Synthesis and properties of guanidinate derivatives of rare-earth metals. Molecular structures of the { (Me3Si)2NC(NPri)2}2Y(µ-Cl)2Li(THF)2, [{ (Me3Si)2NC(NPri)2}2SmCl]2 and {(Me3Si)2NC(NPri)2} Sm(µ3-BH4)2(DME) complexes

The reaction of anhydrous SmCl₃ with two equivalents of lithium N,N′-diisopropyl-N″-bis(trimethylsilyl)guanidinate in THF afforded the [{(Me₃Si)₂NC(NPrⁱ)₂}₂SmCl]₂ complex (1) in 82% yield. Analogous reactions with YCl₃ and GdCl₃ produced the ate-complexes { (Me₃Si)₂NC(NPrⁱ)₂}₂Ln(µ-Cl)₂Li(THF)₂ (Ln = Y (2) and Gd (3)). The structures of complexes 1 and 2 were established by X-ray diffraction. The reaction of complex 1 with NaBH₄ in hexane (20 °C) followed by treatment with dimethoxyethane yielded the unexpected product, { (Me₃Si)₂NC(NPrⁱ)₂}Sm(µ³-BH₄)₂(DME) (5). X-ray diffraction study showed that both borohydride ligands in complex 5 are tridentate.     

Synthesis and properties of bis(indenyl) derivatives of ytterbium and lutetium. Molecular structures of the complexes (C9H7)2Ln(μ-Cl)2Li(Et2O)2 (Ln = Yb, Lu) and [(C9H7)2YbCl2][Li(DME)3]

The heterobimetallic bis(indenyl) chloride complexes of ytterbium and lutetium (C₉H₇)₂Ln(μ-Cl)₂Li(Et₂O)₂ (Ln = Yb or Lu) were synthesized by the metathesis reaction of LnCl₃ with two equivalents of indenyllithium in diethyl ether. In the case of ytterbium, the analogous reaction in 1,2-dimethoxyethane afforded the ionic complex [(C₉H₇)₂YbCl₂]⁻[Li(DME)₃]⁺. The reaction of YbCl₃ with indenylpotassium in a molar ratio of 1: 2 in THF is accompanied by reduction of the metal atom to give the bis(indenyl) derivative of Yb^II, (C₉H₇)₂Yb(THF)₂. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 39–44, January, 2008.     

Simple Lanthanide Amides [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3 as Highly Efficient Catalysts for the Nitroaldol Reaction

This contribution is to report the application of simple lanthanide amides [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3 exhibiting a high activity toward catalyzing Henry reaction of aromatic aldehydes with nitroalkanes to give β-nitroalcohols or β-nitroolefins with a very good chemoselectivity by controlling the reaction temperatures and by selecting aromatic aldehydes. It was found that this catalytic system was compatible with a wide range of substrates of aldehydes.     

Synthesis,structure and catalytic activity of complexes [Ln(EDBP)_2(DME)Na(DME)_3](Ln=Er,Yb,Sm) for ring-opening polymerization of ε-caprolactone

Discrete ion-pair complexes [Ln(EDBP)2(DME)Na(DME)3] [Ln=Er (1), Yb (2), Sm (3)] have been synthesized by the reaction between sodium salt of 2,2'-ethylidene-bis(4,6-di-tert-butylphenol)(EDBPH2) and Ln(BH4)3·3THF (Ln=Er, Yb, Sm) followed by centrifugation and recrystalization. The complexes were characterized by elemental analysis and FT-IR, and the bonding model of these compounds was confirmed by X-ray single crystal diffraction for complex 1. It was found that four O atoms in two biphenol ligands as well...     

