Silver(I) Pyrazolates. Synthesis and X-ray and ³¹P-NMR Characterization of Triphenylphosphine Complexes and Their Reactivity toward Heterocumulenes

Abstract

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).

New copper(I) and silver(I) triazolato-complexes: Synthesis, reactivity and catalytic activity in olefin cyclopropanation

“…The polymeric nature of this derivative can be tentatively assumed from its remarkable insolubility in all organic solvents and from its reactivity, comparable to that of formerly reported pyrazolate and imidazolate silver(I) coordination compounds [19]. To prove this assumption, treatment of 2 with PPh 3 in CH 2 Cl 2 was exploited and, as already observed with the analogous [Ag(pz)] n species (pz = pyrazolate) [20], resulted into the cleavage of the polymeric chain and formation of the binuclear [Ag(H 2 L 1 )(PPh 3 )] 2 compound (3), whose nature was confirmed by an X-ray analysis (see below). The single resonance at 6.44 ppm in the 31 P NMR spectrum of 3 was clearly attributed to the two phosphines bonded to the Ag(I) centres.…”

Synthesis and ligand properties towards gold and silver of the ferrocenylamidobenzimidazole ligand

“…The Ag-P distance, 2.3530(5) Å , is similar to that reported for the complex [Ag{HB(3,5-Me 2 pz) 3 }(PMePh 2 )] (2.336(2) Å ) [30] but shorter than those found in [Ag 3 (lbim) 3 (19) Å for the four-coordinated silver atoms) [28,29] or other tetrahedral silver complexes such as [Ag(dppe) 2 ]NO 3 (range 2.488(3)-2.527(3) Å ) [32]. In addition, complex 6 displays several intra-and intermolecular hydrogens bonds N-HÁ Á ÁO, C-HÁ Á ÁO and C-HÁ Á ÁF, that are summarised in Table 4. DFT calculations [33] (ADF program [34]; see Computational section for details) were performed in order to understand the preference for the dimeric arrangement consisting of two complex cations and two triflate ions.…”

“…The cyclopentadienyl rings deviate slightly from an eclipsed geometry [torsion angle C(1)-X(1)-X(2)-C(7) 4.6°(X(1) and X(2) represent the centroids The Ag-N distance, 2.1840(16) Å , is shorter than those found in some tetracoordinated silver complexes, such as [Ag 3 (l-bim) 3 (PPh 3 ) 5 ] (from 2.290(5) to 2.349(5) Å for the four-coordinated silver atoms) [28], [Ag 2 (pz) 2 (PPh 3 ) 3 ] (2.295(2) and 2.323(2) Å for the four-coordinated silver atom) [29], [Ag{HB(3,5-Me 2 pz) 3 }(PMePh 2 )] (from 2.316(6) to 2.336(5) Å ) [30] or the complexes [AgX{Fe[C 5 H 4 CH(pz) 2 ] 2 }] n (X = BF 4 , PF 6 , SO 3 CF 3 and SbF 6 ) (from 2.225(3) to 2.420(4) Å ) [31].…”

Deposition of Silver Thin Films Using the Pyrazolate Complex [Ag(3,5‐(CF3)2C3HN2)]3

“…The structure of this complex appears to be analogous to that of the closely related [(2,4,6-collidine)Ag(tfpz)] 2 [27] and phosphine adduct [Ag 2 (pz) 2 (PPh 3 ) 2 ], [28] for which no close intermolecular Ag_Ag contact was observed. Meanwhile, more detailed structural analysis on [(2,4,6-collidine)Ag(tfpz)] 2 revealed formation of both the half-boat or the flattened chair conformations for its Ag 2 core structure, indicating only a minor difference in the relative thermodynamic stabilities of its conformational isomers.…”