Room Temperature Stable Organocuprate Copper(III) Complex

Abstract

The paramagnetic trigonal-planar copper complexes {K(18C6)}-[Cu II (OC(CH 3 )(CF 3 ) 2 ) 3 ] (2) and K[Cu II (OC(C 6 H 5 )(CF 3 ) 2 ) 3 ] (3) have been prepared and characterized, including X-ray crystallography, in 61% and 3% yields, respectively. The latter complex does not form preferentially, because CuBr 2 and KOC(C 6 H 5 )(CF 3 ) 2 ) 3 also form the diamagnetic complexes {K(18C6)}-[K 2 {Cu I (OC(C 6 H 5 )(CF 3 ) 2 ) 2 } 3 ] (4) and {K(18C6)}[Cu III (OC(C 6 H 4 )(CF 3 ) 2 ) 2 ] (5). These species were characterized by X-ray crystallography, UV−vis spectroscopy, 1 H, 13 C{ 1 H}, and 19 F{ 1 H} NMR spectroscopy, and elemental analysis. The unique organocuprate Cu(III) species with {O 2 C 2 } coordination was formed by ortho metalation of two phenyl rings, resulting in trans-{O 2 C 2 } coordination of Cu(III), and is stable at room temperature in the solid state and in dark solutions of THF.

K⋅⋅⋅F/O Interactions Bridge Copper(I) Fluorinated Alkoxide Complexes and Facilitate Dioxygen Activation

“…In another study, a trinuclear Cu I species, [24] with three linear [CuA C H T U N G T R E N N U N G (OCPhMe À groups and the non-encapsulated K + cations assemble a trinuclear Cu 3 core. [24] O 2 reaction stoichiometry: Exposure of solutions of 1, 2, and 3 in THF to O 2 at À78 8C resulted in the rapid generation of intensely colored species, the Cu/O 2 stoichiometries of which were determined manometrically. [25] Details of the error analysis are given in Table S7 in the Supporting Information.…”

“…The elongated bridging Cu À O alkoxide distances are comparable to a similar Cu1 À O8 alkoxide bond distance of 1.858(2) in 6 in which the bridging alkoxide distance is longer than the terminal alkoxide distance. [24] The two other coordination sites of each Cu II center are filled by a bidentate carbonate, with Cu1 À O2 and Cu1 À O3 distances of 1.978(2) and 2.003(2) , respectively. The Cu1···O1 distance to the next asymmetric unit is nonbonding at 2.511(2) , effectively resulting in a four-coordinate geometry for Cu II .…”

On the Way to a Trisanionic {Cu3O2} Core for Oxidase Catalysis: Evidence of an Asymmetric Trinuclear Precursor Stabilized by Perfluoropinacolate Ligands

“…[23] Reduced homoleptic Cu I complexeso ft he form K[Cu I (OR F ) 2 ], with af ully fluorinated ligand, (OC 4 F 9 ; 1)o rp artially fluorinated ligands( OC(C 6 H 5 )(CF 3 ) 2 ; 2 and OC(CH 3 )(CF 3 ) 2 ; 3) [24] (Scheme 3) react readily with O 2 .C omplexes 1-3 reduce O 2 to form the {(R F O) 6 Cu 3 (m-O 2 )} 3À trianionic species T OC4F9 , T OCPhMeF2 ,a nd T OCMeMeF2 ,r espectively,a t[ Cu I ] > 4mm.T hese speciesw ere characterized by UV/Vis spectroscopya nd manometry,a nd were the first trimeric species with exclusively O-donor ligands and the first overall trianionic{ Cu 3 (m 3 -O) 2 }s pecies. Notably,e x-tensiveK ···O and K···F interactions were observed in the solid state for these Cu I /fluorinated monodentate alkoxide com-plexes, [22,24] and they play an important role in the Cu/O 2 chemistry.W hen [18]crown-6 encapsulated the K + cation of 1-3 no reactivity with O 2 was observed under conditions for which the unencapsulated K + saltsr eacted quickly.T herefore, K···O andK ···F interactions facilitatea ssembly of the {Cu 3 (m 3 -O) 2 } cores and reductiono fO 2 . [24] Severalh eteroleptic Cu I -phosphine complexesw ith bridging fluorinated alkoxide compounds have also been reported.…”

“…[14] However,i nt he presence of PPh 3 (5 equiv) Tb -DKT oxidized the substrate to O=PPh 3 in 40 % yield (based on the trinuclearc omplex), which was indicative of electrophilic oxygen-atom transfer.T he partially-hydrogenated O-donor T OCPhMeF2 and T OCMeMeF2 [32] hydroxylate sp 2 -a nd sp 3hybridized CÀHb onds via an electrophilic oxygen atom. Fur-thermore, both the N-donor Tb -DKT [22] and O-donors T OC4F9 , T OCPhMeF2 ,a nd T OCMeMeF2 [32] have displayed nucleophilic oxygen atom reactivity by reactingw ith exogenous CO 2 to form CO 3 2À . Most recently it has been reported that T Me3 abstracts ah ydrogen atom from 5,6-isopropylidene ascorbic acid 10 6 times slower than independently generated O Me3 ,a nd that T nBu reacts 100-times slower than O nBu .…”

“…[18b] Extensivel igand fluorination reduces the p-donor character of the oxygen atom and potential ligand bridging in metal complexes. Less p-electron donation to the metal center can stabilize unusualh igh-oxidation states (e.g.,t he Cu III complex [K( [18]crown-6)] [Cu III (OC(C 6 H 4 )(CF 3 ) 2 ) 2 ]i ss table at room temperature) [22] or unusual spin states, such as high-spin square-planar Co II and Fe II complexes. [23] Reduced homoleptic Cu I complexeso ft he form K[Cu I (OR F ) 2 ], with af ully fluorinated ligand, (OC 4 F 9 ; 1)o rp artially fluorinated ligands( OC(C 6 H 5 )(CF 3 ) 2 ; 2 and OC(CH 3 )(CF 3 ) 2 ; 3) [24] (Scheme 3) react readily with O 2 .C omplexes 1-3 reduce O 2 to form the {(R F O) 6 Cu 3 (m-O 2 )} 3À trianionic species T OC4F9 , T OCPhMeF2 ,a nd T OCMeMeF2 ,r espectively,a t[ Cu I ] > 4mm.T hese speciesw ere characterized by UV/Vis spectroscopya nd manometry,a nd were the first trimeric species with exclusively O-donor ligands and the first overall trianionic{ Cu 3 (m 3 -O) 2 }s pecies.…”