Isotope and bonding effects in ammonium oxalate monohydrate, determined by the combined use of neutron and X-ray diffraction analyses

Oxalate Biominerals

“…The structure of NH 4 2 C 2 O 4 ·H 2 O has been reported by different authors in the past [39,40] and later refined by low temperature (30 K) diffraction measurements [41] and complemented by three-dimensional neutron and X-ray structural studies of both the protonated and deuterated forms [42]. This salt belongs to the orthorhombic P2 1 2 1 2 space group with Z = 2.…”

A deformation electron density study of potassium oxalate monohydrate at 100 K

“…The C-C bond length in (CH3)2NH2HC204 obtained from X-ray and neutron diffraction at room temperature (Thomas, 1977) is 1.545 (2) and 1.548 (2) A; in NaHC204.H20, obtained by neutron diffraction at room temperature (Tellgren, Thomas & Olovsson, 1977) and at 120 K (Delaplane, Tellgren & Olovsson, 1984) it is 1.552 (1) and 1.553 (1) A, respectively. In ammonium oxalate monohydrate studied by X-ray and neutron diffraction at room temperature (Taylor & Sabine, 1972), the fully ionized C20 2-groups have C-C distances of 1.565 (14) and 1.557 (2)A. In comparison with these values, the C-C bond is abnormally long in K2C204.H20, 1.573 (1)/~ (cfi Table 3).…”

Hydrogen bond studies. XCVI. X–N maps and ab initio MO–LCAO–SCF calculations of the difference electron density in noncentrosymmetric lithium formate monohydrate, LiHCOO.H2O

“…3(b) and (e), the contents of which will now be discussed and compared with the results from the ab initio calculations. (1969) and Taylor & Sabine (1972), respectively. The contours are drawn as in Fig.…”

“…Otherwise the map displays a high degree of symmetry, reflecting the close similarity in the lengths of the two hydrogen bonds donated by the water molecule, 2.88 and 2.91 A~ (corresponding H...O distances: 1.94 and 2.01 A). In the case of deutero-ammonium oxalate monohydrate (Taylor & Sabine, 1972) [ Fig. 8(b)], the water molecule lies on a twofold axis which imposes a mirror symmetry on the X-N map.…”