Gold Complexes with ADAP Ligands: Effect of Bulkiness in Catalytic Carbene Transfer Reactions (ADAP = Alkoxydiaminophosphine)

Article abstract of DOI:10.1021/acs.organomet.0c00343

A family of gold(I) complexes of composition AuCl(ADAP) (ADAP = alkoxydiaminophosphine) has been synthetized through a one-pot simple protocol in which the ADAP ligand is prepared in situ before reaction with the Au(I) source. Structural data demonstrate that these ADAP ligands exert a trans effect superior to those of phosphine or phosphite ligands. Evaluation of the buried volume (percentVBur) indicates a steric hindrance higher than those of several NHC, PR3, and P(OR3) ligands, in the context of AuCl(L) complexes. These complexes promote the catalytic transfer of a carbene group from ethyl diazoacetate to alkenes and alkanes. In the case of styrene, both the Csp2-H bonds and the Ca? C bond are functionalized, the relative ratio depending on the catalyst employed and correlating well with the percentVBur value. Data available allow proposing that these compounds display quite similar electronic properties but differ in steric properties, a variable that can be readily controlled upon modifying the alkoxy group at the ADAP ligand by simply replacing the starting alcohol employed in the synthesis.

Full text of DOI:10.1021/acs.organomet.0c00343

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Gold Complexes with ADAP Ligands: Effect of Bulkiness in Catalytic
Carbene Transfer Reactions (ADAP = Alkoxydiaminophosphine)
́
Juan Diego Pizarro, Francisco Molina, Manuel R. Fructos,* and Pedro J. Perez*
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ABSTRACT: A family of gold(I) complexes of composition
AuCl(ADAP) (ADAP = alkoxydiaminophosphine) has been
synthetized through a one-pot simple protocol in which the
ADAP ligand is prepared in situ before reaction with the Au(I)
source. Structural data demonstrate that these ADAP ligands exert
a trans effect superior to those of phosphine or phosphite ligands.
Evaluation of the buried volume (%VBur) indicates a steric
hindrance higher than those of several NHC, PR3, and P(OR3)
ligands, in the context of AuCl(L) complexes. These complexes
promote the catalytic transfer of a carbene group from ethyl
diazoacetate to alkenes and alkanes. In the case of styrene, both the
2
Csp −H bonds and the CC bond are functionalized, the relative
ratio depending on the catalyst employed and correlating well with
the %VBur value. Data available allow proposing that these compounds display quite similar electronic properties but differ in steric
properties, a variable that can be readily controlled upon modifying the alkoxy group at the ADAP ligand by simply replacing the
starting alcohol employed in the synthesis.
Scheme 1. Gold(I)-Catalyzed Carbene Transfer Reactions,
Now Incorporating ADAP Ligands
INTRODUCTION
■
After centuries as a dormant metal in terms of chemical
reactivity, gold has emerged as one of the most promiscuous
elements in the last few decades, with particular emphasis in
homogeneous catalysis.1 In its +1 oxidation state, gold
complexes are dicoordinated, showing a linear geometry
along the L−Au−L′ axis.2 In the context of catalytic uses,
the strategy of employing an L ancillary ligand to exert
electronic and/or steric control onto the Au(I) center has been
extensively employed with either P-donor (phosphine,
phosphite) or N-heterocyclic carbene (NHC) ligands,1,3 the
catalytic reaction taking place at the opposite coordination
position. In a joint collaboration with Nolan, our group
discovered4 the potential of gold as a catalyst for the carbene
transfer reaction from a diazo compound to saturated or
unsaturated fragments.5 Since then, we and others have
employed complexes of the type AuXL (L = PR3, NHC; X =
halide) as catalyst precursors for such transformations with
notable success (Scheme 1).6 However, the modification of the
composition of those P- or C-donor ligands usually requires
considerable synthetic effort, and thus the tuning of the steric
and electronic properties at the gold center is not
straightforward.
