bluuebunny/crossref_metadata_2025 huggingface dataset:
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 Phosphorus

Substitution 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.
Quantum‐Mechanical ab initio Investigation of the Transition‐Metal Compounds OsO4, OsO3F2, OsO2F4, OsOF6, and OsF8
Authors: Veldkamp Achim , Frenking Gernot
Published: July 2007

The equilibrium geometries of OsO4, OsO3F2, OsO2F4and OsF8are theoretically predicted by using quantum‐mechanical ab initio methods at the Hartree‐Fock and MP2 level of theory employing quasi‐relativistic pseudopotentials for Os and 3‐21G and 6‐31G(d) basis sets for O and F. A comparison of the calculated geometries and vibrational frequencies with available experimental results shows a good agreement. The energy minimum structure for OsO4hasTdsymmetry, for OsO3F2it hasD3hsymmetry, for OsO2F4C2vsymmetry withcis1‐coordinated oxygen atoms, and for OsF8aD2dsymmetry with two different Os – F bond lengths is predicted. OsOF6is not a minimum on the potential energy hypersurface. The calculation of the thermodynamic stabilities indicates that the Os – F bond in OsF8is clearly weaker than in OsO3F2, OsO2F4and in OsF6. It will be very difficult to observe OsF8experimentally. The analysis of the electronic structure shows that the Os – O bond is partly covalent, while the Os – F bonds are mainly ionic.
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 Osmium

The 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 Spacer

The 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 Dienophile

2,5‐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

Free 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 Donor

The 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

A 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 Bonds

Ozonolyses 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

The 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

The 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 Trifluoromethanesulfonate

By 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

The 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‐Tricarbahexaboranes

By 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

The 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

Potassium 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).
Metal Complexes with Tetrapyrrole Ligands, LXV[1]. Generation and ESR Spectra of the Cation Radicals of Bis(octaethylporphyrinato)zirconium(IV) and Bis(chelate)(octaethylporphyrinato)zirconium(IV) Complexes
Authors: Buchler Johann W. , Eberle Mike , Hammerschmitt Peter , Hüttermann Jürgen , Kappl Reinhard
Published: July 2007

Electron spin resonance spectra of the cation radicals A+ and B+ generated from a zirconium(IV) monoporphyrin, bis(acetato)(octaethylporphyrinato)zirconium(IV), Zr(OEP)(OAc)2 (A), and bis(octaethylporphyrinato)zirconium(IV), Zr(OEP)2 (B), respectively, have been measured at 293 and 77 K. [Zr(OEP*)(OAc)2]Br (A+ Br–) has been prepared in situ by oxidation of A with bromine, [Zr(OEP√/2)2]PF6 (B+ PF6–) by electrochemical oxidation of B. ESR parameters at 293 K are as follows: A+ Br–: g = 2.0025, ΔHpp = 0.57 mT; B+ PF6–: g = 2.0024, ΔHpp = 0.39 mT. The ratio of the line widths ΔHpp(A+) and ΔHpp(B+) of the ESR signals of A+ and B+ is 1.46 at room temperature, i. e. very close to the value of √2 expected for a defect electron completely delocalized between the two porphyrin π electron systems in [Zr(OEP*/2)2]+. The ESR signal of A+Br– persists on cooling to 77 K excluding any kind of π‐π dimer formation. Treatment of (octaethylporphyrinato)bis(2,4‐pentanedionato)zirconium(IV), Zr(OEP)(acac)2, with bromine yields bis(3‐bromo‐2,4‐pentanedionato)(octaethylporphyrinato)zirconium(IV), Zr(OEP)(Bracac)2.
Ephedrine‐Derived Imidazolidin‐2‐ones. Broad Utility Chiral Auxiliaries in Asymmetric Synthesis
Authors: Drewes Siegfried E. , Malissar Dean G. S. , Roos Gregory H. P.
Published: July 2007

The scope of the readily available (4R,5S)‐1,5‐dimethyl‐4‐phenylimidazolidin‐2‐one (4) and its 4‐cyclohexyl analogue 6 as practical, efficient chiral auxiliaries has been demonstrated. The enolate chemistry of their N‐acyl derivatives exhibits features which recommend their use in asymmetric synthesis. The stereoselective boron‐mediated aldol as well as alkylation and acylation results are presented. The steric control benefit derived by conversion of phenyl to cyclohexyl is highlighted.
Nb4Te17I4, a New Pseudo One‐Dimensional Solid‐State Polytelluride
Authors: Tremel Wolfgang
Published: July 2007

