The full assignation of 1 H and 1 3 C NMR parameters using both homo- and hetero-nuclear two dimensional spectroscopy techniques (COSY, HMQC and HMBC) allows the determination of electronic properties in cyclopalladated complexes obtained by reaction ofN -methyl-2-phenylbenzimidazole (a), 2-phenylbenzothiazole (b) and 2-phenylbenzoxazole (c) with palladium salts.The attempts to separate the anti and syn isomers (detected by NMR) led to the formation of two different kinds of crystal for the 2-phenylbenzoxazole palladium complex, 1c (yellow and orange). The X-ray diffraction study of these crystals indicates the formation of two polymorphic phases both in anti disposition.