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  • 1980-1984  (21)
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  • 1
    Keywords: Hochschulschrift
    Type of Medium: Online Resource
    Pages: Online-Ressource (132 Seiten = 6 MB) , Illustration, Diagramm, Karte
    Language: German
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  • 2
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Kinetic and Mechanistic Investigations of Transition Metal Complex Reactions, IV. Reactions of Complex Ligands, XVIII. Kinetic and Mechanism of the Insertion of 1-(Diethylamino)-1-propyne into the Metal-Carbene Bond of Pentacarbonyl(arylmethoxycarbene)chromium(0) and -tungsten(0)Pentacarbonyl(arylmethoxycarbene) complexes (CO)5M[C(p-C6H4R)OCH3] (M = Cr, W; R = CF3, Br, H, CH3, OCH3) (1a - g) add 1-(diethylamino)-1-propyne (2) via insertion of the alkyne into the metal-carbene bond. The formation of pentacarbonyl[(diethylamino)(2-aryl-2-methoxy-1-methylethenyl)carbene]chromium(0) and -tungsten(0) (3a - g) in octane follows a second-order rate law: d[3]/dt = k[1][2]. The tungsten complexes react faster than the analogous chromium compounds. Replacement of R = H by electron withdrawing substituents (CF3, Br) results in an increase, by electron donating groups (CH3, OCH3) in a decrease of the reaction rate. The activation enthalpies ΔH≠ are low (25.1 - 39.4 kJ · mol-1), the activation entropies ΔS≠ strongly negative (-129 to -145 J · mol- K-1). The results are discussed on the basis of an associative stepwise mechanism with an attack of the ynamine at the carbene carbon in the first reaction step.
    Notes: Pentacarbonyl(arylmethoxycarben)-Komplexe (CO)5M[C(p-C6H4R)OCH3] (M = Cr, W; R = CF3, Br, H, CH3, OCH3) (1a - g) addieren 1-(Diethylamino)-1-propin (2) unter Einschiebung des Alkins in die Metall-Carbenkohlenstoff-Bindung. Die Bildung von Pentacarbonyl[(diethylamino)(2-aryl-2-methoxy-1-methylethenyl)carben]chrom(0) und -wolfram(0) (3a - g) in Octan erfolgt nach einem Geschwindigkeitsgesetz zweiter Ordnung: d[3]/dt = k[1][2]. Die Wolframkomplexe reagieren schneller als die entsprechenden Chromverbindungen. Ersatz von R = H durch elektronenziehende Substituenten (Br, CF3) führt zu einer Erhöhung, durch elektronenspendende Gruppen (CH3, OCH3) zu einer Verringerung der Reaktionsgeschwindigkeit. Die Aktivierungsenthalpien ΔH≠ sind niedrig (25.1 - 39.4 kJ · mol-1), die Aktivierungsentropien ΔS≠ stark negativ (-129 bis -145 Jmol-1 K-1). Die Ergebnisse werden auf der Grundlage eines mehrstufigen Mechanismus mit einem Angriff des Inamins am Carbenkohlenstoff im ersten Reaktionsschritt diskutiert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Kinetic and Mechanistic Investigations of Transition Metal Complex Reactions, XI. Reactions of Complex Ligands, XXII. Kinetic and Mechanism of the Formation of Tricarbonyl(naphthol)chromium Complexes from Pentacarbonyl[(methoxy)(phenyl)carbene]chromium(0) and AlkynesPentacarbonyl[(methoxy)(phenyl)carbene]chromium(0), (CO)5Cr[C(Ph)OMe] (1), reacts with arylalkynes p-R1C6H4—C≡C—R2 (R1 = H, Me; R2 = Ph, 4-C6H4CF3, Me) (2a-e) with elimination of CO to give substituted tricarbonyl(1-naphthol)chromium complexes (3a-e, 4a-d) in dibutyl ether by the following rate law: -d[1]/dt = {k1k2[2]/(k-1[CO] + k2[2])} [1]. The activation parameters for the CO-elimination reaction are: ΔH± = 108 ± 2 kJ mol-1, ΔS± = 26 ± 6 J mol-1 K-1. The reaction rate increases with increasing electron density within the triple bond of 2a-e. The results are discussed on the basis of a dissociative mechanism.
