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[3+2] Fragmentation of a Pentaphosphido Ligand by Cyanide

submitted on 14.07.2019 and posted on 15.07.2019 by Christian M. Hoidn,, Thomas M. Maier, Karolina Trabitsch, Jan J. Weigand, Robert Wolf
The activation of white phosphorus (P4) by transition metal complexes has been studied for decades, but the functionalization and release of the resulting (organo)phosphorus ligands has rarely been achieved. Herein we describe the formation of unusal diphosphanides from a P5 ligand by treatment with cyanide. New cobalt diorganopentaphosphido complexes have been synthesized by a stepwise reaction sequence involving a low-valent dimine cobalt complex, white phosphorus and diorganochlorophosphanes. Reactions of such complexes with tetraalkylammonium or potassium cyanide afford the first cyclotriphosphido cobaltate anion 5 and rare 1-cyano-diphosphan-1-ide anions [R2PPCN]− (6-R). The molecular structure of a related product 7 suggests a novel reaction mechanism, where cyanide anion coordination to cobalt induces a ligand rearrangement. This is followed by nucleophilic attack of a second cyanide anion at a P atom, releasing the P2 fragment.


European Research Council (CoG 772299)

Deutsche Forschungsgemeinschaft (WO1496/7-1)

Deutsche Forschungsgemeinschaft (WE4621/3-1)

Stiftung der Deutschen Wirtschaft

Fonds der Chemischen Industrie


Email Address of Submitting Author


University of Regensburg, Institute of Inorganic Chemistry



ORCID For Submitting Author


Declaration of Conflict of Interest

no conflict of interest to declare