Synthesis, Electronic Structure, and Reactivities of Two-Sulfur-Stabilized Carbones Exhibiting Four-Electron Donor Ability

Article abstract of DOI:10.1002/chem.201700863

Bis(sulfane)carbon(0) (BSC; Ph₂S→C←SPh₂ (1)) is successfully synthesized by deprotonation of the corresponding protonated salt 1?HTfO. The diprotonated salt 1?(HTfO)₂ as the starting material can be also easily accessed by

Full text of DOI:10.1002/chem.201700863

A Journal of
Accepted Article
Title: Synthesis, Electronic Structure, and Reactivities of Two-Sulfur
Stabilized Carbones Exhibiting Four-electron Donor Ability
Authors: Tomohito Morosaki, Ryo Iijima, Tsubasa Suzuki, Wei-Wei
Wang, Shigeru Nagase, and Takayoshi Fujii
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To be cited as: Chem. Eur. J. 10.1002/chem.201700863
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Synthesis, Electronic Structure, and Reactivities of Two-Sulfur
Stabilized Carbones Exhibiting Four-electron Donor Ability
Tomohito Morosaki[a], Ryo Iijima[a], Tsubasa, Suzuki[a], Wei-Wei Wang[b], Shigeru Nagase[b], Takayoshi
Fujii*[a]
Dedicated to Professor Marian Mikołajczyk on the occasion of his 80th birthday
Abstract: Bis(sulfane)carbon(0) (BSC; Ph2S→C←SPh2 (1)) is
successfully synthesized by deprotonation of the corresponding
protonated salt 1·HTfO. The diprotonated salt 1·(HTfO)2 as the
starting material can be also easily accessed by the deimination of
iminosulfane(sulfane)carbon(0) (iSSC)·HBF4. Density functional
theory calculations revealed the peculiar electronic structure of 1
having two lone pairs of electrons at the central carbon atom. The
largest proton affinities (PA(1): 297.5 kcal mol−1; PA(2) 183.7 kcal
mol−1) and the highest energy levels of the HOMOs (HOMO: −4.89
eV; HOMO−1: −5.02 eV) for 1 among the two-sulfur-stabilized
carbones clearly indicate the strong donor ability of carbon center
stabilized by two SII ligands. The donating ability of these lone pairs
of electrons is demonstrated by the C-diaurated and C-proton-
aurated complexes, which provide the first experimental evidence for
two-sulfur-stabilized carbones behaving as four-electron donors.
Furthermore, the syntheses and application of AgI carbone
complexes as carbone transfer agents are also reported.
carbon bases is that carbones can bind two Lewis acids
whereas carbenes usually bind to only one owing to the number
of lone pairs.[1–7] This has been theoretically verified by the high
value of their first and second proton affinities (PAs), as well as
their high affinities to electrophiles.[1] Further theoretical and
experimental work has revealed that the - and -lone pairs in
carbones can simultaneously donate to stabilize double-Lewis-
acids with vacant - and -orbitals.[8]
The species most commonly utilized to confirm the carbone
character of
a compound are experimentally synthesized
diaurated complexes, in which the central carbon binds to two
gold(I) atoms in 1 mode.[9] Alcarazo et al. reported the
syntheses and characterization of a series of mono- and
diaurated complexes containing various heteroleptic carbones
stabilized by one phosphane and one carbene ligand.[10] They
concluded that C-diauration using the central carbon reveals the
four-electron-donating ability of carbones, and that it should be
used as a definitive indicator for the carbon(0) character of
divalent carbon compounds. Thus, the C-diauration of a central
carbon atom has become established as a criterion for the
definition of carbone character. This coordination behavior is
also utilized to predict the carbone character of compounds.[11]
These unique concepts of carbones have provided a starting
point for exploring the possible extension of the bonding concept,
and this exploration has allowed the development of useful
guidelines for the syntheses of -donor stabilized low-valent
main-group atoms, such as EL2 (E = C, Si, Ge, Sn, or Pb;
tetrylone or ylidone).[1h,1j,12]
Introduction
Divalent carbon(0) species, also known as carbones are a
newly recognized class of compounds that exhibit unique
bonding and donating characteristics at the central carbon.[1]
The central zero-valent carbon atom of carbones possesses all
four valence electrons in - and -type lone pair orbitals and is
stabilized by two strongly electron-donating ligands (L), such as
the phosphane ligands in carbodiphosphoranes (also termed
bis(phosphane)carbon(0) (BPC: A)), or the carbene ligands in
carbodicarbenes (bis(carbene)carbon(0) (BCC)), through donor-
acceptor interactions (Scheme 1).[2–6] Thus, CL2 carbones are
also regarded as carbon(0) complexes (L→C0←L) that are
analogous to metal complexes. These electronic structures
clearly distinguish carbones from divalent carbon(II) species, i.e.,
carbenes (R-C-R), which have only one lone pair and one
vacant p orbital on the CII atom, and contain covalent bonds to
the R substituents.[1] The obvious difference between these
Scheme 1. a) schematic representation of carbones CL2; b) molecular
structures of A–G.
[a]
Dr. T. Morosaki, R. Iijima, T. Suzuki, Prof. T. Fujii
Department of Applied Molecular Chemistry, College of Industrial
Technology, Nihon university
Recently, we extended the carbone chemistry toward the
phosphorus-
and
sulfur-stabilized
carbones
Chiba 275-8575 (Japan)
E-mail: fujii.takayoshi@nihon-u.ac.jp
(iminosulfane(phosphane)carbon(0) (iSPCs: B–D) and revealed
their carbone character using the diaurated- and proton-aurated
complexes (Figure 1).[13] We also reported the syntheses and
reactivities of bis(chalcogenane)carbon(0) species (BChCs),
[b]
Dr. W. Wang, Prof. S. Nagase
Fukui Institute for Fundamental Chemistry, Kyoto University
Kyoto 606-8103 (Japan)
including
iminosulfane(sulfane)carbon(0)
bis(iminosulfane)carbon(0)
(iSSC:
(BiSC:
F),
E),
and
Supporting information for this article is given via a link at the end of
the document.((Please delete this text if not appropriate))
iminosulfane(selenane)carbon(0) (iSSeC: G), and suggested
that replacement of the iminosulfane (SIV) ligand with a sulfane
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(SII) or selenane (SeII) ligand leads to an increase in the
reactivity of the carbon center.[14]
The molecular structures of 1·(HTfO)2 and 1·HTfO were
determined by X-ray crystallography (Scheme 3). Selected bond
lengths and angles of 1·(HTfO)2 and 1·HTfO are given in Table 1
together with data for E, F, and their monoprotonated salts
E·HClO4 and F·HBF4. The reported structure of 1·(HTfO)2
represents the first full characterization of a diprotonated salt of
a two-sulfur-stabilized carbone (Scheme 3), and shows that the
central carbon atom of 1·(HTfO)2 binds to two protons. The
S→C distances are shortened upon the deprotonation
(1·(HTfO)2: 1.818 Å and 1.816 Å; 1·HTfO: 1.685 Å and 1.676 Å).
The former are comparable to single bond lengths (S–C: 1.81 Å),
whereas the latter are similar to those of E·HClO4 (1.695 Å and
1.691 Å) and F·HBF4 (1.695 Å and 1.672 Å).[14] The S→C←S
bond angle becomes more acute in the following order: 1·HTfO
(112.6°), F·HBF4 (113.5°), E·HClO4 (118.0°). This may indicates
the presence of significant electron density at the central carbon,
owing to the fact that Ph2S ligands are weaker -acceptor
ligands than Ph2SNMe.