    Notes: Pentacarbonyl[(methoxy)(phenyl)carben]chrom(0), (CO)5Cr[C(Ph)OMe] (1), reagiert mit den Arylalkinen p-R1C6H4—C≡C—R2 (R1 = H, Me; R2 = Ph, 4-C6H4CF3, Me) (2a-e) unter CO-Abspaltung zu substituierten Tricarbonyl(1-naphthol)chrom-Komplexen (3a-e, 4a-d) in Dibutylether nach folgendem Geschwindigkeitsgesetz: —d[1]/dt = {k1k2[2]/(k-1[CO] + k2[2])}[1]. Die Aktivierungsparameter für die CO-Abspaltung sind: ΔH± = 108 ± 2 kJ mol-1, ΔS± = 26 ± 6 J mol-1 K-1. Mit steigender Elektronendichte in der Dreifachbindung von 2a-e nimmt die Geschwindigkeit der Umsetzung zu. Die Ergebnisse werden auf der Grundlage eines dissoziativen Mechanismus diskutiert.
    Additional Material: 1 Ill.
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  • 4
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Kinetic and Mechanistic Investigations of Transition Metal Complex Reactions, XV1). Transition Metal Sulfur Ylide Complexes, XX2). Kinetic Evidence of [(CO)5Cr=CH2] in the Reaction of Pentacarbonyl[(dimethyloxosulfonio)-methanide]chromium(0) with Tertiary PhosphanesPentacarbonyl[(dimethyloxosulfonio)methanide]chromium(0), (CO)5Cr[CH2S(O)Me2] (1), reacts with tertiary phosphanes PR3 (2) (R = Ph, C6H4OMe-(p), C6H4Me-(p), C6H4Cl-(p)) to give pentacarbonyl(phosphonium ylide)chromium(0) complexes, (CO)5Cr[CH2PR3] (3), and dimethyl sulfoxide according to the first-order rate law. The reaction rate is independent on the type of the phosphane. The activation parameters for the reaction in 1,1,2-trichloroethane in the temperature range 39.6 to 68.0°C are ΔH≠ = 28.1 kcal · mol-1 and ΔS≠ = 12.7 cal · mol-1 · K-1. The reaction is initiated by irreversible dissociation of OSMe2 from 1. Addition of 2 to the carbene carbon of the resulting pentacarbonylmethylenechromium, [(CO)5Cr=CH2], yields 3 in a fast succeeding step. A mechanism involving rate determining dissociation of the Cr=CH2 bond can be excluded. These results represent the first evidence of a neutral, electrophilic carbonylmethylene complex.
    Notes: Pentacarbonyl[(dimethyloxosulfonio)methanid]chrom(0), (CO)5Cr[CH2S(O)Me2] (1), reagiert mit tertiären Phosphanen PR3 (2) (R = Ph, C6H4OMe-(p), C6H4Me-(p), C6H4Cl-(p)) nach dem Geschwindigkeitsgesetz erster Ordnung zu Pentacarbonyl(phosphorylid)chrom(0)-Komplexen, (CO)5Cr[CH2PR3] (3), und Dimethylsulfoxid. Die Reaktionsgeschwindigkeit ist von der Art des Phosphans unabhängig. Die Aktivierungsparameter für die Reaktion in 1,1,2-Trichlorethan im Temperaturbereich von 39.6-68.0°C sind ΔH≠ = 28.1 kcal · mol-1 und ΔS≠ = 12.7 cal · mol-1. K-1. Die Reaktion wird durch irreversible Dissoziation von OSMe2 vom Komplex 1 eingeleitet. An das Carbenkohlenstoffatom des resultierenden Pentacarbonylmethylenchroms, [(CO)5Cr=CH2], addiert sich dann 2 in einem raschen Folgeschritt unter Bildung von 3. Ein Mechanismus über einen geschwindigkeitsbestimmenden Cr-CH2-Bindungsbruch kann ausgeschlossen werden. Diese Ergebnisse sind der erste Nachweis eines neutralen elektrophilen Carbonylmethylen-Komplexes.
