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Highlights • Transition-metal-catalyzed C H bond activation has attracted substantial interest in recent years as an efficient, step-economic, and environmentally benign pathway for the synthesis of functional polymers. • The polymerization reaction may proceed through C H/C X cross-coupling, oxidative C H/C H coupling, and C H addition to unsaturated C C bonds. • C H activation may also serve as a chain transfer reaction for olefin polymerization and polymer post-functionalization. This review summarizes recent advances in this area. Abstract Transition-metal-catalyzed C H bond activation has attracted substantial interest in recent years as an efficient, step-economic, and environmentally benign pathway for the synthesis of functional polymers. The polymerization reaction may proceed through C H/C X cross-coupling, oxidative C H/C H coupling, and C H addition to unsaturated C C bonds. C H activation may also serve as a chain transfer reaction for olefin polymerization and polymer post-functionalization. This review summarizes recent advances in this area. [ABSTRACT FROM AUTHOR]

The simultaneous chain-growth and step-growth polymerization of a monomer is of great interest and importance because it can produce unique macromolecules which are difficult to prepare by other means. However, such a transformation is usually difficult to achieve in one polymerization system because chain-growth polymerization and step-growth polymerization proceed by different reaction mechanisms. Reported here is the simultaneous chain-growth and step-growth polymerization of para- and meta-methoxystyrenes catalyzed by half-sandwich rare-earth alkyl complexes, and the step-growth polymerization proceeds by the C−H polyaddition of anisyl units to vinyl groups. This unprecedented transformation affords a new family of macromolecules containing unique alternating anisole-ethylene sequences. In contrast to para- and meta-methoxystyrenes, ortho-methoxystyrene exclusively undergo syndiospecific, living chain-growth polymerization by continuous C=C bond insertion to give perfect syndiotactic poly(ortho-methoxystyrene) with high molecular weight and narrow polydispersity (rrrr >99 %, Mn up to 280 kg mol−1, Mw/Mn <1.10). [ABSTRACT FROM AUTHOR]

The simultaneous chain-growth and step-growth polymerization of a monomer is of great interest and importance because it can produce unique macromolecules which are difficult to prepare by other means. However, such a transformation is usually difficult to achieve in one polymerization system because chain-growth polymerization and step-growth polymerization proceed by different reaction mechanisms. Reported here is the simultaneous chain-growth and step-growth polymerization of para- and meta-methoxystyrenes catalyzed by half-sandwich rare-earth alkyl complexes, and the step-growth polymerization proceeds by the C−H polyaddition of anisyl units to vinyl groups. This unprecedented transformation affords a new family of macromolecules containing unique alternating anisole-ethylene sequences. In contrast to para- and meta-methoxystyrenes, ortho-methoxystyrene exclusively undergo syndiospecific, living chain-growth polymerization by continuous C=C bond insertion to give perfect syndiotactic poly(ortho-methoxystyrene) with high molecular weight and narrow polydispersity (rrrr >99 %, Mn up to 280 kg mol−1, Mw/Mn <1.10). [ABSTRACT FROM AUTHOR]

By use of a half ‐ sandwich scandium dialkyl complex bearing cyclopentadienyl ligand with a phosphine oxide side arm [(C5Me4SiMe2CH2P(O)Ph2)Sc(CH2SiMe3)2] in the presence of [Ph3C][B(C6F5)4], the cyclocopolymerization of 1,6 ‐ heptadiene with styrene has been achieved for the first time to afford a new family of cyclopolyolefins containing a six ‐ membered ring (methylene ‐ 1,3 ‐ cyclohexane), a five ‐ membered ring (ethylene ‐ 1,2 ‐ cyclopentane), and styrene–styrene units. [ABSTRACT FROM AUTHOR]

A series of half-sandwich scandium-dialkyl complexes that bear various auxiliary ligands have been examined for the copolymerization of isoprene (IP) with nonconjugated α,ω-dienes such as 1,5-hexadiene (HD) and 1,6-heptadiene (HPD). Significant ligand influence on the catalytic activity and selectivity has been observed. The thf-coordinated complex [(C5Me4SiMe3)Sc(CH2SiMe3)2(thf)] ( 2) and the methoxy side arm containing the half-sandwich complex [(C5Me4C6H4OMe- o)Sc(CH2SiMe3)2] ( 3), in combination with an equivalent of [Ph3C][B(C6F5)4], can serve as excellent catalysts for the random cyclocopolymerizations of IP with HD and HPD. The resulting random HD-IP copolymers contain five-membered-ring methylene-1,3-cyclopentane (MCP), 3,4-polyisoprene (3,4-IP), and 1,4-polyisoprene (1,4-IP) units with controllable HD incorporation in a range of 17-82 mol %. The random HPD-IP copolymers possess six-membered-ring methylene-1,3-cyclohexane (MCH), 1,4-IP, and 3,4-IP units with HPD incorporation in a range of 11-55 mol %. By use of a catalyst that bears a phosphine oxide group [{C5Me4SiMe2CH2P(O)Ph2}Sc(CH2SiMe3)2] ( 5), the alternating copolymerizations of IP with HD and HPD have been achieved for the first time in which HD and HPD are completely cyclized to the MCP and MCH units, respectively. More remarkably, in the alternating copolymerization of HPD and IP by 5, the regio- and stereospecific cis-MCH selectivity reached as high as 99 %. The microstructures and compositions of these copolymers showed significant influences on their mechanical properties. [ABSTRACT FROM AUTHOR]

