The Si−Ge Bond: Rearrangements, Migrations, and Cleavages

1-Chloropentamethyl-1-silylgermane, ClSiMe 2 GeMe 3 ( 1 ), and 1-chloromethylpentamethyl-1-silylgermane, ClCH 2 SiMe 2 GeMe 3 ( 2 ), undergo Lewis acid-catalyzed rearrangements to ClGeMe 2 SiMe 3 ( 3 ) and ClSiMe 2 CH 2 GeMe 3 ( 4 ), respectively. Under similar conditions the isomeric ClGeMe 2 SiMe 3 ( 3 ) undergoes a fragmentation reaction involving the formation of Me 3 SiCl and Me 2 GeCl 2, and ClCH 2 GeMe 2 SiMe 3 ( 5 ) rearranges to ClMe 2 GeCH 2 SiMe 3 ( 6 ). Methyllithium treatment of Ph 3 SiGeMe 3 and Me 3 SiGePh 3 and [1,1‘]-tetramethylsilylgermylferrocenophane [(1,1‘-Me 2 SiMe 2 Ge((η 5 -C 5 H 4 ) 2 Fe] results in methylation of the silicon atom and formation of the corresponding germyl anion. When the silicon−germanium-bonded fragment is incorporated into a bimetallic transition metal complex, i.e., (η 5 -C 5 H 5 )Fe(CO) 2 SiMe 2 GeMe 2 Fe(η 5 -C 5 H 5 )(CO) 2 ( 7 ), base treatment with 1 equiv of lithium diisopropylamide (LDA) leads to predominance of silyl group migration to the cyclopentadienyl ring over germyl migration (9:1). Treatment of 7 with a 2.5 molar excess of LDA, followed by quenching with Me 3 SnCl, results in migration of both the silyl and germyl ends of the bridging group to form (η 5 -{Me 3 Sn(CO) 2 Fe(η 5 -C 5 H 4 GeMe 2 SiMe 2 C 5 H 4 })Fe(CO) 2 SnMe 3 ( 8 ).