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Cite This: Organometallics XXXX, XXX, XXX-XXX
Reductive Ring Opening of a Cyclo-Tri(phosphonio)methanide
Dication to a Phosphanylcarbodiphosphorane: In Situ UV-Vis
Spectroelectrochemistry and Gold Coordination
Sivathmeehan Yogendra,† Stephen Schulz,† Felix Hennersdorf,† Sarath Kumar,‡ Roland Fischer,§
and Jan J. Weigand*,†
Department of Chemistry and Food Chemistry, TU Dresden, 01062 Dresden, Germany
Department of Inorganic and Physical Chemistry, Indian Institute of Science, 560012 Bangalore, India
Department of Inorganic Chemistry, TU Graz, 8010 Graz, Austria
S Supporting Information
ABSTRACT: The formal two-electron reduction of the cyclotri(phosphonio)methanide dication 12+ results in a ring-opening
reaction via C−P bond cleavage to yield the unique phosphanylfunctionalized carbodiphosphorane 2. In situ spectroelectrochemical investigations of the reduction of dication 12+ and the
oxidation of 2 give insights into the mechanism of this unusual
and reversible bond cleavage reaction. Compound 2 features in
total three lone pairs of electrons, facilitating the preparation of
mono-, di-, and trigold complexes.
Scheme 1. (I) Stabilization of Ylides by the Introduction of
α-Phosphonio Groups, (II) Preparation of the
Carbodiphosphorane (Ph3P)2C, and (III) Reactivity of 12+
toward Fluoride Ions
hosphorus ylides are considered as reactive 1,2-dipolar
compounds that are now indispensable in organic
chemistry, especially in the Wittig olefination.1 The reactivity
of phosphorus ylides strongly depends on the α substituents
around the ylidic carbon atom. Neutral α-phosphonio ylides of
type A (Scheme 1, I) feature a strongly nucleophilic carbon
atom, rendering them inter alia as excellent ligands for metal
The introduction of two phosphonio substituents as
electron-withdrawing groups to give cations of type B stabilizes
the ylidic carbanion by forming negative hyperconjugation from
the lone pair of the C atom to the antibonding P−R orbitals of
the phosphonio groups (lone pair → σ*(P−R)).2a,3 This
facilitates the isolation of bisylidic carbodiphosphoranes bearing
a formally dianionic C atom in the zero oxidation state
(Scheme 1, II).4 The two lone pairs at the carbon atom of
carbodiphosphoranes with σ and π symmetry enable the
simultaneous coordination of two metal-based Lewis acids5 and
allow the stabilization of unique electron-deficient main-groupelement Lewis acids.6 Successful isolation of functionalized
bisylides was also accomplished by the introduction of
imidazolio7 or sulfonio8 groups as electron-withdrawing
substituents. The implementation of three phosphonio groups
into a ylidic carbanion gives tri(phosphonio)methanide salts of
type C, where the lone pair is strongly delocalized around the
CP3 moiety.9 In this context, we have recently reported on the
fluorophilic cyclo-tri(phosphonio)methanide dication 12+
(Scheme 1, III), which was prepared from a trifluoromethyl© XXXX American Chemical Society
Special Issue: Organometallic Chemistry in Europe
Received: August 2, 2017
DOI: 10.1021/acs.organomet.7b00597
Organometallics XXXX, XXX, XXX−XXX
sulfonyl-phosphonium dication10 via an intramolecular electrophilic aromatic substitution.11 Dication 12+ represents a waterresistant Lewis acid which is capable of binding fluoride ions
selectively and reversibly from an organic/aqueous biphasic
solution to give fluorophosphorane [1-F]+. Among other
effects, the ring strength of the five-membered cycle was
identified as a key factor for the high fluoride affinity of 12+.
This exceptional electrophilicity prompted us to investigate the
redox reactions of dication 12+.
A preparative access to the formal two-electron-reduction
reaction product of dication 12+ was found by using KC8 as a
chemical reduction reagent. The reaction of 1[OTf]2 with 2
equivalents of KC8 results in a ring-opening reaction via a C−P
bond cleavage to yield the unique phosphanyl-functionalized
carbodiphosphorane 2 isolated as a highly air and moisture
sensitive yellow solid in very good yield (81%, Scheme 2a).
