Yu. N. Luzikov

Indenyl-and flourenyl-transition metal complexesss : I. Synthesis, structures, and reactions of ν5-and ν6-derivatives of chromium group metals

Abstract The reaction leading to the ν5-fluorenyl-and ν-indenyl-tricarbonylmetallate anions, ν5-C13H9(CO)3Cr- and ν5-C9H7(CO)3M- where M stands for Cr, Mo, W have been studied. Deprotonation of (ν6-fluorene)Cr(CO)3 with t-BuOK seemingly proceeds via the corresponding ν6-anionic intermediate which is transformed into the ν5-isomer with a conversion halftime of several minutes. Chromium and molydenum ν5-anions rearrage on treatment with CH3COOH to the corresponding ν6-indene and fluorene complexes. Protonation of ν5-C9H7- (CO)3W- leads to the stable hyride ν5-C9H7(CO)3WH. All the anions studied react with Hg(CN)2 to give symmetric organomercury derivatives containing M–Hg bonds (M=Cr, Mo, W). The reaction of ν5-C9H7(CO)3Cr- and ν5-C13H9 structure and containing a Cr–CH3 bond: the product ν5-C9H7(CO)3CrCH3 has undergo thermal rearrangement to the ν6-compounds via transfer of the CH3 group to the five-membered ring and of the Cr(CO)3 group to the benzene nucleus. The molybdenum and tungsten anions form stable σ-methyl derivatives in reactions with CH3I. The possible reversible isomerization processes involving anionic and neutral compounds are considered form mechanic and stereo-chemical points view.

Relative migratory abilities of metals for cyclopentadienyl and indenyl ligands

Abstract The 1 H and 13 C{ 1 H} NMR spectra of the fluxional molecules C 9 H 7 Si-(CH 3 ) 3 , C 9 H 7 Ge(CH 3 ) 3 , and C 9 H 7 Sn(CH 3 ) 3 have been studied over a wide range of temperatures. The metal atom in the indenylgermane migrates through a 1,2 shift. This is shown by isolation of the Diels—Alder cycloaddition adducts of this compound with the dienophiles tetracyanoethylene, maleic anhydride and acetylene dicarboxylate. The thermodynamic characteristics of metallotropic migration in the Group IVB indenyl derivatives show that the difference between the free energies of activation of indenyl and the corresponding cyclopentadienyl compounds in each case is close to 8.5 kcal/mole. New parameters, μ and r a , characteristic of the fluxional behaviour of some organometallic compounds have been introduced, and some predictions based on these parameters have been made.

Electron-donating ability of triarylphosphines and related compounds studied by 31P NMR spectroscopy

The influence of aryl, heterocyclic, amide, alkyl, alkoxyl, thioalkoxyl, and ferrocenyl substituents at the phosphorus atom on its electron-donating ability was studied by the measurement of direct 31P—77Se spin-spin coupling constants for the corresponding selenides. Series of diphenylorganylphosphines and their selenides were studied.

Intramolecular rearrangements in tris(trimethylsilyl)cyclopentadiene

Abstract Clear-cut temperature dependences of line shapes and line intensities in NMR spectra recorded for tris(trimethylsilyl)cyclopentadiene (I) and for the deuterated analogue (II) demonstrate that metallotropic and prototropic intramolecular rearrangements occur in these compounds. Four possible migration routes for metallotropic rearrangements in compounds I and II have been considered. It has been shown that temperature dependences of PMR and 13 C—{ 1 H} NMR spectra for I and II and a Diels—Alder reaction of I with acetylenedicarboxylic ester may be explained only in terms of four successive 1,2 shifts of the metal. A detailed description of dynamic processes in tris(trimethylsilyl)cyclopentadiene has been made on the basis of total line shape studies carried out for 1 H—{ 2 H} NMR spectra of II under exchange conditions. These spectra avoid complications from spin—coupling effects. The effect of introduction of organometallic groups in the cyclopentadienyl ring on the metallotropic rearrangement is discussed. An attempt is made to extend the concept of relative migratory ability of metals so as to include cyclopentadienyl ligands.

