Novel μ-CO-Containing Butterfly Fe/S Cluster Anions Generated from Tetrathiols, Fe₃(CO)₁₂, and Et₃N: Their Reactions with Electrophiles To Give Neutral Butterfly Fe/S Cluster Complexes

Abstract

Tetrathiol 1,2,4,5-(HSCH 2 ) 4 C 6 H 2 reacted with Fe 3 (CO) 12 and Et 3 N followed by treatment of the intermediate µ- CO-containing 10) generated in situ from the initially formed tetraanion 7. Similarly, the triplebutterfly complexes [(µ-Ph 2 P)Fe 2 (CO) 6 ] 2 [Fe 2 (CO) 6 ][(µ-SCH 2 ) 4 C] (14) and [(µ-σ,π-CH 2 CHdCH 2 )Fe 2 (CO) 6 ] 2 -[Fe 2 (CO) 6 ][(µ-SCH 2 ) 4 C] (16) were produced by reaction of Ph 2 PCl or CH 2 dCHCH 2 Br with the µ-CO- 12) generated initially by reaction of tetrathiol C(CH 2 SH) 4 with Fe 3 (CO) 12 and Et 3 N. The double-butterfly complex [Fe 2 (CO) 6 ] 2 [(µ-SCH 2 ) 4 C] (15) derived in situ from dianion 13 was also isolated as a minor product along with major products 14 and 15. All the new complexes 9, 11, and 14-16 were characterized by elemental analysis and IR and NMR spectroscopy, as well as by X-ray crystallography for 9, 11, 14, and 15.

Recent studies on chemistry of novel μ-CO-containing butterfly Fe/E (E = S, Se, Te) cluster salts

“…Also unexpected is that when cluster salt H⋅[Et 3 NH] 4 is treated with electrophile Ph 2 PCl under similar conditions, the starlike complex 18 containing one 2Fe2S and two 2FeSP subclusters is obtained, but not the expected starlike complex containing four 2FeSP subclusters. It follows that the chemical behavior of this quadruple butterfly four μ-CO-containing Fe/S cluster salt resembles that of the triple butterfly three μ-CO-containing salt F⋅[Et 3 [33] .…”

“…Very recently, we [33] found that when tetrathiol 1,2,4,5-(HSCH 2 ) 4 C 6 H 2 reacts with Fe 3 (CO) 12 and Et 3 N in a 1:4:4 molar ratio in THF at room temperature, the expected novel quadruple butterfly four µ-CO-containing cluster salt H⋅[Et 3 NH] 4 can be obtained. However, when this salt reacts further in situ with 2-furancarbonyl chloride, the expected starlike Fe/S complex m 14 is not obtained, but instead, an unexpected starlike Fe/S complex 17 is produced.…”

“…That is, starlike intermediate m 14 is first formed by nucleophilic attack of the four negatively charged Fe atoms in H⋅[Et 3 NH] 4 at the four acyl C atoms in four molecules of furancarbonyl chloride followed by displacement of the four μ-CO ligands in H⋅[Et 3 NH] 4 . Then, starlike product 17 is obtained by loss of the four μ-acyl carbonyls of m 14 followed by coordination of the four C== C double bonds located in four furan rings of m 14 , respectively (Scheme 15) [33] .…”

“…As can be seen in Figure 12, this complex has four identical butterfly subclusters, which are connected through their S1, S2, S1A and S2A atoms to four α-C atoms of the central benzene ring by equatorial bonds. In addition, the four furan rings in butterfly subclusters are all coordinated to two Fe atoms through one of their C== C double bonds with a σ,π-manner [19,20,33] . Also unexpected is that when cluster salt H⋅[Et 3 NH] 4 is treated with electrophile Ph 2 PCl under similar conditions, the starlike complex 18 containing one 2Fe2S and two 2FeSP subclusters is obtained, but not the expected starlike complex containing four 2FeSP subclusters.…”

“…As can be seen in Figure 13, complex 18 contains one butterfly 2Fe2S subcluster and two butterfly 2FeSP subclusters. The former is connected via its two sulfur atoms S1 and S2 to the neighboring two α-C atoms of the central benzene ring by axial bonds, whereas the latters are linked to another two neighboring α-C atoms of the central benzene ring via their sulfur atoms S3 and S4 by equatorial bonds [19,20,33] .…”