While representative two-chalcogen-stabilized carbones
have been accessed, there have been no reports of such
systems stabilized by two SII ligands. Moreover, the four-
electron-donating ability of two-sulfur-stabilized carbones, such
as in diaurated complexes or dicationic salts, has not been
experimentally demonstrated. Herein we report the synthesis,
electronic structure, and four-electron donating ability of the first
example of two-SII-stabilized carbones (bis(sulfane)carbon(0)
(Ph2S→C←SPh2, BSC: 1)). We also present a comparison of 1
to previously reported two-sulfur-stabilized carbones. The
syntheses of AgI complexes and their application as carbone
trasnfer reagents are also described.
Results and Discussion
At the outset of our study, we attempted the preparation of
the dicationic salt 1·(HTfO)2 as a precursor for two-SII-stabilized
carbones by the reaction of Ph2S with diiodomethane (DIM) in
the presence of AgTfO following a protocol analogous to the one
Scheme 2. Reaction of Ph2S with CH2I2 and molecular structure of
[Ph2SCH2I]TfO. Hydrogen atoms (except for that on Ccenter) and TfO anions are
omitted for clarity. Reagents and conditions: a) AgTfO, MeCN, reflux, 24 h;
[Ph2SCH2I]TfO (89%) .
[7a]
described for the synthesis of BPC·(HBr)2
(Scheme 2).
However, the reaction gave the sulfonium salt [Ph2SCH2I]I in
89% yield and only a trace amount of 1·(HTfO)2 was obtained.
We also attempted the reaction of [Ph2SCH2I]TfO with Ph2S in
the presence of AgTfO, but 1·(HTfO)2 was not obtained. This
may due to the weaker nucleophilicity of S atom than that of P
atom.
Unexpectedly, the desired dicationic salt 1·(HTfO)2 is
obtained by the deimination of F·HBF4. When solid-state F·HBF4
is treated with excess amount of TfOH at −40 °C, the reaction
mixture immediately turns dark green, indicating that
a
deimination process occurs (Scheme 3).[15] The 1H NMR spectra
of 1·(HTfO)2 presents the central proton signal at  = 6.60 ppm,
and the central carbon resonance is observed at  = 55.3 ppm in
the 13C NMR spectra. 1·(HTfO)2 can be isolated as air- and
moisture-stable colorless crystals in 56% yield, confirming the
double basicity of the central carbon atom in 1.
One of the two protons at the carbon center of 1·(HTfO)2 is
easily abstracted by reaction with K2CO3, affording the
monoprotonated salt 1·HTfO. Interestingly, the central proton
and carbon resonances of 1·HTfO (1H:  = 3.88 ppm; 13C:  =
19.4 ppm) are observed at significantly higher field than those of
E·HClO4 1H:  = 5.18 ppm, 13C:  = 39.3 ppm) and F·HBF4 1H:
 = 4.69 ppm; 13C:  = 30.9 ppm), indicating the presence of
significant electron density at the central carbon of 1.[14]
Scheme 3. Synthesis of 1 and molecular structures of 1·(HTfO)2 and 1·HTfO.
Hydrogen atoms (except for that on Ccarbone) and TfO anions are omitted for
clarity. Reagents and conditions: a) TfOH (11 eq.), −40 °C to r.t., 3 h;
1·(HTfO)2 (56%) b) K2CO3, MeCN, r.t., 2 h; 1·HTfO (80%); c) NaNH2, THF,
−30 °C, 2 h; 1 (quant.). TfOH = trifluoromethanesulfonic acid.
The addition of 1·HTfO to an equimolar
amount of potassium hexamethyldisilazide
(KHMDS) at −80 °C in THF resulted in the
Table 1. Selected bond lengths (Å) and angles (°) of 1·(HTfO)2, 1·HTfO, 1, E·HClO4, F·HBF4, E, and F.
immediate formation of a yellow solution.
However, upon warming to room
[a]
[a,c]
[a,d]
1·(HTfO)2
1·HTfO[a]
1[b]
E·HClO4
F·HBF4
E[a,c]
F[a,d]
temperature, the solution becomes colorless,
and room temperature 1H NMR analysis
revealed the presence of two equivalents of
diphenylsulfide. The thermal instability of 1
may be attributed to the weak -acceptor
ability of SII ligands. However, when the
reaction is performed in an NMR tube in
[D8]THF at −30 °C, a single product is
observed, which is consistent with the
1.818(2),
1.816(2)
1.685(5),
1.676(6)
1.713,
1.712
SII→C
–
1.6951(14)
1.6723(14)
113.54(8)
–
1.708(2)
1.695(2),
1.691(2)
1.636(2)
1.635(4)
SIV→C
E→C←E
–
–
–
1.648(2)
106.67(14)
105.8(10)
112.6(3)
105.2
118.0(1)
116.8(2)
[a] Experimental values. [b] calculated values at B3PW91/6-311G(d,p) level. [c] Ref. 14a. [d] Ref. 14b
1
generation of 1 (Scheme 2). In the H NMR
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spectra, the addition of NaNH2 to an [D8]THF solution containing
1·HTfO resulted in the complete disappearance of signal
assigned to the monocation. Additionally, the original 13C NMR
signal of 1·HTfO ( = 15.4 ppm) disappeared and a new signal
at  = 41.8 ppm cleanly emerged, which is shifted to lower field
than those of E (39.5 ppm) and F (35.3 ppm).[16] 1 decomposes
slowly at −30 °C and very rapidly at room temperature in
[D8]THF solution, forming diphenylsulfide.
Figure 1. The optimized structure of 1 (left) and its HOMO (center) and
HOMO–1 (right).
The molecular structure of
1
was investigated
computationally (Figure 1). Density functional theory (DFT)
calculations at B3PW91/6-311G(d,p) level of theory gave S→C
bond distances for 1 (1.713 Å and 1.712 Å) that are slightly
longer than the experimental values for monoprotonated salt
1·HTfO. The elongation of distance between central carbon and
Ph2S ligands is in contrast to the trend typically seen with other
-accepting ligands,[1–7] and it should be attributed to the
electronic repulsion between the lone pairs on the SII and central
C0 atoms.[14b] This could be considered as a characteristic
feature of ligands bearing two lone pairs on the coordinated
atoms. These structural features suggest that the n-*
interaction between C0 and the Ph2S ligands may be significantly
reduced. The central carbon of 1 is in a significantly bent
conformation (105.2°), which is more acute than that of 1·HTfO
and nearly matches that of 1·(HTfO)2 (105.8°). In fact, the
S→C←S arrangements seen here are among the most bent of
the experimentally characterized acyclic carbones (105.5–
180°).[1–7,13,14,17] The angle tends to become more acute upon
deprotonation, and shows a similar trend to that observed for E
and F.
