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  • Chemistry  (47)
  • crystal structure  (3)
  • 1995-1999  (47)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Reaction of 1,3-Dialkyl-4,5-dimethylimidazol-2-ylidenes with 2-Bromo-2,3-dihydro-1H-1,3,2-diazaboroles (Alkyl=iPr and tBu)Dedicated to professor Adolf Zschunke on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 705-710 
    Details
    ISSN: 0009-2940
    Keywords: Boron ; Diazaboroles ; Carbenes ; Heterocycles ; Imidazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Bromo-2,3-dihydro-1H-1,3,2-diazaboroles (3a-c) were synthesized by cyclocondensation of dilithiated 1,4-diazabutadienes (5a-c) with boron tribromide in hexane. 3a was also obtained by sodium amalgam reduction was conducted in ether solvents, diboroxane (2) resulted as the main product. Compound 3a and 1,3-dialkyl-4,5-dimethylimidazol2-ylidenes (6a, b) underwent halide displacement to afford the borolylimidazolium salts 7a, b. Compounds 2, 3a-c, and 7a, b were characterized by elemental analyses and spectroscopic methods (1H, 11B, 13C NMR; Ir; MS). The molecular structures of 2 and 7a were established by single-crystal X-ray diffraction analyses.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300606
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  • 2
    Electronic Resource
    Electronic Resource
    Protolysis of Tri-tert-butylazadiboriridine: Formation of a B-H-B Bridge in Unusual Coordination (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 99-103 
    Details
    ISSN: 0009-2940
    Keywords: Tri-tert-butylazadiboriridine ; (Hydroboryl)(methoxyboryl)amine ; 2,3-μ-Hydro-1,2,3-azoniadiborata-l-cyclopropenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The B—B bond of tri-tert-butylazadiboriridine [—NR—BR—BR—] (R = tBu; 1) is oxidized by MeOH to give the (hydroboryl)(methoxyboryl)amine H—BR=NR-BR(OMe) (2a). μ-2,3-Hydroazoniadiborata-1-cyclopropenes [=NR—BR(X)—μH—BR=] (3a, 3c-e) are formed by the action of the acids HX upon 1. A similar hydrogen bridge as in 3a-e is formed during the hydroboration of 1 by catecholborane, yielding 3f. A B atom is identified in the products 3a-f to be planarly coordinated by four atoms, two of which are forming a BHB three-center bond with that B atom. This is a novel bonding situation in boron chemistry. The structures of the products are deduced from 1H-, 11B-, and 13C-NMR spectra and are confirmed by X-ray structural analyses of 2a, 3a, and 3c.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951280203
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  • 3
    Electronic Resource
    Electronic Resource
    Perfluororganochalkogensäuren in hohen Oxidationsstufen (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 423-428 
    Details
    ISSN: 0009-2940
    Keywords: Perfluoroethylselenoic acid, -salts, -esters ; Bis(pentafluorophenyl)tellurium(IV) acid, mixed anhydrides, -tellurium(VI) oxide, -tetrakis(trifluoromethylsulfonate), -dihydroxybis(trifluoromethylsulfonate) ; Pentafluorophenyltellurium(IV) oxoacid ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Perfluoroorganochalcogenic Acids in Higher Oxidation StatesPentafluoroethylseleninic acid is oxidized by KMnO4 in slightly alkaline aqueous solution to give K[C2F5SeO3]. With HClO4 the salt is converted into the free acid. Neutralisation of C2F5SeO3H with NaOH, Ag2O, NH3 + H2O provides the corresponding salts. The ethyl ester is made from Ag[C2F5SeO3] and C2H5I. Oxidation of C6F5TeC6F5 with concd. HNO3 yields C6F5Te(OH)ONO2 which on controlled hydrolyses gives (C6F5)2Te(OH)2. Strong acids like HClO4 or H2SO4 form mixed anhydrides like (C6F5)2Te(OH)ClO4 or (C6F5)2Te(OH)OS(O)2OTe(OH)(C6F5)2. For the latter compound a cyclic or noncyclic polycondensate form cannot be ruled out. Acidic 35% H2O2 solution oxidizes (C6F5)2Te(OH)2 at 40°C (48 h) to give (C6F5)2TeO2. This anhydride dissolves only in CF3SO3H forming (C6F5)2Te(OSO2CF3)4. It is soluble in CH3CN and reacts in solution with water to yield (C6F5)2Te(OH)2(OSO2CF3)2. Oxidation of C6F5TeTeC6F5 with concd. HNO3 provides oligomeric [C6F5Te(O)OH]x which still contains some HNO3. A single-crystal X-ray structure determination carried out on [(C6H5)4As][C2F5SeO3] shows convincingly that the central selenium atom is coordinated by three equivalent oxygen atoms with d(Se-O) = 1.614(3) Å, proving that Se has the oxidation state VI.