bluuebunny/crossref_metadata_2025_split huggingface dataset:
2,4,6,8‐Tetraphenylbarbaralan – ein orangeroter, thermochromer Kohlenwasserstoff ohne Chromophor[1,2]
Authors: Quast Helmut , Knoll Katja , Peters Eva‐Maria , Peters Karl , Schnering Hans Georg Von 
Published: July 2007

2,4,6,8‐Tetraphenylbarbaralane – an Orange‐Red, Thermochromic Hydrocarbon Devoid of a Chromophore[1,2]The diphenylbicyclo[3.3.1]nonanedione 6 adds phenylcerium‐(III) dichloride to afford a high yield of the triphenyl‐2‐oxa‐twistanol 8. In contrast, phenyllithium yields a mixture of tri‐phenylhydroxyketone exo‐7, tetraphenylbicyclo[3.3.1]nona‐nediol 9, and 8. The latter is dehydrated by sulfuric acid in acetic acid to produce the triphenylbicyclo[3.3.1]nonenone 10 in almost quantitative yield. Addition of phenylcerium(III) dichloride to 10 affords a 3:2 mixture of the tetraphenylbicy‐clo[3.3.1]nonenols exo‐ and endo‐11 which may be separated by chromatography. Dehydration of the mixture yields quantitatively the tetraphenyldiene 12. On treatment with an excess of butylpotassium in pentane, 12 is converted to the deep violet, crystalline dipotassium salt 17 which may be purified by reprecipitation from its tetrahydrofuran solution with pentane. When the solution of 17 in tetrahydrofuran is slowly added to an excess of 1,2‐dibromoethane at –60°C, the dianion is immediately oxidized to produce the tetraphenylbarbara‐lane 4 which is isolated in 30% yield as orange‐red crystals after chromatography. – The structures of the new compounds are based on spectroscopic evidence and X‐ray diffraction analyses of 4, 8, exo‐11, and 12. The conformations in solution are inferred on the basis of vicinal proton coupling constants and a comparison with coupling constants calculated with the aid of the Karplus equation from torsional angles obtained by X‐ray diffraction analyses. The conformation of exo‐11 in solution closely resembles that present in the crystal. – While the barbaralane 4 exists as a pair of very rapidly rearranging degenerate valence tautomers in solution, the degeneracy is lifted in the crystal lattice. As a result, the crystal consists of two rapidly rearranging but non‐equivalent valence tautomers in a ratio of 9:1 as estimated from the apparent atomic distance C2–C8 of 4 and the C2–C8 bond length of the model barbaralane 18. – The orange‐red colour of 4 in the crystal and in solution results from a pronounced shoulder in the UV/Vis spectrum at 430 nm, the intensity of which strongly depends on the temperature. Thus, 4 is the first barbaralane which exhibits colour though it is lacking a classical long‐wavelength chromophore.
[2,3]1‐Thia‐Wittig Rearrangements Proceeding with Complete Inversion or with Partial Loss of Configuration at the Carbanionic Center
Authors: Brickmann Kay , Brückner Reinhard 
Published: July 2007

AbstractTwo pairs of diastereomeric γ1‐(benzyloxy)1‐α1‐(tributylstannyl) sulfides (anti‐ and syn‐13, anti‐ and syn‐30) were prepared, nBuLi induced tin/lithium exchange in each of these compounds furnished α1‐lithiated sulfides which underwent [2,3]1‐thia‐Wittig rearrangements in THF at – 78°C within 30 min. Competing [1,2]1‐thia‐Wittig rearrangements were not observed, not even starting from stannyl sulfides 30 where the [2,3] shift requires the intermediacy of lithium thiolates 32 in which the aromaticity of a benzene ring is given up. The homoallyl thiols syn‐ and anti‐19 were formed stereoselectively starting from the allylthio stannanes anti‐ and syn‐13, respectively. This implies that the underlying thia‐Wittig rearrangements are stereospecific and proceed with inversion of configuration at the carbanionic center, and that the lithio sulfides anti‐ and syn‐18 formed in the course of these reactions are configurationally stable until they rearrange. The benzylthio stannanes anti‐ and syn‐30 rearranged with low stereoselectivity. They furnished the benzyl thiols 33 as 71:29 and 28:72 mixtures of diastereomers, respectively. This means that the lithio sulfide intermediates involved in the latter rearrangements suffer some epimerization anti‐31 ⇄ syn‐31 prior to the sigmatropic bond shift.
Verbindungen mit dem 1,3,5,2‐Triazaphosphorinan‐Grundgerüst: Synthese und Koordinationschemie neuartiger,N,N,N′‐Trimethylethylendiamin‐substituierter Verbindungen mit drei‐und vierfach koordiniertem Phosphor
Authors: Kaukorat Thomas , Neda Ion , Fischer Axel , Jones Peter G. , Schmutzler Reinhard 
Published: July 2007

