SYNTHESIS AND CHARACTERIZATION OF A SERIES OF TRIPODAL TRANSITION-METAL COMPLEXES WITH THE SCHIFF-BASE OF 2,2',2''-TRIAMINOETHYLAMINE AND 2-PYRIDINECARBOXALDEHYDE N-OXIDE - CRYSTAL-STRUCTURES OF HEPTACOORDINATE MANGANESE(II) AND COBALT(II) COMPLEXES OF A 7-COORDINATE LIGAND

A series of tripodal transition metal complexes with the condensation product of 2,2',2''-triaminoethylamine (tren) and 2-pyridinecarboxaldehyde N-oxide (pyo) as the ligand have been synthesized and spectroscopically characterized. The crystal structures of [Mn(pyo3tren)](PF6)2.C2H5OH (1) and [CO(pyo3tren)](PF6)2.CH3CN (2) have been determined. Both 1 and 2 crystallize in the cubic space group P2(1)3 with four formula units. Crystal data: 1, a = 15.220(2) angstrom, final R = 0.045; 2, a = 15.069(2) angstrom, final R = 0.054. The X-my structures of 1 and 2 indicate both complex ions have a heptacoordinate metal center with a coordination polyhedron of the monocapped trigonal antiprism owning C3 symmetry. [Ni(pyopyoOHtren)](PF6)2.H2O (3) is a hexacoordinate tripodal complex with three inequivalent arms, which had been confirmed by X-ray diffraction. [Cu(pyotren)](PF6)2 (4), the possible hydrolysis product of [CU(pyo3tren)](PF6)2, is a pentacoordinate copper(II) complex with the configuration of a trigonal bipyramid.