Molecular orbital analyses indicate that the central carbon
atom of 1 has lone pair orbitals for the HOMO (nC) and the
HOMO−1 (nC; Figure 1). The comparison of energy levels of
HOMOs revealed that 1 (HOMO: −4.89 eV; HOMO−1: −5.02 eV)
has the strongest donor ability among the two-sulfur-stabilized
carbones (Table 2). The nC of 1 has significantly enhanced s
character (63%) compared to those of E (42%) and F (55%),
whereas nC has 100% p character. Natural bond orbital (NBO)
analyses indicate that the occupancy of nC (1.91) is
significantly higher than those of E (1.75) and F (1.84), which
suggests the significant lessening of back-donation (n-*
interaction) from the nC of the central carbon to the adjacent *
orbitals of the SII ligands. In fact, the stabilization energy for nC
(Etotal = 1.1 kcal mol–1) indicates the almost no n-* interaction
from the nC to the *(SII–CPh) compared to those for
corresponding carbones stabilized by SIV ligands (E: Etotal = 34.1
kcal mol–1, F: Etotal = 15.1 kcal mol–1; see Table S11 in the
Supporting Information), as determined by NBO second-order
perturbation analysis. Conversely, the occupancy and
stabilization energy for nC (Occ.: 1.48; Etotal = 55.49 kcal mol–1)
are similar to those of E (Occ.: 1.53; Etotal = 63.14 kcal mol–1)
and F (Occ.: 1.52; Etotal = 54.79 kcal mol–1). These results
indicate that the replacement of SIV with SII ligands mainly
effects an increase in the electron density of the -type lone pair.
The natural population analysis (NPA) charge on the central
carbon atom of 1 (−1.15 a.u.) is large and negative, similar to
those of E (−1.24 a.u.) and F (−1.20 a.u.).[14] The Wiberg bond
index values for the S→C (1.22) bonds of 1 are similar to those
for E (1.20 and 1.22) and F (1.18 and 1.24).
Table 2. Calculated energy levels of the HOMO, HOMO−1 and proton
affinities (PAs) of 1, E, and F at B3PW91/6-311G(d,p)
HOMO
[eV]
HOMO−1
[eV]
PA(1)
[kcal mol−1
PA(2)
[kcal mol−1
]
]
1
E
F
−4.89
−5.26
−5.08
−5.02
−5.56
−5.32
297.5
278.8
288.0
183.7
182.2
184.4
To verify carbone character, we calculated the first and
second PAs (PA(1) and PA(2)) of 1 and compared them with the
theoretically predicted PAs of E and F (Table 2). As expected,
among the two-sulfur-stabilized carbones, the largest value of
PA(1) (297.5 kcal mol−1) is predicted for 1. The relatively large
value of PA(2) (183.7 kcal mol−1) suggests that 1 possesses
carbone character. These results are consistent with the
generation of the dicationic salt 1·(HTfO)2. PA(1) is mainly
determined by the energy level of the highest occupied  orbital
of neutral carbone 1, whereas PA(2) is mainly determined by the
highest occupied  orbital of monoprotonated 1·H+.[1]
Encouraged by the relatively high electron-donating ability of
1, we attempted to ascertain whether the central carbon of two-
sulfur-stabilized carbones could actually serve as a four-electron
donor. We also synthesized and characterized AuI complexes
containing E and F as ligands for comparison. The reaction of
freshly generated 1, E, and F at −40 °C with [AuCl(PPh3)] and
subsequent addition of NaTfO in THF results in the respective
formation of monoaurated complexes 2–4 (Scheme 4). The
desired diaurated complexes 5–7 are efficiently obtained by
treating 1, E, and F, respectively, with two equivalents of
[AuCl(PPh3)]/AgTfO (Scheme 4). This substantiates the
coordination ability of the second lone pair in the two-SII-
stabilized carbones. Even more interestingly, the cationic salts
1·HSbF6 and F·HBF4 react smoothly with [Au(PPh3)Cl]/AgX (X =
SbF6 or BF4) to give the corresponding proton-aurated species 8
and 9, respectively, despite their cationic character (Scheme 5).
The generation of 8 and 9 containing cations 1·H+ and F·H+,
respectively, as ligands clearly indicates the lone pair character
at the carbon center in these cations. In the 31P NMR spectra,
the signals for mono- (2: 42.0 ppm; 3: 39.0 ppm; 4: 40.8 ppm),
di- (5: 36.4 ppm; 6a: 34.3 ppm; 7: 36.0 ppm), and proton-aurated
(8: 37.8 ppm; 9: 38.1 ppm) complexes are observed as singlets,
and are similar to those of the gold(I) complexes of A–D ( =
34.9–41.3 ppm).[10d,13] In the 13C NMR spectra, the central
carbon resonances of the monoaurated complexes (2: 65.4 ppm,
2
2
2JPC = 134 Hz; 3: 65.1 ppm, JPC = 98.2 Hz; 4: 67.4 ppm, JPC
=
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2
116 Hz) and the proton-aurated complexes (8: 66.0 ppm, JPC
=
2
82.6 Hz; 9: 72.1 ppm, JPC = 78.9 Hz) appear as doublets, but
the central carbon resonances of the diaurated complexes 5–7
were not observed.
Table 3. Selected bond lengths (Å) and angles (°) of 5–9
Lengths(Å)
5
6
7
8
9
2.116(6),
2.084(5)
2.126(4),
2.125(4)
2.130(3),
2.103(3)
C→Au
Au−Au
P→Au
2.090(7)
–
2.098(3)
–
3.0022(4)
2.9671(7)
2.9551(7)
2.2749(16),
2.266
2.2780(11),
2.2788(13)
2.2751(11),
2.2716(10)
2.2726(18)
2.2711(10)
1.782(6),
1.767(6)
1.837(7),
1.805(7)
SII→C
SIV→C
–
1.792(3)
1.746(3)
1.796(3)
1.789(3)
1.789(4),
1.735(5)
–
–
Angles (˚)
Au←C→Au
91.3(2)
88.53(15)
88.55(13)
–
–
177.48(17),
175.54(16)
175.43(12),
174.80(13)
175.30(9),
172.38(10)
C→Au←P
175.76(13)
104.4(4)
175.02(10)
106.83(17)
S→C←S
115.4(3)
112.5(2)
106.72(18)
The molecular structures of 3–9 were determined by single
crystal X-ray diffraction analysis, unambiguously confirming the
1 coordination of 1, E, and F to the AuI center (Scheme 4). To
the best of our knowledge, complexes 5–9 are the first examples
of diaurated and proton-aurated complexes of two- sulfur-
stabilized carbones. Table 3 lists selected bond lengths and
angles of 5–9. The C→Au distances for 5 (2.115 Å and 2.084 Å)
and 8 (8: 2.091 Å) are similar to those for the diaurated (6: 2.126
Å and 2.125 Å; 7: 2.130 Å and 2.103 Å) and proton-aurated
complexes (9: 2.098 Å). The Au–Au distance for 5 (3.002 Å) is
slightly longer than those in 6 (2.967 Å) and 7 (2.955 Å). These
distances are within the range typically observed for Au–Au
interactions (2.50–3.50 Å).[19] The SII→C distances of 5 (1.782 Å
and 1.767 Å) are almost exactly halfway between those of
1·HTfO and 1·(HTfO)2, whereas the distances for 8 (1.837 Å and
1.805 Å) are similar to that of the single bond distance (1.81
Å).[18] The Au←C→Au bond angle for 5 (91.3°) is wider than
those for 6a (88.5°) and 7 (88.5°). The S→C←S angle of 1
(115.4°) is wider than that for 1·HTfO, whereas the angle for 8
(104.3°) is significantly narrower than that of diprotonated salt
1·(HTfO)2. These results clearly demonstrate the four-electron-
donating abilities of 1, E, and F.
Scheme 4. Syntheses of 2–7 and molecular structures of 5–7. Hydrogen
atoms and TfO anions are omitted for clarity. Reagents and conditions: a)
[AuCl(PPh3)] (1 eq.), THF, −40 °C to 0 °C, 5 h, then NaTfO (1 eq.) 1 h; 2
(91%); 3 (77%); 4 (62%); b) [AuCl(PPh3)] (2 eq.), THF, −40 °C to 0 °C, 5 h,
then AgTfO (2 eq.) 1 h; 5 (91%); 6 (77%); 7 (97%).
