bluuebunny/crossref_metadata_2025 huggingface dataset:
Versuche zur Umlagerung von Cyclobutyl‐ in 3‐Butenyl‐Anionen: Endocyclische Ringöffnung bei der Reaktion von (3,3‐Diphenyl‐1‐vinylcyclobutyl)methylether mit Alkalimetallen – anionisch oder radikalisch?
Authors: Maercker Adalbert , Berkulin Willi
Published: July 2007

Attempted Rearrangement of Cyclobutyl Anions to 3‐Butenyl Anions: Endocyclic Ring Opening upon Reaction of 3.3‐Diphenyl‐1‐vinylcyclobutyl Methyl Ether with Alkali Metals ‐ via Anions or Radicals?

The reaction of the title compound 16 with lithium or sodium in THF yields mainly the open‐chain E/Z isomeric trianions 31 ⇌ 32 besides the expected cyclobutyl anion 10. The endocyclic ring opening takes place via the radical intermediate 28 primarily yielding a butadiene derivative 29, which is then further reduced. The anion 10 – prepared independently by deprotonation of the corresponding hydrocarbon 18 – does not rearrange. On investigating side reactions it was discovered that 4,4‐diphenyl‐1‐butene derivatives treated with lithium in THF undergo C–C bond cleavage affording diphenyl‐methyllithium in good yields.
Trends Across the Periodic Table – A Screening of the Gas‐Phase Chemistry of d‐Block Transition‐Metal Ions with Isocyanides
Authors: Eller Karsten , Schwarz Helmut
Published: July 2007

By screening the reactions of alkyl isocyanides RNC with most of the d‐block transition metal ions several trends are uncovered that permit a deeper insight in the intrinsic properties of the metal ions. The ability of C – H activation, relative binding energies to alkenes and hydrogen isocyanide as well reactivity in general can be deduced from collisional activation of RNC/M+ complexes, using tandem mass spectrometry methodologies.
Synthese und seitenselektive Diels‐Alder‐Reaktion von Homodehydroisodicyclopentadien
Authors: Ipaktschi Junes , Herber Jürgen , Kalinowski Hans‐Otto , Boese Roland
Published: July 2007

Synthesis and Face‐Selective Diels‐Alder Reaction of Homodehydroisodicyclopentadiene

Under alkaline conditions the mesylate 6c, obtained from the tetracyclic ketone 6b fragments into the enone 8a. The latter is transformed via alcohol 9 into the homodehydroisodicyclopentadiene 3 and via tosylhydrazone 8b into the triene 4. Cyclopentadiene 3 reacts with a series of non‐acetylenic dienophiles from the sterically less hindered side to give the products 14‐17. Acetylenic dienophiles yield the adducts 19–22 in a 1:1 ratio. The UV and PE spectra of triene 4 are discussed.
Neue wasserlösliche makrobicyclische Großhohlräume
Authors: Wallon Alexander , Peter‐Katalinića Jasna , Werner Ute , Müller Walter M. , Vögtle Fritz
Published: July 2007

New Watersoluble Macrobicyclic Cavities

The watersoluble macrobicyclic compounds 1, 3, 5a, and 5b have been synthesized for the first time bearing large endolipophilic cavities of different sizes and shapes. They were studied with respect to their interactions towards lipophilic guest compounds. The “in/out” isomerism of the hitherto largest endolipophilic cavities 4a, 4b, 5a, and 5b has been investigated by 1H‐, 13C‐NMR spectroscopy and FAB mass spectrometry. The absence of significant 1H‐NMR high‐field shifts in hostguest studies is attributed to the rigidity of cavities 1 and 3, whilst the isomeric cavities 5a and 5b contain very large openings. Orientational fluorescence spectroscopy investigations, however, suggest hostguest interactions of the isomers 5a and 5b with ammonium 8‐anilino‐1‐naphthalenesulfonate (8,1‐ANS).
Synthese und Kristallstruktur von Iminophosphanen mit Liganden hoher π‐Donorfähigkeit
Authors: Niecke Edgar , Nieger Martin , Gärtner‐Winkhaus Christiane , Kramer Bertold
Published: July 2007

Synthesis and Crystal Structure of Iminophosphanes Containing Ligands with High π‐Donor Ability

Reaction of the lithiated ketimines LiN=CR2 (R2 = tBu2, fluorenyl) 1a,b with the chloro(arylimino)phosphanes Cl–P=N–Ar (AR = 2,4,6‐tBu3C6H2) 2 affords the heterobutadienes R2C=N–P=NAr 3a,b. The X‐ray structure determination of 3a,b reveals an unusually short P–N single bond both cis and trans arrangements of the NPN skeleton.
Short Communication 9‐Diisopropylamino‐9‐borabicyclo[4.2.1]nona‐2,4,7‐triene from the Reaction of Cyclooctatetraene with Sodium‐Potassium Alloy and Dihalogeno(diisopropylamino)boranes
Authors: Maringgele Walter , Stalke Dietmar , Heine Andreas , Meller Anton , Sheldrick George M.
Published: July 2007

The reaction of 1,3,5,7‐cyclooctatetraene with sodium‐postassium alloy and dihalogeno(diisopropylamino)boranes in 1,2‐dimethoxyethane gives the title compound, characterized by elemental analysis, MS (EI, FI), NMR (1H, 11B, 13C), and X‐ray crystallography.
Chemistry of the Heterocyclic Pseudobasic Amino Alcohols, XXXVIII Ring‐Chain Tautomerism of Pyrimido[6,1‐a]isoquinolines
Authors: Korbonits Dezsö , Horváth GÁBor , Simon KÁLmÁN , Kolonits PÁL
Published: July 2007

In basis media, 4‐substituted pyrimido[6,1‐a]isoquinolin‐2‐imine hydrochlorides (4) constitute an equilibrium system involving the tautomeric forms characteristic of pseudobases 5, 6, 7 and the anhydro base 9. In aqueous solution in the pH range 7–13 the ammonium hydroxide form 5 is present. Between pH 13 and 14 the pseudobase 6 probably arises from this by covalent binding of the hydroxy group. 6 is then converted to the more stable imino type anhydrobase 9. Ring cleavage of 4 by excess alkali or of 9 by a small amount of water gives 1‐(acylamidinomethylen)isoquinolines 7. Compounds 7 and 9 are stable in the solid state or in aprotic solutions but revert to cation 5 in dilute protic solutions.
Nitroxide (Aminyloxide), 43 Der Einfluß struktureller Faktoren auf die Dimerisierung von Vinylnitroxiden mit cyclischen Acylgruppen als β‐Substituenten
Authors: Aurich Hans Günter , Franzke Michael , Kesselheim Hans‐Peter , Keßler Wilfried , Massa Werner , Wocadlo Sigrid
Published: July 2007

Nitroxides (Aminyl Oxides), 43. ‐ The Effect of Structural Features upon the Dimerization of Vinyl Nitroxides Substituted in β‐Position by Cyclic Acyl Groups

Reaction between N‐alkyl‐ and N‐arylhydroxylamines and hydroxymethylene compounds 4 (derivatives of menthone, norboranone, borananone, indanone, and γ‐butyrolactone) affords nitrones existing in the tautomeric forms 5 and 6. Oxidation of these nitrones generates the β‐acylated vinyl nitroxides 7, which dimerize in various ways. The N‐alkyl‐substituted vinyl nitroxides 7DA, De, Ea, Ga, and Gf yield simple CC‐bonded dimers 8 From 7Ba dimer 10 is formed via 8Ba. The structure of 10 is confirmed by an X‐ray analysis. In contrast, the N‐arylsubstituted vinyl nitroxides 7 Ab, Fc, and Bc as well as the N‐alkyl‐substituted 7 Aa afford the bicyclic dimers 9 which arise by OC dimerization followed by an intramolecular 1,3‐dipolar cycloaddition. Finally, the vinyl nitroxides 7Dc and Dd underwent further oxidation to give dehydrodimers 12. 12e is formed only if 6De is oxidized by a large excess of lead dioxide.
Zur Dehydrierung von 1,4‐Dihydroarenen mit Mangan‐Reagentien
Authors: Radtke Rainer , Heesing Albert
Published: July 2007

