bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthese von 1,7‐Diazaperylen
Authors: Naumann Christoph , Langhals Heinz 
Published: July 2007

Synthesis of 1.7‐DiazaperyleneThe hitherto unknown 1,7‐Diazaperylene (2) has been prepared in a five‐step synthesis from 1,5‐diaminoanthraquinone (3) by a Meerwein arylation reaction. Applications as a fluorescent dye are discussed.
1H‐CIDNP bei einer Insertionsreaktion von Dimethylsilylenen
Authors: Lehnig Manfred , Reininghaus Frank 
Published: July 2007

1H‐CIDNP During an Insertion Reaction of DimethylsilylenesDuring the reaction of photochemically generated silylenes Me2Si: with benzyl bromide, 1H‐CIDNP (chemically induced dynamic nuclear polarization) is observed in the radical abstraction‐recombination product PhCH2‐SiMe2Br formed from singlet states of Me2Si:.
Intramolekulare Cycloaddition von Nitronen
Authors: Aurich Hans Günter , Boutahar Mostafa , Köster Heiner , Möbus Klaus‐Dieter , Ruiz Luis 
Published: July 2007

Intramolecular Cycloaddition of NitronesNitrones 9 and 10, formed by treatment of the corresponding aldehydes with N‐substituted hydroxylamines, are converted into the cis fused bicyclic compounds 11 and 12, respectively. While this intramolecular cycloaddition as a rule occurs at room temperature, the formation of compounds 17/18 and/or 20/21 from the corresponding nitrones needs refluxing in toluene with exception of 17Ca. The N‐aryl‐substituted nitrones 14C/15C form dimers 22C/23C spontanously at room temperature. However, dimerization is reversible; thus 22/23C afford the bicyclic compounds 17/18 and/or 20/21 on heating in toluene via the corresponding nitrone intermediates. — Hydrogenation cleaves isoxazolidine ring of the bicyclic compounds. Thus, 17Ca and 18Ca yield the hexahydrothiepine 27C and oxepane derivatives 28C, respectively, 21Ca gives the tetrahydropyran 30C. Diastereomerically pure 29C arises by prolonged hydrogenation of 17Ca under reinforced conditions via 27C.
Neue Dienophile und Diene, III. Über die Addition von Cyanacetylen an [2.2]Paracyclophan
Authors: Witulski Bernhard , Ernst Ludger , Hopf Henning , Jones Peter G. 
Published: July 2007

New Dienophiles and Dienes, III. — On the Addition of Cyanoacetylene to [2.2]ParacyclophaneHeating a benzene solution of [2.2]paracyclophane (2) in the presence of excess cyanoacetylene (1b) at 160°C in a sealed ampoule provides the novel 2:1‐addition product 10, as well as the previously obtained cycloadducts 7–9. It is suggested that these Nenitzescu hydrocarbon systems are formed via the cyclobutadiene intermediates 17 and 18. This hypothesis is supported by the isolation of the side‐products 1,2,4‐and 1,2,3‐tricyanobenzene (11 and 12). When a mixture of 7 and 8 is pyrolyzed at 220°C the novel dihydronaphthalene 24 is formed; the mechanism of this isomerization is discussed. The structures of 10 and 24 were confirmed by X‐ray structure determination.
Synthesen mit aliphatischen Dialdehyden, XLIV. Chirale Pentamethincyanin‐Farbstoffe und Heterocyclen aus Derivaten des (S)‐(+)‐2‐sec‐Butylmalonaldehyds
Authors: Reichardt Christian , Budnik Ulrich 
Published: July 2007

Syntheses with Aliphatic Dialdehydes. XLIV. — Chiral Pentamethine Cyanine Dyes and Heterocycles from Derivatives of (S)‐(+)‐2‐sec‐ButylmalonaldehydeSyntheses and UV/Vis‐spectroscopic properties of the chain‐substituted, homochiral pentamethine cyanine dyes 16 and 17 are described. 16 and 17 as well as the homochiral five‐, six‐, and seven‐membered heterocycles 11–15 are prepared from derivatives (5 and 6) of homochiral (S)‐(+)‐2‐sec‐Butylmalonaldehyde (8), the first known chiral malonaldehyde, which in turn is synthesized in a seven‐step procedure from homochiral (S)‐(‐)‐2‐methyl‐1‐butanol (1).
Organische Synthesen mit Übergangsmetallkomplexen, 48. Methyl(thiocarben)‐ und Alkenyl(thiocarben)‐Chrom‐Komplexe: Darstellung und Reaktionen
Authors: Aumann Rudolf , Schröder Jochen 
Published: July 2007

