文档介绍：research papers
Acta Crystallographica Section B Calculation of the crystal densities of molecular
Structural
Science salts and hydrates using additive volumes for
ISSN 0108-7681 charged groups
Sylvain Beaucamp,a Nicolas Standard group volumes which can be used to estimate the Received 6 March 2003
Marchet,a Didier Mathieua* and crystal densities of molecular salts and hydrates are reported, Accepted 11 June 2003
Viatcheslav Agafonovb as plement to values derived recently for the functional
groups of pounds. These new parameters
were derived from a least-squares ®t of cell volumes for a set
aCommissariat aÁ l'Energie Atomique, Centre du of 1132 ionic molecular crystals from the Cambridge
Ripault, BP16, F-37260 Monts, France, and Structural Database. Their values point to the unusual overlap
bLaboratoire de Chimie Physique, EA PIMIR
2098, Faculte de Pharmacie, 31 Avenue Monge, between monovalent O atoms and neighbouring H atoms.
F-37200 Tours, France Using the new group volumes presently obtained, the crystal
densities of the salts are predicted with an average error of
<%, while previous atom-based schemes yield average
Correspondence e-mail: didier.******@ errors of >3%. To illustrate the possible application of the
present database, the problem of designing environmentally
friendly propellants is addressed.
1. Introduction
Methods to es