Concurrent Stabilization of π‐Donor and π‐Acceptor Ligands in Aromatized and Dearomatized Pincer [(PNN)Re(CO)(O)2] Complexes1. (28th May 2014)

• Record Type: Journal Article
• Authors: Mazzotta, Michael G.; Pichaandi, Kothanda Rama; Fanwick, Phillip E.; Abu‐Omar, Mahdi M.
• Is Part Of: Angewandte Chemie. Volume 126:Number 32(2014)
• Page Start: 8460
• Page End: 8462
• Publication Date: 2014-05-28
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201403788
• Languages: English
• ISSNs: 0044-8249

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Aromatized cationic [(PNN)Re(π acid)(O)₂]⁺ (<bold>1</bold>) and dearomatized neutral [(PNN*)Re(π acid)(O)₂] (<bold>2</bold>) complexes (where π acid=CO (<bold>a</bold>), <italic>t</italic>BuNC (<bold>b</bold>), or (2, 6‐Me₂)PhNC (<bold>c</bold>)), possessing both π‐donor and π‐acceptor ligands, have been synthesized and fully characterized. Reaction of [(PNN)Re(O)₂]⁺ (<bold>4</bold>) with lithiumhexamethyldisilazide (LiHMDS) yield the dearomatized [(PNN*)Re(O)₂] (<bold>3</bold>). Complexes <bold>1</bold> and <bold>2</bold> are prepared from the reaction of <bold>4</bold> and <bold>3</bold>, respectively, with CO or isocyanides. Single‐crystal X‐ray structures of <bold>1 a</bold> and <bold>1 b</bold> show the expected <italic>trans</italic>‐dioxo structure, in which the oxo ligands occupy the axial positions and the π‐acidic ligand occupies the equatorial plane in an overall octahedral geometry about the rhenium(V) center. DFT studies revealed the stability of complexes <bold>1</bold> and <bold>2</bold> arises from a π‐backbonding interaction between the d_{<italic>xy</italic>} orbital of rhenium, the π orbital of the oxo ligands, and the π* orbital of CO/isocyanide.</p> </abstract>