Facile and Room-Temperature Activation of C_sp3–Cl Bonds by Cheap and Air-Stable Nickel(II) Complexes of (<i>N</i>‑Thioether) DPPA-Type Ligands

Reaction of the diphosphine (<i>P</i>,<i>P</i>) ligand N­(PPh₂)₂(<i>n-</i>PrSMe) (<b>1</b>) or N­(PPh₂)₂(<i>p</i>-(SMe)­C₆H₄) (<b>2</b>) with [Ni­(NCMe)₆]­[BF₄]₂ in a 2:1 molar ratio afforded the bis-chelated, dicationic Ni­(II) complexes [Ni­(<b>1</b>)₂]­[BF₄]₂ (<b>3</b>) and [Ni­(<b>2</b>)₂]­[BF₄]₂ (<b>4</b>), respectively. Both complexes were characterized in solution by various spectroscopic techniques and in the solid state by X-ray diffraction studies. In the presence of Zn metal used as cheap reductant, complexes <b>3</b> and <b>4</b> activate the inert C–Cl bonds of dichloromethane at room temperature to afford in high yield the phosphonium ylide derivatives [Ni­((Ph₂P)­N­{P­(CH₂)­Ph₂}­(<i>n-</i>PrSMe)-<i>P</i>,<i>C</i>)₂]­[BF₄]₂ (<b>5</b>) and [Ni­((Ph₂P)­N­{P­(CH₂)­Ph₂}­(<i>p-</i>(SMe)­C₆H₄)-<i>P</i>,<i>C</i>)₂]­[BF₄]₂ (<b>6</b>), respectively. The formation of [Ni­((Ph₂P)­N­{P­(CH₂)­Ph₂}­(<i>n-</i>PrSMe)-<i>P</i>,<i>C</i>)₂]­Cl₂ (<b>5</b>′), an analogue of complex <b>5</b>, from a Ni(0) precursor supports the reduction of the Ni­(II) precursors by the Zn reagent prior to C–Cl bond activation. The structures of <b>5</b> and <b>5</b>′ were unambiguously established by X-ray diffraction analysis