bluuebunny/crossref_metadata_2025 huggingface dataset:
Neue zwitterionische λ51‐Spirosilicate: Synthesen, Einkristall‐Röntgenstrukturanalysen und Festkörper‐NMR‐Untersuchungen
Authors: Tacke Reinhold , Lopex‐Mras Angel , Sperlich Jörg , Strohmann Carsten , Kuhs Werner F. , Mattern Günter , Sebald Angelika
Published: July 2007

New Zwitterionic λ51‐Spirosilicates: Syntheses, Single‐Crystal X‐Ray Structure Analyses, and Solid‐State NMR Studies

The zwitterionic spirocyclic λ51‐silicates bis[3,4,5,6‐tetrabromo‐1,2‐benzenediolato(2‐)][2‐(pyrrolidinio)ethyl]silicate (5; and its monohydrate 5 · H2O) and bis[1,2‐benzenediolato(2–)]1‐[(dimethylammonio)methyl]silicate (6) were synthesized by various methods including Si – C bond cleavage reactions. The crystal structures of 5, 5·H2O, and 6 were investigated by X‐ray diffarction. Furthermore, 5, 5·H2O, 6, and the related zwitterionic λ51‐spirosilicates 1·1/4 CH3CN, 2·CH3CN, 3·CH3CN, and 4 were characterized by solid‐state NMR spectroscopy (29Si and 15N CP/MAS). The pentacoordinate silicon atoms of 5, 5·H2O (two cystallographically independent zwitterions and two crystallographically independent water molecules), and 6 (two crystallographically independent zwitterions) are surrounded by four oxygen atoms and one carbon atom. The coordination polyhedrons around the silicon atoms of 5 and 6 can be described as distorted (5) or nearly ideal (6) trigonal bipyramids, the carbon atoms being in equatorial positions. 5 forms intramolecular and 6 intermolecular (→ for‐mation of dimeric units) N – H…O hydrogen bonds. The co‐ordination polyhedrons around the two crystallographically independent silicon atoms of 5·H2O can be described as a nearly ideal and slightly distorted square pyramid, respectively, the carbon atoms being in the apical positions. In the crystal lattice of 5·H2O, intermolecular N – H…O O – H…O hydrogen bonds between the zwitterions and water molecules are observed. The results obtained by X‐ray diffraction and solid‐state NMR spectroscopy are consistent for each compound studied.
Struktur und Dynamik von Lanthanoid‐Tetraazacyclododecantetraacetat‐(DOTA‐)Komplexen in Lösung
Authors: Hoeft Simone , Roth Klaus
Published: July 2007

Structure and Dynamics of Lanthanoid Tetraazacyclododecanetetraacetate DOTA Complexes in Solution

In aqueous solution lanthanoid DOTA complexes exist as a mixture of two stereoisomers, and their structures have been determined from the dipolar parts of the observed 1H‐NMR chemical shifts for EuDOTA and YbDOTA. The relative concentration of the δ(δδδδ) isomer decreases with decreasing ionic radius. For EuDOTA a 1:4 mixture is observed, and the main isomer has a δ(λλλλ) structure which is also found in the solid state. Two independent intramolecular isomerizations were detected by 1H‐NMR Exchange Spectroscopy (EXSY). The faster process is the rotation of the four acetate substituents around the C–N bonds [δ(λλλλ)→δ(λλλλ)isomerization]. The cyclododecane ring inversion is slower [δ(λλλλ)→δ(δδδδ) isomerization]. The intramolecular racemization of the δ(λλλλ) main isomer into its δ(δδδδ) enantiomer includes two successive isomerizations in a δ(λλλλ)→δ(λλλλ)→δ(δδδδ) sequence and is the slowest process.
Synthese und Reaktionen von (η51‐Pentamethylcyclopentadienyl)1‐ und (η51‐Ethyltetramethylcyclopentadienyl)titantrifluorid
Authors: Sotoodeh Mansoreh , Leichtweis Iring , Roesky Herbert W. , Noltemeyer Mathias , Schmidt Hans‐Georg
Published: July 2007

Preparation and Reactions of (η51‐Pentamethylcyclopentadienyl)1‐ and (η51‐Ethyltetramethylcyclopentadienyl)titanium Trifluoride[1]

Compound Cp*TiCl3 (1, Cp*η51‐Me5C5) reacts with an excess of AsF3 to yield the crystalline complex [Cp*TiF3]2·2 AsF3 (2). AsF3 can be removed from 2 in vacuo to give Cp*TiF3 (3). Complex (η51‐EtMe4C5)TiCl3 (4) is converted by an excess of AsF3 to (η51‐EtMe4C5)TiF3 (5). Compound 3 reacts with a lithium 1,3‐diketonate to form the hexacoordinated complex (6) and with a lithium benzamidinate to yield pentacoordinated Cp*TiF2[(Me3SiN)2 C‐C6H4OMe‐(4)] (7): The reaction of 3 with Ph3PNSiMe3 and C2H2(Ph2PNSiMe3)2 leads to Cp*TiF2NPPh3 (8) and (Cp*TiF2NPPh2)2C2H2 (9), respectively. X‐Ray structure analyses of compounds 2 and 5–9 have been performed.
Metallorganische Lewis‐Säuren, XLVIII. Neue Vorläufer metallorganischer, kationischer Lewis‐Säuren mit zwei freien Koordinationsstellen: (OC)4Re(OEt2)FBF3 und (OC)2(PPh3)2Ru(FBF3)2
Authors: Krämer Roland , Lippmann Elisabeth , Noisternig Karin , Steimann Manfred , Nagel Ulrich , Beck Wolfgang
Published: July 2007

Organometallic Lewis Acids, XLVIII[1]. – New Precursors to Organometallic Cationic Lewis Acids with two Accessible Coordination Sites: (OC)4Re(OEt2)FBF3 and (OC)2 (PPh3)2Ru(FBF3)2

The allyl transfer reaction between Re(CO)5− and [(η31‐allyl)PdCl]2 complexes leads to (allyl)rhenium complexes (η31‐H2CCR1CR2R3) Re(CO)4 (1: R1, R2, R3H; 2; R2, R3H, R1Me; 3: R1, R2H, R3Me; 4: R1H, R2, R3Me). The 2‐methylallyl complex 2 has been characterized by low‐temperature X‐ray diffraction. Protonation of 1 with HBF4 · OEt2 in CH2Cl2 gives the complex (OC)4Re(OEt2)FBF3 (5), which is a precursor for the 14 e− System “(OC)4Re+”. THF and H2O replace the diethyl ether in 5 to give [(OC)4Re(solvent)2]BF4 (6, 7). The reaction of (OC)2(PPh3)2RuCl2 with AgBF4 yields the complex (OC)2 (PPh3)2Ru(FBF3)2 (8), which can be considered as a precursor for the 14 e− cation “(OC)2 (PPh3)2Ru2+” and reacts with H2O to give [(OC)2 (PPh3)2Ru(F)(H2O)]BF4 (9). Complexes 5–9 are characterized by IR, 1H‐, 13C‐, 31P‐and 19F‐NMR spectroscopy.
Tetraalkylhydrido‐und Tetraalkylmethyldialuminat(5) mit Aluminium – Aluminium‐Bindung: [R2Al – AlXR2]− {RCH(SiMe3)2; XH, Me}
Authors: Uhl Werner , Vester Annegret
Published: July 2007

