Bond valence sums and structural studies of antimony complexes containing Sb bonded only to O ligands

New R₀ values for Sb(III)-O of 1.955(13) Å and for Sb(V)-O of 1.912(12) Å were derived from a bond valence sum, or BVS, analysis of of 123 SbO_n fragments with n = 3-7. These R₀ values can be used to calculate the oxidation state, or OS, of Sb in complexes where Sb is bonded only to O ligands. If the OS of the Sb ion is uncertain, the average R₀ value of 1.934 Å can be used to decide between the +3 or +5 OS from the observed Sb-O bond distances without any assumptions. The Sb-O distances used in deriving the R₀ values for the +3 and +5 complexes are tabulated as a function of coordination number and have a wide range of values, but the average Sb-O distance reflects the requirement that the BVS must equal the OS. To supplement the Sb-O data, 2 new antimony tartrates were synthesized, and their crystal structures were determined. A single crystal structure determination of NaSb(OH)₆, an unexpected reaction product, gave Sb-O distances that were also included in our BVS analysis.