Ligand properties structural analysis

The ylides and imides are present as monomers, and the bismuth center adopts a distorted tetrahedral geometry. In contrast, the structural properties of the bismuth oxides vary widely depending on the aryl ligands attached to the bismuth center the oxides exist as hydrates, dimers, or polymers in solution and in the solid state. X-ray structural analysis of an oxide dimer revealed that the bismuth center has a distorted, trigonal bipyramidal geometry with the two oxygen atoms at the apical and equatorial positions [47, 48]. 

Attenuated Total Reflectance FTIR (ATR-FTIRf) is a method that has been applied by a number of workers for the study of protein conformation. ATR has been used for monitoring adsorption of proteins or blood components to sur ces (1,2), and for the structural analysis of proteins dried onto an IRE (thin film) (3,4). It has also been used for exploring the effects of solution conditions on the structure of proteins irreversibly adsorbed to an IRE (5,6,7), and has been shown to be usefel for studying the secondary structure and ligand binding properties of membrane proteins (8,9). 

Hypercoordinate silicon complexes with tetradentate (O, N, N, 0)-chelating ligands of the salen type are expected to exhibit unusual chemical and physical properties because of the higher coordination number of the silicon atom [1,2]. Therefore, several attempts were made to synthesize such compounds [2, 3]. Starting from easily available silicon compounds such as SiCU or other chlorosilanes, conversion with salen type ligands mostly yielded complexes with a hexacoordinate [2, 3] and, in some cases, pentacoordinate silicon atom [4]. Unfortunately, there are only a few examples where the coordination geometry has been confirmed by X-ray structure analysis [2, 4]. 

Dinuclear complexes were obtained by reacting some binary copper(I) and silver(I) homoleptic pyrazolate complexes with neutral ligands. The trimeric [Cu(dmpz)]3 (23) readily reacted with phen or RNC (R = cyclohexyl) to give the doubly bridged species [(phen)Cu(/i-dmpz)2Cu(phen)], 32, (49) or [(RNC)Cu(/t-dmpz)2Cu(RNC)], 33 (50). The dimeric nature of 32 was argued from its spectroscopic and chemical properties, while 33 was characterized by an X-ray crystal structure analysis (50). 

The purpose of an RNA footprinting experiment is to predict the structure of the RNA and/or to identify the binding site(s) for proteins or ligands. The experimental approach for the structural analysis of RNA, or RNA-protein to complexes, utilises a number of different chemicals and ribonucleases which react with nucleotides in certain structural conformations of the RNA. The properties required of the chemicals and ribonucleases used for probing of the RNA structure are not necessarily the same as the properties required for probing of an RNA-protein complex (Fig. 4.6). 

The spectroscopic properties and structure of [Cu(74)(OH2) ] n = 0, 2 [Fig. 2ij) with n = 0], based on an MM-AOM analysis (202, 203) have been reported (99). The computed structure of the ligand part of the molecule agrees well with the crystal-structural analysis of the metal-free ligand, which is available as the free base and in the diprotonated form (99, 181, 182). There are two isomers with respect to the conformation of the ethylene bridges. That in Fig. 2 f) is the more stable stmcmre of the complex, those in Fig. 3 are the... 

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