Organic Syntheses via Transition Metal Complexes, 48. — Methyl Thiocarbene and Alkenyl Thiocarbene Chromium Complexes: Synthesis and ReactionsThiocarbene chromium complexes (CO)5CrC(SR1)R (4: R  Me, Ph; R1  c‐C6H11, CH2CHCH2, C2H5, C6H5) were readily obtained in up to 97% isolated yields from the corresponding ethoxycarbene chromium complexes 5a, b and thiols 6 in methanol in the presence of Na2CO3 as a catalyst. Reaction conditions, which lead to unfavorable side products, like thioacetals 8 and or thioenol ether 10, are discussed. Methyl thiocarbene complexes 4b–d undergo a facile aldol condensation with the aromatic aldehydes 14 or 16 to give alkenyl thiocarbene complexes 15b–d and 17, respectively. The CrC bonds of 15 prove to be reactive towards the insertion of isocyanides or oxygen. Thus, on addition of two equivalents of the isocyanide 18 to 15d, 1‐aza‐1,2,4‐pentatriene 20 is obtained. The oxidative decomposition of 15d on silica gel leads to the formation of thioester 25 and thioindene 26. Characteristic differences in the reactivity of thiocarbene complexes and ethoxycarbene complexes are discussed.
Übergangsmetall‐Silyl‐Komplexe, 35. Silber(I)‐Silyl‐Komplexe (R3P)nAgSiR'3 (n = 1‐3)
Authors: Wagner Herbert , Schubert Ulrich 
Published: July 2007

Transition‐Metal Silyl Complexes, 35. — Silyl Complexes of Silver(I). (R3P)nAgSiR3' (n = 1‐3)The complexes (R3P)nAgSiR'3 (n = 1‐3), dppm(AgSiR'3)2 and dppe(AgSiR'3)2 [SiR3 = Si(aryl)3 or, except for n = 3, Si(Si Me3)3) are prepared from the corresponding halide complexes or dppm/dppe(AgNO3)2 with LiSiR'3. The stability of the products increases with increasing n : the dppe‐ or dppm‐substituted complexes are distinctly more stable than the corresponding complexes with monodentate phosphane ligands. The silver‐silicon bond is highly polar as demonstrated by their properties.
Zum anomeren Effekt bei Dithiatriazinen
Authors: Jaudas‐Prezel Evelyn , Maggiulli Roberto , Mews Rüdiger , Oberhammer Heinz , Paust Thomas , Stohrer Wolf‐Dieter 
Published: July 2007

The Anomeric Effect in DithiatriazinesFrom (CF3CN3S2)n (1) and XeF2, Br2, or (CF3)2NO* the corresponding S,S‐substituted dithiatriazines CF3CN3S2F2 (2), CF3CN3S2Br2 (3), and CF3CN3S2[ON(CF3)2]2 (4) are prepared. An electron diffraction study of 2 in the gas phase results in a slightly aplanar 6‐membered ring with chair conformation and both S‐F bonds in axial position. MNDO calculations show that the position of the substituents at the sulfur atoms is strongly dependent on these substituents and on the ring geometry. The cis preference is the result of an anomeric effect.
Tin for organic synthesis, 3. Facile and effective synthesis of unusually substituted aromatic N‐phenylamides
Authors: Kobs Uwe , Neumann Wilhelm P. 
Published: July 2007

AbstractA mild and effective new method for the preparation of a variety of arylamides 3a‐i as well as heterocyclic 5a,b and 6 and olefinic amides 7, 9 is described. The reaction of tri‐alkylstannyl‐substituted aromatic, heterocyclic or vinylic hy‐drocarbons with aryl isocyanates in the presence of aluminium trichloride provides the corresponding N‐aryl‐substituted am‐ides in good to excellent yields. The stannyl group serves as a powerful leaving group superior to hydrogen by several powers of ten which allows, via ips0 substitution, to obtain isomer patterns not accessible by normal electrophilic substi‐ tution reactions, e. g. substitution in meta position with respect to a methoxy group.
Alken‐, Alkin‐, Isonitril‐ und Carbonyl‐Komplexe von Kupfer(I) und Silber(1) mit dreizähnigen Sauerstoff‐Chelatliganden
Authors: Lenders Bernd , Kläui Wolfgang 
Published: July 2007

