Organolanthanides with 3-(2-pyridylmethyl) indenyl ligands: synthesis, crystal structures and catalytic activities of divalent complexes for ε-caprolactone polymerization

Reaction of 3-(2-pyridylmethyl)indenyl lithium (1) with LnI₂(THF)₂ (Ln = Sm, Yb) in THF produced the divalent organolanthanides (C₅H₄NCH₂C₉H₆)₂Ln^II(THF) (Ln = Sm (2), Yb (3)) in high yield. 1 reacts with LnCl₃ (Ln = Nd, Sm, Yb) in THF to give bis(3-(2-pyridylmethyl)indenyl) lanthanide chlorides (C₅H₄NCH₂C₉H₆)₂Ln^IIICl (Ln = Nd (4), Sm (5)) and the unexpected divalent lanthanides 3 (Ln = Yb). Complexes 2-5 show more stable in air than the non-functionalized analogues. X-ray structural analyses of 2-4 were performed. 2 and 3 belong to the high symmetrical space group (Cmcm) with the same structures, they are THF-solvated 9-coordinate monomeric in the solid state, while 4 is an unsolvated 9-coordinate monomer with a trans arrangement of both the sidearms and indenyl rings in the solid state. Additionally, 2 and 3 show moderate polymerization activities for ε-caprolactone (CL).     

Synthesis and molecular structures of lanthanocene amide complexes and their catalytic activity for addition of amines to nitriles

Reaction of (CH₃C₅H₄)₂LnCl(THF) with NaNHAr in a 1:1 molar ratio in THF afforded the amide complexes (CH₃C₅H₄)₂LnNHAr(THF) [(Ar = 2,6-Me₂C₆H_3, Ln = Yb (I), Y (III); Ar = 2,6-ⁱPr₂C₆H₃, Ln = Yb (II)]. X-ray crystal structure determination revealed that complexes I-III are isostructural. The central metal in each complex coordinated to two methylcyclopentadienyl groups, one amide group and one oxygen atom from THF to form a distorted tetrahedron. Complexes I-III and a known complex (CH₃C₅H₄)₂YbNⁱPr₂(THF) IV all can serve as the catalysts for addition of amines to nitriles to monosubstituted N-arylamidines. The activity depended on the central metals and amide groups, and the active sequence follows the trend IV ≈ III < I < II.     

Insertion reaction of elemental sulfur into the Ln–C bond: Synthesis and characterization of [(C5H4SiMe2Bu)2Ln(μ-SR)]2 (R = Me,Ln = Yb,Er, Dy,Y; R = Bu,Ln = Yb,Dy)

Treatment of (C₅H₄SiMe₂^tBu)₂LnR with 1 equiv of elemental sulfur in toluene at ambient temperature gives dimeric complexes [(C₅H₄SiMe₂^tBu)₂Ln(μ-SR)]₂ [R = Me, Ln = Yb (1), Er (2), Dy (3), Y (4); R = ⁿBu, Ln = Yb (5), Dy (6)]. All these complexes have been characterized by elemental analysis, IR and mass spectroscopies. The structures of complexes 1, 3, 5 and 6 are also determined through X-ray single crystal diffraction analysis, indicating that only one sulfur atom from elemental sulfur inserts into Ln–C σ-bond.     

Synthesis,reactivity and structural characterization of lanthanide hydroxides stabilized by a carbon-bridged bis(phenolate) ligand

