Thioether-functionalized ferrocenyl-bis(phosphonite), Fe{(C 5H4)P(-OC10H6(μ-S)C 10H6O-)}2: Synthesis, coordination behavior, and application in Suzuki-Miyaura cross-coupling reactions

Article abstract of DOI:10.1021/ic701537k

The thioether-functionalized metalloligand ferrocenyl-bis(phosphonite), Fe(C₅H₄PR)₂ (4, R = -OC₁₀H ₆(μ-S)C₁₀H₆O-) is synthesized in three steps starting from ferrocene, and its coordination behavior toward various transition-metal derivatives is described. The reactions of 4 with [Rh(CO) ₂Cl]₂ or M(COD)Cl₂ afforded the chelate complexes, cis-[Rh(CO)Cl{Fe(C₅H₄PR)₂-κP, κP}] (5) or cis-[MCl₂{Fe(C₅H₄PR) ₂-κP,κP}] (6, M = Pd^II; 7, M = Pt ^II), respectively. However, treatment of 4 with CuX (X = Cl, Br, and I) produces binuclear complexes, [Cu₂(μ-X)₂(MeCN) {Fe(C₅H₄-PB)₂-κP,κP}] (B, X = Cl; 9, X = Br; 10, X = I) where the sulfur atom on one side of the ligand is involved in a weak interaction with the copper center. Reaction of 4 with 1 equiv of Ag(PPh₃)OTf gives the mononuclear chelate complex [Ag(OTf)PPh₃{Fe(C₅H₄PR)₂-κP, κP}] (11), whereas treatment with 2 equiv of AuCl(SMe₂) produces the dinuclear gold complex [Au(Cl){Fe(C₅H ₄PR)₂-κP,κP}Au(Cl)] (12). The crystal structures of 10 and 12 are reported, where a strong metallophilic interaction is observed between the closed-shell metal centers. The palladium complex 6 catalyzes the Suzuki cross-coupling reactions of aryl bromides with phenylboronic acid with excellent turnover numbers (TON up to 1.36 × 10⁵).

Full text of DOI:10.1021/ic701537k

Inorg. Chem. 2007, 46, 10268−10275
Thioether-Functionalized Ferrocenyl-bis(phosphonite),
Fe (C5H4)P( OC10H6( -S)C10H6O 2: Synthesis, Coordination Behavior,
{
−
µ
−)}
and Application in Suzuki-Miyaura Cross-Coupling Reactions
Benudhar Punji,† Joel T. Mague,‡ and Maravanji S. Balakrishna*,†
Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology Bombay,
Powai, Mumbai 400 076, India, Department of Chemistry, Tulane UniVersity,
New Orleans, Louisiana 70118
Received August 2, 2007
The thioether-functionalized metalloligand ferrocenyl-bis(phosphonite), Fe(C5H4PR)2 (4, R ) −OC10H6(µ-S)C10H6O−)
is synthesized in three steps starting from ferrocene, and its coordination behavior toward various transition-metal
derivatives is described. The reactions of 4 with [Rh(CO)2Cl]2 or M(COD)Cl2 afforded the chelate complexes, cis-
[Rh(CO)Cl
However, treatment of 4 with CuX (X
PR)2-κP, ] (8, X Cl; 9, X Br; 10, X
weak interaction with the copper center. Reaction of 4 with 1 equiv of Ag(PPh3)OTf gives the mononuclear chelate
complex [Ag(OTf)PPh3 Fe(C5H4PR)2-κP, ] (11), whereas treatment with 2 equiv of AuCl(SMe2) produces the
dinuclear gold complex [Au(Cl) Fe(C5H4PR)2-κP, Au(Cl)] (12). The crystal structures of 10 and 12 are reported,
{
Fe(C5H4PR)2-κP,
κP
}
] (5) or cis-[MCl2
Cl, Br, and I) produces binuclear complexes, [Cu2(
I) where the sulfur atom on one side of the ligand is involved in a
{
Fe(C5H4PR)2-κP,
κ
P
}
] (6, M
)
PdII; 7, M
)
PtII), respectively.
Fe(C5H4-
)
µ
-X)2(MeCN)
{
κ
P
}
)
)
)
{
κP}
{
κP}
where a strong metallophilic interaction is observed between the closed-shell metal centers. The palladium complex
6 catalyzes the Suzuki cross-coupling reactions of aryl bromides with phenylboronic acid with excellent turnover
numbers (TON up to 1.36
×
105).
Introduction
cenyl-phosphines such as monophosphines,4 diphosphines
(1,1′-, 1,2-, 1,3-disubstitution),5 polyphosphines6 with dif-
ferent steric and electronic properties, and also chiral
ferrocenyl ligands7 have been well-studied and have shown
good catalyst activity. In contrast, the readily modifiable
ferrocenyl-phosphonite or -phosphite derivatives have been
much-less explored although they offer an attractive alterna-
tive to ferrocenyl-phosphine ligands. Recently, Reetz and co-
workers and Pastor and co-workers have reported8 the
Metal-containing ligands, particularly those based on the
ferrocene scaffold, have played important roles in catalysis
and material science1 and also in medicinal applications.2
Ferrocenyl-phosphine ligands are able to form complexes
with transition metals in a variety of coordination geometries
and oxidation states, which have proven to be efficient
catalysts for many organic transformations.3 Several ferro-
* To whom correspondence should be addressed. E-mail: krishna@
chem.iitb.ac.in, Tel.: + 91 22 2576 7181, Fax: + 91 22 2576 7152/2572
3480.
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‡ Tulane University.
