Organoamido- and aryloxo-lanthanoids. XIII [1]. Organometallic compounds of the lanthanoids. CV [2]. New Lanthanoid(III) Complexes with Pyrazolate Ligands

The complexes Er(Me₂pz)₃(thf) and Ln(Ph₂pz)₃(thf)_n (Ln = Sc, Y, Gd, Er, n = 2; Ln = Lu, n = 3) (Me₂pz^? = 3,5-dimethylpyrazolate, thf = tetrahydrofuran, Ph₂pz^? = 3,5-diphenylpyrazolate) have been prepared by reaction of the lanthanoid metal with bis(pentafluorophenyl)mercury and the pyrazole in thf. The Ln(Ph₂pz)₃(thf)₂ complexes are considered to be eight coordinate with three η²-Ph₂pz ligands. Other lanthanoid pyrazolate complexes, Y(pz)₃(thf)₂, La(Me₂pz)₃(thf), Cp₂Ln(Me₂pz)(thf)_n (Ln = Y, Lu, n = 0; Ln = Lu, n = 1), (C₅Me₅)₂Y(pz)(thf), (C₅Me₅)₂Y(Mepz)(thf), (C₅Me₅)₂Y(Me₂pz)(thf)₂ (pz^? = pyrazolate, Mepz^? = 3-methylpyrazolate, Cp = cyclopentadienyl) have been synthesized by reaction of LnCl₃, Cp₂LnCl, or (C₅Me₅)₂LnCl with the appropriate sodium pyrazolate in thf. The structure of Ln(Me₂pz)₃(thf) (Ln = La or Er) is considered to be a symmetrical dimer with four chelating and two bridging Me₂pz groups, and two bridging thf ligands, whereas the cyclopentadienyl complexes are most likely dimers with bridging pyrazolate groups, and lattice thf of solvation.     

Syntheses and Crystal Structures of Lanthanide Chloride Complexes with Diglyme

Reactions of [LnCl₃(DME)₂] (Ln = Nd, Sm, Ho, Lu; DME = dimethoxyethane) and diglyme (diglyme = diethylen glycol dimethyl ether) in THF resulted in polymeric [LnCl₃(diglyme)]_n (Ln = Nd ( 1 ), Sm ( 2 )) or mononuclear complexes [LnCl₃(diglyme)(THF)] (Ln = Ho ( 3 ), Lu ( 4 )). Neodymium and samarium atoms in 1 and 2 are eight‐coordinated by three oxygen atoms from diglyme, one terminal and four bridging chloride ions. Holmium and lutetium atoms in 3 and 4 are seven‐coordinated by three oxygen atoms from diglyme, three chloride ions and one oxygen atom from THF. [ErCl₃(diglyme)(H₂O)] ( 5 ) resulted from the reaction of ErCl₃·6H₂O, (CH₃)₃SiCl and diglyme in THF. The molecular structures of 3 , 4 and 5 are similar, with either a molecule of THF coordinated to the lanthanide atom in 3 and 4 or with a molecule of water coordinated in 5 .     

Steric modulation of coordination number and reactivity in the synthesis of lanthanoid(III) formamidinates

