Coordination and catalytic properties of a semihomologous Dppf congener, 1-(diphenylphosphino)-1′-[(diphenylphosphino)methyl]ferrocene

Article abstract of DOI:10.1021/om2004805

Alcohol Ph₂PfcCH₂OH (2, fc = ferrocene-1,1′- diyl) reacts smoothly with Ph₂PH and Me₃SiCl/NaI in acetonitrile to give 1-(diphenylphosphino)-1′-[(diphenylphosphino)methyl] ferrocene (1), a new ferrocene diphosphine that fills the obvious gap left between the well-studied 1,1′-bis(diphenylphosphino)ferrocene (dppf) and its bis-spaced analogue, 1,1′-bis[(diphenylphosphino)methyl]ferrocene. The P-oxidized alcohols Ph₂P(E)fcCH₂OH (E = O, 3; S, 4) behave similarly, yielding the corresponding semichalcogenides Ph ₂P(E)fcCH₂PPh₂ (E = O, 5; S, 6). Exhaustive oxidations of 1 with hydrogen peroxide or elemental sulfur produce Ph ₂P(E)fcCH₂P(E)Ph₂ (E = O, 7; S, 8), while similar oxidations of 5 and 6 afford the unsymmetric bis-chalcogenides Ph ₂P(O)fcCH₂P(S)Ph₂ (9) and Ph ₂P(S)fcCH₂P(O)Ph₂ (10), respectively. Compounds 1 and 3-10 were characterized by spectral methods, and the crystal structures of 3 and 8-10 were determined by single-crystal X-ray diffraction analysis. Compound 1 reacts with group 10 metal dichloride precursors to give the respective chelate complexes [MCl₂(1-κ²P,P′)] (11, M = Ni; 12, M = Pd; and 13, M = Pt). The Ni complex is paramagnetic and tetrahedral; the Pd and Pt complexes are expectedly square-planar and diamagnetic. Crystal structures of 11-13 reveal less acute ligand bite angles (P-M-P′) than those observed in the analogous dppf complexes, the difference being considerably larger for the Ni complex than in the less flexible square-planar complexes. Similarly to dppf and fc(CH ₂PPh₂)₂, ligand 1 reacts with [(L ^NC)PdCl]₂ (L^NC = [2-(dimethylamino)methyl] phenyl) to give a diphosphine-bridged complex, [(μ-1){(L^NC)PdCl} ₂] (14), whereas the reaction with the mononuclear precursor [(L ^NC)Pd(MeCN)₂]ClO₄ yields a mixture of isomeric bis-chelates [(L^NC)Pd(1-κ²P,P′)]ClO ₄ (15a,b). Catalytic tests in Pd-catalyzed Suzuki-Miyaura cross-coupling and in Pd-catalyzed cyanation of aryl halides with K ₄[Fe(CN)₆]?3H₂O suggest that introduction of one methylene spacer group into the structure of dppf influences catalytic performance only marginally.

Full text of DOI:10.1021/om2004805

ARTICLE
pubs.acs.org/Organometallics
Coordination and Catalytic Properties of a Semihomologous
Dppf Congener, 1-(Diphenylphosphino)-
10-[(diphenylphosphino)methyl]ferrocene
ꢀ
Petr Stꢀepniꢀcka,* Ivana Císaꢀrovꢁa, and Jiꢀrí Schulz
Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, 128 40 Prague 2, Czech Republic
S Supporting Information
b
ABSTRACT: Alcohol Ph2PfcCH2OH (2, fc = ferrocene-1,10-diyl) re-
acts smoothly with Ph2PH and Me3SiCl/NaI in acetonitrile to give
1-(diphenylphosphino)-10-[(diphenylphosphino)methyl]ferrocene (1),
a new ferrocene diphosphine that fills the obvious gap left between the
well-studied 1,10-bis(diphenylphosphino)ferrocene (dppf) and its bis-
spaced analogue, 1,10-bis[(diphenylphosphino)methyl]ferrocene. The
P-oxidized alcohols Ph2P(E)fcCH2OH (E = O, 3; S, 4) behave similarly,
yielding the corresponding semichalcogenides Ph2P(E)fcCH2PPh2 (E = O, 5; S, 6). Exhaustive oxidations of 1 with hydrogen
peroxide or elemental sulfur produce Ph2P(E)fcCH2P(E)Ph2 (E = O, 7; S, 8), while similar oxidations of 5 and 6 afford the
unsymmetric bis-chalcogenides Ph2P(O)fcCH2P(S)Ph2 (9) and Ph2P(S)fcCH2P(O)Ph2 (10), respectively. Compounds 1 and
3ꢀ10 were characterized by spectral methods, and the crystal structures of 3 and 8ꢀ10 were determined by single-crystal X-ray
diffraction analysis. Compound 1 reacts with group 10 metal dichloride precursors to give the respective chelate complexes
[MCl2(1-k2P,P0)] (11, M = Ni; 12, M = Pd; and 13, M = Pt). The Ni complex is paramagnetic and tetrahedral; the Pd and Pt
complexes are expectedly square-planar and diamagnetic. Crystal structures of 11ꢀ13 reveal less acute ligand bite angles
(PꢀMꢀP0) than those observed in the analogous dppf complexes, the difference being considerably larger for the Ni complex
than in the less flexible square-planar complexes. Similarly to dppf and fc(CH2PPh2)2, ligand 1 reacts with [(LNC)PdCl]2 (LNC
=
[2-(dimethylamino)methyl]phenyl) to give a diphosphine-bridged complex, [(μ-1){(LNC)PdCl}2] (14), whereas the reaction with
the mononuclear precursor [(LNC)Pd(MeCN)2]ClO4 yields a mixture of isomeric bis-chelates [(LNC)Pd(1-k2P,P0)]ClO4 (15a,b).
