Lanthanide(III) nitrobenzenesulfonates and p-toluenesulfonate complexes of lanthanide(III), iron(III), and copper(II) as novel catalysts for the formation of calix[4]resorcinarene

Lanthanide(III) salts of p-toluenesulfonic acid [lanthanide(III) tosylates, Ln(TOS)₃] and nitrobenzenesulfonic acid [Ln(NBSA)₃], and p-toluenesulfonate complexes of iron(III) and copper(II) were prepared, characterized, and examined as catalysts for the synthesis of resorcinol-derived calix[4]resorcinarenes. The reaction of resorcinol with benzaldehyde yields two isomers, the all-cis isomer (rccc) and the cis-trans-trans isomer (rctt) with the relative isomer ratios depending on the reaction conditions. However, in the reaction of resorcinol with octanal only one isomer, the all-cis isomer, is formed in high yields with less than 0.1 mol % of Yb(TOS)₃. Examination of lanthanide(III) tosylates and lanthanide(III) nitrobenzenesulfonates revealed that ytterbium(III) 4-nitrobenzenesulfonate [ytterbium(III) nosylate, Yb(4-NBSA)₃] and ytterbium(III) 2,4-dinitrobenzenesulfonate [Yb(2,4-NBSA)₃] are the most active catalysts. The catalysts could be easily recovered and reused several times for resorcinarene formation without loss of efficiency. Surprisingly good results were also obtained with iron(III) and copper(II) p-toluenesulfonates. Besides optimizing the reaction conditions, new insights into the reaction mechanism were also obtained.     

Neuartige Synthese eines Lanthanoidtrialkyls – Charakterisierung und Kristallstruktur von Yb(CH2tBu)3(thf)2

Novel Synthesis of a Lanthanide Trialkyl – Characterization and Crystal Structure of Yb(CH₂ t Bu)₃(thf)₂ The solvated ytterbium alkyl Yb(CH₂tBu)₃(thf)₂ ( 1 ) was obtained in moderate yield from the reaction of ytterbium metal with neopentyl iodide. Ruby‐red air‐sensitive crystals of 1 were characterized by melting point, elemental analysis, IR, NMR, and UV/Vis spectroscopy and by X‐ray crystallography. In the solid state the ytterbium atom shows a trigonal bipyramidal coordination with the neopentyl groups and the THF ligands occupying equatorial and axial positions, respectively.     

Yb3F4S2: Ein gemischtvalentes Ytterbiumfluoridsulfid gemäß YbF2 · 2 YbFS

Yb₃F₄S₂: A mixed‐valent Ytterbium Fluoride Sulfide according to YbF₂ · 2 YbFS Attempts to synthesize ytterbium(III) fluoride sulfide (YbFS) from 2 : 3 : 1‐molar mixtures of ytterbium metal (Yb), elemental sulfur (S) and ytterbium trifluoride (YbF₃) after seven days at 850 °C in silica‐jacketed gastight‐sealed arc‐welded tantalum capsules result in the formation of the mixed‐valent ytterbium(II,III) fluoride sulfide Yb₃F₄S₂ (tetragonal, I4/mmm; a = 384,61(3), c = 1884,2(4) pm; Z = 2) instead. The almost single‐phase product becomes even single‐crystalline and emerges as black shiny platelets with square cross‐section when equimolar amounts of NaCl are present as fluxing agent. Its crystal structure can be described as a sheethed intergrowth arrangement of one layer of CaF₂‐type YbF₂ followed by two layers of PbFCl‐type YbFS parallel (001). Accordingly there are two chemically and crystallographically different ytterbium cations present. One of them (Yb²⁺) is surrounded by eight fluoride anions in a cubic fashion, the other one (Yb³⁺) exhibits a capped square‐antiprismatic coordination sphere consisting of four F^– and five S^2– anions. In spite of being structurally very plausible, the obvious ordering of the differently charged ytterbium in terms of a localized mixed valency can only be fictive because of the black colour of Yb₃F₄S₂ which rather suggests charge delocalization coupled with polaron activity.     

Novel Process for Synthesis of 1,2,4‐Triazoles: Ytterbium Triflate–Catalyzed Cyclization of Hydrazonyl Chlorides with Nitriles

Abstract

A series of 1,3,5‐trisubstituted 1,2,4‐triazoles were synthesized via the intermolecular cyclization of hydrazonyl chlorides with nitriles catalyzed by ytterbium triflate [Yb(OTf)₃]. The amount of catalysis was discussed and Yb(OTf)₃ could be reused without loss of activity.     

