Synthesis and Reactivity of the Rare-Earth Metal Complexes Bearing the Indol-2-yl-Based NCN Pincer Ligand.

The pincer rare-earth dialkyl complexes [-RE(CHSiMe) (RE = Lu(), Yb(), Er(), Y(), Dy())] with the indol-2-yl-based NCN pincer ligand were synthesized by the reactions of the proligand ( = 1-MeNCHCH-3-(2-PrCHN═CH)CHN) with RE(CHSiMe)(THF). These complexes exhibited a variety of reactivities toward organic compounds such as amines, triphenylphosphine ylide, -phenylimidazole, pyridine derivatives, and -carborane leading to -bond metathesis, migration insertion, and redox reaction products. The reactions of the dialkyl rare-earth metal complexes with -carborane afforded the novel NCN pincer-ligated carboryne-based metallacyclopropanes which reacted with diphenyl ketone to give insertion products of the RE-C and one of the RE-C bonds, while the reaction of the carboryne-based metallacyclopropanes with diphenyldiazomethane produced the di--metallacyclopentanes via the insertions of the N═N bond of the diphenyldiazomethane into two RE-C bonds and the RE-C bond.

Reactivity of Rare Earth Metal Alkyl Complexes with Nitriles or Isonitrile: Versatile Ways toward Multiply Functionalized β-Diketiminato, (Iso)indolyl, and Imidazolyl Chelating Rare Earth Metal Complexes.

The reactivity of the rare earth metal alkyl complexes RE(CHSiMe)(THF) () [RE = Y (), Yb (), Lu (); = 2,5-[(2-pyrrolyl)CPh](-methylpyrrole)] with various nitriles and isonitriles has been fully developed. Treatment of the yttrium monoalkyl complex () with 2 equiv of aromatic nitriles afforded the symmetric trisubstituted β-diketiminato yttrium complexes (, , and through successive cyano group insertion into the RE-C bond and 1,3-H shift or the unsymmetric trisubstituted β-diketiminato yttrium complex () unexpectedly via a 1,3-SiMe shift when 4-(trifluoromethyl)benzonitrile was used in this reaction under the same conditions. By treating with 2 equiv of tolyl acetonitrile, an activation of the C-H bond occurred to form the corresponding β-aryl keteniminato complexes and .

Synthesis and catalytic activity of tetradentate β-diketiminato rare-earth metal monoalkyl complexes in tandem Oppenauer oxidation and cross-aldol condensation.

A series of unsymmetric tetradentate β-diketiminato rare-earth metal monoalkyl complexes were synthesized, and their catalytic behavior has been well developed. Indole-incorporated β-diketiminato proligands HL (L = MeC(NDipp)CHC(Me)NCHCH-3-(1-R-CHN), R = CH-(2-CHO), L1; R = (CH)OMe, L2; Dipp = 2,6-PrCH) were prepared by the reaction of an arylamino-enone with 1-substituted-tryptamine in good yields. Treatment of the proligands with the rare-earth metal trialkyl complexes RE(CHSiMe)(THF) generated the corresponding unsymmetric ,,,-tetradentate β-diketiminato rare-earth metal monoalkyl complexes LRE(CHSiMe) (L1, RE = Y (1a), Gd (1b), Yb (1c), Lu (1d); L2, RE = Y (2a), Gd (2b), Yb (2c), and Lu(2d)).

Aryl C-H bond functionalization with diphenyldiazomethane induced by rare-earth metal alkyl complexes.

The first examples of regioselective aryl -C-H functionalization with diphenyldiazomethane for the construction of C-N bonds were accomplished the activation of C-H bonds and the subsequent reaction of diphenyldiazomethane with the RE-C bond. The reactions of rare-earth metal monoalkyl complexes LRE(CHSiMe)(THF) (L = 2,5-[(2-pyrrolyl)CPh](-Me-pyrrole)) supported by a neutral -methylpyrrole anchored dipyrrolyl ligand with 2 equiv. of PhCN gave irreversibly unprecedented hydrazonato-functionalized imino rare-earth metal complexes LRE(PhCNNCH-(-CNHPh) (RE = Y (2a), Lu (2a')) in good yields involving a rather complex process including the interaction of a diazo unit with a RE-C bond, a β-H elimination, a N-N cleavage, 1,4-hydrogen transfer and the subsequent C-N coupling with another diphenyldiazomethane.

