Unprecedented oxo-titanium citrate complex precipitated from aqueous citrate solutions, exhibiting a novel bilayered Ti8O10 structural core

Inorg Chem. 2004 Oct 4;43(20):6300-6. doi: 10.1021/ic049760r.

Abstract

Aqueous titanium citrate solutions were prepared from the reaction of citric acid with titanium 2-propoxide in a range of molar ratios. Solutions containing two or fewer citrates per titanium resulted in the slow crystallization of an insoluble titanium oxo-citrate complex. Single-crystal X-ray analysis identified the species as Ti(8)O(10)(citrate)(4)(H(2)O)(12).14H(2)O.3HOPr(i)(), crystallized in the tetragonal space group I4(1)/a, with a = 30.775(7) A, c = 14.528(7) A, V = 13 759(8) A(3), and Z = 8. The trianionic citrate ligands supply both carboxylate and alkoxide coordination and stabilize the structure using simultaneous chelating and bridging modes of attachment. The compound is a neutral species, exhibiting titanium in three contrasting environments. Laser Raman microscopy and (13)C CPMAS solid-state NMR data were consistent with those of the X-ray crystal structure. When exposed to air, the crystals rapidly lost water and became a powder. The dehydrated powder was noncrystalline to X-rays and insoluble, but (13)C NMR results demonstrated retention of the carboxylate linkages.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Citrates / chemistry*
  • Citric Acid / chemistry*
  • Crystallography, X-Ray
  • Models, Molecular
  • Organometallic Compounds / chemical synthesis
  • Organometallic Compounds / chemistry*
  • Solutions / chemistry
  • Spectrum Analysis, Raman
  • Titanium / chemistry*
  • Water / chemistry

Substances

  • Citrates
  • Organometallic Compounds
  • Solutions
  • titanium citrate
  • Water
  • titanium dioxide
  • Citric Acid
  • Titanium