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

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 tetraanion {[(μ-CO)Fe 2 (CO) 6 ] 4 [1,2,4,5-(μ-SCH 2 ) 4 C 6 H 2 ]} 4− ( 7 ) with 2-furancarbonyl chloride to give quadruple-butterfly complex [(μ-σ, π-C 4 H 3 O)Fe 2 (CO) 6 ] 4 [1,2,4,5-(μ-SCH 2 ) 4 C 6 H 2 ] ( 9 ), whereas triple-butterfly complex [(μ-Ph 2 P)Fe 2 (CO) 6 ] 2 [Fe 2 (CO) 6 ][1,2,4,5-(μ-SCH 2 ) 4 C 6 H 2 ] ( 11 ) could be produced by reaction of Ph 2 PCl with the μ-CO-containing dianion {[(μ-CO)Fe 2 (CO) 6 ] 2 [Fe 2 (CO) 6 ][1,2,4,5-(μ-SCH 2 ) 4 C 6 H 2 ]} 2− ( 10 ) generated in situ from the initially formed tetraanion 7 . Similarly, the triple-butterfly 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 CH═CH 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 ═CHCH 2 Br with the μ-CO-containing dianion {[(μ-CO)Fe 2 (CO) 6 ] 2 [Fe 2 (CO) 6 ][(μ-SCH 2 ) 4 C]} 2− ( 13 ) formed in situ from tetraanion {[(μ-CO)Fe 2 (CO) 6 ] 4 [(μ-SCH 2 ) 4 C]} 4− ( 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 .