bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthese und Photolyse von 1,4,4‐Trialkyl ‐4,5‐dihydro‐5‐imino ‐1H‐1,2,3‐triazolen. — Regio‐ und diastereoselektive Bildung von (Z)‐Aziridiniminen
Authors: Quast Helmut , Regnat Dieter
Published: July 2007

Synthesis and Photolysis of 1,4,4‐Trialkyl‐4,5‐dihydro‐5‐imino‐1H‐1,2,3‐triazoles. — Regio‐ and Diastereoselective Formation of (Z)‐Aziridinimines

The novel 5‐iminodihydro‐1,2,3‐triazoles 14 are synthesized from the 5‐isopropylidenedihydrotetrazole 11 through a ring transformation involving cycloaddition and cycloreversion of alkyl azides 12. Thus, [3 + 21 cycloaddition of 11 and 12 pro‐ duces high yields of the spiro compounds 13. On thermolysis at 120‐ 130°C, the latter undergo clean [3 + 2] cycloreversion into methyl a i d e (12a) and the iminodihydro‐1,2,3‐triazoles 14, which exist as mixtures of diastereomers, e.g. (E)‐/(Z)‐14a = 955, or as a single stereoisomer (E)‐14c. When toluene solutions of 14 are irradiated (≥ 1 280 mm) at ‐ 60°C, the configuration of the products is under kinetic control. Irradiation of 14a affords a quantitative yield of the aziridinimines (E)‐and (Z)‐15a (11:89) besides molecular nitrogen. In order to allow the distinction between the least‐motion and the non‐least‐motion path of product formation, the photolysis of iminodihydro‐1,2,3‐triazoles is studied which are labelled at N‐1 by a deuterated methyl group (14b) or a neopentyl group (14c). Neither photolysis (λ ≥280 nm) nor heating to 120 to 130°C induces any scrambling of the alkyl groups attached to N‐1 and the exocyclic nitrogen atom of 14b and c. The major product from (E)‐/(Z)‐14b (84%) is formed by the non‐least‐motion path leading diastereoselectively to (Z)‐15 b, while the least‐motion products (E)‐ and (Z)‐17b (16%) exhibit a diastereo‐meric ratio of 3: 1. Very similar results are obtained on photolysis of (E)‐14c, except that the least‐motion product (15%) arises only in a single configuration [(E)‐l7c]. In the non‐least‐motion products (Z)‐15b, c, the geometry of the MeN‐CN???R group, fixed by the ring in 14b, c, is completely retained. Therefore, the (Z) diastereoselectivity is interpreted in terms of a one‐bond cleavage leading to diazenyl‐1,3‐diazaallyl diradicals 22 having lifetimes too short for changes of their configuration which is determined by the structure of the precursor.
Wasserstoffübertragungen, 16. Freie 1‐Phenylallyl‐Kationen bei der Aromatisierung von Dihydronaphthalinen mit Triphenylmethyl‐tetrafluoroborat
Authors: Giese Georg , Heesing Albert
Published: July 2007

Free 1‐Phenylallyl Cations in the Aromatisation of Dihydronaphthalenes by Triphenylmethyl Tetrafluoroborate

The aromatisation of 1,2‐ and 1,4‐dihydronaphthalenes by trityl cations proceeds by a common intermediate, the 1‐phenylallyl cation 4 of sufficient lifetime to allow for both side reactions and loss of stereoselectivity. The primary hydride abstraction occurs with moderate tunneling participation and in a linear geometry of the three participating atoms as shown by the temperature dependence of the primary isotope effect.
Stereoselective synthesis of alcohols, XXXIV. Towards an understanding of cram/anti‐cram selectivity on addition of crotylboronates to α‐methylbutyraldehyde
Authors: Hoffmann Reinhard W. , Brinkmann Heinrich , Frenking Gernot
Published: July 2007

The diastereoselectivity on addition of γ‐substituted allylboronates to α‐methylbutyraldehyde (9) did not depend on the size of the substitutent in the reagent, but only on its location in the Z or E position. This finding required a reinterpretation of the reasons for the attendant reversal in diastereoselectivity. New hypotheses are presented based on force‐field calculations on model structures for the transition states.
Radical ions and photochemical charge transfer phenomena, 28. 1,1′‐Binaphthalene‐2,2′‐dicarbonitrile in photochemically sensitized enantiodifferentiating isomerizations
Authors: Vondenhof Martin , Mattay Jochen
Published: July 2007

The synthesis of optically active (+)‐ and (‐)‐1,1′‐binaphthalene‐2,2′‐dicarbonitrile (1) is described as well as its application in photoinduced electron transfer (PET) dimerizations and isomerizations.
Derivate des Borols, XVII {η5‐[1‐(Diisopropylamino)borol]}metall‐Komplexe: Synthesen, Protonierung, interne Rotation
Authors: Herberich Gerhard E. , Negele Michael , Ohst Holger
Published: July 2007

Derivatives of Borole, XVII1). – {η5‐[1‐(Diisopropylamino)borole]}metal Complexes: Syntheses, Protonation, Internal Rotation

New complexes M(CO)4L (M = Cr, W), cis‐M(CO)2L2 [M = Mo, W (not isolated)], and (COD)NiL have been prepared from the Diels‐Alder dimer L2, where L is 1‐(diisopropylamino)borole, C4H4BNiPr2. Complexes of L can be protonated at the nitrogen atom to give stable salts such as [Cr(CO)4(LH)]BF4, [Fe(CO)3(LH)]BF4, [(C6Me6)Ru(LH)]BF4, and [CpCo(LH)]BF4; B — N bond dissociation is not observed. Barriers to internal rotation have been determined by variable temperature NMR spectroscopy for Cr(CO)4L, (COD)NiL, and NiL2. Three processes have been identified: rotation of the NiPr2 group around the B — N bond, gear‐mesh rotation of the isopropyl groups around the C — N bonds, and rotation of L with respect to the counter ligands.
(Perfluoralkyl)(dimethylamino)sulfonium‐hexafluoroarsenate
Authors: Erhart Markus , Rüdiger  , Pauer Frank , Stalke Dietmar , Sheldrick George M.
Published: July 2007

(Perfluoroalkyl)(dimethylamino)sulfonium Hexafluoroarsenates

MeN = S(CF3)2 (5) is alkylated by Me3O⊕ AsF⊖6 to Me2N‐S(CF3)⊕2 AsF⊖6 (4). From 5 and MeOSO⊕ AsF⊖6 (6) MeOS(O)‐N(Me)S(CF3)⊕2 AsF⊖6 (7) is formed as a relatively stable primary product. Decomposition of 7 gives the expected 4 only in poor yield. Nucleophilic substitution of the sulfur‐bonded fluorine in CF3SF⊕2 AsF⊖6 (8) by Me3SiNMe2 yields CF3S(NMe2)⊕2 AsF⊖6 (9). Similarly, (CF3)2CFSF⊕2 AsF⊖6 (10) reacts with dimethyl(trimethylsilyl)amine to give (CF3)2CFS(NMe2)⊕2 AsF⊖6 (11). The structures of 4 and 9 are elucidated by X‐ray analyses, and the influence of the substituents on the bonding is discussed.
Lithiated 5,6‐Dihydro‐4H‐1,2‐oxazines: Synthesis, Highly Diastereoselective Reactions with Electrophiles, and Subsequent Transformations
Authors: Reißig Hans‐Ulrich , Hippeli Claudia
Published: July 2007

