CH CHCH Research Articles

Zero-Dimensional Sn-Based Enantiomeric Phase-Transition Materials with High-Tc and Dielectric Switching.

The combination of chirality and phase-transition materials has broad application prospects. Therefore, based on the quasi-spherical theory and the thought strategy of introducing chirality, we have successfully synthesized a pair of chiral enantiomeric ligands (R/S)-triethyl-(2-hydroxypropyl)ammonium iodide, which can be combined with a tin hexachloride anion to obtain a pair of new organic-inorganic hybrid enantiomeric high-temperature plastic phase-transition materials: (R/S)-[CH3 CH(OH)CH2 N(CH2 CH3 )3 ]2 SnCl6 (1-R/1-S), which have a high temperature phase transition of Tc =384 K, crystallize in the P21 chiral space group at room temperature, and have obvious CD signals. In addition, compounds 1-R and 1-S have a good low-loss dielectric switch and broadband gap. This work is conducive to the research into chiral high-temperature reversible plastic phase-transition materials, and promotes the development of multi-functional phase-transition materials.

Theoretical Investigation into a Possibility of Formation of Propylene Oxide Homochirality in Space.

The preferential synthesis or destruction of a single enantiomer by ultraviolet circularly polarized light (UV-CPL) has been proposed as a possible triggering mechanism for the extraterrestrial origin of homochirality. Herein, we investigate the photoabsorption property of propylene oxide (c-C3H6O) for UV-CPL in the Lyman-α region. Our calculations show that c-C3H6O was produced by CH3+ and CH3CH(OH)CH3 or C3H7• and O (triplet). The computed electronic circular dichroism spectra show that c-C3H6O and the intermediate (CH3CH(OH)CH2+) could absorb the UV-CPL originating from the Lyman-α emitter spectrum, suggesting that the photolysis of c-C3H6O or CH3CH(OH)CH2+ upon irradiation could induce chiral symmetry breakage.

Evaluation of the daytime tropospheric loss of 2-methylbutanal

Abstract. Saturated aldehydes, e.g. 2-methylbutanal (2 MB, CH3CH2CH(CH3)C(O)H), are emitted into the atmosphere by several biogenic sources. The first step in the daytime atmospheric degradation of 2 MB involves gas-phase reactions initiated by hydroxyl (OH) radicals, chlorine (Cl) atoms, and/or sunlight. In this work, we report the rate coefficients for the gas-phase reaction of 2 MB with OH (kOH) and Cl (kCl), together with the photolysis rate coefficient (J), in the ultraviolet solar actinic region in Valencia (Spain) at different times of the day. The temperature dependence of kOH was described in the 263–353 K range by the following Arrhenius expression: kOH(T)=(8.88±0.41)×10-12 exp[(331±14)/T] cm3 molec.−1 s−1. At 298 K, the reported kOH and kCl are (2.68±0.07)×10-11 and (2.16±0.32)×10-10 cm3 molec.−1 s−1, respectively. Identification and quantification of the gaseous products of the Cl reaction and those from the photodissociation of 2 MB were carried out in a smog chamber by different techniques (Fourier transform infrared spectroscopy, proton transfer time-of-flight mass spectrometry, and gas chromatography coupled to mass spectrometry). The formation and size distribution of secondary organic aerosols formed in the Cl reaction were monitored by a fast mobility particle sizer spectrometer. A discussion on the relative importance of the first step in the daytime atmospheric degradation of 2 MB is presented together with the impact of the degradation products in marine atmospheres.

In Situ Characterization of Mixtures of Linear and Branched Hydrocarbons Confined within Porous Media Using 2D DQF-COSY NMR Spectroscopy.

