Novel Dinucleating Ligand Systems Containing Two Adjacent Coordination Compartments of the Potential Triamidoamine-Type - Nickel(II) and Cobalt(II) Coordination Chemistry

The preparation of novel dinucleating pyrazolate ligands H5L3 - H5L8 carrying chelating side arms with appending secondary amine functions is reported. Following different synthetic routes, either CH2CF3, C6H2F3 , or C6F5 moieties can be introduced as substituents at the terminal nitrogen atoms. These systems are reminiscent of two coupled coordination compartments of the potential triamidoamine-type. Crystallographic analyses of a series of bimetallic complexes of the CH2CF3 -substituted ligand H5L4 with NiCl2 and CoCI2 reveal manifold coordination modes in the solid state, resulting from the facile detachment of a single or several N-donor sites from the metal centers. Coordination number sets {4/6} (in H5L4Co2Cl4) and {5/6} (in H4L4Ni2Cl3, H4L4Co2 Cl3 and H5L4Ni2Cl4) are thus observed. In the non-deprotonated H5L-type systems the remaining protons are found to be scavenged by a pyrazolate-N (in H5L4Ni2Cl4) or an amine function of a ligand side arm (in H5L4Co2Cl4).