The synthesis of lanthanide hydroxo complexes stabilized by a carbon-bridged bis(phenolate) ligand 2,2’-methylene-bis(6-tert-butyl-4-methylphenoxo) (MBMP²⁻) was described, and their reactivity toward phenyl isocyanate was explored. Reactions of (MBMP)Ln(C₅H₅)(THF)₂ with a molar equiv. of water in THF at −78 °C afforded the bis(phenolate) lanthanide hydroxides as dimers [{(MBMP)Ln(μ-OH)(THF)₂}₂] [Ln = Nd (1), Yb (2)] in high yields. Complexes 1 and 2 reacted with phenyl isocyanate in THF, after workup, to give the desired O−H addition products, [(MBMP)Ln(μ-η¹:η²-O₂CNHPh)(THF)₂]₂ [Ln = Nd (3), Yb (4)] in excellent isolated yields. These complexes were well characterized, and the molecular structures of complexes 2 to 4 were determined by X-ray crystallography. The ytterbium atom in complex 2 is coordinated to six oxygen atoms to form a distorted octahedral geometry, whereas each metal center in complexes 3 and 4 is seven-coordinated, and the coordination geometry can be best described as a distorted pentagonal bipyramid.     

Homolysis of the Ln-N bond: Synthesis, characterization and catalytic activity of organolanthanide(II) complexes with 2-pyridylmethyl and 3-pyridylmethyl-functionalized indenyl ligands

Two series of new organolanthanide(II) complexes with general formula {η⁵:η¹-[1-R-3-(2-C₅H₄NCH₂)C₉H₅]}₂Ln(II) (R = H-, Ln = Yb (3), Eu (4); R = Me₃Si-, Ln = Yb (5), Eu (6)), and {η⁵:η¹-[1-R-3-(3-C₅H₄NCH₂)C₉H₅]}₂Ln(II) (R = H-, Ln = Yb (9), Eu (10); R = Me₃Si-, Ln = Yb (11), Eu (12)) were synthesized by silylamine elimination with one-electron reductive reactions of lanthanide(III) amides [(Me₃Si)₂N]₃Ln(μ-Cl)Li(THF)₃ (Ln = Yb, Eu) with 2 equiv. 1-R-3-(2-C₅H₄NCH₂)C₉H₆ (R = H (1), Me₃Si- (2)) or 1-R-3-(3-C₅H₄NCH₂)C₉H₆ (R = H (7), Me₃Si- (8)) in good yields. All the complexes were fully characterized by elemental analyses and spectroscopic methods. Complexes 3 and 5 were additionally characterized by single-crystal X-ray diffraction study. The catalytic activities of the complexes for MMA polymerization were examined. It was found that complexes with 3-pyridylmethyl substituent on the indenyl ligands could function as single-component MMA polymerization catalysts with good activities, while the complexes with 2-pyridylmethyl substituent on the indenyl ligands cannot catalyze MMA polymerization. The temperatures and solvents effect on the MMA polymerization have also been examined.     

Rare earth metal bis(alkyl) complexes bearing amino phosphine ligands: Synthesis and catalytic activity toward ethylene polymerization

Reactions of neutral amino phosphine compounds HL^1-3 with rare earth metal tris(alkyl)s, Ln(CH₂SiMe₃)₃(THF)₂, afforded a new family of organolanthanide complexes, the molecular structures of which are strongly dependent on the ligand framework. Alkane elimination reactions between 2-(CH₃NH)-C₆H₄P(Ph)₂ (HL¹) and Lu(CH₂SiMe₃)₃(THF)₂ at room temperature for 3 h generated mono(alkyl) complex (L¹)₂Lu(CH₂SiMe₃)(THF) (1). Similarly, treatment of 2-(C₆H₅CH₂NH)-C₆H₄P(Ph)₂ (HL²) with Lu(CH₂SiMe₃)₃(THF)₂ afforded (L²)₂Lu(CH₂SiMe₃)(THF) (2), selectively, which gradually deproportionated to a homoleptic complex (L²)₃Lu (3) at room temperature within a week. Strikingly, under the same condition, 2-(2,6-Me₂C₆H₃NH)-C₆H₄P(Ph)₂ (HL³) swiftly reacted with Ln(CH₂SiMe₃)₃(THF)₂ at room temperature for 3 h to yield the corresponding lanthanide bis(alkyl) complexes L³Ln(CH₂SiMe₃)₂(THF)_n (4a: Ln = Y, n = 2; 4b: Ln = Sc, n = 1; 4c: Ln = Lu, n = 1; 4d: Ln = Yb, n = 1; 4e: Ln = Tm, n = 1) in high yields. All complexes have been well defined and the molecular structures of complexes 1, 2, 3 and 4b-e were confirmed by X-ray diffraction analysis. The scandium bis(alkyl) complex activated by AlEt₃ and [Ph₃C][B(C₆F₅)₄], was able to catalyze the polymerization of ethylene to afford linear polyethylene.     