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951280415
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  • 4
    Electronic Resource
    Electronic Resource
    Ethyloboration of Selenium Dioxide and Selenium Bis(tert-butylimide) - Molecular Structure of an Organo-Substituted Eight-Membered [-BOSeO-]2 Heterocycle (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 503-507 
    Details
    ISSN: 0009-2940
    Keywords: Selenium dioxide, 1,2-ethyloboration ; Selenium diimide, 1,2-ethyloboration ; Seleninic acid, ethane- ; Transborylation, OBEt2, O-9-BBN ; Ethene, elimination ; Amino(diethyl)boranes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Both selenium dioxide (1) and selenium bis(tert-butylimide) (2) react with triethylborane (A) by 1,2-ethyloboration. In the case of 1, ethane, ethene, diethylselane (4a), tetraethyldiboroxane (Et2B)2O (B), triethylboroxine (EtBO)3 (D) and a cyclic compound [-Et2BOSe(Et)O-]2 (52) are formed after heating to 65°C. Compound 52 is also formed when 1 reacts with B. Treatment of selenous acid (3) with A or, preferentially for synthetic purposes, with B provides further routes to 52. The reaction of the diimide 2 with A starts already below -50°C: a cyclic ethaneselenic acid derivative 6, Et2BN(tBu)-Se(Et)NtBu, is formed, and 6 starts to decompose at -50°C by elimination of ethene to give finally (tert-butylamino)diethylborane (8), bis(diethylboryl)-tert-butylamine (9), and Et2Se (4a). Transborylation of 52 with (9-BBN)2O (C) affords [-(9-BBN)OSe(Et)O-]2 (102), which crystallizes in the monoclinic space group P21/n with the lattice constants (118 K) a = 667.1(1), b = 1282.5(1), c = 1289.1(1) pm and β = 93.06(1)°. All reactions were monitored by 11B- and 77Se-NMR spectroscopy. Furthermore, the reactions of 1 with A and B and the transborylations were studied by 17O-NMR spectroscopy using the 17O-enriched compounds 1(17O), B(17O), C(17O), and D(17O).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290506
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  • 5
    Electronic Resource
    Electronic Resource
    Derivate des Imidazols, XIII. Carben-Komplexe des Siliciums und ZinnsHerrn Professor Peter Paetzold zum 60. Geburtstag gewidmet. (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 245-250 
    Details
    ISSN: 0009-2940
    Keywords: Carbenes ; Organosilicon compounds ; Organotin compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Imidazole Derivatives, XIII. - Carbene Complexes of Silicon and TinHerrn Professor Peter Paetzold zum 60. Geburtstag gewidmet.Stable adducts of the composition L · SiCl4 (2), L · SiR2Cl2 (3,4), and L · SnR2Cl2 (6) are formed by the reaction of the imidazol-2-ylidenes L (1) with the corresponding silicon and tin halides. For L = SiCl4 (2b; L = 1,3-diethyl-4,5-dimethylimidazol-2-ylidene) and L · SnPh2Cl2 (6c; L = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) the monomeric nature of the compounds containing pentacoordinated silicon and tin is established by X-ray structure analyses. The reaction of 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (1c) with SnCl2 leads to the formation of the monomeric stannylene complex L · SnCl2 (7c; L = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) whose molecular geometry indicates a week carbon-to-tin donor bond [Sn—C(1) 2.290(5) Å].