The analysis of 1D anti-diagonal spectra from the projections of 2D double-quantum filtered correlation spectroscopy NMR spectra is presented for the determination of the compositions of liquid mixtures of linear and branched alkanes confined within porous media. These projected spectra do not include the effects of line broadening and therefore retain high-resolution information even in the presence of inhomogeneous magnetic fields as are commonly found in porous media. A partial least-square regression analysis is used to characterize the mixture compositions. Two case studies are considered. First, mixtures of 2-methyl alkanes and n-alkanes are investigated. It is shown that estimation of the mol % of branched species present was achieved with a root-mean-square error of prediction (RMSEP) of 1.4 mol %. Second, the quantification of multicomponent mixtures consisting of linear alkanes and 2-, 3-, and 4-monomethyl alkanes was considered. Discrimination of 2-methyl and linear alkanes from other branched isomers in the mixture was achieved, although discrimination between 3- and 4- monomethyl alkanes was not possible. Compositions of the linear alkane, 2-methyl alkane, and the total composition of 3- and 4-methyl alkanes were estimated with a RMSEP <3 mol %. The approach was then used to estimate the composition of the mixtures in terms of submolecular groups of CH3CH2, (CH3)2CH, and CH2CH(CH3)CH2 present in the mixtures; a RMSEP <1 mol % was achieved for all groups. The ability to characterize the mixture compositions in terms of molecular subgroups allows the application of the method to characterize mixtures containing multimethyl alkanes. The motivation for this work is to develop a method for determining the mixture composition inside the catalyst pores during Fischer–Tropsch synthesis. However, the method reported is generic and can be applied to any system in which there is a need to characterize mixture compositions of linear and branched alkanes.

Physical properties and interaction studies for polyethylene glycol 200 and 1,2-propanediamine system at temperature from 293.15 to 318.15 K under atmospheric pressure

In this work, density(ρ) and viscosity(η) of polyethylene glycol 200(PEG 200) and 1,2-propanediamine(1,2-PDA) system were measured at temperature from 293.15 to 318.15 K with temperature difference about 5 K under atmospheric pressure condition. In accordance with ρ and η, the excess molar volume (VmE), the thermal expansion coefficient(αp), viscosity deviation(Δη), and the viscosity activation free energy(ΔG*E) were computed and corrected with Redlich-Kister(R-K) equation. In addition, the viscosity values of PEG 200 and 1,2-PDA system were fitted with the three-body McAllister semi-empirical models. The intermolecular interactions between PEG 200 and 1,2-PDA were analyzed by FTIR, UV–vis, and Fluorescence spectral results, which were intermolecular hydrogen bond, and the interaction mode was expressed as follow: CH3CH(NH2) CH2(H2)N⋯H-OCH2CH2-.According to the data of VmE and ΔG*E, it is known that when the molar ratio of PEG to 1,2-PDA was about 1:1, the interaction is strongest. Theoretically, CO2 capture absorption with this system can effectively inhibit the volatilization of amines.

Molecularly "clicking" active moieties to germanium-based inorganic 2D materials.

Two dimensional materials beyond graphene are in forefront research. Two dimensional analogues of graphene of group 14, germanene, are of high importance for their electronic and optical properties. The commonly used deintercalation fabrication approach has reached a major bottleneck in the field due to the lack of versatility derived from the limited library of precursors available for 2D-Ge functionalization with terminal groups. Thus, a chemical procedure that would allow for the on-demand synthesis of functional 2D-Ge derivatives with tuned physicochemical features for task-specific applications is of utmost importance to advance in the field. To fill this gap, click chemistry is herein presented as a straightforward "one-pot" synthetic strategy to simply reach functional 2D-Ge derivatives by covalently assembling ad hoc thiol-rich active molecular components (R'-SH) upon commercially available allyl 2D-Ge (2D-Ge-CH2CHCH2) by taking advantage of a photoinduced thiol-ene click reaction. Consequently, the combination of molecular engineering and Ge-based 2D materials through click chemistry supposes a step forward towards the achievement of a new family of smart 2D-Ge-CH2CH2CH2S-R' derivatives with different (supra)molecular responsiveness, which goes beyond the state-of-the-art in the field. This approach of functionalization of 2D monoelemental post-graphene material germanene is highly innovative and shall provide universal way of functionalization of germananes.

Synthesis of folded H-stacking skipped π polymers consisting of different 2-substituted trimethylene tethering units and their optical and conductive property

A series of polymers P1–P4 ([–CH2CH(Z)CH2–(π conjugated unit)–]n, where Z = a bulky substituent) were synthesized via the Suzuki–Miyaura coupling polymerization and predominantly existed in their folded H-stacking form in the solution and film, which was evidenced by ultraviolet absorption, fluorescent behavior, and X-ray diffraction analysis. The morphology of the polymers in the solid states was dependent on the structure of the Z group present. The conductive nature of P1–P4 was preliminarily demonstrated on hole-only devices. Moreover, a similar onset voltage was observed for P1–P3, which all contained the same π units; however, their current–voltage characteristics were highly dependent on the Z structure. P4, which contained cross-conjugated π units, exhibited a relatively high conductivity with a lower onset requirement.

