Variations in capping the Zr6O4(OH)4 cluster core.: X-ray structure analyses of [Zr6(OH)4O4(OOC-CH=CH2)10]2(μ-OOC-CH=CH2)4 and Zr6(OH)4O4(OOCR)12(PrOH) (R = Ph, CMe = CH2)

The title compounds were obtained by reaction of Zr((OPr)-Pr-n)(4)) with an excess of the corresponding acids and analyzed by single crystal Xray diffraction. Each cluster consists of a Zr6O4(OH)(4) core in which the faces of a Zr-6 octahedron are capped by mu-OH or mu-O groups, while the arrangement of the carboxylate ligands shows variations: in [Zr-6(OH)(4)O-4(acrylate)(10)](2)(mu-acrylate)(4) two cluster units are bridged by acrylate ligands. In Zr-6(OH)(4)O-4(OOCR)(12)((PrOH)-Pr-n) (R = Ph, CMe = CH2) one carboxylate ligand is only monodentate, and the emptied coordination site is occupied by a propanol ligand. Several carboxylic acid molecules are hydrogen-bonded at the periphery of the clusters, mostly via the mu-OH groups. (C) 1999 Elsevier Science S.A. ALI rights reserved.