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951280307
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis, Structures and Properties of CF3S-Substituted Tellurium Compounds (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 477-480 
    Details
    ISSN: 0009-2940
    Keywords: Tellurium, bis(sulfinylamido)-, bis(trifluoromethylthio)- ; Thiachalcogenadiazole ; Ditelluradiazetidine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New preparations for the following compounds are described: Te(SCF3)2, Te(NSO)2, and Cl2Te(NSO)2. The catalytic or thermal SO2 elimination from Cl2Te(NSO)2 affords a coordinated or non-coordinated thiachalcogenadiazole. Conversions of these compounds are reported. Evidence for the proposed mechanism for the reaction between Te(NSO)2 and SbCl5 is provided. Cl4Te2N2(SCF3)2, prepared from TeCl4 and CF3SN(SiMe3)2, reacts with LiN(SiMe3)2 to form [(Me3Si)2N]4Te2N2(SCF3)2. An X-ray structural analysis of Cl4Te2N2(SCF3)2 is presented.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951280507
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  • 7
    Electronic Resource
    Electronic Resource
    Derivate des Imidazols, XIXPart XVIII: Ref.[1]. Koordination oder Reduktion? Zur Reaktion von 1,3-Diisopropyl-4,5-dimethylimidazol-2-yliden mit Schwefelhalogeniden und SchwefeloxidhalogenidenHerrn Professor Max Herberhold zum 60. Geburtstag gewidmet. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1579-1586 
    Details
    ISSN: 0009-2940
    Keywords: Imidazoles ; Carbenes ; Sulfur Compounds ; Fluorine Compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Imidazole Derivatives, XIXPart XVIII: Ref.[1] .  -  Coordination or reduction? On the Reaction of 1,3-Diisopropyl-4,5-dimethylimidazol-2-ylidene with Sulfur Halides and Sulfur Oxygen Halides Herrn Professor Max Herberhold zum 60. Geburtstag gewidmet.The reaction of 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (4, Im) with sulfur halides and sulfur oxygen halides may be described as a coordination (1) or reduction (2) process in respect to the sulfur centre. With SCl2 and SOCl2 the hypervalent sulfur compounds Im · SCl2 (5) and Im · S(O)Cl2 (13) are obtained. The SF2 adduct Im · SF2 (11) is formed on treatment of 5 with AgF. 13 is alkylated by methyl iodide to give the Im · S(Me)OCl2 cation (15). Surprisingly, reduction of the sulfur centre (2) occurs on treatment of 4 with SF4 to form the ImF+SF3- salt 18 containing the new SF3 anion. As expected, the same type of reaction occurs with the sulfuryl halides SO2ClF and SO2F2 to give the fluorosulfites ImCl+-SO2F- (21) and ImF+SO2F- (23). The X-ray structures of 5, 13 and 23 are reported.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961291228
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  • 8
    Electronic Resource
    Electronic Resource
    The Reduction of Oxalic Amidines with Metallic Lithium: Preparation of Lithiated Bisamides [R″N(RR′N)C=C(NRR′)NR″]Li2 and Their Use as Intermediates in a Novel Synthesis of Tetraaminoethenes (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 39-44 
    Details
    ISSN: 0009-2940
