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Temperature programmed reduction (t.p.r.) has been used to study the redox behaviour of copper ions in X and Y zeolites. Two distinct CuII to CuI reduction processes are discernible in both X and Y zeolites. These two processes have been attributed to the reduction of CuII ions occupying sodalite and supercage sites ; a small fraction of the CuII ions, assumed to occupy hexagonal prism sites, remain unreduced. At 773 K in nitrogen, autoreduction of both sodalite and supercage CuII occurs in X zeolite, while only supercage CuII ions are autoreduced in Y zeolite. The reductions are reversible in Y zeolite, but some CuO is formed in X which is subsequently reduced by a third process. Activation energies (kJ mol-l) were obtained as follows : CuII to CuI (sodalite cages) 84f 13, CuII to CuI (supercages) 642 10 and CuO to Cuo (X-type zeolite) 494 7.

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Vibrational-spectroscopic measurements show the formation of [HgMeCI,]-from [HgMe(CI)] and "Bun4] CI in benzene, chloroform, dichloromethane, tetrahydrofuran, and acetonitrile but not in methanol or water. Similar formation of complex anions occurs for [HgMe(X)] (X = Br, I, or SCN) and for [HgR(X)] (RX = EtCI, Pr"CI, Bu"C1, EtBr, Pr"Br, Bu"Br, or Etl). The effects of the addition of halide ions on 8(lg9Hg), measured by lH-{lg9Hg} INDOR, and 2J(HgH) have been investigated and compared with the effects of solvents on these parameters. It is suggested that the complexes have an essentially linear RHgX group with the second halide much more weakly attached in the equatorial plane.