K×××F/O interactions bridge copper(I) fluorinated alkoxide complexes and facilitate dioxygen activation

Article abstract of DOI:10.1002/chem.201204275

Seven E[Cu(OR)₂] copper(I) complexes (E=K⁺, {K(18C6)}⁺ (18C6=[18]crown-6), or Ph₄P⁺; R=C₄F₉, CPhMe^F₂, and CMeMe ^F₂) have been prepared and their reactivity with O ₂ studied. The K[Cu(OR)₂] species react with O₂ in a copper-concentration-dependent manner such that 2:1 and 3:1 Cu/O ₂ 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. Copyright

Full text of DOI:10.1002/chem.201204275

DOI: 10.1002/chem.201204275
K···F/O Interactions Bridge Copper(I) Fluorinated Alkoxide Complexes and
Facilitate Dioxygen Activation
June S. Lum,[a] Laleh Tahsini,[a] James A. Golen,[b, c] Curtis Moore,[c]
Arnold L. Rheingold,[c] and Linda H. Doerrer*[a]
Abstract: Seven E[Cu(OR)2] copper(I)
Solution conductivity data demonstrate
that these K[Cu(OR)2] complexes do
not behave as 1:1 electrolytes in solu-
tion. 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 dom-
inance of the fluorine interactions in
the coordination spheres of K+ ions.
Intramolecular hydroxylation of ligand
complexes
(E=K+,
{KACTHNGUTERNNUG
(18C6)}+
(18C6=[18]crown-6), or Ph4P+; R=
C4F9, CPhMeF , and CMeMeF ) have
2
2
been prepared and their reactivity with
O2 studied. The K[Cu(OR)2] species
react with O2 in a copper-concentra-
tion-dependent manner such that 2:1
and 3:1 Cu/O2 adducts are observed
manometrically at ꢀ788C. Analogous
reactivity with O2 is not observed with
ꢀ
aryl and alkyl C H bonds is observed.
Nucleophilic reactivity with CO2 is ob-
served for the oxygenated Cu com-
plexes and a CuII carbonate has been
isolated and characterized.
ꢀ
Keywords: C H activation · cop-
per · dioxygen reactivity · fluorinat-
ed ligands · K···F/O interaction
the {KACHTUNGTRENNUNG
(18C6)}+ or Ph4P+ derivatives.
Introduction
metallic[8] CuII complexes with partially fluorinated and non-
fluorinated alkoxides have also been previously synthesized.
Although numerous syntheses exist for CuI alkoxide com-
plexes, prior to this report there had been only one report
of their reactivity with O2, in which non-fluorinated alkoxide
{Cu(OR)}n species reacted with O2 to give ligand-derived al-
dehydes or ketones in low yields.[9]
Homoleptic complexes of 3d transition metals, including
FeII,[10] FeIII,[10b] CoII,[10a,11] NiII,[12] and CuII,[11,13] have been
prepared with completely fluorinated aryloxide and alkoxide
ligands. These aryloxides and alkoxides are medium-field li-
gands, such as OHꢀ or Fꢀ, from UV/Vis spectroscopic[10–13]
and DFT[10b] studies. Ligand fluorination also reduces bridg-
ing in metal complexes due to the diminished basicity of the
O donor atom, resulting in the formation of discrete mono-
meric species.[10,11] Such fluorinated ligands should be ideal
for stabilizing transition metals, even transiently, in high oxi-
The dioxygen reactivity of CuI complexes and the oxidative
properties of the resulting Cu/O2 species have gained wide-
spread attention in small-molecule catalysis[1] and biologi-
cal[2] systems. Distinct oxygenated products are produced
from one-, two-, and four-electron reduction of dioxygen by
CuI complexes, leading to superoxide, peroxide, and oxide
species. The majority of CuI complexes used to generate
well-characterized oxygenated species in biomimetic studies
contain aromatic nitrogen-donor ligands (pyrazole, pyridine,
and imidazole) and ligands with aliphatic amine groups.[3]
ꢀ
Herein, we report that O2 reduction and subsequent C H
hydroxylation chemistry can be achieved with CuI bound to
oxygen-donor, fluorinated alkoxide ligands as well. Hetero-
II
I [4]
II
II [5]
I[6]
bimetallic Ba Cu , Ba Cu , and AlIII Cu complexes
ꢀ
ꢀ
ꢀ
with partially fluorinated alkoxides and hetero-[7] and homo-
ꢀ
dation states for C H activation studies in which intramo-
ꢀ
lecular C H activation is less likely or impossible. Extend-
[a] Dr. J. S. Lum, Dr. L. Tahsini, Prof. Dr. L. H. Doerrer
Department of Chemistry, Boston University
590 Commonwealth Avenue, Boston, MA 02215 (USA)
Fax : (+1)617-353-6466
ing our studies to CuI, we have synthesized a series of CuI
alkoxide complexes with varying degrees of ligand fluorina-
tion, OC4F9, OCPhMeF , and OCMeMeF , and studied their
2
2
O2 reactivity. The extensive K+–ligand interactions observed
E-mail: doerrer@bu.edu
are demonstrated to effect dioxygen reduction and subse-
[b] Prof. Dr. J. A. Golen
2ꢀ
ꢀ
quent C H activation or CO3 formation by assembling
Department of Chemistry and Biochemistry
University of Massachusetts, Dartmouth
285 Old Westport Road, North Dartmouth, MA 02747 (USA)
polynuclear {Cun} units in solution.
[c] Prof. Dr. J. A. Golen, Dr. C. Moore, Prof. Dr. A. L. Rheingold
Department of Chemistry and Biochemistry
University of California, San Diego
Results and Discussion
9500 Gilman Drive, La Jolla, CA 92093 (USA)
Syntheses: A modified alcoholysis route[10a,11] was used to
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201204275.
prepare the homoleptic CuI compounds (Scheme 1). The
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Chem. Eur. J. 2013, 19, 6374 – 6384

FULL PAPER
Scheme 1. Syntheses of CuI fluorinated alkoxide complexes. 18C6=
[18]crown-6, mes=mesityl.
Figure 1. ORTEP diagram of complex 1, showing two K···F interactions
in the solid state per molecule (dotted lines to F ellipsoids). Ellipsoids
are shown at the 50% probability level.
salt, KOC4F9, has been reported previously.[4,14] The potassi-
um salts of the ligands KOCPhMeF and KOCMeMeF were
2
2
synthesized from the reaction of HOR with KH. Three
anionic CuI complexes were prepared by the reaction of
{Cu
KOR, resulting in K[Cu
(2), and K[Cu
(OCMeMeF )2] (3). The 18C6 complexes {K-
(18C6)}[Cu(OC4F9)2] (4), {K
and {K(18C6)}[Cu
(OCMeMeF )2] (6) were prepared for in-
creased solubility with unexpected effects on reactivity (see
below). Tl(OC4F9) was used to prepare Tl[Cu(OC4F9)2] (in
situ), leading to (Ph4P)[Cu(OC4F9)2] (7) by cation metathesis
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
2
ACHTUNGTRENNUNG
2
A
U
(OCPhMeF )2] (5),
ACHTUNGTNRE(NUNG 18C6)}[CuACHTNUGTRENNUNG
2
A
ACHTUNGTRENNUNG
2
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
reaction. Complexes 4, 5, and 6 were soluble in both toluene
and CH2Cl2, whereas compound 7 was soluble only in
CH2Cl2.
Figure 2. ORTEP diagram of complex 1, showing that multiple K···F in-
teractions bridge two [Cu
50% probability level.
