Sterically Demanding Phosphines with 2,6-Dibenzhydryl-4-methylphenyl Core: Synthesis of RuII, PdII, and PtII Complexes, and Structural and Catalytic Studies

Article abstract of DOI:10.1021/acs.inorgchem.8b01095

The synthesis of sterically demanding aminophosphine and phosphinite ligands Ar?NHPPh₂ (1) and Ar?OPPh₂ (2), based on 2,6-dibenzhydryl-4-methylphenyl core having bulky benzhydryl groups, and their Ru^II, Pd^II and Pt^II complexes is described. The reactions of 1 and 2 with [Ru(ν⁶-p-cymene)Cl₂]₂ in 2:1 molar ratios produced mononuclear complexes [RuCl₂{(ν⁶-p-cymene)PPh₂-EAr?}-κ¹-P] (E = NH (3) and O (4)). Interestingly, complexes 3 and 4, upon refluxing in chlorobenzene, displace the p-cymene ring by one of the phenyl rings of side arms, forming rare ν⁶-arene coordinated tethered complexes [RuCl₂{(PPh₂-EAr?)-κ¹-P-ν⁶-arene}] (E = NH (5) and O (6)). Treatment of 1 and 2 with [M(COD)Cl₂] [M = Pd, Pt] in 2:1 ratios afforded mononuclear complexes [MCl₂{(PPh₂Ear?)-κ¹-P}₂] (E = NH, M= Pd (7), Pt (8); E = O, M= Pd (9), Pt (10)). Similarly, 1:1 reactions of 1 and 2 with [Pd(COD)Cl₂] produced chloro-bridged dinuclear complexes [PdCl₂{(PPh₂EAr?)-κ¹-P}]₂ (E = NH (11) and O (12)), whereas [Pt(COD)Cl₂] yielded only the mononuclear complexes 8 and 10. The reactions of 1 and 2 with [Pd(ν³-C₃H₅)Cl]₂ in 2:1 molar ratios produced the mononuclear complexes [PdCl{(ν³-C₃H₅)(PPh₂EAr?)-κ¹-P}] (E = NH (13) and O (14)). Many of these complexes have been structurally characterized, which show C-H···π interactions between the methine hydrogen of the benzhydryl and with one of the carbon atoms of the phenyl ring attached to the phosphorus center. The complex [RuCl₂{(ν⁶-p-cymene)PPh₂-NHAr?}-κ¹-P] (3) shows very short C-H···π interactions of 2.36 ? in addition, C-H···M interactions were observed between the methine hydrogen of one of the benzhydryl groups and palladium centers in 11 and 13. The tethered ruthenium complex 5 is found to be an excellent catalyst for the catalytic oxidation of various styrene derivatives.

Full text of DOI:10.1021/acs.inorgchem.8b01095

Article
Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX
pubs.acs.org/IC
Sterically Demanding Phosphines with 2,6-Dibenzhydryl-4-
II
II
II
methylphenyl Core: Synthesis of Ru , Pd , and Pt Complexes, and
Structural and Catalytic Studies
†
‡
,†
Madhusudan K. Pandey, Joel T. Mague, and Maravanji S. Balakrishna*
†Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
‡Department of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
*
S Supporting Information
ABSTRACT: The synthesis of sterically demanding amino-
phosphine and phosphinite ligands Ar*NHPPh2 (1) and
Ar*OPPh2 (2), based on 2,6-dibenzhydryl-4-methylphenyl
II
II
core having bulky benzhydryl groups, and their Ru , Pd and
II
Pt complexes is described. The reactions of 1 and 2 with
6
[
Ru(η -p-cymene)Cl ] in 2:1 molar ratios produced mono-
2
2
6
1
nuclear complexes [RuCl {(η -p-cymene)PPh -EAr*}-κ -P]
E = NH (3) and O (4)). Interestingly, complexes 3 and 4,
2
2
(
upon refluxing in chlorobenzene, displace the p-cymene ring
6
by one of the phenyl rings of side arms, forming rare η -arene
1
6
coordinated tethered complexes [RuCl {(PPh -EAr*)-κ -P-η -
2
2
arene}] (E = NH (5) and O (6)). Treatment of 1 and 2 with
M(COD)Cl ] [M = Pd, Pt] in 2:1 ratios afforded
[
2
1
mononuclear complexes [MCl {(PPh EAr*)-κ -P} ] (E = NH, M= Pd (7), Pt (8); E = O, M= Pd (9), Pt (10)). Similarly,
1
NH (11) and O (12)), whereas [Pt(COD)Cl ] yielded only the mononuclear complexes 8 and 10. The reactions of 1 and 2 with
[
and O (14)). Many of these complexes have been structurally characterized, which show C−H···π interactions between the
methine hydrogen of the benzhydryl and with one of the carbon atoms of the phenyl ring attached to the phosphorus center. The
complex [RuCl {(η -p-cymene)PPh -NHAr*}-κ -P] (3) shows very short C−H···π interactions of 2.36 Å; in addition, C−H···M
interactions were observed between the methine hydrogen of one of the benzhydryl groups and palladium centers in 11 and 13.
The tethered ruthenium complex 5 is found to be an excellent catalyst for the catalytic oxidation of various styrene derivatives.
2
2
2
1
:1 reactions of 1 and 2 with [Pd(COD)Cl ] produced chloro-bridged dinuclear complexes [PdCl {(PPh EAr*)-κ -P}] (E =
2
2
2
2
2
3
3
1
Pd(η -C H )Cl] in 2:1 molar ratios produced the mononuclear complexes [PdCl{(η -C H )(PPh EAr*)-κ -P}] (E = NH (13)
3
5
2
3
5
2
6
1
2
2
1
6
INTRODUCTION
example, κ -P-η -arene, where P is the σ-donor atom, along
5
■
6
with η -coordinated arene as a π-donor. A few known tethered
complexes of ruthenium are shown in Chart 1. Most of these
complexes typically contain two- or three-carbon tethers (I−
Ligand design plays an important role in coordination
chemistry and catalysis. Phosphines with sterically bulky
groups in the ligand framework are particularly interesting,
1
5,6
VII), whereas the complexes having heteroatoms in their
because of their catalytic efficiency in a range of organic
spacers are scarce. Alain and co-workers have reported
2
transformations. Buchwald and co-workers have reported
1
methylenaminophosphine ligands of the type R (Ph)CN−
several dialkylbiarylphosphine ligands bearing sterically bulky
1
i
PR (R = H, Ph, Pr N), which form tethered complexes of the
2
a−c
2
2
groups
that can stabilize metals in their low-valent and low-
7
type VIII. Herein, we report the synthesis of new phosphines
and 2 having bulky benzhydryl group at 2,6 positions as
pendant arms and their Ru , Pd , and Pt complexes. The
tethered ruthenium complex 5 shows excellent catalytic activity
toward the oxidation of various styrene derivatives.
coordination states and promote organic transformations
1
2
a,d,f
efficiently.
Although several bulky phosphines are known
II
II
II
in the literature, reports on bulky phosphines with direct P−N
3
and P−O bonds or having bulky aryl groups with 2,6-aryl
4
substituents are scarce. Phosphines having pendant aromatic
groups in close proximity to the P atoms are particularly
interesting, because of their ability to exhibit η , η , η , or η
binding modes, depending on the electronic situation at the
RESULTS AND DISCUSSION
2
3
4
6
■
Synthesis of N-(2,6-dibenzhydryl-4-methylphenyl)-
diphenylphosphinamine (1) and (2,6-dibenzhydryl-4-
metal center. If such ligands form complexes of the type
6
[
MX (κ-P-η -arene)] (mostly in the case of ruthenium), they
2
are usually called tethered complexes and the ligands can also
be termed as polydentate ligands (most often tetradentate), for
Received: April 20, 2018
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.inorgchem.8b01095
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Inorganic Chemistry
Article
6
Chart 1. η -Arene Tethered Ruthenium Complexes Known
in the Literature
methylphenoxy)diphenylphosphine (2). The reactions of
lithiated amide [Li{NH(Ar*)}] or lithium phenoxide [Li{O-
Figure 1. Molecular structure of Ar*NHPPh (1). Thermal ellipsoids
2
are drawn at the 50% probability level. Hydrogen atoms except (H1A
and H21) have been omitted for clarity. Selected bond lengths: P1−
N1, 1.702(13) Å; P1−C34, 1.821(16) Å; P1−C40, 1.838(16) Å; and
C1−N1, 1.419(19) Å. Selected bond angles: ∠P1−N1−C1,
(
Ar*)}] generated in situ with 1 equiv of chlorodiphenylphos-
phine resulted in the formation of Ar*NHPPh2 (1) and
Ar*OPPh (2) as white solids, as shown in Scheme 1. Because
2
1
1
23.78(11)°; ∠N1−P1−C34, 100.41(7)°; and ∠N1−P1−C40,
00.24(7)°.
Scheme 1. Synthesis of Phosphines 1 and 2
that observed in terpy-C H N(PPh ) (P−N = 1.721(2)−
6
4
2 2
8
1
.731(2) Å), N-(2,6-dibenzhydryl-4-isopropylphenyl)-1,1-di-
phenylphosphanamine (1.711(2) Å) and longer than that in
4b
t
t
the 2,6-{μ-( BuN) P( BuHN)PO} C H I (P−N = 1.666(3)−
2
2
6
3
8
,9
1
.686(3) Å) system. The C21−H21···P1 distance of 2.84 Å
in 1 suggests the phosphorus lone pair pointing toward the
methine hydrogen (see Figure 1).
II
II
II
Synthesis of Ru , Pd , and Pt Complexes. The bulky
phosphines 1 and 2, having benzhydryl substituents in close
proximity to P atom, which can freely rotate around C−C
single bonds, can coordinate and thus influence the
coordination behavior. Hence, it would be interesting to
explore their coordination behavior with various transition-
metal precursors. The possible coordination modes of 1 and 2
of the presence of bulky groups, phosphines 1 and 2 are found
to be highly air stable and also soluble in most of the organic
solvents. The spectroscopic and structural features of 1 is
similar to the aminophosphine analogue reported by Jones and
4
b
co-workers; however, the chemical shifts of NH and CH
protons of benzhydryl groups in 1 are more shielded, compared
to the Jones ligand.