The new ternary compound Nb4Te17I4 has been prepared and structurally characterized. It crystallizes in the monoclinic system, space group C2/c with unit‐cell parameters a = 16.199(4), b = 8.128(2), c = 27.355(6) Å, β = 110.84(2)°, Z = 4. The structure consists of infinite one‐dimensional niobium/tellurium chains running parallel to the crystallographic c direction. The chains are separated by iodine atoms. Short and long metal–metal distances alternate in the sequence of three consecutive short bonds ([d ≈ 3.1 – 3.2 Å) and one long (d = 4.268 Å) metal–metal separation. Each Nb atom is eight‐coordinate. The composition of the chain is ∞11[(Nb5+)2(Nb4+)2(Te22−)4(Te32−)3(I−)4].
Zur Bildung eines Fe2(CO)6‐Komplexes mit (Boryloxy)allyl‐Brücke
Authors: Braunschweig Holger , Spaniol Thomas P. , Paetzold Peter
Published: July 2007

On the Formation of a Fe2(CO)6 Complex with a (Boryloxy)allyl Bridge

The amino(imino)borane Me3Si(tBu)NBNtBu (1) reacts with (benzylideneacetone)tricarbonyliron (2) in 1:2 molar ratio to give a 50% yield of the hexacarbonyldiiron complex 3 with a fly‐over (boryloxy)allyl bridge, which crystallizes in the space group P21/c. The structure of 3 can be described as a pyramid with Fe(CO)3 at the apex and a non‐planar pentagon [‐Fe(CO)3‐O(BXX′)‐C(Me)‐CH‐C(Ph)‐] [X = NHtBu, X′ = N(SiMe3)tBu] as the basis, but there is no bond between the apex and the O atom.
Reaktion von Decaboran mit dem Phosphaalkin PCtBu
Authors: Meyer Franc , Pactzold Peter , Englert Ulli
Published: July 2007

Reaction of Decaborane with the Phosphaalkyne PC tBu

The borane B10H12(SMe2)2 (1) reacts with the phosphaalkyne P°CtBu to form the product [B10H11(SMe2)][C(tBu)‐PH](B10H12) (2), in which two B10 units are linked by a HP‐CtBu bridge. The B10 unit B is simply bound to the bridge C atom, whereas the B10 unit A is bound to both bridging atoms, P and C, by atom B6 and, moreover, to the P atom by atom B5. The solvate complex 2 · CH2Cl2 crystallizes in the space group P¯.
Darstellung geeigneter Vorstufen zur Synthese von 16,16,16,17,17,17‐Hexafluorretinalen
Authors: Abele Herbert , Haas Alois , Lieb Max , Zwingenberger Jorg
Published: July 2007

Preparation of Suitable Precursors for the Synthesis of 16,16,16,17,17,17‐Hexafluororetinals

Cycloaddition reactions of (CF3)2C = CHCHO with butadiene or 1,3‐pentadiene provide the corresponding cyclohexane derivatives 2, 3 and 4. Condensation of 3 with (C2H5O)2P‐(O)CH2C(O)CH3 or of 2 with acetone in the presence of bases yields 5 and 7. While 5 reacts with CH2 = CHMgBr to give 6, treatment of 7 with diluted HCI provides 8. Compounds 7 and 8 proved to be not suitable as starting materials for the preparation of 16,16,16,17,17,17‐hexafluororetinals. A better synthon is the diene 11. This is obtained in a threestep reaction starting from hexafluoroacetone and (C6H5)3PCHC(O)CH3 to give 9 which on treatment with CH3MgI provides 10. Dehydration of 10 with 50% H2SO4 forms 11. In this reaction sequence byproduct 12 is formed presumably by addition of CF3C(O)CF3 to 9. At elevated temperatures under pressure 11 adds ethylene to form 13. Functionalization of 13 in 2‐position is achieved by hydroboration/oxidation yielding 14 which is oxidized with pyridinium dichromate to 15. Oxidation and bromination reaction of 13 are described.
Stereoselektive Protonierung von Carbanionen, 2. Diastereoselektive Protonierung von Schöllkopf‐Bislactimether‐Anionen
Authors: Hünig Siegfried , Klaunzer Norman , Wenner Hermann
Published: July 2007

