This review highlights the 1999 literature for the zinc triad with emphases on co-ordination and organometallic chemistry. For the purposes of this review, cluster complexes are de¢ned as those which contain at least three transition metal atoms, connected by metal^metal bonds and/or by bridging ligands.
Co-ordination chemistryImproved performance and information achieved using natural abundance 67 Zn NMR employing a single crystal have been demonstrated for [Zn(OAc) 2 ]Á2H 2 O. 1 Applicability of 113 Cd NMR to the detection of cadmium nitrate complexes with food biopolymers has been demonstrated under different conditions using leguminous seed globulins as an example. 2 Colorimetric tests for mercury(II) ions have been reviewed 3 as have other analytical methods for mercury compounds, particularly chromatographic techniques. 4Group 15 donor ligands There has been a review of divalent zinc-promoted hydrolysis of the phosphodiester bonds of RNA, based upon model compounds from dinucleoside monophosphate to oligio-and poly-nucleotides, and from the point of view of zinc complex formation. 5 Cadmium(II) and mercury(II) complexes with polyamines, nucleosides and nucleotides have also been reviewed. Comprehensive data for stability constants are given. 6 The trimethylene bisadenine complexes [{(H-Ade) 2 (CH 2 ) 3 } 2 -M 2 Cl 8 (H 2 O) 2 ] (M Zn, Cd or Hg) have been prepared, and the structure determined for the cadmium tetrahydrate complex. 7 EPR and single crystal X-ray data have been reported for the ¢ve-co-ordinate bis(L-alanine) complex, [Zn(O 2 CCH-(NH 3 )CH 3 ) 2 ]. 8