Reactions of a range of the readily prepared and sterically tunable N,N'-bis(aryl)formamidines with lanthanoid metals and bis(pentafluorophenyl)mercury (Hg(C6F5)2) in THF have given an extensive series of tris(formamidinato)lanthanoid(III) complexes, [Ln(Form)3(thf)n], namely [La(o-TolForm)3(thf)2], [Er(o-TolForm)3(thf)], [La(XylForm)3(thf)], [Sm(XylForm)3], [Ln(MesForm)3] (Ln=La, Nd, Sm and Yb), [Ln(EtForm)3] (Ln=La, Nd, Sm, Ho and Yb), and [Ln(o-PhPhForm)3] (Ln=La, Nd, Sm and Er). [For an explanation of the N,N'-bis(aryl)formamidinate abbreviations used see Scheme 1.] Analogous attempts to prepare [Yb(o-TolForm)3] by this method invariably yielded [{Yb(o-TolForm)2(mu-OH)(thf)}2], but [Yb(o-TolForm)3] was isolated from a metathesis synthesis. X-ray crystal structures show exclusively N,N'-chelation of the Form ligands and a gradation in coordination number with Ln3+ size and with Form ligand bulk. The largest ligands, MesForm, EtForm and o-PhPhForm give solely homoleptic complexes, the first two being six-coordinate, the last having an eta1-pi-Ar--Ln interaction. Reaction of lanthanoid elements and Hg(C6F5)2 with the still bulkier DippFormH in THF resulted in C--F activation and formation of [Ln(DippForm)2F(thf)] (Ln=La, Ce, Nd, Sm and Tm) complexes, and o-HC6F4O(CH2)4DippForm in which the formamidine is functionalised by a ring-opened THF that has trapped tetrafluorobenzyne. Analogous reactions between Ln metals, Hg(o-HC6F4)2 and DippFormH yielded [Ln(DippForm)2F(thf)] (Ln=La, Sm and Nd) and 3,4,5-F3C6H2O(CH2)4DippForm. X-ray crystal structures of the heteroleptic fluorides show six-coordinate monomers with two chelating DippForm ligands and cisoid fluoride and THF ligands in a trigonal prismatic array. The organometallic species [Ln(DippForm)2(C[triple chemical bond]CPh)(thf)] (Ln=Nd or Sm) are obtained from reaction of Nd metal, bis(phenylethynyl)mercury (Hg(C[triple chemical bond]CPh)2) and DippFormH, and the oxidation of [Sm(DippForm)2(thf)2] with Hg(C[triple chemical bond]CPh)2, respectively. The monomeric, six-coordinate, cisoid [Ln(DippForm)2(C[triple chemical bond]CPh)(thf)] complexes have trigonal prismatic geometries and rare (for Ln) terminal C[triple chemical bond]CPh groups with contrasting Ln--C[triple chemical bond]C angles (Ln=Nd, 170.9(4) degrees; Ln=Sm, 142.9(7) degrees). Their formation lends support to the view that [Ln(DippForm)2F(thf)] complexes arise from oxidative formation and C--F activation of [Ln(DippForm)2(C6F5)] intermediates.     

Syntheses and Crystal Structures of Mononuclear and Binuclear Lanthanide Halide Complexes with Diglyme

Two types of isostructural complexes of lanthanide chlorides with diglyme have been synthesized. These are mononuclear molecular complexes [LnCl₃(diglyme)(THF)] (Ln = Eu ( 1 ), Gd ( 2 ), Dy ( 3 ), Er ( 4 ), Yb ( 5 ); diglyme = diethylen glycol dimethyl ether) and binuclear molecular complexes [LnCl₃(diglyme)]₂ (Ln = Dy ( 3d ), Er ( 4d ), Yb ( 5d )). Complex 1 was obtained by the reaction of [EuCl₃(DME)₂] with diglyme in THF. The complexes 2 – 5 and 3d – 5d resulted from reactions of LnCl₃·6H₂O, (CH₃)₃SiCl and diglyme in THF. The mononuclear complexes 2 – 5 crystallized directly from the solutions where the reactions of lanthanide compounds with diglyme took place. Recrystallizations of the powder products of the same reactions from dichloromethane resulted in the binuclear complexes 3d – 5d . Reactions of lanthanide bromide hydrates, (CH₃)₃SiBr and diglyme in THF achieved mononuclear molecular complexes [LnBr₃(diglyme)(L)] (Ln = Gd, L = H₂O ( 6 ); Ln = Ho, L = THF ( 7 )). Crystals of 6 and 7 were grown by recrystallization from dichloromethane. The lanthanide atoms (Ln = Eu–Yb) are seven‐coordinated in a distorted pentagonal bipyramidal fashion in all reported complexes, 1 – 7 and 3d – 5d . Four oxygen atoms and three halide ions are coordinated to lanthanide atoms in 1 – 7 , [LnX₃(diglyme)(L)]. Four chloride ions, two bridging and two nonbridging, and three oxygen atoms are coordinated to lanthanide atoms in 3d – 5d , [LnCl₃(diglyme)]₂.     

Manipulation of reaction pathways in redox transmetallation-ligand exchange syntheses of lanthanoid(II)/(III) aryloxide complexes