Synthesis, characterization, and catalytic activity of divalent organolanthanide complexes with new tetrahydro-2H-pyranyl-functionlized indenyl ligands

Two series of new divalent organolanthanide complexes with the general formula [η⁵:η¹-{1-R-3-(C₅H₉OCH₂)C₉H₅}]₂Ln^II (R = H, Ln = Yb (3); R = Me₃Si, Ln = Yb (4); R = H, Ln = Eu (5); R = Me₃Si, Ln = Eu (6)) were prepared by reactions of 2 equiv. of 1-R-3-(C₅H₉OCH₂)C₉H₆ (R = H (1), R = Me₃Si (2)) with the lanthanide(III) amides [(Me₃Si)₂N]₃Ln(μ-Cl)Li(THF)₃ (Ln = Yb, Eu) via a one-electron reductive elimination process. Recrystallization of 6 from n-hexane afforded [η⁵:η¹-(C₅H₉OCH₂C₉H₅SiMe₃)]₂Eu^II · (C₆H₁₄)_0.5 (7). All compounds were fully characterized by elemental analyses, and spectroscopic methods. The structures of complexes 4 and 7 were additionally determined by single-crystal X-ray analyses. The catalytic activity of the complexes on methyl methacrylate and ε-caprolactone polymerization was studied, and the temperatures, substituents on the indenyl ring, and solvents effects on the catalytic activity of the complexes were examined.     

Rare earth metal alkyl complexes bearing N,O,P multidentate ligands: Synthesis, characterization and catalysis on the ring-opening polymerization of l-lactide

Alkane elimination reactions of rare earth metal tris(alkyl)s, Ln(CH₂SiMe₃)₃(THF)₂ (Ln = Y, Lu) with the multidentate ligands HL^1-4, afforded a series of new rare earth metal complexes. Yttrium complex 1 supported by flexible amino-imino phenoxide ligand HL¹ was isolated as homoleptic product. In the reaction of rigid phosphino-imino phenoxide ligand HL² with equimolar Ln(CH₂SiMe₃)₃(THF)₂, HL² was deprotonated by the metal alkyl and its imino CN group was reduced to C-N by intramolecular alkylation, generating THF-solvated mono-alkyl complexes (2a: Ln = Y; 2b: Ln = Lu). The di-ligand chelated yttrium complex 3 without alkyl moiety was isolated when the molar ratio of HL² to Y(CH₂SiMe₃)₃(THF)₂ increased to 2:1. Reaction of steric phosphino β-ketoiminato ligand HL³ with equimolar Ln(CH₂SiMe₃)₃(THF)₂ afforded di-ligated mono-alkyl complexes (4a: Ln = Y; 4b: Ln = Lu) without occurrence of intramolecular alkylation or formation of homoleptic product. Treatment of tetradentate methoxy-amino phenol HL⁴ with Y(CH₂SiMe₃)₃(THF)₂ afforded a monomeric yttrium bis-alkyl complex of THF-free. The resultant complexes were characterized by IR, NMR spectrum and X-ray diffraction analyses. All alkyl complexes exhibited high activity toward the ring-opening polymerization of l-lactide to give isotactic polylactide with controllable molecular weight and narrow to moderate polydispersity.     