Structural characterization: X-ray crystallographic data were
(OC4F9)2]ꢀ anions. Ellipsoids are shown at the
ACHTUNGTRENNUNG
obtained for KOCPhMeF , KOCMeMeF , Tl
ACTHNUGTRNEUGN(OC4F9), and
2
2
complexes 1, 2, 4, 6, and 7. For the three ligand salts, data
collection parameters are given in Table S1 in the Support-
ing Information with selected metrical information in
Table S2. Data collection parameters for the copper alkox-
ide complexes are given in Table S3 in the Supporting Infor-
mation with selected metrical information in Table S4.
sphere (Figure 3). In addition, 2 exhibits two crystallographi-
cally independent solid-state cuprophilic interactions, with
Cu···Cu distances of 2.5566(6) and 2.5558(6) ꢁ (sum of two
Cu atom van der Waals radii is 2.80 ꢁ). Metallophilic inter-
The MOR salts of the ligands have cubane structures with
the general formula [M(OR)]4, similar to that of
KOC4F9,[10a,12] and are shown in Figures S1–S3 in the Sup-
porting Information. Similar tetrameric fluorinated alkoxide
actions between Cu centers were first observed in [Cu-
AHCTUNGTRENNUNG
(CH2SiMe3)]4 and have subsequently been reviewed.[19] As
[18]
[15]
[16]
structures of [LiACHTUNGTRENNUNG(OC4F9)]4 and [NaACHUTNGTREN(NUGN OC4F9)]4 have been
reported previously.
All of the anionic [Cu(OR)2]ꢀ compounds have effectively
linear two-coordinate CuI centers. Complex 1 has Cu O
ꢀ
bond lengths of 1.852(2) and 1.832(2) ꢁ and the K+ cation
has an {O3F7} coordination environment. Seven K···F (aver-
age 2.96(11) ꢁ) and three K···O (average 2.76(10) ꢁ) inter-
actions link the [Cu
shown in Figures 1 and 2. Related Na···F interactions have
(OC4F9)2]ꢀ anions in the solid state, as
ACHTUNGTRENNUNG
[17]
been described for Na2{Cu
G
(MeF)2]4}2
and the
[NaOR]4 cubanes (R=CMe2MeF and C4F9).[16]
ꢀ
ꢀ
The Cu1 O1 and Cu1 O2 distances in 2 of 1.8666(18)
and 1.8665(18) ꢁ, respectively, are slightly longer than those
in 1, and an almost linear O1-Cu-O2 angle of 176.14(8)8 is
observed. Bridging K···F/O interactions are also present in
2, such that each K+ cation has an {O2F6} coordination
Figure 3. ORTEP diagram of one crystallographically independent unit
of 2. One Cu···Cu cuprophilic interaction is shown (2.5558(6) ꢁ) and
dotted lines indicate bridging K···F interactions. Hydrogen atoms are re-
moved for clarity and ellipsoids are shown at the 50% probability level.
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6375

L. H. Doerrer et al.
ꢀ
with the better-studied aurophilic compounds, cuprophilicity
is most often observed between d10 centers with linear coor-
dination. In comparison to other cuprophilic interactions re-
ported in the literature,[19] those Cu···Cu interactions in 2 are
short; this phenomenon is due to the bridging K+ ions
shown in Figure 3.
by the K O interactions to the alkoxide ligands. These
seven K···F distances in 1 range from 2.810(2) to 3.086(3) ꢁ,
in bridging both within and between the anions (Figure 2).
A similar contribution of K···F contacts was quantified for
the three crystallographically unique potassium cations in 2.
Each K+ cation has a coordination sphere of {O2F6} and an
average of 48% is donated to the total bond valence by
K···F interactions. The average K···F distances are longer in
2 than those in 1, and overall smaller values of s were calcu-
lated for those lengthier K···F contacts.
In 4 and 6 (Figures S4 and S5 in the Supporting Informa-
tion), the number of K···F/O alkoxide contacts decreases
when K+ is encapsulated by 18C6. For 4, the Cu1 O7 and
ꢀ
ꢀ
Cu1 O8 distances are 1.865(6) and 1.861(7) ꢁ, respectively,
both are noticeably longer than those in 1, and the O7-Cu-
The bond valence analysis for the encapsulated K+ cati-
ꢀ
ꢀ
O8 angle is 172.0(3)8. In contrast, in 6, the Cu1 O7 bond
ons in 4 and 6 showed that the six K O bonds from 18C6
length is 1.8152(19) ꢁ and the Cu1 O8 length is 1.805(2) ꢁ,
dominated the K+ environment, with {O7F1} coordination
for both, and the K···F contributions are less than 7% in
each case. Clearly, ensnaring the K+ cation by the cyclic
ꢀ
both are much shorter than those in 2, with a linear O7-Cu-
O8 angle of 172.34(9)8. Complex 7 (Figure S6 in the Sup-
porting Information), with the Ph4P+ cation, has Cu O
crown ether molecule in 4 and 6 produces discrete
ꢀ
bond lengths of 1.8297(17) and 1.8289(17) ꢁ, which are
[Cu(OR)2]ꢀ anions with fewer bridging contacts, impacting
the solubility and solution-state conductivity behavior of the
complexes.
ꢀ
slightly contracted compared with the same Cu O bond
lengths in 1. A comparison of the new CuI alkoxide struc-
tures with several from past work is presented in Table S5 in
the Supporting Information.
Solution-state conductivity: The solution conductivities of
ACTHNUTRGNEUNG
the {ECu(OR)2} complexes, in which E=K+, {K(18C6)}+,
Bond valence analysis: Bond valence[20] is a useful concept
for analyzing bond distance data obtained from single-crys-
tal X-ray diffraction studies and quantifying the relative
contributions to the coordination sphere of a metal ion. The
bond valence value, s, provides a quantitative measure[21] of
how much the secondary K···F/O interactions contribute to
the coordination sphere of each K+ cation. The bond valen-
ces (s) were obtained by using the appropriate bond valence
parameters[20,21] and Equation (1)
or Ph4P+, were measured in THF and CH2Cl2 to determine
their degree of electrolyte behavior. Solution-state conduc-
tivity data were acquired for solutions of 1, 2, 3, and 7 in
THF and for solutions of 4, 5, 6, and 7 in CH2Cl2. The 1:1
electrolyte TBAPF6 (TBAPF6 =nBu4NPF6 in THF or
CH2Cl2) and non-electrolyte [FeCp2] (in THF; Cp=cyclo-
pentadiene) were used as reference solutions. The Onsager
plots[22] for complexes 1, 4 and 7 are shown in Figure 4;
those for 2 and 5 are in Figure S7 in the Supporting Infor-
KꢀX ꢀdKꢀF=O
Þ
s ¼ eðR
B
ð1Þ
in which RKꢀF =1.992, RKꢀO =2.132, B=0.37, and dKꢀ are
F/O
ꢀ
the K···F or K O distances obtained from crystallographic
data. The sums of the bond valence values (ꢀ (s)) for each
K+ ion in the CuI alkoxides have been calculated (Table 1)
and approach unity, as expected, for a monovalent cation.
The same analysis for KOCPhMeF and KOCMeMeF gives
2
2
similar results and is presented in Table S6 in the Supporting
Information.
The potassium cation in 1 has a {O3F7} coordination
sphere with 49% of the valence contributed by K···F con-
tacts alone, and the remaining coordination sphere filled out
Figure 4. Solution conductivity studies of [CuACTHNUTRGNEUNG
(OC4F9)2]ꢀ derivatives 1, 4,
7, and TBAPF6 in THF and CH2Cl2.
Table 1. K+ bond valence analysis for {K[Cu(OR)2]} complexes.
K+ coordination sphere S (s)[a] S (s) K···F [%] K···F [ꢁ]
sACTHNGUTER(NNUG K···F)
mation, and those for 3 and 6 in Figure S8 along
with the control 1:1 electrolyte and non-electrolyte
measurements. The solvent THF was hypothesized
to disrupt any K···F/O interactions due to the
weak basicity of the fluorinated alkoxides (pKa
1
2
K1 O3F7
K1 O2F6
K2 O2F6
K3 O2F6
K1 O7F1
K1 O7F1
1.09
49
48
47
48
6.3
5.8
2.810(2)–3.086(3) 0.052–0.110
2.865(2)–3.174(2) 0.041–0.094
2.884(2)–3.179(2) 0.040–0.090
2.869(2)–3.154(2) 0.043–0.093
2.945(7)
3.015(2)
0.940
0.925
0.953
1.21
4
6
0.076
0.063
(HOC4F9)=5.4 and pKa (HOCMeMeF )=9.6),[23]
1.08
2
[a] Calculated by using Equation (1), in which RKꢀF =1.992, RKꢀO =2.132, B=0.37,[20,21]
and therefore, yield 1:1 electrolytes, regardless of
and dKꢀ are the crystallographically determined K···F or K O distances.
the encapsulation of K+.
