Ligand isomers

Should a ligand exist in different isomeric forms then of course the corresponding complexes will also be isomers, often described as ligand isomers . In [CoCl(en)2(NH2C6H4Me)]Cl2, for instance, the toluidine may be of the o-, m- or p- form. 

J. A. (2005) Isocoumarins as estrogen receptor beta selective ligands isomers of isoflavone phytoestrogens and their metabolites. Bioorg Med Chem 13, 6529-6542. 

The syntheses presented here are examples of two types of "ligand isomers (1) Nitrito complexes, [Ni 2-[(methylamino)-methyl]pyridine 2(ONO)2], and [Ni 2-[(methylamino)methyl]-piperidine)2(ONO)2] (2) Chelating nitrite groups, [Co(2,4,6-trimethylpyridine iV-oxide NCh ], [Co(2,6-dimethylpyridine iV-oxide) 2 (NO 2)2], and [Co(4-methylquinoline iV-oxide)2(N02)2]. 

The interaction of the chiral quaterpyridine 75, bearing fused chiral groups in the 5,6- and 5", 6" -positions, with copper(I) has been investigated. The respective ligand isomers were demonstrated to form structurally characterised P or M dinuclear double helicates in approximately 99% diasteromeric excess upon coordination to the above ion. ... 

Terminal internal alkyl ligand isomers Isomer ratio... 

The stereochemistry at the carbon bonded to W was investigated using the threo-ligand isomer of (OC)jW—CHD-CHDPh and was found to proceed with retention of stereochemistry at the a carbon, as shown by... 

The isomer possibilities in DOTA derivatives can increase dramatically. For example, introducing a chiral center by substitution at Ca, of the acetate arms of DOTA can gives rise to six ligand isomers defined by the absolute configuration at the carbon (SSSS), RSSS (SRRR), and the achiral... 

We need to make a few comments about the information in this table before discussing the significance of the data. Note first that the symbols for the compounds use M for the central metal and As and B s for the various ligands. Ihe numbers in parentheses for each isomer refer to the relative positions of the B ligands. Isomers are... 

Such a conversion of the allyl ligand from a one-electron to a three-electron donor coordination results from the generation of a vacant coordination site upon the initial photodissociation of a carbonyl ligand. This intermediate Mn( -C3Hs)(CO)4then becomes coordinately saturated again as the allyl ligand isomer-izes from to... 

The complexes of isomeric l%ands are known as ligand isomers. 

Figure 7 (a) 1,3-diaminopropane and (b) 1,2-diaminopropane ligand isomer complexes. 

In the case of certain mixed ligand complexes, the total elemental composition due to the co-ligands becomes the same. These type of ligand isomers are known as co-ligand isomers. 

Generally, a pair of co-ligand isomers results due to an intramolecular nucleophilic addition reaction in coordinated ligands. One of the isomers is an ordinary complex, while the other isomer formed upon the above-mentioned reaction is a chelate. 

An illustration of co-ligand isomerism [1] in ortahedral complexes is provided by a5-[Co(en)2(NH2CH2CN)Cl] which converts into its chelate form of the co-ligand isomer [Co(en)(NH2CH2C(NH2)=NCH2CH2NH2) Cl] in nearly neutral or basic solution, as shown in F pre 8. 

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