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  • Inorganic Chemistry  (3.613)
  • Chemical Engineering  (3.294)
  • 1990-1994  (6.907)
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  • 1
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1693-1697 
    ISSN: 0009-2940
    Schlagwort(e): Nonclassical T1(I)-T1(I) interactions ; Thallium, fulvalene complex ; (Cyclopentadienyl)thallium complex ; 5,5′;-Pentafulvalene, 1,1′;,3,3′;-tetra-tert-butyl-dithallium ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: (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) InteractionsReaction 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.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 423-431 
    ISSN: 0009-2940
    Schlagwort(e): Bicyclopropyl / Diphosphines, chelating ligands / Rhodium complexes / Gold complexes / Phosphine sulfides / Phosphine-boranes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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 Å. 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.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1805-1811 
    ISSN: 0044-2313
    Schlagwort(e): Dithiolene chelates ; titanocene complexes ; η5-trimethylelementcyclopentadienyl complexes ; temperature-dependent 1H NMR ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: 1,1′-Disubstituted Titanocene Dithiolene Chelates of Type (η5-Me3EC5H4)2Ti(S2C2R2) (E = C, Si, Ge)Reaction of the titanocene dichlorides (η5-Me3EC5H4)2TiCl2 (E = C, 1a; E = Si, 1b; E = Ge, 1c) with the 1,2-dithiolates (NaS)2C2H2, (NaS)2C2(CN)2 or (LiS)2C6H3Me-4 gave the new titanocene dithiolene chelates (η5-Me3EC5H4)2Ti(S2C2H2) (2a-c), (η5-Me3EC5H4)2Ti[S2C2(CN)2] (3a-c) and (η5-Me3EC5H4)2Ti(S2C6H3Me-4) (4a-c). These have been characterized by 1H NMR, IR, and mass spectroscopy, and have been compared with the unsubstituted η5-C5H5 analogues 2d, 3d and 4d. Activation energies for the chelate ring inversion in solution of 2a-c, 3a-d and 4a-c have been estimated by temperature-dependent 1H NMR spectroscopy.
    Notizen: Die Reaktion der Titanocen-dichloride (η5-Me3EC5H4)2TiCl2 (E = C, 1a; E = Si, 1b; E = Ge, 1c) mit den 1,2-Dithiolaten (NaS)2C2H2, (NaS)2C2(CN)2 oder (LiS)2C6H3Me-4 ergab die neuen Titanocen-dithiolen-Chelate (η5Me3EC5H4)2Ti(S2C2H2) (2a-c), (η5-Me3EC5H4)2Ti[S2C2(CN)2] (3a-c) und (η5-Me3EC5H4)2Ti(S2C6H3Me-4) (4a-c). Sie wurden durch 1H-NMR-, IR- und Massen-Spektroskopie charakterisiert und mit den unsubstituierten η5-C5H5-Analoga 2d, 3d und 4d verglichen. Für 2a-c, 3a-d und 4a-c wurden die Aktivierungs-energien der Chelatringinversion in Lösung aus temperatur-abhängig aufgenommenen 1H-NMR-Spektren abgeschätzt.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2487-2492 
    ISSN: 0009-2940
    Schlagwort(e): 2-Azapropenylium salts ; 2-Azaallenium salts ; 2-Azaallylium salts ; Carbamates, N-(dialkoxymethylene) ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 1,1,3,3-Tetraalkoxy-2-azaallylium Salts: Synthesis and Stereochemical Properties The title salts 1 were synthesized in satisfactory yield by regioselective alkylation at the carboxyl oxygen atom of N-(dialkoxymethylene)carbamates 7 with oxonium salts 8. According to IR, 1H- and 13C-NMR spectra, in solution a bent 2-azaallyl cation structure is strongly favored over a linear cumulenic form. Dynamic NMR spectra indicate a barrier of ca. 11.7 kcal/mol between these two valence isomers. - Quantum mechanical calculations (ab initio 3-21G optimizations) on the model compound 1,1,3,3-tetrahydroxy-2-azaallylium (9) confirm the 2-azaallyl structure as the global minimum on the energy hyperface. 2-Azaallenium structures are calculated to be ca. 20 kcal/mol higher in energy. The conformations of the hydroxy groups depend on the C - N - C bond angle. The best isomeric N-protonated N-(dialkoxymethylene)carbamate 10a is predicted to be favored by ca. 3 kcal/mol over the energy lowest 2-azaallylium structure 9a.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 612 (1992), S. 56-62 
    ISSN: 0044-2313
    Schlagwort(e): 1λ5,3λ5-diphosphete ; addition compounds with GeCl2, SnCl2, (CO)5W(Z-cyclooctene) ; n.m.r., i.r., mass spectra ; X-ray structures ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: 1,1,3,3-Tetrakis(dimethylamino)-1λ5,3λ5-diphosphete as Ligand in Coordination Compounds1,1,3,3-Tetrakis(dimethylamino)-1λ5,3λ5-diphosphete, 1, reacts with GeCl2 · 1,4-dioxane, SnCl2, and (CO)5W(Z-cyclooctene) to give the complexes {HCP[N(CH3)2]2}2 · GeCl2, 3, {HCP[N(CH3)2]2}2 · SnCl2, 4, and {HCP[N(CH3)2]2}2 · W(CO)5, 5, respectively. The n.m.r., mass, and i.r. spectra of the new compounds as well as the crystal and molecular structures of 3 and 4 are reported and the bonding situation in compounds 3-5 is discussed.