Redox transmetallation/ligand exchange reactions of lanthanoid metals (Ln), Hg(C6F5)2 and HOAr(OMe) (Ar(OMe) = C6H2-2,6-Bu(t)-4-OMe), in thf (tetrahydrofuran) gave, for Ln = Yb, [Yb(OAr(OMe))2(thf)3], and for Ln = Sm, a mixture of [Sm(II)(OAr(OMe))2(thf)3] and mainly [Sm(III)(Ar(OMe))3(thf)] x thf. X-Ray structure determinations show the divalent complexes to have distorted square-pyramidal stereochemistry with transoid thf and OAr(OMe) ligands in the basal plane. Treatment of [Yb(OAr(OMe))2(thf)3] with diethyl ether or PhMe at room temperature gave [Yb(OAr(OMe))2] or [Yb(OAr(OMe))2] x 0.5 PhMe. For lanthanoids Ln = Nd, Er or Y, the reactions with Hg(C6F5)2 and HOAr(OMe) yielded complex product mixtures, from one of which the novel erbium aryloxide fluoride cage [Er3(OAr(OMe))4(mu2-F)3(mu3-F)2(thf)4] x thf x 0.5 C6H14 was isolated. The cage core consists of a triangle of Er atoms joined to two mu3-fluoride ligands and three further mu2-fluorides bridge adjacent Er atoms. One of the Er atoms is six-coordinate with additionally two OAr(OMe) ligands whilst the other two have one OAr(OMe) and two thf ligands and are seven coordinate. Substitution of Hg(C6F5)2 by Hg(CCPh)2 in the redox transmetallation/ligand exchange reactions gave the new derivatives [Ln(OAr(OMe))3(thf)] x thf (Ln = La, Pr, Nd, Sm, Gd, Ho) in good yields whilst Ln = Yb gave [Yb(OAr(OMe))2(thf)3]. Recrystallisation of [Sm(OAr(OMe))3(thf)] x thf from dme (1,2-dimethoxyethane) yielded [Sm(OAr(OMe))3(dme)]. Structural characterisation of [Ln(OAr(OMe))3(thf)] x thf (Ln = Nd, Ho) and [Sm(OAr(OMe))3(dme)] showed monomeric four-coordinate distorted tetrahedral and five-coordinate distorted square-pyramidal complexes respectively. For the smaller lanthanoids Ln = Y, Er or Lu, reactions with Hg(CCPh)2 and HOAr(OMe) gave the mixed aryloxide/alkynide complexes [Ln(OAr(OMe))2(CCPh)(thf)2]. Oxidation of the divalent ytterbium aryloxide [Yb(OAr(OMe))2(thf)3] by Hg(CCPh)2 in thf gave the analogous [Yb(OAr(OMe))2(CCPh)(thf)2]. The erbium alkynide [Er(OAr(OMe))2(CCPh)(thf)2] x 0.25 C6H14 has distorted square-pyramidal stereochemistry with transoid OAr(OMe) and thf ligands in the basal plane and a rare (for Ln) terminal alkynide ligand in the apical position. The reactive Lu-C bond in the [Lu(OAr(OMe))2(CCPh)(thf)2] complexes could be slowly cleaved by free HOAr(OMe) in hydrocarbon solvents, yielding Lu(OAr(OMe))3 species and fortuitous partial hydrolysis of [Er(Ar(OMe))2(CCPh)(thf)2] gave the dimeric [Er(OAr(OMe))2(mu-OH)2]2.     

Synthesis and Spectroscopic [Electronic,IR, NMR (1H, 13C, 89Y)] Characterization of Hexaisopropoxoniobates and ‐Tantalates of Yttrium(III) and Lanthanides(III)

Hexaisopropoxoniobates/tantalates of lathanides of the type [Ln{(μ‐OPrⁱ)₂M(OPrⁱ)₄}₃] (M = Nb, Ln = Y( 1 ), La( 2 ), Nd( 3 ), Er( 4 ), Lu( 5 ); M = Ta, Ln = Y( 6 ), Gd( 7 )) have been prepared by the reactions of LnCl₃.3PrⁱOH with three equivalents of KM(OPrⁱ)₆ in benzene. Reactions in 1:2 molar ratio of LnCl₃.3PrⁱOH with KTa(OPrⁱ)₆ yielded derivatives of the type [{(PrⁱO)₃Ta(μ‐OPrⁱ)₃}Ln{(μ‐OPrⁱ)₂Ta(OPrⁱ)₄}(Cl)] (Ln = Y( 8 ), Gd( 9 )), which on interactions with one equivalent of KOPrⁱ afforded [{(PrⁱO)₃Ta(μ‐OPrⁱ)₃}Ln {(μ‐OPrⁱ)₂Ta(OPrⁱ)₄}(OPrⁱ)] (Ln = Y( 10 ), Gd( 11 )). All these derivatives have been characterized by elemental analyses and molecular weight measurements as well as by their spectroscopic [IR, ¹H and ¹³C NMR (Y, La, Lu), electronic (Nd, Er)] studies. ⁸⁹Y NMR studies have also been carried out on derivatives ( 6 ), ( 8 ), and ( 10 ).     