Received: May 15, 2020
With the idea of expanding the availability of Au(I) catalysts,
we have moved to a new family of ligands, alkoxydiamino-
phosphines (ADAP), which contain a five-membered cycle
with two N atoms directly bonded to the P donor, resembling
the skeleton of an NHC ligand. The third substituent at P
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consists of an alkoxy group, which is readily installed from any
alcohol and provides a certain phosphite-like behavior to the
ADAP ligand. We have recently described7 a family of copper
complexes bearing these ligands and showed that their catalytic
activity toward several transformations (carbene transfer,
CuAAC, nitrene transfer) is similar to that of their NHC
analogues. Herein we describe a protocol for the direct
syntheses of a new family of gold complexes of the formula
AuCl(ADAP), where the ligand is prepared in situ before the
gold(I) source is added. Their structural characterization
provides relevant data regarding a trans effect higher than that
of other NHC or P-donor ligands as well as a noticeable steric
effect. These complexes catalyze the functionalization of
alkenes and alkanes. Interesting correlations between structural
data and the catalytic properties have also been found (Scheme
1).
RESULTS AND DISCUSSION
■
Synthesis and Characterization of the AuCl(ADAP)
Complexes. Following our recent protocol for related copper
complexes,7 we have prepared a series of six gold complexes
bearing alkoxydiaminophosphine (ADAP) ligands. The bromo
derivative 1 (1,3-bis[2,6-bis(1-methylethyl)phenyl]-2-bromo-
2,3-dihydro-1H-1,3,2-diazaphospholene; Scheme 2) was re-
Scheme 2. One-Pot Synthesis of ADAP Ligands 2a−f and
Their Corresponding Au(I) Derivatives 3a−f
acted with the desired ROH in toluene with added NEt3,
generating ADAP ligands 2a−f before AuCl(THT) (THT =
tetrahydrothiophene) was incorporated in the reaction
mixture. After workup, complexes of the composition AuCl-
(ADAP) (3a−f; Scheme 2) were isolated in 75−95% yields,
based on initial 1, all but 3e providing crystalline materials
suitable for X-ray characterization. The isolation of most
ADAP ligands is elusive7 due to fast hydrolysis. This procedure
generates clean solutions of 2a−f as inferred from 31P{1H}
NMR studies, which are subsequently treated with AuCl-
(THT). The ligation of ADAP to gold can be monitored by
that technique, showing the smooth disappearance of the
resonances of ligands 2 and the appearance of those of
complexes 3.
Spectroscopic and analytical data for complexes 3a−f agreed
with the formulation AuCl(ADAP) (see the Experimental
Section). Since the already described copper7 analogues
showed a dinuclear structure in the solid state in some cases,
supported by two bridging Cl ligands, we have determined the
solid-state structure8 of the new gold complexes 3a−d,f to
ascertain the molecularity of the new complexes. Figure 1
displays such structures, which show their mononuclear nature,
Figure 1. Molecular structures of complexes 3a−d,f. Hydrogen atoms
have been omitted for clarity.
as well as the typical linear coordination of the two ligands
around the gold center. The relevant Au−P1 and Au−Cl
distances, as well as the P−Au−Cl angles, are given in Table 1.
Despite the differences in the R group of the alkoxy fragment,
the three magnitudes are found within a narrow range of
values. Thus, both P−Au and Au−Cl distances seem
Table 1. Main Distances (Å) and Angles (deg) for
Complexes 3a−d,f
complex
d(Au−P)
d(Au−Cl)
P−Au−Cl angle
3a
3b
3c
3d
3f
2.2114(6)
2.2062(8)
2.2083(15)
2.2136(13)
2.2070(8)
2.2853(8)
2.2846(8)
2.2700(16)
2.2834(13)
2.3007(9)
176.23(3)
175.49(3)
177.68(6)
177.34(5)
177.56(4)
B
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unaffected by the R group, despite being as distinct as ethyl or
binaphthyl.
Table 2 displays the values for the Au−L and Au−Cl
distances and the L−Au−Cl angles for representative AuCl(L)
Table 2. Comparison of Relevant Structural Data for Several
AuCl(L) Complexes (L = ADAP, NHC, PR3, P(OR3))
complex
d(Au−L)
d(Au−Cl)
L−Au−Cl angle
a
AuCl(ADAP)
AuCl(IPr)
AuCl(PCy3)
AuCl(PPh3)
2.209
1.942
2.242
2.235
2.284
2.269
2.279
2.279
2.260
176.86
177.0
177.0
179.63
176.52
b
AuCl[(ArO)3P]
2.198
a
b
Average of values in Table 1. Ar = 2-isopropyl-5-methylphenyl.
complexes bearing ADAP, NHC, phosphine, and phosphite
ligands. The main difference is provided by the IPr-containing
complex,9 with a significantly shorter L−Au distance, explained
as the result of the nearly nonexistent π-back-bonding
contribution, at variance with the ligands containing P donors.
