Ghorai S, Meena R, Joseph AP, Jemmis ED. Comparison of RNC Coupling and CO Coupling Mediated by Cr-Cr Quintuple Bond and B-B Multiple Bonds: Main Group Metallomimetics.
J Phys Chem A 2021;
125:7207-7216. [PMID:
34402622 DOI:
10.1021/acs.jpca.1c05185]
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Abstract
A theoretical analysis of reductive coupling of isocyanide and CO mediated by a Cr-Cr quintuple bonded complex and B-B multiple bonded complexes shows how the difference in donor-acceptor capability of isocyanide and CO ligands controls the product distributions. In the case of CO, the Cr-Cr quintuple bonded complex is unable to show C-C coupling due to the high π- back bonding possibility of CO and the reaction follows the singlet potential energy surface throughout, whereas, in the case of isocyanide, less π- back bonding possibility allows the reactions to undergo a spin transition and gives a series of products with different spin multiplicities. Similarly, reactions of B-B multiple bonded complexes with CO and isocyanides are also controlled by donor-acceptor capabilities of ligands, and the C-C coupling takes place by changing the oxidation state of the boron centers from +I to +II, in contrast to the classical main group mediated reactions where stable oxidation states are always preserved. This part of the main group chemistry which is dominated by donor-acceptor bonding interaction is more likely to follow transition metal behavior.
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