Diphosphorus Release and Heterocumulene Oligomerisation by Nickel Complexes

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Materials Science

Background:

• Diphosphorus (P2) molecules are valuable synthons for creating diphosphine ligands via [4+2] cycloadditions.
• Previously, P2 release from nickel complexes was achieved using CO gas.
• An alternative, milder method for P2 generation is desirable.

Purpose of the Study:

• To develop an alternative protocol for generating diphosphorus (P2) molecules from nickel complexes using heterocumulenes.
• To explore the reactivity of these P2 units in solution.
• To synthesize novel nickel complexes featuring pincer-type ligands.

Main Methods:

• Utilized heterocumulenes (aryl isothiocyanates and carbon disulfide) as reagents for P2 release.
• Employed a nickel butterfly complex [{(IMes)Ni(CO)}2(μ2,η2:η2-P2)] as the P2 source.
• Investigated reactions with N-heterocyclic carbene nickel(0) complexes as precursors.

Main Results:

• Developed a new protocol for P2 generation using heterocumulenes, avoiding CO gas.
• Observed trimerization of aryl isothiocyanates within the nickel coordination sphere, forming S-C-S pincer ligands.
• Carbon disulfide coordinated to form a dinuclear complex.
• P4 formation (P2 dimerisation) was also observed.

Conclusions:

• Heterocumulenes provide an effective alternative to CO gas for P2 generation from nickel complexes under mild conditions.
• This method facilitates the synthesis of novel nickel complexes with unique pincer-type ligands.
• The study expands the synthetic utility of P2 chemistry in organometallic catalysis.