Cd(II) complexes with phthalic acids: solution study and crystal structure of cadmium(II) phthalate hydrate

Abstract

Abstract:The acid-base properties of phthalic acid (H,L) have been determined by simultaneous spectroscopic, potentiometric, and polarographic measurements. Stability constants of the complexes CdHLf, CdL, CdL,'-, C~L;-, C~H,L; and their distribution versus pH were determined at 25OC and ionic strength in 0.1 M NaNO,. The advantages of each method are pointed out in such a way as to describe more precisely the interactions between cadmium and phthalic acid over a wide range of ligand and metal concentrations. The crystal structure of the [CdL] complex has been established by single-crystal X-ray diffraction. Cd (C,H,O,).H,O is orthorhombic, space group Pbca, a = 23.463(5), b = 9.293(2), c = 7.730(1) A, Z = 8, and p = 2.323 g cm-,.The structure was refined to a final R value of 0.054 for 323 1 unique reflections with I > 3u(4. The crystal is a three-dimensional polymeric network in which the Cd atom is seven-coordinated. The first ligand coordinates in a bidentate carboxylate (0,O') mode (Cd-0 = 2.372(5) and 2.445(5) A); a second ligand is part of a seven-membered ring formed with its two carboxylate groups (Cd-0 = 2.317(5) and 2.341(5) A); two other phthalic ligands make one coordination bond (Cd-0 = 2.255(5) and 2.449(5) A) while the seventh bond is a water molecule (Cd-0 = 2.333(6) A).Key words: crystal structure, cadmium complexes, phthalic acid complexes.

Hydrothermal synthesis and structural studies of novel 2-D lanthanide coordination polymers with phthalic acid

“…For 1,2-BDC, the two carboxylate groups are in ortho position, which may impede the formation of higher dimensional networks with the benzene rings, resulting in '' sandwich '' structures when the carboxylate groups coordinate with the metal ions. Compared to reported binary transition metal phthalato complexes, 12 we find that all the carboxyl oxygen atoms of the deprotonated phthalato anions are liable to form coordination bonds in the title complexes. Furthermore, coordination modes for the transition metal phthalato complexes are simpler than those of the lanthanide phthalato complexes due to the large ionic radii and high coordination numbers of lanthanide ions.…”

Bringing a New Flexible Mercaptoacetic Acid Linker to the Design of Coordination Polymers

“…The comparison between the geometric parameters of 1H and 2H shows that the Cd−O (2.240(2) and 2.304(2) Å) and Cd−S (2.686(1) Å) distances in the Cd(II) product are expectedly longer than those in the Zn(II) compound. However, all bond lengths are similar to those found in related derivatives [ 22 , 23 , 24 , 25 , 26 , 27 ]. The p -XBTA 2− moiety acts as a µ 4 -linker and an S 2 ,O 4 -hexadentate ligand ( Figure 2 c).…”

Poly[diaqua(μ4-3-fluorophthalato-κ4 O:O:O′:O′′)cadmium(II)]

“…The Cd-O bond distances are normal (Table 1), with an average value of 2.3031 (18) Å . All other distances and angles are comparable with those in a similar Cd II -phthalate coordination polymer (Vaz et al, 1996).…”

“…As is typical for metal phthalate-type complexes, the two carboxylate groups in (I) are not coplanar with the aromatic ring (Vaz et al, 1996). One of the carboxylate groups makes a dihedral angle of 72.7 (1) , while the other is twisted at an angle of 31.5 (1) .…”