Showing papers in "Chemische Berichte in 1990"

Functionalized cyclopentadienyl ligands, IV. Synthesis and complexation of linked cyclopentadienyl‐amido ligands

Abstract: [(tert-Butylamino)dimethylsilyl]cyclopentadienes C 5 H 5−n -(CMe 3 ) n (SiMe 2 NHCMe 3 ) (n=1,2) and C 5 H 4 (SiMe 3 )(SiMe 2 -NHCMe 3 ) have been prepared and the complexation of their lithium derivatives with FeCl 2 (THF) 1.5 and TiCl 4 (THF) 2 investigated

Chirale Halbsandwich-Komplexe von Rhodium(III), Iridium(III), Iridium(I) und Ruthenium(II) mit α-Aminosäure-Anionen

Abstract: The chloro-bridged metal compounds Cp * (Cl)M(μ-Cl) 2 M(Cl)-Cp * (M=Rh, Ir; Cp * =η 5 -C 5 Me 5 ), (η 6 -C 6 H 6 )(Cl)Ru(μ-Cl) 2 -Ru(Cl)(η 6 -C 6 H 6 ), and (COD)Ir(μ-Cl) 2 Ir(COD) react with α-amino acidates to give monomeric chelate complexes. The structures of Cp * (Cl)Ir(L-ProO) (1j), Cp * (Cl)Rh(L-azetidine-2-carboxylate) (1m), [Cp * (Cl)Ir(L-HisOH)]Cl (3), and (η 6 -C 6 H 6 )(Cl)Ru(L-ProO) (4a) have been determined by X-ray crystallography

Über Metallalkyl‐ und ‐aryl‐Verbindungen, 40 Strukturverfeinerung von Methyllithium durch Neutronenbeugung von (LiCD3)4 bei 1.5 und 290 K

Abstract: Metal Alkyl und Aryl Compounds, 40% - Structure Refinement of Methyl Lithium by Neutron Diffraction of (LiCD3)4 at 1.5 and 290 K The structure of deuterated methyl lithium has been refined by neutron powder diffraction at 1.5 and 290 K. At both temperatures a cubic body-centered arrangement of (LiCD3)4 units (Td, symmetry) is found. In agreement with previous X-ray powder investigations (290 K) each tetramer contains a distorted cubic Li4C4 core with pyramidal methyl groups in staggered positions with respect to the adjacent Li3 unit. Refined values, in particular precise D positions, have now been obtained.

Orotate complexes. Synthesis and crystal structure of lithium orotate(—I) monohydrate and magnesium bis[ orotate(—I)] octahydrate

Abstract: Neutralization of orotic acid (OrH2) by lithium or magnesium hydroxide in aqueous medium yields the crystalline metal orotate hydrates Li(OrH). H2O (1) and Mg(OrH)2. (H2O)6 (2). By single-crystal X-ray diffraction studies it has been shown that 1 (space group P1) forms a layer structure, with lithium in a tetrahedral environment of oxygen atoms from three different orotate( - I) anions (one carboxylate and two uracil oxygen atoms) and the water molecule. 2 (space group P21/c) has been shown to feature a hexaquo complex of magnesium, the Mg(H2O)26 cations being associated with two hydrated OrH⊖ ions only through hydrogen bonds. The anions are also engaged in “base-pairing” hydrogen bonds between the planar uracil ring systems of different units. The results are relevant for applications of magnesium orotates in magnesium therapy.

Titanocen‐ und Zirconocen(diazadien)‐Komplexe: Darstellung, Charakterisierung und Struktur

Abstract: 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.

1,1′-Bis(diphenylphosphino)bicyclopropyl: Synthesis, Properties, Precursors, Derivatives, and Metal Complexes

