Yu. F. Oprunenko

Indenyl and flourenyl transition metal complexes : III. Some new reactions of flourenyl- and indenyl-metal tricarbonyl anions

Abstract Deprotonation of η 6 -flourenechromium tricarbonyl (III) with excess t-BuOK in THF at70°C yields [η 6 -C 13 H 9 Cr(CO) 3 ] − K + (Ia), which isomerizes to η 5 -C 13 H 9 Cr(CO) 3 Cr − K + (II) at temperatures above −20°C. [η 6 -C 13 H 9 Cr(CO) 3 ] − Li + (Ib) may be obtained in the solid state by treatment of III with BuLi in absolute ether followed by precipitation with n-hexane. Methylation of Ib and II with methyl iodide goes stereospecifically to give η 6 - exo - (IX) and η 6 -(9- endo -methylfuorene)chromium tricarbonyl (XII) from Ib and II, respectively. Acylation of Ia with CH 3 COCl yields the acetate of 9-acetylfluorenechromium tricarbonyl (VII) in its enol form. Treatment of III with excess t-BuOK and CH 3 I in THF at −30°C leads to the derivative (XI), which is fully methylated at C(9). Phenyldiazonium borofluoride, diphenyliodonium iodide, ferrocenium borofluoride, trimethylchlorostannane and triethylbromogermane react with η 5 -C 9 H 7 (CO) 3 M − K + in THF to give compounds of the η 5 -series: η 5 -C 9 H 7 (CO) 2 MN 2 C 6 H 5 (M  Cr, Mo, W), η 5 -C 9 H 7 (CO) 3 WC 6 H 5 , [η 5 -C 9 H 7 (CO) 3 M] 2 (M  Mo, W), η 5 -C 9 H 7 (CO) 3 MSnMe 3 (M  Cr, Mo, W) and η 5 -C 9 H 7 (CO) 3 MGeEt 3 (M  Cr, Mo, W), respectively.

Inter-ring η6⇄η6 haptotropic rearrangements in naphthalenetricarbonylchromium complexes

Abstract Two methods for the controlled introduction of substituents in the coordinated and non-coordinated ring of η 6 -naphthalenetricarbonylchromium are proposed. When the selectively substituted naphthalenetricarbonylchromium complexes are heated the tricarbonylchromium groups are redistributed between the substituted and the unsubstituted rings because of inter-ring haptotropic rearrangements. The rate constants of these isomerizations were measured. During rearrangement of individual isomers of (1-methylacenaphthene)tricarbonylchromium the configuration of the methyl group does not change, thus testifying to intramolecular rearrangements.

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 : VIII. Synthesis, structure and properties of metal carbonyl derivatives of azafluorenes, indole, carbazole and the corresponding anions

Abstract The interaction of indole, carbazole and aza-analogues of fluorene, 1-azafluorene (I), 2-azafluorene (II), 3-methyl-II (III), 3-azafluorene (IV), 4-azafluorene (V), 7-methyl-V (VI) and [2,3]benzo-V (VII) with Cr(CO)6 (diglyme/heptane, 140° C), and with (NH3)3Cr(CO)3 (boiling dioxan) and of II with [BrM(CO)5] [NEt4] (M  Cr, Mo, W) has been studied. In all cases II and IV form only N-donor complexes of the LCr(CO)5 type, and the other heterocycles: arene-chromium tricarbonyl derivatives coordinated to the benzene, and not the heterocyclic, ring. The interaction of I and III with (NH3)3Cr(CO)3 results in the formation of a mixture of both types of complexes, predominantly arene ones. Reactions with (NH3)3Cr(CO)3 give appreciably higher yields than similar processes involving Cr(CO)6. Deprotonation of arenechromium tricarbonyl compounds (THF, t-BuOK) leads to η6-anions which reversibly isomerize in the case of complexes Ill, V and VI into η5-anions. These are new examples of metallotropic tautomerism in which the metal “slips” between the rings along the plane of the aromatic ligand. In the case of η6-anions of complexes of indole, carbazole, I and VII no such isomerization takes place. Alkylation of η6-anions yields 9-exo-alkyl compounds. These are also the only substances that can be isolated from the alkylation of tautomeric mixtures of anions obtained from XI, XIII and XXIV.

