bluuebunny/crossref_metadata_2025 huggingface dataset:
Intramolekulare Cycloadditionen mit Nitriloxiden: Untersuchungen zur Synthese von Heterophanen
Authors: Heinze Ingrid , Knoll Katja , Müller Ralf , Eberbach Wolfgang
Published: July 2007

Die intramolekularen Cycloadditionsreaktionen der aus 2,5‐difunktionellen Furan‐Hydroximsäurechloriden (12a, b und 18) bzw. den Nitroverbindungen 9c, d, 21 und 29 in situ hergestellten Nitriloxide 30a–d, 35, 36 und 47 werden beschrieben. Eine Reaktion zu den angestrebten Isoxazolo‐furanophanen des Typs 31 verläuft für 30c in brauchbarer Ausbeute; das Regioisomere 32c sowie das Dimere 34c treten hierbei nur in geringem Maße auf. Während das höchste Homologe 30d neben 31d und dem Makrocyclus 34d hauptsächlich Zersetzungsprodukte bildet, reagieren die Derivate mit kürzerer Seitenkette (30a, b; n = 1, 2) ausschließlich unter dipolarer Addition an eine Furandoppelbindung zu 33a, b. Für n = 1 entsprechen diesem Verhalten auch die elektronisch bzw. sterisch modifizierten Dipolsysteme 35/36 und 47, die trotz günstigerer Voraussetzungen für die Cyclophanbildung nur zu den Tricyclen 41, 42 bzw. 49 reagieren. Die präparativen Anwendungsmöglichkeiten der isomeren Cycloadditionsverbindungen als Synthesezwischenprodukte werden diskutiert.
Donorsubstituierte Benzonitrile als Seitenkettendienophile bei der intramolekularen [4 + 2]‐Cycloaddition mit inversem Elektronenbedarf
Authors: Seitz Gunther , Richter Joachim
Published: July 2007

Unter Einschluß donorsubstituierter Benzonitrile als Seitenkettendienophile haben wir die Anwendungsbreite der intramolekularen Diels‐Alder‐Reaktion von 1,2,4,5‐Tetrazinen erweitert und beschreiben Synthesewege zu neuen anellierten Heterotricyclen wie den Benzofuro[3,2‐e]‐1,2,4‐triazinen 11a, b und den Benzothieno[3,2‐e]‐1,2,4‐triazinen 14a, b sowie 17. Die doppelt anellierten Pyrazine 22 und 23 lassen sich durch eine nachfolgende zweite intramolekulare Benzonitril/1,2,4‐Triazin‐Diels‐Alder‐Cycloaddition mit 11a bzw. 14a als Edukten herstellen.
Metal complexes with tetrapyrrole ligands, LIV: Synthesis, spectra, structure, and redox properties of cerium(IV) Bisporphyrinates with identical and different porphyrin rings in the sandwich system
Authors: Buchler Johann W. , De Cian André , Fischer Jean , Hammerschmitt Peter , Löffler Jürgen , Scharbert Bernd , Weiss Raymond
Published: July 2007

Further symmetrical cerium(IV) bisporphyrinates are prepared from cerium(III) acetylacetonate and tetraphenylporphyrin, tetra‐p‐chlorophenylporphyrin, and hexadecahydrotetrabenzporphyrin. In the latter case, a biscerium(III) triple‐decker is also found which is the only product in the case of octamethylporphyrin. From a mixture of two different porphyrins, namely octaethylporphyrin [H2(OEP)] and either tetraphenylporphyrin [H2(TPP)] or tetra‐p‐chlorophenylporphyrin [H2(TClP)], besides the symmetrical species Ce(OEP)2 and Ce(TPP)2, the unsymmetrical (“mixed”) double‐deckers Ce(OEP)(TPP) or Ce(OEP)(TClP) are obtained which have different porphyrin rings in the sandwich system and can be separated by chromatography. The crystal structure analysis of Ce(OEP)(TPP) shows CeIV in a square‐antiprismatic geometry of the pyrrole N atoms of the porphyrin rings. While the IR and NMR spectra of the unsymmetrical double‐deckers are superpositions of the spectra of the individual rings, their UV/VIS spectra and cyclic voltammograms indicate that the two porphyrin rings behave as a common π‐electron system. The preparation of the π‐cation radical salts [Ce(OEP)2]ClO4 and [Ce(OEP)(TPP)]SbCl6 is also described. In the latter, the defect electron seems to reside preferentially in the OEP ring.
Aufbau von FeSn‐Bindungen über die Reaktion von Tris(trimethylstannyl)amin mit Fe(CO)5 und Fe(CO)4CS; 13C‐, 17O‐ und 119Sn‐NMR‐spektroskopische Untersuchungen
Authors: Petz Wolfgang , Wrackmeyer Bernd , Storch Wolfgang
Published: July 2007

Formation of Fe‐Sn Bonds by the Reaction of Tris(trimethylstannyl)amine with Fe(CO)5 and Fe(CO)4CS; 13C‐, 17O‐, and 119Sn‐NMR‐Spectroscopic Studies

The reaction between N(SnMe3)3 and Fe(CO)5 gives the known complex cis‐Fe(CO)4(SnMe3)2 (1) in high yield. In the analogous reaction of Fe(CO)4CS the complex fac‐Fe(CO)3(CS)(SnMe3)2 (2) is obtained together with small amounts of 1. In addition to the 13C‐NMR data, the 17O‐ and 119Sn‐NMR measurements proved particularly useful for studying the dynamic behaviour of 1 and 2.
[3.2]Paracyclophane‐10‐enes and [3.2.3.2]Paracyclophane‐10,27‐dienes: A convenient synthesis by the McMurry reaction and dynamic stereochemistry
Authors: Grützmacher Hans‐Friedrich , Neumann Ekkehard , Ebmeyer Frank , Albrecht Karsten , Schelenz Peter
Published: July 2007

The 1,3‐bis(4‐acylphenyl)propanes 2, 3, 9, 12, and 15 were subjected to a cyclization by reductive coupling with low‐valent titanium (McMurry reaction). 2 and 3 are converted into the corresponding 10,11‐dialkyl[3.2]paracyclophane‐10‐enes 4 and 5, respectively, under carefully controlled conditions in good yields. By the same method the dialdehydes 12 and 15 give rise to [3.2]paracyclophane‐10‐ene 13 and [3.2]metacyclophane‐10‐ene 16. However, the ditoluoyl derivative 9 gives rise only to the macrocyclic cyclophane 10 by dimerization. The corresponding macrocyclic cyclophanes 6 and 7 were also obtained from 2 and 3, respectively. The conformational mobility of the cyclophanes 4,5, and 13 was studied by variable‐temperature 1H‐NMR, and ΔG≠ = 48–51 KJ/mol was determined for the wobbling motion of the propano bridges.
A new synthesis of ortho‐Quinones by transition‐metal‐mediated oxygenation of phenols with tert‐butylhydroperoxide and the mimoun oxodiperoxo molybdenum complex [Mo(O2)2O] · Py · HMPT
Authors: Krohn Karsten , Rieger Hagen , Khanbabaee Karamali
Published: July 2007

