Coordination Chemistry Reviews
Volume 336,
April 1, 2017
, Pages 96-151
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graphic summary
This review brings together the main advances in the field of enantioselective transformations promoted by chiralslanthanidecatalysts, covering the literature since the beginning of 2012, well illustrating the power of these special catalysts in promoting different types of reactions.
Introduction
Asymmetric catalysis of organic reactions constitutes an important field in modern science and technology [1]. Although asymmetric catalysts containing p-block metal elements or d-block elements have been extensively investigated [1](d), [1](e), the use of f-block elements such as lanthanides as metal components for Asymmetric Lewis acid catalysts have been underestimated for a long time. The use of lanthanides (scandium, yttrium and lanthanum will be included as lanthanides in this review for brevity) in asymmetric catalysis was first reported by Danishefsky et al. in 1983, who obtained moderate enantioselectivities of up to 58% ee in europium-catalyzed hetero-Diels-Alder reactions [2]. Since then, the involvement of chiral lanthanide complexes as new catalysts in asymmetric synthesis has become of intense interest related to their unique chemical and physical properties. For example, because of their large ionic radii, lanthanide complexes can exhibit high coordination numbers of six or more (up to 12), maintaining their Lewis acidity in contrast to conventional Lewis acids which sometimes lose their activities as result of coordinative saturation. These properties are highly advantageous for the assembly of various chiral ligands around metals, allowing the construction of structurally sophisticated complexes to be achieved with an integrated chiral space in which the stereochemistry of the reaction can be effectively controlled. The aim of this review is to collect the main developments in all types of enantioselective transformations catalyzed by lanthanides published since the beginning of 2012, as this field was reviewed more recently by Mori and Kobayashi in a book chapter published in 2012, covering the literature until 2011 [3]. It should be noted that special coverage of enantioselective asymmetric reactions catalyzed by scandium and yttrium is limited to the year 2016, as two recent reviews published in 2016 included literature up to 2015 [4]. Prior to 2012, and more generally, the field of catalysis of rare earth (racemic) metals was reviewed by several authors [5]. Furthermore, several reports were reported by Shibasaki et al. [6]. The review is divided into eleven parts, dealing successively with the enantioselective Michael reactions catalyzed by lanthanides, the enantioselective reactions of cycloaddition catalyzed by lanthanides, the enantioselective reactions catalyzed by aldol-type lanthanides, the enantioselective reactions of epoxidation of alkenes catalyzed by lanthanides, the lanthanide-catalyzed enantioselective Mannich-type reactions, lanthanide-catalyzed enantioselective additions of 1,2-nucleophiles to carbonyl compounds and imines, lanthanide-catalyzed Friedel-Crafts reactions, lanthanide-catalyzed enantioselective hydroamination reactions, lanthanide-catalyzed ring-opening reactions by enantioselective lanthanides, domino and tandem reactions catalyzed by enantioselective lanthanides and various enantioselective reactions catalyzed by lanthanides.
