Deprotonation Pathway in the Reaction of Me6Si2 with MeLi

A mixture of 3 mol of Me 6 Si 2 and 1 mol of MeLi in the presence of P(O)(NMe 2 ) 3 produced Me 3 SiLi as the initial product. This then deprotonated excess Me 6 Si 2 and started an unprecedented transformation leading to (Me 3 Si) 2 (SiMe 2 H)CLi ( 3 ), whose quench by [(η 5 -C 5 H 5 )Fe(CO) 2 PPh 3 + ] produced {η 4 - exo -[(Me 3 Si) 2 C-(SiMe 2 H)]C 5 H 5 }Fe(CO) 2 (PPh 3 ) ( 2e ). In the literature the reaction of Me 6 Si 2 and MeLi gives Me 3 SiLi and/or Me 3 SiSiMe 2 Li ( 4 ). The lithium compound 3 is the major product when a previously unnoticed deprotonation pathway is enhanced by use of an excess of Me 6 Si 2 and a longer reaction time.