ꢀ
F/O
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K···F/O Interactions
FULL PAPER
Interestingly, complex 1 did not exhibit the conductivity
of a 1:1 electrolyte. Complexes 1, 2, and 3 all showed de-
creased conductivities relative to their corresponding {K-
ACHTUNGTRENNUNG
(18C6)}+ derivatives (4, 5, and 6), which did behave as 1:1
electrolytes. The increased fluorination and K···F interac-
tions are proposed to account for the decreased conductivity
of 1 in THF versus 2 or 3. The {KACHTNUGRTNEUNG
(18C6)}+ species 4–6 and
Ph4P+ 7 displayed increased conductivity in THF and
CH2Cl2,consistent with a low degree of ion pairing in solu-
tion.
The pattern of the conductivity studies matches the bimo-
dal groupings in the bond valence analysis and strongly sug-
gests that the observed bridging solid-state K···F/O interac-
tions are maintained in solution for complexes 1, 2 and 3,
which therefore behave as multinuclear {K[Cu
ACHTUNGTNER(NUNG OCR-
Figure 5. Cu/O2 stoichiometry determined by manometry for complexes
A
1–3 in THF at ꢀ788C.
gands, but the observation of both with the same ligand is
extremely rare.[27]
ꢀ
UV/Vis spectroscopy of {Cun O2} species: Exposing color-
less to pale-yellow solutions of complexes 1–3 in THF to dry
O2 at ꢀ808C caused a relatively rapid color change to
purple (1), dark blue (2), and dark red–brown (3). As indi-
cated in Table 2, all CuI complexes exhibit a single strong
Table 2. UV/Vis spectral data for compounds 1–3.
Compound
CuI complex[a]
Cun-O2 adduct[a,b]
Scheme 2. a) Drawing of a proposed {K[Cu
solution with K···F/O interactions bringing two CuI centers. b) Discrete
anionic [Cu{OCR
(CF3)2)2]ꢀ and cationic {K(18C6)}+ units responsible for
1:1 electrolyte behavior in solution.
ACHTUNGTRNENUG(OCRAHCUTGNTREN(NNGU CF3)2)2]}2 aggregate in
1
2
240 (1790)
234 (4240)
307 (nd)[c]
520 (448)
602 (406)
590 (393)
315 (nd)[d]
320 (nd)[e]
320 (nd)[d]
320 (nd)[e]
496 (323)
644 (104)
500 (858)
511 (218)
G
G
ACHTUNGTRENNUNG
3
236 (3000)
720 (170)
673 (96)
character than compounds 4–6 and 7. In another study, a tri-
nuclear CuI species, {K (OCPhMeF )2]3},[24] with
(18C6) K2[Cu
three linear [Cu
(OCPhMeF )2]ꢀ anions held together by two
[a] Absorption maxima (lmax) are given in nanometers. Extinction coeffi-
cients are based on the Cun-O2 species and are given in parentheses
(mꢀ1 cmꢀ1). [b] Solutions were oxygenated in THF at ꢀ808C. [c] Due to
deviation from Beerꢂs law, extinction coefficients could not be deter-
mined. [d] Observed in a 6.0 mm oxygenated solution of CuI. [e] Ob-
served in a 2.0 mm oxygenated solution of CuI.
G
ACHTUNGTRENNUNG
2
ACHTUNGTRENNUNG
2
unencapsulated K+ cations has been characterized crystallo-
graphically. Extensive bridging K···F/O interactions between
the [Cu(OR)2]ꢀ groups and the non-encapsulated K+ cations
assemble a trinuclear Cu3 core.[24]
absorption band in the UV region, which is likely to be an
ꢀ
O2 reaction stoichiometry: Exposure of solutions of 1, 2,
and 3 in THF to O2 at ꢀ788C resulted in the rapid genera-
tion of intensely colored species, the Cu/O2 stoichiometries
of which were determined manometrically.[25] Details of the
error analysis are given in Table S7 in the Supporting Infor-
mation. The O2 uptake of these solutions at varying Cu con-
centrations is shown in Figure 5. Regardless of the [CuI], the
O2 uptake of 1 was observed to have a 3:1 Cu/O2 ratio. In
contrast, a 2:1 Cu/O2 stoichiometry for solutions with [CuI]
less than 2 mm and a 3:1 Cu/O2 ratio for [CuI] greater than
3 mm was observed for complexes 2 and 3. A non-integral
Cu/O2 ratio was obtained at Cu concentrations between 2
and 3 mm, which increased linearly between the regions of
O Cu ligand-to-metal charge-transfer (LMCT) band. After
exposure to O2, intense and multiple absorptions in the 300–
350 nm region develop, but related molar absorptivity
values could not be determined due to deviation from
Beerꢂs law. Other distinct absorbances for 1 occur at 520
(e=448) and 602 nm (406mꢀ1 cmꢀ1) at all Cu concentrations
studied, as shown in Figure 6a and Figure S9 in the Support-
ing Information, whereas oxygenated solutions of 2 revealed
different chromophores, depending on the amount of CuI
complex (Figure 6b). Introduction of O2 into solutions of 2
with less than 2 mm CuI produces a species with a relatively
weak absorption at 644 nm (e=104mꢀ1 cmꢀ1). Oxygenation
of 2 with greater than 3.0 mm CuI, however, generates a spe-
cies with two visible absorptions at 496 (e=295 mꢀ1 cmꢀ1)
and 590 nm (e=330mꢀ1 cmꢀ1).
ꢀ
ꢀ
integral ratios. Di- {Cu2 O2} and trinuclear {Cu3 O2} inter-
mediates[3,26] have previously been observed with N-donor li-
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L. H. Doerrer et al.
Figure 7. UV/Vis spectral changes observed upon the introduction of O2
Figure 6. a) UV/Vis spectral changes observed upon the introduction of
O2 into a solution of 1 (2.1 mm) in THF at ꢀ808C. The inset shows a
close up of the visible region of the generated O2 adduct in different con-
centrations of 1. b) UV/Vis spectra of generated chromophores in differ-
ent concentrations of oxygenated solutions of 2 in THF at ꢀ808C.
into a 6.0 (a) and 2.0 mm (b) solution of 3 in THF at ꢀ808C. The insets
ꢀ
show the time profile of the absorbance at 495 nm due to {Cun O2} spe-
cies.
Reaction of 3 with O2 produces different chromophores
for low and high concentrations of CuI, specifically affected
by the concentration of O2 in solution. When oxygen diffus-
es slowly through the headspace into a solution of 3 with
6 mm CuI, a broad band at 720 nm (203mꢀ1 cmꢀ1) develops
along with an intense broad absorption at about 500 nm cov-
ered by charge-transfer features at 300–450 nm (Figure 7a).
ꢀ
Scheme 3. The O2-concentration-dependent formation of {Cun O2} spe-
cies from 3.
ꢀ
ꢀ
The copper–oxygen adduct produced, likely {Cu3 O2}, is
produced {Cu2 O2} with an intense absorption at 511 nm
quite stable once fully formed, as indicated by the time pro-
file of the oxygenation reaction (inset of Figure 7a) at
495 nm. The initial incomplete formation of the same chro-
mophore was observed in 3 with 2 mm CuI (Figure 7b), how-
ever, it converts into a new species, likely {Cu2O2}, with ab-
sorption bands at 511 and 700 nm shortly after formation
(inset of Figure 7b).
and a broad band at 700 nm (Figure S9 in the Supporting In-
formation). These spectral features are quite different from
those observed in slow diffusion of O2 into a solution of CuI
ꢀ
(Figure 7). Interestingly, the {Cu3 O2} adduct formed by
slow diffusion of O2 can be converted into the {Cu2 O2} pro-
duced from O2 bubbling through the solution (Figure S9 in
the Supporting Information).
