Coordination chemistry of the sterically hindered N3-donor hydrotris (3,5-diphenylpyrazol-1-yl) borate toward silver(I) triorganophosphino compounds. Synthesis, structural and spectroscopic characterization

The interaction between Ag(O3SCF3), trialkyl-or triaryl-phosphine ligands (PR3: R=phenyl, o-, m- and p-tolyl, benzyl; PMePh2), and the anionic N3-donor tris(3,5-diphenylpyrazol-1-yl)borate [TpPh2] in tetrahydrofuran or methanol gives new air-stable and highly soluble 1:1 [TpPh2]Ag{PR3} and [TpPh2]Ag{PMePh2} compounds. The tricyclohexylphosphine (PCy3) is able to displace PPh3 and PBz3 from the coordination sphere of silver(I), yielding the derivative [TpPh2]Ag{PCy3}. In contrast, imidazole, 1-methylmercaptoimidazole, 1,10-phenanthroline and 2,9-dimethyl-1,10-phenanthroline are not able to displace either phosphine or [TpPh2] from the coordination center. Reaction of Ag(O3SCF3) with 1 equiv. of [TpPh2] and CNR (R=Cy or But) yields the air-stable neutral compounds [TpPh2]Ag(CNR). When the reaction between [TpPh2] and Ag(O3SCF3) is carried out in tetrahydrofuran at - 70°C in the absence of the phosphorus donor, breaking of the B - N bond occurs in the anionic ligand and the ionic compound [(3,5-Ph2PzH)3Ag] (O3SCF3) · (H2O)2 was obtained from the reaction solution. All the derivatives were characterized through elemental analyses, spectral data (IR, 1H, 31P and 13C NMR) and conductivity measurements. Comparison is made with the results previously obtained with other tris(pyrazol-1-yl)borates. The solid state structures of [TpPh2]Ag{PPh3} and [TpPh2]Ag{PBz3} · 2/3CHCl3 show that the silver atom adopts a distorted tetrahedral geometry with the donor [TpPh2] coordinating in tridentate fashion. © 1998 Elsevier Science S.A. All rights reserved.