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Atomic layer deposition (ALD) is a suitable technology for conformally depositing thin films on nanometer‐scale 3D structures. RuO2 is a promising diffusion barrier for Ru interconnects owing to its compatibility with Ru ALD and its remarkable diffusion barrier properties. Herein, a RuO2 diffusion barrier using an ALD process is developed. The highly reactive Ru precursor [tricarbonyl(trimethylenemethane)ruthenium] and improved O2 supply enable RuO2 deposition. The optimal process conditions [pulsing time ratio (tO2/tRu): 10, process pressure: 1 Torr, temperature: 180 °C] are established for the RuO2 growth. Growth parameters, such as the growth rate (0.56 Å cycle–1), nucleation delay (incubation period: 6 cycles), and conformality (step coverage: 100%), are also confirmed on the SiO2 substrate. The structural and electrical properties of the Ru/RuO2/Si multilayer are investigated to explore the diffusion barrier performance of the ALD‐RuO2 film. The formation of Ru silicide does not occur without the conductivity degradation of the Ru/RuO2/Si multilayer with an increase in the annealing temperature up to 850 °C, thus demonstrating that interdiffusion of Ru and Si is completely suppressed by a thin (5 nm) ALD‐RuO2 film. Consequently, the practical growth behavior and diffusion barrier performance of RuO2 can serve as a potential diffusion barrier for Ru interconnects. [ABSTRACT FROM AUTHOR]

Summary of main observation and conclusion: A palladium‐catalyzed asymmetric [4 + 3] cycloaddition of trimethylenemethanes and indoline‐derived aza‐dienes has been developed. The potential [3 + 2] side pathway was completely suppressed in the process. This protocol provides an efficient access to azepino[2,3‐b]indoles bearing two vicinal stereocenters in generally excellent diastereo‐ and enantioselectivities (up to > 20 : 1 dr, 99% ee). [ABSTRACT FROM AUTHOR]

Summary of main observation and conclusion: A palladium‐catalyzed asymmetric [4 + 3] cycloaddition of trimethylenemethanes and indoline‐derived aza‐dienes has been developed. The potential [3 + 2] side pathway was completely suppressed in the process. This protocol provides an efficient access to azepino[2,3‐b]indoles bearing two vicinal stereocenters in generally excellent diastereo‐ and enantioselectivities (up to > 20 : 1 dr, 99% ee). [ABSTRACT FROM AUTHOR]

In this study, we observed that methylenecyclopropane 1 c, possessing geminal phenyl and 1‐naphthyl groups at C‐2 of the three membered ring, emits green thermoluminescence (TL) in a low temperature matrix, associated with two sets of bands in the 480–600 and 600–700 nm regions. The bands are assigned to phosphorescence from 31 c* and triplet‐triplet (T−T) fluorescence (FL) from the corresponding trimethylenemethane biradical 32 c..*, respectively. In contrast, as previously reported, the analogous 2‐naphthyl derivative 1 b emits red TL associated with two bands in the 350–450 and 600–700 nm regions, which are assigned to FL from 11 b* and T−T FL from 32 b..*. The results of spectroscopic studies and density functional theory calculations show that the observed dissimilarity in the TL properties of 1 b and 1 c is a consequence of differences in the rate of methylenecyclopropane ring opening of 1 b.+ and 1 c.+ associated with stereoelectronic effects of the naphthyl groups. [ABSTRACT FROM AUTHOR]

A general method for asymmetric synthesis of heteroaryl‐containing cycles via palladium‐catalyzed cyclization is reported. Most classes of nitrogen‐containing aromatics, including pyridines, quinolines, pyrimidines, various azoles and the derivatives of nucleobases are compatible substrates, offering various heteroaryl‐substituted cyclopentane, pyrrolidine, furanidine and bicyclo[4.3.1]decadiene derivatives with good to excellent enantioselectivity and diastereoselectivity. [ABSTRACT FROM AUTHOR]