Alkene, Alkyne, Isonitrile, and Carbonyl Complexes of Copper(I) and Silver(I) with Tris‐Chelating Oxygen LigandsThe preparation of η2‐alkynecopper(I) complexes of the composition [LRCu(η2‐alkyne)], alkyne = tolan, dimethyl acetylenedicarboxylate, is described. LR are anionic tris‐chelating oxygen ligands of the type [(C5H5)Co{P(O)R2}3]−, R  OMe, OEt, O‐i‐Pr. The isonitrile complexes [LRM(CNt‐Bu)], M  Cu, Ag, have been prepared from [LOMeCu(CO)] and [{AgLOEt}2], respectively, The silver carbonyl complex [LOEt}Ag(CO)] [v(CO)  2147 cm−1] forms in hexane and methanol solutions of [{AgLOEt}2] under 1 atm of CO gas. The olefin complexes [LRCu(ba)], ba = benzytlideneacetone, have been prepared from [Cu(CH3CN)4]PF6, NaLOMe, and ba and from the carbonyl complex [LOEtCu(CO)] and ba. The coordination of the carbon‐carbon double bond of ba at the LRCu fragment does not lead to a 1,4‐addition of methyllithium to the α,β‐unsaturated ketone.
Synthese, Reaktivität und Ligandeigenschaften von 1,4‐Dihydro‐1,4‐diboranaphthalin‐ und 2,3‐Benzo‐1,4‐dihydro‐1,4‐diborafulven‐Derivaten
Authors: Febenbecker Achim , Schulz Hartmut , Pritzkow Hans , Siebert Walter 
Published: July 2007

Synthesis, Reactivity, and Ligand Properties of 1,4‐Dihydro‐1,4‐diboranaphthalene and 2,3‐Benzo‐1,4‐dihydro‐1,4‐diborafulvene DerivativesThe chlorine derivative 1a of 1,4‐dihydro‐1,4‐diboranaphthalene and 2a of 2,3‐benzo‐1,4‐dihydro‐1,4‐diborafulvene are obtained by treating 1,2‐bis(trimethylstannyl)benzene (3)with (EtCBCl2)2 (4) and 1,2‐bis(dichloroboryl)benzene (5) with 1,1‐bis(trimethylstannyl)‐2‐methyl‐1‐propene (6), respectively. The dimethyl derivatives 1b and 2b react with the Fe(CO)3 complex fragment to yield the iron complexes 7b and 8b, in which the iron is bound to the heterocycle of 1b and 2b, respectively. The X‐ray structure analyses of 7b, 8b, and 2b are described.
Darstellung eines viergliedrigen Indium‐Phosphor‐Rings mit am Phosphor gebundenem Wasserstoff. — Kristallstruktur von [(Me3SiCH2)2InPHtBu]2
Authors: Dembowski Udo , Noltemeyer Mathias , Rockensüß Wilfried , Stuke Michael , Roesky Herbert W. 
Published: July 2007

Preparation of a Four‐Membered Indium‐Phosphorus Ring with a Hydrogen Atom Bound to Phosphorus. — Crystal Structure of [(Me3SiCH2)2 InPHtBu]2Reaction of tBuPH2 (1) with (Me3SiCH2)3In (2) in the presence of Ag+ ions leads to [(Me3SiCH2)2InPHtBu]2 (3). According to an X‐ray structure analysis, 3 forms a four‐membered planar P2In2 ring with alternating P — In bonds and crystallizes in the monoclinic space group C2/c.
Cyclophanes, XXXV. DNMR, molecular mechanics, and crystal structures of 2,11‐dithia[3.3]orthometacyclophane and 2,11‐dithia[3.3]orthoparacyclophane
Authors: Bodwell Graham J. , Ernst Ludger , Hopf Henning , Jones Peter G. , McNally John P. , Schomburg Dietmar 
Published: July 2007

