The Homoleptic Square-Antiprismatic Chelate Tetrakis(3-acetyl-2,4-pentanedionato)zirconium(IV): A Promising Coordination Motif for Tetrahedral Metal−Organic Frameworks

The novel analogue of the parent Zr(acac)4 complex, tetrakis(3-acetyl-2,4-pentanedionato)zirconium(IV), Zr[C7O3H9]4,
has been synthesized straightforwardly by a salt-free methodology and was characterized by a number of complementary methods
(1H NMR, 13C NMR, IR, and bulk density). From polycrystalline material, X-ray powder diffractograms and micro-Raman spectra
were obtained and are discussed in detail. The crystal structure was determined from laboratory X-ray powder diffraction data by
simulated annealing and subsequently refined with the Rietveld technique. The compound is monoclinic with space group P2/c. Zr,
residing on a crystallographic 2-fold rotation axis, is coordinated by the four chelating ligands forming a square-antiprismatic
coordination polyhedron. Differences and similarities to zirconium(IV)acetylacetonate, Zr[C5O2H7]4, and other similar complexes
are discussed, addressing the conformational rigidity of this symmetrically substituted homoleptic acac complex.