The title bicyclic system 3, the adduct arising from the formal [6+3] cycloaddition of α‐tropolone O‐methyl ether (1) and trimethylenemethane (2), has been prepared and subject to single‐crystal X‐ray analysis. The chemical manipulation of adduct 3 in a range of ways is reported, including through acid‐catalysed rearrangement of the derived mono‐oxide to give the bicyclo[4.3.1]undecane 21. [ABSTRACT FROM AUTHOR]

Abstract: A protocol for the asymmetric synthesis of highly substituted chiral allenes with control of point and axial chirality has been developed. A palladium‐catalyzed [3+2] cycloaddition using readily available racemic allenes gives access to densely functionalized chiral allenes with excellent yields and functional group tolerance. The catalytic asymmetric protocol utilizes a broad range of allenyl TMM (trimethylenemethane) donors to form cyclopentanes, pyrrolidines, and spirocycles with very good control of regio‐, enantio‐, and diastereoselectivity. The chiral allene moiety is shown to be a valuable functional group for rapid elaboration towards complex targets. [ABSTRACT FROM AUTHOR]

Abstract: A nitrile‐substituted trimethylenemethane (TMM) donor undergoes palladium‐catalyzed [3+2] cycloadditions with fluorinated ketones to generate tetrasubstituted trifluoromethylated centers in high enantioselectivity under mild conditions. The generation of the palladium–TMM complex was achieved by a self‐deprotonation strategy, which shows remarkable improvements in regiocontrol, efficiency, and atom economy of asymmetric [3+2] cycloadditions. Moreover, the versatility of the nitrile group provides direct access to a variety of synthetically useful intermediates, including amides, aldehydes, and esters. The developed reaction conditions allow for the synthesis of a wide variety of aromatic, heteroaromatic, and aliphatic fluorinated dihydrofurans in excellent regio‐ and enantioselectivities. [ABSTRACT FROM AUTHOR]

Abstract: The first realization of the amino‐trimethylenemethane chemistry is reported using a deprotonation strategy to simplify the synthesis of the amino‐trimethylenemethane donor in two steps from commercial and inexpensive materials. A broad scope of cycloaddition acceptors (seven different classes) participated in the chemistry, chemo‐, regio‐, diastereo‐, and enantioselectively generating various types of highly valuable complex amino cycles. Multiple derivatization reactions that further elaborated the initial amino cycles were performed without isolation of the crude product. Ultimately, we applied the amino‐trimethylenemethane chemistry to synthesize a potential pharmaceutical in 8 linear steps and 7.5 % overall yield, which previously was achieved in 18 linear steps and 0.6 % overall yield. [ABSTRACT FROM AUTHOR]

Abstract: (12/12)CASSCF and CASPT2 calculations have been performed on the triplet and two lowest‐lying singlet states of the 2,7‐naphthoquinodimethane (NQDM) and 2,7‐naphthoquinone (NQ) diradicals. Both diradicals are predicted to have triplet ground states but to differ in the ordering of the two lowest singlet states, with E(1A1) < E(1B2) in NQDM, but E(1A1) > E(1B2) in NQ. The reason for the difference in ordering of the singlet states in these two diradicals is discussed. The state reordering is shown to be responsible for the prediction that the substitution of the oxygens in NQ for the CH2 groups in NQDM increases, rather than decreases, the singlet‐triplet energy separation (ΔEST). [ABSTRACT FROM AUTHOR]

Abstract: (12/12)CASSCF and CASPT2 calculations have been performed on the triplet and two lowest‐lying singlet states of the 2,7‐naphthoquinodimethane (NQDM) and 2,7‐naphthoquinone (NQ) diradicals. Both diradicals are predicted to have triplet ground states but to differ in the ordering of the two lowest singlet states, with E(1A1) < E(1B2) in NQDM, but E(1A1) > E(1B2) in NQ. The reason for the difference in ordering of the singlet states in these two diradicals is discussed. The state reordering is shown to be responsible for the prediction that the substitution of the oxygens in NQ for the CH2 groups in NQDM increases, rather than decreases, the singlet‐triplet energy separation (ΔEST). [ABSTRACT FROM AUTHOR]