The 6‐(trimethylsilyl)methyl‐substituted 1,2‐oxazine 1 can smoothly be deprotonated with n‐butyllithium at C‐4 to give a lithiated species which reacts with a variety of electrophiles to provide the new 1,2‐oxazines 5 – 16 in good yields. Besides the preparative aspect of these transformations, the high stereoselectivity of many reactions is also interesting from a mechanistic point of view. By deprotonation of the 4‐deuterated compound 5a it has been proven that n‐butyllithium removes exclusively the proton (or deuteron) cis to the 6‐CH2SiMe3 group. Also, in most cases the reaction of lithiated 1 with electrophiles occurs with overall retention of configuration to afford preferentially cis‐1,2‐oxazines (series a). A mechanistic proposal for this highly stereoselective deprotonation process, which seems to be governed by the 1,2‐oxazine oxygen, is discussed including a comparison with a recently reported ab initio calculation dealing with oxime ethers. Similar deprotonation/substitution reactions are described for 1,2‐oxazines 14, 2, 3, and 4. Possibly due to a differing carbanion structure a deviating behavior is observed in some cases. Several acidinduced and reductive ring‐opening reactions of 1, 6a, 8a, and 14a demonstrate the potential of 4‐substituted 1,2‐oxazines for the stereoselective synthesis of polyfunctionalized compounds.
Stereospezifische Umwandlungen des (+)‐2‐ und (+)‐3‐Carens in optisch aktive Siebenring‐Systeme
Authors: Eilbracht Peter , Winkels Irmgard
Published: July 2007

Stereospecific Conversions of (+)‐2‐ and (+)‐3‐Carene into Optically Active Seven‐Membered Ring Systems

The reactions of (+)‐2‐carene (6b) and (+)‐3‐carene (15) with iron carbonyls are studied under various conditions. Besides double bond isomerization and interconversion of the two isomeric hydrocarbons, at least two different modes of ring opening leading to six‐ and seven‐membered ring products are observed. Under mild conditions the primary ring opening complex 7b is isolated without loss of sterical information. Carbonylation of 7b under various conditions yields optically active cycloheptane systems 18, 19, and 20 or the bicyclic systems 9b and 10b.
Synthesis of 2,2,5,5‐Tetramethylcyclopentanecarboxylic Acid – A Building Block of an Amino Acid Based Sweetener
Authors: Mayr Herbert , Heilmann Werner , Bäuml Englbert , Vorbrüggen Helmut
Published: July 2007

The title compound 2 is synthesized in three steps from readily available 2,5‐dichloro‐2,5‐dimethylhexane (8) and vinylidene chloride (9). The key steps are carbocationic additon and cyclization reactions.
Neue O6‐Makrocyclen mit 2,2‐Bis(2‐furyl)propan‐Einheiten
Authors: Gast Achim , Breitmaier Eberhard
Published: July 2007

New O6 Macrocycles with 2,2‐Bis(2‐furyl)propane Units

The macrocycles 3a and 6 are prepared in 29 and 16% yield by cyclization of dilithiated 2,2‐bis(2‐furyl)propane (1) and 2,5‐bis[1‐(2‐furyl) 1‐methylethyl]furan (5), respectively, with ethyl N,N‐dimethylcarbamate (2).
Kurzmitteilung / Short Communication. Acid‐Catalyzed and Lewis Acid‐Promoted Synthesis of 6‐Hydroxybicyclo[4.3.0]nonan‐3‐ones
Authors: Schinzer Dieter , Ruppelt Martin
Published: July 2007

3a‐Hydroxy‐6‐hydrindanones of type 10 and 11 can be obtained by acid‐catalyzed or Lewis acid‐promoted cyclization reactions of ene‐ketals of type 6 and 7. The compounds described are interesting building blocks for biologically active heart glycosides.
Die Kristallstrukturen von Kalium‐, Rubidium‐ und Cäsium‐trifluororthocarbonat mit einer Bemerkung zum Bariumsulfat‐Typ1
Authors: Arlt Joachim , Jansen Martin
Published: July 2007

The Crystal Structures of Potassium, Rubidium, and Cesium Trifluororthocarbonate and a Remark Concerning the Barium Sulfate Type1)

Crystals of potassium, rubidium, and cesium trifluororthocarbonate (9a, 9b, and 9c) have been grown by Ostwald ripening in CH3CN applying a COF2 pressure of 3 bar. According to X‐ray single‐crystal structure analysis, 9a, 9b, and 9c belong to the baryte‐structure family with an pseudotetrahedral anion being dynamically disordered at room temperature. All of the title compounds undergo a phase transition into a monoclinic, completely ordered low‐temperature form, which has been refined for 9c. The C – O bond seems to be shortened by polar interactions. The results obtained with 9a, 9b, and 9c at room temperature indicate that the type of disorder found in 9 might be generally present in baryte‐type compounds.
Addition von Phosphor‐Nucleophilen an Benzothiet
Authors: Eckes Heinz‐Ludwig , Niedermann Hans‐Peter , Meier Herbert
Published: July 2007

Addition Reactions of Phosphorus Nucleophiles to Benzothiete

Trialkyl phosphites 4 add to the o‐quinoid form 2 of benzothiete (1) to yield the phosphonates 6. An intermolecular migration of an alkyl group from oxygen to sulfur is the most important feature of this transformation. The rearrangement – related to the Arbuzov reaction – can be avoided in a two‐step process by the subsequent action of PCl3 and alcohol; thus the phosphonates 10 are generated. Analogous to 2 → 6, dimethyl phenylphosphinate (11) furnishes 13. In contrast, the cyclic esters 14a–d form 2:1 adducts, namely the 12‐ to 15‐membered heterocyclic compounds 17a – d. An intramolecular rearrangement in a 1:1 adduct is only observed for the 1,3,2‐dioxaphosphepine 14e, a benzylic system which allows an SN1 process generating the 1,6,2‐oxathiaphosphecine 18e. A similar rearrangement at a tertiary carbon center is prevented by the competitive addition of water (1 + 14f → 20).
Notizen/Notes Synthesis of 1‐Phenyl‐1,2‐ and 4‐Phenyl‐1,5‐dihydropentalenes
Authors: Griesbeck Axel G.
Published: July 2007

An efficient one‐pot synthesis of 3‐substituted 1‐phenyl‐1,2‐dihydropentalenes from α,β‐unsaturated ketones is described. These compounds can be rearranged to their 1,5‐dihydro isomers using different methods such as acid catalysis and vacuum‐flash thermolysis or by chromatography on alumina.
[(BH2)6S4]2−, [(BH2)6Se4]2−: neue Chalcogenoborwasserstoff‐Anionen mit Adamantanstruktur
Authors: Binder Herbert , Loos Helge , Dermentzis Konstantinos , Borrmann Horst , Simon Arndt
Published: July 2007

[(BH6)2]S4]2−, [(BH2)Se4]2−: New Chalcogenoboron Hydride Anions with Adamantane Structure

