We thank Mark Tanouye for providing the para cDNA P15 and Bill Engels for statistical advice and software. We are also indebted to past and present members of the Ganetzky laboratory for both technical advice and comments on the manuscript. This work was supported by a NATO postdoctoral fellowship from the Science and Engineering Research Council

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The variation of the magnetic susceptibility of oxovanadium(IV) acetate with temperature may be fitted to the Ising model of an infinite linear antiferromagnetic chain with the exchange energy of -166 cm-1. On the basis of this and infrared evidence a structure for the compound is proposed.

Two series of complexes, believed to be of the forms (R1 = R2 = Me, Et, Pri, Bu and R1 = H, R2 = Me) and (R = Me, Et, C2H4Cl, Pr, Bu, n-C8H17) have been prepared. A large anion X was used to precipitate the green compounds, which are monomeric and 1 : 1 electrolytes in solution. Infrared, electronic and e.s.r. spectra are reported together with magnetic susceptibility measurements. The phosphorus hyperfine coupling observed in the dithiophosphates is discussed in the light of current models. VO(R,NCS,),.~-~~ There have also been reports of e.s.r. measurements on solutions containing the vanadyl ion and d i t h i~~h o s~h a t e s~~"~ and dithiophosphinate~.l~-~~ Recently some vanadyl dithiophosphinates have actually been isolated and fully c h a r a c t e r i~e d .~~-~~ In accordance with the class A character of the metal, the majority of these compounds have proved air-sensitive.Previous work2 has shown that the presence of two cyclopentadienyl rings y-bonded to vanadium@) modifies the nature of the metal so as to facilitate chelation of ligands coordinating through two sulphur atoms. In this paper, the preparation and properties of complexes of the [cp2VI2 + group with some selected dithiocarbamates and dithiophosphates are described. The dithiophosphates are of special interest because of the possibility of superhyperfine interaction, in the e.s.r. spectra, between the unpaired electron on the vanadium atom and the phosphorus nucleus.Abbreviations used in the text are as follows: y- Experimental Sodium N,N-DialkyldithiocarbamatesThe compounds were prepared from carbon disulphide, the appropriate amine and sodium hydroxide essentially by the method of Klopping and van der Kerk.24 Bis(~-cyclopentadienyl)-N,N-dialkyldithiocarbamatovanadium(~v) TetraphenylboratesThe stoichiometric amount of sodium dialkyldithiocarbamate in approximately 50 ml of distilled water was added with stirring to 1.0 g of cp2VC12 in approximately 150 ml of distilled water. The resulting solution was allowed to stand for 10 min and then filtered into an aqueous solution of Na(Ph,B). The light green powder which resulted was washed well with water, ethanol and ether, and dried at 60°C.

The first xanthates of vanadium(1v) to be isolated have been prepared in aqueous media from opzVClz and NaSzCOR (R = CH3, CzH5, i-C3H7, C4H9, and C6Hll). The purple crystalline solids are monomeric 1 : 1 electrolytes in solution and believed to be of the form Room temperature magnetic moments are c. 1.65 B.M. and the magnetic susoeptibility follows the Curie law. Infrared, electronic, and e.s.r. spectra are reported.