section excerpts
Michael reactions catalyzed by enantioselective lanthanides
The conjugate addition of nucleophiles to electron-poor alkenes plays an important role in organic synthesis, allowing carbon-carbon and carbon-heteroatom bond formation reactions to be easily achieved [7]. Consequently, many different versions of this transformation, including asymmetric ones, have been reported, using a wide variety of nucleophiles, conjugate acceptors, as well as catalysts. In addition to the increasing success of organocatalysts to promote these reactions [8], chiral rare earth metals
1,3-Dipolar Cycloadditions
Cycloaddition reactions are important tools for assembling complex molecular structures [22]. Among them, the 1,3-dipolar cycloaddition [23] of a dipolarophile with a 1,3-dipolar compound allows the production of important five-membered heterocycles [24]. In early 1997, Jørgensen et al. reported asymmetric ytterbium-catalyzed 1,3-dipolar cycloadditions performed in the presence of a Pybox ligand, providing cycloadducts at enantioselectivities of up to 73% ee [25]. Since then, others
Direct aldol reactions
The direct catalytic asymmetric aldol reaction is a powerful and atom-economic method to prepare chiral β-hydroxycarbonyl compounds. Many metals, organocatalysts [38], but also more recently lanthanides [39] have been applied to promote these reactions. In fact, the first direct catalytic asymmetric aldol reaction between unmodified aldehydes and ketones was described by Shibasaki et al., in 1999 [40]. The process was promoted by the REMB La/Li heterobimetallic catalyst, providing
Enantioselective epoxidation reactions catalyzed by lanthanides of alkenes
Chiral epoxides are fundamental building blocks for the synthesis of a wide range of important products [55]. In particular, the asymmetric epoxidation of α,β-unsaturated carbonyl compounds is an important and challenging transformation in organic synthesis [56]. Since the first use of BINOL-derived chiral lanthanides as catalysts in these reactions reported by Shibasaki et al. in 1997 [57], other chiral complexes based on lanthanides were successfully investigated in such reactions. As a
Mannich-type reactions catalyzed by enantioselective lanthanides
The asymmetric catalytic Mannich reaction represents a powerful methodology for preparing a range of pharmaceutically and agrochemically relevant products [63]. Although recently several chiral organocatalysts have been successfully applied to promote these reactions, the number of approaches involving chiral metal complexes remains limited. In particular, enantioselective Mannich reactions based on the use of chiral ytterbium catalysts are unexplored. In 2013, Karimi et al. reported a rare
Lanthanide-catalyzed enantioselective 1,2-nucleophilic additions to carbonyl compounds and imines
Reactions involving highly reactive oxocarbenium ions generated in situ are challenging due to their usefulness in the synthesis of complex natural products and biologically active compounds. In 2012, Rueping et al. developed the first asymmetric addition of aldehydes110to in situ oxocarbenium ions generated from chromene acetals111, allowing the synthesis of the corresponding chiral chromenes112showing two stereogenic centers after subsequent reduction with NaBH4[66]. As shown no Schematic
Friedel-Crafts reactions catalyzed by enantioselective lanthanides
Despite the importance of the Friedel-Crafts reaction in organic chemistry [69]; enantioselective catalytic versions are still unexplored, even though a variety of chiral Lewis acids or organocatalysts have recently been developed for this type of reactions involving different substrates, including nitroalkenes. In particular, the useful asymmetric Friedel-Crafts reaction between these substrates and indoles has recently seen great advances using Lewis and Brønsted chiral acid catalysts [70]
Enantioselective hydroamination reactions catalyzed by lanthanides
Hydroamination, which consists of the addition of an amine N-H bond to an unsaturated carbon-carbon bond, is of great potential interest for the synthesis of nitrogen heterocycles that are found in various biologically active products. Consequently, it is not surprising that recent efforts have focused on the development of chiral catalysts for hydroamination of asymmetricalkenes [74]. Among them, chiral lanthanide catalysts have shown to be promising for this transformation, enabling the
Ring opening reactions catalyzed by enantioselective lanthanides
Nucleophilic ring opening of epoxides represents an important strategy in organic synthesis due to its powerful ability to form bonds [79]. This process leads to the possible formation of two adjacent stereocenters at the α,α' positions of themeso-epoxide, allowing chiral 1,2-difunctional compounds, including 1,2-diol monoethers, 1,2-aminoalcohols or 1,2-thioalcohols, to be easily synthesized. In the last decade, chiral or chiral bipyridine lanthanide complexesN,N'-dioxide
Scandium catalysts
A domino reaction was defined by Tietze as a process involving two or more bond-forming transformations that occur under the same reaction conditions, without the addition of additional reagents and catalysts, and in which subsequent reactions result as a consequence of the functionality formed by bond formation or fragmentation in the previous step [83]. The use of these one-pot reactions is steadily increasing [84], and has already allowed the synthesis of a wide range of natural complexes.