A specific oxygenation of phenols to ortho‐quinones can be effected by a combination of the transition metal complexes Ti(OiPr)4, VO(acac)2, Zr(acac)4, Zr(OnPr)4 and tert‐butylhydroperoxide (TBHP) or [Mo(O2)2O] · Py · HMPT. Naphthols, anthracenols, phenanthrols and donor substituted mononuclear phenols are readily converted into the corresponding 1,2‐quinones. Unhindered ortho‐naphthoquinones can yield binaphthyls with unreacted starting material by Michael addition.
Cycloadditionen, 17: Einfluß von Methyl‐ und Phenylgruppen in der allenischen ω‐Position auf die thermisch induzierten Isomerisierungen von N‐[2‐Furanyl‐(Thienyl‐, Pyrrolyl‐)‐methyl]allencarboxamiden
Authors: Schlindwein Hans‐Jürgen , Himbert Gerhard
Published: July 2007

Die N‐(2‐Heteroarylmethyl)‐1,2‐alkadiencarboxamide 9a–q werden auf dem Ylid‐Weg synthetisiert und auf ihre Bereitschaft zur intramolekularen Diels‐Alder‐Reaktion untersucht. Die Pyrrolderivate 9p und 9q und das Thiophen‐Derivat 9o ohne direkt gebundenen Phenylkern zeigen lediglich Zersetzung, während die Thiophen‐Allene 9m und 9n durch Reaktion ihrer Amid‐Phenylkerne (R1  Ph) die „normalen”︁ Tricyclen 12a und 12b bilden. In allen Furfuryl‐allencarboxamiden (9a–1) geht der Furankern die intramolekulare Diels‐Alder‐Reaktion ein, unabhängig von der Art des Aminsubstituenten R1. Der Furankern reagiert in allen Fällen mit der endständigen Doppelbindung zu den Oxatricyclen 10a–1 mit sechsgliedrigem Lactamteil. Reaktion mit der ersten allenischen Doppelbindung (s. Bildung von 11c,d und g) wird daneben nur beobachtet, wenn durch Einbau von Methyl‐gruppen in die ω‐Position die Reaktion mit der endständigen Doppelbindung stark verlangsamt und die Bildung von 11 nicht durch eine Methylgruppe in der Furan‐5‐Position verhindert wird.
Cycloadditionen an die Doppelbindung von (R)‐2‐tert‐Butyl‐Δ4‐1,3‐oxazolin‐3‐carbonsäure‐methylestern
Authors: Seebach Dieter , Stucky Gerhard , Pfammatter Elmar
Published: July 2007

Die Titelverbindungen (mit und ohne zusätzliche Substituenten wie z. B. Methyl oder Vinyl in der 5‐Stellung) werden mit Persäuren (→ Dihydroxyderivate 3), mit Cyclopropanierungsreagentien (wie z.B. ICH2ZnEt, N2CHCOOEt, HCBr3 oder HCCl3/NaOH → Produkte 5–9), mit Tetracyanethylen und OsO4 (→ Produkte 19–20) und mit Dienophilen (Maleinsäureanhydrid, siehe 23) umgesetzt. Die Doppelbindung der Oxazoline reagiert hoch diastereoselektiv, wobei der bevorzugte Angriff von der der tert‐Butylgruppe abgewandten Seite erfolgt. Einige der erhaltenen Produkte werden weiter umgesetzt (siehe 4, 12–18, 23, 29–33). Stereochemische und synthetische Aspekte der Reaktionen werden diskutiert.
Ein neuer Weg zu N‐silylierten Diaminosulfanen: Die Spaltung der Si–Si‐Bindung in Disilanen durch Schwefeldiimide
Authors: Herberhold Max , Frank Stefan M. , Wrackmeyer Bernd , Borrmann Horst , Simon Arndt
Published: July 2007

A New Route to N‐Silylated Diaminosulfanes: The Splitting of the Si  Si Bond in Disilanes by Sulfur Diimides

Sulfur diimides (R1N)S(N2) (R1, R2 = tBu, SiMe3; 1a–c) and disilanes Cl2(R)Si–Si(R)Cl2 [R = Me (2), Cl (3)] react fast and quantitatively in a 1:1 ratio to give diaminosulfanes (4, 5) by cleavage of the Si–Si bond. The solid‐state structure of tBu(SiMeCl2)N–S–N(SiMe3)SiMeCl2 (4b) has been studied both by X‐ray crystallography and 29Si‐NMR spectroscopy.
Difluoro‐ and Dichlorodioxasilirane
Authors: Patyk Andreas , Sander Wolfram , Gauss Jürgen , Cremer Dieter
Published: July 2007

The reaction of difluorosilylene and dichlorosilylene with molecular oxygen in Ar matrices has been investigated. Under the reaction conditions the silylenes proved to be of low thermal reactivity, and irradiation in the UV/VIS was necessary to produce difluorodioxasilirane and dichlorodioxasilirane, respectively. The IR spectra have been assigned by isotopic labelling and by comparison with ab initio calculations.
Reductive Coupling by Chromium(0) – (Bibenzyl)‐ and (Stilbene)tricarbonylchromium(0) Complexes by a One‐Pot Reaction from Benzylic Halides
Authors: Wey Hans G. , Butenschön Holger
Published: July 2007

Reaction of Cr(CO)3(NH3)3 with benzylic mono‐, di‐, and trihalides leads to the formation of 1,2‐diarylethanes, ‐ethenes, and diphenylethyne in satisfactory yields. Di(halomethyl)benzene derivatives yield product mixtures containing both reduction products and coupling products. With a higher excess in chromium(O), under otherwise unchanged reaction conditions, the corresponding (arene)tricarbonylchromium(O) complexes of the coupling products are formed in a one‐pot reaction from the benzylic halides.
Synthese von Sieben‐ und Achtring‐anellierten Pyridinen durch “inverse” intramolekulare Diels‐Alder‐Reaktion mit Trifluormethyl‐substituierten 1,2,4‐Triazinen
Authors: John Rainer , Seitz Gunther
Published: July 2007

Synthesis of Seven‐ and Eight‐Membered Ring‐Annulated Pyridines by “Inverse” Intramolecular Diels‐Alder Reaction with Trifluoromethyl‐Substituted 1,2,4‐Triazines

Intramolecular [4 + 2] cycloaddition reactions with inverse electron demand of trifluoromethyl‐substituted 1,2,4‐triazines carrying 7‐ or 8‐membered o‐alkyne side‐chain dienophiles (3,8,12) lead to the synthesis of bicyclic pyridines with annulated heterocyclic seven‐ (5, 9, 13‐15) or eight‐membered rings (19, 22, 23, 26).
Concave Reagents, 4 Protonation of Nitronate Anions via concave Pyridines. Stereoselective C‐Protonation versus Nef Reaction
Authors: Lünig Ulrich , Baumstark Roland , Müller Michael , Wangnick Carsten , Schillinger Fritz
Published: July 2007

The intramolecular competition for C‐ or O‐protonation of the nitronate anion 5a is determined by sterical factors and by the [EtOH⊕2] concentration. The product of the Nef reaction 6 is formed in buffered, non‐acidic media when the proton donors are sterically hindered.
Redoxchemie, Zweikernkomplexe und Ru3‐Clusterderivate des ”︁Liganden”︁ [Cp(Co)2Mn–CN]−
Authors: Oswald BenoǏT , Powell Anne K. , Rashwan Farouk , Heinze Jürgen , Vahrenkamp Heinrich
Published: July 2007

