SYNTHESIS, CRYSTAL-STRUCTURES AND MAGNETIC-PROPERTIES OF SALTS CONTAINING BIS[HYDROTRIS(3,5-DIMETHYL-1-PYRAZOLYL)BORATE]IRON(III)

The salts [Fe(C15H22N6B)(2)][PF6], [Fe(C15H22N6B)(2)][TCNQ].THF and [Fe(C15H22N6B)(2)][FeBr4] have been prepared and the first two subjected to X-ray diffraction studies. In [Fe(C15H22N6B)(2)][PF6] the coordination geometry around the Fe centre is almost perfectly octahedral, with the Fe-N bond distances in the range 1.960(3)-1.970(3) Angstrom, which are typical distances for low spin iron(III) complexes. In [Fe(C15H22N6B)(2)][TCNQ].THF the Fe-N bond lengths lie in the range 1.980(3)-1.949(2) Angstrom and there is essentially octahedral symmetry around the metal centre. In the case of [Fe(C15H22N6B)(2)][TCNQ].THF the [TCNQ](-) anions lie in rows perpendicular to the crystallographic be-plane, these rows being separated by parallel rows of [Fe(C15H22N6B)(2)] cations. The solid state magnetic susceptibility data for these compounds obey the Curie law (chi(M) = C/T) in the temperature range 6-300 K with mu(eff) = 1.65, 2.55 and 5.39 mu(B) for the three complexes respectively. None of these salts showed any evidence of short-range spin-spin interactions at low temperature.