The average P−Au distance in AuCl(ADAP) complexes is
2.209 Å, slightly shorter than those of the phosphine (PCy3,
PPh3)10 derivatives and similar to that of the phosphite
(P(OAr)3) analogue.11 The Au−Cl distance (average) for
ADAP complexes is longer than those for any of the other
complexes, a feature which supports the proposal that these
ADAP ligands induce a trans effect higher than that of IPr,
PCy3, PPh3, or (P(OAr)3).
Estimation of the Steric Hindrance of ADAP Ligands:
Calculation of %VBur. The structural characterization of five
AuCl(ADAP) complexes has allowed the estimation of the
buried volumes (%VBur) for the ADAP ligands 2a−d,f.12 The
topographic steric maps are shown in Figure 2. The buried
volume values range from 45.1 for the ethyl-containing 3a to
50.0 for the bulkier binaphthyl derivative 3f. The trend follows
the increase in the volume of the R group attached to the O
atom in the alkoxy group, the remaining five-membered ring
very likely providing the same steric hindrance along the series.
In the previous section structural data have served to propose
that these ADAP ligands induce a trans effect higher than that
of other NHC or P-donor ligands. With the %VBur values, we
can now evaluate their steric pressure as related to other
AuCl(L) complexes. Figure 2 contains the reported values for
several L ligands in such those complexes.13 Those bearing
PPh3, PCy3, PtBu3, P(o-Tol)3, and IPr ligands display %VBur
values lower than those calculated for the ADAP ligands
reported herein. Only the very bulky PMes3 (Mes = 2,4,6-
trimethylphenyl) shows a buried volume (50.5) higher than
that of any of the ADAP ligands 2, albeit it is very close to that
of the binaphthyl derivative 2f (50.0).
Figure 2. (top) Topographic maps and buried volumes for ADAP
ligands in complexes 3a−d,f. (bottom) Comparison of %VBur values
for several L ligands in complexes AuCl(L).
Catalytic Activity of Complexes 3a−f in Carbene
Transfer Reactions to Hydrocarbons. Previous work from
our laboratory demonstrated the potential of some (NHC)-
AuCl complexes for the catalytic transfer of the CHCO2Et
group from ethyl diazoacetate (N2CHCO2Et, EDA) to
arenes, olefins, or alkanes, among others.4,6,14 In order to check
the capabilities of the AuCl(ADAP) complexes toward that
end, we first carried out a series of experiments using 1-octene,
4-trans-octene, and n-hexane, with ethyl diazoacetate as the
carbene source. Scheme 3 displays the results of this screening
performed with complex 3a and a halide scavenger, as a
representative catalyst. Terminal and internal octenes gave the
corresponding cyclopropanes, as the result of the catalytic
transfer of the CHCO2Et unit from EDA via gold-carbene
intermediates.15 For the terminal olefin, a 60:40 ratio of the cis
and trans diastereomers was found (yields have not been
optimized), whereas the internal olefin only gave the
corresponding trans cyclopropane, as the result of a stereo-
rententive transfer of the carbene unit. This is in agreement
with the well-known concerted nature of such a process.5
n-Hexane has also been tested as a substrate, aiming at the
3
more challenging Csp −H bond functionalization by carbene
insertion.16 Albeit in low yield (30% based in initial EDA),
C
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isomers: cis and trans), with an overall yield of 90% (EDA-
based). Table 3 shows the outcome with the other five
Scheme 3. Alkene and Alkane Functionalization by Carbene
Insertion from Ethyl Diazoacetate Catalyzed by 3a
Table 3. Catalytic Functionalization of Styrene with Ethyl
Diazoacetate Using 3a−f + AgSbF6 as Catalysts
a
b
complex
C−H func (%) (o:m:p)
cyclopropanes (%) (cis:trans)
3a
3b
3c
3d
3e
3f
46 (48:27:25)
41 (44:24:32)
40 (46:26:28)
30 (30:30:40)
31 (34:29:37)
54 (50:50)
59 (51:49)
60 (52:48)
70 (52:48)
69 (57:43)
73 (62:38)
27 (35:26:39)
a
b
See the Experimental Section. Distribution of products.
AuCl(ADAP) complexes. With regard to the distribution of
products, i.e. C−H functionalization vs olefin cyclopropana-
tion, a variation from 46:54 with 3a to 27:73 with 3f is
observed, parallel to the increase in the steric pressure around
the gold center as inferred from the %VBur values. There is also
a slight variation in the isomer ratio within each type of
product. Thus, the formation of the ortho isomer seems to
decrease in favor of the para isomer in going from 3a to 3f, in
line with the augment in the amount of the cis isomer of the
cyclopropane.
