Silver(I) Pyrazolates. Synthesis and X-ray and (31)P-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)(PPh(3))(2)] and [Ag(2)(pz)(2) (PPh(3))(3)] complexes (Hpz = pyrazole), which were extensively characterized by (31)P-NMR methods and single-crystal X-ray analyses. Crystals of [Ag(2)(pz)(2)(PPh(3))(2)] are triclinic, space group P&onemacr;, with a = 9.567(2) Å, b = 11.440(2) Å, c = 10.073(2) Å, 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 > 4sigma(F). They contain centrosymmetric dimers with trigonally coordinated silver atoms, which are 3.870(1) Å apart. Crystals of [Ag(2)(pz)(2) (PPh(3))(3)] are triclinic, space group P&onemacr;, with a = 9.752(2) Å, b = 14.163(2) Å, c = 20.450(2) Å, 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 > 4sigma(F). Each molecule contains two inequivalent silver ions, bearing one and two phosphines, respectively, and a Ag(&mgr;-pz)(2)Ag ring with a rare twisted conformation. Both complexes readily react with heterocumulenes such as CS(2), COS, CO(2), and RNCO, affording new derivatives, the nature of which is dependent on the experimental conditions. Single-crystal X-ray analysis of [Ag(pz-CS(2))(PPh(3))(2)] has shown the unexpected S,S coordination of the pyrazolecarbodithioate fragment. Its crystals are triclinic, space group P&onemacr;, with a = 10.329(4) Å, b = 13.082(2) Å, c = 14.284(3) Å, 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 > 4sigma(F).