Resolution and characterization of helicate dimer and trimer complexes of 1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)propane with copper(i)

Abstract

Complexation of copper(I) with the binucleating ligand, 1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)propane, mphenpr, result in formation of helical dimers, [Cu2(mphenpr)2](2+). The resolution of the enantiomeric forms of the dimers has been carried out with Δ-[As(cat)3](-) as resolving agent and X-ray structures for two compounds, P-[Cu2(mphenpr)2](Δ-[As(cat)3])2 and P-[Cu2(mphenpr)2](Δ-[As(cat)3])2·4(CH3CN), are reported. The rate of racemization in poorly-coordinating solvents has been examined by (1)H NMR, and is slow. At saturating concentrations of [[Cu2(mphenpr)2](2+)] in acetonitrile, crystals of the helical trimeric complex [Cu3(mphenpr)3](ClO4)3 are obtained. The X-ray structure of the trimer is reported. This species has also been resolved. As with the helical dimer, racemization in poorly-coordinating solvents is slow, and circular dichroism and (1)H NMR spectra are reported. The absolute configuration of the resolved complex, P-[Cu3(mphenpr)3](Δ-[As(cat)3])3, has been determined by X-ray crystallography.

Hydroxyl Radical Generation and DNA Nuclease Activity: A Mechanistic Study Based on a Surface‐Immobilized Copper Thioether Clip‐Phen Derivative

“…In fact, the 1 H NMR spectrum in deareated C 2 D 2 Cl 4 presented in Figure S6 of the Supporting Information shows a complex pattern of signals, in addition to paramagnetic residues due to the fast oxidation of the cuprous complex in solution, likely by traces of oxygen. The aliphatic (3.3–3.7 ppm) and some aromatic (7.6–7.8 ppm) protons show a diastereotopic behavior in solution because of the formation of a helical bimetallic complex, which coexists with the monometallic complex in a dynamic equilibrium, as reported for several copper(I) compounds containing rigid bidentate ligands …”

Steric and Electronic Factors Affecting the Conformation of Bimetallic CuI Complexes: Effect of the Aliphatic Spacer of Tetracoordinating Schiff‐Base Ligands

“…We carried out the exchange of the non-chiralC lO 4 À ,b yt he enantiomerically pure (D)[As V (cat) 3 ] À (cat = catecholate)f or all the complexes (Figures S5-S9, Supporting Information). [34] The splitting of the aromatic protons ignals of the bimetallic species was observed only for [Cu I (L 2 )] 2 2 + (Figure 2, black spectrum). The counterion exchangep roduces the shift in all the protons, in which the mosta ffected were the imine,H 5, (Dd = À0.212 ppm), and the aliphatic protons of the spacer (Dd = À0.195 ppm).…”

“…Previously,w eh ave reportedt he effect of an odd aliphatic spacer on the stability of ab imetallic copper(I) helicate, [Cu I (mphenpr)] 2 2 + ,i nw hich the ligand mphenpr consists of two phenanthroline units linked by ap ropylb ridge. [33,34] According to the odd-even rule, the propyl spacer should promote the formation of am esocate. However,a so bserved in solid and solution phases,t he helical conformationi sf avored by stabilization involving p-p-interactionsb etween adjacent phenanthroline groups (closest interplanar distance 3.37 ).…”

Heteroleptic copper phenanthroline complexes in motion: From stand-alone devices to multi-component machinery

“…M (K) interconversion of a copper(I) pyridine-imine complex was monitored in methanol [79]. The dissociation kinetics of bis(2,9-dialkylphenanthroline)cop per(I) complexes was measured within dimeric chiral helicates [80]. Whereas at 300 K and in d 2 -TCE as a non-coordinating solvent the process was very slow (k 300 = 6.3 Â 10 À6 s À1 ), it could be greatly accelerated by acetonitrile and upon heating.…”