Ligand structures complexes

The bonding in the mononuclear metal complexes is considered to involve the two nitrogen atoms of the ligand structure, giving the familiar... 

Frensch and Vdgtle have recently appended three crown ether units to the cyclo-triveratrylene unit . Note that Hyatt had previously prepared the open-chained relatives of this structure (see Sect. 7.3 and Eq. 7.6). Whereas Hyatt prepared the cyclo-triveratrylene skeleton and then appended polyethyleneoxy arms to it, Frensch and Vogtle conducted the condensation reaction (formaldehyde/HCl) on the preformed benzocrown. Thus benzo-15-crown-5 was converted into the corresponding tris-crown (IS) (mp 203.5—205.5°) in 4% yield. The yield was somewhat higher for the condensation of benzo-18-crown-6, but in both cases, yield ranges were observed. These species formed 1 3 (ligand/salt) complexes with sodium and potassium ions. 

Bidentate dithiolate ligands afford complexes like Au(S2CNR2) (R = Et, Pr, Bu) and Au(S2PR2) (R = Pr), which have dimeric structures based on 8-membered rings with linear S—Au—S coordination and short Au-Au distances. These in turn are associated into chains (Figure 4.16) (Au-Au c. 3.0-3.4 A) [99],... 

If structural information of the protein target is available, e.g., a crystal structure, in silico screening of huge virtual compound libraries can be conducted by the use of docking simulations. Based on identified primary hits, structural variations of the ligand can be evaluated by computational modeling of the ligand-protein complex. 

With Hg2 bidentate nitrogen ligands form complexes that have chain structures. For example, 1,4-diazine III forms a complex [Hg2(C4H4N2XN03)2] (IV) that has Hg—Hg units joined in infinite chains, with the [N03] groups between the chains . ... 

Ahn et al. [20] reported the synthesis of homochiral bis(oxazolinyl)-biferrocene ligands (structure 11 in Scheme 7), which also have both planar and central chirality. With these complexes, 2-(phenyl)cyclopropane carboxy-lates were obtained in up to 99% ee and a trans/cis ratio of 88/12. 

Zhang et al. [49] prepared a chiral ruthenium complex coordinated by a pyridine-bis(imine) ligand (structure 43 in Scheme 21). 

Figure 13.3 Potential pharmacophore points can be generated with MOE s site detection algorithm. The white and red dots are the antomatically generated site points, and the ligand structure comes from the X-ray structure of the complex. See color plate.

The crystal structures of monomeric ligands such as GH and EPO in complex with their respective receptors show that these hormones are bivalent and one ligand binds simultaneously to two receptor molecules to form a 1 2 (ligand receptor) complex. Receptor dimerization is further stabilized by additional receptor-receptor interactions. 

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