Mono- and polynuclear Ag(i) complexes of N-functionalized bis(diphenylphosphino)amine DPPA-type ligands: synthesis, solid-state structures and reactivity.

The reactivity of the N-functionalized DPPA-type ligands (PhP)N(p-Z)CH [Z = H (1a), SMe (1b), OMe (1c)] with AgBF was investigated and revealed an unexpected influence of the para substituent Z of the N-aryl ligand. In acetone, the mononuclear bis-chelated [Ag{(1a-1c)-P,P}]BF (2a·BF-2c·BF) and dinuclear bridged Ag{μ-(1a-1c)-P,P} [3a·(BF)-3c·(BF)] complexes were obtained with a 1 : 2 and 1 : 1 AgBF/ligand molar ratio, respectively. While the molecular structures of 2a·BF and 2b·BF determined in the solid-state by X-ray diffraction revealed their mononuclear nature and the absence of cation/anion interaction, complexes 3b·(BF) and 3c·(BF) form 2D coordination polymers through intermolecular Ag-S or Ag-O interactions, respectively, involving the N-function of the respective DPPA-type ligand, and display direct interactions between one BF anion and both Ag(i) cations. Surprisingly, the equimolar reaction between ligands 1a-1c and AgBF in CHCl led to different proportions of the dinuclear complexes 3a·(BF)-3c·(BF) and clusters [Ag(μ-Cl){μ-(1b-1c)-P,P}]BF (4b·BF-4c·BF), depending on the nature of the para substituent Z of the N-aryl ligand. The trinuclear complexes resulted from C-Cl bond activation of the chlorinated solvent and were characterized by NMR spectroscopy and X-ray diffraction, and could be selectively produced by addition of 2/3 equiv. of [NMe]Cl to the corresponding dinuclear complexes or by a one-pot procedure involving the correct amount of each reagent. A series of experiments and kinetic NMR investigations were performed to gain further insight into the formation of the trinuclear AgCl core clusters.