyte interphase as well as unfavorable dendritic growth. The use of sodium cyclopentadienide dissolved in tetrahydrofuran as the electrolyte reveals an improved reversibility of sodium dissolution and electrodeposition combined with an electrochemical stability window of around 2.2 V vs. Na/Na+ and an ionic conductivity of 1.36 mS cm−1 at 25 °C. Furthermore, the plated electrodes showed a remarkable morphology of the Na deposits, that is, no dendrite formation, whereby the above‐mentioned electrolyte could overcome the aforementioned cycling issues, thus suggesting suitability for further studies.

Infrared photoacoustic spectroscopy as an alternative tool for the analysis of surface-modified glycidyl-based polymeric microspheres

The post-polymerization modification of porous glycidyl methacrylate – ethylene glycol dimethacrylate microspheres was subsequently achieved firstly by reacting the glycidyl functionalities with sodium cyclopentadienide and secondly by the Diels-Alder click reaction with maleic anhydride. Analysis of the surface-decorated spherical polymeric materials was performed using the Fourier transform vibrational (Raman), and infrared (attenuated total reflectance) spectroscopies. In addition, the FT-IR photoacoustic spectroscopy as an alternative, and interesting tool in the chemical analysis of modified polymers was used. The results from those three non-destructive complementary spectroscopic methods providing important molecular structural information were compared together.

Inverse Sandwich Cyclopentadienyl Complexes of Sodium in the Gas Phase.

Infrared multiple photon dissociation (IRMPD) experiments and electronic structure computations have been used to explore the structures and energetics of binding in gas phase sodium cyclopentadienyl complexes of the general form Na nCp n-1+. Computational work for the analogous anionic Na nCp n+1- complexes reveals nearly identical energetics for the loss of neutral NaCp units from both cationic and anionic species leading to the conclusion that the binding in the gas phase species is largely electrostatic, arising primarily from ion-ion and ion-dipole interactions. This is supported by an examination of the molecular orbitals of these species, which show no orbital overlap between the Na and Cp moieties. Observation of peaks in the IRMPD spectra, which do not correspond to any of the computed linear absorption frequencies, strongly suggest the contribution of overtone and combination bands.

A Route toward (Aminomethyl)cyclopentadienide Ligands and Their Group 4 Metal Complexes

A new method is described, by which N‐functionalized cyclopentadienide ligands are synthesized via the nucleophilic substitution of sodium cyclopentadienide onto Katritzky's (benzotriazolyl) compounds. This route enables the introduction of bulky and basic amines, separated from the cyclopentadienyl ring by a methylene spacer. The method thus represents a valuable alternative to the general fulvene route. The resulting ligands have been coordinated to titanium and zirconium, producing a series of discrete metallocene derivatives with a pendant amine arm. These complexes are extremely sensitive towards moisture, but they can easily be converted into benchtop‐stable ammonium chloride derivatives. The ligands and their complexes have been fully characterized by NMR and IR spectroscopy, elemental analysis and/or high resolution ESI‐MS. The solid‐state structures of ten complexes have been established by single‐crystal X‐ray diffraction analysis.

Unexpected Formation and Structural Characterization of a Dinuclear Sodium Half-Sandwich Complex

Treatment of N,N′-diisopropylcarbodiimide with sodium cyclopentadienide (NaCp) in a molar ratio of 1:1 in THF solution resulted in formation of the unexpected dinuclear sodium half-sandwich complex [NaC5H3{C(NHiPr)(=NiPr)}2-1,2]2 (1) as colorless crystals in low yield. The newly formed ligand, which belongs to the group of 6-aminofulvene-2-aldiminate ligands, coordinates to sodium in an η5-coordination mode via the cyclopentadienyl ring. Dimerization occurs through additional chelating κN,N′-coordination of the amidine substituents. The NMR data of 1 indicated a slow dimer/monomer equilibrium in solution. A serendipitously isolated hydrolysis product, {µ-(iPrNH)2C=O}2[NaC5H3{C(NHiPr)(=NiPr)}2-1,2]2 (2), contains the new 6-aminofulvene-2-aldiminate ligand in the N,N′-chelating coordination mode with the cyclopentadiene ring being uncoordinated. In this case, dimerization occurs through the presence of two bridging neutral N,N′-diisopropylurea ligands. Both compounds have been structurally characterized by single-crystal X-ray diffraction.