We have plotted the ratio of products for both reactions, i.e.
cyclopropanation and C−H functionalization, relative to the %
VBur values obtained for the gold complexes 3a−d,f (3e could
not be crystallized with enough quality for X-ray studies).
Figure 3 shows such a plot, where a correlation is clearly
products derived from the insertion of the carbene group into
the three different C−H bonds of hexane were obtained
(Scheme 3). The distribution of products favored that derived
from modification at C2, followed by C1 and C3. It is worth
mentioning that, to our knowledge, this is the first example of
the functionalization of alkane C−H bonds with gold catalysts
not containing NHC ligands: P donors have been employed in
Au-mediated carbene transfer, but only aromatic C−H bonds
have been achieved to date.
The use of styrene implies an increase in the number of
possible transformations (Scheme 4). This is a substrate which
Scheme 4. Styrene Functionalization by Incorporation of a
Carbene Group from a Diazo Compound: (Top) Potential
Reaction Sites; (Bottom) Use of Complexes 3 as Catalysts
Figure 3. Correlation between the %VBur values in complexes 3 and
the selectivity cyclopropanation/C−H functionalizations in the
reaction of styrene and EDA catalyzed by 3/AgSbF6.
observed. The increase in the steric pressure of the ADAP
ligands on the gold center favors the cyclopropanation
products instead of the C−H functionalization products.
To explain the above results, we must relay on previous
mechanistic work with AuCl(IPr) precatalysts.15 On that basis,
the reaction of complexes 3, in the presence of halide
scavengers, with ethyl diazoacetate provides an electrophilic
gold-carbene intermediate which reacts with an arene ring,
forming Wheland-like intermediates (Scheme 5) as the first
step toward the C−H functionalization product. This seems
reasonable, assuming that the approach of the styrene substrate
with the C−H bonds oriented toward the carbene carbon atom
is less favored than that of the styrene olefinic bond when the
may undergo the incorporation of the carbene unit into the
olefinic CC bond, leading to cyclopropanes. However, the
aromatic ring is not exempted from participating and may
incorporate the carbene into a CC bond (Buchner reaction)
or into a C−H bond. In previous work from our laboratory we
found that with an (NHC)Au-based catalyst mixtures of
products derived from cyclopropanation and C−H function-
alization were obtained, the Buchner reaction being
deactivated.4,15 With 3a/AgSbF6 as the catalyst, we observed
a similar behavior: 46% of the products derived from styrene
corresponded to those derived from C−H modification (three
isomers: ortho, meta, and para) and 54% to cyclopropanes (two
D
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from dichloromethane/hexane mixtures (6/4), after cooling at −30
°C (yields 75−95%, combined crops).
Scheme 5. Two Competitive Pathways for the Interaction of
Styrene with the Gold-Carbene Intermediate
1
Complex 3a: 95% yield (713 mg, 0.95 mmol); H NMR (400
MHz, CDCl3) δ 1.12 (d, 6H, J = 7.2 Hz, CH(CH3)2), 1.21 (d, 6H, J =
7.2 Hz, CH(CH3)2), 1.22 (t, 3H, J = 7.2 Hz, OCH2CH3), 1.28 (d,
6H, J = 7.2 Hz, CH(CH3)2), 1.47 (d, 6H, J = 7.2 Hz, CH(CH3)2),
3.33 (m, 2H, CH(CH3)2), 3.52 (m, 2H, CH(CH3)2), 4.07 (m, 2H,
OCH2CH3), 6.03 (dd, 2H, JH−P = 12.7 Hz, CHN), 7.22 (d, 4H,
CHAr), 7.37 (m, 2H, CHAr); 13C{1H} NMR (100 MHz, CDCl3) δ
16.2 (s, OCH2CH3), 23.3 (s, CH(CH3)2), 23.4 (s, CH(CH3)2), 26.1
(s, CH(CH3)2), 26.3 (s, CH(CH3)2), 27.8 (s, CH(CH3)2), 29.4 (s,
CH(CH3)2), 64.6 (d, JC−P = 6.5 Hz, POCH2CH3), 118.2 (CHN),
124.1, 124.7, 129.5, 129.6, 132.9, 133.1 (CAr); 31P{1H} NMR (162
MHz, CDCl3) δ 104.30 (s). Anal. Calcd for C28H41AuClN2OP: C,
49.09; H, 6.03; N, 4.09. Found: C, 48.99; H, 6.10; N, 4.09.
