Das erste Oxocobaltat des Typs A2CoIIO2: K2CoO2 = K4[OCoO2CoO]

The First Oxocobaltate of the Type A₂Co^IIO₂: K₂CoO₂ = K₄[OCoO₂CoO] By “reaction with the cylinder surface” of intimate mixtures of K₂O and CdO (molar ratio 1:1) in closed Co-Cylinders at 450°C during 73 d dark-red single-crystals of K₂CoO₂ were obtained. Structure solution and refinement (four-circle diffractometer-data, MoKα , 1 567 independent I_o(hkl), none was omitted, R = 3.25%, R_w = 2.67%) result in a monoclinic unit cell containing anions [Co₂O₄]^4? of two connected triangles similar to those of Rb₁₀[Co^IO₂]₂[CoO₄]. MAPLE-values and Charge-distributions are given and discussed.     

Über „Gemischt-Koordinierte”︁ einkernige Anionen. 2. Ein Oxoruthenat(VI) neuen Typs: CsK5Ru2O9 = CsK5[RuO5][RuO4]

On ?Mixed-coordinated”? isolated Anions. 2. A New Type of Oxoruthenates(VI): CsK₅Ru₂O₉ = CsK₅[RuO₅][RuO₄] By heating of intimate mixtures of the oxides [KO_1.1, CsO_1.2, RuO₂; K:Cs:Ru = 2.2:1:1; Ag-tube, 750°C, 34d] dark-green single crystals of CsK₅Ru₂O₉ = CsK₅[RuO₅][RuO₄] were obtained for the first time. Ru⁶⁺ shows two different polyhedra in this oxide (tetrahedron, trigonal bipyramid). Untill now Rb₆[TeO₅][TeO₄] [1] next to ?Mg₄GeO₆”? [3] and the isotypic high-pressure silicate [4] was the only examples known. The structure was determined by four-circle diffractometer data [Mo? Kα , 1824 from 1949 I₀(hkl), SG: Pnma, R equals; 12.6%, R_w = 4.5%], parameters see text. Guinier-Simon data gave a = 1701.6(3), b = 827.6(1), c = 905.7(1) pm, Z = 4. The Madelung Part of Lattice Energy, MAPLE, Effective Coordination Numbers, ECoN, these calculated via Mean Fictive Ionic Radii, MEFIR, were calculated and discussed.     

Oxydation intermetallischer Phasen: CsK2[AuO2] aus CsAu + K2O2

Oxidation of Intermetallic Phases CsK₂[AuO₂] from CsAu+K₂O₂ We prepared the hitherto unknown CsK₂[AuO₂] [Heating mixtures of CsAu and K₂O_2,2; 1:1; gives single crystals (Ag-cylinder, 430°C, 6d)]. The single crystals are light blue, nearly colourless, and transparent. A new type of structure is found. The single crystal data are: Pnma; a = 1256.5(5), b = 727.3(2), c = 627.9(2)pm, Z = 4; four-circle diffractometer PW 1100, MoKα;849 out of 871 I₀(hkl), R = 7.3% and R_w = 6.3%. The Madelung Part of Lattice Energy, MAPLE, is calculated.     

Zur Kenntnis der Na5[GaO4]-Verwandtschaft: KNa4[GaO4] und CsK4[GaO4]