1
are depicted in Chart 2. Although simple κ -coordination via
The 31P{ H} NMR spectra of 1 and 2 showed single
1
1
Chart 2. Possible Coordination Modes for Phosphines 1 and
2
resonances at 38.5 and 115.1 ppm, respectively. In the H
NMR spectra of 1 and 2, methyl protons appear as a singlet
around 2.0 ppm and aromatic protons display multiplets at
∼
6.80−7.50 ppm, while the CH protons of methine groups
show a doublet at ∼5.50 ppm, possibly due to the through-
space coupling (J = 3.1 and 2.1 Hz, respectively) with the P
PH
atom. The NH proton of 1 appeared as a doublet at 3.23 ppm
1
with a J coupling of 7.6 Hz. The molecular compositions
PH
were confirmed by mass spectrometry, and the structure was
confirmed by X-ray analysis in the case of 1. The perspective
view of the molecular structure of 1, along with the selected
bond lengths and the bond angles, are shown in Figure 1. The
pyramidal geometry around the P atom (∠N1−P1−C34 =
1
00.40(7)°, ∠N1−P1−C40 = 100.25(7)°, ∠C34−P1−C40 =
9.15(7)°) is slightly distorted. The geometry around nitrogen
9
the P atom (I, II, and III) is the most common and preferred
mode for both ligands 1 and 2, the bulky phosphines 1 and 2,
upon treatment with suitable metal precursors, can give rise to
type IV complexes. The coordination behavior of 1 and 2 with
various transition-metal derivatives has been investigated in
detail.
(∠C1−N1−P1 = 123.78(11)°, ∠P1−N1−H1 = 117.4(13)°,
∠
C1−N1−H1 = 110.3(13)°) is also distorted, with a
significantly larger ∠C1−N1−P1 bond angle of 123.78(11)°,
probably to overcome the steric congestion. The two phenyl
rings on P atoms are nearly orthogonal to each other, as
observed from their torsion angles (∠P1−C40−C45−C44 =
6
The reactions of 1 and 2 with [Ru(η -p-cymene)Cl ] in 2:1
2
2
1
68.92(13)°, ∠P1−C34−C39−C38 = 176.28(13)°). The P−N
ratios in dichloromethane resulted in mononuclear complexes
6
1
bond distance of 1.702(13) Å in 1 is in the expected range with
partial N2Pπ → Pσ* multiple bonding, but slightly shorter than
[RuCl {(η -p-cymene)PPh -NHAr*}-κ -P] (3) and
2 2
6 1
[RuCl {(η -p-cymene)PPh -OAr*}-κ -P] (4) in good yield as
2
2
B
DOI: 10.1021/acs.inorgchem.8b01095
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Inorganic Chemistry
Article
red solids (see Scheme 2). Complexes 3 and 4 showed singlets
at 57 and 124 ppm, respectively, in their P{ H} NMR spectra.
observed in related arene ruthenium(II) complexes and is
attributed to the bond-lengthening effect of the phosphine
3
1
1
5
,12
ligands.
The Ru−P (2.366(7) Å) and Ru−Cl (2.415(7) Å)
6
Scheme 2. Synthesis of Ruthenium Complexes 3−6
bond distances are similar to those in [Ru(η -p-cymene)-
Cl {DippNH-PPh }-κ -P] (2.372(5) and 2.418(6) Å), [{Ru-
1
10
2
2
6
1
(
η -p-cymene)Cl } {(μ-DPEphos)-κ -P}] (2.370(10) and
2 2
12c
6
1
2
(
.410(8) Å),
and [Ru(η -p-cymene)Cl {(PPh )-κ -P}]
2 3
11
2.343(6) and 2.415(6) Å).
The objective of making ligands 1 and 2 with bulky
benzhydryl pendant arms was to form tethered complexes
involving phenyl groups as (η −η ) donors. Since the reactions
of 1 and 2 with [Ru(η -p-cymene)Cl ] did not yield
2
6
6
2
2
anticipated tethered complexes of the type [RuCl {PPh -
2
2
1
6
EAr*}(κ -P-η -arene)], complex 3 was heated to 120 °C in
chlorobenzene for 16 h, which resulted in tethered complex 5,
as confirmed from spectroscopic and structural studies.
6
Alternately, the reactions of 1 and 2 with [Ru(η -p-cymene)-
Cl ] in chlorobenzene at 120 °C produced the same tethered
2
2
complexes 5 and 6 in good yield. Arene exchange reactions are
13
known in the case of (arene)tricarbonylchromium complexes.
These reactions proceed at very high temperature (150−170
C) and require aromatic reagents as solvents. In order to
assess the arene exchange reactions, the ruthenium complexes
1
The H NMR spectra of 3 and 4 are consistent with the
°
proposed structures. The NH proton of 3 appeared as a
doublet at 5.25 ppm with a J coupling of 14.9 Hz. The large
downfield shift (2.02 ppm) of NH proton in 3, compared to
that of the free ligand 1, is due to its hydrogen bonding with the
Cl ion, as evident from its X-ray structure. Complex 3 adopts
the three-legged “piano stool” geometry with the ruthenium
atom in a pseudo-octahedral environment (Figure 2). The
1
PH
3
−6 were heated at 150 °C in xylene or mesitylene for 24−48
h; arene exchange was not observed, but cymene complexes 3
and 4 were converted to tethered complexes 5 and 6. The H
1
−
NMR spectrum of 5 showed triplets at δ 6.24 and 6.14 ppm,
with a coupling of 6.0 Hz; doublets at δ 5.81 and 4.73 ppm,
with a coupling of 4.3 and 5.6 Hz; and a triplet at δ 5.01 ppm,
with a coupling of 5.6 Hz. These observations supported the
6
presence of a η -coordinated phenyl ring, hence confirming the
1
formation of a tethered complex [RuCl (PPh -NHAr*)(κ -P-
2
2
6
η -arene)] (5). Under identical reaction conditions, 4 produced
1
6
tethered complex [RuCl (PPh -OAr*)(κ -P-η -arene)] (6)
2
2
(
see Scheme 2). The 31P{ H} NMR spectra of 5 and 6
1
showed singlets at 64.3 and 118.7 ppm, with shifts of 7.3 and
5
.2 ppm, with respect to complexes 3 and 4.
1
In the H NMR spectrum of 5, the NH proton appears as a
1
doublet at 3.78 ppm with a J coupling of 5.0 Hz, which is
PH
more shielded, compared to that of complex 3 (5.25 ppm). The
structures of 5 and 6 were confirmed by single-crystal X-ray
analysis.
The perspective views of molecular structures of 5 and 6,
along with the atom labeling scheme, are shown in Figure 3.
The crystallographic data and the details of the structure
6
Figure 2. Molecular structure of [RuCl {(η -p-cymene)PPh -
2
2
1
NHAr*}-κ -P] (3). Hydrogen atoms except (H1 and H21) have
been omitted for clarity. Displacement ellipsoids are drawn at the 50%
probability level.
∠
C1−N1−P1 bond angle (125.48(18)°) is slightly larger than
the same in 1 (123.78(11)°) due to the steric interactions
between the p-cymene and the Ph CH moieties of the ligand
2
backbone. As a result, the p-cymene group is pushed away from
the metal center, which is evident from the slightly longer Ru−
C(cymene) distances in 3 (2.175(3)−2.249(3) Å). However,
the average Ru−C(cymene) distance of 2.219 Å in 3 is in the
6
range observed in complexes such as [Ru(η -p-cymene)-
1
10
6
Cl {DippNH-PPh }-κ -P] (2.211(2) Å) and [RuCl (η -p-
1
6
2
2
2
Figure 3. Molecular structures of [RuCl (PPh -NHAr*)-(κ -P-η -
1
11
2
2
cymene){(PPh )-κ -P}] (2.218(2) Å). The Ru−C bonds
1
6
3
arene)] (5) and [RuCl (PPh -OAr*)-(κ -P-η -arene)] (6). Hydrogen
2 2
trans to the P atom (Ru(1)−C(53) = 2.241(3) Å and Ru(1)−
C(54) = 2.249(3) Å) are slightly longer than those trans to the
two Cl− ions (2.175(3)−2.231(3) Å). Similar trends were
atoms except for (H1 and H8 in 5 and H8 and H21 in 6) have been
omitted for the sake of clarity. Displacement ellipsoids are drawn at the
50% probability level.
C
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Inorganic Chemistry
Article
determination are given in Table S2 (in the Supporting
Information (ESI)), and the selected bond lengths (Å) and the
bond angles (deg) are listed in Table 1. Complexes 5 and 6
in the range observed in complexes [CpRuCl(PPh )(PPh N-
3
2
9
(H)Ph)] and [CpRuCl(PPh N(H)Ph) ]. The P−O distance
2
2
6
of 1.625(2) Å in 6 is similar to that found in [{RuCl (η -p-
cymene)} (Ph POC H OPPh )] (1.635(2) Å)
[RuCl (η -p-cymene){Ph P(OAr)}] (1.627(2) Å). The
2
1
5
and
2
2
6
4
2
6
16
Table 1. Selected Bond Lengths and Bond Angles for
Compounds 3, 5, and 6
2 2
∠C1−E1−P1 bond angles of 129.6(3)° and 128.7(2)° in 5
and 6 are larger than the same in 3 (125.4(8)°). The larger
3
5
6
∠
C1−E1−P1 angles in 5 and 6 push the PPh group away from
2
Bond Lengths (Å)
the methine hydrogen of benzhydryl, and, as a result, the C−
H···π interactions in these complexes become considerably
weaker than the same in 3. The molecular structure of 3 shows
very short C−H···π interactions of 2.36 and 2.69 Å between the
methine hydrogen of the benzhydryl group with the ortho and
ipso carbons (C39 and C34) of one of the phenyl rings of PPh2
moiety (see Figure 2). The analogous arene complexes 5 and 6
have slightly longer C−H···π interactions between the methine
hydrogen of the benzhydryl group and with the ipso carbon of
M1−P1
M1−Cl1
M1−Cl2
P1−E
2.366(7)
2.416(7)
2.415(7)
1.693(2)
2.312(11)
2.401(11)
2.410(10)
1.690(3)
2.278(9)
2.382(9)
2.386(9)
1.625(2)
Bond Angles (deg)
C1−E1−P1
125.48(18)
86.59(2)
129.6(3)
128.7(2)
89.86(3)
88.56(3)
85.09(3)
100.71(16)
Cl2−M1−Cl1
Cl2−M1−P1
Cl1−M1−P1
C34−P1−C40
90.14(4)
88.46(4)
85.90(4)
99.78(18)
87.62(2)
90.70(2)
one of the phenyl rings of the PPh group (H8···C34 = 2.88 Å
2
100.50(13)
in 5, H8···C34 = 2.88 Å, and H21···C40 = 2.83 Å in 6) (see
Figure 3). The C−H···π interactions found in these complexes
are very comparable to the same in analogous complexes
adopt the three-legged “piano stool” geometry with a Ru atom
4a,17
reported in the literature.