Indenyl and fluorenyl transition metal complexes : VII. Innersphere “ricochet” rearrangements on alkylation of η5-indenyl- and η5-fluorenyltricarbonylchromate anions

Abstract Alkylation of K[η 5 -C 9 H 7 Cr(CO) 3 ] (Xa) with CH 3 I and C 6 H 5 CH 2 Br leads to σ-alkyl derivatives of η 5 -C 9 H 7 Cr(CO) 3 Alk type. These complexes undergo innersphere “ricochet” rearrangement, with the alkyl group being shifted to the endo position at C(1) and the chromium tricarbonyl group shifted to the benzene nucleus. The structure of the product of such a rearrangement in the case of η 5 -C 9 H 7 (CO) 3 CrCH 2 C 6 H 5 , i.e. (1-benzyl-3a,4-7,7a-η 6 -indene)chromium tricarbonyl (XVIII), is established by a low temperature X-ray study, indicating an endo position for the benzyl radical. On alkylation of equilibrium tautomeric mixtures of η 5 - and η 6 -fluorenylchromium tricarbonyl anions XIa ⇌ XIb under similar conditions, the η 5 -anion (Xa) yields a σ-alkyl derivative, which is rearranged to (9- endo -alkyl-1-4,4a,9a-η 6 -fluorene)chromium tricarbonyl. Electrophilic attack of the η 6 -anion (XIb) takes place on the outer side at C(9) and leads to a corresponding 9- exo -alkyl derivative.

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

IR and PMR spectroscopy was used to study the reversible isomerization of η6- and η5-fluorenylchromium tricarbonyl anions (I and II, respectively) in solutions. Consideration was given to the dependence of the equilibrium position and nature of the resulting particles on the type of cation (Li+, Na+, K+, Ph3PCH3+, n-Bu4N+), the solvent and the presence of solvating cation additives (dicyclohexyl-18-crown-6 (IV), DMSO). The η5-isomer exists in THF solution as an equilibrium mixture of solvent-separated and contact ion pairs (SSIP and CIP, respectively), the cation in the latter being located near the oxygen atom of one of the carbonyl groups. The existence of such an equilibrium is also shown for the salts of the C5H5(CO)3Cr− anion. The dependence of the equilibrium constants for I ⇄ II on the above factors was determined. For the K salt in THF solution at 28°C both IR and PMR spectroscopy gave fairly coincident values of Keq equal to 7.15 and 7.35, respectively. IR spectroscopy was applied to the kinetic studies of the reversible isomerization of K salts of I and II at 0—28°C with and without crown ether IV. The process is shown to be entropy controlled. The equilibrium position is governed by the type of cation, the degree of its solvation and the temperature. The factors promoting the formation of SSIPs lead to the equilibrium being shifted towards I.

Indenyl and fluorenyl transition metal complexes : VI. Analysis of 13C NMR spectra of some fluorenechromium tricarbonyls

Abstract Carbon-13 NMR spectra of the η6-fluorenyl complexes (fluorene- (I), 3-methylfluorene- (II), and 6-methylfluorenechromium tricarbonyl (III) are described by the means of the “fingerprint” method, 13C spin-lattice relaxation time measurements, and an additive calculation of carbon chemical shifts of the methyl-substituted complexes (II,III). This sequence of operations can be used to analyze 13C NMR spectra of related polyaromatic transition metal complexes and their isomeric mixtures containing species of the same or different structural types.

Synthesis and Conformations of Adamantylated Calix[5]- and -[6]arenes

Procedures have been developed for the preparation of completely and partially adamantylated calix[n]arenes (n = 5, 6) by reaction of 3-R-substituted 1-hydroxyadamantanes (R = H, 4-MeC6H4, 4-MeSO2C6H4, 4-HO-3-HOCOC6H3, HOCOCH2) with p-H-calix[n]arenes (n = 5, 6) and 5,11,23,29-tetra-tert-butylcalix[6]arene in trifluoroacetic acid. Lower- and upper-rim modification of the prepared compounds has been studied. According to the 1H NMR data, adamantylcalix[6]arenes possessing carboxymethyl groups in the adamantane moieties are characterized by reduced conformational mobility.

Alkylation of schleyer's lithiocarbon C4Li4 by methyl iodide

Abstract Alkylation of lithiocarbon C 4 Li 4 gives the hydrocarbon C 8 H 12 to which the structure of tetramethyltetrahedrane has been ascribed.

Synthesis and photochemical properties of phenoxy derivatives of anthra[2,3- b ]furan-5,10-dione

Nucleophilic replacement of the hydroxy groups in ethyl 4,11-dihydroxy-2-methyl-5,10-dioxo-5,10-dihydroanthra[2,3-b]furan-3-carboxylate by chlorine upon treatment with phosphorus acid chlorides gave the corresponding 4(11)-chloro derivatives which were converted into photochromic ethyl 4(11)-phenoxy-2-methyl-5,10-dioxo-5,10-dihydroanthra[2,3-b]furan-3-carboxylates. Photoinduced decomposition of the latter leads to the formation of phenol and fluorescent hydroxyanthra[2,3-b]furandiones.