Dicatechol cis-dioxomolybdenum(VI): a building block for a lithium cation templated monomer-dimer equilibrium.

Dinuclear helicate-type complexes form from 3-carbonyl catechol derivatives and MoO2 units. The two monomeric subunits are non-covalently bound through templating Li+ ions. The monomeric and dimeric complexes as well as a hydrolysis product have been investigated in the solid state by X-ray crystallography, in solution by NMR experiments, and in the gas phase by ESI mass spectrometry. Dimerization constants can easily be extracted from NMR experiments. A particular property of these complexes is the mutual homochiral recognition between the two halves of the dimers which only occurs between homochiral monomers.