Catalytic tests in Pd-catalyzed SuzukiꢀMiyaura cross-coupling and in Pd-catalyzed cyanation of aryl halides with K4[Fe-
(CN)6] 3H2O suggest that introduction of one methylene spacer group into the structure of dppf influences catalytic performance
3
only marginally.
’ INTRODUCTION
only one PPh2 group is replaced by another P-donor moiety
remain very rare.9,10 Another approach toward modification of
the dppf molecule is (formally) represented by the attachment
of an additional functional (donor) group and subsequent
manipulations. A typical example of this approach is the vast
family of donors related to BPPFA (Scheme 2)1,2,11 and com-
pounds having an additional donor group directly attached to the
cyclopentadienyl ring (type C in Scheme 2).1,2,12
Phosphinoferrocene ligands received considerable attention
in the recent past owing to their versatile coordination properties
and numerous successful applications in catalysis.1,2 So far, there
have been reported a vast number of ferrocene phosphines
differing by the number and type of donor groups and also by
the substitution patterns. The design of ferrocene ligands thus
obviously follows two established major approaches: the design
of new ligand types and modifications of known structures.
Despite the enormous progress in the chemistry of ferrocene
donors, the archetypal diphosphine, 1,10-bis(diphenylphosphino)-
ferrocene (dppf, Scheme 1),3 still dominates the field, represent-
ing the most frequently studied and practically utilized ferrocene
ligand, which also became a subject of extensive structural
modifications.1,4
Typically, the modification of the basic dppf skeleton has been
achieved through changing the substituents at the phosphorus
atoms. Representative examples of such modified ligands are
symmetrical dppf analogues bearing bulky and/or electron-
donating substituents4ꢀ7 or P-chiral phosphino moieties4,8 (B in
Scheme 2). In contrast, donor-unsymmetric derivatives in which
Recently, we13 decided to go beyond the rather straightforward
“substitution approach” outlined above and set about to modify
bidentate ferrocene ligands by introducing a methylene spacer
between one of the donor groups and the ferrocene moiety.14
Such an approach has already proved warranted for many donors
with organic backbones, typically resulting in changed coordina-
tion preferences, ligand bite angles, and catalytic performance.15
This prompted us to prepare 1-(diphenylphosphino)-10-
[(diphenylphosphino)methyl]ferrocene (1, Scheme 1) as a unsym-
metric dppf congener. This compound, whose donor-asymmetry
Received: June 6, 2011
Published: July 29, 2011
r
2011 American Chemical Society
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|

Organometallics
ARTICLE
Scheme 1
1 and its several P-chalcogenide derivatives. Also reported are the
results of our coordination and catalytic study aimed at a
comparison of this new donor with the well-studied dppf.
’ RESULTS AND DISCUSSION
Synthesis of Diphosphine 1 and Chalcogenide Deriva-
tives Thereof. Compound 1 was prepared by phosphinylation of
10-(diphenylphosphino)ferrocenyl]methanol (2)19 with an ex-
cess of Ph2PH and chlorotrimethylsilane/sodium iodide20,21 in
acetonitrile (Scheme 3). The compound was isolated by column
chromatography, resulting in a viscous, amber brown oil in good
yield (typically ca. 75%). It is noteworthy that although the
diphosphine is moderately air-sensitive, no special precautions
are required in the isolation steps since the unreacted Ph2PH
prevents its oxidation during the aqueous workup and chroma-
tography. Similar phosphinylation reactions with P-oxidized
alcohols 3 and 4 furnished the corresponding semichalcogenides
5 and 6 (Scheme 3). Like any other diphosphine, compound
1 was readily oxidized with aqueous hydrogen peroxide or
elemental sulfur, affording air-stable bis-chalcogenide derivatives
7 and 8. Similar oxidations of semichalcogenides 5 and 6 led to
a pair of mutually isomeric bis-chalcogenide derivatives 9 and
10 (Scheme 3).
Scheme 2. “Standard” Modifications of the Dppf Structure
As Established in the Literature
The formulation of compounds 1 and 3ꢀ10 was established
from NMR and mass spectra and further corroborated by X-ray
diffraction analysis for compounds 322 and 8ꢀ10. In 1H and 13
C
NMR spectra, diphosphine 1 displays characteristic signals due
to ferrocene-1,10-diyl moiety and the PPh2 substituents. Diagnostic
resonances of the methylene linker are seen at δH 2.86 (singlet)
and δC 29.55 (doublet, 2JPC = 15 Hz). The 31P NMR spectrum of
1 corroborates the presence of two nonequivalent PPh2 groups
(δP ꢀ16.2 and ꢀ11.4). Oxidation of the phosphorus groups
such as in chalcogenides derivatives 5ꢀ10 is reflected by cha-
racteristic shifts of the 31P NMR signals to lower fields (to δP ca.
