A MIXED-METAL SALT COMPRISED OF METAL-METAL BONDED DINUCLEAR IONS - STRUCTURE AND PROPERTIES OF [RH2(OAC)2(MECN)6][RE2CL8]

The unusual salt [Rh2(OAc)2(MeCN)6][Re2Cl8] (1) is produced from a met hathetic reaction of the salt [NBu4n]2[Re2Cl8] with [Rh2(OAc)2(MeCN)6] [BF4]2. Crystal data for 1: Pccn, a = 27.42(l), b = 26.736(4), c = 18. 137(5) angstrom, V = 13.296(7) angstrom3, Z = 16, D(calc) = 2.450 g/cm 3, mu(Mo Kalpha) = 90.05 cm-1, R = 0.078, R(w) = 0.109 for 483 paramet ers and 5229 data with F(o)2 > 3sigma(F(o))2. The new salt constitutes the only example of a structure wherein the octachlorodirhenate unit is present in three different crystallographic environments in the sam e unit cell. The asymmetric unit contains two independent [Rh2]2+ cati ons together with one [Re2Cl8]2- anion at full occupancy and two dirhe nium anions each at half-occupancy. The synthesis, structure, key spec troscopic properties and solution behavior of 1 are presented and disc ussed.