Acyclic nucleoside phosphonates containing the amide bond: hydroxy derivatives

To study the influence of a linker rigidity and changes in donor–acceptor properties, three series of nucleotide analogs containing a P–X–HN–C(O)– residue (X=CH(OH)CH2, CH(OH)CH2CH2, CH2CH(OH)CH2) as a replacement for the P–CH2–O–CHR– fragment in acyclic nucleoside phosphonates, e.g., adefovir, cidofovir, were synthesized. EDC proved to provide good yields of the analogs from the respective ω-amino-1- or -2-hydroxyalkylphosphonates and nucleobase-derived acetic acids. New phosphorus–nucleobase linkers are characterized by two fragments of the restricted rotation within amide bonds and in four-atom units (P–CH(OH)–CH2–N, P–CH(OH)–CH2–C and P–CH2–CH(OH)–C) in which antiperiplanar disposition of P and N/C atoms was deduced from 1H and 13C NMR spectral data. The synthesized analogs P–X–HNC(O)–CH2B [X=CH(OH)CH2, CH(OH)CH2CH2, CH2CH(OH)CH2] appeared inactive in antiviral assays on a wide variety of DNA and RNA viruses at concentrations up to 100 μM, while two phosphonates showed cytostatic activity towards myeloid leukemia (K-562) and multiple myeloma cells (MM.1S) with IC50 of 28.8 and 40.7 μM, respectively.Graphical abstract

Micellization and Adsorption Properties of New Cationic Gemini Surfactants Having Hydroxyisopropyl Group

A series of cationic gemini surfactants, N,N′-bis(alkyl)-N,N′-bis(2-hydroxypropyl)ethylenediammonium dibromide, [CnH2n+1(CH3CH(OH)CH2)NH(CH2)2NH(CH2CH(OH)CH3)CnH2n+1]Br2 (where n is the tail chain length, n = 9, 12, and 14), referred to as CnC2Cn[iso-Pr(OH)] was synthesized. Via conductometric and tensiometric methods, at different temperatures (283 to 313 K), specific electrical conductivities and surface tensions of the aqueous solutions of these cationic gemini surfactants were determined. According to the obtained values, micellization and adsorption parameters such as critical micellization concentration (CMC), maximum surface excess (Γmax), minimal cross sectional surface area of surfactant polar group (Amin), adsorption efficiency (pC20), surface pressure (π), and binding degree of counterion (β) were calculated. The values of standard Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) were also computed. Via the dynamic light scattering method, diameters of aggregates of the synthesized ca...

Synthesis and Reactivity of Palladium(II) Alkyl Complexes that Contain Phosphine-cyclopentanesulfonate Ligands

The synthesis of the phosphine-cyclopentanesulfonate pro-ligands Li/K[2-PPh2-cyclopentanesulfonate] (Li/K[2a]), Li/K[2-P(2-OMe-Ph)2-cyclopentanesulfonate] (Li/K[2b]), and H[2b], and the corresponding Pd(II) alkyl complexes (κ2-P,O-2a)PdMe(pyridine) (3a) and (κ2-P,O-2b)PdMe(pyridine) (3b) is described. The sulfonate-bridged base-free dimer {(2b)PdMe}2 (4b) was synthesized by abstraction of pyridine from 3b using B(C6F5)3. The borane-coordinated base-free dimer [{2b·B(C6F5)3}PdMe]2 (5b), in which B(C6F5)3 binds to a sulfonate oxygen, was prepared by addition of 1 equiv of B(C6F5)3 per Pd to 4b or addition of 2 equiv of B(C6F5)3 to 3b. Compounds 3b, 4b, and 5b polymerize ethylene with low activity (up to 210 kg mol–1 h–1 at 250 psi and 80 °C) to linear polyethylene (Mn = 1950–5250 Da) with predominantly internal olefin placements. 3b and 4b copolymerize ethylene with methyl acrylate to linear copolymers that contain up to 11.7 mol % methyl acrylate, which is incorporated as −CH2CH(CO2Me)CH2– (80%) in-chain u...

Mass spectrometric monitoring of oxidation of aliphatic C6-C8 hydrocarbons and ethanol in low pressure oxygen and air plasmas.

