Preparation of [Co(II)(PNNP)Br]+ PNNP = {PR12CH2CHNCHR2-}2 complexes by the template method and their reactions.

Paramagnetic cobalt(II) and diamagnetic cobalt(III) PNNP complexes were prepared for the first time from bench-stable phosphonium dimers in a facile one-pot template synthesis. The template method allows for the easy customization of the phosphine and amine backbone substituents. Smaller substituents and anions result in the formation of unusual polymeric structures featuring linear bromide bridges. These complexes were characterized by crystallography, elemental analysis, cyclic voltammetry, magnetometry and electron paramagnetic resonance spectroscopy. The PNNP ligands impart similar electrochemical properties to Co(II) as the (PMe2CH2CH2PMe2)2 ligand set according to a modified Lever correlation. The complexes undergo interesting redox disproportionation reactions. They are less active for the catalytic transfer hydrogenation of ketones than similar complexes with an NH group on the PNNHP' ligand.