Kinetics of η6→η5 isomerization of (η6-fluorenyl)(η5-cyclopentadienyl)iron

The kinetics of the reversible isomerization of the zwitterionic complex [(⁶-C₁₃H₉)Fe(⁵-C₅H₅)] (1) into dibenzoferrocene (2) was studied by electronic spectroscopy in the temperature range from 70 to 103 °C. The activation parameters of the reaction 1 2 were determined, E _a = 22.5 kcal mol^–1.     

Reaction of fluorinated β-dicarbonyl compounds with ethylmercaptan

Conclusions Addition of ethylmercaptan to fluorinated-diketones proceeds through the enol form at the carbon atom bound to the fluoroalkyl substituent; with fluorinated-ketoesters it is also the enol form which reacts with the mercaptan.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2293–2298, October, 1985.     

Oxidation of (η5-6-exo-cyclopentadienylcyclohexadienyl)- (η5-cyclopentadienyl) iron by trityl hexafluorophosphateby trityl hexafluorophosphate

Oxidation of the cyclohexadienyl complex Fe(η⁵-C₅H₅)(1-5-7⁵-6-exo-C₅H₅-C₆H₆) (2) by (Ph₃C)PF₆ (CH₂Cl₂, from −30 to +20 °C) occurs as two concurrent processes: elimination of an H atom from the cyclohexadienyl ligand and replacement of an H atom in the cyclopentadienyl ring by a CPh₃ fragment. A mixture of cationic complexes [Fe(η⁵-C₅H₅) (η⁶-Ph-C₅H₅]⁺ (1⁺) and [Fe(η⁵-C₅H₄CPh₃) (η⁶-Ph-C₅H₅]⁺ (4⁺) (4 ⁺) with PF₆ ⁻ anions is obtained. Deprotonation of the mixture of 1⁺ and 4⁺ complexes under the action of Bu ^t OK inm-xylene followed by boiling of the reaction mixture gives phenylferrocene (7) as the product of η⁶:η⁶ haptotropic rearrangement. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, NO. 5, pp. 1045–1047, May, 1997.     

Mechanisms and kinetics of the elementotropic rearrangements of tetrahydro-4,4,8,8-tetramethyl-4,8-disila-sym-indacene

The dynamic stereochemistry of silatropic rearrangements of tetrahydro-4,4,8,8-tetra-methyl-4,8-disila-sym-indacene (dimer of 6,6-dimethyl-6-silafulvene), which exists in solution as an equilibrium mixture of two interconverting isomers, was studied. The mechanisms and complete kinetic scheme of rearrangements were established using¹H,¹³C, and²⁹Si 2D quantitative EXSY NMR spectroscopy. It was found that the interconversion and degenerate rearrangements of the observed isomers proceedvia two concurrent pathways due to the formation of different intermediates. The activation parameters of the rearrangements were determined by means of total lineshape analysis of dynamic NMR (DNMR) spectra. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1285–1295, July, 1997.     

CNDO/2 calculation of prototropic rearrangement in cyclopentadiene

A self-consistent procedure has been worked out for the optimisation of geometrical parameters of ground and transition states of molecular systems and chemical reactions. For cyclopentadiene molecule, the CNDO/2 method is used to calculate a number of the geometrical configurations which lie at the reaction co-ordinates corresponding to possible channels of the proton migration.     

Indenyl and fluorenyl transition metal complexes IX. A study of the reversible isomerisation of η6- and η5-fluorenylchromium tricarbonyl anions by 13C NMR spectroscopy

¹³C NMR spectroscopy was used to study the reversible isomerisation of η⁶- and η₅-fluorenylchromium tricarbonyl anions. The influence of the electron withdrawing effect of the Cr(CO)₃ moiety on the π-electron distribution has been examined in the uncoordinated rings of η⁶-(I), η⁵-(II) fluorenylchromium tricarbonyl anions and fluorenylchromium tricarbonyl (III). IR spectra of I-M⁺ (M = Li, Na, K, Rb, Cs, Ph₃PCH₃) is discussed in connection with the structure of ion pairs in these salts.     

Heteroorganic betaines. 7. Synthesis and structure of a germanium-containing organophosphorus betaine Et3P+—CHMe—GeMe2—S–

Germanium-containing organophosphorus betaine Et₃P⁺—CHMe—GeMe₂—S^– was synthesized by the reaction of hexamethylcyclotrigermatrithiane with Et₃P=CHMe. The structure of the betaine was established by X-ray diffraction analysis and multinuclear NMR spectroscopy. In the crystal, the P⁺—C—Ge—S^– main chain of the molecule adopts a folded cis-gauche conformation due to strong Coulomb interactions between the anionic and cationic centers. The equilibrium geometry of the isolated molecule was calculated within the framework of the density functional theory (the PBE functional, the TZ2P basis set). The calculated geometric characteristics are in qualitative agreement with the X-ray data. The structure of the betaine is compared with the structure of its silicon-containing analog studied previously.     

Mechanisms of processes involving β-substituted cyclopropyl radicals. Ring expansion in the reaction with CO

The reaction of -substituted cyclopropyl radicals with CO was studied by ESR. Tile acyl radical resulting from the addition of CO to the cyclopropyl radical was detected. At temperatures near 270 K, an intramolecular rearrangement of the acyl radical affords substituted 2-oxocyclobutyl radicals (ring expansion reaction). Mechanisms for the free-radical transformations studied were suggested.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 497–499, February, 1996.     

New stable germylenes, stannylenes, and related compounds: 6. Heteroleptic germanium(II) and tin(II) compounds [(SiMe3)2N-E-OCH2CH2NMe2]n (E = Ge, n = 1; Sn, n = 2): synthesis and structure

New stable heteroleptic germanium(II) and tin(II) compounds [(SiMe₃)₂N-E¹⁴-OCH₂CH₂NMe₂]_n (E¹⁴ = Ge, n = 1 (1), Sn, n = 2 (2)) have been synthesized and their crystal structures have been determined by X-ray diffraction analysis. While compound 1 is monomer stabilized by intramolecular Ge ← N coordination, compound 2 is associated to dimer via intermolecular dative Sn ← O interactions.     

Synthesis and reactions of dicarbonyl (η2-indene)-η5-indenyl complexes of manganese and rhenium

Photochemical reactions of M(CO)₃(⁵-C₉H₇), where M=Mn (1) or Re (2), with indene have produced ²-indene complexes M(CO)₂(²-C₉H₈)(⁵-C₉H₇), where M=Mn (3) or Re (4). Deprotonation of complex3 witht-BuOK in THF at –60 °C gives the anion [Mn(CO)₂(¹-C₉H₇)(⁵-C₉H₇)^– (5), in which there occurs a rapid interchange of the Mn(CO)₂(⁵-C₉H₇) group between positions 1 and 3 in the ¹-indenyl ligand. The reaction of complex4 with Ph₃CPF₆ in CH₂Cl₂ at 0 °C leads to the complex [Re(CO)₂(³-C₉H₇)(⁵-C₉H₇)PF₆, whereas the similar reaction of complex3 gives only decomposition products even at –20 °C.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1280–1285, July, 1993.