Experimental and theoretical studies on the oxidation of saturated hydrocarbons (n-hexane, cyclohexane, n-heptane, n-octane and isooctane) and ethanol in 28 Torr O2 or air plasma generated by a hollow cathode discharge ion source were made. Ions corresponding to [M + 15]+ and [M + 13]+ in addition to [M - H]+ and [M - 3H]+ were detected as major ions where M is the sample molecule. The ions [M + 15]+ and [M + 13]+ were assigned as oxidation products, [M - H + O]+ and [M - 3H + O]+ , respectively. By the tandem mass spectrometry analysis of [M - H + O]+ and [M - 3H + O]+ , H2 O, olefins (and/or cycloalkanes) and oxygen-containing compounds were eliminated from these ions. Ozone as one of the terminal products in the O2 plasma was postulated as the oxidizing reagent. As an example, the reactions of C6 H14+• with O2 and of C6 H13+ (CH3 CH2 CH+ CH2 CH2 CH3 ) with ozone were examined by density functional theory calculations. Nucleophilic interaction of ozone with C6 H13+ leads to the formation of protonated ketone, CH3 CH2 C(=OH+ )CH2 CH2 CH3 . In air plasma, [M - H + O]+ became predominant over carbocations, [M - H]+ and [M - 3H]+ . For ethanol, the protonated acetic acid CH3 C(OH)2+ (m/z 61.03) was formed as the oxidation product. The peaks at m/z 75.04 and 75.08 are assigned as protonated ethyl formate and protonated diethyl ether, respectively, and that at m/z 89.06 as protonated ethyl acetate. Copyright © 2016 John Wiley & Sons, Ltd.

Synthesis and In Vitro Pharmacological Evaluation of 5-(Alkoxymethyl)-2-(3-alkylamino-2-hydroxypropoxy)phenylethanones Related to Acebutolol and Celiprolol.

The structure-activity relationships of 13 analogs of aryloxyaminopropanol type derived from 2-hydroxyphenylethanone as potential β-blockers are described. The synthesized compounds possess an isopropyl or a tert-butyl group in the hydrophilic part of the molecule and an alkoxymethyl substitution in the lipophilic moiety. The target compounds were prepared by an established four-step method and their structures were confirmed by interpretation of their UV, IR, (1) H NMR and (13) C NMR spectra, and by elemental analysis. The β-adrenolytic efficacy of the prepared racemic compounds was determined on isolated guinea pig atria (β1 ) and trachea (β2 ) and expressed as pA2 values against isoprenaline tachycardia. The assumed cardioselectivity was expressed as β1 /β2 ratio and the values of compounds with an alkoxy group (CH3 O, iC3 H5 O, C5 H11 O, CH2 CHCH2 O, CH3 OCH2 CH2 O) in the lipophilic part and with tert-butyl in the hydrophilic part of the molecule were found to be comparable or higher than those of the standards acebutolol and celiprolol. All evaluated substances at a concentration of 10(-7) mol/dm(3) showed also negative chronotropic effects.

Insertion Homo- and Copolymerization of Diallyl Ether.

The previously unresolved issue of polymerization of allyl monomers CH2 CHCH2 X is overcome by a palladium-catalyzed insertion polymerization of diallyl ether as a monomer. An enhanced 2,1-insertion of diallyl ether as compared to mono-allyl ether retards the formation of an unreactive five-membered cyclic O-chelate (after 1,2-insertion) that otherwise hinders further polymerization, and also enhances incorporation in ethylene polymers (20.4 mol %). Cyclic ether repeat units are formed selectively (96 %-99 %) by an intramolecular insertion of the second allyl moiety of the monomer. These features even enable a homopolymerization to yield polymers (poly-diallyl ether) with degrees of polymerization of DPn ≈44.

Computational protocol to predict hyperpolarizabilities of large π-conjugated organic push–pull molecules

The first hyperpolarizability (β) for a set of 21 large π-conjugated organic push–pull molecules is predicted using an affordable computational protocol. Static -β(0)- and frequency-dependent -β(−2ω; ω,ω)- total first hyperpolarizability were calculated, using density functional theory (DFT) at the cam-B3LYP/NLO-V// level, where the NLO-V basis set was developed specifically for predicting nonlinear optics (NLO) properties. The average absolute deviations were 158 and 392 (in units of 10−30 esu) for β(0) and β(0.67 eV), respectively, in the gas phase. These errors correspond, on average, to 49% and 65% of the experimental values. The inclusion of solvent effects (CHCl3) through a continuum model slightly improves the predictions of β(0.67 eV), with absolute error decreasing to 265 (in units of 10−30 esu), corresponding to an error of 35%. For the julolidinyl-(CHCH)2–C(CH3) = CH–CHCH–CHC(CH3)–CHCH–CHN,N'-diethylthiobarbituric acid (molecule st_5_6, Graphical Abstract), which presents the highest NLO response among the compounds analyzed, the calculated value for μβ(0.67 eV) in CHCl3 was 40,255 × 10−48 esu, in satisfactory accordance with the experimental data, 34,779 × 10−48 esu (an error of 16% only). In addition, the two-states approach was applied for the set of molecules studied, and the results showed that the increase in total β is explained well by the charge transfer excitation, involving the frontier orbitals. Therefore, the computational protocol, based on the cam-B3LYP/NLO-V// level, should be considered an affordable and reliable calculation scheme to predict very high first hyperpolarizability for large π-conjugated organic molecules.