Stereoselective Protonation of Carbanions, 2[1]. — Diastereoselective Protonation of Schöllkopf's Bislactim Ether Anions

The anions of the bis‐lactim ethers 5–7 serve as models for a systematic investigation of diastereoselective protonation. From 5Li, 6Li, and 7Li in THF at −78°C 30 proton sources (OH, NH, SH, CH) of different acidity and bulkiness produce the following cis/trans ratios: 5 8:92 → 37:63; 6 15:85 → 48:52; 7 25:75 → 59:41 (equilibria ≈ 50:50). Substitution of R1 = iPr in 5 by Me (→ 6) decreases the stereoselectivity slightly, but substitution of OMe in 6 by OEt (7) much stronger (Table 1). Most of the added Lewis acids show week or even leveling effects, whereas with 5K a dramatic change is observed with cis/trans‐5 = 27:73 → 89:11 (Table 2). By variation of solvent and several additives only minor effects on the cis/trans ratio are observed (Table 3). Backed by 13CNMR spectra of the ion pairs and literature data protonation of 5Li‐7Li is supposed to occur on a dimer, which will mainly react to give trans‐5–7. The prevailing formation of cis‐5 from 5K is explained by the reaction of the monomeric ion aggregat.
Relative Reactivities of Acetals and Ethers under Friedel‐Crafts Conditions
Authors: Mayr Herbert , Dau‐Schmidt Jan‐Peter
Published: July 2007

Competition experiments have been performed to determine the relative reactivities of acetals and ethers toward allyltrimethylsilane in the presence of catalytic amounts of BF3 OEt2. It is found that acetals R‐CH(OMe)2 and their phenylogous p‐anisyl ethers R‐CH(p‐MeOC6H4)(OMe) show very little differences in reactivity. The reactivity scales are employed to rationalize the results of Lewis acid‐catalyzed additions of acetals and ethers to CC double bonds.
Radikalische Cyclisierung von Dienen, VIII. Über die regioselektive Herstellung von ungesättigten Cyclopenta[b]furan‐2‐onen aus (S)‐(+)‐Carvon — Bausteine zur Synthese von enantiomerenreinen Triquinanen
Authors: Weinges Klaus , Reichert Hans , Braun Ralf
Published: July 2007

Radical‐Type Cyclization of Dienes, VIII[1]. — On the Regioselective Synthesis of Unsaturated Cyclopenta[b]furan‐2‐ones from (S)‐(+)‐Carvone — Building Blocks for the Synthesis of Enantiomerically Pure Triquinanes

The diastereomeric products 2a and 2b, which were synthesized from (S)‐(+)‐carvone (1), are converted to (3aS,5S,6aS)‐(‐)‐5‐acetoxyhexahydro‐6a‐methyl‐2H‐cyclopenta[b]furan‐2‐one (4) in ca. 50% yield. 4 is regioselectively converted to (3aR,6aS)‐(‐)‐3,3a,6,6a‐tetrahydro‐6a‐methyl‐ (8a) and (3aS,6aR)‐(+)‐3,3a,4,6a‐tetrahydro‐6a‐methyl‐2H‐cyclopenta[b]‐furan‐2‐one (8b). These are used at the 10‐g scale for the synthesis of enantiomerically pure triquinanes.
Bimolecular Formation of Radicals by H‐Transfer, 6. Uncatalyzed Transfer Hydrogenation of a Benzhydryl Fluoride by 9,10‐Dihydroanthracene
Authors: Schaffer Frank , Beckhaus Hans‐Dieter , Rieger Hans‐Jürgen , Rüchard Christoph
Published: July 2007

1‐Adamantylfluorodiphenylmethane (2) was reduced to 1‐adamantyldiphenylmethane (3) when heated with 9,10‐dihydroanthracene to 330°C. From the second‐order kinetics, the activation parameters (ΔH‡ = 37.2 ± 0.5 kcal mol−1, ΔS‡ = −18.8 ± 0.8 cal mol−1 K−1), the kinetic isotope effect kH/kD = 2.4 (373°C)[17], and the observation of intermediate radical species by ESR it was concluded that the reaction is a new example of a molecule‐induced radical formation (MIRF) process. This is supported by thermochemical data.
Synthesis and Crystal Structures of Copper(I) and Gold(I) Complexes [C(NH2)3]2[M2(1,2–dithiosquarate)2], M = Cu, Au, Containing Short M···M Distances, and of the Gold(III) Complex (cycloPrPh3P)[Au(1,2‐dithiosquarate)2]
Authors: Kleinitz Ulf , Mattes Rainer
Published: July 2007

