The bifunctional chelating agents N,N,N',N'',N''-pentakis(carboxymethyl)-1- [(4-aminophenyl)methyl]-diethylenetriamine and N,N,N',N'',N''-pentakis(carboxymethyl)-1-[(4-aminophenyl)methyl]-4- methyldiethylenetriamine were prepared in six-step syntheses in overall yields of 38% and 31%, respectively. The use of bromoacetate esters in the synthesis allowed large-scale flash chromatographic purification of reaction products. The synthesis of N,N,N',N'',N''-pentakis(carboxymethyl)-1- [(4-aminophenyl)-methyl]-4-methyldiethylenetriamine resulted in a mixture of two diastereomers. Chelation of yttrium-(III) with these bifunctional chelating agents resulted in 1:1 chelates. In the case of N,N,N',N'',N''-pentakis(carboxymethyl)-1-[4- aminophenyl)methyl]diethylenetriamine, two diastereomers were observed upon chelation, as expected. In the case of N,N,N',N'',N''- pentakis(carboxymethyl)-1-[(4-aminophenyl)-methyl]-4- methyldiethylenetriamine, only three of the four anticipated diastereomers were observed.

of the di product is formed in an S^AE)*®1® reaction of the d2 starting material, and the rest (22.4 -11.7 = 10.7%) is formed in an SN(AE)ipeo reaction of dx starting material. So from 66.1% of dx product, 10.7% undergoes an SN-(AE)ip®°reaction, and the rest (66.1 -10.7 = 55.4%) undergoes an SnÍAE)1®1® reaction, or in other words k/kD = 10.7/55.4 = 0.18. From kH/kO and fe/feD, k^/k can be calculated. kH/k is the ratio of the reaction rate of the Sn(AE)*®1® reaction in the undeuterated compound and the rate of the SN(AE)ip®°r eaction.

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