Silver(I) pyrazolates. Synthesis and X-ray and P-31-NMR characterization of triphenylphosphine complexes and their reactivity toward heterocumulenes

Silver(I) pyrazolate was reacted with triphenylphosphine, leading to the dinuclear [Ag-2(pz)(2)(PPh3)(2)] and [Ag-2(pz)(2) (PPh3)(3)] complexes (Hpz = pyrazole), which were extensively characterized by P-31-NMR methods and single-crystal X-ray analyses. Crystals of [Ag-2(pz)(2)(PPh3)(2)] are triclinic, space group P (1) over bar, with a = 9.567(2) Angstrom, b = 11.440(2) Angstrom, c = 10.073(2) Angstrom, alpha = 93.59(2)degrees, beta = 64.01(2)degrees, gamma = 107.24(2)degrees, Z = 1, and D-calc = 1.539 g.cm(-3); final R = 0.028 for 2532 independent reflections having F > 4 sigma(F). They contain centrosymmetric dimers with trigonally coordinated silver atoms, which are 3.870(1)Angstrom apart. Crystals of [Ag-2(pz)(2) (PPh3)(3)] are triclinic, space group P (1) over bar, with a = 9.752(2) Angstrom, b = 14.163(2) Angstrom, c = 20.450(2) Angstrom, alpha = 101.84(1)degrees, beta = 99.83(2)degrees, gamma = 100.68(2)degrees, Z = 2, and D-calc = 1.424 g.cm(-3); final R = 0.025 for 7075 independent reflections having F > 4 sigma(F). Each molecule contains two inequivalent silver ions, bearing one and two phosphines, respectively, and a Ag(mu-pz)(2)Ag ring with a rare twisted conformation. Both complexes readily react with heterocumulenes such as CS2, COS, CO2, and RNCO, affording new derivatives, the nature of which is dependent on the experimental conditions. Single-crystal X-ray analysis of [Ag(pz-CS2)(PPh3)(2)] has shown the unexpected S,S coordination of the pyrazolecarbodithioate fragment. Its crystals are triclinic, space group P (1) over bar, with a 10.329(4) Angstrom, b = 13.082(2) Angstrom, c = 14.284(3) Angstrom, alpha = 86.71(2)degrees, beta = 75.14(2)degrees, gamma = 74.79(2)degrees, Z = 2, and D-calc = 1.431 g.cm(-3); final R = 0.028 for 5179 independent reflections having F > 4 sigma(F).