Magnetic Investigations and 151Eu Mössbauer Spectroscopy of MYbSi4N7 with M = Sr,Ba, Eu

The isotypic nitridosilicates MYb[Si₄N₇] (M = Sr, Ba, Eu) were obtained by the reaction of the respective metals with Si(NH)₂ in a radiofrequency furnace below 1600 °C. On the basis of powder diffraction data of MYb[Si₄N₇] Rietveld refinements of the lattice constants were performed; these confirmed the previously published single‐crystal data. The compounds contain a condensed network of corner‐sharing [N(SiN₃)₄] units. The central nitrogen thus exhibits ammonium character. Magnetic susceptibility measurements of MYb[Si₄N₇] (M = Sr, Ba, Eu) show paramagnetic behavior with experimental magnetic moments of 3.03(2), (Sr), 2.73(2) (Ba), and 9.17(2) (Eu) μ_B per formula unit. In EuYbSi₄N₇ the europium and ytterbium atoms are in stable divalent and trivalent states, respectively. According to the non‐magnetic character of the alkaline earth cations, ytterbium has to be in an intermediate valence state Yb^III‐x in the strontium and barium compound. Consequently, either a partial exchange N^3—/O^2— resulting in compositions MYb^III‐x[Si₄N_7—xO_x] or an introduction of anion defects according to MYb^III‐x[Si₄N_7—x/3□_x/3] has to be assumed. The phase width 0 ≤ x ≤ 0.4 was estimated according to the magnetic measurements. ¹⁵¹Eu Mössbauer spectra of EuYb[Si₄N₇] at 78 K show a single signal at an isomer shift of δ = —12.83(3) mm s^—1 subject to quadrupole splitting of ΔE_Q = 5.7(8) mm s^—1, compatible with purely divalent europium.     

A Novel Divalent Ytterbium Complex Supported by a Bridged Diamide Ligand: Synthesis and Structure of [{Me2Si(NPh)2Yb(THF)2}(μ3‐Cl)(μ4‐Cl){Li(THF)}2]2·2THF

The reaction of anhydrous YbCl₃ with 1 equiv. of Li₂Me₂Si(NPh)₂ in THF, after workup, yielded a ytterbium(III) chloride [{Me₂Si(NPh)₂Yb}(μ₂‐Cl)(TMEDA)]₂·3PhMe ( 1 ) (TMEDA=tetramethylethanediamine). The same reaction followed by treatment with Na‐K alloy afforded a new ytterbium(II) complex supported by a bridged diamide with four coordinated LiCl molecules, [{Me₂Si(NPh)₂Yb(THF)₂}(μ₃‐Cl)(μ₄‐Cl){Li(THF)}₂]₂·2THF ( 2 ) in high yield. Both complexes were structurally characterized by X‐ray analysis to be dimers. Complex 1 was a chlorine‐bridged dimer with ytterbium in a distorted octahedral geometry. In complex 2 two [Me₂Si(NPh)₂Yb(THF)₂]‐(μ₃‐Cl)[Li(THF)]₂ moieties were connected with each other by two μ₄‐Cl bridges to form a "chair‐form" framework.     

Two new phosphate langbeinites,Rb2YbTi(PO4)3 and Rb2Yb0.32Ti1.68(PO4)3, investigated at 293 and 150 K

The rubidium ytterbium titanium phosphates Rb₂YbTi(PO₄)₃, (I), and Rb₂Yb_0.32Ti_1.68(PO₄)₃, (II), have been structurally characterized from X‐ray data collected at both 293 and 150 K. Compound (II) is blue owing to the presence of mixed‐valence titanium (41% Ti³⁺ + 59% Ti⁴⁺). Both (I) and (II) belong to the langbeinite structure type, with mixed Yb/Ti populations in the two crystallographically independent octahedral sites (of symmetry 3). Ytterbium favours one of these sites, where about two‐thirds of the Yb atoms are found. The O‐atom displacement parameters are large in both compounds at both temperatures.     

Enhancing the Value of Free Metals in the Synthesis of Lanthanoid Formamidinates: Is a Co‐oxidant Needed?