In an attempt to extend of the coordination chemistry of two-
sulfur-stabilized carbones, we synthesized silver complexes
bearing 1, E, and F as ligands and applied them as the carbone
transfer reagents. Previously, we have reported the facile
preparation of silver carbone complexes through an in situ
deprotonation/complexation reaction.[13a] Here, by analogues
method, reactions of the hydrochloric salts of 1, E, and F with
Ag2O in dichloromethane (DCM) were performed under air. The
reactions proceeded smoothly at room temperature and affrod
the corresponding silver carbone complexes 10–12 in good
yields (Scheme 6). It is worth noting that the formation of 10
indicates that this synthetic protocol can be applied to the
thermally labile carbone species. In the solid state, silver
complexes 11 and 12 are stable to moisture and no degradation
of the solids is observed over a period of several weeks.
Scheme 5. Syntheses and molecular structures of 8 and 9. Hydrogen atoms
(except for that on Ccarbone), BF4, and SbF6 anions are omitted for clarity.
Reagents and conditions: a) [AuCl(PPh3)] (1 eq.) and AgX (X = BF4 or SbF6, 1
eq.), DCM, r.t., 1 h; 8 (50%); 9 (45%).
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Conversely, complex 10 is gradually decomposes in the solid
state at room temperature. The use of 10–12 as carbone
transfer agents was investigated by the formation of diaurated
complexes. In line with our expectations, the reactions of silver
complexes 10–12 with two equivalents of [AuCl(PPh3)]/AgTfO in
DCM under air give the corresponding diaurated complexes 5–7
(Scheme 6). These results demonstrate that this synthetic
protocol can be applied to two-sulfur-stabilized carbones.
Finally, we attempted to synthesize a heteronuclear gold(I)-
silver(I) cluster stabilized by carbones. Recently, we revealed
that the introduction of appropriate -donor substituents on the
ligands of the carbones enables the formation of multimetallic
cluster complexes bearing carbones as novel chelating
ligands.[14c] Inspired by this work, the reaction of diaurated
complex 6b with silver(I) should lead to the formation of a
heteronuclear complex, because the two-nitrogen-donor of
ligand E may form a bidentate pincer-type complex (Scheme 7).
Treatment of 6b with AgTfO in DCM at room temperature gives
the desired complex 13 in 21% yield.
The molecular structures of silver complexes 10–12 were
revealed by X-ray diffraction analysis. The selected bond lengths
and angles of 10–12 are listed in Table 4. Interestingly,
complexes 10 and 11 form neutral carbone silver halide
complexes, whereas 12 forms a cationic bis-carbone complex.
The C→Ag bond distance for 10 (2.059 Å) is significantly shorter
than those for 11 (2.134 Å) and 12 (2.111 Å and 2.098 Å). The
mean values of the SII→C distances in 10 (1.703 Å) and 12
(1.718 Å) are slightly longer than the mean values of the SIV→C
distances in 11 (1.689 Å) and 12 (1.664 Å). The C→Ag←Cl
angles (10: 172.8°; 12: 177.7°) and C→Ag←C angle (176.3°)
are nearly linear. The S→C←S angle for 10 (107.3°) is smaller
than that for 1 upon complexation, whereas the angle for 11
(112.1°) and 12 (avg. 106.6°) are larger than those of E and F.
Crystals suitable for X-ray analysis were obtained by slow
evaporation from the reaction mixtures. Surprisingly, complex 13
is a hexanuclear complex in which two independent Au-Au-Ag
clusters are held together by two E ligands. To the best of our
knowledge, complex 13 is the first example of
a
heterohexametallic cluster supported by two carbone ligands
that adopt a 4C,C’,N,N’ coordination. Both of nitrogen atoms
clearly bond to the silver atom at a mean distance of 2.402 Å.
These values are similar to those of silver morpholine (2.39 Å) or
azido (2.561 Å) complexes,[20] and thus the carbone
E
coordinates in a pincer fashion. The six-membered heterocyclic
Ag-N-S-C-S-N ring forms a distorted boat structure. The bond
distances (C→Au: 2.139 Å and 2.108 Å; S→C: 1.757 Å and
1.747 Å) and angles (Au←C→Au: 87.2°; S→C←S: 116.8°) of
13 around Ccenter are only slightly different from that of the
corresponding complex 6a.
The silver
atoms are
pentacoordinated by a gold atom, two nitrogen atoms, and two
TfO anions with distorted square pyramid geometry. The Au–Ag
distance (3.003 Å) of 13 indicates the presence of metallophilc
interactions.[21] The two TfO anions bridge two silver atoms (Ag–
O1: 2.254 Å; Ag–O2: 2.464 Å) forming an eight-membered
heterocyclic ring.
Scheme 6. Syntheses, transmetallation, and molecular structures of Ag
complex 10–12. Hydrogen atoms and AgCl2 anion are omitted for clarity.
Reagents and conditions (yields): a) Amberlite IRA-410 ion-exchange resin
(Cl– form), MeOH, r.t., then Ag2O (1.0 eq.), DCM, r.t., 24 h; 10 (95%); 11
(99%); 12 (98%); b) [AuCl(PPh3)] (2 eq.), AgTfO (2 eq.), DCM, –20 °C to r.t., 2
h;5 (94%); 6 (97%); 7 (91%).
Table 4. Selected bond lengths (Å) and angles (°) of 10–12.
Lengths(Å)
10
11
12
2.111(7),
2.097(7)
1.719(6),
1.717(7)
1.669(7),
1.659(7)
C→Ag
2.058(8)
2.134(3)
1.707(8),
1.698(8)
SII→C
SIV→C
–
1.690(3),
1.687(3)
–
Angles (˚)
C→Ag←C
C→Ag←Cl
Scheme 7. Synthesis and molecular structure of 13. Hydrogen atoms, phenyl
substituents (except Cipso) and BF4 anions are omitted for clarity. Reagents
and conditions (yield): a) AgTfO, DCM, r.t., 2 h, (21%).
–
–
176.3(3)
172.8(3)
177.67(7)
–
106.6(3),
106.5(4)
S→C←S
107.3(5)
112.16(14)
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10.1002/chem.201700863
Chemistry - A European Journal
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1 h, AgTfO (2.0 eq.) was added. The resulting solution was slowly warm
to r.t. for 1 h. The reaction mixture was filtered then the Celite washed
with DCM. Concentration of the filtrate under reduced pressure afforded
the desired product.
Conclusions
We have successfully prepared the first two-SII-stabilized
carbone 1 by the deprotonation of the corresponding protonated
salt, which was unexpectedly obtained by the deimination
reaction of E·HBF4. The replacement of a SIV with a SII ligand
significantly reduces the n-* interactions between nC and the
SII ligand because of the presence of the lone pair on the S atom.
Comparison of the calculated PAs and energy levels of the
HOMOs, and a structural analysis of diprotonated salt 1·(HTfO)2,
confirm the superior electron-donating ability of 1 over those of E
and F. These results suggest that the presence of a lone pair on
the coordinated atom causes a significantly enhanced electron
density at the carbon center. The carbone characters of 1, E,
and F were demonstrated by the corresponding diaurated- and
proton-aurated complexes 5–9, and this constitutes the first
experimental proof of two-sulfur-stabilized carbones behaving as
four-electron donors. The facile preparation of silver carbone
complexes 10–12 and their application as carbone transfer
regents revealed that our synthetic protocol can be applied to
two-sulfur-stabilized carbones, even for thermally labile species.