Abstract: The title compound 4 has been prepared from readily available 2,3-bis(diphenylphosphinyl)-1,3-butadiene (1) through double cyclopropanation using Me2S(CH2)O to give 1,1′-bis(diphenylphosphinyl)bicyclopropyl (2), followed by reduction using HSiCl3/NEt3. Addition of sulfur to compound 4 yields the disulfide 5, and reaction with tetrahydrofuran – borane affords the 1:2 adduct with BH3 (6). Quaternization reactions with MeI or CH2I2 give the double quaternary salts 7 and 8, respectively. Single dehydrohalogenation employing nBuLi converts 8 into the cyclic semiylide salt 9. 4 is an excellent ligand for lowvalent late transition-metal cations. With PdI2 the 1:1 complex LPdI2 (10, with L = 4), and with [(CO)2RhCl]2 the ionic 2:1 complex L2Rh+Cl- (11) are obtained. Experiments with (CO)AuCl yield the 1:2 complex L(AuCl)2 (12), X-ray structure analyses were performed with single crystals of the disulfide 5, as well as the rhodium(I) and gold(I) complexes 11 and 12. 5 has a conformation between s-cis and s-trans with the PS functions pointing away from each other at opposite ends of the molecule. By contrast, in the gold(I) complex the ligand approaches an s-cis conformation, and through rotations about P–C and C–C bonds – as referred to the conformation of 5 – the metal atoms are brought into close contact: Au…Au = 3.085 A. Through temperature-dependent NMR investigations of compounds 5 and 12, and by comparison with values calculated or experimentally determined for related bicyclopropyl compounds (available in the literature), the energy of the Au…Au attraction has been estimated to be ca. 6 kcal/mol. Compound 11 features a square-planar, double-chelate cation.

Regio‐ und stereoselektive Photocycloadditionen aromatischer Aldehyde an Furan und 2,3‐Dihydrofuran

Abstract: Regio- and Stereoselective Photocycloaddition Reactions of Aromatic Aldehydes to Furan and 2.3-Dihydrofuran The Paterno-Buchi reaction between benzaldehyde (1a), tolualdehyde (1b), mesitylaldehyde (1c), and 2,4-di-tert-butyl-4-methylbenzaldehyde (1d) and the electron-rich alkenes furan and 2,3-dihydrofuran has been investigated. The reaction with furan leads exclusively to exo-6-aryl-2,7-dioxabicyclo[3.2.0]-hept-3-enes 2a to 2d in yields of 78% to 97% (2a, 2b). In the photoreaction of 2a and 2b with 2,3-dihydrofuran, however, mixtures of exo- and endo-7-aryl-2,6-dioxabicyclo[3.2.0]heptanes 3a and 4a (7:1) as well as 3b and 4b (15:1) could be isolated. The sterically more hindered aldehydes 1c and 1d give rise to exclusive formation of the endo adducts 3c and 3d. Irradiation of 1d in the presence of 2,3-dihydrofuran leads to the benzocyclobutenol 5 (Norrish-type II; up to 45%) as a side product. The regioselectivity observed in these reactions may be explained by comparing the stability of the possible 1,4-diradical intermediates. The observed stereoselectivity could be rationalized by the geometry of the triplet 1,4-diradicals during the ISC process and by the life times of the resulting singlet 1,4-diradicals.

Inversionsbarrieren Ortho,ortho′‐verbrückter Biphenyle

Abstract: Inversion Barriers of ortho,ortho′-Bridged Biphenyls The syntheses and spectroscopic properties of the ortho,ortho′-bridged biphenyls 2–19 are described. In the case of 5, 15, and 16 the inversion barrier is determined from the temperature dependence of the NMR spectra (lineshape analysis), in the case of 12, 13, and 14 from the temperature of coalescence, and in the case of 2a, 3b, 7, 17, 18, and 19 from the rate of racemization of the optically active compounds. The experimental inversion barriers, including data from the literature, are compared with those calculated using the extended force field (MM2erw). The conformational behavior of the title systems is significantly affected upon transformation into the corresponding dianion salts. The relevant energy terms are discussed.

Active Magnesium from Catalytically Prepared Magnesium Hydride or from Magnesium Anthracene and its Uses in the Synthesis

Abstract: 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.

Multiple Bonds between Main Group Elements and Transition Metals, LXXXIII. Trioxo(pyrazolyl)rhenium(VII) and [Hydridotris(1‐pyrazolyl)borato‐N,N′,N″]trioxorhenium(VII)

Abstract: The syntheses of the rhenium(VII) title compounds (pz)ReO3 (1) and [HB(pz)3]ReO3 (2) (pz = pyrazolyl) are described. An X-ray crystallographic study of 2 shows, that it has a monomeric structure.