Compounds with the 1,3,5,2‐Triazaphosphorinane Skeleton: Synthesis and Coordination Chemistry of NovelN,N,N′‐Trimethylethylenediamine‐Substituted Compounds with Three‐and Four‐Coordinate PhosphorusSubstitution of chlorine for theN,N,N′‐trimethylethylenediamine group in the 1,3,5‐trimethylbiuret derivative2produced4. The reaction of the 1,3,5,2‐triazaphosphorinane4with sulfur furnished the expected P(=S) derivative5. Reaction of4with methyl iodide led to the formation of the ammonium iodide6by methylation of the nitrogen atom of the terminal NMe2group while the phosphorus atom of4remained unaffected. The structure of6was confirmed by a single‐crystal X‐ray structure analysis. In the unusual reaction of4with Br2the bromodimethylammonium‐bromophosphonium dibromide7was formed. The reaction of4with Fe2(CO)9furnished the expected Fe(CO)4complex8while with (C7H8)Cr(CO)4(C7H8norbornadiene)9was obtained. In9, norbornadiene is replaced byonemolecule of4, which is coordinated by phosphorus and the nitrogen atom of the NMe2group. In the reaction of4with C7H8Mo(CO)4(C7H8norbornadiene) the complexes10aand10bwere formed. In10a, the P(III) atom of4is coordinated to Mo; the second coordination site at Mo(CO)4is occupied by the nitrogen atom of the terminal NMe2group. In10b, the nitrogen atoms of the PN(Me) and of the NMe2grouping are coordinated to Mo, with formation of a five‐membered ring.
Alkyleisen‐und Alkylcobalt‐Reagenzien, VII. Über die Substitution des Halogens von Alkenylchloriden, Alkenylfluoriden und Alkinylhalogeniden durch Reagenzien des Typs R4MLi2 (MFe, Co)
Authors: Kauffmann Thomas , Sälker Reiner , Voß Karl‐Uwe 
Published: July 2007

Alkyliron and Alkylcobalt Reagents, VII[1]. – On the Substitution of the Halogen of Alkenyl Chlorides, Alkenyl Fluorides, and Alkynyl Halides by Reagents of the Type R4MLi2 (MFe, Co)Me4FeLi2 and Me4CoLi2, which are favourable reagents for the substitution of Br in alkenyl bromides[1–4], also proved to be favourable for the substitution of the halogen in alkenyl chlorides (yields 68–99%; nearly complete retention of configuration in the case of Me4FeLi2), β1‐fluorostyrene (best yield 92%), and 1‐fluoronaphthalene (best yield 47%). Me4FeLi2 differentiates between various alkenyl chlorides in 1:1 competition experiments better than Me4CoLi2 and is the optimal reagent for the substitution of halogen in 1‐chloro‐2‐phenylethyne (12), 1‐bromo‐2‐phenylethyne (13), and 1‐chloro‐3‐phenoxypropyne (15) by methyl (yields 70, 46, and 80%, respectively). Substitution of the halogen in 12 by the n1‐butyl, n1‐octyl, and phenyl residue is better achieved by the catalytic systems RMgBr + 2.5 mol % FeCl2 (RnBu, nOct, Ph; yields 75, 63, and 96%, respectively) than by the reagents nBu4FeLi2, nBu4Fe(MgBr)2, nOct4Fe(MgBr)2, or Ph4Fe(MgBr)2 (yields 18–28%).
2,6‐Dicyan‐4,8‐diphenylbarbaralan
Authors: Quast Helmut , Geißler Evelyn , Herkert Thomas , Knoll Katja , Peters Eva‐Maria , Peters Karl , Schnering Hans Georg Von 
Published: July 2007