AbstractThe syntheses of 2,11‐dithia[3,3]orthometacyclophane (5) and 2,11‐dithia[3,3]orthoparacyclophane (6) by dithiol‐dibromide coupling are described. Whereas the yield of 5 is not significantly affected by the substrate pairing, that of 6 is. Both compounds exhibit a temperature‐dependent 1H‐NMR spectrum. An energy barrier of 11.0 ± 0.2 kcal/mol (45.7 ± 0.8 kJ/mol) has been calculated for 5, but that of 6 was too low to be determined. Slightly contrasting results were obtained from two different molecular mechanics programs for the relative energies of the six limiting conformations of 5. Crystal structure determinations of 5 and 6 have been carried out, and the conformational behavior of 5 and 6 in solution and in the solid state is discussed.
Macrocyclic pyridinophanetetraene
Authors: Thilgen Carlo , Vögtle Fritz 
Published: July 2007

AbstractThe new pyridinophanetetraene 4 has been prepared in a two‐step synthesis by a modified Kharash coupling reaction of 2,6‐bis[3‐lithio‐(E)‐styryl]pyridine with copper(II) chloride. Starting from isomerically pure 2,6‐bis[3‐bromo‐(E)‐styryl]pyridine (3), the cyclization reaction takes place without rearrangement of the stilbazole double bonds. The electronic spectrum of 4 shows characteristic differences when compared to that of its open‐chain analogue 2,6‐bis[(E)‐styryl]pyridine (7).
1,4‐Dioxino[2,3‐b]pyridine und 1,4‐Oxathiino[2,3‐b]pyridine
Authors: Neunhoeffer Hans , Sponheimer Otto 
Published: July 2007

1,4‐Dioxino[2,3‐b]pyridines and 1,4‐Oxathiino[2,3‐b]pyridines1,4‐Dioxino[2,3‐b]pyridine and 1,4‐Oxathiino[2,3‐b]pyridine Reaction of 3‐hydroxy‐2‐pyridones 1 or 3‐hydroxy‐2‐pyridinthiones 2 with sodium hydride and 1,2‐dibromoethane in hexamethylphosphorous triamide gives 1,4‐dioxino[2,3‐b]pyridines 3 and 1,4‐oxathiino[2,3‐b]pyridines 5 which can be hydrogenated to amino‐1,4‐dioxino[2,3‐b]pyridines 7.
Addition von Alkenen an 5‐(Trifluormethyl)‐1,3,2,4,6‐dithiatriazin
Authors: Maggiulli Roberto , Mews Rüdiger , Noltemeyer Mathias , Offermann Werner , Paape Rainer , Stohrer Wolf‐Dieter 
Published: July 2007

Addition of Alkenes to 5‐(Trifluoromethyl)‐1,3,2,4,6‐dithiatriazinesDechlorination of 1,3‐dichloro‐5‐(trifluoromethyl)‐1,3,2,4,6‐dithiatriazine (1) with Ph3Sb gives (CF3CN3S2)n (2) in quantitative yield. By 1,3‐addition of alkenes (dicyclopentadiene, cyclopentene, cis‐ and trans‐2‐butene, propene, and ethene) to 2 the corresponding penta‐ (4a), tri‐(5a), and bicyclic ring systems 6a, 6b, 7, 8a, 8b, and 9 are prepared in 65–85% yields. The molecular structures of 6a and 7 were determined by single‐crystal X‐ray analysis; the other structures were derived from NMR data. The NMR analyses are in accordance with MNDO calculations. For 4a and 5a only the thermodynamically favoured anti‐isomers are found, as expected from these calculations; for 6 and 8 they show satisfactory agreement for anti/syn‐proportions as determined by NMR spectroscopy. The product distribution corresponds to a symmetry‐allowed alkene addition to a singlet dithiatriazine.
Synthese und Eigenschaften von 1,2,4,3‐Thiadiazaboretidinen. Kristallstruktur des 2,4‐Di‐tert‐butyl‐3‐phenyl‐1,2,4,3‐thiadiazaboretidins
Authors: Habben Carl D. , Heine Andreas , Sheldrick George M. , Stalke Dietmar , Bühl Michael , Schleyer Paul Von R. 
Published: July 2007