Mixed-ligand guanidinate derivatives of rare-earth metals. Molecular structures of { (Me3Si)2NC(N-cyclo-Hex)2}Y[N(SiMe3)2]2, [{ (Me3Si)2NC(N-cyclo-Hex)2}YbI(THF)2]2, and [{(Me3Si)2N} Y(THF)(µ-Cl)]2 complexes

The insertion of N,N′-dicyclohexylcarbodiimide at one of the Y-N bonds of the [(Me₃Si)₂N]₃Y complex in toluene at 70 °C afforded the monoguanidinate diamide derivative { (Me₃Si)₂NC(N-cyclo-Hex)₂}Y[N(SiMe)₃]₂ (1) (cyclo-Hex is cyclohexyl) in 72% yield. The reaction of equimolar amounts of sodium N,N′-dicyclohexyl-N″-bis(trimethylsilyl)guanidinate, which was prepared in situ from {(Me₃Si)₂N}Na and N,N′-dicyclohexylcarbodiimide, and YbI₂(THF)₂ in THF gave the [{(Me₃Si)₂NC(N-cyclo-Hex)₂}YbI(THF)₂]₂ complex (2). An attempt to use this procedure for the synthesis of the yttrium compound { (Me₃Si)₂NC(NSiMe₃)₂}₂YCl containing the sterically more hindered guanidinate ligand unexpectedly led to the formation of the diamide chloride complex [{(Me₃Si)₂N}₂Y(THF)(µ-Cl)]₂ (3). The structures of complexes 1–3 were established by X-ray diffraction. Compound 1 is mononuclear. Complexes 2 and 3 are dinuclear and contain two µ²-bridging halide ligands.     

[(C5H4Me)2Sm(THF)(DME)][BPh4]的合成和晶体结构

三（甲基环戊二烯基）钐和四苯基硼银在四氢呋喃和乙二醇二甲醚混合溶剂中反应合成了 阳离子稀土有机化合物「（Ｃ５Ｈ４Ｍｅ）２Ｓｍ（ＴＨＦ）（ＤＭＥ）」ＢＰｈ４」。产物经元素分析,红外光谱和Ｘ射线晶体结构表征,分子式为Ｃ８８Ｈ１０４Ｂ２Ｏ６Ｓｍ２,分子量１５８０．２１,单斜晶系,空间群Ｐ２１／ａ,ａ＝１．７９１１（４）ｂｎｍ,ｂ＝２．１３６８９４）ｎｍ,ｃ＝２．０８９４（７）ｎｍ,β＝１０１．７７（２）     

Lanthanide amides [(Me(3)Si)(2)N](3)Ln(μ-Cl)Li(THF)(3) catalyzed hydrophosphonylation of aryl aldehydes

A highly efficient method for the synthesis of α-hydroxy phosphonates via lanthanide amides [(Me(3)Si)(2)N](3)Ln(μ-Cl)Li(THF)(3) catalyzed hydrophosphonylation of aromatic aldehydes was developed. The reactions produced the products in excellent yields in the presence of 0.1 mol % [(Me(3)Si)(2)N](3)La(μ-Cl)Li(THF)(3) at room temperature within 5 min. The existence of LiCl in the catalyst was a key factor affecting the catalytic activity. The mechanism for the process of high efficiency was proposed.     

Synthesis, structure and catalytic activity of complexes [Ln(EDBP)2(DME)Na(DME)3](Ln=Er, Yb, Sm) for ring-opening polymerization of ?-caprolactone

Discrete ion-pair complexes [Ln(EDBP)₂(DME)Na(DME)₃] [Ln=Er (1), Yb (2), Sm (3)] have been synthesized by the reaction between sodium salt of 2,2′-ethylidene-bis(4,6-di-tert-butylphenol)(EDBPH₂) and Ln(BH₄)₃·3THF (Ln=Er, Yb, Sm) followed by centrifugation and recrystalization. The complexes were characterized by elemental analysis and FT-IR, and the bonding model of these compounds was confirmed by X-ray single crystal diffraction for complex 1. It was found that four O atoms in two biphenol ligands as well as two O atoms in one ethylene glycol dimethyl ether (DME) molecule connect to the center rare earth metal atom, while sodium exists as counterpart cation to balance the charge. Complexes 1–3 can all be used as single component initiators for the ring-opening polymerization of ɛ-caprolactone.     