Comparative study of gamma-irradiated PP and PE polyolefins part 1: Identification and quantification of radicals using electron paramagnetic resonance

Three grades of polypropylene (PP) and two grades of polyethylene (PE) were γ-irradiated with 25 kGy integral dose in air atmosphere and investigated using X-band electron paramagnetic resonance (EPR). All the spectra exhibited a mixture of free radicals, the absolute spin concentration of which was obtained from EPR signal simulations and intensity calibration using references of known spin concentrations. The free radicals were identified and their concentrations were related to both formulation and crystallinity of the polymer. The recombination of each species was monitored versus temperature. The concentration decay versus time concentration was monitored and simulated as a mixture of zero or first order mechanism for HDPE and of one for the PP polymers. In the highly crystalline High Density Polyethylene HDPE, γ-irradiation produces mainly alkyl radicals (R) and some alkyloxyl (RO) formed in low mobility phases where dioxygen has poor accessibility. Heating at 330 K destabilizes the alkyloxyl that disappears while allylic radicals (R–CHCH–CH2) show up as a fingerprint of β-scission. At 290 K in HDPE, the radical concentration decays rather rapidly according to a single exponential decay. A residual concentration of allyl and alkyl radicals (zero order mechanism) is assigned to radicals located in the largest crystallized zones of very weak molecular mobility. In contrast, low density PE or PP exhibit mostly oxidised radicals of alkylperoxyl (R–OO) type that are rather stable in PP (time constant τ ∼ 70 h), the decay of the non-oxydized part is much faster (τ ∼ 2 h) in PP. The higher concentration of radicals in PP than in HDPE (τ ∼ 8 h) is then attributed to the oxidised radicals while highly stable radicals (zero order mechanism) are consistent with a low density material.

Aspartic acid in a new role: Synthesis and application of a pH-responsive cyclopolymer containing residues of the amino acid

The reaction between diallylamine and dimethyl maleate afforded the Michael addition product dimethyl N,N-diallylaspartate [(CH2CH–CH2)2NCH(CO2Me)CH2CO2Me] I, which upon treatment with dry HCl and ester hydrolysis with aqueous HCl gave its hydrochloride salt [(CH2CH–CH2)2NH+CH(CO2Me)CH2CO2Me Cl−] II and N,N-diallylaspartic acid hydrochloride [(CH2CH–CH2)2NH+CH(CO2H)CH2CO2H Cl−] III, respectively. The new monomers II and III underwent cyclopolymerization to give, respectively, cationic polyelectrolytes (CPEs) poly(II) and poly(III). Under the influence of pH, triprotic acid (+) poly(III) was equilibrated to water-insoluble diprotic polyzwitterionic acid (±) IV, water-soluble monoprotic poly(zwitterion–anion) (± −) V, and its conjugate base polydianion (=) VI. The protonation constants of the carboxyl group and trivalent nitrogen in VI have been determined. A 20-ppm concentration of IV is effective in inhibiting the precipitation of CaSO4 from its supersaturated solution with an ≈100% scale inhibition efficiency for a duration of 50h at 40°C. The aqueous two-phase systems (ATPSs) of VI and polyoxyethylene have been studied. The transformation of water-soluble VI to insoluble IV makes it a recycling ATPS as it can be recycled by precipitation at a lower pH.

