Abstract:
Mononuclear heteroleptic complexes [Fe(tpma)(bimz)](ClO4
)2
(1a), [Fe(tpma)(bimz)](BF4
)2
(1b), [Fe(bpte)(bimz)](ClO4
)2
(2a), and [Fe(bpte)(bimz)](BF4
)2
(2b) (tpma = tris(2-pyridylmethyl)amine,
bpte = S,S0
-bis(2-pyridylmethyl)-1,2-thioethane, bimz = 2,20
-biimidazoline) were prepared by reacting
the corresponding Fe(II) salts with stoichiometric amounts of the ligands. All complexes exhibit
temperature-induced spin crossover (SCO), but the SCO temperature is substantially lower for
complexes 1a and 1b as compared to 2a and 2b, indicating the stronger ligand field afforded by the
N2S2
-coordinating bpte ligand relative to the N4
-coordinating tpma. Our findings suggest that ligands with mixed N/S coordination can be employed to discover new SCO complexes and to tune the
transition temperature of known SCO compounds by substituting for purely N-coordinating ligands.