29 for PdO and 41ꢀ42 for PdS) and further by changes in the
order of 13C NMR signals of carbons within the PPh2 groups and
Scheme 3. Synthesis of Diphosphane 1 and Its Chalcogenide
Derivatives
n
in the magnitude of the associated JPC (n = 1ꢀ4) coupling
constants.
The solid-state structures of 8, 9, and 10 H2O (Figures 1 and
3
S2ꢀ4) show the usual ferrocene geometries with alike FeꢀCg
distances and tilt angles less than ca. 2°. The PdO and PdS
distances compare very well with those reported earlier for
dppfE223 and [Fe(η5-C5H3-1-CO2H-2-CH2P(E)Ph2)(η5-C5H5)]
(E = O, S).21b In all cases, the CH2PPh2 arm is directed away
from the ferrocene unit (C6ꢀC11ꢀP2 = 110.8(1)ꢀ114.5(1)°)
and the disubstituted ferrocene moiety assumes a conformation
close to synclinal eclipsed (τ = 71° for 8, 63° for 9, and 72° for 10;
ideal value: 72°).
Preparation and Characterization of Group 10 Metal
Complexes. For the sake of structural comparison, diphosphine
1 was subjected to complexation reactions for which analogies in
the chemistry of dppf can be found using the catalytically relevant
group 10 metals. Thus, reaction of 1 with one equivalent of
[NiCl2(dme)] (dme = 1,2-dimethoxyethane) in acetone/etha-
nol produced complex [NiCl2(1-k2P,P0)] (11) as a dark green
microcrystalline solid in a 95% isolated yield (Scheme 4).
Since solution NMR spectra suggested the complex to be
paramagnetic, a solid sample of 11 was subjected to magnetic
susceptibility measurements. The magnetic susceptibility (Figure 2)
was found to be independent of the magnetic field (except for
very low temperatures) as expected for a standard paramagnetic
arises exclusively from the presence of a single methylene spacer,
has not yet been reported in the literature. It represents a missing
link between dppf3,16 and its doubly spaced counterpart, 1,10-
bis[(diphenylphosphino)methyl]ferrocene (A in Scheme 1).17,18
In this contribution, we describe the preparation of diphosphine
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Scheme 4. Synthesis of [MCl2(1)] Complexes with Group 10
Metalsa
a dme = 1,2-dimethoxyethane; cod = cycloocta-1,5-diene.
Figure 1. Views of the molecular structures of 8, 9, and 10 H2O (for
3
conventional displacement ellipsoid plots, see Supporting Information).
Selected distances and angles (in Å and deg): 8, FeꢀCg1 1.638(1),
FeꢀCg2 1.647(1), tilt 0.9(1); P1ꢀS1 1.9509(8), P2ꢀS2 1.9565(8); 9,
FeꢀCg1 1.6445(7), FeꢀCg2 1.6502(7), tilt 1.58(9); P1ꢀO1 1.489(1),
P2ꢀS2 1.9460(5); 10, FeꢀCg1 1.6418(8), FeꢀCg2 1.6504(8), tilt
1.6(1); P1ꢀS1 1.9593(6), P2ꢀO2 1.493(1). Definitions: Cg1 and Cg2
are the ring centroids of the rings Cp1 = C(1ꢀ5) and Cp2 = C(6ꢀ10),
respectively; tilt = the dihedral angle of the Cp1 and Cp2 least-squares
planes. Note: Atom labeling and plane definitions used for all complexes
of ligand 1 are strictly analogous.
system.24 The molar susceptibility data (within the field-inde-
pendent interval) were evaluated using the CurieꢀWeiss law:
Figure 2. Temperature dependence of molar magnetic susceptibility of
complex 11 at different magnetic fields (specified in the figure). The
inset shows the expansion of the low-temperature region. For plots of
1/χ vs T and a magnetization curve, see Supporting Information.
NAg2μB SðS þ 1Þ
NAμeff
1
C
2
2
χm
¼
¼
¼
3kB
T ꢀ θp
3kB T ꢀ θp
T ꢀ θp
where NA and kB are the Avogadro and Boltzmann constants,
respectively, θp is the paramagnetic Curie temperature, μeff is the
effective magnetic moment, μB is the Bohr magneton, S is the spin
quantum number, and C is the Curie constant.
Assuming that that there is no significant contribution of the
spinꢀorbital interaction, the g factor was fixed to 2.00. The
analysis then gave μeff = 3.05(4) μB and θP = 1.5(5) K. The value
of the effective magnetic moment is slightly higher than the
theoretical one (μeff/μB = [S(S + 1)]1/2 ≈ 2.82 for S = 1) but
corresponds well with the values reported for other Ni2+ com-
plexes with tetrahedral coordination.25 The paramagnetic Curie
temperature indicates a weak ferromagnetic exchange interac-
tion, which is in line with the field-dependent behavior of
magnetic susceptibility at low temperatures (Figure 2).
