Activation and functionalization of vinylic C-F bonds by transition metal compounds: The factors determining reactions between nucleophiles and a (perfluorovinyl)diiron(I) complex; Syntheses of diiron derivatives containing new C-N, C-S, C-H and C-O bonds

The reactions between alcohols ROH (R = Me, Et) and RR(OH)(2) (RR = CH2-CH2) and the [perfluoro(sulfanyl)vinyl]-diiron complex [[Fe(CO)(3)}(2)(p-C(SMe)(CF3)CbetaCalphaF2}] (1) in THF at room temperature involve substitution at the C. atom to give new (alkoxymethylene)thiaferracyclobutadiene compounds [{Fe(CO)(3))(2)] t-S(Me)C(CF3)CbetaCalpha(OR)(2)}] [R = Me (2a), Et (2b); RR = CH2CH2 (2c)]. Treatment of I with aniline and (methoxycarbonyl)hydrazine, bases of intermediate strength according to Pearson, produces alpha, beta-substituted thiaferracyclopentadiene [(Fe(CO)(3)}(2) t-S(Me)C(CF3)CO(NHR)Cbeta(NHR)C-alpha [R = Ph (5a), NHC(O)OMe (5b)] complexes. It is suggested that these compounds form through initial nucleophilic attack at C. to give the zwitterionic intermediate [[Fe(CO)(3)}(2)(mu-S(Me)C(CF3)CC(NRH)(2)}] (f). Thermally induced C-F bond activation is a feature of these reactions. When I reacts with thioamides containing three “hard” competitive primary and secondary amine functions and one “soft” thione function, the nucleophile first attacks at C, through a secondary amine and, in a second step, at Cbeta through the thiol function to give alpha,beta adducts [jFe(CO)(3)}(2){mu-S(Me)C(CF3)CpSC(=NR2)N(R-1)C-alpha(C-beta-C-alpha) [R-3 = NH2, R-2 = CH3 (6a); R-1 = CH3, R-2 = H (6b); R-1 = R-2 = CH3 (6c)] possessing novel immothiazolidine systems fused to the five-membered metallacyclic ring. Treatment of I with acetylhydrazine, which has three “hard” nucleophilic functions, results in the formation of the compound [Fe(CO)(3)}(2){mu-S(Me)C(CF3)C(H)C((10))NNC(Me)O(C((10))-O)}] (7a), in which an oxadiazole function is fused to the thiaazaferracyclohexene ring. The position of the fluorine substituent on the CalphaCbetaCgamma(CF3)S(Me) ring of ferracyclopentadiene complexes has been found to be the essential factor determining the specific activation of the C-F bond. A single fluoro substituent attached to the P-carbon atom of the chain can be activated y nucleophiles to give alpha,beta adducts [{Fe(CO)(3)}(2){mu-S(Me)C(CF3)C-beta(X)C-alpha(NRR’)}] [X = OR”, R = R’ = R” Me (3a); X = OR”, R = R” = Me, R” = C(O)NMe2 (3b); X SR” (4)]. In contrast, complexes in which a single fluorine atom is linked to the alpha-carbon atom do not undergo C-F bond cleavage reactions. X-ray structures of compounds 2a, 3b, 5a, 5b, 6a and 7a are reported.