Hydrogen Transfer Reactions, 141) ‐ The Dehydrogenation of 1,4‐Dihydroarenes by Manganese Oxidants

Hydrogen abstraction from 1,4‐dihydroarenes by both MnO2 and the KMnO4‐dicyclohexano‐[18]crown‐6 complex occurs successively. In the first, rate‐determining step one hydrogen is transferred. A synchronous transfer (by cyclic or termolecular pathways), a SET mechanism, or the addition of the permanganate ion to the double bond are not in accord with the large isotope effects. A moderate cis‐selectivity is found for the abstraction of the second hydrogen by MnO2.
Synthese und Reaktionen von Hydrido(oxim)‐, Hydrido(oximato)‐ und Alkenyl(oximato)‐Komplexen des Rutheniums und Osmiums
Authors: Meyer Uwe , Werner Helmut
Published: July 2007

Synthesis and Reactions of Hydrido(oxime), Hydrido(oximato) and Alkenyl(oximato) Complexes of Ruthenium and Osmium

The carbonyl(hydrido) complexes MHCl(CO)[PMe(tBu)2]2 (4: M = Ru; 5: M = Os) react with aldoximes and ketoximes to give the octahedral hydrido(oxime)ruthenium and ‐osmium compounds MHCl(CO)[N(OH)=CRR′](PMe(tBu)2]2 (8–13) in high yields. Using MHCl(CO)(PiPr3)2 (6, 7) as starting materials, the complexes MHCl(CO)[N(OH)=CRR′](PiPr3)2 (14–16) are obtained. Reactions of 9 (M = Os; R = R′ = CH3) illustrate that the oxime ligand in the hydrido(oxime) compounds is easily displaced by Lewis bases. Either from 4, 5 and Na[N(O) = CRR′] in methanol or from 8–13 and NaH in THF the hydrido(oximato) complexes 20–25 in which the oximato ligand is coordinated via N and O, are formed almost quantitatively. CO opens the three‐membered ring by cleavage of the M‐N bond. Analogously, the alkenyl(oximato) compounds 28–30 are obtained from M[(E)–CH = CHPh]Cl(CO)[PMe(tBu)2)2]2 (18: M = Os; 27: M = Ru) with Na[N(O) = CRR′].
N,N′‐Dilithiobis(alkylamino)phenylborane als Synthesebausteine für viergliedrige Metallacyclen
Authors: Fest Dietmar , Habben Carl D. , Meller Anton , Sheldrick George M. , Stalke Dietmar , Pauer Frank
Published: July 2007

N,N′‐Dilithiobis(alkylamino)phenylboranes as Starting Materials for Four‐Membered Metallacycles

Reactions of N,N′‐Dilithiobis(alkylamino)phenylboranes with tetrachlorides MCl4 (M = Ge, Sn, Ti, Zr) produce the 4,4′‐spirobi(1,3‐dialkyl‐2‐phenyl‐1,3‐diaza‐2‐bora‐4‐metalla‐cyclobutane) derivatives 1a, 1b, 2b, 3a, and 3b. With diorganylmetal dihalides R2MX2(M = Sn, Zr; X = Cl, Br), the 1,3‐diaza‐2‐bora‐4‐metallacyclobutanes 2a and 4 are obtained. For 3a an X‐ray structure analysis has been performed.
Strukturen von Pentaarylbismut‐Verbindungen
Authors: Schmuck Arno , Leopold Dieter , Wallenhauer Stephan , Seppelt Konrad
Published: July 2007

Structures of Pentaarylbismuth Compounds

Rose‐colored, dichroitic pentakis (4‐methylphenyl) bismuth has an intermediate structure between trigonal bipyramidal and square‐pyramidal. It cocrystallizes with (LiCl · 2 THF)2. The LiCl forms an almost regular rectangle with two short (195pm) and two long (235pm) bonds. Red Bi(4‐CH3C6H4)3(2,6‐F2C6 H3)2 is very similar to square pyramidal Bi(4‐C6H5)3 (2,6‐F2C6H3)2: The structural isomerism of yellow Bi(4‐CH3C6H4)3 (2‐FC6H4)2 (trigonal bipyramidal) and violet Bi (C6H5)3 (2‐FC6H4)2 (square pyramidal) is not found here. Orange red, dichroitic Bi(C6H5)3‐(C12H8) remains in a distorted square pyramidal structure in spite of the constraints of the 2,2′‐biphenylylene ring system. The square pyramidal geometry seems to dominate in bismuth chemistry of this type, in contrast to P, As, and Sb. However, the structure of (C6F5)3BiF2 shows an almost regular trigonal bipyramid, as expected. The latter cocrystallizes as (C6F5)3BiF2 · 2 Bi (C6F5)3, so the structure of Bi(C6F5)3 is elucidated also.
Chirale Halbsandwich‐Komplexe von Rhodium(III), Iridium(III), Iridium(I) und Ruthenium(II) mit α‐Aminosäure‐Anionen
Authors: Krämer Roland , Polborn Kurt , Wanjek Herbert , Zahn Ingo , Beck Wolfgang
Published: July 2007

Metal Complexes of Biologically Important Ligands, LIII. – Chiral Half‐Sandwich Complexes of Rhodium(III), Iridium(III), Iridium(I), and Ruthenium(I1) with a‐Amino Acid Anions

The chloro‐bridged metal compounds Cp*(Cl)M(μ‐Cl)2M(Cl)‐Cp* (M = Rh, Ir; Cp* = η5‐C5Me5), (η6‐C6H6)(Cl)
Umlagerungen von 6‐Bicyclo[3.2.1]octyl‐Kationen
Authors: Brandt Sigrid , Kirmse Wolfgang , Mönch Dietmar , Wroblowsky Heinz‐Jürgen
Published: July 2007

Rearrangements of 6‐Bicyclo[3.2.l]octyl Cations

6‐Bicyclo[3.2.1]octyl cations were generated by nitrous acid deaminations of the amines 12, 14 and by acetolyses of the tosylates 9, 20. the major products are bicyclo[3.2.1]octan‐exo‐6‐ol (17), bicyclo[3.2.1]octan‐exo‐2‐o. (18), and bicyclo[2.2.2]octan‐2‐ol (19). 4,6(4,5) hydride shifts account for the formation of 18 and 19. The product distributions indicate substantial kS contributions for he endo precursors while the exo precursors react almost exclusively by way of carbocations, as confirmed by the ring expansion of bicyclo[4.1.1]octane‐2‐di‐azonium ions (30. The product distributions obtained from the exo‐diazonium ion 15n and from the exo‐tosylate 20 are rather similar, but hte distributions of a deuterium label differ strongly. Dediazoniation of 15 leads to a highly unsymmetrical intermediate, whereas acetolysis of 20 involves an effectively equilibrated species. These findings cannot e interpreted in terns of open ions. Unsymmetrically bridged ions, whose conformational equilibration competes with substitution and hydride shifts, provide a consistent explanation.
(E,Z) Equilibria, 12. Differential NMR Shielding by Phenyl, Assigned from Chemical Labelling and (Z,E) Equilibration
Authors: Knorr Rudolf , Hintermeyer‐Hilpert Monika , Böhrer Petra
Published: July 2007