Rare-Earth Metal Complexes Supported by 1,3-Functionalized Indolyl-Based Ligands for Efficient Hydrosilylation of Alkenes.

Two different 1,3-functionalized indolyl-based proligands 1-(2-CHO)CH-3-(2-BuCHN═CH)CHN () and 1-MeNCHCH-3-(2-PrCHN═CH)CHN () were designed, prepared in high yields, and successfully applied to rare-earth metal chemistry showing different reactivities and different bondings with the central metals. The reactions of with RE(CHSiMe)(THF) provided two types of rare-earth metal complexes: the pincer type mononuclear complexes κ-()RE(CHSiMe) [ = 1-(2-CHO)CH-3-(2-BuCHN═CH)CHN, RE = Lu(), Yb()], and the dinuclear rare-earth metal alkyl (per alkyl/per metal) complexes having the ligand in novel coordination modes {(η:(μ-η:η):η-1-(2-CHO)CH-3-[2-BuCHNCH-(CHSiMe)]CHN)RECHSiMe} [RE = Er(), Y(), Dy(), and Gd()]. Meanwhile, the reactions of with RE(CHSiMe)(THF) led to the isolation and characterization of only the mononuclear rare-earth metal dialkyl complexes κ-()RE(CHSiMe) [ = 1-MeNCHCH-3-(2-PrCHN═CH)CHN, RE = Lu(), Gd()] bearing the ligand in the pincer chelate form.

Indolyl-based Copper(I) Complex-Catalyzed Intermolecular Trifluoromethylazolation of Alkenes via Radical Process.

Herein, we synthesized and characterized a binuclear copper(I) complex supported by the indolyl-based ligand. Employing this complex as catalyst, we have developed a three-component intermolecular trifluoromethylazolation of alkenes to deliver various trifluoromethylated azole derivatives. The method features exclusive chemo- and regioselectivity, a broad scope of alkenes and oxazoles, thiazoles, and good tolerance of functional groups under mild conditions.

Synthesis of rare-earth metal complexes with a morpholine-functionalized β-diketiminato ligand and their catalytic activities towards C-O and C-N bond formation.

Unusual tridentate β-diketiminato rare-earth metal chlorides LRECl(μ-Cl)Li(THF) (RE = Y (1a), Yb (1b), and Lu (1c); L = MeC(NDipp)CHC(Me)N(CH)NCHO; Dipp = 2,6-PrCH) and the corresponding dialkyl complexes LRE(CHSiMe) (RE = Y (2a), Yb (2b), and Lu (2c)) were prepared by reaction of a morpholine-functionalized β-diketiminato proligand HL with anhydrous RECl and rare-earth metal trialkyl complexes RE(CHSiMe)(THF), respectively. In 1 and 2, the morpholine moiety displayed a stable chair conformation and the resulting ligand coordinated to the rare-earth metal ion in a [NNN]-tridentate chelating fashion. Further studies demonstrated that these dialkyl complexes showed high activity towards the catalytic formation of C-O and C-N bonds in the alcoholysis of isothiocyanates and aminolysis of epoxides.

Rare-Earth-Metal-Complex-Catalyzed Hydroalkoxylation and Tandem Hydroalkoxylation/Cyclohydroamination of Isocyanates: Synthesis of Carbamates and Oxazolidinones.

