THE REACTION OF (MU(3)-CCO(2)R)CO(2)M(CO)(8)L (M=CO,MO,W L=CO,MECP R=ME,ET) WITH NA-2[FE(CO)(4)] - X-RAY CRYSTAL-STRUCTURE ANALYSIS OF (ETO(2)CCCCO(2)ET)CO-4(CO)(10) AND (MEO(2)CCCCO(2)ME)FECO2(CO)(9)

The reactions of clusters [(mu(3)-CCO(2)Et)Co(2)M(CO)(8)(MeCp)][M = Mo (2a), W (2b)], derived from the reactions of (mu(3)-CCO(2)Et)Co-3(CO) (9) with Na[M(CO)(3)(MeCp)], with Na-2[Fe(CO)(4)] in THF at reflux not only gave the expected metal fragment exchange products [(mu(3)-CCO(2 )Et)FeCoM (CO)(8)(MeCp)H][M = Mo (3a), W (3b)], but also gave the unex pected compounds [(mu(3)-CCO)FeCoM(CO)(8)(MeCp)][M = Mo (4a), W (4b)]. It is suggested that the formation of two kinds of compounds resulted from two competitive reactions of the intermediates [(mu(3)-CCO(2)Et) FeCoM(CO)(8)(MeCp)](-) with acidic treatment: the one is the protonic reaction of the intermediate giving the clusters 3a and 3b; the other is the intermolecular nucleophilic substitution reaction of the interm ediate by the catalysis of H+, giving the clusters 4a and 4b. Under th e different reaction temperature and molar ratio of the starting mater ials, the reactions of (mu(3)-CCO(2)R)Co-3(CO)(9)[R = Me (1a), Et (1b) ] with Na-2[Fe(CO)(4)] produced two kinds of novel clusters (RO(2)CCCC O(2)R)Co-4(CO)(10) [R = Me (6a), Et (6b)] and (RO(2)CCCCO(2)R)FeCo2(CO )(9)[R = Me (7a), Et (7b)] besides the expected exchange products mu(3 )-CCO(2)R)FeCo2(CO)(9)H[R = Me (5a), Et (5b)l. This is the first examp le that the reaction of 6a and 6b with Na-2[Fe(CO)(4)] could produce t he clusters 7a and 7b. The clusters (EtO(2)CCCCO(2)Et)Co-4(CO)(10) and (RO(2)CCCCO(2)R)FeCo2(CO)(9) were determined structurally by X-ray di ffraction. Copyright (C) 1996 Elsevier Science Ltd