1
Complex 3b: 86% yield (694 mg, 0.86 mmol); H NMR (400
MHz, CDCl3) δ 0.90 (d, J = 6.7 Hz, 6H, CH(CH3)2), 1.03 (d, J = 6.7
Hz, 6H, CH(CH3)2), 1.09 (d, J = 6.8 Hz, 6H, CH(CH3)2), 1.65 (d, J
= 6.8 Hz, 6H, CH(CH3)2), 3.33 (q, JH−F = 8.3 Hz, 2H, CH2CF3),
3.36 (hept, J = 6.7 Hz, 2H, CH(CH3)2), 3.48 (hept, J = 6.8 Hz, 2H,
CH(CH3)2), 5.64 (d, JH−P = 13.1 Hz, 2H, CHN), 6.89−7.16 (m, 6H,
CHAr); 13C{1H} NMR (100 MHz, CDCl3) δ 22.5 (s, CH(CH3)2),
23.0 (s, 2C, CH(CH3)2), 26.1 (s, 2C, CH(CH3)2), 26.3 (s, 2C,
CH(CH3)2), 27.9 (s, 2C, CH(CH3)2), 29.6 (s, 2C, CH(CH3)2), 63.2
(s, 1C, CH2CF3), 118.6 (d, JC−P = 4.2 Hz, 2C, CHN), 124.2, 124.3,
124.7, 125.3, 128.1, 128.9, 129.9, 130.0, 132.5, 132.6 (CAr), 148.44
(dd, JC−F = 2.7 Hz, 1C, CH2CF3); 31P{1H} NMR (162 MHz, CDCl3)
steric bulk of the ADAP ligand is increased, as it is
experimentally observed. This reasoning also applies to the
increase of the functionalization of the para position and that
of the cis isomer of cyclopropane.
CONCLUSIONS
■
δ 110.0; 19F NMR (400 MHz, CDCl3) δ −73.4 (t, CH2CF3, JH−F
=
The new family of gold(I) complexes AuCl(ADAP) bearing
alkoxydiaminophosphine ligands (ADAP) has been synthe-
sized and characterized, including structural studies, from
which the steric hindrance has been determined using the %
VBur magnitude. These compounds promote the catalytic
transfer of carbene CHCO2Et groups from ethyl diazoacetate
to olefins, alkanes, and styrene. The last substrate undergoes
competitive transformations in which the carbene group is
transferred to the aromatic C−H bond or to the olefinic CC
bond. The relative ratio of these two products depends of the
catalyst employed; a correlation between the %VBur value and
such a ratio has been found. This family of complexes seems to
display similar electronic properties and significantly different
steric properties, imposed by the alkoxy group, thus providing
a valuable tool for the control of such variables in numerous
systems already reported for Au(I) catalysts.
8.3 Hz). Anal. Calcd for C28H38AuClF3N2OP: C, 45.51; H, 5.18; N,
3.79. Found: C, 46.49; H, 5.20; N, 3.66.
Complex 3c: 75% yield (752 mg, 0.75 mmol); H NMR (400
1
MHz, CD2Cl2) δ 1.15 (d, 6H, J = 6.8 Hz, (CH(CH3)2), 1.22 (d, 6H, J
= 6.8 Hz, (CH(CH3)2), 1.31 (d, 6H, J = 6.9 Hz, (CH(CH3)2), 1.47
(d, 6H, J = 6.9 Hz, CH(CH3)2), 2.46 (m, 2H, J = 7.1, JH−F = 10.0 Hz,
CH2CF2), 3.34 (sept, 2H, J = 6.9 Hz, CH(CH3)2), 3.50 (sept, 2H, J =
6.8 Hz, CH(CH3)2), 4.35 (m, 2H, J = 7.1 Hz, OCH2), 6.15 (d, 2H,
JH−P = 12.9 Hz, CHN), 7.26−7.47 (m, 6H, CHAr); 13C{1H} NMR
(100 MHz, CD2Cl2) δ 22.9 (s, 2C, CH(CH3)2), 23.0 (s, 2C,
CH(CH3)2), 25.9 (s, 2C, CH(CH3)2), 26.0 (s, 2C, CH(CH3)2), 27.9
(s, 2C, CH(CH3)2), 29.4 (s, 2C, CH(CH3)2), 32.0 (dq, 1C,
CH2CF2), 59.8 (m, 1C, OCH2), 118.6 (d, JC−P = 4.6 Hz, 2C,
CHN), 124.2, 124.3, 129.6, 129.7, 132.7, 132.8 (CAr), 148.6 (dd, C-
F); 31P{1H} NMR (162 MHz, CD2Cl2) δ 107.06 (s); 19F NMR (400
MHz, CD2Cl2) δ −79.2 (t, 2F, JH−F = 10.0, CH2CF2), −111.8 (t, 2F,
−CF2−), −120.2 (t, 2F, −CF2−), −121.2 (t, 2F, −CF2−), −121.8 (t,
2F, −CF2−), −124.4 (m, 3F, −CF3). Anal. Calcd for
C34H40AuClF13N2OP: C, 40.71; H, 4.02; N, 2.79. Found: C, 40.66;
H, 3.90; N, 2.78.
