Characterization and studies of some triethanolamine complexes of transition and representative metals

The ligand triethanolamine, 2,2′, 2″-nitrilotriethanol, forms air-stable, crystalline complexes with the bi- and the trivalent transition and representative metal salts from chromium to zinc. These compounds have not previously been characterized. They have the general formula: M (NTEH3)∗ (NTEHn) Xm where X is Cl− or CH3CO2−, and n is 2,3; m is 1,2 or 3, respectively, depending upon the charge the central metal cation, and on the value of n. Analytical and spectral data indicate that the metal is six coordinate in these compounds when the cation has unfilled 3 d subshells. These compounds are all of the high-spin type. Electronic reflectance and paper-mull spectra support the octahedral, Oh, formulation within the metallic-polyhedron, but an actual overall C2h point group for the entire monomeric group assemblage. The relative i.r. hydroxyl band intensity ratios provide direct evidence that the two axial positions in the monomers are occupied by the more basic nitrogen donor groups, and that the four equatorial positions are occupied by oxygens from the ligands. Conductance data indicate a 1:3 electrolyte in the case of Cr(NTEH3)2Cl3 and Fe(NTEH3)2Cl3; a 1:2 electrolyte in the case of Co(NTEH3)2Cl2 and Ni(NTEH3)2Cl2; and a 1:1 electrolyte in the case of Ni(NTEH3)(NTEH2)OAc, Cu2(NTEH2)2Cl2 and Cu(NTEH3)2Cl2.