c37 Journal of Organometallic Chemistry, 371 (1989) C37-C39 Elsevier Sequoia S.A., Lausanne - Printed in The Netherlands zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPON JOM 20069PC Preliminary communication The crystal structure of (phenylazophenyl-C,N ’ ) mercury( II) chloride: a dimeric trans-metallation reagent Mushtaq Ali, William R. McWhiiie, Department of Chemical Engineering and Applied Chemistry Aston University, Aston Triangle, Birmingham B4 7ET (United Kingdom) and Thomas A. Hamor Department of Chemistry, University of Birmingham, Birmingham B15 2TT (United Kingdom) (Received May 4th, 1989) Abstract zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA An X-ray diffraction study of (phenylazophenyl-C, N’)mercury(II) chloride has shown it to be dimeric via long Hg-Cl bridging interactions of 3.367 A. The use of simple organomercury compounds as truns-metallation reagents in organometallic chemistry in general, and in organotellurium chemistry in particular [l], is long established. Some years ago we introduced (phenylazophenyl- C,N’)mercury(II) chloride as a convenient intermediate in the formation of cyclo- tellurated azobenzenes [2], but a more recent reinvestigation of that reaction suggested that a product containing both tellurium and mercury “contaminated” the major product [3]. The reaction of mercurated 2-phenylpyridine with p-eth- oxyphenyltellurium(IV) trichloride affords well defined ionic compounds containing both mercury and telhuium [4]. With selenium tetrabromide, the same reagent gives a material which ‘H and 13C NMR spectroscopy show to contain mercurated and selenated 2-phenylpyridine in l/ l ratio [5]. Constable [6] has demonstrated the tetrameric nature of 2-(2_pyridyl)phenyl- mercury(I1) chloride, and so it is not unreasonable that hetero-bimetallic inter- mediates may be isolated from truns-metallation reactions. The observation in the mass spectrum of (phenylazophenyl-C, N’)mercury(II) chloride of a significant fragment of m/ e = 799 (100%) having the correct isotopic distribution for [(C,,H,N,)HgCIHg(CI,H,Nz)]+ suggested that this material was not monomeric, and that, in this case also, heterobimetallic intermediates in trans-metallation reactions might, under favourable circumstances, be isolable. The cell parameters and reflection intensities were measured with graphite monochromated MO-K, radiation .for a bright red crystal, 0.6 0.06 0.05 mm of the 0022-328X/89/$03.50 0 1989 Elsevier Sequoia S.A.