Homoleptic lanthanide complexes of chelating bis(phosphanyl)amides: synthesis,structure, and ring-opening polymerization of lactones

Treatment of the bis(phosphanyl)amide (Ph2P)2NH with KH in boiling THF followed by crystallization from THF/n-pentane leads to [K(thf)n][N(PPh2)2] (n = 1.25, 1.5). Reaction of [K(thf)n][N(PPh2)2] with anhydrous yttrium or lanthanide trichlorides in a 3:1 molar ratio afforded homoleptic bis(phosphanyl)amide complexes [Ln[N(PPh2)2]3] (Ln = Y, Er) as large crystals in good yields. [Ln[N(PPh2)2]3] can also be obtained by reaction of the homoleptic bis(trimethylsilyl)amides of Group 3 metals and lanthanides [Ln[N(SiMe3)2]3] (Ln = Y, La, Nd) with three equivalents of (Ph2P)2NH in boiling toluene. The single-crystal X-ray structures of these complexes always show eta 2 coordination of the ligand. Dynamic behavior of the ligand is observed in solution and is caused by rapid exchange of the two different phosphorus atoms. [Ln[N(PPh2)2]3] was used as catalyst for the polymerization of epsilon-caprolactone. Significant differences in terms of correlation of theoretical and experimental molecular weights as well as polydispersities were observed depending on the nature of Ln. On the basis of the crystal structure of the heteroleptic complex [Lu[N(PPh2)2]3(thf)], we suggest that in the initiation step of epsilon-caprolactone polymerization the lactone adds to the lanthanide atom to form a sevenfold coordination sphere around the central atom.     

Reactivity of lanthanocene hydroxides toward carbodiimide and CO2: Synthesis and characterization of lanthanide ureido and carbonate complexes

[Cp₂Ln(μ-OH)(THF)]₂ react with 2 equiv of CyNCNCy (Cy = cyclohexyl) to form [Cp₂Ln(μ-OC(NHCy)NCy)]₂ (Ln = Er (1-Er), Y (1-Y)), while treatment of [Cp₂Ln(μ-OH)]₂(μ₃-O)LnCp(THF) with CyNCNCy affords the addition/rearrangement products [Cp₂Ln(μ₃-O)(μ-OC(NHCy)NCy)LnCp]₂ (Ln = Yb (3-Yb), Er (3-Er)). Compounds [(Cp₂Ln)₂(μ₃-CO₃)(THF)]₂ (Ln = Yb (4-Yb), Er (4-Er)) can be obtained by treatment of [Cp₂Ln(μ-OH)(THF)]₂ with CO₂ immediately followed by the reaction with the corresponding Cp₃Ln. Complexes 1-4 were characterized by elemental analysis, spectroscopic properties and X-ray single crystal diffraction analysis.     

Das System KCl/ErCl3 und die Modifikationen der Verbindungen K3LnCl6 (Ln = Ce–Lu,Y)

The System KCl/ErCl₃ and the Modifications of Compounds K₃LnCl₆ (Ln = Ce–Lu, Y) The phase diagram of the system KCl/ErCl₃ was investigated by DTA and XRD. Two compounds exist: KEr₂Cl₇ incongruently and K₃ErCl₆ congruently melting. Their thermodynamic functions for the formation from KCl and ErCl₃ were determined by solution calorimetry and emf vs T measurements in a galvanic cell for solid electrolytes. Both compounds are stable down to 0 K. – K₃ErCl₃ exists in three modifications. The structure of T–K₃ErCl₆ was determined by single crystal measurements: S.G. P2₁/c; Z = 4; a = 1309.8(5), b = 767.1(3), c = 1252.6(4) pm, β = 109.94(2)°. – A survey of all known results on compounds K₃LnCl₆ reveals, that from Ln = Ce to Ln = Ho they only are stable at higher temperatures, > 521 °C (Ce) and > –27 °C (Ho), resp.     

Monomeric f-element chemistry with sterically encumbered allyl ligands

A new class of allyl-lanthanide salts of the type [K(thf)₄][(C₃H₃(SiMe₃)₂)₃LnI] (Ln=Ce, Pr, Nd, Gd, Tb, Dy, Er) have been prepared and isolated by reaction of three equivalents of the 1,3-bis(trimethylsilyl)allyl anion with LnI₃. The neutral complex [C₃H₃(SiMe₃)₂]₃Nd(thf) has been isolated from the reaction of the triflate complex Nd(O₃SCF₃)₃ with three equivalents of the 1,3-bis(trimethylsilyl)allyl anion. These complexes have been structurally characterized using single crystal X-ray diffraction.     