ꢀ
The O2-reduction product of 3 is not only controlled by
the Cu concentration, but also by the rate of O2 diffusion
Chromophore formation for oxygenated solutions of 1, 2,
or 3 is irreversible under vacuum or argon purge, but stabili-
ty is maintained at ꢀ808C for more than an hour in each
case. Reactive complexes decompose quickly into green–
brown solutions upon warming to room temperature,again
indicative of irreversible O2 reduction. Attempts to record
resonance Raman spectra were unsuccessful.
Surprisingly, no chromophores were generated upon the
addition of O2 to 4 in toluene, or to 7 in CH2Cl2, at ꢀ808C.
These compounds with 1:1 electrolyte character were also
ꢀ
into the solution. Generation of the {Cu3 O2} adduct is fa-
vored at high CuI concentration under slow diffusion of O2;
these are the manometry experimental conditions. In con-
trast, fast/enforced O2 introduction into the solution by bub-
I
ꢀ
bling leads to the {Cu2 O2} species independent of Cu con-
centration. Scheme 3 shows how the generation of oxygenat-
ed species from 3 depends on the O2 introduction method.
Letting O2 bubble through a 6 mm solution of 3 at ꢀ808C
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K···F/O Interactions
FULL PAPER
unreactive with O2 in THF at ꢀ808C. Only upon warming to
room temperature was oxidation evident through the slow
evolution of the green color. The reactivity of the CuI alkox-
ides with O2 is thus more facile in the presence of more
K···F/O interactions. The di- or trinuclear aggregates of 1, 2,
and 3 indicated by O2 uptake measurements could provide
up to four or six reducing electrons, respectively, for the ir-
reversible reduction of O2. Without the assembly of a poly-
nuclear {Cun} core, the reaction with O2 does not occur at
ꢀ808C.
CO2 reactivity: Some electrophilic character of the {CunO2},
n=2 or 3, moieties was demonstrated in the phenyl hydrox-
ylation of 2. The nucleophilic character of the reduced
oxygen species was demonstrated in their reaction with
CO2. It is unusual for these two disparate types of reactivity
to be achieved with one ligand system. A CuI b-diketiminate
system also generates a {Cu3O2} moiety and carbonate, but
does not abstract H atoms.[27d]
Reaction of O2 with complexes 1, 2, and 3, in Cu concen-
trations greater than 5 mm, was followed by the addition of
CO2 after removal of excess oxygen and resulted in the for-
C H bond hydroxylation and 18O2 studies: The reduction of
mation of green (1 CO3 and 2 CO3) or blue (3 CO3) pow-
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
O2 by 1, 2, and 3 is not reversible at ꢀ808C, and warming
the reaction mixtures to room temperature changes the
color of oxidized solutions to green–brown. The vulnerable
ders. The recrystallization of 3 CO3 from dimethoxyethane
ꢀ
(DME) afforded X-ray quality blue crystals of 3 CO3 and 8,
along with a green species that has not yet been identified.
ꢀ
ꢀ
ꢀ
ꢀ
phenyl C H bonds of 2 and methyl C H bonds of 3 were
activated by insertion of an “O” atom to form hydroxyl
groups. ESI-MS analysis of the oxygenated product of 2 at
room temperature revealed an ion peak at m/z 259, the
mass and isotope distribution of which corresponds to [OC-
The solid-state IR spectra for powders of 1 CO3, 2 CO3,
and crystals of 8 are shown in Figure S10 and Table S8 in
the Supporting Information, which lists the relevant IR-
active stretches for carbonate vibrational modes and com-
pares them with two other reported CuII carbonate spe-
cies.[28] The IR stretches are observed in the region of 1320–
(C6H4OH)MeF ]ꢀ, with a hydroxylated phenyl ring of the
2
2ꢀ
ligand. ortho-Hydroxylation of the phenyl ring for complex
2 is proposed, based on the favorability of six-membered
chelate ring formation, which yields the ortho-hydroxylated
ligand as the product of the reaction. Similarly the oxygenat-
ed product of 3 at room temperature is the ligand with a hy-
droxylated methyl substituent, as indicated by a peak at m/z
197, corresponding to [OC
data for the oxygenated solution of complex 1 after warming
show only the OC4F9 ligand.
When the oxidation reactions were carried out with iso-
topically labeled 18O2, ESI-MS analysis revealed a new peak
at m/z 261 for 2 along with that observed earlier at m/z 259,
and a new peak at m/z 199 for 3 along with one for m/z 197.
The observation of an increase in m/z by two units upon iso-
topic substitution confirms the source of the hydroxyl O
atom as 18O2 (Figure 8). Three higher concentrations of com-
plexes (4, 5, and 6 mm) were studied in oxygenation reac-
tions of 2 and 3, and all three trials revealed incorporation
of 18O.
1550 cmꢀ1, consistent with a metal-bound CO3 moiety.[29]
Similar IR stretches were reported for the CuII carbonate
[28b]
complexes {[Cu
(pip)
E
E
and [Cu2-
[28a]
A
E
R
(pip=2-[2-(2-pyridyl)ethylimino-
methyl]pyridine, Me2im= 1,2- dimethylimidazole) and also
for potassium carbonate.[30] The other IR stretches are as-
(CH2OH)MeF ]ꢀ. The ESI-MS
signed as alkoxide-related vibration modes: 1199 (nC F),
ꢀ
2
1175, 957 (nCu OR), and 700 cmꢀ1 (nC F and nCu
OR).[10a,30]
ꢀ
ꢀ
ꢀ
ꢀ
Compound 8 is a CuII alkoxide carbonate tetramer, the
asymmetric unit of which is shown in Figure 9, along with
the full tetramer in Figure 10. The four crystallographically
2ꢀ
identical CuII centers are bridged by CO3 and K+ with the
stoichiometry {{K2ACTHGNUNERT(GUNN DME)1.5}[CuACHTUNGTREUNNNG 2ACHTUTGNRENG(NU CO3)]}4. Two
(OCMeMeF )
2
alkoxide ꢀOCMeMeF ligands are bound terminally to each
2
CuII and bridged by a K+ cation, in which the Cu1 O4 and
ꢀ
ꢀ
Cu1 O5 distances are 1.940(2) and 1.898(3) ꢁ, respectively.
The elongated bridging Cu Oalkoxide distances are compara-
ble to a similar Cu1 O8alkoxide bond distance of 1.858(2) ꢁ in
ꢀ
ꢀ
6 in which the bridging alkoxide
distance is longer than the ter-
minal alkoxide distance.[24]
The two other coordination
sites of each CuII center are
filled by a bidentate carbonate,
ꢀ
ꢀ
with Cu1 O2 and Cu1 O3 dis-
tances 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 result-
ing in a four-coordinate geome-
try for CuII. The four-coordi-
nate CuII center has
a
t4
value[31] of 0.18, indicating a
slight distortion from square-
Figure 8. 16O2 and 18O2 reactivity of complexes 2 and 3, showing hydroxylated C H bonds of the ligands, with
proposed regioselectivity for the phenyl ring resulting from 2 and O2.
ꢀ
Chem. Eur. J. 2013, 19, 6374 – 6384
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6379

L. H. Doerrer et al.
in the Supporting Information, however, only the intramo-
ꢀ
lecular K···F and K O contacts in one asymmetric unit of 8
are depicted in Figure 9 for clarity. The range of K···F dis-
tances for K1 and K2 is 2.818(3)–3.034(3) ꢁ, similar to the
distances found for complexes 1 and 2.