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10268 Inorganic Chemistry, Vol. 46, No. 24, 2007
10.1021/ic701537k CCC: $37.00
© 2007 American Chemical Society
Published on Web 10/19/2007

Suzuki-Miyaura Cross-Coupling Reactions
Scheme 1
synthesis of ferrocenyl-bis(phosphonites) containing sterically
congested BINOL and tetralkyl-substituted dibenzo[d,f]-
[1,3,2]-dioxaphosphepin ring systems, which are highly
efficient catalysts in hydrogenation and cross-coupling reac-
tions.
catalytic properties. In view of this and as a part of our
interest in designing new inexpensive ligands and studying
their coordination behavior12 and catalytic applications,13 we
report on the synthesis and characterization of a new type
of mixed P,S-ferrocenyl ligand and its coordination behavior
toward various transition-metal derivatives. The palladium-
(II) complex of this ligand exhibits excellent catalytic activity
in the Suzuki-Miyaura cross-coupling reaction.
Ferrocenyl-bis(phosphines) or -bis(phosphonites) contain-
ing hemilabile backbones such as P,N-4c,9 P,O-4a,b,10
compounds have been found to show high activity in several
catalytic processes, and their reactivity offers interesting
structural possibilities. Despite the considerable current
interest in the chemistry of mixed-donor ferrocenyl functional
ligands and the catalytic properties of their metal complexes,
there are very few reports of ferrocene-based P,S-donor
ligands.11 In our recent work on mesocyclic-thioether-
phosphonites, we observed sulfur f phosphorus coordination
that influences the coordinating ability and also the geometry
of the phosphorus atoms. In this context, we sought to make
more derivatives to examine their coordination behavior and
Results and Discussions
Ligand Synthesis. The bis(diethylamino)chlorophosphine,
(Et2N)2PCl (1), was prepared from the reaction of PCl3 with
4 equiv of diethylamine at -20 °C by a modification of the
published procedure.14 The ferrocenyl derivatives Fe(C5H4P-
(NEt2)2)2 (2) and Fe(C5H4PCl2)2 (3) were also prepared in
improvedyieldbyamodificationofthepublishedprocedure.8a,15
The ferrocenyl-bis(phosphonite), Fe(C5H4PR)2 (R ) -OC10H6-
(µ-S)C10H6O-) (4), was synthesized by the reaction of
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Inorganic Chemistry, Vol. 46, No. 24, 2007 10269

Punji et al.
Figure 1. Molecular structure of 10. For clarity, all of the hydrogen atoms have been omitted.
Figure 2. (a) Molecular structure of 12. For clarity, all of the hydrogen atoms have been omitted. (b) Core view of 12 showing Au-Au aurophillic
interaction.
thiobis(2,2′-naphthol) with 3 in the presence of an excess of
triethylamine at -15 °C (Scheme 1). Bisphosphonite 4 is a
dark-orange colored solid, which is moderately stable in air.
The 31P NMR spectrum of 4 consists of a singlet at 175.2
ppm, and the H NMR spectrum shows two broad singlets
at 4.83 and 4.77 ppm for the protons of the ferrocenyl group.
phosphorus atoms rather than to chlorine.16 The 31P NMR
spectrum of 5 shows two doublets centered at 180.1 and
140.2 ppm due to the presence of two magnetically non-
1
equivalent phosphorus atoms. The corresponding JRhP
1
coupling constants are 177 and 145 Hz, respectively. The
2JPP coupling constant is 33 Hz. Because the carbon
monoxide is a good π acceptor, the upfield shift at δ 140.2
(1JRh-P ) 145 Hz) is assigned to the phosphorus atom trans
to the carbon monoxide, and the downfield shift at δ 180.1
(1JRhP ) 177 Hz) is assigned to the phosphorus atom trans
Metal Complexes. The reaction of ferrocenyl-bis(phos-
phonite) 4 with [Rh(CO)2Cl]2 in a 2:1 molar ratio gives the
mononuclear chelate complex, cis-[Rh(CO)Cl{Fe(C5H4PR)2-
κP,κP}] (5), in good yield. The IR spectrum of 5 shows a
strong CO absorption at 2031 cm-1, which clearly indicates
the trans disposition of the CO ligand to one of the
(16) van den Beuken, E. K.; de Lange, W. G. J.; van Leeuwen, P. W. N.
M.; Veldman, N.; Spek, A. L.; Feringa, B. L. J. Chem. Soc., Dalton
Trans. 1996, 3561-3569.
10270 Inorganic Chemistry, Vol. 46, No. 24, 2007

Suzuki-Miyaura Cross-Coupling Reactions
1
Table 1. Crystallographic Data for 10 and 12
satellite peaks with a JPtP coupling of 4476 Hz. This high
value of the Pt-P coupling constant signifies the mutual cis
10
12
orientation of the phosphorus atoms around the platinum
center. In the H NMR spectra, two broad singlets are
observed in the region 4.47-4.75 ppm for the ferrocenyl
protons in both of the complexes.
formula
fw
cryst syst
cryst size (mm3)
space group
a (Å)
C
50H32I2O4P2S2FeCu2.(MeCN)2
C
50H32Au2Cl2FeO4P2S2
1
1341.7
1343.5
triclinic
0.06 × 0.08 × 0.13
P1h (No. 2)
11.356(1)
12.034(1)
19.243(2)
86.241(1)
77.666(1)
74.859(1)
2479.7(4)
2
1.810
2.585
1327
100
2.0, 28.4
1.04
0.0450
monoclinic
0.08 × 0.12 × 0.12
C2/c (No. 15)
18.585(1)
9.683(6)
24.923(2)
90
103.520(1)
90
4360.7(5)
4
2.046
7.380
2576
100
2.3, 28.3
1.08
0.0330
The reaction of bis(phosphonite) 4 with an excess of CuX
(X ) Cl, Br, I) in a dichloromethane/acetonitrile mixture
afforded the halide-bridged binuclear complexes, [Cu2(µ-X)2-
(MeCN){Fe(C5H4PR)2-κP,κP}] (8, X ) Cl; 9, X ) Br; 10,
X ) I) in good yield as dark-orange crystals. The 31P NMR
spectra of 8-10 show at room temperature as well as at
0 °C only broad singlets at 139.6, 139.3, and 138.4 ppm,
respectively. The 1H NMR spectra show two singlets in the
region 4.97-5.26 ppm for the ferrocenyl protons and sharp
singlets around 2.07-2.49 ppm for the protons of a
coordinated acetonitrile ligand. Although the X-ray structure
of 10 shows two different environments for copper atoms,
the 31P NMR data suggests that the acetonitrile probably does
disrupt the thioether-copper interaction and that it does so
very rapidly on the NMR time scale and exchanges itself
between the two copper centers. Similarly, treatment of 4
with 1 equiv of Ag(PPh3)OTf afforded the mononuclear
chelate complex [Ag(OTf)PPh3{Fe(C5H4PR)2-κP,κP}] (11).
