Paramagnetic ellipsoids and π bonding in dithiocyanatotetrapyridine-cobalt(II) and -iron(II)

Abstract

Average and principal susceptibilities of [Co(py)₄(NCS)₂] and [Fe(py)₄(NCS)₂] in the temperature range 80–300 K are reported. They have been fitted to the low-symmetry model described in the preceding paper, virtually perfect agreement being obtained between all three observed and calculated crystal susceptibilities for each molecule. The magnetic properties depend predominantly on π bonding, parameter values of which compare well between the two complexes and with otherwise established chemical-bonding concepts. In particular, pyridine is involved in a definite, but small, π-donating role to the metal atoms. The orientations of the molecular magnetic ellipsoids bear no simple relation to the approximate structural symmetry in these molecules.