Silver(i)-organophosphane complexes of electron withdrawing CF3- or NO2-substituted scorpionate ligands

Abstract

New silver(I) complexes have been synthesized from the reaction of AgNO₃, monodentate tertiary phosphanes PR₃ (PR₃ = P(C₆H₅)₃, P(o-C₆H₄CH₃)₃, P(m-C₆H₄CH₃)₃, P(p-C₆H₄CH₃)₃, PCH₃(C₆H₅)₂) and two novel electron withdrawing ligands: potassium dihydrobis(3-nitropyrazol-1-yl)borate and potassium dihydrobis(3-trifluoromethylpyrazol-1-yl)borate. These compounds have been characterized by elemental analyses, FT-IR, ESI-MS and multinuclear (¹H, ¹⁹F and ³¹P) NMR spectroscopy. Solid state structures of the potassium salts K[H₂B(3-(NO₂)pz)₂] and K[H₂B(3-(CF₃)pz)₂] have been reported. They form polymeric networks due to intermolecular contacts of various types between the potassium ion and atoms of the neighboring molecules. The silver adducts [H₂B(3-(NO₂)pz)₂]Ag[P(C₆H₅)₃]₂ and [H₂B(3-(NO₂)pz)₂]Ag[P(p-C₆H₄CH₃)₃] have pseudo tetrahedral and trigonal planar silver sites, respectively. The bis(pyrazolyl)borate ligand acts as a κ²-N₂ donor. The nitro-substituents are coplanar with the pyrazolyl rings in all these adducts indicating efficient electron delocalization between the two units. The [H₂B(3-(CF₃)pz)₂]Ag[P(C₆H₅)₃] complex has been obtained from re-crystallization of {[H₂B(3-(CF₃)pz)₂]Ag[P(C₆H₅)₃]₂} in a dichloromethane–diethyl ether solution; it is a three-coordinate, trigonal planar silver complex.