A deformation electron density study of potassium hydrogen diformate

KH(HCOO) 2, Mr=130.144, orthorhombic, Pbca, a=17.703(8), b=7.349(4), c=7.302(3) Aring, V=950.1(8) Aring 3, Z=8, Dx=1.820(1) g cm -3, lambda(Mo Kalpha)=0.71069 Aring, mu x(calc.)=0.973 mm -1, F(000)=528, T=120 K, R( F2)=0.033 for 2109 unique reflexions. The deformation electron density in KH(HCOO) 2 has been studied by means of experimental X- N maps obtained at 120 K. The electron distributions in the two chemically similar but crystallographically nonequivalent formate groups are discussed and correlated with bond order. The density distribution in the short intermolecular O-H. . . bond [2.437(1) Aring] is compared with experimental and theoretical maps in related compounds.