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This paper reports a computational study on the specific 1,4‐cis polymerization of butadiene catalyzed by the cationic gadolinium metallocene [(C5Me5)2Gd][B(C6F5)4] combined with excess amount of Al(iBu)3. Because this reaction system has no initial Gd–alkyl bond, a mechanism with conventional coordinative chain transfer polymerization (CCTP) is not feasible. Density functional theory (DFT) analyses indicate a novel mechanism in which the cationic Gd plays a crucial role by assisting butadiene insertion into one of the Al−C bond of Al(iBu)3. The proposed butadiene polymerization mechanism can account for the specific 1,4‐cis selectivity of this catalyst system. [ABSTRACT FROM AUTHOR]

The hydrophilic nature of clean surfaces and the hydrophobic nature of TMA-covered surfaces are revealed by the behavior of H2O on clean and trimethylacetate. The TMA is removed and the wetting behavior of the surface is restored, by the irradiation with the UV light in the presence of Torr of O2.

The Ru K-edge extended X-ray absorption fine structure (EXAFS) is used to investigate the surface Ru site-structure, which is formed under various catalyst preparation and reaction conditions. The NO under NO+CO gas predominantly occupies the Ru metal surface of conventional Ru/TiO2 catalysts, as reported.

The reactive excited state for photodissociation and the association mechanisms of CN-R to both Cl(H2O)Cr(super III)TPP and the five-coordinate ClCr(super III)TPP were investigated in laser-photolysis experiments. Experimental results showed that chloroaquachromium(III) tetraphenylporphyrin undergoes reversible reaction with isocyanide to form Cl(CN-R)Cr(super III)TPP in toluene solutions containing 4.4 x 10(super -3) M H2O and CN-R. The photodissociation of CN-R from Cl(CN-R)Cr(super III)TPP results in Cl(H2O)Cr(super III)TPP with a quantum yield ca. 0.1.

A study was conducted on the isolation, structural characterization and reactivity of a series of lanthanide ketyl complexes. The findings indicate that the reactivity and stability of a ketyl species are extremely susceptible to the steric environment around the central metal ion. Moreover, the results suggest that the choice of reducing agents including metals and ancillary ligands is very important in the isolation of a ketyl species.

Several sulfur dioxide ligand-containing hexaruthenium carbonyl clusters are synthesized with the substitution of CO with an SO in the presence of trimethyl amine oxide. The positions of NO and C3H5 ligands in some clusters were determined by X-ray diffraction analysis. The conventional coordination configuration of the sulphur dioxide ligand undergoes an S-O bond fission to give the SO complex.

The ab initio molecular orbital analysis of Werner's reaction is analyzed on a model system. Rearrangement is undertaken in a square planar rhodium d8 system. The model system replaces the PiPr3 ligand and monosubstituted acetylene used in real reactions by PH3 and HC=CH. The isomerization route and the transition state structures derived from the Rh complex show the importance of the electronic configuration of the metal center.

The [(ArO)Sm(mu-I)(THF)3]2 Sm(II) mixed aryloxide/iodide was produced by the reaction of Sm(OAr)2(THF)3 with SmI2 in tetrahydrofuran (THF). The Sm(II) mixed aryloxide/iodide exhibits a weak Sm...I bond interactions which results in a dimeric structure. The reaction of Sm(II) aryloxide/iodide with C5Me5K in THF produced dark brown crystals of Sm(II) aryloxide/cylcopentadienide. The Sm(II) complex exhibits a distorted tetrahedral structure that is composed of a central Sm(II) ion with one C5Me5, ArO ligands.

Spectroscopic and ab initio theoretical studies of the reaction between RuX2(PPh3)3 (X = Cl, Br) and tert-butylacetylene that yields vinylidene complexes and help examine the characteristics of acetylene molecule in transition metal complexes. X-ray studies of the final trans-bis(phosphine) complex reveal that it is a thermodynamically-stable five-coordinate complex. The mechanism involves formation of an eta(2)-CH coordinated complex by slippage of the eta(2)-CC coordinated alkyne. 1, 2-hydrogen migration in the eta(2)-CH complex occurs within the acetylene to yield a metastable vinylidene complex having a cis-bis(phosphine) that isomerizes to the final trans-bis(phosphine) complex.

