The coordination chemistry of tartronic acid, 1, with copper(II) has been investigated. Structures of two complexes are reported containing respectively the complex [Cu(1–2H)₂Cl]³⁻ where 1 acts as a bidentate ligand through carboxylates, and [Cu₃(1–3H)₃]³⁻ where the alcohol function is deprotonated to bridge two coppers in a triangular trinuclear complex. The latter species undergoes facile oxidation leading to carbon–carbon bond formation. The magnetic and EPR properties of the trinuclear complex have been studied in detail.

The chiral ligand S-1,2-bis(1H-benzimidazol-2-yl)ethanol, 1, reacts with manganese(II) salts to form cubanes which readily undergo oxidation reactions leading either to a tetranuclear manganese(II,III) mixed valence complex 4 or to a tetranuclear complex of ligand 5 where the secondary alcohol has been oxidised to an enolate. N-methylation of ligand 1 slows the oxidation reaction and stable manganese(II) cubanes may be isolated. The fully methylated ligand 2 gives a cubane of opposite helicity to that found previously for 1 with cobalt. The inversion may be explained by conformational analysis. Cyclic voltammetry suggests that the manganese cubanes reported here are insufficiently robust to store oxidising equivalents as in the oxygen evolving system of photosystem II.

Herein, we introduce the concept of pseudoisotope to describe particles which have similar chemistry but different masses. Examples include ligands with different substituents or metal ions with identical charges and similar coordination properties. Mixtures of pseudoisotopes may be used to establish rapidly the nuclearity of polynuclear species by electrospray ionization-mass spectrometry. Pseudoisotope exchange allows the study of the dynamics of polynuclear complexes, and shows these reactions may be surprisingly slow. The evolution of the mass spectra indicates the degree of fragmentation occurring during the exchange.