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  1. Article: Computational support for tunneling in thermal[1,7]-hydrogen shift reactions.

    Hess, B A

    The Journal of organic chemistry

    2001  Volume 66, Issue 17, Page(s) 5897–5900

    Abstract: Density functional calculations have been performed for the [1,7]-hydrogen shift in two substituted 1,3,5-heptatrienes (1 and 9) for which kinetic data are available from the literature, including the observed kinetic isotope effects. For both cases the ... ...

    Abstract Density functional calculations have been performed for the [1,7]-hydrogen shift in two substituted 1,3,5-heptatrienes (1 and 9) for which kinetic data are available from the literature, including the observed kinetic isotope effects. For both cases the computed kinetic isotope effect was significantly smaller than that observed. These results provide further support for the presence of tunneling in thermal, antarafacial [1,7]-hydrogen shift reactions.
    Language English
    Publishing date 2001-08-24
    Publishing country United States
    Document type Journal Article
    ZDB-ID 123490-0
    ISSN 1520-6904 ; 0022-3263
    ISSN (online) 1520-6904
    ISSN 0022-3263
    DOI 10.1021/jo010622i
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Book: Relativistic effects in heavy-element chemistry

    Hess, B. A

    (Berichte der Bunsen-Gesellschaft ; 101.1997,1)

    1997  

    Author's details B.a. Hess
    Series title Berichte der Bunsen-Gesellschaft ; 101.1997,1
    Size S. 1 - 11
    Publisher Wiley-VCH
    Publishing place Weinheim u.a.
    Document type Book
    Database Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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  3. Article: Dewar resonance energy.

    Schaad, L J / Hess, B A

    Chemical reviews

    2001  Volume 101, Issue 5, Page(s) 1465–1476

    Language English
    Publishing date 2001-05
    Publishing country United States
    Document type Journal Article
    ZDB-ID 207949-5
    ISSN 1520-6890 ; 0009-2665
    ISSN (online) 1520-6890
    ISSN 0009-2665
    DOI 10.1021/cr9903609
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Bonn / Germany

    Z 4' 49/78: Show issues
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  4. Article: Synthesis, reactivity, and structure of strictly homologous 18 and 19 valence electron iron nitrosyl complexes.

    Sellmann, D / Blum, N / Heinemann, F W / Hess, B A

    Chemistry (Weinheim an der Bergstrasse, Germany)

    2001  Volume 7, Issue 9, Page(s) 1874–1880

    Abstract: The 18 and 19 valence electron (VE) nitrosyl complexes [Fe(NO)('pyS4')]BF4 ([1]BF4) and [Fe(NO)('pyS4')] (2) have been synthesized from [Fe('pyS4')]x ('pyS4'(2-) = 2,6-bis(2-mercaptophenylthiomethyl)pyridine(2-)) and either NOBF4 or NO gas. Complex [1] ... ...

    Abstract The 18 and 19 valence electron (VE) nitrosyl complexes [Fe(NO)('pyS4')]BF4 ([1]BF4) and [Fe(NO)('pyS4')] (2) have been synthesized from [Fe('pyS4')]x ('pyS4'(2-) = 2,6-bis(2-mercaptophenylthiomethyl)pyridine(2-)) and either NOBF4 or NO gas. Complex [1]BF4 was also obtained from [Fe(CO)('pyS4')] and NOBF4. The cation [1]+ is reversibly reduced to give 2. Oxidation of 2 by [Cp2Fe]PF6 afforded [Fe(NO)('pyS4')]PF6 ([1]PF6). The molecular structures of [1]PF6 and 2 were determined by X-ray crystallography. They demonstrate that addition of one electron to [1]+ causes a significant elongation of the Fe-donor atom bonds and a bending of the FeNO angle. Density functional calculations show that the unpaired electron in 2 occupies an orbital, which is antibonding with respect to all Fe-ligand interactions. As expected from qualitative Molecular Orbital (MO) theory, it has a large contribution from a pi* type NO orbital. The nu(NO) frequency decreases from 1893 cm(-1) in [1]BF4 to 1648 cm(-1) in 2 (in KBr). The antibonding character of the unpaired electron explains the ready reaction of 2 with excess NO to give [Fe(NO)2('pyS4')] (3), the facile NO/CO exchange of 2 to afford [Fe(CO)('pyS4')], and the easy oxidation of 2 to [1]+.
    Language English
    Publishing date 2001-05-04
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1478547-X
    ISSN 1521-3765 ; 0947-6539
    ISSN (online) 1521-3765
    ISSN 0947-6539
    DOI 10.1002/1521-3765(20010504)7:9<1874::aid-chem1874>3.0.co;2-2
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  5. Article: Dinuclear diazene iron and ruthenium complexes as models for studying nitrogenase activity.