    Notizen: 1,1,3,3-Tetrakis(dimethylamino)-1λ5,3λ5-diphosphet, 1 bildet mit GeCl2 · 1,4-Dioxan, SnCl2 bzw. (CO)5W(Z-cycloocten) die komplexe {HCP[N(CH3)2]2}2 · GeCl2, 3, {HCP[N(CH3)2]2}2 · SnCl2, 4, bzw. {HCP[N(CH3)2]2}2 · W(CO)5, 5. Die NMR-, Massen- und IR-Spektren der neuen Verbindungen sowie die Kristall- und Molekülstruktur von 3 und 4 werden mitgeteilt und die Bindungsverhältnisse in den Verbindungen 3-5 diskutiert.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 613 (1992), S. 119-122 
    ISSN: 0044-2313
    Schlagwort(e): 1,1-Dithio-oxalate ; Cu12Cu11 complex ; EPR spectra ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: 1,1-Dithio-oxalate as Bridging Ligand in Bi- and Trinuclear Complexes1,1-Dithio-oxalate (i-dto), a four-dentate chalcogenrich ligand, possesses the unique constitution of C—C coupled CO2 and CS2. Due to its ambident behaviour i-dto forms mononuclear complexes and defined homo- and heterobimetallic bi- and trinuclear complexes. Obviously as a combined result of the symmetry and the electron distribution the ligand acts preferably bridging. The formation of coordination polymers can be prevented using coordinatively halfside-saturated species „(Ph3P)2M+“ (M = Cu, Ag). From EPR investigations of a trinuclear Cu21Cu11 complex we could get information about the coordination geometry and the electron distribution.
    Notizen: 1,1-Dithio-oxalat (i-dto) als vierzähniger chalkogenreicher Ligand hat die interessante Konstitution von C—C-gekoppeltem CO2 und CS2. Aufgrund seines ambidenten Verhaltens bildet i-dto definierte Einkernkomplexe sowie homo- und heterobimetallische Zwei- und Dreikernkomplexe, wobei die Funktion als Brückenligand auch infolge der Symmetrie und Elektronenverteilung des Liganden offenbar bevorzugt ist. Die Bildung von Koordinationspolymeren läßt sich durch koordinativ halbseitig gesättigte Komplexfragmente „(Ph3P)2M+“ (M = Cu, Ag) unterbinden. Aus EPR-spektroskopischen Untersuchungen eines dreikernigen Cu21Cu11-Komplexes konnten Informationen über die Koordinationsgeometrie und Elektronenverteilung erhalten werden.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 7
    ISSN: 0044-2313
    Schlagwort(e): Thiooxalates ; 1,1-Dithiooxalate ; 1,1-Dithiooxalic ester ; transition metal complex ; Crystal structures ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: 1,1-Dithiooxalic Acid Derivatives as Ligands in Transition Metal Complexes: Structure of O-Methyl-1,1-dithiooxalato-bis(triphenylphosphine)copper(I) and silver(I)Despite O-Alkyl-1,1-dithiooxalates are also tetradentate thioligands their tendency towards the formation of multi-nuclear bridged chelates as found for the basic 1,1-dithiooxalate does practically not exist because of derivatisation. The reaction with triphenylposphinemetal(I)-halogenides yields defined mono-nuclear mixed ligand complexes: O-Methyl-1,1-dithiooxalato-bis(triphenylphosphine)copper(I) (2) and silver(I) (1). X-ray analysis shows that both complexes (1 and 2) are isostructural and crystallize in the monoclinic space group P21/n: (Ph3P)2Ag(S2C2O2Me) (1) with a = 12.794(1), b = 21.314(4), c = 13.560(1) Å, β = 97.983(6)°, and (Ph3P)2Cu(S2C2O2Me) (2) with a = 12.622(1), b = 21.196(2), c = 13.426(1) Å, β = 96.533(7)°. These complexes are the first authentic examples of exclusively end-on coordinated thiooxalate.