the associated interligand angles notably differ in both complexes,
ranging from 101.41(4)° to 128.86(6)° for 11 and 95.6(1)° to
124.5(1)° for [NiCl2(dppf-k2P,P0)]. A wider span of the inter-
ligand angles in the dppf complex suggests a more severe deforma-
tion of the tetrahedral coordination environment, resulting from
a lower flexibility of dppf, which is already manifested by a
considerably more acute bite angle (cf. P1ꢀNiꢀP2 = 111.76(4)°
for 11 and 105.0(1)° for the dppf complex). Accordingly, the NiCl2
and NiP2 planes in 11 subtend a dihedral angle of 87.70(8)°,
which is close to the 90° expected for a regular tetrahedron. In the
dppf complex, this dihedral angle is only 83.9(1)°.27 On the other
hand, the geometry of coordinated 1 is regular, showing similar
FeꢀCg distances and negligible tilting (1.9(3)°; cf. 4.5° for the
dppf analogue). Unlike the structurally characterized chalcogenides
8ꢀ10, the CH2PPh2 moiety is oriented toward the cyclopentadienyl-
bound PPh2 group to allow for an efficient chelation.28
Altogether, the data collected suggest 11 to be a “standard”
tetrahedral [NiIICl2P2] complex, which was indeed confirmed by
single-crystal X-ray diffraction analysis (Figures 3 and S5). The
NiꢀP and NiꢀCl distances observed for 11 are quite similar to
those reported for [NiCl2(dppf-k2P,P0)].26 On the other hand,
Analogous complexation reactions of 1 with [MCl2(cod)] (M =
Pd or Pt, cod = η2:η2-cycloocta-1,5-diene) in dichloromethane
afforded diamagnetic, square-planar cis-chelate complexes
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Figure 3. View of the molecular structure of complex 11 (conventional
PLATON plot is available as Supporting Information). Selected dis-
tances and angles for 11 (in Å and deg): NiꢀCl1 2.214(2), NiꢀCl2
2.201(1), NiꢀP1 2.312(1), NiꢀP2 2.335(1), Cl1ꢀNiꢀCl2 128.86(6),
P1ꢀNiꢀP2 111.76(4); FeꢀCg1 1.630(2), FeꢀCg2 1.644(2), P1ꢀC1
1.793(4), P2ꢀC11 1.830(4), C6ꢀC11 1.521(6), P2ꢀC11ꢀC6
117.5(3), tilt 1.9(3). Cg1/2 are defined as for 8 (see Figure 1).
[MCl2(1-k2P,P0)] (12, M = Pd; 13, M = Pt). These compounds
are air-stable but separate as crystalline solvates highly prone to
desolvation under ambient conditions. ESI mass spectra support
the formulation of 12 and 13 by showing signals due to
[MCl(1)]+ with characteristic isotopic patterns. Coordination
of the phosphorus atoms of ligand 1 is manifested through a shift
of both 31P NMR resonances to lower fields (12: δP 18.2 and
24.6, 13: δP 0.6 and 5.0) and, in the case of 13, also by a scalar
coupling between the chemically nonequivalent phosphorus
nuclei (2JPP = 18 Hz) and by 195Pt satellites. The associated
one-bond coupling constants (1JPtP = 3537 and 3655 Hz) suggest
the cis-PꢀP arrangement.29 It is worth noting that whereas 1
behaves similarly to dppf for all the “MCl2” fragments, dipho-
sphine A reacts with hydrated NiCl2 and [PdCl2(MeCN)2]
under the formation of P,P0-bridged dimers, [(μ-A)MCl2]2.17,30
The crystal structures of solvated complexes 12 and 13
(Figures 4, S6, and S7) reveal similar coordination geometries.
For instance, the interligand distances and angles differ by as little
as 0.035 Å and 1.7° in the respective pairs. Moreover, the
individual M-donor bond lengths compare well with those of
Figure 4. View of the complex molecules in the structure of
12 2CH2Cl2 (top) and 13 0.8CH2Cl2 (bottom). Conventional PLA-
TON plots are available as Supporting Information. Selected distances
3
3
and angles for 12 2CH2Cl2 [analogous parameters for 13 0.8CH2Cl2
3
3
in square brackets] (in Å and deg): MꢀCl1 2.3582(8) [2.3555(8)],
MꢀCl2 2.3304(9) [2.3351(7)], MꢀP1 2.2624(8) [2.2484(7)], MꢀP2
2.2892(8) [2.2554(7)], Cl1ꢀMꢀCl2 88.74(3) [86.97(2)], P1ꢀMꢀP2
96.31(3) [97.90(2)]; FeꢀCg1 1.644(2) [1.638(1)], FeꢀCg2 1.646(2)
[1.646(1)], P1ꢀC1 1.793(3) [1.796(3)], P2ꢀC11 1.851(4) [1.845(3)],
C6ꢀC11 1.500(5) [1.509(4)], P2ꢀC11ꢀC6 121.6(2) [120.3(2)], tilt
1.7(2) [3.1(2)]. Cg1/2 are defined as for 8 (see Figure 1).
[PdCl2(dppf)] Solv (Solv = CHCl331 or CH2Cl232) and [PtCl2-
In analogy to dppf and A,36 1 reacts with the dimeric precursor
[(LNC)Pd(μ-Cl)]2 under bridge cleavage to afford diphosphine-
bridged dipalladium(II) complex 14 (Scheme 5). A replacement
of acetonitrile ligands from the bis-solvento complex [(LNC)-
Pd(MeCN)2]ClO4 with an equimolar amount of 1 affords a
mixture of isomeric bis-chelate complexes 15a and 15b in a ca.
40:60 ratio according to integration of the 31P NMR spectrum.
This suggests that the nonequivalent phosphine groups of 1 are
differentiated only insignificantly by the dissymmetric (LNC)Pd
fragment.