We report the hydrogenolysis andprotonation reactions of a tetrametalliclutetium tetramethylidene complex [Cp′Lu(μ3-CH2)]4(Cp′ = C5Me4SiMe3) (1) and a trimetallic lutetium hexamethylcomplex [Cp′Lu(μ2-CH3)2]3(2) with H2and ammonium boratecompounds. The hydrogenolysis of 1with H2afforded the corresponding tetrahydride tetramethyl complex [Cp′4Lu4(μ4-H)(μ3-H)(μ2-H)2(μ2-Me)4] (3) in 87% yield. In this transformation, each of the four[Lu-μ2-CH2] methylidene groups in 1reacted with one molecule of H2to give a mixedmethyl/hydride “Lu(H)CH3” unit. The reactionof 1with [PhMe2NH][B(C6F5)4] gave the cationic tetrametallic lutetium monomethyltrimethylidene complex [Cp′4Lu4(μ3-CH2)3(μ3-CH3)][B(C6F5)4] (4) in85% yield, through protonation of one of the four methylidene unitsin 1with the anilinium borate. In contrast, the reactionof the trimetallic hexamethyl complex 2with H2led to formation of a tetrametallic lutetium monohydride heptamethylcomplex [Cp′4Lu4(μ4-H)(μ3-Me)(μ2-Me)6] (5)in 65% yield, while the protonation reaction of 2with3 equiv of [Et3NH][BPh4] gave a monometalliclutetium monomethyl contact-ion-pair complex [Cp′LuMe(η6-Ph)(η1-Ph)BPh2] (6) in 81% yield. Complexes 3–6werefully characterized by 1H and 13C NMR, single-crystalX-ray diffraction, and micro elemental analyses. [ABSTRACT FROM AUTHOR]

The reactivity of the cubane-type rare-earth methylidene complex [Cp′Lu(μ3-CH2)]4 ( 1, Cp′=C5Me4SiMe3) with various unsaturated electrophiles was investigated. The reaction of 1 with CO (1 atm) at room temperature gave the bis(ketene dianion)/dimethylidene complex [Cp′4Lu4(μ3-CH2)2(μ3,η2-O-CCH2)2] ( 2) in 86 % yield through the insertion of two molecules of CO into two of the four lutetium-methylidene units. In the reaction with the sterically demanding N, N-diisopropylcarbodiimide at 60 °C, only one of the four methylidene units in 1 reacted with one molecule of the carbodiimide substrate to give the mono(ethylene diamido)/trimethylidene complex [Cp′4Lu4(μ3-CH2)3{ iPrNC(=CH2)N iPr}] ( 3) in 83 % yield. Similarly, the reaction of 1 with phenyl isothiocyanate gave the ethylene amido thiolate/trimethylidene complex [Cp′4Lu4(μ3-CH2)3{PhNC(S)=CH2}] ( 4). In the case of phenyl isocyanate, two of the four methylidene units in 1 reacted with four molecules of the substrate at ambient temperature to give the malonodiimidate/dimethylidene complex [Cp′4Lu4(μ3-CH2)2{PhN=C(O)CH2(O)CNPh}2] ( 5) in 87 % yield. In this reaction, each of the two lutetium-methylidene bonds per methylidene unit inserted one molecule of phenyl isocyanate. All the products have been fully characterized by NMR spectroscopy, X-ray diffraction, and microelemental analyses. [ABSTRACT FROM AUTHOR]

This Review gives an overview on recent progress in the synthesis and chemistry of rare-earth metal dialkyl complexes bearing monoanionic ancillary ligands, with an emphasis on novel polymerization catalysts. These structurally well-defined and highly reactive compounds are prepared either by alkane elimination reactions between trialkyl rare-earth complexes and acidic neutral ligands, or by the metathetical reactions of rare-earth trihalides with the alkali metal salts of the corresponding ligands. On treatment with an appropriate borate compound, the dialkyl complexes are converted into the corresponding cationic monoalkyl species, which serve as excellent catalysts for the polymerization and copolymerization of a variety of olefins to yield a series of new polymer materials that exhibit novel properties. Alternatively, hydrogenation of the dialkyl rare-earth complexes with H2 affords a new class of rare-earth polyhydride complexes with unique features in terms of both their structure and reactivity. [ABSTRACT FROM AUTHOR]