By using the donating ability of the N atoms of the iminosulfane
ligands, the first heterohexametallic complex 13 stabilized by
carbones was synthesized. In this complex, carbone E exhibits a
4C,C’,N,N’ pincer-type coordination mode. The easy tunability
and unique coordination behavior of two-sulfur-stabilized
carbones may present a new methodology for the design of
multimetallic carbone complexes. An investigation into the
synthesis and catalytic properties of these species is currently
under way in our laboratory.
General Procedure for the syntheses of proton-aurated complexes
(GP3): The reaction was carried out under air. To a mixture of
carbone·HX (X = BF4 or SbF6), Ph3PAuCl (1.0 eq.), and AgX (X = BF4 or
SbF6, 1.0 eq.) was added DCM (5 mL) at r.t.. After stirring for 1 h, the
reaction mixture was filtered then the Celite washed with DCM.
Concentration of the filtrate under reduced pressure afforded the desired
product.
General Procedure for the syntheses of carbone-AgCl complexes
(GP4): The reaction was carried out under air. The MeOH solution of
carbone·HX (X = TfO or BF4) was passed through a column of Amberlite
IRA-410 ion-exchange resin (Cl- form). After removal of all the volatiles
under vacuum, the residue redissolved in DCM and Ag2O (1.0 eq.) was
added. After stirring for 24 h in the dark, the reaction mixture was filtered
through Celite. The clear filtrate was evaporated to give desired silver
complex.
[Ph2CH2I]TfO: To a MeCN (2.0 mL) solution of Ph2S (240 L, 1.4 mmol)
and diiodomethane (145 L, 1.4 mmol) was added AgTfO (770 mg, 3.0
mmol) and refluxed 24 h in the dark. The reaction mixture was filtered
through Celite with MeCN. Concentration of filtrate under reduced
pressure and washed with Et2O afforded the [Ph2CH2I]TfO (416 mg,
89%) as gray powder. The solid product of [Ph2CH2I]TfO suitable for X-
ray analysis was recrystallized in DCM/Et2O to yield colorless crystals;
1
m.p. 154-156 °C; H NMR (500 MHz, CDCl3) δ 5.63 (s, 2H), 7.72 (t, J =
7.7 Hz, 4H), 7.78 (t, J = 7.7 Hz, 2H), 8.04 (d, J = 7.7 Hz, 4H) ppm;
13C{1H} NMR (125 MHz, CDCl3) δ 1.58, 120.7 (q, JCF = 319 Hz, CF3),
124.9, 130.7, 131.7, 135.3 ppm; 19F{1H} NMR (470 MHz, CDCl3) δ -79.1
ppm. Elemental analysis: Calcd. (%) for C14H12F3O3S2I: C, 35.31; H,
2.54; N, 0.00; Found C, 35.10; H, 2.38; N, 0.00.
Experimental Section
1·(HTfO)2 (BSC·(HTfO)2): The reaction was carried out under air.
Trifluoromethanesulfonic acid (TfOH: 2.40 mL, 27.3 mmol) was added to
iSSC•HBF4 (1.20 g, 2.39 mmol) at -40 °C and the resulting reaction
mixture was stirred and allowed to slowly warm to r.t. for 3 h. The
resulting mixture was recooled to -40 °C and water (2 mL) was added.
The water phase was extracted with DCM/MeOH (9:1; 5 mL × 5). The
organic phase was dried (MgSO4) and filtered. Solvent removal and
washed with THF afforded the desired product (920 mg, 56%) as white
solid. The solid product of BSC·(HTfO)2 suitable for X-ray analysis was
recrystallized in acetone/Et2O to yield colorless crystals; BSC•(HTfO)2: m.
p. 204-205 °C; 1H NMR (500 MHz, CD3CN) δ 6.60 (s, 2H), 7.65 (t, J = 7.4
Hz, 8H), 7.80 (t, J = 7.4 Hz, 4H), 7.98-8.01 (m, 8H) ppm; 1H NMR (500
MHz, CDCl3) δ 6.87 (s, 2H), 7.60 (t, J = 7.8 Hz, 8H), 7.70 (t, J = 7.8 Hz,
General considerations
Unless otherwise specified, reactions were carried out under an
atmosphere of dry argon. Reagents were purchased reagent grade from
commercial suppliers and used without further purification. 1H, 13C{1H},
19F{1H}, and 31P{1H} NMR spectroscopies were recorded on a Bruker
Avance 500 MHz spectrometer. 1H and 13C{1H} NMR chemical shifts ()
in CDCl3 are given in ppm relative to Si(CH3)4, coupling constants (J) in
Hz. 1H and 13C{1H} NMR chemical shifts (δ) in C6D6, THF-d8, and CD2Cl2
are calibrated to the residual proton resonance of the solvent (C6D6: δH =
7.16, δC = 128.06; THF-d8: δH = 3.58, δC = 67.21; CD2Cl2: δH = 5.32,
δC = 53.84). Chemical shifts for 19F{1H} and 31P{1H} NMR spectroscopy
were referenced to an external standard (C6H5CF3; F = -63.7, 85%
H3PO4; 0.0). Melting points (m.p.) were determined with Yanaco MP-03
instrument. BiSC (E)[14a] and iSSC (F)[14b] were prepared according to the
literature.
1
4H), 8.20 (d, J = 7.8 Hz, 8H) ppm; H NMR (500 MHz, C6D6) δ 6.44 (s,
2H) 6.65 (t, J = 7.8 Hz, 4H), 6.79 (t, J = 7.8 Hz, 8H), 8.03 (d, J = 7.8 Hz,
8H) ppm; 13C{1H} NMR (125 MHz, CD3CN) δ 55.3, 122.0 (q, JCF = 321 Hz,
CF3), 123.0, 132.4, 132.8, 137.1 ppm; 13C{1H} NMR (125 MHz, CDCl3) δ
55.2, 122.6, 120.5 (q, JCF = 321 Hz, CF3) 131.7, 132.0, 136.1 ppm;
19F{1H} NMR (470 MHz, CD3CN) δ -80.2 ppm; 19F{1H} NMR (470 MHz,
CDCl3)
δ
-79.2 ppm. Elemental analysis: Calcd. (%) for
Synthesis and characterization of compounds
C27H22F6O6S6·0.5H2O: C, 46.75; H, 3.34; N, 0.00; Found C, 46.92; H,
3.19; N, 0.00.
General Procedure for the syntheses of mono- and di-aurated
complexes (GP1): To a mixture of carbones and Ph3PAuCl (1.0 or 2.0
eq.) was added THF (2 mL) at -40 °C. After stirring for 5 h at 0 °C, NaTfO
(1.0 eq.) or AgX (X = TfO or BF4, 2.0 eq.) was added. The resulting
solution was stirred 1 h. The reaction mixture was filtered then the Celite
washed with DCM. Concentration of the filtrate under reduced pressure
afforded the desired product.
1·HTfO (BSC•HTfO): The reaction was carried out under air. To a MeCN
(5 mL) solution of BSC•2HTfO (287.5 mg, 0.42 mmol) was added K2CO3
(70.0 mg, 0.51 mmol) at r.t.. After stirring for 2 h, water (5 mL) was added.
