Neutron profile refinement of potassium and rubidium oxalate monoperhydrates

Ammonium and caesium carbonate peroxosolvates: supramolecular networks formed by hydrogen bonds

“…Significant interest has been shown in the oxalates (Pedersen, 1972a,b;Adams et al, , 1980a, phosphates (Adams & Ramdas, 1978;Oeckler & Montbrun, 2008) and sulfates Pritchard et al, 2005) of alkali metals (Adams et al, 1980a,b;Oeckler & Montbrun, 2008;Pritchard et al, 2005) and of ammonium (Pedersen, 1972a,b) and guanidinium Adams & Ramdas, 1978) cations. Significant interest has been shown in the oxalates (Pedersen, 1972a,b;Adams et al, , 1980a, phosphates (Adams & Ramdas, 1978;Oeckler & Montbrun, 2008) and sulfates Pritchard et al, 2005) of alkali metals (Adams et al, 1980a,b;Oeckler & Montbrun, 2008;Pritchard et al, 2005) and of ammonium (Pedersen, 1972a,b) and guanidinium Adams & Ramdas, 1978) cations.…”

Neutron profile refinement of rubidium oxalate perdeuterate, Rb2[C2O4].D2O2, at 5 K

“…The fact that the O-O bond in D20 2 obtained both here and in the 300 K neutron study (Adams, Ramdas & Hewat, 1980) is longer than that obtained by Pedersen (1967) is probably a consequence of a reduction in the amount of random substitution of D20 2 by D20 relative to that of Pedersen's sample (there of H20 2 by H20 ). Such substitution often occurs in variable amounts in different batches of perhydrate crystals and can cause considerable apparent shortening in the peroxide O-O distances (Pedersen, 1972).…”

“…The structure is basically that found at room temperature (Pedersen, 1967;Adams, Ramdas & Hewat, 1980) with small adjustments to the molecular and ionic geometry. It should be noted that in Pedersen's (1967) work the labelling of O(1) and 0(2) has become transposed between the atom coordinate list and the molecular geometry tables.…”

“…The structure of H20 2 itself (Busing & Levy, 1965), studied by neutron diffraction, gave 1.453 (7) A while the earlier X-ray work (Abrahams, Collin & Lipscomb, 1951) gave 1.49 (2) A. A recent accurate X-ray and neutron determination of charge-density distribution in H20 2 at 110 K has been reported (Savariault & Lehmann, 1978) NEUTRON PROFILE REFINEMENT OF RUBIDIUM OXALATE PERDEUTERATE (iv) x, 1 -y, ½ + z 300 K (Adams, 300 K Ramdas (Pedersen, & Hewat, 1967, 1980 corrected) 0.99 (1) A -1.619 (9) 2.603 (8) 2.74 (1) .A 174.5 (7) The dihedral angle found for the D20 2 molecule in the title compound is 6.5 o different from that at 300 K and demonstrates the ease with which the D20 2 molecule can cope with changes in hydrogen-bonding environment by rotation about the O-O bond. The hydrogen bond which joins chains of alternating hydrogen peroxide molecules and oxalate ions has become slightly shorter at 2.597 (6) ,/~ and is almost linear (Table 3).…”

“…Recently, as part of a study of simple salt perhydrates (Adams & Pritchard, 1978;Adams, Pritchard & Hewat, 1979) we had occasion to re-examine the room-temperature crystal structures of K z [CEO4].D202 and Rb2 [CEO4].D202 (Adams, Ramdas & Hewat, 1980) to find the D atoms accurately and hence define the molecular geometry of D202 in these compounds. It had been found that the dihedral angle of this molecule can vary between wide limits depending upon the hydrogen-bonding environment (Pedersen, 1967).…”