Bond‐Stretch Isomers and Spin‐State Isomers: A Comment on the Article “Bond‐Stretch Isomers: Fact not Fiction”

What exactly is meant by bond‐stretch isomerism? Confusion seems to reign about the phenomenon, partly because the original papers did not explicitly define the term. However, if limited to its original meaning, no bond‐stretch isomers have yet been discovered, in spite of a recent claim to the contrary (see Correspondence by P. Giitlich, H. A. Goodwin, and D. N. Hendrickson in the second February issue of Angewandte Chemie).