About the Na₅[GaO₄]-Relationship: KNa₄[GaO₄] and CsK₄[GaO₄] KNa₄[GaO₄] was newly prepared from binary oxides (powders) and also from KGaO₂/Na₂O/K₂O (colourless columnar single crystals) in a closed Ag-cylinder at 600 and 650°C. Space group Pbca with a = 1046.1(2), b = 596.3(1), c = 1871.1(3) pm, Z = 8 [Four-circle-diffractometer data, 1138 I₀(hkl), MoKα, R = 8.29, R_w = 6.76%, anisotropic refinement] (Parameter s. text). Colourless cubic single crystals of hitherto unknown CsK₄[GaO₄] are formed by reaction of K₂O, CsGaO₂, and Cs₂O (surplus) in a closed Au-tube at 580°C. Space group Pbca with a = 1154.7, b = 667.7, c = 2096.6 pm, Z = 8 [Four-circle-diffractometer data, 1798 I₀(hkl), MoKα, R = 7.62, R_w = 7.68%, anisotropic refinement] (Parameter s. text). Both crystal structures belong to the Na₅[GaO₄] type. Structural aspects, ECoN, and MAPLE of KNa₄[GaO₄] and CsK₄[GaO₄] in relation with Na₅[GaO₄] are discussed.     

Zur Kenntnis der Oxocobaltate(II) Na4[CoO3], ein Nesocobaltat(II)

On the Knowledge of Oxocobaltates(II). Na₄[CoO₃], the First Nesocobaltate(II) Newly prepared transparent, blood red single crystals of Na₄[CoO₃] (Na₂O/?CoO’? Na:Co = 4.4:1, cobalt tube, 550°C, 20d, dry argon), crystallize triclinically, P1, a = 8.14₄, b = 6.22₀, c = 5.75₈ Å; α = 117.5, β = 89.9, γ = 111.2 (diffractometer data), Z = 2. There are carbonate-like, isolated [CoO₃] groups, respectively parameters and distances see text. 2358 symmetry independent reflections (automatical four cycle diffractometer PW 1100, Mo–Kα, graphite monochromator, 4° ? Θ ? 36°), R = 0.0597. The Madelung Part of the Lattice Energy, MAPLE, Effective Coordination Numbers, ECoN and Mean Fictive Ionic Radii, MEFIR are calculated and discussed.     

Zur Oxydation intermetallischer Phasen: Die Oxoplumbate(II) K6[Pb2O5] [1] und K4[PbO3] [2]

On the Oxidation of Intermetallic Phases: The Oxoplumbates(II) K₆[Pb₂O₅] [1] and K₄[PbO₃] [2] Very pale yellow crystals of K₆[Pb₂O₅] were obtained by heating a wellground mixture of LiPb und K₂O₂ (K₂O₂: LiPb = 2.5:1) in Ag-tubes (550°C; 40 d). The crystal structure, triclinic, space group P1 , a = 1 326.7(6); b = 758.8(4); c = 637.0(3) pm; α = 92.17(3)°; β = 94.41(3)°; γ = 112.85(4)°; Z = 2 was determined (four-circle diffractometer data, Mo? K, 3 270 I_o(hkl), R = 8.0%, R_w = 3.5%, parameters see text). The pale yellow crystals of K₄[PbO3] were received by heating KPb and K₂O₂ (K₂O₂: KPb = 3.3:2) in Ni-tubes (450°C; 17 d). The crystal structure (orthorhombic, space group Pbca with a = 658.2(1); b = 1 131.8(4); c = 1 872.2(6) pm; Z = 8) was refined (four-circle diffractometer data, Mo? K, 2 003 I_o(hkl), R = 4.9%, R_w = 2.8%). The Madelung Part of Lattice Energy (MAPLE), Effective Coordination Numbers (ECoN), the Mean Fictive Ionic Radii (MEFIR) and the Charge Distribution (CHARDI) are being calculated for both oxides.     

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].     

Über Oxoosmate(VII) Na5[OsO6] und Li5[OsO6]

On Oxoosmates(VII). Na₅[OsO₆] and Li₅[OsO₆] For the first time bluish black single crystals of Na₅[OsO₆] have been prepared. The structure was determined according to four-circle-diffractometer data. According to powder samples Li₅[OsO₆] is isotypic to Na₅[OsO₆]. Both are of the NaCl-type like Na₅[ReO₆] (space-group C2/m (No. 12, I.T.), Z = 2): Na₅[OsO₆]: a = 568.10(4), b = 975.00(6), c = 559.65(5) pm, β = 111.00° (1), 436 hkl, 4° ? Θ ? 30°, MoK, R = 2.7%, R_W = 2.6%. Li₅[OsO₆]: a = 568.10(4), b =975.00(6), c = 559,65(5) pm, β = 111.00° (1). Effective Coordination Numbers, ECoN, and the Madelung Part of Lattice Energy, MAPLE, are calculated and discussed.     