Novel N,N,N-tridentate β-diketiminato rare-earth-metal dialkyl complexes RE(CHSiMe) [RE = Y (), Gd (), Yb (), Lu (); = MeC(NDipp)CHC(Me)N(CH)NCH, where Dipp = 2,6-PrCH] have been conveniently synthesized by one step from reactions of the rare-earth-metal trialkyl complexes RE(CHSiMe)(THF) (THF = tetrahydrofuran) with a pyrrolidine-functionalized β-diketiminate H, and their catalytic behaviors toward hydroalkoxylation and tandem hydroalkoxylation/cyclohydroamination of isocyanates have been described. These rare-earth-metal catalysts exhibited high efficiency in the hydroalkoxylation of isocyanates, providing a variety of -alkyl and -aryl carbamate derivatives under mild reaction conditions with a rather low catalyst loading (0.04 mol %).

Synthesis and characterization of rare-earth metallate amido complexes bearing the 2-amidate-functionalized indolyl ligand and their application in the hydroboration of esters with pinacolborane.

The reactions of 2-amidate-functionalized indolyl proligand 2-(2,6-PrCHNHCO)CHNH (HL) with [(MeSi)N]RE(μ-Cl)Li(THF) were studied leading to the synthesis and characterization of a series of novel discrete trinuclear rare-earth metallate amido complexes containing the anion [{η:(μ-η:η):η-LREN(SiMe)}(μ-Cl)] and cation Li(THF) (RE = Y(1a), Nd (1b), Sm (1c), Gd (1d), Dy (1e), Er (1f), and Yb (1g)) in good yields by silylamine elimination. All of the complexes were characterized by spectroscopic methods, elemental analyses and single-crystal X-ray diffraction, and complexes 1a and 1c were additionally characterized by NMR spectroscopy. As proof of principle of their activity, these complexes were used as precatalysts for the hydroboration of esters using HBpin as the hydride source displaying high activity under neat and room temperature conditions.

Transformation of the sp Carbanion to Carbene with Subsequent 1,1-Migratory Insertion and Nucleophilic Substitution in Rare-Earth Metal Chemistry.

The development of Fischer-type electrophilic carbene chemistry with early transition metals has been a great challenge due to the fact that such metals in their high oxidation states lack the d electrons to stabilize the electrophilic carbene. Herein, we disclose the first experimental and theoretical findings of transformation of an sp carbanion to a Fischer-type electrophilic carbene with rare-earth metals in their high oxidation state with a d electron via electron transfer. The carbene may undergo 1,1-migratory insertion into an adjacent RE-C(sp) bond, and an unprecedented ring opening of the indole ring of the ligand occurs when the carbenes undergo nucleophilic substitution with a special organolithium reagent -MeNCHCHLi.

Dehydrogenative Coupling of Terminal Alkynes with O/N-Based Monohydrosilanes Catalyzed by Rare-Earth Metal Complexes.

Newly synthesized rare-earth metal alkyl complexes bearing a tripyrrolyl ligand act as excellent precatalysts for the cross-dehydrogenative coupling between various terminal alkynes and O/N-based monohydrosilanes of HSi(OEt)/HSi(NMe), leading to the formation of a variety of alkoxysilylalkyne and aminosilylalkyne derivatives in good to high yields. The precatalysts RE(CHSiMe)(thf) (RE = Y(), Er(), Yb(), = 2,5-[(2-CHN)CPh](CHNMe), thf = tetrahydrofuran) were easily prepared in high yields via the reactions of RE(CHSiMe)(thf) with the proligand H in a single step. Mechanistic studies reveal that treatment of with phenylacetylene could generate the active catalytic species: dinuclear rare-earth metal alkynides ((thf)[RE(μ-C≡CPh)]) (RE = Y(), = 1; Yb(), = 0), which could react with HSi(OEt) to produce the coupling product and the dinuclear rare-earth metal hydrides ( (thf)[RE(μ-H)]) (RE = Y(); Yb()).

Syntheses of Dianionic α-Iminopyridine Rare-Earth Metal Complexes and Their Catalytic Acitivities toward Dehydrogenative Coupling of Amines with Hydrosilanes.