Tetraalkylhydrido‐and Tetraalkylmethyldialuminate(5) with Aluminium – Aluminium Bond: [R2Al – AlXR2]– {RCH(SiMe3)2; XH, Me}

Tetrakis[bis(trimethylsilyl)methyl]dialuminium(4) (1) with an aluminium – aluminium bond reacts with tert1‐butyllithium in the presence of the chelating tetramethylethylenediamine (TMEDA) to give a hydridodialuminate(5) 2 [R2Al – AlHR2]− {RCH(SiMe3)2} by β1‐elimination and addition of the hydride anion to one aluminium atom. By treatment of 1 with methyllithium a similar product is formed containing a methyl group bound to aluminium: [R2A1 – AlMeR2]– 3. As shown by crystal structure determination the aluminium – aluminium bond of both molecules is not bridged. Instead, the compounds contain a saturated, four‐coordinated aluminium neighbouring an unsaturated, threefold coordinated aluminium atom. While in the hydrogen compound 2 the aluminium – aluminium bond length [266.7(3) pm] remains unaffected in comparison to the neutral starting compound 1, it is lengthened in the methyl derivative 3 by 9 pm to 275.2(3) pm probably due to the higher sterical demand of the methyl group.
Synthesis of Isomerically Pure Organodihydrofullerenes
Authors: Hirsch Andreas , Grösser Thomas , Skiebe Andreas , Soi Antonio
Published: July 2007

Controlled two‐step nucleophilic hydroalkylations, hydroar‐ylations as well as hydrostannylations of fullerene‐60 (1) and fullerene‐70 (2) lead to defined organodihydrofullerenes C60HR and C70HR. NMR investigations show that only one isomer of each organodihydrofullerene with Cs symmetry is formed. In all cases the addition takes place at a double bond separating two six‐membered rings of the fullerene core. In this way a variety of organodihydrofullerenes also carrying functional groups have been synthesized.
Oxidative Spaltung von Poly(o1‐phenylendiselenid)
Authors: Heckmann Gert , Wolmershäuser Gotthelf
Published: July 2007

Oxidative Cleavage of Poly(o1‐phenylenediselenide)

Poly(o1‐phenylenediselenide) is cleaved at the Se–Se bond by treatment with SOCl2 to give benzene‐1,2‐bis(selenenyl chloride) (2) and benzene‐1,2‐bis(selenium trichloride) (3), respectively. In the solid state 2 is dimerized by Se…Se bonds whereas 3 is monomeric having terminal as well as intramolecular bridging Cl atoms. Treatment of 2 with SbCl5 gives an ionic compound (4) with a dimeric cation exhibiting a weak SeSe bond and SbCl6– as a counterion 3 reacts with W(CO)6 to give trigonal prismatic dicarbonyl bis(o1‐phenylenediselenolato)tungsten (5).
Metallinduzierte und basenkatalysierte 2‐Propinyl‐Allenyl‐Umlagerung in [(HCCCH2)(2,4,6‐tBu3C6H2O)]PMoCP(CO)2
Authors: Leise Michael , Lang Heinrich , Imhof Wolfgang , Zsolnai Laszlo
Published: July 2007

Metal‐Induced and Base‐Catalyzed 2‐Propynyl‐Allenyl Rearrangement in [(HCCCH2)(2,4,6‐tBu3C6H2O)]PMoCP(CO)2

The synthesis and reactivity of [(HCCCH2)(2,4,6‐tBu31‐C6H2O)]PMoCp(CO)2 (3) is described. [(HCCCH2)(R)]PCl (1) reacts with NaMoCp(CO)3 (2) to afford the s̀3,λ41‐phosphanediyl compounds 3. With NEt3 a prototropic rearrangement of the 2‐propynyl ligand of 3 to an allenyl group in [(H2CCCH)(R)]PMoCp(CO)2 (5) is observed. However, with Cr(CO)5 · THF a metal‐induced rearrangement of the 2‐propynyl unit in 3 yields η3‐{(2,4,6‐tBu3C6H2O)[(CO)5Cr]PCHCCH2}MoCp(CO)2 (7). Complex 7 contains a 1‐phosphaallyl system, which is functionalized by an exocyclic CC double bond X‐ray structure analyses of 3 and 7 are performed.
(tert1‐Butylisonitril)kupfer(I)1‐Komplexe mit Acetylacetonato‐oder η51‐Cyclopentadienyl‐Liganden
Authors: Kruck Thomas , Terfloth Christian
Published: July 2007

(tert1‐Butylisonitrile)copper(I) Complexes with Acetylacetonato‐or η51‐Cyclopentadienyl Ligands

Copper(I) complexes of the type acacCu(CNtBu) (1) and CpCu(CNtBu) (2) are accessible by the reaction of [ClCu‐(CNtBu)]4 with M(β1‐diket) or MCp (MLi, Na, K, Tl), respectively. hfacCu(CNtBu)2 (3) and hfacCu(CNtBu)3 (4) are prepared by adding molar amounts of tBuNC to hfacCu(CNtBu) (1b).
Azabicyclononane durch Fragmentierung, II. Regiospezifische (Grob‐)Fragmentierung zur Darstellung von 3‐Azabicyclononanen
Authors: Risch Nikolaus , Billerbeck Ulrich , Meyer‐Roscher Bernd
Published: July 2007

Azabicyclononanes by Fragmentation, II[1]. – Synthesis of 3‐Azabicyclononanes by Regiospecific (Grob) Fragmentation

Clemmensen reduction of the non‐enolizable β1‐dioxo group in the 1‐azaadamantanedione derivative 1 gives the β1‐hydroxy ketone 2, which is converted to the thioesters 3. Treatment of 3a or 3b with nBu3SnH/toluene yields the partially deoxygenated monoketone 4. Chlorination of 2 with SOCl2 generates 6 (geminal dichlorination). Dehalogenation with nBu3SnH produces 5. On the other hand, 2 can be monochlorinated to give 7, selectively. Preparative Grob fragmentation of the aza‐tricyclic skeleton in 7 regiospecifically provides the 3‐azabicyclo[3.3.1]nonane derivative 8. An even better access to 8 from 2 proceeds via an intermediate tosylate.
Complexation with Diol Host Compounds, 12. Synthesis and Solid‐State Inclusion Properties of Bis(diarylhydroxymethyl)1‐Substituted 1,1′‐Binaphthyls. Crystal Structures of a Host and Its Pyridine Clathrate
Authors: Weber Edwin , Skobridis Konstantinos , Wierig Andreas , Barbour Leonard J. , Caira Mino R. , Nassimbeni Luigi R.
Published: July 2007

