Indium , inert complexes

The stability of trihydride complex (171) has been fonnd to be a remarkable featnre. Complex (171) is stable under inert atmosphere up to 115 °C in the sohd state and in toluene solution at room temperatnre for months. It was observed that when the toluene solntion was heated at 100 °C, no decomposition occurred until indium(O) traces appeared. In the presence of catalytic amount of indium(0), complex (171) decomposed entirely in a few minutes, freeing the free carbene, IMes (equation 24). 

The electrochemical procedure for the synthesis of the complex was similar to those described by Tuck [559]. The cell was a 100-cm3 tail-form beaker fitted with a rubber bung through which the electrochemical leads enter the cell. The indium anode was suspended from a platinum wire and the cathode was a platinum wire. [(pySe)2] (0.31 g) was dissolved in acetonitrile and a small amount of tetraethylammonium perchlorate was added to the solution as a current carrier. An applied voltage of 10 V produced a current of 15 mA. During the electrolysis nitrogen gas was bubbled through the solution to provide an inert atmosphere and also to stir the solution phase. After 1 hr of reaction 70 mg of metal had been dissolved from the anode (Ey = 1.1). 

DOTA is of particular interest as a BFC for radiolabeling of small BMs with yttrium and lanthanide isotopes. The macrocyclic framework is well organized so that it forms yttrium and indium complexes with high thermodynamic stability and kinetic inertness. The pXa values of the carboxylic groups are in the range 2-5. Lower pKa values result in less competition from protons, high stability of the metal complex, and minimum acid-assisted demetallation, even... 

Coupled techniques have increased in popularity in recent years. Electrochemical techniques can be coupled to another characterization method to provide unique information. Many electrochemical techniques lend themselves well to coupling with other electrochemical or nonelectrochemical techniques. With these methods, cell design is often complex to allow simultaneous execution of both techniques. For example, optically transparent indium tin oxide is used as the working electrode with an optically transparent mesh electrode to allow for simultaneous electrochemical conversion and electronic absorption spectroscopy. For some techniques the sample is electrolyzed and then transferred under inert atmosphere for analysis. 

The kinetics in the basic media are summarised in the table. Since the rate is not affected by the buffer under due conditions, the reaction mechanism seems to involve essentially that of hydroxo complexes except for thallium, and the attack of hydroxide ions upon the complex appears to play an important role. The fact that the rate of the indium complex is proportional to the square of the hydroxide ion concentration tells that indium is the most inert among the three. Such an inertness of indium complexes may be reflected in the small value of its apparent dissociation constant of the coordinated water molecule, K. ... 

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