3
(dppf)] Solv (Solv = 1/2Me2CO33 or CHCl334). The ligand bite
3
angles in 12 and 13 are more acute than in the respective dppf
complexes. Yet, the differences are considerably smaller than that
for the nickel complexes discussed above (ca. 2.2° for Pd and ca.
1.4° for Pt), probably due to a higher rigidity of the square-planar
coordination environment.
Atoms constituting the coordination planes in 12 and 13, {M,
Cl1/2, P1/2}, are coplanar within less than 0.1 Å, and the planes
are oriented nearly perpendicular to the ferrocene backbone (the
dihedral angle of the coordination and Cp1 planes is 85° in both
structures). Formation of the chelate ring is aided by the ferrocene
unit adopting a conformation close to synclinal eclipsed (τ = 14°
for 12 and 15° for 13; tilts e3°) and further by rotation of the
CH2PPh2 pendant toward P1 (the arm is more opened than in
8ꢀ10; C6ꢀC11ꢀP2 = 120ꢀ122°).35 All phenyl groups are
directed away from the coordination plane and the ferrocene unit.
Catalytic Tests. Catalytic properties of 1 were evaluated in
palladium-catalyzed CꢀC bond forming reactions, namely, in
SuzukiꢀMiyaura cross-coupling37 of aromatic halides with var-
ious boronic acids and in cyanation of the same substrates with
K4[Fe(CN)6] 3H2O.38 Both reactions hold particular value for
3
organic synthesis:39 The first one is typically used to build up a
molecular skeleton, while the latter represents a convenient
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Scheme 5. Preparation of Palladium Complexes with an
Auxiliary [2-(Dimethylamino-jN)methyl]phenyl-kC1 (LNC
Ligand
Table 1. Summary of Catalytic Results Obtained with
)
Defined and in Situ Generated Catalysts in SuzukiꢀMiyaura
Reactions of 4-Bromoacetophenone with Boronic Acidsa
boronic acid
PhCHd
Ph(CH2)2
b
c
c
c
catalyst
PhB(OH)2 CHB(OH)2
B(OH)2
BuB(OH)2
[PdCl2(1)]
92 (91)
100 (86)
100 (63)
97 (78)
n.a.
42
52
56
51
20
12
53
26
36
29
8
[PdCl2(dppf)]
Pd(OAc)2/1
Pd(OAc)2/dppf
Pd2(dba)3/1
Pd2(dba)3/dppf
73
100
61
11
41
18
n.a.
100
a For detailed conditions, see Experimental Section (n.a. = not available).
b Conversions with 0.1 mol % (0.01 mol %) Pd catalyst. c Reactions with
5 mol % Pd catalyst.
Scheme 6. Pd-Catalyzed SuzukiꢀMiyaura Cross-Coupling
Reactions
alternative to the standard, often hazardous, conventional meth-
ods used for the preparation of synthetically valuable nitriles.
Initial tests in the SuzukiꢀMiyaura cross-coupling were per-
formed for the reaction of 4-bromoacetophenone with phenyl-
boronic acid to give 4-acetylbiphenyl (Scheme 6) using 0.1 or
0.01 mol % Pd catalyst either as a defined complex (i.e.,
[PdCl2(L)] (L = 1 or dppf)) or generated in situ from palladium-
(II) acetate and the respective diphosphine. The results are
summarized in Table 1.
Figure 5. Kinetic profiles for SuzukiꢀMiyauracross-coupling reaction of
4-bromoacetophenone with phenylboronic acid. Conditions: 0.1 mol %
of Pd-catalyst (b Pd(OAc)2/dppf, O Pd(OAc)2/1, Δ [PdCl2(1)], 1
[PdCl2(dppf)]), dioxane, 100 °C.
Scheme 7. Pd-Catalyzed Cyanation of Aryl Bromides
All reactions performed at 0.1 mol % Pd loading (in dioxane at
100 °C for 24 h) proceeded with complete or very good
conversions regardless of the type of catalyst. Upon lowering
the amount of Pd catalyst to 0.01 mol %, the defined precatalyst
still performed very well, while the activity of their in situ formed
counterparts significantly decreased (Table 1). Kinetic profiles
determined for the model reaction (Figure 5) showed that both
in situ generated catalysts (Pd(OAc)2/diphosphine) are “acti-
vated” very rapidly and achieve complete conversions within 2 h
(0.1 mol % Pd). In contrast, the catalysts formed from the
defined complexes [PdCl2(L)] exert relatively slower reaction
rates and also differ significantly for both chelating ligands (rate:
1 . dppf).
35% for L = dppf; Pd(OAc)2/L: 15% for L = 1 and 12% for L =
dppf; Pd2(dba)3/L: 9% for L = 1 and 25% for L = dppf; in
dioxane at 100 °C after 24 h).
The results obtained in reactions of 4-bromoacetophenone
with other boronic acids (Table 1) were rather modest despite
using the typically higher amounts of the Pd catalyst (5 mol %).
In the case of styrylboronic acid, dppf-based catalysts performed
somewhat better than those derived from 1. In other cases
(phenethyl- and butylboronic acid), either the catalytic perfor-
mance of the pairs of structurally related catalysts were very
similar ([PdCl2(L)] and Pd(OAc)2/L) or the catalysts obtained
from 1 reacted slightly better (Pd2(dba)3/L system).
