bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ein Weg zu neuartigen funktionalisierten Bis(imino)phosphoranen XP( NAryl)NAlkyl
Authors: Niecke Edgar , von der Gönna Volker , Nieger Martin 
Published: July 2007

A Route to Novel Functionalized Bis(imino)phosphoranes XP(NAryl)NAlkylChloro(arylimino)phosphane (1) reacts with alkyl azides RN3 (R  tBu, Et3C, 1‐Ad) to form 4,5‐dihydro‐1H‐tetrazaphos‐pholes 2a‐c. The thermal decomposition of these compounds results in the formation of the diazadiphosphetidines 4a–c via the chlorobis(imino)phosphorane intermediates 3a–c, which were detected by NMR spectroscopy. By treating 2a with the lithium salts Li(nBu, C5Me5, NHAryl, OAryl, tBuS) the 4,5‐dihydro‐1H‐tetrazaphosphole intermediates 5a–d are obtained, which by elimination of nitrogen form the bis(imino)phosphoranes 6a–e. The X‐ray structure determination of the phosphane derivative tBu2PP(NCEt3) NAryl (7), obtained by the same procedure, is discussed.
Stereoselective synthesis of alcohols, XXXV. Addition of E‐ and Z‐crotylboronates to chiral α‐substituted aldehydes
Authors: Brinkmann Heinrich , Hoffmann Reinhard W. 
Published: July 2007

AbstractThe direction (Cram/anti‐Cram) and the extent of asymmetric induction on addition of crotylboronates to a range of chiral aldehydes was investigated. A reversal in the sense of the asymmetric induction on changing from the Z‐ to the E‐crotylboronate was found for aldehydes having polar α substituents and for some of the nonpolar chiral aldehydes. Forcefield calculations on transition‐state models reproduced these results in the majority of the cases investigated despite of unaccounted short comings of the method.
(2R)‐5‐Alkyl‐2‐tert‐butyl‐6‐methyl‐4H ‐1,3‐dioxin‐4‐one als Zwischenprodukte zur Herstellung von α,β,β‐trisubstituierten β‐Hydroxycarbonsäuren unter Selbstregeneration des stereogenen Zentrums von (R)‐3‐Hydroxybuttersäure
Authors: Amberg Willi , Seebach Dieter 
Published: July 2007

(2R)‐5‐Alkyl‐2‐tert‐butyl‐6‐methyl‐4H‐1,3‐dioxin‐4‐ones as Intermediates for the Preparation of α,β,β‐Trisubstituted β‐Hydroxycarboxylic Acids from (R)‐3‐Hydroxybutyric Acid under Self‐Regeneration of the Stereogenic CenterThe exocyclic double bonds of the readily available (2R,6R)‐5‐alkylidene‐2‐tert ‐butyl‐6‐methyl‐1,3‐dioxan‐4‐ones (preceding paper) are shifted to the endocyclic position by treatment with Pd‐C/H2 to give the dioxins 2 ‐ 6 in overall yields of 40‐ 60% (calcd. from the parent tert‐butyl‐methyl‐dioxanone, 4 steps). F3B ‐ OEt2‐mediated Me‐, Bu‐ and Ph‐cuprate additions to the tetrasubstituted double bonds of these dioxinones can be used to prepare the 2‐tert‐butyl‐5,6,6‐trialkyl‐1,3‐dioxanones 7 ‐ 15 (40‐65% yield, 5: 1 to 16: 1 diastereoselectivity) as single isomers. Hydrolysis leads to 5,6,6‐trialkyl hydroxy acids (for instance 16‐18) specified in the title; formally, these compounds are aldol‐type adducts of carboxylic acids to unsymmetrical ketones. — The configurational assignment rests upon NOE measurements and, in one case, upon a chemical correlation. The stereochemical course of the conjugate addition and of the Li enolate protonations, which are responsible for the selective formation of the two new stereogenic centers, is discussed.
[1.1.1]Propellane and maleic anhydride: Face‐specific copolymerization with formation of an alternating 1:1 copolymer
Authors: Gosau Jan‐Michael , Schlüter Arnulf‐Dieter 
Published: July 2007

