(Pyrazol-1-ylmethyl)pyridine palladium complexes: Synthesis, molecular structures, and activation of small molecules

Reactions of 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L1) and 2-(3,5-di-tert-butylpyrazol-1-ylmethyl)pyridine (L2) with either [PdClMe(COD)] or [PdCl2(COD)] gave the mononuclear palladium complexes [PdCl2(L1)] (1), [PdClMe(L1)] (2) [PdCl2(L2)] (3) and [PdClMe(L2)] (4) in good yields. All compounds were characterized by NMR spectrometry, mass spectrometry, elemental analyses and also by single crystal X-ray crystallography for complexes 1, 3, and 4. The reaction of 2 with NaBAr4 in NCMe gave the salt, [[PdMeNCMe(L3)]BAr4 (5), in good yield. This salt was used as a catalyst to oligomerize ethylene at high pressures to branched polyethylene, but catalytic activity was low. The reaction of 2 with SO2 and CO formed the respective insertion products [PdClS(O)2Me(L1)] (6) and [PdClC(O)Me(L1)] (7).