multidentateligandexchangekinetics:reactionsofaminocarboxylato-ferrate(ⅲ)complexeswith4-(2-pyridylazo)resorcinol

thekineticsandmechanismofligandsubstitutionreactionsofnitnlotriacetatoiron(ⅲ),(fe(nta)],andn-(2-hydroxycthyl)-ethylencdiaminetriacetatoiron(ⅲ),[fe(hedta)],complexeswith4-(2-pyridylazo)resorcinol(par)hasbeeninvestigatedatph=9.0±0.02,i=0.1mol·l-1(naclo4,andtemp.=25±0.1℃and30±0.1℃respectively.thereactionhasbeenstudiedspectrophotometricallyat496nm.(λmaxoffe(par)2.inbothreactionsthefinalproductwas[fe(par)2]-.thevaluesofsecondorderrateconstantsforntaandhedtaexchangereactionsare(10.0±0.8)×1011·mol-1·s-1and(2.7±0.1)×10-1·mol-1·s-1respectively.thereactionsofntaandhedtaexchangewerestudiedinthephrange6-9.5and7-10.85respectively.therateofreactonof[fe(nta)]withhpar-firstincreaseswithphandthenlevelsoff.however,inthecaseof[fe(hedta)]reaction,therateincreasesmonotonicallywithincreaseofphinthespecifiedrange.