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 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 {PR3} and [Tp(Ph2)] Ag{PMePh2} compounds. The tricyclohexylphosphine (PCy3) is able to displace PPh3 and PBz(3) from the coordination sphere of silver(I), yielding the derivative [Tp(Ph2)] 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 [Tp(Ph2)] and CNR (R=Cy or Bu-t) yields the air-stable neutral compounds [Tp(Ph2)]Ag(CNR). When the reaction between [Tp(Ph2)] and Ag(O3SCF3) is carried out in tetrahydrofuran at -70 degrees 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(2)PzH)(3)Ag](O3SCF3).(H2O)(2) was obtained from the reaction solution. All the derivatives were characterized through elemental analyses, spectral data (IR,H-1, P-31 and C-13 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{PPh3} 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. (C) 1998 Elsevier Science S.A. All rights reserved.