When the less reactive 4-chloroacetophenone37,40 was em-
ployed as the substrate in the SuzukiꢀMiyaura reaction, the
yields of the coupling product were fairly low even at 1 mol % Pd
loading. The defined precatalysts still performed better than their
in situ generated counterparts (cf. [PdCl2(L)]: 24% for L = 1 and
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Table 2. Catalytic Results for Pd-Catalyzed Cyanation of
4-Substituted Bromobenzenes (4-RC6H4Br) with
recorded with an FT IR Nicolet Magna 760 instrument. Magnetic
susceptibilities were measured using a Quantum Design superconduct-
ing quantum interference device (SQUID) MPMS 7XL magnetometer
at 1.0, 2.0, 4.0, and 7.0 T over the temperature range 2ꢀ300 K. A
magnetization curve (see Supporting Information) was measured at 2 K
up to a magnetic field of 7 T. The sample was loaded into a gelatin
capsule and fixed in a plastic straw. Low-resolution electrospray ioniza-
tion (ESI) mass spectra were obtained with an Esquire 3000 (Bruker)
spectrometer. High-resolution ESI MS spectra were recorded with an
LTQ Orbitrap XL spectrometer (Thermo Fisher Scientific).
K4[Fe(CN)6] 3H2Oa
3
conversion [%]
conversion [%]
R
[PdCl2(dppf)] [PdCl2(1)]
R
[PdCl2(dppf)] [PdCl2(1)]
Ac
100
100
100
100
MeO
NO2
85
70
80
77
Me
a 4-RC6H4Br (1.0 mmol), Na2CO3 (1.0 mmol), and K4[Fe-
Synthesis of [10-(Diphenylphosphinoyl)ferrocenyl]methanol
(3). In air, a solution of alcohol 2 (1.41 mg, 3.5 mmol) in acetone
(25 mL) was treated with ca. 30% aqueous hydrogen peroxide solution
(1 mL, ca. 10 mmol) while stirring and cooling in ice. After 30 min, the
reaction mixture was diluted with brine (10 mL) and excess hydrogen
peroxide was destroyed by addition of saturated aqueous Na2S2O3
(10 mL). The acetone was removed under reduced pressure, and the
residue extracted twice with ethyl acetate. The combined organic extracts
were washed with brine, dried over MgSO4, and filtered through a pad of
silica gel (chromatographic grade, elution with ethyl acetate). The eluate
was evaporated under vacuum, and the residue was subsequently crystal-
lized from ethyl acetate/hexane. Yield:1.31 g, 90%;orange-brown crystals.
1H NMR (CDCl3): δ 4.01 (vt, 2 H, J0 = 1.9 Hz, fc), 4.35 (m, 4 H, fc),
4.43 (d, 2 H, 3JHH = 6.7 Hz, CH2OH), 4.53 (vq, 2 H, J0 = 1.9 Hz, fc), 5.87
(td, 1 H, 3JHH = 6.7, J = 1.2 Hz, CH2OH), 7.41ꢀ7.72 (m, 10 H, PPh2).
13C{1H} NMR (CDCl3): δ 59.81 (CH2OH), 67.73, 68.25, 71.97 (d,
JPC = 10 Hz) (3 ꢁ CH of fc); 72.74 (d, 1JPC = 117 Hz, C-P(O)Ph2 of fc),
72.81 (d, JPC = 13 Hz, CH of fc), 93.14 (C-CH2OH of fc), 128.33 (d,
(CN)6] 3H2O (0.25 mmol) were reacted in the presence of Pd-catalyst
(5 μmol) in DMF at 130 °C for 16 h.
3
Palladium-catalyzed cyanation of 4-substituted bromoben-
zenes was carried out only with the defined precatalysts [PdCl2-
(L)] (Scheme 7 and Table 2). At 0.5 mol % palladium loading
(in DMF at 130 °C for 16 h), both complexes behaved similarly,
affording complete conversions with 4-bromoacetophenone and
4-bromotoluene and ca. 80% conversions for the remaining
substrates (4-bromoanisole and 4-nitrobromobenzene).
’ CONCLUSIONS
Compound 1, a semihomologous derivative of the popular
dppf, is readily obtained upon reacting alcohol 2 with HPPh2 and
Me3SiCl/NaI. Such a synthetic approach is highly versatile
because the phosphorus substituents are introduced in a stepwise
manner and can be also independently manipulated, which was
demonstrated by the preparation of a series of chalcogenide
derivatives, 5ꢀ10.
2
3JPC = 12 Hz, CHmeta of PPh2), 131.40 (d, JPC = 10 Hz, CHortho of
4
1
PPh2), 131.76 (d, JPC = 3 Hz, CHpara of PPh2), 133.32 (d, JPC
=
107 Hz, Cipso of PPh2). 31P NMR (CDCl3): δ 31.8 (s). IR (Nujol): 3340
br s, 3097 vw, 3080 w, 3071 vw, 3060 w, 2719 w, 2611 w, 2013 w, 1911 w,
1896 w, 1815 w, 1733 m, 1591 m, 1358 w, 1347 w, 1310 m, 1248 m, 1235
m, 1196 s, 1180 s, 1165 s, 1123 s, 1104 s, 1071 m, 1044 m, 1033 m, 1016
s, 998 m, 978 w, 948 m, 922 m, 882 w, 853 m, 837 s, 822 m, 752 s, 738 m,
708 s, 697 s, 670 m, 633 m, 621 m, 570 s, 528 s, 518 s, 500 s, 483 s, 466 m,
439 s cmꢀ1. Anal. Calcd for C23H21FeO2P (416.22): C 66.37, H 5.09.