NMR spectroscopy is a powerful
in a pseudo-octahedral environment with the tethered phenyl
−
method for studying the weak interactions in solution; the
ring of the ligand backbone, two Cl ions, and the P atom
1
1
H− H NOESY experiments are very useful for the detection of
completing the coordination sphere. The Ru−P bond lengths
of 2.312(11) and 2.2787(9) Å in complexes 5 and 6 are shorter
than the same in 3 (2.3663(7) Å). The Ru−P and Ru−Cl bond
distances in 3 and 5 are unexceptional and are found to be in
18
C−H···π interactions in solutions. Two-dimensional nuclear
1
1
1
1
magnetic resonance (2-D) NMR ( H− H COSY and H− H
NOESY) and NOE experiments were carried out in order to
7
,14
1
1
the range of previously reported complexes.
Ru1−Cl1 bond angles in complexes 5 (85.90(4)°) and 6
85.09(3)°) are smaller than the same in 3 (90.70(2))°,
The ∠P1−
gain some insight into the C−H···π interactions. The H− H
1 1
COSY and NOE spectra of 3 and the H− H NOESY
spectrum are presented in Figure 4, as well as Figure S12 in the
ESI, respectively. All the protons of 3 have been identified
based on their location, integration, coupling constants, and
(
whereas the ∠P1−Ru1−Cl2 and ∠Cl1−Ru1−Cl2 bond angles
in 5 and 6 lie within a fairly narrow range and are surprisingly
close to the corresponding angles in 3, suggesting that
constraining the coordinated phosphine moiety and arene
ring via unsaturated tether does not have a marked influence on
the coordination geometry at the metal center. The molecular
structures of complexes 3, 5, and 6 show that the distance
between the Ru center and the centroid of p-cymene or
proximal phenyl ring of ligand backbone is 1.70 Å and is
independent of coordination geometry around the metal. The
P−N bond lengths of 1.693(2) and 1.690(3) Å in 3 and 5 are
1
1
1
1
cross-peak correlations using H− H COSY and H− H
NOESY NMR spectra. The aromatic protons of the side
arms of benzhydryl groups appear in two sets (6.6 and. 7.0
ppm) and show correlation with each other, whereas the
aromatic protons attached to phosphorus-bound phenyl groups
appear as three sets of multiplets in which H protons show
f
correlation with H protons, which, in turn, show correlation
e
with H protons. The methine protons of benzhydryl groups
d
observed at 6.15 ppm show NOE correlation with H protons
d
1
1
Figure 4. H− H COSY and NOE spectra of 3 recorded in CDCl .
3
D
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Inorganic Chemistry
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1
1
of phenyl groups bonded to the P atom. In the H− H NOESY
The metal center in complexes 7, 8, and 10 adopt slightly
distorted square-planar geometries. The Pd−P and Pd−Cl
bond distances of 2.3138(8) and 2.299(8) Å in 7 are similar to
spectrum, the H protons show through-space correlation with
a
1
1
Hd protons. Therefore, the NOE and H− H NOESY
experiments clearly demonstrate the existence of intramolecular
CH···π interactions in 3.
Synthesis of Pd and Pt Complexes. The reactions of
M(COD)Cl ] (M = Pd or Pt) with 1 and 2 in 1:2 molar ratios
in dichloromethane afforded the trans complexes
MCl {(PPh EAr*)-κ -P} ] (7−10) as shown in Scheme 3.
1
those in [PdCl {(DippNH-PPh ) }-κ -P] (2.3124(4) and
2
2 2
20
2.3014(8) Å) and lie within the normal range expected for
II
II
21
trans-[PdCl (PR ) ] complexes, as well as the Pt−P and Pt−
2
3 2
[
Cl bond distances in 8 (2.297(13), 2.3066(11) Å) and 10
2
21b
(2.3071(2), 2.3065(9) Å).
The solid-state molecular
1
[
structures of 7, 8, and 10 confirm the trans arrangement of
the bulky phosphines around the metal center. These
complexes have a center of symmetry lying at the metal center.
In addition, they also have a crystallographically imposed 2-fold
rotation axis passing through the metal center. In complexes 7
and 8, the 2-fold rotation axis is passing through the metal
center and is perpendicular to the square plane formed by two
2
2
2
II
II
Scheme 3. Synthesis of Pd and Pt Complexes
−
Cl ions and two P atoms. In contrast, the 2-fold rotation axis
in complex 10 is passing through the PtCl moiety along the
2
plane formed by the two Cl− ions and two P atoms. The
pendant phenyl rings are disposed above and below the 4-
methylphenyl moiety and, although pointed away from the
PPh group, provide enough steric hindrance (hence, the trans
2
conformations around the metal center). Complexes 8 and 10
show C−H···π type intramolecular interactions. The C−H···π
interactions between the methine hydrogen of the benzhydryl
and the ipso carbon of the PPh group (H8···C40 = 2.56 Å in 7,
2
H21···C34 = 2.57 Å in 8, and H21···C40 = 2.76 Å in 10) are in
the range found in the ruthenium complexes 3, 5, and 6 (2.36−
However, the equimolar reactions of 1 and 2 with [Pd(COD)-
4a
Cl ] under similar reaction conditions produced chloro-bridged
2.88 Å), as well as in other similar complexes. The ∠E1−P1−
M1 angles of 110.55(10)° and 110.81(16)° in 7 and 8 (Figure
5) are considerably smaller than the same in complex 10
(117.11(7)°) (Figure 6). The larger ∠E1−P1−M1 bond angle
2
1
dimers [PdCl {(PPh EAr*)-κ -P}] (11 and 12) (see Scheme
). Similar reactions of 1 and 2 with [Pt(COD)Cl ] in 1:1
2
2
2
3
2
molar ratios yielded only the mononuclear complexes 8 and 10.
The 31P{ H} NMR spectra of palladium complexes 7 and 9
showed singlets at 54.5 and 100.6 ppm, whereas the platinum
complexes 8 and 10 also showed singlets at 46.0 and 90.4 ppm,
1
in 10 allows the PPh and benzhydryl groups to stay away from
2
each other; as a result, the C−H···π interaction becomes
weaker in complex 10. [Selected bond lengths and bond angles
for compounds 7, 8, and 10 are shown in Table 2.]
The molecular structures of complexes 11 and 12 are
confirmed by single-crystal X-ray analysis. Both complexes 11
and 12 have similar bond parameters. Complexes 11 and 12
have crystallographically imposed 2-fold rotation axis passing
1
95
1
but with characteristic Pt satellites with J couplings of
PtP
1
2
611 and 2887 Hz, respectively. The lower JPtP coupling values
support the trans disposition of P atoms. The dimeric
palladium complexes 11 and 12 showed P{ H} chemical
shifts at 61.2 and 102.6 ppm, respectively, which are slightly
deshielded, compared to the same in complexes 7 and 9. The
19
3
1
1
through the bridging chloride (μ -Cl) atoms. The palladium
2
1
H NMR spectra and mass spectrometry also support the
center in these complexes adopt slightly distorted square planar
geometries. Complexes 11 and 12, by virtue of their bulkiness,
showed C−H···π as well as C−H···M type intramolecular
product formation. The identity of complexes 7, 8, and 10−12
were established by single-crystal X-ray studies.
1
1
Figure 5. Molecular structures of [PdCl {(PPh NHAr*) -κ -P}] (7) and [PtCl {(PPh NHAr*) -κ -P}] (8). All hydrogen atoms (except H8 in 7,
2
2
2
2
2
2
and H21 in 8) are omitted for the sake of clarity. Displacement ellipsoids are drawn at the 50% probability level.
E
DOI: 10.1021/acs.inorgchem.8b01095
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Inorganic Chemistry
Article
23
distances are as expected. [Selected bond lengths and bond
angles for compounds 11 and 12 are shown in Table 3.]
Table 3. Selected Bond Lengths and Bond Angles for
Compounds 11 and 12
1
1
12
Bond Lengths (Å)
1.675(4)
E1−P1
1.610(5)
2.208(2)
2.327(17)
2.428(18)
2.273(18)
1.415(8)
P1−Pd1
Cl1−Pd1
Cl1−Pd1
Cl2−Pd1
C1−E1
2.203(12)
2.307(12)
1
2.432(12)
2.283(11)
1.438(6)
Bond Angles (deg)
116.42(16)
110.01(14)
97.27(4)
Pd1−P1−C34
Pd1−P1−E1
Cl1−Pd1−P1
Cl1 −Pd1−P1
Cl2−Pd1−P1
Cl2−Pd1−Cl1
116.5(2)
113.9(2)
95.96(7)
177.80(7)
86.98(6)
91.06(6)
1
172.83(5)
1
Figure 6. Molecular structure of [PtCl {(PPh OAr*) -κ -P}] (10). All
2
2
2
84.58(4)
hydrogen atoms except H21 are omitted for the sake of clarity.
Displacement ellipsoids are drawn at the 50% probability level.
1
91.68(4)
3
Treatment of 1 and 2 with 0.5 equiv [Pd(η -C H )Cl]
3
5
2
Table 2. Selected Bond Lengths and Bond Angles for
Compounds 7, 8, and 10
3
1
afforded [PdCl{(η -C H )(PPh EAr*)-κ -P}] (13 and 14), as
shown in Scheme 4. The P{ H} NMR spectra of 13 and 14
3
5
2
31
1
7
8
10
Scheme 4. Synthesis of Palladium Allyl Complexes 13 and 14
Bond Lengths (Å)
M1−P1
M1−Cl1
P1−E1
2.313(8)
2.299(8)
1.680(3)
2.297(17)
2.306(17)
1.681(4)
2.307(7)
2.288(9)
1.626(19)
Bond Angles (deg)
1
Cl1 −M1−Cl1
180.0
180.0
180.0
1
1
Cl −M1−P1
P1 −M1−Cl1
P1−M1−P1
86.68(3)
93.32(3)
180.0
86.66(4)
93.34(4)
180.0
93.79(17)
86.20(17)
172.40(3)
1
1
interactions. The C−H···π interactions between the methine
hydrogen of the benzhydryl and the ipso carbon of the PPh2
group (H21···C34 = 2.82 Å in 11 and H8···C40 = 2.87 Å in 12)
are slightly weaker than the same observed in mononuclear
complex (H8···C40 = 2.56 Å) 7. In addition to the C−H···π
interaction, complex 11 also shows C−H···M interaction
between the methine hydrogen of the benzhydryl group and
palladium atom (H8···Pd1 = 2.61 Å) (see Figure 7). The
relatively long M···H bond distance of 2.61 Å and nearly linear
showed singlets at 69.0 and 132.1 ppm, respectively. The allylic
group in square planar palladium complexes are known to
3
1
undergo η to η conversion influenced by the ligand steric
3
1
attributes. Sterically bulky phosphines retard the η -to-η
24
conversion process. Similar phenomena were observed in
1
13 and 14, as evidenced by the H NMR spectral data. The
allylic protons showed five distinct signals for each proton of
3
1
the allyl group ruling out the possibility of η to η exchange in
1
solution. The H NMR spectra of 13 and 14 showed five allylic
3
∠
M···H−C bond angle of 176.92° in 11 suggests it to be an
signals due to the presence of an unsymmetrical η -allyl group.