Unequivocal NMR assignments of the (E,Z) isomeric pairs 3 and 8 are possible by (Z,E) equilibration. Deprotonation of 2‐methyl‐1‐phenylpropene (1) with n‐BuLi under any conditions gives only a single allyl‐metal derivative 2. Methylation of the latter gives the isomer (Z)‐3, while deuteriolysis leads to the isotopically labelled derivative 6 of the olefin 1; this Proves the NMR assignments for 1 as well as the endo configuration of 2. The phenyl group gives rise to a differential shielding effect on the γ‐carbon nuclei in methyl and methylene gropus along a CC double bond (ca, 7 ppm), and this effect is comparable to that along a CN double bond as in 8. The nitrile function in 5c is much less effective.
Reaktionen von Homobenzvalenen mit 4 ‐Phenyl‐3H‐l,2,4‐triazol‐3,5(4H)‐dion, Tetracyanethylen, Chlorsulfonylisocyanat und Schwefeldioxid. Einige konzertierte 1,4‐Additionen an eine Vinylcyclopropan‐Einheit
Authors: Lang Reinhard , Herzog Clemens , Stangl Roland , Brunn Erich , Braun Max , Christl Manfred , Peters Eva‐Maria , Peters Karl , Schneringb Hans Georg Von
Published: July 2007

Reactions of Homobenzvalenes with 4‐Phenyl‐3H‐1,2,4‐triazole‐3,5(4H)‐dione, Tetracyanoethylene. Chlorosulfonyl Isocyanate, and Sulfur Dioxide. Several Concerted 1,4‐Additions to a Vinylcyclopropane Subunit

Homobenzvalene (le) and its derivatives 1f.g with an anellated four‐membered ring reacted with 4‐phenyl‐3H‐l,2,4‐tri‐ azole3,5(4H)‐dione (PTAD) to give the pentacyclic urazole 2e and its hexacyclic derivatives 2f, g, respectively. Tetracyano‐ ethylene (TCNE) and le in benzene afforded only the Diels‐ Alder adduct 5 of norcaradiene. In other solvents the homo Diels‐Alder adduct 3a of le was formed as the main product together with some 5 and a small fraction of the cyclohexa‐ dienylcyclopropanetetracarbonitrile 4a. 5‐Methylhomobenz‐ valene (lh) and TCNE in acetonitrile gave 3b and 4b in the ratio 10: 1. On treatment with TCNE, dihydrohomobenzvalene (6) was converted into 8, which is structurally related to 4. In contrast, tetracyc10[4.1.0.02,4.03,5]]heptane (7) and TCNE gave rise to the tetracyclic adduct 9 and a minor quantity of 5. Chlorosulfonyl isocyanate reacted with le to furnish mainly the N‐(chlorosulfony1)imino ether 10 and the N‐(chlorosulfonyl)‐lactams 11 and 12a as well as a further isomer as byproducts. On heating, 10 rearranged to 12a. The Ksulfonyl chlorides 10, 11, and 12a were transformed to the N‐unsubstituted compounds 16,15, and l7, respectively, by treatment with sodium sulfite/aqueous potassium hydroxide. In wet [D6]dimethyl‐ sulfoxide 10 was converted into a cycloheptatriene derivative (14) as well as the rearranged and hydrolyzed lactam 15, whereas 11 gave 15 exclusively. Exposure of le to sulfur dioxide yielded the 1,4 adduct 18 to the vinylcyclopropane subunit of le. Possible mechanisms of the reactions of the homobenzvalenes are discussed. In particular, the pathways to 3, 18, and at least to a fraction of 10 and 11 are considered to be concerted six‐electron processes. – The structures of 4a and 10 have been established by X‐ray analyses.
Schwermetall‐π‐Komplexe, V. Das Schichtenpolymer {([C6H6SnCl][GaCl4])2}x, y
Authors: Frank Walter
Published: July 2007

Heavy Metal π Complexes, V1. ‐ The Layer Polymer {([C6H6SnCl][GaCl4])2}x,y

In the system C6H6/SnC12/GaC13 crystalline (benzene)chlorotin(+2) tetrachlorogallate(+3) (1) is obtained. According to an X‐ray structure analysis (Pca21) the solid contains polymeric {([C6H6SnCl][GaCl4])2}x,y layers built up by ((C6H6SnC1][GaCl4])2 structural units. A unit consists of an Sn2Cl22+ four‐ membered ring, two GaCl4− tetrahedra at opposite sides of the ring plane, and two benzene molecules bound to the tin atoms in a distorted η6 state. A pseudorotational disorder of one of the benzene ligands was found. The tin‐arene bonding is much weaker in 1 compared to the chain polymer (([C6H6SnCl](AICl4])}x(2).
Organosubstituierte Kalium‐2,5‐dihydro‐1,2,5‐oxasilaboratolate aus cis‐2‐Boryl‐1‐silylalkenen mit Kaliumhydroxid
Authors: Köster Roland , Seidel Günter , Wrackmeyer Bernd , Horchler Klaus
Published: July 2007

Organosubstituted Potassium 2,5‐Dihydro‐1,2,5‐oxasilaboratolates from cis‐2‐Boryl‐1‐silylalkenes with Potassium Hydroxide

The compounds (E)‐CH3ElIV(R2)2CR3C(C2H5)B(C2H5)2 [R2,2,3 = CH3: 1a; R2 = C2H5, R2,3 = CH3: 1b; R2,2 = C6H5, R3 = CH3: 1c; R2,2 = CH3, R3 = C6H5: 1d; R2,2 = CH3, R3 = c‐C6H11: 1e] add KOH in THF at – 20°C to form the pure solid 1:1 adducts KOH‐1ElIV with ElIV = Si, Sn, and Pb. Above ≥0°C compounds KOH‐1Si liberate quantitatively R2H to give the potassium salts of the cyclic anions K‐2a to K‐2e. With Me4NCl or Me3NHCl the corresponding salts Me4N‐2 or Me3NH‐2 are obtained from K‐2. Above ≈︁80°C KOH‐1aGe and KOH‐1aSn eliminate gas (CH4, C2H6) with formation of mixtures. The compounds KOH‐1ElIV and K‐2Si are characterized by multi‐NMR spectroscopy (1H, 11B, 13C, 17O, 29Si, 119Sn, 207Pb), and the NMR data of KOH‐1aElIV are compared to the data of the compounds .
Notizen / Notes. Eine neue Bildungsweise der Phosphor – Phosphor‐Bindung. Kristallstrukturanalyse von Tetramethyldiphosphanmonosulfid
Authors: Gruber Matthias , Jones Peter G. , Schmutzler Reinhard
Published: July 2007

A New Mode of Formation of a Phosphorus ‐ Phosphorus Bond. X‐ray Crystal Structure of Tetramethyldiphosphane Monosulfide

Tetraphenyldiphosphane monosulfide (7) was formed during an attempt to synthesize the diphenylphosphino‐substituted thioureas 5 and 6 by the reaction of thiourea (1) or N,N′‐bis‐(trimethylsilyl)thiourea (2) with chlorodiphenylphosphane. The attempted distillation of the dimethylphosphino‐substituted N,N′‐dimethylthiourea 9 furnished tetramethyldiphos‐phane monosulfide (10). These reactions provide a new mode of formation of phosphorus – phosphorus bonds. – According to an X‐ray analysis, 10 crystallizes in the space group P21/n. The molecule adopts a trans configuration, with the S atom antiperiplanar to the lone pair.
Die Funktion der 4′‐Aminopyrimidin‐Komponente im Katalysemechanismus von Thiaminpyrophosphat‐Enzymen aus heutiger Sicht
Authors: Schellenberger Alfred
Published: July 2007

