Tetrahedral cobaltii complexes stabilized by the aminodiphosphine PNP ligand PNP CH3CH2CH2NCH2CH2PPh22

The reaction of CoCl2·6H2O and PNP PNP 1,1-bisdiphenylphosphinoethyl-n-propylamine CH3CH2CH2NCH2CH2PPh22 in ethanol affords the blue Coii complex CoCl3η1-PPPh2CH2CH2NCH2CH2CH3HCH2CH2POPh21, which has been characterized by spectroscopic methods and X-ray diffraction analysis. The structure of 1consists of a tetrahedral cobalt atom coordinated by three chlorides and by an η1-P-PNP ligand bearing a dangling PO end and quaternised at the nitrogen atom. EPR measurements and a detailed analysis of the magnetic behaviour of 1are consistent with a tetrahedral Coii ion and accordingly support the protonation of the PNP nitrogen atom. A mechanistic picture accounting for the formation of 1has been proposed from the isolation and characterization of three reaction intermediates along the pathway leading to 1which involve either η2-P,P- and η2-P,N-PNP cobalt complexes.