Mechanism of the hydroxyiodination of 2-butenoic acid

Aqueous iodination of trans-2-butenoic acid proceeds via hydrolysis of I₂ to form HOI and I^?, then rapid addition of HOI across the double bond to form the iodohydrin product. In the presence of iodate to keep iodide concentration low, the reaction proceeds at a conveniently measurable rate. The rate for the addition reaction is ?d[C₄H₆O₂]/dt = 5900 [H⁺][C₄H₆O₂][HOI]M/s at 25.0°C when [IO] = 0.025M and ionic strength = 0.3. The overall rate law in the presence of iodate is where [H⁺] and [IO] are total concentrations used to prepare the solution.     

Chloro‐N′,N′‐dimethylformamidinium‐(dimethylcyanamid)trichloroberyllat, [Me2NC(Cl)NH2]+[BeCl3(NCNMe2)]−

Chloro‐N′,N′‐dimethylformamidinium‐(dimethylcyanamide)trichloroberyllate, [Me₂NC(Cl)NH₂]⁺[BeCl₃(NCNMe₂)]^? Chloro‐N′,N′‐dimethylformamidinium‐(dimethylcyanamide)trichloroberyllate, [Me₂NC(Cl)NH₂]⁺[BeCl₃(NCNMe₂)]^? was prepared from BeCl₂ with two equivalents of dimethylcyanamide in CH₂Cl₂ suspension. The compound was characterized by X‐ray crystallography and by IR spectroscopy. Space group , Z = 2, lattice dimensions at 193 K: a = 620.7(1), b = 744.9(2), c = 1520.3(3) pm, α = 96.87(2)°, β = 100.41(2)°, γ = 100.17(2)°, R₁ = 0.0443. Cations and anions form N–H…Cl hydrogen bridges along [010].     

Die Kristallstrukturen von [Ph3PMe]Cl·CH2Cl2, [Ph4P]NO3·CH2Cl2 und [Ph4P]2[SiF6]·CH2Cl2

Crystal Structures of [Ph₃PMe]Cl·CH₂Cl₂, [Ph₄P]NO₃·CH₂Cl₂, and [Ph₄P]₂[SiF₆]·CH₂Cl₂ The crystal structures of the title compounds are determined by X‐ray diffraction. In all cases, the included dichloromethane molecules as well as the phosphonium cations are involved to form hydrogen bridges with the anions. [Ph₃PMe]Cl·CH₂Cl₂ ( 1 ): Space group , Z = 2, lattice dimensions at 100 K: a = 890.3(1), b = 988.0(1), c = 1162.5(1) pm, α = 106.57(1)°, β = 91.79(1)°, γ = 92.60(1)°, R₁ = 0.0253. [Ph₄P]NO₃·CH₂Cl₂ ( 2 ): Space group P2₁/n, Z = 4, lattice dimensions at 193 K: a = 1057.0(1), b = 1666.0(1), c = 1358.9(1) pm, β = 100.10(1)°, R₁ = 0.0359. [Ph₄P]₂[SiF₆]·CH₂Cl₂ ( 3 ): Space group , Z = 2, lattice dimensions at 193 K: a = 1063.9(1), b = 1233.1(1), c = 1782.5(2) pm, α = 76.88(1)°, β = 83.46(1)°, γ = 72.29(1)°, R₁ = 0.0332.     

