Conformational Heterogeneity in Diphthalocyaninato(2–)metallates(III) of Sc,Y, In,Sb, Bi,La, Ce,Pr, and Sm

Potassium diphthalocyaninato(2–)metallate(III), K[M(pc^2–)₂] (M = Bi, La, Ce, Pr, Sm, Sb, In) has been prepared by melting the metal chloride, iodide or acetate with 1,2‐dicyanobenzene in the presence of potassium methylate. Crystallisation with tetra(n‐butyl)ammonium bromide or hydroxide ((ⁿBu₄N)Br/OH), tetra(n‐pentyl)ammonium chloride ((ⁿPe₄N)Cl) or bis(triphenylphosphine)iminium halide ((PNP)X; X = Br, I) yields the corresponding red‐purple complex salt (ⁿBu₄N)[M(pc^2–)₂] (M = Bi ( 1 ), La ( 3 ), Ce ( 2 )), (ⁿBu₄N)[M(pc^2–)₂] · x CH₃OH (M = Bi ( 5 ), Pr ( 6 ), Sm ( 7 ); 0 9 x 9 1), (ⁿPe₄N)[La(pc^2–)₂] ( 4 ), (ⁿBu₄N)[Pr(pc^2–)₂] · 2 py ( 10 ), (ⁿBu₄N)[Sb(pc^2–)₂] · 2 thf ( 11 ), (PNP)₂[M(pc^2–)₂]Br · 2 Et₂O (M = Sb ( 12 ), Bi ( 13 )), and (PNP)₂[In(pc^2–)₂]I · 2 Et₂O ( 14 ). Bronze coloured diphthalocyaninato(1–)metal(III) polyiodide, [M(pc^–)₂]I₂ (M = Sc, Y) has been prepared similarly in the presence of ammonium iodide. Reduction with (ⁿBu₄N)OH provides (ⁿBu₄N)[M(pc^2–)₂] · x CH₃OH (M = Y ( 8 ), Sc ( 9 ); 0 9 x 9 1). Spectral properties (UV/VIS/NIR; IR; resonance Raman) of diphthalocyaninates in their different ring oxidation states (2–/2–; 2–/1–; 1–/1–) are discussed. 1 – 3 crystallise in the tetragonal (P4/ncc), 5 – 9 in the orthorhombic (Pna2₁), 10 , 11 in the triclinic (P‐1), and 4 , 12 – 14 in the monoclinic crystal system ( 4 : P2₁/m; 12 : C2/c; 13 , 14 : P2/c). Ecliptic rotamers with skew angles ranging from 4.1° to 6.0° are found in 1 – 3 , and staggered rotamers with skew angles ranging from 35.8° to 45.0° are found in 4 – 14 . The mean M–N_i bond lengths and interplanar distances increase monotonically with the ionic radius of the metal ion. Both distances deviate notably from this linear correlation in the Sb^III and Bi^III derivatives. The discrepancy is presumably due to the sterical dominance of the ns² lone‐pair character. The actual size of eight co‐ordinated Sb^III and Bi^III is estimated to be R₈ ≈ 1.02(Sb)/1.11(Bi) Å. In every complex salt, the pc ligand is severely distorted from planarity and can adopt domed, saddled, waved and mixed non‐planar conformations; the crystal symmetry is the most important factor for the conformational heterogeneity.