The solution-based conductivity for 8 demonstrates weak
electrolyte behavior in solution. The Onsager plot of 8 is
shown along with solution conductivity studies of a dianionic
[CuACHTNUTGRNEUNG
(OArF)4]2ꢀ species[20] in Figure S12 in the Supporting In-
formation. The conductivity of 8 is very low in THF com-
pared with similar concentrations of dianionic [Cu-
F
2ꢀ
ꢀ
AHCTUNGRTEGNUN(N OAr )4] . The aforementioned K···F and K O interactions
are proposed to be maintained in solution, consistent with
the tetramer observed in the solid state.
The Evans method[32] magnetic moment of 8 was deter-
mined to be 3.00 mB in THF and 3.08 mB in acetone. The
spin-only magnetic moment of 4.89 mB for an S=2 complex
indicates that the four CuII centers are antiferromagnetically
coupled, resulting in meff =0.76 mB per CuII center. The lower
solution meff value again supports retention of the tetrameric
structure in solution. In this compound, the carbonate group
is the primary reason for a polynuclear structure, as is well-
known in other multinuclear carbonate compounds.[33]
Figure 9. ORTEP drawing of one unit of tetrameric compound 8 with
DME. Hydrogen atoms have been removed for clarity. Ellipsoids are
drawn at the 50% probability level. Selected K···F interactions are de-
picted as dotted lines.
Conclusion
The present K[Cu(OR)2] complexes with fully (1, R=C4F9)
or partially (2, R=CPhMeF2 or 3, R=CMeMeF ) fluorinated
2
ꢀ
alkoxides react rapidly with O2 at ꢀ808C to form {Cun O2}
species. The Cu/O2 ratio of the oxygenated species is strong-
ly affected by K···F/O interactions that keep Cu centers ag-
gregated in solution. A higher degree of ligand fluorination
ꢀ
in 1 favors the formation of the {Cu3 O2} adduct independ-
ent of Cu concentration due to extensive K···F/O interac-
tions.
Complex 2 is one of the rare examples that can preferen-
Figure 10. ORTEP drawing of 8 shown as a tetramer with DME mole-
cules and fluorine atoms of ligand removed for clarity. Relevant atoms of
a single monomeric unit are labeled. Ellipsoids are drawn at the 50%
probability level.
ꢀ
tially form tri- or binuclear Cu O2 adducts, depending on
the Cu concentration. The {Cu3-O2} moiety forms as the
dominant species from 2 and O2 with [CuI] greater than
3 mm, whereas a 2:1 Cu/O2 ratio for [CuI] less than 2 mm
planar geometry. The small bite-angle O2-Cu1-O3 of
66.8(1)8 subtends the four-membered chelate ring and the
bidentate binding mode of the CO3 group with a O2-C1-
O3 bond angle of 114.5(3)8.
The CF3 groups of 8 also engage in K···F interactions like
those in 1 and 2, but are fewer in the presence of the carbo-
was observed. To the best of our knowledge, compound 3 is
2ꢀ
I
ꢀ
the first example of a Cu complex that can produce Cu O2
adducts with different Cu/O2 stoichiometries controlled by
not only [CuI] but also the O2 diffusion rate. Slow O2 diffu-
sion into solutions of 3 with [CuI] greater than 3 mm gener-
ꢀ
ꢀ
nate. There are also multiple K O contacts between the car-
ated a {Cu3 O2} species, whereas quickly saturating the solu-
bonate O atoms and the K+ cations in the tetramer, in
tion with O2 produces a dinuclear {Cu2 O2} complex inde-
ꢀ
ꢀ
ꢀ
which the distances for K1 O1 and K1 O3 are 2.656(2) and
pendent of Cu concentration. Reduction of O2 is irreversible
for all complexes and concentrations studied. With C H
bonds present in the ligands, intramolecular hydroxylation
of sp - (2) and sp -hybridized (3) C H bonds is observed.
Nucleophilic reactivity with CO2 has also been shown and a
CuII carbonate species has been isolated and characterized.
Thus, these fluorinated alkoxides support {CunO2} moieties
with both electro- and nucleophilic character. Previously,
alkali cations have been reported to increase the reactivity
ꢀ
ꢀ
2.656(3) ꢁ, respectively, and K1 O2 is longer at 2.981(2) ꢁ.
One of the DME groups is disordered between two K+ cati-
ons. Bond valence analysis for the {O6F2} coordination
2
3
ꢀ
ꢀ
sphere of K1 indicated a total of 1.18 for the K···F and K O
contributions, 15% of which is due to K···F interactions. The
{O6F2} coordination of K2 resulted in a sum of 1.24 for bond
valence, with 14% contributed by K···F contacts. The bond
ꢀ
lengths for the K···F and K O contacts are listed in Table S4
6380
www.chemeurj.org
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 6374 – 6384

K···F/O Interactions
FULL PAPER
SADABS software program. Solution was by direct methods (SHELXS)
and all non-hydrogen atoms were refined anisotropically by full-matrix
least-squares methods (SHELXL-97). Hydrogen atoms were treated as
idealized contributions and were placed in calculated positions with ap-
propriate riding models for KOCMeMeF2. CHECKCIF indicated the
presence of a large void volume (50 ꢁ3), yet no appreciable residual elec-
tron density was found; use of PLATON Squeeze resulted in an electron
of reduced mononuclear transition-metal complexes with
CO[34] and CO2.[35] More recently, Ca2+ has been shown to
accelerate the rate of O2 reduction in a Mn system[36] and
K+ has been shown to facilitate N2 reduction by low-valent
Fe.[37] Thus, the pairing of d- and s-block metals for small-
molecule activation may prove increasingly general. In bio-
logical systems, dioxygen reactivity of multinuclear Cu is
mediated by intricate scaffolding of proteins with kilodalton
molecular weights. Analogous multinuclear Cu chemistry
has now been achieved with exclusively O-donor coordina-
tion, without bridging bulky ligands, and simply the
0.039 kDa K+ cation.
count of 27 eꢀ. In Tl
ACTHNUGTRNEUGN(OC4F9), C3 was refined with an EADP command
referenced to atom C1 and a large second weight correction factor was
noted and kept with the refinement. Residual electron density greater
than 1 eꢀ was noted near atoms F9 (1.58 eꢀ at 1.25 ꢁ), F6 (1.41 eꢀ at
1.13 ꢁ), and F3 (1.35 eꢀ at 1.08 ꢁ) in Tl
ACHTNUTRGNE(UNG OC4F9). There were some minor
distortions with respect to some of the fluorine atoms in complex 1, but
these were not treated. The X-ray structure was twinned for 4 and solved
by using appropriate corrections, however, the statistics were still poor.
All non-hydrogen atoms were refined anisotropically by Fourier full-
matrix least squares on F2 and hydrogen atoms were placed in calculated
positions with appropriate riding models for compound 6. For compound
8, disordered atoms in DME molecules were at 50% occupancy. All soft-
ware is contained in various libraries (SHELXTL, SMART, and SAINT)
maintained by Bruker AXS, Madison, WI,[39] except CHECKCIF, which
is a service of the International Union of Crystallography.
Experimental Section
General procedures: Ligand synthesis and CuI complex preparations
were performed at RT in an MBraun purified N2-filled drybox or by
using standard Schlenk techniques under an atmosphere of N2 or Ar. The
anhydrous solvents CH2Cl2, diethyl ether, toluene, and hexanes were pu-
rified with an Ar-filled MBraun solvent purification system (SPS) equip-
ped with dual columns of anhydrous Al2O3. Anhydrous THF (99.9%)
was distilled under N2 from purple sodium benzophenone ketyl and de-
gassed before further treatment with calcium hydride in the drybox. Deu-
terated solvents used for NMR samples (CDCl3 and CD2Cl2) and the in-
ternal 19F standard, trichlorofluoromethane (CFCl3), were dried by heat-
ing at reflux over CaH2; [D6]acetone was dried over molecular sieves. All
solvents were stored over molecular sieves in an N2-filled drybox. Celite
was dried overnight in vacuo while being heated to 1258C with an oil
bath. The reagent 18C6 was obtained from commercial sources and re-
crystallized from hexanes. KH was obtained as a mineral oil dispersion
(30 wt%) and purified by washing with hexanes and drying in vacuo
prior to storage in the drybox. The fluorinated alcohols HOC4F9, HOC-
CCDC-899244–899252 contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_re-
quest/cif.
