bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoreduction on Irradiation of 3,3,5,5‐Tetramethyl‐4‐methylene‐1‐pyrazoline. — An Overlooked Example of a Reaction Competing with the Extrusion of Molecular Nitrogen from Reluctant Azoalkanes
Authors: Quast Helmut , Jakobi Harald
Published: July 2007

The photolysis of the 4‐methylene‐1‐pyrazoline 1 is reinvestigated under a variety of experimental conditions. Direct irradiation (350‐nm light) affords the alkylidenecyclopropanes 4 and 5 as predominant products, besides molecular nitrogen, and in a constant ratio of (55 ± 1): (45 ∓ 1), which is not altered in the presence of 1,4‐diazabicyclo[2.2.2]octane (DABCO) or piperylene nor in [D6]acetone solution. When oxygen is excluded, an additional compound is formed whose proportion depends on the capability of the solvent to act as hydrogen donor. In the presence of three equivalents of DABCO, it eventually becomes the major product. The 4‐methylenepyrazolidine structure 13 of the novel photoproduct is established by NMR spectroscopy, a comparison with an authentic sample, obtained in quantitative yield by zinc reduction of 1, and reoxidation to 1 as well. An extensive investigation to detect any traces of the 4‐isopropylidene‐2‐pyrazoline 6 in the irradiated solutions has failed. This result is at variance with recent disclosures reporting evidence for a turnaround photoisomerization of 1 via diazenylallyl diradicals. The contribution of photoreduction to the decay of the first excited singlet state of reluctant azo compounds is emphasized.
Carbodesilylierung von (Trimethylsilyl)imidazolen und ‐pyrazolen
Authors: Effenberger Franz , Roos Michael , Ahmad Roshan , Krebs Andreas
Published: July 2007

Carbodesilylation of (Trimethylsilyl)imidazoles and ‐pyrazoles

The preparation of the 1‐methyl(trimethylsilyl) (TMS)‐substituted imidazoles 3a, 4a, 8, 9, and 11a by silylation of the corresponding metallated imidazoles is described. Carbodesilylation of 3 with aldehydes or carboxylic halogenides occurs selectively in 2‐position. In the presence of a strong base (CsF) the reactivity against carbon electrophiles correlates well with the stability of the imidazolyl anions; regioselective carbodesilylation in 2‐, 5‐, or 4‐position of the twofold TMS‐substituted imidazoles 3a and 9 therefore is possible, which allows the synthesis of a great variety of hydroxyalkyl‐substituted imidazoles and of acylimidazoles. By using the dimethylsulfamoyl substituent as an N‐protecting group, the N‐ unsubstituted 5‐benzoylimidazole (26) as well as the comparable 5‐benzoyl‐pyrazole (30b) and 5‐(hydroxyphenylmethyl)‐pyrazole (30a) are accessible.
Generation and Fate of 1‐Dewar‐pyridin‐3‐olates and ‐2‐olates. Synthesis of 1‐Dewar‐pyridin‐3‐ones
Authors: Maas Gerhard , Rahm Rainer , Krebs Fred , Regitz Manfred , Stang Peter J. , Crittell Charles M.
Published: July 2007

3‐Oxy‐1‐azabicyclo[2.2.0]hexa‐2,5‐dienes (“3‐oxy‐1‐Dewar‐pyridines”) 6a–d, on cleavage of the enol ether or enol ester function, yield either 1‐azabicyclo[2.2.0]hex‐2‐en‐5‐ones (“1‐Dewar‐pyridin‐3‐ones”) 9 or 2‐azabicyclo[3.1.0]hex‐2‐en‐4‐ones 11, depending on the substituents and reaction conditions. Ester cleavage of 2‐(benzoyloxy)‐1‐Dewar‐pyridine 7a with methyllithium does not furnish a 1‐Dewar‐2‐pyridinone, but a dimer thereof, namely the tricyclic compound 14.
Medizinisch interessante Metallchelate, VI Synthese eines tripodalen Triisocyanid‐Liganden und seine Reaktion mit Na[99mTcO4]
Authors: Ekkehardt Hahn F. , Tamm Matthias , Dittler‐Klingemann Andreas , Neumeier Reinhard
Published: July 2007

Metal Chelates of Medical Interest, VI. – Synthesis of a Tripodal Triisocyanide Ligand and its Reaction with Na[99mTcO4]

The tripodal triisocyanide ligand tris[3‐(2‐isocyanophenoxy)‐ propyl]amine, TARC (6), is prepared from tris(3‐chloropropyl)‐ amine (1) and the potassium salt of 2‐nitrophenole followed by reduction of the nitro functions and conversion of the primary amines into isocyanide functions by the method of Ugi et al. The structure of the intermediate tris[3‐(2‐nitrophenoxy)‐ propyl]amine (3) has been determined by X‐ray diffraction. Tripode 6 binds 99mTc from nuclide generator‐produced Na[99mTcO4].
(1,1′,3,3′‐Tetra‐tert‐butyl‐5,5′‐pentafulvalen) dithallium – Synthese und Kristallstruktur: Ein Beitrag zur Diskussion von nichtklassischen Thallium‐Thallium‐Wechselwirkungen
Authors: Jutzi Peter , Schnittger Jörg , Hursthouse Mike B.
Published: July 2007

(1,1′,3,3′‐Tetra‐tert‐butyl‐5,5′‐pentafulvalene)dithallium – Synthesis and Crystal Structure: a Contribution to the Discussion of Nonclassical TI(I)‐TI(I) Interactions

Reaction of 1,1′,3,3′‐tetra‐tert‐butyl‐5,5′‐dihydropentafulvalenediyldilithium with stoichiometric amounts of thallium chloride affords the dinuclear complex (η5:(η5‐tBu4C10H4)Tl2 (2). Compound 2 is air‐and moisture‐sensitive, and photolabile. It crystallizes in the space group P•1 and consists of two (cyclopentadienyl)thallium units which are connected by a central C‐C bond and twisted against each other by 70°. The monomeric units of 2 form a two‐dimensional polymer with a zick‐zack chain of T1 atoms and a periphery of substituted cyclopentadienyl ligands. Rather short T1‐T1 contacts of 3.760 and 3.998 Å are formed within a dimeric substructure. The geometry of the cyclopentadienyl ligands around the shortest T1‐T1 bond is similar to that predicted by the theory for weak T1‐T1 interactions.
Structures of Tris(donor)‐Tris(acceptor)‐Substituted Benzenes, 2.Potassium Salts of Trinitrophloroglucinol
Authors: Jens Wolff J. , Nelsen Stephen F. , Powell Douglas R. , Desper John M.
Published: July 2007

The X‐ray crystallographic analysis of the mono‐, di‐, and tri‐potassium salts 2b – d of trinitrophloroglucinol (2a) show their benzene rings to become considerably more distorted on successive deprotonation. A parallel increase in C – C, and a decrease in C – O and C – N bond lengths leading to a radialenetype structure is also observed. For 2b, two chemically different molecules are found in the crystal which differ in their hydrogen‐bond pattern as well as in their average bond lengths and deviation of their benzene rings from planarity. AM1 calculations show that for 2b,d a multitude of structures, differing widely in the deviation of their benzene cores form planarity, can exist within a small energy range ( < 3 kcal/mol). The experimental and computational results are discussed in terms of a model that emphasizes “push‐pull” interactions as the main cause for the distortions of the benzene rings in compounds of type 1 and 2.
Funktionalisierte Octabisvalene
Authors: Trupp BjöRn , Handreck Dirk‐Rainer , Böhm Hans‐Peter , Knothe Lothar , Fritz Hans , Prinzbach Horst
Published: July 2007

