Furfuroxides of lanthanum,praseodymium, neodymium,and samarium

Ln(R)₃, Ln(R)₂(OPrⁱ), and Ln(R)(OPrⁱ)₂ (where Ln = La, Pr, Nd, and Sm; R = deprotonated furfuryl alcohol, RH) were prepared from lanthanide isopropoxide and furfuryl alcohol in 1:3, 1:2 and 1:1 stoichiometric ratios respectively in anhydrous benzene under reflux. Ln(R)₂-(OPrⁱ) and Ln(R)(OPrⁱ)₂ were also obtained at room temperature. The isopropoxy group(s) of these derivatives were replaced by tertiary butoxy group(s) during the alcohol exchange reactions with tertiary butanol. All these derivatives are soluble in benzene except the tertiary butoxy derivatives which are only sparingly soluble. However, they become insoluble on standing. These furfuroxides did not distil at ～300°C/10² torr but decomposed. Isopropoxy/butoxy furfuroxides were characterized by the elemental analysis and also by estimating the liberated isopropanol. The i.r. spectra of Ln(R)₃ clearly supports the presence of furfuroxide groups in these derivatives.     

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 ).     

Synthesis and properties of some Metal Crotyloxides

The crotyloxides of the general formula M(OCH₂? CH ? CH-CH₃)_n [when M = B and Al, n = 3; M = Ti and Ge, n = 4 and M = Nb and Ta, n = 5] and Bu_nSn(OCH₂? CH ? CH? CH₃)₄-n [where n = 2 and 3] have been synthesized by the reaction of the corresponding metal alkoxide (ethoxide or isopropoxide) with crotyl alcohol in the appropriate molar ratios. These derivatives have been characterized by elemental analysis, i.r. and p.m.r. spectra. Their refractive indices and molecular weigths have also been measured.     

Synthesis and structure of titanium alkoxide complexes with bulky ligands derived from natural products: Asymmetric epoxidation of cinnamyl alcohol

A family of titanium(IV) alkoxide compounds [{Ti(OPrⁱ)₃(OR)}₂], [{Ti(OPrⁱ)₂(OR)₂}₂], and Ti(OR)₄ (1-12) have been prepared using two different routes: by metathesis reaction of TiCl(OPrⁱ)₃ and TiCl₂(OPrⁱ)₂ with ROH in the presence of Et₃N and alternatively by alcohol exchange of Ti(OPrⁱ)₄ and the corresponding higher boiling alcohol (ROH=adamantanol, 1,2:3,4-di-O-isopropylidene-α-d-galactopyranose, 1,2:5,6-di-O-isopropylidene-α-d-glucofuranose, 1R,2S,5R-(−)-menthol). These tetra alkoxide titanium(IV) compounds have been characterized by spectroscopic techniques. In addition, some of these chiral Lewis acid titanium compounds, derived from diacetone galactose and diacetone glucose, have been studied in the asymmetric epoxidation of cinnamyl alcohol in order to evaluate their catalytic activity and stereoselectivity.     

Lanthanide and Transition Metal Complexes of Dialkyl α-Hydroxyiminophosphonates

Abstract

α-Hydroxyiminophosphonic acid derivatives are widely known not only as intermediates in the synthesis of the important aminophosphonic acids,^1,2 but also as phosphorylating agents,³ potential metalloenzyme inhibitors,⁴ and as compounds having fungicidal activity.⁵ In this work the scope of these compounds has been extended considerably by the synthesis of a number of novel dialkyl derivatives. Novel lanthanide (La^III, Pr^III, Nd^III, Gd^III and Dy^III) and transition metal (Co^II and Ni^III) complexes of dialkyl α-hydroxyiminophosphonates (RO)₂P(O)C(R')N(OH) where R = Et. Prⁱ and R′ = Me, Et have been prepared and the NMR shift properties of the Pr^III complex (R = Et; R′ = Et) indicate the potential of these compounds as NMR shift reagents for the analysis of geometric isomers.^6,7 X-ray crystal structure analysis of [Ni(L¹)₂C1₂] (L¹: R = Et; R′ = Et) shows a distorted cis octahedral coordination at the nickel atom giving two symmetry related diethyl-(E)-α-hydroxyiminopropanephosphonate ligands and two chlorine donors, and those of [Pr(L²)₃Cl₃] and [Nd(L²)₂(NO₃)₃(H₂O)] (L²: R = Prⁱ; R′ = Et) show nine-coordination geometries with asymmetric bidentate and monodentate L² bonding respectively. Thus the metal complexes show unusual coordination ambivalence, changing from symmetrically bidentate to asymmetrically bidentate and then to monodentate bonding modes, to accommodate the different steric requirements of the coordinating anions in facilitating neutral complex formation.     

