Abstract
In the title centrosymmetric cluster compound, hexa-kis-(μ2-1,1,1,3,3,3-hexa-fluoro-propan-2-olato)octa-kis-(1,1,1,3,3,3-hexa-fluoro-propan-2-olato)octa-μ2-hydroxido-di-μ4-oxido-di-μ3-oxido-deca-aluminium, [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-hexa-fluoro-propan-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 hexa-fluoro-propyl 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 tetra-hedral (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.
Highlights
In the title centrosymmetric cluster compound, hexakis(2-1,1,1,3,3,3-hexafluoropropan-2-olato)octakis(1,1,1,3,3,3-hexafluoropropan-2-olato)octa-2hydroxido-di-4-oxido-di-3-oxido-decaaluminium, [Al10(C3HF6O)14(OH)8O4] (C42H22Al10F84O26), there is a central 4-OAl4 moiety, which has six edges of which three contain (O)-1,1,1,3,3,3-hexafluoropropan-2-olate (L) ligands and two contain -OH groups each bridging two Al atoms along an edge
The sixth edge is occupied by a group containing a fifth aluminium atom [bis-(OH), 3(O)—AlL]
This last 3(O) group generates a centrosymmetric Al2O2 dimer, the 3(O) atom is linked to two Al atoms in the asymmetric unit as well as a third Al atom through a center of inversion
Summary
The interest in metal alkoxides (Turova et al, 2002) is due to their potential use as precursors of oxide materials in sol–gel technology (Brinker & Scherer, 1990) with applications in many fields including biomaterials (Avnir et al, 2006), and in the synthesis of single-phase materials, which provide unique possibilities to tailor the mechanical, electrical, and optical properties (Schottner, 2001). Both contain a 3(O) group linking the two halves as well as an additional Al(OEt) group, which links the two building blocks through two (OEt) on each side of the group In this instance this both linking moieties are located about a center of inversion The situation for Al11O6(OnPr)10(OiPr)10(Oi/nPr)(HOi/nPr) (Starikova et al, 2004) is slightly more complex: in this case the two building blocks are linked by group containing three Al atoms of which the central Al is located on a twofold crystallographic axis. From this survey of aluminum alkoxide aggregates containing more than five Al centers, it can be seen that the present structure is unique in both its building block and the method of aggregation In this instance, the edges of the OAl4 block are made up by three (O)-1,1,1,3,3,3-hexafluoropropan-2-olate (L) and two -OH bridges with the sixth edge vacant to allow for dimerization. In addition there are strong O—HÁ Á ÁO and O—HÁ Á ÁF and weak
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