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 AgNO(3), monodentate tertiary phosphanes PR(3) (PR(3) = P(C(6)H(5))(3), P(o-C(6)H(4)CH(3))(3), P(m-C(6)H(4)CH(3))(3), P(p-C(6)H(4)CH(3))(3), PCH(3)(C(6)H(5))(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 ((1)H, (19)F and (31)P) NMR spectroscopy. Solid state structures of the potassium salts K[H(2)B(3-(NO(2))pz)(2)] and K[H(2)B(3-(CF(3))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 [H(2)B(3-(NO(2))pz)(2)]Ag[P(C(6)H(5))(3)](2) and [H(2)B(3-(NO(2))pz)(2)]Ag[P(p-C(6)H(4)CH(3))(3)] have pseudo tetrahedral and trigonal planar silver sites, respectively. The bis(pyrazolyl)borate ligand acts as a kappa(2)-N(2) donor. The nitro-substituents are coplanar with the pyrazolyl rings in all these adducts indicating efficient electron delocalization between the two units. The [H(2)B(3-(CF(3))pz)(2)]Ag[P(C(6)H(5))(3)] complex has been obtained from re-crystallization of {[H(2)B(3-(CF(3))pz)(2)]Ag[P(C(6)H(5))(3)](2)} in a dichloromethane-diethyl ether solution; it is a three-coordinate, trigonal planar silver complex.

Copper(I) Isocyanide and Phosphane Complexes of Fluorinated Mono‐ and Bis(pyrazolyl)borates

“…[19] The Ndonor/copper ion/C-or P-based co-ligand (1:1:2) complexes 4-6 were obtained in high yield from the reaction between one equivalent of the potassium salt K[H 2 B{3-(CF 3 )pz} 2 ], an equimolar quantity of [Cu(CH 3 CN) 4 ]PF 6 or CuI, and two equivalents of triphenylphosphane, tert-butyl isocyanide, or cyclohexyl isocyanide (Scheme 2), in acetonitrile solution, at room temperature. The stoichiometry of the compounds was not affected by reducing (1 equiv.)…”

“…Indeed, [{HB [3,5- 6 ]DMSO solution shows a single broad signal at δ = -0.85 ppm at 293 K in the range typical for bis(phosphane) species, [20,42,43] in accordance with the crystallographic data. The 13 [19,37] The broad resonances observed in the range δ = 139.90-140.30 ppm in the 13 C NMR spectra of 2 and 3 can be assigned to the isocyanide carbons. These values can be compared to the 13 C isocyanide carbon resonances at δ = 153.40 and 154.02 ppm in free CNtBu and CNCy, respectively.…”

“…[17] An area of particular interest to us has been the effects of electron-withdrawing substituents on scorpionates and their metal adducts. [1,4,18,19] Accordingly, we have developed and isolated a variety of fluorinated tris-and bis(pyrazolyl)borate ligands, as well as rare mono(pyrazolyl)-borates. For example, we recently reported the first successful synthesis of the 5-substituted pyrazolylborate anion [H 3 B{5-(CF 3 )pz}]…”

Unsymmetrical 3- and 5-substituted bis(pyrazolyl)borate system

“…Generally, the 3-and 5-trifluoromethylpyrazole regioisomers can be distinguished on the basis of 19 F chemical shift [18]. The 19 F NMR spectrum of Na[H 2 B(3-(CF 3 )pz)(5-(CF 3 )pz)] in DMSO exhibits two singlets at À56.52 and À59.14, the first being attributable to 5-trifluoromethylpyrazole [16,19] and the second in the expected region of 3-trifluoromethylpyrazole [17,19]. Overall, we describe a systematic route to an asymmetrically substituted bis(pyrazolyl)borate ligand and the isolation of its silver(I) adduct supported by two phosphine donors.…”

“…We have also synthesized a 3-substituted dihydrobis(pyrazolyl)borate, 2 ], by treating KBH 4 with 3-(trifluoromethyl)pyrazole at 110°C [17].…”