A recyclable heavy fluorous tag carrying an allyl alcohol pendant group: design and evaluation toward applications in synthetic carbohydrate chemistry

Toward applications in synthetic carbohydrate chemistry, we converted our previous acid-resistant heavy fluorous tag [(Rf)3C–CH2–OH, 1] to allyl alcohol derivatives [(Rf)3C–CH2–O–(CH2)n–CHCH–CH2–OH, 3 (n=1) or 4 (n=3)] by means of olefin cross metathesis. They were then subjected to β-glycosylation reactions by using a series of glycosyl donors, including glycosyl bromide and trichloroacetimidates. The terminal OH group in 3 and 4 was found to be β-glycosylated in moderate yield when 2,3,4,6-tetra-O-benzoyl-d-galactosyl trichloroacetimidate was used as the glycosyl donor. Upon a detachment reaction using Pd(PPh3)4, the initial heavy fluorous tag 1 was recovered in high yield (>90%) together with 1-hydroxy sugar, indicating that not only the allyl ether linkage in the glycosides but also the internal di-alkyl ether linkage in 4 be cleaved by the action of the Pd-catalyst enabling long-range olefin transmigration. Potential utility was demonstrated by using the tetra-O-benzoyl-β-d-galactosylated derivative of 3 in a series of deprotection, protection and glycosylation reactions, which were conductible in high yields without using chromatographic purification process. These findings prompt us to propose a general scheme in which the acid-resistant heavy fluorous compound 1 is applied as a recyclable tag in synthetic carbohydrate chemistry.

FTIR gas kinetic study of the reactions of ozone with a series of hexenols at atmospheric pressure and 298 K

Relative rate coefficients of the reactions of O3 with (Z)-3-hexen-1-ol, (E)-3-hexen-1-ol and (E)-2-hexen-1-ol have been determined in an environmental chamber with in situ FTIR detection of the reactants at 298K and 760Torr. The following rate coefficients (in units of 10−17cm3molecule−1s−1) have been determined: (6.04±0.95) for (Z)-CH2(OH)CH2CHCHCH2CH3; (5.83±0.86) for (E)-CH2(OH)CH2CHCHCH2CH3; (5.98±0.73) for (E)-CH2(OH)CHCH(CH2)2CH3. This is the first kinetic study for the reactions of O3 with (E)-2-hexen-1-ol and (E)-3-hexen-1-ol. Reactivity trends are developed and the atmospheric persistence of these compounds is calculated based on the rate coefficients.

Electrochemistry and structural properties of new mixed ligand nickel(ii) complexes based on thiosemicarbazone

Mixed ligand nickel(II) complexes of 5-chloro-2-hydroxybenzophenone-N-R-thiosemicarbazone (R: –CH3 (L1), –CH2–CHCH2 (LII)) and triphenylphosphine were synthesized. The structures of the complexes were characterized by elemental analysis, IR, 1H and 31P NMR spectroscopy, conductivity, electrochemical and magnetic moment measurements, and single-crystal X-ray diffraction technique. The two nickel(II) complexes have a square planar geometry containing O, N, and S atoms of the thiosemicarbazone, and the P atom of triphenylphosphine. The electrochemical behaviors of the thiosemicarbazone ligands and the nickel complexes were studied using cyclic voltammetry and square wave voltammetry. The redox processes of the compounds were significantly influenced by the central metal ions and the nature of the substituents on the thiosemicarbazones, which are the important factors in controlling the redox properties. In situ spectroelectrochemical studies were employed to determine the colors and spectra of the electro-generated species of the complexes.

Reactions of Aromatic S- and O-Enynes with Two Methyl Substituents on the Olefinic Unit Assisted by a Ruthenium Complex: Tandem Cyclization and Product Selectivity

Ruthenium-assisted cyclizations of two enynes, HC≡CCH(OH)(C6H4)X-CH2CH=CMe2 (X=S (1a), O (1b)), each of which contains two terminal methyl substituents on the olefinic parts, are explored. The reaction of 1a in CH2Cl2 gives the vinylidene complex 2a from the first cyclization and two side products, 3a and the carbene complex 4a with a benzothiophene ligand. The same reaction in the presence of HBF4 affords 4a exclusively. Air oxidation of 4a in the presence of Et3N readily gives an aldehyde product. In MeOH, tandem cyclizations of 1a generate a mixture of the benzothiochromene compound 10a and the carbene complex 7a also with a benzothiochromene ligand. First, cyclization of 1b likewise proceeds in CH2Cl2 to give 2b. Tandem cyclization of 1b in MeOH yields comparable products 10b and 7b with benzochromene moieties, yet with no other side product. The reaction of [Ru]Cl with HC≡CCH(OH)(C6H4)S-CH2CH=CH2 (1c), which contains no methyl substituent in the olefinic part, in MeOH gives the carbene complex 15c with an unsubstituted thiochromene by means of a C-S bond formation. Structures of 3a and 15c are confirmed by X-ray diffraction analysis. The presence of methyl groups of enynes 1a and 1b promotes sequential cyclization reactions that involve C-C bond formation through carbocationic species.