The Function of the 4′‐Aminopyrimidine Component in the Mechanism of the Catalysis of Thiamine Pyrophosphate Enzymes from Today's View

Binding mechanism and coenzyme function of thiamine pyrophosphate (TPP) are described with the help of site‐directed substitutions at different positions of the coenzyme. In accordance to the earlier suggestions of Langenbeck (see this issue2) it is shown, that besides the thiazolium moiety (C2 atom) also the aminopyrimidine part plays an essential role in the catalytic mechanism of TPP enzymes such as pyruvate decarboxylase, pyruvate dehydrogenase, and transketolase, respectively. A two‐center mechanism of TPP is proposed explaining the function of the amino group as an internal proton relay in the catalytic mechanisms of TPP enzymes.
Active Magnesium from Catalytically Prepared Magnesium Hydride or from Magnesium Anthracene and its Uses in the Synthesis
Authors: Bartmann Ekkehard , Bogdanovic̀ Borislav , Janke Nikolaus , Schlichte Klaus , Spliethoff Bernd , Treber Joachim , Westeppe Uwe , Wilczok Ursula , Liao Shijan
Published: July 2007

Highly reactive, pyrophoric forms of magnesium with specific surface areas of 20–109 m2/g (Mg*) can be generated by the dehydrogenation of catalytically prepared magnesium hydride (MgH2*) or by decomposition of magnesium anthracene · 3 THF (4). The decomposition of 4, with recovery of anthracene and THF, may be accomplished both thermally and by ultrasound in an organic solvent (toluene, n‐heptane) or thermally in the solid state in vacuo. Mg* obtained by the latter method exhibits only weak reflections in the X‐ray powder diagram and has, in comparison to other mentioned Mg* species, the highest reactivity toward hydrogen. Diverse Grignard compounds can be prepared under mild conditions (⪕25°C) in THF or ether as well as in hydrocarbons by using Mg* from MgH2* from MgH2* or 4. The cleavage of THF with formation of 1‐oxa‐2‐magnesiacyclohexane (2) is possible by employing Mg* from MgH2* or 4.
Kooperative Wirkung in π‐Ligand‐verbrückten Zweikernkomplexen, IX. Einfluß der Cp′XCp′‐Brücke in CpM(CO)3‐Zweikernkomplexen (M  Mo, W) auf die Reaktion mit Alkinen2
Authors: Abriel Walter , Baum Gerhard , Heck Jürgen , Kriebisch Karin‐Anke
Published: July 2007

Co‐operative Effect in π‐Ligand‐Bridged Dinuclear Complexes, IX. ‐ Influence of Cp′ ‐ X ‐ Cp′‐Bridged Dinuclear CpM(CO)3 Complexes (M  Mo. W) on Reactions with Alkynes

The Cp′  X  Cp′‐bridged dinuclear complexes Me2Si[Cp′M(CO)3)2 (4, Cp′  C5H4, M  Mo, W) react thermally as well as photochemically with alkynes RCCR′ to form the monoalkyne compounds {Me2Si(Cp′M(CO)2]2‐μ‐(η2:2‐RCCR′)} (6, 7, 9) which possess M2C2 dimetallatetrahedrane units (X‐ray structure analysis of 7a). A molecular fluxionality is shown for R  R′ (7) by NMR spectroscopy. The activation barrier for this process depends on the steric bulkiness of the alkyne substituents R. For this kind of dynamic behaviour a new mechanism is proposed. In the reaction of 4 (M  Mo) with the electron‐rich alkyne bis(diethylamino)ethyne (R  R′  NEt2) a novel bis(carbene) complex 8 is formed, which contains a 1,2‐dimetallacyclobutadiene core in the central M2C2 unit. In some cases products are isolated and characterized, in which three (R  Ph, 10) and two (R  nPr, 11) alkyne units are co‐ordinated under C ‐ C linkage. Based on spectroscopic results a structural proposal is made for 10. By X‐ray structure analysis of 11 it is shown that besides a dimerisation of the two alkynes an isomerisation occurs with formation of a complexed vinylallene.
Cycloadditionsreaktionen von Organometallkomplexen, XI. Cobalta‐Heterocyclen durch [2 + 3]‐Cycloaddition von α‐Ketocarbenen an Co‐CO‐ und Co‐ CNR‐Bindungen
Authors: Strecker Beate , Zeier Bernd , Schulz Michael , Wolf Justin , Werner Helmut
Published: July 2007

Cycloaddition Reactions of Organometallic Complexes, XI. ‐ Cobaltaheterocycles by [2 + 3) Cycloaddition of α‐Keto Carbenes to Co ‐ CO and Co ‐ CNR Bonds

The reactions of the carbonyl(cyclopentadienyl) and (cyclopentadienyl)isocyanidecobalt complexes C5H5Co(CO)(PR3) (1‐4) and C5H5Co(CNR)(PMe3) (5, 6) with α‐diazocarbonyl compounds R1C(O)C(N2)R2 lead to the formation of the cobaltaheterocycles C5H5(PR3)magnified image(O) (7‐12) and C5H5(PMe3)magnified image(NR) (13‐16), respectively. For R  (S)‐CH(Me)Ph a mixture of diastereoisomers RCoSCoSc is obtained. The complexes 13‐16 react with HBF4 in ether to give the cations [C5H5(PMe3)‐magnified image(NHR)]+ (17‐20, with BF4 as anion), which on treatment with base regenerate the uncharged cobaltaheterocycles. The X‐ray structural analysis of 19‐RCoSc reveals the presence of a planar CoOC3 five‐membered ring which presumably is formed by a [2+3] cycloaddition of an α‐ketocarbene to the CoCNR bond.
Alkinverbrückte Dreikerncluster mit Organo‐Rhodium‐Bausteinen
Authors: Albiez Thomas , Bantel Harald , Vahrenkamp Heinrich
Published: July 2007

Alkyne‐Bridged Trinuclear Clusters with Organo‐Rhodium Moieties

Several approaches are utilized to incorporate rhodium‐containing building blocks in alkyne‐bridged trinuclear clusters. The metal exchange procedure allows to introduce a Rh(CO)3 unit into cluster 1 with formation of RuMoRhCp(CO)8(μ‐MeCCMe (6). Starting from dinuclear alkyne‐bridged complexes, RhCp units are attached, as in Co2RhCp(CO)6(μ‐HCCR) (10, 11) and CoMoRhCpCp*(CO)5(μ‐HCCR) (12). Side reactions yield tetranuclear clusters with Co2Rh2 and Co3Rh frameworks.
Conformational effects in 2‐deoxyglucopyranos‐1‐yl radicals
Authors: Korth Hans‐Gert , Sustmann Reiner , Giese Bernd , Rückert Brigitte , Gröninger Kai Stefan
Published: July 2007

2‐Unsubstituted and 2‐substituted (fluoro, tosylamino, n‐propyl) 3,4,6‐tri‐O‐acetyl‐2‐deoxypyranosyl radicals are obtained by reaction of the corresponding pyranosyl bromides or phenylselenides with photolytically generated trimethyltin radicals in benzene solution. Analysis of the ESR hyperfine splittings reveals that the 2‐deoxy‐2‐fluoroglucopyranosyl radical exists in a boat‐like conformation at room temperature, whereas the others retain the 4C1 chair conformation of the starting material. The observed conformational effects are explained by a “quasi‐homo‐anomeric” frontier orbital interaction of the nx lone pair of the ring oxygen atom with the σ* MO of the β‐C‐O bond, in which the singly occupied p orbital at C‐1 acts as a mediator for this 1,3‐anomeric interaction.
Preparation and characterisation of 9,10‐dihydroanthracene and tert‐butyl‐9,10‐dihydroanthracene complexes with one or two tricarbonylchromium units; crystal structure of tricarbonyl (η1,2,3,4,4a,9a‐9,10‐dihydroanthracene)chromium
Authors: Whitton Alan J. , Kumberger Otto , Müller Gerhard , Schmidbaur Hubert
Published: July 2007