Redox Chemistry, Dinuclear Complexes, and Ru3,‐Cluster Derivatives of the “Ligand” [Cp(CO)2Mn ‐ CN]−

By means of the compounds Na[Cp(CO)2MnCN] (1a, b) the abilities of the cyanide ion to link different organometallic units and to stabilize unusual electron counts in organometallic complexes were tested. The dinuclear complexes [Cp(CO)2Mn–CN–M]‐ [form M = MnCp(CO)2 and W(CO)5 as PPN salts 2a, 3a] as well as Cp(CO)2Mn–Cn–M [for M = MoCp(CO)3 and NiCpPPh3, 4a, 5a] were obtained in a pure state. From the reactions with Ru3(CO)12 the cluster derivatives HRu3(CO)10[μ‐NC–Mn(CO)2Cp] (6a, b) and Ru3(CO)10[μ‐NC–Mn(CO)2Cp]2 (7b) were characterized. One‐electron transfers were investigated for the starting complex and for the two anionic dinuclear complexes 2a, 3a. Crystal structures were determined of the dinuclear Mn–CN–Mn compex 2a and of the two cluster derivatives 2b, 7b.
Synthesen und Strukturen neuer Komplexes des 2,2′‐Bipyridins mit Niob, Molybdän, Wolfram und Rhenium in hohen Oxidationsstufen
Authors: Herrmann Wolfgang A. , Thiel Werner R. , Herdtweck Eberhardt
Published: July 2007

Syntheses and Structures of New 2,2′‐Bipyridine Complexes of Niobium, Molybdenum, Tungsten, and Rhenium in High Oxidation States

Exchange of oxo for chlorine ligands by means of hexamethyl‐disiloxane provides an easy and effective synthesis of the oxo halides (bipy)MVOCl3 (bipy = 2,2′‐bipyridine, C10H8N2; M = Nb, 1c; Re, 2c; W, 3c) and (bipy)MVIO2Cl2 (N = Mo, 6a;W, 6b). Starting from ReCl5 the structurally (X‐ray) characterized byproduct (bipy)ReIVCl4 (2b) is also formed. Dirhenium heptaoxide (7) is converted into the complex (bipy)ReVIIO3Cl (8) upon treatment with chlorotrimethylsilane in the presence of 2,2′‐bipyridine, thus being now easily available a key compound in rhenium chemistry. The new imido complexes of composition (bipy)MoVI(NR)2Cl2 [R = C(H3)3, 9a; C6H5, 9b] are accessible from 6a and the corresponding silylated amines. The rhenium and tungsten complexes 2b and 6b, resp., exhibit octahedral structures in the crystal, with that of 6b being distorted as a result of different ligands and intermolecular contacts.
Bifunktionelle Katalyse der Reaktion von Kohlendioxid mit Oxiranen
Authors: Dümler Walter , Kisch Horst
Published: July 2007

Bifunctional Catalysis of the Reaction of Carbon Dioxide with Oxiranes

Kinetic investigation of the Lewis acid/Lewis base‐catalyzed reaction of carbon dioxide with monosubstituted oxiranes 1 to cyclic carbonates 2 at atmospheric pressure reveals that the rate depends first order on substrates and the catalyst components ZnCl2 and (n‐Bu)4NI. Electron‐releasing substituents accelerate the reaction, except they are sterically demanding like the tert‐butyl group in which case complete inhibition occus; 2,2‐disubstituted oxiranes are inert. The activation parameters are ΔH≠ = (71.4 ± 3.7) kJ ± mol‐1 und ΔS≠ = (–49.2 ± 9.3) J ± K‐1. A rate law is established for the multi‐step reaction mechanism and simplified for the extremes of high and low pressure of carbon dioxide. The reactivity pattern of several catalyst combinations suggests that solvated zinc chloride and trihalogenozincates are the Lewis acids which catalyze the nucleophilic ring opening of the oxirane by iodide to the corresponding iodo alcoholate. This is stabilized by the Lewis acid as indicated by the investigation of the stereochemistry at the unsubstituted ring carbon atom by the use of [2‐D]‐2‐phenyloxirane. Nucleophilic attack of te alcoholate at carbon dioxide leads t the linear carbonate which is transformed into the product by intramolecular substitution of iodide.
Gold(I) Complexes of Primary Phosphanes: Pair Formation through Au…Au Interactions
Authors: Schmidbaur Hubert , Weidenhiller Gabriele , Steigelmann Oliver , Müller Gerhard
Published: July 2007

(CO)AuCl reacts with (2,4,6‐trialkylphenyl)phosphanes 1a–d (alkyl = Me, Et, iPr, tBu) to give the 1:1 complexes 2a–d. The crystal structure of 2d shows pairs of molecules with Au…Au contacts of 3.440(1) Å.
Ungewöhnliche Reaktion eines Diazaphosphetidinthions mit Trimethylsilylazid
Authors: Gruber Matthias , Schmutzler Reinhard
Published: July 2007

Unusual Reaction of a Diazaphosphetidinethione with Trimethylsilyl Azide

2‐Dimethylamino‐1,3‐dimethyl‐1,3‐diaza‐2‐phosphetidine‐4‐thione (1) and trimethylsilyl azide do not react with formation of the expected phosphane imine 2. Instead, (a) addition of trimethylsilyl azide to the °C=S group of 1, (b) sulfurization of the phosphorus atom of 1 and formation of the racemic thiophosphoryl compound 3 (as a result of intramolecular methyl/trimethylsilyl migration) take place. For 3 two pairs of diastereomers are discussed, which have been studied by 1H‐, 13C‐ and 31P‐NMR spectroscopy, and through a 1H‐13C NMR correlation.
Imidazole Derivatives, III. Regiospecific Synthesis,Structure, and Fluorescence Properties of Highly substituted Imidazo[1,2‐a]pyridines and Pyrido[1,2‐a]benzimidazoles
Authors: Knölker Hans‐Joachim , Hitzemann Rainer , Boese Roland
Published: July 2007

1‐(Arylacetyl)imidazoles 1 react with acetylenedicarboxylic esters to provide highly functionalized imidazo[1,2‐a]pyridines 2 in up to 89% yield. The scope and limitations of this novel condensation reaction have been investigated, ad a mechanistic interpretation is presented. A strong effect on the yield of this reaction is observed for electron‐donating and electronwithdrawing substituents in the para position of the aryl ring. Moreover, the transformation is shown to proceed in a regiospecific manner starting with 4,5‐unsymmetrically substituted 1‐(arylacetyl)imidazoles (1d–g) and is extended to the synthesis of the corresponding pyrido[1,2‐a]benzimidazoles 12. The crystal structure of derivative 2a has been determined by X‐ray analysis. Imidazo[1,2‐a]pyridines 2 and pyrido[1,2‐a]‐benzimidazoles 12, obtained by this procedure, are highly fluorescent in the visible region with characteristically large Stokes shifts.
Ozonolysen von Olefinen mit vinylständigen Chlorsubstituenten auf Polyethylen
Authors: Griesbaum Karl , Greinert Reinhard
Published: July 2007

Ozonolyses of Olefins with Chloro Substituents in Vinylic Positions on Polyethylene

