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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis, Structure and Reactivity of [(acac)AuCH(PPh2AuPPh2)2CHAu(acac)], a Complex Containing the Tridentate Ligand [HC(PPh2)2]- (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 121-124 
    Details
    ISSN: 0009-2940
    Keywords: Gold complexes ; Acetylacetonate ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complex [(acac)AuCH(PPh2AuPPh2)2CHAu(acac)] (1) is obtained by various procedures: a) by reaction of [Ph3PAuCH (PPh2AuPPh2)2CHAuPPh3](ClO4) 2 with NBu4[Au(acac)Cl], b) by reaction of [ClAuCH(PPh2AuPPh2)2CHAuCl] with [Au(acac)PPh3] or with Tl(acac) and c) by reaction of [ClAuPPh2CH2PPh2AuCl] with Tl(acac). The acetylacetonato ligand can act as deprotonating agent; thus, complex 1 reacts with (phosphane)gold complexes, [Au(C6F5)2{(PPh2)2-CH2)]ClO4, [Au(C6F5)3(PPh2CH2PPh2)] or [Au(PPh3)2]ClO4, to give the hexanuclear complexes [(C6F5)2Au{(PPh2)2CH} AuCH(PPh2AuPPh2)2CHAu{CH(PPh2)2) Au(C6F5)2](ClO4)2, [(C6F5)3Au(PPh2CHPPh2)AuCH (PPh2AuPPh2)2CHAu-(PPh2CHPPh2)Au(C6F5)3] or [(Ph3PAu)2C(PPh2AuPPh2)2C-(AuPPh3)2](ClO4)2, respectively. The crystal structure of 1 has been established by X-ray crystallography and displays two independent eight-membered rings with inversion symmetry and short transannular gold-gold contacts. The first ab initio results for a transannular AuI-AuI interaction are reported.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951280206
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  • 2
    Electronic Resource
    Electronic Resource
    General purpose heuristics for integer programming—Part I (1997)
    Springer
    Journal of heuristics 2 (1997), S. 343-358 
    Details
    ISSN: 1572-9397
    Keywords: integer programming ; branch and cut ; cut search ; ray probing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In spite of the many special purpose heuristics for specific classes of integer programming (IP) problems, there are few developments that focus on general purpose integer programming heuristics. This stems partly from the perception that general purpose methods are likely to be less effective than specialized procedures for specific problems, and partly from the perception that there is no unifying theoretical basis for creating general purpose heuristics. Still, there is a general acknowledgment that methods which are not limited to solving IP problems on a “class by class” basis, but which apply to a broader range of problems, have significant value. We show that certain ideas proposed in the 1970s, which are often overlooked, can be reformulated and linked with more recent developments to give a useful theoretical framework for generating general purpose IP heuristics. This framework, which has the appeal of being highly visual, makes use of cutting plane derivations that also give a natural basis for marrying heuristics with exact branch and cut methods for integer programming problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00132504
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  • 3
    Electronic Resource
    Electronic Resource
    General Purpose Heuristics for Integer Programming—Part II (1997)
    Springer
    Journal of heuristics 3 (1997), S. 161-179 
    Details
    ISSN: 1572-9397
    Keywords: integer programming ; branch and cut ; star-paths ; scatter search
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In spite of the many special purpose heuristics for specific classes of integer programming (IP) problems, there are few developments that focus on general purpose integer programming heuristics. This stems partly from the perception that general purpose methods are likely to be less effective than specialized procedures for specific problems, and partly from the perception that there is no unifying theoretical basis for creating general purpose heuristics. Still, there is a general acknowledgment that methods which are not limited to solving IP problems on a “class by class” basis, but which apply to a broader range of problems, have significant value. We provide a theoretical framework and associated explicit proposals for generating general purpose IP heuristics. Our development, makes use of cutting plane derivations that also give a natural basis for marrying heuristics with exact branch and cut methods for integer programming problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009631530787