Synthesis and properties of homoleptic 2,2′-bipyridyl complexes of rare-earth elements. Crystal and molecular structures of the complexes Ln(N2C10H8)4 (Ln=Sm, Eu, Yb, or Lu) and the ionic complex [Lu(N2C10H8)4][Li(THF)4]

Homoleptic 2,2′-bipyridyl complexes of lanthanides (Ln), Ln(bpy)₄, were prepared by the reactions of iodides LnI₂(THF)₂ (Ln=Sm, Eu, Tm, or Yb), LnI₃(THF)₃ (Ln=La, Ce, Pr, Nd, Gd, or Tb), or bis(trimethylsilyl)amides Ln[N(SiMe₃)₂]₃ (Ln=Dy, Ho, Er, or Lu) with bipyridyllithium in tetrahydrofuran (THF) or 1,2-dimethoxyethane in the presence of free 2,2′-bipyridine. The IR and ESR spectral data, the magnetic susceptibilities, and the results of X-ray diffraction analysis indicate that the complexes of all elements of the lanthanide series, except for the europium complex, contain Ln⁺³ cations and anionic bpy ligands. According to the X-ray diffraction data, the coordination polyhedra about the Sm and Eu atoms are cubes, whereas the environment about the Yb atom is a distorted dodecahedron. In the ionic complex [Lu(bpy)₄][Li(THF)₄], the geometry of the [Lu(bpy)₄]⁻ anion is similar to that of the Lu(bpy)₄ complex. The possible modes of charge distributions over the ligands,viz., Ln(bpy²⁻)(bpy^.−)(bpy⁰)₂ and Ln(bpy^.−)₃(bpy⁰), are discussed. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1897–1904, November, 2000.     

Synthesis,structure and stereochemistry of diiodide complexes (E)[(η5-t-BuC5H3)Fe(CO)2I]2 (E = Me2Si,Me2SiSiMe2, and Me2SiOSiMe2)

Reactions of diiron complexes (E)[⁵-t-BuC₅H₃)Fe(CO)]₂(-CO)₂ [E = Me₂Si (1), Me₂SiSiMe₂ (2), and Me₂SiOSiMe₂ (3)] with iodine in CHCl₃ yielded diiodide complexes (E)[⁵-t-BuC₅H³)Fe(CO)₂I]₂ [E=Me₂Si (5), Me₂SiSiMe₂ (6), and Me₂SiOSiMe₂ (7)]. Like (1–3), complexes (5–7) also exists as mixtures of cis and trans isomers even though the Fe–Fe bond in (1–3) has been cleaved. When the pure isomers (1–3) reacted with iodine respectively in CHCl₃, the cis isomers (1c–3c) yielded only the cis products (5c–7c), whereas the trans isomers (1t–3t) yielded only the trans isomers (5t–7t). This indicates that iodination of bridged diiron complexes is stereospecific. Similar treatment of trans-(Me₂Si)[{⁵-t-(heptyl)C₅H₃}Fe(CO)]₂(-CO)₂ (4t) with iodine gave only the trans product (Me_2Si)[{⁵-t-(heptyl)C₅H₃}Fe(CO)₂I]₂ (8t). The molecular structure of (5t) was determined by X-ray diffraction.     

Low-temperature thermodynamics of Ln(Me2dtc)3(C12H8N2) (Me2dtc = dimethyldithiocarbamate, Ln = La, Pr, Nd, Sm)