22
anagostic interaction. The Pd−P, Pd−Cl, and Pd−Pd bond
The two upfield resonances at ∼3.0 and 1.9 ppm can probably
1
1
Figure 7. Molecular structures of [PdCl {(PPh NHAr*)-κ -P}] (11) and [PdCl {(PPh OAr*)-κ -P}] (12). All hydrogen atoms (except H8 and
2
2
2
2
2
2
H21 in 11 and H8 in 12) are omitted for the sake of clarity. Displacement ellipsoids are drawn at the 50% probability level.
F
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Inorganic Chemistry
Article
−
be assigned to the CH group anti to the Cl ion, which lies in
is an important reaction in the organic synthesis, because it
leads to the addition of oxygen functionality. Generally, it is
2
the anisotropic cone of the phenyl core of the ligand backbone.
The metal center in these complexes adopt slightly distorted
square-planar geometries. The Pd−C(allyl), Pd−P, and Pd−Cl
carried out with highly toxic OsO and a variety of co-oxidants
4
[H O , TBHP, PhI(OAc) , NaIO ] in different solvent
2
2
2
4
25
26
bond lengths are typical for these types of complexes. The
systems. RuCl with NaIO as the oxidant was used by
3 4
27
∠
Cl1−Pd1−P1 bond angles in 13 and 14 are 96.95(7)° and
Sharpless for oxidative cleavage of olefins. Subsequently, a
3
9
3.65(2)°, respectively. The molecular structure of [PdCl{(η -
significant number of RuCl /oxidant/solvent combinations
3
1
28
C H )(Ar*NHPPh )-κ -P}] (13) shows a C−H···π interaction
have been explored. However, high catalyst loading and
3
5
2
between the methine hydrogen of the benzhydryl and the ipso
carbon (C40) of the PPh2 group (H8···C40 = 2.70 Å).
overoxidation of aldehydes to the corresponding acids is the
major drawback. Apart from RuCl /oxidant/solvent combina-
3
3
1
Interestingly, the complex [PdCl{(η -C H )(Ar*OPPh )-κ -
tions, abnormal NHC-based ruthenium complexes that show
3
5
2
2
9
P}] (14) shows C−H···π interactions between both the
moderate to good conversion also have been used.
methine hydrogen of the benzhydryl groups and both the
Surprisingly, to the best of our knowledge, ruthenium
complexes of phosphine ligands have not been explored in
the catalytic oxidation of olefin. Complexes 3, 4, and 6 showed
only moderate conversion (up to 85%) at room temperature,
whereas the arene complex 5 afforded quantitative conversion
to aldehydes. During the process, the formation of dihydroxy,
epoxide, α-hydroxy ketone, or α-dione are not observed. Acid
formation was observed in a few cases. Quantitative conversion
to benzaldehyde was achieved at room temperature within 20
min in a 1:1 acetonitrile/water solvent combination. The
substrate scope was examined under the optimized conditions
at room temperature (see Chart 3). Styrene and the electron-
ipso carbons (C40 and C34) of the PPh group (H8···C40 =
.58 Å and H21···C34 = 2.76 Å). In addition, complex 13 also
displays a C−H···M interaction (H21···Pd = 2.98 Å) between
the methine hydrogen of the benzhydryl side arm and the
palladium center (see Figure 8). The longer C−H···M bond
2
2
Chart 3. Substrate Scope for Catalytic Oxidation of Various
a
Styrene Derivatives
3
1
Figure 8. Molecular structures of [PdCl{(PPh NHAr*)(η -C H )-κ -
2
3
5
3
1
P}] (13) and [PdCl{(PPh OAr*)(η -C H )-κ -P}] (14). All hydrogen
2
3
5
atoms except H8 and H21 are omitted for the sake of clarity.
Displacement ellipsoids are drawn at the 50% probability level.
distance and the relatively larger ∠C−H···M bond angle of
a
3
1
Conditions: olefins, 0.4 mmol; catalyst 5 (1 mol %); solvent
1
29.91° in [PdCl{(η −C H )(Ar*NHPPh )-κ -P}] (13) sug-
3
5
2
b
22
(CH CN:H O), (1:1, 4 mL); NaIO , 1.2 mmol; RT. Based on GC-
gest this interaction to be weakly anagostic in nature.
Selected bond lengths and bond angles for compounds 13
3
2
4
MS.
[
and 14 are shown in Table 4.]
Catalytic Oxidation of Styrene Derivatives Using
Ruthenium Complexes 3−6. Oxidative cleavage of olefins
rich styrene derivatives p-methyl and tert-butylstyrene afforded
quantitative conversions to the corresponding aldehydes
(
entries b and c in Chart 3) but required longer time. The
Table 4. Selected Bond Lengths and Bond Angles for
Compounds 13 and 14
electron-deficient styrenes took less time than the electron-rich
styrenes (entries d−h in Chart 3). Optimization of the reaction
conditions for the catalytic oxidation of styrene is detailed in
Table 5.
To assess and compare the catalytic efficiency of 5 with other
ligands, catalytic oxidation reactions were performed using a
1
3
14
Bond Lengths (Å)
2.309(5)
M1−P1
M1−Cl1
P1−E1
M1−C46
M1−C47
M1−C48
2.291(17)
2.361(19)
1.657(5)
2.179(9)
2.161(9)
2.147(10)
2.3545(6)
6
mixture of [Ru(η -p-cymene)Cl ] and PPh , PPh (NHPh), or
PPh (OPh) with NaIO as an oxidant. In all of these cases,
2
2
3
2
1.700(17)
2
4
2.139(2)
moderate conversion to benzaldehyde was observed (up to
0%), along with the formation of some overoxidation products
see in the ESI, Table S1). Under identical conditions, ligands 1
2.148(4)
6
(
2.190(2)
Bond Angles (deg)
96.95(2)
and 2 showed conversions of 65% and 60%. However, isolated
complex 5 in the presence of NaIO4 showed almost
quantitative conversions.
P1−M1−Cl1
93.62(7)
172.9(3)
99.9(3)
C(46)−M1−P(1)
E(1)−P(1)−C(34)
E(1)−P(1)−M(1)
E(1)−P(1)−C(40)
101.33(7)
104.05(10)
112.63(6)
To probe the actual catalyst involved in the catalysis, we
123.15(19)
99.4(3)
carried out the reaction of complex 5 with an excess NaIO (aq)
at room temperature in acetonitrile. Acetonitrile solution was
4
106.08(9)
G
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Table 5. Optimization of the Reaction Conditions for the Catalytic Oxidation of Styrene
a
No.
substrate
NaIO (equiv)
precatalyst (mol %)
time (min)
product
conversion (%)
4
1
2
3
4
5
6
7
8
styrene
styrene
styrene
styrene
styrene
styrene
styrene
2
3
3
3
3
3 (5)
3 (1)
5 (1)
4 (1)
6 (1)
5 (1)
10
10
10
10
10
10
10
30
benzaldehyde
benzaldehyde
benzaldehyde
benzaldehyde
benzaldehyde
not observed
not observed
benzaldehyde
48
70
100
75
85
b
NC
b
3
4
NC
styrene
10
a
b
Based on GC-MS. NC = no conversion.
subjected to ESI-MS analysis, which showed a signal for [M-
acquired using broadband decoupling methods. The spectra were
recorded in CDCl solutions with CDCl as an internal lock; chemical
shifts of H and C{ H} NMR spectra are reported in ppm downfield
+
VI
Cl] at m/z 792.1339 (z = 1) corresponding to [Ru (1)Cl2-
O) ] (1 = Ligand) [see ESI Figure S57]. The presence of
3
3
1
13
1
(
2
from TMS, which was used as an internal standard. The chemical shifts
metal-bound 1 suggests that the molecular integrity of the
31
1
of P{ H} NMR spectra were referred to 85% H PO as an external
3
4
catalyst is maintained during the catalysis. Therefore, the
standard. Positive values indicate downfield shifts. Mass spectra were
recorded using a Bruker Maxis Impact LC-q-TOF mass spectrometer.
Infrared spectra were recorded on a PerkinElmer Spectrum One FT-
IR spectrometer (Model No. 73465) in KBr disk. The microanalyses
were performed using a Thermo Finnigan FLASH EA 1112 Series
CHNS Analyzer. The melting points of all compounds were
determined on a Veego melting point apparatus and were uncorrected.
VI
complex 5 acts as a pre-catalyst and the Ru dioxo compound
VI
[
Ru (1)Cl (O) ] might be the active catalyst.
2
2
CONCLUSIONS
■
The coordination behavior of sterically demanding phosphines
II
II
II
1
and 2 toward Ru , Pd , and Pt has been described.
Synthesis of (Ar*NHPPh ) (1). To a solution of 2,6-bis-
2
1
Phosphines 1 and 2 form mononuclear (κ -P) complexes with
(benzhydrylmethyl)-4-methylaniline (1.92 g, 4.36 mmol) in toluene
6
3
n
[
RuCl (η -p-cymene)] and [Pd(η -C H )Cl] , whereas with
(40 mL) was added, dropwise, a solution of BuLi (3.0 mL, 1.6 M in
2
2
3
5
2
[
M(COD)Cl ], both mononuclear as well as chloro-bridged
hexanes) at −50 °C; the mixture was allowed to warm to room
temperature and additional stirring occurred for 4 h. A solution of
2
dinuclear complexes were isolated. The ruthenium p-cymene
complexes afforded tethered η -arene complexes on refluxing in
6
PPh Cl (0.970 g, 4.40 mmol) in toluene (20 mL) was added dropwise
2
at −70 °C and the reaction mixture was allowed to come to room
temperature and additional stirring was performed for a period of 16 h.