Functionalized Octabisvalenes

Quadricyclanone (13) is the starting material for a five‐step synthesis of 3‐cyanooctabisvalene (24, 19% total yield), cyclooctatetraene for a six‐step synthesis of (Z)‐3,7‐dicyanooctabisvalene (58, 7% total yield). By decyanation of 24, the parent octabisvalene (1) is produced. NMR data, including 13C,13C coupling constants, are presented.
Organische Synthesen mit übergangsmetall‐Komplexen, 52 N‐Vinylaminocarben‐ und N‐(2‐Propenyl)aminocarben‐Komplexe durch Addition von Keteniminen an Carben‐Eisenkomplexe
Authors: Aumann Rudolf , Trentmann Beate , Dartmann Mechtild , Krebs Bernt
Published: July 2007

Organic Syntheses with Transition Metal Complexes, 52 1). ‐ N‐Vinylaminocarbene and N‐(2‐Propenyl)aminocarbene Complexes by Addition of Ketene Imines to Carbene Iron Complexes

Ketene imines R(Me)C = C = NPh (2, R = Me, Et, i‐Pr) form 1 : 1 adducts with the carbene iron complex (CO)4,FeC(OEt)Ph (1). The initial step of the reaction involves an attack of the nitrogen atom of 2 at the carbene carbon atom of 1 and a subsequent rearrangement to give N‐vinylaminocarbene complexes (E/Z)‐4. In a parallel process with different regiochemistry the central carbon of the CCN unit is attached to the carbene carbon to yield π‐allyl,σ‐complexes (E/Z)‐3. Alkylation of 3a with [Et3O]BF4 leads to the formation of a cationic N‐(2‐propenyl)‐aminocarbene complex 6a. Protonation of 4 with trifluoroacetic acid results in a ring contraction to give the four‐membered metallacycles 7. X‐ray data are reported for prototypes (Z)‐4c and 6a.
Photo Valence Isomerization of 8,9‐Bis(N‐cyclohexylcarbamoyloxymethyl)‐[6]paracyclophane
Authors: Bockisch Frank , Dreeskamp Herbert , Von Haugwitz Thilo , Tochtermann Werner
Published: July 2007

Irradiation in the wavelength range of λ = 270 ‐ 320 nm of 8,9‐bis(N‐cyclohexylcarbamoyloxymethyl)‐[6]paracyclophane(1b) in dilute fluid solutions produces the 1,4‐Dewar isomer 2b in a quantum yield of 2.8% while the quantum yield of the rearomatization is 19% in heptane at room temperature. A photostationary equilibrium may be attained which depends strongly on the wavelength of irradiation. At λ = 290 nm 76% of the [6]paracyclophane isomer 1b is obtained whereas at λ = 310 nm 83% of the Dewar isomer 2b is formed in ethanol. The thermal back reaction 2b → 1b follows the Arrhenius law (Ea = 95.9 ± 4.0 kJ/mol, lg A = 10.6 ± 0.4 in heptane). By irradiating 1b with λ < 270 nm the prismane isomer 3b is formed via the Dewar isomer 2b.
Notizen/Notes Kronenether aus o‐Chinondiaziden und Oxetan
Authors: Kirmse Wolfgang , Lelgemann Rudolf
Published: July 2007

Crown Ethers from o‐Quinone Diazides and Oxetane

The carbenes 11, generated by photolysis of the di‐ and tetrachloro‐o‐quinone diazides 10, react with oxetane in a 1:3 ratio to give the 15‐membered crown ethers 19. In the presence of methanol, the oxonium ions 12 are trapped with formation of 1‐(aryloxy)‐3‐methoxypropanes (13). In the absence of additional nucleophiles, 12 reacts with oxetane until the chain length is appropriate for inverting intramolecular attack of the aryl oxide at the α‐carbon atom of the oxonium ion (18 → 19).
Tripeldecker‐Komplexe, VIII. Elektrophile Aufstockungsreaktionen von Borataferrocen‐ und Bis(borol)cobaltat‐Ionen mit Tricarbonylmetall‐Fragmenten der Chrom‐ und Mangan‐Gruppe
Authors: Herberich Gerhard E. , Köffer Dieter P. J. , Peters Karl M.
Published: July 2007

Tripledecker Complexes, VIII. — Electrophilic Stacking Reactions of Borataferrocene and Bis(borole)cobaltate Ions with Tricarbonylmetal Fragments of Chromium and Manganese Group Metals

Bis(borole)cobaltate ions [CoL2]‐ (1‐) and borataferrocene ions [CpFeL]‐ (2‐) (a: L = C4H4BMe; b: L = C4H4BPh) readily undergo stacking reactions. When treated with sources of chromium group M(CO)3 fragments, 1b‐ and 2b‐ form 30‐e tripledecked anions [μ‐L(CoL){M(CO)3}]‐ (M = Cr, Mo, W) (3‐ ‐ 5‐) and [μ‐L(FeCp){M(CO)3}]‐ (M = Cr, Mo, W) (6‐‐8‐). These 30‐e anions are very sensitive to nucleophilic degradation by e.g. water, acetonitrile and to a lesser extent acetone. Cyclic voltammetry reveals a reversible oxidation of 6‐ to give the 29‐e neutral tripledecker complex μ‐ L(FeCp)[Cr(CO)3] (6), while the oxidation of the higher homologues is fully irreversible. Protonation of 6‐ ‐8‐ affords hydrido complexes μ‐L(FeCp)[MH(CO)3] (M = Cr, Mo, W) (9–11), and, with PhCH2Br, the benzyl derivate μ‐L(FeCp)‐[W(CO)3(CH2Ph)] (12) is produced. Similar stacking reactions with manganese group M(CO)3 fragments produce neutral tripledecked complexes as e.g. μ‐L(CoL)[Re(CO)3] (14) (L = C4H4BPh). In the case of the reaction of [CpFeL]‐ (2‐) with [Mn(CO)3(NCMe)3]3]PF6 symmetric tripledecker compounds μ‐L[Mn(CO)3]2 (15a,b) and μ‐L(FeCp)2 (16a,b) are formed in a novel dismutation reaction (a: L = C4H4BMe; b: L = C4H4BPh).
Vinyliden‐übergangsmetallkomplexe, XVII. Synthese von trans‐[IrCl(=C=CH2)(PR3)2] (PR3 = PMetBu2, PPh3), [IrHCl(CCPh)(PMe2tBu)3] und einigen Dihydridoiridium(III)‐Komplexen
Authors: Werner Helmut , Dirnberger Thomas , Höhn Arthur
Published: July 2007

Vinylidene Transition‐Metal Complexes, XVII. — Synthesis of trans‐[IrCl(=C=CH2)(PR3)2] (PR3 = PMetBu2, PPh3), [IrHCl(CCPh)(PMe2tBu)3], and of some Dihydridoiridium(III) Complexes