Über den Phosphandiyl‐Transfer von invers‐polarisierten Phosphaalkenen R1P=C(NMe2)2 (R1 = tBu,Cy, Ph,H) auf Phospheniumkomplexe [(η5‐C5H5)(CO)2M=P(R2)R3] (R2 = R3 = Ph; R2 = tBu,R3 = H; R2 = Ph,R3 = N(SiMe3)2)

Phosphanediyl Transfer from Inversely Polarized Phosphaalkenes R¹P=C(NMe₂)₂ (R¹ = tBu, Cy, Ph, H) onto Phosphenium Complexes [(η⁵‐C₅H₅)(CO)₂M=P(R²)R³] (R² = R³ = Ph; R² = tBu, R³ = H; R² = Ph, R³ = N(SiMe₃)₂) Reaction of the freshly prepared phosphenium tungsten complex [(η⁵‐C₅H₅)(CO)₂W=PPh₂] ( 3 ) with the inversely polarized phosphaalkenes RP=C(NMe₂)₂ ( 1 ) ( a : R = tBu; b : Cy; c : Ph) led to the η²‐diphosphanyl complexes ( 9a‐c ) which were isolated by column chromatography as yellow crystals in 24‐30 % yield. Similarly, phosphenium complexes [(η⁵‐C₅H₅)(CO)₂M=P(H)tBu] (M = W ( 6 ); Mo ( 8 )) were converted into (M = W ( 11 ); Mo ( 12 )) by the formal abstraction of the phosphanediyl [PtBu] from 1a . Treatment of [(η⁵‐C₅H₅)(CO)₂W=P(Ph)N(SiMe₃)₂] ( 4 ) with HP=C(NMe₂)₂ ( 1d ) gave rise to the formation of yellow crystalline ( 10 ). The products were characterized by elemental analyses and spectra (IR, ¹H, ¹³C‐, ³¹P‐NMR, MS). The molecular structure of compound 10 was elucidated by an X‐ray diffraction analysis.     

Kristallstrukturen,Schwingungsspektren und Normalkoordinatenanalysen der stereoisomeren Trifluorotrichloroplatinate(IV), fac-[(C5H5N)2CH2][PtF3Cl3] · 0,5(CH3)2CO und mer-[(C5H5N)2CH2][PtF3Cl3]

Crystal Structures, Vibrational Spectra, and Normal Coordinate Analyses of the Stereoisomeric Trifluorotrichloroplatinates(IV), fac-[(C₅H₅N)₂CH₂][PtF₃Cl₃] · 0.5(CH₃)₂CO and mer-[(C₅H₅N)₂CH₂][PtF₃Cl₃] The geometric isomers fac- und mer-[PtF₃Cl₃]^2? have been isolated by ion exchange chromatography on diethylaminoethyl cellulose. The doubly charged complex anions form stable AB-type salts with the dication dipyridiniomethane, [(C₅H₅N)₂CH₂]²⁺. The X-ray structure determination on single crystals of fac-[(C₅H₅N)₂CH₂][PtF₃Cl₃] · 0,5(CH₃)₂CO ( 1 ) (triclinic, space group P1 with a = 8.468(3), b = 8.847(2), c = 12.1260(10) Å, α = 79.986(12), β = 79.009(12), γ = 69.20(3)°, Z = 2) and mer-[(C₅H₅N)₂CH₂][PtF₃Cl₃] ( 2 ) (monoclinic, space group P2₁/n with a = 9.620(2), b = 14.031(4), c = 10.435(3) Å, β = 97.54(2)°, Z = 4) reveals the perfect ordering of the anion sublattice. Due to the stronger trans influence of Cl compared to F in asymmetric axes $ {\rm F}^. $? Pt? Cl′ the Pt? $ {\rm F}^. $ distance is lengthened by 1.8%, the Pt? Cl′ distance is shortened by 1.2% in comparison with symmetrically coordinated axes. Correspondingly, the vibrational spectra exhibit shifts of the Pt$ {\rm F}^. $ streching vibrations by 8% to lower, and of the PtCl′ streching vibrations by 12% to higher frequencies. Normal coordinate analyses performed on the basis of the X-ray data result in valence force constants for weakened Pt? $ {\rm F}^. $ bonds to be 14% lower, for the strengthened Pt? Cl′ bonds to be 20% higher than in symmetric axes, respectively. Generally the trans influence in fluorochloroplatinates(IV) on the bond lengths is very low with 1–2%, it results in considerable shifts of the stretching vibrations by 8–12% and reveals the strongest effect on the valence force constants with 14–20%.     