In Scheme 2 a mechanistic rationalization of the formal twoelectron-reduction process with likely radical cationic intermediate [1]+• after the first electron transfer followed by the
ring-opening reaction and a final electron transfer to radical
cation [2]+• are depicted (ECE mechanism, where E denotes
electron transfer and C a homogeneous follow-up reaction
This reaction motivated a more detailed investigation of the
redox reaction of dication 12+ to 2 by the use of cyclic
voltammetry (CV), square wave voltammetry (SWV), and in
situ UV−vis spectroelectrochemistry (UV−vis SEC) during CV
measurements. Dication 12+ shows a reduction reaction that
appears to be irreversible in the CV measurement (Figure 2) at
a peak potential of EP = −2.18 V (vs E1/2(Cp2Fe/Cp2Fe+))
with a formal potential of E1/2 = −2.02 V from the SWV
measurement. This nonreversible reaction can possibly be
assigned to the reduction of dication 12+ to 2. In the second
cycle of the CV curve an irreversible emerging reoxidation
process appears at Ep = −0.35 V. CV and SWV assign this
process to a reoxidation of the reduction product 2 formed at
the electrode after a feasible follow-up reaction coupled to the
electron transfers. A minor side reaction process (marked by
asterisks) occurs according to the high moisture sensitivity of
the reduction product (likely a reversible reduction process of
protonated 2: [2-H]+/[2-H]•; Chapter 2.5 in the Supporting
In situ UV−vis SEC under ultradry conditions12 is used to
obtain further information about the product of the reduction
reaction as well as the reoxidation reaction and their assignment
to dication 12+ and 2. An in situ UV−vis measurement in a
double-compartment cuvette cell over four cycles of CV
(Figure 1, left) shows the formation of a species with an
absorbance maximum at 333 nm during the reduction process.
The potential product 2 of the reduction reaction is again
consumed during the reoxidation reaction, forming back the
starting material dication 12+. As deduced from this overall
chemically reversible process, reduction reactions of dication
12+ coupled to a potential follow-up reaction to the stable final
Scheme 2. Reaction of 1[OTf]2 with 2 equivalents of KC8 to
give 2 and a Postulated Electrochemical Pathwaya
Legend: a) +2 KC8, −2 KOTf, THF, −60 °C to room temperature,
81%; b) E < −2.02 V; c) E > −0.43 V vs E1/2(Cp2Fe/Cp2Fe+), THF,
0.1 M [nBu4N][OTf], Pt-mesh electrode, 0.5 mm cuvette cell.
Figure 1. In situ UV−vis SEC measurement (v = 15 mV/s) of dication 12+ (0.6 mM) in THF/0.1 M [nBu4N][OTf] at a platinum-mesh electrode in
a double-compartment cuvette cell (d = 0.5 mm): (left) 2D plot of differential UV−vis spectra during the CV measurement (four cycles); (upper
right) cyclic voltammogram; (lower right) absorbance of 12+ (red line) and 2 (blue line) during the measurement of the CV.
DOI: 10.1021/acs.organomet.7b00597
Organometallics XXXX, XXX, XXX−XXX
process at Ep = −0.29 V (E1/2 = −0.43 V) that is comparable
to the reoxidation of 2 in Figure 2 and a nonreversible
rereduction process at Ep = −2.07 V in the second cycle in
accordance with the start of the measurement from the redox
state of reduction product 2. No further evidence for a
persistent intermediate in the formal two-electron-reduction
process has been found. In situ UV−vis SEC data during a CV
measurement of carbodiphosphorane 2 under ultradry
conditions are depicted in Figure 3. The UV−vis data show
an overall chemical reversible switching between the starting
material 2 and the oxidation product 12+. Dication 12+ (Figure
1) and neutral 2 (Figure 3) show exactly the same redox
behavior, but in an inverted manner. The UV absorbance of
dication 12+ (Figure 3, lower right, blue line) and neutral 2 (red
line) show the expected correlation to the nonreversible peaks
in the in situ CV (Figure 3, upper right).
Since the overall two-electron reduction coupled to a
homogeneous follow-up reaction is quite uncommon, the
method of chronoamperometry with multiple potential steps
under in situ UV−vis monitoring was used. Switching between
the open circuit potential, the oxidation potential Eox = 0.30 V
and the rereduction potential Erered = −2.56 V results in a
current vs time profile and an absorbance vs time profile
(Figure 4, left) from the in situ UV−vis (Figure 4, right) data.