Found: C 66.28, H 5.05.
As a ligand in group 10 metal complexes, diphosphine 1 binds
more flexibly than dppf, which is reflected mainly in the ligand
bite angles. Introduction of a methylene group lowers the overall
molecular symmetry and results in an enhanced solubility of 1
and its complexes in organic solvents in comparison with dppf.
On the other hand, the presence of the flexible methylene linker
does not affect much the catalytic performance of both the
defined complexes and precatalysts generated in situ from 1 and a
metal source. This warrants further catalytic and structural
studies with libraries of 1-type ligands in which the phosphino
groups and the nature of the single spacer unit are varied. In
summary, the results presented in this work demonstrate that
homologation of the known ligand structures is a viable route to
new ferrocene donors with modified ligating properties.
Synthesis of [10-(Diphenylthiophosphinoyl)ferrocenyl]-
methanol (4). A solution of alcohol 2 (1.203 g, 3.0 mmol) and sulfur
(97.5 mg, 3.0 mmol) in dry toluene (20 mL) was heated at reflux for
90 min. After cooling, the solvent was evaporated under vacuum and the
yellow-brown residue was crystallized from ethyl acetate/hexane. Yield:
1.10 g, 84%, orange-brown crystals.
1H NMR (CDCl3): δ 2.70 (t, 1 H, 3JHH = 6.3 Hz, CH2OH), 3.97 (vt,
2 H, J0 = 1.6 Hz, fc), 4.28 (d, 2 H, 3JHH = 6.3 Hz, CH2OH), 4.28 (vt, 2 H,
J0 = 1.6 Hz, fc), 4.46 (vq, 2 H, J0 = 1.6 Hz, fc), 4.53 (q, 2 H, J0 = 2.0 Hz, fc),
7.39ꢀ7.76 (m, 10 H, PPh2). 13C{1H} NMR (CDCl3): δ 60.09
’ EXPERIMENTAL SECTION
(CH2OH), 69.19, 69.59, 72.10 (d, JPC = 10 Hz), 73.39 (d, JPC
=
Unless noted otherwise, the syntheses were carried out under an
argon atmosphere and with exclusion of direct daylight. Alcohol 2,19
[MCl2(cod)] (M = Pd and Pt),41 [(LNC)Pd(μ-Cl)]2,42 and [(LNC)-
13 Hz) (4 ꢁ CH of fc); 75.18 (d, 1JPC = 98 Hz, C-P(S)Ph2 of fc), 90.95
(C-CH2OH of fc), 128.25 (d, 3JPC = 13 Hz, CHmeta of PPh2), 131.35 (d,
4JPC = 3 Hz, CHpara of PPh2), 131.58 (d, 2JPC = 1 Hz, CHortho of PPh2),
134.18 (d, 1JPC = 87 Hz, Cipso of PPh2). 31P NMR (CDCl3): δ 42.5 (s).
IR (Nujol): 3609 w, 3571 m, 3471 br m, 3072 vw, 3055 vw, 3044 vw,
2723 w, 1734 w, 1307 m, 1265 w, 1228 m, 1181 m, 1171 s, 1104 s, 1070
w, 1025 s, 1003 s, 936 w, 920 m, 871 m, 838 m, 822 m, 754 s, 717 s, 697 s,
655 s, 627 m, 614 m, 544 s, 521 w, 504 s, 494 s, 449 m, 436 w, 429
w cmꢀ1. Anal. Calcd for C23H21FeOPS (432.04): C 63.90, H 4.90.
Found: C 63.83, H 4.70.
43
Pd(MeCN)2]ClO4 were synthesized according to literature proce-
dures. Dichloromethane and chloroform were dried over anhydrous
potassium carbonate and distilled. Toluene and (1,4-)dioxane were
distilled from sodium metal. Other chemicals, anhydrous acetonitrile,
and solvents used for crystallizations and in chromatography were used
as received (Fluka, Aldrich; solvents from Lach-Ner).
NMR spectra were measured with a Varian UNITY Inova 400
spectrometer at 298 K. Chemical shifts (δ/ppm) are given relative to
internal SiMe4 (1H and 13C) or to external 85% H3PO4 (31P). In
addition to the standard notation of signal multiplicity, vt and vq are used
to denote virtual multiplets due to protons constituting the AA0BB0 and
AA0BB0X spin systems of the Ph2PCH2- and PPh2-substituted cyclo-
pentadienyl rings, respectively (fc = ferrocene-1,10-diyl). IR spectra were
1-(Diphenylphosphino)-10-[(diphenylphosphino)methyl]-
ferrocene (1). Chlorotrimethylsilane (0.8 mL, 6 mmol) was added
to a stirring solution of alcohol 5 (1.00 g, 2.5 mmol) and sodium iodide
(750 mg, 7.5 mmol) in dry acetonitrile (50 mL). A white precipitate
(NaCl) formed immediately. After 5 min, neat diphenylphosphine
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Organometallics
ARTICLE
(1.15 mL, 6.6 mmol) was introduced, and stirring was continued for
24 h. Then, the reaction mixture was diluted with saturated aqueous
NaCl and diethyl ether. The organic phase was separated, dried over
MgSO4, and co-evaporated with alumina (chromatographic grade, neutral).