Abstract: Our single-crystal neutron diffraction results unambiguously reveal a four-coordinate H atom located in the center of a soluble organometallic tetrahedral complex [Li(THF)4][(C5Me4SiMe3)4Dy4(μ-Cl)(μ-H)8]. The core of the molecule consists of a tetranuclear cluster with one interstitial, two face-bridging and five edge-bridging hydride ligands. The four Dy–H distances to the interstitial hydride ligand are 2.249(9), 2.255(9), 2.157(12) and 2.160(12)Ǻ. The compound was prepared via the reaction of [(C5Me4SiMe3)4Dy4(μ-H)8(THF)2] with LiCl. Neutron data collected on a 3mm3 pale-yellow single crystal on the Quasi-Laue diffractometer VIVALDI at I.L.L. (Grenoble) which gave an agreement factor R =10.1% in the final structure refinement against 6947 reflections. The existence of a four-coordinate hydrogen reinforces previous results observed with a series of high-connectivity hydride ligands located at the interstitial cavities of molecular clusters. Interestingly, this structure allows us to analyze simultaneously three different types of hydride coordination in the same molecule (M2(μ2-H), M3(μ3-H), and M4(μ4-H)). [Copyright &y& Elsevier]

Abstract: The reaction of Ln(CH2SiMe3)3(thf)2 with 1 equiv. of the amine ligand 2,6- i Pr2C6H3NH(SiMe3) gave the corresponding amido-ligated rare earth metal bis(alkyl) complexes [2,6- i Pr2C6H3N(SiMe3)]Ln(CH2SiMe3)2(thf) (Ln=Sc (1), Y (2), Ho (3), Lu (4)), which represent rare examples of bis(alkyl) rare earth metal complexes bearing a monodentate anionic ancillary ligand. In the case of Gd, a similar reaction gave the bimetallic complex Gd2(μ-CH2SiMe2NC6H3 i Pr2-2,6)3(thf)3 (5) through intramolecular C–H activation of a methyl group of Me3Si on the amido ligand by Gd–CH2SiMe3 and the subsequent ligand redistribution. Complexes 1–5 were structurally characterized by X-ray analyses. On treatment with 1 equiv of [Ph3C][B(C6F5)4] in toluene at room temperature, complexes 1–4 showed high activity for the living polymerization of isoprene. The 1/[Ph3C][B(C6F5)4] system showed high activity also for the polymerization of 1-hexene and styrene. [Copyright &y& Elsevier]

A series of silylene-linked cyclopentadienyl-phosphido rare earth alkyl and hydride complexes of type Me2Si(C5Me4)(PR′)LnR (Ln=Y, Yb, Lu; R′=Ph, Cy, C6H2tBu3-2,4,6; R=CH2SiMe3, H) have been synthesized and structurally characterized, and their activity in ethylene polymerization and olefin hydrosilylation has been studied. These complexes represent the first examples of rare earth alkyl and hydride complexes bearing cyclopentadienyl-phosphido ligands, which are in sharp contrast both structurally and chemically with the analogous cyclopentadienyl-amido and metallocene complexes. [Copyright &y& Elsevier]

The creation of self‐healing polymers from commodity olefins is of great interest and importance but has remained a challenge to date. We report here for the first time the synthesis of self‐healing polymers by catalyst‐controlled polymerization of a simple commodity diene, isoprene. We found that polyisoprenes having an appropriate mixture (ca. 70/30) of 3,4‐ and cis‐1,4‐microstructures synthesized by using a half‐sandwich scandium catalyst could act as excellent self‐healing elastomers without any external intervention. The unprecedented self‐healability could be ascribed to nanoscale heterogeneities formed by microphase separation of the relatively hard 3,4‐segments from a flexible cis‐1,4‐segment matrix. The hydrogenated polyisoprenes (without C=C bonds) with the analogous microstructures also exhibited excellent mechanical and self‐healing properties, further demonstrating that even simple polyolefins can be made self‐healable if the microstructures are appropriately regulated. [ABSTRACT FROM AUTHOR]

The creation of self‐healing polymers from commodity olefins is of great interest and importance but has remained a challenge to date. We report here for the first time the synthesis of self‐healing polymers by catalyst‐controlled polymerization of a simple commodity diene, isoprene. We found that polyisoprenes having an appropriate mixture (ca. 70/30) of 3,4‐ and cis‐1,4‐microstructures synthesized by using a half‐sandwich scandium catalyst could act as excellent self‐healing elastomers without any external intervention. The unprecedented self‐healability could be ascribed to nanoscale heterogeneities formed by microphase separation of the relatively hard 3,4‐segments from a flexible cis‐1,4‐segment matrix. The hydrogenated polyisoprenes (without C=C bonds) with the analogous microstructures also exhibited excellent mechanical and self‐healing properties, further demonstrating that even simple polyolefins can be made self‐healable if the microstructures are appropriately regulated. [ABSTRACT FROM AUTHOR]

Presents the study on the assembly of a macrocyclic molecules from 4,4'-diaminodiphenylmethane and pentacoordinated copper(II) ions. Assembly of two-dimensional maze-type network through hydrogen bonds; Formation of two-dimensional network layers via hydrogen bonds; Assembly of supramolecular architecture by bidentate oligoanilines.