The reaction of THF·BH3/NaBH4 (2: 1) with H2S produces Na[H3B‐μ2‐S(B2H5)] (5) with hydrogen evolution. 5 reacts with an excess of H2S to give Na2[(BH2)6S4] (3a), which is also formed in the reaction of THF·BH3 with NaSH or anhydrous Na2S. These reactions proceed via 5 and the intermediates 7 or 8 by loss of BH–4 and cyclization. The analogous compound Na2[(BH2)6Se4] (4a) is obtained by the reaction of elemental selenium with NaBH4 (1:1) in triglyme. The primary product is Na2[H3B–Se–Se–BH3] (9). Treatment of 9 at 100 – 110°C yields 4a and polymers, 3a and 4a react with CsBr to form the crystalline compounds Cs2[(BH2)6Se4]·CsBr (3b) and Cs2–[(BH2)6Se4]·CsBr (4b), characterized by X‐ray structure determinations. The anions of 3b and 4b consist of an adamantane skeleton. The Br− ion is octahedrally coordinated by Cs+ ions. The Cs6Br octahedra share faces to form columns along the hexagonal c axis. The crystal structures of the isotypic compounds 3b and 4b are closely related to the structure of CsNiCl3.
Stereoselective Synthesis of Alcohols, XXXVII. Origins of Stereoselectivity in Reactions of α‐Substituted Allylboronates with Aldehydes
Authors: Hoffmann Reinhard W. , Jens Wolff J.
Published: July 2007

Rate constants for the addition of α‐substituted allylboronates 4 (XH, Cl, Br, OCH3, SCH3] to aldehydes have been measured. The results have been used to differentiate between different models that have been advanced to account for the high proportion of (Z)‐configurated homoallyl alcohols 5 formed in allylboration reactions. Attempts have been made in this context to detect ate‐complex formation between benzylboronates and aldehydes.
β‐Aminoketone als Schlüsselverbindungen zur Synthese von Pyridinen: Ein neuartiger, leistungsfähiger Zugang zu kondensierten Bi‐ und Terpyridinen
Authors: Westerwelle Ulrich , Esser Achim , Risch Nikolaus
Published: July 2007

β‐Amino Ketones as Key Intermediates in the Synthesis of Pyridines: A Novel and Efficient Route to Annelated Bi‐ and Terpyridines

The hydrochlorides of β‐amino ketones 1a – e (Mannich bases) are easily obtained starting compounds for a novel synthesis of pyridines. Condensation with the heteroaromatic ketones 8, 9, and 10 yields 5,6‐dihydro‐1,10‐phenanthrolines 3a – d, 13 and 4,5‐diazafluorenes 4a – d, which have not yet been described in literature. Symmetrical terpyridines 3e, 4e are formed in a one‐step reaction of 8, 9 with dimethylmethylenammonium chloride in the presence of an ammonia source.
Reactions of Organic Anions, 177. Vicarious Nucleophilic Substitution of Hydrogen, Bisannulation and Competitive Reactions of α‐Haloalkyl Carbanions with Bicyclic Azaaromatic Compounds
Authors: Makosza Mieczyslaw , Golinski Jerzy , Ostrowski Stanislaw , Sahasrabudhe Arvind B. , Rykowski Andrzej
Published: July 2007

Carbanions of α‐haloalkyl aryl sulfones, sulfonates, and sulfonamides react with bicyclic heteroaromatic compounds (quinoxalines, naphthyridines, and 5‐azaquinoxalines) according to two general pathways: vicarious nucleophilic substitution of hydrogen and/or bisannulation. In some cases other competitive reactions such as SNAr are observed. Factors governing the direction of these reactions are discussed in terms of the charge distribution in the anionic σ adducts and the reaction conditions.
Struktur und Reaktivität von isoanellierten heterocyclischen Systemen mit 4n;‐π‐ und (4n + 2)‐π‐Elektronen, XVIII. Benzo[c]thiophene mit symmetrischer Struktur: Modifizierte und optimierte Herstellung nach der S‐Oxid‐Route
Authors: Kreher Richard P. , Kalischko Jürgen
Published: July 2007

Structure and Reactivity of Isoannullated Heterocyclic Systems with 4n;‐π and (4n + 2)‐π Electrons, XVIII. – Benzo[c]thiophenes with Symmetric Structure: Modified and Optimized Preparation by the S‐Oxide Route

Benzo[c]thiophenes (15) with symmetric structure have been prepared efficiently from 1,3‐dihydrobenzo[c]thiophene 2‐oxides (9) by reaction with aluminium oxide, by O‐acylation with trifluoroacetic anhydride, or O‐alkylation with methyl trifluoromethanesulfonate. The aromatization of the S‐oxides 9 is achieved by O‐functionalization, subsequent elimination, and consecutive deprotonation.
Zur Reaktivität des Silaethens Me2SiC(SiMe3)2: Stereospezifität der Diels‐Alder‐Reaktionen mit Hexadienen1,2
Authors: Wiberg Nils , Fischer Gerd , Wagner Susanne
Published: July 2007

On the Reactivity of Silaethene Me2SiC(SiMe3)2: Stereospecificity of Diels‐Alder Reactions with Hexadienes1,2)

[4 + 2] Cycloaddition of trans,trans;‐ and cis,trans;‐2,4‐hexadiene to silaethene Me2SiC(SiMe3)2 (1) takes place stereo‐specifically in one step with formation of 3 and 4, respectively. In addition, both reactions lead to ene products 5, 6.
Großflächige, starre Makrocyclen aus 1,4‐Diphenylbutadiin‐Bauteilen
Authors: Kadei Klaus , Vögtle Fritz
Published: July 2007

Flat and Rigid Macrocycles Based on 1,4‐Diphenylbutadiyne Units

[1.1](3,3′)‐1,4‐Diphenylbutadiynophanes of type Ia,b (e.g. 1 – 4) are obtained by coupling the diethynyl derivatives 18 – 21 by means of CuCl/CuCl2. The properties of 1 – 4 (UV, NMR, charge transfer) are compared to 1,4‐diphenylbutadiyne. In contrast to 1,4‐diphenylbutadiyne, 1 and 2 (type Ia) are highmelting, colorless solids, which are sparingly soluble in common organic solvents. The better soluble compounds 3 and 4 (type Ib) are also prepared. The macrocycles 1 – 4 consist of two “isolated” 1,4‐diphenylbutadiyne units. In contrast to 1,4‐diphenylbutadiyne they do not seem to form charge‐transfer complexes with tetracyanoethene (TCNE) in CH2Cl2.
Mehrfachbindungen zwischen Hauptgruppenelementen und übergangsmetallen, XC. Selektive Bildung von Alkylrheniumoxiden aus Glykolat‐Komplexen
Authors: Herrmann Wolfgang A. , Watzlowik Petra , Kiprof Paul
Published: July 2007

Multiple Bonds between Main Group Elements and Transition Metals, XC. – Selective Formation of Alkylrhenium Oxides from Glycolato Complexes

