THE CHEMISTRY OF ANIONIC ANTIMONY SELENIDES - SYNTHESIS AND STRUCTURE OF SALTS OF [SB4SE6](2-) AND [FE-2(CO)(4)(SBSE4)(2)](2-)

The reaction of [HFe(CO)(4)](-) with various binary antimony selenides was investigated. In the presence of Sb2Se3 the organometallic anion acts as a reducing agent leading to formation of [Sb4Se6](2-) which has a crown shaped geometry with a transannular Sb-Sb bond. Reaction with Sb2Se5 leads to incorporation of iron carbonyl with formation of a dimer of formula [Fe-2(CO)(4)(SbSe4)(2)](2-). The cluster contains two Fe(CO)(2) fragments bridged by SbSe43- units. The main group anions are not tetrathiometallates, but rather a trivalent Sb bound to two selenides and a diselenide, Both compounds were structurally characterized as their [PPh(4)](+) salts. Crystal data for [PPh(4)](2)[Sb4Se6], triclinic, P-1, a = 10.124(2)Angstrom, b = 14.670(2)Angstrom, c = 17.352(2)Angstrom, alpha = 96.42(2)degrees, beta = 95.78(2)degrees, gamma = 97.09(2)degrees, V = 2524.2(7)Angstrom(3), Z = 2, R = 0.0377, R(w) = 0.0465; crystal data for [PPh(4)](2)[Fe-2(CO)(4)(SbSe4)(2)], monoclinic, P2(1)/n, a = 15.552(5)Angstrom, b = 110.279(3)Angstrom, c = 18.159(6)Angstrom, beta = 101.72(3)degrees, V = 2819(1)Angstrom(3), Z = 2, R = 0.0372, R(w) = 0.0395.