1665-01-6Relevant academic research and scientific papers
[Cl@Si20H20]-: Parent Siladodecahedrane with Endohedral Chloride Ion
Bamberg, Marcel,Bolte, Michael,Brandl, Matthias,Bursch, Markus,Grimme, Stefan,Hansen, Andreas,Kunze, Lukas,Lerner, Hans-Wolfram,Sentis, Gabriele,Wagner, Matthias
, p. 10865 - 10871 (2021)
Fullerenes and diamondoids are at the core of nanoscience. Comparable monodisperse silicon analogues are scarce. Herein, we report the synthesis of the parent siladodecahedrane, which represents the largest Platonic solid. It shares its pattern of pentagonal faces with the smallest fullerene, C20, and its saturated, H-terminated skeleton with diamondoids. Similar to endofullerenes, the silicon cage encapsulates a chloride ion ([Cl@Si20H20]-); similar to diamondoids, its Si-H termini offer a wealth of opportunities for further functionalization. Mere treatment with chloromethanes leads to the perchlorinated cluster [Cl@Si20Cl20]-. Both compounds were characterized by mass spectrometry, X-ray crystallography, NMR spectroscopy, and quantum-chemical calculations. The experimentally determined 35Cl resonances of the endohedral chloride ions are particularly diagnostic to probe the Cl- → Si20 interaction strength as a function of the different surface substituents, as we have proven by high-level computational analyses.
Kinetic and theoretical study of the hydrodechlorination of CH 4- xClx (x = 1-4) compounds on palladium
Chen, Nan,Rioux, Robert M.,Barbosa, Luis A. M. M.,Ribeiro, Fabio H.
, p. 16615 - 16624 (2010)
The reaction kinetics of hydrodechlorination (HDCl) for a series of CH 4-xClx (x = 1-4) compounds were measured on a Pd/carbon catalyst. The rate of HDCl correlated with the C-Cl bond energy, suggesting scission of this bond in the molecularly adsorbed molecule is rate-determining. The measured reaction kinetics of the CH4-xClx compounds support a previously proposed Langmuir-Hinshelwood type reaction mechanism. Kinetic and isotope exchange experiments demonstrated the following: gas phase H2 and HCl are in equilibrium with surface H and Cl; adsorbed Cl is the most abundant surface intermediate; and irreversible scission of the first C-Cl bond is rate-determining. The overall hydrodechlorination reaction rate can be written as kKR-Cl[R-Cl]/(1 + KHCl[HCl]/KH2 1/2[H2]1/2). The activation energy of the rate-determining step was related linearly to the dissociation energy of the first C-Cl bond broken in a Broensted-Evans-Polanyi relationship. This behavior is in agreement with a previous study of CF3CF 3-xClx compounds. During the reaction of CH3Cl, CH2Cl2, and CHCl3 with deuterium, H-D exchange occurred in only 2%, 6%, and 9% of products, respectively. The increasing H-D exchange with Cl content suggests the steps which determine selectivity in these multipath, parallel reactions. The density functional theory (DFT)-calculated activation energies for the dissociation of the first C-Cl bond in the family of chlorinated methane compounds are in good agreement with the values extracted from kinetic modeling, suggesting that parameters estimated from DFT calculations may be used to estimate the reactivity of a particular chlorinated compound within a family of chlorocarbons.
Involvement of Exciplexes in the Photolysis of Aliphatic Ketones in Deuteriochloroform: CIDNP Evidence
Zhang, Mao-Xi,Liu, Zhong-Li,Wu, Lung-Min,Liu, You-Cheng
, p. 451 - 454 (1989)
Photolysis of 4-acetyl-4-ethoxyformylcyclohexanone and 4-acetyl-4-phenylcyclohexanone in deuteriochloroform showed an unusual polarization which suggests that a singlet exciplex of the ketone with deuteriochloroform may be involved in the Norrish type I reaction.KEY WORDS - Photolysis Ketones CIDNP Exciplex
Formation of [NiIII(κ1-S2CH)(P(o- C6H3-3-SiMe3-2-S)3)]- via CS2 insertion into nickel(III) hydride containing [Ni III(H)(P(o-C6H3-3-SiMe3-2-S) 3)]-
Lai, Kuan-Ting,Ho, Wei-Chieh,Chiou, Tzung-Wen,Liaw, Wen-Feng
, p. 4151 - 4153 (2013/05/22)
Insertion of CS2 into the thermally unstable nickel(III) hydride [PPN][Ni(H)(P(o-C6H3-3-SiMe3-2-S) 3)] (1), freshly prepared from the reaction of [PPN][Ni(OC 6H5)P(C6H3-3-SiMe 3-2-S)3] and 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (HBpin; pin = OCMe2CMe2O) in tetrahydrofuran at -80 C via a metathesis reaction, readily affords [PPN] [NiIII(κ1-S2CH)(P(o-C6H 3-3-SiMe3-2-S)3)] (2) featuring a κ1-S2CH moiety.
