19235-88-2Relevant articles and documents
A gas-phase study on the cyclometallation of a series of Cp*Ir(III) complexes bearing bidentate pyrimidine ligands
Becker, Yanik,Huber, Maximilian,Becker, Sabine,Sun, Yu,Niedner-Schatteburg, Gereon,Thiel, Werner R.
, (2021/09/20)
A concerted approach of synthesis and gas phase experiments characterizes the relative cyclometallation barriers of a series of cationic η5-Cp* iridium(III) compounds. The common feature of the investigated compounds is a bidentate N,N’-donor ligand possessing a pyridine site functionalized with a 5-butylpyrimidin-2-yl ring in the 2-position. In addition, the pyridine ring was functionalized with electron-donating or -withdrawing groups. The compounds were characterized by means of NMR and IR spectroscopy and elemental analysis. For the measurements of the relative barriers of the cyclometallation, collision-induced dissociation (CID) experiments were carried out, which revealed a clear dependence of the relative barriers from the nature and the position of the substituents at the pyridine ring could be worked out.
Single component N-O chelated arylnickel(II) complexes as ethene polymerisation and CO/ethene copolymerisation catalysts. Examples of ligand induced changes to the reaction pathway
Desjardins, Sylvie Y.,Cavell, Kingsley J.,Hoare, Jason L.,Skelton, Brian W.,Sobolev, Alexander N.,White, Allan H.,Keim, Wilhelm
, p. 163 - 174 (2007/10/03)
Arylnickel(II) phosphine complexes containing substituted N-O bidentate ligands, of the type [NiR(N-O)L] [N-O = 4-nitropyridine-2-carboxylate (4-NO2-pyca), R = 0-tolyl, L = PPh3; N-O = 2-pyrazinecarboxylate (pyzca), R = 0-tolyl, L = PPh3; and N-O = 4-methoxypyridine-2-carboxylate (4-MeO-pyca), R = 0-tolyl, L = PPh3] have been prepared and characterised. Single crystal X-ray studies of the complexes [Ni(0-tolyl)(pyca)PPh3], 1, and the isomorphous analogue [Ni(0-tolyl)(4-NO2-pyca)PPh3], 3, show the expected square planar coordination about the nickel centres, with the pyridine nitrogens being trans to the phosphine ligand for both compounds. The coordination spheres of the two complexes are very similar, no elongation of the Ni-N bond for complex 3, which contains the 4-NO2-pyca ligand, being evident. In complex 3 the 0-tolyl ligand is disordered over two sites indicating the presence, in the solid state, of two conformers in which the 0-methyl groups of 0-tolyl are located to either side of the coordination plane. The complexes with substituted pyca ligands form single component catalysts for the conversion of ethene to high molecular weight polyethene and for the copolymerisation of ethene and carbon monoxide to polyketone under mild conditions. The nature of the product, whether predominantly high molecular weight polymer or a mixture of polymer and lower oligomer, is dependent on the basicity of the N-O chelate ligand. From an NMR study of the effect of added ethene on the complex [Ni(0-tolyl)(4-NO2-pyca)PPh3], a mechanism involving alkene promoted ligand dissociation is suggested.