The cationic gadolinium metallocene [(C5Me5)2Gd][B(C6F5)4], when combined with an excess amount of Al(iBu)3, efficiently produces polyethylene at 80 °C under 0.8 MPa pressure of ethylene. After quenching, the resulting polyethylene has ethyl group at one end and isobutyl group at the other terminal. Because no Gd‐alkyl species appears to be involved, a mechanism with conventional coordinative chain transfer polymerization (CCTP) is not feasible. Density functional theory (DFT) analyses indicate a novel mechanism in which the cationic Gd plays a crucial role by coordinating ethylene and assists the insertion of the coordinated ethylene into Al−C bond. [ABSTRACT FROM AUTHOR]

The P-C bond of trimethylphosphine can be activated by the coordination site from a suitable heterodimetallic complex. (C5H5)Ni(mu-CO)(mu-H)W(C5H5)2 (1) was treated with excess PMe3 in THF at room temperature resulting in (C5H5)Ni(mu-CO)(mu-PMe2)(C5H5)W(Me)(PMe3) (2) with a 58% yield. This unique form of bond activation has been verified by x-ray analysis and the reaction is described in terms of the structure of compound 2.

Am investigation of the mechanism of the selective conversion of 1-alkynes to aldehydes by hydration was conducted by isolating organic and organometallic byproducts, deuterium-labeling experiments, and DFT calculations. The results suggest that the involvement of a metal-acyl intermediate with the original acetylenic hydrogen also bound to the metal center as a hydride, with the next step being release of aldehyde by reductive elimination.

Catalytic dimerization of terminal alkynes is an atom economic and straightforward method for the synthesis of conjugated enynes, which are important building blocks for organic synthesis and significant components in various biological active compounds. A novel organolanthanide catalyst system for the region- and stereoselective head-to-head (Z)-dimerization of terminal alkynes is reported.

A structurally characterized (pentamethylcyclopentadienyl)lanthanide(II) alkyl compound is reported.

Research developing a based for the deprotonation of compounds of acidic organic nature and a type of catalyst for the bon-cleavage of the C-C type is presented. Michael additions and aromatic 1,2 diols are emaphsized in the use of binuclear iridium hydrite complex.

The reaction of Sm metal with three equiv of fluorenone in THF produced tris(ketyl)samarium(III) complex in the form of a yellow precipitate. Dark green blocks of the monomeric samarium(III)tris(fluorenone ketyl) complex was produced by combining three equiv of hexamethylphosphoric triamide (HMPA) with ether. Analysis of the monomeris samarium(III)tris(fluorenone ketyl) complex indicated the presence of a central Sm atom that is coordinated by three ketyls and three HMPA in octahedral configuration.

Dimeric and tetrameric sodium fluorenone ketyls of the type Na(mu2-eta2-biphenyl-2,2'-diyl ketyl)-(HMPA2) 2 and Na(mu3-eta1-biphenyl-2,2'-diyl ketyl)-(HMPA) 4 where HMPA = hexamethylphosphoric triamide were isolated for the first time using as a HMPA as a ligand. The complexes, which were generated from the reaction of fluorenone with sodium metal in tetrahydrocortisol, may also be synthesized through carbon-carbon bond cleavage of the pinacolate in a reaction between 1,2(biphenyl-2,2'-diyl)ethane-1,2-diol and NaN(SiMe3)2.

Density functional theory (DFT) analysis indicates a mechanism in which cationic Gd assists butadiene insertion into one of the Al-C bonds of Al( SP I i i sp Bu) SB 3 sb , explaining the 1,4- I cis i selectivity unique to this catalytic system. Keywords: Lanthanides; Alkylaluminum; Butadiene polymerization; Reaction mechanisms; DFT study EN Lanthanides Alkylaluminum Butadiene polymerization Reaction mechanisms DFT study 1 1 1 12/06/22 20221201 NES 221201 B A novel mechanism for the polymerization of butadiene b by cationic gadolinium metallocene in the presence of excess Al( SP I i i sp Bu) SB 3 sb is presented. Front Cover: Non- -Allyl Mechanism for the 1,4-cis-Butadiene Polymerization: Theoretical Study of Polymerization via Insertion of Butadiene into Al-C Bond with Cationic Gadolinium Metallocene. [Extracted from the article]

The reaction between samarium(II) aryloxide and fluorenone produces the metal ketyl complex Sm(biphenyl-2,2'-diyl ketyl)- (OAr)2(THF)2. For the first compound, the Sm-O bond distance of the fluorenone part is almost identical to that of Sm-OAr bonds of the produced complex, confirming the ionic nature of the Sm-O bond. A coupling of the ketyl to samarium(III) pinacolate, which has a crystallographic inversion center on the C(1)-C(1') bond, was reversible through an additive strongly coordinative solvent, supporting previous research.