Answers are grounded in this paper and cite their sources.
Multiconfigurational quantum chemical calculations on the R-diimines dichromium compound confirm that the Cr-Cr bond, 1.80 A, is among the shortest Cr(I)-Cr(I) bonds. However, the bond between the two Cr atoms is only a quadruple bond rather than a quintuple bond. The reason why the bond is so short has to be attributed to the strain in the NCCN ligand moieties.
No takes yet. Share an insight, caveat, or question.
Macchia et al. (2008) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: