Schwermetall-π-Komplexe. IX. Die Kettenpolymere [(1,2- (CH3)2C6H4BiCl3)2], [(1,3) (CH3)2C6H4BiCl3)2] und [(1,4- (CH3)2C6H4BiCl3)2]

Heavy Metal π-Complexes. IX. The Chain Polymers [(1,2- (CH₃)₂C₆H₄BiCl₃)₂], [(1,3- (CH₃)₂C₆H₄BiCl₃)₂] and [(1,4- (CH₃)₂C₆H₄BiCl₃)₂] In the crystal structures of the three solid state complexes (C₆H₄(CH₃)₂BiCl₃ (C₆H₄(CH₃)₂ = o-xylene: 1 , m-xylene: 2 , p-xylene: 3 ) quasi-dimeric units of almost undistorted, arene coordinated BiCl₃ fragments can be found that are further associated via additional Bi? Cl contacts to form one-dimensional polymeric chains. Whereas the chains of 2 and 3 are constituted by Bi₂Cl₂ four-membered rings only, further Cl-bridging in 1 leads to additional trigonal-bipyramidal arrangements with Bi atoms exhibiting coordination numbers of 3 + 3 + 1 and 3 + 2 + 1, respectively (prim. + sec. Cl contacts + arene). The arene-metal bonding is characterized by Bi-arene distances in the range from 297 – 306 pm, including ring slippages of 24 –41 pm and 73 pm with the Bi atoms being six and seven coordinated, respectively. The direction of this slipping with respect to the arene's methylation sites cannot be understood in terms of electronic influences but is shown to be caused by steric demands. The values IP₁ of the arenes prove to determine the colours of the complexes.     

Schwingungsspektren und Kraftkonstanten der Übergangsreihe O2PF—S2PF— S2P(CH3)

Vibration spectra and force constants of the series O₂PF — S₂PF — S₂P(CH₃). The vibrational spectra of OSPF, S₂PF, S₂PF(CH₃) and S₂P(CN) are reported and discussed with O₂PF and S₂P(CH₃). On the basis of a simplified valence-force-field the force constants are calculated and the bonding relations are discussed. In the ions, f PF is lower than in corresponding molecules. The ionic charge is distributed over nearly all atoms of the ions.     

K3Au5Pb: eine Schichtstruktur mit [AuAu3/2]-Gold-Tetraedern und [Pb2/2]-Blei-Ketten

K₃Au₅Pb: Layers of [AuAu_3/2] Gold Tetrahedra and [Pb_2/2] Lead Chains Silver coloured, brittle single crystals of K₃Au₅Pb were synthesized by reaction of potassium azide with gold sponge and lead powder at T = 920 K. The structure of the compound (space group Imma, Z = 4, a = 5.646(1) Å, b = 19.500(4) Å, c = 8.412(1) Å) was determined from X-ray single-crystal diffractometry data. The gold lead partial structure consists of layers of [AuAu_3/2] tetrahedra and [Pb_2/2] zigzag chains with four-bonded lead atoms which are connected to a framework structure via Au–Pb contacts. The potassium atoms occupy channels within the gold lead partial structure.     

Darstellung,Schwingungsspektren und Kristallstrukturen von [(Ph3P)2N]2[(W6Cl)I] · 2 Et2O · 2 CH2Cl2 und [(Ph3P)2N]2[(W6Cl)(NCS)] · 2 CH2Cl2

Synthesis, Crystal Structures, and Vibrational Spectra of [(Ph₃P)₂N]₂[(W₆Cl )I ] · 2 Et₂O · 2 CH₂Cl₂ and [(Ph₃P)₂N]₂[(W₆Cl )(NCS) ] · 2 CH₂Cl₂ By treatment of [(W₆Cl)I]^2– with (SCN)₂ in dichloromethane at –20 °C the hexaisothiocyanato cluster anion [(W₆Cl)(NCS)]^2– is formed. X‐ray structure determinations have been performed on single crystals of [(Ph₃P)₂N]₂[(W₆Cl)I] · 2 CH₂Cl₂ · 2 Et₂O ( 1 ) (triclinic, space group P1, a = 10.324(5), b = 14.908(3), c = 17.734(8) Å, α = 112.78(2)°, β = 99.13(3)°, γ = 92.02(3)°, Z = 1) and [(Ph₃P)₂N]₂[(W₆Cl)(NCS)] · 2 CH₂Cl₂ ( 2 ) (triclinic, space group P1, a = 11.115(2), b = 14.839(2), c = 17.036(3) Å, α = 104.46(1)°, β = 105.75(2)°, γ = 110.59(1)°, Z = 1). The thiocyanate ligands of 2 are bound exclusively via N atoms with W–N bond lengths of 2.091–2.107 Å, W–N–C angles of 173.1–176.9° and N–C–S angles of 178.1–179.3°. The vibrational spectra exhibit characteristic innerligand vibrations at 2067–2045 (ν_CN), 879–867 (ν_CS) and 490–482 (δ_NCS). Based on the molekular parameters of the X‐ray determination of 1 the vibrational spectra of the corresponding (n‐Bu₄N) salt of 1 are assigned by normal coordinate analysis. The valence force constants are f_d(WW) = 1.61, f_d(WI) = 1.23 and f_d(WCl) = 1.10 mdyn/Å.     