The 31P NMR spectrum of 11 shows two doublets centered
at 162.4 ppm with Ag-P couplings of 361 (1J(109AgP)) and
312 Hz (1J(107AgP)) for the phosphonite phosphorus and a
broad singlet at 11.6 ppm for PPh3. The resonance for the
PPh3 group was too broad to obtain values for couplings
with the 107Ag and 109Ag nuclei. The dinuclear gold complex
[Au(Cl){Fe(C5H4PR)2-κP,κP}Au(Cl)] (12) was obtained by
the reaction of 4 with 2 equiv of AuCl(SMe2) in dichlo-
romethane at room temperature. The 31P NMR spectrum of
12 shows a singlet at 142.7 ppm, and the 1H NMR spectrum
shows two singlets at 5.50 and 5.31 ppm for the ferrocenyl
protons. The proposed formulations for the complexes
described above are further supported by elemental analyses
and by single-crystal structure determinations for 10 and 12.
Molecular Structures of 10 and 12. Perspective views
of the molecular structures of 10 and 12 with atom-
numbering schemes are shown in Figures 1 and 2, respec-
tively. The crystallographic data and the details of the
structure determinations are given in Table 1 and selected
bond lengths and bond angles are listed in Table 2.
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å 3)
Z
F
calcd (g cm-3
)
µ (Mo KR), (mm-1
F (000)
)
T (K)
θ
min-max (deg)
GOF (F 2)
R1a
wR2b
0.1024
0.0756
a R1 ) ∑|Fo| - |Fc|/∑|Fo|. b wR2 ) {∑w[(Fo2 - Fc )2]/∑[w(Fo )2]}1/2
.
2
2
Table 2. Selected Bond Distances (Angstroms) and Bond Angles
(Degrees) for 10 and 12
10
12
I1-Cu1
I1-Cu2
I2-Cu1
I2-Cu2
Cu1-P1
Cu2-P2
Cu2-N1
Fe-C41
Fe-C42
Fe-C43
Fe-C44
Fe-C45
P1-C41
P2-C46
Cu1...S1
2.581(7)
2.723(7)
2.565(7)
2.686(7)
2.185(1)
2.218(1)
1.994(4)
2.028(5)
2.044(5)
2.053(6)
2.056(6)
2.032(5)
1.773(4)
1.772(5)
2.979(1)
Au-Cl
Au-P
2.284(1)
2.202(1)
2.044(4)
2.049(5)
2.049(5)
2.054(5)
2.042(5)
1.608(3)
1.610(3)
1.755(4)
1.792(4)
1.783(6)
Fe-C21
Fe-C22
Fe-C23
Fe-C24
Fe-C25
P-O1
P-O2
P-C21
S-C2
S-C12
Cu1-I1-Cu2
Cu1-I2-Cu2
I1-Cu1-I2
I1-Cu1-P1
I2-Cu1-P1
I1-Cu2-I2
I1-Cu2-P2
I1-Cu2-N1
I2-Cu2-P2
P2-Cu2-N1
C41-Fe-C42
C41-Fe-C43
C41-Fe-C47
C41-Fe-C50
Cu1-P1-C41
O2-P1-C41
O1-P1-C41
Cu2-P2-C46
O3-P2-C46
O4-P2-C46
60.91(2)
61.61(2)
108.55(2)
117.87(4)
132.52(4)
101.15(2)
122.37(4)
98.12(1)
110.34(4)
112.76(1)
41.36(2)
68.54(2)
108.57(2)
164.70(18)
116.13(2)
102.17(2)
98.28(2)
126.61(2)
96.5(2)
Cl-Au-P
170.95(4)
40.75(2)
68.29(2)
C21-Fe-C22
C21-Fe-C23
C21-Fe-C25i
C21-Fe-C22i
Au-P-O1
111.73(2)
164.08(2)
111.76(1)
116.27(1)
119.71(1)
100.66(2)
105.19(2)
99.23(2)
Au-P-O2
Au-P-C21
O1-P-C21
O1-P-O2
C2-S-C12
10 is dinuclear with both the iodine atoms and the bis-
(phosphonite) ligand bridging the two copper atoms. One
of the copper atoms is tetra-coordinated, being bound to one
phosphorus atom, two iodine atoms, and one acetonitrile
ligand. The other copper atom is best considered to be pseudo
tetra-coordinated because, in addition to coordination by the
other phosphorus atom and the two iodine atoms, there is a
weak interaction with the sulfur atom as indicated by the
S1‚‚‚Cu1 distance (2.979(1) Å), which is less than the sum
of the van der Waals radii for copper and sulfur (3.20 Å).17
The Cu2I2 core adopts a butterfly shape with the iodine atoms
at the wing tips, as indicated by the Cu-I-Cu angles [Cu1-
97.96(2)
to the chlorine.16 Treatment of ligand 4 with M(COD)Cl2
(M ) PdII or PtII) in dichloromethane produce the complexes,
[MCl2{Fe(C5H4PR)2-κP,κP}] (6, M ) PdII; 7, M ) PtII).
