Novel Di- and Trinuclear Palladium Complexes Supported by N,N′-Diphosphanyl NHC Ligands and N,N′-Diphosphanylimidazolium Palladium, Gold, and Mixed-Metal Copper–Gold Complexes
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- 作者：Pengfei Ai ; Christophe Gourlaouen ; Andreas A. Danopoulos ; Pierre Braunstein
- 刊名：Inorganic Chemistry
- 出版年：2016
- 出版时间：February 1, 2016
- 年：2016
- 卷：55
- 期：3
- 页码：1219-1229
- 全文大小：576K
- ISSN：1520-510X
文摘
The reaction of the trinuclear complex [Ag3(μ3-PCNHCP,κP,κCNHC,κP)2](OTf)3 (Ag3; PCNHCP = N,N′-bis(di-tert-butylphosphanyl)imidazol-2-ylidene) with [Pd(dba)2] afforded the trinuclear palladium complex [Pd3(μ3-PCNHCP,κP,κCNHC,κP)2](OTf)2 (Pd3) and the dinuclear palladium(I) complex [Pd2(μ2-PCNHCP,κP,κCNHC,κP)2](OTf)2 (Pd2). The assignment of the oxidation state of the metals in the mixed-valence Pd3 chain as Pd0–PdII–Pd0 was based on the reactivity of the complex with 2,6-dimethylphenyl isocyanide and density functional theory calculations. Reaction of PCNHCP with [PdMe2(tmeda)] afforded the palladium(II) complex [PdMe2(PCNHCP,κP,κCNHC)] (Pd-Me2), with PCNHCP acting as a bidentate ligand. The reaction of PCNHCP with [Pd(dba)2] led to a dinuclear palladium(0) complex [Pd2(μ2-PCNHCP,κP,κCNHC,κP)](dba) (Pd2-dba); attempted replacement of the remaining dba by PCNHCP failed. The imidazolium triflate PCHP, precursor to PCNHCP, was reacted with [Pd2(dba)3]·CHCl3 to give the (2 + 2) metalla-mesocyclic cationic palladium(0) complex [Pd2(μ2-PCHP,κP,κP)2] (PCHP-Pd2), which resisted further deprotonation of the imidazolium cation. In contrast, PCHP reacted with [AuCl(tht)] to give [Au2Cl2(μ2-PCHP,κP,κP)] (PCHP-Au2), in which one Au–Cl moiety is bound to each P donor. Further reaction of PCHP-Au2 with [Au{N(SiMe3)2}(PPh3)] afforded a mixture of the trinuclear [Au3(μ3-PCNHCP,κP,κCNHC,κP)2](OTf)3 (Au3) and [AuCl(PPh3)], while reaction with [CuMes]5, where Mes = 2,4,6-trimethylphenyl, resulted in a novel, centrosymmetric, heterometallic complex [Au2Mes2(Cu4Cl4)(PCHP,κP,κP)2] (PCHP-AuCu) featuring a new PCHP-AuMes metalloligand bridging a Cu···Cu diagonal of a Cu4Cl4 cubane via the P and AuMes functionalities.