Synthesis, characterization and copper chemistry of a non-symmetric phenanthroline ligand: 2-Methyl-9-(3,5-dimethyl-N-pyrazolylmethyl)-1,10-phenanthroline

Abstract

The synthesis of an unsymmetrical phenanthroline based ligand, 2-methyl-9-(3,5-dimethylpyrazolylmethyl)-1,10-phenanthroline (L), and its cupric [Cu(II)] (1) and cuprous [Cu(I)] (2) complexes, are reported. The X-ray structures of each of these Cu complexes show distinct changes in coordination environments consistent with the geometrical preferences of the two oxidation states. In the solid state the Cu(II) complex (1) adopts a geometry best described as trigonal bipyramidal, while the Cu(I) complex (2) consists of a single dicationic dimer in which the ligand bridges between two copper ions, separated by 4.26 Å. The two Cu(I) coordination sites differ in 2 with one copper center complexed in a trigonal planar geometry and the other copper in a distorted tetrahedral environment; the latter coordination results from an additional CH 3 CN ligand. Complex 1 exhibits a reversible redox process at −0.34 V vs. Fc/Fc + in CH 3 CN, attributable to the Cu 2+ / Cu + couple, while the dimeric Cu(I) complex (2) is resistant to oxidation on the CV timescale. Over minutes however, complex 1 does oxidize in the presence of dioxygen to 2 in CH 3 CN.

Syntheses and Structures of Mononuclear, Dinuclear and Polynuclear Silver(I) Complexes of 2-Pyrazole-Substituted 1,10-Phenanthroline Ligands

“…Phen derivatives with pendant arms of functional group(s) are of special importance for organic, inorganic and supramolecular chemistry because they can serve as versatile building blocks for the construction of complex systems with a variety of applications. A large number of 2-mono- or 2,9-disubstituted 1,10-phenanthroline derivatives have been synthesized, and their coordination chemistry toward different metal ions has been extensively studied at the solid state and in solution . Recently, we have designed and synthesized some 2-pyrazole-substituted 1,10-phenanthroline ligands and their nickel(II) complexes as precatalysts for ethylene oligomerization/polymerization .…”