Palladium 6 was precipitated out within 20 min from the
reaction solution, whereas platinum 7 was crystallized from
the reaction solution at room temperature. The 31P NMR
spectra of 6 and 7 show single resonances at 94.8 and 76.7
ppm, respectively, with the platinum complex showing
(17) Bondi, A. J. Phys. Chem. 1964, 68, 441-451.
Inorganic Chemistry, Vol. 46, No. 24, 2007 10271

Punji et al.
Table 3. Suzuki Cross-Coupling of Aryl Halides with Phenyl Boronic Acida
a Aryl halide (0.5 mmol), phenyl boronic acid (0.75 mmol), K2CO3 (1 mmol), MeOH (5 mL), at 60 °C. b Conversion to coupled product determined by
GC, based on aryl halides; average of two runs.
I1-Cu2 ) 60.91(2); Cu1-I2-Cu2 ) 61.61(2)°]. The four
Cu-I bond lengths (Table 2) differ significantly from one
another with each copper atom forming a long and a short
Cu-I bond. The distance between the two copper centers is
2.691 Å, which indicates the presence of a ligand-supported
Cu‚‚‚Cu interaction.18 The Cu-P bond lengths (Cu1-P1 )
2.185(1), Cu2-P2 ) 2.218(1) Å) are slightly shorter than
the corresponding distances observed in the analogous
complex, [Cu(µ-I)(dppf-P,P′)]2 (Cu-P ) 2.28(1), 2.286(8)
Å), where dppf chelates the copper centers.19 The bond angles
around Cu(1) and Cu(2) range from 108.55(2) to 132.52(4)
and 98.13(1) to 122.37(4)°, respectively, indicating the
distorted-tetrahedral environment around copper. One of the
eight-membered rings containing phosphorus and sulfur is
in an anti chairlike conformation, where the sulfur atom
remains away from the copper center, whereas the other
eight-membered ring is in a syn boatlike conformation, and
its sulfur atom shows a coordinative interaction toward the
copper center. Previously, binuclear copper iodide complexes
ofbis(phosphine)scrystallizedfromsolventsystemscontaining
acetonitrile generally have been found to adopt tetrahedral
geometries at both copper centers due to the coordination
of acetonitrile at both metals.20 However, in this complex,
the coordinative interaction of one thioether moiety with the
adjacent copper atom is evidently strong enough to prevent
displacement by acetonitrile.
12 has crystallographically imposed 2-fold rotation sym-
metry with the 2-fold axis passing through the iron atom
and the midpoint of the Au1-Au2 vector. The bis(phos-
phonite) ligand coordinates the metal centers in an open
bridging mode with Au-P and Au-Cl bond distances of
2.202(1) and 2.284(1) Å, respectively, which are close to
those found in the similar structure of [Au2Cl2(µ-dppf)]
(Au-P ) 2.226(1) and Au-Cl ) 2.282(1) Å).21 The
P-Au-Cl bond angle, 170.95(4)°, is significantly distorted
from the expected linear geometry. This may be due to
packing interactions because the chlorine atom makes
contacts of 2.61 Å with H23 (at -x, -1 + y, 1/2 - z) and of
2.69 Å with H15 (at -x, 1 - y, -z), both of which would
be even shorter were the angle to be more linear. The
cyclopentadienyl rings adopt an eclipsed conformation. Both
the eight-membered rings containing phosphorus and sulfur
are in an anti chairlike conformation, where the sulfur atom
remains too far from the gold centers for there to be any
sulfur-to-gold interactions. This contrasts with what was
found previously for complexes of related bis(phosphonite)
ligands,12d,13e where these eight-membered rings adopted syn
boat conformations. The shortest Fe-Au distance is 4.179
Å, indicating that there is no Fe- - -Au interaction. Both of
the gold centers are on same side, and there appears to be
an aurophilic interaction because the Au‚‚‚Au contact
distance is 3.175 Å, which falls within the range of Au-Au
distances (2.7-3.7 Å) reported for several gold complexes.22
These metallophilic interactions in 10 and 12 are due to the
(18) (a) Pyykko, P. Chem. ReV. 1997, 97, 597-636. (b) Mehrotra, P. K.;
Hoffmann, R. Inorg. Chem. 1978, 17, 2187-2189.
(19) Neo, S. P.; Zhou, Z.; Mak, T. C. W.; Andy Hor, T. S. J. Chem. Soc.,
Dalton Trans. 1994, 3451-3458.
(21) Canales, F.; Gimeno, M. C.; Jones, P. G.; Laguna, A.; Sarroca, C.
Inorg. Chem. 1997, 36, 5206-5211.
(22) Schmidbaur, H. Gold Bull. 2000, 33, 3-10.
(20) Ganesamoorthy, C.; Balakrishna, M. S.; George, P. P.; Mague, J. T.
Inorg. Chem. 2007, 46, 848-858.
10272 Inorganic Chemistry, Vol. 46, No. 24, 2007

Suzuki-Miyaura Cross-Coupling Reactions
Scheme 2
phonite) forms chelate complexes with rhodium(I), paladium-
(II), and platinum(II) metals, whereas with copper(I) deriva-
tives, bridged binuclear complexes are obtained. In these
binuclear copper complexes, one of the copper centers is
coordinated to the sulfur in the ligand backbone, whereas
an acetonitrile ligand occupies the corresponding coordina-
tion site on the other copper center. Both binuclear complexes
10 and 12 show strong metallophilic interactions between
the closed-shell metal centers, which make them ideal
candidates for luminescence studies. The palladium complex
of the ferrocenyl-bis(phosphonite) is an effective catalyst for
the Suzuki cross-coupling reaction (TON up to 1.36 × 105)
and is found to be superior to most of the commonly used
catalysts. The catalytic activity of this palladium complex
toward aryl chlorides and other coupling reactions (e.g., Heck
cross-coupling, amination reactions) of different aryl halides
is under progress in our laboratory and will be reported in
due course.
