Nature of the Coordination Bond in Metal Complexes of Substituted Pyridine Derivatives. VI. Electronic Spectra of Some Complexes of Copper(II)

Abstract

The electronic spectra of some substituted pyridine complexes of copper(II) have been studied. The effects of bonding on the spectroscopic data are discussed, and compared with the Rπ values determined from infrared measurements.

The Stronger the Better: Donor Substituents Push Catalytic Activity of Molecular Chromium Olefin Polymerization Catalysts

“…A similar change in activity by additional para-N-donors is observed for the other groups of catalysts like indenyl-quinolyl complexes (21,14,15), cp complexes (C, 16, 17) and thiophene fused cp complex 9 as well. The positive effects of donor substituents at the pyridine and indenyl or cp moiety regarding the catalytic activity seem to be additive to some extent.…”

“…A similar change in activity by additional para-N-donors is observed for the other groups of catalysts like indenyl-quinolyl complexes (21,14,15), cp complexes (C, 16, 17) and thiophene fused cp complex 9 as well. The positive effects of donor Triisobutylaluminum, a = g PE mmol À 1 h À 1 bar À 1 , b: intrinsic viscosity, c: Mv calculated with Mark-Houwink equation from intrinsic viscosity with K = 6.2 • 10 À 4 • dL g À 1 α [41] = 0.7, d: 1-hexene content determined by 1 H NMR spectroscopy of PE in tetrachloroethane at 120 °C, e: crystallinity of PE.…”

“…All other complexes (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) show a similar behaviour: An increased donor strength of the N-donor ligand leads to a shift of the absorption bands to lower energies (Table S1, Supporting Information) and the colour of the complexes shifts from green (7, 20, 21, 23, C: no 4-substituent) to turquoise (8, 10-13, 14, 15)or blue (9, 16, 17, 4-amino substituent). Complex 18 and 19 have a bright green colour due to some additional strong absorption band around 400 nm caused by the dimethylaniline substituent.…”

“…It is well known that the basicity of aromatic donors such as pyridine has an influence on its coordination behaviour, the metal-nitrogen bond length and the complex stability. [11][12][13][14][15][16][17][18] The basicity is therefore used as a measure of donor strength of the aromatic N-donors. The basicity of pyridine is mostly effected by inductive (I) or mesomeric (M) effects.…”

Tuning of the Properties of Transition-Metal Bispidine Complexes by Variation of the Basicity of the Aromatic Donor Groups

“…There are many examples in the literature that deal with a systematic study of substitution effects of pyridine moieties as a simple ligand or as part of a more complex ligand system on the pyridine-to-metal bond strength, ,− and there have also been reports of correlations of Hammett parameters with electrochemical data . The correlation of the Hammett coefficients with the half-wave potentials of substituted metal complexes is not limited to a substitution of aromatic donor moieties. , A linear relationship was reported of the Hammett coefficients and half-wave potentials of the cobalt(III) complexes of apically substituted hexaaza-cage ligands, which can be explained by either a through-space Coulombic mechanism or an interaction through the ligand’s σ framework …”