Titanium(IV) nitrate crystallises with four Ti(NO3)4 in each monoclinic unit cell of dimensions a= 7·80 ± 0·01, b= 13·57 ± 0·01, c= 10·34 ± 0·02 Å, β= 125·0°± 0·2°, and space group P21/c. The structure consists of individual molecules in each of which four symmetrically bidentate nitrato-groups are arranged according to D2d symmetry in a flattened tetrahedral manner round the central titanium atom. The dimension of the nitrato-groups differ considerably from those of a typical nitrate ion, having average N–O distances 1·292 ± 0·008 Å for the bonds adjacent to the titanium atom and 1·185 ± 0·004 Å for the outer bonds. These indicate a high contribution of the bond structure [graphic omited] to the resonance form of the molecule, consistent with the unusually high stretching frequency, 1635 cm.–1, in the infrared spectrum.