The complexes [9,10‐dihydroanthracene][tricarbonylchromium]n [9,10‐DHA][Cr(CO)3]n [n = 1 (1), 2 (2)] and the related mono‐ and bis(tricarbonylchromium) complexes of 2,6‐ and 2,7‐di‐tert‐butyl‐9,10‐dihydroanthrancene [2,6‐DB‐9,10‐DHA][Cr(CO)3]n [n = 1 (3), 2 (4)] and [2,7‐DB‐9,10‐DHA][Cr(CO)3]n [n = 1 (5), 2 (6)] have been prepared by heating the 9,10‐DHA species in the presence of hexacarbonylchromium [Cr(CO)6]. Evidence for the existence of the complex [2,6,9‐tri‐tert‐butyl‐9,10‐DHA][Cr(CO)3] (7) is also presented. The complexes have been characterised spectroscopically, and for complex 1 an X‐ray crystallographic structure determination has been carried out. This complex adopts the unexpected structure in which the non‐coordinated arene ring is bent towards the Cr(CO)3 moiety. The syntheses and spectroscopic characterisations of 2,6‐ and 2,7‐di‐tert‐butylanthracene (2,6‐ and 2,7‐DBA), 2,6‐ and 2,7‐di‐tert‐butyl‐9,10‐dihydroanthracene (2,6‐and 2,7‐DB‐9,10‐DHA), 2,6,9‐, 2,7,9‐, and 2,7,10‐tri‐tert‐butyl‐9,10‐dihydroanthracene (2,6,9‐, 2,7,9‐ and 2,7,10‐TB‐9,10‐DHA), and 2,6,9,10‐ and 2,7,9,10‐tetra‐tert‐butyl‐9,10‐dihydroanthracene(2,6,9,10‐ and 2,7,9,10‐TeB‐9,10‐DHA) are also given.
Cycloadditionen von 1,3,4‐Oxadiazin‐6‐onen (4,5‐Diaza‐α‐pyronen), 9. 6‐Oxo‐5‐phenyl‐1,3,4‐oxadiazin‐2‐carbonsäure‐methylester — Synthese und Reaktionen mit Norbornen, Norbornadien, Cyclopropenen, Cyclobuten und Benzvalen
Authors: Christl Manfred , Lanzendörfer Ulrike , Grötsch Maria M. , Ditterich Elke , Hegmann Joachim
Published: July 2007

Cycloadditions of 1,3,4‐Oxadiazin‐6‐ones (4,5‐Diaza‐a‐pyrones), 9. — Methyl 6‐0xo‐5‐phenyl‐1,3,4‐oxadiazin‐2‐carboxylate — Synthesis and Reactions with Norbornene, Norbornadiene. Cyclopropenes, Cyclobutene. and Benzvalene

Methyl 6‐oxo‐5‐phenyl‐1,3,4‐oxadiazin‐2‐carboxylate (7) was prepared by treatment of hydrazone 6 with dicyclohexylcarbodiimide. The reactions of 7 with norbornene and norbornadiene afforded the Diels‐Alder adducts 8 and 9, respectively, which decomposed in solution at 20°C to give mainly the γ‐oxoketenes 10 and 12 and small amounts of the β‐lactones 11 and 13, respectively. The stable γ‐oxoketenes 10, 12, and the bis(γ‐oxoketene) 14 were obtained directly from solutions of 7 and the respective olefin. Cyclopropene, 1‐methylcyclopropene, and cyclobutene were converted by 7 mainly into the oxepin derivatives 15, 17, 18 and the oxocin derivative 19, respectively. Benzvalene and 7 provided the tetracyclo[3.3.0.02,8.04,6]octanone 21. In these reactions, small quantities of β‐lactones were formed, too, which together with the β‐lactones 11 and 13 give evidence for the dihydropyryliumolates 24 as intermediates in the thermal denitrogenation of the Diels‐Alder adducts of 7, e.g. 8 and 9.
Concave reagents, 6. Can the structure of concave reagents determine selectivities?
Authors: Lüning Ulrich , Schillinger Fritz
Published: July 2007

The concave position of the proton in protonated concave pyridines 8·H+ or 9·H+ leads to increased selectivities in protonation reactions of nitronate anions 2a–d. Thus, the reprotonation of the nitronate anion 2a by the protonated concave pyridine 8·H+ selectively yields the nitro compound 1a whereas the nitronate anions 2b–d are transformed to the Net products 4b–d.
Titanocen‐ und Zirconocen(diazadien)‐Komplexe: Darstellung, Charakterisierung und Struktur
Authors: Scholz Joachim , Dlikan Mansour , Ströhl Dieter , Dietrich Andreas , Schumann Herbert , Thiele Karl‐Heinz
Published: July 2007

Titanocene‐ and Zirconocene(diazadiene) Complexes: Preparation, Characterization, and Structure

By treating Cp2MCl2 (M = Ti, Zr) with magnesium in the presence of the diazadienes R1N = CR2CR2  NR1 (R1  R2  Ph:1a; R1  Ph, R2  Me: 1b) metallocene complexes of formula Cp2) (M  Ti: 2a, b; M  Zr: 3a, b) have been obtained in good yields. 2a–3b exhibit dynamic NMR spectra indicating a rapid intramolecular migration of the bent metallocene unit Cp2M from one “face” of the reduced diazadiene to the other. From the 1H‐NMR Cp‐coalescence ΔG‡ values for the activation barrier of this automerization process have been obtained. Complex 3a was characterized by X‐ray diffraction. The five‐membered metallacyclic ZrNCCN ring system adopts an “envelope”‐conformation.
Über Reaktionen des 2,4,6‐Tris(trifluormethyl)phenols mit Verbindungen von Hauptgruppen‐ und Nebengruppen‐Elementen (Li, Na, Mg, Ca, Ba, Ge, Sn und Ti, W, Mn, Cd)
Authors: Roesky Herbert W. , Scholz Mario , Noltemeyer Mathias
Published: July 2007

Reactions of 2,4,6‐Tris(trifluoromethyl)phenols with Compounds of Main Group (Li, Na, Mg, Ca. Ba, Ge. Sn) and Transition (Ti, W, Mn, Cd) Elements

The 2,4,6‐tris(trifluoromethyl)phenoxides of composition RfONa · 1.5 THF (2), [Rf = 2,4,6‐(CF3)3C6H2], RfOLi · 0.75 Et2O (3), (RfO)2Mg · 3 THF (4), (RfO)2Ca · 3 THF (5), (RfO)2Ba · THF (6), (RfO)2 (7), (RfO)2Me2NWWNMe2(ORf)2 (8), (RfO)2Ge · THF (9), (RfO)2Sn · THF (10), (η5‐C5Me5)TiCl2ORf (11), (RfO)2Mn · 3 THF (12), and (RfO)2 · 2 THF (13) are prepared. The singlecrystal X‐ray structures of 4, 8, and 12 are described.
Molybdänkomplexe mit hochalkylierten Cyclopentadienyl‐Liganden
Authors: Sitzmann Helmut
Published: July 2007