The water phase was extracted with DCM. The organic phase was dried
(MgSO4) and filtered. Solvent removal and washed with Et2O afforded
the desired product (180 mg, 80%) as white solid. The solid product of
BSC·HTfO suitable for X-ray analysis was recrystallized in DCM/Et2O to
yield colorless crystals; BSC•HTfO : m. p. 142-145 °C; 1H NMR (500
MHz, CD3CN) δ 3.88 (s, 1H), 7.56-7.59 (m, 8H), 7.60-7.64 (m, 12H) ppm;
General Procedure for the carbone transfer reaction (GP2): The
reaction was carried out under air. To a mixture of [Ag(carbone)Cl] and
Ph3PAuCl (2.0 equiv.) was added DCM (5 mL) at -20 °C. After stirring for
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10.1002/chem.201700863
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1H NMR (500 MHz, CDCl3) δ 4.34 (s, 1H), 7.49-7.53 (m, 12H), 7.65-7.66
(m, 8H) ppm; 1H NMR (500 MHz, C6D6) δ 5.61 (s, 1H), 6.77 (t, J = 7.6 Hz,
4H), 6.93 (t, J = 7.6 Hz, 8H), 7.65 (d, J = 7.6 Hz, 8H) ppm; 1H NMR (500
MHz, THF-d8) δ 4.92 (s, 1H), 7.41-7.47 (m, 12H), 7.92 (d, J = 6.5 Hz, 8H)
ppm; 13C{1H} NMR (125 MHz, CD3CN) δ 19.4, 122.2 (q, JCF = 321 Hz,
CF3), 128.7, 131.4, 133.2, 137.0 ppm; 13C{1H} NMR (125 MHz, CDCl3) δ
18.1, 120.1 (q, JCF = 321 Hz, CF3), 127.7, 130.6, 132.2, 135.9 ppm;
13C{1H} NMR (125 MHz, THF-d8) δ 15.4, 122.7 (q, JCF = 321 Hz, CF3),
128.6, 131.1, 132.5, 138.5 ppm; 19F{1H} NMR (470 MHz, CD3CN) δ -80.2
ppm; 19F{1H} NMR (470 MHz, CDCl3) δ -79.0 ppm; 19F{1H} NMR (470
MHz, C6D6) δ -78.5 ppm; 19F{1H} NMR (470 MHz, THF-d8) δ -79.8 ppm.
Elemental analysis: Calcd. (%) for C26H21F3O3S3: C, 58.41; H, 3.96; N,
0.00; Found C, 58.01; H, 3.89; N, 0.00.
mg, 91%). The solid product of [Au2(BSC)(PPh3)2](TfO)2 suitable for X-
ray analysis was recrystallized in DCM/Et2O to yield colorless crystals;
GP2: [Ag(BSC)Cl] (13.2 mg, 25 mol), Ph3PAuCl (24.7 mg, 50 mol),
and AgTfO (12.8 mg, 50 mol) were employed (38 mg, 94%);
[Au2(BSC)(PPh3)2](TfO)2: m.p. 119-121 °C; 1H NMR (500 MHz, CD3CN)
δ 7.24 (q, JPH = 6.8 Hz, 12H), 7.39-7.43 (m, 20H), 7.56-7.61 (m, 10H),
8.00 (d, J = 7.5 Hz, 8H) ppm; 13C{1H} NMR (125 MHz, CD3CN) δ 122.2 (q,
JCF = 321 Hz, CF3), 128.6, 128.9 (d, JPC = 58.8 Hz), 130.6 (d, JPC = 12.6
Hz), 131.0, 132.1, 132.8, 133.5, 134.8 (d, JPC = 12.6 Hz), 134.9 ppm, the
signal of central carbon was not observed; 19F{1H} NMR (470 MHz,
CD3CN) δ -80.3 ppm; 31P{1H} NMR (202 MHz, CD3CN) δ 36.4 ppm;
Elemental analysis: Calcd. (%) for C63H48Au2F6O6P2S4·0.5CH2Cl2: C,
46.40; H, 3.13; N, 0.00; Found C, 46.08; H, 3.20; N, 0.00.
1 (BSC): Method A : BSC•HTfO (53.5 mg, 0.10 mmol) was placed in a
flask and dissolved in THF-d8. To the resulting solution potassium
hexamethyldisilazide (KHMDS: 22.1 mg, 0.11 mmol) was added at -
80 °C. The product was characterized at -30 °C without any purification;
Method B : To a mixture of BSC•HTfO (26.7 mg, 0.05 mmol) and NaNH2
(19.5 mg, 0.5 mmol) was added THF (10 mL) at -80 °C. The resulting
mixture was stirred 1 h at -30 °C. The reaction mixture was filtered below
-30 °C and evaporation afforded the desired product (18.6 mg, 97%).
BSC : 1H NMR (500 MHz, THF-d8, -20 °C) δ 7.27 (t, J = 7.8 Hz, 4H), 7.33
(t, J = 7.8 Hz, 8H), 7.91 (d, J = 7.8 Hz, 8H) ppm; 13C{1H} NMR (125 MHz,
THF-d8, -20 °C) δ 41.8, 126.9, 129.0, 129.2, 148.4 ppm. Due to air,
moisture, and thermal sensitivity elemental analysis cannot be used to
confirm the composition of 1.
6a ([Au2(BiSC)(Ph3P)2](TfO)2): GP1: The reaction was carried out under
air. BiSC (44.7 mg, 0.10 mmol), Ph3PAuCl (98.8 mg, 0.20 mmol), and
AgTfO (49.8 mg, 0.20 mmol) were employed (173 mg, 96%). The solid
product of [Au2(BiSC)(Ph3P)2](TfO)2 suitable for X-ray analysis was
recrystallized in acetonitrile/diethylether to yield colorless crystals; GP2:
[Ag(BiSC)Cl] (14.6 mg, 25 mol), Ph3PAuCl (24.7 mg, 50 mol), and
AgTfO (12.8 mg, 50 mol) were employed (43 mg, 97%); m.p. 109-
110 °C; 1H NMR (500 MHz, CDCl3) δ 2.76 (brs, 6H), 6.93 (dd, J = 7.5 Hz,
12H), 7.31-7.35 (m, 12H), 7.52-7.55 (m, 14H), 7.69 (br, 4H), 8.25 (d, J =
7.5 Hz, 8H) ppm; 13C{1H} NMR (125 MHz, CDCl3) δ 34.3, 121.1 (q, JCF
=
321 Hz, CF3), 126.9 (d, JPC = 60.1 Hz), 129.2, 129.8, (d, JPC = 11.9 Hz),
130.4, 132.8, 133.4 (d, JPC = 13.6 Hz), 135.2, 138.2 ppm, the signal of
central carbon was not observed.; 19F NMR (470 MHz, CDCl3) δ -78.9
ppm; 31P NMR (202 MHz, CDCl3) δ 34.3 ppm; Elemental analysis: Calcd.
(%) for C65H56Au2F6N2O6P2S4·H2O: C, 46.54; H, 3.49; N, 1.67; Found C,
46.59; H, 3.17; N, 1.72.
2 ([Au(BSC)(Ph3P)]TfO): GP1: BSC (38.4 mg, 0.10 m mol), Ph3PAuCl
(49.5 mg, 0.10 mmol), and NaTfO (17.2 mg, 0.10 mmol) were employed
(103 mg, 91%); m.p. 133-135 °C; 1H NMR (500 MHz, CD3CN) δ 7.24-
7.28 (m, 6H), 7.43-7.49 (m, 13H), 7.54-7.58 (m, 8H), 7.74 (d, J = 7.5 Hz,
8H) ppm; 13C NMR (126 MHz, CDCl3) δ 65.4 (d, J = 133.8 Hz), 121.7 (q,
JCF = 321 Hz, CF3), 128.6, 129.3 (d, J = 85.0 Hz), 130.1 (d, J = 11.3 Hz),
130.7, 132.2, 132.7 134.6 (d, J = 13.8 Hz), 141.5 ppm; 19F{1H} NMR (470
MHz, CD3CN) δ -80.3 ppm; 31P{1H} NMR (202 MHz, CD3CN) δ 42.0 ppm.