Synthesis and Properties of 1,2,4,3‐Thiadiazaboretidines. Crystal Structure of 2,4‐Di‐tert‐butyl‐3‐phenyl‐1,2,4,3‐thiadiazaboretidineReaction of sulfur diimides with alkyl(aryl)bis(methylthio)boranes leads to reductive 1,3‐cycloaddition of the NSN sequence with formation of the 1,2,4,3‐thiadiazaboretidines 2a‐g. NMR (1H, 11B, 13C, 15N, 29Si), mass spectra and the results of the X‐ray analysis of 21 are reported and discussed. The 11B chemical shifts have been calculated for 3‐phenyl‐1,2,4,3‐thiadiazaboretidine and some related model compounds by the IGLO method and correlate acceptably with the experimental values.
Molecular Structure of Hg[C(COF)SF2O]2
Authors: Bittner Jürgen , Seppelt Konrad 
Published: July 2007

AbstractHg[C(COF) = SF2 = O]2 is prepared by the reaction of FCO  CH = SF2 = O with HgF2. This compound represents the third known example of an alkylidenesulfur difluoride oxide. Its molecular structure is the same as that of the most abundant of the three isomers of FCO‐CH = SF2 = O. This is assumed to be the result of weak intramolecular Hg… O contacts. With the exception of the fluorine atoms bound to sulfur, all atoms lie approximately in one plane.
Heterocyclen als Liganden, X 2,2′,5,5′‐Tetra‐tert‐butyl‐1,1′‐diazaferrocen — Stabilisierung der Diheterometallocen‐Struktur durch sterische Abschirmung
Authors: Kuhn Norbert , Jendral Kai , Boese Roland , Bläser Dieter 
Published: July 2007

Heterocycles as Ligands, X1). — 2,2′,5,5′‐Tetra‐tert‐butyl‐1,1′‐diazaferrocene – Stabilization of the Diheterometallocene Structure by Steric ShieldingStable 2,2′,5,5′‐tetra‐tert‐butyl‐1,1′‐diazaferrocene (3) is obtained by the reaction of the corresponding lithiopyrrole with FeCl2. The X‐ray analysis reveals a distorted sandwich structure influenced by repulsive interactions presumably both between the nitrogen atoms and the bulky tert‐butyl substituents.
Is the Fe+‐Induced C — H/C — C Bond Activation of α,ω‐Alkanedinitriles Affected by Bifunctional Interactions?
Authors: Prüsse Tilmann , Czekay Gregor , Schwarz Helmut 
Published: July 2007

AbstractThe metastable‐ion mass spectra of Fe+ complexes of alkanedinitriles NC(CH2)nCN (n = 1 – 10) exhibit six types of reactions: (1) Loss of the intact ligand to regenerate bare Fe+ as the exclusive (n = 1) or major reaction (n = 2) for the lower homologues; (2) generation of nitriles H(CH2)mCN with m = 0 – 6; (3) formation of unsaturated nitriles CH2 = CH(CH2)mCN with m = 0 – 4; (4) production of C2H4; (5) dehydrogenation, and (6) expulsion of the radicals C2H5 and CH2CN+. The branching ratios of these competing processes are governed by the chain length (CH2)n separating the two CN groups. Mechanistic insight is provided by the study of isotopomers. A comparison of the present data with the previously described behaviour of RCN/Fe+ complexes (R = alkyl) leaves no doubt that for the α,ω‐alkanedinitriles it is the Fe+‐mediated interaction of the two functional groups which controls the gas‐phase chemistry of these organometallic systems. For example, results are presented demonstrating inter alia that losses of H2 and C2H4 proceed by completely different pathways when dinitriles serve as precursors, and either reaction is affected by neighbouring group participation. In distinct contrast, for RCN/Fe+ complexes (R = alkyl) the existing data point to common intermediates.
Nucleophile Substitution von Nitrit in Nitrobenzolen, Nitrobiphenylen und Nitronaphthalinen
Authors: Effenberger Franz , Koch Markus , Streicher Willi 
Published: July 2007

