Specific structural features of 1-hydroxyethane-1,1-diphosphonic acid (HEDP) and its salts with organic and alkali-metal cations

Specific structural features of 1-hydroxyethane-1,1-diphosphonic acid (HEDP , H4L) and its ten salts with organic and alkali-metal cations are discusse d. The following problems are addressed: (1) the dependence of the P-O bond lengths on whether the oxygen atom is protonated or not and on the total c harge of the HnLn-4 anion; (2) the variants of the statistical distribution of the shared protons; (3) the modes of connection of the HnLn-4 anions by hydrogen bonds into dimers or polymeric chains; (4) coordination modes of polydentate HnLn-4 ligands in the salts of alkali-metal cations. (C) 2000 M AIK "Nauka/Interperiodica".