The heat capacities of Ln(Me₂dtc)₃(C₁₂H₈N₂) (Ln = La, Pr, Nd, Sm, Me₂dtc = dimethyldithiocarbamate) have been measured by the adiabatic method within the temperature range 78–404 K. The temperature dependencies of the heat capacities, C _p,m [La(Me₂dtc)₃(C₁₂H₈N₂)] = 542.097 + 229.576 X ? 27.169 X ² + 14.596 X ³ ? 7.135 X ⁴ (J K^?1 mol^?1), C _p,m [Pr(Me₂dtc)₃(C₁₂H₈N₂)] = 500.252 + 314.114 X ? 17.596 X ² ? 0.131 X ³ + 16.627 X ⁴ (J K^?1 mol^?1), C _p,m [Nd(Me₂dtc)₃(C₁₂H₈N₂)] = 543.586 + 213.876 X ? 68.040 X ² + 1.173 X ³ + 2.563 X ⁴ (J K^?1 mol^?1) and C _p,m [Sm(Me₂dtc)₃(C₁₂H₈N₂)] = 528.650 + 216.408 X ? 16.492 X ² + 12.076 X ³ + 4.912 X ⁴ (J K^?1 mol^?1), were derived by the least-squares method from the experimental data. The heat capacities of Ce(Me₂dtc)₃(C₁₂H₈N₂) and Pm(Me₂dtc)₃(C₁₂H₈N₂) at 298.15 K were evaluated to be 617.99 and 610.09 J K^?1 mol^?1, respectively. Furthermore, the thermodynamic functions (entropy, enthalpy and Gibbs free energy) have been calculated using the obtained experimental heat capacity data.     

Structure of [Dy(Phen)(C4H8NCS2)3]·3CH2Cl2 solvate. Magnetic properties and photoluminiscence of [Ln(Phen)(C4H8NCS2)3] (Ln = Sm,Eu, Tb,Dy, Tm) complexes

It is found that diffraction patterns of complexes I–V of the composition [Ln(Phen)(C₄H₈NCS₂)₃] (Ln = Sm, Eu, Tb, Dy, and Tm respectively) are similar. Single crystals of [Dy(Phen)(C₄H₈NCS₂)₃]·3CH₂Cl₂ (VI) obtained are. According to the X-ray crystallographic data, in the structure of VI the unit cell contains two crystallographically independent molecules of the [Dy(Phen)(C₄H₈NCS₂)₃] complex and six CH₂Cl₂ molecules. The N₂S₆ coordination polyhedron of the Dy atom is a distorted square antiprism. In the range of 2–300 K the magnetic properties of complexes I–V are studied. It is found that complex III passes to the magnetically ordered state; the spontaneous magnetization at 2 K is 24 600 G·cm³/mol. At 300 K compounds I–IV exhibit photoluminescence in the visible spectral range. It is found that the photoluminescence intensity of complex I is several times higher than the photoluminescence intensity of complexes II–IV.     

Bulk polymerization of rac-lactide initiated by guanidinate alkoxide complexes of rare earth metals. The molecular structure of the cluster [{(Me3Si)2NC(NPri)2}Nd]4(μ3-OPri)8Li7(μ2-Cl)3(μ3-Cl)2(μ4-Cl)2

The complexes {(Me₃Si)₂NC(NPrⁱ)₂}₂LnOBu^t (Ln = Y (1), Lu (2)) initiate the bulk polymerization of racemic lactide (LA) at 130 °C. At the monomer: initiator molar ratio ([LA]: 1) equal to 1000: 1, the quantitative conversion of the monomer is achieved within 6 h. The resulting polymers are characterized by a rather narrow monomodal molecular weight distribution (M _w/M _n = 1.46–1.82) and molecular weights up to 33400 g mol^?1. The molecular weights of the resulting polylactides measured by gel permeation chromatography are 3–11 times lower than the values calculated from the monomer: initiator ratio on the assumption of one growing polymer chain per catalytic center. The reaction of the in-situ prepared complex [(Me₃Si)₂NC(NPrⁱ)₂]NdCl₂ with 2 equiv. of PrⁱOLi produced the 11-nuclear cluster [{(Me₃Si)₂NC(NPrⁱ)₂}Nd]₄(μ³-OPrⁱ)₈Li₇(μ²-Cl)₃(μ³-Cl)₂(μ⁴-Cl)₂ (3), which was isolated in 62% yield. The structure of compound 3 was established by X-ray diffraction. Complex 3 initiates both the bulk and solution polymerization of rac-lactide. In the bulk polymerization at the molar ratio [LA]: [Nd] = 500: 1, the 89% conversion of the monomer was achieved within one hour. The polylactide thus synthesized has the molecular weight M _n = 19720 g mol^?1 and a rather narrow polydispersity M _w/M _n = 1.54.     

