Cyclopentadienyl trimethylsilyl metal complexes

These compounds have been obtained indirectly by reactions of silylated acetylenes with metal carbonyls or olefin complexes. Thus, trimethylsilylphenylacetylene reacts with rj5-cyclopentadienylcobalt dicarbonyl, cobaltocene, or rjs-cyclopentadienyl-(l,3-cyclooctadiene) cobalt, in refluxing xylene, to give a mixture of cis- and trans-bis-(trimethylsilyl)cyclobutadiene complexes (R = Me, R = Ph) 68, 127, 137) ... 

The interaction of [MN(SiMe3)2] (M = Li, Na, K) and LiTMP with carbenes (1) (R = i-Pr, R = Me), (3) (R = i-Pr) and (4) (R = Me) in solution was also reported. Evidence of complexation of these carbenes with the Li, Na, and K species in solution was given by the NMR shifts for the relevant carbene center. Recently, the reaction of carbene (1) with lithium l,2,4-tris(trimethylsilyl)cyclopentadienide was reported to result in monomeric carbene complexes with 1 1 stoichiometry (R = H R = f-Bu (6), adamantyl (7), or 2,4,6-trimethylphenyl(8)). The crystal structure of (6) showed that the cyclopentadienyl ring is coordinated in an -fashion to the lithium center (see Alkali Metals Organometallic Chemistry) and there is a single a-interaction present between the lithium and the carbene center (Li-C(carbene)... 

There are three useful mechanistic papers, the first of which is on the mechanism of electrophilic substitution, specifically mercuration, which concludes that the initial mercuration takes place on the cyclopentadienyl ring without the involvement of the metal center. The other papers, by the same author, were on the acetylation of l,l -bis(trimethylsilyl)- and l,l -bis(tributylstannyl)ferrocenes, where it was concluded through mechanistic experiments using deuterium labeling that the attack of the acetyl chloride-aluminum trichloride complex occurred at the gxo-face of the cyclopentadienyl ring followed by a proton transfer from carbon to iron. ... 

---