L. N. Novikova

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.

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: 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 ] − .

Oxidative dehydrodimerization of manganese phenylvinylidene complex (η5-C5H5)(CO)2MnCC(H)Ph. X-ray structure of phenyl(trityl)vinylidene complex (η5-C5H5)(CO)2MnCC(CPh3)Ph

Abstract The oxidatively induced dehydrodimerization of the manganese vinylidene complex (η 5 -C 5 H 5 )(CO) 2 MnCC(H)Ph ( I ) to the bis-vinylidene compound (η 5 -C 5 H 5 )(CO) 2 MnCC(Ph)C(Ph)CMn(CO) 2 (η 5 -C 5 H 5 ) ( II ) proceeds via C β H bond homolysis in the radical cation ( I + ) and is thought to involve the formally 16-electron mononuclear σ-phenylethynyl cation [(η 5 -C 5 H 5 )(CO) 2 MnCCPh] + ( III ) and the bis-carbyne dication [(η 5 -C 5 H 5 )(CO) 2 MnCC(Ph)C(Ph)CMn(CO) 2 (η 5 -C 5 H 5 )] 2+ ( II 2+ ) as the key sequential intermediates. Compound II 2+ was characterized by IR and CV. The reduction of II 2+ with (C 6 H 6 ) 2 Cr gave II in an 80% yield. Compound II can be prepared more conveniently by treating I with (C 5 H 5 ) 2 FeBF 4 in the presence of Et 3 N. The interaction of I with Ph 3 CPF 6 yields the trityl(phenyl)vinylidene complex (η 5 -C 5 H 5 )(CO) 2 MnCC(CPh 3 )Ph ( IV ) as a result of the electrophilic attack of the trityl cation on C β followed by the loss of a proton. The structure of IV was established by an X-ray structural analysis.

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.

Indenyl and fluorenyl transition metal complexes: XV.Reactions of 1,1-dimethylindene, spirocyclopropane-1,1-indene, and spirocyclopropane-9,9-fluorene with L3M(CO)3 (L = NH3, Py; M = Cr, Mo, W)☆

Abstract Reaction of indene, 1,1-dimethylindene, spirocyclopropane-1,1-indene, and spirocyclopropane-9,9-fluorene with Py 3 M(CO) 3 /BF 3 · OEt 2 (M = Cr, Mo, W) involves two competing processes: (i) the formation of the 6 -arene complexes (A) and (ii) the oxidative addition at the C(1)R and C(9)R bonds (R = alkyl) with the formation of chelated σ,π-complex ( B ). The reaction pathway ( A or B ) is determined both by the metal and the ligand.

Indenyl- and fluorenyl-transition metal complexes. XII: Synthesis and deprotonation of η6-fluorenemolybdenum and -tungsten tricarbonyls and η6-indenemolybdenum tricarbonyl

Abstract Py 3 Mo(CO) 3 reacts with fluorene and indene in ether in the presence of (C 2 H 5 ) 2 O· BF 3 to give η 6 -C 13 H 10 Mo(CO) 3 (I) and η 6 -C 9 H 8 Mo(CO) 3 (III), respectively. The analogous reactions of Py 3 W(CO) 3 lead to η 6 -C 13 H 10 w(CO) 3 (II) and η 5 -C 9 H 7 (CO) 3 WH (V), respectively. On deprotonation of I–III the corresponding unstable η 6 -anions are formed which rearrange into η 5 -isomers. The rate of these rearrangements is considerably higher than that of the analogous process for η 6 -C 13 H 9 Cr(CO) 3 − .

Oxidation of theexo- andendo-phenylcyclohexadienyl iron complexes Fe(η5-6-PhC6H6) (η5- C5H5)

The roe of oxidatively induced homolyhc scission a the C(sp3)-H bonds in the iron phenykychhexadienyl complexes Fe(η5-6-PhC6H6)(η5-C5H5) (1) depends on the spatial orientation of the Ph substitutent. In the case of the (1endo+) radical cation this process, resulting in the cationic biphenyl complex (Fe(η6 -C6H5C6H5)(η5-C5H5)]+ (2+), is fast and proceeds for several minutes. In the case of the more stable radical cation (1exo+) the formation of 2+ is slow and takes tens minutes to complete.

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 ButOK inm-xylene followed by boiling of the reaction mixture gives phenylferrocene (7) as the product of η6:η6 haptotropic rearrangement.

Redox-induced ?5 ? ?3 haptotropy of the fluorenyl ligand in 9-substituted ?5-fluorenylmanganesetricarbonyl complexes

It has been shown by cyclic voltammetry in THF within the −90 to 40 °C temperature range that fluorenyl (η5-9-R-C13H8)Mn(CO)3 complexes (R=But (3) and Ph (4)) undergo two-electron reduction to form allyl type [(η3-9-R-C13H8)Mn(CO)3]2− dianions as final products. At low temperatures complexes3 and4 are reduced in two one-electron steps according to the EEC-scheme. The first step is reversible and corresponds to the formation of 19ē-radical anions 3−. and 4−.. TheE0 values for redox pairs30/−. and40/−. are −1.88 and −1.73 V, respectively. The further reduction of radical anions3−. and4−. at more negative potentials is accompanied by fast η5 → η3 haptocoordination of the fluorenyl ligand to form 18ē-dianions [(η3-9-R-C13H8)Mn(CO)3]2−. These dianions obtained by the reduction of complexes3 and4 by the radical anion of pyrene are stable at −80 °C and are characterized by their IR spectra. At room temperature the η5 ⇔ η3 hapticity change is a fast and reversible process occurring at the step of 19ē-radical anions3−. and4−. and leading to the electron deficient 17ē-species [(η3-9-R-C13H8)Mn(CO)3]−., which are reduced easier than the initial complexes. As a result, complexes3 and4 are reduced to the corresponding dianions [(η3-9-R-C13H8)Mn(CO)3]2− at room temperature in one reversible two-electron step according to the ECE-scheme. Reactivities of 19e−-species of the isomeric η5- and η6-fluorenylmanganesetricarbonyl complexes are compared.