Ozonolyses of the chloro‐substituted 5‐ and 6‐membered cycloolefins 20a, 20b and 30a–c on polyethylene afforded the corresponding chloro‐substituted ozonides. The thermal decomposition of these ozonides is described. Ozonolyses of the same olefins in solution and of the acyclic chloro olefins 5 and 8 both on polyethylene and in solution gave no ozonides.
Nickelapnicogencubane
Authors: Scherer Otto J. , Braun Jürgen , Wolmershäuser Gotthelf
Published: July 2007

Nickelapnicogencubanes

The thermolysis of [C*pNi(CO))]2 (1) (C*p=η5‐C5Me5) and [Cp′Ni(CO)]2 (6) (Cp′ = η5‐C5H4Me) with the pnicogens E4 (E = P, As) affords the distorted cubanes [(C*pNi)3(μ3‐E)(E4)] (2a: E = P; 2b: E = As), the sandwich complex [C*pNi(η3‐P3)] (3), as well as the cubanes [Cp′Ni(μ3‐E)]4 (7a,b) and the trinuclear cluster [(Cp′Ni)3(μ3‐CO)2] (8). With [M(CO)5(thf)], 2a and 3 give the multinuclear clusters [(C*pNi)3(μ3‐P)(P4)M(CO)5] (4a: M = CR; 4b: M = Mo; 4c: M = W) as well as [C*pNi(P3)‐{Cr(CO)5}3] (5). In addition to the NMR studies, 2a,b and 3 have been characterized by X‐ray structure analyses.
Cycloadditions of 1‐Thia‐3‐azoniabutatriene Salts to Azomethines, Carbodiimides, and Ketene Imines
Authors: Jochims Johannes C. , Lubberger Hans‐Jürgen , Dahlenburg Lutz
Published: July 2007

A new method for the preparation of sulfur‐substituted 2‐azoniaallene salts (3a–f, 5a–d, 7) by [2 + 2] cycloadditions of 1‐thia‐3‐azoniabutatriene salts (1c,d) to azomethines (2a–f), carbodiimides (4a–d), and the ketene imine 6 is described. The X‐ray crystal analysis of the adduct 3b of 4‐(dimethylamino)‐4‐phenyl‐1‐thia‐3‐azoniabutatriene hexachloroantimonate (1d) to N‐benzylidene‐p‐toluidine (2b) shows an almost planar 2‐azaallylium cation with a W‐shaped arrangement of the N–C–N–C–N fragment, the plane of which also contains the 1,3‐thiazetidine ring. Improved methods for the preparation of 1d and the corresponding tetrachloroaluminate (1e) are given.
Mechanism of CH2+ Transfer from Distonic Ions X ‐ CH2+ (X = CH2O, CH2CH2) to π‐ and n‐Electron Bases in the Gas Phase. A Fourier Transform Ion Cyclotron Resonance (FTICR) Study Supplemented by ab initio MO Calculations
Authors: Rusli Ridwan D. , Schwarz Helmut
Published: July 2007

The reactions of acetonitrile, propyne, acetylene, trimethyl‐silylacetylene, and tetramethylsilane, with distonic ions CH2XCH2+ [X = CH2 (2), O (3)] are studied in the gas phase using Fourier Transform Ion Cyclotron Resonance (FTICR) mass spectrometry. In line with previous studies, CH2+ is transferred to the electron Ione‐pair of the nitrogen atom of CH3CN to generate CH3CN–CH2+ (4); upon collisional excitation, this ion undergoes competitive losses of H* and CH*. While both neutrals originate from the “methylene” unit of 4′, detailed studies employing labeled substrates and using various types of collision experiments reveal an intriguing dissociation pattern in that the dissociations are preceded by two intramolecular hydrogen migrations giving rise to CH3C(H) = NCH* + (6) and CH3C = N(H)CH*+ (7). While 6 serves as intermediate en route to loss of H* from the “CH” moiety, 7 is the actual precursor to generate, by loss of CH*, protonated acetonitrile, CH3CNH+ (12) (Scheme 5). In addition, 12 is formed by bimolecular proton transfer. In this reaction, translationally excited CX3CN – CY2+ * (X, Y = H, D) transfers X +‐ to neutral CX3CN to generate CX3CNX+ (Scheme 4). The bimolecular proton transfer as well as the intramolecular isomerizations of 4 to 6 and 7 are subject to very large kinetic isotope effects. In the transfer of CH2+ to CH3C = CH two products are formed [i.e. H3C ‐ C ≡ C ‐ CH3+ (16) and CH2  C = CHCH3+ (l7) presumably via intermediate 18 (Scheme 6)]; the latter is formed by addition of CH2+ to the less hindered carbon atom of HC ≡ CCH3 reflecting the higher stability of the so‐formed intermediate compared with addition to C‐2, Reactions of 2 and 3 with HC ≡ CH do not result in the formation of a detectable CH2+‐transfer product. When using CH2CH2CH2+ (2) the reaction is prohibited by the endothermicity to generate the initial complex (structurally related to 18). On the other hand, when CH2OCH2+ (3) is employed, the intermediate of CH2+ transfer is formed with sufficient energy to split off a hydrogen atom. Preliminary experiments with silicon‐containing molecules, like Si(CH3)4 or HC ≡ CSi(CH3)3, demonstrate that the favored processes of these neutrals with 2 and 3 are due to charge transfer (in the form of an electron or an anion like CH‐3 or C2H‐) from the silicon‐containing molecule to the distonic ions. The experimental results obtained for the CH3CN/CH2+ system are supported by ab initio MO calculations (3‐21G/3‐21G + ZPVE).
Asymmetric Induction in the Wittig‐Still Rearrangement of Ethers Containing an Allylic Stereocenter – Diastereocontrol by Allylic Nitrogen
Authors: Priepke Henning , Brückner Reinhard , Harms Klaus
Published: July 2007

The stereochemistry of Wittig‐Still rearrangements under the influence of an allylic stereogenic center attached to Bn2N or RNBoc groups is studied. Rearrangements are subject to stereocontrol through asymmetric induction. Stannylated allyl ethers 13 with Z double bonds give syn‐configuration amino alcohols 15 exclusively (ds >95 : < 5 ‐ > 99.8 : < 0.2). Stannanes of E configuration 14 lead to 15 less selectively (syn :anti = 46 : 54 ‐ 92 : 8). X‐ray structural data are provided for amino alcohol syn‐15b and for the bis(carbamate) 17.
Alkin⇄Vinyliden‐Umwandlungen auf Vierkernclustern
Authors: Albiez Thomas , Powell Anne K. , Vahrenkamp Heinrich
Published: July 2007

Alkyne ⇄ Vinylidene Rearrangements on Tetranuclear Clusters

The expansion of vinylidene‐bridged FeCo2 and RuCo2 clusters 1a–d, 2d with (cyclopentadienyl)rhodium building blocks 3a, b mainly yields alkyne‐bridged FeCo2Rh and RuCo2Rh clusters (4b–d, 5a, b, 6d), which exist as two isomers A and B. Additionally, in a few cases tetranuclear clusters 7, 8 containing one more CO group and bearing a μ4‐vinylidene ligand are formed. The two cluster types can be interconverted by CO transfer. Starting from both types of FeCo2Rh clusters (4b, d, 8b), metal exchange with NaMoCp(CO)3 produces a product mixture in which the majour tetranuclear complex is the novel tetrahedral FeCoRhMo compound (11b, d, 12b) with a μ3‐vinylidene ligand. Thus it is shown that the shape as well as the mode of attachment of the CCHR ligand are controlled by the number and electronic structure of the organometallic building blocks. The structural assignments have been confirmed by four X‐ray structure determinations [4b(A), 4b(B), 8a, 11b].
Partial Hydrogenation: From Anthracene to Coronene
Authors: Yalpani Mohamed , Köster Roland
Published: July 2007