The new compounds [C(NH2)3]2[Cu2(dtsq)2] (1), [C(NH2)3]2‐[Au2(dtsq)2] · H2O (2), and (cycloPrPh3P)[Au(dtsq)2] (3, cycloPr = cyclopropyl) have been prepared from CuSO4 · 5 H2O, KAuCl4, and K2dtsq · H2O (dtsq = dianion of 1,2‐dithiosquaric acid, C4O2S2−2). Compounds 1 and 2 contain pairs of metal atoms with short intermetallic distances of 2.587(2) (Cu···Cu) and 2.846(2) Å (Au···Au). Cu(I) is trigonally coordinated to three sulfur atoms of three different ligands and lies 0.51 Å above the S3 plane. It is oriented towards the copper atom of a second CuS3 unit related to the first one by a center of inversion. Au(I) shows a linear coordination, leading to the formation of Au2(dtsq)2−2 dimers. These have intermolecular Au···Au distances of 3.259(2) Å. Compound 3 contains isolated Au(dtsq)−2 ions with square planar coordination geometry stacked along the a axis at 4.708 Å distance.
Komplexe von Metallen der dritten Hauptgruppe mit [(en)2MIII(OH)2]‐Liganden (M = Cr, Co)
Authors: Rominger Frank , Müller Annette , Thewalt Ulf
Published: July 2007

Complexes of Third Group Elements with [(en)2MIII(OH)2] Ligands (M = Cr, Co)

Heteronuclear complexes are formed on reaction of cis‐[(en)2‐MIII(OH)(H2O)]2+ (M = Cr, Co; en = ethylenediamine) with A1III, GaIII, InIII, and T1III in aqueous solution. The following salts with tetranuclear cations have been isolated: [A1{(OH)2‐Cr(en)2}3](S2O6)3 · 13 H2O (1), [A1{(OH)2Co(en)2}3](S2O6)3 · 5 H2O (2), [Ga{(OH)2Co(en)2}3](S2O6)3 · 5 H2O (3), [In{(OH)2‐Cr(en)2}3](S2O6)3 · 6 H2O (5), and [In{(OH)2Co(en)2}3]‐(ClO4)4Cl2 · 4 H2O (6). Furthermore, the dinuclear neutral complexes [InCl4{(OH)2Cr(en)2}] (4) and [TlCl4{(OH)2‐Cr(en)2}] · 0.5 H2O (7) are prepared. X‐ray analyses confirm that in all cases the [(en)2MIII(OH)2] groups act as bidentate ligands in the hydroxo‐bridged heterometallic complexes.
Flüchtige Metallalkoxide nach dem Konzept der donorfunktionalisierten Liganden
Authors: Herrmann Wolfgang A. , Huber Norbert W.
Published: July 2007

Volatile Metal Alkoxides According to the Concept of Donor‐Functionalized Ligands

Homoleptic metal(II) alkoxides 3–5 of manganese, iron, cobalt, and zinc are prepared by applying the concept of donor‐functionalized ligands. The trifunctional ether ligands 1 thus form volatile metal alkoxides that sublime below 100°C at 10−2 mbar. Monomeric molecules are present in the gas phase and are likely to occur in the solid state, too. The heterodimetallic alkoxide 6 (Li/Co) sublimes without decomposition.
Synthese und Reaktionen der ersten zweifach überbrückten Fiscellane
Authors: Düll Bernhard , Müllen Klaus
Published: July 2007

Synthesis and Reactions of the First Doubly‐Bridged Fiscellanes

The synthesis of the novel hexacycle 2 containing a fiscellane framework is described. Starting from Weiss' tetraester 6, the fiscellane 2 is build up in six steps by successive chemical transformation of the methoxycarbonyl functions using SEM protecting groups. The behaviour of the novel diol 2 towards introduction of several leaving groups is examined. Upon treatment with methanesulfonyl chloride the highly strained hexacycle 2 undergoes a skeletal rearrangement with formation of the triene 4. Instead of reacting to a doubly‐bridged semibullvalene 3, the diol 2 gives rise to a new heterocyclic π perimeter 5 when the trifluoroacetyl derivative 12 is treated with sodium iodide in acetone.
Cyclische isomere vier‐ und fünfgliedrige heterodinucleare Fischer‐Carbenkomplexe — gebildet aus einem Vinylidentitanocen‐Fragment und Metallcarbonylen
Authors: Beckhaus Rüdiger , Oster Jürgen , Wagner Trixie
Published: July 2007