Systematic study of the formation of the lanthanoid cubane cluster motif mediated by steric modification of diketonate ligands

The treatment of ortho ring-functionalised 1-phenylbutane-1,3-dione ligands bearing nitro (Hnpd, Hnmc), methoxy (Hmmc) or fluoro (Hfpp) groups with hydrated lanthanoid salts has provided [Er(4)(μ(3)-OH)(4)(H(2)O)(2)(npd)(8)] (3), [Ln(4)(μ(3)-OH)(4)(nmc)(8)] (Ln = Gd (4), Tb (5), Dy (6) and Er (7)), [Er(4)(μ(3)-OH)(4)(mmc)(8)] (8) and [Er(4)(μ(3)-OH)(4)(H(2)O)(2)(fpp)(8)] (9), respectively. The products were all obtained as cubane clusters in the solid state, as distinct from previous diketonato clusters, with control over motif formation attributed to the steric influence of the ortho-positioned functional groups at the cluster periphery. This work highlights a means of targeting a specific lanthanoid cluster motif by the rational modification of ligands at key locations.     

Synthesis and structures of the C5Me4SiMe3-supported polyhydride complexes over the full size range of the rare earth series

The acid-base reaction of [Ln(CH(2)SiMe(3))(3)(thf)(2)] with Cp'H gave the corresponding half-sandwich rare earth dialkyl complexes [(Cp')Ln(CH(2)SiMe(3))(2)(thf)] (1-Ln: Ln=Sc, Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; Cp'=C(5)Me(4)SiMe(3)) in 62-90% isolated yields. X-ray crystallographic studies revealed that all of these complexes adopt a similar overall structure, in spite of large difference in metal-ion size. In most cases, the hydrogenolysis of the dialkyl complexes in toluene gave the tetranuclear octahydride complexes [{(Cp')Ln(μ-H)(2)}(4)(thf)(x)] (2-Ln: Ln=Sc, x=0; Y, x=1; Er, x=1; Tm, x=1; Gd, x=1; Dy, x=1; Ho, x=1) as the only isolable product. However, in the case of Lu, a trinuclear pentahydride [(Cp')(2)Lu(3)(μ-H)(5)(μ-CH(2)SiMe(2)C(5)Me(4))(thf)(2)] (3), in which the C-H activation of a methyl group of the Me(3)Si unit on a Cp' ligand took place, was obtained as a major product (66% yield), in addition to the tetranuclear octahydride [{(Cp')Lu(μ-H)(2)}(4)(thf)] (2-Lu, 34%). The use of hexane instead of toluene as a solvent for the hydrogenolysis of 1-Lu led to formation of 2-Lu as a major product (85%), while a similar reaction in THF yielded 3 predominantly (90%). The tetranuclear octahydride complexes of early (larger) lanthanide metals [{Cp'Ln(μ-H)(2)}(4)(thf)(2)] (2, Ln=La, Ce, Pr, Nd, Sm) were obtained in 38-57% isolated yields by hydrogenolysis of the bis(aminobenzyl) species [Cp'Ln(CH(2)C(6)H(4)NMe(2)-o)(2)], which were generated in-situ by reaction of [Ln(CH(2)C(6)H(4)NMe(2)-o)(3)] with one equivalent of Cp'H. X-ray crystallographic studies showed that the fine structures of these hydride clusters are dependent on the size of the metal ions.     

Pyridinium‐Chlorometallate von Lanthanoid‐Elementen. Die Kristallstrukturen von [HPy]2[LnCl5(Py)] mit Ln = Eu,Er, Yb und von [H(Py)2][YbCl4(Py)2] · Py

Pyridinium Chlorometallates of Lanthanoid Elements. Crystal Structures of [HPy]₂[LnCl₅(Py)] mit Ln = Eu, Er, Yb und von [H(Py)₂][YbCl₄(Py)₂] · Py The pyridinium chlorometallates [HPy]₂[LnCl₅(Py)] with Ln = Eu, Er and Yb, as well as [H(Py)₂][YbCl₄(Py)₂]·Py have been obtained by the reaction of diacetone alcohol with solutions of the corresponding metal trichlorides in pyridine at 100 °C. According to the crystal structure determinations the anions [LnCl₅(Py)]^2— are linked by bifurcated Cl···H···Cl bridges with the protons of the [HPy]⁺ cations forming chains along [001]. The anions of [H(Py)₂][YbCl₄(Py)₂]·Py form discrete octahedrons with trans‐positions of the pyridine ligands. [HPy]₂[EuCl₅(Py)] ( 1a ): Space group Pnma, Z = 4, lattice dimensions at —80 °C: a = 1874.4(2), b = 1490.2(2), c = 741.5(1) pm, R₁ = 0.0466. [HPy]₂[ErCl₅(Py)] ( 1b ): Space group Pnma, Z = 4, lattice dimensions at —80 °C: a = 1864.3(1), b = 1480.7(2), c = 739.7(1) pm, R₁ = 0.0314. [HPy]₂[YbCl₅(Py)] ( 1c ): Space group Pnma, Z = 4, lattice dimensions at —80 °C: a = 1858.9(2), b = 1479.0(1), c = 736.8(1) pm, R₁ = 0.0306. [H(Py)₂][YbCl₄(Py)₂]·Py ( 2 ·Py): Space group Ia, Z = 4, lattice dimensions at —80 °C: a = 1865.5(1), b = 827.5(1), c = 1873.4(1) pm, ß = 103.97(1)°, R₁ = 0.0258.     

