Pd3(OAc)5NO2, an impurity in “Pd(OAc)2” {formally Pd3(OAc)6}, emerges as a serious issue in the synthesis of pure PdII complexes derived from Pd(OAc)2, for example in our C–H activation precatalyst, Pd(OAc)2(pip)2 (pip = piperidine). A previous proposal that nitrite anion can be formed by oxidation of CH3CN by metallic Pd and air, leading to cyclo(ortho)palladated complexes containing nitrite anion, e.g. Pd(NO2)(C^N)L (C^N = papaverine; L = CH3CN or DMSO) can be explained by Pd3(OAc)5NO2 acting as the nitrite source. Finally, photocrystallographic metastable linkage isomerisation and complete conversion to an oxygen-bound nitrito complex Pd(η1-ONO)(C^N)PPh3 has been observed

A multidentate and flexible diolefin-diphosphine ligand, based on the dibenzylidene acetone core, namely dbaphos (1), is reported herein. The ligand adopts an array of different geometries at Pt, Pd and Rh. At Pt(II) the dbaphos ligand forms cis- and trans-diphosphine complexes and can be defined as a wide-angle spanning ligand. (1)H NMR spectroscopic analysis shows that the β-hydrogen of one olefin moiety interacts with the Pt(II) centre (an anagostic interaction), which is supported by DFT calculations. At Pd(0) and Rh(I), the dbaphos ligand exhibits both olefin and phosphine interactions with the metal centres. The Pd(0) complex of dbaphos is dinuclear, with bridging diphosphines. The complex exhibits the coordination of one olefin moiety, which is in dynamic exchange (intramolecular) with the other "free" olefin. The Pd(0) complex of dbaphos reacts with iodobenzene to afford trans-[Pd(II)(dbaphos)I(Ph)]. In the case of Rh(I), dbaphos coordinates to form a structure in which the phosphine and olefin moieties occupy both axial and equatorial sites, which stands in contrast to a related bidentate olefin, phosphine ligand ("Lei" ligand), in which the olefins occupy the equatorial sites and phosphines the axial sites, exclusively.