A kinetic study of the reactions of dimethyl sulfide bridged tetramethylplatinum(II) and octamethylplatinum(IV) complexes with dimethyl sulfide and bidentate ligands

1998 ◽  
Vol 76 (1) ◽  
pp. 62-70
Author(s):  
Katsuyuki Nakayama ◽  
Yuichi Kondo ◽  
Koji Ishihara
Keyword(s):  
High Pressure ◽  
Reaction Mechanism ◽  
Dimethyl Sulfide ◽  
Activation Parameters ◽  
Bidentate Ligand ◽  
Direct Reaction ◽  
Bidentate Ligands ◽  
High Pressure Kinetics ◽  
Subsequent Substitution ◽  
Rapid Conversion

Kinetics for the reactions of [1] [PtIV2Me8 (μ - SMe2 )2] + 2 Me 2S kf<-->kd 2[PtIVMe4 (SMe2 ) 2] [2] [PtII2Me4 (μ - SMe2 )2] + 2 Me 2S kf--> 2[PtIIMe2(SMe2 ) 2 ] and [3] [PtIV2Me8 (μ - SMe2 ) 2 ] + 2NN --> 2 [PtIVMe4 (NN)]+2Me2S where NN = bipy or 4,4'-Me2-bipy, have been studied at various temperatures and pressures. Reaction [3] was shown to consist of the rapid conversion of the dimer to a monomer and the much slower subsequent substitution of the dimethyl sulfide with bidentate ligand NN: [PtIV2Me8 (μ - SMe2 )2] + 2 Me 2S <--> 2 [PtIVMe4 (SMe2 ) 2 ] and [PtIVMe4(SMe2)2] + NN --> [PtIVMe4(NN)] + 2 Me2S The rate constants and activation parameters for the reactions are as follows: kf = 3.16 ± 0.06 M-1 s-1 (25°C), Δ H doubledaggerf= 51.8 ± 1.7 kJ mol-1, Δ S doubledaggerf= -61.0 ± 5.8 J mol-1 K-1, kd = 1.18 ± 0.22 M-1 s-1 (25°C), Δ H doubledaggerd= 65 ± 22 kJ mol-1, Δ S doubledaggerd= -26 ± 73 J mol-1 K-1 for reaction [1] in n-hexane; kf = 6.68 ± 0.06 M-1 s-1 (25°C), Δ H doubledaggerf= 58.0 ± 3.1 kJ mol-1, Δ S doubledaggerf= -34.5 ± 10.5 J mol-1 K-1, Δ V doubledaggerf= -10.7 ± 1.3 cm3 mol-1 for reaction [2] in dichloromethane; k2 = (7.09 ± 1.89) x 10-4 M-1 s-1, Δ H doubledagger2= 95 ± 21 kJ mol-1, and Δ S doubledagger2= 18 ± 70 J mol-1 K-1, Δ V doubledagger2= 9 ± 9 cm3 mol-1 for reaction [3] with bipy, and k1 = (1.10 ± 0.10) x 10-2 s-1, k3/k-1 = (4.33 ± 0.30) x 10-2, and k2 = (6.09 ± 1.35) x 10-4 M-1 s-1 for reaction [3] with 4,4'-Me2-bipy. It was shown that reactions [1] and [2] proceed nucleophilically without any intermediates, and reaction [3] proceeds through a mainly k2 path for NN = bipy and through both k1 and k2 paths for NN = 4,4'-Me2-bipy, without appreciable participation of the direct reaction between the dimer and NN as shown by the following reaction scheme.Key words: octamethylplatinum(IV) dimer, tetramethylplatinum(II) dimer, reaction mechanism, high-pressure kinetics.

High‐Pressure Kinetics and Highly Viscous Media

2002 ◽  
pp. 97-128 ◽  
Author(s):  
Tsutomu Asano
Keyword(s):  
High Pressure ◽  
Viscous Media ◽  
High Pressure Kinetics

scholarly journals A new lanthanum(III) complex containing acetylacetone and 1H-imidazole

2017 ◽  
Vol 73 (11) ◽  
pp. 1739-1742 ◽  
Author(s):  
Atsuya Koizumi ◽  
Takuya Hasegawa ◽  
Atsushi Itadani ◽  
Kenji Toda ◽  
Taoyun Zhu ◽  
...  
Keyword(s):  
Bidentate Ligand ◽  
Bidentate Ligands ◽  
Monodentate Ligand ◽  
Intermolecular Hydrogen Bonds ◽  
Molecular Plane ◽  
One Dimensional ◽  
Nitrate N ◽  
Dimensional Network ◽  
Monodentate Ligands ◽  
Nitrate Anions

In the title complex, diaqua(1H-imidazole-κN3)(nitrato-κ2O,O′)bis(4-oxopent-2-en-2-olato-κ2O,O′)lanthanum(III), [La(C5H7O2)2(NO3)(C3H4N2)(H2O)2], the La atom is coordinated by eight O atoms of two acetylacetonate (acac) anions acting as bidentate ligands, two water molecule as monodentate ligands, one nitrate anions as a bidentate ligand and one N atom of an imidazolate (ImH) molecule as a monodentate ligand. Thus, the coordination number of the La atom is nine in a monocapped square antiprismatic polyhedron. There are three types of intermolecular hydrogen bonds between ligands, the first involving nitrate–water O...H—O interactions running along the [001] direction, the second involving acac–water O...H—O interactions along the [010] direction and the third involving an Im–nitrate N—H...O interaction along the [100] direction (five interactions of this type). Thus, an overall one-dimensional network structure is generated. The molecular plane of an ImH molecule is almost parallel to that of a nitrate ligand, making an angle of only 6.04 (12)°. Interestingly, the ImH plane is nearly perpendicular to the planes of two neighbouring acac ligands.