Synthese und spektroskopische Charakterisierung einiger Pentacarbonylwolfram(0)-Komplexe mit verschiedenen 1H-Phosphiren-Liganden,Kristallstrukturen von,und

Synthesis and Spectroscopic Characterization of some Pentacarbonyltungsten(0) Complexes with Various 1H-Phosphirene Ligands: Crystal Structures of , and The tungsten(0) complex 1 reacts upon heating with acetylene derivatives 2a–f in toluene to form benzonitrile and the complexes 4a–f ( 4a : R¹ ? Ph, R² ? H; 4b : R¹ ? Ph, R² ? CH₃; 4c : R¹ ? OEt, R² ? H; 4d : R¹ ? Ph, R² ? CO₂Et; 4e : R¹, R² ? CO₂Me; 4f : R¹, R² ? SiMe₃), which have been isolated by chromatography. Spectroscopic and mass spectrometric data are discussed. The crystal structures of the compounds 4a, b and d were determined by X-ray single crystal structure analysis ( 4a : space group P2₁/n, Z = 4, a = 937,5(2) pm, b = 2202,4(6) pm, c = 1266,3(4) pm, β = 108,94(4)°; 4b : space group P2₁/c, Z = 4, a = 1293,9(2) pm, b = 923,5(1) pm, c = 2223,4(3) pm, β = 92,385(6)°; 4d : space group P2₁/c, Z = 4, a = 955,2(2) pm, b = 3190,9(4) pm, c = 930,7(2) pm, β = 99,64(1)°).     

Kristallstrukturen der Fluorochloroplatinate(IV) cis-[(C5H5N)2CH2][PtF4Cl2], trans-[(C5H5N)2CH2][PtF4Cl2] · H2O und [(C5H5N)2CH2][PtF5Cl]

Crystal Structures of the Fluorochloroplatinates(IV) cis-[(C₅H₅N)₂CH₂][PtF₄Cl₂], trans-[(C₅H₅N)₂CH₂][PtF₄Cl₂] · H₂O, and [(C₅H₅N)₂CH₂][PtF₅Cl] The complex ions cis-[PtF₄Cl₂]^2?, trans-[PtF₄Cl₂]^2? and [PtF₅Cl]^2? have been synthesized by stereoselective ligand exchange reactions utilizing the trans effect and are separated by ion exchange chromatography on diethylaminoethyl cellulose. These anions form stable AB-type salts with the doubly charged cation dipyridiniomethane, [(C₅H₅N)₂CH₂]²⁺. X-ray structure determinations on single crystals of cis-[(C₅H₅N)₂CH₂][PtF₄Cl₂] ( 1 ) (monoclinic, space group P2₁/n with a = 10.379(10), b = 9.635(2), c = 13.738(2) Å, β = 99.142(10)°, Z = 4), trans-[(C₅H₅N)₂CH₂][PtF₄Cl₂] · H₂O ( 2 ) (triclinic, space group P1 with a = 7.757(4), b = 10.059(7), c = 10.408(6) Å, α = 82.49(5), β = 68.92(4), γ = 75.46(4)°, Z = 2) and [(C₅H₅N)₂CH₂][PtF₅Cl] ( 3 ) (orthorhombic, space group Pnma with a = 10.394(3), b = 13.320(2), c = 9.2694(10) Å, Z = 4), reveal the perfect ordering of the anion sublattice. The stronger trans influence of Cl compared with F is observed in asymmetric axes $ {\rm F}^ \bullet $? Pt? Cl′. The bond lengths Pt? $ {\rm F}^ \bullet $ are 0.026 Å (1.4%) longer and the Pt? Cl′ distances are 0.078 Å (3,3%) shorter in comparison with those of symmetrically coordinated axes. The weakening of the Pt? $ {\rm F}^ \bullet $ bond and the strengthening of the Pt? Cl′ bond is better recognizable from shifts of the stretching vibrations by 8% to lower and by 13% to higher frequencies, respectively. Correspondingly, the valence force constants are found to be 15% lower and 22% higher. The trans influence is observed most distinctly in the ¹⁹F-nmr spectra exhibiting the coupling constant ¹J($ {\rm F}^ \bullet $Pt) to be 29% smaller than ¹J(FPt).     

