Electronic and Steric Manipulation of the Agostic Interaction in benzo[h]quinoline Complexes of Pd(II) and Implications for the Formation of η1‐Pd–C Bonds. Issue 27 (26th June 2020)

• Record Type: Journal Article
• Authors: Nielson, Alastair J.; Harrison, John A.; Sajjad, M. Arif; Schwerdtfeger, Peter
• Is Part Of: European journal of inorganic chemistry. Issue 27(2020)
• Page Start: 2639
• Page End: 2650
• Publication Date: 2020-06-26
• Subjects: C–H bond activation -- Agostic interactions -- Syndetic donation -- η1‐Pd–C bonding -- Cyclometallation reactions; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.202000348
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : Structures and properties were obtained by density functional (DFT) calculations for the complexes [PdCl2 (L)] (L = benzo[ h ]quinolines) containing aromatic ring agostic interactions. The inflexibility of the benzenoid rings of the ligands keep the structures of the complex relatively constant when electron withdrawing substituents are added to the aromatic ring para to the agostic carbon but electron donation causes a change to η 1 ‐Pd–C bond complexes in which agostic donation is significantly reduced and π‐syndetic donation no longer features. Increasing the steric size at the α‐carbon through the series H, Me, CHMe2, CMe3 or Ph, changes the manner in which the ligand sits in relation to the coordination plane but a change in the way the nitrogen atom of the ligand tilts in relation to the coordination plane does not effectively reduce the agostic or syndetic donations. CPh3 reduces the agostic donation but not the syndetic donation and C(Ph‐2, 6‐Me2 )3 turns both donations off and installs η 2 π‐donation on one aromatic ring. Placing ortho ‐substituents on the ring can influence the interplay of electronic and steric effects when η 1 ‐Pd complexes are formed. Abstract : DFT calculations show that agostic complexes of the form [PdCl2 (L)] (L = benzo[ h ]quinoline and substituted benzo[ h ]quinolines) can be converted to η 1 complexes by electron‐donating substituents. Various combinations of steric and electronic effects are able to influence agostic and syndetic donations and the magnitude of the η 1 ‐Pd–C bonding system.