[IrCl(C8H14)2]2 (1) reacts with PMetBu2 in the presence of H2 to give [IrH2Cl(PMetBu2)2] (2). Treatment of 2 with acetylene yields the vinylidene complex trans‐[IrCl(=C=CH2)‐(PMetBu2)2] (3). The reaction of 1 with PMePh2 or PMe2tBu in the presence of H2 leads to the formation of fac‐[IrH2Cl(PR3)3] (4a, 5a), which on warming to 60°C rearrange to give the more stable mer isomers 4b, 5b. Treatment of 1 with PMePh2 or PMe2tBu and phenylacetylene affords the hydrido(phenyl‐ethynyl)iridium(III) compounds mer‐[IrHCl(CCPh)(PR3)3] (8, 9), which could not be converted by phosphine elimination to the corresponding (phenylvinylidene)iridium complexes. The synthesis of trans‐[IrCl(=C=CH2)(PPh3)2] (11) has been achieved by CO abstraction from [IrHCl(CCH)(CO)(PPh3)2] (13) by using trimethylamine oxide.
Mehrstufige reversible Redoxsysteme, LV. Kristallstruktur des CT‐Komplexes 2,5‐Me2‐DCNQI/TTF aus N,N′‐Dicyan‐2,5‐dimethyl‐1,4‐benzochinondiimin und Tetrathiafulvalen sowie des Acceptors 2,5‐Me2‐DCNQI
Authors: Aumüller Alexander , Erk Peter , Hünig Siegfried , Hädicke Erich , Peters Karl , Schnering Hans Georg Von
Published: July 2007

Multi‐Step Redox Systems, LV. – Crystal Structure of the CT Complex 2,5‐Me2‐DCNQI/TTF from N,N′‐Dicyano‐2,5‐dimethyl‐1,4‐benzoquinone Diimine and Tetrathiafulvalene and of the Acceptor 2,5‐Me2‐DCNQI

The crystal structure of the title compound is described and discussed in terms of a neutral non‐conducting mixed‐stack CT complex. X‐ray data for the acceptor 2,5‐Me2‐DCNQI are given for comparison.
Halogen – Kohlenstoff – Schwefel‐Verbindungen: Synthese und Reaktionsverhalten von 4,5‐Bis(trifluormethyl)‐1,3‐dithiol‐Derivaten
Authors: Maletzko Christian , Sundermeyer Wolfgang , Pritzkow Hans , Irngartinger Hermann , Huber‐Patz Ursula
Published: July 2007

Halogen – Carbon – Sulfür Compounds: Synthesis and Modes of Reactions of 4.5‐Bis(trifluoromethyl)‐1,3‐dithiole Derivatives

The chemistry of the bis(trifluoromethyl)‐1,3‐dithiole system is thoroughly investigated starting from the 2‐thione 6. By its oxidation the sulfine 2 and the ketone 7 are obtained. Further oxidation of 2 leads to the spiro compound 3. By chlorination of 6 the 2‐sulfenyl chloride 5 is obtained, which can be desulfurized by PCl3 to the 2,2‐dichloro compound 10. The best method for the preparation of the latter is the reaction of 6 with PCl5. Hydrolysis of 10 yields again the ketone 7. By reaction of 1,2‐ethanedithiol with 10 the spiro compound 11 is obtained, the reaction of which with hexafluoro‐2‐butyne also affords 3. 10 reacts with primary amines to the 2‐imines 9a and 9b, whereas 5 under similar conditions reacts via the thione S‐imides 4a and 4b to 9a (with sulfur extrusion) or in a rearrangement reaction to the 1,2,4‐trithiine 1. The preparation of the tosyl hydrazone 12 does not open an access to the diazo compound 16, neither does the reaction of 10 with hydrazine, which yields the ketazine 14. The homogeneous reaction of disilylhydrazine and 10 produced the tetrazene 17, which is a dimer of 16 and decomposes at its high melting point to the ketazine 14.
Polylithiumorganische Verbindungen, XVI. 1,4‐Disila[6]radialene: Aktivierungsparameter der Sessel‐Twist‐Inversion und analytische Enantiomerentrennung der Twist‐Konformeren
Authors: Maercker Adalbert , Brieden Walter , Kastner Fritz , Mannschreck Albrecht
Published: July 2007

Polylithiumorganic Compounds, XVI. – 1,4‐Disila[6]radialenes: Activation. Parameters of the Chair‐Twist Inversion and Analytical Separation of the Enantiomers of the Twist Conformers

Kinetic measurements of the chair‐twist inversion of the 1,4‐disila[6]radialenes 2 – 4 have been performed at four different temperatures, respectively. The entropies of activation are found to be negative. While the chair conformers of the radialenes are achiral as expected, the enantiomers of the three twist conformers could be separated by HPLC on an optically active stationary phase.
Bestimmung der Singulett‐Triplett‐Aufspaltung von Diradikalen mit Hilfe der Sauerstoff‐Abfang‐Technik
Authors: Roth Wolfgang R. , Ruhkamp Joerg , Lennartz Hans‐Werner
Published: July 2007

Determination of the Singlet‐Triplet Splitting of Diradicals by Oxygen‐Trapping

The diradical 2, generated by thermolysis of 7‐methylenebi‐cyclo[3.2.0]hept‐1‐ene (1), can be trapped by oxygen in the gasphase. From the different trapping rates with and without added SF6 the intersystem crossing rates of the diradical have been deduced. From their temperature dependance the singlet‐triplet splitting is calculated to be 7.4 kcal mol‐1 with the triplet being the ground state. The triplet is protected by an enthalpy barrier of 13.0 kcal mol‐1 against recombination of the unpaired electrons (2‐tr→1). From the heat of hydrogenation of 1 the heat of formation of 1, 2‐s and 2‐tr is derived.
Photochemistry of Tetrabenzo[c,e,i,k] [1,2,7,8]tetraazacyclododecine in 2‐Propanol
Authors: Tauer Erich , Grellmann Karl‐Heinz , Heinrich Angelika
Published: July 2007

The photochemical properties of the tetraazacyclododecine 1 were investigated. The trans,trans isomer 1tt can be photoisomerized yielding the stable cis,cis isomer 1ee. The isomerization requires two photons and proceeds via the unstable trans,cis isomer 1tc. In nitrogen‐purged 2‐propanol as solvent 1 yields five stable photoproducts as a result of a number of consecutive photoreduction reactions. Our attempts to convert 1 by light into the tetraazetidine 4 were not successful.
Schwefelverbindungen, 143 Synthese und Charakterisierung der neuen bicyclischen Schwefel‐Kohlenstoff‐Verbindungen C6H8S8, C4H4S7 und C4H4S82)
Authors: Westphal Ursula , Steudel Ralf
Published: July 2007

Sulfur Compounds, 143. — Synthesis and Characterisation of the New Bicyclic Sulfur‐Carbon Compounds C6H8S8, C4H4S7, and C4H4S8

The reaction of Cp4Ti2C2S4 (1) with two equivalents of the bissulfenyl chloride 1,2‐C2H4(SCl)2 affords the new bicyclic compound C6H8S8 (2). Treatment of 1 with one equivalent of SxCl2 (x = 1, 2) results in Cp2TiC2S5 (3) and Cp2TiC2S6 (4), respectively, which on reaction with 1,2‐C2H4(SCl)2 give the asymmetric bicyclic polysulfides C4H4S7 (5) and C4H4S8 (6), respectively.
Thiolatokomplexe des einwertigen Golds. Synthese und Struktur von [(2,4,6‐iPr3C6H2S)Au]6 und (NH4)[(2,4,6‐iPr3C6H2S)2Au]
Authors: Schröter Ingrid , Strähle Joachim
Published: July 2007