Chalkogenid-Disilicate der Lanthanoide vom Typ M4X3[Si2O7] (M  Ce?Er; X  S,Se)

M₄X₃[Si₂O₇]-Type Lanthanide Chalcogenide Disilicates (M ? Ce? Er; X ? S, Se) Attempts to produce single crystals of MSe₂ (or MSe^2?X) by vapour phase transport with iodine or the oxidation of MCl₂ (or MClH) with sulfur in the presence of NaCl in sealed evacuated quartz containers often yielded well-grown single crystals with the composition M₄X₃[Si₂O₇] (M ? pr, Sm, Gd, X ? Se, and M ? Nd, Er, X ? S) as by-products. The crystal structures (tetragonal, 14₁/amd (no. 141)), Z = 8, contain two crystallographically independent M₃₊ Cations that are interconnected by chalcogenide (X_2?) and disilicate anions ([Si₂O₇]^6?). (M1)³⁺ is surrounded by eight (five X^2? and three terminal O_2? of the disilicate group), (M2)³⁺ by nine (three X^2? and six terminal O^2? of the [Si₂O₇]_6? anion) chalcogenide anions. The disilicate anion itself exhibits the eclipsed conformation with non-linear Si? O? Si bridges (angles: 128 – 133°).     

Very low-pressure pyrolysis (VLPP) of pentynes. III. Pent-2-yne. Heat of formation and resonance stabilization energy of the 3-methylpropargyl radical

The thermal unimolecular decomposition of pent-2-yne has been studied over the temperature range of 988–1234 K using the technique of very low-pressure pyrolysis (VLPP). The main reaction pathway is C₄? C₅ bond fission producing the resonance-stabilized 3-methylpropargyl radical. There is a concurrent process producing molecular hydrogen and penta-1,2,4-triene presumably via the intermediate formation of cis-penta-1,3-diene. The 1,4-hydrogen elimination from cis-penta-1,3-diene is the rate-determining step in the molecular pathway. This is supported by an independent VLPP study of cis- and trans-penta-1,3-diene. RRKM calculations show that the experimental rate constants for C? C bond fission are consistent with the following high-pressure rate expression at 1100 K: where θ = 2.303RT kcal/mol and the A factor was assigned from the results of shock-tube studies of related alkynes. The activation energy leads to ΔH[CH₃C?C?H₂] = 70.3 and DH[CH₃CCCH₂? H] = 87.4 kcal/mol. The resonance stabilization energy of the 3-methylpropargyl radical is 10.6 ± 2.5 kcal/mol, which is consistent with previous results for this and other propargylic radicals.     

