Synthesis and NMR structural analysis of several orthopalladated complexes of substituted benzo-imidazole, -oxazole and -thiazole and study of two polymorphic crystals

Article abstract of DOI:10.1016/0022-328X(96)06218-3

The full assignation of ¹H and ¹³C 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 of N-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.