High-spin Mangan(II)-Phthalocyanine: Darstellung und spektroskopische Eigenschaften von Acidophthalocyaninatomanganat(II)

High Spin Manganese(II) Phthalocyanines: Preparation and Spectroscopical Properties of Acidophthalocyaninatomanganate(II) Acidophthalocyaninatomanaganese(III) is reduced by boranate, thioacetate or hydrogensulfide to yield acidophthalo-cyaninatomanganate(II) (Mn(X)Pc^2?]^?; X = Cl, Br, NCO, NCS) being isolated as tetra(n-butyl)ammonium salt. In the cyclovoltammogram of Mn(NCO)Pc^2?]^? the halv-wave potential for the redoxcouple Mn^II/Mn^III is at ?0.13 V, that of the first ring reduction at ?0.99 V. The magnetic moments are indicative of high-spin ⁶A₁ ground states: μ_Mn = 5.84 (NCO), 5.78(Cl), 5.65 (Br), 5.68 μ_B (NCS). A Curie-like temperature dependence of μ_Mn is observed in the region 300–30 K. Below 30 K an increase in μ_Mn occurs due to weak intermolecular ferromagnetic coupling. The ESR spectra confirm the S = 5/2 ground state with a strong g = 6 resonance observed (A_Mn = 80 G) as expected for an axially distorted ligand-field. Besides the typical π-π* transitions of the Pc^2?-ligand several weak bands are observed in the Uv-vis-n.i.r. spectra at ca. 7.5, 9.1, 14.0 and 19.0 kK that are assigned to trip-multiplet transitions. In resonance with the band at 19.0 kK the Mn? X stretching vibration (v(MnX)) is resonance Raman enhanced: X = NCO: 319, Cl: 286, SCN: 238, Br: 202 cm^?1. These vibrational frequencies are confirmed by the f.i.r. spectra. In the case of the thiocyanato-complex probably both forms of bonding of the ambident NCS-ligand are present (v(Mn? NCS): 274 cm^?1). The frequencies of the vibrations of the inner (CN)₈ ring are reduced by up to 20 cm^?1 as compared with those of low spin Mn^II phthalocyanines.