| | 1 | Author
| AnthonyJ. Arduengo, JensR. Iiia, Fredric Goerlicha, WilliamJ. Davidsonb, Marshall5 | Requires cookie* | | | Title
| Carbene Adducts of Dimethylcadmium  | | | | Abstract
| The first examples of carbene-cadmium complexes are reported from the reactions of a variety of imidazol-2-ylidenes or imidazolin-2-ylidenes with dimethylcadmium. Four new carbene complexes are characterized by NMR spectroscopy ('H , i?C and 1 n Cd). The cadmium centers are strongly shifted downfield (100 -1 5 0 ppm) by interaction with the carbenes. X-ray structures are reported for three carbene-cadmium 1:1 adducts. The cadmium centers exhibit distorted trigonal-planar geometries in which the carbene ligands have an average 18.2 pm longer bond distance to cadmium compared to the methyl groups. The planes of cadmium coordination are twisted with respect to the plane of the imidazole ring. The more basic imidazolin-2-ylidene is shown to displace imidazol-2-ylidenes from the cadmium center. | | | |
Reference
| Z. Naturforsch. 54b, 1350—1356 (1999); received June 16 1999 | | | |
Published
| 1999 | | | |
Keywords
| Carbene, Cadmium, Ylide, Carbene Complex, Imidazol-2-ylidene | | | |
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| default:Reihe_B/54/ZNB-1999-54b-1350.pdf | | | | Identifier
| ZNB-1999-54b-1350 | | | | Volume
| 54 | |
| 2 | Author
| Wolfgang Malisch, Herbert Blau, Peter Weickert, Karl-Heinz Grießmann | Requires cookie* | | | Title
| Zur Reaktion von Metall-koordiniertem Kohlenmonoxid mit Yliden, X [1] /3-Phosphoniocarben-, ß-Phosphonio vinyl-und Phosphor-Ylid-Komplexe des Chroms und Cobalts aus Tetramethylphosphonium- [(trimethylphosphoranyliden)acetyl-metallaten] Reactions of Metal Coordinated Carbon Monoxide with Ylides, X [1] ^-Phosphoniocarbene, /9-Phosphoniovinyl and Phosphorus Ylide Complexes of Chromium and Cobalt Deriving from Tetramethylphosphonium [(trimethylphosphoranyliden)- acetyl-metallates] | | | | Abstract
| The reaction of Cp(CO)2(NO)Cr with Me3P = CH2 yields the tetramethylphosphonium -[(trimethylphosphoranyliden)acetyl-Chromate] Me4P[Cp (CO)(NO)Cr-C(O)-CH = PMe3] (1) via ylide addition at the carbonyl carbon and transylidation. A reversible equilibrium is established between 1 and the starting materials, which is responsible for the facile conversion of 1 into the ylide complex Cp(CO)(NO)Cr-CH2PMe3 (2) on photolysis. In the presence of Mel, 1 is degradated to [Me4P]I, [Me3PEt]I, [Me2PEt2]I and Cp(CO)2(NO)Cr. Treatment of 1 with an equimolar amount of Me0S02F leads to the formation of the "zwitterionic" phosphoniovinyl complexes Cp(CO)(NO)Cr-C(OMe) = CH-PMe3 (3a) and Cp(CO)(NO)Cr-C(OMe) = C(Me)-PMe3 (3b). With excess Me0S02F the phosphoniocarbene complex [Cp(C0)(N0)Cr = C(0Me)-CH(Me)-PMe3]S03F (4a) is obtained. Me3P = CH2 de-protonates 4a to 3b, which adds HCl to give [Cp(CO)(NO)Cr=C(OMe)-CH(Me)-PMe3]Cl (4b). The phosphonium cobaltacylates Me4P[(C0)(N0)(L)C0-C(0)-CH = PMe3] (5a, b), generated from the cobalt complex (CO)2(NO)(L)Co (L = CO, Me3P) and Me3P = CH2, readily transform to the ylide complexes (CO)(NO)(L)Co-CH2-PMe3 (6a, b). MeX (X = I, S03F) cleaves 6b to give (CO)2(NO)(Me3P)Co and [Me3PEt]X. The new complexes are characterized by elementary analysis and spectroscopy. | | | |
Reference
| Z. Naturforsch. 38b, 711—718 (1983); eingegangen am 18. Januar 1983 | | | |
Published
| 1983 | | | |
Keywords
| Carbonmonoxide Conversion, Vinyl Complexes, Carbene Complexes, Ambidentate Nucleophilic Reactivity | | | |
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| default:Reihe_B/38/ZNB-1983-38b-0711.pdf | | | | Identifier
| ZNB-1983-38b-0711 | | | | Volume
| 38 | |
| 3 | Author
| C. Krüger, R. Goddard, K. H. Claus | Requires cookie* | | | Title
| The Experimental Determination of the Electronic Deformation Densities in a Chromium Carbene and a Chromium Carbyne Complex | | | | Abstract
