Preparation and X-ray molecular structure of an unusal copper(I) polynuclear species: tetrakis(copper trifluoroacetate)dibenzene

Abstract

The preparation, some of the reactions with olefins, and the crystal and molecular structure of a unique polynuclear CuI-benzene complex are reported : C~4(F3CC02)4.2C,H,.

Triplet-state benzophenone-sensitized photoreduction of bis(acetylacetonato)copper(II): the generation and stability of copper(I) complexes

“…This indicates that olefins and polyethers coordinate with Cu(acac) so weakly that their complexes are readily decomposed by disproportionation or photolysis, or by both pathways. Indeed, it is well known that olefins form labile copper(1) complexes (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30). Similar photolysis in the presence of styrene was very slow, owing to the quenching of triplet state benzophenone by styrene.…”

Quantitative Evaluation of d–π Interaction in Copper(i) Complexes and Control of Copper(i)–Dioxygen Reactivity

“…[18] This assignment is supported by the 13 C NMR chemical shifts of the aromatic carbon atoms of the ligand sidearm of 1 Me in CD 2 Cl 2 , which are shifted to positions similar to those of the free ligand on addition of CD 3 CN (Table 4). Further studies are required for detailed discussion of the MLCT transitions.…”

“…Thus, the phenyl group is possibly swinging above the copper(i) ion as illustrated in Scheme 2, whereby the ortho (2-and 6-) and meta (3-and 5-) positions of the phenyl group become equivalent. The 1 H and 13 C NMR signals of the aromatic rings did not change at all, even at À80 8C, and this suggests that the energy barrier for the ring swinging above the copper(i) ion is very low. Table 4 summarizes the 13 C NMR data of the aromatic groups of the free ligands and the corresponding copper(i) complexes.…”

“…The Cu I ion in each complex has a distorted tetrahedral geometry consisting of the three nitrogen atoms (one tertiary amine nitrogen atom and two pyridine nitrogen atoms) and C 1 ÀC 2 of the phenyl ring of ligand sidearm, whereby the CuÀC distances of the copper±arene interaction significantly depend on the para substituents. The existence of the copper±arene interaction in a nonpolar organic solvent (CH 2 Cl 2 ) was demonstrated by the observation of an intense MLCT band around 290 nm, and the magnitude of the interaction was evaluated by detailed analysis of the 1 H and 13 C NMR spectra and the redox potentials E 1/2 of the copper ion, as well as by means of the ligand-exchange reaction between the phenyl ring and CH 3 CN as an external ligand. The thermodynamic parameters DH o and DS o for the ligandexchange reaction with CH 3 CN afforded a quantitative measure for the energy difference of the copper±arene interaction in the series of copper(i) complexes.…”

“…Apparently, the two 1 H and 13 C nuclei of the ortho-(2-and 6-) and meta-(3-and 5-) positions of the phenyl group of the ligand sidearm are magnetically equivalent. If the copper(i)--arene interaction in solution were fixed at the C 1 ÀC 2 moiety, as in the crystal structure, the 1 H and 13 C nuclei in the 2-and 3-positions would give rise to different peaks from those of 1 H and 13 C at the 6-and 5-positions, respectively. Thus, the phenyl group is possibly swinging above the copper(i) ion as illustrated in Scheme 2, whereby the ortho (2-and 6-) and meta (3-and 5-) positions of the phenyl group become equivalent.…”