Influence of the lead carboxylate on the molecular composition of its solutions with zirconium and titanium isopropoxides or n-butoxides: 2-ethylhexanoate vs acetate, a way to stabilize the first Pb-Zr carboxylatoalkoxides of 1:1 stoichiometry

The reactions between titanium or zirconium alkoxides namely Ti(OR)₄ (R = ⁱ Pr, ⁿ Bu) or Zr₂(O ⁱ Pr)₈(HO ⁱ Pr)₂, Zr(O ⁿ Bu)₄ respectively and lead 2-ethylhexanoate Pb(O₂CC₇H₁₅)₂ were investigated at room temperature (rt) and by heating. The various compounds were characterized by elemental analysis, FT-IR, ¹H and ²⁰⁷Pb NMR. The mixed-metal species obtained at rt were adducts Pb₄Zr₄(μ-O₂CR′)₈(OR)₁₆(OHR)₂ 1 and Pb₂Ti₄(μ-O₂CR′)₄(OR)₁₆ 2 (R′=CHCHEt(CH₂)₂Me, R = ⁱ Pr) independently of the stoichiometry used. The structures of 1 and 2 are based on triangular M₂Pb cores (M = Zr, Ti). with 6-coordinate transition metals -as required for perovskites- and 6- or 7-coordinate lead atoms. Similar observations were made with n-butoxides. Thermal and hydrolytic condensation reactions were investigated. Thermal condensation was more difficult for the n-butoxide derivatives than for the isopropoxide ones. Powders derived from the hydrolysis of the Single Source Precursor 1 in various conditions were characterized by TGA, XRD and SEM for the PZ ceramic.     

Lanthanon (III) Derivatives of Monofunctional Bidentate Schiff Bases

The 1:1, 1:2 and 1:3 interactions of lanthanon (III) isopropoxide with monofunctional bidentate Schiff bases as salicylidene-o-toluidine (SOTH) and salicylidene-p-p-toluidine (SPTH) have been investigated. The resulting products Ln(OPr¹)₂(SB), Ln(OPr¹)(SB)₂ and Ln(SB)₃ (where Ln=Pr, Nd and Sm and SB^1? is the anion of the corresponding Schiff base) have been isolated in almost quantitative yields. The infrared spectra of these compounds have been recorded and plausible structures suggested.     

Studies on the alcohol exchange reactions of methoxide ditungsten [W(IV)] compound W2Cl4(OCH3)4 (CH3OH)2, prepared from (n-Bu4N)3W2Cl9

(n-Bu₄N)₃W₂Cl₉, prepared from K₃W₂Cl₉, can be readily converted to a series of [W(IV)] cluster compounds, W₂Cl₄ (μ-OR)₂ (OR')₂ (R'OH)₂, including seven known compounds and two new compounds with R=Me, R'=i-Pr and sec-Bu. The crystallographic data of 7 and 8 are hereby presented.     

