Methyl ganoderate H

A novel assessment of the role of the methyl radical and water formation channel in the CH3OH + H reaction.[Pubmed:28890979]

Phys Chem Chem Phys. 2017 Sep 20;19(36):24467-24477.

A number of experimental and theoretical papers accounted almost exclusively for two channels in the reaction of atomic hydrogen with methanol: H-abstraction from the methyl (R1) and hydroxyl (R2) functional groups. Recently, several astrochemical studies claimed the importance of another channel for this reaction, which is crucial for kinetic simulations related to the abundance of molecular constituents in planetary atmospheres: methyl radical and water formation (R3 channel). Here, motivated by the lack of and uncertainties about the experimental and theoretical kinetic rate constants for the third channel, we developed first-principles Car-Parrinello molecular dynamics thermalized at two significant temperatures - 300 and 2500 K. Furthermore, the kinetic rate constant of all three channels was calculated using a high-level deformed-transition state theory (d-TST) at a benchmark electronic structure level. d-TST is shown to be suitable for describing the overall rate constant for the CH3OH + H reaction (an archetype of the moderate tunnelling regime) with the precision required for practical applications. Considering the experimental ratios at 1000 K, kR1/kR2 approximately 0.84 and kR1/kR3 approximately 15-40, we provided a better estimate when compared with previous theoretical work: 7.47 and 637, respectively. The combination of these procedures explicitly demonstrates the role of the third channel in a significant range of temperatures and indicates its importance considering the thermodynamic control to estimate methyl radical and water formation. We expect that these results can help to shed new light on the fundamental kinetic rate equations for the CH3OH + H reaction.

Crystal structure of {(R)-N(2)-[(benzo[h]quinolin-2-yl)meth-yl]-N(2')-[(benzo[h]quinolin-2-yl)methyl-i dene]-1,1'-binaphthyl-2,2'-di-amine-kappa(4)N,N',N'',N'''}(trifluoromethane-sulfo nato-kappaO)zinc(II)} trifluoromethane-sulfonate di-chloro-methane 1.5-solvate.[Pubmed:28775858]

Acta Crystallogr E Crystallogr Commun. 2017 Jun 2;73(Pt 7):949-953.

The zinc(II) atom in the title compound, [Zn(C48H31N4)(CF3SO3)](CF3SO3).1.5CH2Cl2, adopts a distorted five-coordinate square-pyramidal geometry. It is coordinated by one tri-fluoro-methane-sulfonate ligand and four N atoms of the N(2)-[(benzo[h]quinolin-2-yl)meth-yl]-N(2')-[(benzo[h]quinolin-2-yl)methyl-idene] -1,1'-binaphthyl-2,2'-di-amine ligand. The complex is present as a single-stranded P-helimer monohelical structure incorporating pi-pi and/or sigma-pi inter-actions. One of the imine bonds present in the original ligand framework is reduced, leading to variations in bond lengths and torsion angles for each side of the ligand motif. The imine-bond reduction also affects the bond lengths involving the metal atom with the N-donor atoms located on the imine bond. There are two mol-ecules of the complex in the asymmetric unit. One of the mol-ecules exhibits positional disorder within the coordinating tri-fluoro-methane-sulfonate ion making the mol-ecules symmetric-ally non-equivalent.

Nucleoside-O-Methyl-(H)-Phosphinates: Novel Monomers for the Synthesis of Methylphosphonate Oligonucleotides Using H-Phosphonate Chemistry.[Pubmed:28921496]

Curr Protoc Nucleic Acid Chem. 2017 Sep 18;70:4.76.1-4.76.22.

This unit comprises the straightforward synthesis of protected 2'-deoxyribonucleoside-O-methyl-(H)-phosphinates in both 3'- and 5'-series. These compounds represent a new class of monomers compatible with the solid-phase synthesis of oligonucleotides using H-phosphonate chemistry and are suitable for the preparation of both 3'- and 5'-O-methylphosphonate oligonucleotides. The synthesis of 4-toluenesulfonyloxymethyl-(H)-phosphinic acid as a new reagent for the preparation of O-methyl-(H)-phosphinic acid derivatives is described. (c) 2017 by John Wiley & Sons, Inc.

Development of a ReaxFF Force Field for Cu/S/C/H and Reactive MD Simulations of Methyl Thiolate Decomposition on Cu (100).[Pubmed:28981284]

J Phys Chem B. 2018 Jan 18;122(2):888-896.

It has been shown that the rate of decomposition of methyl thiolate species on copper is accelerated by sliding on a methyl thiolate covered surface in ultrahigh vacuum at room temperature. The reaction produces small gas-phase hydrocarbons and deposits sulfur on the surface. Here, a new ReaxFF potential was developed to enable investigation of the molecular processes that induce this mechanochemical reaction by using density functional theory calculations to tune force field parameters for the model system. Various processes, including volumetric expansion/compression of CuS, CuS2, and Cu2S unit cells; bond dissociation of Cu-S and valence angle bending of Cu-S-C; the binding energies of SCH3, CH3, and S atoms on a Cu surface; and energy for the decomposition of methyl thiolate molecular species on copper, were used to identify the new ReaxFF parameters. Molecular dynamics simulations of the reactions of adsorbed methyl thiolate species at various temperatures were performed to demonstrate the validity of the new potential and to study the thermal reaction pathways. It was found that reaction is initiated by C-S bond scission, consistent with experiments, and that the resulting methyl species diffuse on the surface and combine to desorb ethane, also as found experimentally.

Ir-Catalyzed Enantioselective, Intramolecular Silylation of Methyl C-H Bonds.[Pubmed:28820264]

J Am Chem Soc. 2017 Sep 6;139(35):12137-12140.

We report highly enantioselective intramolecular, silylations of unactivated, primary C(sp(3))-H bonds. The reactions form dihydrobenzosiloles in high yields with excellent enantioselectivities by functionalization of enantiotopic methyl groups under mild conditions. The reaction is catalyzed by an iridium complex generated from [Ir(COD)OMe]2 and chiral dinitrogen ligands that we recently disclosed. The C-Si bonds in the enantioenriched dihydrobenzosiloles were further transformed to C-Cl, C-Br, C-I, and C-O bonds in final products. The potential of this reaction was illustrated by sequential C(sp(3))-H and C(sp(2))-H silylations and functionalizations, as well as diastereoselective C-H silylations of a chiral, natural-product derivative containing multiple types of C-H bonds. Preliminary mechanistic studies suggest that C-H cleavage is the rate-determining step.