Experimental Section
combination of correlation and relativistic effects with added
ionic contributions.18a,23
All of the experimental manipulations were carried out under
an atmosphere of dry nitrogen or argon using Schlenk techniques.
Solvents were dried and distilled prior to use by conventional
methods. Bis(2-hydroxy-1-napthyl)sulfide,26 (Et2N)2PCl,14 [Rh-
(CO)2Cl]2,27 M(COD)Cl2, (M ) Pd, Pt),28 CuX (X ) Cl, Br),29
Ag(PPh3)OTf,30 and AuCl(SMe2)31 were prepared according to the
published procedures. Other reagents were obtained from com-
Suzuki Cross-Coupling Reactions using Palladium
Complex. The palladium complex 6 catalyzes the cross-
coupling reactions of aryl bromides and phenylboronic acid,
to yield the desired biaryls in high yields at 60 °C using
methanol as solvent (Table 3). Only electron-poor, highly
reactive aryl bromides were investigated containing electron-
withdrawing π-acceptor substituents in the para position.
Using these catalysts, high yields are maintained from
catalyst loadings of 0.05 to 0.0005 mol%. In the case of the
coupling of 4-bromobenzonitrile with phenyl boronic acid,
the highest TON observed is 1.36 × 105 (entry 5). The
activity of catalyst 6 is found to be superior to that of the
most commonly used catalysts, PdCl2(dppf) and Pd2(dba)3/
(dppf), which catalyze the reaction between 4-bromoac-
etophenone and phenylboronic acid in toluene at 70 °C in
94 and 86% yields, respectively.24
1
mercial sources and used after purification. The H and 31P{1H}
NMR (δ in ppm) spectra were obtained on a Varian VRX 400
spectrometer operating at frequencies of 400 and 162 MHz,
respectively. The spectra were recorded in CDCl3 (or DMSO-d6)
solutions with CDCl3 (or DMSO-d6) as an internal lock; TMS and
1
85% H3PO4 were used as internal and external standards for H
and 31P{1H} NMR, respectively. Positive shifts lie downfield of
the standard in all of the cases. Infrared spectra were recorded on
a Nicolet Impact 400 FTIR instrument as a KBr disk. Microanalyses
were carried out on a Carlo Erba (Model 1106) elemental analyzer.
Q-Tof Micromass experiments were carried out using Waters Q-Tof
micro(YA-105). Melting points of all of the compounds were
determined on a Veego melting point apparatus and are uncorrected.
GC analyses were performed on a PerkinElmer Clarus 500 GC fitted
with a FID detector and a packed column.
The homogeneous nature of the catalysis was checked by
the classical mercury test. Addition of a drop of mercury to
the reaction mixtures did not affect the activity of the catalyst,
thus showing them to be truly homogeneous systems.25
Synthesis of Bis(diethylamino)chlorophosphine, (Et2N)2PCl
(1). A solution of diethylamine (23.7 mL, 228.9 mmol) in diethyl
ether (70 mL) was added dropwise to a solution of PCl3 (5 mL,
57.2 mmol) in diethyl ether (400 mL) at -20 °C. The solution was
slowly warmed to room temperature and stirred for an additional
12 h. The suspension obtained was filtered through celite to remove
Et2NH‚HCl, and the solvent was removed by distillation. The
resulted yellow liquid was transferred to a small round-bottom flask
and distilled under vacuum to obtain product 1 as a colorless liquid.
Conclusion
The ferrocenyl-bis(phosphonite) containing the hemilabile
thioether-dinaphthyl backbone was synthesized from fer-
rocene and bis(2-hydroxy-1-napthyl)sulfide. Ferrocenyl-bis-
(phosphonite), (4), shows versatile coordination modes
toward various transition-metal derivatives. The bis(phos-
(23) (a) Singh, K.; Long, J. R.; Stavropoulos, P. J. Am. Chem. Soc. 1997,
119, 2942-2943. (b) Siemeling, U.; Vorfeld, U.; Neumann, B.;
Stammler, H.-G. Chem. Commun. 1997, 1723-1724. (c) Poblet, J.
M.; Benard, M. Chem. Commun. 1998, 1179-1180. (d) Sundararaman,
A.; Zakharov, L. N.; Rheingold, A. L.; Jakle, F. Chem. Commun. 2005,
1708-1710.
(26) Mercado, R. M. L.; Chandrasekaran, A.; Day, R. O.; Holmes, R. R.
Organometallics 1999, 18, 906-914.
(27) McCleverty, J. A.; Wilkinson, G. Inorg. Synth. 1990, 28, 84-86.
(28) Drew, D.; Doyle, J. R. Inorg. Synth. 1990, 28, 346-349.
(29) Furniss, B. S.; Hannaford, A. J.; Smith, P. W. G.; Tatchell, A. R.
Vogel’s Textbook of Practical Organic Chemistry, Fifth ed.; ELBS:
England, 1989; pp 428-429.
(30) Bardaji, M.; Crespo, O.; Laguna, A.; Fischer, A. K. Inorg Chim. Acta
2000, 304, 7-16.
(31) Brandys, M. C.; Jennings, M. C.; Puddephatt, R. J. J. Chem. Soc.,
Dalton Trans. 2000, 4601-4606.
(24) Colacot, T. J.; Qian, H.; Cea-Olivares, R.; Hernandez-Ortega, S. J.
Organomet. Chem. 2001, 637-639, 691-697.
(25) (a) Widegren, J. A.; Bennett, M. A.; Finke, R. G. J. Am. Chem. Soc.
2003, 125, 10301-10310. (b) Widegren, J. A.; Finke, R. G. J. Mol.
Catal. A: Chem. 2003, 198, 317-341.
Inorganic Chemistry, Vol. 46, No. 24, 2007 10273

Punji et al.
