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

Abstract

The interaction between Ag(O 3SCF 3), trialkyl- or trialkyl-phosphineligands (PR 3: R = phenyl, o- m- and p-tolyl, benzyl; PMePh 2), and the anionic N 3-donor tris(3,5-diphenylpyrazol-1-yl)borate [Tp Ph2] in tetrahydrofuran or methanol gives new air-stable and highly soluble 1:1 [Tp Ph2]Ag{PR 3} and [Tp Ph2]Ag{PMePh 2} compounds. The tricyclohexylphosphine (PCy 3) is able to displace PPh 3 and PBz 3 from the coordination sphere of silver(1), yielding the derivative [Tp Ph2]Ag{PCy 3}. In contrast, imidazole, 1-methylmercaptoimidazole, 1,10-phenanthroline and 2,9-dimethyl-1,10-phenanthroline are not able to displace either phosphine or [Tp Ph2] from the coordination center. Reaction of Ag(O 3SCF 3) with 1 equiv. of [Tp Ph2] and CNR (R = Cy or Bu 1) yields the air-stable neutral compounds [Tp Ph2]Ag(CNR). When the reaction between [Tp Ph2] and Ag(O 3SCF 3) 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-Ph 2PzH) 3Ag](O 3SCF 3)·(H 2O) 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 [Tp Ph2]Ag{PPh 3} and [Tp Ph2]Ag{PBz 3}·2/3CHCL 3 show that the silver atom adopts a distorted tetrahedral geometry with the donor [Tp Ph2] coordinating in tridentate fashion.