Alkylrhenium(VII) and alkylrhenium(VI) oxides, previously not known or hardly accessible, are selectively synthesized from glycolato(O,O') complexes. These are formed in easy terms from methyltrioxorhenium(VII) and aliphatic vic‐diols, e.g. glycol and pinacol, by both redoxneutral and reductive condensation reactions (ReVII → ReVI), respectively. The dinuclear glycolato complex 3 exhibits a centrosymmetric molecular structure with an octahedral core geometry around the metal atom. The mononuclear Re(VII) compound 2 forms a distorted trigonal bipyramidal structure (single crystal X‐ray diffraction).
Dicarbonylgold(I)‐hexafluorouranat(VI), Au(CO)2UF6
Authors: Adelhelm Manfred , Bacher Walter , Höhn Ernst Gerhard , Jacob Eberhard
Published: July 2007

Dicarbonylgold(I) Hexafluorouranate(VI), Au(CO)2UF6

Elemental gold reacts with UF6 in the presence of CO in anhydrous HF to form quantitatively a complex compound, whose IR spectra and analysis are consistent with the formula [Au(CO)2][UF6].
Bidentate Phosphines of Heteroarenes: 4,6‐Bis(diphenylphosphino)dibenzofuran and 4,6‐Bis(diphenylphosphino)dibenzothiophene
Authors: Haenel Matthias W. , Jakubik Dieter , Rothenberger Eveline , Schroth Gerhard
Published: July 2007

Twofold lithiation of dibenzofuran (6) and dibenzothiophene (12) with n‐butyllithium/N,N,N′,N′‐tetramethylethylenediamine (TMEDA) in n‐hexane or n‐pentane followed by the reaction with chlorodiphenylphosphine yielded the title compounds 4 and 5, respectively, The monophosphines 4‐(diphenylphosphino)dibenzofuran (11) and 4‐(diphenylphosphino)dibenzothiophene (15) were obtained analogously via the monolithium compounds 9 and 14 of the heteroarenes. In the case of dibenzofuran (6), it was shown that mono‐ and dilithiation is controlled by temperature.
Alkylations of (R,R)‐2‐t‐Butyl‐6‐methyl‐1,3‐dioxan‐4‐ones which are not Possible with Lithium Amides may be Achieved with a Schwesinger P4 Base
Authors: Pietzonka Thomas , Seebach Dieter
Published: July 2007

Enolates A of the dioxanones specified in the title, when generated with lithium amide bases, can only be alkylated with highly reactive electrophiles, and only once. With Schwesinger's t‐Bu‐P 4 base (a very strong, so‐called neutral base, containing 4P and 13N atoms capable of bearing a positive charge in the conjugate P4H+ cation) the dioxanone 1 can be doubly alkylated even with iodobutane (products 16, 17). The 5,6‐dimethyl‐ and 5‐benzyl‐6‐methyldioxanone 2 and 3 can be alkylated diastereoselectively with the formation of quaternary centers at C(5) (products 4, 8—14). In one case, the configuration of the product 4 obtained was determined by conversion to a β‐lactone 6 and an olefin 7 (a previous assignment had to be revised). Even the 2,5,6,6‐tetraalkyl‐substituted dioxanone 19 could be further alkylated (→ 20 + 21). Five of the new alkylation products were hydrolyzed to the parent 3‐hydroxy‐carboxylic acids 5, 22 — 25. The enormous reactivities achieved with the inherently labile enolates and the P411+ counterions are discussed.
Große Übergangsmetallcluster, VIII. Wie verhalten sich trägergestützte Rh55‐Cluster im Hydroformylierungsprozeß?
Authors: Schmid Günter , Küpper Rolf , Hess Holger , Malm Jan‐Olle , Bovin Jan‐Olov
Published: July 2007

Large Transition Metal Clusters, VIII. ‐ How Do Supported Rh55Clusters Behave in the Hydroformylation Process?

Two‐shell rhodium clusters of the type Rh55L12Clx[L = P(tBu)3, x = 20; L = PPh3, x = 6] can be anchored on TiO2and Na‐ Y‐zeolite. High resolution transmission electron microscopy (HRTEM), BET, and DSC investigations prove that the clusters, about 20 Å in diameter, are fixed on the entrances of the micropores of the supports. The supported clusters catalyze the hydroformylation of ethene and propene variously. During the hydroformylation of ethene without a solvent or in aqueous suspension the catalyst is inactive after a few cycles. However, there is no loss of activity even after 27 experiments if propene is hydroformylated in an aqueous medium.
Zweifache Borylierung von Benzolderivaten mit (Diisoalkylamino)boradiyl‐Einheiten
Authors: Meller Anton , Böker Christian , Seebold Uwe , Bromm Dietmar , Maringgele Walter , Heine Andreas , Herbst‐Irmer Regine , Pohl Ehmke , Stalke Dietmar , Noltemeyer Mathias , Sheldrick George M.
Published: July 2007

Twofold Borylation of Benzene Derivatives with (Diisoalkylamino)boradiyl Units

The reaction of subvalent boron species generated by the defluorination of difluoro(diorganylamino)borane with Na/K alloy in the presence of 1,4‐disubstituted benzene derivatives leads to products which contain two (diorganylamino)boradiyl units and two remaining double bonds which are located on the substituted C atoms. Compounds 5 to 8 exhibit structures based on a 2,8‐diborabicyclo[3,2,1]octa‐3,6‐diene skeleton while 9 shows a skeleton with a 1,3a,4,6a‐tetrahydroborolo[3,2‐b]borole structure. The latter structure corresponds to that of 1 obtained in the same reaction with benzene. The compounds are characterized by elemental analyses and spectroscopically [MS, NMR (1H, 11B, 13C, 15N, 19F, 29Si)]. X‐ray structure analyses are presented for 1, 6, 7, 8, and 9.
Vom Lithium‐Derivat des Aminodi‐tert‐butylfluorsilans zu Cyclodi‐, ‐tri‐ und ‐tetrasilazanen
Authors: Kottke Thomas , Klingebiel Uwe , Noltemeyer Mathias , Pieper Ursula , Walter Simone , Stalke Dietmar
Published: July 2007

Aminodi‐tert‐butylfluorosilane (CMe3)2 SiFNH2 reacts with BuLi in hexane to give the lithium derivative 1, which crystallizes from TMEDA with formation of the dimer 2 [(CMe3)2SiFNHLi(TMEDA)]2. LiF elimination from 1 or 2 leads to cyclodi‐ (3), ‐tri‐ (4), and ‐tetrasilazane (6). 3 is the main product of the LiF elimination from 2 and 4 the main product resulting from 1. Cyclotetrasilazane 6 is the most planar eightmembered Si‐N ring known so far. Chain compound 5 is the direct precursor of 4. The crystal structures of 2, 5, and 6 are described.