Various reactions catalyzed by enantioselective lanthanides
Asymmetric catalytic cyanosylation of aldehydes has been intensively studied with various chiral Lewis acids, including chiral lanthanide catalysts [96]. In 2014, Shibasaki and Kumagai reported the use of an in situ chiral gadolinium catalyst generated from Gd(HMDS)3and sugar-derived chiral ligand178to promote the enantioselective
Conclusions
This review demonstrates that the enantioselective catalysis of lanthanides has gained increasing interest and become indispensable in almost all spheres of organic transformations due to the unique coordination properties of these special catalysts. Lanthanides are characterized by their ability to accommodate a greater number of ligands than traditional metals, consequently, they are less prone to coordinative saturation and allow the construction of structurally sophisticated complexes.
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Quoted by (40)
Chemical reactivity profile of rare earth metal ions with flavonoids. From structural speciation to magneto-optical properties
2023, Polyhedron
Quote Excerpt:
Within the framework of such an undertaking, the focus of research was extended to the chemistry of lanthanides with potential antioxidants, anti-inflammatory, anticancer, organic antioxidant ligands [9-11] of natural origin. Lanthanides constitute a group of f-shell elements with similar physicochemical properties, among which luminescence, optical and magnetic properties and biological (i.e., antitumor) activity stand out in a wide range of application fields involving lasers , batteries, catalysis and medical imaging [12 –14]. Most lanthanide metal ions are suitable candidates for exploiting magnetic materials (e.g. single-molecule magnets) due to their ability to contribute to high spins or introduce anisotropy into a molecule and achieve a blocking temperature above that of liquid nitrogen , as a result of the nature of the f electron shell [15-18].
The diversity of metallopharmaceuticals used as diagnostics and therapeutics in the treatment of diseases and their predominant side effects on human metabolism present an urgent need for exploration and development of new metal-based agents. Among them, rare earth metals are unique when combined with natural binders such as antioxidant flavonoids. Therefore, a multiparametric synthetic investigation of Er(III), Dy(III), Sm(III) ternary systems with chrysin flavone and N,N'-aromatic chelator (phen) led to crystalline mononuclear materials, which were characterized physically -chemically through elemental analysis, FT-IR, UV-Visible, ESI-MS and X-ray crystallography. The trivalent lanthanide coordination environment in each assembly reveals salient features of the binding modes of the ternary components, with the contribution of chrysin to lanthanide coordination validated by BVS and Hirshfeld surface analysis. The structural, electronic and magnetic data of the new species demonstrate the importance of structural speciation in tracing correlations with optical and magnetic properties, thus formulating well-defined physical-chemical profiles and designing essential attributes linked to the development of new materials of potential diagnostic-therapeutic value.
Lanthanide complexes as redox probes and ROS/RNS: a new paradigm that makes use of redox-reactive and non-innocent redox ligands
2021, Coordination Chemistry Assessments
Quote Excerpt:
In particular, the distinctive properties of 4f electrons (see below) give these elements unique optical and magnetic properties that are currently exploited for many commercial applications. The various fields where lanthanides are a must-have include lasers [1], magnets [2], batteries [3], catalysis [4], phosphors [5], security ink [6], medical imaging [7]… Lanthanides are now considered strategic choices for a variety of applications. The solution chemistry of the lanthanides is largely dominated by the (+III) oxidation state under oxygenated atmosphere, which undoubtedly contributed to the original limited interest in these elements [8].