A series of new clathrate host molecules1 – 8containing two bis(diarylhydroxymethyl) groups attached to different positions (2,2′ or 8,8′) of a 1,1′‐binaphthyl frame have been synthesized. Their clathrate formation properties with organic guests including alcohols, amines, ketones, and other dipolar aprotic compounds or aromatic hydrocarbons are reported (74 examples of clathrates) together with the results of solvent competition experiments for the parent host compound. The inclusion formation and the clathrate stoichiometries depend on the structure of the host molecules in a systematic manner. The crystal structures of the free parent host1and its pyridine clathrate (1 : 3) have been determined by X‐ray diffraction. The molecular structure of the host is similar in the two species involving an intramolecular hydrogen bond between the host hydroxyls. No other hydrogen bond is involved in the free host case while in the pyridine inclusion compound the second host hydroxyl forms a hydrogen bond with the nitrogen of one pyridine guest which is surrounded by two unbound pyridine species such as to form clusters of three pyridine guests enclosed in the cavities between the host molecules. Thermal analysis corresponds with the two binding states of the pyridine molecules in the clathrate.
Stereoselektive Protonierung von Carbanionen, 1. Diastereoselektive Protonierung von C – H‐aktivierten Cyclohexan‐Derivaten
Authors: Gerlach Uwe , Haubenreich Thomas , Hünig Siegfried , Keita Yango
Published: July 2007

The diastereoselectivity of the kinetically controlled protonation of carbanions derived from 4‐tert1‐butyl‐1‐X‐cyclohexanes (1: XCN, 2: XCO2Me, 2‐Si: XC(OMe)OSiMe3, 3: XCOPh, 4: XSO2Ph) is systematically investigated. By variation of (a) the base for deprotonation of 1 – 4, (b) OH‐, NH‐, and CH‐proton sources, (c) added salts, Lewis bases, and acids, (d) solvents (cf. Tables 2 – 5) the cis/trans ratios of diastereomers could be influenced as follows: 1: 41/59→85/15; 2: 26/74→73/27; 3: 26/74→>93/<3; 4: 1/99→37/63. The results are discussed with regard to structure and aggregation of 1Li to 4Li and compared with relevant data from the literature. It is concluded that so far an empirical approach to high diastereoselectivities cannot be avoided and that the results cannot be predicted from the ratios obtained by the much slower alkylation reactions.
Darstellung, Struktur und Eigenschaften von harnstoffverbrückten cyclischen Phosphoniumsalzen mit Phosphor‐Phosphor‐, Phosphor‐Arsen‐, Phosphor‐Antimon‐und Phosphor‐Zinn‐Bindung
Authors: Vogt Roland , Jones Peter G. , Schmutzler Reinhard
Published: July 2007

Preparation, Structure, and Properties of Urea‐Bridged Cyclic Phosphonium Salts with Phosphorus‐Phosphorus, Phosphorus‐Arsenic, Phosphorus‐Antimony, and Phosphorus‐Tin Bonds

N‐[tert1‐Butyl(phenyl)phosphanyl]‐N,N′‐dimethyl‐N′‐(trimethylsilyl)urea (2) reacts with organodichlorophosphanes with cleavage of the Si – N bond to form the cyclic phosphanylphosphonium chlorides 3a – i containing the grouping [λ3P – λ4P+]Cl–. Evidence was obtained for the existence of an equilibrium in solution between the ionic phosphonium structure 3 and a covalent form. The position of the equilibrium is determined by the nature of the group R at λ3P. Reaction of the phosphonium salts 3a – i with Na[BPh4] furnished the phosphonium tetraphenylborates 4a – i containing the grouping [λ3P – λ4P+][BPh4]–. In the reaction of 2 with organodichloroarsanes the arsanyl‐phosphonium chlorides 5a and 5b with the grouping [λ3As – λ4P+] were formed. By treatment of 5a and 5b with Na[BPh4] the corresponding tetraphenylborates 6a and 6b were produced. Further cyclic phosphonium salts containing a heteroatom‐phosphorus bond with the complex chloro anions [AsCl4]–, [SbCl4]–, and [Me2SnCl4]2– were formed in the reaction of 2 with the chlorides AsCl3, SbCl3 and Me2SnCl2. – The structures of 4h and 6a were confirmed by low‐temperature X‐ray crystal structure determination; the P – P bond length of 4h is 222.3(2) pm, the P – As bond length of 6a 234.6, 234.1(2) pm in two independent cations.
Novel Spherand‐Type Calixarenes – Synthesis, Conformational Studies, and Isomer Separation
Authors: Yamato Takehiko , Hasegawa Ken‐Ichi , Saruwatari Yoshiyuki , Doamekpor Louis Korbla
Published: July 2007

The novel macrocyclic compounds hexahydroxy[1.0.1.0.1.0]‐6b and octahydroxy[1.0.1.0.1.0.1.0]metacyclophane 6c have been prepared in 50–70% yield by base‐catalyzed condensation of 5,5′‐di‐tert1‐butyl‐2,2′‐dihydroxybiphenyl (5) with formaldehyde in xylene. The conformations of trimer 6b and tetramer 6c have been evaluated from their dynamic 1H‐NMR spectra. Methylation of the hydroxyl groups of 6b and 6c with MeI gives the corresponding methoxy[1n]metabiphenylophanes 7b and 7c in good yields. The metacyclophane 7b has been found to consist of two isomers, out of which one was separated pure. The structural characterization of these products is discussed.
Metallabicyclo[3.1.0]hexene und deren Umlagerung zu Vinylmetallacyclobutenen (M=Ti, Zr)
Authors: Binger Paul , Müller Patrik , Langhauser Franz , Sandmeyer Frank , Philipps Petra , Gabor Barbara , Mynott Richard
Published: July 2007

Metallabicyclo[3.1.0]hexenes and Their Rearrangement to Vinylmetallacyclobutenes (M=Ti, Zr)

Alkyne‐metallocene complexes, e.g. the alkynetitanocenes 1a, b, the alkyne(trimethylphosphane)titanocenes 2a, b and the alkyne(trimethylphosphane)zirconocenes 5a–d react readily with 3,3‐dimethylcyclopropene (3a) and 3,3‐diphenylcyclopropene (3b) to give the corresponding bis(η5‐cyclopentadienyl)‐metallabicyclo[3.1.0]hexene derivatives 4a–e, (M=Ti) and 6a–g (M=Zr) in high yields. In an analogous manner, metallabicyclo[3.1.0]hexene derivatives of Ti or Zr can be prepared from 1,2‐diphenylcyclopropene(trimethylphosphane)metallocenes 9 and 10 and 2‐butyne to yield 11 and 12 and from benzyne 3a or 3b to yield 8a and 8b. Some of these metallabicyclo[3.1.0]hexene derivatives rearrange quantitatively to the corresponding 4‐(dimethylvinyl)‐1‐metalla‐2‐cyclobutene derivates 16 and 17a and 4‐(diphenylvinyl)‐1‐metalla‐2‐cyclobutenes 15c and 17a–c when they are heated to 60–80°C for several hours. The 4‐(diphenylvinyl)‐1‐titana‐2‐cyclobutene derivatives 15a–c can also be obtained by reaction of [(2,2‐diphenylvinyl)carbene](trimethylphosphane)‐titanocen (13) with disubstituted alkynes such as tolane, phenyltrimethylsilylacetylene and bis(trimethylsily)acetylene. With other alkynes, e.g. 2‐butyne, 1‐butyne, 1‐propyne or acetylene, 13 reacts by polymerization of these alkynes; the corresponding 4‐vinyl‐1‐titanacyclobutene derivatives could not be detected in the reaction mixture. All new metallacycles are fully characterized by spectroscopic methods, extensive 1H‐ and 13C‐NMR studies provide unambiguous proof of their structures.
Beiträge zur Chemie des Bors, 218[1]. Über die Reaktion von 9‐Fluorenyliden‐tetramethylpiperidino‐boran mit Nitrilen und Isonitrilen: Azaborafluoranthene und Ketenimino‐azaborolidine
Authors: Mayer Erwin P. , Nöth Heinrich
Published: July 2007