2,6‐Dicyano‐4,8‐diphenylbarbaralane[1]Conjugate addition of the phenylcuprate reagent, obtained from phenyllithium, copper(I) cyanide, and boron trifluoride–diethylether, to the bicyclo[3.3.1]nonadienedione 3 affords the diphenylbicyclo[3.3.1]nonanedione 4 in high yield. Catalyzed by the potassium cyanide/18‐crown‐6 complex, addition of trimethylsilyl cyanide produces a mixture of the diastereomeric bis[O‐(trimethylsilyl)cyanohydrins] exo,exo‐, exo,endo‐ and endo,endo‐5. The hydrogen fluoride – pyridine complex in phosphorus oxychloride as solvent and, subsequently, an excess of pyridine convert the diastereomers 5 into the unsaturated γ,γ′1‐diphenyldinirile 6. This is brominated by N1‐bromosuccinimide to yield the γ,γ′1‐dibromodinitriles exo‐ and endo‐ 7 (6:1). The predominant diastereomer exo‐7 is debrominated by the zinc‐copper couple to afford the orange‐red title compound 2 in 78% yield. More conveniently, the unsaturated dinitrile 6 is converted to 2 in a single step by treatment with hexachloroethane and concentrated aqueous sodium hydroxide in the presence of tetrabutylammonium hydroxide as phase‐transfer catalyst. Surprisingly, low yields of 2 are also obtained when the bis[O‐(trimethylsilyl)cyanohydrins] 5 or the unsaturated dinitrile 6 are treated with phosphorus oxychloride in boiling pyridine. – The structures of the new compounds are based on spectroscopic evidence and X‐ray diffraction analyses of 2, 4, and endo,endo‐5. The conformations of 4 and endo,endo‐5 in solution are inferred on the basis of vicinal proton coupling constants and a comparison with coupling constants calculated with the aid of the Karplus equation and torsional angles obtained by X‐ray diffraction analyses. – While the barbaralane 2 exists as a pair of very rapidly rearranging degenerate valence tautomers in solution, the degeneracy is lifted in the crystal lattice. As a result, the crystal consists of two rapidly rearranging but non‐equivalent valence tautomers in a ratio of 9:1 as estimated from the apparent atomic distance C2–C8 of 2 and the C2–C8 bond length of non‐rearranging barbaralanes. – The colour of 2 in the crystal and in solution results from a maximum at 436 nm which increases on heating of the solution to 450 K. Cooling to 77 K results in reversible fading and the disappearance of the maximum. Thus, 2 is a barbaralane like 1 which exhibits colour though it is lacking a classical long‐wavelength chromophore.
Fünf‐ und sechsfach koordinierte Hydrido(phenolat)‐ und Hydrido(thiophenolat)‐Komplexe von Ruthenium und Osmium
Authors: Tena Migel Angel , Nürnberg Oliver , Werner Helmut 
Published: July 2007