Lanthanide complexes are indispensable in areas related to medicine and biology. Its success lies in the large number of unpaired electrons (4f7gd configuration3+ion) which makes them ideal contrast agents for MRI. On the other hand, its narrow emission bands and long lifetime of its excited state provide unique luminescence properties. The chemistry of the aqueous solution of the lanthanides is dominated by the (+III) oxidation state under oxygenated atmosphere. This severely limits their use as redox probes and, not surprisingly, few redox-switches employing lanthanide ions were reported until 2010. A very promising approach based on redox-reactive and non-innocent redox ligands has recently emerged in the literature, which overcomes this limitation and expands the application of lanthanides for redox monitoring. Here, the ligand acts as a redox sensor, changing its oxidation state or reacting with reactive oxygen (or nitrogen) species (ROS/RNS). Its response induces changes in the environment of the lanthanide ion, which acts as a redox status reporter. Detection is based on modifying the magnetic or optical properties of the complexes, with detection by conventional spectroscopic techniques. We summarize in this review article recent advances in this burgeoning field, with special emphasis on the detection of ROS, RNS and redox status relevant to biology.
Cerium trinuclear complex based on a chiral ligand of 1,1'-binaphthyl-2,2'-diyl phosphate: Synthesis, characterization and model effect of chloride ion
2021, Inorganic Chemistry Communications
Quote Excerpt:
Lanthanide complexes have attracted much research attention for decades due to their potential applications in catalysis [1,2], luminescence [3,4], magnetic properties [5-7], bioimaging [8] and detection [9, 10 ].
A novel chiral trinuclear Ce complex [Ce3Cl(R-EU)6(EtOH)8(H2O)]Cl25EtOH2H2O(1)(R-L = (R)-1,1'-binaphthyl-2,2'-diyl phosphate) was synthesized and characterized by single crystal and powder X-ray diffraction, thermogravimetric analysis, magnetic measurements, UV absorption spectroscopy, infrared and circular dichroism (CD). A suitable reaction temperature was found to be 75°C. the complex1presents a {C3} triangle core with a Cl−anion as a template. Networks of hydrogen bonds were observed from network solvents and Cl−counterions binding [Ce3Cl(R-EU)6(EtOH)8(H2O)] cations. A strong positive and a strong negative Cotton effect were found in the CD spectrum at 214nm and 227nm, respectively. This chirality must originate from the chiral ligand.
Recent developments in enantioselective multicatalyzed tandem reactions
2020, Synthesis and Advanced Catalysis
This review presents an update on the emerging field of enantioselective multicatalyzed multicatalyzed tandem reactions published since early 2015. It illustrates how the combination of different types of catalysts allows unprecedented one-pot enantioselective reactions of many types to be achieved, allowing access to direct to a variety of very complex chiral molecules. : acac: acetylacetonate; Ar: aryl; Bn: benzyl; Boc:tert-butoxycarbonyl; BPE: 1,2-bis(2-pyridyl)ethane; Bz: benzoyl; CAPT: chiral anion phase transfer; Cbz: benzyloxycarbonyl; cod: cyclooctadiene; Cy: cyclohexyl; dba: (AND AND)‐dibenzylidenoacetone; DBU: 1,8-diazabicyclo[5.4.0]undec-7-eno; DCE: dichloroethane;of: diastereomeric excess; DIPEA: diisopropylethylamine; dme: 1,2-dimethoxyethane; DPG: 1,3-diphenylguanidine; dppe: 1,2-bis(diphenylphosphino)ethane;sim: enantiomeric excess; EWG: electron withdrawing group; Hept: heptyl; Hex: hexyl; L: ligand; MTBE: methyltert-butyl ether; MOM: methoxymethyl; MS: molecular sieves; Naf: naphthyl; NHC: No‐carbeno heterocíclico; Pent: pentil; Phth: ftaloil; alfinete: pinacolato; Pybox: 2,6-bis(2-oxazolil)piridina; t.a.: temperatura ambiente; TEMPO: 2,2,6,6-tetrametilpiperidina 1-oxil; Tf: trifluorometanossulfonilo; THF: tetrahidrofurano; TMP: 2,2,6,6-tetrametilpiperidina; TMS: trimetilsililo; Tol: tolil; trifos: bis(difenilfosfinoetil)fenilfosfina; Ts: 4-toluenossulfonil (tosil).