Reduktion kondensierter Arene mit ‐Boranen. – Partielle Hydrierung: Anthracen bis Coronen

Tetrapropyldiboran(6) (TPDB) katalysiert die Hydrierung polycyclisher Arene [z. B. Anthracen (A), Tetracen (TET), Pyren (PY), Perylen (PER) oder Coronen (C)] unter Wasserstoff‐Druck bei 200°C. In einigen Fällen können sehr hohe Ausbeuten an Hydroarenen erzielt werden [z. B. Tetrahydroanthracen (4H‐A), Octahydroanthracen (8H‐A), Dodecahydrotetracen (12H‐TET), Tetrahydropyren (4H‐PY), Hexahydroperylen (6H‐PER) oder Hexahydrocornen (6H‐C)]. Neben unterschiedlichen kleinen Mengen an Perhydroarenen bilden sich nach langer Reaktionszeit aus sämtlichen Arenen auch C – C‐Spaltungsprodukte.
[4 + 2]‐Cycloadditionen mit Übergangsmetall‐koordinierten Heteroalkenen: Einfluß der Koordination auf die Stereoselektivität der Cycloaddition
Authors: Fischer Helmut , Hofmann Josef , Treier Kornelia , Gerbing Ulrike
Published: July 2007

[4 + 21 Cycloadditions with Transition‐Metal‐Coordinated Heteroalkenes: The Influence of the Coordination on the Stereoselectivity of the Cycloadditon

Pentacarbonyl(thiobenzaldehyde), ‐(selenobenzaldehyde), and ‐(diphenyl selenoketone) complexes (CO)5M[X = C(Ph)R] [R = H: M = W, X = S (1a), Se (1b); M = Cr, X = S (1c), Se (1d); R = Ph: M = W, X = Se (1e)] react with cyclopentadiene (2) and 1,3‐cyclohexadiene (4), respectively, by [4 + 2] cycloaddition to give metal‐coordinated this‐ and selenacycles 3 and 5. The additions of 2 and 4 to 1a‐d are stereoselective. In contrast to the endo selectivity observed in the reactions of 2 and 4 with uncomplexed thio‐ and selenoaldehydes, the additions of 2 and 4 to 1a‐d are exo selective. However, the reactions of pentamethylcyclopentadiene (6) with 1a,b to form 7 are endo selective. The structures of the main isomer of the addition of 4 to 1c (5c‐exo) and of 6 to 1 b (7b‐endo) were confirmed by X‐ray analyses.
Zur Reaktivität von Phosphaalkenyl‐ und Phosphavinyliden‐Komplexen des Molybdäns und Wolframs gegenüber dem Schwefelylid Me2S(O)=CH2 Röntgenstrukturanalyse von
Authors: Weber Lothar , Matzke Thomas , Boese Roland
Published: July 2007

Transition‐Metal‐Substituted Acylphosphanes and Phosphaalkenes. XIV. – Transition‐Metal Sulfur Ylide Complexes, XXVIII. – Reactivity of Phosphaalkenyl and Phosphavinylidene Complexes of Molybdenum and Tungsten towards the Sulfur Ylide Me,S(O) = CH2. X‐ray Structure Analysis of

The phosphavinyliden complexes (η5‐C5H5)(CO)2M=P=C(SiMe3) 2 [3, M = Mo (a); W (b)] react with equimolar amounts of sulfur ylide Me2S(O)=CH2 (2) to afford the red metallophosphane‐substituted sulfur ylides (η5‐C5H5)(CO)2M=P[CH‐(SiMe3 2][CH=S(O)Me2] (5a, b). Compounds 3a, b as well as 5a, b are trans‐formed to the metallaheterocycles (η5‐C5H5)‐ (6a, b) by excess of ylide. Constitution and configuration of 5 and 6 were established by spectroscopic means (IR, 1H, 13C, 31P NMR and MS). In addition, the molecular structure of 6a was elucidated by single crystal X‐ray diffraction analysis.
Eine 1,3‐Methyl‐Verschiebung an der ungesättigten BCSi‐Kette
Authors: Paetzold Peter , Schmitz Thomas , Tapper Alexander , Ziembinski Ralf
Published: July 2007

A 1.3‐Methyl Shift along the Unsaturated BCSi Skeleton

The synthesis of the methoxy[tris(trimethylsilyl)methyl]boranes X‐(MeO)B–C(SiMe3)3 (1a‐d; X = Cl, Br, Ph, PhCH2) is described. The methylenoboranes Me‐B=C(SiMe2Hal) (3a, b), the 2,3‐dihydro‐1H‐1‐sila‐3‐boraindene species 6, and the 1,2,3,4‐tetrahydro‐1‐sila‐3‐boranaphthalene species 7 are formed by the thermal elimination of MeOSiMe3 from 1a/b or 1c or 1d, respectively. The boranes 3a, b undergo cyclodimerization at the B=C bond at 25 and 69°C, respectively, the diboretanes 4a, b being formed. The oxaboretanes 5a, b are isolated from the reaction of 3a, b with Ph2CO. The thermal elimination of MeOSiMe3 from Me′‐(MeO)B–C(SiMe3)3 (1g;; Me′ = CD3) and subsequent addition of Ph2CO gives the oxboretanes 5g′/5g″ in the ratio of 1:6, showing that an equilibrium Me′‐B=C(SiMe32 ⇄ Me—B=C(SiMe3(SiMe2Me′) with a statistical distribution of Me′ among seven methyl places is established in the hot tube before Ph2CO finally attacks the double bond. All these results are in accord with the primary formation of the methyleneboranes X‐B=C(SiMe3)2 from 1a‐d, followed by a 1,3‐shift of Me along the unsaturated BCSi skeleton and the subsequent transformation into the isolated products.
Reaktionen von Pentacarbonyl(trifluormethylisocyanid)chrom mit Nucleophilen
Authors: Lentz Dieter , Marschall Robert
Published: July 2007

Reactions of Pentacarbonyl(trifluoromethyl isocyanide)chromium with Nucleophiles

Pentacarbonyl(trifluoromethyl isocyanide)chromium (1) reacts with nucleophilic reagents like secondary amines (2a‐d), 1,2‐dimethylhydrazine (2e), or methanol (2f). The first nucleophilic attack occurs at the isocyanide carbon atom. The formed Fischer‐type carbene complexes readily eliminate HF under the reaction conditions forming a difluoromethanimine moiety, which is further attacked by the nucleophile. The isolated products are carbene complexes of the type (CO)5Cr[C(NR2]N=C(NR2)F] (3a‐c), (CO)5Cr[C(NR2)N=C(NR2)2](3d), (CO)5Cr[CN(CH3)N(CH)3C{N(CH3)H}=N] (3e), and (CO)5Cr(C(OCH3)N=C(OCH3)2] (3f). The structure of 3c has been determined by an X‐ray crystal structure analysis.
Synthesis and Stereochemistry of Stereoisomeric 1,3‐Oxazino‐ and 1,3‐Thiazino[4,3‐a]isoquinolines
Authors: Fülöp Ferenc , Bernäth Gäbor , El‐Gharib M. S. , Kóbor Jenö , Sohár PÁL , Pelczer István , Argay Gyula , Kálmán Alajos
Published: July 2007

