Far infrared spectra of palladium compounds—II Pyridine and 2,2′-bipyridyl complexes of palladium (II) and platinum (II)

Palladium compounds of pyrimidine and pyridine derivatives – proposed structure assignment changes

“…They reached the conclusion that the cis-isomer, PtL,Cl,, formed for the reaction of K2PdC14 and L in water, isomerized rapidly, because of the higher stability of the trans-isomer. cis-[Pd(NH,),CI,] (9) and cis-[Pd(py),Cl,] (3) were isolated at low temperature but isomerized to the trans-compounds even in the solid state (2,3). This would explain why the cis-isomers of palladium are quite rare.…”

“…Infrared spectroscopy is a very effective method for distinguishing the cis from the trans-isomers of palladium complexes because there are marked differences in their spectra especially in the region of the skeleton vibrations of the complexes (3,6). Recently, the structure of a pyrimidine complex, dichloro-bis(1-methylcytosine)palladium(II), was determined by X-ray diffraction (7).…”

“…Recently, Kirschner et al reported some palladium complexes which seemed to be active (1). Previous studies on the chemistry of palladium complexes have shown that cis-[Pd(am),Cl,] isomerizes easily to the trans-isomer (2)(3)(4). It is therefore important that these isomerization reactions be well understood before drawing any conclusion from the antitumour activity results, especially when some of these tests are performed in nonaqueous solvents like DMF.…”

Synthesis and spectroscopic characterization of palladium(II) complexes with 6,8-dimethylimidazo[1,5-a]-1,3,5-triazin-4(3H)-one and 6,8-dimethyl-2-thioxo-2,3-dihydroimidazo-[1,5-a]-1,3,5-triazin-4(1H)-one

“…The other feature which can effect the coordination mode of (2) is the protolytic reactions with the pyrimidine nitrogens. Reported coordination compounds of Pd II with 1,2,4-triazolo[1,5-a]pyrimidine derivatives, pyridine and adenine are monomeric or polymeric species with squareplanar geometry of the central ion [8][9][10][11][12][13][14][15][16][17][18]. Some Pd II complexes like [Pd 2 (l-mtpo-N 3 ,N 4 ) 2 (phen) 2 ](NO 3 ) 2 (where phen = 1,10-phenanthroline, Hmtpo = 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one interact effectively with DNA plasmids, hence they may be treated as an alternative to Pt II analogs in cytotoxic activity against cancer cells [19].…”

“…Ligand (1) (Figure 1) is interesting for studying, because the purine donor atoms system [(N (7) and N (9)] are blocked by methyl groups and coordination sites are available for the pyrimidine ring system. In the literature there are only a few reports of coordination via N(3) or N(1) atoms in adenine [5][6][7].…”