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  • 5
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Carbene Complexes, CXXVII. Kinetic and Mechanistic Investigations of Transition Metal Complex Reactions, XI11 2. Diethylamino(phenyltel1uro)carbene- and Diethylaminocarbyne(phenyltelluro) Complexes of Chromium: Preparative Investigations and Kinetics of the C, Cr-Migration of PhTePentacarbonyl(diethylaminocarbyne)chromium tetrafluoroborate, [(CO)5CrCNEt2]BF4 (1), reacts with lithium tellurophenolate, Li[TePh], with addition of the tellurophenolate anion to the carbyne carbon atom to give pentacarbonyl[diethylamino(phenyltelluro)carbene]chromium, (CO)5Cr[C(TePh)NEt2] (2). On heating in solution, the complex 2 rearranges with CO-elimination and C, Cr-migration of TePh to give trans-tetracarbonyl(diethylaminocarbyne)(phenyltelluro)chromium, trans-(PhTe)(CO)4CrCNEt2 (3). The rearrangement follows a first order rate law (-d[2]/dt = k[2]; ΔH≠ = 108 ± 1 kJmol-1; ΔS≠ = 42 ± 4 Jmol-1K-1; in 1,1,2-trichloroethane). In solution, 3 dimerizes with CO-elimination to give bis(μ-phenyltelluro)-bis[tricarbonyl(diethylaminocarbyne)chromium], (μ-PhTe)2[(CO)3CrCNEt2]2 (4). Addition of PPh3 to solutions of 2 does not influence the rate of the rearrangement but leads to a different product, mer-(PhTe)(CO)3(PPh3)CrCNEt2 (5).
    Notes: Pentacarbonyl(diethylaminocarbin)chrom-tetrafluoroborat, [(CO)5CrCNEt2]BF4 (1), reagiert mit Lithium-tellurophenolat, Li[TePh], unter Addition des Tellurophenolat-Anions an das Carbin-kohlenstoffatom und Bildung von Pentacarbonyl[diethylamino(phenyltelluro)carben]chrom, (CO)5Cr[C(TePh)NEt2] (2). Beim Erwärmen in Lösung lagert sich der Komplex 2 unter CO-Abspaltung und C, Cr-Wanderung von TePh nach einem Geschwindigkeitsgesetz erster Ordnung (-d[2]/dt = k[2]; ΔH≠ = 108 ± 1 kJmol-1; ΔS≠ = Jmol-1K-1; in 1,1,2-Trichlorethan) zu trans-Tetracarbonyl(diethylaminocarbin)(phenyltelluro)chrom, trans-(PhTe)(CO)4-CrCNEt2 (3), um. In Lösung dimerisiert 3 unter CO-Eliminierung zu Bis(μ-phenyltelluro)-bis[tricarbonyl(diethylaminocarbin)chrom], (μ-PhTe)2[(CO)3CrCNEt2]2 (4). Zusatz von PPh3 zu Lösungen von 2 beeinflußt zwar die Umlagerungsgeschwindigkeit nicht, liefert jedoch als Reaktionsprodukt mer-(PhTe)(CO)3(PPh3)CrCNEt2 (5).
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 1349-1354 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Thioketone Complexes via Insertion of Sulfur from Organyl Isothiocyanates into the Metal-Carbene Bond(Arylphenylcarbene)pentacarbonyltungsten complexes, (CO)5W[C(p-C6H4R)(C6H5)] (1) [R = H (a), OMe (b), Me (c), Br (d), CF3 (e)], react with organyl isothiocyanates, R′—N=C=S (2) [R = Me (a), Et (b), Ph (3c)], inserting sulfur from 2 into the metal-carbene bond to give (arylphenyl thioketone)pentacarbonyltungsten complexes, (CO)5W[S=C(p-C6H4R)(C6H5)] (3). The compounds 3 were characterized by spectroscopic means.
