North Carolina 27 109)Summary Preliminary X-ray structure analysis shows tetrachlorostibonium(v) undecafluorodiantimonate(v), an excellent aromatic chlorinating agent, to be SbCl, +Sb2-F 1 1 -s THE chlorofluorides of pentavalent antimony were first studied by Ruff who, from phase studies, adduced the existence of several compounds having the generic formula z S ~C ~, , ~S ~F , . ~ Among others (SbF,),SbCl, and (SbF,),-SbC1, were specifically cited. More recently Aubrey and Van Waser2 reported the variation of n.m.r. chemical shifts, viscosity, and electrical conductivity with composition of mixtures of SbF, and SbCl,. They were unable to obtain data in the composition region of 3.5 mol F/mol Sb because of solid formation and they also noted the generally complicated nature of the system.From an attempted synthesis of the compound Sb,Cl,F, by mixing SbC1, and SbF, in a 3: 7 mole ratio we have isolated by distillation (at ca. 0.25Torr, liquid to solid) a crystalline solid having the composition Sb,C14F,,, which shows a slight melting a t 69" followed by melting a t 79-81O.Analytical data support this formulation. t t Analysis of this material is difficult. A faulty analysis led to the assignment of an incorrect empirical formula early in the work.