Reactions of [(MeSi)N]RE(μ-Cl)Li(THF) with aminomethylene-substituted pyridine 2-[O(CHCH)NCHCHNCH]CHN () gave the dianionic α-iminopyridine rare-earth metal amido complexes {μ-η:σ:κ:κ-2-[O(CHCH)NCHCHNCH]CHN}RE[N(SiMe)] (RE = Y(), La(), Pr(), Nd(), Sm(), Dy(), Er(), and Lu ()). However, reaction of [(MeSi)N]Y(μ-Cl)Li(THF) with pyridin-2-ylmethyl-substituted amines such as 2-(RNHCH)CHN (R = Bu () and 2,6-PrPh ()) or benzyl-substituted amine O(CHCH)NCHCHNHCHCH () afforded the corresponding yttrium complexes containing monoanionic ligands [2-(RNCH)CHN]YN(SiMe) (R = Bu () and 2,6-PrPh ()) or [O(CHCH)NCHCHNCHCH][(MeSi)N)]Y(μ-Cl)(μ-η-O(CHCH)NCHCHNCHCH)Li(THF) (). Dianionic α-iminopyridine rare-earth metal amido complexes showed high catalytic activities for the dehydrogenation coupling reaction of hydrosilanes and amines providing a variety of silylamines in high yields.

Aluminum complexes with Schiff base bridged bis(indolyl) ligands: synthesis, structure, and catalytic activity for polymerization of rac-lactide.

A series of Schiff base bridged bis(indolyl) ligands were developed for aluminum chemistry. The reactions of AlEt3 or AlMe3 with the Schiff base bridged bis(indolyl) proligands R1(-N[double bond, length as m-dash]CHC8H5NH)2 (R1 = -CH2CH2- (H2L1); -CH2CH2CH2- (H2L2); -CH2CMe2CH2- (H2L3); rac-Cy (H2L4); and R,R-Cy (H2L5)) were studied leading to the synthesis of a series of aluminum alkyl complexes L1AlEt (1)-L5AlEt (5) and L3AlMe (3b) in good yields, while the reaction of H2L3 with Al(OiPr)3 gave the aluminum alkoxide complex L3AlOiPr (3a). These aluminum complexes were characterized by spectroscopic methods and elemental analyses.

Synthesis and characterization of 2-t-butylimino-functionalized indolyl rare-earth metal amido complexes for the catalytic addition of terminal alkynes to carbodiimides: the dimeric complexes with the alkynide species in the μ-η:η bonding modes.

A series of new rare-earth metal amido complexes bearing a 2-t-butylimino-functionalized indolyl ligand were synthesized via dehydrogenation of a secondary amine, and their reactivities and catalytic performances were investigated. The reactions of 2-(BuNHCH)CHNH (1) with rare-earth metal amides [(MeSi)N]RE(μ-Cl)Li(THF) afforded the complexes [2-(BuN[double bond, length as m-dash]CH)CHN]RE[N(SiMe)] (RE = Er (2), Y (3), Dy (4), Sm (5), Nd (6)) containing the bidentate ligand via dehydrogenation of the amine to the imine group. Complexes 2-6 exhibited an excellent catalytic activity for the addition of terminal alkynes to carbodiimides affording a series of corresponding N,N'-dialkyl-propiolamidines.

Synthesis, characterization, and reactivity of dinuclear organo-rare-earth-metal alkyl complexes supported by 2-amidate-functionalized indolyl ligands: substituent effects on coordination and reactivity.

Two series of new dinuclear organo-rare-earth-metal alkyl complexes supported by 2-amidate-functionalized indolyl ligands with different haptic modes were synthesized and characterized. The treatment of [RE(CH2SiMe3)3(THF)2] with 1 equiv. of 2-(2,6-iPr2C6H3NHC[double bond, length as m-dash]O)C8H5NH (H2L1) and 2-(2-tBuC6H4NHC[double bond, length as m-dash]O)C8H5NH (H2L2) in toluene yielded the dinuclear organo-rare-earth-metal alkyl complexes {[η1:(μ2-η1:η1)-L1]RE(CH2SiMe3)(THF)2}2 [RE = Gd (1a), Dy (1b), Y (1c), Er (1d), and Yb (1e)] and {[η1:(μ2-η1:η1):η1-L2]RE(CH2SiMe3)(THF)2}2 [RE = Gd (2a), Dy (2b), Y (2c), Er (2d), and Yb (2e)] in good yields.