    Notes: (Arylphenylcarben)pentacarbonylwolfram-Komplexe, (CO)5W[C(p-C6H4R)(C6H5)] (1) [R = H (a), OMe (b), Me (c), Br (d), CF3 (e)], reagieren mit Organyl-isothiocyanaten, R′—N=C=S (2) [R′ = Me (a), Et (b), Ph (c)], unter Insertion des Schwefels von 2 in die Metall-Carbenkohlenstoff-Bindung und Bildung von [(Aryl)(phenyl)thioketon]pentacarbonylwolfram-Komplexen, (CO)5W[S=C(p-C6H4R)(C6H5)] (3). Die Verbindungen 3 wurden mit Hilfe von spektroskopischen Methoden charakterisiert.
    Additional Material: 2 Tab.
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  • 7
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Carbene Complexes, CXXII. Kinetic and Mechanistic Investigations of Transition Metal Complex Reaction, XII. Pentacarbonyl[diethylamino(triphenylplumbyl)carbene]chromium and trans-Tetracarbonyl(diethylaminocarbyne)(triphenylplumbyl)chromium: Preparative Investigations and Kinetics of the C,Cr-Migration of PbPh3Pentacarbonyl(diethylaminocarbyne)chromium tetrafluoroborate, [(CO)5CrCNEt2]BF4 (2), reacts with lithium triphenylplumbate, LiPbPh3 (3), with addition of the plumbate anion to the carbyne carbon atom to give pentacarbonyl[diethylamino(triphenylplumbyl)carbene]chromium, (CO)5-Cr[C(PbPh3)NEt2] (4). Already at room temperature, the complex 4 rearranges with CO-elimination and C,Cr-migration of PbPh3 to give trans-tetracarbonyl(diethylaminocarbyne)(triphenylplumbyl)chromium, trans-(Ph3Pb)(CO)4CrNEt2 (5). The rearrangement follows a first-order rate law (ΔH≠ = 103 kJmol-1; ΔS≠ = 40 Jmol-1, K-1, in 1,1,2-trichloroethane). The compounds 4 und 5 were characterized by analytical and spectroscopic means.
    Notes: Pentacarbonyl(diethylaminocarbin)chrom-tetrafluoroborat, [(CO)5CrCNEt2]BF4 (2), reagiert mit Lithium-triphenylplumbat, LiPbPh3 (3), unter Addition des Plumbat-Anions an das Carbinkohlenstoffatom und Bildung von Pentacarbonyl[diethylamino(triphenylplumbyl)carben]chrom, (CO)5Cr[C(PbPh3)NEt2] (4). Bereits bei Raumtemperatur lagert sich der Komplex 4 unter CO-Abspaltung und C,Cr-Wanderung von PbPh3 nach einem Geschwindigkeitsgesetz erster Ordnung (ΔH≠ = 103 kJmol-1, ΔS≠ = 40 Jmol-1, K-1, in 1,1,2-Trichlorethan) zu trans-Tetracarbonyl-(diethylaminocarbin)(triphenylplumbyl)chrom, trans-(Ph3Pb)(CO)4CrCNEt2 (5), um. Die Verbindungen 4 und 5 wurden analytisch und spektroskopisch gesichert.