Lanthanide complexes – Chiral detection of biomolecules
2019, Coordination Chemical Evaluations
Quote Excerpt:
Lanthanides play a crucial role in various fields such as organic and bioorganic chemistry [1-5], optical detection technology (i.e. luminescence sensors) [6,7] and in medicine (diagnosis and therapy) [8,9 ] and especially in recent years, medical applications have grown continuously.
Thanks to their dimensional versatility and ability to form complexes, lanthanides are increasingly used for the chiral detection of biomolecules. In this work two detection techniques based on lanthanide coordination chemistry are reviewed in detail. Circular dichroism (CD) spectroscopy explores the coupling or binding of lanthanide complexes with chiral substrates, allowing their detection and study. This method is generally employed for the characterization of large biomolecules, ie DNA, proteins or amino acids, as well as selective detection and recognition of anions. Circular polarized luminescence (CPL) can be efficiently employed for the detection of biological molecules when lanthanides are used as probes. Indeed, their complexes are of great interest because their emission spectra may contain information about the symmetry and composition of biomolecules.
Intermediates in Lewis acid catalysis with lanthanide triflates
2019, European Journal of Organic Chemistry
Lanthanide triflates are effective Lewis acid catalysts in reactions involving carbonyl compounds due to their high oxophilicity and stability in water. Despite the growing interest, the identity of the catalytic species formed in reactions catalyzed by lanthanides is still unknown. Therefore, we used mass spectrometry and ion spectroscopy to intercept and characterize the intermediates in a reaction catalyzed by ytterbium and dysprosium triflates. We were able to identify several lanthanide intermediates formed in a simple condensation reaction between a C-acid and an aldehyde. The results show a correlation between the reactivity of the lanthanide complexes and their state of charge and suggest that the triple-charged complexes play a key role in the reactions catalyzed by lanthanides. Spectroscopic data of gaseous ions accompanied by theoretical calculations reveal that the difference between the catalytic efficiencies of ytterbium and dysprosium ions can be explained by their different electrophilicities.
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Polyhedron, Volume 160, 2019, pp. 180-188
New lanthanide complexes with thetrans-Py disubstituted macrocyclic ligand2[18] Anne N.6(denoted aseu1) were successfully synthesized. The coordination properties of the compoundeu1for different lanthanide metal ions (Ln=La–Yb, except Lu) were explored, and structural studies were performed both in solid state and in aqueous solution. In all cases, complexes with a metal:binder molar ratio of 1:1 were obtained. The crystal structures of the following compounds: [H4eu1](NO3)4, [Whoeu1(NO3)2](NO3) e [Smeu1(NO3)2](NO3) were characterized by single-crystal X-ray diffraction. In both complexes, the asymmetric unit contains the cation complex [Lneu1(NO3)2]+(Ln=Ce3+, Sm3+) consisting of a mononuclear endomacrocyclic backbone, while the ten coordination environments are completed by two bidentate nitrate ions. The two five-membered chelate rings formed by the ethylenediamine moieties adopt (δδ) [or (λλ)] conformations and also showC2symmetry (as observed in solution by NMR).