Synthesis and reactivity of the complexes [(dpp-bian)SiCl2] and [(dpp-bian)Si{FeCp(CO)}2(μ-CO)] (dpp-bian is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene)

Russian Chemical Bulletin - The complex [(dpp-bian)SiCl2] (1) was synthesized by the reaction of the free 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) ligand with Si2Cl6. Despite...     

配合物[Li(DME)~3] [(t-BuCp)~2Nd(NPh~2)~2]·1/2 DME的合成及晶体结构

本文合成了配合物[ Li(DME)~3] [(t-BuCp)~2Nd(NP-h~2)~2]·1/2 DME 并测定了其晶体结构. 晶体结构利用Patterson 和Fourier 技术得到, 并经最小二乘法修正.转入各向异性温度因子后, 按理论模型投入所有氢原子坐标, 最后一致性因子R=0.042, Rw=0.040.     

N2S2 macrocyclic ligands. Synthesis and characterization of novel transition metal complexes of the type [LM(Si2Me6NH)2]2+ and [L′M(Si2Me6NH)2]2+

Summary Novel N₂S₂ macrocyclic ligands, L and L [SS-diethyl(1,3-diaminopropane) dithiocarbamate], [SS-cyclohexyl spiro-(1,3-diaminopropane) dithiocarbamate] and their complexes with Mn^II, Fe^II, Co^II, Ni^II and Cu^II have been characterized by elemental analyses, conductivity measurements, i.r., u.v.-vis. and n.m.r. spectra. The divalent transition metal complexes appear to be square planar and achieve octahedral geometry when treated with bis(trimethylsilyl)-amine to yield new heterobimetallic complexes.     

New yttrium complexes with the 1,8-bis(trimethylsilylamido)naphthalene ligand. The molecular structures of complexes [1,8-C10H6(NSiMe3)2YCl(DME)]2(μ-Cl)[Li(DME)3] and {[1,8-C10H6(NSiMe3)2]YN(SiMe3)2(μ-Cl)}2{Li(DME)3}2

The reaction of equimolar amounts of YC1₃ and [1,8-C₁₀H₆(NSiMe₃)₂]Li₂ in THF produced the complex {[1,8-C₁₀H₆(NSiMe₃)₂YCl(DME)]₂(μ-Cl)}[Li(DME)₃] (1), which was isolated by recrystallization from a DME—hexane mixture as yellow crystals in 82% yield. The reaction of complex 1 with (Me₃Si)₂NLi(Et₂0) (in a molar ratio of 1:2) in toluene gave the corresponding amide derivative [1,8-C₁₀H₆(NSiMe₃)₂YN(SiMe₃)₂(μ-Cl)]₂[Li(DME)₃]₂ (2). The recrystallization of the reaction product from toluene afforded complex 2 in 73% yield. The X-ray diffraction study showed that in the crystalline state, compounds 1 and 2 consist of the isolated cationic and anionic moieties. The complex anions are dinuclear moieties with the bridging chlorine ligands.     

Coordination and reductive chemistry of tetraphenylborate complexes of trivalent rare earth metallocene cations, [(C5Me5)2Ln][(μ-Ph)2BPh2