Thiolato Complexes of Monovalent Gold. Synthesis and Structure of [(2,4,6‐iPr3C6H2S)Au]6 and (NH4)[(2,4,6‐iPr3C6H2S)2Au]

Reaction of Au(CO)Cl with 2,4,6‐tri(isopropyl)thiophenol affords hexameric gold(I) thiolate [(2,4,6‐iPr3C6H2S)Au]6 (1). According to an X‐ray analysis 1 forms a centrosymmetrical twelve‐membered Au – S ring in the chair conformation with the linearly coordinated Au atoms at the mid‐edges and the S atoms at the corners of the heterocycle. When the reaction of 2,4,6‐tri(isopropyl)thiophenol is carried out with AuI in liquid ammonia the thiolato complex [(2,4,6‐iPr3C6H2S)2Au]– ‐NH+4 (2) is obtained. It crystallizes as NH4 · 2 · 3 NH3. The gold atom in 2 is linearly coordinated by two thiolato S atoms. The ammonium cation forms hydrogen bonds with three NH3 solvate molecules.
Kristallisiertes Natrium‐triethylhydroborat — Bildung und Charakterisierung
Authors: Köster Roland , Schüßler Wilhelm , Boese Roland , Bläser Dieter
Published: July 2007

Crystalline Sodium Triethylhydroborate — Formation and Characterization

Two equiv. of NaHBEt3 (1) and one equiv. of mesitylene form a crystalline compound, which is characterized by DSC and by a single‐crystal X‐ray structure analysis at 190 K as the solid phase 2.
Enantiomerenreine 3,7‐Dioxa‐2‐azabicylo[3.3.0]octane durch intramolekulare 1,3‐dipolare Cycloaddition von Nitronen
Authors: Güinter Aurich Hans , Biesemeie Frank , Boutahar Mostafa
Published: July 2007

Enantiomerically Pure 3,7‐Dioxa‐2‐azabicyclo[3.3.0]octanes by Intramolecular 1,3‐Dipolar Cycloaddition of Nitrones

Starting with chiral non‐racemic esters of lactic acid 7 and mandelic acid 8, respectively, chiral nitrones 4 have been prepared. They spontaneously undergo an intramolecular cycloaddition which proceeds with asymmetric induction by the chiral center yielding exclusively the bicyclic compounds 5 in enantimerically pure form. Reductive opening of the isoxazolidine ring affords tetrahydrofuran derivatives 13 with an γ‐amino alcohol group. Reaction of 13 with (‐)‐camphanoyl chloride gives the esters 14. Their 1H‐NMR spectra reveal a diastereomeric purity of at least 98%.
Synthese von 6,6,7,7,13,13,14,14‐Octamethyl‐6,7,13,14‐tetrasiladispiro[4.2.4.2]‐ tetradeca‐1,3,9,11‐tetraen und sein Einsatz in der π‐Komplexchemie von p‐ und d‐Block‐Elementen
Authors: Jutzi Peter , Krallmann Ralf , Wolf Gerald , Neumann Beate , Stammler Hans‐Georg
Published: July 2007

Synthesis of 6,6,7,7,13,13,14,14‐Octamethyl‐6,7,13,14‐tetrasiladispiro[4.2.4.2] tetradeca‐1,3,9,11‐tetraene and Its Application in the Chemistry of π Complexes of p‐ and d‐Block Elements

The title compound 2 can be synthesized either by reaction of ([C5H5SiMe2SiMe2C5H5]2‐ 2 Li+) with XSiMe2SiMe2X or by an intermolecular nucleophilic substitution reaction between two molecules of ([XSiMe2SiMe2C5H5]‐ Li+). Isomers of 2 with allylic hydrogen atoms arise from silatropic rearrangements and therefore show “cyclopentadiene reactivity”. Reaction of the monoanion of 2 with FeCl2 yields the ferrocene 4. From the reaction of the dianion of 2 with Me5C5RuCl, the binuclear ruthenium complex 7 with Si – Si bridges in 1,2‐position can be isolated; reactions with FeCl2 or Me5C5Fe(acac), with Me5C5GeCl, with SnCl2, and with PbCl2, lead to the metallocenes 6, 7, 8, and 9; in all these complexes the disilane bridges are in 1,2‐position. The binuclear cobalt complex 10, in which the cyclopentadienyl rings are connected with each other by disilane bridges in 1,3‐position, can be synthesized by the reaction of 2 with CO2(CO)8. The results of single‐crystal X‐ray structure analyses of 6 and 10 are presented. The possible conformations of the dianion of 2 are discussed.
Mehrfachbindungen zwischen Hauptgruppenelementen und Übergangsmetallen, XCVI Niob‐ und Tantalkomplexe mit Imido‐Liganden
Authors: Herrmann Wolfgang A. , Denk Michael , Dyckhoff Florian , Behm Joachim
Published: July 2007

Multiple Bonds Between Main‐Group Elements and Transition Metals, XCVI. – Niobium and Tantalum Complexes Having Imido Ligands

The new niobium and tantalum complexes 2b and 2c of formula M[N(SiMe3)2]2(NSiMe3)(OSiMe3) (M = Nb, b; Ta, c) are accessible by the reaction of the oxychlorides MOCl3 with the lithium amide LiN[Si(CH3)3]2 in 36 and 27% isolated yield, respectively.
Synthesis and Crystal Structure of an Arsolyl Anion and Preparation of an Arsinogallate
Authors: Sendlinger Shawn C. , Haggerty Brian S. , Rbeingold Arnold L. , Theopold Klaus H.
Published: July 2007

The permethylated arsolyl anion C4Me4AsLi(TMEDA) (5) has been prepared; its crystal structure (determined by X‐ray diffraction) revealed an aromatic heterocycle comparable to the homologous pyrrolyl and phospholyl anions.
Water‐Soluble Phtalocyanines Containing Aza‐Crown Ether Substituents
Authors: Musluǧlu Emel , Ahsen Vefa , Gül Ahmet , Bekâroǧlu Ö. , Bekâroǧlu Ö.
Published: July 2007

A straightforward and generalizable synthesis of metal‐free and metal (Ni, Pb, Lu) derivatives of symmetrically tetrasubstituted phthalocyanines derived from 15, 16‐dibromo‐ or ‐dicyano‐2, 3, 6, 7, 8, 9, 11, 12‐octahydro‐5H‐benzo[e][1, 4, 7, 13]tetroxaza‐cyclopentadecine (1) is described. Quaternarization of the N‐acetyl derivatives 7 in a chloroform/dimethyl sulfate mixture gives phthalocyanines 9 soluble in the pH range of 1 – 13. The electronic spectra of the phthalocyanines in buffered solutions (pH 4, 7, and 10) are examined. Furthermore, the electronic spectra of lutetium bis(phthalocyaninate) 9d in water and in DMSO are compared for the first time.
Reactions of 1‐Thia‐3‐azoniabutatriene Salts with Alcohols, Carbonyl Compounds, Diazoalkanes, Nitrile Oxides, Nitrones, Enamines, and Butadienes
Authors: Lubberger Hans‐Jürgen , Müller Edgar , Hofmann Josef , Fischer Helmut , Jochims Johannes C.
Published: July 2007

