502 F.A.COTTON, B.F.G. JOHNSON,
AND
R.M. WING
Inorganic Chemistry
COSTRIBUTION FROX THE DEPARTMENT OF CHEXISTRY, OF TECHSOLOGY, CAMBRIDGE, MASSACHCSETTS MASSACHUSETTS INSTITUTE
Coordination Compounds of Thallium(III)l E\, I?. A. COTTON, R . P. C:. J O H N S O K ,
ANl)
K. h1. &:T:TN 4 apparently do not exist in equilibrium in trile which is more than twice that of the chloro comaqueous solution, i t seems evident that the nature of pound. While this conductance is below the range for the compounds obtained from aqueous solution is dea 1: 1 electrolyte, even if the compound is formulated as { T1[(C&,)3PO]4Br2] [TlBr4], it indicates appreciable termined by complicated heterogeneous equilibria and perhaps by certain kinetic factors, with these depending ionic dissociation of some kind in CH3CN. inter alia upon cation size. It was with these consideraAttempts to prepare TI13 [(C6H5)3P0]2 were unsucin mind that the present studies were carried out cessful, the product being, instead, TI13 [ ( C & ~ B ) ~ P O ] ~tions . largely in nonaqueous media, using relatively large This compound has molar conductances of 106 ohm-' quaternary cations. Our hope of thus finding somemole- 'in acetonitrile and 72 ohm-l cm.2mole-' in what simpler and more regular behavior has been fulnitromethane. Both of these values are close to those filled. Perhaps the most striking result is the prevatypicalof 1: 1electrolytes'jon thebasisof a dimeric moleclence of simple M [TlXd] type compounds, in contrast to ular formuIa, { TI[ ( c ~ H ~ ) 141* ~ P o{ TI[ ( c ~ H ~ ) ]A ~ P]o. the virtual absence of such compounds among the Discussion products which have been obtained from aqueous systems. Published data providing definitive structural inThe present study shows, first, that compounds of the formation on thallium(II1) complexes is very limited. stoichiometry M [TlXb], where M is a large quaternary The binuclear complex occurring in Cs3TlzC19was deammonium or arsonium cation, are easy to prepare in scribed by Hoard and Goldstein.lGHexahalothallatepure, crystalline form, and that such compounds are (111)ions with octahedral structures have been found in 1: 1 electrolytes in CH3CN. No compounds of this KsT1C16 2H20,17 Rb3T1Br6.8/7Ha0,'7 [ C O ( N H ~ ) ~ ] T ~ class appear to have been reported prior to this. For C16,18and [ C O ( N H ~ ) ~ ] T I and B ~ ~the , ~ *octahedral [TIthe particular case of [ (C6H5)&] [TlC14], i t has been C15Hz0]2-ion has been found in the cesium salt.I9 ,4 shown that the tetrachlorothallate ion is tetrahedral. tetrahedral tetrabromothallate(II1) ion has recently The compounds [(n-C4Hg)4N][TlXd] with X = C1 or Br are isomorphous and presumably isostructural, but (13) R I . J. Frazer, W.Gerrard, arid I
