Weak M···H–C Interactions in Neutral Complexes, Anions and Cations of Palladium(II) and Rhodium(I) Containing the iso‐Quinoline Ligand – Anagostic or Preagostic?. Issue 46 (11th December 2017)

• Record Type: Journal Article
• Authors: Sajjad, M. Arif; Schwerdtfeger, Peter; Harrison, John A.; Nielson, Alastair J.
• Is Part Of: European journal of inorganic chemistry. Issue 46(2017)
• Page Start: 5485
• Page End: 5496
• Publication Date: 2017-12-11
• Subjects: Anagostic interactions -- Anagostic/preagostic divide -- Emerging covalency -- Cyclometallation -- Palladium; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201701094
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : DFT‐D calculations show that the above‐plane M··· H–C separations in square‐planar complexes of Pd II and Rh I containing the iso ‐quinoline ligand are influenced by whether the complexes are neutral, anionic or cationic, due mainly to changes in atomic charge on the metal, H and C atoms, but the nature of the cis ‐ligands also plays a part because of the development of weak intramolecular interactions. The Pd··· H–C separations are effected by strong σ‐withdrawing or π‐donating substituents placed at C 7 of the iso ‐quinoline ligand with the shortest anagostic Pd··· H separation of 2.218 Å achieved using the π‐donating S – substituent in an anionic complex. The same substituent on the cationic complex leads to Pd–C covalency. Lack of flexibility of the iso ‐quinoline ring system prevents the anagostic carbon approaching the metal when the electrostatics are favourable. Instead of an anagostic/preagostic divide, it is suggested that all complexes with above‐plane Pd··· H–C close approaches are termed anagostic, and where some agostic covalency develops below an NBO (Natural Bond Order) E (2) value of 5 kcal mol –1 they can be regarded as having an emerging preagostic condition. Abstract : DFT‐D calculations show that above‐plane M··· H–C separations in square‐planar complexes are influenced by whether the complexes are neutral, anionic or cationic due mainly to changes in atomic charge on the metal, H and C atoms but the nature of the cis ‐ligands also plays a part. Instead of an anagostic/preagostic divide it is suggested that all above‐plane M··· H–C close approaches are termed as anagostic.