Nitrogen Chelates

The Cu(I) oxidation state is also stabilized with respect to Cu(II) in the 2,9-dimethyl-1,10-phenanthroline system [78], Clearly, the factors which affect in vitro and in vivo activity are different, but it would be of interest to reconcile these apparently contradictory results that the most active inducers of strand breakage are not antitumour active, while inhibitors of strand breakage are quite active. The cell penetration and lability of the complex once inside the cell will be of importance besides apparent differences in chemistry. A slower redox cycle is actually more selective, being more toxic, than a faster one. 

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Chiral nitrogen chelates derived from sugars were prepared by Ruffo [48], introducing diimines and diamines functionalities on inexpensive monoses, a-D-glucose and a-D-mannose. 

Table 100 Complexes with Miscellaneous Sulfur-Nitrogen Chelating Ligands... 

Oxygen donors to copper(II) are nearly as frequent in occurrence as nitrogen donors (Table 79). They have a lower tendency to form oxygen chelate ligands, compared to the nitrogen chelates (Section 53.4,9.3), but adequately compensate for this limitation in the occurrence of hydrates and oxygen donors in oxyanions (see Chapter 15.5). 

JL is a ligand such as 8-quinolinolate containing a nitrogen chelated to the tungsten. 

Metal complexes of sulphur-nitrogen chelating ligands. (M. A. Ali and S. E. Livingstone, Coord. Chem. Rev., 1974, 13, 101). 

The Y-lithiation of aUylic amines affords a nitrogen-chelated aUylic lithium species by regioselective deprotonadon. An example is shown in Scheme 36. ... 

Nickel(II) complexes with various sulfur-nitrogen chelating ligands are reported in Table 100. 2-Aminoethanethiol (HL) is the simplest representative sulfur-nitrogen ligand acting as an anionic chelate. It forms two types of nickel(II) complex, namely the bis chelate [N1L2I and the trinuclear Nial Ct (333). Both complexes are square planar. Heterometallic complexes similar to (333), [MCNil W", have been reported with different metals such as M = Cu, Cu", Pd +, and Most of the complexes with 2-aminoethanetbiol have been... 

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