The reaction mixture was filtered using a Celite bed to remove LiCl
and toluene was removed under reduced pressure to give the crude
product. Petroleum ether (50 mL) was added and sonicated for 30
min to give a white solid, which was filtered to give analytically pure
product 1 as a white crystalline solid. The colorless crystals of 1
suitable for single-crystal X-ray diffraction (XRD) study were obtained
by slow diffusion of petroleum ether into the dichloromethane
solution of 1 at room temperature. Yield 66.4% (1.8 g). Melting point
chlorobenzene. In mononuclear as well as dinuclear palladium
complexes, ligands 1 and 2 occupy the trans position, because
6
of their steric bulk, while in η -arene complexes, the ligands act
−
as 8e donors. The catalytic activity of ruthenium complexes
3−6 has been evaluated in olefin oxidation reactions. In the
case of tethered ruthenium complex 5, quantitative conversions
were observed, whereas complexes 3, 4, and 6 showed
moderate conversions, similar to other ligands, such as PPh3,
PPh (NHPh), or PPh (OPh) under identical conditions.
2
2
(
2
mp) 200−203 °C. Anal. Calcd for C H NP: C, 86.64; H, 6.14; N,
4
5
38
Interestingly, tethered complex 5, even in the presence of
1
.24. Found: C, 86.36; H, 5.83; N, 2.21. H NMR (400 MHz, CDCl ):
3
oxidant NaIO , did not decompose, which indicated its
4
δ 7.29−7.07 (m, 20H, ArH), 6.78 (dd, J = 7.5, 1.6 Hz, 10H, ArH), 6.43
robustness. Currently, we are looking into the reactivity of
group 10 complexes and also other catalytic reactions using
tethered complex 5. Furthermore, because of the rotational
fluxionality of the phosphine moiety, the acidic methine C−H
bond(s) of the pendant arms of the ligands can be activated to
form interesting complexes.
(
1
s, 2H, ArH), 5.52 (d, J = 3.1 Hz, 2H, Ph CH), 3.23 (d, J = 7.6 Hz,
2
13
H, NH), 2.03 (s, 3H, ArCH3). C NMR (101 MHz, CDCl ): δ
3
143.78 (s), 142.45 (s), 139.27 (d, J = 3.2 Hz), 131.84 (s), 131.63 (s),
129.89 (s), 129.81 (s), 129.14 (s), 128.55 (d, J = 6.7 Hz), 128.19 (s),
126.25 (s), 51.94 (d, J = 4.3 Hz), 21.50 (s). 3 P{ H} NMR (162 MHz,
1
1
−
1
CDCl ): δ 38.54 (s). FT−IR (KBr disk, cm ): 3320 s, 3053 m, 3019
3
m, 2911 w, 2863 w, 1594 w, 1456 s, 1443 s, 1265 m, 1077 w, 1026 w,
78 w, 727 s, 693 s. ESI-MS: m/z calcd. for C H NP (M+H) :
+
8
45
39
EXPERIMENTAL SECTION
■
624.2815. Found: 624.2806.
General Procedures. All of the air-sensitive compounds were
handled and stored in an MBRAUN glove box. All manipulations were
performed under an inert atmosphere of dry nitrogen or argon, using
standard Schlenk techniques. All the solvents were dried by
Synthesis of (Ar*OPPh ) (2). To a solution of 2,6-bis-
2
(benzhydrylmethyl)-4-methylphenol (1.87 g, 4.20 mmol) in toluene
n
(50 mL) was added, dropwise, a solution of BuLi (2.9 mL, 1.6 M in
hexanes) at −50 °C, and the mixture was allowed to warm to room
3
0
conventional methods and distilled prior to use. [Ar*NH ],
temperature and was stirred for 4 h. A solution of PPh Cl (0.936 g,
2
2
3
1
6
32
[
Ar*OH], [Ru(η -cymene)Cl ] , [M(COD)Cl ] (M = Pd or
4.20 mmol) in toluene (20 mL) was added, dropwise, to the reaction
mixture at −70 °C stirred for an additional period of 16 h at room
temperature. The solution was filtered and the crude product obtained
was dissolved in petroleum ether (30 mL) and sonicated for 30 min to
give analytically pure microcrystalline product 2 as a white solid. Yield
69.4% (1.82 g). mp = 168 °C. Anal. Calcd for C H OP: C, 86.51; H,
2
2
2
3
3
3
34
35
36
Pt), [Pd(η -C H )Cl] , [PhNHPPh2], and [PhOPPh2] were
3
5
2
prepared according to the published procedures. Other reagents were
obtained from commercial sources and used after purification.
Instrumentation. The solution NMR spectra were recorded on
Bruker FT spectrometers (Model Avance-400 or 500) MHz at
4
5
37
ambient probe temperatures. 13C{ H} and P{ H} NMR spectra were
1
31
1
5.97. Found: C, 86.71; H, 6.13. H NMR (400 MHz, CDCl ): δ 7.46
1
3
H
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Inorganic Chemistry
Article
(
dd, J = 11.2, 4.7 Hz, 4H, ArH), 7.41−7.29 (m, 8H, ArH), 7.29−7.19
ArH), 7.29−7.18 (m, 7H, ArH), 7.15 (t, J = 7.6 Hz, 2H, ArH), 7.08
(dt, J = 10.7, 7.5 Hz, 2H, ArH), 7.05−6.99 (m, 5H, ArH), 6.33 (d, J =
15.9 Hz, 2H), 6.28 (d, J = 7.6 Hz, 2H), 6.24 (t, J = 6.0 Hz, 1H), 6.14
(
=
m, 10H, ArH), 6.88−6.85 (m, 8H, ArH), 6.62 (s, 2H, ArH), 5.69 (d, J
13
2.1 Hz, 2H, Ph CH), 2.17 (s, 3H, ArCH ). C NMR (126 MHz,
2 3
6
6
CDCl ): δ 143.93 (s), 135.69 (s), 131.07 (s), 130.88 (s), 130.24 (s),
1
1
(
(t, J = 5.9 Hz, 1H, η -C H ), 5.81 (d, J = 4.3 Hz, 1H, η -C H ), 5.01 (t,
3
6 6 6 6
6
6
29.83 (s), 129.72 (s), 128.65 (s), 128.46 (d, J = 7.8 Hz), 128.24 (s),
J = 5.6 Hz, 1H, η -C H ), 4.73 (d, J = 5.6 Hz, 1H, η -C H ), 4.00−3.95
6
6
6
6
27.99 (s), 126.01 (s), 50.43 (d, J = 3.6 Hz), 21.37 (s). 31P{ H} NMR
1
(m, 1H, η -C H ), 3.78 (d, J = 5.0 Hz, 1H, NH), 1.95 (s, 3H,
6
6
6
−
1
13
162 MHz, CDCl ): δ 115.13 (s). FT−IR (KBr disk, cm ): 3056 m,
ArCH ). C NMR (126 MHz, CDCl ): δ 143.33 (s), 141.33 (s),
3
3
3
3
023 m, 2855 w, 1596 w, 1458 s, 1447 s, 1263 m, 1250 m, 1203 w, 863
140.70 (s), 138.62 (s), 134.55 (d, J = 10.2 Hz), 131.11(s), 130.80 (s),
130.63 (s), 130.00 (s), 129.65 (s), 129.16 (s), 128.89 (s), 128.35 (s),
127.54 (s), 127.02 (s), 126.33 (s), 94.60 (s), 91.87 (s), 85.21 (s),
+
m, 850 m, 716 s, 693 s. ESI-MS: m/z calcd. for C H OP (M+H) :
6
45
38
25.2655. Found: 625.2658.
Synthesis of Complex [RuCl {(η -p-cymene)PPh -NHAr*}-κ -
6
1
31
1
83.86 (s), 53.06 (s), 48.74 (s), 21.42 (s). P{ H} NMR (202 MHz,
2
2
6
−1
P] (3). A solution of [Ru(η -p-cymene)Cl ] (0.015 g, 0.024 mmol) in
CDCl ): δ 64.3 (s). FT−IR (KBr disk, cm ): 3056 m, 3035 w, 2961
2
2
3
dichloromethane (8 mL) was added, dropwise, to a solution of 1 (0.03
g, 0.048 mmol) also in dichloromethane (7 mL). The reaction mixture
was stirred at room temperature for 4 h, and the solvent was removed
under reduced pressure; the residue obtained was washed with
petroleum ether (1 × 10 mL) to remove free p-cymene and dried
under vacuum to give 3 as a red solid. Single crystals of 3, suitable for
X-ray studies, were grown from a (1:1) mixture of dichloromethane
and petroleum ether over 24 h. Yield 89.6% (0.040 g). mp = 220−223
m, 2921 w, 1437 m, 1348 w, 1260 m, 1098 m, 1030 w, 802 m, 701 s.
ESI-MS: m/z calcd. for C H ClNPRu (M−C1) : 760.1477. Found:
+
45
38
760.1474.
1
Synthesis of Complex [RuCl (PPh -OAr*)-κ -P] (6). Com-
2
2
pound 6 was prepared according to the procedure described for 5 on
the same scale and isolated as an orange-red crystalline solid. A 1:1
solution (dichloromethane and petroleum ether) of 6 stored at room
temperature for 24 h gave X-ray-quality crystals of 6 as an orange-red
crystalline solid. Yield 78.4% (0.02 g). mp = 253−255 °C (dec). Anal.