Contributions to the Chemistry of Boron, 218[1].–On the Reaction of 9‐Fluorenylidene‐tetramethylpiperidino‐borane with Nitriles and Isonitriles: Azaborafluoranthenes and Ketenimino‐azaborolidines

9‐Fluorenylidene‐tetramethylpiperidino‐borane 1 reacts with nitriles not in a [2 + 2] cycloaddition manner but to form azaborafluoranthenes 3 whose BNC4 ring shows a C–B–N–C element reminiscent to a butadiene unit as revealed by an X‐ray structure analysis of 3a. An unexpected 3:1 reaction occurs between tert‐butyl isonitrile and 1 leading to the keteneimino azaborolidine 10. Its central ring shows an envelope conformation. 1 is fairly inert towards olefins. Out of 5 examples only 1,1‐diethoxyethene gave the [2 + 2] cycloaddition product, i.e. the boretane 4.
Weitere Reaktionen des Amino(imino)borans Me3Si(tBu)N*B*NtBu und des Alkyliden(amino)borans Me3Si(tBu)N=B=CHtBu
Authors: Braunschweig Holge , Paetzold Peter , Spaniol Thomas P.
Published: July 2007

Further Reactions of the Amino(imino)borane Me3Si(tBu)N*B*NtBu and the Alkylidene(amino)borane Me3Si(tBu)‐N=B=CHtBu

The alkylidenetantalum complexes [tBuHCTaCl3(THF)2] (1b), [PhHCTaCl3(PMe3)2] (1c), and [tBuHCTa(CH2tBu)3] (1d) were treated with the amino(imino)borane Me3Si(t‐Bu)N*B*NtBu (2d). From 1b and 2d, the alkylidene(amino)borane Me3Si(tBu)NBCHtBu (7) is formed by metathesis. The 1:2 reaction of 1c with 2d gives the azadiboracyclobutane [–N(tBu)–B(X)–CHPh–B(X)–] [6d, XMe3Si(tBu)N]. The six‐membered ring compound [–N(tBu)BR–N(tBu)–SiMe2–CH2–TaR(CHtBu)–] (8, R=CH2tBu) is obtained from 1d and 2d; the product 8 crystallizes in the space group P 21/c. The borane 7 is attacked at the BC double bond by Et2NH, tBuCHO, and Me3SiN3 giving the diamino(neopentyl)borane 9 by protolysis, the oxaboracyclobutane 10 by [2 + 2] cycloaddition, and the azaboracyclopropane 11 by cycloaddition and elimination of N2, respectively.
Crown Ether‐Bearing Dihydroazulens[1]: Synthesis and Photochromism of a Benzo[15]crown‐5 Derivative
Authors: Fischer Christian , Daub Jörg
Published: July 2007

Photosensitive crown ether 1 composed of 1,8a‐dihydroazulene as a photodynamic unit and a benzo[15]crown‐5 ether subgroup has been synthesized from C‐7‐substituted cycloheptatriene 8, which has been obtained by nucleophilic addition of 4‐acetylbenzo[15]crown‐5 (6) to tropenylium tetrafluoroborate (7). Dehydrogenation of dicyanovinyl derivative 9 leads to heptafulvene 2 which thermally rearranges to dihydroazulene 1. Attempts to synthesize 1 according to the „[8 + 2]‐cycloaddition route”︁ have been unsuccessful. Crown ether 1 shows photochromic bistability with a photochemically driven forward and a thermal back reaction. The spectroscopic properties of 1 and the photochemical isomerization 1 → 2 have been shown to be almost insensitive to sodium iodide addition. The rate of the thermal back reaction 2 → 1 slightly is affected by sodium iodide addition.
Double‐Layered 1,4‐Distyrylbenzene Chromophores–Synthesis, UV and Fluorescene Spectra
Authors: König Burkhard , Knieriem Burkhard , Meijere Armin De
Published: July 2007

The reaction of [2.2]paracyclophane (1) with liquid bromine affords a 1:1 mixture of only two isomeric products, the pseudo‐para 2 and pseudo‐ortho tetrabromide 3. The structure of the pseudo‐para isomer 2 has been determined by X‐ray structure analysis. Fourfold palladium‐catalyzed coupling with styrenes and with methyl acrylate converts 2 and 3 into double‐layered derivatives as e.g. 6a, 7a, and 7b, respectively. The molecular structure of 7a has been established by X‐ray structure analysis. The UV and fluorescence spectra of a variety of substituted products are reported and compared with those of the parent chromophors 2,5‐dimethyl‐1,4‐distyrylbenzene (16) and 2,5‐diethyl‐1,4‐bis(phenylethynyl)benzene (17), respectively.
Synthese und Komplexierung von Dithiatetrazadiborocinen
Authors: Schmid Günter , Gehrke Helmut , Kolorz Hans‐Ulrich , Boese Roland
Published: July 2007

Synthesis and Complexation of Dithiatetrazadiborocines

(Dialkylamino)dichloroboranes R2NBCl2 react with N,N'‐bis‐(trimethylsilyl)sulfur diimide to give a novel class of compounds, the eight‐membered rings 3,7‐bis(dialkylamino)‐3H,7H‐1λ4,5λ4,2,4,6,8,3,7‐dithiatetrazadiborocines (1). The derivates with R = n‐propyl (1a), isopropyl (1b), and n‐butyl (1c) have been synthesized and characterized. The X‐ray structure analysis of 1b shows the molecule to have a boat‐like configuration with two NSN functions connected via the BNR2 groups. Although the B atoms are linked to three N atoms, only the exocyclic nitrogen is engaged in π bond interactions with the boron. 1b reacts with W(CO)5(THF) to form the dinuclear complex 2, which is also investigated by means of an X‐ray structure analysis. One W(CO)5 fragment is coordinated to a nitrogen atom of one NSN unit, whereas another W(CO)5 group is linked to the S atom of the second SN2 function. However, the original sulfur diimide has changed into a sulfur diamide group HN–S–NH. A similar change of a NSN unit happens on treatment of 1b with Cp(CO)3WH leading to 3. As the X‐ray structure analysis shows, in 3 again one sulfur diimide group retains its original character. The second SN2 unit has turned into a sulfur amide function, where one N atom binds the H atom of Cp(CO)3WH, the other one is linked to one of the CO ligands to form a carbonyl bridge between N and W. Among a series of other complexes only TiCl4 has additionally been found to react with 1b to yield 1b · 2 TiCl4, the structure of which is still unknown.
Preparation of Benzo‐diimidazoles and Benzo‐triimidazoles
Authors: Mataka Shuntaro , Irie Takashi , Ikezaki Youji , Tashiro Masashi
Published: July 2007

The reaction of benzenehexamine (1), benzene‐1,2,3,4‐tetramine (4), and benzene‐1,2,4,5‐tetramine (6) with aryl isocyanate 2 afforded the corresponding hexakis(N'‐arylureido)benzene 3 and the tetrakis(N'‐arylureido)benzenes 5 and 7. Pyrolysis of 3, 5, and 7 at 400°C furnished the benzo‐triimidazoletrione 8 and benzo‐biimidazolediones 10 and 11.
LiClO4‐katalysierte nucleophile Addition an α‐chirale Aldehyde, Aldimine und Oxirane
Authors: Ipaktschi Junes , Heydari Akbar
Published: July 2007