AbstractThe spontaneous and face‐specific copolymerization of [l.l.l]propellane and maleic anhydride to give the strictly alternating 1:1 copolymer 2 is described. The molecular weight of 2 after transformation into the corresponding diester 5c was determined to be 80.000 (Mn) and 220.000 (Mw), respectively.
Übergangsmetall‐Silyl‐Komplexe, 36 Zur Frage von Gold‐Gold‐Wechselwirkungen bei Ph2P[CH2]1(2) PPh2 verbrückten zweikernigen Gold‐Silyl‐Komplexen
Authors: Piana Hermann , Wagner Herbert , Schubert Ulrich 
Published: July 2007

Transition‐Metal Silyl Complexes, 361). — On the Question of Gold‐Gold Interactions in Ph2P[CH2]t(2)PPh2‐Bridged Dinuclear Gold Silyl ComplexesDinuclear silyl gold complexes of the type dppm(AuSiR3)2 (1) or dppe(AuSiR3)2 (2) are prepared by the reaction of dppm‐(AuCl)2 or dppe(AuCl)2 with two equivalents of LiSi(aryl)3 or LiSi(SiMe3)3 The complex dppe[AuSi(SiMe3)3]2 (2 c) exhibits crystallographic inversion symmetry, and therefore the distance between both gold atoms is a maximum. In dppm‐(AuSiPh3)2 (1b) a gold‐gold interaction between both gold atoms is observed [Au — Au 316.80(3) pm].
Beiträge zur Chemie des Phosphors, 2101,2) Pentaorganyltricyclononaphosphane mit Brexan‐Struktur, b‐P9R5 (R = Me, Et, iPr)
Authors: Baudler Marianne , Arndt Volker 
Published: July 2007

Contributions to the Chemistry of Phosphorus, 2101.2). – Pentaorganyltricyclononaphosphanes with a Structure Analogous to Brexane, b‐P9R5 (R = Me, Et, iPr)The reaction of RPCl2, P4, and magnesium provides two constitutionally isomeric pentaorganyltricyclononaphosphanes. Besides the isomer with a P9 skeleton analogous to that of noradamantane (a‐P9R5), which was already identified, a further isomer of lower relative abundance (b‐P9R5) has now been found. In the case of R = Et (2) it has been isolated as a pale yellow, oily liquid and, in the cases of R = Me (1) and iPr (3), has been highly enriched. According to their 31P{1H}‐NMR spectra, 1 — 3 have a constitution analogous to that of the hydrocarbon brexane, thus being 2,4,5,8,9‐pentaorganyltricyclo[4.3.0.03.7]nonaphosphanes. They are each formed as mixtures of several configurational isomers, which differ in their relative arrangements of the organyl groups.
Asterane, XXII. Synthese eines doppelten Tetraasterans: Nonacyclo[10.8.0.02,11.04,9.04,19.06,17.07,16.09,14.014,19]eicosan
Authors: Hoffmann Volker Thomas , Musso Hans 
Published: July 2007

Asteranes, XXII1). — Synthesis of a Double Tetraasterane: Nonacyclo[10.8.0.02,11.04,9.04,19.06,17.07,16.09,14.014,19]eicosane1,4,5,8‐Tetrahydronaphthalene‐2,3‐dicarboxylic anhydride (9) is dimerized by UV light in dioxane yielding four isomeric [2 + 2] adducts whose methyl ester derivatives are elucidated spectroscopically. The structures of the major products 14 and 16 have been confirmed by X‐ray structure analysis. Degradation of the carboxylic groups of 14 afforded the title compound 5.
Synthesis of 4‐Aminopyrimidines from 1,2,4‐Oxadiazoles, III A Novel Type of Formation of Olefins from Amines
Authors: Korbonits Dezsö , Simon Kálmán , Kolonits Pál 
Published: July 2007

AbstractOn heating at 100°C, 1,2,3,4‐tetrahydro‐6,7‐dialkoxy‐1‐[(acylamidino)methylene]isoquinolines (5) are transformed into 4‐substituted 6,7‐dihydro‐9,10‐dialkoxy‐2H‐pyrimido[6,1‐α]isoquinoline‐2‐imines (6), while at 140°C they undergo a novel prototropic rearrangement via 6 to give 4‐amino‐6‐(4,5‐dialkoxy‐2‐vinylphenyl)‐2‐phenylpyrimidines (7). The structure of 7a has been determined by X‐ray analysis.
Cyclobuten‐Ringöffnung: Eine nützliche Reaktion zur Synthese doppelsträngiger Moleküle
Authors: Godt Adelheid , Schlüter Arnulf‐Dieter 
Published: July 2007