Mono‐, Di‐, Tri‐ and Tetranuclear Rare Earth Complexes Obtained Using a Moderately Bulky Aryloxide Ligand

Redox transmetallation ligand exchange reactions involving a rare earth metal, 2,4,6‐trimethylphenol (HOmes), and a diarylmercurial afford rare earth aryloxo complexes, which are structurally characterized. Both the lanthanoid contraction and the identity of the reaction solvent are found to influence the outcome of the reactions. Using THF in the reaction affords a dinuclear species [Ln₂(Omes)₆(thf)₄]?2THF (Ln=La 1 , Nd 2 ) for the lighter rare earth metals, while a mononuclear species [Ln(Omes)₃(thf)₃] (Ln=Sm 3 , Tb 5 , Er 6 , Yb 7 , Y 8 ) is obtained for the heavier rare earth elements. Surprisingly, there is no change in metal coordination number between the two structural motifs. A divalent trinuclear linear complex [Eu₃(Omes)₆(thf)₆] 4 is obtained for Eu, and features solely bridging aryloxide ligands. Using DME as the reaction solvent affords [La(Omes)₃(dme)₂] 9 from the reaction mixture, and [Ln₂(Omes)₆(dme)₂]?PhMe (La 10 , Nd 11 ) and [Y(Omes)₃(dme)₂] 14 following crystallization of the crude product from toluene. The dinuclear species [Eu₂(Omes)₄(dme)₄] 12 contains two unidentate and two chelating DME ligands, and contrasts the linear structure of 4 . Treatment of HOmes and HgPh₂ with Yb metal in DME affords the mixed valent Yb^II/III complex [Yb₂(Omes)₅(dme)₂] 13 , which is stabilized by an intramolecular π‐Ph–Yb interaction, and is a rare example of a mixed valent rare earth aryloxide. Treatment of Er metal with HOmes at elevated temperature (solvent free) affords the homoleptic [Er₄(Omes)₁₂] 15 , which consists of a tetranuclear array of Er atoms arranged in a ‘herringbone’ fashion; the structure is stabilized by intramolecular π‐Ph–Er interactions. Reaction of La metal with HOmes under similar conditions yields toluene insoluble “La(Omes)₃”, which affords 1 following extraction with THF.     

Direct reaction of iodine-activated lanthanoid metals with 2,6-diisopropylphenol

Rare earth metals activated with ca. 2% iodine react directly with 2,6-diisopropylphenol (HOdip) in tetrahydrofuran (thf), 1,2-dimethoxyethane (dme), and dig-dme (dig = di(2-methoxyethyl) ether) to give solvated phenolate complexes [Ln(Odip)(3)(thf)(n)] (Ln = La, Nd, n = 3; Ln = Sm, Dy, Y, Yb, n = 2), [Eu(Odip)(μ-Odip)(thf)(2)](2), [Ln(Odip)(3)(dme)(2)] (Ln = La, Yb) and [La(Odip)(3)(dig)] in good yield for Ln = La, Nd, Eu but modest yield for smaller Ln metals under comparable conditions. However, increasing the excess of metal greatly increased the yield for Ln = Y. The synthetic method has general potential, at least for lanthanoid phenolates. Comparison redox transmetallation/protolysis (RTP) reactions between Ln metals, Hg(C(6)F(5))(2) and the phenol gave higher yields in shorter time and, for Eu, gave [Eu(Odip)(3)(thf)(3)] in contrast to an Eu(II) complex from Eu(I(2)). New [Ln(Odip)(3)(thf)(3)] complexes have fac-octahedral structures and [Ln(Odip)(3)(thf)(2)] monomeric five coordinate distorted trigonal bipyramidal structures with apical thf ligands. [Eu(Odip)(μ-Odip)(thf)(2)](2) is an unsymmetrical dimer with two bridging Odip ligands. One five coordinate Eu atom has distorted trigonal bipyramidal stereochemistry and the other is distorted square pyramidal. Whilst [La(Odip)(3)(dme)(2)] has irregular seven coordination with mer-Odip and chelating dme ligands, [Ln(Odip)(3)(dme)(2)] (Ln = Dy, Y (prepared by ligand exchange), Yb) are monomeric six coordinate with one chelating and one unidentate dme. A six coordinate fac-octahedral arrangement is observed in [La(Odip)(3)(dig)].     

