Platinum complexes chelated amines

Chelate complexes of the type [PdX2(diene)] (X = Cl, Br) are readily formed by the dienes hexa-1,5-diene (124), bicyclo 2,2,lJhepta-2,5-diene (1, 7) tricyclo[4,2,2,0]-deca-triene and -diene derivatives (10), cyclo-octa-1,5-diene and dicyclopentadiene, but not dipentene (43). These may be converted to complexes of the types [Pd2X2(dieneOR)2] and [PdCl(dieneOR)-(amine)] (R = alkyl) (43), and their properties indicate that they have similar structures to the platinum complexes (XXXI) and (XXXIII). 

A wide range of multidentate amine ligands coordinate to platinum. The conformational analysis of chelate ring systems by NMR has been reviewed by Hawkins, and platinum complexes are included in this work.959 Amine ligands with sulfur groups can also act as chelates, and this subject has also been reviewed.960... 

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. ... 

Although some palladium a-alkyl complexes formed from additions of amines are stable by virtue of chelation of the aminoalkyl ligand in the product, cr-dkyl platinum complexes lacking chelation are more stable than the palladium analogs. For example,... 

Chelating agents may manifest their antiviral activity by metal sequestration and, as with bacteria and parasites, the natural differences between the host and invading cells may be exploited. Chelating agents with antiviral activity include the thiosemicarbazones, 1,10-phenanthrolines and phosphonoacetates. The latter compounds may act by zinc chelation. Metal complexes with antiviral action are platinum and palladium amines, as well as the antibacterial silver and mercury species. 

Metal complexes as antiprotozoal agents are also known, including rhodium, platinum and ruthenium amines. The antiparasitic action of porphyrins is also related to metal sequestration and conversion to the zinc chelate may be the initial step in activation. 

E. Balint, E. Fazekas, G. Pinter, A. Szollosy, T. Holczbauer, M. Czugler, L. Drahos, T. Kortvelyesi, G. Keglevich, Synthesis and utilization of the bis(>P(0)CH2)amine derivatives obtained by the double Kabachnik-Fields reaction with cyclohexylamine quantum chemical and X-ray study of the related bidentate chelate platinum complexes, Curr. Org. Chem. 16 (2012) 547-554. 

In addition to chelate complexes, the cyclic amine 1,4,7-triazacyclononane will complex to platinum(II) and (IV). The hexacoordinate platinum(IV) complexes are bonded to two molecules of the tridentate ligand, but platinum(II) complexes with the ligand monodentate and bidentate.988 Also the formation of platinum(II) ammine complexes from chloride complexes is a reversible process. The rate constants decrease as the basicity of the leaving amine increases.989... 

A number of platinum(II) complexes have been prepared where the sulfide group is in chelation with an amine. With S(CH2CH2NH2)2, the monodentate S-bonded complex... 

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