On the basis of the assumption of full conversion of the thinlayer compartment of the cuvette cell volume during the
reduction reaction a theoretical charge for a two-electron
process can be calculated12 (Figure 4, dotted line) which is
consistent with the experimental data. From this measurement
a repeated switching between 2 and 12+ consumes ≈ 2e− per
molecule 12+ within the tolerances of the method. On the basis
of the molar extinction coefficient of the chemically prepared
carbodiphosphorane 2 at 333 nm absorbance and of dication
12+ at 243 nm a correlation to the number of electrons for both
the reduction (Figure S2.4 in the Supporting Information: in
situ UV−vis MPCA of 12+ vs UV−vis of 2) and reoxidation
(Figure S2.5 in the Supporting Information: in situ UV−vis
MPCA of 2 vs UV−vis of 12+) are in accordance with an overall
Figure 2. Cyclic voltammogram (v = 0.1 V/s) and square wave
voltammogram of triflate salt 1[OTf]2 (1.67 mM) in THF/0.1 M
[nBu4N][OTf] at a 3 mm platinum-disk electrode.
reduction product 2 causes the nonreversible peak shape of this
process in the cyclic voltammogram (vide inf ra).
The CV curve based on the UV−vis absorbance changes for
the starting material 12+ (Figure 1, right, red line) as well as for
the potential reduction product 2 (Figure 1, right, blue line) are
in accordance with the in situ CV (Figure 1, upper graph). A
cyclic switching between dication 12+ starting material and its
stable reduction product 2 at the nonreversible CV peak
positions is observed over four cycles. Only slight changes in
the relative absorbance are observed after the measurement
cycles because of the UV sensitivity of 12+.12 In situ UV−vis
SEC under full conversion conditions (Figure S2.2 in the
Supporting Information) and UV−vis multi pulse chronoamperometry (UV−vis MPCA, Figure S2.3 in the Supporting
Information) further support this observation.12 The observed
chemical reversibility of the reduction process of dication 12+
(Scheme 2b,c) to neutral 2 in the in situ SEC prompted us to
take a more detailed look into the oxidation process of 2. A CV
and SWV measurement of 2 in THF (Figure S2.1 in the
Supporting Information) shows a nonreversible oxidation
Figure 3. In situ UV−vis SEC measurement (v = 15 mV/s) of carbodiphosphorane 2 (1.18 mM) in THF/0.1 M [nBu4N][OTf] at a platinum-mesh
electrode in a double-compartment cuvette cell (d = 0.5 mm): (left) 2D plot of differential UV−vis spectra during the CV measurement (three
cycles); (upper right) cyclic voltammogram; (lower right) absorbance of 2 (red) and 12+ (blue) during the CV measurement.
DOI: 10.1021/acs.organomet.7b00597
Organometallics XXXX, XXX, XXX−XXX
Figure 4. In situ UV−vis multi pulse chronoamperometry of carbodiphosphorane 2 (1.18 mM) in THF/0.1 M [nBu4N][OTf] at a platinum-mesh
electrode in a double-compartment cuvette cell (d = 0.5 mm); (left, top to bottom) potential profile, chonoamperogram (I has been corrected by I0
to compensate for the additional diffusion of 2 form the bulk part of the cuvette cell to the electrode), chronocoulogram, chronoabsorptiometry;
(right) 2D plot of in situ differential UV−vis spectra during the MPCA measurement.
= 16 Hz) in the 13C{1H} NMR spectrum and is shifted
significantly downfield in comparison to the unsubstituted
carbodiphosphorane (Ph3P)2C (δ = 12.5 ppm, 1JCP = 127
Hz).12 This effect is explained by a donor−acceptor interaction
between one lone pair of electrons of the C atom and the
σ*(P1−C13) orbital (vide inf ra).
The molecular structure of compound 2 is depicted in Figure
5 and displays the expected bent geometry for the C1 atom
two-electron process. The UV−vis spectra are also in very good
agreement with the in situ data, further confirming the
assignment to carbodiphosphorane 2 and dication 12+ in the
in situ measurements. During the fast potential change no
indication of intermediates can be found in the UV absorbance.
Combining the results from the preparative synthesis of 2
and the in situ UV−vis SEC data of 12+ and 2, the nonreversible
character of the reduction and oxidation is most likely explained
by the ring opening reaction (vide supra) as a necessary followup reaction step in the reduction of 12+ to 2. From in situ UV−
vis CV and MPCA measurements no further hints of transient
intermediates on the time scale of the experiments were found.