From the Lithium Derivative of Amino‐di‐tert‐butylfluorosilane to Cyclodi‐, ‐tri‐, and ‐tetrasilazanes
Beiträge zur Chemie des Bors, 209. 1,2‐Diboran(4)diyl‐ und 1,3‐Triboran(5)diyl‐ditosylate und ‐bis(triflate): Elektronenpräzise Polyboran‐Derivate mit aktiven Austrittsgruppen
Authors: Nöth Heinrich , Wagner Matthias
Published: July 2007

Contributions to the Chemistry of Boron, 209. — 1,2‐Diborane(4)diyl and 1,3‐Triborane(5)diyl Ditosylate and Bis(triflate): Electron‐Precise Polyborane Derivatives with Active Leaving Groups

Introduction of the tosylate or triflate group into dimethylamino polyboranes gives electron‐precise polyborane derivatives of high reactivity. Five representatives 1 – 4 of these types of compounds are reported. The RSO3 groups strengthen the B – N bond while they are good leaving groups as shown by alkylation reactions when using LiR compounds. The X‐ray structure of B2(NMe2)2(tos)2 (1) reveals C2 symmetry, and this also holds for B2(NMe2)2(CCPh)2 (7). While the two BNO planes in 1 include an angle of 80.8°, the two BNC planes in 7 are closer to orthogonality (84.6°). In contrast, the bis(9‐fluorenyl)diborane 10 reveals different structures in solution and the solid state. Experimental results correspond fairly well with MNDO calculations on model compounds B2(NH2)2X2, particularly with B – B and B – N bond lengths and conformations. They also suggest that nucleophilic substitutions at 1 – 4 may proceed by a dissoziative process.
Zur Reaktivität des Silaethens Me2Si = C(SiMe3)2: Relative Geschwindigkeiten der Diels‐Alder‐Reaktionen mit organischen Dienen1,2)
Authors: Wiberg Nils , Wagner Susanne , Fischer Gerd
Published: July 2007

On the Reactivity of the Silaethene Me2Si = C(SiMe3)2: Relative Rates of Diels‐Alder Reactions with Organic Dienes1,2)

[4 + 2] Cycloaddition of dienes to silaethene Me2Si = C(SiMe3)2 is accelerated in the directions: (i) butadiene < isoprene < CH2 = CR – CH = CH2 with R = CH2SiMe2CH‐ (SiMe3)2 (increase in electron donation of the diene substiuents), (ii) trans‐piperylene < 2,3‐dimethylbutadiene (DMB) < isoprene (decrease in steric hindrance of diene substituents), (iii) cis‐piperylene or cis,trans‐hexadiene < trans‐piperylene and trans,trans‐hexadiene (decrease in equilibrium concentration of the cisoid conformer).
Mehrstufige reversible Redoxsysteme, LVI. Kristallstruktur und Leitfähigkeiten der CT‐Komplexe TTF/2‐X‐5‐Me‐DCNQI (X = Cl, Br, I) aus Tetrathiafulvalen und 2‐Halogen‐N,N′‐dicyan‐5‐methyl‐1,4‐benzochinondiimin
Authors: Erk Peter , Hünig Siegfried , Klebe Gerhard , Krebs Martin , Schütz Jost Ulrich Von
Published: July 2007

Multi‐Step Redox Systems, LVI. – Crystal Structures and Conductivities of the CT Complexes TTF/2‐X‐5‐Me‐DCNQI (X = Cl, Br, I) from Tetrathiafulvalene and 2‐Halogeno‐N,N′‐dicyano‐5‐methyl‐1,4‐benzoquinone Diimine

In contrast to microcrystalline powders single crystals of the title complexes show low conductivities (&10; < sigma‐5 Scm‐1). These properties are based on a peculiar mixed stack arrangement of donor and acceptor molecules within the crystal lattice (space group P21/n).
1,3‐Cyclopentandiyle – Intermediate oder Übergangszustände?
Authors: Roth Wolfgang R. , Bauer F. , Breuckmann Rolf
Published: July 2007

1,3‐Cyclopentanediyls – Intermediates or Transition States?

The energy well of the singlet diradicals 4a and 6 has been determined by the oxygen trapping technique to be 2.7 and 1.9 kcal/mol, respectively. From the oxygen and temperature dependence of the trapping rate of the diradical 4a activation barriers of 2.2 and 4.9 kcal/mol have been derived for the mutual interconversion of the spin isomers with the triplet being the ground state.
Polyarylenes and Poly(arylenevinylene)s, V. Synthesis of Tetraalkyl‐Substituted Oligo(1,4‐naphthylene)s and Cyclization to Soluble Oligo(peri‐naphthylene)s2)
Authors: Koch Karl‐Heinz , Müllen Klaus
Published: July 2007

A homologous series of oligo(1,4‐naphthylene)s from the binaphthyl 6 to the sexinaphthylene derivative 10 were synthesized successively. The Pd(O)‐catalyzed reaction between aryl bromides and arylboronic acids was used as a coupling method. By appropriate choice of the stoichiometry, the method allowed isolation of the intermediates 20 and 21. Under the influence of potassium in 1,2‐dimethoxyethane the 1,4‐bridged naphthylenes 6—10 were partially cyclized to perylene and terrylene units. This anionic cyclization displayed a high regioselectivity. Complete cyclization to the oligorylenes 3b, 4b and 5b was achieved under the influence of AlCl3 and CuCl2 on the bichromophoric systems 24, 25 and 28. The synthetic sequence allowed substitution by tert‐butyl groups, so that the oligorylenes 2b, 3b, 4b and 5b were amenable to spectroscopic investigations. The trends in absorption maxima and fluorescence are discussed.
Stereoselective Synthesis of Alcohols, XXXVIII Stereoselective Total Synthesis of the Denticulatins
Authors: Andersen Marc W. , Hildebrandt Bernhard , Dahmann Georg , Hoffmann Reinhard W.
Published: July 2007

The total synthesis of the denticulatins 1 is described. Key feature is the efficient generation of the C‐1‐to‐C‐9 building block 37 by three consecutive stereoselective carbon ‐ carbon bond‐forming steps using chiral allylboronates. The C‐10‐to‐C‐17 building block was obtained by kinetic Sharpless resolution of an allylic alcohol followed by an Ireland‐Claisen rearrangement.
Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, LXXVII Synthese, Struktur und Reaktivität von Phosphametallacyclopropanen mit isolobalen ER‐ (E = N, P, As, Sb) und Fe(CO)4‐Bausteinen
Authors: Lindner Ekkehard , Heckmann Maria , Fawzi Riad , Hiller Wolfgang
Published: July 2007

Metal‐Containing Heterocycles: Preparation, Properties, Reactions, LXXVII. – Synthesis, Structure and Reactivity of Phosphametallacyclopropanes with Isolobal ER (E = N,P,As,Sb) and Fe(CO)4 Building Blocks