Incorporation of Titanium(IV) into Sterically Hindered Schiff Bases of Heterocyclic β -Diketones Involving Ketooximes and Glycol as Coligands: Preparation and Structural Considerations

Titanium(IV) complexes of the general formula TiL(OPr ⁱ )₂ [where LH₂ = R CH₃ where R = ─C₆H₅, ─C₆H₄Cl(p)] were prepared by the interaction of titanium isopropoxide with sterically hindered Schiff bases derived from heterocyclic β -diketones in 1:1 molar ratio in dry benzene. The complexes TiL(OPr ⁱ )₂ were used as versatile precursors for the synthesis of other titanium(IV) complexes. Titanium(IV) complexes of the type TiLL'(OPr ⁱ ) (where L'H═R¹R²C═NOH, R¹ = R² = ─CH₃; R¹ = ─CH₃,R² = ─C₆H₅; R¹ = ─COC₆H₅, R² = ─C₆H₅) were synthesized by the reaction of TiL(OPr ⁱ )₂ with ketooximes (L'H) in equimolar ratio in dry benzene. Another type of titanium(IV) complexes having the general formula TiLGH(OPr ⁱ ) (where GH₂═HO─G─OH, G = ─CH₂─CH₂─) have been prepared by the reaction of TiL(OPr ⁱ )₂ with glycol in 1:1 molar ratio in dry benzene. Plausible structures of these new titanium(IV) complexes have been proposed on the basis of analytical data, molecular weight measurements, and spectral studies.     

Synthesis and characterization of cyclopentadienyl/alkoxo titanium dichlorides: structural analysis of monocyclopentadienyl titanium dichlorides with ligands derived from menthol and borneol

A variety of monocyclopentadienyl alkoxo titanium dichloride and bisalkoxo titanium dichloride complexes have been prepared and characterized by spectroscopic techniques. The titanium derivatives containing both cyclopentadienyl and various alkoxo ligands [Ti(η⁵-C₅H₅)(OR)Cl₂] (1-5) have been synthesized from the reaction of [Ti(η⁵-C₅H₅)Cl₃] with 1 equivalent of the corresponding alcohol in THF in the presence of triethylamine (ROH = Adamantanol, 1R,2S,5R-(−)-menthol, 1S-endo-(−)-borneol, cis-1,3-(−)-benzylideneglycerol, 1,2:3,4-di-O-isopropylidene-α-d-galactopyranose). The bisalkoxo titanium dichloride derivatives [TiCl₂(OR)₂] (6-10) have been prepared by a redistribution reaction between Ti(OR)₄ and TiCl₄ compounds 6-8 (OR = Adamantanoxy, (1R,2S,5R)-(−)menthoxy, (1S-endo)-(−)-borneoxy) and by reaction of [Ti(OR)₂(OPrⁱ)₂]₂ with CH₃COCl compounds 9 and 10 (OR = 1,2:3,4-di-O-isopropylidene-α-d-galactopyranoxy, and 1,2:5,6-di-O-isopropylidene-α-d-glucofuranoxy). The molecular structures of 2 and 3 have been determined by single crystal X-ray diffraction studies.     

μ,μ,-bis(alcoholato)- and μ,μ-bis(phenolato)dirhodium(I) tetracarbonyl complexes

Rh₂(CO)₄(OR)₂ complexes (R = Me, Et, Pr, i-pent, Ph, p-chlorophenyl) were prepared from Rh₂(CO)₄Cl₂ and sodium alcoholates or phenolates. They are converted by phosphines into the monomeric Rh(CO)(PR′₃)₂(OR) derivatives (R′ = Bu, Ph) via Rh₂(CO)₃(PR′₃)(OR)₂ intermediates.     

Spectral studies of the newly synthesized azomethine derivatives of zirconium(IV)

Equimolar and bimolar reactions of zirconium isopropoxide with bibasic tridentate azomethine (AZH₂) having the donor system ONO have been carried out and derivatives of the type Zr(OPr¹)₂(AZ) and Zr(AZ)₂ [Where AZ²⁻ is the anion of the azomethine molecule] have been isolated. The labile nature of the isopropoxy groups in 1∶1 derivatives has been shown by carrying out exchange reactions with equimolar amount of 2-methylpentane-2,4-diol. All the newly synthesized derivatives have been characterized on the basis of elemental analysis, conductance measurements, molecular weight determinations and infrared, ultraviolet, visible and proton magnetic resonance spectral studies.     