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Lanthanide(III) and yttrium(III) coordination compounds of diastereomeric (2+2) macrocyclic imines derived from 2,6-diformylpyridine and trans-1,2-diaminocyclopentane
Polyhedron, Volume 147, 2018, pp. 15-25
The enantiopure mononuclear coordination compounds [Ln(L1)]Cl3·nH2O (Ln=Y(III), Nd(III), Sm(III), Eu(III), Tb(III), Yb(III)) of chiral (2+2) macrocyclic imineL1(L1RRRReL1SSSS), derived from (1R,2R) e 1S,2S)-1,2-diaminocyclopentane (DACP) and 2,6-diformylpyridine (DFP), were synthesized in the modeled condensation of the precursors in the presence of the appropriate metal salts. of the racemictrans-DACP and DFP in patterned condensation, a series of racemic mononuclear coordination compounds [Ln(L1rac)]Cl3·nH2O (Ln=Y(III), Nd(III), Sm(III), Eu(III), Tb(III), Yb(III)) were obtained. In the absence of metal salt, condensation of achiral precursors leads to amesobasic Schiff typeL2, which in the presence of lanthanide(III) salts produced the mononuclear coordination compounds [Ln(L2)]Cl3·nH2O (Ln=Y(III), Nd(III), Sm(III), Eu(III), Tb(III)). Mononuclear coordination compounds withL1eL2ligands were characterized by NMR spectroscopy, mass spectrometry, elemental analysis and/or circular dichroism (CD).1CDCl H NMR Signals3/CD3The OD solutions of the Y(III), Nd(III), Sm(III) and Eu(III) coordination compounds were assigned based on their COSY and HMQC spectra, and for the other lanthanide coordination compounds (Tb(III) and Yb(III)), signals were tentatively assigned based on linewidth analyses. The properties and stability of the lanthanide(III) and yttrium(II) coordination compounds of the racemic macrocycleL1racwere compared with the isomersmesotype macrocycleL2in organic solvents and water. The axial exchange of ligands for various coordination compounds was investigated by1H NMR titration experiments in organic solvents. The X-ray crystal structures of representative mononuclear coordination compounds [Nd(L1RRRR)Cl(H2O)2]Cl2·0,5MeOH·H2Ah, [Nd(L1rac)Cl(H2O)2]Cl21,6MeOH 0,2H2OR AND(L1rac)Cl(H2O)2]Cl23,5H2OR AND(L1rac)Cl(H2O)2][Y(L1rac)(H2O)3]Cl56,8H2O e [Nd(L2)Cl2(H2O)]Cl with the diastereomeric ligandsL1eL2have been determined.
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Bis(4-methylpiperidinyl)-phenylphosphine and bis(4-benzylpiperidinyl)-phenylphosphine: Synthesis, derivatization, molybdenum complexes and DFT calculations
Polyhedron, Volume 68, 2014, pp. 103-111
PhP(NR) functionalized bis(amino)phosphines2)2were synthesized by PhPCl treatment2with 4-methylpiperidine or 4-benzylpiperidine. The ligands react with aqueous hydrogen peroxide, elemental sulfur or selenium to give the corresponding chalcogenides in good yield. Molybdenum complexes of bis(amino)phosphines were obtained. All compounds were obtained in good yields and were characterized by IR, NMR and elemental analysis. Quantum chemical calculations such as HOMO-LUMO energies, Mulliken charges, etc., were performed using B3LYP/6-31G(d,p), a version of the DFT method with the standardgaussiano09 software package program for bis(amino)phosphines and their chalcogenides. The experimental and theoretical results show that PPh(NC5H9CH3)2(1) e PPh(NC5H9CH2C6H5)2(2) are strong σ donors and have similar electronic properties.
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Carboxylates of Rare Earth Elements
Coordination Chemistry Reviews, Volume 340, 2017, pp. 98-133
Rare earth carboxylates constitute a huge group of compounds with various structures and properties. The carboxylate group can be attached to metal cations in several ways. The structural aspects of the coordination modes are presented and discussed from a statistical point of view and the most typical groups of carboxylate complexes are reviewed. Data referring to the thermodynamics of lanthanide formation, mainly Eu(III) complexes, were aggregated and briefly analyzed. Electron spectroscopy of lanthanide carboxylates, mainly focused on the analysis of hypersensitive transitions, is discussed for simple carboxylates, acyclic aminopolycarboxylates and dipicolinates, as exemplary systems.