EXPERIMENTAL SECTION
■
General Methods. The preparations and manipulations of metal
complexes were carried out under a nitrogen atmosphere by using
standard Schlenk techniques or under a nitrogen atmosphere in an
MBraun glovebox. Alcohols were purchased from Aldrich. The 1,3-
bis(2,6-diisopropylphenyl)-2-bromo-2,3-dihydro-1H-1,3,2-diaza-
phosphole ligand was prepared according to literature methods.17
Solvents were distilled and degassed before use. NMR spectra were
Complex 3d: 80% yield (700 mg, 0.8 mmol); 1H NMR (400 MHz,
CDCl3) δ 1.11 (d, 6H, J = 6.5 Hz, CH(CH3)2), 1.19 (d, 6H, J = 6.9
Hz, CH(CH3)2), 1.31 (d, 6H, J = 6,5 Hz, CH(CH3)2), 1.51 (d, 6H, J
= 6.9 Hz, CH(CH3)2), 3.31 (sept, 2H, J = 6.5 Hz, CH(CH3)2), 3.41
(sept, 2H, J = 6.9 Hz, CH(CH3)2), 5.61 (m, 1H, JH−F = 8.8 Hz,
CH(CF3)2, 6.20 (d, 2H, JH−P = 13.2 Hz, CHN), 7.25−7−39 (m, 6H,
CHAr); 13C{1H} NMR (100 MHz, CDCl3) δ 22.6 (s, CH(CH3)2),
23.0 (s, CH(CH3)2), 26.0 (s, CH(CH3)2), 26.2 (s, CH(CH3)2), 28.4
(s, CH(CH3)2), 30.0 (s, CH(CH3)2), 67.9 (s, CH(CF3)2, 120.0 (d,
1
recorded on an Agilent 400 MR or Agilent 500 DD2 instrument. H
and 13C NMR shifts were measured relative to deuterated solvent
peaks but are reported relative to tetramethylsilane. Elemental
analyses were performed on a PerkinElmer Series II CHNS/O
Analyzer 2400. Crystal structure determinations were carried out
using a Bruker D8 FIXED-CHI diffractometer equipped with an
Oxford Cryosystem low-temperature device.
J
P−C = 5.5 Hz, CHN), 124.2, 130.0 (CAr), 124.7, 130.0, 132 (C), 147.8
(d, JC−F = 2.6 Hz, CH(CF3)2), 148.6 (d, JC−F = 2.6 Hz, CH(CF3)2);
31P{1H} NMR (162 MHz, CDCl3) δ 122.85; 19F NMR (400 MHz,
CDCl3) δ −72.5 (dd, JF−H = 5.3 Hz, JF−P = 1.8 Hz). Anal. Calcd for
C29H37AuClF6N2OP: C, 43.16; H, 4.62; N, 3.47. Found: C, 43.09, H,
4.58, N, 3.36.