LiClO4‐Catalyzed Nucleophilic Addition to α‐Chiral Aldehydes, Aldimines, and Oxiranes

The diastereoselectivity of lithium perchlorate‐induced addition of trimethylsilyl cyanide and O‐silylated ketene acetals to α‐chiral aldehydes is studied. Whereas aldehyde 1 reacts with the ketene acetal 2 exclusively to form the syn‐ester 3, a divergent selectivity is observed in the case of trimethylsilyl cyanide addition to 5 and 11a–c. Also the reaction of O‐silylated ketene acetals with aldimines 16 in the presence of lithium perchlorate proceeds smoothly to afford the corresponding β‐amino esters 17 in high yields. While the silyl ketene acetal of methyl acetate leads preferentially to the corresponding anti‐diastereomer, in the case of the silyl ketene acetal of methyl isobutyrate a syn‐/anti‐selectivity in the range of 79:21 to 44:56 is observed. In the presence of lithium perchlorate solution in ether the oxiranes 27a–d undergo facile nucleophilic ring opening reactions with 2, 29, and 30.
Metallkomplexe mit biologisch wichtigen Liganden, LXV. Chirale Halbsandwich‐Komplexe von Cobalt(III), Rhodium(III), Iridium(III) und Ruthenium(II) mit α‐Aminosäureamid‐, Glycinnitril‐ und Peptidester‐Liganden
Authors: Krämer Roland , Maurus Michael , Bergs Ralph , Polborn Kurt , Sünkel Karlheinz , Wagner Barbara , Beck Wolfgang
Published: July 2007

Metal Complexes with Biologically Important Ligands, LXV[1]. — Chiral Half‐Sandwich Complexes of Cobalt(III), Rhodium(III), Iridium(III), and Ruthenium(II) with α‐Amino Amide, Glycinenitrile, and Peptide Ester Ligands

Cp*Co(CO)I2 (Cp* = η5‐C5Me5), [(η6‐arene)RuCl2]2 (arene = p‐cymene, hexamethylbenzene), and [Cp*MCl2]2 (M = Rh, Ir) react with α‐amino amides and various peptide esters to give the N,O‐chelate complexes [Cp*(I)Co — NH2C(H)(R1)C(NHR2)‐O]+ (1), [(η6‐arene)(Cl)Ru — NH2C(H)(R1)C(NHR2)O]+ (2), and [CP*(Cl)M—NH2CH2C(NHR)O]+ (M = Rh, Ir) (5, in solution), respectively. In the solid state the ligands are η1N‐bonded in 5. By deprotonation of the peptide bond in 2 and 5 the neutral N, N‐chelate complexes (η6‐arene)(Cl)Ru — NH2C(H)(R1)C(O)‐N̊2 (6) and Cp*(Cl)M — NH2C(H)(R1)C(O)NR2 (M = Rh, Ir) (7) have been obtained. Glycinenitrile is η1‐bonded in (η6‐p‐cymene)(Cl)2Ru(NH2CH2CN) (3) and Cp*(Cl)2Rh(NH2CH2CN) (4). Double deprotonated triglycine methyl ester is a N,N,N‐tridentate ligand in (η6‐C6Me6)Ru(NH2CH2C(O)NCH2C(O)‐NCH2CO2Me) (8). The anions of L‐asparagine and of aspartame (L‐aspartyl‐L‐phenylalanine methyl ester) give the complexes 9–12 with tridentate O,N,O‐ or O,N,N‐chelate ligands. The crystal structures of 1d (L = glyglyOEt), 5a (L = glycinamide), 6e (L = glyglyOEt), and 7k (L = glyglyglyOEt) have been determined by X‐ray structural analysis.
Osmiumkomplexe vom Halbsandwichtyp mit Oximen, Iminen und Azavinylidenen als Liganden
Authors: Daniel Thomas , Knaup Wolfgang , Dziallas Michael , Werner Helmut
Published: July 2007

Osmium Complexes of the Half‐Sandwich Type with Oximes, Imines, and Azavinylidenes as Ligand

Azavinylideneosmium complexes of the general composition [(arene)Os(NCRR)(L)]X (L = PMe3, PMetBu2, PiPr3) have been prepared by two methods. The first one uses the hydrido compound [C6H6OsHI(PMetBu2)] (2) and oximes HONCRR as starting materials and proceeds via the oxime complexes [C6H6OsH{N(OH)CRR}(PMetBu2)]PF6 (10, 11) as intermediates. They react with Al2O3 with elimination of water to give the final products 6–9. The second method starts with the dichloro‐ or diiodoosmium(II) compounds [(arene)OxX2(PR3)] (14, 16, 19, 21; arene = C6H6, 1,3,5‐Me3C6H3i R = Me, iPr) which upon treatment with HN = CPh2 or imine derivatives XNC(R)Ph (X = Li, SiMe3) afford the azavinylidene complexes 13b, 18, 23, 33. In the reactions with HNCPh2, the corresponding imine complexes [(arene)OsX(NHCPh2)‐(PR3)]X (15, 17, 20, 22) are formed as the primary products. Whereas nucleophilic addition of H– and CH3— to the N=C carbon atom of [C6H6Os(NCPh2)(PMetBu2)]+ (6) gives the imidoosmium(II) compounds [C6H6Os(NCRPh2)(PMetBu2)] (24, 25), the reaction of [C6H6Os(NCPh2)(PiPr3)]PF6 (13 b) with LiAlH(OtBu)3 yields the hydrido(imino) derivative [C6H6OsH(NHCPh2)(PiPr3)]PF6 (26). The bis(azido) complex [C6H6Os(N3)2(PiPr3)] (27), which is prepared either from 13 b or [C6H6OsI2(PiPr3)] (14) and NaN3, undergoes a [3 + 2] cycloaddition reaction with C2(CO2Me)2. Two isomeric (triazole)osmium compounds 28, 29 have been isolated. Treatment of [C6H6Os(NCRPh)(PiPr3)]PF6 with HX (X = O2CCF3) leads to addition of the acid to the OsN bond and, for R = Ph (13 b), by subsequent elimination of HX to the formation of a five‐membered metallaheterocycle 31. The X‐ray structural analysis of [C6H6Os(NCPh2)(PMetBu2)]PF6 (6) reveals an allene‐like arrangement of the ligands and substituents around the OsNC unit.
Beiträge zur Chemie des Bors, 220. Untersuchungen über Diborylmethane
Authors: Ederer Bernd , Metzler Nils , Nöth Heinrich
Published: July 2007

Contributions to the Chemistry of Boron 220[1]. — Investigations on Diborylmethanes