Yield: 73% (17.6 g). 1H NMR (400 MHz, CDCl3): δ 3.17 (quartet,
8H, CH2), 1.14 (t, 12H, CH3). 31P{1H} NMR (162 MHz, CDCl3):
δ 158.7 (s).
stirred for 30 min. The orange-colored precipitate formed was
filtered off and dried under vacuum. Yield: 83% (0.091 g). Mp:
172-174 °C (dec). Anal. Calcd for C50H32Cl2O4P2S2FePd: C,
1
56.87; H, 3.05; S, 6.07. Found: C, 56.79; H, 2.99; S, 6.01. H
Synthesis of Fe{C5H4P(NEt2)2}2 (2). A mixture of n-BuLi (37
mL, 59.1 mmol, 1.6 M in hexane) and TMEDA (5.85 mL, 59.1
mmol) in n-hexanes (30 mL) was added dropwise to a solution of
ferrocene (5 g, 26.9 mmol) also in n-hexanes (120 mL) at room
temperature. After stirring for 12 h, (Et2N)2PCl (11.3 g, 53.8 mmol)
in THF (40 mL) was added dropwise to the resulting orange-colored
suspension at -78 °C. The reaction mixture was warmed to room
temperature and stirred for an additional 10 h. The suspension
obtained was filtered through celite to remove LiCl. The solution
was concentrated to dryness to give a pasty crude product of 2.
Yield: 80% (11.5 g). 1H NMR (400 MHz, CDCl3): δ 4.82 (s, 4H,
3
NMR (400 MHz, DMSO-d6): δ 8.51 (d, 4H, Ar, JHH ) 8.0 Hz),
3
3
7.73 (d, 8H, Ar, JHH ) 8.8 Hz), 7.39 (t, 4H, Ar, JHH ) 7.2 Hz),
3
3
7.24 (t, 4H, Ar, JHH ) 7.6 Hz), 7.18 (d, 4H, Ar, JHH ) 9.2 Hz),
4.52 (br s, 4H, Fc), 4.47 (br s, 4H, Fc). 31P{1H} NMR (162 MHz,
DMSO-d6): δ 94.8 (s).
Synthesis of [PtCl2{Fe(C5H4PR)2-κP,κP}] (7). A solution of
Pt(COD)Cl2 (0.03 g, 0.08 mmol) in dichloromethane (6 mL) was
added dropwise to a dichloromethane (10 mL) solution of 4 (0.07
g, 0.08 mmol), and the reaction mixture was stirred for 3 h. The
solution was concentrated and layered with petroleum ether (1 mL),
which gave a crystalline product (7) on slow evaporation. Yield:
85% (0.078 g). Mp: 216-218 °C (dec). Anal. Calcd for C50H32-
Cl2O4P2S2FePt: C, 52.46; H, 2.82; S, 5.60. Found: C, 52.39; H,
2.78; S, 5.57. 1H NMR (400 MHz, DMSO-d6): δ 8.52 (d, 4H, Ar,
3
Fc), 4.76 (s, 4H, Fc), 3.14 (quartet, 16H, CH2, JHH ) 7.0 Hz),
3
1.11 (t, 24H, CH3, JHH ) 7.0 Hz). 31P{1H} NMR (162 MHz,
CDCl3): δ 88.7 (s).
Synthesis of Fe{C5H4PCl2}2 (3). A solution of 2 (11.0 g, 20.6
mmol) in diethyl ether (250 mL) was cooled to -78 °C and
saturated with anhydrous HCl(g) for 2 h with continuous stirring.
The reaction mixture was then allowed to warm to room temperature
and was stirred for an additional 12 h. The resulted suspension
was filtered through celite to remove Et2NH‚HCl. The solvent was
evaporated under vacuum to obtain product 3 as an orange-colored
3
3JHH ) 8.8 Hz), 7.73 (d, 8H, Ar, JHH ) 8.8 Hz), 7.39 (t, 4H, Ar,
3
3JHH ) 7.6 Hz), 7.23 (t, 4H, Ar, JHH ) 7.6 Hz), 7.19 (d, 4H, Ar,
3JHH ) 8.4 Hz), 4.75 (br s, 4H, Fc), 4.49 (br s, 4H, Fc). 31P{1H}
1
NMR (162 MHz, DMSO-d6): δ 76.7 (s), JPtP ) 4476 Hz.
Synthesis of [Cu2(µ-Cl)2(MeCN){Fe(C5H4PR)2-κP,κP}] (8). A
solution of CuCl (0.032 g, 0.323 mmol) in acetonitrile (5 mL) was
added dropwise to a solution of 4 (0.071 g, 0.081 mmol) in
dichloromethane (10 mL) at room temperature, and the reaction
mixture was stirred for 3 h. The solution obtained was concentrated
under vacuum to give a yellow-colored crystalline product (8) upon
standing at room temperature. Yield: 79% (0.071 g). Mp: 168-
170 °C (dec). Anal. Calcd for C52H35Cl2NO4P2S2FeCu2: C, 55.87;
H, 3.16; N, 1.25; S, 5.74. Found: C, 55.79; H, 3.08; N, 1.21; S,
1
solid. Yield: 92% (7.34 g). H NMR (400 MHz, CDCl3): δ 4.72
(s, 8H, Fc). 31P{1H} NMR (162 MHz, CDCl3): δ 160.7 (s).
Synthesis of Fe(C5H4PR)2 (4, R ) -OC10H6(µ-S)C10H6O-).
A solution of 3 (1 g, 2.58 mmol) in THF (30 mL) was added
dropwise to the mixture of bis(2-hydroxy-1-napthyl)sulfide (1.64
g, 5.16 mmol) and Et3N (1.62 mL, 11.6 mmol) in THF (50 mL) at
-15 °C. The reaction mixture was warmed to room temperature
and stirred for 12 h. The solvent was removed under vacuum, and
the residue obtained was redissolved in toluene (20 mL) and filtered
through celite to remove Et3N‚HCl. The orange-colored solution
obtained was concentrated to a small volume and cooled to
-25 °C to give an analytically pure product of 4 as orange crystals.