Since the P−C bond cleavage and formation take place during
the reduction of 12+ and oxidation of 2, a chemical step is
necessarily involved in the mechanism. A description of the
electrode mechanism as a likely ECE mechanism (Scheme 2,
bottom) is favorable, when taking a very fast chemical follow-up
reaction into account. Peak parameters from CV measurements
(Figure S2.10 − S2.16 in the Supporting Information) at scan
rates up to 750 V s−1 are in accordance with this hypothesis.
An alternative EEC electrode reaction mechanism is to the
best of our knowledge less favorable, because the P−C bond
cleavage as well as the P−C bond formation only take place
after an electron transfer. Further mechanistic investigations are
necessary to prove the hypothetical ECE electrode reaction
mechanism.12 However, the nonreversible appearance of the
two-electron reduction and oxidation reaction as well as the
over the whole electrode reaction reversible reaction between
dication 12+ and neutral 2 coupled to a homogeneous reaction
step are a rare example in the chemistry of reactive main-groupelement species.
The 31P{1H} NMR spectrum of 2 displays an AMX spin
system. Part A appears as a doublet at δ(PA) = −17.7 ppm (3JPP
= 21 Hz), which is assigned to the phosphanyl moiety. The M
part appears as a dd resonance at δ(PM) = −6.9 ppm for the
−Ph2PV− moiety (2JPP = 93 Hz and 3JPP = 21 Hz) and the X
part reveals a doublet at δ(PX) = −3.4 ppm for the Ph3P
substituent. The distinct ddd resonance for the central C atom
is observed at δ = 18.1 ppm (1JCP = 136 Hz, 1JCP = 134 Hz, 4JCP
Figure 5. Molecular structure of 2 (hydrogen atoms are omitted for
clarity, and thermal ellipsoids are displayed at 50% probability).
with a slightly larger P2−C19−P3 angle of 140.74(8)° in
comparison to the respective P−C−P angle in (Ph3P)2C
(131.7(3)°).5b,13 The short P−C bonds in 2 (C19−P2
1.636(1) Å, C19−P3 1.642(2) Å) are in accordance with
those observed in other carbodiphosphoranes and refer to a
strong degree of negative hyperconjugation. The short P1···C19
contact (3.035(2) Å, ∑vdW(C, P) 3.5 Å)14 and the linear
arrangement of the C19···P1−C13 fragment are noticeable
(178.40(4)°), confirming a certain degree of donor−acceptor
interaction. The angles P1−C1−C6 (120.80(9)°) and P2−
C6−C1 (120.09(9)°) are widened in comparison to those in
precursor 12+ (P2−C3−P2 114.9(2)°, P1−C2−C3 113.9(2)°),
which leads to reduced angle tension and thus indicates that the
ring opening might be a driving force for the formation of 2.
DOI: 10.1021/acs.organomet.7b00597
Organometallics XXXX, XXX, XXX−XXX
Compound 2 represents a rare example of a carbodiphosphorane that features in total three donor functionalities.
Consequently, 2 features a multidentate donor for metal
coordination. The reaction of 2 with [AuCl(tht)] in a 1:1 ratio
results in the formation of the corresponding gold complex 3,
where the AuCl is coordinated to the carbodiphosphorane
moiety (yield 96%, Scheme 3a). In sharp contrast to the air-
Scheme 4. Reaction of 3 with NH4BF4 To Give the Complex
Scheme 3. Reaction of 2 with 1−3 equivalents of [AuCl(tht)]
(tht = Tetrahydrothiophene) to give mono-, di-, and trigold
Complexes 3, 5, and 6a
Legend: a) +NH4BF4, −NH3, THF, 12 h, room temperature, 55%.
donor for the second equivalent of AuCl rather than the carbon
atom (yield 93%, Scheme 3b).
The 31P{1H} NMR spectrum of 5 measured at 22 °C reveals
three broad resonances at δ = 25.8 ppm (ν1/2 = 50 Hz), 21.5
ppm (ν1/2 = 130 Hz), and 10.8 ppm (ν1/2 = 95 Hz), indicating
the presence of a dynamic process (Figure 6, top).