Abstract: Trimethylenemethane (TMM) diradical is the simplest non‐Kekulé non‐disjoint molecule with the triplet ground state (ΔEST=+16.1 kcal mol−1) and is extremely reactive. It is a challenge to design and synthesize a stable TMM diradical with key properties, such as actual aliphatic TMM diradical centers and the triplet ground state with a large positive ΔEST value, since such species provide detailed information on the electronic structure of TMM diradical. Herein we report a TMM derivative, in which the TMM segment is fused with three NiII meso‐triarylporphyrins, that satisfies the above criteria. The diradical shows delocalized spin density on the propeller‐like porphyrin π‐network and the triplet ground state owing to the strong ferromagnetic interaction. Despite the apparent TMM structure, the diradical can be handled under ambient conditions and can be stored for months in the solid state, thus allowing its X‐ray diffraction structural analysis. [ABSTRACT FROM AUTHOR]

The first total synthesis of waihoensene, a tetracyclic diterpene containing an angular triquinane and a six-membered ring, with four contiguous quaternary carbon atoms, was achieved through the tandem cycloaddition reaction of an allenyl diazo substrate containing a six-membered ring via trimethylenemethane (TMM) diyl intermediate. [ABSTRACT FROM AUTHOR]

Efforts to install the core azepine ring in tetrapetalone A via a palladium π-allyl cascade reaction failed due to competing pathways that included an unexpected and interesting TMM-like cycloaddition reaction that delivers a complex tricyclic ring system. [ABSTRACT FROM AUTHOR]

The degradation of the poly(trimethylene carbonate) (PTMC) and poly(trimethylene carbonate-co-ε-caprolactone) (P(TMC-co-CL)) networks cross-linked by 0.01 and 0.02 mol % 2,21-bis(trimethylene carbonate-5-yl)-butylether (BTB) was carried out in the conditions of hydrolysis and enzymes in vitro and subcutaneous implantation in vivo. The results showed that the cross-linked PTMC networks exhibited much faster degradation in enzymatic conditions in vitro and in vivo versus in a hydrolysis case due to the catalyst effect of enzymes; the weight loss and physical properties of the degraded networks were dependent on the BTB amount. The morphology observation in lipase and in vivo illustrated that enzymes played an important role in the surface erosion of cross-linked PTMC. The hydrolytic degradation rate of the cross-linked P(TMC-co-CL) networks increased with increasing ε-caprolactone (CL) content in composition due to the preferential cleavage of ester bonds. Cross-linking is an effective strategy to lower the degradation rate and enhance the form-stability of PTMC-based materials. [ABSTRACT FROM AUTHOR]

Two biobased polymers, poly(trimethylene terephthalate) (PTT) and high density polyethylene with varying concentrations were injection molded for their performance evaluation. Differential scanning calorimetry determined that the majority of the blends exhibited a cold crystallization peak in the first heating cycle. Dynamic mechanical analysis revealed an increase in the storage modulus after the material has passed its T g which can be related to the material's ability to cold crystallization. Blending demonstrated intermediate values for the tensile and flexural properties in comparison to each neat polymer. However, the notched Izod impact strength was higher for blends containing less than 50 wt.% biobased polyethylene (BioPE) compared to the virgin materials. The best performance in comparison to the other blends was observed for the PTT/BioPE (80/20) wt.% formulation, which had balanced tensile and flexural properties and an increase of 64% in the impact strength. This was explained through the impact fracture morphology via scanning electron microscopy. Variations in PTT and BioPE loading resulted in different surface structures, phase distributions and particle sizes. PTT as the minor phase resulted in randomly distributed large spheres. Whereas, when BioPE was the minor phase, it formed small uniform spherical/rod-like structures. Smaller particle size provided a toughening effect on the impact strength. [ABSTRACT FROM AUTHOR]

