solid bis(cumene) and bis(m-di-isopropy1benzene)chromium were obtained by condensing chromium vapour with the arenes at -1 96". Stable complexes Cr(arene) (PF,), have been made from chromium vapour, PF, , and the vapour of benzene, hexafluorobenzene, cumene, or mesitylene; the yield of Cr(C,F,) (PF,), was poor. Condensation of iron vapour, PF,, and C6H6 formed Fe(C6H,) (PF,),. Manganese vapour condensed with a mixture of NO, BF, , and PF3 gave Mn(N0)3PF3, but nitric oxide has proved to be a dangerous reagent in metal University of Bristol, Bristol BS8 1 TS atom reactions.THE formation of complexes by reacting transition-metal vapours with ligands at low temperatures provides a useful alternative to conventional synthetic methods, as is now apparent in publications from several sou~-ces.~-~ I n this work we describe the preparation of some compounds of zerovalent chromium, manganese, iron, and cobalt, using arenes, trifluorophosphine, and nitric oxide as ligands. EXPERIMENTAL Afifiarutus and Techniques.-Evaporation and low temperature condensation reactions of Mn, Fe, and Co were carried out in glass or stainless steel apparatus previously described.1, 2 s 6 Most reactions with chromium vapour were conducted in the apparatus of Figure (a). The metal was sublimed from a spiral of tungsten or molybdenum wire (1 mm diameter) heated by a current of 40-50 A. Molybdenum1
