Tris complexes point group

Trisbicyclo[2.1. IJhexabenzene, 150 Tris(ethylenediamine) complexes point group of, 5 Tropylimn cation, 275 synthesis, 146... 

During the study of inorganic chemistry, the structures for a large number of molecules and ions will be encountered. Try to visualize the structures and think of them in terms of their symmetry. In that way, when you see that Pt2+ is found in the complex PtCl42 in an environment described as D4h, you will know immediately what the structure of the complex is. This "shorthand" nomenclature is used to convey precise structural information in an efficient manner. Table 5.1 shows many common structural types for molecules along with the symmetry elements and point groups of those structures. 

The shapes of the three complexes in Figure 7 have important consequences in their use as sensitizers in multi-component assemblies. The tris bpy and tris-phen complexes have three fold symmetry Eh point group) while the bis terpy complex... 

When a species cannot be superimposed on its mirror image the two forms are known as enantiomers or optical isomers. Most examples with coordination compounds have chelating (e.g. bidentate) ligands (see Topic E3 ). Structures 10 and 11 show respectively the delta and lambda isomers of a tris(chelate) complex, with the bidentate ligands each denoted by a simple bond framework. As discussed in Topic C3. optical isomerism is possible only when a species has no improper symmetry elements (reflections or inversion). Structures 10 and 11 have the point group D3, with only C3 and C2 rotation axes. 

What is the point group of the tris(ethylenediamine)cobalt(III) complex ion (Each NH2CH2CH2NH2 group occupies two adjacent positions of the octahedral coordination sphere.)... 

What is the point group of the tris(ethylenediamine)cobalt(III) complex ion (Each NH2CH2CH2NH2 group occupies two adjacent positions of the octahedral coordination sphere.) Consider a molecule with the z axis coinciding with the C axis and the x axis coinciding with one of the C2 axes. Show that the product cr(xy)C2(x) moves a point originally at (x, y, z) to x, —y, z). Therefore, xy)C2 x) = a-(xz). Since C2(x) and a- xy) are symmetry operations, their product must be a symmetry operation. Hence the xz plane is a symmetry plane. The same argument holds for any C2 axis, so the molecule has n cr planes. 

If the same alkyl group occurs more than once as a side chain, this is indicated by the prefixes di-, tri-, tetra-, etc. Side chains are cited in alphabetical order (before insertion of any multiplying prefix). The name of a complex radical (side chain) is considered to begin with the first letter of its complete name. Where names of complex radicals are composed of identical words, priority for citation is given to that radical which contains the lowest-numbered locant at the first cited point of difference in the radical. If two or more side chains are in equivalent positions, the one to be assigned the lowest-numbered locant is that cited first in the name. The complete expression for the side chain may be enclosed in parentheses for clarity or the carbon atoms in side chains may be indicated by primed locants. 

Early attempts to purify the enzyme brought the quick realization that aconitase is easily inactivated (6,7). In the early 1950 s Dickman and Qoutier (8,9) found that inactivated aconitase could be reactivated by incubation with iron and a reduc-tant. From kinetic analyses of the iron and reductant effects on enzyme activity, Morrison argued that both formed Michaelis-Menten complexes wiA the enzyme (10). This refuted the earlier idea that the sole role of the reductant was to maintain iron in a reduced state (9). Of several metal cations tried, only ferrous ion was found to be capable of this reactivation process (8,11). Because of the absolute requirement for iron in activation, the known chelation properties of citrate, and Ogston s 3-point attachment proposal, Speyer and Dickman proposed that the active site iron provides three coordination sites for substrate binding - one for hydroxyl and two for carboxyl groups (12). 

The results published thereafter by Kochi s group are especially interesting from a mechanistic point of view . Indeed, for preparative chemistry the yields are not satisfactory and the reaction is limited to reactive alkenyl bromides such as propenyl and styryl bromides (Table 4). Neumann and Kochi were the first to replace iron(III) chloride by iron(III) acetylacetonate or related complexes such as Fe(dbm)3 (iron tris-dibenzoylmethanato) that are less hygroscopic and easier to handle. 

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