PROTONATION AND METHYLATION REACTIONS OF 2-PYRIDYL-PALLADIUM(II) AND -PLATINUM(II) COMPLEXES

Article abstract of DOI:10.1016/S0022-328X(00)98785-0

The reactions of strong acids HX and HClO4 with the 2-pyridyl complexes 2, N)(PPh3)>2(X = Cl, Br), trans-2)(PEt3)2> and 2)(dppe)> yield the N-protonated derivatives cis-2)(PPh3)>, trans-2)(PEt3)2>ClO4 and 2)(dpee)>ClO4, respectively.The terminal 2-pyridyl group of trans-2)(PEt3)2> and 2)(dppe)> also reacts with Me2SO4/NaClO4 to give trans-2>(PEt3)2>ClO4 and 2>(dppe)>ClO4.Analogues N-protonation or N-methylation reactions occur with trans-2)(L)2>(L = PEt3, PPh3).The complexes trans-2)(PMe2Ph)2>ClO4(M = Pd, X = Cl and Br; M = Pt, X = Br) exhibit restricted rotation of the protonated 2-pyridyl group around the M-C bond.This and other chemical results and spectral data, such as the 13C NMR data of the PEt3 derivatives, are interpreted in terms of a significant contribution of a carbenelike limiting structure to the electronic configuration of this new type of ligand.