1‐Thia‐3‐azoniabutatriene salts 1 react with alcohols, carbonyl compounds, diazo alkanes, nitrile oxides, nitrones, enamines, and 1,3‐butadienes in all cases at the C=S double bond to yield new types of 2‐azoniaallene salts (3, 9a, b, 13a, b, 18, 22) and other imines (2, 20). An X‐ray diffraction analysis for 9b, the reaction product of 1b with 9‐diazofluorene, confirms the proposed constitution.
Heterocumulene, 8 C4OS (4‐Thioxo‐1,2,3‐butatrien‐1‐on), C4S2 (1,2,3‐Butatrien‐1,4‐dithion) und C3S (3‐Thioxo‐1,2‐propadienyliden) ‐ Darstellung und spektroskopische Eigenschaften
Authors: Maier Günther , Schrot Jürgen , Reisenauer Hans Peter , Janoschek Rudolf
Published: July 2007

Heterocumulenes, 8. — C4OS (4‐Thioxo‐1,2,3‐butatrien‐1‐one), C4S2 (1,2,3‐Butatriene‐1,4‐dithione), and C3S (3‐Thioxo‐1,2‐propadienylidene) ‐ Preparation and Spectroscopic Properties

C4OS (8) is prepared by matrix photolysis and by flash pyrolysis of the precursor molecule 4, C4S2 (12) by matrix photolysis of 10, 11, and 13. Upon irradiation both 8 and 12 are split reversibly into C3S (9) and CO or CS. The IR and UV/Vis spectra of C4OS (8), C3S (9), and C4S2 (12) are reported. Quantumchemical calculations have been performed for the structures, harmonic vibrational frequencies, singlet‐triplet gaps, and electronic transition energies of 8 and 12.
Synthesen und Strukturen von cyclischen und acyclischen Vanadium(V)‐ und Molbydän(VI)‐haltigen Verbindungen
Authors: Olms Petra , Roesky Herbert W. , Keller Klaus , Noltemeyer Mathias , Bohra Rakesh , Schmidt Hans‐Georg , Stalke Dietmar
Published: July 2007

Syntheses and Structures of Cyclic and Acyclic Compounds Containing Vanadium(V) and Molybdenum(VI)

The reaction of (C2F5)2P(Cl)NSiMe3 (2) with Cl3VNSiMe3 in CH2Cl2 yields the eight‐membered ring [(C2F5)2PN2VCl2]2 (3). (CF3)2P(Cl)NSiMe3 (1) reacts with VOCl3 to form the eight‐membered ring [(CF3)2PN]3NVCl2 (4). A six‐membered ring [Ph2PN]2NVCl2 (5) can be isolated from the reaction of Ph2P(Cl)NSiMe3 with VOCl3. 1 reacts quantitatively with MoO2Cl2 and MoOCl4 to form [MoOCl3‐O‐P(CF3)2N‐SiMe3]4 (6) and (CF3)2P(Cl)N‐MoOCl3 (7), respectively. The molecular structures of 3, 5, and 6 have been determined by X‐ray diffraction.
Komplexierung von 1,3‐Dihydro‐1, 3, 10, 10‐tetramethyl‐1, 3‐dibora‐4, 5‐benzopentafulven mit Fe(CO)3‐ und CpCo‐Fragmenten: Synthese, Kristall‐ und Elektronenstruktur von Tricarbonyl[η5‐cyclopentadienyl)cobalt] [μ,η5:η4‐(1, 3‐dihydro‐1, 3, 10, 10‐tetramethyl‐1, 3‐dibora‐4, 5‐benzopentafulven)]eisen
Authors: Nagy‐Magos Zsuzsanna , Feßenbecker Achim , Pritzkow Hans , Siebert Walter , Hyla‐Kryspin Isabella , Gleiter Rolf
Published: July 2007

Complexation of 1, 3‐Dihydro‐1, 3, 10, 10‐tetramethyl‐1, 3‐dibora‐4, 5‐benzopentafulvene with Fe(CO)3 and CpCo Fragments: Synthesis, Crystal and Electronic Structure of Tricarbonyl[(η5‐cyclopentadienyl)cobalt][μ,η5:η4‐(1, 3‐dihydro‐1, 3, 10, 10‐tetramethyl‐1, 3‐dibora‐4, 5‐benzopentafulvene)]iron

Reaction of the 1, 3‐dibora‐4, 5‐benzopentafulvene 1 with the isolobal organometallic fragments Co(C5H5) and Fe(CO)3 leads to the slipped triple‐decker complex 5. It is also formed when 2 is stacked with the Co(C5H5) fragment. The X‐ray structure analysis of 5 reveals that the Co(C5H5) fragment is coordinated to the 1, 3‐diborole ring, and the Fe(CO)3 group interacts with the Y‐shaped B2CC unit. An MO calculation indicates that the formation of 5 occurs by distortion of 2 (η5‐ → η4‐bonding) and complexation of the Co(C5H5) group. 5 is 16 kcal/mol more stable than its structural isomer 6.
Synthese und Reaktionen der Stereoisomeren von Tetrabenzo‐ und Tetranaphtho[a,c,g,i]cyclododecen
Authors: Bestmann Hans Jürgen , Schaper Wolfgang , Holzmann Hans Gottfried , Zimmermann Reiner
Published: July 2007

Synthesis and Reactions of the Stereoisomers of Tetrabenzo‐ and Tetranaphtho[a,c,g,i]cyclododecene

Starting with the bis‐mercaptane 2 and the dibromide 3 (E,E)‐ tetrabenzo[a,c,g,i]cyclododecene (1a) and the Z,Z isomer 1b are stereoselectively synthesized via the racemic (a) and the meso form (b) of the bis‐thioether 4 and the disulfone 5. Acid‐catalysed rearrangement of 1a and 1b leads to the isomeric phenanthro[9,10‐a]fluoranthene derivatives 7a and 7b. Racemate, meso form, and the optically active (‐)‐SS form of the tetranaphtho compound 18 are synthesized according to 1a and 1b from racemic or optically active starting materials 14 and 15.
Regioselektive Komplexierung von [2.2]Metacyclophanen mit Triammintricarbonylchrom
Authors: Schulz Jürgen , Vögtle Fritz
Published: July 2007

Regioselective Complexation of [2.2]Metacyclophanes with Triamminetricarbonylchromium

The new [2.2]phanes 12, 13, 15, and 17 have been prepared. For the preparation of the known phane 16 a new route has been developed which leads to better yields and includes an interesting reduction with Raney nickel of the naphthalene ring of 15 to a tetrahydronaphthalene ring (→17). The phanes react regioselectively with triamminetricarbonylchromium, which results exclusively in the complexation of the sterically less hindered benzene ring. The bis(tricarbonylchromium) complexes of 18 and 17 were available in good yields, when two equivalents of the precursor of the tricarbonylchromium group were used. 18a was lithiated at –78°C, and the lithiated complexes were trapped with either chlorotrimethylsilane or ethyl chloroformate to yield 4‐ and 5‐substituted products in a ratio of 4:5. Ten X‐ray structures, including those of six transition metal π complexes, which were investigated and compared under the aspect of steric interactions between the tricarbonylchromium group and the substituent at the arene ring, are discussed. Interestingly, the tricarbonylchromium group shows no noticable effect on the boat‐like deformation of the benzene ring in [2.2]metacyclophanes. A new definition of the “angles of helicity” in helical [2.2]phanes is introduced.
Synthese und Röntgenstrukturanalyse luftstabiler Bis[3‐(dimethylamino)propyl]indium‐Derivate
Authors: Schumann Herbert , Görlitz Frank H. , Seuß Thomas D. , Wassermann Wilfried
Published: July 2007

