Coinage Metal Complexes of Tris(pyrazolyl)methanide-Based Redox-Active Metalloligands

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• 作者：Sandra Gonz谩lez-Gallardo ; Istemi Kuzu ; Pascual O帽a-Burgos ; Tanja Wolfer ; Cong Wang ; Karl W. Klinkhammer ; Wim Klopper ; Stefan Br盲se ; Frank Breher
• 刊名：Organometallics
• 出版年：2014
• 出版时间：February 24, 2014
• 年：2014
• 卷：33
• 期：4
• 页码：941-951
• 全文大小：521K
• 年卷期：v.33,no.4(February 24, 2014)
• ISSN：1520-6041

文摘

A series of coinage metal complexes containing the redox-active metalloligands [RuCp^X(魏³N-Tpmd)] {魏³N-Tpmd = 魏³N-[C(pz)₃] with pz = pyrazolyl; [RuCp(Tpmd)] (2a) and [RuCp*(Tpmd)] (2b)} are presented. 2a and 2b are isolable, relatively stable compounds, despite the fact that they feature a 鈥渘aked鈥?carbanion at the bridgehead position of the 魏³N-coordinated tris(pyrazolyl)methanide ligand scaffold. As expected, both complexes act as 魏¹C ligands toward coinage metal fragments to yield dinuclear complexes of the general formula [RuCp^X(渭-Tpmd){MX}] (渭-Tpmd = 渭-魏¹C:魏³N-[C(pz)₃]; M = Au, X = Cl, Cp^X = C₅H₅ (3a) or C₅Me₅ (3b); M = Au, X = CN, Cp^X = C₅H₅ (4a) or C₅Me₅ (4b); M = Cu, X = OC(O)Me, Cp^X = C₅H₅ (5a); M = Cu, X = Si(SiMe₃)₃, Cp^X = C₅H₅ (6a) or C₅Me₅ (6b); M = Ag, X = SC(S)NEt₂, Cp^X = C₅H₅ (7a), M = Au, X = C鈮鈥揂r, Cp^X = C₅H₅ {Ar = C₆H₅ (8a), 4-NH₂-C₆H₄ (9a), 3,5-(CF₃)₂-C₆H₃ (10a)}). All complexes under study were fully characterized by common spectroscopic techniques; the structural parameters of 2a, 3a, 5a, 6a, 7a, and 10a were determined by X-ray diffraction. Coordination of the {MX} fragment leads to electronic effects on the metalloligand unit, as reflected by the corresponding ¹H and ¹³C NMR spectra. Density functional theory calculations were performed in order to elucidate a conceivable interplay between the metal atoms. The bonding characteristics within the {MX} fragment are only marginally affected upon electronic excitation of the ruthenium-based metalloligand. However, some effect of the influence of {MX} on the E⁰_1/2(Ru^II/Ru^III) value was detected with the aid of cyclic voltammetry measurements. A strong Lewis-acidic metal fragment such as GaCl₃ (11a) leads to an E⁰_1/2 value of 0.37 V, while electron-richer coinage metal fragments facilitate the oxidation of the ruthenium center significantly (E⁰_1/2 = 0.14鈥?.23 V). This dependence suggests an interaction between both metals due to their close spatial proximity.