The phosphidometallates \documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ Li_2 \left\{ {\left[ M \right]\dddot - PPh_2 } \right\} $\end{document} {[M] = (η5‐C5H5)M‐(CO)2}, resulting from the metal hydride complexes H[M]PPh2H [M = Cr (1), Mo (2), W (3)] by reduction with nBuLi, react with the geminal dihalides RECl2 to give the three‐membered phosphametallacyclopropanes [ER = NC6F5 (M = Cr (1a), Mo (2a), W (3a)), PPh (M = Cr (1b), Mo (2b), W (3b)), PC6H11 (M = Cr (1c), Mo (2c), W (3c)), P‐tBu (M = Cr (1d), Mo (2d), W (3d)), P(2,4,6‐(tBu)3C6H2) (M = Cr (1e), Mo (2e), W (3e)), As(2,4,6‐(tBu)3C6H2) (M = Cr (1f), Mo (2f), W (3f)), Sb‐tBu (M = Cr (1g), Mo (2g))]. Reaction of Br2Fe(CO)4 with the corresponding dilithium compounds \documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ Li_2 \left\{ {\left[ M \right]\dddot - PPh_2 } \right\} $\end{document} affords the phosphido‐bridged heterodimetallic complexes . According to X‐ray structural analyses in 2a and 2f the P – E bond distances are shortened while the Mo – E bonds are significantly elongated compared to a single bond. (OC)5CrTHF is added to the Lewis basic E atom in 2b, 2d, and 2g with loss of THF to give P‐tBu (4d), Sb‐tBu (4g)]. By this reaction the antimony‐containing ring 2g is kinetically stabilized. Because of the low basicity of the N atom in 2a no addition was observed. The ring skeleton of 4b and 4g, undergoes no change by Cr(CO)5 coordination as shown by X‐ray structural analyses.
Synthesis and Molecular Structure of the Solvent‐Free [LiN(SiMe3)(2,6iPr2C6H3)]2 Dimer
Authors: Kennepohl Dietmar K. , Brooker Sally , Sheldrick George M. , Roesky Herbert W.
Published: July 2007

[LiN(SiMe3)Ar]2 (1, Ar = 2,6‐iPr2C6H3) is prepared by the reaction of HN(SiMe3)Ar with nBuLi in n‐hexane. This compound with an unusual structure contains a four‐membered [LiN]2 heterocycle with two solvent‐free two‐coordinate Li centers. Its molecular structure represents the first solid‐state X‐ray analysis of an uncomplexed [LiN]2 dimer.
Kohlenwasserstoffverbrückte Komplexe XX Nucleophile Addition von Carbonylmetallaten an kationische Hexadienyl‐, Cycloheptadienyl‐, Cycloheptadienyl‐ und Cyclooctadienyl‐Komplexe von Eisen und Ruthenium: Heterodimetall‐Komplexe mit η1:η4‐C6‐, ‐C7‐ und ‐C8‐Kohlenwasserstoffbrücken
Authors: Niemer Burkhard , Breimair Josef , Wagner Barbara , Polborn Kurt , Beck Wolfgang
Published: July 2007

Hydrocarbon‐Bridged Metal Complexes, XX. – Nucleophilic Addition of Carbonyl Metallates to Cationic Hexadienyl, Cyclohexadienyl, Cycloheptadienyl, and Cyclooctadienyl Complexes of Iron and Ruthium: Heterobimetallic Complexes with η1:η4, ‐C6, ‐C7, and ‐C8 Hydrocarbon Bridges

The addition of Re(CO)‐5, Mn(CO)‐5, and [(η5‐C5H5)W(CO)3]‐ to the cationic dienyl complexes [(η5‐dienyl)M(CO)3]+ (M = Fe, Ru; dienyl = hexadienyl, cyclohexadienyl, cycloheptadienyl, cyclooctadienyl, bicyclo[5.1.0]octadienyl) gives the heterobimetallic η1:η4‐hydrocarbon‐bridged complexes 1 – 4, 6, 7. In solution the initial nucleophilic adduct 2e of [(η5‐cyclo‐hexadienyl)Ru(CO)3]+ and [Re(CO)5]‐ rearranges to the complex 3, in which the Re(CO)5 group is bound to a sp2 carbon atom. By using Mn(CO)‐5 also the products of electron transfer between cation and anion have been observed. The crystal structures of (OC)3Fe(μ‐η4:η1‐hexadiene)Re(CO)5 (1), (OC)3Ru(μ‐η4:η1‐cyclohexadiene)Re(CO)5(3), (OC)3Fe(η4:η4‐C7H9—C7H9)Fe(CO)3 (5), (OC)3Ru(μ‐η4:η1‐cyclooctadiene)Re‐(CO)5 (6b), and of (OC)3Fe(η4:η1‐bicyclo[5.1.0]octadiene)‐Re(CO)5 (7) have been determined by X‐ray diffraction.
2,3‐Dioxo‐2,3‐dihydrofurane, 2 Vielseitige Synthese von 2,3‐Dioxo‐2,3‐dihydrofuranen und Alkylidenbutenoliden. – Kristall‐ und Molekülstruktur von 5‐(4‐Chlorphenyl)‐4‐methoxycarbonyl‐2,3‐dioxo‐2,3‐dihydrofuran
Authors: Saalfrank Rolf W. , Lutz Thomas , Hömer Bernd , Gündel Jürgen , Peters Karl , Schnering Hans Georg Von
Published: July 2007

2,3‐Dioxo‐2,3‐dihydrofurans, 2. – Versatile Synthesis of 2,3‐Dioxo‐2,3‐dihydrofurans and Alkylidenebutenolides. – Crystal and Molecular Structure of 5‐(4‐Chlorophenyl)‐4‐methoxycarbonyl‐2,3‐dioxo‐2,3‐dihydrofuran

Reaction of the 1,3‐dicarbonyl compounds 5a – f, containing at least one α‐hydrogen atom in R1 and/or R2, with oxalyl halides 2 in the presence of magnesium chloride yields regioand on the whole stereospecifically the previously unknown (Z)‐alkylidenebutenolides 7a – f. Similarly, the 4‐alkoxycarbonyl‐5‐aryl‐2,3‐dioxo‐2,3‐dihydrofurans 6g – p are obtained (X‐ray structure of 61) starting from 3‐aryl‐3‐oxo‐propanoates 5g – p. Correspondingly, malondiamides 8a, b, e, f react with oxalyl chloride (2a) to give the 2,3‐dioxo‐2,3‐dihydrofurans 9a,b and 11a,b. Having mono(alkyl/aryl)amino substituents in position 5, compounds 11a,b spontaneously tautomerize to give imino enols 12a,b. Hydrochlorides 10a,b are formed on treatment of malondiamides 8c,d with oxalyl chloride (2a). In the case of the β‐oxocarboxamides 13/14 the substituents at the amide nitrogen atom control the regiochemistry. Starting from 13 (R2 = Ph) and oxalyl chloride (2a), 4‐acetyl‐5‐diphenylamino‐2,3‐dioxo‐2,3‐dihydrofuran (15) is formed regiospecifically, whereas under the same conditions 13/14 (R2 = CH2Ph) afford 4‐dibenzylcarbamoyl‐5‐methyl/phenyl‐2,3‐dioxo‐2,3‐dihydrofurans 16/17. Furanone 16 spontaneously enolizes to give 4‐dibenzylcarbamoyl‐3‐hydroxy‐5‐methylene‐2(5H]‐furanone (18). Similarly, the N‐monosubstituted β‐oxocarboxamides 19a,b readily react regiospecifically with oxalyl chloride (2a) to give via the 2,3‐dioxo‐2,3‐dihydrofurans 20a,b the imino enols 21a,b.
Organische Synthesen mit Übergangsmetall‐Komplexen, 54 Cyclopentadiene aus 1‐Metalla‐1,3‐dienen und Alkinen durch Cyclisierung intermediärer 1‐Metalla‐1,3,5‐triene (Metall = Wolfram)
Authors: Aumann Rudolf , Heinen Heinrich , Dartmann Mechthild , Krebs Bernt
Published: July 2007