Synthesis,Structure, and Lanthanide Derivatives of an Unusual Hexameric Alcohol: [2,4,6-(CF3)3C6H2CH2OH]6

Hitherto unknown 2,4,6-tris(trifluoromethyl)benzyl alcohol ( 3 ) was synthesized in 41 % yield by treatment of freshly prepared R_FLi ( 2 ) with paraformaldehyde (R_F = 2,4,6-tris(trifluoromethyl)phenyl). According to an X-ray diffraction study the crystal structure of 3 consists of S₆ symmetric cyclic hexamers [2,4,6-(CF₃)₃C₆H₂CH₂OH]₆. Deprotonation of 3 with NaN(SiMe₃)₂ in toluene afforded the unsolvated sodium alkoxide derivative R_FCH₂ONa ( 4 ). Homoleptic lanthanide alkoxides of the type Ln(OCH₂R_F)₃ (Ln = Nd ( 5 ), Sm ( 6 ), Yb ( 7 )) were made by treatment of Ln(C₅H₅)₃ with three equivalents of 3 . Similar reactions in a 1:1 molar ratio afforded the bis(cyclopentadienyl)lanthanide alkoxide derivatives (C₅H₅)₂Ln(OCH₂R_F) (Ln = Nd ( 8 ), Sm ( 9 ), Yb ( 10 )).     

Mono- and bis-alkoxides of tris(3,5-dimethylpyrazolyl)borato molybdenum and tungsten nitrosyls

The complexes [ML^*(NO)Cl(OR)] {L^* = HB(3,5-Me₂C₃HN₂)₃; M= Mo, R = CH₂CH₂X, X = Cl, OMe or OEt; (CH₂)_nOH, n = 2, 5, 6; M = W, R = CH₂CH₂X, X = Cl, OMe or OEt; (CH₂)_nOH, n = 2–6; CH₂(CF₂)₃CH₂OH; CHMeCH₂CMe₂OH} and [ML^*(NO)(OR)₂] {M = Mo, R = CH₂CH₂X, X = Cl, OMe or OEt; (CH₂)_nOH, n = 2–6; M = W,R = CH₂CH₂X, X= Cl, OMe or OEt; (CH₂)_nOH, n = 2,4–6; CH₂(CF₂)₃CH₂OH} have been prepared from [ML^*(NO)Cl₂] and the appropriate alcohol in the presence of NEt₃ or NaCO₃, and have been characterized by IR, ¹H NMR and mass spectroscopy.     

Studies On Rare-Earth Complexes with Crown Ethers. Part XXV. Synthesis,characterization, and structure of the complexes of lanthanide nitrates with 13-crown-4

The lanthanide nitrate complexes with 13-crown-4(13-C-4) have been prepared in AcOEt. These new complexes with the general formula Ln(NO₃)₃.(13-c-4) (Ln = La–Nd, Sm–Lu) have been characterized by means of elemental analysis, IR and ¹H-NMR spectra, conductivity measurements, and TG-DTA techniques. The crystal and molecular structure of Nd(No₃)₃. (13-c-4) has been determined by single crystal X-ray diffraction. It crystallizes in the monoclinic space group P2₁/a with Z = 8. Lattice parameters are a = 15.393(1), b = 12.578(1), c = 19.279(2) Å, β = 113.05(1)°, V = 3435 ų, D_c = 2.01 g cm^?3, μ = 31.0 cm^?1 (Mok₂), F(000) = 2056. The structure was solved by Patterson and Fourier techniques and refined by least-squares to a final conventional R value of 0.032 for 5218 independent reflections with I ? 3σ(I). There are two independent Nd(No₃)₃ · (13-C-4) monomers in one asymmetrical unit. The coordination numbers are ten in these two independent monomers.     