Starting from the 6,7‐dialkoxy‐1‐[bis(hydroxymethyl)methyl]‐1,2,3,4‐tetrahydroisoquinolines 2 and 3, the 4‐imino‐substituted 1‐(hydroxymethyl)‐9,10‐dialkoxy‐2H, 4H‐1,6,11b‐tetrahydro‐1.3‐oxazino‐and ‐thiazino [4,3‐a]isoquinoline diastereomers 6a‐c, 7a‐c, 8a‐c, 9a‐c, 14, and 15 and the 4‐substituted 1,6,7,11b‐tetrahydro 1,3‐oxazino[4,3‐a]isoquinoline diastereomers 16–24 were prepared. the relative configurations and the predominant conformation of these products were determined by NMR spectroscopy and for 18 by X‐ray diffraction methods. the prepared 1,3‐oxazino[4,3‐a]isoquinoline diastereomers have predominantly trans conformations (16, 18, 22, 23), whereas cis conformations (cis‐A) prevail for 20, 21 and f24. Thus, the first evidence for either trans‐ or cis‐A conformations in 1,3‐oxazino[4,3‐a] isoquinolines is presented.
Neue optisch aktive Chelat‐Phosphane – Synthese und Verwendung in der enantioselektive Katalyse
Authors: Brunner Heari , Lautenschlager Hans‐Jürgen , König Wilfried A. , Krebher Ralph
Published: July 2007

Asymmetric Catalysis, LI. – New Optically Active Chelating Phosphines – Synthesis and Application in Enantioselective Catalysis

The known triphosphines 1 and 4 were transformed into their monophosphine oxide and monophosphine sulfide derivatives 2, 3, 5, and 6 via NiCl2 complexes. 21 optically active phosphines were used as ligands in the Rh‐catalysed hydrogenation of (Z)‐α‐acetamidocinnamic acid and itaconic acid as well as in the Ni‐catalysed cross‐coupling reaction of phenylethylmagnesium chloride with vinyl bromide. The optical inductions of the Grignard cross coupling reaction were determined the first time by enantioselective gas chromatography.
Die β‐Spaltung von α‐(Methoxycarbonyl)alkyl‐Radikalen
Authors: Metrger Jürgen O. , Klenke Kurt
Published: July 2007

Investigations on the Selectivity of the β‐Scission of Alkyl Radicals, 11′1. – Selectivity of the β‐Fragmentation of α‐(Methoxycarbony1)alkyl Radicals

The rate of β‐scission of α‐(Methoxycarbonyl)alkyl radicals 3 und 9, generated by addition of cycloalkyl radicals to appropriate methyl 2‐methylenealkanoates 1 and methyl (E)‐2‐alkenoates 8, resp., has been measured relative to the hydrogen transfer from cycloalkanes. The rate of β‐scission increases with increasing stability of the leaving radical R*, Polar effects reversing the stability sequence have also been observed, e. g. the stability sequence have also been observed, e. g. the more stable (methoxycarbonyl) methyl radical leaves more slowly than a less stable secondary alkyl radical.
Radikalische Cyclisierung von Dienen, III Radikalische Cyclisierung von (R)‐(‐)‐Carvon – Über den Einfluß von Charge‐Transfer‐Wechselwirkung auf den spezifischen Drehwert
Authors: Weinges Klaus , Maurer Wplfgang , Reichert Hans , Schilling Gerhard , Oeser Thomas , Iragartinger Hermann
Published: July 2007

Radical‐Type Cyclisation of Dienes, 111. – Radical‐Type Cyclisation of (R)‐( – )‐Carvone – On the Influence of Charge‐ Transfer Interactions on the Optical Rotation

Under the conditions of radical cyclisation, a 1:1 diastereomeric mixture of (1R,2S,5R,R)‐(+)‐ (2a) and (1R.2S,5R,6S)‐(+)‐6‐methoxy‐2,6‐dimethylbicyclo[3.2.1]octan‐3‐ones (2b) is obtained from (R)‐(‐)‐carvone in 70% yield. the configuration fo 2a and 2b were confirmed by X‐ray structure analyses of their hydrazones 2d and 2e. The regio‐ and stereoselectivity of the radical cyclisation of 1 to 2a and 2b are discussed. The high value of the specific rotation [‐555] of 2d is traced back to charge‐transfer interactions between the endo‐standing methoxy group at C‐6 as electron donor and the dinitrophenyl‐hydrazone group as electron acceptor.
Asymmetric Induction in the [2,3] Witting Rearrangement by Chiral Substituents in the Allyl Moiety: 1,3‐Asymmetric Induction
Authors: Scheuplein Stefan W. , Kusche Andreas , Brückner Reinhard , Harms Klaus
Published: July 2007

Witting rearrangement of he type4→5 can exhibit stereocontrol due to asymmetric induction. The Wittig‐still rearrangements of stannylated ethers (E)‐10 and (Z)‐10 are stereochemically complementary and furnish the homoallylic alcohols anti‐11 and syn‐11 with high diastereoselectivity (ds = 95:5 and 97:3, respectively. The 1,3‐asymmetric induction established in the transformation of ether (Z)‐10 can be reversed and combined with a 1,4‐asymmetric induction as shown by the stereoselective Witting rearrangement of allyl propargyl ether 28 (ds = 88:6:5:1). 1,4‐Asymmetric induction alone was observed neither in the [2,3] Wittig rearrangement tof propargyl ether 34 nor in that of (allyloxy)acetate 37.
Notizen / Notes Phosphorverbindungen ungewöhnlicher Koordination, 43 Hochfunktionalisierte λ3‐Phosphinine aus 5,5‐Dimethoxycyclopentadienen und einem kinetisch stabilisierten Phosphaalkin
Authors: Amena Ulrich , Regitz Manfred , Klugeb Heinz
Published: July 2007

Phosphorus Compounds with Unusual Coordination, 43. – Highly Functionalized λ3‐Phosphinines from 5,5‐Dimethoxycyclopentadienes and Kinetically Stabilized Phosphaalkyne

1,2,3,4‐Tetrachloro‐5,5‐dimethoxycyclopentadiene (5) is transformed into the λ3‐phosphinine 10 by reaction with the phosphaalkyne 6; the bicyclic compound 7 is assumed to be the intermediate of the process. In an analogous way the reaction 14 + 6 yields the isomeric λ3‐phosphinines 15 and 17.
“Tuning” CH/CC Bond‐Activation Processes of Branched Amines by Choosing the Appropriate Gas‐Phase Transition‐Metal Ion
Authors: Karaß Sigurd , Eller Karsten , Schwarz Helmut
Published: July 2007