Calcd for C H OPRuCl : C, 67.84; H, 4.68. Found: C, 67.92; H,
°
C (dec). Anal. Calcd for C H Cl NPRu·CH Cl : C, 66.27; H, 5.36;
55 52 2 2 2
1
N, 1.38. Found: C, 66.38; H, 5.67; N, 1.57. H NMR (400 MHz,
4
5
37
2
1
CDCl ): δ 7.84−7.74 (m, 4H, ArH), 7.36 (d, J = 7.0 Hz, 2H, ArH),
7
6
4.42. H NMR (500 MHz, CDCl ): δ 8.10−8.07 (m, 2H, ArH), 8.02−
3
3
.29 (d, J = 6.6 Hz, 4H, ArH), 7.07 (s, 12H, ArH), 6.61 (s, 8H, ArH),
7.98 (m, 2H, ArH), 7.48 (s, 4H, ArH), 7.35 (t, J = 7.5 Hz, 3H, ArH),
7.31 (d, J = 7.0 Hz, 2H, ArH), 7.16 (dd, J = 12.8, 6.1 Hz, 5H, ArH),
7.10 (t, J = 7.4 Hz, 3H, ArH), 7.01 (d, J = 7.4 Hz, 2H, ArH), 6.51 (s,
.41 (s, 2H, ArH), 6.15 (s, 2H, Ph CH), 5.25 (d, J = 14.9 Hz, 1H,
2
NH), 4.78 (dd, J = 27.6, 5.8 Hz, 4H, p-cymene), 2.79−2.71 (m, 1H,
(
CH ) CH), 1.98 (s, 3H, ArCH ), 1.89 (s, 3H, ArCH ), 1.13 (d, J =
1H, Ph CH), 6.47−6.41 (m, 2H, ArH), 6.36 (d, J = 11.8 Hz, 2H,
3
2
3
3
2
13
6
6
6
1
1
9
.9 Hz, 6H, (CH ) CH). C NMR (101 MHz, CDCl ): δ 144.49 (s),
ArH), 6.29 (t, J = 6.3 Hz, 1H, η -C H ), 5.74 (d, J = 3.8 Hz, 1H, η -
C H ), 5.24 (t, J = 5.6 Hz, 1H, η -C H ), 5.05 (s, 1H, Ph CH) 4.90 (d,
6 6 6 6 2
J = 5.3 Hz, 1H, η -C H ), 4.31−4.26 (m, 1H, η -C H ), 2.05 (s, 3H,
ArCH ). C NMR (101 MHz, CDCl ) δ 143.30 (s), 142.89 (s),
3
2
3
6 6
6
43.84 (s), 135.08 (s), 134.35 (d, J = 10.5 Hz), 130.77 (s), 129.85 (s),
29.40 (s), 127.81 (s), 127.77 (s), 127.71(s), 125.65 (s), 95.90 (s),
0.54 (s), 86.78 (d, J = 6.1 Hz), 50.41 (s), 30.51 (s), 22.44 (s), 21.49
6
6
6
6
6
6
13
3
3
3
1
1
(
(
1
s), 18.16 (s). P{ H} NMR (202 MHz, CDCl ): δ 57.0 (s). FT−IR
141.22 (s), 140.97 (d, J = 4.5 Hz), 140.64 (s), 138.57 (s), 134.46 (t, J
= 9.7 Hz), 133.63 (s), 133.06 (s), 131.05 (s), 130.67 (d, J = 19.3 Hz),
129.76 (dd, J = 26.9, 8.4 Hz), 129.04 (dd, J = 39.7, 13.9 Hz), 128.84
(d, J = 3.5 Hz), 128.75 (dd, J = 19.4, 9.2 Hz), 128.27 (d, J = 6.9 Hz),
127.51 (s), 126.99 (s), 126.62 (d, J = 13.8 Hz), 126.29 (s), 102.21 (d, J
= 10.8 Hz), 99.34 (d, J = 11.0 Hz), 94.54 (s), 91.82 (s), 85.18 (s),
3
−1
KBr disk, cm ): 3056 w, 3019 w, 2961 m, 2920 m, 2851 w, 1260 m,
099 s, 1030 w, 803 s, 702 s. ESI-MS: m/z calcd. for
+
C H Cl NNaPRu (M+Na) : 952.2159. Found: 952.2331.
5
5
52
2
6
1
Synthesis of Complex [RuCl {(η -p-cymene)PPh -OAr*}-κ -P]
2
2
6
(4). A solution of [Ru(η -p-cymene)Cl ] (0.010 g, 0.016 mmol) in
2 2
8
3.80 (s), 53.02 (s), 48.69 (s), 21.38 (s). 3 P{ H} NMR (202 MHz,
1
1
dichloromethane (9 mL) was added dropwise to a solution of 2 (0.02
g, 0.032 mmol) in the same solvent (6 mL) and the reaction mixture
was stirred at room temperature for 4 h. After the removal of solvent
completely under reduced pressure, the residue obtained was washed
with petroleum ether (2 × 5 mL) to remove the free p-cymene and the
residue was dried under vacuum to give compound 4 as a red solid.
Yield 77.2% (0.023 g). mp = 230−233 °C (dec). Anal. Calcd for
C H Cl OPRu·CH Cl : C, 66.21; H, 5.26. Found: C, 66.61; H, 5.05.
−1
CDCl ): δ 118.7 (s). FT−IR (KBr disk, cm ): 3057 w, 2964 m, 2883
3
m, 2852 w, 1454 w, 1433 m, 1262 s, 1112 w, 1004 m, 871 w, 804 m,
+
7
7
36 m, 702 m. ESI-MS: m/z calcd. for C H ClOPRu (M−C1) :
4
5
37
61.1318. Found: 761.1312.
Synthesis of Complex [RuCl (PPh -NHAr*)-κ -P] (5) (Method
1
2
2
6
B). A mixture of 1 (0.024 g, 0.038 mmol) and [Ru(η -p-cymene)Cl ]
2
2
5
5
51
2
2
2
(0.012 g, 0.019 mmol) in chlorobenzene (16 mL) was heated to reflux
for 16 h. The reaction mixture then was allowed to attain room
temperature and was filtered through Celite, and the solvents were
removed under vacuum to give analytically pure product of 5 as an
orange crystalline solid. Yield 86% (0.026 g).
1
H NMR (500 MHz, CDCl ): δ 7.79 (t, J = 8.7 Hz, 4H, ArH), 7.34 (t,
3
J = 7.3 Hz, 3H, ArH), 7.19 (qd, J = 14.5, 7.6 Hz, 15H, ArH), 6.78 (d, J
=
=
1
7.2 Hz, 8H, ArH), 6.52 (s, 2H, ArH), 6.19 (s, 2H, Ph CH), 5.10 (d, J
2
5.7 Hz, 2H, p-cymene), 4.73 (d, J = 5.8 Hz, 2H, p-cymene), 2.89 (m,
1
H, (CH ) CH), 2.02 (s, 3H, ArCH ), 1.17 (d, J = 6.9 Hz, 6H,
Synthesis of Complex [RuCl (PPh -OAr*)-κ -P] (6) (Method
3
2
3
2
2
13
6
(
CH ) CH), 1.09 (s, 3H, p-cymene CH ). C NMR (101 MHz,
B). A mixture of 2 (0.021 g, 0.0336 mmol) and [Ru(η -p-
3
2
3
CDCl ): δ 144.59 (s), 135.94 (s), 134.72 (s), 131.03 (s), 130.81 (s),
cymene)Cl ] (0.010 g, 0.0168 mmol) in chlorobenzene (16 mL)
2 2
3
1
30.16 (s), 129.73 (d, J = 8.3 Hz), 128.23 (s), 127.96 (s), 127.14 (d, J
9.5 Hz), 126.22 (s), 103.82 (s), 100.33 (s), 89.26 (s), 86.47 (s),
was heated to reflux for 16 h. The reaction mixture was cooled to
room temperature and filtered through Celite, and the solvents were
removed under vacuum to give analytically pure product of 6 as an
=
4
9.94 (s), 30.21 (s), 21.99 (s), 21.29 (s), 17.63 (s). 31P{ H} NMR
1
−1
(
3
1
162 MHz, CDCl ): δ 123.9 (s). FT−IR (KBr disk, cm ): 3060 w,
orange-red solid. Yield 82.2% (0.022 g).
3
1
024 w, 2964 m, 2923 m, 2853 w, 1494 w, 1433 m, 1261 m, 1110 s,
Synthesis of [PdCl
2
{(PPh
2
NHAr*)-κ -P}
2
] (7). A solution of
030 w, 871 w, 803 w, 737 s, 703 s. ESI-MS: m/z calcd. for
Pd(COD)Cl
2
(0.0137 g, 0.048 mmol) in dichloromethane (10 mL)
+
C H ClOPRu (M−C1) : 895.2416. Found: 895.2402.
was added dropwise to a solution of 1 (0.06 g, 0.096 mmol) also in
dichloromethane (8 mL) with constant stirring. The reaction mixture
was allowed to be subjected to stirring for 4 h. After removal of solvent
completely under reduced pressure, the residue was obtained as a
yellow solid, which was washed with petroleum ether (2 × 8 mL) and
dried under vacuum to give compound 7 as a yellow crystalline solid.
Yield 76% (0.052 g). mp = 210−212 °C. Anal. Calcd for
C H N P PdCl ·2CH Cl : C, 69.29; H, 5.06; N, 1.76. Found: C,
5
5
51
1
Synthesis of Complex [RuCl (PPh -NHAr*)-κ -P] (5) (Method
2
2
A). A solution of 3 (0.03 g, 0.032 mmol) in chlorobenzene was heated
at 120 °C for 16 h. The resulting solution was filtered through Celite,
washed with diethyl ether (2 × 5 mL), and dried under vacuum to give
analytically pure product of 5 as an orange solid. Crystals suitable for
X-ray analysis were obtained by slow diffusion of dichloromethane into
the petroleum ether solution of 5 at room temperature. Yield 82.5%
9
0
76
2
2
2
2
2
1
(
0.021 g). mp = 262−267 °C (dec). Anal. Calcd for C H Cl NPRu:
68.91; H, 5.14; N, 1.57. H NMR (500 MHz, CDCl ): δ 7.47 (dd, J =
45
38
2
3
1
C, 67.92; H, 4.81; N, 1.76. Found: C, 67.87; H, 4.47; N, 1.80. H
12.6, 5.5 Hz, 4H, ArH), 7.36−7.25 (m, 3H, ArH), 7.14−7.03 (m, 15H,
NMR (500 MHz, CDCl ): δ 8.03−8.01 (m, 2H, ArH), 7.84−7.77 (m,
ArH), 6.54 (d, J = 6.8 Hz, 8H, ArH), 6.36 (s, 2H, ArH), 5.82 (s, 2H,
3
1
3
2
H, ArH), 7.40 (d, J = 6.7 Hz, 3H, ArH), 7.32 (d, J = 7.3 Hz, 1H,
Ph CH), 4.99 (t, J = 6.7 Hz, 1H, NH), 1.98 (s, 3H, ArCH ). C NMR
2
3
I
DOI: 10.1021/acs.inorgchem.8b01095
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
(
126 MHz, CDCl ): δ 143.91 (s), 142.52 (s), 135.19 (s), 134.23 (t, J =
dichloromethane (10 mL) with constant stirring. The reaction mixture
was allowed to be subjected to stirring for 4 h. After removal of solvent
completely under reduced pressure, the residue obtained was washed
with petroleum ether (1 × 10 mL) and dried under vacuum to give 11
as a yellow solid. Single crystals suitable for X-ray diffraction were
3
6
1
5
1
.8 Hz), 130.73 (s), 129.95 (d, J = 12.5 Hz), 128.27 (s), 127.98 (s),
3
1
1
26.10 (s), 51.88 (s), 21.54 (s). P{ H} NMR (202 MHz, CDCl ): δ
3
−1
4.56 (s). FT-IR (KBr disk, cm ): 3324 s, 3053 m, 3023 w, 2960 w,
596 w, 1440 s, 1259 s, 1097 s, 1026 w, 800 s, 697 s. ESI-MS: m/z
+
calcd. for C H Cl KN P Pd (M+K) : 1463.3543. Found: 1463.3505.
grown from a (1:1) mixture of CHCl and petroleum ether over 24 h.