Legend: a) +[AuCl(tht)], −tht, THF, room temperature, 96%; b) +
2[AuCl(tht)], −2 tht, THF, room temperature, 93%; c) +3[AuCl(tht)], −3tht, THF, room temperature, 98%.
stable congener [AuCl((Ph3P)2C)],15 complex 3 is obtained as
a highly reactive and air sensitive solid, which readily
decomposes in C−H acidic solvents such as CH2Cl2,
CH3CN, DMSO, and DMF and is insoluble in THF, oC6H4F2, and C6H5F. However, it is poorly soluble in o-C6H4Cl2
(∼4 mg/mL) but decomposes slowly, as indicated by 31P NMR
spectroscopic investigations showing decomposition of up to
7% after 12 h (Figure S3.1 in the Supporting Information).12
The 31P{1H} NMR spectrum of 3 was recorded in o-C6D4Cl2
at −10 °C in order to decrease the decomposition rate and
reveals an AMX spin system.
The A part resonates as a doublet at δ(PA) = −18.1 ppm
consistent with the phosphanyl moiety. The M and the X parts
are assigned to the Ph3PV− and −Ph2PV− substituents,
respectively, and are observed at lower field due to the metal
coordination with resonances at δ(PM) = 8.6 ppm and δ(PX) =
18.7 ppm (2JPP = 52 Hz and 3JPP = 23 Hz), respectively.
Complex 3 can be protonated with NH4BF4 to give
quantitatively complex 4[BF4] (isolated yield 55%, Scheme
4). This reaction likely proceeds via protonation of the carbon
atom to give intermediate I. A related derivative represents the
known salt [(Ph3P)2CH(AuCl)][OTf].5c However, hypothetical intermediate I is not stable and subsequently rearranges
to the air-stable complex 4[BF4]. This possible AuCl
rearrangement of complex 3 also explains the unusual high
reactivity toward C−H acidic solvents (vide supra).
The 31P{1H} NMR spectrum of 4[BF4] displays the expected
AMX spin system where the A part is assigned to the
Ph2PIII(AuCl) moiety with a resonance observed at lower field
at δ(PA) = 19.6 ppm in comparison to 3. The M and X parts are
assigned to the −Ph2PV− and Ph3PV− moieties, respectively,
and also display downfield-shifted resonances at δ(PM) = 24.8
ppm and δ(PX) = 28.3 ppm (2JPP = 9.1 Hz, 3JPP = 20.5 Hz).
The reaction of 2 with [AuCl(tht)] in a 1:2 ratio forms the
digold complex 5, in which the phosphanyl moiety acts as the
Figure 6. (top) Variable-temperature 31P{1H} NMR spectra of 5
measured in CD2Cl2 at 22, −28, and −68 °C. A1M1X1 and A2M2X2
spin systems are assigned to two different rotamers of 5. (bottom)
31 1
P{ H} 31P{1H} EXSY NMR spectrum of 5 (−48 °C, mixing time 0.2
s, CD2Cl2; unidentified side product is marked with an asterisk).
Upon cooling to −68 °C the 31P{1H} NMR spectrum
displays two comparable AMX spin systems, designated as
A1M1X1 and A2M2X2. The A1M1X1 spin system resonates at
δ(A1) = 9.5 ppm for Ph2PIII(AuCl)−, δ(M1) = 20.2 ppm for
−Ph2PV−, and δ(X1) = 25.6 ppm for Ph3PV moiety (2JPP = 47
Hz and 3JPP = 8 Hz).
DOI: 10.1021/acs.organomet.7b00597
Organometallics XXXX, XXX, XXX−XXX
The A2M2X2 spin system reveals the respective resonances at
δ(A2) = 12.5 ppm, δ(M2) = 24.1 ppm, and δ(X2) = 25.2 ppm
(2JPP = 48 Hz and 3JPP = 8 Hz). The 31P{1H}31P{1H} EXSY
NMR spectrum proves a dynamic exchange process indicative
of different rotamers of 5 (Figure 6, bottom).12 From the
variable-temperature NMR spectra recorded between −30 and
−80 °C, an increasing intensity is observed for the A1M1X1 spin
system when reaching lower temperatures, as indicated by the
different A1:A2 ratio of 1.5:1 at −30 °C compared to that of
2.5:1 at −80 °C.
