Palladium complexes nitrogen donors

The inclusion of the nitrogen donor atom in an aromatic heterocycle allows the possibility of -bonding with the metal centre, giving these ligands some similarities to tertiary phosphines. Thus pyridyl and bipyridyl ligands stabilize organometallic complexes of palladium (see companion volume).2 ... 

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 zero-valent palladium complex Pd(nbd)(ma), nbd = norbomadiene, ma = maleic anhydride, is a useful precursor to novel Pd° complexes with nitrogen a-donor ligands. In THF, pyridine, diethyl amine, aniline, and even NH3 displaced the nbd ligand to form E2Pd(ma) complexes. ... 

Fujita reported a wide range of systems formed by the self-assembly of several nitrogen-donor ligands and palladium and platinum centers.In the assembly of some of these systems, the ternplating properties of anions play an important role. When the square planar complex [Pd(en)2(N03)2] is reacted with l,3,5-rm(4-pyridyl-methyl)benzene in the presence of anionic species having a hydrophobic moiety (such as 4-methoxyphenylacetate), the nearly quantitative formation of the cage structure 9 is observed (see Fig. 3). In the absence of the anionic/ hydrophobic species, this reaction gives rise to a considerable amount of polymeric material. Similarly, the... 

Palladium will form complexes with the great majority of organic compounds containing nitrogen donor atoms. Some representative Pd-N complexes containing mono- and bidentate nitrogen ligands are summarized in Table 5. 

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