scholarly journals Phase Transition and Polymerization of Acetonitrile under High Pressure

2014 ◽  
Vol 70 (a1) ◽  
pp. C763-C763
Author(s):  
Haiyan Zheng ◽  
Kuo Li ◽  
George Cody ◽  
Chris Tulk ◽  
Jamie Molaison ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Reaction Mechanism ◽  
Neutron Diffraction ◽  
Raman Spectra ◽  
Hydrogen Transfer ◽  
Layer Structure ◽  
Van Der Waals ◽  
Orthorhombic Phase ◽  
Organic Polymer

Successful application of high pressure on synthesis of organic polymer, including the conducting polymer and super hard materials depends on the knowledge of reaction mechanism. The evolution of crystal structure under high pressure especially the structure close to transition pressure is crucial to conclude the reaction mechanism. Nitriles represent a large class of interstellar molecules and are the potential source of amino acids. Understanding its behavior at extreme conditions has gained increasing attention recently. Acetonitrile (CH3CN), the simplest organic compound with C≡N triple bond, can act as a model system for studying the pressure induced polymerization. The phase transition of acetonitrile under high pressure has been studied extensively.[1-3] However, it is still controversial and there is no any detailed discussion about its polymerization mechanism under high pressure. Here, we report the in-situ high pressure Raman spectra and powder neutron diffraction results on CD3CN, which indicates a minor phase transition at 5 GPa. The neutron diffraction shows that CD3CN keeps the orthorhombic phase from 1.66 GPa to 20.58 GPa which is very close to the reaction pressure. The week hydrogen bonding CD...N arranges the molecule into 3-dimensional framework which can be treated as two sets of diamond like structures interpenetrating with each other. Interestingly, the observed N...D distance is 1.984 Å at 20.58 GPa, shorter than the van der Waals distance of N...H (2.75 Å) by 28%. The van der Waals separation is often taken as a reference distance for the molecular instability. Thus, a hydrogen transfer process during the polymerization can be concluded. This deduction is also supported by the solid state NMR and FTIR results of the recovered polymerized CH3CN (p-CH3CN) from high pressure. In addition, the atomic pair distribution function and Raman spectra indicate the p-CD3CN or p-CH3CN has a random packed layer structure with nano-graphene lattice.

Direct reaction mechanism of nucleon transfer at thermonuclear energies / Der Mechanismus der direkten Nukleontransfer-Reaktionen bei thermonuklearen Energien.

Kerntechnik ◽  
1989 ◽  
Vol 53 (3) ◽  
pp. 211-214
Author(s):  
H. Oberhummer ◽  
H. Herndl ◽  
H. Leeb ◽  
G. Staudt
Keyword(s):  
Reaction Mechanism ◽  
Direct Reaction ◽  
Nucleon Transfer

Zur Hochdruckpolymorphie der Seltenerdsulfidfluoride LnSF (Ln: Er, Yb, Lu) / High Pressure Polymorphism of Rare Earth Sulfidefluorides LnSF (Ln: E r, Yb, Lu)

1985 ◽  
Vol 40 (12) ◽  
pp. 1644-1650 ◽  
Author(s):  
H. P. Beck ◽  
C. Strobel
Keyword(s):  
High Pressure ◽  
Rare Earth ◽  
Reaction Mechanism ◽  
Type Structure ◽  
Topological Description

Abstract The sulfidefluorides LnSF with Ln = Er, Yb, Lu undergo a high pressure transformation from the β-YSF- to a PbFCl-type structure. The structures involved and a proposed reaction mechanism are explained in terms of a topological description

Kinetics and Activation Parameters for the Alkaline Aqueous Rearrangement of Trichorfon [O,O-Dimethyl-(2,2,2-Trichloro-1-Hydroxyethyl) Phosphonate] to Dichlorvos [O,O-Dimethyl-O-(2,2-Dichloroethenyl)Phosphate]

2001 ◽  
Vol 36 (3) ◽  
pp. 589-604 ◽  
Author(s):  
Julian M. Dust ◽  
Christopher S. Warren
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Activation Parameters ◽  
Base Catalysis ◽  
Rearrangement Product ◽  
Exponential Factor ◽  
First Order ◽  
Pseudo First Order ◽  
Order Plot ◽  
Kinetics Of

Abstract The kinetics of the alkaline rearrangement of O,O-dimethyl-(2,2,2-trichloro-1- hydroxyethyl)phosphonate, (trichlorfon, 1), the active insecticidal component in such formulations as Dylox, was followed at 25±0.5°C by high pressure liquid chromatography (UV-vis detector, 210 nm). The rearrangement product, O,Odimethyl- O-(2,2-dichloroethenyl)phosphate (dichlorovos, 2), which is a more potent biocide than trichlorfon, undergoes further reaction, and the kinetics, consequently, cannot be treated by a standard pseudo-first-order plot. A two-point van't Hoff (initial rates) method was used to obtain pseudo-first-order rate constants (kѱ) at 25, 35 and 45°C: 2.6 × 10-6, 7.4 × 10-6 and 2.5 × 10-5 s-1, respectively. Arrhenius treatment of this data gave an activation energy (Ea) of 88 kJ·mol-1 with a pre-exponential factor (A) of 5.5 × 109 s-1. Kinetic trials at pH 8.0 using phosphate and tris buffer systems show no buffer catalysis in this reaction and indicate that the rearrangement is subject to specific base catalysis. Estimates are reported for pseudo-first-order half-lives for trichlorfon at pH 8.0 for environmental conditions in aqueous systems in the Corner Brook region of western Newfoundland, part of the site of a recent trichlorfon aerial spray program.

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