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Copper and Silver Carbene Complexes without Heteroatom‐Stabilization: Structure, Spectroscopy, and Relativistic Effects
Author(s) -
Hussong Matthias W.,
Hoffmeister Wilhelm T.,
Rominger Frank,
Straub Bernd F.
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201504117
Subject(s) - heteroatom , carbene , copper , spectroscopy , chemistry , photochemistry , physics , organic chemistry , catalysis , astronomy , ring (chemistry)
Abstract Salts of a copper and a silver carbene complex were prepared from dimesityl diazomethane, made possible by the steric shielding of the N‐heterocyclic carbene (NHC) ancillary ligand IPr**. The mint‐green complex [IPr**Ag=CMes 2 ] + [NTf 2 ] − is the first isolated silver carbene complex without heteroatom donor substituents. Single‐crystal X‐ray diffraction provides evidence for a predominant carbenoid character, and supports the postulation of such reactive species as intermediates in silver‐catalyzed CH activation reactions. The greenish yellow copper carbene complex [IPr**Cu=CMes 2 ] + [NTf 2 ] − has spectroscopic properties in between the isostructural silver complex and the already reported emerald green gold carbene complex. A comparison in the Group 11 series indicates that relativistic effects are responsible for the strong σ bond and the significant π back‐bonding in the gold carbene moiety.