The Si-Ge bond: Rearrangements, migrations, and cleavages

1-Chloropentamethyl-1-silylgermane, ClSiMe2GeMe3 (1), and 1-chloromethylpen tamethyl-1-silylgermane, ClCH2SiMe2GeMe3 (2), undergo Lewis acid-catalyzed rearrangements to ClGeMe2SiMe3 (3) and ClSiMe2CH2GeMe3 (4), respectively. U nder similar conditions the isomeric ClGeMe2SiMe3 (3) undergoes a fragmenta tion reaction involving the formation of Me3SiCl and Me2GeCl2, and ClCH2GeM e2SiMe3 (5) rearranges to ClMe2GeCH2SiMe3 (6). Methyllithium treatment of P h3SiGeMe3 and Me3SiGePh3 and [1,1']-tetramethylsilylgermylferrocenophane [( 1,1'-Me2SiMe2Ge((eta(5)-C5H4)(2)Fe] results in methylation of the silicon a tom and formation of the corresponding germyl anion. When the silicon-germa nium-bonded fragment is incorporated into a bimetallic transition metal com plex, i.e., (eta(5)-C5H5)Fe(CO)(2)SiMe2GeMe2Fe(eta(5)-C5H5)(CO)(2) (7), bas e treatment with 1 equiv of lithium diisopropylamide (LDA) leads to predomi nance of silyl group migration to the cyclopentadienyl ring over germyl mig ration (9:1). Treatment of 7 with a 2.5 molar excess of LDA, followed by qu enching with Me3SnCl, results in migration of both the silyl and germyl end s of the bridging group to form (eta(5)-{Me3Sn(CO)(2)Fe(eta(5)-C5H4GeMe2SiM e2C5H4})Fe(C))(2)SnMe3 (8).