Homolysis of the Ln-N bond: Synthesis, characterization and catalytic activity of organolanthanide(II) complexes with furfuryl- and tetrahydrofurfuryl-functionalized indenyl ligands

A series of new organolanthanide(II) complexes with furfuryl- and tetrahydrofurfuryl-functionalized indenyl ligands were synthesized via one-electron reductive elimination reaction. Treatments of [(Me₃Si)₂N]₃Ln^III(μ-Cl)Li(THF)₃ (Ln = Yb, Eu) with 2 equiv. of C₄H₇OCH₂C₉H₇ (1) or C₄H₃OCH₂C₉H₇ (2), respectively in toluene at moderate high temperatures produced, after workup, the corresponding organolanthanide(II) complexes with formula [η⁵:η¹-(C₄H₇OCH₂C₉H₆)]₂Ln^II (Ln = Yb (5), Ln = Eu (6)) and [η⁵:η¹-(C₄H₃OCH₂C₉H₆)]₂Ln^II (Ln = Yb (7), Ln = Eu (8)) in reasonable to good yields. Treatments of [(Me₃Si)₂N]₃Ln^III(μ-Cl)Li(THF)₃ (Ln = Yb, Eu) with 2 equiv. of C₄H₇OCH₂C₉H₆SiMe₃ (3) or C₄H₃OCH₂C₉H₆SiMe₃ (4), respectively, in toluene at moderate high temperatures afforded, after workup, the corresponding organolanthanide(II) complexes with formula [η⁵:η¹-(C₄H₇OCH₂C₉H₅SiMe₃)]₂Ln^II (Ln = Yb (9), Ln = Eu (10)) and[η⁵:η¹-(C₄H₃OCH₂C₉H₅SiMe₃)]₂Ln^II (Ln = Yb (11), Ln = Eu (12)) in good to high yields. All the compounds were fully characterized by spectroscopic methods and elemental analyses. The structure of complex 9 was additionally determined by single-crystal X-ray analyses. Studies on the catalytic activities of complexes showed that the complexes having silyl group functionalized indenyl ligands have high catalytic activities on ε-caprolactone polymerization. The temperatures, substituted groups on the indenyl ligands of the complexes, and solvents effects on the catalytic activities of the complexes were examined.     

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.     

Complexes of tantalum with triaryloxides: Ligand and solvent effects on formation of hydride derivatives

A family of tantalum compounds supported by the triaryloxide [R-L]³⁻ ligands are reported [H₃(R-L) = 2,6-bis(4-methyl-6-R-salicyl)-4-tert-butylphenol, where R = Me or ^tBu]. The reaction of H₃[Me-L] with TaCl₅ in toluene gave [(Me-L)TaCl₂]₂ (1). The [^tBu-L] analogue [(^tBu-L)TaCl₂]₂ (2) was synthesized via treatment of TaCl₅ with Li₃[^tBu-L]. A THF solution of LiBHEt₃ was added to 1 in toluene to provide [(Me-L)TaCl(THF)]₂ (3), while treatment of 2 with 2 equiv of LiBHEt₃ or potassium in toluene followed by recrystallization from DME resulted in formation of [M(DME)₃][{(^tBu-L)TaCl}₂(μ-Cl)] [M = Li (4a), K (4b)]. When the amount of MBHEt₃ (M = Li, Na, K) was increased to 5 equiv, the analogous reactions in toluene afforded [{(bit-^tBu-L)Ta}₂(μ-H)₃M] [M = Li(THF)₂ (5a), Na(DME)₂ (5b), K(DME)₂ (5c)]. During the course of the reaction, the methylene CH activation of the ligand took place. Dissolution of 5a in DME produced [{(bit-^tBu-L)Ta}₂(μ-H)₃Li(DME)₂] (6), indicating that the coordinated THF molecules are labile. When the 2/LiBHEt₃ reaction was carried out in THF, the ring opening of THF occurred to yield [(^tBu-L)Ta(OBuⁿ)₂]₂ (7) along with a trace amount of [Li(THF)₄][{(^tBu-L)TaCl}₂(μ-OBuⁿ)] (8). Treatment of 2 with potassium hydride in DME yielded [{(^tBu-L)TaCl₂K(DME)₂}₂(μ-OCH₂CH₂O)] (9), in which the ethane-1,2-diolate ligand arose from partial C-O bond rupture of DME. The X-ray crystal structures of 2, 3, 4, 5a, 6, 7, and 9 are described.     