Yield: 77% (1.75 g). Mp: 168-170 °C. Anal. Calcd for
C50H32O4P2S2Fe: C, 68.34; H, 3.67; S, 7.29. Found: C, 68.29; H,
1
3
5.68. H NMR (400 MHz, DMSO-d6): δ 8.77 (d, 4H, Ar, JHH
)
8.0 Hz), 8.00 (d, 8H, Ar, 3JHH ) 8.4 Hz), 7.35-7.71 (m, 12H, Ar),
5.25 (s, 4H, Fc), 4.98 (s, 4H, Fc), 2.49 (s, 3H, CH3CN). 31P{1H}
NMR (162 MHz, DMSO-d6): δ 139.6 (s).
Synthesis of [Cu2(µ-Br)2(MeCN){Fe(C5H4PR)2-κP,κP}] (9).
This was synthesized by the procedure similar to that for 8, using
CuBr (0.04 g, 0.278 mmol) and 4 (0.061 g, 0.069 mmol). Yield:
74% (0.062 g). Mp: 220-222 °C (dec). Anal. Calcd for C52H35-
Br2NO4P2S2FeCu2: C, 51.76; H, 2.92; N, 1.16; S, 5.31. Found: C,
51.71; H, 2.89; N, 1.13; S, 5.29. 1H NMR (400 MHz, DMSO-d6):
δ 7.92 (d, 4H, Ar, 3JHH ) 8.0 Hz), 7.14 (t, 8H, Ar, 3JHH ) 9.2 Hz),
1
3.63; S, 7.22. H NMR (400 MHz, CDCl3): δ 8.79 (d, 4H, Ar,
3
3JHH ) 8.4 Hz), 7.75 (d, 4H, Ar, JHH ) 8.0 Hz), 7.70 (d, 4H, Ar,
3
3JHH ) 8.8 Hz), 7.59 (t, 4H, Ar, JHH ) 7.2 Hz), 7.41 (t, 4H, Ar,
3
3JHH ) 7.2 Hz), 7.20 (d, 4H, Ar, JHH ) 9.2 Hz), 4.83 (br s, 4H,
Fc), 4.77 (br s, 4H, Fc). 31P{1H} NMR (162 MHz, CDCl3): δ 175.2
(s).
6.68-6.86 (m, 8H, Ar), 6.49 (d, 4H, Ar, JHH ) 8.4 Hz), 4.89 (s,
3
4H, Fc), 4.43 (s, 4H, Fc), 2.50 (s, 3H, CH3CN). 31P{1H} NMR
(162 MHz, DMSO-d6): δ 139.3 (s).
Synthesis of [Rh(CO)Cl{Fe(C5H4PR)2-κP,κP}] (5). A solution
of 4 (0.068 g, 0.077 mmol) in THF (10 mL) was added dropwise
to a solution of [Rh(CO)2Cl]2 (0.015 g, 0.039 mmol) also in THF
(5 mL) at room temperature, and the reaction mixture was stirred
for 2 h. The orange-colored solution obtained was concentrated,
and petroleum ether (6 mL) was added to precipitate out an orange-
colored product, which was then filtered off and dried under
vacuum. Yield: 90% (0.072 g). Mp: 182 °C (dec). Anal. Calcd
for C51H32ClO5P2S2FeRh: C, 58.61; H, 3.09; S, 6.14. Found: C,
58.57; H, 3.05; S, 6.09. IR (KBr disc, cm-1): νCO, 2031. 1H NMR
Synthesis of [Cu2(µ-I)2(MeCN){Fe(C5H4PR)2-κP,κP}] (10).
This was synthesized by the procedure similar to that for 8, using
CuI (0.06 g, 0.315 mmol) and 4 (0.069 g, 0.079 mmol). Yield:
81% (0.083 g). Mp: 208-210 °C (dec). Anal. Calcd for C52H35I2-
NO4P2S2FeCu2: C, 48.02; H, 2.71; N, 1.08; S, 4.93. Found: C,
47.98; H, 2.65; N, 1.04; S, 4.83. 1H NMR (400 MHz, DMSO-d6):
3
δ 8.74 (d, 4H, Ar, JHH ) 8.4 Hz), 7.96-8.01 (m, 8H, Ar), 7.69
3
3
(t, 4H, Ar, JHH ) 7.2 Hz), 7.53 (t, 4H, Ar, JHH ) 7.2 Hz), 7.36
3
(d, 4H, Ar, JHH ) 8.8 Hz), 5.26 (s, 4H, Fc), 4.99 (s, 4H, Fc),
3
(400 MHz, CDCl3): δ 8.70 (d, 4H, Ar, JHH ) 8.4 Hz), 8.12 (d,
2.07 (s, 3H, CH3CN). 31P{1H} NMR (162 MHz, DMSO-d6): δ
138.4 (s).
3
3
4H, Ar, JHH ) 8.4 Hz), 7.91 (d, 4H, Ar, JHH ) 7.2 Hz), 7.29-
7.71 (m, 12H, Ar), 5.07 (br s, 4H, Fc), 4.86 (br s, 4H, Fc). 31P-
{1H} NMR (162 MHz, CDCl3): δ 180.1 (br d, JRhP ) 177 Hz),
140.2 (br d, JRhP ) 145 Hz).
Synthesis of [Ag(OTf)PPh3{Fe(C5H4PR)2-κP,κP}] (11). To a
solution of 4 (0.068 g, 0.077 mmol) in dichloromethane (12 mL),
Ag(PPh3)OTf (0.04 g, 0.077 mmol) was added, and the reaction
mixture was stirred for 4 h. The solution was concentrated and
petroleum ether (5 mL) was added to precipitate the pale-yellow
product, which was then filtered off and dried under vacuum.
