76096-52-1Relevant academic research and scientific papers
KINETISCHE UND MECHANISTISCHE UNTERSUCHUNGEN VON UEBERGANGSMETALLKOMPLEX-REAKTIONEN. VI. KINETIK UND MECHANISMUS DER EINSCHIEBUNG VON DIMETHYLCYANAMID IN DIE METALL-CARBENKOHLENSTOFF-BINDUNG VON PENTACARBONYL(ARYLPHENYLCARBEN)WOLFRAM
Fischer, Helmut
, p. 303 - 314 (1980)
Pentacarbonyl(arylphenylcarbene)tungsten complexes, (CO)5W (Ia, R=OCH3; Ib, R=CH3; Ic, R=H; Id, R=Br; Ie, R=CF3) react with dimethylcyanamide (II) via insertion of the CN group into the metal-carbene bond.The formation of pentacarbonyltungsten(0) (IIIa-IIIe) follows a second-order rate law: d/dt=k.Replacement of R=H by electron-withdrawing substituents (Br, CF3) results in an increase, by electron-donating groups (CH3, OCH3) in a decrease of the reaction rate.The rate constants correlate well with Hammett's ?-constants.The activation enthalpies ΔH are low (37.3-41.6 kJ mol-1), the activation entropies ΔS strongly negative (-119 to -133 J mol-1 K-1).The results are discussed on the basis of an associative stepwise mechanism with a nucleophilic attack of the CN group of II at the carbene carbon in the first reaction step.
Insertion of Dimethylcyanamide into the Metal-Carbene Bond - A Route to Amino(alkylideneamino)carbene Complexes
Fischer, Helmut,Schubert, Ulrich,Maerkl, Robert
, p. 3412 - 3420 (2007/10/02)
Pentacarbonyl(arylmethoxycarbene)chromium and -tungsten (2a - d) as well as pentacarbonyl(diarylcarbene)tungsten complexes (2e - h) add dimethylcyanamide (3) via insertion of the CN group into the metal-carbene bond and pentacarbonyl complexes (4) are formed.The compounds 4 were characterized by spectroscopic data and in the case of pentacarbonylchromium(0) (4a) additionally by an X-ray analysis.
