α‐ and β‐[Fe 2 (μ‐S t Bu) 2 (S t Bu) 4 ] 2− : Coexistence of Two Bond‐Stretch Isomers of a Classical Bitetrahedral Metal Chalcogenolate Compound

Two of a kind : [Fe 2 (S t Bu) 6 ] 2− shows a new form of isomerism. Besides the isomer of classical structure 1 a (red Fe, yellow S) there is also a variant ( 1 b ) in which the central Fe 2 S 2 rhomb is inverted and the FeS bonds are distinctly shorter. 1 b can be regarded as a transition state during the inversion of the bridging sulfur atoms of 1 a that is stabilized by significant π interactions.