Nucleophilic Substitution of Nitrite in Nitrobenzenes, Nitrobiphenyls, and NitronaphthalenesAromatic compounds, accessible only by multistep procedures, can be synthesized easily by nucleophilic substitution of nitrite in nitrobenzenes, nitrobiphenyls, and nitronaphthalenes. Thus, meta‐substituted phenols 3, 4, and 7 are obtained from 1,3‐dinitrobenzene (1) and meta‐substituted nitrobenzenes 6, as well as 3,5‐disubstituted phenols 10 and 5‐substituted resorcinol derivatives 11 from 3,5‐disubstituted nitrobenzenes 9. The unsymmetrically substituted nitrobiphenyls 13, 15, 17, 19, 21, 23, 24, and 26 are also available by nitrite exchange from the corresponding easily accessible dinitrobiphenyls 16, 18, 20, 22, and 25. A nitrite exchange with nucleophiles is easily possible in the 1,5‐disubstituted naphthalenes 29, 34, while in the case of the 1,8‐disubstituted naphthalenes 31, 36 only the chloro derivative 36 undergoes this exchange under much stronger conditions in low yield.
Zur Reaktion von Dialkylphosphiten mit α‐Enonen, I Synthese und Allyl‐Umlagerung von (1‐Hydroxy‐2‐alkenyl)‐ und (1‐Hydroxy‐2‐cycloalkenyl)phosphonsäure‐dimethylestern
Authors: Öhler Elisabeth , Zbiral Erich 
Published: July 2007

Reaction of Dialkyl Phosphites with α‐Enones, I. – Synthesis and Allylic Rearrangement of Dimethyl (1‐Hydroxy‐2‐alkenyl)‐ and (1‐Hydroxy‐2‐cycloalkenyl)phosphonatesVarious β,γ‐unsaturated α‐hydroxyphosphonates 3 are prepared in good yields by NaOCH3‐catalyzed regioselective 1,2‐addition of dimethyl phosphite to acyclic and cyclic α‐enones at −35°C. On acid‐catalyzed acetylation, the allylic α‐hydroxyphosphonates 3 (R1, R2 + H) rearrange under thermodynamic control; yielding the new 3‐acetyloxy‐1‐(cyclo)alkenyl derivatives 8, from which the transposed allylic alcohols 11 are readily obtained. Using shorter reaction times, acetylation of compounds 3 affords mixtures of 1‐ and 3‐acetylated products, 10 and 8, respectively.
Dioxirane Epoxidation of α,β‐Unsaturated Ketones
Authors: Adam Waldemar , Hadjiarapoglou Lazaros , Smerz Alex 
Published: July 2007

AbstractThe synthesis of epoxides 3a – r is achieved in excellent yields by reaction of the α,β‐unsaturated ketones 1a–c, 4,4′‐disubstituted (E)‐chalcones 1d–o, and 2′‐hydroxy‐4‐substituted (E)‐chalcones 1p – r with isolated dimethyldioxirane (2a) (as acetone solution) and/or in situ generated ethyl(methyl)dioxirane (2b). This method constitutes a useful alternative to the Weitz‐Scheffer epoxidation (alkaline H2O2) of such electronpoor substrates.
Dreikernige Niob‐Oxid‐Cluster1). – Synthese von (η5‐C5Me5)3Nb3(μ2‐O)3(μ3‐O)‐(μ2‐Cl)Cl3 und [(η5‐C5Me5)3Nb3(OH)2(μ2‐OH)(μ3‐OH)(μ2‐O)2(μ3‐O)Cl]Cl
Authors: Leichtweis Iring , Roesky Herbert W. , Noltemeyer Mathias , Schmidt Hans‐George 
Published: July 2007

Trinuclear Niobium Oxide Clusters1). – Synthesis of (η5‐C5Me5)3Nb3(μ2‐O)3(μ3‐O)(μ2‐Cl)Cl3 and [(η5‐C5Me5)3Nb3(OH)2(μ2‐OH)(μ3‐OH)(μ2‐O)2(μ 3‐O)Cl]ClHydrolysis of η5‐C5Me5NbCl4 with excess of water leads to a mixture of products. Pyrolysis of this crude mixture gives (η5‐C5Me5)3Nb3(μ2‐O)3(μ3‐O)(μ‐Cl)Cl3 (1) in good yield. On treatment of 1 with water [(η5‐C5Me5)3Nb3(OH)2(μ2‐OH)(μ3‐OH)(μ2‐O)2(μ3‐O)Cl]Cl (2) is obtained. The products 1 and 2 were characterized analytically and by X‐ray structure determination.
Phosphane‐Borane Chemistry. – Borane Adducts of Two Polyfunctional Phosphanes
Authors: Schmidbaur Hubert , Wimmer Thomas , Lachmann Joachim , Müller Gerhard 
Published: July 2007

