image: Skeletons I-V containing three or four coplanar M–C σ bonds are shown on the left. The two skeletons with five coplanar M–C σ bonds are placed on the right. Art by Dafa Chen.
Credit: Art by Dafa Chen.
This study is led by Dr. Haiping Xia (Southern University of Science and Technology). The team described the synthesis and characterization of two kinds of complexes with five coplanar M–C σ bonds, whose nature was supported by both experimental and computational data. The successful construction of those structures is attributed to the use of a carbon chain as a rigid and polydentate ligand (see right image below) and the conjugation effect between sp2 carbons and the metal center, which maintains the M–C σ bonds in a single plane and prevents elimination of the two neighboring carbons that bind to the metal. Those complexes were found to be exceptionally stable at temperatures even up to 100 ℃ in moisture or air. Those novel structures expanded the coplanar M–C σ bonds to five.
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See the article:
Experimental and theoretical evidences for the formation of transition metal complexes with five coplanar metal-carbon σ bonds
https://doi.org/10.1093/nsr/nwad325
Journal
National Science Review