Crystal and Molecular Structure of Thiocarbonyl-ethoxo(tetraphenylporphyrinato)ruthenium(II), [Ru(TPP)(CS)(HOC₂H₅)]. A Case of Centrosymmetric-Noncentrosymmetric Ambiguity

[Ru(TPP)(CS)(EtOH)] crystallizes in the triclinic system. Crystal data: C₄₇H₃₄N₄ORuS, M_r = 803.91, a = 10.607 (3), b = 11.308 (5), c = 17.699 (2) Å, = 77.53 (2), = 73.17 (1), = 69.85 (3)°, V = 1891.6 (10) Å³, P (C¹_i, no. 2), Z = 2, F(000) = 824, D_x = 1.410, D_m = 1.39 Mg m^-3 (by flotation in aqueous KI), (Mo K) = 0.512 mm^-1, R = 0.094, wR = 0.098, S = 2.28 for 4610 independent reflections with F_o > 5(F_o). A second data set was collected using Cu K radiation. The structure was refined by standard least-squares and difference-Fourier methods in space groups P1 and P using both the Mo K and Cu K data sets. Both data sets favor space group P, the Mo data giving a slightly better result than the Cu data. The two independent Ru atoms lie on the inversion centers ½,0,0 and ½,½,½ of space group P. Consequently, the two independent molecules have crystallographically imposed symmetry, the CS and EtOH axial groups are disordered and the RuN₄ portions of the molecules are planar. The deviations from planarity of the porphyrinato core are very small. The Ru-C-S groups are essentially linear with an average Ru-C-S bond angle of 174 (1)°. The mean Ru-C(CS) and Ru-O (Et) bond lengths are 1.92 (4) and 2.15 (3) Å, respectively.

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