Cyclometalated complexes of palladium(II) and platinum(II) with N-benzyl- and N-(phenylethyl)-.alpha.-benzoylbenzylideneamine. Delocalization in the cyclometalated ring as a driving force for the orthometalation

Synthesis, characterization and solid state structures of thiosemicarbazone palladacycles: Influence of hydrogen bonding in the molecular arrangement

“…All bond distances are within the expected range, with lengthening of the Pd-N bond due to the trans influence of the phosphine ligand, which is reflected in the Pd(1)-N(1), 2.039(6) Å 4a and 2.020(7) Å , 4c, distances (cf. sum of the covalent radii for palladium and nitrogen, 2.01 Å [41]), and shortening of the Pd-C bond with to the expected value of 2.081 Å [41], as has been observed before [42,43], Pd (1) metallated units, in compound 4a they are fixed in a nearly co-planar parallel mode (angle between planes 3.17(0.03)°), and at 4.57(0.03)°and 4.12(0.03)°with the P-C-C-C-P plane, so that the entire molecule may envisaged as planar with the phosphine phenyl rings jutting out from the molecular plane (see Fig. 8), whereas in compound 4c the two metallated moieties are at an angle of 69.10°.…”

Palladium(II) complexes with P,N‐ and C,N‐ligands as catalysts for the Heck reaction

“…The reason for the strong tendency of Schiff bases to form endo-metallacycles was proposed to be the aromatic character of the conjugated π -system, formed by the Materials, Nanoscience and Catalysis aryl ring, the imine double bond and a filled d orbital of the metal with appropriate symmetry. 23 For complexes 1 and 2, crystals suitable for X-ray analysis were obtained. Both palladacycles (1 and 2) were found to form dimeric, acetate-bridged, nearly C 2 -symmetric complexes (Figs 2 and 3).…”

Cyclometallated platinum complexes with heterocyclic ligands

“…The lower tendency of the furane derivative towards cyclometallation is attributed to the lower degree of aromaticity of furane (16 kcal/mol) versus benzene (36 kcal/mol) or thiophene (29 kcal/mol) [9]. The aromaticity of a system containing a fivemember endo-metallacycle fused with an aryl ring has been reported as the main driving force for the formation of platinum (II) and palladium (II) endo-metallacycles [10].…”