{CpFeII(CO)2SnII(Macrocycle?3?)} Radicals with Intrinsic ChargeTransfer from CpFe(CO)2 to Macrocycles (Cp: Cp or Cp*); EffectiveMagnetic Coupling between Radical Trianionic Macrocycles?3?

摘要

Neutral {CpFeII(CO)2[SnII(Pc?3?)]}{Cp iscyclopentadienyl(1,2) or Cp* is pentamethylcyclopentadienyl(3);Pc:phthalocyanine} ,{Cp*FeII(CO)2[SnII(Nc?3?)]}(4, Nc: naphthalocyanine),and {CpFeII(CO)2[SnII(TPP?3?)]} (5, TPP: tetraphenylporphyrin) complexes in which CpFeII(CO)2 fragments (Cp: Cpor Cp*) are coordinated to SnII(macrocycle?3?) have beenobtained. The product complexes were obtained at thereaction of charge transfer from CpFeI(CO)2 (Cp: Cp orCp*) to [SnII(macrocycle2?)] to form the diamagnetic FeII and paramagnetic radical trianionic macrocycles. As a result, theseformally neutral complexes contain S = 1/2 spins delocalized over the macrocycles. This provides alternation of the C?Nimine orC?Cmeso bonds in the macrocycles, the appearance of new bands in the near-infrared spectra of the complexes, and blue shift ofboth Soret and Q-bands. The {CpFeII(CO)2SnII(macrocycle?3?)} units (Cp: Cp or Cp*, macrocycle: Pc or Nc) form closelypacked π-stacking dimers in 1 and 3 or one-dimensional chains in 2 and 4 with effective π?π interaction between themacrocycles. Such packing allows strong antiferromagnetic coupling between S = 1/2 spins. Magnetic interaction can bedescribed well by the Heisenberg model for the isolated dimers in 1 and 3 with exchange interaction J/kB = ?78 and ?85 K,respectively. Magnetic behavior of 2 and 4 is described well by the model that includes contributions from anantiferromagnetically coupled S = 1/2 dimer (Jintra) and a Heisenberg S = 1/2 chain with alternating antiferromagnetic spinexchange between the neighbors (Jinter). Compound 2 demonstrates large intradimer interaction of Jintra/kB = ?54 K andessentially weaker interdimer exchange interactions of Jinter/kB = ?6 K, whereas compound 4 shows strong magnetic coupling ofspins within the dimers (Jintra/kB = ?170 K) as well as between the dimers (Jinter/kB = ?40 K). Compound{CpFeII(CO)2[SnII(TPP?3?)]} (5) shows no π?π interactions between the porphyrin macrocycles, and magnetic couplingis weak in this case (Weiss temperature is ?5 K). Preparation of a similar complex with indium(III) chloride phthalocyanineyields {CpFe(CO)2[In(Pc2?)]} (6). In this complex, indium(III) atoms are reduced instead of the phthalocyanine macrocyclesthat explains electron paramagnetic resonance silence of 6 in the 4?295 K range.