Abstract The new didentate N-donor ligands 2-(4-methyl-1H-pyrazol-1-yl) pyrimidine (4Me- pzpm, 1) and 2-(4-bromo-1H-pyrazol-1-yl) pyrimidine (4Br-pzpm, 2) have been synthesised and used to obtain the allylpalladium derivatives [Pd (η 3-2Me-C 3 H 4)(NN′)] X [X= BAr′ 4−, NN′= 1 (3), NN′= 2 (4); X= CF 3 SO 3−, NN′= 1 (5), NN′= 2 (6)]. In complexes 3− 6 two types of fluxional process have been found: apparent allyl rotation that is observed as ...