Evaluation of Pd→B Interactions in Diphosphinoborane Complexes and Impact on Inner‐Sphere Reductive Elimination

• Published in: Chemistry : a European journal Vol. 26; no. 59; pp. 13436 - 13444
• Main Authors: Ritter, Florian, John, Lukas, Schindler, Tobias, Schroers, Julian P., Teeuwen, Simon, Tauchert, Michael E.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 21.10.2020; John Wiley and Sons Inc
• Subjects: Amides; boranes; Chemistry; donor–acceptor systems; Lithium; Magnetic resonance spectroscopy; NMR; NMR spectroscopy; Nuclear magnetic resonance; Oxidation; palladium; phosphine ligands; reductive elimination; Valence; boranes; palladium; donor-acceptor systems; reductive elimination; phosphine ligands
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.202001189

The dative Pd→B interaction in a series of RDPBR’ Pd0 and PdII complexes (RDPBR’=(o‐PR2C6H4)2BR’, diphosphinoborane) was analyzed using XRD, 11B NMR spectroscopy and NBO/NLMO calculations. The borane acceptor discriminates between the oxidation state PdII and Pd0, stabilizing the latter. Reaction of lithium amides with [(RDPBR’)PdII(4‐NO2C6H4)I] chemoselectively yields the C−N coupling product. DFT modelling indicates no significant impact of PdII→B coordination on the inner‐sphere reductive elimination rate. Ligand effects: The borane acceptor in diphosphinoborane ligands discriminates between the oxidation state PdII and Pd0, stabilizing the latter. The impact of the Pd→B interaction on inner‐sphere C−N bond reductive elimination of N,N‐dimethyl‐4‐nitroaniline was investigated (see scheme).