The crystal structure of the title compound, [Fe((C5H4N)3N)2] (ClO4)2, has been determined by single-crystal X-ray diffraction at 295 K and refined by least squares to a residual of 0.059 (1995 'observed' reflections). Crystals are monoclinic, P21/a, a 12.815(4), b 17.503(7), c 8.318(3) Ǻ, β 121.38(3)°, Z 2. The complex cation lies with the metal atom on a centre of symmetry, the metal being six-coordinate, so that only one of the tridentate ligands is crystallographically independent. The geometry about the metal atom deviates only trivially from octahedral, <N-Fe-N> within the one ligand being 88.1°. <Fe-N> is 1.982 Ǻ.

The crystal structure of the title compound, [Co((C5H4N)3N)2] (ClO4)2, has been determined by single-crystal X-ray diffraction at 295(1) K, i.e. in its pseudo-'high-spin' form, and refined by least squares to a residual of 0.061 for 4639 'observed' reflections. Crystals are monoclinic, P21/a, a 12.811(7), b 17.644(7), c 8.375(4) Ǻ, β 120.15(3)°, Z 2. Whereas in the iron(II) ('low-spin') analogue, the metal atom coordination geometry deviates only trivially from octahedral (<Fe-N> 1.982 Ǻ, <N-Fe-N> within the one ligand 88.1°), in the present compound Co-N ranges from 2.100(2) to 2.152(2) Ǻ and the intraligand N-Co-N angles range from 84.86(7) to 86.09(8)°.