Cyclic Isomeric Four‐ and Five‐Membered Heterodinculear Carbene Complexes — Formed from a Titanocene Vinylidene Fragment and Metal Carbonyls

The four‐membered heterodimetallic carbene complexes Cp*2 16 [LnM: Cr(CO)5 (a), Mo(CO)5 (b), W(CO)5 (c), CpRe(CO)2 (f), Mn2(CO)9(g), Re2(CO)9 (h), Fe(CO)4 (i), Rh(acac)(CO) (i)] are easily prepared by trapping the vinylidenetitanocene [Cp*2TiCCH2] fragment 6 with the corresponding metal carbonyls. The vinylidenetitanocene 6 is generated in a favourable manner from Cp*2Ti(CH3)CHCH2 (13) or Cp * (Fv)TiCH = CH2 (14) [Fv: C5(CH3)4CH2] by a 1,3‐H shift (α elimination) at room temperature. The formation of 16 is characterized by a preferred suprafacial [2 + 2] cycloaddition. Starting from Cp*2 (5) or 14 and transition metal carbonyls unexpected isomeric five‐membered titanacycles Cp*2 8 [MLn = a–c, MnCp(CO)2 (d), MnCp′(CO)2 (e), f–i] are obtained at higher temperatures (70–100°C). These oxatitanacyclopentenes 8 are formed also upon heating via the kinetic product 16 with high yield, as a result of a 1,2‐hydrogen shift, proved for c, g, h. From the spectroscopic data an η1‐vinylcarbene structure is deduced, exhibiting a cis‐ (16) or trans‐configurated (8) LnMCCC sequence. An X‐ray structure analysis shows the importance of the acyl resonance form in 8a, typically observed for such heterodimetallic carbene complexes. The reversible liberation of the metal carbonyl is a remarkable property of complexes 16 in solution, whereas the thermodynamic product 8 shows the typical properties of Fischer carbene complexes.
Stereoselectivity of the Transfer of Hydrogen Atoms to Cyclic Alkyl Radicals
Authors: Metzger Jürgen O. , Schwarzkopf Kay , Saak Wolfgang , Pohl Siegfried
Published: July 2007

The addition of cyclohexane to alkylmaleic anhydrides 1a‐f via cyclic radicals 2a‐f gave a mixture of (Z)‐ and (E)‐2,3‐dialkylsuccinic anhydrides 3a‐f. The stereoselectivity of the hydrogen transfer from cyclohexane to radicals 2a‐d was measured in the temperature range of 200‐260°C, and the relative activation parameters of the formation of (Z)‐ and (E)‐3 were determined. The stereoselectivity of the hydrogen transfer from cyclohexylmercuric hydride at 25°C was measured as well. The results are rationalized assuming steric interactions in the transition state of H donor and β substituent and of α and β substituent, respectively. An X‐ray structure analysis of the highly strained addition product (Z)‐3d was performed.
Transanular Interactions in Difunctional Medium Rings, 5. Spectroscopic Investigations of Bicyclic Boraamines
Authors: Wiesmann Reinhard F. , Rademacher Paul
Published: July 2007

The endo‐7‐[(dialkylamino)methyl]‐3‐borabicyclo[3.3.1]nonanes 1 and 2 have been synthesized and their intramolecular complex formation of the corresponding 2‐azonia‐1‐boratatricyclo[4.3.1.14,8]undecanes 3 and 4 has been studied in the gas phase by UV photoelectron spectroscopy and in solution by 11‐NMR spectroscopy. Deviations of the characteristic spectral features from those of the monofunctional bicyclic boranes 5 and amines 6 and 7 indicate that in the gas phase the (dimethylamino)boranes with a B‐alkyl substituent adopt the tricyclic form 3a–c whereas the diethylamino and the B‐methoxy derivatives 1e and 2 prefer the bicyclic structure. In solution some deviations from this behavior are observed.
Ein einfacher Weg zu Silicium in oktaedrischer Sauerstoffkoordination
Authors: Königstein Karsten , Jansen Martin
Published: July 2007