The ortho-selective benzylic C(sp3)–H alkenylation of 2-methyl tertiary anilines with internal alkynes has been achieved for the first time by using a half-sandwich scandium catalyst. This protocol provides a straightforward route for the synthesis of a new family of 2-allylaniline derivatives, featuring broad substrate scope, 100% atom-efficiency, high yields, and high chemo-, regio-, and stereoselectivity. [ABSTRACT FROM AUTHOR]

Half‐sandwich rare‐earth dialkynyl complexes are of much interest in both structure and reactivity but have remained much underexplored to date. Here we report the synthesis and transformation of a new family of half‐sandwich dialkynyl complexes bearing the C5Me4SiMe3 ligand, which exhibited diverse structural features depending on metal ion size, alkyne substituent and with or without THF coordination. The acid‐base reactions between half‐sandwich rare earth dialkyl complexes (C5Me4SiMe3)Ln(CH2SiMe3)2(THF) (Ln=Sc, Y, Lu) and two equivalents of terminal alkynes such as phenylacetylene and trimethylsilylacetylene in THF generally gave the corresponding THF‐coordinated monomeric rare earth dialkynyl complexes, which upon recrystallization from toluene yielded further aggregated alkynyl complexes with partial or full dissociation of the THF ligands. In the case of phenylacetylene, trimeric yttrium and lutetium hexaalkynyl complexes were formed, in which each pair of the metal atoms was bridged by two alkynyl ligands in solid state but the alkynyl ligands underwent rapid site exchange in toluene solution. In the case of trimethylsilylacetylene with yttrium and lutetium, dimeric tetraalkynyl complexes bearing two terminal and two bridging alkynyl ligands were obtained from toluene. In contrast, recrystallization of the scandium trimethylsilylacetylide complex from toluene induced alkynyl coupling and yielded dimeric scandium complex with one butatrienediyl and two alkynyl bridging ligands. Upon dissolution in THF, all the aggregated alkynyl/butatrienediyl complexes were rapidly reconverted to the monomeric dialkynyl complexes as a result of THF coordination to the rare earth metal atoms. [ABSTRACT FROM AUTHOR]

The search for efficient and selective methods for the divergent synthesis of multi‐substituted aminotetralins is of much interest and importance. We report herein for the first time the diastereoselective [4+2] annulation of 2‐methyl aromatic aldimines with alkenes via benzylic C(sp3)−H activation by half‐sandwich rare‐earth catalysts, which constitutes an efficient route for the divergent synthesis of both trans and cis diastereoisomers of multi‐substituted 1‐aminotetralin derivatives from readily accessible aldimines and alkenes. The use of a scandium catalyst bearing a sterically demanding cyclopentadienyl ligand such as C5Me4SiMe3 or C5Me5 exclusively afforded the trans‐selective annulation products in the reaction of aldimines with styrenes and aliphatic alkenes. In contrast, the analogous yttrium catalyst, whose metal ion size is larger than that of scandium, yielded the cis‐selective annulation products. This protocol features 100 % atom‐efficiency, excellent diastereoselectivity, broad substrate scope, and good functional group compatibility. The reaction mechanisms have been elucidated by kinetic isotope effect (KIE) experiments and the isolation and transformations of some key reaction intermediates. [ABSTRACT FROM AUTHOR]

The search for efficient and selective methods for the divergent synthesis of multi‐substituted aminotetralins is of much interest and importance. We report herein for the first time the diastereoselective [4+2] annulation of 2‐methyl aromatic aldimines with alkenes via benzylic C(sp3)−H activation by half‐sandwich rare‐earth catalysts, which constitutes an efficient route for the divergent synthesis of both trans and cis diastereoisomers of multi‐substituted 1‐aminotetralin derivatives from readily accessible aldimines and alkenes. The use of a scandium catalyst bearing a sterically demanding cyclopentadienyl ligand such as C5Me4SiMe3 or C5Me5 exclusively afforded the trans‐selective annulation products in the reaction of aldimines with styrenes and aliphatic alkenes. In contrast, the analogous yttrium catalyst, whose metal ion size is larger than that of scandium, yielded the cis‐selective annulation products. This protocol features 100 % atom‐efficiency, excellent diastereoselectivity, broad substrate scope, and good functional group compatibility. The reaction mechanisms have been elucidated by kinetic isotope effect (KIE) experiments and the isolation and transformations of some key reaction intermediates. [ABSTRACT FROM AUTHOR]

The asymmetric hydrophosphination of cyclopropenes with phosphines is of much interest and importance, but has remained hardly explored to date probably because of the lack of suitable catalysts. We report here the diastereo‐ and enantioselective hydrophosphination of 3,3‐disubstituted cyclopropenes with phosphines by a chiral lanthanocene catalyst bearing the C2‐symmetric 5,6‐dioxy‐4,7‐trans‐dialkyl‐substituted tetrahydroindenyl ligands. This protocol offers a selective and efficient route for the synthesis of a new family of chiral phosphinocyclopropane derivatives, featuring 100 % atom efficiency, good diastereo‐ and enantioselectivity, broad substrate scope, and no need for a directing group. [ABSTRACT FROM AUTHOR]

The asymmetric hydrophosphination of cyclopropenes with phosphines is of much interest and importance, but has remained hardly explored to date probably because of the lack of suitable catalysts. We report here the diastereo‐ and enantioselective hydrophosphination of 3,3‐disubstituted cyclopropenes with phosphines by a chiral lanthanocene catalyst bearing the C2‐symmetric 5,6‐dioxy‐4,7‐trans‐dialkyl‐substituted tetrahydroindenyl ligands. This protocol offers a selective and efficient route for the synthesis of a new family of chiral phosphinocyclopropane derivatives, featuring 100 % atom efficiency, good diastereo‐ and enantioselectivity, broad substrate scope, and no need for a directing group. [ABSTRACT FROM AUTHOR]