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  • 4
    Electronic Resource
    Electronic Resource
    Coordination Compounds of Coinage Metals with Vinylidenebis(diphenyl-phosphane) and Its Disulfide and Their Reactivity towards NucleophilesDedicated to Professor P. Royo on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1513-1517 
    Details
    ISSN: 0009-2940
    Keywords: Gold ; Silver ; Diphosphane ; Diphosphane Disulfide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vinylidenebis(diphenylphosphane) reacts with gold(I) or gold(III) compounds to give dinuclear {[{Au(C6F5)]2[(PPh2)2C=CH2{] or [Au{PPh2C(=CH2)Ph2P)]2(ClO4)2] or mononuclear complexes ([Au(C6F5)3(PPh2C(=CH2)Ph2P)]}, respectively. The latter reacts with gold(I) or silver(I) compounds to afford dinuclear [[Au(C6F5)3[PPh2C(=CH2)Ph2P}AuX], X=Cl or C6F5) or trinuclear species {[{Au(C6F5)3{PPh2C(=CH2)Ph2P{]2M]ClO4, M=Au or Ag}. No addition of nucleophiles to the C=C double bond is observed in these complexes, which contain the diphosphane acting as bridging or monodentate ligand. (SPPh2)2C=CH2 reacts with AgClO4 to give [Ag{SPPh2C(=CH2)Ph2PS}]2-(ClO4)2or[Ag[PPh2C(=CH2)Ph2P]2]ClO4. The crystal structure of [Au(C6F5)3{PPh2C(=CH2)Ph2P}Au(C6F5)] has been established by X-ray crystallography, and confirms the expected square planar and linear geometry for the Au111 and Au1 centres, respectively.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301026
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis of Silver(I) Complexes with the Bis(diphenylphosphanyl)-o-carborane Ligand. Crystal Structure of [Ag(phen){(PPh2)2C2B10H10}]ClO4 and [Ag{(SPPh2)2CH2}{(PPh2)2C2B10H10}]ClO4 · CH2Cl2 (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 835-840 
    Details
    ISSN: 0009-2940
    Keywords: Silver(I) complexes ; Bis(diphenylphosphanyl)-o-carborane ; o-Carborane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Silver(I) perchlorate or nitrate react readily with bis(di-phenylphosphanyl)-o-carborane to give the complexes [AgX{(PPh2)2C2B10H10}] [X = ClO4 (1), NO3, (2)]. The perchlorate ligand is weakly bound to the silver atom and thus can be displaced by other ligands affording the three-coordinated complexes [AgL{(PPh2)2C2B10H10}]ClO4 [L = PPh3 (3), PPh2Me (4), AsPh3 (5), C5H4NCOOH (6), C9H6NCOOH (7), SPPh3 (8)]. Compounds 3 and 4 can also be obtained by reaction of [Ag(OClO3)PR3] with the diphosphane. Treatment of complex 1 with bidentate ligands leads to the cationic four-coordinated [Ag(L—L){(PPh2)2C2B10H10}]ClO4 [L—L = (PPh2)2C2B10H10 (9), bipy (10), phen (11), (SPPh2)2CH2 (12)] or to the neutral [Ag(S2CNR2){(PPh2)2C2B10H10}] [NR2 = NEt2 (13), NC4H8 (14)]. The crystal structures of 11 and 12 have been established by X-ray crystallography. In both complexes the silver(I) atoms exhibit tetrahedral coordination by two phosphorus and two nitrogen or two sulfur atoms, respectively.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270508
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  • 6
    Electronic Resource
    Electronic Resource
    Gold(I) and Silver(I) Complexes with Methanide Ligands [C{PPh2(X)}3]- (X = O, S). Crystal Structures of [M{C(PPh2(X))3}(PPh3)] (M — Au, X — O; M — Ag, X — S) (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 585-588 
    Details
    ISSN: 0009-2940
    Keywords: Gold complexes ; Silver complexes ; Triphosphane derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal complexes (M(acac)(PPh3)] act as deprotonating agents in the reaction with equimolar amounts of [CH{PPh2(X)}3)] to give the neutral complexes [M{C(PPh2(X))3}(PPh3)] [M = Ag, X = O (1) or S (2); M = Au; X = O (3) or S (4)]. The crystal structures of 2 and 3 have been established by X-ray crystallography. In the structure of 2 (two independent molecules) the silver(I) atoms display a distorted tetrahedral coordination by phosphorus (of PPh3) and three sulfur atoms. In complex 3 the gold(I) atom exhibits linear coordination by phosphorus of PPh3 and the carbon atom of [C{PPh2 (O)}3]-. The reaction of [CH{PPh2(X)}3] with [Ag(CF3SO3)] or [Ag(CF3SO3)(PPh3)] (molar ratio 1:1) leads to [Ag(CF3SO3){CH(PPh2(X))3}] [X = O (5), S (6)] or [Ag(CH(PPh2 (S))3}(PPh3)](CF3SO3) (7), respectively.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290518
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