Re-investigation of ortho-metalated N,N-dialkylbenzylamine complexes of rare-earth metals. First structurally characterized arylates of neodymium and gadolinium Li[LnAr4]

The influence of the ether ligand in [LnCl₃(solv)_n], solv = THF, DME; n = 1–3 in reactions with ortho-lithiated dimethyl-benzylamine Li(dmba) has been studied. An improved protocol towards homoleptic tris-aryl complexes of the type [Ln(dmba)₃], Ln = Y, Er and Yb has been developed and molecular structures of these complexes have been established by X-ray crystallography. For the first time stable homoleptic lithium ate-complexes of the type Li[Ln(dmba)₄] (Ln = Gd, Nd) have been isolated and structurally characterized. The success in their synthesis strongly depends on the choice of the appropriate [LnCl₃(solv)_n] precursor, such as [GdCl₃(dme)₂], [NdCl₃(dme)], and THF-free reaction conditions. Factors influencing on possible degradation pathways of lanthanide tris-aryl complexes with dmba-type ligands are discussed.     

Reactions of lanthanoid metals with 3,5-diphenylpyrazole at elevated temperatures: synthesis and structures of both homoleptic, [Ln3(Ph2pz)9] (Ln = La, Nd), [Ln2(Ph2pz)6] (Ln = Er, Lu), and heteroleptic, [Ln(Ph2pz)3(Ph2pzH)2] (Ln = La, Nd, Gd, Tb, Er or Yb), pyrazolate complexes

The direct reaction of lanthanoid metals with 3,5-diphenylpyrazole (Ph2pzH) at 300 degrees C under vacuum in the presence of mercury gives the structurally characterized [Ln3(Ph2pz)9] (Ln = La or Nd), [Ln2(Ph2pz)6] (Ln = Er or Lu). Similar reactions provided heteroleptic [Ln(Ph2pz)3(Ph2pzH)2] (Ln = La, Nd, Gd, Tb, Er and Y). The last was obtained only from impure Ph2pzH, but was subsequently prepared by treatment of [Yb(Ph2pz)3(thf)2] with Ph2pzH. Reactions of Yb with Ph2pzH at 200 degrees C gave a poorly soluble divalent species which was converted by 1,2-dimethoxyethane into [Yb(Ph2pz)2(dme)2]. Single crystal X-ray structures established a bowed trinuclear pyrazolate-bridged structure for [Ln3(Ph2pz)9] (Ln = La or Nd), Ln...Ln...Ln being 135.94(1) degrees (La) and 137.41(1) degrees(Nd). There are two eta2-Ph2pz ligands on the terminal Ln atoms and one on the central metal with adjacent Ln atoms linked by one mu-eta2:eta2 and one mu-eta5 (to terminal Ln):eta2 pyrazolate group. Thus the terminal Ln atoms are formally nine-coordinate and the central Ln, ten-coordinate. By contrast, [Ln2(Ph2pz)6] (Ln = Er or Lu) complexes are dimeric with two terminal (eta2) and two bridging (mu-eta2:eta2) pyrazolates and eight-coordinate lanthanoids. All six heteroleptic complexes [Ln(Ph2pz)3(Ph2pzH)2] (Ln = La, Nd, Gd, Tb, Er or Yb) are isomorphous with three equatorial eta2-Ph2pz groups, transoid(N-Ln-N 158.18(6)-161.43(9) degrees) eta1-pyrazole ligands, and eight-coordinate Ln throughout.     