The article describes the synthesis and photo- and electroluminescence properties of carbazole-substituted aromatic (E)- and (Z)-enynes. The enynes are easily prepared by catalytic dimerization of a terminal alkyne. They can act as an excellent single-emitting component for white organic light-emitting devices (WOLED), as a result of combination of the blue emission from an isolated molecule with the longer-wavelength emissions from eximers. The quality of white emission did not change under varying driving voltages, demonstrating an advantageous potential of single-emitting-component WOLED.

This article focuses on the catalytic addition of terminal alkynes to carbodiimides by half-sandwich rare earth metal complexes. It is reported in this article that the half-sandwich rare earth metal complexes, which bear silylene-linked cyclopentadienyl-amido ligands act as an excellent catalyst for the addition of terminal alkynes to carbodiimides. In this process a rare earth metal amidinate species has been confirmed to be a true catalytic species. The researchers conclude that the catalytic addition of terminal alkynes to carbodiimides has been achieved for the first time by use of half-sandwich rare earth metal complexes as a catalyst.

Reports on a novel organolanthanide catalyst system for the regio- and stereoselective head-to-head (Z)-dimerization of terminal alkynes. Recovery and reuse of the catalyst system; Reactivity of a series of half-metallocene alkyl complexes; High head-to-head (Z)-selectivity for the dimerization of of phenylacetylene by the lutetium anilido complexes.

Stereodivergent asymmetric catalysis is an important technology that can allow efficient access to various stereoisomers of a given product with multiple stereocenters from the same set of starting materials, but its application to the synthesis of a highly strained cyclopropane compound has remained unexplored to date. We report here the first diastereodivergent enantioselective synthesis of bicyclic aminocyclopropanes by lanthanum-catalyzed asymmetric carboamination/annu-lation of cyclopropenes with aminoalkenes. This protocol features 100% atom efficiency, good yield (up to 90%), and high chemo- (up to >20:1) and stereoselectivity (up to >20:1 dr and 99% ee), constituting a unique route for the efficient synthesis of two different diastereoisomers of a given chiral bicyclic aminocyclopropane compound. [ABSTRACT FROM AUTHOR]

The conversion of carbon monoxide (CO) to hydrocarbons and oxygenates on industrial solid catalysts (the Fischer-Tropsch reaction) largely relies on the cooperation of heteromultimetallic active sites composed of main group (such as alkali) and transition metals, but the mechanistic details have not been fully understood at the molecular level. Here we report the cooperative trimerization of CO by molecular lithium and samarium boryl complexes. We have found that, in the coexistence of a samarium boryl complex and a lithium boryl complex, the trimerization of CO selectively occurred to give a diborylallenetriolate skeleton "BC(O)C(O)C(O)B", in sharp contrast with the reaction of CO with either the lithium or the samarium boryl compound alone. The 13C-labeled experiments and computational studies have revealed that the CO trimerization reaction took place exclusively by coupling of a samarium boryl oxycarbene species, which was generated by insertion of one molecule of CO into the samarium-boryl bond, with a lithium ketenolate species formed by insertion of two molecules of CO into the lithium-boryl bond. These results offer unprecedented insight into CO oligomerization promoted by heteromultimetallic components and may help better understand the industrial F-T process and guide designing new catalysts. [ABSTRACT FROM AUTHOR]

Heteromultimetallic hydride complexes consisting of both rare-earth and d-transition metals are expected to exhibit unique reactivity because they have potential to show the synergistic effect of the substantially different types of metal centers. Here we report the reactions of rare-earth/ruthenium heterobimetallic dihydride complexes [Cp*Lu(THF)( μ -H) 2 ( μ - η 1 : η 1 -CHRP(CH 2 R) 2 )RuCp*] and [(C 5 Me 4 SiMe 3 )Y(DME)( μ -H) 2 ( μ - η 1 : η 1 -C 6 H 4 PPh 2 )RuCp*] (R = H, Me; Cp* = C 5 Me 5 ) with carbon monoxide. C–O bond cleavage and C–C bond formation, as well as P–C bond cleavage of the phosphine ligand occurred through the cooperation of two different metal centers. Dependence of the reaction pattern on the substituents of the phosphine ligands was also observed. [ABSTRACT FROM AUTHOR]

The hydrogenolysis of the PNP-ligated titanium dialkyl complex {(PNP)Ti(CH2SiMe3)2} (1, PNP = N(C6H3-2-P i Pr2-4-CH3)2) with H2 (1 atm) in the presence of N2 (1 atm) afforded a binuclear titanium side-on/end-on dinitrogen complex {[(PNP)Ti]2(μ2,η1,η2-N2)(μ2-H)2} (2) at room temperature, which upon heating at 60 °C with H2 gave a μ2-imido/μ2-nitrido/hydrido complex {[(PNP)Ti]2(μ2-NH)(μ2-N)H} (3) through the cleavage and partial hydrogenation of the N2 unit. The mechanistic aspects of the hydrogenation of the N2 unit in 2 with H2 have been elucidated by the density functional theory calculations. [ABSTRACT FROM AUTHOR]