Knoevenagel adducts derived from readily available acetoxyacetone and malonic acid derivatives served as trimethylenemethane surrogates for formal 1,3-difunctionalization through a sequence of selective γ-deprotonation/a-alkylation and palladium(0)-catalyzed allylic alkylation. Herein, we report the discovery and development of a three-component 1,3-difunctionalization of Knoevenagel adducts as well as a unique palladium(0)-catalyzed branch-selective allylic alkylation. [ABSTRACT FROM AUTHOR]

α-Trifluoromethyl-styrenes, trifluoromethyl-enynes, and dienes undergo palladium-catalyzed trimethylenemethane cycloadditions under mild reaction conditions. The trifluoromethyl group serves as a unique σ-electron-withdrawing group for the activation of the olefin toward the cycloaddition. This method allows for the formation of exomethylene cyclopentanes bearing a quaternary center substituted by the trifluoromethyl group, compounds of interest for the pharmaceutical, agrochemical, and materials industries. In the diene series, the cycloaddition operates in a [3 + 4] and/or [3 + 2] manner to give rise to seven- and/or five-membered rings. This transformation greatly improves the scope of the TMM cycloaddition technology and provides invaluable insights into the reaction mechanism. [ABSTRACT FROM AUTHOR]

Trimethylenemethane (TMM) has long been known as a ligand in metal carbonyl complexes such as [η4-(CH2)3C]Fe(CO)3 and [η4-(CH2)3C]Cr(CO)4. The prospects for synthesizing currently unknown TMM complexes of cobalt carbonyl have been explored by a density functional theory study of the binuclear complexes [(CH2)3C]2Co2(CO)n (n = 2, 3, 4, 5, 6). The dicarbonyl is unexpectedly found to favor by more than ∼12 kcal mol−1 a perpendicular structure [μ-(CH2)3C]2Co2(CO)2 with bridging η4-TMM ligands, terminal CO groups, and a relatively short Co–Co distance of ∼2.29 Å. This is the first example of an energetically favorable perpendicular binuclear metal complex structure having bridging acyclic hydrocarbon ligands. The other viable species is [(CH2)3C]2Co2(CO)4, which is a substitution product of the well-known Co2(CO)8 with terminal η4-TMM ligands. Similar to Co2(CO)8, doubly bridged and unbridged [(CH2)3C]2Co2(CO)4 structures have approximately equal energies within ∼2 kcal mol−1 and predicted Co–Co distances of ∼2.5 and ∼2.7 Å, respectively. Carbonyl-rich [(CH2)3C]2Co2(CO)n (n = 5, 6) structures are also found with dihapto η2-TMM ligands. However, these are predicted to be unstable with respect to CO dissociation to give [(CH2)3C]2Co2(CO)4. [ABSTRACT FROM AUTHOR]

A general protocol for the palladium-catalyzed dearomative trimethylenemethane [3+2] cycloaddition reaction with simple nitroarene substrates is described. This methodology leads to the exclusive formation of the dearomatized alicyclic products without subsequent rearomatization. The reaction is tolerant toward a broad range of heterocyclic and benzenoid substrates. The use of chiral bisdiamidophosphite ligands enabled the development of an enantioselective variant of this transformation, representing one of the rare examples of an asymmetric catalytic dearomatization process. [ABSTRACT FROM AUTHOR]

A protocolfor the asymmetric trimethylenemethane (TMM) [3 + 2]cycloaddition reaction of alkynyl-substituted TMM donors and unsaturated N-acyl pyrroles employing a chiral bisdiamidophosphite ligandhas been developed. This process generates alkynyl-substituted cyclopentanesin high yields and diastereo- and enantioselectivities. These chiralprecursors are employed for the atom economic assembly of fused polycyclichydrocarbons with hydroindene, hydroazulene, and hydrocyclopentanaphthalenescaffolds by consecutive cycloaddition reactions. [ABSTRACT FROM AUTHOR]