Synthesis and X‐ray Structural Analysis of Airstable Bis[3‐(dimethylamino)propyl]indium Derivatives

Pentacoordinate, intramolecularly base‐stabilized organoindium compounds [Me2N(CH2)3]2InBr (1), [Me2N(CH2)3]2InO2‐CCF3 (2) and [Me2N(CH2)3]2InOC6F5 (3) as well as [Me2N‐(CH2)3]2InC2H5 (4), [Me2N(CH2)3]2In(i‐C3H7) (5), and [Me2N‐(CH2)3]2In(t‐C4H9) (6) have been prepared by the reaction of indium tribromide with 3‐(dimethylamino)propyllithium and of bis[3‐(dimethylamino)propyl]indium chloride with NaO2C‐CF3, LiOC6F5, C2H5MgBr, i‐C3H7MgBr, and t‐C4H9Li, respectively. The 1H‐, 13C‐, 19F‐NMR and mass spectra of the new compounds as well as the single‐crystal X‐ray structure analysis of 1 are described and discussed.
Synthetic and Structural Studies on Organotransition Metal‐Gallium Complexes
Authors: Campbell Rachel M. , Clarkson Lucy M. , Clegg William , Hockless DavidC. R. , Pickett Nigel L. , Norman Nicholas C.
Published: July 2007

The transition metal‐gallium complexes [Ga(MLn)3] [where MLn=Fe(CO)2(η‐C5H5), Mo(CO)3(η‐C5H5), Co(CO)3(PPh3), and Mn(CO)5] have been synthesised by salt elimination between GaCl3 and MI(MLn) (MI=Na/K). The iron complex [Ga{Fe(CO)2(η‐C5H5)}3] (1) has been characterised by X‐ray crystallography and shown to contain a planar, three‐coordinate gallium centre bound to three Fe(CO)2(η‐C5H5) fragments by unsupported Ga–Fe bonds [av. 2.444(1) Å]. A partial structure determination of [Ga{Mo(CO)3(η‐C5H5)}3] (5) is consistent with a trigonal‐planar GaMo3 core. Brief mention is also made of two chloro complexes [GaCl(MLn)2] [MLn=Fe(CO)2(η‐C5‐H5) and Co(CO)3(PPh3)].
Metallkomplexe von Farbstoffen — Übergangsmetall‐Komplexe mit 2‐(1,3‐Dioxo‐2‐indanyliden)benzimidazolinen
Authors: Schmidt Christoph , Polborn Kurt , Beck Wolfgang
Published: July 2007

Metal Complexes of Dyes — Transition Metal Complexes of Mono‐ and Dianions of 2‐(1,3‐Dioxo‐2‐indanylidene)‐benzimidazolines

2‐(1,3‐Dioxo‐2‐indanylidene)benzimidazolines (L) (1—6) react with metal salts and chloro‐bridged complexes in the presence of NaH to give the mono and bis‐N,O‐chelate complexes (L — H+)2M (M=Cu, Pd, Ni) (7—9), (L — H+)M(PR3)Cl (M=Pd, Pt; 10—15 and (L — 2H+)[Pt(PEt3)Cl]2 (16, 17). The electronic spectra of the bis(chelate) complexes show a large bathochromic shift of the absorptions in the visible region as compared to the free ligands. The structures of (L — H+)Pd(Cl)‐(PnBu3) (10) and of (L — 2H+)[Pt(Cl)PEt3)]2 (16) have been determined by X‐ray crystallography. The two heterocyclic planes in 16 are bent along the elongated central CC bond [143.2(12)pm] which gives a hip‐roof‐like structure.
Contributions to the Chemistry of Boron, 210. η2‐Transition Metal Complexes of the Ligand 9‐Fluorenylidene(2,2,6,6‐tetramethylpiperidino)borane
Authors: Helm Scott W. , Linti Gerald , Nöth Heinrich , Channareddy Sreelatha , Hofmann Peter
Published: July 2007

The boraolefin 9‐fluorenylidene(tetramethylpiperidino)borane L forms complexes 1—4 with the isolobal fragments Fe‐(CO)4, CpCo(CO), Cp′Mn(CO)2, and C6H6Cr(CO)2, respectively. Compounds FeL(CO)3PR3 (PR3=PMe3, PhPMe2, Ph2‐PMe, PCl3, PhPCl2, 1 a—e) are obtained photochemically from Fe(CO)5, L, and PR3 in toluene solution. An X‐ray structure analysis 1 and 1 a reveals a distorted trigonal‐bipyramidal geometry, with the boron atom of 1 in an equatorial position. 2 contains two independent molecules in the asymmetric unit. The two molecules are enantiomers with Co atoms in a pseudotetrahedral environment. MO calculations demonstrate that the distortion found in 1 is due to electronic rather than steric effects as exemplified by the model compound Fe(CO)4(H2N—B=CH2) (6). π‐Back bonding from the metal‐centred 2a′ orbital to the boron‐centred πBC* orbital contributes significantly to the stabilization of the energy‐minimized structure 8. Experimental evidence for this back bonding is provided by the shorter M–B bond in 1 and 2 as compared with the M–C bond to the boraoelfin unit. However, the reverse is true for the manganese complex 3.
Metal Complexes with Tetrapyrrole Ligands, LXI. Structure and Products of Electrochemical Oxidation of Zirconium(IV) and Hafnium(IV) Bisporphyrinate Double‐Deckers
Authors: Buchler Johann W. , De Cian André , Elschner Steffen , Fischer Jean , Hammerschmitt Peter , Weiss Raymond
Published: July 2007

The electrochemical oxidation of zirconium and hafnium double‐deckers M(P)2 (M=Zr, Hf; P=OEP, TPP) (Scheme 1)2) leads to mono‐ and dications which show near infrared absorption bands which are of ≈ 2000 cm‐1 higher energy than those of the corresponding cerium double‐decker cations. [Zr(OEP)2]X, [Zr(OEP)2]X2, and [Zr(TPP)2]X (X=ClO4− and PF6−) are isolated after electrochemical oxidation and are characterized by IR and NMR spectroscopy. Magnetic susceptibility measurements (2 K < T < 300 K) of the solids confirm the strong coupling of the electron spins in the diamagnetic dication salt [Zr(OEP)2][ClO4]2. The molecular structure of Zr(OEP)2 is elucidated by an X‐ray structural analysis.
Organomolybdän‐ und Organowolfram‐Reagenzien, II. über den carbonylolefinierenden μ‐Methylenkomplex aus Mo2Cl10 und vier äquivalenten Methyllithium
Authors: Kauffmann Thomas , Fiegenbaum Petra , Papenberg Michael , Wieschollek Raphael , Sander JöRg
Published: July 2007

Organomolybdenum and Organotungsten Reagents, II. — On the Carbonyl‐Olefinating μ‐Methylene Complex from Mo2Cl10 and Four Equivalents of Methyllithium

