DONOR PROPERTIES OF POSITIVELY CHARGED LIGANDS . 5-COORDINATE TRANSITION METAL COMPLEXES CONTAINING A MONOQUATERNIZED TERTIARY DIAMINE

A novel series of five-coordinate transition metal complexes, of the general formula M(L+)(Y)X3, has been prepared with M = Mn(II), Fe(II), Cu(II), Ni(II), Co(II); L+ = N-methyl-1,4-diazabicyclo[2.2.2]octonium cation; Y = H2O, NH3; and X = Cl, Br. These complexes are of the high-spin type and can be assigned a trigonal-bipyramidal stereochemistry with the three X ligands in the equatorial plane. Evidence for this formulation is obtained from electronic and vibrational spectra, magnetic properties, and X-ray powder diffraction patterns. These five-coordinate complexes are unusual in that they contain only σ-bonding monodentate ligands, one of which is positively charged, and thus represent an example of fivecoordination induced and stabilized by electronic factors and lattice energy rather than by the steric requirements of a polydentate ligand. © 1969, American Chemical Society. All rights reserved.