Cyclobutene Ring Opening: A Useful Reaction for the Synthesis of Double‐Stranded MoleculesSyntheses and ring‐opening reactions of the compounds endo‐5a – e and 9a – c, all containing cyclobutene rings, are described. From these experiments it is concluded that compound 9a is a useful AB‐type Diels‐Alder monomer for the synthesis of well‐defined double‐stranded molecules. The stereochemistry of the adducts endo‐4b and endo‐5d is determined by X‐ray structure analysis.
Darstellung aromatischer Fluor‐Verbindungen durch nucleophilen Austausch von Nitro‐Gruppen gegen Fluorid
Authors: Effenberger Franz , Streicher Willi 
Published: July 2007

Synthesis of Aromatic Fluoro Compounds by Nucleophilic Exchange of Nitro Groups by FluorideThe synthesis of aromatic fluoro compounds from the respective nitro compounds by nucleophilic substitution of nitrite by fluoride is described. Reasonable yields in case of nonactivated nitro compounds are only obtained if the nitrite formed in the reaction is eliminated by acylation. 1‐Fluoro‐3‐nitrobenzene (2) was obtained from 1,3‐dinitrobenzene (1), and 1‐fluoro‐3,5‐dinitrobenzene (9) as well as 1,3‐difluoro‐5‐nitrobenzene (10) from 1,3,5‐trinitrobenzene (8) in yields up to 92% by reaction of nitro compounds with potassium fluoride in sulfolane at 180 – 200°C in the presence of phthaloyl dichloride (6); 1,2‐difluoro‐4‐nitrobenzene (12) was formed in 58% yield from 2,4‐dinitro‐1‐fluorobenzene (11) in the presence of pyromellitoyl tetrachloride (13).
Neutralization‐Reionization Mass Spectrometry and Matrix Isolation of Some 9‐Silaanthracenes
Authors: Winkel Yvar Van Den , Van Baar Ben L. M. , Bickelhaupt Friedrich , Kulik Willem , Sierakowski Claudia , Maier Günther 
Published: July 2007

AbstractNeutralization‐reionization mass spectrometry of silaanthracene radical cations, which are generated from the 9,10‐dihydro‐9‐silaanthracenes 1, 3, 8 and 11 under electron‐impact conditions, indicates that silaanthracenes are stable molecues in the gas phase. Flash pyrolysis of the starting compounds mentioned above also yields the silaanthracenes 2, 4, and 10, which may be isolated in an argon matrix at 15 K and exhibit characteristic UV spectra.
Organische Synthesen mit Übergangsmetall‐Komplexen, 50 2H‐Pyrrol‐Komplexe durch stufenweise Insertion von Alkinen und Isocyaniden in MC‐Bindungen von Chrom‐ und Wolfram‐Carbenkomplexen
Authors: Aumann Rudolf , Hinterding Peter 
Published: July 2007

Organic Syntheses via Transition Metal Complexes, 501). – 2H‐Pyrrole Complexes by a Stepwise Insertion of Alkynes and Isocyanides into MC Bonds of Carbene Chromium or Tungsten Complexes2H‐Pyrrole complexes 6a, b are obtained in two step by [1+2+2] cycloaddition reactions of the carbene complex (CO)5WC(OEt)C6H5 (1d), the alkyne EtO‐CCH (2) and isocyanides R1‐NC 4a, b [R1 = CH3, c‐C6H11). LnC(OEt)R 1 [LnM = Cr(CO)5, W(CO)5; R = C6H5, CH3] reacts with 2 to give 1‐metalla‐1,3‐dienes 3a–d. (E)/(Z)‐3d and 4 yield 6a, b via 1‐aza‐1,2,4‐pentatriene complexes 5, which are open‐chain precursors of 6. 2H‐Pyrrole complexes 11 and 14 are synthesized in overall [2+1+2] cycloadditions withe reversed connectivity, or formation of 1‐chroma‐1,3‐dienes 10 and 13 by condensation of the methylcarbene complex 1a with acid amides, and cyclisation again with isocyanides 4.
Umlagerungen von 1,4,4‐ und 2,2,5‐Trimethylbicyclo[3.2.1]oct‐6‐yl‐Kationen
Authors: Kirmse Wolfgang , Mönch Dietmar 
Published: July 2007