Mo2Cl10 reacts at — 70°C with 4 equivalents of methyllithium to give a methylated thermolabile molybdenum complex. At higher temperatures it forms a thermolabile carbonyl‐olefinating reagent which according to NMR data is the μ‐CH2 complex Cl3Mo(μ‐CH2)2MoCl3 (2). Reactions of 2 with aldehydes, ketones, azomethines, and epoxides are described.
Alkylchrom‐ und Alkylmangan‐Reagenzien, IV. Über die Aldehyd‐ und cheleselektive Alkylierung organischer Carbonylverbindungen mit Monoalkylchrom(III)‐Reagenzien
Authors: Kauffmann Thomas , Beirich Christoph , Hamsen Angelika , Möller Thomas , Philipp Christian , Wingbermühle Dorothea
Published: July 2007

Alkylchromium and Alkylmanganese Reagents, IV. — On the Aldehyde and Cheleselective Alkylation of Organic Carbonyl Compounds with Monoalkylchromium(III) Reagents

Monoalkylchromium(III) reagents, prepared in crystalline form or in solution, alkylate aldehydes but normally not ketones. Ketones with a basic group (HO, MeO, Me2N) in α‐ or β‐position are methylated by MeCrCl2(thf)3, allowing the highly selective («cheleselective») methylation of such ketones in the presence of normal ketones.
Regio‐ and Diastereoselective Ene Reaction of Triazolinedione with Vinylsilanes
Authors: Adam Waldemar , Richter Markus
Published: July 2007

The ene reaction of 4‐methyl‐1,2,4‐triazoline‐3,5‐dione (MTAD) with vinylsilanes 1 has been investigated. In all cases studied, only hydrogen abstraction geminal to the silyl group with formation of triazolidinediones 3 occurred, irrespective of the number and size of the substituents at the double bond. A mechanism with an aziridinium imide as intermediate is proposed to explain the observed regioselectivity and diastereoselectivity. For the former we invoke preferential cleavage of the C–N bond proximate to the silyl substituent on the aziridine ring, for the latter steric repulsion between the adjacent silyl and alkyl group controls the observed E‐type stereochemistry. A new synthetic approach to the trisubstituted vinylsilane 1e based on reductive lithiation of the corresponding vinyl sulfide is described.
A Mass‐Spectrometric Investigation of CxNO2 (x=1, 2) Ions and Neutrals
Authors: Sülzle Detlev , O'Bannon P. E. , Schwarz Helmut
Published: July 2007

The isomeric [C2,N,O2]+ ions OCNCO+, OCCNO+, and NCCO2− have been generated and structurally characterized on the basis of their collisional activation, charge reversal, and neutralization‐reionization mass spectra. The open‐shell neutrals formed in the neutralization step undergo facile unimolecular decomposition. A recovery signal is obtained only for OCCNO.
A novel route to the triphenylene ring system by a triple intramolecular acyloin condensation
Authors: Praefcke Klaus , Psaras Panicos , Bilgin Belkiz
Published: July 2007

A one‐pot synthesis of a sixfold functionalized dodecahydro‐triphenylene 2 with D3 symmetry starting from 1,2,3,4,5,6‐hexakis(eq)(ethoxycarbonylmethyl)cyclohexane (1) is described. The new and straightforward approach to this tetracyclic ring system is based on a triple intramolecularly occurring acyloin condensation by using sodium in the presence of chlorotri‐methylsilane.
Molecular Motions in Fluctional Crystals: N‐Base Adducts of Bis(1,5‐cyclooctanediylboryl) Oxide
Authors: Yalpani Mohamed , Köster Roland , Boese Roland
Published: July 2007

The adducts of bis(1,5‐cyclooctanediylboryl) oxide (1) with quinuclidine (2a) and with pyridine (2b) show an unusually large premelting endothermic phase transition. 2a has been investigated by 11B‐NMR spectroscopy in the solid state and at various temperatures in its mesophase. The significant differences in the lattice packings of the molecules of the thermally stable adducts of 1 with 4‐methyl‐, 3‐bromo‐, and 4‐(dimethylamino)pyridine (2c—e; X‐ray structural analysis) from those of 2a and 2b suggests that it is the unique molecular arrangement in the respective lattices of the latter two adducts which allows a smooth transition to a two‐dimensionally ordered mesophase. This is stabilized by intermolecular fluctuation of the N‐base molecules between the boron atoms of the neighbouring molecules of 1.
Gasphasen‐Reaktionen, 85[1] Darstellung und Photoelektronen‐Spektrum von Ethyldithioxo‐λ5‐phosphoran H5C2‐P(=S)2
Authors: Bock Hans , Kremer Matthias , Solouki Bahman , Binnewies Michael
Published: July 2007

Gas‐Phase Reactions, 85[1]. – Preparation and Photoelectron Spectrum of Ethyldithioxo‐λ5‐phosphorane H5C2‐P(=S)2

The first alkyldithioxo‐λ5‐phosphorane 1a is obtained by selective monomerization of its readily accessible dimer, 2,4‐diethyl‐1,3,2λ5,4λ5‐dithiadiphosphetane‐2,4‐dithione [4 (R = C2H5)], at 970 K in the gas phase and characterized by its photoelectron spectrum, which is assigned by both Koopmans' correlation and radical‐cation state comparison with the halogen derivatives FPS2 (1b) and CIPS2 (1c).
Bis(trifluormethylchalkogenyl)ketene (CF3E)2C = C = O (E = S, Se, SO2); Synthesen und Eigenschaften
Authors: Haas Alois , Praas Hans‐Walter
Published: July 2007

Bis(trifluoromethylchalcogenyl)ketenes (CF3E)2C = C = O (E = S, Se, SO2); Synthesis and Properties

Bis(trifluoromethylchalkogenyl)ketenes (1) are synthesized either by dehydrohalogenation of the corresponding acetyl chlorides or dehydratization of the corresponding acetic acids. In addition, treatment of trifluoromethylchalkogenyl chlorides with Ag2C = C = O provides 1 a in low but 1 b in good yields. Oxidation of bis(trifluoromethylsulfanyl)acetic acid with CrO3/H2SO4 gives some bis(trifluoromethylsulfonyl)ketene 1 c. Starting materials for the preparation of the ketenes are mono‐ and bis(trifluoromethylchalkogenyl)‐substituted orthoesters which are prepared from CH3C(OC2H5)3 and CF3ECl (E = S, Se). They are hydrolyzed to CH3‐n(ECF3)nC(O)OH (4). For E = Se the acids 4b,d are converted by SOCl2 into CH3‐n(SeCF3)nC(O)Cl (7a,b). Mono‐ and disubstituted malonic esters 5, 6 are formed by treating diethyl malonate with sodium and then CF3ECl. Acidic hydrolysis with 62% HBr converts 5 and 6 into the corresponding acetic acid derivatives 4. From CH3‐n(SCF3)nC(O)Cl and (CH3)3SiN3 isocyanate CH3‐n(SCF3)nNCO (n = 1, 2) are obtained in good yields. Hydrolysis of (CF3S)2C = C = O (1a) either in acidic or basic solution gives (CF3S)2CHC(O)OH (4c). Some chemical reactions of 1 a are described.
Ester von (Hydroxymethyl)diorganylsilanen: Synthese und thermisch induzierte Umlagerung
Authors: Tacke Reinhold , Wiesenberger Frank , Becker Beate , Rohr‐Aehle Regine , Schneider Petra B. , Ulbrich Uwe , Sarge Stefan M. , Cammenga Heiko K. , Koslowski Thorsten , Niessen Wolfgang Von
Published: July 2007

Esters of (Hydroxymethyl)diorganylsilanes: Synthesis and Thermally Induced Rearrangement