Synthesis and Structure of a One‐Dimensional Aluminum Phosphate, [NH3(CH2)2NH2(CH2)3NH3]3+ [Al(PO4)2]3—

A one‐dimensional aluminum phosphate, [NH₃(CH₂)₂NH₂(CH₂)₃NH₃]³⁺ [Al(PO₄)₂]^3—, has been synthesized hydrothermally in the presence of N‐(2‐Aminoethyl‐)1, 3‐diaminopropane (AEDAP) and its structure determined by single crystal X‐ray diffraction. Crystal data: space group = Pbca (no. 61), a = 16.850(2), b = 8.832(1), c = 17.688(4)Å, V = 2632.4(2)ų, Z = 8, R₁ = 0.0389 [5663 observed reflections with I > 2σ(I)]. The structure consists of anionic [Al(PO₄)₂]^3— chains built up from AlO₄ and PO₄ tetrahedra, in which all the AlO₄ vertices are shared and each PO₄ tetrahedron possesses two terminal P=O linkages. The cations, which balances the negative charge of the chains, are located in between the chains and interact with the oxygen atoms through strong N—H···O hydrogen bonds. Additional characterization of the compound by powder XRD and MAS‐NMR has also been performed and described.     

The crystal structure of tris (ethylenediamine), cobalt(III) hexacyanoferrate(III)dihydrate,Co(C2H8N2)3[Fe(CN)6] · 2H2O

The crystal structure of the title compound has been determined from three dimensional x-ray data obtained by the multiple film method. The space group is P2_l/n and the cell dimensions are: a = 14.90, b = 16.84, c = 8.38 Å; β = 93.5° Z = 4. The structure is formed by discrete Co (en) and Fe(CN) ions, both of which have an octahedral configuration. The Fe(CN) ions are approximately octahedrally surrounded by the Co (en) ions while arrangement of Fe (CN) ions around the Co(en) ions completely differs from an octahedron. The mean Fe? C and Co? C dustances are 1.91 and 2.01 Å, respectively. The water molecules do not play an important role in the structure and all distances between oxygen and other atoms indicate the presence of very weak hydrogen bonds. The salts M (en)₃ Q(CN)₆ · H₂O, where M = Co and Cr and Q = Cr, Mn, Fe and Co, are all isomorphous.     

Rate constants for the reactions of OH radicals with CH3OCF2CF3, CH3OCF2CF2CF3, and CH3OCF(CF3)2

The rate constants for the reactions of OH radicals with CH₃OCF₂CF₃, CH₃OCF₂CF₂CF₃, and CH₃OCF(CF₃)₂ have been measured over the temperature range 250–430 K. Kinetic measurements have been carried out using the flash photolysis, laser photolysis, and discharge flow methods combined respectively with the laser induced fluorescence technique. The influence of impurities in the samples was investigated by using gas‐chromatography. The following Arrhenius expressions were determined: k(CH₃OCF₂CF₃) = (1.90) × 10⁻¹² exp[−(1510 ± 120)/T], k(CH₃OCF₂CF₂CF₃) = (2.06) × 10⁻¹² exp[−(1540 ± 80)/T], and k(CH₃OCF(CF₃)₂) = (1.94) × 10⁻¹² exp[−(1450 ± 70)/T] cm³ molecule⁻¹ s⁻¹. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 846–853, 1999     

Preparation,characterization, crystal and molecular structure of Na2[N(CH2COO)3 99Tc(IV) (μ-O)2 99Tc(IV)N(CH2COO)3] · 6H2O

The title compound and its potassium analog have been prepared from corresponding aqueous solutions of ⁹⁹TcO at pH ≈? 2 with SO₂ as a reducing agent. An X-ray structure determination of the Na-salt showed Tc coordinated to the tetradentate N(CH₂COO) ligand (NTA). Two Tc-NTA moieties are joined via two bridging O-atoms into a four-membered Tc₂O₂ ring. The observed diamagnetism, a strong absorption band at 19 950 cm^?1, and a short Tc-Tc distance of 2.363 Å are typical for the Tc₂O₂-fragment with its strong metal-metal interaction. The structural trans-influence at Tc and the network of H-bonds are consistent with Tc in oxidation state IV.     