Kinetics of reactions of CN with chlorinated methanes
Samant, Vaishali,Hershberger, John F.
experimental part, p. 64 - 67 (2009/02/04)
The kinetics of reactions of CN with the chlorinated methanes CH3Cl, CH2Cl2, CHCl3 and CCl4 were investigated over the temperature range 298-573 K, using laser induced fluorescence (LIF) spectroscopy. At 298 K, rate constants of 9.0 ± 0.3 × 10-13, 8.8 ± 0.4 × 10-13, 9.0 ± 0.5 × 10-13 and 4.3 ± 0.6 × 10-13 cm3 molecule-1 s-1 were measured, respectively. A small positive temperature dependence was observed, as well as kinetic isotope effects of kH/kD ～ 2.14-2.25. These data along with product detection experiments strongly suggest that hydrogen abstraction dominates these reactions.
Kinetic Isotope Effects for Proton Abstraction from Methanol by Polyhalogenomethyl Carbanions. Cleavage of Me3SiCHX2 and Me3SiCX3 by Base in Methanol.
Eaborn, Colin,Stanczyk, Wlodzimierz A.
, p. 471 - 473 (2007/10/02)
The carbanions XxH(3-x)C- (X=Cl or Br; x=2 or 3) generated by base cleavage of Me3SiCH(3-x)Xx (or some related compounds) in MeOH, show a kinetic isotope kH/kD of ca. 1.1 in proton abstraction from methanol, as given by the product ratio XxH(3-x)CH/XxH(3-x)CD observed for reaction in MeOH-MeOD (1:1) at ca. 21 deg C.The low value of the isotope effect is attributed to the fact that the free electron pair in the carbanion is localized on the carbon centre; carbanions derived from acids of acidities comparable with those of X3CH and X2CH2 but in which the electron pair is conjugatively delocalized, show much larger isotope effects.
Low-valent rhenium-oxo-alkoxide complexes: Synthesis, characterization, structure, and ligand exchange and carbon monoxide insertion reactions
Erikson, Torsten K. G.,Bryan, Jeffrey C.,Mayer, James M.
, p. 1930 - 1938 (2008/10/08)
A series of rhenium(III)-oxo-alkoxide-bis(acetylene) complexes of the form Re(O)(OR)(R′C≡CR′)2 have been prepared by reaction of the iodide derivatives Re(O)I(R′C≡CR′)2 with thallium alkoxides. An X-ray crystal structure of the phenoxide complex 7 a shows the pseudotetrahedral coordination geometry typical of Re(O)X(RC≡CR)2 compounds, with a short rhenium-oxo bond of 1.712 (13) ? and a longer Re-OPh distance of 1.966 (14) ?. The alkoxide complexes decompose in solution at less than 100°C by a number of pathways including β-hydrogen elimination. The complexes react rapidly with protic reagents such as alcohols, water, amines, acids, etc. with displacement of alcohol. Reactions of the tert-butoxide complex with ammonia or methylamine yield the corresponding amide complexes, and H2S gives the hydrosulfide species. Many of these ligand exchange reactions give equilibrium mixtures, indicating that the Re-X bond strengths in general parallel H-X bond strengths. The methylamide complex is fluxional on the NMR time scale, with a ground state that places the methyl group pointing at one of the acetylene ligands. The phenoxide ligand in the X-ray structure is approximately in the same sterically encumbered orientation. This orientation is preferred because it favors π-bonding and minimizes π-antibonding interactions of the π-donor orbital of the amide or phenoxide ligand. The ethoxide complex readily inserts carbon monoxide and isopropyl isocyanide to give Re(O)[C(O)OEt](MeC≡CMe)2 and Re(O)[C(N-i-Pr)OEt](MeC≡CMe)2, respectively. Crystal data for 7a: Pna21, a = 18.620 (7) ?, b = 7.2389 (9) ?, c = 10.552 (3) ?, Z = 4, refined to R = 0.044, Rw = 0.044.