    Reiher, M / Salomon, O / Sellmann, D / Hess, B A

    Chemistry (Weinheim an der Bergstrasse, Germany)

    2001  Volume 7, Issue 23, Page(s) 5195–5202

    Abstract: The strength of hydrogen bonds has been investigated in various dinuclear diazene FeII, FeIII, and RuII complexes by use of the recently developed shared-electron number approach. Hydrogen bonding in these compounds plays an essential role in view of ... ...

    Abstract The strength of hydrogen bonds has been investigated in various dinuclear diazene FeII, FeIII, and RuII complexes by use of the recently developed shared-electron number approach. Hydrogen bonding in these compounds plays an essential role in view of designing a model system for nitrogenase activity. The general conclusions for iron-sulfur complexes are: hydrogen bonds can stabilize diazene by at least 20% of the total coordination energy; the strength of the hydrogen bonds can be directly controlled through the hydrogen-sulfur bond length; reducing FeIII centers to FeII can double the hydrogen bond energy.
    MeSH term(s) Hydrogen Bonding ; Imides/chemistry ; Iron ; Models, Molecular ; Molecular Structure ; Nitrogenase/chemistry ; Organometallic Compounds/chemistry ; Ruthenium ; Thermodynamics
    Chemical Substances Imides ; Organometallic Compounds ; Ruthenium (7UI0TKC3U5) ; Iron (E1UOL152H7) ; Nitrogenase (EC 1.18.6.1) ; diazene (LM321PYV3Y)
    Language English
    Publishing date 2001-12-03
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1478547-X
    ISSN 1521-3765 ; 0947-6539
    ISSN (online) 1521-3765
    ISSN 0947-6539
    DOI 10.1002/1521-3765(20011203)7:23<5195::aid-chem5195>3.0.co;2-3
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  6. Book: A functional representation of correlations in inhomogeneous many-electron systems

    Dietz, K / Hess, B. A

    (Physikalisches Institut, Universität Bonn. Bonn-AM ; 89-05)

    1989  

    Institution Physikalisches Institut, Universität Bonn
    Author's details K. Dietz; B. A. Hess. Physikalisches Institut, Universität Bonn
    Series title Physikalisches Institut, Universität Bonn. Bonn-AM ; 89-05
    Language English
    Size 22 S
    Publishing place Bonn
    Document type Book
    Database Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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  7. Article: [Ru(HNO)('py(bu)S4')], the first HNO complex resulting from hydride addition to a NO complex ('pybuS4'2-=2,6-Bis(2-mercapto-3,5-di-tert-butylphenylthio)dime thylpyridine(2-1)).

    Sellmann, D / Gottschalk-Gaudig, T / Häussinger, D / Heinemann, F W / Hess, B A

    Chemistry (Weinheim an der Bergstrasse, Germany)

    2001  Volume 7, Issue 10, Page(s) 2099–2103

    Abstract: Treatment of the nitrosyl complex [Ru(NO)('pybuS4')]Br (1a) with NaBH4 in CH3OH yielded [Ru(HNO)('pybuS4')](2), which could be completely characterized. The X-ray structure determination of 2 confirmed the N coordination of the HNO ligand. Density ... ...

    Abstract Treatment of the nitrosyl complex [Ru(NO)('pybuS4')]Br (1a) with NaBH4 in CH3OH yielded [Ru(HNO)('pybuS4')](2), which could be completely characterized. The X-ray structure determination of 2 confirmed the N coordination of the HNO ligand. Density functional theory calculations enabled us to assign the nu(NO) IR band of 2, which appears in KBr at 1358cm(-1) and in THF at 1378 cm(-1). The unprecedented hydride addition to nitrosyl complexes yielding HNO complexes fills a white spot on the map of chemical reactions, represents the as yet unknown counterpart to the well-established formyl complex formation from CO complexes and hydrides, and distinctly differs from the formation reaction of [Os(HNO)(CO)Cl2(PPh3)2], the only other HNO complex characterized structurally. The HNO complex 2 is oxidized stepwise by [Cp2Fe]PF6 in the presence of NEt3 and directly by Bronsted acids to give [Ru(NO)('pybuS4')]+ in 2e- oxidations. H+/D+ exchange indicates acidity of the HNO proton.
    Language English
    Publishing date 2001-05-18
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1478547-X
    ISSN 1521-3765 ; 0947-6539
    ISSN (online) 1521-3765
    ISSN 0947-6539
    DOI 10.1002/1521-3765(20010518)7:10<2099::aid-chem2099>3.0.co;2-a
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  8. Article: A hospital based emergency helicopter service.

    Jablonowski, A J / Hess, B A

    IMJ. Illinois medical journal

    1982  Volume 162, Issue 3, Page(s) 179–182

    MeSH term(s) Aircraft ; Emergency Service, Hospital ; Humans ; Illinois ; Transportation of Patients
    Language English
    Publishing date 1982-09
    Publishing country United States
    Document type Journal Article
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  9. Article: Binding H2, N2, H-, and BH3 to transition-metal sulfur sites: synthesis and properties of [RuL(PR3)(N2Me2S2)] Complexes (L=eta2-H2, H-, BH3; R=Cy, iPr).

