Variations in capping the Zr6O4(OH)(4) cluster core. X-ray structure analyses of [Zr-6(OH)(4)O-4(OOC-CH=CH2)(10)](2)(mu-OOC-CH=CH2)(4) and Zr-6(OH)(4)O-4(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 diff raction. 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 arrangemen t 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 carboxyla te ligand is only monodentate, and the emptied coordination site is occupie d by a propanol ligand. Several carboxylic acid molecules are hydrogen-bond ed at the periphery of the clusters, mostly via the mu-OH groups. (C) 1999 Elsevier Science S.A. ALI rights reserved.