Hydroxyethyl phosphate forms a monodentate complex with [(tren)Co(OH2)2]3+ whereas it forms a bidentate complex with [(trpn)Co(OH2)2]3+ (tren = tris(2-aminoethyl)amine; trpn = tris(3-aminopropyl)amine). The monodentate phosphate hydrolyzes more rapidly (k = 2 X 10(-5) s-1 at pH 6.0, 60-degrees-C) than the bidentate phosphate. Although the chelated phosphate is highly resistant to hydrolysis, it is rapidly hydrolyzed by additional [(trpn)Co(OH2)2]3+ (k = 1 X 10(-2) M-1 s-1 at pH 6.0, 25-degrees-C).