SPIN-CROSSOVER PHENOMENA OF IRON COMPLEXES IN THE MONTMORILLONITE INTERLAYER SPACE

Spin-crossover phenomena of four iron complexes, [Fe(amp)(3)](2+) (amp = 2-(aminomethyl)pyridine), [Fe(acac(2)trien)](+) (H(2)acac(2)trien = is(1-methyl-3-oxobutylidene)triethylenetetramine), [Fe(sal(2)trien)]( +) (H(2)sal(2)trien = N,N'-disalicylidenetriethylenetetramine), and [F e(acpa)(2)](+) (Hacpa = N-(1-acetyl-2-propylidene)-2-pyridylmethylamin e), intercalating into the montmorillonite interlayer space were exami ned by the magnetic susceptibility measurement and Fe-57 Mossbauer spe ctroscopy. Confinement of the complexes in the 2D space brings some di spersion and drop of the spin-crossover temperature in comparison with those for their spin equilibria in solution. Twisting deformation of the complexes was proposed to be responsible for the observed variatio n of the relative stability between high-spin and low-spin species.