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Metal‐Ligand Cooperativity in a Methandiide‐Derived Iridium Carbene Complex
Author(s) -
Weismann Julia,
Waterman Rory,
Gessner Viktoria H.
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201503936
Subject(s) - carbene , chemistry , reactivity (psychology) , ligand (biochemistry) , ruthenium , nucleophile , dehydrogenation , dihydrogen complex , medicinal chemistry , bond cleavage , photochemistry , iridium , metal , catalysis , stereochemistry , hydride , organic chemistry , medicine , biochemistry , alternative medicine , receptor , pathology
The synthesis, electronic structure, and reactivity of the first Group 9 carbene complex, [Cp*IrL] [L=C(Ph 2 PS)(SO 2 Ph)] ( 2 ), based on a dilithio methandiide are reported. Spectroscopic as well as computational studies have shown that, despite using a late transition‐metal precursor, sufficient charge transfer occurred from the methandiide to the metal, resulting in a stable, nucleophilic carbene species with pronounced metal‐carbon double‐bond character. The potential of this iridium complex in the activation of a series of E−H bonds by means of metal‐ligand cooperation has been tested. These studies have revealed distinct differences in the reactivity of 2 compared to a previously reported ruthenium analogue. Whereas attempts to activate the O−H bond in different phenol derivatives resulted in ligand cleavage, H−H and Si−H activation as well as dehydrogenation of isopropanol have been accomplished. These reactions are driven by the transformation of the carbene to an alkyl ligand. Contrary to a previously reported ruthenium carbene system, the dihydrogen activation has been found to proceed by a stepwise mechanism, with the activation first taking place solely at the metal. The activated products further reacted to afford a cyclometalated complex through liberation of the activated substrates. In the case of triphenylsilane, cyclometalation could thus be induced by a substoichiometric (i.e., catalytic) amount of silane.