CrIII phthalocyaninates: Synthesis, properties, and crystal structure of l-bis(triphenylphosphine)iminium trans-Di(nitrito(O))phthalocyaninato(2-)chromate(III)

Article abstract of DOI:10.1002/zaac.19966221010

[Cr(H₂O)₂Pc^2-]I_x reacts with excess (PNP)NO₂ in dimethylformamide to yield less soluble greenblack l-bis(triphenylphosphine)iminium trans-di(nitrito(O))phthalocyaninato-(2-)chromate(III), ^l(PNP)^trans[Cr(ONO)₂Pc^2-], which crystallizes in the triclinic space group P1 (No. 2) with Z = 2. The Cr atom is in the center of the Pc^2- ligand and the two nitrite ions are monodentate O-coordinated in a mutually trans arrangement to the Cr atom. The Cr-O and Cr-N_iso bond distances are 1.9898(14) und 1.981(2) A, respectively. The geometric data of the coordinated nitrite ion are: d(N-O) = 1.307(2) A; d(N-O) = 1.205(2) A; (O-N-O) = 113.7(2)°; (Cr-O-N) = 116.85(12)°. The non-bonding O atoms are trans to the Cr atom. The Pc^2- ligand is slightly saddled. Three weak spin-allowed trip-quartet(TQ) transitions (in 10³ cm^-1): TQ1 (8.20) < TQ2 (11.3) < TQ3 (20.33) and the characteristic π-π* transitions of the Pc^2- ligand: B (14.68) < Q₁ (27.1) < Q₂ (29.0) < N (35.4) are observed in the UV-VIS-NIR spectrum. Prominent luminescence spectra are obtained by excitation within the TQ1 region, in which the spin-forbidden trip-sex-tet transition at 7376 cm^-1 dominates at low temperatures (T < 50 K). The vibrational spectra are discussed. In coincidence of the excitation lines with TQ3, v_s(Cr-O) at 378 cm^-1 is selectively resonance Raman (RR) enhanced. ν_as(Cr-O) is observed in the FIR spectrum at 391 cm^-1. The following internal vibrations (in cm^-1) of the nitrito ligand are in the MIR spectrum: ν_as(N-O)/1447 > ν_as(N-O)/1018/1029 > δ(O-N-O)/828 and in the RR-spectrum: ν_s(N-O)/1410 > ν_s(N-O)/952, the last followed by three overtones. Johann Ambrosius Barth 1996.