    Sellmann, D / Hille, A / Heinemann, F W / Moll, M / Reiher, M / Hess, B A / Bauer, W

    Chemistry (Weinheim an der Bergstrasse, Germany)

    2004  Volume 10, Issue 17, Page(s) 4214–4224

    Abstract: The reactions of [Ru(N(2))(PR(3))('N(2)Me(2)S(2)')] ['N(2)Me(2)S(2)'=1,2-ethanediamine-N,N'-dimethyl-N,N'-bis(2-benzenethiolate)(2-)] [1 a (R=iPr), 1 b (R=Cy)] and [micro-N(2)[Ru(N(2))(PiPr(3))('N(2)Me(2)S(2)')](2)] (1 c) with H(2), NaBH(4), and NBu(4)BH( ...

    Abstract The reactions of [Ru(N(2))(PR(3))('N(2)Me(2)S(2)')] ['N(2)Me(2)S(2)'=1,2-ethanediamine-N,N'-dimethyl-N,N'-bis(2-benzenethiolate)(2-)] [1 a (R=iPr), 1 b (R=Cy)] and [micro-N(2)[Ru(N(2))(PiPr(3))('N(2)Me(2)S(2)')](2)] (1 c) with H(2), NaBH(4), and NBu(4)BH(4), intended to reduce the N(2) ligands, led to substitution of N(2) and formation of the new complexes [Ru(H(2))(PR(3))('N(2)Me(2)S(2)')] [2 a (R=iPr), 2 b (R=Cy)], [Ru(BH(3))(PR(3))('N(2)Me(2)S(2)')] [3 a (R=iPr), 3 b (R=Cy)], and [Ru(H)(PR(3))('N(2)Me(2)S(2)')](-) [4 a (R=iPr), 4 b (R=Cy)]. The BH(3) and hydride complexes 3 a, 3 b, 4 a, and 4 b were obtained subsequently by rational synthesis from 1 a or 1 b and BH(3).THF or LiBEt(3)H. The primary step in all reactions probably is the dissociation of N(2) from the N(2) complexes to give coordinatively unsaturated [Ru(PR(3))('N(2)Me(2)S(2)')] fragments that add H(2), BH(4) (-), BH(3), or H(-). All complexes were completely characterized by elemental analysis and common spectroscopic methods. The molecular structures of [Ru(H(2))(PR(3))('N(2)Me(2)S(2)')] [2 a (R=iPr), 2 b (R=Cy)], [Ru(BH(3))(PiPr(3))('N(2)Me(2)S(2)')] (3 a), [Li(THF)(2)][Ru(H)(PiPr(3))('N(2)Me(2)S(2)')] ([Li(THF)(2)]-4 a), and NBu(4)[Ru(H)(PCy(3))('N(2)Me(2)S(2)')] (NBu(4)-4 b) were determined by X-ray crystal structure analysis. Measurements of the NMR relaxation time T(1) corroborated the eta(2) bonding mode of the H(2) ligands in 2 a (T(1)=35 ms) and 2 b (T(1)=21 ms). The H,D coupling constants of the analogous HD complexes HD-2 a ((1)J(H,D)=26.0 Hz) and HD-2 b ((1)J(H,D)=25.9 Hz) enabled calculation of the H--D distances, which agreed with the values found by X-ray crystal structure analysis (2 a: 92 pm (X-ray) versus 98 pm (calculated), 2 b: 99 versus 98 pm). The BH(3) entities in 3 a and 3 b bind to one thiolate donor of the [Ru(PR(3))('N(2)Me(2)S(2)')] fragment and through a B-H-Ru bond to the Ru center. The hydride complex anions 4 a and 4 b are extremely Brønsted basic and are instantaneously protonated to give the eta(2)-H(2) complexes 2 a and 2 b.
    Language English
    Publishing date 2004-09-06
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1478547-x
    ISSN 1521-3765 ; 0947-6539
    ISSN (online) 1521-3765
    ISSN 0947-6539
    DOI 10.1002/chem.200400120
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  10. Article: Theory of linear equations as applied to quantitative structure-activity correlations.

    Schaad, L J / Hess, B A

    Journal of medicinal chemistry

    1977  Volume 20, Issue 5, Page(s) 619–625

    MeSH term(s) Kinetics ; Mathematics ; Structure-Activity Relationship
    Language English
    Publishing date 1977-05
    Publishing country United States
    Document type Journal Article
    ZDB-ID 218133-2
    ISSN 1520-4804 ; 0022-2623
    ISSN (online) 1520-4804
    ISSN 0022-2623
    DOI 10.1021/jm00215a001
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    In stock of ZB MED Cologne/Königswinter

    Zs.B 151: Show issues Location:
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    Zs.MB 1: Show issues

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