Hydrogen Bond Studies. XXXXVI. The Crystal Structures of Normal and Deuterated Sodium Hydrogen Oxalate Monohydrate NaHC2O4·H2O and NaDC2O4·D2O

Abstract

The crystal structures of NaHC₂O₄·H₂O and NaDC₂O₄·D₂O have been determined from three‐dimensional single crystal x‐ray diffractometer data obtained at room temperature. Two formula units crystallize in a triclinic unit cell with the dimensions: $\text{a\hspace{0.17em}=\hspace{0.17em}6.503, b\hspace{0.17em}=\hspace{0.17em}6.673, c\hspace{0.17em}=\hspace{0.17em}5.698 Å, α\hspace{0.17em}=\hspace{0.17em}85.04, β\hspace{0.17em}=\hspace{0.17em}110.00, γ\hspace{0.17em}=\hspace{0.17em}105.02°}$ for the hydrogen compound and $\text{a\hspace{0.17em}=\hspace{0.17em}6.501, b\hspace{0.17em}=\hspace{0.17em}6.671, c\hspace{0.17em}=\hspace{0.17em}5.716 Å, α\hspace{0.17em}=\hspace{0.17em}84.91 β\hspace{0.17em}=\hspace{0.17em}109.93 γ\hspace{0.17em}=\hspace{0.17em}105.00°}$ for the deuterated compund. The space group is $\text{P1̄}$ . The hydrogen oxalate ions are linked end to end in infinite chains by hydrogen bonds (2.571 Å). The chains are cross linked to form layers by both O–H···O bonds from the water molecules (2.808, 2.826 Å) and by ionic bonds Na⁺···O. These layers are in turn held together by Na⁺···O bonds. The oxalate group is nonplanar with an angle of twist about the C–C bond of 12.9°. The only significant difference between the bond distances in the normal and deuterated compound occurs in the shortest hydrogen bond, which is 0.022 Å longer in the deuterated case.