Darstellung und spektroskopische Eigenschaften von Di(phthalocyaninato(1−))-lanthanidpolybromid; Kristallstruktur von α-Di(phthalocyaninato)samariumpolybromid, α-[Sm(Pc)2]Br1,45 und α-Di(phthalocyaninato)samariumperchlorat, α-[Sm(Pc)2](ClO4)0,63 |
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| Authors: | G. Ostendorp H. W. Rotter H. Homborg |
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| Abstract: | Synthesis and Spectroscopical Properties of Di(phthalocyaninato(1?))lanthanidepolybromide; Crystal Structure of α-Di(phthalocyaninato)samariumpolybromide, α-[Sm(Pc)2]Br1.45 and α-Di(phthalocyaninato)samariumperchlorate, α-[Sm(Pc)2](ClO4)0.63 Bronze-coloured di(phthalocyaninato)lanthanidepolybromide, [Ln(Pc?)2]Bry (Ln = La…(? Ce, Pm)…Lu; y > 1.5) is prepared by oxidation of (nBu4N)[Ln(Pc2?)2] with bromine in excess. The UV-VIS-NIR spectra show the typical B and Q1 bands of the Pc? ligand at ～ 14 kK and ～ 20 kK. For the [Ln(Pc?)2]+ cation a NIR(D) band between 9,14 kK (La) and 11,50 kK (Lu) is characteristic for dimeric cofacial Pc? radicals. Within the row La…Lu, there is a linear relationship of the hypsochromic shift of the strong bands and the LnIII radius. In the case of La? Nd the D band shifts successively with longer time of bromination to ～ 3 kK as a result of increasing electron delocalisation. Characteristic vibrational bands are at ～ 1350/1450 cm?1 (IR) and ～ 560/1120/1170/1600 cm?1 (RR). In the FT-Raman spectra the totally symmetric Ln? N stretching vibration between 141 cm?1 (La) and 172 cm?1 (Lu) is selectively enhanced. As shown by α-[Sm(Pc)2]Br1,45 and α-[Sm(Pc)2](ClO4)0,63 only partially ringoxidized complexes are obtained by the anodic oxidation. Both crystallize in the tetragonal space group P4/nnc. The [Sm(Pc)2] molecular building block contains two nearly planar staggered (～41°) Pc rings packed in columns parallel along [001] leading to the quasi-one-dimensional structure. There is a statistical disorder of the SmIII and the ClO4? resp. Br?/Br3? ions over two incompletely filled crystallographic positions for the cation resp. anion. This results in a partial oxidation of the Pc ligand, which in the picture of localized valence states for α-[Sm(Pc)2](ClO4)0,63 corresponds to [SmPc?Pc2?] · 2[Sm(Pc?)2](ClO4). Accepting the same valence state for [Sm(Pc)2]Br1,45 five positive charges are compensated by two Br? and three Br3?. The spectroscopic differences of the partially and fully oxidized complexes are discussed. |
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| Keywords: | Phthalocyanines(1− ) LnIII complexes crystal structure optical spectra vibrational spectra |
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