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Structure–Activity Relationship Analysis of Pd–PEPPSI Complexes in Cross-Couplings: A Close Inspection of the Catalytic Cycle and the Precatalyst Activation Model

✍ Scribed by Joanna Nasielski; Dr. Nilofaur Hadei; George Achonduh; Dr. Eric Assen B. Kantchev; Dr. Christopher J. O'Brien; Alan Lough; Prof. Michael G. Organ

Publisher
John Wiley and Sons
Year
2010
Tongue
English
Weight
559 KB
Volume
16
Category
Article
ISSN
0947-6539

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✦ Synopsis

Abstract

A series of Pd–N‐heterocyclic carbene (Pd–NHC) complexes with various NHC, halide and pyridine ligands (PEPPSI (pyridine, enhanced, precatalyst, preparation, stabilisation and initiation) precatalysts) were prepared, and the effects of these ligands on catalyst activation and performance were studied in the Kumada–Tamao–Corriu (KTC), Negishi, and Suzuki–Miyaura cross‐coupling reactions. The lowered reactivity of more hindered 2,6‐dimethylpyridyl complex 4 in the Negishi and KTC reactions is consistent with slow reductive dimerisation of the organometallic reaction partner during precatalyst activation. Comparative rate studies of complexes 1, 4 and 5 in the KTC and Suzuki–Miyaura reactions verify that 4 activated more slowly than the others. A potential on/off mechanism of pyridine coordination to NHC–Pd^0^ is also plausible, in which the more basic pyridine stays bound for longer.

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[MCl(ligand)]+ Complexes (M = Ni, Pd, Pt
[MCl(ligand)]+ Complexes (M = Ni, Pd, Pt) with a P,N,N Terdentate Ligand – Solid State and Solution Structures and Catalytic Activity of the PdII Derivative in the Heck Reaction
✍ Alessandro Del Zotto; Ennio Zangrando; Walter Baratta; Alessandro Felluga; Paolo 📂 Article 📅 2005 🏛 John Wiley and Sons 🌐 English ⚖ 159 KB 👁 1 views

## Abstract Ni^II^, Pd^II^ and Pt^II^ cationic complexes of the general formula [MCl(PNN)]PF~6~, where PNN is the terdentate ligand __N__‐[2‐(diphenylphosphanyl)benzylidene][2‐(2‐pyridyl)ethyl]amine, have been synthesised and fully characterised in solution by NMR spectroscopy. The diamagnetic Ni^I