A Simple Route to Silicon in Octahedral Oxygen Coordination

Syntheses and crystal structures of three new compounds Rb2SiP4O13 (1), Cs2H2Si(P2O7)2 (2), and BaH2Si(P2O7)2 (3) containing silicon in an octahedral oxygen coordination are reported. The structures have been determined by X‐ray structure analyses. All three compounds are constituted of silicophosphate polyanions. The NMR chemical shifts of silicon and hydrogen are measured.
Zinkkomplexe von Aminosäuren und Peptiden, 3. Zinkkomplexe von Peptiden mit N‐terminalem Cystein
Authors: Albrich Hans , Vahrenkamp Heinrich
Published: July 2007

Zinc Complexes of Amino Acids and Peptides, 3[1]. ‐ Zinc Complexes of Peptides with N‐terminal Cysteine

Conventional methods were used to prepare three dipeptides Cys‐X‐OR (X = Gly, Phe), nine dipeptides Cys‐X‐NH2 (X = Gly, Ala, Val, Leu, Ile, Pro, Phe, Met, Ser), three tripeptides Cys‐X‐OR (X = Gly‐Gly, Phe‐Phe, Met‐Phe), and three tripeptides Cys‐X‐NH2 (X = Gly‐Gly, Gly‐Ala, Gly‐Leu). All these peptides have the unprotected amino acid cysteine at the N terminus. Their reactions with basic zinc carbonate resulted in the formation of mononuclear complexes ZnL2, with L being the peptide anion resulting from SH deprotonation, IR and NMR spectra indicate that in all these complexes the zinc ion is coordinated by the cysteine thiolate and amino functions of two peptide ligands. This tetrahedral ZnN2S2 coordination by two chelating peptides is confirmed by a crystal structure determination of the complex Zn(Cys‐Gly‐NH2)2.
Selected Transformations of 6‐Cyclopropylidene‐5‐oxaspiro[2.3]hexan‐4‐one, a Highly Strained Tricyclic β‐Lactone
Authors: Wulferding Andreas , Jankowski JöRg H. , Hoffmann H. Martin R.
Published: July 2007

The title lactone 2 acylates a variety of amines including phenylalanine, sterically hindered alcohols, and phenols. With activated non‐enolizable carbonyl compounds, bis‐spiro 6‐membered β‐keto lactones are formed. Oxidative rearrangement of 2 affords bis‐spiro lactones 12 and 13.
Chiral Organometallic Reagents, XI. Stereoselective Exchange of Diastereotopic Iodine Atoms by Magnesium in 3‐Alkoxy‐1,1‐diiodoalkanes
Authors: Hoffmann Reinbard W. , Kusche Andreas
Published: July 2007

α‐Iodoalkylmagnesium species were generated by reaction of 3‐oxygenated 1,1‐diiodoalkanes with isopropylmagnesium halides at −78%C. The resulting magnesium carbenoids were found to be configurationally stable at temperatures up to −20%C and were trapped by benzaldehyde or allyl iodide at low temperatures. Stereoselectivity on exchange of the diastereotopic iodine atoms in 3 was found to be low.
Stereoselective Synthesis of Alcohols, XLVI. Synthesis of a Hydroxytrioxaadamantane, a Model for the Trioxaadamantane Moiety of Muamvatin
Authors: Hoffmann Reinhard W. , Dahmann Georg
Published: July 2007

A protected hydroxy triketone 22 has been generated by direct Swern oxidation of a δ‐trimethylsilyloxy alcohol 11, avoiding the formation of a δ‐hydroxy ketone as an intermediate. Conditions have been worked out, which allow the deprotection of a tert‐butyldimethylsilyl group and the spontaneous tricyclization of the resulting hydroxy triketone 4 to an acid‐sensitive hydroxytrioxaadamantane 5.
Borylation of a Stable Primary Enamine
Authors: Erker Gerhard , Wingbermühle Doris , Grehl Matthias , Fröhlich Roland
Published: July 2007