The mechanisms of the deceptively similar gas‐phase chemistry of amine complexes RC(CH3)2CH2NH2/M+ (R = H, CH3 M = Fe, Co, Ni) are uncovered by the use of deuterium‐labeled compounds. It is demonstrated that the details of CH/CC bond‐activation reactions are strongly metal‐ion‐dependent, as is the product distribution itself.
Disproportionierung von Schwefeldioxid am Molybdän(0)‐Komplex trans‐[(dppe)2Mo(N2)2] Molekülstruktur von trans‐[(dppe)2Mo(S)O]·SO2·H2SO4
Authors: Lorenz Ingo‐Peter , Walter Gudrun , Hiller Wolfgang
Published: July 2007

Disproportionation of Sulfur Dioxide by the Molybdenum(0) Complex trans‐[(dppe)2Mo(N2)2]. Molecular Structure of trans‐[(dppe)2Mo(S)O]·SO2·H2S04

Sulfur dioxide disproportionates into sulfur monoxide and sulfuric acid, when it is passed through a solution of the molybdenum(0) complex trans‐[(dppe)2Mo(N2)2] (1) in toluene. Whereas SO undergoes an oxidative addition reaction onto the intermediate 14 VE‐complex fragment (dppe)2Mo to give the mixed dichalkogenidomolybdenum(IV) complex trans‐[(dppe)2Mo(S)O] (3), both molecules H2SO4 and intact SO2 remain in the solvating sphere. According to an X‐ray structural analysis 3 crystallizes in the monoclinic space group P21/n and shows an octahedral configuration at the central molybdenum atom with the oxo and sulfido ligands in trans positions; the two solvent molecules ethanol and toluene are also incorporated into the crystal lattice.
Metallabis(dialkylphosphito)‐Einheiten als Komplexbildner, VI. Darstellung und Komplexbildungsvermögen des metallorganischen Chelatliganden {C5Me5RhI[P(O)(OMe)2]2}−
Authors: Valderrama Mauricio , Scotti Mario , Campos Pedro , Werner Helmut , Müller Gerhard
Published: July 2007

Complexes Containing Metallabis(dialky1phosphito) Units, VI1. – Synthesis and Complex‐Forming Properties of the Organometallic Chelating Ligand {C5Me5RhI[P(0)(OMe)2]2}‐

The dinuclear complexes [C5Me5NiBr]2 and [C5Me5RhI2]2 react stepwise with P(OMe)3 by cleavage of the halide bridges and a subsequent Michaelis‐Arbuzov‐type reaction to give the neutral compounds C5Me5Ni[P(O)(OMe)2][P(OMe)3] (3) and C5Me5RhI[P(O)(OMe)2][P(OMe)3 (6). Treatment of 6 with an equimolar amount of NaI gives the sodium salt of the {C5Me5RhI[P(O)(OMe)2]2}− anion Na[L] (7) isolated as an adduct with 0.6 NaI. Reaction 7 with H2SO4 in water leads to the formation of the protonated complex C5Me5RhI[P(O)(OMe)2][P(OH)(OMe)2] (8), from which on treatment with thallium acetylacetonate C5Me5RhI[P(O)(OMe)2]2TI (9) is obtained. The X‐ray structural analysis of 9 reveals that the organometallic anion L− is coordinated as a bidentate ligand by the P = O oxygen atoms to thallium, L− also behaves as a bidentate chelating ligand in the complexes [L]2Mg(OH2)2 (12), [L]2Zn (13) and [L]2UO2 (14), whereas it is presumably coordinated as an O,O′,I‐tripod ligand in the compounds [L]PtMe3 (10) and [L]2Cu (11). In acid solution 8 reacts with NaBPh4 to give the diphenylborane derivative LBPh2 (15).
Synthesis and Antitumor Activity of Pt(II) Complexes of Benzyl‐1,2‐diaminoethane Ligands
Authors: Brunner Henri , Hankofer Peter , Treittinger Barbara
Published: July 2007

Twelve new diamine ligands are synthesized and characterized in which a benzyl group and another vicinal substituent or a benzyl group, a 4‐Cl‐benzyl group, and a 4‐MeO‐benzyl group, respectively, and two other geminal substituents are attached to the 1,2‐diaminoethane skeleton. The diamine ligands are transformed into the dichloroplatinum(II) complexes. The chloride ligands of four complexes are replaced by the lactate anion, α‐Cyclodextrin and polyvinylpyrrolidone are used to increase the water solubility of the Pt(II) complexes. The antitumor activity of the Pt(II) complexes is tested towards the P388 leukemia. The compounds with small alkyl substituents show antitumor activities which are much higher than the antitumor activity of cis‐platinum. Compared to the insoluble dichloro complexes, the lactate complexes and the formulations with α‐cyclodextrin and polyvinylpyrrolidone exhibit good water solubility, and no decrease of the antitumor activity is observed.
Hydrocarbonylierende Cyclisierung von Dienen, 7. Cyclisierung von 1,4‐Dienen mit funktionalisierten Seitenketten an C‐3
Authors: Eilbracht Peter , Hüttmann Gerd‐Erich
Published: July 2007

Hydrocarbonylating Cyclization of Dienes, 71. – Cyclization of 1,4‐Dienes Containing Functionalyzed Side Chains at C‐3

In order to test, whether functional groups are tolerable in rhodium‐ or cobalt‐catalyzed hydrocarbonylating cyclizations of 1,4‐dienes 1 to substituted cyclopentanones 2, various dienes of type 3 with functionalyzed side chains in C‐3 were synthesized and treated under cyclization conditions. Ester, hydroxy, alkoxy, and acetate groups proved to be sufficiently stable (the latter only in rhodium‐catalyzed conversions), so that the corresponding cyclopentanones 4 could be obtained in medium to good yields. Free carboxylic acid and aldehyde groups, however, prevented the formation of significant amounts of cyclization products. Pentenynes of type 6 under analogous conditions yielded at best only minor amounts of cyclopentanones.
Carbonylierende Ringerweiterung, 5. Enantioselektive Synthese des Bicyclo[3.2.1]oct‐3‐en‐2,8‐dion‐Systems durch doppelte Carbonylierung von α‐Terpinen und anderen prochiralen Cyclohexadienen
Authors: Eilbracht Peter , Hittinger Christel , Kufferath Klaus , Schmitz Anja , Gilsing Hans‐Detlev
Published: July 2007

Carbonylating Ring Enlargement, 51). – Enantioselective Synthesis of the Bicyclo[3.2.l]oct‐3‐ene‐2,8‐dione Systems by Double Carbonylation of α‐Terpinene and Other Prochiral Cyclohexadienes

The steric information in tricarbonyl iron complexes of type 2(R1 ≠ R2), established during the complexation of prochiral 1,3‐cyclohexadienes can be transferred to bicyclo[3.2.1]oct‐3‐ene‐2,8‐diones by metal‐induced ring enlargement and bridging carbonylation. This was verified by the synthesis and conversion of optically active tricarbonyl iron complexes 2 of α‐terpinene (1). These complexes can be either obtained by chirality transfer during complexation and rearrangement of (R)‐(+)‐ or (S)‐(‐)‐limonene (7) or by separation of racemic mixtures on triacetyl cellulose. The separation on chiral phases and subsequent stereoselective conversion to bicyclo[3.2.1]oct‐3‐ene‐2,8‐diones may also be carried out with other tricarbonyl iron complexes of prochiral cyclohexadienes (lacking additional functional groups).
Fourfold Diamond Structure of the Dipotassium and Disodium Salts of 1,3,5,7‐Adamantanetetracarboxylic Acid
Authors: Ermer Otto , Lindenberg Lorenz
Published: July 2007