Imidazole derivatives. III: Regiospecific synthesis, structure, and fluorescence properties of highly substituted imidazo[1,2-a]pyridines and pyrido[1,2-a]benzimidazoles

Abstract: 1-(Arylacetyl)imidazoles 1 react with acetylenedicarboxylic esters to provide highly functionalized imidazo[1,2-a]pyridines 2 in up to 89% yield. The scope and limitations of this novel condensation reaction have been investigated, ad a mechanistic interpretation is presented. A strong effect on the yield of this reaction is observed for electron-donating and electronwithdrawing substituents in the para position of the aryl ring. Moreover, the transformation is shown to proceed in a regiospecific manner starting with 4,5-unsymmetrically substituted 1-(arylacetyl)imidazoles (1d–g) and is extended to the synthesis of the corresponding pyrido[1,2-a]benzimidazoles 12. The crystal structure of derivative 2a has been determined by X-ray analysis. Imidazo[1,2-a]pyridines 2 and pyrido[1,2-a]-benzimidazoles 12, obtained by this procedure, are highly fluorescent in the visible region with characteristically large Stokes shifts.

Intramolecularly stabilized organoaluminium, ‐gallium and ‐indium derivatives crystal structures of {o‐[(dimethylamino)methyl]phenyl}dimethylgallium and {o‐[(diethylamino)methyl]phenyl}dimethylindium

Abstract: Intramolecularly stabilized four-coordinated organoaluminium, -gallium, and-indium compounds R2MC6H4CH2NR'2-(2) (1–7), Me2MCH2C6H4NMe2-(2) (8, 9), Me2MCH2C6H4CH2-NMe2-(2) (10, 11), and Me2GaC6H4NMe2 (12) have been synthesized from O -[(dialkylamino)methyl]phenyllithium, [O -(dimethylamino)phenyl]methyllithium, {O -[(dimethylamino)methyl]phenyl}methyllithium and O -(dimethylamino)phenyllithium, respectively. The 1H-, 13CNMR, and mass spectra of the new compounds and the X-ray crystal structures of 2 and 7 are reported and discussed.

Synthesis of allenes by 1,6-addition of organocuprates to polarized enynes

Abstract: Ten β-allenic esters, ketones, and thioesters 15 bearing alkyl, alkenyl, aryl, and trimethylsilyl groups are synthesized in 57- 85% yield by 1,6-addition of organocuprates to polarized enynes 10. The dependence of the regioselectivity of the protonation of the allenyl enolate intermediate 7 on the protonating agent is studied: pure allenes are obtained by quenching the intermediate with pivalic acid at −80°C. The method is applied in a short synthesis of pseudoionone (18).

Novel Access to Polyazamacrocycles: Non‐Template Cyclization of Terephthalaldehyde and Aliphatic Polyamines

Abstract: Non-template [2+2] condensation of terephthalaldehyde with bis(3-aminopropyl)amine and N,N'-bis(3-aminopropyl)-1,2-diaminoethane leads to macrocyclic systems that can be reduced and derivatized further, whereas a similar reaction with bis(2-aminoethyl)amine leads to polymeric material only.

Wasserlösliche Metallkomplexe und Katalysatoren. V, 2,2'-Bipyridin-5-sulfonsäure und metallorganische Komplexe : Spektroskopie und Strukturchemie

Abstract: Water-Soluble Metal Complexes and Catalysts, V. — 2,2′-Bipyridine-5-sulfonic Acid and Organometallic Complexes: Spectroscopy and Structures Coplanar orientation of the pyridine rings in 2,2′-bipyridine-5-sulfonic acid (1a) and in metal complexes of this ligand is evident from NMR studies. While the free acid 1a exists as a planar zwitter-ion the rings of the salts 1b–d (Na+, [N(C4H9)4]+,[P(C6H5)4)]+) and sulfonamides 1f–h (tert-butyl, benzyl, 2-pyridylmethyl) are twisted. X-ray crystal structures determined for four complexes 4e, h, 1, and 10b of the sulfonic acid and sulfonamide derivatives of 2,2′-bipyridine show that there is no influence of the sulfonic acid and the sulfonamide groups (meta-position) on the complex chemistry of the chelate ligand. Variation of solubility should, therefore, occur without principal changes of reactivity.

Notizen/Notes A Novel vic‐Dioxime with Crown Ether Moieties

Abstract: The novel vic-dioxime 2 has been synthesized by reaction of the thiourea 1 with cyanogen N,N′-dioxide. The IR and NMR data indicate that 2 is the (E,Z) isomer. However, in the Co(III) complex of 2, the metal ion is coordinated to the nitrogen atoms of the vic-dioxime moiety as in the case of the (E, E) isomers.

