Preparation, Spectroscopic and Structural Data

Typical modes for the preparation of (l-alkynyl)carbene complexes, as well as spectroscopic and structural data, are briefly summarized. Alkoxy-and amino(l-alkynyl)carbene complexes are available from metal carbonyls and metal isocyanides, respectively. 

Alkoxy(l-alkynyl)carbene ligands are obtained either by addition of an alkynyl group to a carbonyl ligand or by transformation of a carbene ligand by generation of an alkyne unit. 

Alkoxy(l-alkynyl)carbene Complexes via the Fischer Route 

The preparation of alkoxy(l-alkynyl)carbene complexes (e.g., of compounds L M = C(OR1)—C=CR) mostly follows the two-step Fischer procedure,14 involving addition of a 1-lithio alkyne LiC=CR to a metal carbonyl L M(CO) to give a metal acylate L M=C(CTLi+) — C= CR14, which is subsequently alkylated with an oxonium salt [R130]BF4,15 an alkyl triflate R10S02C — CF3,16,22 or an alkyl fluorosulfonate R103SF16a,n  

Some examples of such compounds, including typical spectroscopic data, are given in Table I. 

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