The stable conjugated primary enamine 1,6‐diamino‐1,6‐diphenyl‐1,3,5‐hexatriene (2a) was treated with 9‐borabicyclo‐[3.3.1]nonane. At 40°C in dichloromethane solution (18 h) only borylation at nitrogen was observed. With loss of dihydrogen a 9‐BBN substituent became attached to each enamine nitrogen. The N,N′‐diborylated diaminohexatriene product 3 was characterized by X‐ray diffraction.
Preparation, Properties, and Reactions of Metal‐Containing Hetercycles, XC. Reactivity of Differently Activated Alkynes toward Ruthenium and Osmium Complexes of the Type (η2‐C2H4)M(CO)4
Authors: Lindner Ekkehard , Kühbauch Hartwig , Mayer Hermann A.
Published: July 2007

Depending on the substituents, the reaction of the activated alkynes ZC≡CZ (2a‐g) [Z = CO2R: R = Me (a), Et (b); Z = R1: R1 = CF3 (c), CH2Cl (d), CH2Br (e); Z = CH2OC(O)R2: R2 = Me (f), CCl3 (g)] with the labile ruthenium complex (η2‐C2H4)Ru(CO)4 (1) results in the formation of three different types of heterocycles. While the reactions of the dialkyl acet‐ylenedicarboxylates 2a, b lead to the dimeric tricarbonylru‐thenacyclopentadienes 3a, b, being catalytically active in the cyclotrimerization of alkynes like 2a, b, the application of the 1,4‐halogeno‐2‐butynes 2c‐e yields the bicyclic heterocycles 4c‐e. The esters of 2‐butyne‐1,4‐diol 2f, g are converted into the tetracarbonylruthenacyclopentadienes 5f, g. Investigation of the primary attack of the alkynes 2a‐g at complex 1 leads to the conclusion, that an ionic mechanism is preferred in the ruthenium‐catalyzed cyclotrimerization of electron‐poor alkynes. If, instead of 1, (η2‐C2H4)Os(CO)4 (6) is allowed to react with the acetylenes 2a, b the osmium complexes (η4‐C6Z6)Os(CO)3 (7a, b) are isolated. In the presence of CO at 2 bar 7a, b release the benzene derivatives C6Z6 (8a, b) with the formation of Os3(CO)12.
Binary [Hydrotris(1,2,4‐triazolyl)borate]metal Complexes [M{HB(C2H2N3)3}2] with M = Fe, Co, Cu, Zn: Synthesis, Characterization, Magnetochemistry, and X‐ray Structure of [Cu{HB(C2H2N3)3}2·4CH3
Authors: Janiak Christoph
Published: July 2007

The bis[hydrotris(1,2,4‐triazolyl)borate]metal complexes [M{HB(C2H2N3)3}2] with M = Fe (5), Co (6), Cu (7), Zn (8) are obtained from MX2 and K[HB(C2H2N3)3] (9). The complexes are characterized by IR, UV/Vis, and MS. Temperature‐variable magnetic measurements show a Curie‐Weiss behavior for the paramagnetic complexes 6 and 7 with a temperature‐dependent magnetic moment for 6. The iron complex 5 exhibits a spin crossover from diamagnetic to paramagnetic, starting at around 270 K. Single‐crystal X‐ray structures of the solvates 7 · 4 CH3OH and 9 · 2 H2O have been determined. The structure of 7 · 4 CH3OH shows the Jahn‐Teller distorted copper complex 7 surrounded by methanol molecules through hydrogen bonding to exocyclic nitrogen atoms of the tris(1,2,4‐triazolyl)borate ligand. The crystal system for 7 · 4 CH3OH is monoclinic, space group P21/n. Compound 9 · 2 H2O is a one‐dimensional coordination polymer with the potassium atom bridged by the water molecules and the tris(1,2,4‐triazolyl)borate ligand and crystallizes in the orthorhombic space group Ccm21.
3‐Borolene mit diastereotopen Seiten: Synthese von 4‐(Dialkylamino)‐4‐boratricyclo[5.2.1.02,6]dec‐2(6)‐enen und Struktur des Dimethylamino‐Derivats
Authors: Herberich Gerhard E. , Spaniol Thomas P. , Steffan Uwe
Published: July 2007

3‐Borolenes with Diastereotopic Faces: Synthesis of 4‐(Dialkylamino)‐4‐boratricyclo[5.2.1.02,6]dec‐2(6)‐enes and Structure of the Dimethylamino Derivative