Redistribution reactions of heteroleptic barium iodide derivatives: Synthesis and structures of trans-BaI2(DME)(triglyme), cis-BaI2(DME)(tetraglyme) and [Ba(tetraglyme)2]I2 · C7H8

The reaction between BaI₂ · 2H₂O and NaHFIP [HFIP = OCH(CF₃)₂] in a 1:1 stoichiometry gave the heterometallic compound NaBaI₂(HFIP)(H₂O)(THF)_0.5 (1). Attempts to recrystallize 1 in the presence of N- or O-donor ligands lead to redistribution reactions. Barium iodide adducts such as BaI₂(DME)₃ (2), trans-BaI₂(DME)(triglyme) (3) and cis-BaI₂(DME)(tetraglyme) (4) were isolated with DME as solvent. A similar behavior was observed for the reaction between BaI₂ · 2H₂O and NaTFA (TFA = O₂CCF₃) in a 1:1 stoichiometry in THF, and [Ba(tetraglyme)₂]I₂ · C₇H₈ (6) was isolated in the presence of excess tetraglyme. All compounds have been characterized by elemental analysis, IR and ¹H NMR as well as single crystal X-ray studies for 3, 4 and 6. Compounds 3 and 4 are covalent adducts with eight- and nine-coordinate barium, respectively. Compound 6 is an ionic compound where two tetraglyme ligands wrap the 10-coordinate barium cation in a helical fashion. The presence of DME actually allows the coordination number of barium in the mixed-ligand adducts 3 and 4 to be tuned. The average Ba–O bond lengths (2.80 for 3 to 2.87 Å for 6) reflect the coordination number of the metal. The same observation is valid for the average Ba–I bond distance, 3.442 for 3 vs. 3.536 Å for 4.     

Synthesis, characterization and catalytic activity of organolanthanide(II) complexes with heterocyclic-functionalized fluorenyl ligands

Two series of new organolanthanide(II) complexes with tetrahydro-2H-pyranyl- or N-piperidineethyl-functionalized fluorenyl ligands were synthesized via one-electron reductive elimination reaction. Treatments of [(Me₃Si)₂N]₃Ln^III(μ-Cl)Li(THF)₃ with 2 equiv. of C₅H₉OCH₂C₁₃H₉ (1) or C₅H₁₀NCH₂CH₂C₁₃H₉ (2), respectively, in toluene at about 80 °C produced, after workup, the corresponding organolanthanide(II) complexes with formula [η⁵:η¹-C₅H₉OCH₂C₁₃H₈]₂Ln^II (Ln = Yb (3), Ln = Eu (4)) and [η⁵:η¹-C₅H₁₀NCH₂CH₂C₁₃H₈]₂Ln^II (Ln = Yb (5), Ln = Eu (6)) in good yields. All the compounds were fully characterized by spectroscopic methods and elemental analyses. The structures of complexes 3, 4, and 6 were additionally determined by single-crystal X-ray analyses. It represents the first example of solvent-free organolanthanide(II) complexes with fluorenyl ligands. The catalytic properties of the organolanthanide(II) complexes on the polymerization of ε-caprolactone and methyl methacrylate have been studied. The temperatures, solvents and coordination effects on the catalytic activities of the complexes were examined.     

3D Heterometallic (3d–4f) coordination polymers: A ferromagnetic interaction in a Gd(III)–Cu(II) couple

Four 3d–4f heterometallic coordination polymers, [Cu₃(IDA)₆Ln₂] · n(H₂O) [IDA =  iminodiacetate dianion; Ln = Gd, n = 3 (1); Ln = Nd, n = 6 (2); Ln = Sm, n = 6 (3)] and [Cu(Cl)(NTA)Sm(H₂O)₆] · (ClO₄) · (H₂O) (4) [NTA = nitrilotriacetate trianion], have heen synthesized and characterized by single crystal X-ray diffraction analysis. Complexes 1–3 are isomorphous, showing a 3D coordination framework having tubular channels filled by lattice water molecules running parallel to the c axis. Whereas complex 4 is a 1D polymer of alternating copper and samarium ions connected by NTA, and the chains get involved in H-bonding interactions resulting in a 3D network. A low temperature magnetic study reveals ferromagnetic interactions for complex 1. Thermogravimetric and X-ray powder diffraction analyses of 1, 2 and 3 show that the covalently bonded 3D network remains almost unaffected after deaquation.     

