Abstract
Neutral {CpFe(II)(CO)(2)[Sn(II)(Pc(•3-))]} {Cp is cyclopentadienyl (1, 2) or Cp* is pentamethylcyclopentadienyl (3); Pc: phthalocyanine}, {Cp*Fe(II)(CO)(2)[Sn(II)(Nc(•3-))]} (4, Nc: naphthalocyanine), and {CpFe(II)(CO)(2)[Sn(II)(TPP(•3-))]} (5, TPP: tetraphenylporphyrin) complexes in which CpFe(II)(CO)(2) fragments (Cp: Cp or Cp*) are coordinated to Sn(II)(macrocycle(•3-)) have been obtained. The product complexes were obtained at the reaction of charge transfer from CpFe(I)(CO)(2) (Cp: Cp or Cp*) to [Sn(II)(macrocycle(2-))] to form the diamagnetic Fe(II) and paramagnetic radical trianionic macrocycles. As a result, these formally neutral complexes contain S = 1/2 spins delocalized over the macrocycles. This provides alternation of the C-N(imine) or C-C(meso) bonds in the macrocycles, the appearance of new bands in the near-infrared spectra of the complexes, and blue shift of both Soret and Q-bands. The {CpFe(II)(CO)(2)Sn(II)(macrocycle(•3-))} units (Cp: Cp or Cp*, macrocycle: Pc or Nc) form closely packed π-stacking dimers in 1 and 3 or one-dimensional chains in 2 and 4 with effective π-π interaction between the macrocycles. Such packing allows strong antiferromagnetic coupling between S = 1/2 spins. Magnetic interaction can be described well by the Heisenberg model for the isolated dimers in 1 and 3 with exchange interaction J/k (B) = -78 and -85 K, respectively. Magnetic behavior of 2 and 4 is described well by the model that includes contributions from an antiferromagnetically coupled S = 1/2 dimer (J (intra)) and a Heisenberg S = 1/2 chain with alternating antiferromagnetic spin exchange between the neighbors (J (inter)). Compound 2 demonstrates large intradimer interaction of J (intra)/k (B) = -54 K and essentially weaker interdimer exchange interactions of J (inter)/k (B) = -6 K, whereas compound 4 shows strong magnetic coupling of spins within the dimers (J (intra)/k (B) = -170 K) as well as between the dimers (J (inter)/k (B) = -40 K). Compound {CpFe(II)(CO)(2)[Sn(II)(TPP(•3-))]} (5) shows no π-π interactions between the porphyrin macrocycles, and magnetic coupling is weak in this case (Weiss temperature is -5 K). Preparation of a similar complex with indium(III) chloride phthalocyanine yields {CpFe(CO)(2)[In(Pc(2-))]} (6). In this complex, indium(III) atoms are reduced instead of the phthalocyanine macrocycles that explains electron paramagnetic resonance silence of 6 in the 4-295 K range.