Organic Syntheses via Transition Metal Complexes. 80. Allenylidene Complexes from [(2-Aminoethenyl)carbene]chromium Complexes

Allylferrocenylselenide and the synthesis of the first seleno-substituted allenylidene complex: synthesis, spectroscopy, electrochemistry and the effect of electron transfer from the ferrocenylselenyl subunit

“…The formation of 3 from allylferrocenylselenide and trans-[Cl(dppmhRu=C=C=C=CH2]+ is thought to pro ceed by the mechanism outlined in Scheme 1, where REil represents the ferrocenylselenyl group, FcSe: re gioselective addition of the nucleophilic selenoether to Cr initially forms a cationic trisubstituted selenium center to which an allyl and a vinyl group are attached. Like its nitrogen or sulfur counterparts, this primary adduct is unstable and undergoes Cope (or Claisen) type [3,3] sigmatropic rearrangement to the final product. For allylic amines primary adducts trans [Cl(dppm)2Ru-C=C-C(NR2R')=CH2]+ can be detected at early stages of the reaction by virtue of their charac teristic CC stretch at ca.…”

“…Previous studies on trans [Cl(dppmhRu=C=C=C(NMe2)C2H4Fc]+ have given the following results: stepwise oxidation of first the ferro cenyl moiety and then the ruthenium(II) center gave rise to a small red-shift of the UV -vis charge transfer band in the visible range and the CC-stretch in the infrared spectrum and then a larger shift of both these bands to higher energies as the ruthenium is oxidized [8]. The spectroscopic changes accompanying ferrocene oxidation were, however, rather small owing to the ethylene insulator connecting the RuC 3 chromophore + NaSbF., -Noel I [3,3] Hetero-Cope…”

Fischer Carbene Complexes as Chemical Multitalents: The Incredible Range of Products from Carbenepentacarbonylmetalα,β-Unsaturated Complexes

“…Allenylidene complexes of the type 82 are also formed by elimination of ethanol from the b- amino-substituted alkenylcarbene complexes 78 by treatment with Lewis acids such as BF 3 or AlCl 3 . [45] Because the trimethylsilyl substituent in 21 is sterically highly demanding, the 1-dimethylaminocarbene complex 84 is formed by reaction with dimethylamine, the addition product (28 % at 20 8C) is also formed, but not the respective allenylidene complex of type 82. [16] The trimethylsilyl group may be removed from 84 by treatment with fluoride; in this way Wulff and co-workers obtained the first unsubstituted derivative 15 of this class of compounds.…”

Fischer-Carbenkomplexe als chemische Multitalente: die unglaubliche Produktpalette ausα,β-ungesättigten Carbenpentacarbonylmetall-Komplexen

“…Allenylidenkomplexe vom Typ 82 sind auch durch Eliminierung von Ethanol aus den b-aminosubstituierten Alkenylcarben-Komplexen 78 durch Behandlung mit Lewis-Säuren wie BF 3 oder AlCl 3 erhältlich. [45] Schema 2. Bildung der Allenylidenkomplexe 82 mit den Lithiumamiden 79-Li.…”