| The electronic deformation densities for pentacarbonylmethylethoxycarbenechromium I and chlorotetracarbonylethylidynechromium II have been experimentally determined using Neutron (for I) and X-ray diffracted intensities measured from single crystals at 100 K. A build up of electron density in all bonds and around each chromium atom is observed. Deformation density maxima are directed along the 3-fold axes of the approx-imately octahedrally coordinated metal atoms and presumably represent occupation of the t2g d-orbital set. The observed electron density distributions indicate that intermole-cular bonding has an important influence on the distribution of electron density in the molecules. Seit ihrer Entdeckung und strukturchemischen Beschreibung [1] stehen Übergangsmetallkomplexe mit Carben-und Carbin-Fragmenten im Blickfeld theoretischer Betrachtungen [2]. Ziel der vorliegen-den Arbeit war es, einen experimentellen Zugang zu den Bindungs Verhältnissen mit Hilfe neuer, hochauflösender Röntgen-(X-X)-[3] und Neu-tronenbeugungsmethoden (X-N) [4, 5] zu finden. Wir beschreiben im folgenden unsere Untersuchun-gen an Einkristallen des Chrom-Carben-Komplexes I sowie des Chrom-Carbin-Komplexes II. Alle experimentellen Angaben zur Datensamm-lung sowie zur Struktur bear beitung sind in Tab. I zusammengefaßt. Die umfangreichen Röntgenda-tensätze wurden auf einem speziell präparierten, rechnergesteuerten Diffraktometer (Enraf-Nonius-CAD 4) unter Verwendung eines von uns eigens entwickelten, über längere Zeiträume eine stabile (± 0,2 K) Temperatur gewährleistenden Tieftem-peratur-Zusatzes gesammelt. Die Sammlung der entsprechenden Neutronen-beugungsdaten für I erfolgte am ILL Grenoble mit | | | |
Reference
| Z. Naturforsch. 38b, 1431—1440 (1983); eingegangen am 11. Juli 1983 | | | |
Published
| 1983 | | | |
Keywords
| Carbene Complexes, Carbyne Complexes, Structural Analysis, Electronic Deformation Densities | | | |
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| default:Reihe_B/38/ZNB-1983-38b-1431.pdf | | | | Identifier
| ZNB-1983-38b-1431 | | | | Volume
| 38 | |
| 5 | Author
| WolfPeter Fehlhammer, Bartel Klaus, Dagobert Alfons Völkl, Achatz | Requires cookie* | | | Title
| Metallkomplexe funktioneller Isoeyanide, VI [1] Tosylmethyl-, Benzyl-und Benzhydrylisocyanid-Metallverbindungen und ihre Reaktionen mit Nucleophilen und 1.3-Dipolarophilen Metal Complexes of Functional Isocyanides, VI [1] Tosylmethyl-, Benzyl-and Benzhydrylisocyanide Metal Complexes and Their Reactions with Nucleophiles and 1,3-Dipolarophiles | | | | Abstract
| Metal complexes of the type M(CO)5L (M = Cr, W), MX2L2 (M = Pd, Pt; X = Cl, Br, 1), PtClo(L)PPh3, and [Pt(Cl)(L)(PPh3)2]BF4 have been prepared with L = CNCH2S02C6H4-^CH3, CNCHoPh, and CNCHPho, and reacted with a variety of nucleophiles (NH2CH2C02CH3, CH(CN)2", CH(CN)C02CH3-, OH-) and 1,3-dipolarophiles (CF3CN, CH3O2CCEECCO2CH3, CH2 = CHCN, RNCO (R -CH3, Ph), RCHO (R = i-C3H7, Ph, C6H4-0OH)) to give carbene, a-aminovinyl, and carboxamido complexes, and C2-metallated heterocycles (imidazoles, pyrroles, oxazolos, oxazolines), respectively. Ready de-alkylation occurs of benzhydryl isoeyanide in [Pt(Cl)(CNCHPh2)(PPh3)2]BF4* | | | |
Reference
| Z. Naturforsch. 37b, 1044—1053 (1982); eingegangen am 5. Februar 1982 | | | |
Published
| 1982 | | | |
Keywords
| Transition Metal Complexes of Functionalized Isocyanides, Reactions at Co-ordinated Ligands, Carbene Complexes, 1, 3-Dipolar Cycloadditions | | | |
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| default:Reihe_B/37/ZNB-1982-37b-1044.pdf | | | | Identifier
| ZNB-1982-37b-1044 | | | | Volume
| 37 | |
| 6 | Author
| WolfPeter Fehlhammer, Hans Hoffmeister, Heribert Stolzenberg, Borislav Boyadjiev | Requires cookie* | | | Title
| Bor-stabilisierte N,0-Carbene, I Triphenylbor-Addukte von Siloxy-und Hydroxyalkylisocyaniden und spontane At-YIid-Bildung Boron-Stabilized N.O-Carbenes, I Triphenylboron Adducts of Siloxy-and Hydroxyalkyl Isocyanides and Spontaneous Formation of Ate-Ylids | | | |
Reference
| Z. Naturforsch. 44b, 419 (1989); eingegangen am 27. D ezem ber 1988 | | | |
Published
| 1989 | | | |
Keywords
| Functionalized Isocyanides, Borane Isocyanide A dducts, Reactions at Coordinated Ligands, NO-H eterocycles, Carbene Complexes | | | |
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| default:Reihe_B/44/ZNB-1989-44b-0419.pdf | | | | Identifier
| ZNB-1989-44b-0419 | | | | Volume
| 44 | |
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