IntroductionThis review highlights the 2001 literature for the zinc triad with emphasis on coordination and organometallic chemistry. For the purposes of this review, cluster complexes are defined as those which contain at least three transition metal atoms, connected by metal-metal bonds and/or by bridging ligands.
Co-ordination chemistryThere has been a summary of the excitation and fluorescence spectra of zinc, cadmium, and mercury atoms, from which dependable values for potential parameters, like well-depths and ground-state vibrational frequencies have been derived. 1 There have also been reviews of some new zinc fluorescent probes excitable with visible light and highly zinc-selective fluorescent sensor molecules suitable for biological applications, 2 and the luminescence and electroluminescence of zinc() complexes with nitrogen-donor ligands. 3 Other reviews have focussed on primarily zinc phosphates and oxalates with open architectures, 4 and the zinc complexes of calix[6]arenes as biomimetic receptors for neutral molecules. 5
Group 15 donor ligandsThe solid-state structure for [Zn(en)Br 2 ] consists of an infinite zigzag chain, -ZnBr 2 -(en)-ZnBr 2 -(en)-, 1, in which the ethylenediamine shows only the trans conformation. 6 The crystal structure has also been determined for [Zn(en) 3 Cl 2 ]ؒ2H 2 O. 7 Syntheses and thermal analyses have been reported for [Cd(en) = meen, eten, pren, pn, ibn) and [Cd(ipren) 2 (C 4 O 4 )]. 8 The complexes [MCl 2 (OE) 2 ] (M = Zn, Cd) have been prepared and characterised. Microemulsions of these complex surfactants were studied in water/chloroform and water/benzene mixtures. 9 Complexation studies have been carried out for zinc() complexes of tren and the two new derivatives of tren, N,NЈ, amine and N,NЈ,NЉ-