Investigation of the thermal properties of glycidyl methacrylate\u2013ethylene glycol dimethacrylate copolymeric microspheres modified by Diels\u2013Alder reaction

The study describes the thermal properties of functional microspheres composed of glycidyl methacrylate (GMA) and crosslinking agent ethylene glycol dimethacrylate (EGDMA). Copolymeric poly(GMA-co-EGDMA) microspheres were prepared via suspension–emulsion polymerization in the presence of toluene and decan-1-ol as porogens. In order to introduce functional groups, the porous methacrylate network was modified by epoxy ring opening with the use of sodium cyclopentadienide and then the Diels–Alder addition with maleic anhydride. The thermal properties of poly(GMA-co-EGDMA) materials were evaluated by thermogravimetry and differential scanning calorimetry. By TG/FTIR, it was observed that new functional materials exhibited multi-staged decomposition patterns, different from parent poly(GMA-co-EGDMA) microspheres. The synthesized poly(GMA-co-EGDMA) microspheres exhibited rather high thermal stability in inert atmosphere. Their initial decomposition temperature determined at the temperature of 2% of mass loss was about 210 °C; however, after the chemical modification it was slightly lower. The thermal degradation of parent poly(GMA-co-EGDMA) copolymer runs mainly according to the depolymerization mechanism, while functionalized by cyclopentadienyl group and maleic anhydride microspheres decompose through the chain scission mechanism.

Viking Helmet Corroles: Activating Inert Oxidometal Corroles.

Chemically inert oxidometal(V) corrols of molybdenum and rhenium undergo clean ligand-exchange reactions upon the action of SiCl4 . The resulting dichlorido complexes show trigonal prismatic coordination of the metal ion with the chlorine atoms residing in a cis configuration, and were studied by optical and resonance spectroscopy as well as DFT calculations. In situ reactivity studies with carbon nucleophiles indicate high reactivity for chlorine replacement. Treatment with sodium cyclopentadienide paves the way to robust molybdenum corrolocene half-sandwich complexes. These organometallic compounds are the first corrole species that stabilize an air-stable and diamagnetic low spin d2 -MoIV center. Structural, spectroelectrochemical, and chemical investigations prove a reversible MoIV /MoV redox couple close to the Fc/Fc+ potential for these systems. The high stability of the compounds in both redox states calls for future applications in catalysis and as redox switch.

Synthesis of Mono-, Bis- and Tris(pentafluoroethyl)tin Derivatives, (C2 F5 )4-n SnXn (X=Ph, Me, Cl, Br, Cp; n=1-3).

For (pentafluoroethyl)phenylstannanes, (C2 F5 )4-n SnPhn (n=1-3), and dimethylbis(pentafluoroethyl)stannane, (C2 F5 )2 SnMe2 , a high yield synthesis was developed by the use of LiC2 F5 as a C2 F5 transfer reagent. The treatment of these products with gaseous hydrogen chloride or hydrogen bromide afforded (C2 F5 )4-n SnXn (X=Cl, Br; n=1-3) in good yields. The (pentafluoroethyl)stannanes were fully characterized by 1 H, 13 C, 19 F and 119 Sn NMR, IR spectroscopy and mass spectrometry. The treatment of the (pentafluoroethyl)tin halides (C2 F5 )4-n SnXn with 1,10-phenanthroline (phen) led to the formation of the corresponding octahedrally coordinated complexes [(C2 F5 )4-n SnXn (phen)], the structures of which were elucidated by X-ray diffraction analyses. The bromostannane (C2 F5 )3 SnBr reacted with sodium cyclopentadienide to give the (η1 -cyclopentadienyl)tris(pentafluoroethyl)stannane, (C2 F5 )3 SnCp, for which single-crystal X-ray diffraction analysis could be performed. The coupling constants 1 J(119 Sn,13 C) and 2 J(119 Sn,19 F) of all new stannanes are strongly correlated and sensitive to the substitution pattern at the tin atom. For both coupling constants a negative sign could be assigned.

Control of clustering behavior in anionic cerium(iii) corrole complexes: from oligomers to monomers.

The first synthesis of anion capped cerium corrole complexes is reported. Unusual clustering of the lanthanide corrole units has been found and the degree of aggregation can be controlled by the choice of the capping ligand. A polymeric structure 1a, with the general formula [Cor-Ce(THF)-Cp-Na]n (Cor = 5,15-bis(2,4,6-trimethylphenyl)-10-(4 methoxyphenyl)-corrole, THF = tetrahydrofuran), is formed using sodium cyclopentadienide (NaCp) and a dimeric structure 2a, with the general formula [Cor-Ce-Tp]2, is formed when potassium tris(pyrazolyl)borate (KTp) is used. Encapsulation of the counter-cation leads to the isolation of the monomeric structures 1b and 2b, with the general formulas [AM(2.2.2-cryptand)][Cor-Cp-X] (AM = Na or K, X = Cp or Tp). The structural and spectroscopic properties of the complexes have been investigated.

