The Effect of Remote Donor Substituents on the Properties of Alkoxy and Amino Fischer Carbene Complexes of Tungsten. Issue 11 (7th May 2021)

• Record Type: Journal Article
• Authors: Weststrate, Nora‐ann; Hassenrück, Christopher; Linseis, Michael; Liles, David C.; Lotz, Simon; Görls, Helmar; Winter, Rainer F.
• Is Part Of: Zeitschrift für anorganische und allgemeine Chemie. Volume 647:Issue 11(2021)
• Page Start: 1152
• Page End: 1164
• Publication Date: 2021-05-07
• Subjects: Fischer carbene complexes -- tungsten carbene complexes -- (spectro)electrochemistry -- quantum chemical calculations; Chemistry, Inorganic -- Periodicals; Chemistry -- Periodicals; 540
• DOI: 10.1002/zaac.202100081
• Languages: English
• ISSNs: 0044-2313

Abstract

Abstract: Tungsten Fischer ethoxy‐ and dimethylaminocarbene complexes [W{C(X)(C6 H4 ‐4‐R}(CO)5 ] (X=OEt: series a ; or X=NMe2 : series b ) are synthesized from phenyl substrates containing remote tertiary amino substituents R'2 N with R'=Me (2 ), Ph (3 ) or C6 H4 Br‐4 (4 ). The π‐delocalization and carbene‐stabilizing effects of the distant tertiary amine donor substituent are investigated by NMR and IR spectroscopy, electrochemistry and quantum chemical calculations. A significant transfer of electron density from the remote 4‐R'2 N substituent to the carbene C atom in the ethoxycarbene complexes is supported by NMR data and the solid‐state structure of 2 a . This is strongly attenuated in the amino‐substituted carbene complex 2 c and irrelevant in the dimethylaminocarbene complexes of series b, where the electron demand of the electrophilic carbene center is satisfied by the directly attached dimethylamino substituent. Quantum chemical calculations and IR spectroelectrochemistry on complexes 1 a‐ ‐4 a verify carbene‐centered reductions and a ligand based oxidation of complex 2 b . Abstract :