Research Article
6+6 Macrocycles derived from 2,6-diformylpyridine and trans-1,2-diaminocyclohexane
Tetrahedron Letters, Volume 59, Issue 41, 2018, pp. 3669-3673
While the unmodeled reaction of the racemictrans-1,2-diaminocyclohexane with 2,6-diformylpyridine leads to a mixture of 2+2 and 4+4 macrocyclic imines, reaction of the isolated 2+2 macrocycle with cadmium(II) chloride results in the fusion of three smaller macrocyclic units in a big 6+6 macrocycle. X-ray molecular structures of the hexanuclear cadmium complex of this macrocycle, as well as the derived 6+6 protonated amine, reveal multifold macrocycles that adopt container-like conformations.
Research Article
Lanthanide(III) and yttrium(III) nitrate monomeric and dimeric coordination compounds of the macrocycle (2+2) imine derivatives of 2,6-diformylpyridine and trans-1,2-diaminocyclopentane
Polyhedron, Volume 181, 2020, Article 114433
Monomeric coordination compounds of nitrate [Ln(L1)](NO3)3·nH2O (Ln=Y(III), Tm(III), Yb(III) and Lu(III)); n=0, 0.75 or 3)1of the chiral macrocyclic imine (2+2)L1(L1RRRR,L1SSSSand/orL1rac), derived from enantiomerically pure or racemictrans-1,2-diaminocyclopentane (DACP) and 2,6-diformylpyridine (DFP) were synthesized in modeled condensation of precursors in the presence of appropriate metal salts. From these monomers, their homochiral μ-hydroxodimers [Ln2(L1)2(μ-OH)2](NO3)4·nH2O (Ln=Y(III), Tm(III), Yb(III) and Lu(III)); n=4, 5 or 7) were obtained and isolated by adding NaOH to the respective monomeric form of the coordination compound solution. All synthesized coordination compounds were characterized by NMR spectroscopy, mass spectrometry, elemental analysis and/or circular dichroism (CD).1CDCl H NMR Signals3/CD3The OD solutions of the diamagnetic monomers Y(III) and Lu(III) were assigned based on their COSY and HMQC spectra, and for the other paramagnetic lanthanide coordination compounds (Tm(III) and Yb(III)) the signals were assigned tentatively based on analysis of line widths.1H NMR signals from D2The diamagnetic solutions of Y(III) and Lu(III) representatives of dimeric species were established taking into account their COSY, HMQC, HMBC and NOESY spectra. The NOESY spectra confirm that the dimer structure observed in solids is also maintained in solution.
The axial exchange of ligands in all monomeric coordination compounds was investigated by1H NMR titration experiments with acetate and chloride anions in organic solvents, as well as with hydroxide anion in D2O. The formation of heterobimetallic homochiral μ-hydroxodimers [Ln'Ln"(L1)2(μ-OH)2](NO3)4was investigated in a solution by mixing the solutions of two different [Ln'2(L1)2(μ-OH)2](NO3)4·nH2Are you [Ln"2(L1)2(μ-OH)2](NO3)4·nH2The homochiral homobimetallic precursors. This experiment proves chiral recognition between two macrocyclic units of the same chirality in a solution. The μ-hydroxydimers can convert with time to the corresponding peroxo-dimers of the general formula [Ln2(L1)2(no2: o2-O2)](NO3)4.
The X-ray crystal structures of representative monomeric and dimeric coordination compounds [Yb(L1RRRR)(NO3)2]NO3, [Yb2(L1SSSS)2(OH)2(H2O)2](NO3)42MeOH2H2O, [Yb2(L1RRRR)2(OH)2(H2O)2][Yb2(L1SSSS)2(OH)2(H2O)2](NO3)81,5MeOH 5H2OR and [AND2(L1SSSS)2(O2)(NO3)2](NO3)2·2MeOH with enantiomerically pure or racemic ligandL1have been determined. The structure of [Yb2(L1RRRR)2(OH)2(H2O)2][Yb2(L1SSSS)2(OH)2(H2O)2] (NO3)81,5MeOH 5H2The crystal confirms the chiral recognition of macrocyclic units of the same chirality in solids.
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