Molybdenum Complexes with Highly Alkylated Cyclopentadienyl Ligands

Reaction of hexacarbonylmolybdenum with 1,2,3,4‐tetraisopropylcyclopentadiene gives [(η5‐C5iPr4H)Mo(CO)3H] (1), which on treatment with 2,5‐norbornadiene is dehydrogenated to [{(η5‐C5iPr4H)Mo(CO)2}2](Mo  Mo) (2). The mixed‐substituted dimolybdenum complex [(η5‐C5Me5)(CO)2Mo  Mo(CO)2(η5‐C5iPr4H)] (6) is accessible, e.g., from [(η5‐C5Me5)Mo(CO)3Cl] and [(η5‐C5iPr4H)Mo(CO)3]Na (3). Complex 3 yields [(η5‐C5iPr4H)Mo(CO)3Cl] (4) with CuCl2 and [(η5‐C5iPr4H)Mo(CO)3‐SiHMe2] (5) with Me2HSiCl. Low‐temperature 1H‐NMR spectra of [(η5‐C5iPr5)Mo(CO)3CH3] (7), synthesized from [(η5‐C5iPr5)Mo(CO)3]Na and MeI, show the signals of two isomers with different orientation of the isopropyl groups about the five‐membered ring. ΔG‡ of isopropyl rotation has been calculated to be 55.6 ± 4 kJ/mol. [(η5‐C5H2tBu3‐1,2,4)Mo(CO)3]Na reacts with MeI to form [(η5‐C5H2tBu3 ‐1,2,4)Mo(CO)3CH3] (8).
Metall‐π‐Komplexe von Benzolderivaten, 36. Zur Kenntnis der Struktur von μ(η6:η6‐Biphenyl)bis[(η6‐benzol)metall]‐Komplexen in starrer Lösung und im Kristall
Authors: Elschenbroich Christoph , Heck Jürgen , Massa Werner , Birkhahn Matthias
Published: July 2007

Metal π‐Complexes of Benzene Derivatives, 36. — The Structure of μ(η6:η6‐Biphenyl)bis[(η6‐benzene)metal] Complexes in Rigid Solution and in the Crystalline State

For μ(η6:η6‐C6H5C6H5)[η6‐C6H6)Cr]2 (2) an antiperiplanar conformation has been established by means of X‐ray diffraction. Two (C6H6)Cr units coordinate to planar bridging biphenyl. This configuration differs from that of the diradical dication 2d⊕ d⊕ in rigid solution. According to the zero‐field splitting parameter D in the EPR spectrum, 2d⊕ d⊕ adopts a synclinal conformation, the half‐sandwich fragments coordinating to twisted biphenyl (dihedral angle α ≈︁ 60°).
Bis[tris(trimethylsilyl)methyl]diselenid: Ein ungewöhnliches Dichalkogenid mit sterisch erzwungener trans‐C2h‐Konformation
Authors: Wagner Irle , Du Mont Wolf‐Walther , Pohl Siegfried , Saak Wolfgang
Published: July 2007

Bis[tris(trimethylsilyl)methyl] Diselenide: An Unusual Diselenide with Sterically Enforced trans‐C2h Conformation

Deselenation of bis[tris(trimethylsilyl)methyl] triselenide (1) with copper occurs with formation of bis[tris(trimethylsilyl)‐methyl] diselenide (2) and minor amounts of 3,3,5,5‐tetrakis(trimethylsilyl)‐1,2,4‐triselenolane (3). The structures of 2 and 3 have been studied by multinuclear NMR spectroscopy and by X‐ray crystallography. The CSeSeC moiety of 2 adopts an unusual antiperiplanar conformation. Cleavage of the Se  Se bond by iodine providing iodo[tris(trimethylsilyl)‐methyl]selane (5) is complete with 2, but reversible with 1.
Direkte Michael‐artige Addition von Si‐Gruppen an β‐Aryl‐α,β‐ungesättigte Carbonylverbindungen mit R3SiCl/Bu2Cu(CN)Li2
Authors: Amberg Willi , Seebach Dieter
Published: July 2007

Direct Michael‐Type Addition of Si‐Groups to α,β‐Unsaturated p‐Aryl‐Substituted Enones with R3SiCl/Bu2Cu(CN)Li2

(E)‐5‐Benzylidene‐2‐tert‐butyl‐6‐methyl‐1,3‐dioxan‐4‐one (1) undergoes conjugative silylation (Me3Si, Et3Si, tBuMe2Si, Me2PhSi, products 2 ‐ 5) with the reagent specified in the title. The reaction is highly diastereoselective, with formal anti addition of R3Si and H from the Re‐ and Si‐face, respectively, of the exocyclic double bond [proof by NMR analysis and chemical correlation (cf. 6 and 7). A screening of various enone systems showed that this unprecedented Michael addition of Si groups with chlorosilane as a reagent, and under non‐reducing conditions occurs only if the x,p‐unsaturated carbonyl system bears an aryl group in the P‐position to give β‐aryl β‐silyl ketones (products 8‐ 15).
Photochemische Reaktionen von Übergangsmetall‐Organyl‐Komplexen mit Olefinen, 3. [4 + 5]‐Cycloaddition konjugierter Diene an Tricarbonyl(η5‐2,4‐dimethyl‐2,4‐pentadienyl)mangan
Authors: Kreiter Cornelius G. , Lehr Klaus , Leyendecker Michael , Sheldrick William S. , Exner Reiner
Published: July 2007

Photochemical Reactions of Transition Metal Organyl Complexes with Olefines, 31). – [4 + 5] Cycloaddition of Conjugated Dienes to Tricarbonyl(η5‐2,4‐dimethyl‐2,4‐pentadienyl)manganese

Tricarbonyl(η5‐2,4‐dimethyl‐2,4‐pentadienyl)manganese [1] reacts photochemically with the acyclic conjugated dienes 1,3‐butadiene [A], 2‐methyl‐1,3‐butadiene [B], (E)‐1,3‐pentadiene (C), (E,E)‐2,4‐hexadiene (D), 2,4‐dimethyl‐1,3‐pentadiene (E), 2,4‐hexadien‐1‐ol (F), and methyl 2,4‐hexadienoate (G) in a formal [4 + 5] cycloaddition to give tricarbonylmanganese complexes with η3:2‐2,6‐cyclononadien‐1‐yl ligands (2A‐2G). In addition, the reaction of 1 with A yields thermolabile [η3:2:2‐1‐(3‐butene‐1,2‐diyl)‐1,3‐dimethyl‐2,6‐cyclononadiene]dicarbonylmanganese (3A) and E,E and E,Z isomers of [η3‐1‐(2‐butene‐1,1‐diyl)‐1,3‐dimethyl‐2,6‐cyclononadiene]tetracarbonylmanganese (4A, 4A] as byproducts. Similarly, 1 reacts with B to form tetracarbonyl[η3‐1‐(3‐methyl‐2‐butene‐1,1‐diyl)‐1,3,6‐trimethyl1‐2,6‐cyclononadiene]manganese (4B) in a side reaction. The crystal and molecular structures of tricarbonyl(η3:2‐1,3,5,5,7‐pentamethyl‐2,6‐cyclononadien‐1‐yl]manganese (2E) and of 3A are determined by X‐ray structure analyses. In each of the formally octahedral complexes unusual long manganese–carbon bonds are found for one coordinated CC double bond of the hydrocarbon ligands.
Notizen / Notes. Investigation on the Product from Monobutyltin(IV) Compounds and Benzoyl(thiobenzoyl)methane: a 1,3,2λ5,4λ5‐Dithiadistannetane
Authors: Seth Neena , Gupta Vishnu D. , Linti Gerald , Nöth Heinrich
Published: July 2007