Zur Reaktivität der Ferriophosphaalkene [(η5‐C5Me5)(CO)2FeP=C(NR)R2] (NR = NMe2, NC5H10, R2 = Ph,tBu) gegenüber Protonsäuren,Alkylierungsmitteln und [{(Z)‐Cycloocten}Cr(CO)5]

Transition Metal‐substituted Phosphaalkenes. 42 Reactivity of the Ferriophosphaalkenes [(η⁵‐C₅Me₅)(CO)₂FeP=C(NR )R²] (NR = NMe₂, NC₅H₁₀, R² = Ph, t Bu) towards Protic Acids, Alkylation Reagents, and [{( Z )‐Cyclooctene}Cr(CO)₅] The reaction of equimolar amounts of [(η⁵‐C₅Me₅)(CO)₂FeP=C(NR )R²] ( 2 a : NR = NMe₂, R² = Ph; 2 b : NMe₂. tBu; 2 c : NC₅H₁₀, Ph) and etherial HBF₄ gave rise to the formation of [(η⁵‐C₅Me₅)(CO)₂FeP(H)C(NR )R²] (BF₄) ( 3 a – c ) which were isolated as light red powders. Compounds 2 a – c were converted into [(η⁵‐C₅Me₅)(CO)₂FeP(Me)C(NR )R²] (SO₃CF₃) ( 4 a – c ) by treatment with methyl trifluoromethane sulfonate. In addition 2 a and Me₃SiCH₂OSO₂CF₃ afforded light red [(η⁵‐C₅Me₅)(CO)₂FeP(CH₂SiMe₃)C(NMe₂)Ph](SO₃CF₃) ( 5 ). The black complex [(η⁵‐C₅Me₅)(CO)₂FeP{Cr(CO)₅}C(NMe₂)Ph] ( 6 ) resulted from the combination of 2 a with [{(Z)‐cyclooctene}Cr(CO)₅]. The novel products were characterized by elemental analyses and spectra (IR, ¹H‐, ¹³C‐ und ³¹P‐NMR).     

UV absorption spectra and kinetics of the self reaction of CFCl2CH2O2 and CF2ClCH2O2 radicals in the gas phase at 298 K

The ultraviolet absorption spectra of the peroxy radicals derived from hydrochlorofluorocarbons 141b and 142b, (CFCl₂CH₂O₂ and CF₂ClCH₂O₂, respectively), and the kinetics of their self reactions have been studied in the gas phase at 298 K using a pulse radiolysis technique. Absorption cross sections were quantified over the wavelength range 220–300 nm. Measured absorption cross sections at 250 nm were indistinguishable within the experimental uncertainties (≈10%) and yield; Errors represent the sum of statistical uncertainty and our estimate of potential systematic errors. Our absorption cross section data were then used to derive the observed self reaction rate constants for reactions (1) and (2), defined as ?d[RO₂]/dt = 2k[RO₂]² (R = CFCl₂CH₂ or CF₂ClCH₂), of k_1obs = (4.36 ± 0.64) × 10^?12 and k_2obs = (4.13 ± 0.58) × 10^?12 cm³ molecule^?1 s^?1, quoted errors represent 2σ. These results are discussed with respect to previous studies of the absorption spectra and kinetics of peroxy radicals.     

The analytical resolution of parallel first‐ and second‐order reaction mechanisms

Given the species A₁ and A₂, the competition among the three different elementary processes (1) (2) (3) is frequently found in thermal and photochemical reaction systems. In the present paper, an analytical resolution of the system (1)–(3), performed under plausible contour conditions, namely, finite initial molar concentrations for both reactants, [A₂]₀ and [A₁]₀, and nonzero reaction rate coefficients k₁, k₂, and k₃, leads to the equation [A₁] = ((δ[A₂]^γ ? [A₂])/β) ? α, where α = k₁/2k₃, γ = β + 1 = 2k₃/k₂, and δ = ([A₂]₀ + β[A₁]₀ + β α))/[A₂]₀^γ. The comparison with a numerical integration employing the fourth‐order Runge–Kutta algorithm for the well‐known case of the oxidation of organic compounds by ferrate ion is performed. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 562–566, 2010