Low-temperature UV/Vis spectroscopy and generation of {CunO2} spe-
cies: Under a nitrogen atmosphere within a glove box, K[Cu(OR)2] com-
plexes (1–3) were dissolved in O2-free THF (3 mL), giving a range of col-
orless to pale-yellow solutions, depending on the compound. The cuvette
with a side arm was sealed with a septum covered by parafilm, quickly
removed from the glove box, and cooled to 193 K in a Shimadzu UV-
3600 spectrophotometer equipped with
a Unisoku thermostated cell
holder. O2 from a RT balloon (99.999%) was gently bubbled through the
reaction solution. After full formation of {CunO2} species, excess O2 was
removed by purging ultrapure Ar gas through the headspace for about 2–
3 min.
ACHTUNGTRENNUNG(C6H5)ACHTUNGTRENNUNG(CF3)2, and HOCACHTNUGERTG(NNUN CH3)ACHTNUGTREN(UNGN CF3)2 were obtained from Oakwood
Ligand syntheses
Chemicals or Matrix Scientific and dried over sieves before being stored
in the drybox. The perfluorinated tert-butoxide ligand, KOC4F9, was syn-
thesized according to our reported modified procedure.[10a] TBAPF6 was
KOCPhMeF2: A slurry of KH (0.2750 g, 6.856 mmol) in Et2O was cooled
to ꢀ788C by using a dry ice/acetone bath. A deficiency of HOCPhMeF
2
triply recrystallized from CH2Cl2 and hexanes. {CuACHTUNTRGNE(GNU mes)}n was synthe-
(1.510 g, 6.185 mmol) was syringed into the solution slowly, while the
flask was flushed with N2. The reaction mixture was cloudy white and
kept cold for approximately 2 h before being warmed to RT over 4 h.
The solvent was removed in vacuo to yield white solid residue coating
the flask, which was brought into an N2-filled drybox. The white solid
was redissolved in Et2O and filtered over Celite to remove excess KH,
and the filtrate was dried under vacuum, yielding a white powder. The
crude solid was dissolved in 1:1 Et2O/hexanes and layered with hexanes
for recrystallization (ꢀ348C). After two recrystallizations, a white solid
was obtained (88%, 1.537 g). Colorless block crystals suitable for single-
crystal X-ray diffraction were isolated from the same recrystallization
sized by following a literature procedure.[38] All other reagents were ob-
tained from commercial sources and used without any further purifica-
tion.
Physical methods: NMR spectra were recorded on Varian 300, 400, and
500 MHz spectrometers at RT. Chemical shifts (d) for 1H and
13C{1H} NMR spectra were referenced to the resonance of residual pro-
tiosolvent (1H) or the 13C{1H} resonance of the solvent. Chemical shifts
(d) for 19F NMR spectra were referenced to internal CFCl3. 31P{1H} NMR
spectra were collected with standard PPh3 contained in a capillary tube
within the NMR tube. Conductivity studies were performed at RT in the
drybox by using a Fisher Scientific Traceable Portable Conductivity
Meter (model number 09-326-2). Solutions for conductivity were pre-
pared in CH2Cl2 or THF, depending on compound solubility. Triply re-
crystallized TBAPF6 was used as the reference 1:1 electrolyte. ESI mass
spectra were recorded by using an Agilent 1100 LC/MSD spectrometer
equipped with mobile phases of water and MeCN with 0.1% formic acid.
Elemental analyses were performed by Quantitative Technologies, Inc.
(Whitehouse, NJ) or by Atlantic Microlab Inc. (Norcross, GA).
conditions. 1H NMR (300 MHz, (CD3)2CO): d=7.88 (m, 1H; OC
C6H5)(CF3)2), 7.37 ppm (m, 4H; OC(o- and m-C6H5)
(CF3)2); 13C NMR
(75 MHz, (CD3)2CO): d=144.1 (s, OC(ipso-C6H5)(CF3)2), 129.0 (s, OC-
(m-C6H5)(CF3)2), 128.6 (s, OC(p-C6H5)(CF3)2), 128.3 (s, OC(o-C6H5)-
(CF3)2), 127.9 (quartet, (OC(C6H5) (C,F)=293.5 Hz), 83.7 ppm
(CF3)2), 1J
(septet, OC(C6H5)
(CF3)2, 2J(C,F)=25.2 Hz); 19F NMR (282 MHz,
(CF3)2); elemental analysis calcd
ACHTUNGTRENNUNG(p-
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
A
E
E
N
ACHTUNGTRENNUNG
A
E
N
ACHTUNGTRENNUNG
A
R
ACHTUNGTRENNUNG
(CD3)2CO): d=ꢀ75.45 ppm (s, OCPh
ACHTUNGTRENNUNG
(%) for C9H5OF6K: C 38.30, H 1.79, F 40.39; found: C 38.37, H 2.03, F
40.30.
X-ray crystallography and structure determination: Single-crystal X-ray
diffraction data were collected on a APEX-CCD detector equipped
Bruker diffractometers. All CuI complexes structurally characterized
were colorless crystals mounted on a Cryoloop with Paratone-N oil and
cooled under a stream of nitrogen gas. Data were corrected for absorp-
tion by using semi-empirical, multiscan methods. All structures were
solved by heavy-atom methods and the remaining non-hydrogen atoms
were located from subsequent difference maps. Data were integrated by
using the Bruker SHELXTL software program and scaled by using the
KOCMeMeF2: A slurry of KH (1.6882 g, 42.09 mmol) in Et2O was cooled
to ꢀ788C by using a dry ice/acetone bath. A deficiency of HOCMeMeF
2
(6.826 g, 37.49 mmol) was syringed into the solution slowly, while the
flask was flushed with N2. The stirred reaction mixture was cloudy white
and kept cold for approximately 2 h before being warmed to RT over 4 h.
The solvent was removed in vacuo to yield off-white solid coating the
flask, which was brought into an N2-filled drybox. The solid residue was
redissolved in Et2O and filtered over Celite to remove excess KH and
Chem. Eur. J. 2013, 19, 6374 – 6384
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6381

L. H. Doerrer et al.
the filtrate was dried under vacuum, yielding an off-white powder. The
crude solid was dissolved in 1:1 Et2O/hexanes and layered with hexanes
for recrystallization (ꢀ348C). After two recrystallizations, a white solid
was obtained (67%, 5.5417 g). Colorless block crystals suitable for single-
crystal X-ray diffraction were isolated from the same recrystallization
(septet, OCAHCTUNGTRENGN(UN C6H5)ACHTUTGNRENNUG ACTHUNGTRENNUNG
(CF3)2, 2J
(CD3)2CO): d=ꢀ74.56 ppm (s, OCPh
ACHTUNGTRENNUNG
(%) for C18H10O2F12KCu: C 36.71, H 1.71, F 38.71; found: C 36.45, H
1.46, F 38.86.
K[Cu
(OCMeMeF2)2] (3):
A
a
portion of HOCMeMeF (0.25233 g,
yellow slurry of {CuACHTNUGRTENUNG(mes)}n (0.2519 g,
2
conditions. (Fluorine analysis was likely to be low due to incomplete F
1.39 mmol) was added to
1
combustion.) H NMR (400 MHz, (CD3)2CO): d=1.27 ppm (s, OC
U
1.38 mmol) in Et2O. The reaction mixture was yellow and slightly cloudy.
