ChemInform Abstract: Metal Ion Size Selectivity of 1-Thia-4,7-diazacyclononane (9-aneN2S), and Other Tridentate Macrocycles. A Study by Molecular Mechanics Calculation, Structure Determination, and Formation Constant Determination of Complexes of 9-aneN2S.
Abstract
Several aspects of the coordination chemistry of the tridentate cyclononane type macrocycles (I) and (II) are examined using molecular mechanics calculations, crystallography and formation constant determinations.
ChemInform Abstract
Several aspects of the coordination chemistry of the tridentate cyclononane type macrocycles (I) and (II) are examined using molecular mechanics calculations, crystallography and formation constant determinations. The molecular mechanics calculations show that small metal ions coordinate best to these ligands, such that metal ions with a covalent radius of 1.25 Å fit best into (IIa) and 1.40 Å fit best into (Ib). For mixed donor members of the series such as (Ia) the disparity in metal-ligand bond length between the M-N and M-S bond lengths leads to a much higher strain situation than expected from the strain energies of (Ib) and (IIa) complexes. The formation constants of (Ia) with Ni, Zn, Cd, Co, Fe, and Pb and the crystal structure of the complex (III) (space group P21/n, Z=4)are reported.