Treatment of N,N′‐bis(aryl)formamidines (ArFormH), N,N′‐bis(2,6‐difluorophenyl)formamidine (DFFormH) or N,N′‐bis(2,6‐diisopropylphenyl)formamidine (DippFormH), with europium metal in CH₃CN is an efficient synthesis of the divalent complexes: [{Eu(DFForm)₂(CH₃CN)₂}₂] ( Eu1 ) or [Eu(DippForm)₂(CH₃CN)₄] ( Eu2 ). The synthetic method was extended to ytterbium, but the metal required activation by addition of Hg⁰. With DFFormH in CH₃CN, [{Yb(DFForm)₂(CH₃CN)}₂] ( Yb1 ) was obtained in good yield, and [Yb(DFForm)₂(thf)₃] ( Yb3 ) was obtained from a synthesis in CH₃CN/THF. Thus, this synthetic method completely circumvents the use of either salt metathesis, or redox transmetallation/protolysis (RTP) protocols to prepare divalent rare‐earth formamidinates. Heating Yb1 in PhMe/C₆D₆ resulted in decomposition to trivalent products, including one from a CH₃CN activation process. For a synthetic comparison, divalent ytterbium DFForm and DippForm complexes were synthesised by RTP reactions between Yb⁰, Hg(R)₂ (R=Ph, C₆F₅), and ArFormH in THF, leading to the isolation of either [Yb(DFForm)₂(thf)₃] ( Yb3 ), or the first five coordinate rare‐earth formamidinate complex [Yb(DippForm)₂(thf)] ( Yb4 b ), and, from adjustment of the stoichiometry, trivalent [Yb(DFForm)₃(thf)] ( Yb6 ). Oxidation of Yb3 with benzophenone (bp), or halogenating agents (TiCl₄(thf)₂, Ph₃CCl, C₂Cl₆) gave [Yb(DFForm)₃(bp)] or [Yb(DFForm)₂Cl(thf)₂], respectively. Furthermore, the structural chemistry of divalent ArForm complexes has been substantially broadened. Not only have the highest and lowest coordination numbers for divalent rare‐earth ArForm complexes been achieved in Eu2 and Yb4 b , respectively, but also dimeric Eu1 and Yb1 have highly unusual ArForm bridging coordination modes, either perpendicular μ‐1κ(N:N′):2κ(N:N′) in Eu1 , or the twisted μ‐1κ(N:N′):2κ(N′:F′) DFForm coordination in Yb1 , both unprecedented in divalent rare‐earth ArForm chemistry and in the wider divalent rare‐earth amidinate field.     

Yb2+3—xPd12—3+xP7 (x = 0.40): Different Ytterbium Species in a Substituted Structural Motif of the Zr2Fe12P7 Type

The new compound Yb_2+3—xPd_12—3+xP₇ x = 0.40(4)) was synthesized by sintering of a mixture of elemental components at 1100 °C with subsequent annealing at 800 °C. The crystal structure of Yb_2+3—xPd_12—3+xP₇ was solved and refined from X‐ray single‐crystal diffraction data: space group P6¯, a = 10.0094(4)Å, c = 3.9543(2)Å, Z = 1; R(F) = 0.022 for 814 observed unique reflections and 38 refined parameters. The atomic arrangement reproduces a structure motif of the hexagonal Zr₂Fe₁₂P₇ type in which one of the transition metal positions is substituted predominantly by ytterbium (Yb : Pd = 0.86(1) : 0.14). The ytterbium atoms are embedded in the 3D polyanion formed by palladium and phosphorus atoms. Two different environments for ytterbium atoms are present in the structure. Magnetic susceptibility measurements and XAS spectroscopy at the Yb L_III edge show the presence of ytterbium in two electronic configurations, 4?¹³ and 4?¹⁴. The following model was derived. Ytterbium atoms in the 3k site are in the 4?¹³ state, the two remaining positions contain ytterbium in intermediate‐valence states, giving totally 79 % ytterbium in the 4?¹³ electronic configuration.     