Penta‐ and Hexacoordinate Hydrido(phenolate) and Hydrido(thiophenolate) Complexes of Ruthenium and OsmiumThe hydrido(phenolate)‐ and Hydrido(thiophenolate)ruthenium and ‐osmium complexes [MH(EC6X5)(CO)(PiPr3)2] (2–4, 10, 11, 15–19) have been prepared from [MHCl(CO)(PiPr3)2] and NaEC6X5 in good to excellent yields. Whereas in 2, 3, 15, 16 and in all the hydrido(thiophenolate) complexes the EC6X5 ligand is η1‐bonded (by O or S), in 4 and 17 the pentachlorophenolate is coordinated in a bidentate mode. This is confirmed by the X‐ray structural analysis of 4 which reveals a surprisingly short Os–Cl distance. The compounds 2 and 3 react with O2 to give stable 1:1 adducts 7, 8 and with CS2 by insertion to yield [MH(η2‐S2COC6X5)(CO)(PiPr3)2] (5, 6). From 10, 11, 19 and CS2, the corresponding trithiocarbonate complexes 12, 13, 20 have been prepared. Treatment of 4 with Cl2 leads to the formation of [OsCl(η2‐OC6Cl5)(CO)(PiPr3)2] (9) by cleavage of the Os–H bond.
Darstellung und optische Eigenschaften endständig substituierter Polyene mit Androstan als Spacer
Authors: Effenberger Franz , Strobel Hartmut 
Published: July 2007

Synthesis and Optical Properties of Terminally Substituted Conjugated Polyenes with Androstane as SpacerThe conjugated polyenes 10, 11, 21, 22, and 26 with 9‐anthryl and 2‐tetraphenylporphyrinyl (TPP) terminal groups and an androstane unit incorporated into the polyene chain were synthesized by Wittig or Wittig‐type olefinations. In most but not all cases the desired all‐(E) isomers could be obtained from the (E)/(Z)‐isomeric mixtures by chromatographic purification. From the UV/Vis spectra it is concluded that in all cases the TPP group and the polyene chain are electronically separated, whereas the 9‐anthryl residue and the connected dienyl moiety in 10 and 11 are electronically amalgamated. In 21, 22, and 26 a selective excitation of the anthryl group, the TPP moiety, and the polyene is possible.
Cycloadditionen von 6H‐1,3,4‐Oxadiazin‐6‐onen (4,5‐Diaza‐α‐pyronen), 13[1]. Diels‐Alder‐Reaktionen mit 6H‐1,3,4‐Oxadiazin‐6‐onen als Dienophil
Authors: Feineis Erich , Schwarz Harmut , Hegmann Joachim , Christl Manfred , Peters Eva‐Maria , Peters Karl , Schnering Hans Georg Von 
Published: July 2007

Cycloadditions of 6H‐1,3,4‐Oxadiazin‐6‐ones (4,5‐Diaza‐α‐pyrones), 13[1].–Diels‐Alder Reactions with 6H‐1,3,4‐Oxadiazin‐6‐ones as Dienophile2,5‐Diphenyl‐1,3,4‐oxadiazin‐6‐one (1b) reacted as dienophile with 2,3‐dimethyl‐1,3‐butadiene to afford the pyridooxadiazinone 5. Analogously, the oxadiazinoisoquinolines 7c– e were formed on treatment of 2‐(4‐nitrophenyl)‐ (1c), 2‐(4‐tolyl)‐ (1d), and 2‐(4‐bromophenyl)‐5‐phenyloxadiazinone (1e) with 1,2‐bis(methylene)cyclohexane (6). In contrast, the methyl oxophenyloxadiazinecarboxylate 1a gave a low yield of the cyclopentenone derivative 8 and 7a in the ratio 2.3:1.0. A third type of product, i.e. the cyclobutanone derivative 9, resulted on exposure of the anisyl(isopropyl)oxadiazinone 1f to 6. The oxadiazinones 1d, e, f have been prepared for the first time. X‐ray structure analyses established the identity of the compounds 7d and 9.
Free‐Radical Coupling of Alkyl and Aryl Halides with Electron‐Deficient Alkenes Mediated by Chromium(II) Complexes[1]
Authors: Tashtoush Hasan I. , Sustmann Reiner 
Published: July 2007

AbstractFree radicals generated from organic halides and (ethylenediamine)chromium(II) complexes in DMF are trapped by electron‐deficient olefins. The coupling reactions of alkyl halides, described in Part I[1], are extended and, in addition, aryl halides are shown to be efficient radical precursors to yield coupling products in good yield.
Darstellung und Kristallstrukturen einiger intramolekularer Donator‐Akzeptor‐Komplexe mit der Phosphorylgruppe als Donator
Authors: Well Michael , Fischer Axel , Jones Peter G. , Schmutzler Reinhard 
Published: July 2007