(CF3)2; 13C NMR (100 MHz, (CD3)2CO): d=128.2 (quartet, OC
(CF3)2, 1J (CF3)2, 2J
(C,F)=293.4 Hz), 79.2 (septet, OC(CH3)
25.3 Hz), 21.5 ppm (OC(CH3)
d=ꢀ79.58 ppm (s, OC(CH3)
ACHTUNGTRENNUNG
A solution of KOCMeMeF (0.3060 g, 1.39 mmol) in Et2O was added and
2
G
E
G
ACHTUNGTRENNUNG
the mixture was stirred for 2 h at RT. Complex 3 was obtained by using a
workup analogous to that of 1. The yellow solid was recrystallized by
using Et2O/hexanes and a microcrystalline solid was obtained (71%,
G
ACHTUNGTRENNUNG
N
ACHTUNGTRENNUNG
0.4561 g). 1H NMR (500 MHz, (CD3)2CO): d=1.40 ppm (s, OC
ACHTUNGTRENNUNG
A
ACHUTGTNERN(NUG CH3)ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
A
E
E
ACHTUNGTRENNUNG
cooled to ꢀ788C by using a dry ice/acetone bath and flushed with N2.
Thallium ethoxide (5.0 g, 20.04 mmol) was slowly syringed into the solu-
tion. A white precipitate formed upon mixing and the solution was very
pale purple. The reaction was kept cold for approximately 1 h before
being warmed to RT over 2 h. Stirring was stopped and the white precipi-
tate was allowed to settle to the bottom of the flask, after which time the
solution layer was removed by using a cannula. The white solid was
washed three times with a total of 30 mL of anhydrous CH2Cl2, and the
solid was dried in vacuo and brought into the N2-filled drybox. The crude
white solid was redissolved in toluene/THF, filtered to remove any in-
soluble particulate, yielding a very pale purple solution. The product was
recrystallized by layering the solution in toluene/THF with hexanes and
stored at ꢀ348C. After two recrystallizations, white solid was obtained
(71%, 6.2822 g) and colorless crystal blocks suitable for single-crystal X-
ray diffraction were isolated from the same recrystallization mixture.
G
ACHTUNGTRENNUNG
E
ACHTUNGTRENNUNG
G
ACHTUNGTRENNUNG
toluene (10 mL) was added to a slurry of 1 (0.4689 g, 0.819 mmol) in tol-
uene (10 mL). The immediately cloudy yellow solution was left stirring at
RT overnight. The resulting cloudy, pale yellow solution was filtered to
remove any yellow insoluble precipitate and the clear, colorless filtrate
was concentrated to dryness in vacuo. The white solid was soluble in
CH2Cl2 and recrystallized from layering a solution in CH2Cl2 with hex-
anes (72%, 0.4940 g). Colorless crystals suitable for single-crystal X-ray
diffraction were grown from the same recrystallization conditions at
ꢀ348C. 1H NMR (500 MHz, CD2Cl2): d=3.62 ppm (s, C12O6H24);
13C NMR (125 MHz, CD2Cl2): d=123.3 (quartet, OC
G
ACHTUNGTRENNUNG(C,F)=
13C NMR (75 MHz, (CD3)2CO): d=125.5 (quartet, OC
296.6 Hz), 83.5 ppm (dectet, OC
(CF3)3, 2J(C,F)=28.4 Hz); 19F NMR
(CF3)3); elemental analysis
(CF3)3, 1J
ACHUTGTNRNEUNG AHCUTNGTREN(NUGN C,F)=
(CF3)3, 2J
294.9 Hz), 83.5 (dectet, OCACHTNUGTRENNUGN CAHTUNGTRNENNUG
C12O6H24); 19F NMR (470 MHz, CD2Cl2): d=ꢀ75.99 ppm (s; OC4F9);
A
ACHTUNGTRENNUNG
ESI-MS (CH2Cl2) negative scan: m/z: 235 [ꢀOC4F9], 533/535 [Cu-
(282 MHz, (CD3)2CO): d=ꢀ74.02 ppm (s, OC
ACHTUNGTRENNUNG
ACHUTNGRENNUG CAHTUNGTRENNUGN
(OC4F9)2]ꢀ; positive scan: m/z: 145/147 [Cu(MeCN)2]+, 303 [K18C6]+; el-
calcd (%) for C4F9OTl: C 10.93, F 38.91; found: C 10.87, F 38.87.
emental analysis calcd (%) for C20H24O8F18KCu: C 28.70, H 2.89, F
Copper(I) alkoxide complex syntheses
40.86; found: C 28.70, H 2.49, F 40.47.
K[Cu
ACHTUNGTRENNUNG
{K
A
N
A
solution of 18C6 (0.2477 g,
ringed into a yellow slurry of {CuAHCNUTGTRENNUNG
0.937 mmol) in toluene (10 mL) was added to a slurry of 2 (0.6375 g,
1.083 mmol) in toluene (10 mL). After a workup analogous to 4, complex
5 was obtained as a white solid. Recrystallized solid was obtained in 72%
The reaction mixture was yellow and slightly cloudy. A colorless solution
of KOC4F9 (0.3811 g, 1.39 mmol) in Et2O was added and the mixture stir-
red for 2 h at RT. The cloudy yellow solution was filtered over Celite to
remove any insoluble material, and the bright yellow filtrate was concen-
trated to dryness in vacuo. The resultant yellow solid residue was washed
twice with hexanes to remove mesitylene (Hmes), then the solid was
dried in vacuo, yielding a pale yellow powder, and recrystallized by using
yield (0.5733 g). 1H NMR (500 MHz, CD2Cl2): d=7.90 (m, 1H; OC
ACHTUNGTRENNUNG
C6H5)ACHTUNGTRENN(UNG CF3)2), 7.29 (m, 4H; OC(o- and m-C6H5)ACHTNUGTRENNNUG
A
E
E
N
ACHTUNGTRENNUNG
A
G
G
G
ACHTUNGTRENNUNG
Et2O/hexanes to obtain
a microcrystalline solid (62%, 0.4935 g). If
291.9 Hz), 82.2 (septet, OCCAHTUGNTERNU(NGN C6H5)ACHTUGNTENRNUG ACTUHNGTRENNUGN
(CF3)2, 2J
drybox conditions were not optimal, recrystallization attempts resulted in
an orange insoluble material precipitating from solution; this significantly
lowered the yield, making the pure yellow solid difficult to recover. Col-
orless crystals suitable for single-crystal X-ray diffraction were grown
slowly from the same Et2O/hexanes recrystallization mixture at ꢀ348C.
Satisfactory elemental analyses could not be obtained due to the excep-
tional sensitivity of 1 to O2 and the high degree of fluorination. 13C NMR
C12H24O6); 19F NMR (470 MHz, CD2Cl2): d=ꢀ75.27 ppm (s, OC
ACHTUNGTRENNUNG(C6H5)-
AHCTUNGTRENNUNG
(CF3)2); ESI-MS (CH2Cl2) negative scan: m/z: 243 [ꢀOCPhMeF2]; posi-
tive scan: m/z: 145/147 [CuACHTNUGRTNEUNG
(MeCN)2]+, 303 [K18C6]+; elemental analysis
calcd (%) for C30H34O8F12KCu: C 42.23, H 4.02, F 26.72; found: C 42.30,
H 3.65, F 26.72.
{K
(18C6)}[Cu
N
A
(125 MHz, (CD3)2CO): d=123.9 (q,
84.1 ppm (dectet,
(CF3)3, 2J(C,F)=27.7 Hz); 19F NMR (470 MHz,
(CD3)2CO): d=ꢀ75.35 ppm (s, OC(CF3)3); ESI-MS (CH2Cl2) negative
scan: m/z: 235 [ꢀOC4F9], 533/535 [Cu(OC4F9)2]ꢀ; positive scan: m/z: 145/
147 [Cu
(MeCN)2]+.
K[Cu
(OCPhMeF2)2] (2): A portion of HOCPhMeF (0.3366 g, 1.38 mmol)
was added to a yellow slurry of {CuACTHUNGTRNE(NUG mes)}n (0.2517 g, 1.38 mmol) in Et2O.