Structural features of thiocarbamide derivatives of some lanthanide iodides

Data on the synthesis, IR spectroscopy, and single crystal XRD are presented for thiocarbamide compounds of the composition [Ln(H₂O)₉]I₃·2CS(NH₂)₂, where Ln = Dy (I) and Yb (II). The structural features of [Ln(H₂O)₉]I₃·2CS(NH₂)₂ (Ln = Pr, Nd, Eu, Gd, Dy, Ho, Er, and Yb) are discussed. The compounds of thiocarbamide with Pr, Nd, Eu, Gd, and Dy iodides are found to form the first isostructural series characterized by a continuous network structure, while with Ho, Er, and Yb iodides the second isostructural series with a layered type structure is formed.     

Guanidinate derivatives of rare-earth metals. The synthesis, properties, and molecular structures of the complexes {(Me3Si)2NC(NPri)2}3Nd, {(Me3Si)2NC(NCy)2}3Lu, and {(Me3Si)2NC(NPri)2}2HC(NPri)2}Nd

The reactions of anhydrous LnCl₃ (Ln = Nd or Lu) with three equivalents of {(Me₃Si)₂NC(NR)₂}Li (R = Prⁱ or Cy; Cy is cyclohexyl) in THF afforded the corresponding tris(guanidinate) derivatives of lanthanides {(Me₃Si)₂NC(NR)₂}₃Ln (Ln = Nd, R = Prⁱ, (1); Ln = Lu, R = Cy (2)), which were isolated after the recrystallization from hexane in 82 and 88% yields, respectively. The complex {(Me₃Si)₂NC(NCy)₂}₂{HC(NCy)₂}Nd (3) containing two guanidinate ligands and one formamidinate ligand was isolated in attempting to synthesize the bis(guanidinate) borohydride derivative by the reaction of {(Me₃Si)₂NC(N-Cy)₂}Na with Nd(BH₄)₃(THF)₂ (in a molar ratio of 2: 1) in THF. This complex is apparently formed as a result of the fragmentation and redistribution of the guanidinate ligands. The X-ray diffraction study showed that in the crystalline state compounds 1–3 are mononuclear complexes containing no coordinated Lewis bases.     

Synthesis,Structures and Reactivity of Lanthanoid(II) Formamidinates of Varying Steric Bulk

New reactive, divalent lanthanoid formamidinates [Yb(Form)₂(thf)₂] (Form=[RNCHNR]; R=o‐MeC₆H₄ (o‐TolForm; 1 ), 2,6‐Me₂C₆H₃ (XylForm; 2 ), 2,4,6‐Me₃C₆H₂ (MesForm; 3 ), 2,6‐Et₂C₆H₃ (EtForm; 4 ), o‐PhC₆H₄ (o‐PhPhForm; 5 ), 2,6‐iPr₂C₆H₃ (DippForm; 6 ), o‐HC₆F₄ (TFForm; 7 )) and [Eu(DippForm)₂(thf)₂] ( 8 ) have been prepared by redox transmetallation/protolysis reactions between an excess of a lanthanoid metal, Hg(C₆F₅)₂ and the corresponding formamidine (HForm). X‐ray crystal structures of 2 – 6 and 8 show them to be monomeric with six‐coordinate lanthanoid atoms, chelating N,N′‐Form ligands and cis‐thf donors. However, [Yb(TFForm)₂(thf)₂] ( 7 ) crystallizes from THF as [Yb(TFForm)₂(thf)₃] ( 7 a ), in which ytterbium is seven coordinate and the thf ligands are “pseudo‐meridional”. Representative complexes undergo C? X (X=F, Cl, Br) activation reactions with perfluorodecalin, hexachloroethane or 1,2‐dichloroethane, and 1‐bromo‐2,3,4,5‐tetrafluorobenzene, giving [Yb(EtForm)₂F]₂ ( 9) , [Yb(o‐PhPhForm)₂F]₂ ( 10) , [Yb(o‐PhPhForm)₂Cl(thf)₂] ( 11) , [Yb(DippForm)₂Cl(thf)] ( 12) and [Yb(DippForm)₂Br(thf)] ( 16) . X‐ray crystallography has shown 9 to be a six‐coordinate, fluoride‐bridged dimer, 12 and 16 to be six‐coordinate monomers with the halide and thf ligands cis to each other, and 11 to have a seven‐coordinate Yb atom with “pseudo‐meridional” unidentate ligands and thf donors cis to each other. The analogous terbium compound [Tb(DippForm)₂Cl(thf)₂] ( 13 ), prepared by metathesis, has a similar structure to 11 . C? Br activation also accompanies the redox transmetallation/protolysis reactions between La, Nd or Yb metals, Hg(2‐BrC₆F₄)₂, and HDippForm, yielding [Ln(DippForm)₂Br(thf)] complexes (Ln=La ( 14 ), Nd ( 15 ), Yb ( 16 )).