Ligands, deprotonated

With ethylenediamine, high oxidation states become a possibility (Figure 1.57), sometimes involving a deprotonated ligand (see also section 1.12.1) [148],... 

A copper(II) complexes of 5-phenylazo-3-methoxy salicylidene thiosemicarbazone has been shown to have promising growth inhibition activity against P388 lymphocytic leukemia cells sensitive and resistant to adriamycin [196], The complex involves ON coordination of two deprotonated ligands and v(CS) is reported to be unaltered in intensity and position in the complex from its position in the spectrum of the ligand. Inhibition studies with the uncomplexed thiosemicarbazone indicating an important role for the copper(II). 

Various mixed tridentate ligands with P,N,0/S/N donor sets have been explored in Ni11 chemistry. For example, condensation of 2-(diphenylphosphino)aniline with substituted (5-chloro-, 5-nitro, 5-bromo-, 5-methoxy-, and 3-methoxy-) salicylaldehydes yields (253).697 The deprotonated ligand coordinates through its P,N,0 donor set in a square planar geometry with some distortion, which is probably due to the bulk of the phosphine group and to the bite angle of the P,N chelate. 

Figure 7.12 Molecular structure of the asymmetric complex [Ln2(HL)2(H2L)(N03)(py)(H20)] with the three deprotonated ligands resulting in two lanthanide sites with differing chemical...

This equilibrium may be used to define an extraction constant (Kex) in the usual way. It should be noted that under some conditions, especially when larger ions are involved, a second equilibrium involving complexation of a further molecule of (non-deprotonated) ligand may also be present. 

Some other Ni(III) complexes containing saturated macrocyclic ligands are reported to decompose to Ni(II) complexes of oxidized macrocycles in alkaline solution of 9.0 < pH < 11.0. The reaction involves the Ni(III) complex of the deprotonated ligand (119). 

The easy deprotonadon of the charged complexes and the marked stability of the neutral complexes (most of them can be sublimed unchanged) can be ascribed to the formation of a conjugated system involving the whole molecular framework. In the neutral complexes containing such types of deprotonated ligands subnormal magnetic moments have usually been found. 

Other examples of complexes derived from deprotonated ligands are reported in Section 50.5.3.7.i. 

Tridentate Schiff bases containing a peripheral donor atom of low electronegativity (P, As) form high-spin five-coordinate complexes [NiX2L] with the neutral ligands (III Table 9V)2289 and square planar complexes [NiLj with the deprotonated ligands (IV) which are bilegate.2290... 

In (l-methylthymine)silver(I), one half of the silver atoms had linear coordination (N—Ag—N angle of 180°) and were strongly bound to the N atoms of the deprotonated ligands (Ag—N = 208.1 pm). The resulting planar Ag(L)J units (9) were connected by the remaining silver atoms, which were tetrahedrally surrounded with oxygen atoms from two Ag(L)2 units (Ag—0 = 233.3 and 251.2 pm). 

The complexes ML2-nH20 (M = Zn or Cd H2L = diformyl- or diacetyl-hydrazine) have also been synthesized, and are dimeric or polymeric with the quadridentate hydrazine acting as a bridging ligand.158 159 A normal coordinate analysis of diformylhydrazine and its zinc complex with deprotonated ligand has been reported.160... 

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