Kinetics and mechanism of the cationic polymerization of tetrahydrofuran in solution. THF–CH2Cl2 and THF–CH2Cl2/CH3NO2 systems

Cationic polymerization of tetrahydrofuran (THF) in CH₂Cl₂ solvent and in mixed CH₂Cl₂/CH₃NO₂ solvent was initiated with 1,3-dioxolan-2-ylium cations with AsF and SbF anions. Dissociation constants of the polytetrahydrofuranium ion pairs into ions were measured (e.g., K_D = 1.5 × 10^?5M at 25°C and [THF]₀ = 7.0M; CH₂Cl₂ solvent) and were found to be more than 100 times lower than in CH₃NO₂ solvent at the same [THF]₀ and temperature. The rate constants k and k, measured for degrees of dissociation ranging from 0.03 to 0.35 in CH₂Cl₂, were the same within an experimental error of measurements (±15% of the value of k_p). Dependence of k( = k = k) on the dielectric constant was a monotonous function in three different solvents, namely, CCl₄, CH₂Cl₂, and CH₃NO₂, which covered a large range of dielectric constants of the medium (from D = 5 to D = 22) and degrees of dissociation of the macroion pairs, α (from 0.03 to more than 0.70). Thus a decrease in the dielectric constant increases the rate constant k in the whole range of studied polarities of the medium. This result confirms an earlier conclusion that the rate constant of propagation does not depend on the state of aggregation of ions and k = k.     

Cis-/Trans-Isomerie bei Bis-(trisalkoxy)-hexavanadaten: cis-Na2[VO7(OH)6{(OCH2)3CCH2OH}2] · 8 H2O,cis-(CN3H6)3[VIVVO13{(OCH2)3CCH2OH}2] · 4,5 H2O und trans-(CN3H6)2[VO13{(OCH2)3CCH2OH}2] · H2O

Cis-/Trans-Isomerism of Bis-(trisalkoxy)-hexavanadates: cis-Na₂[V O₇(OH)₆{(OCH₂)₃CCH₂OH}₂] · 8 H₂O, cis-(CN₃H₆)₃[V^IVV O₁₃{(OCH₂)₃CCH₂OH}₂] · 4.5 H₂O and trans-(CN₃H₆)₂[V O₁₃{(OCH₂)₃CCH₂OH}₂] · H₂O Polyoxovanadates with distorted Lindquist-structure, in which six of the twelve μ₂-oxygen atoms are formally replaced by the oxygen atoms of two coordinated pentaerythritol ligands, can be prepared by a simple method in an aqueous medium. The “fully reduced”, six-fold protonated compound cis-Na₂[VO₇(OH)₆{(OCH₂)₃CCH₂OH}₂] · 8 H₂O ( 1 ), the mixed valence species cis-(CN₃H₆)₃[V^IVVO₁₃{(OCH₂)₃CCH₂OH}₂] · 4.5 H₂O ( 2 ) containing one localized V^IV centre and the “fully oxidized” compound trans-(CN₃H₆)₂[VO₁₃{(OCH₂)₃CCH₂ · OH}₂] · H₂O ( 3 ) have been synthesized and characterized by UV/VIS-, IR- and EPR-spectroscopy, by magnetic measurements, cyclic voltammetry and by a single-crystal X-ray structure analysis. The organic {(CH₂)₃CCH₂OH}³⁺-groups tend to cap the triangular faces formed by μ₂-oxygen atoms of the central approximately octahedral {V₆O₁₉}-unit. Therefore the anions of bis-(trisalkoxy)-hexavanadates can exist in a trans-form as well as in an isomeric cis-form referring to a “basic” plane of four vanadium atoms of the {V₆}-octahedron. The different relative positions of the ligands have a significant influence on the redox potentials of the compounds. For structural details see “Inhaltsübersicht”.     

