Synthesis and characterization of hexadentate cobalt(III) complexes with novel edta-type ligands Part 2. Circular dichroism of the trans(O5O6) and trans(O6) isomers of a cobalt(III) complex of 1,3-propanediamine-N,N′-diacetic-N,N′-di-3-propionic acid

Cobalt(II) complexes with aminopolycarboxylate 1,3-pdta-type ligands: synthesis and characterization of trans(O6)-[Mg(H2O)6][CoII(1,3-pddadp)]·H2O

“…Ba 2 (1,3-pddadp) Á 8H 2 O was prepared by a modification of the method of Radanovi c et al [24]. Chloroacetic acid (48.20 g, 0.51 mol) was dissolved in H 2 O (100 cm 3 ) and cooled in an ice bath.…”

“…(1,3-pdta)] Á 2H 2 O [11] complexes are shown in Figure 2. The corresponding numerical data for these complexes are given in Table 3 (1,3-pddadp)] ) complex of known Xray crystal structure and defined absorption maxima at 612 nm (sh) and 543 nm for the first absorption band and 388 nm for the second absorption band [24,25]; see Figure 3. The presented u.v.-vis.…”

“…In relation to edta these structurally related ligands have changes in the diamine chain (1,3-propanediminetetraacetate ion, 1,3-pdta [3][4][5][6][7][8][9][10][11]) or in the carboxylate arms (ethylenediamine-N,N¢-diacetate-N,N¢-di-3-propionate ion, eddadp [2,[12][13][14][15][16][17][18][19][20][21][22]), but most of them have longer diamine chains as well as longer single or more carboxylate arms (1,3propane-diamine-N,N¢-diacetate-N,N¢-di-3-propionate ion, 1,3-pddadp [23][24][25][26][27][28]). The coordination chemistry of these edta-type ligands is very interesting because they can form hexadentate complexes with rather large metal ions and under their hexadentate coordination more geometrical isomers can be obtained.…”

Kinetics and Mechanism of Interaction between Chromium(III) and Ethylenediaminetetra-3-Propinate in Aqueous Acidic Media

“…All solutions were prepared using bidistilled water. The ethylenediaminetetra-3-propinate was prepared using a previously described procedure [6]. Stock solution of (0.1 mol·dm ) of hexaaquachromium (III) was prepared by dissolving CrCl 3 in bidistilled water and leaving the solution for 48 hours at 45˚C, where upon green color of CrCl 3 changed to blue color of aquachromium(III) [7].…”

“…It is well known that substitution reactions of hexaaquachromium(III) with a variety of ligands proceed by associative [12,[20][21][22] and dissociative [23,24] mechanisms. Swaddle [25,26] and Lincoln [27] have reviewed that the activation parameters and mechanism of octahedral substitution and concluded that an associative mechanism is operative for octahedral cationic complexes of trivalent metal ions except for Co(III) with ionic radii greater than 60 pm, which demand associative character for substitution reaction of [Cr(H 2 O) 6 ] 3+ The associative mechanism is further supported by 1) lowering of enthalpy and large negative entropy for substitution of water by ligand compare to water exchange (for water exchange ∆H* = 109.6 kJ·mol −1 and ∆S* = +12 J·K −1 ·mol −1 [28]); 2) the straight line obtained from plotting of log k 1 with log k 2 [29], (Figure 5) (Where k1 and k 2 are the first order rate constants at different temperature) for the substitution of water in [Cr(H 2 O) 6 ] 3+ by valine [16], glycine [17], serine [18], Aspartic acid [19], L-glutamic acid [21], DL-lysine [21], DL-leucine [22] and EDTP (this work).…”