Synthesis and molecular structure of new heterometal alkoxide clusters Ln2Na8(OCH2CF3)14(THF)6 (Ln = Sm, Y, Yb): Highly active catalysts for polymerization of ε-caprolactone and trimethylene carbonate

The new polynuclear heterometal alkoxide clusters Ln₂Na₈(OCH₂CF₃)₁₄(THF)₆ (Ln = Sm 1, Y 2, Yb 3) have been synthesized by the reaction of anhydrous LnCl₃ with 7 equiv. of NaOCH₂CF₃ in 68–75% yields. Crystal structural analysis revealed clusters 1–3 are isomorphous composed of two cubanes and a double open cubane, with one face of an Ln₁Na₂O₄ open cubane capped by an additional Ln₁O₂ layer. Clusters 1–3 show extremely high activity for the polymerization of ε-caprolactone (ε-CL) and trimethylene carbonate (TMC). The reactivity is much higher than those found for the monometallic alkoxides lanthanide complexes previously reported. The dependence of catalytic activity on lanthanide metals is observed: Yb ≈ Y < Sm for ε-CL and Yb < Y < Sm for TMC. The polymers obtained with these clusters all show a unimodal molecular weight distribution with moderate molecular weight distributions (M_w/M_n = 1.4–1.7), indicating that clusters 1–3 can really be used as single-component catalysts. The bimetallic cooperation and the coordination–insertion mechanism were proposed.     

Synthesis, characterization of homoleptic guanidino lanthanide complexes and their catalytic activity for the ring-opening polymerization of ε-caprolactone

A series of homoleptic lanthanide guanidinate (guan)₃Ln · ((C₂H₅)₂O)_n (Ln=Yb, n=1 guan=(CyN)₂CNiPr₂, (1); Ln=Nd, n=0, guan=(CyN)₂CNiPr₂, (2); (iPrN)₂CNiPr₂, (3); (iPrN)₂CN(CH₂)₅, (4)); (iPr=isopropyl, Cy=Cyclohexyl) were synthesized by the reaction of THF solution of lithium guanidinate with anhydrous lanthanide trichlorides in THF in 3:1 molar ratio. The molecular structures of 2 and 3 were determined to be monomeric in solid state with a six coordinate lanthanide metal ligated by six nitrogens of three guanidinate groups. All the complexes exhibited extremely high activity for the ring-opening polymerization of ε-caprolactone and the polymerization gave the polymers with high molecular weights. The different substituents at guanidino ligands have great effect on the catalytic activity. The mechanism of the polymerization was presented.     

Synthesis, structural characterization, and reactivity of organolanthanides derived from a new chiral ligand (S)-2-(pyrrol-2-ylmethyleneamino)-2′-hydroxy-1,1′-binaphthyl

Condensation of (S)-2-amino-2′-hydroxy-1,1′-binaphthyl with 1 equiv. of pyrrole-2-carboxaldehyde in toluene in the presence of molecular sieves at 70 °C gives (S)-2-(pyrrol-2-ylmethyleneamino)-2′-hydroxy-1,1′-binaphthyl (1H₂) in 90% yield. Deprotonation of 1H₂ with NaH in THF, followed by reaction with LnCl₃ in THF gives, after recrystallization from a toluene or benzene solution, dinuclear complexes (1)₃Y₂(thf)₂ · 3C₇H₈ (3 · 3C₇H₈) and (1)₃Yb₂(thf)₂ · 3C₆H₆ (4 · 3C₆H₆), respectively, in good yields. Treatment of 1H₂ with Ln[N(SiMe₃)₂]₃ in toluene under reflux, followed by recrystallization from a benzene solution gives the dimeric amido complexes {1-LnN(SiMe₃)₂}₂ · 2C₆H₆ (Ln = Y (5 · 2C₆H₆), Yb (6 · 2C₆H₆)) in good yields. All compounds have been characterized by various spectroscopic techniques, elemental analyses and X-ray diffraction analyses. Complexes 5 and 6 are active catalysts for the polymerization of methyl methacrylate (MMA) in toluene, affording syn-rich poly-(MMA)s.     