An enantioselective C−H addition to a C=C bond represents the most atom-efficient route for the construction of chiral carbon-carbon skeletons, a central research topic in organic synthesis. We herein report the enantioselective yttrium-catalyzed C(sp3)−H bond addition of 2-methyl azaarenes, such as 2-methyl pyridines, to various substituted cyclopropenes and norbornenes. This process efficiently afforded a new family of chiral pyridylmethyl-functionalized cyclopropane and norbornane derivatives in high yields and high enantioselectivities (up to 97 % ee). [ABSTRACT FROM AUTHOR]

An enantioselective C−H addition to a C=C bond represents the most atom-efficient route for the construction of chiral carbon-carbon skeletons, a central research topic in organic synthesis. We herein report the enantioselective yttrium-catalyzed C(sp3)−H bond addition of 2-methyl azaarenes, such as 2-methyl pyridines, to various substituted cyclopropenes and norbornenes. This process efficiently afforded a new family of chiral pyridylmethyl-functionalized cyclopropane and norbornane derivatives in high yields and high enantioselectivities (up to 97 % ee). [ABSTRACT FROM AUTHOR]

The [2+2] cycloaddition of allenes with alkenes is of much interest and importance as a straightforward route for the construction of four‐membered carbocycles but has remained much underexplored to date. Herein we report for the first time the intermolecular regio‐ and diastereoselective formal [2+2] cycloaddition of a wide range of allenes with amino‐functionalized alkenes by half‐sandwich rare‐earth catalysts. The reaction proceeded through an allene C(sp2)−H activation mechanism initiated by the site‐selective deprotonation of the allene unit by a rare‐earth metal alkyl species followed by alkene insertion into the resulting metal‐allenyl bond and the subsequent intramolecular cycloaddition to an allene C=C bond. This protocol offers a unique route for the synthesis of a new family of cyclobutane and cyclobutene derivatives which were difficult to access previously. [ABSTRACT FROM AUTHOR]

The [2+2] cycloaddition of allenes with alkenes is of much interest and importance as a straightforward route for the construction of four‐membered carbocycles but has remained much underexplored to date. Herein we report for the first time the intermolecular regio‐ and diastereoselective formal [2+2] cycloaddition of a wide range of allenes with amino‐functionalized alkenes by half‐sandwich rare‐earth catalysts. The reaction proceeded through an allene C(sp2)−H activation mechanism initiated by the site‐selective deprotonation of the allene unit by a rare‐earth metal alkyl species followed by alkene insertion into the resulting metal‐allenyl bond and the subsequent intramolecular cycloaddition to an allene C=C bond. This protocol offers a unique route for the synthesis of a new family of cyclobutane and cyclobutene derivatives which were difficult to access previously. [ABSTRACT FROM AUTHOR]

The catalytic selective multi-component coupling of CO2, bis(pinacolato)diboron, LiOtBu, and a wide range of aldehydes has been achieved for the first time by using an NHC-copper catalyst. This transformation has efficiently afforded a series of novel lithium cyclic boracarbonate ion pair compounds in high yields from readily available starting materials. This protocol has not only provided a new catalytic process for the utilization of CO2, but it has also constituted a novel route for the efficient synthesis of a new class of lithium borate compounds that might be of interest as potential electrolyte candidates for lithium ion batteries. [ABSTRACT FROM AUTHOR]

The catalytic selective multi-component coupling of CO2, bis(pinacolato)diboron, LiOtBu, and a wide range of aldehydes has been achieved for the first time by using an NHC-copper catalyst. This transformation has efficiently afforded a series of novel lithium cyclic boracarbonate ion pair compounds in high yields from readily available starting materials. This protocol has not only provided a new catalytic process for the utilization of CO2, but it has also constituted a novel route for the efficient synthesis of a new class of lithium borate compounds that might be of interest as potential electrolyte candidates for lithium ion batteries. [ABSTRACT FROM AUTHOR]

The catalytic CH addition of pyridines to allenes has been achieved for the first time by using a half-sandwich scandium catalyst, thus constituting a straightforward and atom-economical route for the synthesis of alkenylated pyridine derivatives. The reaction proceeded regio- and stereoselectively, affording a new family of alkenylated pyridine compounds which are otherwise difficult to synthesize. A cationic Sc-η2-pyridyl species was isolated and confirmed to be a key catalyst species in this transformation. [ABSTRACT FROM AUTHOR]

Here we report for the first time the regio‐ and diastereoselective [3+2] annulation of a wide range of aliphatic aldimines with alkenes via the activation of an unactivated β‐C(sp3)−H bond by half‐sandwich scandium catalysts. This protocol offers a straightforward and atom‐efficient route for the synthesis of a new family of multi‐substituted aminocyclopentane derivatives from easily accessible aliphatic aldimines and alkenes. The annulation of aldimines with styrenes exclusively afforded the 5‐aryl‐trans‐substituted 1‐aminocyclopentane derivatives with excellent diastereoselectivity through the 2,1‐insertion of a styrene unit. The annulation of aldimines with aliphatic alkenes selectively gave the 4‐alkyl‐trans‐substituted 1‐aminocyclopentane products in a 1,2‐insertion fashion. A catalytic amount of an appropriate amine such as adamantylamine (AdNH2) or dibenzylamine (Bn2NH) showed significant effects on the catalyst activity and stereoselectivity. [ABSTRACT FROM AUTHOR]