Rearrangements of 1,4,4‐ and 2,2,5‐Trimethylbicyclo[3.2.1]oct‐6‐yl Cations1,4,4‐Trimethylbicyclo[3.2.1]oct‐6‐yl cations (18) are generated from the tosylhydrazone 7, by nitrous acid deamination of the amines 6 and 8, and by acetolysis of the brosylates 21 and 24. The product distributions are but slightly affected by the configuration (exo vs. endo) of the leaving groups. The predominant product, 1,4,4‐trimethylbicyclo[3.2.1]octan‐exo‐6‐ol (11) is formed without significant redistribution of a 6‐2H label. The degenerate Wagner‐Meerwein rearrangement of the parent bicyclo[3.2.1]oct‐6‐yl cation is virtually eliminated by the presence of two methyl groups at C‐4. Enhanced conformational strain, raising the barrier to ring flipping, accounts for these observations. Minor products (12, 13) arise from a 7,6‐hydride shift of 18, followed by Wagner‐Meerwein rearrangement. When the 2,2,5‐trimethylbicyclo[3.2.1]oct‐6‐yl cation (19) is generated directly from the tosylhydrazone 17, the tertiary alcohol 13 is obtained as the major product. The conformational barrier to Wagner‐Meerwein rearrangement is compensated by the incipient stabilization of the tertiary carbocation 20.
Umlagerungen von 5,5,6,6‐Tetraalkyl‐2‐norbornyl‐Kationen
Authors: Kirmse Wolfgang , Mrotzeck Uwe , Siegfried Rainer 
Published: July 2007

Rearrangements of 5,5,6,6‐Tetraalkyl‐2‐norbornyl CationsWhen the 6,6‐dimethyl‐2‐norbornyl cation (9) is generated from the tosylhydrazone 5 by way of the diazonium ion 8, a 2H label is distributed equally between positions 1 and 2 of the exo‐alcohol 10. The degeneracy of 9, previously derived from solvolytic studies, is thus confirmed for the deaminative route. 5,5,6,6‐Tetramethyl‐2‐norbornanone (25) and tetracyclo[4.2.2.12,5.01,6]undecan‐3‐one (31) are prepared by using Diels‐Alder methodology. The corresponding tosylhydrazones 26 and 32 are employed as precursors for the 5,5,6,6‐tetramethyl‐2‐norbornyl and tetracyclo[4.2.2.12,5.01,6]undec‐3‐yl cations (11 and 12). Again, the distributions of 2H labels are close to 1 : 1. The angular distortions expected from repulsive interactions of the methyl groups in 11 and from cyclobutane annulation in 12 do not affect the relative energies of the bridged ions.
Zum Koordinationsverhalten von Alkinylphosphanen RnP(CC–R')3–n
Authors: Lang Heinrich , Zsolnai Laszlo 
Published: July 2007

Coordination Ability of Alkynylphosphines RnP(CC – R')3 – nAlkynylphosphines RP(CC–R')2 (2) react with one equivalent of octacarbonyldicobalt to yield selectively the η2‐μ side‐on‐coordinated alkyne complexes (R)(R' – CC)P[(η2‐CC–R')Co2(CO)6] (6); with another equivalent of Co2(CO)8 the dicoordinated compounds (R)P[(η2‐CC–R')Co2(CO)6]2 (7) are obtained. 7 may also be synthesized directly by the reaction of 2 with two equivalents of Co2(CO)8. However, P(CC–Ph)3 yields with two equivalents of Co2(CO)8 the cyclic Co2P2C2 system {(Ph–CC)(R')P[(η2‐CC–Ph)Co2(CO)5]} 2 (4) [R' = (η2‐CC–Ph)Co2(CO)6]. Decarbonylation of 6a gives the six‐membered cyclic compound {(Ph)(Ph – C  C)P[(η2‐C  C – Ph)Co2(CO)5]}2 (8), while 6b yields the cluster Co3(CO)9(μ3‐PtBu) (9). The structure of (tBu)P[(η2‐C  C – H)Co2)CO)6]2 (7b) is elucidated by an X‐ray analysis.
Cycloadditionsreaktionen von Organometallkomplexen, XII1) Ketenimine aus Isocyaniden und Diazoalkanen: Eine neue Cobalt‐vermittelte C–C‐Verknüpfungsreaktion
Authors: Strecker Beate , Hörlin Gerhard , Schulz Michael , Werner Helmut 
Published: July 2007