90
76
2
2
2
3
1
Synthesis of [PtCl {(PPh NHAr*)-κ -P} ] (8). A solution of
Yield 83% (0.032 g). mp = 188 °C (dec). Anal. Calcd for
2
2
2
Pt(COD)Cl (0.018 g, 0.048 mmol) in dichloromethane (10 mL) was
C H N P Pd Cl ·CHCl : C, 63.48; H, 4.50; N, 1.62. Found: C,
2
90 76
2
2
2
4
3
1
added dropwise to a solution of 1 (0.06 g, 0.096 mmol) in the same
solvent (15 mL) and stirred for 4 h. After the removal of solvent under
reduced pressure, the residue obtained was washed with petroleum
ether (2 × 6 mL) and dried under vacuum to give 8 as a colorless
crystalline solid. X-ray-quality crystals were grown from a 1:1 mixture
of CH Cl and petroleum ether. Yield 80% (0.058 g). mp = 223−228
64.34; H, 4.50; N, 1.62. H NMR (500 MHz, CDCl ): δ 7.42 (s, 5H,
3
ArH), 7.21 (dd, J = 26.2, 19.9 Hz, 17H, ArH), 6.86 (d, J = 6.3 Hz, 8H,
ArH), 6.46 (s, 2H, ArH), 6.27 (s, 2H, Ph CH), 2.37 (s, 1H, NH), 2.03
2
(s, 3H, ArCH3). 13C NMR (126 MHz, CDCl ): δ 143.45 (s), 142.55
3
(s), 133.69 (t, J = 12.7 Hz), 132.12 (s), 130.47 (s), 130.03 (d, J = 13.3
2
2
Hz), 128.56 (s), 128.53 (s), 128.45 (s), 128.31 (s), 126.60 (s), 116.73
3
1
1
°
C. Anal. Calcd for C H N P PtCl : C, 71.42; H, 5.06; N, 1.85.
Found: C, 71.34; H, 4.88; N, 1.76. H NMR (500 MHz, CDCl ): δ
(s), 52.36 (s), 31.09 (s), 21.62 (s). P{ H} NMR (CDCl ): δ 61.21
90
76
2
2
2
3
1
−1
3
(s). FT-IR (KBr disk, cm ): 2963 m, 1261 s, 1098 s, 1019 m, 863 m,
802 s, 700 m. ESI-MS: m/z calcd. for C H ClNPPd (M+H) :
+
7
1
.50 (d, J = 6.0 Hz, 4H, ArH), 7.32−7.26 (m, 4H, ArH), 7.08 (td, J =
4.2, 6.5 Hz, 14H, ArH), 6.55 (d, J = 7.3 Hz, 8H, ArH), 6.37 (s, 2H,
45
38
764.1473. Found: 764.1406.
1
ArH), 5.87 (s, 2H, Ph CH), 4.95 (s, 1H, NH), 2.01 (s, 3H, ArCH ).
Synthesis of [PdCl {(PPh OAr*)-κ -P}] (12). A solution of
2
3
2 2 2
1
3
C NMR (126 MHz, CDCl ): δ 143.97 (s), 142.71 (s), 134.33 (s),
Pd(COD)Cl (0.010 g, 0.035 mmol) in dichloromethane (5 mL) was
3
2
1
1
33.94 (s), 130.69 (s), 129.90 (s), 129.65 (s), 128.58 (s), 128.03(s),
added dropwise to a solution of 2 (0.022 g, 0.035 mmol) also in
dichloromethane (6 mL), and the clear solution obtained was stirred
for 4 h. After the removal of solvent under reduced pressure, the
residue obtained was washed with petroleum ether (2 × 8 mL) and
dried under vacuum to give 12 as a yellow solid. Single crystals suitable
27.80 (t, J = 5.4 Hz), 126.20 (s), 126.04 (s), 51.80 (s), 21.52 (s).
3
1
1
1
P{ H} NMR (162 MHz, CDCl ): δ 46.00 (s, J = 2611.44 Hz).
3
PtP
−1
FT-IR (KBr disk, cm ): 3250 m, 3053 m, 3023 m, 2960 m, 1631 m,
451 m, 1259 s, 1099 s, 1030 m, 801 s, 699 s. ESI-MS: m/z calcd. for
1
+
C H ClN P Pt (M−C1) : 1477.4831. Found: 1477.4814.
for X-ray diffraction were grown from a 1:1 mixture of CHCl
toluene over 48 h at room temperature. Yield 73.3% (0.022 g). mp =
228−232 °C (dec). Anal. Calcd for C90 Pd Cl ·CHCl : C,
63.42; H, 4.38. Found: C, 63.53; H, 4.78. H NMR (400 MHz,
CDCl ): δ 7.36−7.31 (m, 4H, ArH), 7.23−7.17 (m, 12H, ArH), 7.12
(d, J = 5.0 Hz, 6H, ArH), 7.06 (d, J = 6.8 Hz, 8H, ArH), 6.48 (s, 2H,
3
and
9
0
76
2 2
1
Synthesis of [PdCl {(PPh OAr*)-κ -P} ] (9). A solution of
2
2
2
Pd(COD)Cl (0.014 g, 0.048 mmol) in dichloromethane (15 mL)
H
74
O
2
P
2
2
4
3
2
1
was added dropwise to a solution of 2 (0.06 g, 0.096 mmol) in the
same solvent (12 mL), and the reaction was stirred for 4 h. The
solvent was removed under reduced pressure and the residue obtained
was washed with petroleum ether (1 × 10 mL) dried under vacuum to
give 9 as a yellow solid. Yield 73% (0.050 g). mp = 215−218 °C (dec).
Anal. Calcd for C H O P PdCl : C, 75.76; H, 5.23. Found: C, 75.43;
3
3
1
1
ArH), 6.19 (s, 2H, Ph
(CDCl ): δ 102.60 (s). FT-IR (KBr disk, cm ): 3053 m, 3019 m,
2952 w, 2915 w, 1598 m, 1434 s, 1257 m, 1192 m, 1099 s, 928 m, 800
CH), 2.04 (s, 3H, ArCH ). P{ H} NMR
2
3
−1
3
90
74
2
2
2
1
+
H, 5.02. H NMR (400 MHz, CDCl ): δ 7.23 (m, 2H, ArH), 7.19−
m, 701 s. ESI-MS: m/z calcd. for C90
H74Cl
4
NaO
2
P
2
Pd
2
(M+Na) :
3
7
8
2
1
1
.11 (m, 3H, ArH), 7.07 (d, J = 7.1 Hz, 5H, ArH), 7.01 (t, J = 7.3 Hz,
H, ArH), 6.90 (d, J = 7.3 Hz, 12H, ArH), 6.73 (s, 2H, ArH), 5.69 (s,
H, Ph CH), 2.28 (s, 3H, ArCH ). C NMR (126 MHz, CDCl ): δ
50.98 (s), 143.92 (s), 136.20 (s), 134.23 (s), 133.89 (d, J = 31.3 Hz),
33.68 (d, J = 7.3 Hz), 130.85 (s), 130.46 (s), 129.88 (s), 129.79 (d, J
1627.1894. Found: 1627.1509.
3
1
Synthesis of [PdCl{(η -C
H
)(PPh
5
NHAr*)-κ -P}] (13). A sol-
3
2
13
3
ution of [Pd(η -C H )Cl] (0.012 g, 0.032 mmol) in dichloromethane
2
3
3
3 5 2
(6 mL) was added dropwise to a solution of 1 (0.04 g, 0.062 mmol)
also in dichloromethane (6 mL) and stirred for 4 h. The solvent was
removed under reduced pressure to give compound 13 as a yellow
solid. X-ray-quality crystals were grown from a 1:1 mixture of CH Cl
2
=
22.7 Hz), 127.98 (s), 127.73 (s), 127.44 (s), 127.39 (s), 127.35 (s),
26.04 (s), 51.36 (s), 21.73 (s). 3 P{ H} NMR (162 MHz, CDCl ): δ
1
1
1
1
1
3
2
−
1
00.71 (s). FT-IR (KBr disk, cm ): 3053 m, 3023 m, 2956 w, 1596 w,
436 m, 1255 m, 1196 m, 1116 m, 1097 m, 801 m, 699 s. ESI-MS: m/
and petroleum ether at room temperature over 24 h. Yield 88% (0.044
g). mp = 174 °C (dec.). Anal. Calcd for C H NPPdCl: C, 71.47; H,
48
43
+
1
z calcd. for C H ClO P Pd (M−C1) : 1391.3905. Found:
5.37; N, 1.74. Found: C, 71.53; H, 5.27; N, 1.82. H NMR (500 MHz,
9
0
74
2 2
1
391.3903.