Synthesis and Structural Characterization of Some Potassium Complexes of Some Bis(phenolate) Ligands and Some Novel Heterobimetallic Binuclear Arrays Formed with Trivalent Lanthanoid Ions

The structural characterizations of the potassium complexes of a pair of dianionic bis(phenolate) ligands, {L^R = [^?OC₆H₂(2,4‐Bu^t)(6‐CH₂)]₂NCH₂CH₂R} R = NMe₂, OMe, crystallized from 1,2,‐dimethoxyethane (DME) are recorded, showing them to take the binuclear form [K₂L^R(DME)₃]. A pair of neutral binuclear heterobimetallic isotypic complexes are defined with ytterbium(III), with phenol, as sodium salts, of the form [Yb(L^R)(OPh)₂Na(DME)(HOPh)], and a further array with samarium(III), of the (partially protonated) form [Sm(L^OMe)₂Na(OH₂)]. A further complex, [Na(DME)₃][Yb(*L^py)₂], results from an unusual ligand reduction by an ytterbium(II) species to give a new dianionic Schiff base ligand which is coordinated to ytterbium(III) {*L^py = ^?OC₆H₂(2,4‐Bu^t)(6‐CH=N‐CH‐2‐C₆H₄N)}.     

Crystal Structure of Di[(μ‐benzoato‐O,O′)bis(η5‐methylcylopentadienyl)ytterbium(III)]

Transparent orange‐red crystals of [Yb(MeCp)₂(O₂CPh)]₂ obtained by oxidation of Yb(MeCp)₂ with Tl(O₂CPh) in tetrahydrofuran have a dimeric structure with bridging bidentate (O,O′)‐benzoate groups and eight‐coordinate ytterbium.     

Synthesis and Structural Characterization of Several Ytterbium Bis(trimethylsilyl)amides Including Base‐free [Yb{N(SiMe3)2}2(μ‐Cl)]2 — A Coordinatively Unsaturated Complex with Additional Agostic Yb···(H3C—Si) Interactions

The reaction of YbCl₃ with two equivalents of NaN‐(SiMe₃)₂ has afforded a mixture of several ytterbium bis(trimethylsilyl) amides with the known complexes [Yb{N(SiMe₃)₂}2(μ‐Cl)(thf)]₂ ( 1 ) and [Yb{N(SiMe₃)₂}₃]( 4 ) as the main products and the cluster compound [Yb₃Cl₄O{N(SiMe₃)₂}₃(thf)₃]( 2 ) as a minor product. Treatment of 1 and 2 with hot n‐heptane gave the basefree complex [Yb{N(SiMe₃)₂}₂(μ‐Cl)]₂ ( 3 ) in small yield. The structures of compounds 1—4 and the related peroxo complex [Yb₂{N(SiMe₃)₂}₄(μ‐O₂)(thf)₂]( 5 ) have been investigated by single crystal X‐ray diffraction. In the solid‐state, 3 shows chlorobridged dimers with terminal amido ligands (av. Yb—Cl = 262.3 pm, av. Yb—N = 214.4 pm). Additional agostic interactions are observed from the ytterbium atoms to four methyl carbon atoms of the bis(trimethylsilyl)amido groups (Yb···C = 284—320 pm). DFT calculations have been performed on suitable model systems ([Yb₂(NH₂)₄(μ‐Cl)₂(OMe₂)₂]( 1m ), [Yb₂(NH₂)₄(μ‐Cl)₂]( 3m ), [Yb‐(NH₂)₃]( 4m ), [Yb₂(NH2₄(μ‐O₂)(OMe₂)₂]( 5m ), [Yb{N‐(SiMe₃)₂}₂Cl] ( 3m/2 ) and Ln(NH₂)₂NHSiMe₃ (Ln = Yb ( 6m ), Y ( 7m )) in order to rationalize the different experimentally observed Yb—N distances, to support the assignment of the O—O stretching vibration (775 cm ^‐1) in the Raman spectrum of complex 5 and to examine the nature of the agostic‐type interactions in σ‐donorfree 3 .     

One‐Step Reaction of Friedel–Crafts Acylation and Demethylation of Aryl‐Methyl Ethers Catalyzed by Ytterbium(III) Triflate

Abstract

Catalytic amount of ytterbium(III) triflate [Yb(OTf)₃] has been used to catalyze Friedel–Crafts acylation and demethylation of aryl‐methyl ethers in one‐step reaction to produce hydroxyacylphenones with moderate yields under mild conditions.     

