Heterolytic splitting of H–X bonds at a cationic (PNP)Pd center

Abstract

The (PNP)PdOTf complex is a suitable synthetic equivalent of the [(PNP)Pd](+) fragment in reactions with various HX substrates. The [(PNP)Pd](+) fragment either simply binds HX molecules as L-type ligands (X = NH(2), PCy(2), imidazolyl) or heterolytically splits the H-X bond to produce [(PN(H)P)Pd-X](+) (X = H, CCR, SR). DFT calculations analyze the relative energetics of the two outcomes and agree with the experimental data. Calculations also allow to assess the unobserved Pd(IV) isomer [(PNP)Pd(H)(2)](+) and validate its unfavourability with respect to the Pd(II) isomer [(PN(H)P)PdH](+).

A terminal palladium fluoride complex supported by an anionic PNP pincer ligand

“…The Pd-N distance of 1.996(5) Å in ( F PNP)PdF is among the shortest we have observed in any structurally analyzed (PNP)PdX complex; for comparison, the Pd-N distance is 2.015(5) Å in both ( F PNP)PdOAc [22] and ( Me PNP)PdCl [23]. The Pd-N distance is affected by the trans-influence of the ligand trans to it, as we discussed in a previous publication [24]. Fluoride is a weak trans-influence ligand and a short Pd-N distance trans to it is expected.…”

Phosphido pincer complexes of platinum: synthesis, structure and reactivity

“…As suggested by a reviewer the methylation of the phosphido P could be a viable reaction with formation of a cationic Pt(II) complex. 69 Further studies are underway to examine this issue. act both as a Lewis base or as an acid.…”

Metall‐Ligand‐Kooperation

“…Im Vergleich zu den aliphatischen PNP‐Liganden ist der Amid‐Stickstoff in Diarylamid‐PNP‐Komplexen deutlich weniger basisch, und es ist unwahrscheinlich, dass Metall‐Ligand‐Kooperation eine größere Rolle in solchen Systemen spielt. Zum Beispiel berichteten Ozerov et al., dass der Palladiumkomplex 38 mit einem Diarylamid‐PNP‐Liganden die heterolytische Spaltung von H‐X‐Bindungen (HX=H 2 , terminales Alkin, Thiol) unter Bildung von 39 bewirkt (Schema ) 43. Obwohl diese Reaktionen letztlich zu einer Addition der H 2 ‐Bindung an die Pd‐Amid‐Bindung führen, wurde der direkte Transfer eines Protons von H 2 zum Amid‐Stickstoff als unwahrscheinlich eingeschätzt.…”