This work aims to contribute to the discussion about the suitability of bond paths and bond-critical points as indicators of chemical bonding defined within the theoretical framework of the quantum theory of atoms in molecules. For this purpose, we consider the temporal evolution of the molecular structure of [Fe{C(CH2)3}(CO)3] throughout Born-Oppenheimer molecular dynamics (BOMD), which illustrates the changing behaviour of the molecular graph (MG) of an electronic system. Several MGs with significant lifespans are observed across the BOMD simulations. The bond paths between the trimethylenemethane and the metallic core are uninterruptedly formed and broken. This situation is reminiscent of a 'hopping' ligand over the iron atom. The molecular graph wherein the bonding between trimethylenemethane and the iron atom takes place only by means of the tertiary carbon atom has the longest lifespan of all the considered structures, which is consistent with the MG found by X-ray diffraction experiments and quantum chemical calculations. In contrast, the η4 complex predicted by molecular-orbital theory has an extremely brief lifetime. The lifespan of different molecular structures is related to bond descriptors on the basis of the topology of the electron density such as the ellipticities at the FeCH2 bond-critical points and electron delocalisation indices. This work also proposes the concept of a dynamic molecular graph composed of the different structures found throughout the BOMD trajectories in analogy to a resonance hybrid of Lewis structures. It is our hope that the notion of dynamic molecular graphs will prove useful in the discussion of electronic systems, in particular for those in which analysis on the basis of static structures leads to controversial conclusions. [ABSTRACT FROM AUTHOR]

Abstract: The trimethylenemethane ligand is found in the experimentally known and structurally characterized mononuclear iron carbonyl derivative (CH2)3CFe(CO)3, which may be regarded as a substitution product of Fe(CO)5. The structures of trinuclear trimethylenemethane iron carbonyl derivatives similarly related to the well-known doubly bridged Fe3(CO)12 structure have now been investigated by density functional theory. The lowest energy [(CH2)3C]Fe3(CO)10 structures likewise have two CO bridges and can be derived from the known Fe3(CO)12 structure by replacement of two terminal CO groups with either an unsymmetrical edge-bridging or face-bridging trimethylene methane ligand while preserving the central Fe3 triangle. However, replacing four CO groups in Fe3(CO)12 with two trimethylenemethane ligands to give [(CH2)3C]2Fe3(CO)8 is predicted unexpectedly to give a very different type of structure. In this structure one edge of the Fe3 triangle in Fe3(CO)12 is broken to form a bent Fe–Fe–Fe chain with the trimethylenemethane ligands bonded to the end iron atoms of this triiron chain. This [(CH2)3C]2Fe3(CO)8 structure appears to be very favorable, since it lies ∼22kcal/mol below alternative structures. We anticipate that both [(CH2)3C]Fe3(CO)10 and [(CH2)3C]2Fe3(CO)8 should be sufficiently stable to be synthesized from the known (CH2)3CFe(CO)3 by thermolysis or photolysis with suitable iron carbonyls. [Copyright &y& Elsevier]

We have recently developed the full and active-space doubly electron-attached (DEA) and doubly ionised (DIP) equation-of-motion coupled-cluster (EOMCC) methods with up to 4-particle–2-hole (4p-2h) and 4-hole–2-particle (4h-2p) excitations. By examining the low-lying singlet and triplet states of the methylene, (HFH)−, and trimethylenemethane biradicals, and a few different types of molecular orbitals (MOs) to describe the corresponding wave functions, including the restricted or restricted open-shell Hartree–Fock orbitals of the targetN-electron species and their counterparts associated with the (N ∓ 2)-electron reference systems, we demonstrate that the DEA- and DIP-EOMCC approaches with the full and active-space treatments of 4p-2hand 4h-2pexcitations provide high-accuracy results which are not only in perfect agreement with one another, but also practically insensitive to the choice of the underlying MO basis. This should be contrasted with the DEA- and DIP-EOMCC methods truncated at 3p-1h/3h-1pexcitations, which are generally less accurate and more sensitive to the types of orbitals used in the calculations. [ABSTRACT FROM AUTHOR]