Synthesis of AuCl(ADAP) Complexes. The in situ generation of
the ADAP ligands7 was carried out by treatment of toluene solutions
of 1 (1 mmol) with the corresponding alcohol and NEt3. After
filtration, a clean solution (by 31P{1H} NMR) of the ADAP ligand
was obtained. The complex AuCl(THT) (THT = tetrahydrothio-
phene) was added (1 mmol) and the mixture stirred for 12 h at room
temperature. Upon filtration, the volatiles were removed at reduced
pressure and the residue was washed with hexane, affording complexes
3a−f as off-white or beige solids. The compounds can be crystallized
1
Complex 3e: 88% yield (691 mg, 0.88 mmol); H NMR (400
MHz, CDCl3) δ 0.39 (d, 3H, J = 6.5 Hz, (CH(CH3)2)ment), 0.46 (d,
3H, J = 6.5 Hz, (CH(CH3)2)ment), 0.55 (m, 1H, (CHCCH3)ment) 0.72
(d, 3H, J = 6.7 Hz, (CH2(CH3)ment), 0.78 (m, 2H, (CH2CH2)ment),
0.90 (m, 1H, CH(CH3)2), 0.91 (m, 2H, (CH2CH2)ment, 1.13 (d, 3H, J
= 6.7 Hz, CH(CH3)2), 1.17 (d, 3H, J = 6.7 Hz, CH(CH3)2), 1.21 (d,
3H, J = 6.7 Hz, CH(CH3)2), 1.23 (d, 3H, J = 6.7 Hz, CH(CH3)2),
E
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Article
1.25 (m, 1H, CH(CH3)ment), 1.29 (d, 3H, J = 6.7 Hz, CH(CH3)2),
1.33 (d, 3H, J = 6.7 Hz, CH(CH3)2), 1.44 (d, 3H, J = 6.8 Hz,
CH(CH3)2), 1.51 (d, 3H, J = 6.8 Hz, CH(CH3)2), 1.91 (m, 2H,
OCHCH2ment), 2.99 (sept, 1H, J = 6.7 Hz, CH(CH3)2), 3.44 (sept,
1H, J = 6.7 Hz, CH(CH3)2), 3.73 (sept, 1H, J = 6.7 Hz, CH(CH3)2),
3.97 (sept, 1H, J = 6.7 Hz, CH(CH3)2), 4.56 (m, 1H, (CH-O)ment),
6.08 (dd, 2H, JH−P = 13.3 Hz, CHN), 7.11−7.15 (m, 6H, CHAr);
13C{1H} NMR (100 MHz, CDCl3) δ 16.2 (s, (CH(CH3)2)ment), 21.4
(s, CH(CH3)2)ment, 21.7 (s, (CH2(CH3)ment), 21.9 (s, CH(CH3)2),
22.4 (s, CH(CH3)2), 22.7 (s, CH(CH3)2), 23.7 (s, CH(CH3)2), 24.1
(s, CH(CH3)2), 24.4 (s, CH(CH3)2), 26.4 (s, CH(CH3)2), 26.6 (s,
CH(CH3)2), 27.9 (s, CH(CH3)2), 28.1 (s, CH(CH3)2), 29.1 (s,
CH(CH3)2), 29.8 (s, CH(CH3)2), 78.8 (d, JC−P = 14.2, CHOP),
117.3 (s, CHN), 120.6 (s, CHN), 123.4, 124.1, 124.4, 128,5, 135.5,
135.7, 146.8, 148.1, 148.3, 148.8, 149.3 (CAr); 31P{1H} NMR (162
MHz, CDCl3) δ 122.81 (s). Attempts to obtain samples with
analytical purity within the 0.4% range failed. The following
corresponds to an average of three different samples. Anal. Calcd for
C36H55AuClN2OP: C, 54.37; H, 6.97; N, 3.52. Found: C, 55.00; H,
7.63; N, 3.87.