Elemental analysis: Calcd. (%) for C44H35AuF3O3PS3·CH2Cl2: C, 50.15; H,
3.46; N, 0.00; Found C, 50.41; H, 3.34; N, 0.00.
7
([Au2(iSSC)(Ph3P)2](TfO)2): GP1: iSSC (41.4 mg, 0.10 mmol),
Ph3PAuCl (98.8 mg, 0.20 mmol), and AgTfO (49.8 mg, 0.20 mmol) were
employed (172 mg, 97%). The solid product of [Au2(iSSC)(Ph3P)2](TfO)2
suitable for X-ray analysis was recrystallized in DCM/Hexane to yield
colorless crystals; GP2: [Ag(iSSC)2]AgCl2 (11.1 mg, 10 mol), Ph3PAuCl
(19.8 mg, 40 mol), and AgTfO (10.2 mg, 40 mol) were employed (32
mg, 91%); m.p. 124-126 °C (decomp.); 1H NMR (500 MHz, CDCl3) δ 2.66
(s, 3H), 6.92-6.96 (m, 12H), 7.24-7.27 (m, 4H), 7.31-7.34 (m, 12H), 7.44
(t, J = 7.0 Hz, 2H), 7.52-7.55 (m, 6H), 7.66 (t, J = 8.5 Hz, 4H), 7.75 (t, J =
8.0 Hz, 2H), 8.12 (d, J = 8.0 Hz, 4H), 8.19 (d, J = 8.0 Hz, 4H) ppm;
13C{1H} NMR (125 MHz, CDCl3) δ 33.8, 121.1 (q, JCF = 321 Hz, CF3),
127.2 (d, JPC = 59.7 Hz), 128.3, 129.8 (d, JPC = 12.1 Hz), 130.6, 130.8,
130.9, 132.8, 133.4, 133.5, 133.9, 135.7, 136.2 ppm, the signal of central
carbon was not observed.; 19F NMR (470 MHz, CDCl3) δ -79.0 ppm; 31P
NMR (202 MHz, CDCl3) δ 36.0 ppm; Elemental analysis: Calcd. (%) for
C64H53Au2F6NO6P2S4·CH2Cl2: C, 45.52; H, 3.23; N, 0.82; Found C,
45.35; H, 3.03; N, 0.89.
3 ([Au(BiSC)(Ph3P)]TfO): GP1: BiSC (44.7 mg, 0.10 mmol), Ph3PAuCl
(49.4 mg, 0.10 mmol), and NaTfO (17.2 mg, 0.10 mmol) were employed
(85 mg, 77%). The solid product of [Au(BiSC)(Ph3P)]TfO suitable for X-
ray analysis was recrystallized in DCM/Hexane to yield colorless crystals;
m.p. 154-156 °C: 1H NMR (500 MHz, CDCl3) δ 3.06 (s, 6H), 7.06-7.10 (m,
6H), 7.33-7.39 (m, 18H), 7.46-7.49 (m, 3H), 8.15-8.19 (m, 8H) ppm; 13C
NMR (126 MHz, CDCl3) δ 30.5, 65.1 (d, J = 98.2 Hz), 121.3 (q, JCF = 321
Hz, CF3), 128.4, 128.8, 129.2 (d, J = 11.3 Hz), 129.3, 131.7 (d, J = 2.5
Hz), 132.6, 133.7 (d, J = 13.8 Hz), 140.4 ppm; 19F NMR (470 MHz,
CDCl3) δ -79.0 ppm; 31P NMR (202 MHz, CDCl3) δ 39.0 ppm; Elemental
analysis: Calcd. (%) for C46H41AuF3N2O3PS3: C, 52.57; H, 3.93; N, 2.67;
Found C, 52.29; H, 3.87; N, 2.72.
8 ([Au(BSC·H)(Ph3P)](SbF6)2): The reaction was carried out under air.
The MeOH solution of BSC·HTfO (29.4 mg, 55 mol) was passed
through a column of Amberlite IRA-410 ion-exchange resin (OH- form),
then NaSbF6 (14.2 mg, 55 mol) was added and stirred for 1 h. After
removal of all the volatiles under vacuum, the residue redissolved in
DCM and filitered through Celite. The filtrate was concentrated under
reduced pressure, then GP3: Ph3PAuCl (27.2 mg, 55 mol) and AgSbF6
(18.9 mg, 55 mol) were employed (33.8 mg, 50%). The solid product of
[Au(BSC·H)(Ph3P)](SbF6)2 suitable for X-ray analysis was recrystallized
in acetone/Et2O to yield colorless crystals; m.p. 210-211 °C; 1H NMR
(500 MHz, CDCl3) δ 6.91 (d, 2J PH= 5.5 Hz, 1H), 7.01 (q, JPH = 7.0 Hz,
6H), 7.33 (t, J = 7.6 Hz, 4H), 7.40-7.53 (m, 17H), 7.90 (d, J = 7.6 Hz, 4H),
8.21 (d, J = 7.6 Hz, 4H) ppm; 13C{1H} NMR (125 MHz, CDCl3) δ 66.0 (d,
JPH = 82.6 Hz), 127.0, 127.5 (d, JPH = 12.5 Hz), 129.6 (d, JPH = 12.5 Hz),
130.5 (d, JPH = 12.5 Hz), 131.3, 131.4, 131.8, 132.4, 134.0, 134.1, 134.6,
134.7 ppm; 31P{1H} NMR (202 MHz, CDCl3) δ 37.8 ppm. Elemental
analysis: Calcd. (%) for C43H35AuF12PS2Sb2: C, 39.24; H, 2.76; N, 0.00;
Found C, 39.17; H, 2.67; N, 0.00.
4 ([Au(iSSC)(Ph3P)]TfO): GP1: iSSC (82.7 mg, 0.20 mmol), Ph3PAuCl
(98.8 mg, 0.20 mmol), and NaTfO (34.4 mg, 0.20 mmol) were employed
(144 mg, 62%). The solid product of [Au(iSSC)(Ph3P)]TfO suitable for X-
ray analysis was recrystallized in THF/Hexane to yield colorless crystals;
m.p. 83-84 °C: 1H NMR (500 MHz, CDCl3) δ 2.82 (s, 3H), 7.09-7.13 (m,
6H), 7.38-7.41 (m, 6H), 7.45-7.54 (m, 11H), 7.57-7.60 (m, 4H), 7.77-7.79
(m, 4H), 8.16-8.18 (m, 4H) ppm; 13C NMR (126 MHz, CDCl3) δ 30.4, 67.4
(d, J = 116 Hz, SCS), 121.1 (q, JCF = 321 Hz, CF3), 128.1, 128.3, 128.9
(d, J = 56.6 Hz), 129.4 (d, J = 11.4 Hz), 129.7, 130.4, 132.0 (d, J = 2.4
Hz), 132.1, 133.7, 133.8, 137.8, 141.0 ppm; 19F NMR (470 MHz, CDCl3)
δ -78.9 ppm; 31P NMR (202 MHz, CDCl3) δ 40.8 ppm; Elemental
analysis: Calcd. (%) for C45H38AuF3NO3PS3: C, 52.89; H, 3.75; N, 1.37;
Found C, 52.60; H, 3.74; N, 1.19.
