Diphenylcarbene ligands

Benzannulation of the diphenylcarbene ligand by 2-ethynylglucose derivative 34 results in only low diastereoselection, albeit it represents a rather rare example of a low-temperature protocol [38] (Scheme 22). 

An interesting case is the coordination polymerisation of acetylene and higher alkynes. It may proceed by a mechanism quite similar to the metathesis polymerisation of cycloalkenes involving metal carbene and metallacycle (metallacyclobutene) species [45], The initiation and propagation steps in alkyne polymerisation (leading to a polymer of cis structure) in the presence of a catalyst with a diphenylcarbene initiating ligand are as follows ... 

The reaction " of the diphenylcarbene complex (21) with organonitriles, RCN, leads to the insertion product (22), as well as the nitrile complexes [(C0)5W(NCR)] and d5-[(CO)4W(NCR)2ketene]. In 1,1,2-trichloroethane, the reaction obeys the two-term rate law (1). Carbonyl ligand substitution occurs via... 

The fundamental interconversion of a ketene iridium complex with a carbene-CO iridium complex has been investigated by experimental [84] and theoretical [85] methods. A controlled, reversible conversion of a diphenylketene ligand to diphenylcarbene and CO ligands on a single iridium center was discovered and rationalized (reaction 8.53). 

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