5,10,15,20-Tetraphenylporphyrin–bis(trifluoroacetic acid)dioxouranium(VI) trifluoroacetate, C44H30N4.2C2HF3O2.[UO2][C2F3O2]2

Abstract

Abstract. Mr= 1339, monoclinic, Pc, a= 9.593 (8), b = 17.481 (4), c= 15.816 (9)/k, fl= 97.3 (2) ° , Z= 2, V = 2631 (7)/k 3, D x = 1.69 Mg m -3, Cu Ka, 2 = 1.5418A, #=9.85mm -1, T=233(5) K, F(000)= 1304, final R =0.068 for 3417 observed reflections. The structural features generate a pseudosymmetry which renders the interpretation of the Fourier synthesis 0108-2701/83/121625-04501. 50 and refinement of the structure difficult. The uranyl group has no direct contact with the tetraphenylporphyrin (TPP) but presents a pentacoordination in the equatorial plane with five 0 atoms belonging to four trifluoroacetate groups. Hydrogen bonds connect the TPP and the bridging trifluoroacetic acid molecules (Htfa). © 1983 International Union of Crystallography C44H30N 4.2C 2HF30 2 . [UO 2 ] [C 2F302 ] 2Introduction. The present work is part of a research programme which is being carried out on uraniummacrocycle complexes. Single crystals were supplied by Drs G. Folcher and G. de Villardi (D~partement de Physicochimie, CEN-Saclay). The space group was determined photographically. After an unsuccessful trial of structure refinement with data collected at room temperature, the intensities were measured at 233 +5 K. Cell parameters at room temperature: a= 9.601(2), b= 17.473 (3), c= 15.988 (4)A, fl= 98.2 (2) °, V= 2655 (2)/~3. Experimental. A blue prismatic crystal (approximate dimensions 0.075 × 0.075 × 0.30 mm) with boundary faces {011} was selected and mounted along the [100] direction. Enraf-Nonius CAD-4 diffractometer equipped with a cooling device. Unit-cell dimensions and their estimated standard deviations obtained from a least-squares fit of the optimized diffractometer setting angles of 25 selected reflections. 3792 unique reflections (20 < 116 °) measured with the o3/20 scan technique [scan angle (1.5 + 0.14 tg0~°], graphite-monochromatized CuKct radiation; 366 considered unobserved [I< 1.5tr(I)]. Three standard reflections monitored every 100 measurements: no significant fluctuations. Data corrected for Lorentz-polarization effects; absorption corrections made taking crystal morphology into account. The position of the U atom was determined from a Patterson synthesis. The particular position of this atom and of the centre of the tetraphenylporphyrin added a non-existing twofold axis to the Fourier map, whose symmetry group was then P2/c. The problem of separating the real structure from its pseudosymmetry-generated image was difficult, since pseudosymmetric atomic positions were very close to those of the true atoms and the tendency to produce centrosymmetric phases was very strong. The noncentrosymmetric phases computed from the positions of the U atom and the C atoms of one phenyl group located in a Fourier map were used as the initial step to break the pseudosymmetry. The subsequent Fourier synthesis calculated with the 1790 highest I Fol using MULTAN78 (Main, Hull, Lessinger, Germain, Declercq & Woolfson, 1978) enabled us to locate the TPP and three tfa groups. At this stage the R value was 0.28. Difference maps...

Effects of Porphyrin Core Saddling, meso-Phenyl Twisting, and Counterions on the Optical Properties of meso-Tetraphenylporphyrin Diacids: The [H4TPP](X)2 (X = F, Cl, Br, I) Series as a Case Study

“…15 Porphyrin diacids typically have nonplanar structures with mainly saddle-type distortions (D 2d symmetry) of the porphyrin core, as revealed by X-ray crystallography. [1][2][3][4][5][6][7][8] The deviations from planarity for diacids bearing meso-phenyl rings, such as H 2 TPP diacids, approach in magnitude those seen in peripherally crowded porphyrins, such as free-base octaethyltetraphenylporphyrin (H 2 OETPP), 16 dodecaphenylporphyrin (H 2 DPP), 17 and octabromotetraphenylporphyrin (H 2 Br 8 TPP). 18 Diprotonation of the porphyrin core has important effects on the static and dynamic photophysical properties of the diacids compared to their free-base parents.…”

“…A thorough analysis of the structural and spectroscopic properties of H 2 TPP diacids cannot leave aside the counterions, indeed. It is by now well established that close interactions exist between the diprotonated porphyrins and the conjugate bases of two acid molecules, either in the solid state [1][2][3][4][5][6][7][8] or in solutions of organic solvents. [25][26][27] There is, additionally, clear evidence for the nature of the counterions influencing significantly the photophysical parameters of the porphyrin diacids.…”

“…Porphyrin diacids, a class of compounds obtained by diprotonation of free base porphyrins, have attracted considerable interest since the mid-1960s because of their intrinsically appealing structural − and photophysical − properties. Their capability to form J -aggregates under specific conditions further stimulated this interest.…”

“…Porphyrin diacids typically have nonplanar structures with mainly saddle-type distortions ( D 2 d symmetry) of the porphyrin core, as revealed by X-ray crystallography. − …”

Promising density functional theory methods for predicting the structures of uranyl complexes

“…All calculations in this study were carried out on Gaussian 09 platform. 46 The gas-phase geometry optimization and frequency calculations are all performed at the same level. The examination on the RECPs are carried out with the B3LYP method, and the 6-311G (d,p) basis set is used for all other atoms except U.…”