Indenyl and fluorenyl transition metal complexes: XIII. Determination of geometric configuration of (9-substituted fluorenes)chromium tricarbonyl complexes by ASIS-effect in 1H NMR spectra☆

Abstract A method to determine the geometric configuration of chromium tricarbonyl complexes of 9-substituted fluorenes (η 6 -9-RC 13 H 9 )Cr(CO) 3 which allows one to distinguish between exo -isomers (IIIa–e) and endo -isomers (Va–e) is proposed; a, R = CH 3 ; b, R = CH 2 HC 6 H 5 , c, R = D; d, R = t-C 4 H 9 ; e, R = C 6 H 5 . This method is based on measuring chemical shifts induced in 1 H NMR spectra by aromatic solvents when passing from CDCl 3 to C 6 D 6 solutions (ASIS effect). The validity of the criterion is confirmed by X-ray analysis of IIIb. Exo -isomers, IIIb,c, were obtained by alkylation of the η 6 -fluorenylchromium tricarbonyl anion (I) with the corresponding halides RX in tetrahydrofuran (THF) at low temperature. Endo -isomers (Vb,c) have been obtained by alkylation of the η 6 -fluorenylchromium tricarbonyl anion (II) with subsequent thermal rearrangement of intermediate σ-organometal derivatives (IV) without their isolation. Endo -isomers, Vd,e, have been formed by stereoselective protonation of substituted complex anions [(η 6 -9-RC 13 H 8 )Cr(CO) 3 ] − .

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: X. Anionic chromium tricarbonyl complexes of fluoradene, substituted fluorenes and indene: The structure of ion pairs and η6 → η5 rearrangements

Abstract The metallotropic η 6 ⇌ η 5 tautomeric equilibrium in anionic chromium tricarbonyl complexes of fluoradene, substituted fluorenes and indene has been studied. A criterion is proposed for determining the ion-pair type in η 6 -anions according to the E -band splitting in the ν(CO) region of their IR spectra. The influence of ligand structure and cation solvation on K eq. is discussed.

Indenyl- and fluorenyl-transition metal complexes: XI. Intramolecularity of the haptotropic η6⇌η5 rearrangements in fluorenylchromium tricarbonyl anions by crossover experiments☆

Abstract The intramolecular character of equilibrium and reversible isomerization of η6- and η5-fluorenylchromium tricarbonyl anions (IXa, IXb) is proved using crossover experiments. The rearrangement IXa ⇌ IXb in the presence of 9-methylfluorenyl anion does not yield mixed products, i.e. η6- or η5-9-methylfluorenylchromium tricarbonyl anions. Similarly, under conditions of equilibrium between η6- and η5-(2,7-dideuterofluorenyl)chromium tricarbonyl anions (XIIa, XIIb) in the presence of non-deuterated fluorenyl anion, redistribution of the chromium tricarbonyl group among deuterated and deuterium-free fluorenyl anions does not take place.

A density functional study of intra- and interring haptotropic η2,η2 rearrangements in rhodium, ruthenium, and osmium naphthalene complexes

The density functional theory method was used to perform quantum-chemical modeling of the mechanisms of η2,η2-intraring (Intra-HR) and η2,η2-interring (Inter-HR) haptotropic rearrangements for μ2 complexes of naphthalene with rhodium, ruthenium, and osmium. The structure of transition states and intermediates was studied, and the energy parameters of haptotropic rearrangements in these complexes were determined. We used the PBE functional, the TZV2p three-exponential basis set for valence electrons, and the SBK-JC relativistic pseudopotential for core electrons. η2,η2 Intra-HR was found to occur inside the aromatic ring of η2 naphthalene complexes without going outside it through intermediates and transition states with ηn structures (n = 1, 2). Inter-HR occurred as metal replacements on the periphery of the naphthalene ligand through intermediates and transition states with ηn structures (n = 1, 2, 3) from one ring into another. The calculated activation barriers for η2,μ2 Intra-HR and η2,η2 Inter-HR in the complexes studied closely agree with their experimental values.

New dinuclear palladium complex with a Chinese-lantern structure

The new dinuclear palladium complex Pd2(μ-S,N-SC7H5N2)4 with a Chinese-lantern structure was synthesized by the reaction of K2PdCl4 with 2-mercaptobenzimidazole and structurally characterized by X-ray diffraction analysis.