The (isomorphous) crystal structures of the dipotassium and disodium salts of 1,3,5,7‐adamantanetetracarboxylic acid are described. In the tetragonal, non‐polar crystals of space group P42/nbc hte tetrahedral dihydrogen tetracarboxylate anions join to form four hydrogen‐bonded superdiamond networks interpenentrating each other. The cations are arranged in chains (“metal‐over‐metal”] within fourfold helical channels (double antiparallel double‐helices). The short, negatively charged O‐H…O⊖ hydrogen bonds are symmetric on average. However, in the dipotassium salt actually disordered, asymmetric hydrogen bonds are likely to be present (double‐minimum potential, O‐H…O⊖ distance 2.52 Å). In analogy to potassium dihydrogen phosphate, KH2PO4, the present tetrahedral dipotassium dihydrogen tetracarboxylate may thus potentially form polar, ferroelectric crystals at low temperature with an ordered array of asymmetric hydrogen bonds. In the course of the crystallization of the disodium salt of adamantanetetracarboxylic acid, tetragonal crystals of a tetrahydrate of the tetrasodium salt were accidentally obtained (space group I41/α) and their structure determined. The arrangement of the hydrated anions may be characterized either as a hydrogen‐bonded, distorted triple‐diamond structure, or else aas a “semi‐clathrate”, consisting of non‐intersecting orthogonal water chains interpenetrating each other and tetracarboxylate tetraanions functioning as cross‐links between these chains by means of hydrogen bonds.
Konformationsanalysen von pyrolytisch erzeugten [2.2]phanen des 4‐Pyranons
Authors: Massa Werner , Schween Michael , Steuber Friedrich W. , Wocadlo Sigrid
Published: July 2007

Conformational Analyses of [2.2]Phanes of 4‐Pyranone Generated by Pyrolysis

The synthesis of the first phanes of 4‐pyranone is accomplished by pyrolysis of bis(sulfone) 4. Analogously, 9, 10 and 11 are synthesized. While 5is conformationally mobile in solution, 9 and 10 are fixed (up to 100°C) and exhibit anti conformation as shown by X‐ray structural analysis (11). Like 9 and 11, 5, exists in a staircase‐like structure in the crystal. 1H‐NMR spectra of the metaparacyclophane 10 shows coalescence of the signals of the methylene protons at room temperature. The flexibility at 10 at 60°C is interpreted as a swinging process. The crystal structure of bis(sulfone) 8a shows that the two planar rings are tilted by 60°C with respect to each other.
Conformation of C‐1‐Substituted Pyranos‐1‐yl and Pyranosan‐5‐yl Radicals Evidence for a Quasi‐Homo‐Anomeric Stabilization Effect
Authors: Korth Hans‐Gert , Sustmann Reiner , Praly Jean‐Pierre , Somsák László
Published: July 2007

Acetylated 1‐cyano‐ and 1‐chloro‐pyranos‐1‐yl radicals and 5‐acetoxycarbonyl‐, 5‐methoxycarbonyl‐, and 5‐unsubstituted pyranosan‐5‐yl radicals were generated from the corresponding bromides by bromine abstraction with trimethyltin radicals. The conformation of these radicals, as deduced from the ESR hyperfine splittings, is explained by the combined action of a quasi‐anomeric and a homo‐anomeric stabilization effect. A captodative substitution pattern of the radical center does not influence the conformations.
Koordinationschemie π‐gebundener Cyclopentadienyl‐Chalkogeno‐Ether, I. Chelatkomplexe von Pentakis(methylthio)cymantren mit Metallcarbonylen
Authors: Sünkel Karlheinz , Blum Adrian , Polborn Kurt , Lippmann Elisabeth
Published: July 2007

Coordination Chemistry of rr‐Bonded Cyclopentadienyl Chalcogeno Ethers, I. ‐ Chelate Complexes of Pentakis(methylthio)cymantrene with Metal Carbonyls

[C5(SMe)5]Mn(CO)3 (1) reacts with W(CO)5(THF), Mo(CO)4(πC7H8), Cr(CO)3(NCMe)3, and Re(CO)4(π‐C3H5)/HBF4 to yield the monochelate complexes [[C5(SMe)5]Mn(C0)3][M(CO)4] (M = W: 2; M = Mo: 3) and the dichelate complexes [[C5(SMe)5]Mn(CO)3][M(C0)4]2 (M = W: 4; M = Cr: 5; M = Re⊕ BFF4⊖ : 6). The reaction with Mo(CO)3(p‐xylene) in THF leads via unstable intermediates, which contain coordinated THF, to a mixture of 3 and [[C5(SMe)5]Mn(CO)3][Mo(CO)4]2 (7). The structures of 3 and 4 in the crystal have been determined by X‐ray diffraction methods.
Beiträge zur Chemie des Phosphors, 206. Über die cyclische Silaphosphane (tBuSi)4P2l6, (t/BuSiP)4H2Cl2 und (tBuSiP)4HCl – Vorstufen des Silaphosphacubans (tBuSiP)4
Authors: Baudler Marianne , Scholz Guido
Published: July 2007

Contributions to the Chemistry of Phosphorus, 206. ‐ The Cyclic Silaphosphanes (tBuSi)4P2Cl6, (tBuSiP)4H2Cl2, and (tBuSiP)4HC1 ‐ Precursors of the Silaphosphacubane (tBuSiP)4

The reaction of tBuSiCl3 with LiAl(PH2)4 yields the silaphosphacubane 2. Besides the compounds 1,3, and 4, which were already identified, three additional silaphosphanes (tBuSi)4‐P2Cl6 (5), (tBuSiP)4H2Cl2 (6), and (tBuSiP)4HCl (7) have been found representing precursors of 2. According to NMR spectroscopic investigations, 5, is a derivative of 1,3‐diphospha‐2,4‐disiletane, whereas 6 and 7 exhibit a structure analogous to norcubane and secocubane, respectively. The compounds 3 – 7 reveal the reaction pathway from 1 to 2.
Pyrazole‐Organoboranes, VII. Addition Complexes of Pyrazolylboranes
Authors: Yalpani Mohamed , Boese Roland , Köster Roland
Published: July 2007

The monomeric 9‐pyrazolyl‐9‐borabicyclo[3.3.1]nonanes react in situ with either excess of 9H‐9‐BBN or of some pyrazoles to form the 2:1 or 1:2 adducts 1–5 or 7–11, respectively. Spectroscopic data (NMR, IR) suggest and the solid state structure of 4 confirms the presence of a central heterocycle in complexes of the type 1–5. In solutions of 7–11 NMR data at room temperature indicate a rapid exchange of the four nitrogen atoms of the two pyrazole rings at the boron atom of the 9‐BBN moiety. In the solid state (X‐ray structure of 8) intermolecular N–H ⃛N bonds lead to dimeric structures. In the almost insoluble adduct 7 a polymeric structure is suggested. Pyrazoles with large substituents, e. g. 3,5‐diphenylpyrazole (P2Pz) give addition complexes of the type 1–5 only in solution in equilibrium with the corresponding monomeric species (11B NMR) and none of the type 7–11.