Yield: 83% (0.090 g). Mp: 192-194 °C (dec). Anal. Calcd for
1
1
Synthesis of [PdCl2{Fe(C5H4PR)2-κP,κP}] (6). A solution of
Pd(COD)Cl2 (0.03 g, 0.105 mmol) in dichloromethane (6 mL) was
added dropwise to a dichloromethane (10 mL) solution of 4 (0.092
g, 0.105 mmol) at room temperature, and the reaction mixture was
10274 Inorganic Chemistry, Vol. 46, No. 24, 2007

Suzuki-Miyaura Cross-Coupling Reactions
C69H47F3O7P3S3FeAg: C, 59.28; H, 3.39; S, 6.88. Found: C, 59.21;
H, 3.34; S, 6.81. 1H NMR (400 MHz, CDCl3): δ 8.44 (d, 4H, Ar,
3JHH ) 8.8 Hz), 7.25-7.66 (m, 20H, Ar, 15H, PPh3), 4.62 (s, 4H,
Fc), 4.50 (s, 4H, Fc). 31P{1H} NMR (162 MHz, CDCl3): δ 162.4
(2d, 2P, 1J(109AgP) 361, 1J(107AgP) 312 Hz), 11.6 (br s, 1P, PPh3).
Synthesis of [{Fe(C5H4PR)2-κP,κP}Au2Cl2] (12). A solution
of AuCl(SMe2) (0.04 g, 0.136 mmol) in dichloromethane (8 mL)
was added dropwise to a solution of 4 (0.06 g, 0.068 mmol) in
dichloromethane (10 mL), and the reaction mixture was stirred for
6 h. The yellowish-colored solution was concentrated under vacuum
and layered with petroleum ether (1 mL) to give an orange-colored
crystalline product of 12 on cooling at -25 °C. Yield: 88% (0.081
g). Mp: 214-216 °C (dec). Anal. Calcd for C50H32Cl2O4P2S2-
FeAu2: C, 44.69; H, 2.40; S, 4.77. Found: C, 44.61; H, 2.38; S,
using three sets of 400 scans in ω (0.5° per scan) at æ ) 0, 90, and
100° plus two sets of 800 scans in æ (0.45° per scan) at ω ) -30
and 210° using the SMART software package.32 The raw data were
reduced to F 2 values using the SAINT+ software,33 and a global
refinement of unit cell parameters using 8200-8700 reflections
chosen from the full data set was performed. Multiple measurements
of equivalent reflections provided the basis for an empirical
absorption correction as well as a correction for any crystal
deterioration during the data collection (SADABS34). The structure
of 12 was solved by direct methods, whereas for 10, the positions
of the metal atoms were obtained from a sharpened Patterson
function. Both structures were refined by full-matrix least-squares
procedures using the SHELXTL program package.35 Hydrogen
atoms were placed in calculated positions and included as riding
contributions with isotropic displacement parameters tied to those
of the attached non-hydrogen atoms.
1
3
4.72. H NMR (400 MHz, DMSO-d6): δ 8.97 (d, 4H, Ar, JHH
)
)
3
3
8.4 Hz), 8.13 (d, 4H, Ar, JHH ) 9.2 Hz), 7.89 (d, 4H, Ar, JHH
8.0 Hz), 7.58-7.77 (m, 12H, Ar), 5.50 (s, 4H, Fc), 5.31 (s, 4H,
Acknowledgment. We are grateful to the C.S.I.R., New
Delhi, and the Department of Science and Technology (DST),
New Delhi, for funding. We also thank the Department of
Chemistry Instrumentation Facilities, Bombay, for spectral
and analytical data and the Louisiana Board of Regents
through Grant LEQSF(2002-03)-ENH-TR-67 for the pur-
chase of the CCD diffractometer and the Chemistry Depart-
ment of Tulane University for support of the X-ray labora-
tory.
Fc). 31P{1H} NMR (162 MHz, DMSO-d6): δ 142.7 (s).
Catalysis. In a two-necked round-bottom flask under an atmo-
sphere of nitrogen was placed the appropriate amount of catalyst
solution, and 5 mL of methanol was added to it. The correct amount
of catalyst was added as a methanol solution made up by multiple
volumetric dilutions of stock solutions. After stirring for 5 min,
aryl bromide (0.5 mmol), phenylboronic acid (0.75 mmol), and K2-
CO3 (0.138 g, 1 mmol) were introduced into the reaction flask.
The mixture was heated at 60 °C for the required time under an
atmosphere of nitrogen (the course of reaction was monitored by
GC analysis), following which the solvent was removed under
reduced pressure. The residue was diluted with H2O (8 mL) and
Et2O (8 mL) followed by extraction twice (2 × 6 mL) with Et2O.
The combined organic fractions were dried (MgSO4), stripped of
the solvent under vacuum, and the residue redissolved in 5 mL of
dichloromethane. An aliquot was taken with a syringe and subjected
to GC analysis. Yields were calculated versus aryl bromides or
dodecane as an internal standard.
Supporting Information Available: X-ray crystallographic
files in CIF format for the structure determinations of 10 and 12.
This material is available free of charge via the Internet at
http://pubs.acs.org.
IC701537K
(32) SMART, version 5.625; Bruker-AXS: Madison, WI, 2000.
(33) SAINT+, version 6.35A; Bruker-AXS: Madison, WI, 2002.
(34) Sheldrick, G. M.; SADABS, version 2.05; University of Go¨ttingen:
Go¨ttingen, Germany, 2002.
(35) (a) SHELXTL, version 6.10; Bruker-AXS: Madison, WI, 2000. (b)
Sheldrick, G. M. SHELXS97 and SHELXL97; University of Go¨ttin-
gen: Go¨ttingen, Germany, 1997.
X-ray Crystallography. Crystals of 10 and 12 were mounted
in a Cryoloop with a drop of Paratone oil and placed in the cold
nitrogen stream of the Kryoflex attachment of the Bruker APEX
CCD diffractometer. For each, a full sphere of data was collected
Inorganic Chemistry, Vol. 46, No. 24, 2007 10275