Organic Syntheses via Transition Metal Complexes, 54. — Cyclopentadienes from 1‐Metalla‐1,3‐dienes and Alkynes by Cyclization of Intermediate 1‐Metalla‐1,3,5‐trienes (Metal = Tungsten)

We report on first examples of the formation of cyclopentadienes from a 1‐metalla‐1,3‐diene LnM=C‐C=C [LnM = W(CO)5] and an alkyne in [3 + 2] cycloaddition multistep reactions. In a first step the alkyne Et2N‐C=C‐Me (2) adds to the 1‐metalla‐1,3‐diene (CO)5W = C(OEt)‐CH=CHPh (1b) to give 1‐metalla‐1,3,5‐trienes (CO)5W=C(NEt2)‐CMe=C(OEt)‐CH=CHPh (3b) and (CO)5W=C(OEt)‐CH=C(NEt2)‐CMe=CHPh (4b). In a second step 3b cyclizes to thecyclopentadiene complex 5, which has an η1 ylide‐type structure as established by an X‐ray analysis. Hydrolysis of 5 leads to the formation of a 3‐aminocyclopentenone 7. The 1‐metalla‐1,3,5‐triene 4b yields a cyclopentadiene complex 8. In contrast to 5 the carbon skeleton of 8 has a connectivity different from that of the C3 unit of the 1‐metalla‐1,3‐diene 1.
Sulfur Compounds, 144 Synthesis of Sulfur‐Rich Organic Polysulfanes Utilizing Titanocene Pentasulfide as a Sulfur‐Transfer Reagent
Authors: Steudel Ralf , Förster Stefan , Albertsen Jörg
Published: July 2007

Titanocene pentasulfide, Cp2TiS5 (1) reacts with Ph3CCl (4), C2H4(SCl)2 (6), and CH3C6H3(SCl)2 (9) to give the corresponding polysulfanes (Ph3C)5 (5), C2H4S7 (7), and CH3C6H3S7 (8) which have been characterized by NMR, mass, and Raman spectroscopy. By interconversion reactions the mentioned polysulfanes yield homologous molecules with up to 11 sulfur atoms which have been separated by reversed‐phase HPLC. Linear relationships between the capacity factor and the number of sulfur atoms in the molecule have been derived for each series, and retention indices have been calculated.
Epoxidation of Enol Silyl Ethers, Phosphates, Esters, and Lactones by Dimethyldioxirane
Authors: Adam Waldemar , Hadjiarapoglou Lazaros , Jäger Volker , Klicić Jasna , Seidel Bernhard , Wang Xiaoheng
Published: July 2007

The epoxides 2a–u (Table 1) of the enol silyl ethers 1a, b, enol phosphates 1c–k, and enol esters and lactones 11–u were prepared in excellent yields by epoxidation with isolated dimethyldioxirane (4) (as acetone solution). These labile epoxides (stable below 0°C) could be isolated in pure form and characterized spectroscopically (IR, 1H and 13C NMR). The derivatives 2p–u were sufficiently stable so that even C,H analyses were obtained. Warming up to room temperature led to rearrangement to the corresponding α‐oxy‐functionalized carbonyl products 3. Since epoxide 2c was sufficiently resistant towards hydrolysis, it could be prepared by the in situ method.
A Phosphine Complex of Bismuth(III): X‐ray Crystal Structure of [PMe3H][Bi2Br7(PMe3)2]
Authors: Clegg William , John Errington R. , Fisher George A. , Green Marjorie E. , Hockless David C. R. , Norman Nicholas C.
Published: July 2007

The reaction between BiBr3 and one equivalent of PMe3 in THF affords, after recrystallisation from MeCN/Et2O, yellow crystals of [PMe3H][Bi2Br7(PMe3)2]. 2 (MeCN) (1), which has been characterised by X‐ray crystallography. Compound 1 is the first reported bismuth‐phosphine complex and comprises a polymeric anion, the monomeric unit of which contains a planar Bi2Br6 core, each bismuth being further bonded to a PMe3 ligand and an additional bromide such that the bismuth resides in an octahedral coordination environment. The latter bromides form linear bridges between monomeric units; the phosphines are trans with respect to the Bi2 unit, with a Bi‐P distance of 2.762(3) A. The reaction between Bil3 and PEt3 in THF affords, after recrystallisation from MeCN/Et2O, orange crystals of [PEt4]4[Bi6I22] (3) which has also been characterised by X‐ray crystallography.
Cycloallene, 7 Ein Siebenringallen‐Dimer: Darstellung aus einem 7,7‐Dibromnorcaran‐Derivat und Thermolyse
Authors: Jelinek‐Fink Hans , Christl Manfred , Peters Eva‐Maria , Peters Karl , Schnering Hans Georg Von
Published: July 2007

Cycloallenes, 7. – A Seven‐Membered‐Ring Allene Dimer: Preparation from a 7,7‐Dibromonorcarane Derivative and Thermolysis

Prepared by addition of dibromocarbene to 1,2‐dihydro‐3‐phenylnaphthalene, the 7,7‐dibromonorcarane derivative 6 gave the tetra‐ and pentacyclic hydrocarbons 7 and 8, respectively, on treatment with n‐butyllithium. The formation of 8 is considered to proceed via the 1,2‐cycloheptadiene derivative 15, which undergoes a dimerisation with the tetramethyleneethane diradical 16 as intermediate. Diradical 16 is also believed to be the intermediate in the thermal rearrangements of 8 to the penta‐ and hexacyclic hydrocarbons 12 and 13 and of 12 to 13. The structures of 8 and 13 have been determined by X‐ray structure analyses. Of special interest is the unusual length (165 pm) of the C‐12a – C‐12b bond (C‐1 – C‐22 in Figure 1) in 8.
Synthese mittlerer und großer Ringe, XXX Regioselektive Thermolyse von Oligomethylen‐oxaquadricyclan‐dicarbonsäureestern zu 3,6‐Alkanooxepindicarbonsäureestern – Röntgenstrukturanalysen und semiempirische Rechnungen
Authors: Tochtermann Werner , Vogt Carola , Peters Eva‐Maria , Peters Karl , Schnering Hans Georg Von , Würthwein Ernst‐Ulrich
Published: July 2007

Synthesis of Medium and Large Rings, XXX1). – Regioselective Thermolysis of Oligomethylene Oxaquadricyclanedicar‐boxylic Esters to 3,6‐Alkanooxepinedicarboxylic Esters – X‐ray Structural Analyses and Semiempirical Calculations

X‐ray structural analyses and semiempirical calculations for the oxaquadricyclanes 1 – 3 are discussed. The regioselectivity observed for the thermolyses of 1 – 3 (exclusive formation of 3,6‐alkanooxepines 6) is in line with the assumption that preferential cleavage of the long C – C bonds between the donor and acceptor substituents of the cyclopropane rings determines the reaction course.
Synthesis and Reactivity of “Bismuthinidene” Compounds and the Formation of Bi1 Chelate Complexes
Authors: Davies Simon J. , Compton Neville A. , Huttner Gottfried , Zsolnai Laszlo , Garner Stephanie E.
Published: July 2007