Well-Defined Amidate-Functionalized N-Heterocyclic Carbene -Supported Rare-Earth Metal Complexes as Catalysts for Efficient Hydroboration of Unactivated Imines and Nitriles.

Four amidate-functionalized N-heterocyclic carbene (NHC) rare-earth metal amido complexes [(κ-N,O-κ-L)REN(SiMe)] (L = 1-(CHC═ONCHCH)-3-(CH)CH(N(CH)NC)) [RE = Er (1), Y (2), Dy (3), Gd (4)] were synthesized by one-pot reactions of 2 equiv of (1-(CHC═ONHCHCH)-3-(CH)CH-(N(CH)NCH))Br (HLBr) with 5 equiv of KN(SiMe) followed by treatment with 1 equiv of RECl in tetrahydrofuran at -40 °C. These complexes were fully characterized, and their catalytic activities toward hydroboration of unactivated imines and nitriles were investigated, and it was found that these complexes displayed excellent activities as well as remarkable functional group compatibility for imine and nitrile substrates such as halo-, alkyl-, hydroxyl-, N, N-dimethylamino-, and nitro- substituents. Among those, the chemoselectivity for this reaction among the common unsaturated functional groups was achieved in the order C═O ≫ C═N > C≡N > COEt > C═C in the current catalytic system, which may facilitate their further application in synthetic chemistry.

Syntheses, Structures, and Catalytic Activities of the Anionic Heterobimetallic Rare-Earth Metal Complexes Supported by Pyrrolyl-Substituted 1,2-Diimino Ligands.

A series of the anionic heterobimetallic rare-earth metal complexes supported by trans- or chiral pyrrolyl-substituted 1,2-diimino ligands were synthesized in good yields via reactions of [(MeSi)N]RE(μ-Cl)Li(THF) with the corresponding 1,2-diimino proligands. Reactions of [(MeSi)N]RE(μ-Cl)Li(THF) with 2 equiv of trans-1,2-bis(pyrrol-2-ylmethylene)-1,2-diphenylethanediamine (HL) afforded the discrete ion-pair rare-earth metal complexes [Li(THF)][(L)RE] (RE = Sm(5), Dy(6), Er(7)). Reactions of [(MeSi)N]RE(μ-Cl)Li(THF) with 2 equiv of ( R, R)-1,2-bis(pyrrol-2-ylmethylene)-1,2-diphenylethanediamine (HL) gave the heterobimetallic rare-earth metal complexes (L)RELi(THF) (RE = Sm(8), Y(9)).

Versatile reactivities of rare-earth metal dialkyl complexes supported by a neutral pyrrolyl-functionalized β-diketiminato ligand.

Herein, rare-earth metal dialkyl complexes supported by a neutral pyrrolyl-functionalized β-diketiminato ligand with the formula LRE(CHSiMe)(thf) (RE = Y (1a), Dy (1b), Er (1c), Yb (1d); L = MeC(NDipp)CHC(Me)NCHCHNCH-2,5-Me, Dipp = 2,6-PrCH) were synthesized via the reactions of the β-diketimine HL with the rare-earth metal trialkyl complexes RE(CHSiMe)(thf) in high yields. The reactivities of 1 with pyridine derivatives, unsaturated substrates, and elemental sulfur were investigated, and some interesting chemical transformations were observed. Ligand exchange and activation of sp and sp C-H bonds occurred during the reactions with pyridine derivatives to afford different types of mononuclear rare-earth metal pyridyl complexes, namely, LEr(CHSiMe)(η-NCH) (2c), LRE(η-CH-2-NCH-4,6-Me) (RE = Y (3a), Er (3c)), and LRE(CHSiMe)(η-(C,N)-2-(2-CHNCH)) (RE = Er (4c), Yb = (4d)).

