The crystal structure of the decaaluminum alkoxide cluster Al₁₀O₄(OH)₈ L ₁₄ (L = 1,1,1,3,3,3-hexafluoropropan-2-olate)

Abstract

In the title centrosymmetric cluster compound, hexakis(μ2-1,1,1,3,3,3-hexafluoropropan-2-olato)octakis(1,1,1,3,3,3-hexafluoropropan-2-olato)octa-μ2-hydroxido-di-μ4-oxido-di-μ3-oxido-decaaluminium, [Al10(C3HF6O)14(OH)8O4] (C42H22Al10F84O26), there is a central μ4-OAl4 moiety, which has six edges of which three contain μ(O)-1,1,1,3,3,3-hexafluoropropan-2-olate (L) ligands and two contain μ-OH groups each bridging two Al atoms along an edge. The sixth edge is occupied by a group containing a fifth aluminium atom [bis-μ(OH)-, μ3(O)—AlL]. This last μ3(O) group generates a centrosymmetric Al2O2 dimer, thus the μ3(O) atom is linked to two Al atoms in the asymmetric unit as well as a third Al atom through a center of inversion. Three of the hexafluoropropyl groups of the C3HF6O− ligands are disordered and each was refined with two conformations with occupancies of 0.770 (3)/0.230 (3), 0.772 (3)/0.228 (3) and 0.775 (3)/0.225 (3). The five unique Al centers have coordination numbers varying from four to six with bond angles that show considerable distortions from regular geometry: for the four-coordinate atom, τ4′ = 0.886, while three Al atoms are five-coordinate (τ5 values = 0.098, 1.028, and 0.338) and one is distorted six-coordinate with O—Al—O bond angles ranging from 74.22 (9) to 171.59 (12)°. The geometry about the central O atom in the OAl4 block is significantly distorted tetrahedral (τ4′ = 0.630) with Al—O—Al angles ranging from 95.50 (9) to 147.74 (13)°. The extended structure features numerous O—H...O, O—H...F, C—H...O and C—H...F hydrogen bonds and short F...F contacts.