Synthesis, Characterization, and Photocontrolled Ring-Opening Polymerization of Sila[1]ferrocenophanes with Multiple Alkyne Substituents

Sila[1]ferrocenophanes with multiple alkyne substituents [Fe(η-C5H4)2Si(C⋮CtBu)2] (2) and [Fe(η-C5H4)2Si(Me)C⋮CC⋮CPh] (5) have been synthesized and structurally characterized. These compounds are prepared by reacting [LiC⋮CtBu] or [LiC⋮CC⋮CPh] with sila[1]ferrocenophanes containing silicon−chlorine bonds. Ring-opening polymerizations (ROP) of 2 and 5 have been studied using transition metal-catalyzed, thermal, anionic, and photocontrolled routes. Thermal and anionic ROP both failed to give significant amounts of polymer (<30%). And unlike most other ferrocenophanes, 2 cannot be polymerized by Karstedt's catalyst, possibly due to chelation of the catalyst by the acetylide ligands. Platinum-catalyzed ROP of 5 was also relatively ineffective, giving polymers with bimodal molecular weight distributions in moderate yields. Nevertheless, living polymerization of 2 and 5 was possible using photocontrolled ROP with NaCp as initiator. The key to photocontrolled ROP was the reduced basicity of NaCp compared to BuLi...

Diels–Alder Reaction as a Tool to Modify the Surface of Polymeric Microspheres

The study describes the synthesis of glycidyl methacrylate microspheres cross-linked with ethylene glycol dimethacrylate. With the use of suspension–emulsion polymerization, microspheres with different degrees of cross-linking were prepared. Their chemical modification involved several steps: at the beginning, the epoxide ring was opened using sodium cyclopentadienide; in the next step, materials with grafted cyclopentadiene fragments were then subjected to Diels–Alder reaction with maleic anhydride; in the last step, the anhydride groups were turned into carboxylic groups. To confirm the attachment of cyclopentadiene to the microspheres surface, the material obtained was treated with fluorescence marker N-(1-pyrene) maleimide. The resulting material has fluorescent properties in the UV wavelength of 366 nm. Moreover, to confirm the chemical structure of modified materials, attenuated total reflection-Fourier transform infrared spectroscopy analysis was performed. Thermal stability in inert atmosphere of ...

ChemInform Abstract: Low‐Temperature Olefin Syntheses in View of Parent Fulvenes and Fulvalenes

AbstractReview: 94 refs.

Preparation, characterization, and catalytic activity of zirconocene bridged on surface of silica gel

Zirconocene catalyst supported on silica gel was prepared for olefin polymerization by surface modification of calcined silica with SiCl4, and the reaction between the modified silica and cyclopentadienyl sodium and ZrCl4. The catalyst was characterized by using Fourier-transform infrared (FT-IR) spectrometer, thermogravimetric (TG), and differential scanning calorimetric (DSC) analytic spectrometer. It was found that the metallocene structure could be formed and connected on silica surface by chemical bond. Initial catalytic tests showed that the supported metallocene was catalytically active (methylaluminoxane as a cocatalyst), producing polymer with higher molecular weight than the metallocene just immobilized on the surface of silica gel.

Low‐Temperature Olefin Syntheses in View of Parent Fulvenes and Fulvalenes

AbstractParent fulvenes and fulvalenes are thermally unstable cross‐conjugated olefins for which low‐temperature syntheses are indispensable. In this review 5 syntheses (in the temperature range between −100 and −10°) are discussed: 1. Reaction of sodium cyclopentadienide with 1‐acetoxy‐1‐chloroalkanes or 1‐acetoxy‐1‐bromoalkanes (26) gives acetoxy‐alkyl‐cyclopentadienes (27) which are easily converted to pentafulvenes (2) by low‐temperature HOAc‐elimination with NEt3. This synthesis has been applied to parent pentafulvene (2a), heptafulvene (3a), nonafulvene (4a) and sesquifulvalene (19a) (Schemes 8–11). 2. Based on a nearly quantitative oxidative coupling of cyclononatetraenide (8) to give dihydrononafulvalene (38) (Scheme 10), a general synthetic plan for fulvalenes has been outlined (Scheme 11) and applied to the synthesis of pentafulvalene (12), nonapentafulvalene (16) and nonafulvalene (14). Several applications of oxidative couplings of Hückel anions are discussed (Schemes 20 and 21). 3. Trifunctional cyclopropanes 67 (in most cases 1,1‐dibromo‐2‐X‐cyclopropanes) are attractive precursors of parent triafulvene (1a) and calicene (17) (Scheme 18). Contrary to classical procedures they are transformed into nucleophiles (67→68) by halogen‐lithium exchange, methylation (68→69) and HBr‐elimination to give 1‐methylidene‐2‐X‐cyclopropanes of type 71. By subsequent HX‐elimination triafulvene (1a) has been synthesized and trapped as a [4+2]‐cycloadduct 73 (Scheme 20). Furthermore, calicene precursors 77 are available by using cyclopentenone as an electrophilic cyclopentadiene equivalent. 4. Similarly, 1‐lithio‐1‐bromo‐2‐X‐cyclopropanes 68 are directly transformed into triafulvalene precursors 81 (Scheme 26) by a novel CuCl2‐catalyzed oxidative coupling. 5. In view of the synthesis of parent triafulvene (1a), triafulvalene (11) and calicene (17), retro‐DielsAlder reactions of stable precursors – prepared by low‐temperature reactions (described in chapters 3 and 4) – have been explored.