Cycloaddition Reactions of Organometallic Complexes, XII1). – Ketenimines from Isocyanides and Diazoalkanes: A New Cobalt‐Assisted C–C Bond Forming ReactionThe compounds C5H5Co(CNR)(PMe3) (1–3) react with diaryl‐diazomethanes (X)(Y)CN2 to give the C,C‐bound ketenimine cobalt complexes C5H5Co[η2‐C,C‐RNCCXY] (PMe3) (4–9), while the reaction of 1–3 with 9‐diazofluorene leads to the formation of N,C‐bound ketenimine complexes C5H5Co[η2‐N,C‐RNCC(C12H8)](PMe3) (11–13). The different bonding modes of the ketenimine ligands in 4–9 and 11–13, indicated already by the significantly different spectroscopic data, are shown by the X‐ray structural analysis of 9‐RCoSC (R = CHMePh; X and Y = 4‐ClC6H4) and 12 (R = C6H11). On treatment of compounds 4, 6–9, 11, and 13 with an equimolar amount of iodine, free ketenimines are generated. The by‐product C5H5Co(PMe3)I2 can be transformed into the starting materials 1–3 in two steps via the cations [C5H5Co(CNR)‐(PMe3)I]+ as intermediates.
Metallatome in der Synthese von Metallclustern, II1) Reaktionen von substituierten Cyclopentadienen und Nickelocen mit Nickel‐ und Eisenatomen
Authors: Schneider JöRg J. , Goddard Richard , Krüger Carl , Werner Stefen , Metz Bernkard 
Published: July 2007

Metal Atoms in the Synthesis of Metal Clusters, II1). – Reactions of Substituted Cyclopentadienes and Nickelocene with Nickel and Iron AtomsBy vaporizing nickel atoms into solutions of tert‐butyl‐substituted cyclopentadienes in methylcyclohexane mononuclear sandwich compounds (1, 4, and 6 as main products) as well as tri‐ and tetranuclear clusters are prepared. With mono‐ and di‐tert‐butyl‐substituted cyclopentadienes as ligands the new clusters 2 and 5 are obtained. In the reaction with 1,2,4‐tri‐tert‐butylcyclopentadiene 6 is the only observed product. Hindered rotation around the metal‐ligand bond vector is observed for 4 even at room temperature. When treating 1 with nickel atoms cluster 2 is formed, indicating some importance of 1 during the formation of 2 in the above reaction. Clusters 2 and 5 contain hydrido ligands, which could be identified in the case of tris(1,3‐di‐tert‐butyl‐η5‐cyclopentadienyl)trinickel dihydride (5) by a single crystal structure determination as μ3‐H bridges. A tetrahedral structure is found for the cluster 2 by X‐ray crystallography. With the aid of MS, IR, magnetic measurements, and cyclovoltammetric investigations 2 is identified as a mixture of 2a and 2b bearing one or three bridging hydrogens, respectively. In general 2a, 2b, and 5 show a rich redox chemistry with reversible redox couples between –2 and +2. Reaction of iron atoms, nickelocene, and mesitylene in methylcyclohexane at −120°C leads unexpectedly to cluster 3, tetrakis(η5‐cyclopentadienyl)tetranickel trihydride and a not yet identified (η5‐cyclopentadienyl)mesityleneiron complex. Possible formation routes for 1–6 are discussed.
Photocycloadditionen mit α‐ und β‐Naphthaldehyd: Vollständige Umkehr der Diastereoselektivität als Konsequenz unterschiedlich konfigurierter elektronischer Zustände
Authors: Griesbeck Axel G. , Mauder Harald , Peters Karl , Peters Eva‐Maria , Schnering Hans Georg Von 
Published: July 2007

