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*Ir^IIII₂)­Sn^IIPc­(2−)}·2C₆H₄Cl₂ (<b>1</b>) (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*Ir^IIII₂)­Sn^IIPc­(2−)}·0.5C₆H₁₄ (<b>2</b>), the {(Cp*Ir^IIII₂)­Sn^IIPc­(2−)} units cocrystallize with (TBA⁺)­(C₆₀^•–) to form double chains of C₆₀^•– anions and closely packed chains of {(Cp*Ir^IIII₂)­Sn^IIPc­(2−)}. Interactions between the fullerene and phthalocyanine subsystems are realized through π–π stacking of the Cp* groups of {(Cp*Ir^IIII₂)­Sn^IIPc­(2−)} and the C₆₀^•– pentagons. Furthermore, the spins of the C₆₀^•– are strongly antiferromagnetically coupled in the chains with an exchange interaction <i>J</i>/<i>k</i>_B = −31 K. Anionic (TBA⁺)­{(Cp*Ir^IICl)­(η²-C₆₀^–)}·1.34C₆H₄Cl₂ (<b>3</b>) and (TBA⁺)­{(Cp*Ir^III)­(η²-C₆₀^–)}·1.3C₆H₄Cl₂·0.2C₆H₁₄ (<b>4</b>) are the first transition metal complexes containing η²-bonded C₆₀^– anions, with the Cp*Ir^IICl and Cp*Ir^III units η²-coordinated to the 6–6 bonds of C₆₀^–. Magnetic measurements indicate diamagnetism of the {(Cp*Ir^IICl)­(η²-C₆₀^–)} and {(Cp*Ir^III)­(η²-C₆₀^–)} anions due to the formation of a coordination bond between two initially paramagnetic Cp*Ir^IICl or Cp*Ir^III groups and C₆₀^•– units. DFT calculations support a diamagnetic singlet ground state of <b>4</b>, in which the singlet–triplet energy gap is greater than 0.8 eV. DFT calculations also indicate that the C₆₀ molecules are negatively charged