Ligands alike

The different coordination behaviour of F- and 0-ligands in the [P03F] ion becomes evident in the interesting structural isomery of (NH4)2P03F H2O (26) and (NH4)2S03 H2O (28) also, the stmctural parameters of which are very much alike -the part of the F-atom in the fluorophosphate being played by the lone electron pair in the sulfite ion. 

Alike metallocomplex anion-radicals, cation-radicals of odd-electron structure exhibit enforced reactivity. Thus, the 17-electron cyclopentadienyl dicarbonyl cobalt cation-radical [CoCp(CO)2] undergoes an unusual organometallic chemical reaction with the neutral parent complex. The reaction leads to [Co2Cp2(CO)4]. This dimeric cation-radical contains a metal-metal bond unsupported by bridging ligands. The Co—Co bond happens to be robust and persists in all further transformations of the binuclear cation-radical (Nafady et al. 2006). 

Robert Plane I would like to comment on the photochemistry of these complexes, particularly the chromium which I think are well chosen for at least two of Dr. Gray s reasons. First, in the case of chromium, unlike cobalt, the charge transfer band is well separated, so that one can study the d-d transitions, at least in certain systems where one has six ligands all alike, and there is no Jahn-Teller splitting, and one has a fairly good idea as to the assignment of bands. 

Given the same coordination polyhedron, diustereoisomerism can arise when the ligands are noi all alike as with the tis and Irani37 isomers of tctraamminedichloro-chromium(IU), diammincdichlcrop]atinum(ll), and bis(2-aminoe hancthtolato)nickcl(ll) (Examples 1-6). 

This section is actually devoted to the description of rhenium alkoxides, as the technetium ones are rarely studied. The latter are reviewed in a short appendix at the end. The chemistry ofrhenium in lower oxidation states is much alike that of ruthenium and therefore even for rhenium, the lower oxidation state complexes with jt-acceptor ligands are described in this chapter. 

We have indicated in the previous section that some apparently alike ligands are, in fact, not equivalent towards enzymes or in their NMR signals. How does one... 

Although the spectra are alike, the spectral intensity depends upon pH indicating the extent of the bound Nd3+ ion, and this may be useful in the determination of pK s of the protein ligands at the binding site [18]. 

The chemist s intuition is that the eclipsed and staggered polymers can t be very different—at least, not until the ligands start bumping into each other, and for such steric effects there can be, in turn, much further intuition. The band structures may look different, since one polymer has one, the other two basic electronic units in the cell. Chemically, however, they should be similar, and we can see this by returning from reciprocal space to real space. Figure 36, which compares the DOS of the staggered and eclipsed polymers, shows just how alike they are in their distribution of levels. 

While the chemical structures and biological properties of steroids have fascinated chemists and biologists alike for many decades, it is only recently that their receptors have been studied [1,5]. This section will give an overview of the structural biology of steroid receptor ligand complexes focusing on the role of the ligand. 

Apart from necessities of efficient coupling of different metal-catalyzed biochemical pathways, e.g. in photosynthesis, there is highly positive correlation among most of these elements yet, holding for abundances of metals and non-metals in various plants alike (also cp. Fig. 1.3). Apart from this, biochemically relevant ligands will control resorption, retention and transport of metals according to Eqs. 2.1 0,2.11 (below, section 2.2.5) all the way from rhizosphere upward to... 

Overall, this book provides a broad overview of both many areas in which ligands hold sway and the means by which they accomplish this. 1 am certain it will serve as a great resource for students and practitioners in the field alike. 

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