A convenient synthesis and spectroscopic properties of various organyl‐halogen‐substituted diborylmethanes (RXB)2CH2 (2a — e, R = Me, Et, Pr, Ph, Mes) are described. Reaction of bis(dichloroboryl)methane (1 b) with tBuLi in a 1:2 ratio leads to isomerization of the tert‐butyl group, whereas bis(dimethoxyboryl)methane (1a) reacts with 5 equivalents of tBuLi to yield tri‐tert‐butylborane and lithium di‐tert‐butylethyleneborate (9). Borate 9 is characterized NMR‐spectroscopically and by derivatization with Me3SiCl. Bis[alkinyl(dialkylamino)‐boryl]methanes 10a—c are obtained from the bis[chloro(dialkylamino)boryl]methanes 5a, b and LiCCPh or LiCCMe, respectively. 10c is characterized by an X‐ray crystal structure analysis which allows, for the first time, a direct comparison of an sp‐ and an sp3‐carbon atom bound to the same boron atom. Finally, an almost linear relationship between dL13C of the methylene group and dL11B in diborylmethanes has been detected.
Umwandlungen zwischen Ru3‐fixierten Azoalkan‐ und Dialkylhydrazin‐Baueinheiten
Authors: Hansert Bernhard , Vahrenkamp Heinrich
Published: July 2007

Interconversions Between Ru3‐Bound Azoalkane and Dialkylhydrazine‐Derived Building Units

Reactions involving hydrogen transfer have been investigated starting from the azoalkane‐bridged clusters Ru3(CO)9‐(RCH2NNCH2R) (1a, R = H; 1b, R = Me). In boiling toluene they are isomerized to the hydrazonide‐bridged clusters HRu3(CO)9(RCH2N—NCHR) (2a, R = H; 2b, R = Me). Pd/C‐catalyzed hydrogenation converts both compound types into the hydrazide‐bridged clusters HRu3(CO)9(RCH2N—NHCH2R) (3a, R = H; 3b, R = Me). Hydride attachment to 1 and 2 and deprotonation of 3 yield a common anionic intermediate 4 which is converted into 3 upon protonation. While deuteration experiments and NMR spectra indicate that the anionic intermediate equilibrates between the N—H and Ru—H isomers, aurations of deprotonated clusters with Ph3PAuCl yield the Ru—Au‐connected clusters Ph3PAuRu3(CO)9(EtN—NCHMe) (5) and Ph3PAuRu3(CO)9(MeN—NHMe) (6). The reversible cluster expansion of 2b with Fe(CO)3 fragments which results in the formation of FeRu3(CO)12(μ4‐η2‐N2Et2) (7) involves a reversible reconversion of the hydrazonide ligand to the azoalkane ligand.
Tricarbonylchromium complexes of centropolyindans, 3. Synthesis and structural investigation of tricarbonylchromium mono‐, bis‐, and tris‐Complexes of triptindan
Authors: Ceccon Alberto , Gambaro Alessandro , Manoli Francesco , Venzo Alfonso , Ganis Paolo , Valle Giovanni , Kuck Dietmar
Published: July 2007

The reaction of 9H,10H‐4b,9a([1,2]benzenomethano)indeno[1,2‐a]indene (triptindan, TRIP) with Cr(CO)6 in Bu2O/THF (9:1) affords a monocomplex (A) together with two bis‐Cr(CO)3 complexes (B and C) and one tris‐Cr(CO)3 complex (D). The relative yields of the four complexes as well as their tendency to lose Cr(CO)3 are related to stabilizing intramolecular factors. All the Cr(CO)3 units of the complexes A, B, and D are coordinated in the isoclined orientation with respect to the polar axis of the ligand, whereas complex C bears one isoclined and one anticlined Cr(CO)3 unit. The results of X‐ray measurements support the hypothesis of weak attractive electronic interactions bonds between the oxygen atoms of the carbonyl groups and polarized faces of benzene rings.
Structure and Spectroscopic Properties of p‐Benzoquinone Diazides
Authors: Sander Wolfram , Bucher Götz , Komnick Peter , Morawietz Jens , Bubenitschek Peter , Jones Peter G. , Chrapkowski Axel
Published: July 2007

A series of p‐benzoquinone diazides were investigated by 13C‐NMR and IR spectroscopy as well as by semiempirical and abinitio calculations. In addition, X‐ray structure analyses of the parent compound and three derivatives were performed. The electronic structure and effects of substituents can be described in terms of diazoketo and diazonium phenolate resonance structures. While alkyl groups as substituents have only a minor influence on quinone diazides, electron‐withdrawing substituents lead to a larger participation of the aromatic diazonium phenolate structure. Benzoannellation, on the other hand, leads to a decrease of the interaction between the keto and diazo functional group and to properties more reminiscent of “ordinary” ketones and diazo compounds.
A group 4 metallocene template synthesis of β,γ‐unsaturated ε‐hydroxy carboxylic acids
Authors: Berlekamp Martin , Erker Gerhard , Schönecker Bruno , Krieg Reimar , Rheingold Arnold L.
Published: July 2007

The reaction of (butadiene)zirconocene with hexacarbonyltungsten gives the metallacyclic [(π‐allyl)zirconoxy]carbene complex 7. This reagent adds to a variety of ketones to yield chiral nine‐membered metallacyclic ring systems (8). These systems are thus formed by means of 1,4‐selective coupling reactions of 1,3‐butadiene with W(CO)6 and an organic carbonyl compound at the zirconocene template. The ketones subjected to react with 7 include benzophenone, methyl vinyl ketone, cyclopentanone, and 3‐methoxyestra‐1,3,5(10)‐trien‐17‐one (12). The coupling products of 7 with cyclopentanone (8c) and 12 (8d‐A) were characterized by X‐ray crystal structure analyses. Of the four possible diastereomeric nine‐membered metallacyclic coupling products of 7 with 12 a single isomer [8d‐A with (13'S,17'R,2,3,4‐pS) configuration] was formed with ≥98% selectivity and isolated in 95% yield. Treatment of the complexes 8 in tetrahydrofuran with water and pyridine N‐oxide very effectively removed both transition metals with the formation of the corresponding β,γ‐unsaturated ε‐hydroxy carboxylic acids. The overall reaction sequence has thus converted the steroid ketone 12 very selectively to 5‐[3‐methoxy‐17β‐hydroxyestra‐1,3,5(10)‐trien‐17α‐yl]‐(E)‐pent‐3‐enoic acid (10d)
Pseudoazulene als Dienophile in der [4 + 2]‐Cycloaddition mit inversem Elektronenbedarf
Authors: Reimers Uwe , Seitz Gunther
Published: July 2007

Pseudoazulenes as Dienophiles in the [4 + 2] Cycloaddition with Inverse Electron Demand

[4 + 2] Cycloadditions of the pseudoazulenes 2, 6, 13, 18, and 22 to the extremely electron‐deficient s‐cis‐fixed diazadiene system of 3,6‐bis(trifluoromethyl)‐1,2,4,5‐tetrazine (1) are described. Probably according to a two‐step mechanism the pseudoazulenes 2, 6, and 18 react with 1 to form the corresponding cycloadducts followed by elimination of nitrogen and oxidation to furnish the novel 14 systems 5, 12, and 21 in rather high yields. In contrast, with the cyclopenta[d]‐pyridazines 13 and 22 the azines 17 and 26, respectively, are formed exclusively.
Reaktionen eines freien Stannaimins und von Basen‐stabilisierten Stannylenen
Authors: Ossig Günter , Meller Anton , Freitag Stefanie , Herbst‐Irmer Regine , Sheldrick George M.
Published: July 2007