Synthesis and spectroscopy studies of new neodymium(III) complexes with cyanamide derivatives as N-Donor ligand

Four new complexes [Nd(phen)₂(pcyd)₃] (1), [Nd(phen)₂(2-Clpcyd)₃] (2), [Nd(phen)₂(2,3,5-Cl₃pcyd)₃] (3) and [Nd(phen)₂(2,3,4,5-Cl₄pcyd)₃] (4) where pcyd = phenylcyanamide anion, 2-Clpcyd = (2-chlorophenyl)cyanamide anion, 2,3,5- Cl₃pcyd = (2,3,5-threechlorophenyl)cyanamide anion and 2,3,4,5-Cl₄pcyd = (2,3,4,5-tetrachlorophenyl)cyanamide anion, were prepared and characterized by IR, UV-Vis and ¹H NMR spectroscopy as well as elemental analysis. The ¹H NMR spectra of these complexes show broadening of ligand protons attributed to coordination of paramagnetic center.     

铬(III)离子催化铈(IV)离子氧化四氢糠醇的反应动力学及机理

在酸性介质中用氧化还原滴定法研究了铈(IV)离子在铬(III)离子催化作用下, 于25～40 ℃区间氧化四氢糠醇的反应动力学. 结果表明反应对铈(IV)和四氢糠醇均为一级. 准一级速率常数k_obs随催化剂[Cr(III)]增加而增大, 亦随[H^＋]增加而增大, 而随增加而减小. 在氮气保护下, 反应不能引发丙烯酰胺聚合, 说明在反应中没有自由基产生. 提出了催化剂、底物和氧化剂间生成双核加合物的反应机理. 通过k_obs与的依赖关系, 并结合Ce(IV)在溶液中的平衡, 找到了本反应体系的动力学活性物种是Ce(SO₄)₂. 还计算出一些速率常数及相应的活化参数.     

Synthesis and characterization of 2-hydroxy-pyridine modified Group 4 alkoxides

The reaction of Group 4 metal alkoxides ([M(OR)₄]) with the potentially bidentate ligand, 2-hydroxy-pyridine (2-HO-(NC₅H₄) or H-PyO), led to the isolation of a family of compounds. The products isolated from the reaction of [M(OR)₄] [where M = Ti, Zr, or Hf; OR = OPrⁱ (OCH(CH₃)₂), OBu^t (OC(CH₃)₃), or ONep (OCH₂C(CH₃)₃] under a variety of stoichiometries with H-PyO were identified by single crystal X-ray diffraction as [(OPrⁱ)₂(PyO-κ²(O,N))Ti(μ-OPrⁱ)]₂ (1), [(ONep)₂Ti(μ(O)-PyO-κ²(O,N))₂(μ-ONep)Ti(ONep)₃] (2), [(ONep)₂Ti(μ(O)-PyO-κ²(O,N))(η¹(N),μ(O)-PyO)(μ-O)Ti(ONep)₂]₂ (2a), [H][(PyO-κ²(O,N))(η¹(O)-PyO)Ti(ONep)₃] (3), [(OR)₂Zr(μ(O)-PyO-κ²(O,N))₂(μ-OR)Zr(OR)₃] (OR = OBu^t (4), ONep (5)), [(OR)₂Zr(μ(O,N)-PyO-κ²(O,N))₂(μ(O,N)-PyO)Zr(OR)₃] (OR = OBu^t (6), ONep (7)), [[(OBu^t)₂Zr(μ(O)-PyO-(κ²(N,O))(μ(O,N)-PyO)₂Zr(OBu^t)](μ₃-O)]₂ (6a), [[(ONep)(PyO-κ²(N,O))Zr(μ(O,N)-PyO-κ²(N,O))₂(μ(O)-PyO-κ²(N,O))Zr(ONep)](μ₃-O)]₂ (7a), [(OBu^t)(PyO-κ²(O,N))Zr(μ(O)-PyO-κ²(O,N))₂((μ(O,N)-PyO)Zr(OBu^t)₃] (8), [(OBu^t)₂Hf(μ(O)-PyO-κ²(N,O))₂(μ-OBu^t)Hf(OBu^t)₃] (9), [(OR)₂ M(μ(O)-PyO-κ²(N,O))₂(μ(O,N)-PyO)M(OR)₃] (OR = OBu^t (10), ONep (11)), and [(ONep)₃Hf(μ-ONep)(η¹(N),μ(O)-PyO)]₂Hf(ONep)₂ (12)·tol. The structural diversity of the binding modes of the PyO led to a number of novel structure types in comparison to other pyridine alkoxy derivatives. The majority of compounds adopt a dinuclear arrangement (1, 2, 4–11) but oxo-based tetra- (2a and 7a), tri- (12), and monomers (3) were observed as well. Compounds 1–12 were further characterized using a variety of analytical techniques including Fourier Transform Infrared Spectroscopy, elemental analysis, and multinuclear NMR spectroscopy.     

