The crystal structures of anhydrous nitrates and their complexes. Part IV. Tin(IV) nitrate

Abstract

The crystal structure of tin(IV) nitrate is isomorphous with that of titanium(IV) nitrate. There are four Sn(NO₃)₄ molecules in each monoclinic unit cell of dimensions a= 7·80 ± 0·01 Å, b= 13·85 ± 0·01 Å, c= 10·23 ± 0·01 Å, β= 123·6°± 0·2°, and space-group P2₁/c. The Sn(NO₃)₄ molecule corresponds closely to D_2d symmetry and the nitrato-groups are equivalent, each being symmetrically bidentate to the tin atom. The dimensions of the nitrato-groups differ considerably from those of a typical nitrate ion, having average N–O distances 1·288 ± 0·010 Å for the bonds adjacent to the tin atom and 1·179 ± 0·016 Å for the outer bonds, indicating strong co-ordination of the nitrato-groups to the tin atom. The adoption of the dodecahedral arrangement by the eight oxygen atoms adjacent to the metal atoms in Ti(NO₃)₄ and Sn(NO₃)₄ is discussed, and a correlation between the length and stretching frequency of N–O bonds is presented.