SINGLE AND DOUBLE BASE-INDUCED MIGRATIONS AND REARRANGEMENTS OF GROUP-14 LIGAND BIMETALLIC COMPLEXES, TA(5)-C5H5)(CO)(M)M(ER(2))(N)M(CO)(M)(ETA(5)-C5H5) (M=FE(M=2),W,M,(M=3), (2))(N)=(SIME(2))(2),(SIME(2))(5),GEME(2),SNME(2))

Treatment of the bimetallic complexes [(eta(5)-C5H5)Fe(CO)(2)](2)(ER(2 ))(n), Fp(ER(2))(n)Fp (1), (ER(2))(n) = Si(2)Me(4) (1a), Si(5)Me(10) ( 1b), GeMe(2) (1c), and SnMe(2) (1d), with 1 equiv of lithium diisoprop ylamide, LDA, followed by quenching with Mel produced single-migration products Fp(EMe(2))(n)(eta(5)-C5H4)Fe(CO)(2)Me, (2a,c,d from 1a,c,d, respectively), and a mixture of single- 2b, and double-, [Me(CO)(2)Fe( eta(5)-C5H4)](2)(ER(2))(n) (3b), migration products from Ib. Treatment of 1d with of LDA, added slowly, also produced a novel dimeric comple x [(eta(5)-C5H4)Fe(CO)(2)SnMe(2)](2) (4) containing both Fe-Sn and (et a(5)-C5H4)-Sn bonds. A single-crystal structure of this latter complex was determined. Treatment of the starting materials (1a-d) with 2 equ iv of LDA followed by quenching with Mel yielded double-migration prod ucts, 3a-d, in moderate yields, 30%-60%. Quenching the reaction betwee n la and either 1 or 2 equiv of LDA with Me(3)SnCl yielded the analogo us tin single- and double-migrated derivatives, 5 and 6. Treatment of the analogous Mo and W tin complexes [(eta(5)-C5H5)M(CO)(3)](2)SnMe(2) , M = Mo, W, with LDA resulted in double-migration products, 7a,b. How ever, similar treatment of the related tungsten germanium derivative r esulted in cleavage of the W-Ge bond. After the reaction was quenched with MeI, (eta(5)-C5H5)W(CO)(3)Me was obtained.