    Keywords: Oxalic Amidines ; Lithium diamides ; Calculations, PM3 ; Single-electron transfer ; Tetraaminoethenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reduction of the 1,4-diaza-1,3-butadiene substructure of hexasubstituted oxalic amidines with lithium metal yields the new lithium diamides 3. Subsequent reaction of 3 with various electrophiles gives the title substances 4, 5, and the acylated derivative 6, respectively. The first SET step in this reaction is the formation of monolithium radical anions 2, which were detected by EPR spectroscopy. The second electron transfer leads to the deeply colored dianions 3. - In the case of compound 3a [cis-3a · 3 Et2O], the X-ray crystal structure reveals the cisoid arrangement of the bidental ligand and three molecules of diethyl ether which are located in a 2:1 fashion in the first coordination sphere of the lithium cations. The NMR 2D-1H,6Li-HOESY investigations of 3a in [D10]diethyl ether/diethyl ether (8:1) show Li+ contacts to the hydrogen atoms of the ether molecules and to the ortho-hydrogen atoms of the aryl moieties. Results of semiempirical calculations (PM3) are throughout in acceptable agreement with the experimental data and explain the unusual coordination pattern of the lithium cations of compounds 3.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290110
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  • 9
    Electronic Resource
    Electronic Resource
    Reactivity of the Heavier Group-13 Monochlorides [{CH(SiMe3)2}2AlCl], InCl, TlCl, and of the Elements Ga and Hg Towards the Unsupported Ni-Ni Bond of [{(η5-Cp)Ni(PEt3)}2]  -  A Straightforward Synthetic Approach to the Synthesis of Mixed Main-Group/Transition-Metal Clusters Containing Unsupported Metal-Metal BondsDedicated to Prof. Dr. G Hutter on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1433-1440 
    Details
    ISSN: 0009-2940
    Keywords: Metal - metal bonds ; Insertion reactions ; Group-13 monochlorides ; Main-group elements ; Nickel ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dinuclear compound [{(η5 - Cp)Ni(PEt3)}2] (1) containing an unbridged Ni-Ni bond reacts with the heavier group 13 monochlorides [{CH(SiMe3)2)2}AlIIICl], InCl, and TlCl by scission of the metal-metal bond. In the case of InCl and TlCl the chloro-bridged dimmers [{(η5-Cp)Ni(PEt3)2ECl2Ecl}2] (E = In 2, Tl 5) were formed. The Tl compound 5 is unstable and decomposes via disproportionation a and formation of the halogen-free Tl [III] compound [{(η5-Cp)Ni(PEt3)}3Tl] (6). 2 can be dehalogenated with activated magnesium to yield the halogen-free In [III] compund [{(η5-Cp}Ni(PEt3)}3In] (4). The Ga analogue of 4 and 6 [{(η5-Cp)Ni(PEt3)}3Ga] (7) is accessible by a conproportionation of 1 with Ga metal in refluxing THF. In contrast to InCl and TlCl the aluminium (III) monochloride [{CH(SiMe3)2}2AlCl] reacts with 1 by a ligand redistribution reaction and formation of the salt [{(η5-Cp)Ni(PEt3)2]+-[{CH(SiMe3)2]2AlCl]2-. (8). Elemental Hg or Mg amalgam show the same activity as elemental Ga towards 1 and insert into the Ni—Ni bond by forming the linear Hg-bridged complex [(n3-Cp)Ni(PEt3)]2Hg] (9). The molecular structures of 2, 4, 8, and 9 were determined by X-ray crystallography. The In atom in 4 has a distorted trigonal-planar configuration with the central In atom being surrounded by three [(n5-Cp)Ni(PEt3)] fragments. 4 represents the first Ni-In cluster containing exclusively unsupported In - Ni bonds, as well as the first carbonyl-free Ni - In cluster. On the basis of spectroscopic data the same structure is assigned to the Ga and Tl analogues of 4. The Ni—Hg—Ni arrangement in 9 is exactly linear, as determined by X-ray crystallography.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301013
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  • 10
    Electronic Resource
    Electronic Resource
    Wissenschaft Aktuell (1998)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 32 (1998), S. 83-106 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19980320207
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