Butyltin triisopropoxide reacts with benzoyl(thiobenzoyl)methane (LH) to yield BuSn(S)L and an organic sulfide 2 instead of the expected BuSnL3. The use of other butyltin(IV) starting materials invariably leads to the same products. From an X‐ray structure determination the tin sulfido complex is found to be a centrosymmetric dimer, [BuSn(S)L]2 (1) with a planar four‐membered Sn2S2 ring containing pentacoordinated tin atoms.
Elektrochemische und spektroskopische Charakterisierung von N,N′‐Dialkylchinoxalinium‐Redoxsystemen
Authors: Schulz Andreas , Kaim Wolfgang
Published: July 2007

Electrochemical and Spectroscopic Characterization of N,N′‐Dialkylquinoxalinium Redox Systems

The outstanding position of the 1,4‐isomer, quinoxaline, among the diazanaphthalenes is confirmed by comparing LUMO energies from HMO perturbation calculations. Diquaternary salts [(R+)2(quin)](X−)2, R = Me, Et; quin = quinoxaline, 2,3‐ and 6,7‐dimethyl‐ and 2,3,6,7‐tetramethylquinoxaline, X− = BF4‐ or SbCl6‐ (4a – g), were isolated and characterized as compounds which are sensitive to reduction and hydrolysis. Cyclic voltammetry of the two‐step redox systems of the Weitz type showed two reversible one‐electron reductions with an extraordinarily stable radical cation intermediate (lg Kc 12). The redox potentials are less negative than those of the 4,4′‐bipyridinium systems but also less positive in comparison to the values of N,N′‐dialkylphenazinium compounds. The radical cation intermediates which include a TCNQ− salt cannot only be characterized by ESR, but also by absorption spectroscopy in comparison to the respective dications.
Borogranyle, II1,2) Darstellung, Struktur und Reaktionen von Lithium‐[cyan(triphenyl‐phosphoranyliden)methyl]trihydroborat(‐1)
Authors: Bestmann Hans Jürgen , Röder Thomas , Bremer Matthias , Löw Dieter
Published: July 2007

Organoboron Compounds, II1,2) – Preparation, Structure, and Reactions of Lithium [Cyano(triphenylphosphoranylidene)‐methyl]trihydroborate(‐1)

(Cyanomethylene)triphenylphosphorane (5) adds borane (from 2) with formation of phosphorane‐borane 6, which cannot be rearranged. 6 reacts with butyllithium to afford a crystalline lithium compound 9, which contains four tetrahydrofuran molecules. The X‐ray structure analysis of 9 is reported, 9 is acting as a reducing agent towards halogeno and carbonyl compounds.
Trioxypentafulvenes, 2 synthesis of 1‐substituted 2,3,6‐trioxypentafulvenes
Authors: Victory Pedro , Alvarez‐Larena Angel , Beti Carlos , Borrell Joséa I. , Batllori Xavier , Córdoba Carlos
Published: July 2007

Syntheses of 2,3,6‐trioxypentafulvenes with a free position at the ring are described, in which the protection of the C‐3 hydroxy group as methoxy or acetoxy derivative has been required. The difference in the behavior of the title compounds in relation to the previously reported 1,4‐disubstituted 2,3,6‐trihydroxypentafulvenes 2a‐e, which only exhibit enol forms, is discussed and attributed to the disappearance of the push‐pull system formed by the C‐3 enol group and the C‐4 electron‐withdrawing substituent.
Regio‐, Diastereo‐, and Enantioselective Synthesis of vic‐Diols via α‐Silyl Ketones According to the SAMP/RAMP Hydrazone Method
Authors: Enders Dieter , Nakai Shiro
Published: July 2007

α‐Silylated ketones 5 or 10 of high enantiomeric purity (ee ≥ 90%) are easily available by silylation or silylation/alkylation of ketones 1 or 6, resp., according to the SAMP/RAMP hydrazone method. Reduction of 5 or 10 with L‐selectride™, followed by oxidative cleavage of the C–Si bond, leads to vic‐diols 11–13 with high diastereoselectivity (de ≥ 90%) and without racemization. The stereoselectivity of the reduction depends on the structure of the α‐silyl ketones 5 or 10, the reducing reagents, and the solvents used.
Synthese und Struktur eines Imino(phosphoranylidenmethyl)phosphans: Ein neues Hetero‐Allyl‐Anion
Authors: Krüger Uwe , Pritzkow Hans , Grützmacher Hansjörg
Published: July 2007

Synthesis and Structure of an Imino(phosphoranylidenemethyl)phosphine: A New Hetero Allyl Anion

Reaction of the (dichlorophosphinyl)methylphosphonium salt 1 with three equivalents of sodium bis(trimethylsilyl)amide (2) in THF at – 78°C leads to the P‐(phosphoranylidenemethyl)‐substituted iminophosphine 4. Compound 4 is probably formed via 3 by 1,3‐silyl migration. According to an X‐ray analysis, 4 can be described as a hetero allyl anion with a 3‐ center‐4‐electron bond C1–P1–N1. Oxidative addition of sulfur or selenium results in formation of the imino(thioxo)phosphorane 8 or imino(selenoxo)phosphorane 9.
Synthesis and Dynamic Behaviour of [7]‐ and [8]Metacyclophanes
Authors: Takeshita Michinori , Tsuge Akihiko , Tashiro Masashi
Published: July 2007

The synthesis and structure of [7]‐ and [8]metacyclophanes 2, 4 are described. The reductive ring opening of the thiophene rings of [2]metacyclo[2](2,4)‐ and ‐(2,5)thiophenophanes 1 and 3 by Raney‐Ni affords the corresponding [7]‐ and [8]metacyclophanes 2 and 4, respectively. Two types of motion have been observed for the methylene chain of [8]metacyclophane 4c, flipping and pseudorotation.
Darstellung von dreikernigen Carbonylmanganaten sowie deren Reaktionsprodukten mit InCl3; Röntgenstrukturanalysen von K3[Mn3(μ‐CO)2(CO)10], [(C6H5)4As]2[(μ‐H)Mn3(μ‐CO)10], [{(C6H5)3P}2N]2[μ‐H)Mn3(CO)12], [(C6H5)4As]2[{μ‐H)Mn3(CO)12}2(μ4‐In)] und [(C6H5)4As]2[{(μ‐H)Mn3(CO)12}(μ3‐In){Mn(CO)5}Cl]
Authors: Schatz Wolfgang , Neumann Hans‐Peter , Nuber Bernhard , Ziegler Manfred L. , Kanellakopulos Basil
Published: July 2007

Synthesis of Trinuclear Carbonylmanganates and Their Reaction Products with InCl3; X‐ray Structure Determinations of K3[Mn3(μ‐CO)2(CO)10], [(C6H5)4As]2[(μ‐H)Mn3(μ‐CO)10], [{(C6H5)3P}2N]2[μ‐H)Mn3(CO)12], [(C6H5)4As]2[{μ‐H)Mn3(CO)12}2(μ4‐In)] und [(C6H5)4As]2[{(μ‐H)Mn3(CO)12}(μ3‐In){Mn(CO)5}Cl]

Mn2(CO)10 reacts with KOH in aqueous solution to give the potassium carbonylmanganate K3[Mn3(μ‐CO)2(CO)10] (1). The trianion 1 is isoelectronic with Fe3(CO)12 and is protonated with methanol to form the μ‐hydrido cluster [(μ‐H)Mn3;‐(CO)12]3⊖, which is precipitated with [{(C6H5)3P}2N]Cl as [{(C6H5)3P}2N]2[(μ‐H)Mn3(CO)12] (2), whereas the carbonyl‐bridged μ‐hydrido species [(μ‐H)Mn3(μ‐CO)2(CO)10]2⊖ seems to be trapped as the [(C6H5)4As]⊕ salt 3. The reaction of 3 with InCl3 yields the Mn‐In clusters [(C6H5)4As]2[{(μ‐H)Mn3(CO)12}2;‐(μ4‐In) (4) and [(C6H5)4As]2[{(μ‐H)Mn3(CO)12}(μ3‐In){Mn(CO)5}Cl] (5). X‐ray structure analyses have been carried out for the compounds 1 – 5.
Synthese und Reaktionen von Eisen‐Clustern mit μ3;‐λ2‐koordiniertem Trifluormethylisocyanid‐Liganden. Bildung eines N;‐(Trifluormethyl)‐formimidoyl‐Liganden
Authors: Lentz Dieter , Marschall Robert
Published: July 2007

