Phosphenium Versus Pro-Phosphide Character of P-tert-butyl-dicyclopropeniophosphine: Zwitterionic Palladate Complexes of a Dicationic Phosphido Ligand

Cleve Dionel Mboyi; Carine Maaliki; Amelle Mankou Makaya; Yves Canac; Carine Duhayon; Remi Chauvin

doi:10.1021/acs.inorgchem.6b01524

Phosphenium Versus Pro-Phosphide Character of P-tert-butyl-dicyclopropeniophosphine: Zwitterionic Palladate Complexes of a Dicationic Phosphido Ligand

Inorg Chem. 2016 Nov 7;55(21):11018-11027. doi: 10.1021/acs.inorgchem.6b01524. Epub 2016 Oct 21.

Authors

Cleve Dionel Mboyi^{1

2}, Carine Maaliki^{1

2}, Amelle Mankou Makaya^{1

2}, Yves Canac^{1

2}, Carine Duhayon^{1

2}, Remi Chauvin^{1

2}

Affiliations

¹ Laboratoire de Chimie de Coordination (LCC), CNRS , 205, route de Narbonne, F-31077 Toulouse, France.
² Universite Toulouse III Paul Sabatier (UPS), Institut National Polytechnique (INP), Laboratoire de Chimie de Coordination (LCC), Université de Toulouse , F-31077 Toulouse, France.

PMID: 27768309
DOI: 10.1021/acs.inorgchem.6b01524

Abstract

With the view to enhancing the unique coordinating ability of the known phenyl-tetrakis(diisopropylamino)dicyclopropeniophosphine (Ph-DCP), replacement of the phenyl substituent by a tert-butyl substituent was envisaged. Both α-dicationic R-DCP phosphines, with R = Ph and ^tBu, were prepared in 54%-55% yield by substitution of RPCl₂ with two equivalents of bis(diisopropylamino)-dicyclopropenylidene (BAC) and metathesis with NaBF₄. This method is implicitly consistent with the representation of R-DCPs as BAC-phosphenium adducts. The R-DCP salts were found to coordinate hard and soft Lewis acids such as a promoted oxygen atom (in the singlet spin state) in the corresponding R-DCP oxides, and electron-rich transition-metal centers in η¹-R-DCP complexes with AuCl, PtCl₃^-, or PdCl₃^-, respectively. Coordination of Ph-DCP with PdCl₂, which is a more electron-deficient Pd(II) center, leads to pentachlorinated dinuclear complexes [(Ph-DCP)PdCl₂]₂Cl^-, where the dicoordinate Cl^- bridge screens the repelling pairs of positive charges from each other. The same behavior is inferred for the ^tBu-DCP ligand, from which addition of an excess of (MeCN)₂PdCl₂ was found to trigger a heterolytic cleavage of the DCP-^tBu bond, releasing ^tBu⁺ and a dicationic phosphide, DCP^-: the latter is evidenced as a ligand in a tetranuclear complex ion [(μ²-DCP^-)Pd₂Cl₄]₂, which, upon HCl treatment, dissociates to a doubly zwitterionic dipalladate complex. All the complexes were isolated in 82%-97% yield, and five of them were characterized by X-ray crystallography.