Photocycloadditions with α‐ and β‐Naphthaldehyde: Complete Inversion of Diastereoselectivity as a Consequence of Differently Configurated Electronic StatesThe diastereoselectivity of the [2 + 2] photocycloaddition reaction between aromatic aldehydes and 2,3‐dihydrofuran (3) is completely inverted when changing the electronic configuration of the excited triplet from 3(nη*) to 3(nπ*). Mesitylenaldehyde, which corresponds to the first case, reacts endo‐ selectively, whereas α‐ and β‐naphthaldehyde (with low‐lying ππ* triplets and reactive nπ* singlets) react exo‐selectively. The configuration of the α‐naphthaldehyde adduct is proven by means of X‐ray structure analysis. This type of spin‐correlation effect can be rationalized by comparing the conformation of the reactive biradical intermediates for rapid inter‐system crossing and/or bond closure. In the furan (1) case, this effect cannot be observed. All carbonyl compounds investigated here react exo‐selectively. A possible explanation for this pronounced selectivity is the assumption of a secondary orbital effect.
Verschiedenartige Koordinationen bei η2‐Alken)‐(η5‐cyclopentadienyl)organylnickel(II)‐Komplexen
Authors: Lehmkuhl Herbert , Näser Jürgen , Mehler Gerlinde , Keil Thomas , Danowski Friedhelm , Benn Reinhard , Mynott Richard , Schroth Gerhard , Gabor Barbara , Krüger Carl , Betz Peter 
Published: July 2007

Various Coordinations in (η2‐Alkene)(η5‐cyclopentadienyl)organylnickel(II) ComplexesA series of (η2‐alkene)(η5‐cyclopentadienyl)organylnickel(II) complexes with substituted cyclopentadienyl ligands is synthesized in order to compare the structures, the thermal stabilities, and chemical reactivities. In (allyl)(η5‐Cp')Ni compounds the allyl moiety is η3‐coordinated when Cp'=C5H5, C5Me5 (1), C5Ph5 (2), indenyl (3), [Hydridotri(pyrazolyl)borato] (4) (as an equivalent of the cyclopentadienyl ligand), and [C5H4((CH2)3CHCH2)] (22). It is found that the [(η2‐alkene)alkyl(η5‐Cp')nickel] compounds [Cp'=C5Me5; alkeneC2H4, alkyl=Me (10), Et (9) or alkene=(1 – 2‐η2)‐1,3‐butadiene, alkyl=Me (11); Cp'=C5Ph5; alkene=C2H4, alkyl=Me (12)] are thermally more stable and less reactive than their η5;‐ C5H5 analogues; the largest increase in thermal stability is observed when the η5‐Cp' and the η2‐alkene functions are connected by substitution of the cyclopentadienyl ligand with an alkenyl group of suitable chain length. In the case of compounds of the general type [(η5‐C5R4((CH2)nCHCH2))‐(ligand)Ni(II)] with Ph3P as the ligand these complexes are cationic [RH, n=3 (14+) or RMe, n=2 (17+)]. On the other hand, the compounds with anionic ligands are neutral complexes (RH, n=3, ligand=methyl (19), ethyl (20), isopropyl (21) or RMe, n=3 and ligand=iodide (24), bromide (25), methyl (26), ethyl (27)]. In 14+, 17+, 19 – 21 and 24 – 27 the CC bond of the alkenyl group is η2‐coordinated to the nickel atom. X‐ray structures have been determined for 4 and 25.
Medizinisch interessante Metallchelate, I. 99mTc‐Komplexe mit sechszähnigen Tribrenzkatechin‐Liganden
Authors: Ekkehardt Hahn F. , Rupprecht Stefan 
Published: July 2007

Metal Chelates of Medical Interest, I. – 99mTc Complexes with Hexadentate Tricatechol LigandsThe tricatechol ligand tris[3‐(2,3‐dihydroxyphenoxy)propyl]‐amine hydrochloride, TRIPACE (9), is prepared from tris(3‐chlorpropyl)amine (5) and the potassium salt of 2,2‐dimethyl‐1,3‐benzodioxol‐4‐ol (7). This ligand is capable of reducing the 99m[TcO4]− ion to lower valent 99mTc and subsequent complexation of the reduced 99mTc ion. The structures of 5 and of tris[3‐(2,2‐dimethyl‐1,3‐benzodioxol‐4‐yloxy)propyl]amine (8) are determined by X‐ray diffraction.
Verhalten von cis;‐2‐Boryl‐1‐stannylalkenen gegenüber (Dimethylamino)trimethylstannan, Methoxytrimethylstannan und Methanol – Aufbau neuer Zinn – Element‐Bindungen, Beispiele für Lösungsmittel‐gesteuerte Reaktionen
Authors: Wrackmeyer Bernd , Wagner Klaus 
Published: July 2007

