Palladium complexes multidentate

A logical extension of the condensation reactions which yield multidentate nitrogen donors is the formation of macrocyclic ligands. The preference of palladium for square planar coordination makes it an ideal metal for the formation of complexes of these ligands. Thus palladium porphyrins are very stable and resistant to demetallation.281 Both 14- and 16-atom macrocycles have been used to form complexes. The ligand l,8-dihydro-5,7,12,14-tetramethyl-dibenzo[b,i][l,4,8,ll]tetraaza[14]annulene reacts with [PdCl2(PhCN)2] to yield the complex (46). 

The number and variety of coordination complexes of palladium(II) with sulfur-containing bidentate or multidentate ligands is legion, and it is possible here only to summarize the different kinds of complexes formed and to guide the reader into the literature. Table 2 contains a selection of typical palladium(II) complexes of bi- or multi-dentate sulfur or selenium donor ligands, and comments on pertinent aspects of particular complexes. Chelate... 

Multidentate amine ligands react readily with palladium(II) halides to yield chelated products. Crystal structure determinations have been carried out for 1,2-diaminoethane complexes [PdCl2(en)], [Pd(en)2]Cl2 and [Pd(en)2][Pd(S203)2(en)]. A variety of 1,2-diaminoethane, 1,2-diaminocyclohexane and 1,3-diaminocyclohexane complexes have been prepared because their necessarily cis geometry makes them analogous to the antitumour platinum complexes. In contrast to compounds tram-[PdX2L2] these former complexes are claimed to have activity comparable with or greater than that of cisplatin. ... 

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