Hydrogen bonds in binuclear mu-hydroxo-bis[trichloroantimony(V)] complexeswith phosphate or phosphonate groups as bridging ligands

Benzylphosphonic acid monoalkylesters react with antimony(V) chloride and w ater to yield Cl3SbO(OH)[(C6H5CH2)RPO2]SbCl3. H2O (1: R = OCH3; 2: R = OC2H 5). With difluoro phosphoric acid only Cl3SbO(OH)(F2PO2)SbCl3 (3) can be is olated. The crystal and molecular structures of 1 to 3 were determined. 1 a nd 2 both crystallizing orthorhombic in the space group Pnma are hydroxoniu m salts H3O+ [Cl3SbO2((C6H5CH2) RPO2)SbCl3]-. Strong hydrogen bridges link cations and anions to chains. One of the hydrogen atoms of the cation makes a weak but important OH/pi interaction to the para C atom of the benzyl gr oup. In 3 (monoclinic, P2(1)/n) the molecules are connected by hydrogen bri dges to fourfold Delta and helices Lambda. In solution there is a rapid int ermolecular exchange of protons. IR and NMR data are communicated and brief ly discussed.