Treatment of [Cp′Mn(CO)2THF] (Cp′C5H4Me) with BiCl3 at 20°C affords the “bismuthinidene” species [Cp′‐ (CO)2Mn]2BiCl (1b) and very small amounts of the “star‐type” compound [Cp′(CO)2Mn]3Bi2 (2). Higher yields of both compounds are obtained from the reaction of BiCl3 with [Na] [Cp′(CO)2MnSi(C6H5)3‐]. The molecular structure of 1b has been determined by an X‐ray diffraction study, which shows that the bismuth atom, having a trigonal‐planar coordination geometry, is bonded to two manganese atoms and one chlorine atom. There are weak interactions between the molecules of 1b in the solid state thus forming infinite spiral chains of “inidene” complexes. Compound 1b reacts with NaI to afford the iodine‐substituted species [Cp′(CO)2Mn]2BiI (3). Displacement of the chloride substituent from 1b by anionic chelating ligands AB− is also possible; 1b reacts with tropolonate, 8‐oxoquinolate, or 8‐mercaptoquinolate to form the bismuth(I) chelate compounds [CP′(CO)2Mn]Bi − AB (5a–c). The molecular structure of 5b has been determined by X‐ray crystallography which shows the bismuth atom in a pseudo trigonalbipyramidal geometry with the nitrogen atom lying above the plane defined by the two manganese and the oxygen atoms in an apical position. The molecular structure of 5c has also been determined, and although the numerical values are not very accurate, the coordination geometry of the bismuth atom is seen to be intermediate between pseudo trigonalbipyramidal and distorted tetrahedral. Abstraction of a chloride ligand from 1b by Me3SiOSO2CF3 affords the cationic cumulene‐type complex [Cp′(CO)2MnBiMn(CO)2Cp][CF3SO3] (6a). Dichloromethane solutions of 6a are not stable at room temperature but may be treated with 2,−2′‐bipyridine (bpy) to afford the stable adduct [{CP′(CO)2Mn}2Bi(bpy)][CF3SO3](7). The molecular structure of 7 has been determined by X‐ray analysis, and – similarly to 5c, although the numerical values are not very accurate – the overall geometry has been determined unequivocally. The bismuth atom is shown to have a distorted tetrahedral geometry, thus being ligated by two manganese atoms and the two nitrogen atoms of the bpy ligands.
A Versatile Synthesis of 1,4‐Dienes: Use of Vinyl Ethers as Vinyl Cation Equivalents
Authors: Ohm Stefan , Bäuml Englbert , Mayr Herbert
Published: July 2007

The α,β‐dibromo ethers 2, in situ generated from the vinyl ethers 1 and bromine, react with the allylsilanes 3 in the presence of ZnCl2 to give the β‐bromo ethers 4. Treatment of 4 with Na in diethyl ether yields 1,4‐dienes 5 in 62–79% overall yield.
Organoerdmetallkomplexe von d‐Block‐Elementen, III. Erste flüchtige Organogalliocobalt‐Verbindungen
Authors: Fischer Roland A. , Behm Joachim
Published: July 2007

Organo Group‐13 Metal Complexes of d‐Block Elements, III. — First Volatile Organogallio Cobalt Compounds

In non‐coordinating solvents, salt elimination between sodium tetracarbonylcobaltate and bulky alkylgallium chlorides yields almost quantitatively the novel volatile cobalt‐gallium complexes of formula (CO)4CoGaR2(L) [3a: R=CH2C(CH3)3; 3b: R=CH2Si(CH3)3; L=THF]. The synthesized compounds were identified by means of 1H‐, 13C‐, 31P‐NMR, MS, and infrared ν(CO) data. Additonal, 3a was characterized by an X‐ray single‐crystal analysis. The σ(Co–Ga) bond length is 257.8(3) pm. Those bonds are highly reactive and rapidly cleaved due to electrophilic or nucleophilic attack. 3a, b are used as canditates to generate intermetallic Co/Ga films by the procedure of low‐pressure MOCVD.
1λ5,3λ5‐Diphosphol‐Derivate aus Bis(diphenylphosphino)methan und Propargylbromiden
Authors: Schmidpeter Alfred , Stocker Johanna , Karaghiosoff Konstantin
Published: July 2007

1λ5,3λ5‐Diphosphole Derivatives from Bis(diphenylphosphino)methane and Propargyl Bromides

The two title reagents 2 and 3 form a five‐membered 1,3‐diphosphole ring by nucleophilic interaction of the two phosphino groups of 2 with the methylene carbon atom and the adjacent acetylenic carbon atom of 3. (Phosphinomethyl)propargylphosphonium, diphosphafulvenium and diphospholium bromides (4, 6, and 1) result and can be isolated from consecutive steps of this reaction. By hydrolysis the diphospholium rings of 1 and 6 are selectively opened at the PCP unit to yield four different isomeric (phosphinoylpropenyl)phosphonium bromides 8—11.
Die Kristallstrukturen von {Li3(12‐Krone‐4)2[HC(CN)2]3}, {Na(15‐Krone‐5)‐[HC(CN)2]} und {Na[N(nBu)4][HC(CN)2]2 · THF}
Authors: Hiller Wolfgang , Frey Stephanie , Strähle Joachim , Boche Gernot , Zarges Wolfgang , Harms Klaus , Marsch Michael , Wollert RenéA , Dehnicke Kurt
Published: July 2007

The Crystal Structures of {Li3(12‐crown‐4)2[HC(CN)2]3}, {Na(15‐crown‐5)[HC(CN)2]}, and {NaN(nBu)4[HC(CN)2]2 · THF}

The preparation and the crystal structures of the title compounds 1—3 are described. 1 forms a polymeric chain structure, in which one of the lithium ions is linked by Li…NCC(H)CN… bridges. The remaining lithium ions form (12‐crown‐4)Li[NCC(H)CN] units, which are coordinated by one of the nitrogen atoms of the dicyanomethanide ions with the lithium ions of the chain. 2 forms an ion pair, in which the sodium ion is coordinated by the five oxygen atoms of the crown ether molecule and by one nitrogen atom of the dicyanomethanide ion. 3 has a threedimensional network, in which the sodium ions are coordinated in a distorted tetrahedral manner by the nitrogen atoms of the dicyanomethanide ions. In the cavities of the network the tetrabutylammonium ions and the THF molecules are found.
Mehrfachbindungen zwischen Hauptgruppenelementen und übergangsmetallen, CII. Flüchtige MN4‐Metallkomplexe von Niob und Tantal mit Dimethylsilyl‐Substituenten
Authors: Herrmann Wolfgang A. , Huber Norbert W. , Härter Peter , Denk Michael , Dyckhoff Florian
Published: July 2007

Multiple Bonds between Main‐Group Elements and Transition Metals, CII[1]. — Volatile MN4 Metal Complexes of Niobium and Tantalum Containing Dimethylsilyl Substituents

Niobium and tantalum complexes 4a and 4b of formula (Me2SiH)N=M[N(SiHMe2)2]3 (a: M=Nb; b: M=Ta) are formed from lithium bis(dimethylsilyl)amide and either MOCl3 (2a,b) or MCl5 (3a,b). No β‐hydrogen decomposition of these compounds occurs under normal conditions.