98705-13-6Relevant academic research and scientific papers
Study of the reactivity of [HFe4(CO)13]- toward acetylene and monosubstituted alkynes. X-ray structure determination of [N(P(C6H5)3)2][Fe 4(μ4-η3-C(CH 3)CHCH)(μ-CO)2(CO)9]
Alami, Mahmoud Kalam,Dahan, Fran?oise,Mathieu, René
, p. 2122 - 2127 (2008/10/08)
[PPN][HFe4(CO)13] (1; PPN = N(P(C6H5)3)2) reacts with acetylene in boiling ethyl acetate to give [PPN][Fe4(μ3-CCH3)(CO)12] (2) in a first step. This cluster then reacts with a second molecule of acetylene in boiling 3-pentanone leading to [PPN][Fe4(μ4-η3-C(CH 3)CHCH)(μ-CO)2(CO)9] (3) whose structure has been determined by X-ray diffraction. 3 is monoclinic of space group C2h5-P21/n with a = 23.014 (4) A?, b = 9.420 (1) A?, c = 22.166 (4) A?, β = 90.45 (1)°, and Z = 4. The structure has been solved and refined to R and Rw values of 0.026 and 0.030, respectively, using 4539 reflections. 3 contains an allylic ligand, resulting from the coupling of the ethylidyne ligand with one molecule of acetylene, μ4-η3-bonded to a butterfly arrangement of the four iron atoms. Extension of the study to monosubstituted alkynes, RC≡CH, shows that the reaction is alkyne dependent and two types of reactions have been observed. If the substituents on the alkyne have electron-withdrawing properties like R = C6H5 or CH3OC(O), complexes of type 3 with the C(CH2R)CHC(R) allylic ligand are formed directly without observation of the alkylidyne intermediate. If the substituents R are electron-donating alkyl groups, fragmentation of the tetranuclear unit of the cluster is observed and trinuclear anionic clusters [PPN][Fe3(μ3-C≡CR)(CO)9] are formed. The fluxionality of complexes with the structure of 3 is also discussed.