    Additional Material: 3 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3209-3219 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Carbene Complexes, CXVII1) [(Arylseleno)(diethylamino)carbene]pentacarbonylchromium(0)Pentacarbonyl(diethylaminocarbyne)chromium tetrafluoroborate, [CO)5CrCNEt2]BF4, (1) reacts with lithium arylselenolate, LiSeR, (3) [R = 4-C6H4CF3 (a), 4-C6H4Br (b) 4-C6H4F (c), C6H5 (d), 4-C6H4CH3 (e), 4-C6H4OCH3 (f), 1-C10H7 (g)] with addition of the selenolate anion to the carbyne carbon atom to give [(arylseleno)(diethylamino)carbene]pentacarbonylchromium(0), (CO)5Cr[C(SeR)NEt2], (4a - g). The complexes 4 were characterized by elemental analyses, spectroscopic data and in the case fo 4d additionally by an X-ray analysis. On heating in solution, 4a - g rearrange with CO-elimination and C,Cr-migration of SeR to the corresponding trans-(arylseleno)tetracarbonyl(diethylaminocarbyne)chromium complexes, trans-RSe(CO)4-CrCNEt2, (5a - g).
    Notes: Pentacarbonyl(diethylaminocarbin)chrom-tetrafluoroborat, [(CO)5CrCNEt2]BF4, (1) reagiert mit Lithium -arylselenolat, LiSeR, (3) [R = 4-C6H4CF3 (a), 4-C6H4Br (b) 4-C6H4 (c), C6H5 (d), 4-C6H4CH3 (e), 4-C6H4OCH3 (f), 1-C10H7 (g)] unter Addition des Selenolat-Anions an das Carbinkohlenstoffatom und Bildung von [Arylseleno)(diethylamino)carben]pentacarbonylchrom(0), (CO)5Cr[C(SeR)NEt2], (4a-g). Die Komplexe 4 wurden elementaranalytisch, spektroskopisch sowie im Fall von 4d zusätzlich durch eine Röntgenstrukturanalyse gesichert. Beim Erwärmen in Lösung lagern sich 4a-g unter CO-Abspaltung und C, Cr-Wanderung von SeR zu den entsprechenden trans-(Arylseleno)tetracarbonyl(diethylaminocarbin)chrom-Komplexen, trans-RSe(CO)4(CrCNEt2, (5a-g) um.
    Additional Material: 1 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 17 (1983), S. A66 
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3349-3365 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Bonding Model of Transition Metal Aminocarbyne ComplexesBy comparison of the structures of [trans-PH3(CO)4CrCNEt2]BF4 (3), mer-Br(CO)4CrCNEt2 (4), and [(CO)5CrCNEt2]BF4 (5) with the known structures of trans-Br(CO)4CrCNEt2 (1) and trans-Ph3Sn(CO)4CrCNEt2 (2) the influence of the varying metal fragment on the bonding parameters of the carbyne ligand CNEt2 is investigated. Extended-Hückel-MO calculations on models and an analysis of fragment orbital interactions between the MLn system and the aminocarbyne ligand serve a discussion of the bonding. In each complex the amino group is in conjugation with the Cr-Ccarbyne bond. The extent of conjugation is influenced by the ligand trans to the carbyne group. For cis ligands additional influences are discussed.
    Notes: Durch Vergleich der Strukturen von [trans-Ph3P(CO)4CrCNEt2]BF4(3),mer-Br(PPh3)(CO)3CrCNEt2 (4) und [(CO)5CrCNEt2]BF4 (5) mit den bereits bekannten Strukturen von trans-Br(CO)4CrCNEt2 (1) und trans-Ph3Sn(CO)4CrCNEt2 (2) wird der Einfluß des variierenden Metallkomplex-Fragments auf die Bindungsparameter des Carbin-Liganden CNEt2 untersucht. Extended-Hückel-MO-Berechnungen an Modellen und die Analyse der Fragment-Orbital-Wechselwirkungen zwischen MLn-System und Aminocarbin-Ligand dienen zur Diskussion der Bindungsverhältnisse. In allen Komplexen ist die Aminogruppe mit der Cr-Ccarbin-Bindung konjugiert. Durch die Art des zum Carbin-Rest trans-ständigen Liganden wird das Ausmaß an Konjugation verändert. Für cis-ständige Liganden müssen auch noch andere Einflüsse diskutiert wurden.
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