Syntheses and Reactions of Iron Cluster Compounds with a μ3;‐λ2‐Coordinated Trifluoromethyl Isocyanide Ligand. Formation of an N;‐(Trifluoromethylformimidoyl Ligand

Pyrolysis of the iron clusters Fe3(CO)10(L)(μ2‐CNCF3) (1a – d) [LP(OCH3)3 a, P(OC2H5)3 b, P(CH3)3 c, P(C2H5)3 d] in n‐heptane at 95°C results in the reversible elimination of two mol of carbon monoxide and formation of the cluster compounds Fe3(CO)8(μ3;‐λ2‐CNCF3)L (2a–d). According to the crystal structure determination of 2a trifluoromethyl isocyanide acts as a μ3;‐λ2‐bridging ligand with its CN bond perpendicular to one iron‐iron edge. 2a reacts with molecular hydrogen to yield Fe3(CO)8(L)(μ3;‐λ2‐HCNCF3)(μ2‐H) (3a) containing a μ3;‐λ2;‐N;‐(trifluoromethyl)formimidoyl ligand. 3a exists as a mixture of three isomers. The isomerization of two of these isomers is studied by variable temperature 1H‐, 19F‐, and 31P‐NMR spectroscopy. Reaction of 2a with NaBH4 leads to the ionic cluster Na[Fe3(CO)8(L)(μ3;‐λ2‐HCNCF3)] (4a), which yields 3a on protonation with trifluoroacetic acid.
Steuerung der Aggregation von Mangankomplexen durch unterschiedliche Basen an den Beispielen [Mn(O2CCF3)2(py)4] und [Mn3(O2CCF3)6(benz)6]
Authors: Hübner Kay , Roesky Herbert W. , Noltemeyer Mathias , Bohra Rakesh
Published: July 2007

Influencing the Aggregation of Manganese Complexes by Different Bases: Formation of [Mn(O2CCF3)2(py)4] and [Mn3(O2CCF3)6(benz)6]

Manganese powder reacts quantitatively with trifluoroacetic acid to yield Mn(O2CCF3)2 (1). The aggregation of 1 is directed by different N‐containing bases. Pyridine (py) forms the mono‐nuclear complex [Mn(O2CCF3)2(py)4] (2), while benzonitrile (benz) yields the trinuclear complex [Mn3(O2CCF3)6(benz)6] (3). The X‐ray structures of 2 and 3 are described.
Synthesen neuer Azofarbstoffe mit 1,6‐Methano[10]annulen‐Partialstruktur
Authors: Neidlein Richard , Lu Yinrong
Published: July 2007

Synthesis of New Azo Dyes with 1,6‐Methano[10]annulene Partial Structure

Bridged quinone hydrazones 1 are transformed by aromatic acyl chlorides to the corresponding azo dyes 3a –6. Nitro derivative 1a reacts analogously with p‐tolylsulfonyl chloride, acetyl chloride, methyl chlorocarbonate, and dimethylcarbamoyl chloride to give the corresponding azo dyes 7 and 8a –c. Reaction of 1a with diphenylcarbamoyl chloride unexpectedly leads to Berson‐Wilcott rearrangement with formation of the azo dye 9. Acylations of 1a with the bifunctional acyl chlorides diphosgene and terephthaloyl chloride yield the azo derivatives 11 and 12.
The Conformational Behaviour of 10‐Substituted Spiro[4.5]decanes
Authors: Jens Wolff J. , Frenking Gernot , Harms Klaus
Published: July 2007

The conformational behaviour of 10‐X‐substituted 1,4‐dioxa‐and 1,4,6‐trioxaspiro[4.5]decanes 1 – 4 has been studied by 13C‐, 19F‐ and 1H‐NMR spectroscopy. Two X‐ray analyses (of 2a,e) are presented, and their implications to cleavage reactions of chiral acetals are discussed. Participation of twist boat forms in the conformeric equilibrium of at least 1c has been made plausible by observing 13C,19F‐NMR coupling constants. The ratios of axial to equatorial conformer in 1 – 4 have been calculated by molecular mechanics.
Synthese von 1,2,5‐Azastannaborol‐Derivaten aus Schwefeldiimid‐Anionen und cis‐Stannyl‐boryl‐alkenen – Röntgenstrukturanalyse von zwei 2,5‐Dihydro‐1‐(imino‐λ4‐sulfanyliden)‐1,2,5‐azastannaboratolen
Authors: Wrackmeyer Bernd , Frank Stefan M. , Herberhold Max , Borrmann Horst , Simon Arndt
Published: July 2007

Synthesis of 1,2,5‐Azastannaborole Derivatives from Sulfur Diimide Anions and cis‐Stannyl‐boryl‐alkenes – X‐ray Crystallographic Study of Two 2,5‐Dihydro‐1‐(imino‐λ4‐sulfanylidene)‐1,2,5‐azastannaboratoles

(E)‐3‐(Diethylboryl)‐2‐(chlorodimethylstannyl)‐2‐pentene (1) reacts with the sulfur diimide anions 3 [R – NSN−K+, R=tBu (a), Me3Si (b), tBu2P (c)] in a 1:1 ratio, and with 4 (K+;−NSN−K+) in a 2:1 ratio, to give various heterocycles. The first products of the reaction between 1 and 3 [2,5‐dihydro‐1‐(imino‐λ4‐sulfanylidene)‐1,2,5‐azastannaboratoles 5a, b, c] are isolated at −30°C and characterized by X‐ray crystallography. The compounds 5a,b rearrange into the borole derivates 6a,b (with an additional NSn coordination) by transfer of an ethyl group from the boron to the sulfur atom. Ethylene is eliminated from compound 6a (not 6b) to give the diaminosulfane derivative 7a. The 2:1 reaction between 1 and 4 affords an unstable intermediate 8 with a fluxional structure, leading to 9 in which an EtS moiety bridges a borole ring (analogous to 6 but without the additional N – Sn coordination) and a boratole ring (analogous to 5). All compounds are characterized by 1H‐, 11B‐, 13C‐, 15N‐ (in part), 29Si‐ and 119Sn‐NMR spectra.
Small and Medium Rings, 76. Photorearrangement of Polycyclic Quinoxalines, Isomerisations of Isodrin‐Type and Aza‐Di‐π‐Methane Chromophores
Authors: Behr Jürgen , Braun Ralf , Martin Hans‐Dieter , Steigel Alois , Rubin Mordecai B.
Published: July 2007

The multichromophoric polycyclic quinoxaline 11 has been synthesized starting with diketone 7. Irrespective of whether quinoxaline 11 is irradiated in its nπ☆ or ππ☆ band, the photoproduct formed in high yield is invariably the cage compound 14. This excitation energy transfer from the quinoxaline to the isodrin subchromophore of 11 is facilitated by a strong mixing of energy levels in these two fragments of 11, as evidenced by the PE spectrum of quinoxaline 13. The direct interaction of a quinoxaline chromophore with a nonconjugated double bond, i.e. an aza‐di‐π‐methane rearrangement, is shown to occur photochemically in bicyclic quinoxaline 12.