The different reaction profiles of lithium trimethylsilyldiazomethane with various 4-alkenyl ketones are described. It was found that the individual steps along the reaction pathway including a Brook rearrangement, elimination of lithium trimethylsilanolate to form alkylidene carbenes, and their addition to an alkene to form strained bicyclo[3.1.0]hex-1-ene derivatives were significantly affected by the substituents near or on the alkene moiety. Especially, the dimerization of bicyclo[3.1.0]hex-1-enes depends critically on the substituent pattern of the alkene, which controls the reaction to proceed in a concerted or a stepwise manner. On the basis of X-ray diffraction analysis, the dimers, which are of unprecedented structural complexity, were unambiguously elucidated. [ABSTRACT FROM AUTHOR]

Abstract: Quantum chemical calculations using gradient-corrected DFT methods (BP86) using effective core potentials and TZP quality basis sets have been carried out for the complexes (CO)3M–TMM (M = Fe, Ru, Os, Rh+; TMM = trimethylenemethane). The calculated equilibrium geometries give trigonal pyramidal structures which are in good agreement with experimental results for the iron and ruthenium species. The TMM ligand adopts a pyramidal coordination of the central carbon atom which has a shorter distance to the metal atom than the terminal carbon atoms. The theoretically predicted bond dissociation energies of the TMM ligand are between 108.0 kcal/mol for the iron complex and 155.1 kcal/mol for the rhodium complex. The trend of the calculated TMM–M bond strength is Fe < Ru < Os < Rh+. The investigation of the electronic structure of the complexes (CO)3M–TMM using MO correlation diagrams and energy partitioning methods clearly shows that the metal atom is mainly bonded to the terminal carbon atoms of the TMM ligand while the bonding to the closer central carbon atom is much weaker. This is further supported by the AIM analysis which shows that the Laplacian distribution ∇2 ρ(r) at the terminal carbon atoms possesses local area of charge concentration which points toward the metal atom while the Laplacian distribution at the central carbon atoms is nearly undistorted. In spite of the shape of the Laplacian distribution, there are bond paths between the metal atom and the central carbon atom but not to the terminal carbon atom which comes from the different interatomic distances. This clearly shows that the absence and the existence of a bond path are not reliable criteria for chemical bonding. [Copyright &y& Elsevier]

β,β-Disubstituted nitroalkenes readily undergo palladium-catalyzed [3 + 2] cycloaddition with trimethylenemethane to generate nitrocyclopentanes in excellent yield and enantioselectivity. The reaction provides access to heavily substituted cyclopentanes containing up to three contiguous stereocenters, and the products may be converted to both cyclopentylamines and cyclopentenones. A rare dependence of the sense of chirality of the cycloadducts was observed to be exclusively dependent on the structure of the palladium-bound trimethylenemethane intermediate. [ABSTRACT FROM AUTHOR]

Highlights: [•] The structures and energetics of (C4H6)2Cr2(CO) n (n =7, 6, 5) are investigated by density functional theory. [•] (C4H6)2Cr2(CO)7 is disfavored with respect to dissociation into mononuclear fragments. [•] (C4H6)2Cr2(CO)6 is disfavored with respect to disproportionation into (C4H6)2Cr2(CO)7 +(C4H6)2Cr2(CO)5. [•] (C4H6)2Cr2(CO)5 is predicted to have all terminal CO groups and a Cr Cr triple bond. [•] The (C4H6)2Cr2(CO) n (n =7, 6, 5) structures are closely related to the isomeric [(CH2)3C]2Cr2(CO) n structures. [ABSTRACT FROM AUTHOR]

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading chemistry journals. The following PDF file contains a complete ChemInform issue, thus enabling easy electronic browsing further facilitated by electronic bookmarks. [ABSTRACT FROM AUTHOR]