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The Effect of Remote Donor Substituents on the Properties of Alkoxy and Amino Fischer Carbene Complexes of Tungsten
Author(s) -
Weststrate Noraann,
Hassenrück Christopher,
Linseis Michael,
Liles David C.,
Lotz Simon,
Görls Helmar,
Winter Rainer F.
Publication year - 2021
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.202100081
Subject(s) - carbene , substituent , chemistry , alkoxy group , electrophile , ligand (biochemistry) , transition metal carbene complex , delocalized electron , medicinal chemistry , crystallography , photochemistry , stereochemistry , organic chemistry , alkyl , catalysis , biochemistry , receptor
Tungsten Fischer ethoxy‐ and dimethylaminocarbene complexes [W{C(X)(C 6 H 4 ‐4‐R}(CO) 5 ] (X=OEt: series a ; or X=NMe 2 : series b ) are synthesized from phenyl substrates containing remote tertiary amino substituents R’ 2 N with R’=Me ( 2 ), Ph ( 3 ) or C 6 H 4 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 .