AbstractThe tris(borane) adduct MeC(CH2PMe2BH3)3 (2) of 1,1,1‐tris‐[(dimethylphosphino)methyl]ethane has been prepared from the tripodal phosphane and Me2S–BH3 as the borane source. The crystal structure of 2·1/2 toluene has been determined by single‐crystal X‐ray diffraction methods. The molecules display crystallographic C3 symmetry and an overall staggered conformation. In an analogous way the bis(borane) adduct CH2(PH2BH3)2 (3) of 1,3‐diphosphapropane has been synthesized, which decomposes above 50°C to give insoluble products, whose elemental analysis indicated that termal P–C bond cleavage is more frequent than P–B bond cleavage.
Umsetzungen von Ga2Br4 · 2 Dioxan mit (Trimethylsilyl)methyllithium und Neopentyllithium – Synthese und Kristallstruktur von Lithiumtetraalkylgallanaten(III) mit Li–C–Ga‐Brücke
Authors: Uhl Werner , Klinkhammer Karl‐Wilhelm , Layh Marcus , Massa Werner 
Published: July 2007

Reactions of Ga2Br4 · 2 Dioxane with (Trimethylsilyl)methyllithium and Neopentyllithium — Synthesis and Molecular Structure of Lithium Tetraalkylgallanates(III) with Li–C–Ga BridgesGa2Br4 · 2 dioxane reacts with (trimethylsilyl)methyllithium or neopentyllithium to yield in n‐pentane/diethyl ether solution besides elemental gallium exclusively the disproportionation product trialkylgallane. In pure n‐pentane the dioxane adducts of the corresponding lithium tetraalkylgallantes (R = CH2SiMe3 2; R = CH2CMe3 4) are formed. 2 and 4 are also synthesized by the reaction of GaBr3 with alkyl lithium in the molar ratio 1:4. The crystal structure of 2 shows a dioxane‐bridged dimer and Li–C–Ga bridges with lithium probably bound by the C–H s̀‐bonds of the central carbon atoms.
Kristallines Tl2B9H9C2Me2: Synthese und Festkörperstruktur; ein Beitrag zum Problem “attraktive Tl(I)–Tl(I)‐Wechselwirkungen”
Authors: Jutzi Peter , Wegener Dirk , Hursthouse Mike B. 
Published: July 2007

Crystalline Tl2B2H9C2Me2: Synthesis and Solid State Structure; a Contribution to the Problem of Tl(I)–Tl(i) InteractionsCrystalline Tl2B9H9C2Me2 (1) is obtained in the reaction of the carborane B9H11C2Me2 with two equivalents of thallium(I) ethanolate. An X‐ray diffraction study of 1 shows – contrary to the expectation – the presence of isolated thallium ions and thalladicarbollide counteranions. The latter represent ion pairs composed of Tl(I)+ and B9H9C2Me212− units forming slipped icosahedrons. All possible Tl–Tl distances in 1 are too long for even weak attractive interactions, with one exception: A set of symmetry‐equivalent cations possesses a Tl–Tl distances of 3.67 A, which is in a range postulated by calculations for weak bonding.
Selektivitäten bei Photoadditionen an multifunktionelle Coffein‐Derivate
Authors: Kaupp Gerd , Ringer Ernst 
Published: July 2007

Selectivities in Photoadditions with Multifunctional Caffeine DerivativesElectronically excited stilbene (21*), 4,4′‐dichlorostilbene (1*), and 4,4′‐dimethoxystilbene (18*) are trapped by caffeine derivatives 2, 13, or 22 with variable results. While 1* and 2 react predominantly at the imino double bond (substitutive and fragmentating additions), 1* or 18* and 13 produce mostly propellanes by [2 + 2] photocycloaddition, which hydrolyze or may be hydrolyzed. 21* and the relatively electron‐poor compound 22 produce mostly propellanes, which always show a preponderance of the syn‐10, anti‐11 stereoisomers. These selectivities as well as the competition with reactions at the imino double bonds are rationalized on the basis of diradical mechanisms with the aid of semiempirical AM1 calculations. Earlier results on closely related transformations are also discussed.