Reactions of a Free Stannaimine and of Base‐Stabilized Stannylenes

The free stannaimine A reacts with methyllithium, 2,6‐diisopropylaniline, and methyl vinyl ketone to give the corresponding 1,2‐addition products (to the SnN bond) 2, 3, and 10. With 2,6‐diisopropylphenyl isocyanate and benzaldehyde [2 + 2] cycloadditions to the CO bonds lead to 4 and 5, while with benzonitrile oxide and acroleine [2 + 3] and [2 + 4] cyclo‐additions produce 8 and 9. The pyridine adducts bis‐[bis(trimethylsilyl)amino]stannylene and ‐germylene react with aryl azides to give the corresponding derivatives of tri‐amino‐2‐pyridylstannane 11 and ‐germane 12. Bis[2‐pyridyl‐bis(trimethylsilyl)methyl]stannylene upon treatment with aryl azides form the 1‐aza‐8‐stannabicyclo[3.2.0]octa‐2,4,6‐triene systems 13 and 14 via stannaimine intermediates. X‐ray structure analyses are presented for 3, 11, and 13.
Blausäure‐N‐methylid: Darstellung, spektroskopische Eigenschaften und seine Beziehung zu anderen C2H3N‐Isomeren
Authors: Maier Günther , Schmidt Christiane , Reisenauer Hans Peter , Endlein Edgar , Becker Dieter , Eckwert Jürgen , Andes Jr. B. Hess , Schaad Lawrence J.
Published: July 2007

Hydrogen Cyanide N‐Methylide: Preparation, Spectroscopic Identification, and Its Relationship to Other C2H3N Isomers

With the intention of isolating 1H‐azirene (8) we studied several precursors which should offer an entry into the C2H3N potential energy hypersurface. It was found that in addition to the known isomers 1, 2, 3, and 6 hydrogen cyanide N‐methylide (5) — and probably aminoacetylene (4) — can be detected in an argon matrix at 10 K. No spectroscopic evidence for the formation of 1H‐azirene (8) was found. In other words, the first six members 1—6 are now all identified. The elucidation of the structure of the new C2H3N species is based on the comparison of the observed IR spectra with those calculated by ab initio methods.
Bis[(di‐tert‐butylphosphanyl)methyl]methylphosphan
Authors: Krill Jochen , Shevchenko Igor V. , Fischer Axel , Jones Peter G. , Schmutzler Reinhard
Published: July 2007

Bis[(di‐tert‐butylphosphanyl)methyl]methylphosphane[1]

The synthesis of [(di‐tert‐butylphosphanyl)methyl]dimethyl‐phosphane (3) and of the title compound 5 is described. 5 reacts with sulfur to form the trisulfide 6. Both 3 and 5 behave as bidentate ligands in forming the molybdenum complexes 8 and 10, which are characterized by single crystal X‐ray structure determinations. 10 reacts with sulfur to yield the sulfide 11, which decomposes in solution within 6 h.
Strukturell unterschiedliche Metallamide (Li, Cu, Ag, Cd) mit dem Chelatliganden [tBu–N–SiMe2–O–C6H4–O–Sime2–N–tBu]2–
Authors: Veith Michael , Woll Karl Ludwig
Published: July 2007

Structurally Different Metal Amides (Li, Cu, Ag, Cd) with the Chelating Ligand [tBu‐N–SiMe2–O–C6H4–O–SiMe2–N–tBu]2–

Herrn Professor Heinrich Nöth zum 65. Geburtstag gewidmet.

The amino hydrogen atoms in the silylamine o‐C6H4O2(Me2SiN(H)tBu)2 (1) can be replaced by monovalent (Li, Cu, Ag) or divalent (Cd) metallic elements. Whereas the lithium compound is obtained as an ether adduct, [C6H4O2(Me2SiNtBu)2]Li2 · OEt2 (2), the copper and silver compounds are solvens‐free. The latter two form similar dimers comprising four metal atoms: [C6H4O2(Me2SiNtBu)2]2Cu4 (3) and [C6H4O2 (Me2SiNtBu)2]2Ag4 (4). The cadmium compound is also a dimer with two ligands and two cadmium atoms making up the molecule, [C6H4O2(Me2SiNtBu)2]2Cd2 (5). X‐ray structure analyses reveal that in all compounds the metallic elements are highly coordinated by N and O interactions, with coordination numbers of 4 (2, 3, 4) and 5 (5). The oxygen contacts are quite long ranging from 260 to 301 pm. In the Cu und Ag compounds quadratic planar arrangements at the metals are found (bridged by nitrogen) with distances Cu–Cu 262.6(2)–270.1(2) and Ag–Ag 291.7(1)–301.8(2) pm.
Übergangsmetall‐Stannyl‐Komplexe, 9[1]. Substitutions‐Reaktionen der anionischen Hydrid‐Komplexe [(π‐MeC5H4)(CO)2MnH]– und [(π‐Aromat)(CO)2CrH]–
Authors: Mock Stefan , Schubert Ulrich
Published: July 2007

Transition Metal Stannyl Complexes, 9[1]. – Substitution Reactions of the Anionic Hydrido Complexes [(π‐MeC5H4)‐(CO)2MnH]– and [(π‐Arene)(CO)2CrH]–

The anionic hydrido complexes K[(π‐MeC5H4)(CO)2MnH] (2c) and K[(π‐arene)(CO)2CrH] (π‐arene = C6H6, C6H5Me, 1,2,3‐C6H3Me3, C6Me6, C6H5Ph, indan) (5a–f) are spontaneously formed on stirring THF solutions of the dianionic complexes K2 [(π‐MeC5H4)(CO)2Mn] (1) or K2[(π‐arene)(CO)2Cr] (4) at – 78°C. The dianionic complexes are obtained by potassium naphthalenide reduction of (π‐MeC5H4)(CO)2MnL or (π‐arene)(CO)2CrL (L = pyridine or THF). Reaction of 2c with Me3SnCl or Ph2SnCl2 yields the bis(stannyl) complexes Cp*(CO)2Mn(SnR3)2 (SnR3 = SnMe3, SnPh2Cl), while reactions with the „smaller”︁ stannanes Me2SnCl2 or Et2SnCl2 results in the SnR2‐bridged complexes [Cp′(CO)2Mn]2(μ‐SnR2)((Mn–Mn). The bis(stannyl) complexes (π‐arene)(CO)2Cr(SnR2Cl)2 (R = Me, Ph) are obtained from 5 and R2SnCl2. However, the reaction is strongly influenced by steric effects: with Me2SnCl2, bis(stannyl) complexes are obtained for π‐arene = C6H6, C6H5Me, 1,2,3‐C6H3Me3, or C6Me6, with Ph2SnCl2 only for π‐arene = C6H6 and C6H5Me. Reaction of the sterically demanding complexes K[(π‐C6H5Ph)(CO)2CrH] or K[(π‐indan)(CO)2CrH] with Ph2SnCl2 stops at the stage of the anionic stannyl complexes K[(π‐arene)(CO)2Cr‐SnPh2Cl].
Synthesis and Structure of a Silyl‐aminoalane Ring
Authors: Janik Jurik F. , Duesler Eileen N. , Paine Robert T.
Published: July 2007