The reaction of 2 with [AuCl(tht)] in a 1:3 ratio results in
the formation of the corresponding trigold complex 6, in which
two AuCl moieties are coordinated to the carbon atom and one
AuCl fragment to the phosphanyl group (yield 98%, Scheme
Table 1. Selected Bond Lengths (in Å) and Angles (in deg)
of Crystallographically Characterized Complexes 2, 3, 4+, 5,
and 6
indicating sp2 hybridization. As expected, the P2/P3−C19 bond
lengths increase upon coordination or protonation at the C19
atom, as observed in complexes 3, 4+, and 5. This is explained
by the reduced negative hyperconjugation of the π-type lone
pair of electrons at the C19 atom into the σ*(P−R) orbitals in
comparison to the carbodiphosphorane 2. Interestingly, the
second gold coordination in 5 leads to a slight shortening of the
P2/3−C19 bonds in comparison to those observed in complex
3. Complex 6 displays a distorted-tetrahedral bonding environment around the C19 atom and reveals the longest P2/3−C19
bonds due to the double auration of the carbon atom, disabling
the aforementioned negative hyperconjugation. The Au−C19
bond lengths in 6 (Au3−C19 2.089 Å, Au2−C19 2.064 Å) are
slightly longer than those observed in complexes 3 (Au1−C19
2.043 Å) and 5 (Au2−C19 2.037(3) Å) but are in the expected
range of doubly gold coordinated carbodiphosphoranes.5b,c,16
In conclusion, the formal two-electron reduction of the
highly electrophilic cyclo-tri(phosphonio)methanide dication
12+ results in the formation of the phosphanyl-functionalized
carbodiphosphorane 2. Detailed investigations of the redox
reaction by in situ UV−vis spectroelectrochemistry reveal the
overall two-electron nature of this process with an reversible
P−C bond cleavage as a follow-up reaction. The phosphanyl
carbodiphosphorane 2 represents a rare example of such
compounds with three donor functions. These donor functions
were utilized to synthesize gold(I) complexes with one (3), two
(5), and three (6) coordinated AuCl fragments.
Figure 7. Molecular structure of 4+ (selected hydrogen atoms are
omitted for clarity, and thermal ellipsoids are displayed at 50%
Similar to the case for the digold complex 5, the 31P{1H}
NMR spectrum of 6 reveals broad resonances at 27 °C which
show at −50 °C one distinct AMX spin system (Figure S3.2 in
the Supporting Information).12
The A part resonates as a doublet at δ(PA) = 14.1 ppm and is
assigned to the Ph2P(AuCl) moiety. The M and X parts are
assigned to the Ph3PV− and −Ph2PV− moieties, respectively,
and display resonances at δ(PM) = 25.4 ppm and δ(PX) = 26.9
ppm, which are shifted slightly downfield due to the second
gold coordination at the C atom in comparison to the
complexes 3 and 5.
The molecular structures of complexes 3, 4+, 5, and 6 are
depicted in Figures 7 and 8, and selected geometrical
parameters are given in Table 1. Complexes 3, 4+, and 5 reveal
a trigonal-planar bonding environment around the C19 atom
S Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organomet.7b00597.
Experimental procedures, characterization data, spectroscopic data, crystallographic data, and additional CV and
in situ UV−vis spectroelectrochemical data (PDF)
Figure 8. Molecular structures of 3, 5, and 6 (hydrogen atoms are omitted for clarity, and thermal ellipsoids are displayed at 50% probability).
DOI: 10.1021/acs.organomet.7b00597
Organometallics XXXX, XXX, XXX−XXX
Accession Codes
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CCDC 1560752−1560756 contain the supplementary crystallographic data for this paper. These data can be obtained free of
charge via, or by emailing, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
Corresponding Author
*E-mail for J.J.W.:
Felix Hennersdorf: 0000-0002-3729-030X
Jan J. Weigand: 0000-0001-7323-7816
Author Contributions
S.Y. performed the synthesis and characterization, and S.S.
performed the electrochemical and spectroelectrochemical
measurements and the data analyses. Both authors contributed
equally and share first authorship. F.H. and R.F. performed
single crystal X-ray diffraction and data analysis, and S.K.
assisted in the synthesis and characterization. J.J.W. supervised
this project.
The authors declare no competing financial interest.
This work was supported by the European Research Council
(ERC, SynPhos 307616) and Fonds der Chemischen Industrie
(FCI, Scholarship for F.H.). J.J.W. thanks the DFG for funding
a diffractometer (INST 269/618-1)
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DOI: 10.1021/acs.organomet.7b00597
Organometallics XXXX, XXX, XXX−XXX
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