    Notizen: Obwohl potentiell auch vierzähnig, ist die Tendenz von O-Alkyl(bzw. Aryl)-1,1-dithio-oxalaten zur Ausbildung von Brücken in Mehrkern-Chelaten durch die Derivatisierung gegenüber dem Stammliganden 1,1-Dithiooxalat praktisch nicht mehr vorhanden. Durch Umsetzung mit Triphenylphosphinmetall(I)-halogeniden sind definierte einkernige Gemischtligandenkomplexe zugänglich. O-Methyl-1,1-dithiooxalato-bis(triphenylphosphin)kupfer(I) und -silber(I) konnten mittels Röntgenkristallstrukturanalyse strukturell gesichert werden. Beide Komplexe sind isostrukturell und kristallisieren in der monoklinen Raumgruppe P21/n: (Ph3P)2Ag(S2C2O2Me) (1), mit a = 12,794(1), b = 21,314(4), c = 13,560(1) Å, β = 97,983(6)° und (Ph3P)2Cu(S2C2O2Me) (2), mit a = 12,622(1), b = 21,196(2), c = 13,426(1) Å, β = 96,533(7)°. Diese beiden Komplexe sind die ersten strukturell gesicherten Vertreter mit ausschließlich end-on koordiniertem Thiooxalat.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2221-2226 
    ISSN: 0009-2940
    Schlagwort(e): Silanes, alkynyl[(trimethylstannyl)ethynyl]- ; 1,1-Ethyloboration, intermolecular ; 1,1-Vinyloboration, intramolecular ; Siloles ; Protodeborylation ; Protodestannylation ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis of alkynyl[(trimethylstannyl)ethynyl]dimethylsilanes 4 [alkynyl R1 - C≡C: R1 = Bu (b), tBu (c), iPent (d), Ph (e), SiMe3 (f)] is reported. The intermolecular 1,1-ethyloboration of 4 with triethylborane takes place selectively at the Sn - C≡ bond to give first the alkenyl(alkynyl)dimethylsilanes 5 and 6. There exists an equilibrium between 5 and 6, and compound 6 has the suitable stereochemistry for the final intramolecular 1,1-vinyloboration to form the 4-(diethylboryl)-2-(trimethylstannyl)siloles 7. Protodeborylation of 7 with water gives the 2-(trimethylstannyl)siloles 8, and protodeborylation and protodestannylation with an excess of acetylacetone affords the siloles 9. Multinuclear NMR (1H-, 11B-, 13C-, 29Si-, and 119Sn-) serves for monitoring the reactions and for the characterization of the products.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2523-2529 
    ISSN: 0009-2940
    Schlagwort(e): Cyclohexane ; Liquid crystals ; Oxygen effect ; Scyllitol ; Stereochemistry ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 1,2,3,4,5,6-Hexa(eq)alkylcyclohexane Model Compounds for Structure-Property Comparisons of Saturated Discotic Liquid CrystalsThe new hydrocarbon (1α, 2β, 3α, 4β, 5α, 6β)-hexahexylcyclohexane (19) and a number of new and differently functionalized scyllo-hexaalkylcyclohexane derivatives (16a, b, 18a - c) with identical stereochemistry were synthesized stereospecifically starting from simple chemical materials. In comparison to the known scyllitol hexaester 1 and the hexaether 2 none of the novel compounds 16, 18, and 19 were thermomesomorphic. This extreme difference in the thermotropic liquid-crystalline behaviour of the hexa(eq)hydroxycyclohexane (scyllitol) derivatives 1 and 2 on the one hand and of our varied hexa(eq)alkylcyclohexans 16, 18, and 19 on the other obviously is a function of the presence and the position of the element oxygen within the side chains of these symmetric star-/disc-shaped compounds. Details concerning this oxygen effect are discussed briefly.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2681-2686 
    ISSN: 0009-2940
    Schlagwort(e): 1,2,3,4-Diazadiboretidines ; Oxadiazadiborolidines ; Triazadiborolidines ; Diazadiboracyclohexanes ; Tetraazadiboracyclohexanes ; 1,2,5,6,3,4,7,8-Tetraazatetraborocane ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 1,2,3,4-Diazadiboretidines: Reactions of a Novel Class of Unsaturated Boron-Nitrogen Four-Membered Rings1,2,3,4-Diazadiboretidines [=B(tBu)-B(tBu)=NR-NR=] (R=Et, iPr: 2a, b) belong to the hitherto unknown class of head-head isomers of the known 1,3,2,4-diazadiboretidines (1). They are formed from the diborane(4) Cl-B(tBu)-B(tBu)-Cl and the hydrazines RHN-NHR in the presence of NEt3 via the partially unsaturated four-membered rings [-B(tBu)Cl-B(tBu)=NR-NHR-] (4a, b), which are transformed into 2a, b by the abstraction of HCl by means of the base LiNC9H18. Whereas the pure products 2a, b are instable, solutions of 2a, b in alkanes can be handled at 0°C without considerable decomposition. Reaction of 2a, b with the amine oxide Me3NO leads to insertion of an O atom, reaction with diazoalkane tBuCR′N2 (R′ = H, Me) to insertion of its β-N atom, and reaction with the azide PhCH2N3 to insertion of a nitrene N atom into the B-B bond of 2a, b with formation of five-membered rings 5a, b or 6a, b or 7a, b, respectively. Six-membered rings 8a, 9a, 10a, respectively, are the products of the insertion of the C≡C unit of 3-hexyne, the N=N unit of EtO2C-N=N-CO2Et, or the unsaturated C atoms of two molecules of C≡NtBu into the B-B bond of 2a. The condensation of the diaminodiborane(4) Cl-B(NMe2)-B(NMe2)-Cl with the hydrazine EtHN-NHEt in the presence of NEt3 yields the corresponding eight-membered ring [-B(NMe2)-B(NMe2)-NEt-NEt-]2 (11), which crystallizes in a twist conformation with symmetry group D2.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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