The reactions of hydrazine with tris(trimethylsilyl)aluminium‐ether have been studied: Reactant ratios of 0.5:1 and 0.8:1 produce the cyclic aminoalane [(Me3Si)2AlN(H)(SiMe3)]2 (1), which is formed by N–N bond cleavage and silyl group migration from aluminium to nitrogen. Pyrolysis under NH3 of a polymeric product formed from a 1:1 reaction produces an AlN/Si3N4 composite.
Anticancer Agents, 19[1]. Synthesis of the Reduced A‐Unit (CI) of the Antitumor Antibiotic CC‐1065
Authors: Tietze Lutz F. , Grote Thomas
Published: July 2007

The synthesis of the reduced A‐unit 2 (CI) of CC‐1065 (1) using a metal‐mediated cyclisation is described. Reaction of N‐allyl‐N‐benzylaniline 4b and zirconocene(methyl) chloride with tert‐BuLi leads via a zirconocene‐stabilized benzyne complex 5 to the 3,4‐difunctionalized indoline derivative 7, which was converted in five steps into 2.
Die verschiedenartigen Konformationen N‐Trimethylsilyl‐substituierter p‐Phenylendiamin‐Derivate: Untersuchungen an Einkristallen sowie in der Gasphase
Authors: Bock Hans , Meuret Jochen , Näther Christian , Krynitz Ulrich
Published: July 2007

Structures of Sterically Overcrowded and Charge‐Perturbed Molecules, 38[1]. — The Different Conformations of N‐Trimethylsilyl‐Substituted p‐Phenylenediamine Derivatives: Investigation of Single Crystals and in the Gas Phase

The ESR‐proven generation of a Wurster's Blue radical anion by one‐electron reduction of N,N,N′,N′‐tetrakis(trimethylsilyl)‐p‐phenylenediamine is rationalized by a posterior singlecrystal structure determination of the neutral molecule, which demonstrates inter alia that the bulky [(H3C)3Si]2N substituents are twisted out of the benzene plane by 83°. In contrast, the skeleton of the sterically congested N,N′‐bis(trimethylsilyl)‐p‐phenylenediamine remains almost planar and, accordingly, allows nN/π interaction between the p‐type nitrogen electron pairs of the also flattened [(H3C)3Si]HN groups and the benzene π system. These conformational differences are reflected in the gas‐phase photoelectron spectra, in which nN/π ionisation bands are split by less than 1 eV or more than 3 eV, respectively. The evidence for analogous structures of the two organosilicon p‐phenylenediamine derivatives in solution is confirmed by geometry‐optimized AM1 calculations, which readily explain the surprising insertion of an extra electron into an already electron‐rich molecule.
Bis(pentamethylcyclopentadienyl)methanol: Synthese, Struktur und Derivatisierung
Authors: Jutzi Peter , Mix Andreas , Lindermeier Tanja , Stammler Hans‐Georg , Neumann Beate
Published: July 2007

Bis(pentamethylcyclopentadienyl)methanol: Synthesis, Structure, and Derivatization

Bis(pentamethylcyclopentadienyl) ketone (1) reacts at low temperatures with LiAlH4 to form in good yields (pentamethylcyclopentadienyl)methanol (2) and its corresponding intramolecular Diels‐Alder product 3 in a ca. 2:1 ratio. The alcohol 2 is separated from the tetracyclic compound 3 by crystallisation at −70°C from hexane/pyridine as pyridine adduct. The pyridine‐free alcohol 2 is available by repeated dissolving of the adduct in hexane and removal of the volatile components in vacuo. The alcohol tends to intramolecular [4 + 2] cycloaddition even at room temperature with formation of 3. A derivatization of 2 is possible by deprotonation with alkyllithium compounds, which leads to the alcoholate 4, and subsequent treatment with phosgen and tosyl chloride, thus affording the chloroformate 6 and the tosylate 7, respectively, in good yields. The thermolabile tosylate 7 decomposes to pentamethylbenzene or, under basic conditions, to the pentacyclic compound 7.
A Molecular‐Dynamics Simulation of the Complex Formation between Methyl (R)/(S)‐2‐Chloropropionate and Heptakis(3‐O‐acetyl‐2,6‐di‐O‐pentyl)‐β‐cyclodextrin
Authors: Köhler Jutta E. H. , Hohla Manfred , Richters Martina , König Wilfried A.
Published: July 2007

The energies of complexation of methyl (R)/(S)‐2‐chloropropionate [(R)/(S)‐2] with heptakis(3‐O‐acetyl‐2,6‐di‐O‐pentyl)‐β‐cyclodextrin (1) and the structures of the corresponding complexes were determined by molecular‐dynamcis (MD) simulations at 300 and 333 K. The geometry of the complexes, the conformations of complexed and uncomplexed 1 and (R)/(S)‐2 and the closest H–H distances between host and guest in the complexes were determined from the trajectories. The results correspond to the experimental findings from enantioselective gas chromatography.
Charge‐Transfer‐Komplexe von Metalldithiolenen, XIII. cis‐trans‐Photoisomerisierbare Viologene als redoxaktive Akzeptoren —Synthese und elektrische Leitfähigkeit
Authors: Schmauch Georg , Knoch Falk , Kisch Horst
Published: July 2007

Charge‐Transfer Complexes of Metal Dithiolenes, XIII[1]. ‐ cis‐trans‐Photoisomerisable Viologens as Redoxactive Acceptors — Synthesis and Electrical Conductivity

Ion Pair Charge‐Transfer (IPCT) complexes of the type [A2+[ML2]2−} (1a‐f to 4a‐f) are synthesized from dianionic metal dithiolenes [M = Ni, Zn, L = cis‐1,2‐dicyano‐1,2‐ethene‐dithiolate (mnt2−), 2‐thioxo‐1,3‐dithiol‐4,5‐dithiolate (dmit2‐)] and dicationic viologens [A2+ = 4,4′‐(1,2‐ethenediyl)bis(1‐alkylpyridinium)]. The acceptors can exist as cis/trans isomers and may have coordinating properties in the case of 1‐cyanoalkyl groups. The IPCT bands are in the range of 500 to 1200 nm and their energy follows the Hush‐Marcus relation. For the nickel complexes the reorganization energy amounts to 73, for the zinc compounds to 115 kJ/mol. As shown by X‐ray analysis of {A2+[Ni(mnt)2]2−} (2d), A2+ = trans‐4,4′‐(1,2‐ethenediyl)‐bis[1‐(3‐cyanopropyl)pyridinium], the structure consists of stacks of alternating donors and acceptors with a typical plane‐to‐plane distance of 350 pm. There is no interaction between the cyano group of the acceptor and the nickel atom of the donor. The electrical conductivities of the nickel compounds are in the range of 5 · 10−6 to 3 · 10−11 Ω−1 cm−1, and the corresponding activation energies vary from 0.24 to 0.61 eV. For the dmit complexes these values agree well with the free activation enthalpy of the electron transfer reaction A2+ + [ML2]2− → A+ + [ML2]− calculated from the Hush‐Marcus model. This suggests that charge carrier generation occurs by electron transfer. When a trans acceptor is replaced by its cis isomer in [A2+[NiL2]2−}, conductivity changes from 5 · 10−7 to 5 · 10−6 Ω−1 cm−1 and the activation energy from 0.43 to 0.24 eV, when L ‐ dmit2− but stays at about 1 · 10−8 Ω−1 cm−1 for L = mnt2−.