Tetrabutylammonium Salts of Aluminum(III) and Gallium(III) Phthalocyanine Radical Anions Bonded with Fluoren-9-olato(-) Anions and Indium(III) Phthalocyanine Bromide Radical Anions.

Abstract

Reduction of aluminum(III), gallium(III), and indium(III) phthalocyanine chlorides by sodium fluorenone ketyl in the presence of tetrabutylammonium cations yielded crystalline salts of the type (Bu4 N(+) )2 [M(III) (HFl-O(-) )(Pc(.3-) )](.-) (Br(-) )⋅1.5 C6 H4 Cl2 [M=Al (1), Ga (2); HFl-O(-) =fluoren-9-olato(-) anion; Pc=phthalocyanine] and (Bu4 N(+) ) [In(III) Br(Pc(.3-) )](.-) ⋅0.875 C6 H4 Cl2 ⋅0.125 C6 H14 (3). The salts were found to contain Pc(.3-) radical anions with negatively charged phthalocyanine macrocycles, as evidenced by the presence of intense bands of Pc(.3-) in the near-IR region and a noticeable blueshift in both the Q and Soret bands of phthalocyanine. The metal(III) atoms coordinate HFl-O(-) anions in 1 and 2 with short Al-O and Ga-O bond lengths of 1.749(2) and 1.836(6) Å, respectively. The C-O bonds [1.402(3) and 1.391(11) Å in 1 and 2, respectively] in the HFl-O(-) anions are longer than the same bond in the fluorenone ketyl (1.27-1.31 Å). Salts 1-3 show effective magnetic moments of 1.72, 1.66, and 1.79 μB at 300 K, respectively, owing to the presence of unpaired S=1/2 spins on Pc(.3-) . These spins are coupled antiferromagnetically with Weiss temperatures of -22, -14, and -30 K for 1-3, respectively. Coupling can occur in the corrugated two-dimensional phthalocyanine layers of 1 and 2 with an exchange interaction of J/kB =-0.9 and -1.1 K, respectively, and in the π-stacking {[In(III) Br(Pc(.3-) )](.-) }2 dimers of 3 with an exchange interaction of J/kB =-10.8 K. The salts show intense electron paramagnetic resonance (EPR) signals attributed to Pc(.3-) . It was found that increasing the size of the central metal atom strongly broadened these EPR signals.