Preparation and Structures of Some Intramolecular Donor‐Acceptor Complexes with the Phosphoryl Group as DonorThe reaction of [2,2‐diphenyl‐1‐(trimethylsiloxy)ethenyl]‐dimethylphosphane oxide (1) with PF5 yields 2, involving hexacoordinated phosphorus, by cleavage of the Si–O bond and elimination of (CH3)3SiF. The same compound was formed in the reaction of 1 with RPF4 (R = dimethylamino, morpholino) by cleavage of the P–N bond and elimination of the corresponding silylated amine, R2NSiMe3. The reaction of 1 with F3B · OEt2 led to the intramolecular donor‐acceptor‐complex 3 with a tetracoordinated boron atom. The complex 4 with penta‐ (or hexa)coordinated tin was prepared by reaction of 1 with tin(IV) chloride with elimination of (CH3)3SiCl. X‐ray structure analyses of 2 and 3 confirm the donor‐acceptor interaction between the oxygen atom of the PO group and the PF4 or BF2 group.
Structures, Dynamics, and Reactivity of Tripodal Amido Ligands Coordinated to TiIV Centres
Authors: Friedrich Stefan , Gade Lutz H. , Edwards Andrew J. , McPartlin Mary 
Published: July 2007

AbstractA new class of amido titanium(IV) halides containing tripodal ligands H3CC(CH2NR)3TiX (R = Me, X = Cl: 1; R = Me3Si, X = Cl: 2a, Br: 2b; R = SiMe2tBu, X = Cl: 3a, Br: 3b) has been synthesised. Compound 1 has been structurally characterised by X‐ray crystallography and found to be dimeric in the crystal displaying an idealised C2 symmetry with bridging amido functions linking the two halves of the molecule. The dimeric structure is retained in solution as has been shown by 1H‐ and 13C‐NMR spectroscopy which has also revealed a high degree of ligand dynamics, effecting the interconversion of the two enantiomeric forms of the molecule. This process has been investigated by variable temperature NMR studies and phase‐sensitive 1H‐NOESY/EXSY spectra. The dimeric μ‐imido complexes [H3CC(CH2NSiMe3)2 (H)CH2NTiX]2 (X = Cl: 4a, Br: 4b) have been isolated as a byproduct in the synthesis of 2a/b, and a single‐crystal X‐ray structure analysis of 4a has established its molecular structure.
Ozonide von acyclischen Olefinen mit mono‐ und dichlorsubstituierten Doppelbindungen
Authors: Griesbaum Karl , Schlindwein Konrad , Hilβ Michael 
Published: July 2007

Ozonides of Acyclic Olefins Having Mono‐ and Dichloro‐Substituted Double BondsOzonolyses of acyclic olefins containing 1,2‐dichloro‐substituted (4a, b) and monochloro‐substituted double bonds (7a, b, 12) as well as two (4a, b, 7a, b) or one halomethyl group (12) attached to the double bond afford the corresponding ozonides as the first representatives of monocyclic chlorinated ozonides. Their stability decreases in the order 5a, 5b 8a, 8b 13.
A Stepwise [4 + 3] Cycloaddition Reaction of the 1,3‐Diphenyl‐2‐azaallyl Anion
Authors: Mayr Herbert , Heigl Ulrich W. , Baran Janusz 
Published: July 2007

AbstractThe 1,3‐diphenyl‐2‐azaallyl anion (1) undergoes [3 + 2] cycloaddition reactions with the s‐cis‐fixed 1,3‐dienes 8–11. In contrast, 1,1,2,2,3,3‐hexamethyl‐4,5‐bis(methylene)cyclopentane (7) reacts with 1 to give the [4 + 3] cycloadduct 13 and the linear 1,4‐addition product 14. This reaction is four orders of magnitude slower than the corresponding reaction of 1 with 1,2‐bis(methylene)cyclopentane (8), which exclusively yields [3 + 2] cycloadducts. A change of mechanism – concerted cycloaddition of 8 and stepwise cycloaddition of 7 – is suggested, but not unequivocally proven. It is concluded that reactions of 1 with ordinary dienes cannot profit from concertedness by more than 5 kcal · mol–1.
Phosphorus‐centered gold clusters: A novel pentanuclear species {[(Ph3P)6Au5]P}2+
Authors: Beruda Holger , Zeller Edgar , Schmidbaur Hubert 
Published: July 2007

