Coordination Complexes of Pentamethylcyclopentadienyl Iridium(III) Diiodide with Tin(II) Phthalocyanine and Pentamethylcyclopentadienyl Iridium(II) Halide with Fullerene C60– Anions

Abstract

Synthetic approaches to iridium complexes of metal phthalocyanines (Pc) and fullerene anions have been developed to give three types of complexes. The compound{(Cp*IrIIII2)SnIIPc(2−)}·2C6H4Cl2 (1) (Cp* is pentamethylcyclopentadienyl) is the first crystalline complex of a metal phthalocyanine in which an iridium(III) atom is bonded to the central tin(II) atom of Pc via a Sn–Ir bond length of 2.58 Å. In (TBA+)(C60•–){(Cp*IrIIII2)SnIIPc(2−)}·0.5C6H14 (2), the {(Cp*IrIIII2)SnIIPc(2−)} units cocrystallize with (TBA+)(C60•–) to form double chains of C60•– anions and closely packed chains of {(Cp*IrIIII2)SnIIPc(2−)}. Interactions between the fullerene and phthalocyanine subsystems are realized through π–π stacking of the Cp* groups of {(Cp*IrIIII2)SnIIPc(2−)} and the C60•– pentagons. Furthermore, the spins of the C60•– are strongly antiferromagnetically coupled in the chains with an exchange interaction J/kB = −31 K. Anionic (TBA+){(Cp*IrIICl)(η2-C60–)}·1.34C6H4Cl2 (3) and (TBA+){(Cp*IrIII)(η2-C60–)}·1.3C6H4Cl2·0.2C6H14 (4) are the first transition metal complexes containing η2-bonded C60– anions, with the Cp*IrIICl and Cp*IrIII units η2-coordinated to the 6–6 bonds of C60–. Magnetic measurements indicate diamagnetism of the {(Cp*IrIICl)(η2-C60–)} and {(Cp*IrIII)(η2-C60–)} anions due to the formation of a coordination bond between two initially paramagnetic Cp*IrIICl or Cp*IrIII groups and C60•– units. DFT calculations support a diamagnetic singlet ground state of 4, in which the singlet–triplet energy gap is greater than 0.8 eV. DFT calculations also indicate that the C60 molecules are negatively charged.