139705-59-2Relevant academic research and scientific papers
Nitrile Addition to (η4-Butadiene)zirconocene: The Formation of Organometallic and Metal-Free Hexatrienediamine Derivatives
Erker, Gerhard,Pfaff, Ronald,Krueger, Carl,Nolte, Matthias,Goddard, Richard
, p. 1669 - 1674 (2007/10/02)
(η4-Butadiene)zirconocene adds one equivalent of benzonitrile to form the five-membered azazirconacyclopentene derivative 7, which contains an NH group in the ring and a vinyl substitutent at the α-carbon center.The reaction of 7 with an additional equivalent of benzonitrile furnishes the chiral nine-membered metallacycle (12) which may be isomerized to the thermodynamically favoured tautomer (13).The Gibbs activation energy of the enantiomerization of the trans-cycloalkene-like 13 is ΔG(excit.) (323 K) = 15.5 +/- 0.3 kcal mol-1.The analogous conformational equilibration of 12 has a lower activation barrier of ΔG(excit.) (236 K) = 12.1 +/- 0.3 kcal mol-1; complex 13 is characterized by X-ray diffraction.Hydrolysis of 13 yields the conjugated 1,6-diamino-1,6-diphenylhexatriene 16 which is characterized by X-ray diffraction. Key Words: Butadiene dianion equivalent, 1,4-addition / Metallocene template, bent / Enamine, primary, stable / Metallacycles, nine-membered, chiral / Zirconocene
