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

Abstract

Seven E[Cu(OR)2] copper(I) complexes (E = K(+), {K(18C6)}(+) (18C6 = [18]crown-6), or Ph4P(+); R = C4F9, CPhMe(F)2, and CMeMe(F)2) have been prepared and their reactivity with O2 studied. The K[Cu(OR)2] species react with O2 in a copper-concentration-dependent manner such that 2:1 and 3:1 Cu/O2 adducts are observed manometrically at -78 °C. Analogous reactivity with O2 is not observed with the {K(18C6)}(+) or Ph4P(+) derivatives. Solution conductivity data demonstrate that these K[Cu(OR)2] complexes do not behave as 1:1 electrolytes in solution. The K(+) ions induce aggregation of multiple [Cu(OR)2](-) units through K⋅⋅⋅F/O interactions and thereby effect irreversible O2 reduction by multiple Cu centers. Bond valence analyses for the potassium cations confirm the dominance of the fluorine interactions in the coordination spheres of K(+) ions. Intramolecular hydroxylation of ligand aryl and alkyl C-H bonds is observed. Nucleophilic reactivity with CO2 is observed for the oxygenated Cu complexes and a Cu(II) carbonate has been isolated and characterized.

Well‐Defined Copper(I) Fluoroalkoxide Complexes for Trifluoroethoxylation of Aryl and Heteroaryl Bromides

“…Fewe xamples of structurally characterized fluorinated copper(I) alkoxide complexes are reported in the literature, [24,25] and this prompted us to conduct single-crystal X-ray crystallographic studies on our complexes (Figure 1). 2g)and may be stored indefinitely at À30 8 8C.…”

K+···Cπ and K+···F Non-Covalent Interactions in π-Functionalized Potassium Fluoroalkoxides

“…The Figure 1) [6,18,28,29]. Two K4O4 cuboid motifs are associated through bridging K···F interactions to generate a centrosymmetric macromolecular edifice containing eight potassium ions.…”

“…The concept of so-called secondary interactions, which are essentially weak donor-acceptor interactions between the cation and charge-neutral C π , halide, H, or other neutral atom or group of atoms, was highlighted in a landmark article by Ruhlandt-Senge and coworkers in 2010 [1]. This and other groups have in particular prepared many a compound of alkali metals (M) featuring one or more M + ···F [2][3][4][5][6] and, perhaps more prominently, M + ···C π (arene) [4,7] intramolecular interactions. Of note, the importance of M + ···C π (arene) in biological structures, supramolecular assemblies, and catalytic and ion transportation processes has long been established [8][9][10][11][12][13][14].…”

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

“…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. 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 .…”

“…An asymmetric {Cu 3 O 2 }s pecies, As T pinF ,w hich bears as tructure similar to multicopper oxidases, forms prior to full formation of the symmetric trinuclear core, Sy T pinF .T he trimer catalytically oxidizes para-hydroquinonet ob enzoquinone( af orm of oxidase chemistry).Scheme2.N-Donorligands that stabilize neutral (n = 0) and cationic {Cu 3 (m 3 -O) 2 } n + cores.Scheme3.Synthesis of Cu I /bis-alkoxide complexes 1-3 (see ref. [24]).…”