Modulation of S‐Centered Reactivity: Impact of Terminal Ligands on Alkynyl Addition in [Fe₂(μ‐S₂)(CO)₄L₂] Complexes

Abstract

The reactivity of complexes [Fe2(µ‐S2)(CO)4L2] (L = CO (1), PPh3 (2)), with lithium alkynylide reagents generated in situ, was investigated. The behavior of the S2‐bridge in these compounds depends on the substitution at the diiron core. The reaction with the hexacarbonyl derivative 1 leads to the formation of the 1,2‐dithiolene bridged complex [Fe2(µ‐SCH=C(R)S)(CO)6] (3R) while the molecule [Fe2(µ‐SH)(µ‐SC≡CR)(CO)4(PPh3)2] (5R), with an open butterfly structure, is isolated when reacting the disubstituted derivative 2. The disubstituted dithiolene complex [Fe2(µ‐SCH=C(Ph)S)(CO)4(PPh3)2] (4Ph) can only be obtained by substitution of carbonyls with PPh3 in 3R. In the presence of piperidine, 5R isomerizes into the 1,1’‐dithiolene bridged derivative 6Ph. The novel compounds 4‐6 were synthesized and characterized by IR and NMR spectroscopies. X‐ray crystallographic studies of the dithiolene complexes 3Ph‐4Ph allowed their structural analysis.