The reactivity of the tetraphenylborate salts of the rare earth metallocene cations [(C(5)Me(5))(2)Ln][(μ-Ph)(2)BPh(2)] (Ln = Y, 1; Sm, 2) has been investigated with substrates that undergo reduction with f element complexes to probe metal-substrate interactions prior to reduction. Results with NaN(3), 1-adamantyl azide, acetone, benzophenone, phenanthroline, pyridine, azobenzene, and phenazine are described. Not only were coordination complexes isolated, but substrate reduction by (BPh(4))(-) was also observed. Complex 1 reacts with NaN(3) to form the azide [(C(5)Me(5))(2)YN(3)](x), 3, which crystallizes as [(C(5)Me(5))(2)Y(μ-N(3))](3), 4, when obtained from 1 and 1-adamantyl azide. The samarium analogue [(C(5)Me(5))(2)SmN(3)](x), 5, can be produced similarly from 2 and NaN(3) and crystallized from MeCN as [(C(5)Me(5))(2)Sm(NCMe)(μ-N(3))](3), 6, and {[(C(5)Me(5))(2)Sm(μ-N(3))][(C(5)Me(5))(2)Sm(NCMe)(μ-N(3))]}(n), 7. Complexes 1 and 2 react with stoichiometric amounts of acetone and benzophenone to form the ketone adducts [(C(5)Me(5))(2)Ln(OCMe(2))(2)][BPh(4)] (Ln = Y, 8; Sm, 9) and [(C(5)Me(5))(2)Ln(OCPh(2))(2)][BPh(4)] (Ln = Y, 10; Sm, 11), respectively. Phenanthroline (phen) coordinates to 1 to form [(C(5)Me(5))(2)Y(phen)][BPh(4)], 12. Complexes 1 and 2 react with pyridine (py) to form [(C(5)Me(5))(2)Ln(py)(2)][BPh(4)], (Ln = Y, 13; Sm, 14). Complexes 3, 8, 10, and 12 can also be made from the solvated cation [(C(5)Me(5))(2)Y(THF)(2)][BPh(4)]. The reaction of 1 with PhNNPh yields the diamagnetic adduct [(C(5)Me(5))(2)Y(PhNNPh)][BPh(4)], 15, which transforms in benzene to the radical anion complex (C(5)Me(5))(2)Y(PhNNPh), 16, via a one electron reduction by (BPh(4))(-). Complex 1 similarly reacts with phenazine (phz) to produce the first rare earth phenazine radical anion complex {[(C(5)Me(5))(2)Y](2)(phz)}{BPh(4)}, 17. Further reduction of phenazine by (BPh(4))(-) in 17 yields [(C(5)Me(5))(2)Y](2)(phz), 18, which contains the common (phz)(2-) dianion. The reduction of fluorenone by (BPh(4))(-) is also reported.     

New Stable Germylenes,Stannylenes, and Related Compounds II. Bis(butylthio)tin(II) and ate-Complexes [(Me3Si)3CE(μ-SBu)2Li(THF)2] (E = Ge,Sn). Synthesis and Structure

By reaction of Me₃SiSBu with anhydrous tin(II) chloride bis(butylthio)tin was obtained that exemplified a coordination polymer [Sn(SBu)₂] _n , whose elementary unit contained according to X-ray diffraction study three independent four-membered rings Sn₂S₂ of unusual geometry. It was demonstrated that polymeric thiolates [E(SBu)₂] _n (E = Ge, Sn) readily reacted with TsiLi (Tsi = C(SiMe₃)₃) in a mixed solvent ether THF affording in a good yield ate-complexes [(Me₃Si)₃CE(-SBu)₂Li(THF)₂]. Both complexes contain a four-membered ring in a butterfly conformation where the lithium atom is symmetrically bonded to both sulfur atoms, and the coordination polyhedra of Ge and Sn atoms may be regarded as distorted tetrahedra AB₃X, where one of coordination places is occupied by unshared electron pair. The structure of the ate-complexes observed in a crystal is conserved also in solution of nonpolar solvents.     

Thermal decomposition reaction kinetics of complexes of [Sm(o-MOBA)3bipy]2·H2O and [Sm(m-MOBA)3bipy]2·H2O

The complexes of [Sm(o-MOBA)₃bipy]₂·H₂O and [Sm(m-MOBA)₃bipy]₂·H₂O (o(m)-MOBA = o(m)-methoxybenzoic acid, bipy-2,2′-bipyridine) have been synthesized and characterized by elemental analysis, IR, UV, XRD and molar conductance, respectively. The thermal decomposition processes of the two complexes were studied by means of TG–DTG and IR techniques. The thermal decomposition kinetics of them were investigated from analysis of the TG and DTG curves by jointly using advanced double equal-double steps method and Starink method. The kinetic parameters (activation energy E and pre-exponential factor A) and thermodynamic parameters (ΔH ^≠ , ΔG ^≠ and ΔS ^≠) of the second-step decomposition process for the two complexes were obtained, respectively.