Behaviour of cis;‐2‐Boryl‐1‐stannylalkenes Against (Dimethylamino)trimethylstannane, Methoxytrimethylstannane, and Methanol – Formation of New Tin – Element Bonds, Examples of Solvent‐Controlled ReactionsWhen alkene derivatives1 [Me3Sn(R1)CC(R)BR2], with the trimethylstannyl‐ and the dialkylboryl group in cis position at the CC double bond, are treated with (dimethylamino)‐trimethylstannane (4), methoxytrimethylstannane (5), or methanol, the product distribution depends remarkably on the solvent [hexane or tetrahydrofuran (THF)]. In hexane, 1a, b (R1=H, REt, Pr) react with 4 to give the B‐dimethylamino compounds 6a, b in high yields as a result of addition and rearrangement. Other derivatives 1 do not react with 4 in hexane. Under the same conditions in hexane some alkenes 1 react with 5 to yield the B‐methoxy derivatives 8, which are analogous to 6. A complex mixture of various products is obtained from the reaction of 1 with methanol in hexane. If the same reactions are carried out in THF, many compounds 1 react with 4 and 5 to eliminate tetramethyltin and give dihydro‐ 1,2,5‐azonia‐ (7) or dihydro‐1,2,5‐oxoniastannaboratoles (9), respectively. The reaction with methanol in THF also leads to the oxonia‐stannaboratoles 9, this time by elimination of methane. Pure samples of compound 9g are obtained as the crystalline THF adduct 9g‐THF. A mechanism is proposed involving adduct formation at the boryl group, followed by intramolecular reactions depending on the donor quality of the respective solvent.
Über die Funktion von Di(tert‐butyl)silandiolat als Anker für Metallfragmente in hohen und mittleren Oxidationsstufen. Synthese und Strukturen von (tBu2SiO2(TeCl2–μ‐Cl2 – TeCl2) und (tBu)2Si(OReO3)2
Authors: Roesky Herbert W. , Mazzah Ahmed , Hesse Detlev , Noltemeyer Mathias 
Published: July 2007

Function of Di(tert‐butyl)silanediolate as an Anchor for Metal Fragments in High and Medium Oxidation States. Synthesis and Structures of (tBu)2SiO2(TeCl2 – μ‐Cl2 – TeCl2) and (tBu)2Si(OReO3))2The compounds (tBu)2SiO2(TeCl2 – μ‐Cl2 – TeCl2) (2) and (tBu)2Si(OReO3)2 (3) have been prepared by the reactions of (tBu)2Si(OH)2 (1) with TeCl4 and Re2O7. The single‐crystal X‐ray structures of 2 and 3 are reported. The (tBu)2SiO2 group functions as an anchor for the metal fragments TeCl3 and ReO3.
Zur Struktur von 2‐Azapentadienyllithium‐Verbindungen
Authors: Wolf Gerhard , Würthwein Ernst‐Ulrich 
Published: July 2007

On the Structures of 2‐Azapentadienyllithium Compounds2‐Azapentadienyllithium compounds 3 – 10 are easily accessible by deprotonation of N‐allylimines 1,2 with lithium diisopropylamide. Their structures in THF solution at various temperatures are studied by means of 1H‐ and 13C‐NMR spectroscopy. 1‐Phenyl‐substituted 2‐aza‐pentadienyllithium derivatives adopt all‐trans W conformations, whereas 1‐alkylsubstituted 2‐azapentadienyllithium compounds show s‐cis conformations (sickle shapes). 13C shifts of the 2‐azapentadienyl carbon atoms are discussed in terms of HOMO coefficients. The experimental structural results are compared with theoretical data obtained by MNDO and ab initio calculations for the corresponding anions. MNDO results are also given for monomeric 2‐azapentadienyllithium conformers 13,14.