PREPARATION AND PROPERTIES OF BINUCLEAR A NTIMONY(V) COMPLEXES WITH BRIDGING BENZYLMETHOXOPHOSPHONATO LIGANDS

The binuclear antimony(V) complexes Cl3Sb(O)[R(3)(R(1)O)PO2](OR(2))SbC l3 with R(1) = R(2) CH3 and R(3) = p-ClC6H4CH2 (1), p-O2NC6H4CH2 (2) a re prepared by reaction of the corresponding benzylmethoxophosphonic a cids with antimony(v) chloride; water and methanol. 2 crystallizes in the orthorhombic space group Pnma with a = 1297.3, b = 1324.8, c = 126 9.7 pm and Z = 4. The molecules of 1 and 2 are formed from two octahed ra sharing one edge with antimony central atoms. Oxygen atoms are the links between the antimony atoms which are bridged by the bidentate ph osphonato ligand. In solution the bridging phosphonato groups are inve rted rapidly and the R(2) groups undergo a slow intermolecular exchang e. Two isomers can be detected by NMR spectroscopy.