Twenty silanes of the type R1R2Si(H)CH2OR3 (A) were synthesized [R1, R2 = Me, Ph, 1‐naphthyl, PhCH2,Me3SiCH2; OR3 = OC(O)Me, OC(O)Ph, OC(O)CF3, OS(O)2CF3, OP(O)Ph2, OC(O)Cl] and studied for their thermal behaviour. The silanes A undergo a thermally induced rearrangement to give the corresponding silanes R1R2Si(OR3)Me (B). For compounds with OR3 = OC(O)Cl, an additional decarboxylation takes place to yield the chlorosilanes R1R2Si(Cl)Me. Except for the derivatives with OR3 = OC(O)Cl, the energetic (reaction enthalpy) and kinetic data (reaction order, frequency factor, enthalpy and entropy of activation) of these reactions were studied by means of differential scanning calorimetry (DSC). In addition, the kinetics of all reactions were investigated by 1H‐NMR spectroscopy. The transition state of the rearrangement was investigated by an ab initio study based on the model compound H3SiCH2OC(O)H [→ MeH2SiOC(O)H]. The theoretical data and the experimentally obtained energetic and kinetic data are discussed in terms of mechanistic aspects of the rearrangement reaction A → B.
Alkalimetall‐trialkylhydroxyborate und (Alkalimetalloxy)dialkylborane[1]
Authors: Köster Roland , Seidel Günter , Wrackmeyer Bernd
Published: July 2007

Alkalimetal Trialkylhydroxyborates and (Alkalimetaloxy)dialkylboranes[1]

Et3B (1) and 9‐Et‐9‐BBN (2) react with alkalimetal hydroxides (LiOH, NaOH, KOH) to yield the alkalimetal hydroxytriorganoborates M‐3 and M‐4, resp. Heating (about 100°C) of the borates, catalyzed by NaHBEt3, leads to elimination of ethane with formation of the boranes MOBEt2 (M‐5, M = Na, K) or MOBC8H14 (M‐7, M = Li, Na, K), which associate to compounds with BOB, BOM, or MOM bridge bonds. At temperatures higher than 160°C (without catalyst), M‐3 (M = Li, Na) and Li‐4 dissociate. Na‐4 is dehydroborated with formation of H2 and NaOB(Et)C8H13 (Na‐9). From K‐7 and ClSiMe3 9‐Me3SiO‐9‐BBN (10) is obtained. Na‐9 reacts with ClSiMe3 to give a mixture of the unsaturated mixed borane 11 and the mixed diboroxane 12. The degree of the association of the alkalimetal compounds were determined by the specific electric conductivity measurements (K) and by 17O‐NMR spectroscopy.
Functionalized Cyclopentadienyl Ligands, VII[1] Cobalt‐Mediated Cyclohexadiene Formation Involving an Intramolecularly Coordinated CC Bond
Authors: Okuda Jun , Zimmermann Karl Heinz
Published: July 2007

Reaction of Co(η5:η2‐C5Me4CH2CH2CH = CH2)(η2‐C2H4) (1) with bis(trimethylsilyl)acetylene gives a substitution product Co(η5:η2‐C5Me4CH2CH2CHCH2)(η2‐Me3SiC≡CSiMe3) (2) which simultaneously contains both an η2‐alkene and an η2‐alkyne ligand. With 1 substituted alkynes R1C≡C2 (R1 = R2 = CO2Me, Ph; R1 = CO2Me, R2 Ph; = R1 = SiMe3, R2 = H) react to give cyclohexadiene complexes of the type Co(η5:η4‐C5Me4CH2CH2C6H3R4) (4, 5, 8, 9). This [2+2+2] cycloaddition involves two molecules of an alkyne and the intramolecularly coordinated CC bond leading to an η4‐bonded cyclohexadiene ligand which is linked to the five‐membered ring by a CH2CH2 bridge. In the case of diphenylacetylene the cyclobutadiene complex Co(η5‐C5Me4CH2CH2CHCH2(η4‐C4Ph4) (6) is formed as a byproduct.
Asymmetrische Katalysen, 77[1] Neue optisch aktive Pyrazolderivate für die enantioselektive Katalyse
Authors: Brunner Henri , Scheck Thomas
Published: July 2007

Asymmetric Catalysis, 77[1]. – New Optically Active Pyrazole Derivatives for Enantioselective Catalysis

Starting from the amines 3–6 and the dipyrazolopyrazinedione 2, the optically active (pyrazolylmethyl)amines 11–14 have been synthesized. Furthermore, the preparation of the (+)‐camphor‐derived optically active pyrazole 17 is described. Pyrazoles 11–13 and 17 are introduced as chiral building blocks into the 2‐(1‐pyrazolyl)pyridines 30–33. The optically active compounds 23–25 are formed from 2‐[3(5)‐pyrazolyl]pyridine and 2,6‐bis[3(5‐)pyrazolyl]pyridine, respectively, and (+)‐3‐(bromomethyl)pinane. The pyrazole derivatives 27–29 contain (+)‐(1‐phenylethyl)hydrazine as the optically active component.
Structural NMR Investigations on Allyllithium Compounds
Authors: Balzer Hartmut , Berger Stefan
Published: July 2007

Four differently substituted phenylallyllithium compounds Li · 2 have been investigated by dynamic 1H‐ and 13C‐NMR, NOESY and HOESY spectroscopy. It is shown that a considerable barrier of rotation (ca. 40 kJ/mol) between the phenyl and the allyl moiety exists which is only slightly affected by the addition of TMEDA. The lithium atom prefers a bridged position with respect to the allylic part in solution and has HOESY contacts to the ortho hydrogen atoms of the aromatic ring.
Fe+‐Mediated Dehydrogenation of 2‐Propanol and Ethanol by 1,3‐Butadiene and Evidence for Interligand Hydrogen Exchange Processes
Authors: Karraß Sigurd , Schröder Detlef , Schwarz Helmut
Published: July 2007

Gas‐phase experiments on the Fe+‐mediated oxidation of 2‐propanol and ethanol by 1,3‐butadiene are described. The reaction takes place at an atomic Fe+ centre, and labeling experiments uncover its specificity. While the gas‐phase reaction of Fe(η4‐C4H6)+ with 2‐propanol occurs at collision‐rate and the analysis of ligand‐binding energies, in principle, favour a catalytic cycle for the Fe+‐mediated dehydrogenation of 2‐propanol by 1,3‐butadiene, this conjecture is not born out experimentally due to complicating “side” processes. In addition to the specific interligand two‐hydrogen‐atom transfer from the alcohol to butadiene, the study of isotopomers reveals several hydrogen‐exchange processes preceding dehydrogenation, dehydration, and alkene loss from (C4H6)Fe+ (alcohol) complexes.
Synthese und Struktur von SeSb2Cl2(NCMe3)4 — eines nur von Stickstoffatomen umgebenen Selenimids[1]
Authors: Björgvinsson MÁR , Roesky Herbert W. , Pauer Frank , Sheldrick George M.
Published: July 2007

Synthesis and Structure of SeSb2Cl2(NCMe3)4 – a Compound with a Selenium Atom Coordinated by three Nitrogen Atoms[1]

Reaction of Se[NCMe3(SiMe3)]2 (2) with SbCl3 leads to the novel tricyclic compound SeSb2Cl2(NCMe3)4 (3). According to an X‐ray structure analysis the six‐membered SeSb2Cl2(NCMe3)3 ring in 3 is bound to the NCMe3 moiety.