N‐Heterocyclic Carbene–Ytterbium Amide as a Recyclable Homogeneous Precatalyst for Hydrophosphination of Alkenes and Alkynes

The N‐heterocyclic carbene–ytterbium(II) amides (NHC)₂Yb[N(SiMe₃)₂]₂ ( 1 : NHC: 1,3,4,5‐tetramethylimidazo‐2‐ylidene (IMe₄); 2 : NHC: 1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene (IiPr)) and the NHC‐stabilized rare‐earth phosphide (IMe₄)₃Yb(PPh₂)₂ ( 3 ) have been synthesized and fully characterized. Complexes 1 – 3 are active precatalysts for the hydrophosphination of alkenes, alkynes, and dienes and exhibited much superior catalytic activity to that of the NHC‐free amide (THF)₂Yb[N(SiMe)₂]₂. Complex 1 is the most active precursor among the three complexes. In particular, complex 1 can be recycled and recovered from the reaction media after the catalytic reactions. Furthermore, it was found that complex 3 could catalyze the polymerization of styrene to yield atactic polystyrenes with low molecular weights. To the best of our knowledge, complex 1 represents the first rare‐earth complex that can be recovered after catalytic reactions.     

Synthesis,Structure, and Catalytic Behavior of Ytterbium Complexes Derived from a Linked Bis(β‐ketoiminato) Ligand

Ytterbium complexes supported by a linked bis(β‐ketoiminato) ligand, N,N′‐ethylenebis(benzoylacetoimine) (H₂L), were synthesized and their catalytic behavior was explored. The reaction of YbCl₃ with 1 equiv. of LLi₂ afforded the mononuclear ytterbium chloride LYbCl(THF)₂ ( 1 ) in high yield. Complex 1 can be used as starting material to prepare β‐ketoiminate‐ytterbium derivatives. Treatment of complex 1 with NaN(SiMe₃)₂ produced the dimeric ytterbium amide {LYb[N(SiMe₃)₂]}₂ ( 2 ), while the similar reaction of complex 1 with NaOAr (ArO = 2, 6‐tBu‐4‐MeC₆H₂O) led to the mononuclear ytterbium aryloxide LYbOAr(THF) ( 3 ). The three complexes were well detected by elemental analysis and single‐crystal X‐ray analysis. It was found that complexes 2 and 3 can initiate the ring‐opening polymerization of ?‐caprolactone with moderate activity.     

Syntheses and Crystal Structures of Potassium–Lanthanoid(III) Complexes with the 1,2‐Benzenedisulfonate Ligand

The complexes [K(H₂O)₂LnL₂] (Ln = La or Nd; L = 1,2‐benzenedisulfonate) and [K(H₂O)Yb(H₂O)₄L₂] were initially isolated fortuitously from attempts to prepare the corresponding Ln₂L₃ complexes from Ln₂O₃ and H₂L in water. Indeed the bulk products from these reactions have the composition Ln₂L₃. Subsequently, deliberate syntheses by reacting equimolar amounts of Ln₂L₃ with K₂L in water gave the complexes in good yield. X‐ray crystal structures of [K(H₂O)₂LnL₂] (Ln = La or Nd) showed the complexes to be isostructural with a two dimensional polymeric network structure in which LnL₂ units are linked into chains crosslinked by potassium ions. Each Ln is nine coordinate with solely sulfonate oxygen donor atoms. Between adjacent lanthanoid ions there are three different types of sulfonate bridges and two examples of each. Most noteworthy is highly unsymmetrical bridging through μ‐η²‐sulfonate oxygen atoms. Consequently, one Ln–O bond is ca. 0.5 Å longer than the other eight. Potassium is nine‐coordinate with seven sulfonate oxygen atoms and two aqua ligands, and surprisingly <K–O(sulfonate)> is much longer than <K–O(H₂O)>. Pairs of potassium ions are linked by two μ‐η²‐sulfonate oxygen atoms, which are unsymmetrically bridging. The structure of [K(H₂O)Yb(H₂O)₄L₂] comprises discrete tetranuclear units containing two independent ytterbium ions, each coordinated by four water molecules and two chelating (via seven membered rings) disulfonate ligands, and two potassium ions, each coordinated by six sulfonate oxygen atoms and a water molecule. For each potassium, four of the coordinated sulfonate oxygen atoms are from sulfonate ligands bonded to one ytterbium atom and two from sulfonate ligands attached to the other ytterbium atom. In contrast to the Nd and La complexes, <K–O(sulfonate)> is shorter than <K–O(H₂O)>.     

