The synthesis of the tridentate ligand bis(2-pyridylmethyl)amine by reaction of 2-chloromethylpyridine and excess 2-aminomethylpyridine is described, and the proton dissociation constants are reported. The coordination tendencies have been studied potentiometrically (at 25°and µ = 0.10 in KNOs) with Cu(II), Co(II), Ni(II), Zn(II), Cd(II), Mn(II), and Ag(I).Chelation was observed and the corresponding stepwise formation constants and Gibbs free energies are reported. These results are compared with the coordination tendencies of the analogous aliphatic amine, diethylenetriamine. Geometrical considerations for bis (2-pyridylmethyl )amine coordination are discussed. The proton dissociation constants of bis(3-pyridylmethyl)amine are also reported.

The synthesis of di-(2 -pyridylmethyl) amine, Z-aminoethyl-(2-pyridyimethyl) amine, di-(2-2'-pyridylethyl) amine, 3-aminopropyl-(2-2'-pyridylethyl) amine, 2-2'-pyridylethyl-(2-pyridylmethyl) amine. and 3-aminopropyl-(2-pyridylmethy1)amine is described. Their infrared and n.m.r. spectral characteristics are described, and their trihydrochlorides and dipicrates have been prepared. The three proton dissociation constants have been rigorously determined in each case by potentiometric titration at 25" and p 0.1 0 in potassium nitrate.ALTHOUGH the synthesis of a number of 2-pyridyl amines and polyamines has been de~cribed,l-~ several new polyamines were required for a planned long-range study of the role of x-bonding4p5 during chelation reactions. These amines, which must satisfy rigid molecular-structure requirements, comprise pairs containing one and two 2-pyridyl groups, respectively. The compounds reported here include di(2-pyridyl-methy1)amine (I), 3-aminopropyl-(2-2'-pyridylethyl)amine (IV), 2-2'pyridylethyl-(2-pyridylmethyl)amine (V) , and 3-aminopropyl-(2-pyridylmethyl)amine (VI) .Although di-(2-2'-pyridylethyl)amine (111) and 2-aminoethyl-(2-pyridylmethyl)amine (11) have been r e p~r t e d ,~,~ they have been synthesized here by different routes, which are reported together with spectra, dissociation constants, derivatives, and other new data.

Synthesis of 2,2/-iminodimethylene dipyridine has been accomplished in good yield by reaction of 2-chloromethyl pyridine with excess 2-aminomethyl pyridine. Stepwise

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