π-Complexes of p-Block Elements: Synthesis and Structures of Adducts of Arsenic and Antimony Halides with Alkylated Benzenes

Abstract: 1,2,4,5-Tetramethyl-and pentamethylbenzene from stable 1:2 complexes with SbCl3 of the type (C6H6-Men) · 2SbCl3(1,2) with an inverse sandwich structure. The compounds crystallize isotypically and are isostructural to the (hexamethylbenzene)antimony and -bismuth complexes.They are thus built of tetrameric chlorine-bridged Sb4Cl12 units, which are crosslinked at the metal centers with four other tetramers by double-sided arene coordination (X-ray structure analysis of 1). The Sb atoms, which are in a distorted trigonal bipyramidal environment, show a slight deviation from a centric (η6) coordination. The same stoichiometry and the same structural principle are found for the complex (C6Me6 · 2 AsCl3 (4), which is obtained from solutions of hexamethylbenzene and AsCl3 in toluene. In 4 the arsenic atoms are η6-coordinated to the hexamethylbenzene ring from both sides (X-ray analysis). Treatment of AsBr3 with hexamethylbenzene leads to a product of the composition 5 (C6Me6) · AsBr3. Reaction of hexaethylbenzene with AsCl3 in petroleum ether leads to the formation of the 1:2 complex (C6Et6) · 2 AsCl3 (5), built of discrete inverse sandwich units, which are arranged in strings parallel to the crystallographic c axis. From solutions of AsCl3 (AsBr3), SbCl3 (SbBr3) and hexaethylbenzene in petroleum ether ternary compounds are isolated with an As:Sb ratio of 1:5.2 and 1:1.86, respectively. Single crystal X-ray structure determinations failed as a consequence of severe disorder.

Reaktive EC(p‐p)π‐Systeme, XXVI. Einfache Synthese für Methylenphosphane (Phosphaalkene) des Typs HPC(F)NR2 und das Phosphaalkin PC‐N(iPr)2

Abstract: Reactive EC(p-p)π-Systems, XXVI. — Facile Synthesis of Phosphaalkenes of the Type HPC(F)NR2 and the Phosphaalkyne PC-N(iPr)2 The reaction of trifluoromethylphosphane CF3PH2 with secondary amines in a 1:3 molar ratio leads to the novel methylenephosphanes (phosphaalkenes) HP C(F)NR2 [R Me (1), Et (2), Pr (3), piperidine (4)] in yields between 40 and 60%. The analogous deuterium compound DP C(F)NEt2 (5) is formed by the reaction of CF3PD2 with Et2ND. However, with di(isopropyl)amine the new phosphaalkyne P CN(iPr)2 (6) is produced instead of the expected phosphaalkene.

(E,R,R)-5-Alkyliden-2-tert-butyl-6-methyl-1,3-dioxan-4-one: Herstellung aus (R)-3-Hydroxybuttersäure, Cuprat-Additionen und Hydrolysen zu 3-Hydroxycarbonsäuren mit chiralen sekundären Alkylgruppen in 2-Stellung

Abstract: (E,R,R)-5-Alkylidene-2-tert-butyl-6-methyl-1,3-dioxan-4-ones: Preparation from (R)-3-Hydroxybutyric Acid, Cuprate Additions, and Hydrolyses to 3-Hydroxycarboxylic Acids with Chiral Secondary Alkyl Substituents in the 2-Position Li enolates of (R,R)-2-tert-Butyl-6-methyl-1,3-dioxan-4-one add to aliphatic or aromatic aldehydes with relative topicity Re,Re (2: 1 to 10: 1, 9 examples). The title compounds are obtained from these aldol adducts by dehydration through mesylates (5 examples, total yields from the dioxanone 35–55%). Cuprate additions (R2CuLi/F3BOEt2) to these alkylidene dioxanones and quenching with acid produce 5,6-trans-substituted dioxanones in an overall anti addition of R and H to the exocyclic double bond from the Re and the Si face, respectively (5: 1 to 40:1, 13 examples, 50–80%). The configurations of the products were assigned by NMR spectroscopy and by chemical correlation. In 8 cases, the dioxanone products were hydrolysed to the corresponding free β-hydroxycarboxylic acids. It is also demonstrated that transacetalisation of the aldol adducts leads to 1,3-dioxane-5-carboxylic acids (acetal-protected derivatives of “double aldols”, formally derived from acetic acid, 4 examples). Reduction of these acids with LAH, in turn, produces tris(hydroxyalkyl)methanes (acetal-protected, 3 examples). All chiral products described herein are enantiomerically pure.