Thermal decomposition of di-t-butyl peroxide in the presence of (CH3)2CCH2: Reactions of CH3, (CH3)2ĊCH2CH3, and (CH3)2ĊCH2C(CH3)2CH2CH3 radicals

A study of the reaction initiated by the thermal decomposition of di-t-butyl peroxide (DTBP) in the presence of (CH₃)₂C?CH₂ (B) at 391–444 K has yielded kinetic data on a number of reactions involving CH₃ (M·), (CH₃)₂CCH₂CH₃ (MB·) and (CH₃)₂?CH₂C(CH₃)₂CH₂CH₃ (MBB·) radicals. The cross-combination ratio for M· and MB· radicals, rate constants for the addition to B of M· and MB· radicals relative to those for their recombination reactions, and rate constants for the decomposition of DTBP, have been determined. The values are, respectively, where θ = RT ln 10 and the units are dm^3/2 mol^?1/2 s^?1/2 for k₂/k and k₉/k, s^?1 for k₀, and kJ mol^?1 for E. Various disproportionation-combination ratios involving M·, MB·, and MBB· radicals have been evaluated. The values obtained are: Δ₁(M·, MB·) = 0.79 ± 0.35, Δ₁(MB·, MB·) = 3.0 ± 1.0, Δ₁(MBB·, MB·) = 0.7 ± 0.4, Δ₁(M·, MBB·) = 4.1 ± 1.0, Δ₁(MB·, MBB·) = 6.2 ± 1.4, and Δ₁(MBB·, MBB·) = 3.9 ± 2.3, where Δ₁ refers to H-abstraction from the CH₃ group adjacent to the center of the second radical, yielding a 1-olefin. © 1994 John Wiley & Sons, Inc.     

Synthese und Strukturuntersuchungen von Iodocupraten(I). XV Iodocuprate(I) mit solvatisierten Kationen: [Li(CH3CN)4][Cu2I3] und [Mg{(CH3)2CO}6][Cu2I4]

Synthesis and Structure Investigations of Iodocuprates(I). XV Iodocuprate(I) with Solvated Cations: [Li(CH₃CN)₄] [Cu₂I₃] and [Mg{(CH₃)₂CO}₆][Cu₂I₄] [Li(CH₃CN)₄][Cu₂I₃] 1 and [Mg((CH₃)₂CO)₆][Cu₂I₄] 2 were prepared by reactions of CuI with LiI in acetonitrile and of CuI with MgI₂ in acetone. 1 crystallizes orthorhombic, Pnma, a = 552.7(2), b = 1258.8(8), c = 2516(1) pm, z = 4. [Li(CH₃CN)₄]⁺ cations are located between rod packings of CuI₄ tetrahedra double chains [(CuI_2/2I_2/4)₂]^? parallel to the axis. Short intermolecular anion/cation contacts were observed. The crystal structure of 2 (monoclinic, P2₁/n, a = 1840(2), b = 1059.2(2), c = 1879(2)pm, β = 112.94(4)°, z = 4) is built up by [Mg((CH₃)₂CO)₆]²⁺ cations forming a simple hexagonal sphere packing. The binuclear anions [Cu₂I₄]^2? occupy holes in the trigonal prismatic channels formed by the cations.     

Tetraammin-Lithium-Kationen zur Stabilisierung phenylsubstituierter Zintl-Anionen: Die Verbindung [Li(NH3)4]2[Sn2Ph4]

Tetraammine Lithium Cations Stabilizing Phenylsubstituted Zintl-Anions: The Compound [Li(NH₃)₄]₂[Sn₂Ph₄] Ruby-red, brittle single crystals of [Li(NH₃)₄]₂[Sn₂Ph₄] were synthesized by the reaction of diphenyltin dichloride and metallic lithium in liquid ammonia at ?35°C. The structure was determined from X-ray singlecrystal diffractometer data: Space group, P1 , Z = 1, a = 9.462(2) Å, b = 9.727(2) Å, c = 11.232(2) Å, α = 66.22(3)°, β = 85.78(3)°, γ = 61.83(3)°, R₁ (F ? 4σF) = 5.13%, wR₂ (F₀² ? 4σF) = 10.5%, N(F ? 4σF) = 779, N(Var.) = 163. The compound contains to Sb₂Ph₄ isosteric centres [Sn₂Ph₄]^2? as anions which are connected to rods by lithium cations in distorted tetrahedral coordination by ammonia. These rods are arranged parallel to one another in the b,c-plane, but stacked along [100].     