5 ([Au2(BSC)(Ph3P)2](TfO)2): GP1: BSC (9.6 mg, 25 mol), Ph3PAuCl
(24.7 mg, 50 mol), and AgTfO (12.8 mg, 50 mol) were employed (36
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9 ([Au(iSSC·H)(Ph3P)](BF4)2): GP3: iSSC·HBF4 (50.2 mg, 0.10 mmol),
Ph3PAuCl (49.4 mg, 0.10 mmol), AgBF4 (19.4 mg, 0.10 mmol) were
employed (58.7 mg, 45%). The solid product of [Au(iSSC·H)(Ph3P)](BF4)2
suitable for X-ray analysis was recrystallized in DCM/Hexane to yield
brown crystals; m.p. 164-166 oC (decomp.); 1H NMR (500 MHz, CDCl3) δ
3.41 (s, 3H), 7.00-7.05 (m, 6H), 7.32-7.37 (br, 6H), 7.40-7.43 (m, 7H),
7.50-7.55 (m, 8H), 7.91 (d, JPH = 6.3 Hz SCHS), 8.10-8.36 (brm, 8H)
ppm; 13C{1H} NMR (125 MHz, CDCl3) δ 31.9, 72.1 (d, J = 78.9 Hz, SCS),
126.9 (d, J = 60.8 Hz), 127.4, 129.6 (d, J = 12.0 Hz), 130.9, 131.3, 132.4
(d, J = 2.5 Hz), 133.7, 133.9, 134.2, 135.2 ppm; 19F NMR (470 MHz,
CDCl3) δ -151.3 ppm; 31P{1H} NMR (202 MHz, CDCl3) δ 38.1 ppm;
Elemental analysis: Calcd. (%) for C44H39AuB2F8NPS2·CH2Cl2: C, 47.73;
H, 3.65; N, 1.24; Found C, 47.72; H, 3.43; N, 1.32.
Promoted Research Grant (22000009) and
fellowship from the Japan Society for the Promotion of Science
for Young Scientists (No. 15J05047).
a
research
Keywords: carbones • density functional calculations • donor–
acceptor systems • electronic structure • gold
[1]
a) R. Tonner, F. Öxler, B. Neumüller, W. Petz, G. Frenking, Angew.
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10 ([Ag(BSC)Cl]): GP4: BSC·HTfO (107 mg, 0.20 mmol) and Ag2O (46.3
mg 0.20 mmol) were employed (103 mg, 98%); m.p. 128-130 °C: H
1
NMR (500 MHz, CDCl3) δ 7.41-7.47 (m, 12H), 7.56-7.58 (m, 8H); 13C{1H}
NMR (125 MHz, CDCl3) δ 127.5, 129.7, 130.8, 142.1 ppm, the signal of
central carbon was not observed; Elemental analysis: Calcd. (%) for
C25H20AgClS2: C, 56.88; H, 3.82; N, 0.00; Found C, 57.10; H, 3.83; N,
0.00.
11 ([Ag(BiSC)Cl]): GP4: BiSC·HTfO (186 mg, 0.37 mmol) and Ag2O
(85.8 mg 0.37 mmol) were employed (111 mg, 95%). The solid product of
[Ag(BiSC)Cl] suitable for X-ray analysis was recrystallized in
1
DCM/Hexane to yield colorless crystals; m.p. 131-132 °C; H NMR (500
MHz, CDCl3) δ 2.88 (s, 6H), 7.35 (t, J = 7.5 Hz, 8H), 7.42 (t, J = 7.5 Hz,
4H), 7.96 (d, J = 7.5 Hz, 8H) ppm; 13C NMR (125 MHz, CDCl3) δ 30.3,
127.7, 129.0, 132.2, 142.0 ppm, the signal of central carbon was not
observed; Elemental analysis: Calcd. (%) for C27H26AgClN2S2: C, 55.34;
H, 4.47; N, 4.78; Found C, 55.32; H, 4.38; N, 4.67.
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12 ([Ag(iSSC)2]AgCl2): GP4: iSSC·HTfO (106 mg, 0.37 mmol) and Ag2O
(85.8 mg 0.37 mmol) were employed (204 mg, 99%). The solid product of
[Ag(iSSC)2]AgCl2 suitable for X-ray analysis was recrystallized in
THF/Hexane to yield colorless crystals; m.p. 82-83 °C; 1H NMR (500
MHz, CDCl3) δ 2.73 (s, 6H), 7.43-7.51 (m, 24H), 7.71 (d, J = 6.5 Hz, 8H),
8.04 (d, J = 7.5 Hz, 8H) ppm; 13C NMR (125 MHz, CDCl3) δ 30.5, 127.8,
127.9, 129.2, 130.0, 131.4, 132.3, 139.5, 142.7 ppm, the signal of central
carbon was not observed; Elemental analysis: Calcd. (%) for
C52H46Ag2Cl2N2S4·THF: C, 56.71; H, 4.59; N, 2.36; Found C, 56.95; H,
4.31; N, 2.61.
13 ([{Au2Ag(BiSC)(Ph3P)2}{BF4}2TfO]2): To a DCM (5 mL) solution of
[Au2(BiSC)](BF4)2 (6b: 83.7 mg, 50 mol) at -40 °C was added AgTfO
(12.8 mg, 50 mol). The resulting solution was stirred 2 h. The reaction
mixture was filtered then the Celite washed with DCM. Concentration of
the filtrate under reduced pressure afforded the desired product (18.8 mg,
21%). The solid product of [{Au2Ag(BiSC)}{BF4}2TfO]2 suitable for X-ray
analysis was obtained by slow evaporation of reaction mixture as
colorless crystals; m.p. 114-116 oC (decomp.); 1H NMR (500 MHz,
CD2Cl2) δ 2.75 (s, 12H), 6.90-6.92 (br, 24H), 7.24-7.26 (br, 24H), 7.41 (t,
J = 8.0 Hz, 16H), 7.49 (t, J = 7.0 Hz, 12H), 7.62 (t, J = 8.0 Hz, 8H), 8.12
(d, J = 8.0 Hz, 16H) ppm; 13C NMR (125 MHz, CDCl3) δ 35.1, 126.6 (d, J
= 60.9 Hz) 128.4, 129.2, 129.7 (d, J = 11.9 Hz), 130.5, 132.9, 133.5 (d, J
= 13.7 Hz), 135.4 ppm, the signals of central carbon and CF3 anions
[3]
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P
NMR (202 MHz, CD2Cl2) δ 34.1 ppm. Elemental analysis: Calcd. (%) for
C128H112Ag2Au4B4F22N4O6P4S6: C, 42.90; H, 3.15; N, 1.56; Found C,
42.90; H, 2.94; N, 1.77.
Acknowledgements
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This work was partially supported from the Ministry of Education,
Culture, Sports, Science, and Technology of Japan by Grants-in-
Aid for Scientific Research(c) (No. 15K05438) and a Specially
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Entry for the Table of Contents (Please choose one layout)
Layout 1:
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Three sulfur-carbone familiy: The
first bis(sulfane)carbone(0) (BSC) is
accessed by the deprotonation of the
corresponding protonated salt.
Strongest donor ability of BSC
among the two-sulfur-stabilized
carbones makes the diprotonated
salt BSC·H2. Four-electron-donating
ability of two-sulfur-stabilized
carbones is demonstrated by the
structural analysis of aurated
complexes.
Tomohito Morosaki, Ryo Iijima,
Tsubasa, Suzuki, Wei-Wei Wang,
Shigeru Nagase, Takayoshi Fujii*
Page No. – Page No.
Synthesis, Electronic Structure, and
Reactivities of Two-Sulfur Stabilized
Carbones Exhibiting Four-electron
Donor Ability
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