AbstractThe reaction of tris[(triphenylphosphane)gold]oxonium tetrafluoroborate with phosphane gas in tetrahydrofuran leads to a mixture of products, one of which has now been isolated and identified as the complex {[(Ph3P)6Au5]P}2+ (BF4—)2 (1). This cluster can be described as an adduct of [(Ph3PAu)4P]+ and [(Ph3P)2Au]+. Crystals of (1)2 (CH2Cl2)3 Et2O contain two crystallographically independent formula units of very similar structure. The dications are centered by pentacoordinate phosphorus atoms in an irregular coordination geometry. In the crystal one of the five gold atoms is attached to two triphenylphosphane ligands, while the other four bear only one such ligand. In solution rapid ligand exchange renders the ligands equivalent on the NMR time scale. This stoichiometry and structure of 1 are indicative of the strong basicity of the [(Ph3PAu)4P]+ cation probably owing to its square‐pyramidal structure with strong Auä bonding, as suggested by the structure of its arsenic analogue.
Halogen—Kohlenstoff—Schwefel‐Verbindungen: Synthesen mit 2‐Methylthio‐4,5‐bis(trifluormethyl)‐1,3‐dithiolium‐trifluormethansulfonat
Authors: Mono Susanne , Pritzkow Hans , Sundermeyer Wolfgang 
Published: July 2007

Halogen—Carbon—Sulfur Compounds: Syntheses with 2‐Methylthio‐4,5‐bis(trifluoromethyl)‐1,3‐dithiolium TrifluoromethanesulfonateBy reactions of the strongly electrophilic 2‐methylthio‐4,5‐bis‐(trifluoromethyl)‐1,3‐dithiol‐2‐ylium trifluoromethanesulfonate (6) with nucleophiles like secondary amines, phenoles and active methylene compounds the new 2‐amino‐1,3‐dithiolium salts11 a—eand 1,3‐dithiol‐2‐ylidene compounds5–10, 12were obtained. The 1,3‐dithiolium salts14were prepared in two different ways. Reaction with PPh3yields the phosphonium salt16, from which the ethylidene compound20was obtained via the intermediate phosphorane18. The crystal structures of7, 16and of the fulvalene19were determined.
On the mechanism of the benzophenone‐sensitized photolysis of 2,3‐diazabicyclo[2.2.1]hept‐2‐ene in the laser jet: Evidence for intermolecular triplet diradical reactions
Authors: Adam Waldemar , Finzel Ralf , Walther Barbara 
Published: July 2007

AbstractThe benzophenone‐sensitized laser jet photolysis of 2,3‐diazabicyclo[2.2.1]hept‐2‐ene (1) affords, besides the previously reported cyclopentene and housane (2), also cyclopentane, cyclopentadiene, and the dimers bicyclopent‐2‐en‐1‐yl (7), 3‐cyclopentylcyclopent‐1‐ene (8), and 1,1'‐bicyclopentyl (9). As a model reaction, the pyrolysis of dimer 8 at 600°C/20 Torr leads to the other dimers 7 and 9 together with cyclopentadiene, cyclopentene, and traces of cyclopentane. Control experiments showed that H abstraction by the cyclopentane‐1,3‐diyldiracidal (3) from cyclohexene (as model substrate for cyclopentene) and addition to housane (2) with formation of diradical 6 are unlikely pathways. Instead, the product data available can be best explained in terms of an intermolecular disproportionation of two diradicals 3 to give the cyclopent‐2‐en‐1‐yl (4) and cyclopentyl (5) radical pair, which is subsequently converted to the observed products by in‐cage and out‐of‐cage coupling and H transfer reactions. Such intermolecular diradical chemistry becomes feasible due to the high steady‐state concentrations (ca, micromolar) generated in the laser jet. Two‐photon processes take place, but are of subordinate importance.
Synthese, Reaktivität und Komplexeigenschaften von nido‐2,3,5‐Tricarbahexaboranen
Authors: Feßenbecker Achim , Hergel Achim , Hettrich Ralph , Schäfer Volker , Siebert Walter 
Published: July 2007

