Activation of CO2 and CS2 by (Me3Si)(i-Pr2P)NH and its zinc complex

The reaction of (Me3Si)(i-Pr2P)NH with ZnEt2 gives the complex {[(Me3Si)(i-Pr2P)N]ZnEt}2, which was characterized by multinuclear NMR spectroscopy and X-ray crystallography. This Zn complex reacts with CO2 to give an adduct with the proposed formula of [(Me3Si)N(i-Pr2PCO2)]ZnEt that undergoes further transformation into the crystallographically characterized di-adduct [(Me3Si)N(i-Pr2PCO2)]2Zn, in addition to a Zn6 cluster containing both P–CO2 adducts and fragments of the isocyanate i-Pr2P–NCO. These reaction pathways have been separately observed in related group 2 and group 14 complexes, but not previously within the same molecule. Reactions with the related heteroallene CS2 were also examined. The free ligand (Me3Si)(i-Pr2P)NH reacts with CS2 to form a bright red, crystalline adduct (Me3Si)[P(i-Pr)2(CS2)]NH. This adduct was treated with ZnEt2 to provide the same product that is obtained from the reaction of {[(Me3Si)(i-Pr2P)N]ZnEt}2 with CS2, proposed to be a dithiocarbamate complex, with the CS2 bound to the N instead of the P atom.

Graphical abstractThe reaction of (Me3Si)(i-Pr2P)NH with ZnEt2 gives {[(Me3Si)(i-Pr2P)N]ZnEt}2, which was characterized by NMR spectroscopy and X-ray crystallography. This Zn complex reacts with CO2 to eventualy provide both the di-adduct [(Me3Si)N(i-Pr2PCO2)]2Zn and a Zn6 cluster containing both P–CO2 adducts and fragments of the isocyanate i-Pr2P–NCO. The ligand (Me3Si)(i-Pr2P)NH reacts with CS2 to form an adduct (Me3Si)[P(i-Pr)2(CS2)]NH. This adduct was treated with ZnEt2 to provide the same product as obtained from the reaction of {[(Me3Si)(i-Pr2P)N]ZnEt}2 with CS2.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Syntheses of Zn(II) complexes with amido ligands. ► Examined reactions of CO2 and CS2 with Zn complexes. ► CO2 adducts and complexes derived from fragments of phosphino-substituted isocyanates. ► CS2 adduct with free amine ligand.