Platinum complexes cyclic amines

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... 

We certainly do not intend these rules to restrict future research, but only to encompass a large amount of past experience with platinum(II) complexes. Obviously exceptions will, and have already, occurred. For example, the high activity of bidentate leaving groups such as oxalate and malo-nate (see structures of Fig. 4) first synthesized by M. Cleare and J. Hoe-schele in this laboratory are not encompassed nor is the effect of cyclic amines, developed by Tobe, which decrease the solubility of the complexes, but markedly enhance the antitumor activity. Here, studies of the rela-... 

Resolution of lj-cyclononadiene. Cope et al. examined the resolution of the cyclic allene 1,2-cyclononadiene (1) by way of the diastereomeric platinum complex containing this amine (compare resolution of cycloalkenes (2, 272-273)). A... 

A phenyl-substituted cyclic silyl enolate is synthesized from 1,1-dimethylsilacyclobutane and benzoyl chloride in the presence of a stoichiometric amount of triethylamine and a catalytic amount of PdCl2(PhCN)2 (eq 8). In the case of aliphatic acid chlorides, the use of diisopropylamine instead of triethylamine gives better results. A platinum complex, Pt(CH2=CH2)(PPh3)2, also mediates the reaction although its performance is inferior to that of palladium complexes. Acid anhydrides or combinations of organic halides and carbon monoxide are alternatives to acid chlorides. In the case of acid anhydrides, the amine is not necessary for the reaction. 

Scheme 32 Synthesis of cyclic platinum complexes (67) from bis(phosphinoxidomethyl) amines.

Platinum compounds yield various kinds of carbene complexes [118-137]. For example, if isocyanate platinum compounds react with alcohols or amines, the carbon of the isocyanate bonds to the hetero atom to afford the reactive CXY (X and Y are hetero atoms) group, and the carbene complex yields as shown in eqs. (21.44) [119,127] and (21.45) [120]. On the other hand, as shown in eq. (21.46) [121], the platinum carbene complexes are also obtained by the reaction of cyclic XYC = CXY with platinum compounds on heating for a long time. In these carbene complexes, the cw-isomer is more stable than the /ra/75-isomer as shown in eq. (21.47), the rra/j5-isomers being isomerized to the m-isomer at around 200 C [125]. The Pt-C bond length of these carbene eomplexes is about 2.00 A slightly shorter than 2.16 A, the sum of the covalent radii of the Pt-C bond (Pt= 1.39 A, C = 0.77A). 

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