Syntheses and molecular structures of mono(guanidinate) lanthanide borohydrides and their catalytic activity for MMA-polymerization

The mono(guanidinate) lanthanide borohydride complexes of [(Me₃Si)₂NC(NCy)₂]Ln(BH₄)₂(THF)₂ (Ln = Yb (1), Er (2)) have been synthesized by the reactions of corresponding Ln(BH₄)₃(THF)₃ with sodium guanidinate of [(Me₃Si)₂NC(NCy)₂]Na in a 1:1 molar ratio in THF. They were characterized by elemental analysis, infrared spectrum and X-ray diffraction analysis. 1 and 2 have similar structures. The lanthanide ion was bonded by an η²-guanidinate ligand, two η³-BH₄ ligands and two THF molecules as a distorted octahedron. The two BH₄ ligands in a complex are equivalent and cis to each other. The structure of solvated sodium guanidinate of {[(Me₃Si)₂NC(NCy)₂]Na(THF)}₂ (3) was also presented. In a dimeric molecule of 3, each Na atom is bound to three nitrogen atoms from two guanidinate groups and one oxygen atom from the THF molecule. 1 and 2 displayed moderate high catalytic activity for the polymerization of methyl methacrylate. The Er complex is more active than the Yb complex.     

Persistent π-arene interactions in bulky formamidinate complexes of potassium

The reaction of potassium hexamethyldisilazide (K-HMDS) with 1 equiv. of the bulky formamidine N(Diep)C(H)NH(Diep) (DiepFormH, Diep = 2,6-Et₂C₆H₃) in THF yields the half deprotonated compound [K(DiepForm)(DiepFormH)] (1), which exhibits suppressed reactivity with the hexamethyldisilazide anion. Reaction of 1 with n-BuLi gives the polymer [{Li(THF)₂K(DiepForm)₂}_n] (2). Preparation of 1 in the presence of the chelating solvents 1,2-dimethoxyethane (DME) or N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA) gives the fully deprotonated species [{K₃(DiepForm)₃(DME)₃}_n] (3) and [{K(PMDETA)K(DiepForm)₂}_n] (6). The syntheses of compounds 1-3, 6 and related compounds, e.g. [{K₃{N(Dimp)C(H)N(Dimp)}₃(DME)₃}_n] (4) (Dimp = 2,6-Me₂C₆H₃), are described.     

Synthesis,structures and luminescent properties of 4d–4f heterometallic coordination frameworks based on lanthanide oxalate substructures with nicotinate bridging ligands

Four transition–lanthanide metal–organic coordination polymers, namely [Ag₂Ln(nic)₄(H₂O)₄ · (ClO₄) · H₂O] [Ln = Eu (1), Gd (2)] and [AgLn(nic)₂(ox)_0.5(H₂O)₂ · (ClO₄) · H₂O] [Ln = Tb (3), Yb (4)] (nic = nicotinate; ox = oxalate) have been synthesized by the hydrothermal reactions of 4d and 4f metal salts with N-/O-donor ligands. The isostructural complexes 1 and 2 exhibit novel 2D wave-like heterometallic layers constructed by the assembly of 1D chains of lanthanide–carboxylate with Ag(nic)₂ subunits. Complexes 3 and 4 show another unusual 3D heterometallic coordination framework constructed from 2D lanthanide–oxalate layers and pillar-like Ag(nic)₂ subunits. Furthermore, the luminescent properties of complexes 1 and 3 were studied.