Zur Struktur der basischen Diquecksilber(I)-nitrate. I kristallstruktur des Hg2OH(NO3) · Hg2(NO3)2

The Crystal Structure of the Basic Dimercury (I) Nitrates. I. The Crystal Structure of Hg₂OH(NO₃) · Hg₂(NO₃)₂ The unit cell of Hg₂OH(NO₃) · Hg₂(NO₃)₂ is orthorhombic, space group Cc2a - standard setting Aba2 (C) — with a = 2017.1(5) pm, b = 935.8(3) pm, c = 1121.7(3) pm and contains 8 formula units. Characteristic are chains [Hg₂OH(Hg₂)_2/2]³⁺ parallel [001]. These are interconnected to a three-dimensional network by nitrate ions coordinated to mercury. The structure achieves additional stabilization through weak hydrogen bonds between oxygen atoms of the hydroxy groups and neighbouring nitrate ions. The bonding relationship of one hydrogen atom to four tetrahedrally correlated oxygen atoms is discussed.     

Sur les carbonates basiques de fer (III): II. Préparation,radiocristallographie et spectres IR. du (NH4)2Fe2(OH)4(CO3)2 · H2O

The obtention of the crystalline basic carbonate of iron (III) and ammonium, (NH₄)₂Fe₂(OH)₄(CO₃)₂ · H₂O, is described and its formula is established by chemical analysis and infrared spectroscopy. The powder X-ray diagram could be indexed tetragonally leading to a body centred elementary cell with a = 12,04 ± 0,02 Å and c = 6,62 ± 0,01 Å. The infrared spectra show that in the CO groups either one oxygen atom is linked to one iron atom or, rather, two oxygen atoms are linked to two iron atoms. The symmetry of the NH groups is lower than C_3v. The OH-groups are linked by hydrogen bonds of 2,75 Å. Two sorts of OH-groups can be distinguished, with a radius of approximately 1,34 Å and 1, 48 Å, respectively. The iron atoms are octahedrally coordinated by oxygen atoms, but either the octahedra are deformed or the iron atoms are in part coordinated tetrahedrally.     

Kinetic studies of the reactions CH2I2 + HI⇄CH3I + I2 and 2 CH3I⇄CH4 + CH2I2 the heat of formation of the iodomethyl radical

The rate of the reaction CH₂I₂ + HI ? CH₃I + I₂ has been followed spectrophotometrically from 201.0 to 311.2°. The rate constant for the reaction fits the equation, log (k₁/M^?1 sec^?1) = 11.45 ± 0.18 - (15.11 ± 0.44)/θ. This value, combined with the assumption that E₂ = 0 ± 1 kcal/mole, leads to ΔH (CH₂I, g) = 55.0 ± 1.6 kcal/mole and DH (H? CH₂I) = 103.8 ± 1.6 kcal/mole. The kinetics of the disproportionation, 2 CH₃I ? CH₄ + CH₂I₂ were studied at 331° and are compatible with the above values.     

19F-NMR-spektroskopischer Nachweis und statistische Untersuchung zur Bildung der gemischten Clusteranionen [(Mo6ICl)F]2−, n = 0–7, und Darstellung von (TBA)2[(Mo6I)F]

¹⁹F NMR Spectroscopic Evidence and Calculation of the Statistical Formation of Mixed Cluster Anions [(Mo₆I Cl )F ]^2?, n = 0–7, and Preparation of (TBA)₂[(Mo₆I )F ] The octa-μ₃-iodo-hexafluoro-hexamolybdate(2?)ion [(Mo₆I)F]^2? is prepared for the first time. The system of the 21 innersphere mixed clusters (Mo₆ICl)⁴⁺, n = 0–7 is formed by exchange of innersphere bound Clⁱ against outersphere bound I^a on tempering solid [(Mo₆Cl)I] at 400°C. Prolonged tempering leads to increasing average n values of the mixture, which is converted into the tetrabutylammonium salt (TBA)₂[(Mo₆ICl)F]. Using increments of chemical shifts and integral peak intensities the 54 ¹⁹F-nmr signals of the 21 species (compound n = 8 is absent) are assigned and confirmed by the 2 D-¹⁹F/¹⁹F-COSY spectrum. From the measured intensities the distribution of the different compounds is determined and proves significant deviation from statistical occupation, revealing the preference of isomers with iodine atoms occupying edges of the innersphere cube and discrimination of those sharing diagonals of the faces. Moreover all compounds with n = 3 and 4 are present overaverage in comparison to the others.     