Gold complexes with selenium ligands, I. Preparation and crystal structures of phenylselenolato‐gold(I) complexes

Abstract: (Triphenylphosphine)phenylselenolatogold(I), Ph3PAuSePh (1), and the corresponding dppm derivative, [(dppm)(AuSePh)2] (3), are prepared from Me3SiSePh and the appropriate (phosphine)chlorogold(I) complex. The reaction between Ph3PAuCl, Ph2Se2 and AgSbF6 leads to the salt [(Ph3PAu)2SePh]+SbF−6 (2), with a bridging PhSe ligand. X-ray structure analyses of 1 and 2 confirm the expected linear geometry at gold and reveal short Au-Au contacts; both compounds may thus be regarded as loose dimers.

Optical Resolution of [2,2]Paracyclophanes by High‐Performance Liquid Chromatography on Tris(3,5‐dimethylphenylcarbamates) of Celllulos and Amylose

Abstract: Optical resolution of 22 [2,2]paracyclophane derivatives was examined by high-performance liquid chromatography (HPLC) using tris(3,5-dimethylphenylcarbamates) of cellulose and amylose as chiral stationary phases. Most compounds were completely separated into enantiomers at least on one of the stationary phases. The preparation of hte new cyclophane derivatives 10, 11, 12, 14, 16, and 19 as wel as a new procedure for the synthesis of 4-fluoro-[2,2]paracyclophane (3) are described.

1,3,2‐Dithiazol‐2‐yl‐Radikale aus N‐substituierten 1,3,2‐Dithiazolen

Abstract: 1,3,2-Dithiazol-2-yl Radicals from N-Substituted 1,3,2-Dithiazoles Thermolysis of N-substituted 1,3,2-dithiazoles 1,2 as well as their reactions with bases affords the corresponding 1,3,2-dithiazol-2-yl radical 3, 4. Radical 3 has been characterized by X-ray structure analysis.

Gold(I) Complexes of Primary Phosphanes: Pair Formation through Au…Au Interactions

Abstract: (CO)AuCl reacts with (2,4,6-trialkylphenyl)phosphanes 1a–d (alkyl = Me, Et, iPr, tBu) to give the 1:1 complexes 2a–d. The crystal structure of 2d shows pairs of molecules with Au…Au contacts of 3.440(1) A.

Zur Lewis-Acidität von Nickel(0), XII. Dimethylaluminiumhydrid-Komplexe von Nickel(0)

Abstract: On the Lewis Acidity of Nickel(0). XII. - Dimethylaluminium Hydride Complexes of Nickel(O) Ni(CDT) reacts with (1-azabicyclo[2.2.2]octane)dimethylaluminium hydride in pentane to form the yellow crystaline addition compound (C7H13N)(Me2AlH)Ni(CDT) (2c). In its crystal structure 2c exhibits a Ni–H–Al three-center bond. Displacement of the CDT ligand of 2c with ethene in pentane at 0°C yields light brown crystals of (C sb7H13N)(Me2AlH)Ni(C2H4)2 (4), which is also obtained from Ni(C2H4)3 and (C7H13N)-Me2AlH). Complex 4 is converted by CO at – 78°C into the colorless carbonyl complex (C7H13N)(Me2AlH)Ni(CO)3 (5). 2c and 4 may be considered as model compounds for intermediates of the nickel(0)-catalyzed hydroalumination reaction of alkenes.

Kondensation von Methylcarben-Komplexen mit Säureamiden: β-Alkoxyalkenyl- und β-Aminoalkenylcarben-Komplexe von Chrom und Wolfram - Konkurrenz von Kondensation und Insertion

Abstract: Organic Syntheses via Transition Metal Complexes, 441. - Condensation of Methyl Carbene Complexes with Acid Amides: β-Alkoxyalkenyl- and β-Aminoalkenyl Carbene Complexes of Chromium and Tungsten - Competition of Condensation and Insertion The condensation of the methyl(ethoxycarbene) complexes LnM = C(OEt)CH3 (4) [LnM = Cr(CO)5, W(CO)5] with acid amides RCONR1R2 (5) under the influence of POCl3/Et3N leads stereoselectively to (E)-β-aminoalkenyl(ethoxycarbene) complexes LnM=C(OEt)CH=C(R)NR1R2 [(E)-6] (R = H, aryl, alkyl). A condensation of 4 can also be achieved via amidium salts 11, which are easily available from 5. In this case, (E)-6 and (E)-β-alkoxyalkenyl(ethoxycarbene) complexes LnM=C(OEt)CH = C(R)OEt[(E)-13] were obtained. Via the cyclic amidium salts 15 and 20 four-to seven-membered lactams (E)-17 and (E)-21a-d are accessible. The reaction of 4 with acid amides RCH2CONR1R2 (2) and POCl3/Et3N yields mainly insertion products LnM=C(NR1R2)C(R)=C(OEt)CH3 [(E)/(Z)-22] and only small amounts of condensation products LnM=C(OEt)CH=C(CH2R)NR1R2 [(E)-23].

