Contribution a l'etude des tetraoxalatolanthanidates III

Abstract Guanidinium tetra-oxalatolanthanidates III of general formula (CN 3 H 6 ) 5 M(C 2 O 4 ) 4 , nH 2 O have been prepared in highly cristalline solide state (M = Nd, Ho, Er, Tm et Sc, Y). Formation constants of corresponding ionic species in aqueous solution M(C 2 O 4 ) 4 5− (M = Ho et Er) were determined by spectrometric investigation using M(C 2 O 4 ) 4 5− - Y 4− system with formation of a mixed complex M C 2 O 4 Y 3− (Y = ethylenediaminetetracetate ion): log β 4 Ho = 16,8±0,2 and β 4 Er = 16,9±0,3 at an ionic strength of 2.5.