Here we report for the first time the regio‐ and diastereoselective [3+2] annulation of a wide range of aliphatic aldimines with alkenes via the activation of an unactivated β‐C(sp3)−H bond by half‐sandwich scandium catalysts. This protocol offers a straightforward and atom‐efficient route for the synthesis of a new family of multi‐substituted aminocyclopentane derivatives from easily accessible aliphatic aldimines and alkenes. The annulation of aldimines with styrenes exclusively afforded the 5‐aryl‐trans‐substituted 1‐aminocyclopentane derivatives with excellent diastereoselectivity through the 2,1‐insertion of a styrene unit. The annulation of aldimines with aliphatic alkenes selectively gave the 4‐alkyl‐trans‐substituted 1‐aminocyclopentane products in a 1,2‐insertion fashion. A catalytic amount of an appropriate amine such as adamantylamine (AdNH2) or dibenzylamine (Bn2NH) showed significant effects on the catalyst activity and stereoselectivity. [ABSTRACT FROM AUTHOR]

The terpolymerization of a non‐polar olefin (such as ethylene) and two different polar functional olefins in a controlled fashion is of great interest and importance but has hardly been explored to date. We report for the first time the terpolymerization of ethylene (E) and two different methoxyaryl‐substituted propylenes (AR1P=hexylanisyl propylene; AR2P=methoxynaphthyl propylene or methoxypyrenyl propylene) by a half‐sandwich scandium catalyst. The terpolymerization took place in a sequence‐controlled fashion, affording unique multi‐block copolymers composed of two different ethylene‐alt‐methoxyarylpropylene sequences E‐alt‐AR1P (soft segments) and E‐alt‐AR2P (hard segments) and relatively short ethylene–ethylene (EE) blocks (crystalline segments). The terpolymers exhibited excellent elasticity and unprecedented self‐healing as a result of microphase separation of nanodomains of the crystalline EE segments and the hard amorphous E‐alt‐AR2P segments from a very flexible E‐alt‐AR1P matrix, demonstrating unique synergy of the three different components. [ABSTRACT FROM AUTHOR]

The terpolymerization of a non‐polar olefin (such as ethylene) and two different polar functional olefins in a controlled fashion is of great interest and importance but has hardly been explored to date. We report for the first time the terpolymerization of ethylene (E) and two different methoxyaryl‐substituted propylenes (AR1P=hexylanisyl propylene; AR2P=methoxynaphthyl propylene or methoxypyrenyl propylene) by a half‐sandwich scandium catalyst. The terpolymerization took place in a sequence‐controlled fashion, affording unique multi‐block copolymers composed of two different ethylene‐alt‐methoxyarylpropylene sequences E‐alt‐AR1P (soft segments) and E‐alt‐AR2P (hard segments) and relatively short ethylene–ethylene (EE) blocks (crystalline segments). The terpolymers exhibited excellent elasticity and unprecedented self‐healing as a result of microphase separation of nanodomains of the crystalline EE segments and the hard amorphous E‐alt‐AR2P segments from a very flexible E‐alt‐AR1P matrix, demonstrating unique synergy of the three different components. [ABSTRACT FROM AUTHOR]

Tetranuclear cubane-type rare-earth methylidene complexes consisting of four "Cp′LnCH2" units, [Cp′Ln(μ3-CH2)]4 (4-Ln; Ln = Tm, Lu; Cp′ = C5Me4SiMe3), have been obtained for the first time through CH4 elimination from the well-defined polymethyl complexes [Cp′Ln(μ2-CH3)2]3 (2-Ln) or mixed methyl/methylidene precursors such as [Cp′3Ln3(μ2-Me)3(μ3-Me)(μ3-CH2)] (3-Ln). The reaction of the methylidene complex 4-Lu with benzophenone leads to C-O bond cleavage and C-C bond formation to give the cubane-type oxo complex [Cp′Lu(μ3-O)]4 and CH2-CPh2, while the methyl/methylidene complex 3-Tm undergoes sequential methylidene addition to the C-O group and ortho C-H activation of the two phenyl groups of benzophenone to afford the bis(benzo-1,2-diyl)ethoxy-chelated trinuclear complex [Cp′3Tmμ(μ2-Me)3{(C6H4)2C(O)Me}] (6-Tm). [ABSTRACT FROM AUTHOR]

The living isospecific-cis-1,4-polymerization and block-copolymerization of (E)-1,3-pentadiene with 1,3-butadiene have been achieved for the first time by using cationic half-sandwich scandium catalysts. [ABSTRACT FROM AUTHOR]