N,N'-Dilithiobis(alkylamino)phenylborane als Synthesebausteine für viergliedrige Metallacyclen

Abstract: 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.

Synthesen und Strukturen neuer Komplexes des 2,2′-Bipyridins mit Niob, Molybdän, Wolfram und Rhenium in hohen Oxidationsstufen

Abstract: Syntheses and Structures of New 2,2′-Bipyridine Complexes of Niobium, Molybdenum, Tungsten, and Rhenium in High Oxidation States Exchange of oxo for chlorine ligands by means of hexamethyl-disiloxane provides an easy and effective synthesis of the oxo halides (bipy)MVOCl3 (bipy = 2,2′-bipyridine, C10H8N2; M = Nb, 1c; Re, 2c; W, 3c) and (bipy)MVIO2Cl2 (N = Mo, 6a;W, 6b). Starting from ReCl5 the structurally (X-ray) characterized byproduct (bipy)ReIVCl4 (2b) is also formed. Dirhenium heptaoxide (7) is converted into the complex (bipy)ReVIIO3Cl (8) upon treatment with chlorotrimethylsilane in the presence of 2,2′-bipyridine, thus being now easily available a key compound in rhenium chemistry. The new imido complexes of composition (bipy)MoVI(NR)2Cl2 [R = C(H3)3, 9a; C6H5, 9b] are accessible from 6a and the corresponding silylated amines. The rhenium and tungsten complexes 2b and 6b, resp., exhibit octahedral structures in the crystal, with that of 6b being distorted as a result of different ligands and intermolecular contacts.

Concave Reagents, 5 Bimacrocyclic 1,10‐Phenanthroline Cyclophanes

Abstract: The addition of lithium aryls 3 to 1,10-phenanthroline (2), functionalization of the rearomatized bisadduct 8b to the tetraphenol 8d, and cyclization of 8d with two equivalents of an α,ω-ditosylate 9 led to a highly symmetrical, conformer-free bimacrocyclic 1,10-phenanthroline 10a in which the basic and coordinating region possesses a concave shielding.

η2‐tert‐Butylphosphaacetylen‐Komplexe des Titanocens und Zirkonocens

Abstract: η2-tert-Butylphosphaacetylene Complexes of Titanocene and Zirconocene (η2-2-tert-Butyl-1-phosphaacetylene)(trimethylphosphane) complexes of titanocene (5a) and zirconocene (5b) are obtained in 85 and 73% yield, resp., by the reaction of 2-tert-butyl-1-phosphaacetylene (1) with the corresponding bis(trimethylphosphane)metallocenes 2a (MTi) and 2b (MZr). For the preparation of 5b it is more convenient to start with the (1-butene)zirconocene complex 3 or with the tolanezirconocene complex 4. With the help of a suitable Lewis-acid, e.g. triethylborane, trimethylphosphane can be eliminated from 5a or 5b to yield the new coordinatively unsaturated phosphaalkyne metallocenes 6a (MTi) and 6b (MZr), which are unstable and oligomerize easily to the dimer 7 (MTi) and trimer 8 (MZr); only the monomer 6a can be observed in solution. The crystal structures of 5a, 7, and 8 are determined by X-ray analyses.

Partial Hydrogenation: From Anthracene to Coronene

Abstract: Reduktion kondensierter Arene mit-Boranen. – Partielle Hydrierung: Anthracen bis Coronen Tetrapropyldiboran(6) (TPDB) katalysiert die Hydrierung polycyclisher Arene [z. B. Anthracen (A), Tetracen (TET), Pyren (PY), Perylen (PER) oder Coronen (C)] unter Wasserstoff-Druck bei 200°C. In einigen Fallen konnen sehr hohe Ausbeuten an Hydroarenen erzielt werden [z. B. Tetrahydroanthracen (4H-A), Octahydroanthracen (8H-A), Dodecahydrotetracen (12H-TET), Tetrahydropyren (4H-PY), Hexahydroperylen (6H-PER) oder Hexahydrocornen (6H-C)]. Neben unterschiedlichen kleinen Mengen an Perhydroarenen bilden sich nach langer Reaktionszeit aus samtlichen Arenen auch C – C-Spaltungsprodukte.