Polysila analogs of aromatic hydrocarbon ions: Structures and energies of Si3H3+, Si4H,and Si5H5−

Silicon analogs of aromatic monocyclic ions, (SiH) ( 4 ), (SiH) ( 5 ), and (SiH) ( 6 ) have been studied ab initio at MP 2(full)/6-31G *. The D_3h structure of Si₃H₃⁺ is the global minimum, whereas other two ions are nonplanar. The D_2d structure of (SiH) is less folded than the carbon analog and possesses a higher stabilization energy. Stabilization energies for the monocharged ions are diminished with respect to the corresponding carbons © 1993 John Wiley & Sons, Inc.     

Darstellung,Schwingungsspektrum und Kristallstruktur von (n‐Bu4N)2[(W6Cl)F] · 2 CH2Cl2 und 19F‐NMR‐spektroskopischer Nachweis der gemischten Clusteranionen [(W6Cl)FCl]2–, n = 1–6

Synthesis, Vibrational Spectra, and Crystal Structure of ( n ‐Bu₄N)₂[(W₆Cl )F ] · 2 CH₂Cl₂ and ¹⁹F NMR Spectroscopic Evidence of the Mixed Cluster Anions [(W₆Cl )F Cl ]^2–, n = 1–6 The reaction of (n‐Bu₄N)₂[(W₆Cl)Cl] with CF₃COOH in dichloromethane gives intermediately a mixture of the cluster anions [(W₆Cl)(CF₃COO)Cl]^2–, n = 1–6. By treatment with NH₄F the outer sphere coordinated trifluoracetato ligands are easily substituted and the components of the series [(W₆Cl)FCl], n = 1–6 are formed and characterized by their distinct ¹⁹F NMR chemical shifts. An X‐ray structure determination has been performed on a single crystal of (n‐Bu₄N)₂[(W₆Cl)F] · 2 CH₂Cl₂ (orthorhombic, space group Pbca, a = 15.628(4), b = 17.656(3), c = 20.687(4) Å, Z = 4). The low temperatur IR (60 K) and Raman (20 K) spectra are assigned by normal coordinate analysis based on the molecular parameters of the X‐ray determination. The valence force constants are f_d(WW) = 1.89, f_d(WF) = 2.43 and f_d(WCl) = 0.93 mdyn/Å.     

Iodine catalyzed pyrolysis of dimethyl sulfide. Heats of formation of CH3SCH2I,the CH3SCH2 radical,and the pibond energy in CH2S

A kinetic study has been made of the gas phase, I₂-catalyzed decomposition of (CH₃)₂S at 630–650 K. Some I₂ is consumed initially, reaching a steady-state concentration. The initial major products are CH₄ and CH₂S together with small amounts of CH₃SCH₂I, CH₃I, HI, and CS₂. The initial reaction corresponds to a pseudo-equilibrium: accompanied by: and which brings (I₂) into steady state and a final complex reaction: From the initial rate of I₂ loss it is possible to obtain Arrhenius parameters for the iodination: We measure k₁, (644 K) = 150 L/mol s and from both the Arrhenius plot and independent estimates A₁ (644 K) = 10^{11.2 ± 0.3} L/mol s. Thus, E₁ = 26.7 ± 1 kcal/mol. From the steady-state I₂ concentration, an assumed mechanism and the known rate parameters for the CH₃I/HI system. It is possible to deduce K_A (644) = 3.8 × 10^?2 with an uncertainty of a factor of 2. Using an estimated ΔS (644) = 4.2 ± 1.0 e.u. we find ΔH_A (644) = 7.0 ± 1.1 kcal. With 〈ΔC_PA〉644 = 1.2 this becomes: ΔH_A(298) = 6.6 ± 1.1 kcal/mol. Then ΔH (CH₃SCH₂I) = 6.3 ± 1 kcal/mol. Making the assumption that E_?1 = 1.0 ± 0.5 kcal/mol we find ΔH (644) = 25.7 ± 0.7 kcal/mol and with 〈ΔC_PI〉 = 1.2; ΔH = 25.3 ± 0.8 kcal/mol. This gives ΔH (CH₃S?H₂) = 35.6 ± 1.0 kcal/mol and DH (CH₃SCH₂? H) = 96.6 ± 1.0 kcal/mol. This then yields E_π(CH₂S) = 52 ± 3 kcal. From the observed rate of pressure increase in the system and the preceding data k₃, is calculated for the step CH₃SCH₂ → CH₃ + CH₂S. From an estimated A-factor E₃ is deduced and from the overall thermochemistry values for k_?3 and E_?3. A detailed mechanism is proposed for the I-atom catalyzed conversion of CH₂S to CS₂ + CH₄.