Preparation, Structure, and Reactivity of Dipalladium(I) Complexes Containing the Carbanion 2-C6F4PPh2: Coexistence of Distinct, Noninterconverting Head-to-Head [Dipalladium(0/II)] and Head-to-Tail [Dipalladium(I)] Species

Heterometallic d8 -d10 Coupling of Rh(I) and M(0) (M=Pd, Pt) in a Sandwich Framework of π-Conjugated Ligands

A heterometallic M-M' bond formation is a key to construct atomically precise bimetallic clusters and materials. However, it is sometimes not straightforward to construct a heterometallic M-M' bond through conventional methods including redox condensation. Here, we found that a sandwich framework of π-conjugated unsaturated hydrocarbon ligands provides a unique coordination environment that facilitates unusual coupling of d⁸ Rh^I and d¹⁰ M⁰ (M=Pd, Pt). The molecular orbital analysis showed that the electron-accepting ability of the sandwich framework through back-donation allows the formation of a dσ-type Rh-Pd bond in a (d-d)¹⁸ electron system.

Metallophilic interactions: observations of the shortest metallophilicinteractions between closed shell (d10⋯d10, d10⋯d8, d8⋯d8) metal ions [M⋯M′ M = Hg(ii) and Pd(ii) and M′ = Cu(i), Ag(i), Au(i), and Pd(ii)]

The salt metathesis reaction of two equivalents of 8-lithioquinoline (C₆H₆NLi) with HgBr₂ afforded bis(quinoline-8-yl)mercury, [(C₆H₆N)₂Hg].

Tin(IV) Compounds with 2-C6F4PPh2 Substituents and Their Reactivity toward Palladium(0): Formation of Tin-Palladium Complexes via Oxidative Addition

The tin(IV) compounds Me_xSn(2-C₆F₄PPh₂)_4-x (1, x = 1; 2, x = 2) and ClSn(2-C₆F₄PPh₂)₃ (3) were obtained from the reactions of 2-LiC₆F₄PPh₂ with MeSnCl₃ (3:1), Me₂SnCl₂ (2:1), or SnCl₄ (3:1), respectively. The reactions of 2-LiC₆F₄PPh₂ with SnCl₄ in different stoichiometric ratios (4:1-1:1) gave 3 as the main product. Compound Cl₂Sn(2-C₆F₄PPh₂)₂ (4) was formed in the transmetalation reaction of 3 and [AuCl(tht)] but could not be isolated. 1 and 2 react with palladium(0) sources {[Pd(PPh₃)₄] and [Pd(allyl)Cp]} by the oxidative addition of one of their Sn-C_Aryl bonds to palladium(0) with formation of the heterobimetallic complexes [MeSn(μ-2-C₆F₄PPh₂)₂Pd(κC-2-C₆F₄PPh₂)] (5) and [Me₂Sn(μ-2-C₆F₄PPh₂)Pd(κ²-2-C₆F₄PPh₂)] (6) featuring Sn-Pd bonds. The reaction of 3 with palladium(0) proceeds via the oxidative addition of the Sn-Cl bond to palladium(0), thus furnishing the complex [Sn(μ-2-C₆F₄PPh₂)₃PdCl] (7) featuring a Sn-Pd bond and a pentacoordinate Pd atom. Transmetalation of Me_xSn(2-C₆F₄PPh₂)_4-x (x = 1-3) with [Pd(allyl)Cl]₂ gave Me_xClSn(2-C₆F₄PPh₂)_3-x and [Pd(allyl)(μ-2-C₆F₄PPh₂)]₂. For x = 1, the compound MeClSn(2-C₆F₄PPh₂)₂ (generated in situ) reacted with another 1 equiv of [Pd(allyl)Cl]₂ by the oxidative addition of the Sn-Cl bond to palladium(0) and the reductive elimination of allyl chloride, thus leading to [MeSn(μ-2-C₆F₄PPh₂)₂PdCl] (8). The reductive elimination of allyl chloride was also observed in the reaction of 3 with [Pd(allyl)Cl]₂, giving [Sn(μ-2-C₆F₄PPh₂)₃PdCl] (7). All compounds have been characterized by means of multinuclear NMR spectroscopy, elemental analysis, single-crystal X-ray diffraction, and selected compounds by ¹¹⁹Sn Mössbauer spectroscopy. Computational analyses (natural localized molecular orbital calculations) have provided insight into the Sn-Pd bonding of 5-8.

Cyclopalladated complexes containing 2-C6R4PPh2 ligands (R = H, F): one-electron electrochemical reduction leading to metal–carbon σ-bond cleavage via palladium(i)

Cyclopalladated complexes containing the 2-C₆F₄PPh₂ fragment have been prepared and their electrochemical reduction behaviour investigated.