Synthesis of [PtCl {(PPh OAr*)-κ -P} ] (10). A solution of
CDCl ): δ 7.36 (dt, J = 11.4, 7.0 Hz, 6H, ArH), 7.30 (d, J = 6.9 Hz,
3
1
4H, ArH), 7.24−7.16 (m, 12H, ArH), 6.83 (t, J = 6.5 Hz, 8H, ArH),
2
2
2
3
Pt(COD)Cl2 (0.009 g, 0.024 mmol) in dichloromethane (8 mL)
was added dropwise to a solution of 2 (0.03 g, 0.048 mmol) in the
same solvent (9 mL), and the reaction mixture was stirred for 4 h. The
solvent was removed under vacuo to give 10 as white solid. The
product was washed with petroleum ether (1 × 10 mL) to remove the
free cyclooctadiene. The crystals of 10 suitable for X-ray analysis were
obtained by recrystallizing 10 in a 1:1 mixture of dichloromethane and
petroleum ether at room temperature. Yield 85.2% (0.031 g). mp =
6.56 (s, 2H, ArH), 5.69 (s, 2H, Ph CH), 5.17−5.07 (m, 1H, η -C H ),
2
3
5
3
3
4.78 (t, J = 7.5 Hz, 1H, η -C H ), 3.62 (dd, J = 13.5, 10.9 Hz, 1H, η -
3
5
3
C H ), 3.35 (d, J = 4.2 Hz, 1H, NH), 3.03 (d, J = 5.5 Hz, 1H, η -
3
5
3
13
C H ), 2.10 (s, 3H), 1.94 (d, J = 12.2 Hz, 1H, η -C H ). C NMR
3
5
3
5
(126 MHz, CDCl ): δ 143.60 (s), 142.45 (s), 138.20 (s), 136.00 (s),
3
132.64 (s), 130.83 (s), 129.90 (s), 129.89 (d, J = 11.6 Hz), 128.36 (s),
126.54 (s), 117.69 (s), 80.46 (d, J = 31.1 Hz), 56.76 (s), 52.44 (s),
3
1
1
21.79 (s). P{ H} NMR (202 MHz, CDCl ): δ 69.05 (s). FT-IR (KBr
3
−
1
2
6
45−248 °C (dec). Anal. Calcd for C H O P PtCl ·2CH Cl : C,
disk, cm ): 3048 w, 3024 w, 2961 m, 2919 w, 1449 m, 1435 m, 1261
90
74
2
2
2
2
2
1
5.56; H, 4.66. Found: C, 65.44; H, 4.25. H NMR (400 MHz,
s, 1093 m, 1029 m, 802 s, 707 s, 699 s. ESI-MS: m/z calcd. for
+
CDCl ) δ 7.24 (s, 2H, ArH), 7.15 (d, J = 7.4 Hz, 4H, ArH), 7.12−7.06
C H NPPd (M−Cl) : 770.2180. Found: 770.2180.
3
48 43
3
1
(
m, 6H, ArH), 7.02 (t, J = 7.3 Hz, 8H, ArH), 6.90 (d, J = 7.1 Hz, 12H,
Synthesis of [PdCl{(η -C H )(PPh OAr*)-κ -P}] (14). A solution
3 5 2
3
ArH), 6.71 (s, 2H, ArH), 5.72 (s, 2H, Ph CH), 2.28 (s, 3H, ArCH ).
of [Pd(η -C H )Cl] (0.012 g, 0.032 mmol) in dichloromethane (9
2
3
3
5
2
1
3
C NMR (126 MHz, CDCl ): δ 150.64 (s), 143.99 (s), 136.31 (s),
mL) was added, dropwise, to a solution of 2 (0.04 g, 0.062 mmol) also
in dichloromethane (7 mL) with constant stirring. The reaction
mixture was allowed to be subjected to stirring for 4 h. The solvent
was evaporated under reduced pressure to afford 14 as a yellow solid.
Single crystals suitable for X-ray diffraction were grown from a 1:1
mixture of CH Cl and petroleum ether. Yield 72% (0.036 g). mp =
3
1
1
33.70 (s), 130.81 (s), 130.46 (s), 129.86 (s), 127.72 (s), 127.35 (s),
31
1
26.04 (s), 100.15 (s), 51.30 (s), 31.04 (s), 21.73 (s). P{ H} NMR
1
(
162 MHz, CDCl ): δ 90.36 (s, J = 2887.94 Hz). FT-IR (KBr disk,
3 PtP
−1
cm ): 3083 w, 3056 m, 3024 w, 2961 w, 1436 m, 1260 m, 1118 s,
099 s, 1030 w, 801 s, 699 s. ESI-MS: m/z calcd. for
1
2
2
+
C H Cl KO P Pt (M+K) : 1553.3828. Found: 1553.3811.
152 °C (dec.). Anal. Calcd for C H OPPdCl: C, 71.37; H, 5.24;
9
0
74
2
2
2
48 42
1
1
Synthesis of [PdCl {(PPh NHAr*)-κ -P}] (11). A solution of
Found: C, 71.48; H, 5.51. H NMR (500 MHz, CDCl ): δ 7.71−7.62
(m, 4H, ArH), 7.43 (d, J = 6.7 Hz, 2H, ArH), 7.34 (d, J = 5.2 Hz, 4H,
ArH), 7.26 (s, 12H, ArH), 6.95−6.81 (m, 8H, ArH), 6.72 (s, 2H,
2
2
2
3
Pd(COD)Cl (0.013 g, 0.048 mmol) in dichloromethane (8 mL) was
added dropwise to a solution of 1 (0.03 g, 0.048 mmol) also in
2
J
DOI: 10.1021/acs.inorgchem.8b01095
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Inorganic Chemistry
Article
3
ArH), 5.67 (s, 2H, Ph CH), 5.30−5.20 (m, 1H, η -C H ), 4.97 (t, J =
Nixon, J. F.; Laurent, J. C. T. R. B. S. Coordination chemistry of
diphosphinoamine and cyclodiphosphazane ligands. Coord. Chem. Rev.
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2
3
5
3
3
7
.5 Hz, 1H, η -C H ), 3.84−3.76 (m, 1H, η -C H ), 3.07 (d, J = 5.0
3
5
3
5
3
3
Hz, 1H, η -C H ), 2.21 (s, 3H, ArCH ), 2.03 (d, J = 12.2 Hz, 1H, η -
3
5
3
13
C H ). C NMR (126 MHz, CDCl ): δ 151.23 (s), 143.40 (s), 136.04
s), 134.49 (s), 132.65 (s), 132.52 (s), 132.30 (s), 132.16 (s), 131.49
s), 131.28 (s), 130.37 (s), 129.76 (s), 128.43 (s), 128.17 (d, J = 32.0
Hz), 126.38 (s), 118.15 (s), 83.08 (d, J = 32.5 Hz), 56.70 (s), 50.99
3
5
3
(
(
(2) (a) Walker, S. D.; Barder, T. E.; Martinelli, J. R.; Buchwald, S. L.
A Rationally Designed Universal Catalyst for Suzuki−Miyaura
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1
(
s), 21.51(s). P{ H} NMR (CDCl ): δ 132.11 (s). FT−IR (KBr
−1
3
disk, cm ): 3054 w, 3019 m, 2924 m, 2852 w, 1260 w, 1199 w, 1097
m, 1028 w, 875 w, 707 s, 695 s. ESI-MS: m/z calcd. for C H OPPd
48
42
+
(
M−Cl) : 771.2020. Found: 771.2016.
General Procedure for the Catalytic Oxidation of Olefins.
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2
it. NaIO (256 mg, 1.2 mmol) was dissolved in 1 mL of H O and
4
2
transferred to the reaction mixture. The reaction mixture was stirred at
room temperature for ∼15−360 min. The reaction products and
unreacted substrates were analyzed by gas chromatography/mass
spectroscopy (GC/MS). The conversion of the products were
calculated via GC/MS analyses.
ASSOCIATED CONTENT
Supporting Information
■
*
S
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.inorg-
chem.8b01095.
(h) Doherty, S.; Knight, J. G.; McGrady, J. P.; Ferguson, A. M.; Ward,
N. A. B.; Harrington, R. W.; Clegg, W. ortho,ortho′-Substituted
KITPHOS Monophosphines: Highly Efficient Ligands for Palladium-
Catalyzed C−C and C−N Bond Formation. Adv. Synth. Catal. 2010,
NMR and HRMS data for 1−14 (PDF)
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(
52, 201−211.
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Accession Codes
̈
̇
̈ ̈ ̈
z, N.; Ozdemir, I.; Gumgum,
̈
rbu
̧aylak, N.; Yıldırım, L. T. Synthesis and characterization
CCDC 1836869−1836879 contain the supplementary crystal-
lographic data for this paper. These data can be obtained free of
charge via www.ccdc.cam.ac.uk/data_request/cif, or by email-
ing data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, U.K.; fax: + 44 1223 336033.
̈
B.; Ozkar, S.; C
of new (N-diphenylphosphino)-isopropylanilines and their complexes:
crystal structure of (Ph PS)NH−C H −4-CH(CH ) and catalytic
2
6
4
3 2
activity of palladium(II) complexes in the Heck and Suzuki cross-
coupling reactions. Appl. Organomet. Chem. 2010, 24, 17−24.
(b) Poetschke, N.; Nieger, M.; Khan, M. A.; Niecke, E.; Ashby, M.
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AUTHOR INFORMATION
Corresponding Author
■
4
087−4093. (c) Rivard, E.; Lough, A. J.; Manners, I. Synthesis,
characterization and thermolysis of phosphinite-borane adducts:
Investigation of an unusual thermally-induced phenol elimination
reaction. J. Chem. Soc., Dalton Trans. 2002, 2966−2972.
*
Fax:+91-22-5172-3480/2576-7152. E-mail addresses:
krishna@chem.iitb.ac.in, msb_krishna@iitb.ac.in.
ORCID
(4) (a) Iwai, T.; Tanaka, R.; Sawamura, M. Synthesis, Coordination
Maravanji S. Balakrishna: 0000-0003-3736-6148
Notes
The authors declare no competing financial interest.
Properties, and Catalytic Application of Triarylmethane-Mono-
phosphines. Organometallics 2016, 35, 3959−3969. (b) Bottcher, T.;
Jones, C. Extremely bulky secondary phosphinoamines as substituents
for sterically hindered aminosilanes. Dalton Trans. 2015, 44, 14842−
1
4853.
5) Doherty, S.; Knight, J. G.; Addyman, C. R.; Smyth, C. H.; Ward,
ACKNOWLEDGMENTS
■
(
We are grateful to the Science & Engineering Research Board,
New Delhi, for financial support of this work through Grant
No. SB/S1/IC-108/2014. We also thank the Department of
Chemistry, Indian Institute of Technology Bombay, Mumbai,
for instrumentation facilities, as well as spectral and analytical
data. M.K.P. thanks UGC, New Delhi for SRF fellowship.
J.T.M. thanks the Louisiana Board of Regents for the purchase
of the APEX CCD diffractometer, an NSF-MRI grant (No.
N. A. B.; Harrington, R. W. Ruthenium Complexes of κ(P)- and κ(P)-
6
η -Coordinated KITPHOS Monophosphines: Efficient Catalysts for
the Direct Ortho Arylation of 2-Phenylpyridine and N-Phenylpyrazole
with Aryl Chlorides. Organometallics 2011, 30, 6010−6016.
(
6) (a) Ghebreyessus, K. Y.; Nelson, J. H. Base-Promoted
Hydroalkylation Reactions of 1,3,5-Me C H , p-MeC H CHMe ,
3
6
3
6
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C Me , p-MeC H Me, and MeC H Ligands Coordinated to
6
6
6
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Ruthenium(II). Organometallics 2000, 19, 3387−3392. (b) Umeza-
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Synthesis, Characterization, and Thermal Stability of (η :η -
C H CH CH PR )Ru(CH ) (R = Cy, Ph, Et). Organometallics
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