CACTHNGUTRENUNG ACHTUGNRTEN(NUNG C,F)=293.4 Hz),
(CF3)3, 1J
0.724 mmol) in toluene (10 mL) was added to a slurry of 3 (0.3352 g,
0.721 mmol) in toluene (10 mL). After a workup analogous to 4, complex
6 was obtained as a white solid. The solid was recrystallized from a con-
centrated solution in toluene and layered with hexanes (69%, 0.3634 g).
Colorless crystals suitable for X-ray analysis were grown from the same
recrystallization conditions at ꢀ348C. 1H NMR (500 MHz, CD2Cl2): d=
C
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
2
3.62 (s, 24H; C12O6H24), 1.44 ppm (s, 3H; OC
(125 MHz, CD2Cl2): d=126.6 (quartet, OC
291.0 Hz), 78.4 (septet, OC(CH3) (C,F)=26.4 Hz), 70.7 (s,
(CF3)2, 2J
C12H24O6), 23.7 ppm (s, OC(CH3)
(CF3)2); 19F NMR (470 MHz, CD2Cl2):
d=ꢀ79.22 ppm (s, OC(CH3)(CF3)2); ESI-MS (CH2Cl2) positive scan: m/
z: 145/147 [Cu
(MeCN)2]+, 303 [K18C6]+; elemental analysis calcd (%)
N
ACHTUNGTRENNUNG
E
G
ACHTUNGTRENNUNG
The reaction mixture was yellow and slightly cloudy. A solution of
KOCPhMeF (0.3901 g, 1.38 mmol) in Et2O was added and the mixture
A
U
ACHTUNGTRENNUNG
2
A
ACHTUNGTRENNUNG
stirred for 2 h at RT. Complex 2 was obtained by using a workup analo-
gous to that of 1. The pale yellow solid was recrystallized from a mixture
of Et2O and hexanes (84%, 0.6835 g). Pale yellow crystals suitable for
single-crystal X-ray diffraction were grown from the same mixture at
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
for C20H30O8F12KCu: C 32.95, H 4.15, F 31.27; found: C 33.17, H 4.07, F
30.73.
ꢀ348C. 1H NMR (500 MHz, (CD3)2CO): d=7.94 (m, 1H; OC
ACHTUNGTRNE(NUNG p-C6H5)-
A
A
A
ACHTUNGTRENNUNG
(125 MHz, (CD3)2CO): d=139.4 (s, OC(ipso-C6H5)
(m-C6H5)(CF3)2), 128.4 (s, OC(p-C6H5)(CF3)2), 128.2 (s, OC
(CF3)2), 126.3 (quartet, OC(C6H5) (C,F)=291.1 Hz), 82.4 ppm
(CF3)2, 1J
G
ACHTUNGTRENNUNG
E
E
G
E
ACHTUNGTRENNUNG
R
R
G
N
ACHTUNGTRENNUNG
6382
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ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 6374 – 6384

K···F/O Interactions
FULL PAPER
was added to the mixture and stirred for 2 h at RT. A portion of Ph4PI
(0.1082 g, 0.2320 mmol) was added by using Et2O and bright yellow pre-
cipitate (presumably TlI) formed immediately. The cloudy yellow mixture
was stirred for 2 h and filtered over Celite to remove any insoluble TlI.
The filtrate was very pale yellow and the solvent was removed in vacuo.
The resultant off-white residue was washed and triturated twice with hex-
anes and CH2Cl2, respectively, to remove Hmes. The product was ob-
Palmer, Angew. Chem. 2001, 113, 4702–4724; Angew. Chem. Int.
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tained as
a white solid (79%, 0.1588 g) after recrystallization from
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5063.
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CH2Cl2/hexanes. Colorless needles suitable for single-crystal X-ray dif-
fraction studies were grown very slowly from CH2Cl2 and hexanes at
ꢀ348C. 1H NMR (400 MHz, CD2Cl2): d=7.93 (t, 4H; (p-C6H5)4P), 7.78
(m, 8H; (m-C6H5)4P), 7.63 ppm (m, 8H; (o-C6H5)4P); 13C NMR
(100 MHz, CD2Cl2): d=135.9 (s, 1C, (p-C6H5)4P), 134.5 (s, (o-C6H5)4P),
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131.2 (s, (m-C6H5)4P), 123.4 (quartet, OC
A
ACHTUNGTRENNUNG
118.4 (s, (ipso-C6H5)4P), 83.4 ppm (dectet, OC
G
ACHTUNGTRENNUNG
[8] A. P. Purdy, C. F. George, G. A. Brewer, Inorg. Chem. 1992, 31,
2633–2638.
19F NMR (376 MHz, CD2Cl2): d=ꢀ75.47 ppm (s, OC
ACHTUNGTRENNUNG
(CH2Cl2) negative scan: m/z: 235 [ꢀOC4F9], 533/535 [Cu
ACHTUNGTRENNUNG
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383; b) S. A. Cantalupo, H. E. Ferreira, E. Bataineh, A. J. King,
M. V. Petersen, T. Wojtasiewicz, A. G. DiPasquale, A. L. Rheingold,
L. H. Doerrer, Inorg. Chem. 2011, 50, 6584–6596.
tive scan: m/z: 145/147 [CuACHTNUGRTNEUNG
(MeCN)2]+, 339 [Ph4P]+; elemental analysis
calcd (%) for C32H20O2F18PCu: C 44.03, H 2.31, F 39.17; found: C
40.2(7), H 2.0(2) (the CH analyses represents an average of six replicate
runs), F 39.12.
CuII carbonate complex synthesis
(OCMeMeF
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({K2ACHTUNGTRENNUNG(DME)1.5}[CuACHTUNGTRENNUNG )2ACHTUGNTERNNUG(CO3)])4 (8): A solution of 3 (0.2905 g,
2
0.625 mmol) was prepared in THF (40 mL). The pale yellow solution was
placed in a Schlenk flask, flushed with N2, and cooled to ꢀ788C. After
equilibrating at ꢀ788C for 10 min under N2, O2 was introduced by direct-
ly bubbling the gas into the CuI solution. The color immediately changed
to deep brown and the reaction with O2 continued for 30 min. While
maintaining the temperature at ꢀ788C, excess O2 was removed from the
headspace by purging with N2, and CO2 was then bubbled into the brown
solution for 20 min. When the solution was warmed to RT, there was a
distinct color change to deep emerald green. The solvent was removed
under vacuum and a green powdery residue remained in the flask, which
was brought back into a N2-filled drybox for workup and recrystalliza-
tion. The solid was redissolved in THF (5 mL) and the dark green solu-
tion was filtered to remove some dark, insoluble precipitate. The solution
was layered with hexanes (15 mL) and placed in the freezer for recrystal-
lization. Further recrystallization with DME and hexanes resulted in the
growth of blue crystals suitable for single-crystal X-ray diffraction studies.
The blue single-crystalline solid was obtained in 35% yield, based on the
{Cu3O2} stoichiometry (0.0533 g) and was separated from a dark green
sticky material that co-precipitated from green DME/hexanes solution.
UV/Vis (DME): lmax =280 (e=3958), 668 nm (57 cmꢀ1 mꢀ1); IR (neat):
n˜ =2963 (nC-H), 1552 (nCO3), 1459 (nCO3), 1300, 1199 (nC-F), 1175, 957
(nCu-OR), 700 cmꢀ1 (nC-F and nCu-OR); elemental analysis calcd (%)
for K2C15H21O8F12Cu: C 25.77, H 3.03, F 32.61; found: C 25.55, H 2.81, F
32.64; meff (Evans method, [D8]THF)=3.00 mB; meff (Evans method,
[D6]acetone)=3.08 mB.
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Acknowledgements
We are grateful for the financial support of Boston University, the Na-
tional Science Foundation (CHE 0910647 and CHE 0619339) and the
ACS Petroleum Research Fund (48022-AC3). We thank Professor J. P.
Caradonna and Dr. P. C. Tarves for helpful advice and sharing facilities
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Received: December 1, 2012
Published online: March 19, 2013
6384
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ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 6374 – 6384