Mild and Convenient Synthesis of 1,2‐Dihydroquinolines from Anilines and Acetone Catalyzed by Ytterbium(III) Triflate in Ionic Liquids

A mild, convenient, and efficient process has been developed for the synthesis of 2,2,4‐trimethyl‐1,2‐dihydroquinolines by the reaction of anilines with acetone catalyzed by ytterbium(III) triflate [Yb(OTf)₃] in ionic liquids. The catalyst and ionic liquids can be easily recovered and reused, making this method friendly and environmentally acceptable.     

Reactivity of Lanthanoid Aryloxide Complexes: Isolation of a 1,2‐Dimethoxyethane Cleavage Product

[Yb(OAr)₂(μ‐OMe)(DME)]₂ ( 1 ) (OAr = 2,6‐di‐iso‐propylphenolate) was synthesised via a redox transmetallation ligand exchange reaction between ytterbium metal, diphenylmercury and 2,6‐di‐isopropylphenol in DME. The source of the methoxy groups is from cleavage of DME, and the C‐O bond activation is unexpected given that the reaction was undertaken at ambient temperature. Each Yb³⁺ metal ion in 1 is six coordinate, and the coordination arrangement around each metal ion is distorted trigonal antiprismatic with Yb‐O(OMe) bond lengths (2.191(2) and 2.258(2) Å) shorter than the Yb‐O(aryloxide) bond distances (2.094(2) and 2.074(2) Å).     

Cs[Yb(NPPh3)4] – ein homoleptischer Phosphaniminato‐Komplex des Ytterbiums

Cs[Yb(NPPh₃)₄] – a Homoleptic Phosphoraneiminato Complex of Ytterbium Cesium tetrakis(phosphoraneiminato)ytterbate, Cs[Yb(NPPh₃)₄] ( 1 ) has been prepared by the reaction of the dimeric complex [Yb(NPPh₃)₃]₂ with CsNPPh₃ in thf solution. 1 crystallizes from thf solution to give colourless moisture sensitive crystals which contain three molecules thf per asymmetric unit. According to the crystal structure determination 1 forms a dimeric ion ensemble [Cs{Yb(NPPh₃)₄}]₂ in which the Cs⁺ ions connect the [Yb(NPPh₃)₄]^– ions via Cs…N bridges. The ytterbium atoms are distorted tetrahedrally coordinated by the nitrogen atoms of the phosphoraneiminato ligands (NPPh₃^–) with short Yb–N‐bond lengths between 212.1 and 221.9(8) pm. The included thf molecules are without bonding contacts with the complex. [Cs{Yb(NPPh₃)₄}]₂ · 6 thf: Space group P 1, Z = 2, lattice dimensions at 193 K: a = 1837.2(2), b = 2041.5(2), c = 2095.8(2) pm, α = 79.953(13)°, β = 79.364(11)°, γ = 88.239(12)°, R = 0.0625.     

When Metathesis Reactions Go Wrong: Novel Structural Consequences

The complex [Yb(Ph₂pz)₃(LiOBu)]₂ ( 1 ) (Ph₂pz = 3,5‐diphenylpyrazolate), fortuitously obtained from reaction of Yb metal with a lithium containing sample of [SnMe₃(Ph₂pz)] at elevated temperatures forms a centrosymmetric butoxy‐ and pyrazolate‐bridged open box structure. Each ytterbium atom is eight coordinate with one chelating Ph₂pz ligand, one μ‐η²:η² bridging pyrazolate, one μ‐η²(Yb):η⁴(Li) Ph₂pz group and two bridging butoxide ligands. Each lithium atom is unsymmetrically chelated by an η²‐Ph₂pz group, η⁴(N,C(pz)C₂(Ph)) bonded by another pyazolate group, and bridged through a butoxide oxygen atom to two ytterbium atoms. The type of η⁴‐pyrazolate coordination is unprecedented and is the first observation of interactions to a metal by the Ph rings of the Ph₂pz ligand. The complex [Li(dme)₃][Eu(Ph₂pz)₃(dme)] ( 2 ) obtained from reaction of Eu metal with the same sample of [SnMe₃(Ph₂pz)] in dme at room temperature is a charged separated species with the first anionic pyrazolatolanthanoidate(II) complex in which europium is eight coordinate with three chelating Ph₂pz ligands and a chelating dme.