The precise control of monomer sequence and stereochemistry in copolymerization is of much interest and importance for the synthesis of functional polymers, but studies toward this goal have met with only limited success to date. Now, the co‐syndiospecific alternating copolymerization of methoxyphenyl‐ and N,N‐dimethylaminophenyl‐functionalized propylenes with styrene by half‐sandwich rare‐earth catalysts is reported. This reaction efficiently afforded the corresponding functionalized propylene‐alt‐styrene copolymers with a perfect alternating sequence and excellent co‐syndiotacticity (rrrr >99 %), thus constituting the first example of co‐stereospecific alternating copolymerization of polar and non‐polar olefins. [ABSTRACT FROM AUTHOR]

The precise control of monomer sequence and stereochemistry in copolymerization is of much interest and importance for the synthesis of functional polymers, but studies toward this goal have met with only limited success to date. Now, the co‐syndiospecific alternating copolymerization of methoxyphenyl‐ and N,N‐dimethylaminophenyl‐functionalized propylenes with styrene by half‐sandwich rare‐earth catalysts is reported. This reaction efficiently afforded the corresponding functionalized propylene‐alt‐styrene copolymers with a perfect alternating sequence and excellent co‐syndiotacticity (rrrr >99 %), thus constituting the first example of co‐stereospecific alternating copolymerization of polar and non‐polar olefins. [ABSTRACT FROM AUTHOR]

Small angle neutron scattering (SANS) is a versatile and convenient method to investigate the higher order structure of molecular assembly systems. However, the more complicated a system of interest, the more difficult the interpretation in the SANS profile. In order to increase the reliability of structural analysis on a complicated system, it is desirable to obtain different kinds of structural information from the same sample simultaneously. Polarized infrared spectroscopy is able to provide information about the molecular structure, concentration, and orientation of each chemical species in a system. In order to utilize these advantages of polarized infrared spectroscopy, a simultaneous measurement system was built by incorporating a Fourier transform infrared (FTIR) spectrometer into a time-of-flight small angle neutron scattering instrument covering a wide Q range. Using this system, simultaneous measurements of wide- and small-angle neutron scattering and polarized FTIR spectroscopy was realized for the first time. [ABSTRACT FROM AUTHOR]

Transition metal catalyzed C−H functionalization of organic compounds has proved to be a useful atom‐efficient strategy in organic synthesis. In contrast, main‐group‐element‐based catalytic processes for C−H functionalization have remained underexplored to date. Reported herein is the catalytic C(sp)−H silylation of a wide range of terminal alkynes with hydrosilanes by using a combination of B(C6F5)3 and an organic base such as triethylenediamine (DABCO). This protocol constitutes the first example of boron‐catalyzed C(sp)−H functionalization, offering a convenient route for the synthesis of a variety of alkynylsilanes. Experimental and computational studies have revealed that DABCO plays two crucial roles (Lewis base and Brønsted base) in this catalytic transformation. Double duty: The combination of B(C6F5)3 and an organic base, such as triethylenediamine (DABCO), serve as an excellent catalytic system for the C(sp)−H silylation of terminal alkynes with hydrosilanes. DABCO plays two crucial roles (Lewis base and Brønsted base) as revealed by experimental and DFT studies. [ABSTRACT FROM AUTHOR]

Transition metal catalyzed C−H functionalization of organic compounds has proved to be a useful atom‐efficient strategy in organic synthesis. In contrast, main‐group‐element‐based catalytic processes for C−H functionalization have remained underexplored to date. Reported herein is the catalytic C(sp)−H silylation of a wide range of terminal alkynes with hydrosilanes by using a combination of B(C6F5)3 and an organic base such as triethylenediamine (DABCO). This protocol constitutes the first example of boron‐catalyzed C(sp)−H functionalization, offering a convenient route for the synthesis of a variety of alkynylsilanes. Experimental and computational studies have revealed that DABCO plays two crucial roles (Lewis base and Brønsted base) in this catalytic transformation. [ABSTRACT FROM AUTHOR]

Abstract: The catalytic asymmetric construction of silicon‐stereogenic silanes is of great interest and significance, but has met with only limited success to date. We herein report the enantioselective hydrosilylation of alkenes with dihydrosilanes by a chiral half‐sandwich scandium catalyst, which constitutes an efficient and general route for the synthesis of a wide range of enantioenriched silicon‐stereogenic silanes from easily accessible starting materials. This reaction features a broad substrate scope, high yields, and high enantioselectivity. Some of the chiral tertiary silane products were also converted into valuable derivatives, such as chiral silanol, quaternary silane, and benzosilole compounds. [ABSTRACT FROM AUTHOR]

Abstract: The catalytic asymmetric construction of silicon‐stereogenic silanes is of great interest and significance, but has met with only limited success to date. We herein report the enantioselective hydrosilylation of alkenes with dihydrosilanes by a chiral half‐sandwich scandium catalyst, which constitutes an efficient and general route for the synthesis of a wide range of enantioenriched silicon‐stereogenic silanes from easily accessible starting materials. This reaction features a broad substrate scope, high yields, and high enantioselectivity. Some of the chiral tertiary silane products were also converted into valuable derivatives, such as chiral silanol, quaternary silane, and benzosilole compounds. [ABSTRACT FROM AUTHOR]