Accession Codes
CCDC 2003903−2003906 and 2003923 contain the supple-
mentary crystallographic data for this paper. These data can be
obtained free of charge via www.ccdc.cam.ac.uk/data_request/
cif, or by emailing data_request@ccdc.cam.ac.uk, or by
contacting The Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
AUTHOR INFORMATION
Corresponding Authors
■
́
́
Manuel R. Fructos − Laboratorio de Catalisis Homogenea,
́
Unidad Asociada al CSIC, CIQSO-Centro de Investigacion en
́
́
Quimica Sostenible and Departamento de Quimica,
Universidad de Huelva, 21007 Huelva, Spain;
Email: manuel.romero@dqcm.uhu.es
́
́
́
Pedro J. Perez − Laboratorio de Catalisis Homogenea, Unidad
́
́
Asociada al CSIC, CIQSO-Centro de Investigacion en Quimica
́
Sostenible and Departamento de Quimica, Universidad de
Complex 3f: 90% yield (844 mg, 0.9 mmol); 1H NMR (400 MHz,
C6D6) δ 0.3 (d, 3H, J = 6.4 Hz, CH(CH3)2), 0.61 (d, 3H, J = 6.4 Hz,
CH(CH3)2), 0.87 (d, 3H, J = 6.4 Hz, CH2(CH3)2, 0.91 (d, 3H, J = 6.4
Hz, CH(CH3)2), 1.05 (d, 3H, J = 6.4 Hz, CH(CH3)2), 1.07 (d, 3H, J
= 7.1 Hz, CH(CH3)2), 1.56 (d, 3H, J = 7.1 Hz, CH(CH3)2), 1.68 (d,
3H, J = 7.1 Hz, CH(CH3)2), 3.19 (sept, 1H, J = 6.4 Hz, CH(CH3)2),
3.12 (s, 3H, CH3-Ph), 3.05 (sept, 1H, J = 6.4 Hz, CH(CH3)2), 3.64
(sept, 1H, J = 6.4 Hz, CH(CH3)2), 3.89 (sept, 1H, J = 7.1 Hz,
CH(CH3)2), 5.82 (dd, 2H, JH−P = 12.2 Hz, CHN), 6.70−7.59 (m,
18H, CHAr); 13C{1H} NMR (100 MHz, C6D6) δ 21.4 (s, CH2(CH3),
22.2 (s, CH2(CH3), 22.8 (s, CH2(CH3), 23.1 (s, CH2(CH3), 25.6 (s,
CH2(CH3), 26.2 (s, CH2(CH3), 26.3 (s, CH2(CH3), 26.7 (s,
CH2(CH3), 27.8 (s, CH(CH3)2), 28.0 (s, CH(CH3)2), 29.3 (s,
CH(CH3)2), 29.6 (s, CH(CH3)2), 55.2 (s, CH3−Ph), 118.8 (d, CHN,
JC−P = 3.3 Hz), 119.3 (d, CHN, JC−P = 2.1 Hz), 121.5, 123.1, 124.2,
124.5, 124.7, 124.8, 125.1, 125.3, 126.2, 126.3, 128.1, 129.1, 129.3,
130.0, 130.1, 132.7, 133.7, 133.9, 134.5, 136.0 (CAr); 31P{1H} NMR
(162 MHz, C6D6) δ 104.32 (s). Attempts to obtain samples with
analytical purity within the 0.4% range failed. The following
corresponds to an average of two different samples. Anal. Calcd for
C47H51AuClN2O2P: C, 60.10; H, 5.47; N, 2.98. Found: C, 60.87; H,
5.92; N, 3.05.
Huelva, 21007 Huelva, Spain; orcid.org/0000-0002-6899-
4641; Email: perez@dqcm.uhu.es
Authors
Juan Diego Pizarro − Laboratorio de Catalisis Homogenea,
́
́
́
Unidad Asociada al CSIC, CIQSO-Centro de Investigacion en
́
́
Quimica Sostenible and Departamento de Quimica,
Universidad de Huelva, 21007 Huelva, Spain
́
́
Francisco Molina − Laboratorio de Catalisis Homogenea,
́
Unidad Asociada al CSIC, CIQSO-Centro de Investigacion en
́
́
Quimica Sostenible and Departamento de Quimica,
Universidad de Huelva, 21007 Huelva, Spain
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.organomet.0c00343
Funding
The authors declare no competing financial interests.
Notes
The authors declare no competing financial interest.
General Catalytic Experiments. Octenes. The precatalyst 3a
(0.0125 mmol) and AgSbF6 (0.0125 mmol) were dissolved in 3 mL of
dichloromethane and stirred for 15 min. The olefin (2.5 mmol) was
added before a solution of EDA (0.25 mmol) in 6 mL of
dichloromethane was added for 12 h with the aid of a syringe
pump. After that time, volatiles were removed and the products
isolated by column chromatography.
ACKNOWLEDGMENTS
■
Support for this work was provided by the Ministerio de
́
Economia y Competitividad (CTQ2017-82893-C2-1-R) and
Universidad de Huelva (PO FEDER 2014-2020-UHU-
1260216).
n-Hexane. An equimolar mixture of complex 3a and AgSbF6
(0.025 mmol) was dissolved in 10 mL of n-hexane and 4 mL of
dichloromethane. After 15 min of stirring, EDA (0.5 mmol) dissolved
in n-hexane (10 mL) was added for 12 h via syringe pump. Yields
were determined using calibration curves following already reported
protocols from our laboratory.18
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ASSOCIATED CONTENT
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sı
* Supporting Information
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