THs complex

Ph3SnRe(C0) s(l, 10-phenanthroline) (2, 56) and related canplexes can be formulated as having a M-M or M -M single bond. Table IV summarizes the known photoprocesses for such complexes. The lowest excited state in th complexes has been identified as arising from a (M-M)o - tr phen charge transfer transition (2, 55.> 56). Importantly, the orbital of termination of the... 

Binding of Cl- to an aryl iodide may well involve sp d hybridization at iodine to accommodate the ninth electron, but the involvement of a d-oibital in bonding at sulfur is more controversial. Recently it was discovered that even first row elements can form Cl- complexes the evidence indicates that th complexes utilize three-electron bonds, not d-orbitals. Best explored are templates for radical relay chlorination using nitrogen atoms. 

Figure 9. Cumulative formation constants of monomeric Th complexes plotted against their ligand numbers. All the data are for 1 = 0 unless otherwise indicated.

Fia. 21. if . of th complex bands of iodine complexes as a function of the relative basicity (Table 10). 

The Th complexes with organic reagents have been applied in determinations of fluoride in waters [57] and in organic compounds [4,56]. The Alizarin S method has been automated [55]. The aluminium complex with Xylenol Orange has been used for determining fluorine in phosphates [59]. Fluorine was determined in dental preparations with the use of methylsalicylic acid [43]. 

Fluoride, oxalate, phosphate, and (to a lesser degree) sulphate interfere. In a 0.01 M sulphate solution, the absorbance of the Th complex with Thoron I reduces to 60%. 

Table VIII-6 Equihbrium constants for formation of aqueous Th" complexes with F".

The study has been made in a self-medium , where the ionic medium cation consists of Th". The experiments, potentiometric titrations have been made in test solutions of varying total concentration of protons, Htot, in a -logio[H ] range where the value of is less than 0.1. Hence, the free metal ion concentration is approximately equal to Thtot and it is straightforward to make the necessary corrections for the amount of hydroxide complexes formed. From experiments of this type it is only possible to determine the sum of the concentrations of Th complexes that contain a given number of hydroxide ions (one and two in this study) it is not possible to determine the nuclear-ity of the complexes without additional information. The experimental data obtained refers to reactions of the type... 

The amount of radionuclide that is adsorbed on the walls of the container dep ds on the concentration, on the chemical state of the radionuclide and on the nature of the container material. Figure 9.1 shows the variation of the adsorption of thorium on the walls of glass and polyethylene containers as a function of conc tradon and pH. In case (a) the sorption time is that of pipetting (of an aqueous Th-complex), in case (b) it is that for equilibrium. The variation of adsorption with pH reflects the adsorption of various hydrolytic species formed by thorium as the pH is increased. Curve (a) shows that sorption can be neglected at concentrations > lO" M in this system. 

Methyl-substituted thiophenes bind more strongly to transition metals than the unsubstituted ligand, as illustrated by ligand-exchange reactions of CpRu(77 -Th) complexes. The equilibrium constant measured by NMR increases by a factor of about 6 for each methyl group added on the thiophene " benzene, BT, and DBT also displace T. These observations can be related to the inhibition effect of benzene and other aromatic hydrocarbons on FIDS of BT over solid catalysts, ascribed to a stronger binding of arenes on metal sulfide surfaces as compared to common sulfur... 

By means of the above method the Th complex composition with a number of aminopolycarboxylic acids was studies uranyldiacetic, nitrilotriacetic, cyclopentane-, cyclobutane- diaminecyclohexanetetraacetic acids. The results closely agree with those obtained by other methods (7),... 

The interaction of 7MeLi with ThCl in the presence of tmeda provides the seven coordinate Th complex [Li(tmeda)13[ThMey].tmeda which although apparently coordinatively saturated is reactive. 

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