Syntheses, Reactivity and Complexation Properties of nido‐2,3,5‐TricarbahexaboranesBy double hydroboration of 1,3‐dihydro‐1,3‐diborafulvenes 2 or 4,5‐diisopropylidene‐1,3‐diborolanes 3 with (Et2BH)2 and subsequent loss of triethylborane derivatives 1 of 2,3,5‐tricarbahexaborane are formed under mild conditions. The stability of the nido‐carboranes 1 depends on the substituents in the basal positions. After deprotonation, the tricarbahexaboranate ion (1 — H)— functions as a cyclopentadienyl analogue (C5H5)—, and its reaction with allylnickel bromide dimer gives the allylnickel complexes 8a, b. Reaction of octacarbonyl dicobalt with 1b yields the dicarbonylcobalt complex 10b. Treatment of 1e with [(C5H5)Ni(CO)]2 results in the formation of the di‐nuclear carbonyl‐bridged complex 12e.
On the α,α'‐Oxidative Coupling of β‐Alkoxy‐Substituted 2‐Pyrrolecarboxylates
Authors: Ribó Josep M. , Acero Carles , Claret Josep 
Published: July 2007

AbstractThe electrochemical and chemical oxidative α,α'‐coupling of 3‐methoxy‐4‐methyl‐2‐pyrrolecarboxylic acid (2) and its ethyl ester 4 is compared with that of the corresponding 4‐methoxy‐2‐pyrrolecarboxylates (1 and 3 respectively). The β‐alkoxy substituent exerts a strong directing influence on its vicinal α‐position, which in the case of compounds 2 and 4 determines the 2,5'‐coupling and allows the isolation of the corresponding 1H,2'H‐2,2'‐bipyrrole 6 in the case of 4. For 2 the polypyrrole can be obtained by exhaustive electrochemical or chemical coupling, whereas in the case of 1 only the corresponding tetramers are formed. The structures of these tetrapyrroles, already described in the literature, here obtained by oxidation of 4‐alkoxy‐2‐pyrrolecarboxylic acid (1), have been reexamined: they are mixtures of tetramers with zwitterionic structure, have at least two substitution patterns and are partially oxidized to the corresponding bipyrrolylidenes.
Synthesis of μ‐Cyano(2,3‐naphthalocyaninato)iron(III) and Comparison to μ‐Cyano(phthalocyaninato)iron(III)
Authors: Ziener Ulrich , Fahmy Naglaa , Hanack Michael 
Published: July 2007

AbstractPotassium dicyano(2,3‐naphthalocyaninato)ferrate(III), K[2,3‐NcFe(CN)2] (2), reacts in water with elimination of KCN to form μ‐cyano(2,3‐naphthalocyaninato)iron(III), [2,3‐NcFe(CN)]n (4a). Dichloro(2,3‐naphthalocyaninato)iron(III), 2,3‐NcFeCl2 (3), reacts with KCN to yield also [2,3‐NcFe(CN)]n (4b). Both compounds 4a and 4b show similar IR spectra with a typical blue‐shifted CN valence frequency caused by a bridging function of CN‐. Compounds 4a and 4b also show almost identical 57Fe‐Mössbauer spectra which, however, might be interpreted with a Fe(+II) oxidation state of the iron. The measured magnetic moment of 4 however clearly proves the expected oxidation state +III of the iron in [2,3‐NcFe(CN)]n (4). Compounds 4a and 4b both exhibit good semiconducting properties (σRT ∼ 10–3 S/cm) without additional external oxidative doping. The property is quite similar to that of the known μ‐cyano(phthalocyaninato)iron [PcFe(CN)]n (σRT ∼ 10‐2 S/cm).