Two syntheses of 2,5‐dihyro‐1H‐borole derivatives with diastereotopic faces are described. 2,3‐Dimethylenenorbornane (2) is transformed into the zirconocene complex 5 (≡ Cp2Zr · 2) in a large‐scale preparation; 5 reacts with dichloro‐(dialkylamino)boranes BCl2(NR2) to give 4‐(dialkylamino)‐4‐boratricyclo[5.2.1.02,6]dec‐2(6)‐enes 1 (R = Me, iPr). Alternatively, 2,3‐dimethylnorbornene (santene) (3) or 3‐methyl‐2‐methylenenorbornane (4) can be kaliated by means of Lochmann‐Schlosser base to give a dimetallation product 6 (≡ K2 2); treatment of 6 with BCl2(NR2) also affords the boratricycles 1 (R = Et, iPr). The structure of the dimethylamino derivative 1a has been determined by X‐ray diffraction.
Stereoselective Additions of Chiral, Functionalized Organozinc Reagents to Achiral and Chiral Aldehydes: a Matched‐Mismatched Case in Organozinc Chemistry
Authors: Koert Ulrich , Wagner Holger , Pidun Ulrich
Published: July 2007

The additions of the enantiomerically pure organozinc reagents 17 and 33 to the THF‐aldehyde 1 in the presence of the monodentate Lewis acid boron trifluoride—ether give the nonchelation‐controlled addition products 7 and 36, respectively (stereoselectivity 95:5, 86:14). These results provide a route to oligo(tetrahydrofuran)s with the relative stereochemistry trans‐syn‐cis. A stereodirecting effect of the chiral center in the organozinc reagent 17 is found, leading to simple diastereoselectivies in the reaction with achiral aldehydes and to a matched‐mismatched case in the reaction with the chiral aldehyde 1.
Highly Substituted 1,3‐Dienes, V. A Theoretical Study of the Stereochemical Effects of tert‐Butyl Substituents in 1,3‐Butadiene
Authors: Trætteberg Marit , Bakken Pirkko , Hopf Henning , Hünel Ralf
Published: July 2007

For 1,3‐butadiene and for all mono‐ and di‐tert‐butyl derivatives potential energy curves, as function of the C=C–C=C dihedral angle, have been calculated by molecular mechanics methods (MM3). The stereochemical implication of these results are discussed for each of the compounds. The minimum‐energy conformer of each derivative has been optimized by ab initio HF calculations, using GAUSSIAN 90 and a 3–21G basis set.
Dithiametacyclophane mit Dreifachbindungen
Authors: Dai Yujia , Kolshorn Heinz , Meier Herbert
Published: July 2007

Dithiametacyclophanes with Triple Bonds

Schemes 1 and 2 show the syntheses of dithia[8]metacyclo‐phanes 4a‐d and tetrathia[m.n]metacyclophanes 9, 10 by cyclization reactions applying the cesium effect. All these cyclophanes contain C—C triple bonds which influence the molecular dynamics; especially the halogen substituents in 4b‐d obstruct the topomerization.
Liquid‐crystalline Compounds, 86. The First Disc‐Shaped Dinuclear Platinum Mesogen
Authors: Praefcke Klaus , Bilgin Belkiz , Pickardt Joachim , Borowski Marina
Published: July 2007

The cycloplatination of the tetrasubstituted imine 1 leads to the diplatinum organyl 3 as the main reaction product, which represents the first example of a new class of metallomesogens exhibiting monotropically a nematic‐discotic phase. An X‐ray crystal structure of this anti‐isomer 3 has been performed. Furthermore, this platinomesogen also shows the induction of a hexagonal columnar mesophase (Dho) on doping with 2,4,7‐trinitrofluorenone as an electron acceptor. Compared to the analogous palladomesogen the two mesophases observed are more stable in the case of the platinum liquid crystal.
anti‐Michael Addition of Cyanocuprate tBuCu(CN)Li to Acceptor‐Substituted Enynes
Authors: Gerold Andreas , Krause Norbert
Published: July 2007

Acceptor‐substituted enynes 1 react with lithium tert‐butyl‐cyanocuprate [tBuCu(CN)Li] in THF to afford anti‐Michael adducts 3. The formation of the isomeric side products 4 can be suppressed by regioselective protonation of the organometallic intermediates with ethanol at ‐80°C. Evidence for radical intermediates or electron‐transfer steps in these reactions could not be obtained.