Reactivity of 1,3-Disubstituted Indoles with Lithium Compounds: Substituents and Solvents Effects on Coordination and Reactivity of Resulting 1,3-Disubstituted-2-Indolyl Lithium Complexes.

Reactivity of 1,3-disubstituted indolyl compounds with lithium reagents was studied to reveal the substituents and solvent effects on coordination modes and reactivities resulting in different indolyl lithium complexes. Treatment of 1-alkyl-3-imino functionalized compounds 1-R-3-(R'N═CH)CHN [R = Bn, R' = Dipp (HL); R = Bn, R' = Bu (HL); R = CHOCH, R' = Dipp (HL); Dipp = PrCH] with MeSiCHLi or BuLi in hydrocarbon solvents (toluene or n-hexane) produced 1,3-disubstituted-2-indolyl lithium complexes [η:(μ-η:η)-1-Bn-3-(DippN═CH)CHNLi] (1), {[η:(μ-η:η:η)-1-Bn-3-(BuN═CH)CHN][η:η:(μ-η:η)-1-Bn-3-(BuN═CH)CHN][η:(μ-η:η)-1-Bn-3-(BuN═CH)CHN]Li} (2), and [η:η:(μ-η:η)-1-CHOCH-3-(DippN═CH)CHNLi] (3), respectively. The bonding modes of the indolyl ligand were kept in 1 by coordination with donor solvent, affording [η:(μ-η:η)-1-Bn-3-(DippN═CH)CHNLi(THF)] (4).

Di and trinuclear rare-earth metal complexes supported by 3-amido appended indolyl ligands: synthesis, characterization and catalytic activity towards isoprene 1,4-cis polymerization.

Different di and trinuclear rare-earth metal complexes supported by 3-amido appended indolyl ligands were synthesized and their catalytic activities towards isoprene polymerization were investigated. Treatment of [RE(CHSiMe)(thf)] with 1 equiv. of 3-(CyN[double bond, length as m-dash]CH)CHNH in toluene or in THF afforded dinuclear rare-earth metal alkyl complexes having indolyl ligands in different hapticities with central metals {[η:η-μ-η-3-(CyNCH(CHSiMe))Ind]RE-(thf)(CHSiMe)} (Cy = cyclohexyl, Ind = Indolyl, RE = Yb (1), Er (2), Y (3)) or {[η-μ-η-3-(CyNCH(CHSiMe))Ind]RE-(thf)(CHSiMe)} (RE = Yb (4), Er (5), Y (6), Gd (7)), respectively.

Reactivity of functionalized indoles with rare-earth metal amides. Synthesis, characterization and catalytic activity of rare-earth metal complexes incorporating indolyl ligands.

The reactivity of several functionalized indoles 2-(RNHCH2)C8H5NH (R = C6H5 (1), (t)Bu (2), 2,6-(i)Pr2C6H3 (3)) with rare-earth metal amides is described. Reactions of 1 or 2 with [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 (RE = Eu, Yb) respectively produced the europium complexes [2-(C6H5N[double bond, length as m-dash]CH)C8H5N]2Eu[N(SiMe3)2] (4) and [2-((t)BuN[double bond, length as m-dash]CH)C8H5N]Eu[N(SiMe3)2]2 (5), and the ytterbium complex [2-((t)BuN[double bond, length as m-dash]CH)C8H5N]2Yb[N(SiMe3)2] (6), containing bidentate anionic indolyl ligands via dehydrogenation of the amine to the imine. In contrast, reactions of the more sterically bulky indole 3 with [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 afforded complexes [2-(2,6-(i)Pr2C6H3NCH2)C8H5N]RE[N(SiMe3)2](THF)2 (RE = Yb (7), Y (8), Er (9), Dy (10)) with the deprotonated indolyl ligand.