Living polymerization with well-defined alkylidene catalysts

Alkylidene complexes of the type Mo(CH-t-Bu)(NAr)(OR)₂ (Ar = 2, 6-diisopropylphenyl; OR = O-t-Bu, OCMe₂(CF₃), OCMe(CF₃)₂, etc.) can be prepared from a “universal precursor”, Mo(CH-t-Bu)(NAr)(triflate)₂(1, 2-dimethoxyethane),¹ which can be prepared in three high-yield steps from ammonium dimolybdate.² These complexes serve as initiators for the ring opening metathesis of norbornenes and substituted norbornadienes,³ or for the polymerization of acetylenes to give polyenes,⁴ all in a living manner. The organic polymer can be cleaved upon treatment with an aldehyde. Norbornenes that contain a variety of organic or inorganic functionalities can be polymerized to give essentially monodisperse homopolymers and block copolymers. Recently chiral catalysts have been prepared that will polymerize norbornenes and norbornadienes stereoselectively to give all cis isotactic polymers.⁵ Molybdenum catalysts also have been found that will cyclopolymerize dipropargyl derivatives or substituted phenylacetylenes in a living manner.⁶ The stereospecific synthesis of all cis, or all trans, tactic polynorbornadienes and polynorbornenes will be discussed in detail, including a proof of tacticity.⁷     

Saure Sulfate des Neodyms: Synthese und Kristallstruktur von (H5O2)(H3O)2Nd(SO4)3 und (H3O)2Nd(HSO4)3SO4

Acidic Sulfates of Neodymium: Synthesis and Crystal Structure of (H₅O₂)(H₃O)₂Nd(SO₄)₃ and (H₃O)₂Nd(HSO₄)₃SO₄ Light violett single crystals of (H₅O₂)(H₃O)₂ · Nd(SO₄)₃ are obtained by cooling of a solution prepared by dissolving neodymium oxalate in sulfuric acid (80%). According to X‐ray single crystal investigations there are H₃O⁺ ions and H₅O₂⁺ ions present in the monoclinic structure (P2₁/n, Z = 4, a = 1159.9(4), b = 710.9(3), c = 1594.7(6) pm, β = 96.75(4)°, R_all = 0.0260). Nd³⁺ is nine‐coordinate by oxygen atoms. The same coordination number is found for Nd³⁺ in the crystal structure of (H₃O)₂Nd(HSO₄)₃SO₄ (triclinic, P1, Z = 2, a = 910.0(1), b = 940.3(1), c = 952.6(1) pm, α = 100.14(1)°, β = 112.35(1)°, γ = 105.01(1)°, R_all = 0.0283). The compound has been prepared by the reaction of Nd₂O₃ with chlorosulfonic acid in the presence of air. In the crystal structure both sulfate and hydrogensulfate groups occur. In both compounds pronounced hydrogen bonding is observed.