| Description |
Nickel (II) and cobalt (II) complexes are reported for the first time with the following ligands: propionamide (PA), N-butyramide (NBA), isobutyramide (IBA), trimethylacetamide (TMA), and dipropionamide (DPA),. The size of the amide affects the number of these ligands that coordinate to the central metal ion. With the perchlorate anion, six monoamides or three diamides formed octahedral complexes. Similar results were obtained for the nickel (II) chloride compounds. The nickel (II) nitrates of propionamide, isobutyramide, and N-butyramide are of the form [Ni(L)6] (NO3)2 while the trimethylacetamide complex is [Ni(TMA)4(NO3)2]. The cobalt (II) complex with propionamide has the molecular formula [Co(PA)6][CoC14], whiled the remaining complexes of this salt have only four monoamides or two diamides coordinated to the cationic complex. The cobalt (II) nitrates of proprionamide and N-butlyramide are octahedral with non-coordinating nitrates: [Co(L)6](N03)2. The larger ligands (isobutyramide, trimethylacetamide, and dipropionamide) from complexes with four coordinated monoamides or six coordinated diamides. These are also octahedral. Steric effects appear to be the most likely explanation as to the number of amide an diamide groups that coordinate to the central metal ion. The molecular formulas and configurations of these complexes were determined from the infrared absorption spectra, visible spectra, conductance measurements, and elemental analysis. Many of the diamide complexes were shown to undergo decomposition upon isolation of the solid compounds. Consequently, continuous variation studies were done in acetone solutions with cobalt (II) salts and the following diamides: dipropionamide, di-ispbutyramide, and N-propionylisobutyramide. From these studs it can be seen that complexation does occur in solution. |
