Synthesis of [Fe 2(CO) 6(μ-SC 2H 5)(μ-CCR)] (R = CH 3 or C 6H 5) and reactivity with electron-rich molecules, triphenylphosphine, diphenylacetylene, ethylthio(phenyl) ethyne and (diethylamino) propyne. Preparation of [Fe 2(CO) 6(μ-SCCC 6H 5)(μ-CCC 6H 5)] and formation of [Fe 4(CO) 12(μ 4-S)(μ-CCC 6H 5) 2

Abstract

Compounds [Fe 2(CO) 6(μ-SC 2H 5)(μ-CCR)] with R = CH 3 or C 6H 5, were prepared and allowed to react with triphenylphosphine, diphenylacetylene, (ethylthio)phenylethyne, 1-(diethylamino)prop-1-yne. These four reactants are electron-rich molecules able to attack at the acetylide carbon atoms C α ≡ C βR. The structures of nine complexes were determined by X-ray diffraction. For R = CH 3 or P(C 6H 5) 3 reaction occurred at C β leading to [Fe 2(CO) 6(μ-SC 2H 5)μ-C=C[P(C 6H 5) 3](CH3)]. In the case of R = C 6H 5, a monosubstituted complex [Fe 2(CO) 5P(C 6H 5) 3(μ-SC 2H 5)(μ-CCC 6H 5)] and a disubstituted complex [Fe 2(CO) 4P(C 6-H 5) 32(μ-SC 2H 5)(μ-CCC 6H 5)] were obtained. With C 6H 5CCC 6H 5, [Fe 2(CO) 5 μ-S(C 2H 5)C(R)CC(C 6H 5C(C 6H 5)C(O))] was obtained (R = CH 3 or C 6H 5). The opening of the triple bond of the incoming alkyne led to two CC bonds, one with acetylide C α , one with a carbonyl group. The SC 2H 5 moved around an iron atom from a bridging position to be linked to C β . In addition, for R = C 6H 5 is omer was obtained the structure of which is based on a nido Fe 2C 3 framework. It readily transformed into [Fe 2(CO) 5μ-S(C 2H 5)C(C 6H 5)CC(C 2H 5)C(C,H,)C(O)]. With C 6H 55C≡CSC 2H 5 two complexes, [Fe 2(CO) 5μ-S(C 2H 5)C(C 6H 5)CC(C 6H 5)C(SC-H 5)C(O)] (80%) and [Fe 2(CO) 5μ-S(C 2H 5)C(C 6H 5)CC(SC 2H 5)C(C 6H,)C(O)] (20%), were obtained. They are of the same structural type as above. The major product resulted from the coupling of thioalkyne C β with acetylide C α . With CH 3C≡CN(C 2H 5) 2 the complex obtained, [Fe 2(CO) 6C[C(O)SC 2H 5]C(C 6H 5)C(CH 3)C[N(C 2H 5) 2]], has a structure based on a ferracyclopentadienyl fragment ligated to a second iron atom by a FeFe bond and by an allylic fragment. An unprecedented CO insertion occured in a side chain, yielding an ethylthiocarboxy radical. Both CS bonds were eventually cleaved using S(C≡CC 6H 5) 2 as a starting alkyne. First, [Fe 2(CO) 6(μ-SC≡CC 6H 5)(μ-C≡CC 6H 5)] was prepared. Second, an excess of iron carbonyl yielded [Fe 4(CO) 12(μ 4-S)(μ-C≡CC 6H 5) 2]. The four iron atoms belong to two dinuclear entities and form a tetrahedron around sulfur.