Copper-Catalyzed Electrophilic Amination of Organoaluminum Nucleophiles with O-Benzoyl Hydroxylamines.

A copper-catalyzed electrophilic amination of aryl and heteroaryl aluminums with N,N-dialkyl-O-benzoyl hydroxylamines that affords the corresponding anilines in good yields has been developed. The catalytic reaction proceeds very smoothly under mild conditions and exhibits good substrate scope. Moreover, the developed catalytic system is also well suited for heteroaryl aluminum nucleophiles, providing facile access to heteroaryl amines.

Synthesis and Characterization of Organo-Rare-Earth Metal Monoalkyl Complexes Supported by Carbon σ-Bonded Indolyl Ligands: High Specific Isoprene 1,4-Cis Polymerization Catalysts.

A series of N-protected 3-imino-functionalized indolyl ligands 1-R-3-(R'N═CH)C8H5N [R = Bn, R' = 2,6-(i)Pr2C6H3 (HL(1)); R = CH3, R' = 2,6-(i)Pr2C6H3 (HL(2)); R = Bn, R' = (t)Bu (HL(3))] and 1-CH3-2-(2,6-(i)Pr2C6H3N═CH)C8H5N (HL(4)) was prepared via reactions of N-protected indolyl aldehydes with corresponding amines. The C-H σ-bond metathesis followed by alkane elimination reactions between RE(CH2SiMe3)3(thf)2 and HL(1)-HL(3) afforded the carbon σ-bonded indolyl-ligated rare-earth metal monoalkyl complexes. Reactions of RE(CH2SiMe3)3(thf)2 with 2 equiv of HL(1) or HL(2) gave the carbon σ-bonded indolyl-ligated rare-earth metal monoalkyl complexes L(1)2RECH2SiMe3 (RE = Y(1), Er(2), Dy(3)) and L(2)2RECH2SiMe3 (RE = Y(5), Er(6), Dy(7), Yb(8)), while reaction of Yb(CH2SiMe3)3(thf)2 with 2 equiv of HL(1) afforded the ytterbium dialkyl complex L(1)Yb(CH2SiMe3)2(thf)2 (4).

Dinuclear rare-earth metal alkyl complexes supported by indolyl ligands in μ-η(2) :η(1) :η(1) hapticities and their high catalytic activity for isoprene 1,4-cis-polymerization.

Two series of new dinuclear rare-earth metal alkyl complexes supported by indolyl ligands in novel μ-η(2) :η(1) :η(1) hapticities are synthesized and characterized. Treatment of [RE(CH2 SiMe3 )3 (thf)2 ] with 1 equivalent of 3-(tBuN=CH)C8 H5 NH (L1 ) in THF gives the dinuclear rare-earth metal alkyl complexes trans-[(μ-η(2) :η(1) :η(1) -3-{tBuNCH(CH2 SiMe3 )}Ind)RE(thf)(CH2 SiMe3 )]2 (Ind=indolyl, RE=Y, Dy, or Yb) in good yields. In the process, the indole unit of L1 is deprotonated by the metal alkyl species and the imino C=N group is transferred to the amido group by alkyl CH2 SiMe3 insertion, affording a new dianionic ligand that bridges two metal alkyl units in μ-η(2) :η(1) :η(1) bonding modes, forming the dinuclear rare-earth metal alkyl complexes.

Lewis acid catalyzed cascade reaction to carbazoles and naphthalenes via dehydrative [3 + 3]-annulation.

A novel Lewis acid catalyzed dehydrative [3 + 3]-annulation of readily available benzylic alcohols and propargylic alcohols was developed to give polysubstituted carbazoles and naphthalenes in moderate to good yields with water as the only byproduct. The reaction was presumed to proceed via a cascade process involving Friedel-Crafts-type allenylation, 1,5-hydride shift, 6π-eletrocyclization, and Wagner-Meerwein rearrangement.