The preadsorbed crude product was transferred onto the top of an alumina
column (hexane), and the column was eluted with hexane to remove an
excess of diphenylphosphine. Subsequent elution with hexane/diethyl
ether (1:1 v/v) gave a yellow band, which, after evaporation under
reduced pressure, afforded analytically pure 1 as a viscous, amber-brown
oil. Yield: 1.09 g (77%). Note: Ph2PH and 1 may co-elute during the
chromatography if the acetonitrile is not removed completely.
1H NMR (CDCl3): δ 2.92 (s, 2 H, CH2), 3.92 and 3.96 (2 ꢁ vt, J0 ≈
1.9 Hz, 2 H, fc); 4.34 and 4.44 (2 ꢁ vq, J0 ≈ 1.9 Hz, 2 H, fc); 7.28ꢀ7.74
(m, 20 H, PPh2). 13C{1H} NMR (CDCl3): δ 29.20 (d, 1JPC = 13 Hz,
CH2), 69.30 (2 C), 71.26 (d, 2 C, JPC = 4 Hz), 72.54 (d, 2 C, JPC = 10
Hz), 73.85 (d, 2 C, JPC = 13 Hz) (CH of fc); 75.03 (d, 1JPC = 98 Hz,
C-P(S)Ph2 of fc), 84.42 (d, 2JPC = 16 Hz, C-CH2PPh2 of fc), 128.13 (d, 4
C, 3JPC = 13 Hz, CHmeta of P(S)Ph2), 128.29 (d, 4 C, 3JPC = 7 Hz, CHmeta
4
of PPh2), 128.71 (2 C, CHpara of PPh2), 131.12 (d, 2 C, JPC = 3 Hz,
CHpara of P(S)Ph2), 131.61 (d, 4 C, 2JPC = 11 Hz, CHortho of P(S)Ph2),
132.89 (d, 4 C, 2JPC = 18 Hz, CHortho of PPh2), 134.65 (d, 2 C, 1JPC = 87
1
Hz, Cipso of P(S)Ph2), 138.34 (d, 2 C, JPC = 15 Hz, Cipso of PPh2).
1H NMR (CDCl3): δ 2.86 (s, 2 H, CH2), 3.84 and 3.89 (2 ꢁ vt, J0 =
1.8 Hz, 2 H, fc); 4.01 (vq, J0 = 1.9 Hz, 2 H, fc), 4.32 (vt, J0 = 1.8 Hz, 2 H,
fc), 7.24ꢀ7.37 (m, 20 H, PPh2). 13C{1H} NMR (CDCl3): δ 29.55 (d,
1JPC = 15 Hz, CH2), 68.58 (2 C), 70.27 (d, 2 C, JPC = 4 Hz), 71.68 (d, 2
C, JPC = 4 Hz), 73.71 (d, 2 C, JPC = 15 Hz) (CH of fc); 75.70 (d, 1JPC = 7
Hz, C-PPh2 of fc), 84.81 (d, 2JPC = 15 Hz, C-CH2PPh2 of fc), 128.08 and
128.23 (2 ꢁ d, 4 C, 3JPC = 7 Hz, CHmeta of PPh2); 128.44 and 128.58
(2 ꢁ s, 2 C, CHpara of PPh2); 132.86 (d, 4 C, 2JPC = 18 Hz) and 133.50
31P{1H} NMR (CDCl3): δ ꢀ11.0 (s, PPh2), 42.2 (s, P(S)Ph2). HR MS
(ESI+): calcd for C35H3156FeP2S ([M + H]+) 601.0966, found 601.0967.
1-(Diphenylphosphinoyl)-10-[(diphenylphosphinoyl)methyl]-
ferrocene (7). In air, 30% aqueous hydrogen peroxide (0.2 mL) was
added to a solution of diphosphine 1 (114 mg, 0.20 mmol) in acetone
(10 mL) while stirring and cooling in an ice bath. After stirring for 1 h,
sodium thiosulfate solution (5 mL of 30% solution in water) was
introduced, and the stirring was continued at the same temperature for
another 30 min to destroy an excess of H2O2. The acetone was removed
under vacuum, and the residue was diluted with water and extracted with
chloroform. The organic extract was dried (MgSO4), evaporated, and
then purified by column chromatography (silica gel, dichloromethane/
methanol, 10:1 v/v). The single yellow band was collected and evaporated
under vacuum to afford pure 7 as a brown, viscous oil. Yield: 113 mg (93%).
1H NMR (CDCl3): δ 3.32 (d, 2JPH = 12.2 Hz, 2 H, CH2), 4.00 (vt, J0 =
1.9 Hz, 2 H, fc), 4.16 (td, J = 1.9, ca. 0.8 Hz, 2 H, fc), 4.25 (vq, J0 = 1.9 Hz,
2 H, fc), 4.44 (vq, J0 = 1.9 Hz, 2 H, fc), 7.37ꢀ7.72 (m, 20 H, PPh2).
13C{1H} NMR (CDCl3): δ 32.39 (d, 1JPC = 67 Hz, CH2), 69.47 (2 C),
71.52 (d, 2 C, JPC = 2 Hz), 72.41 (d, 2 C, JPC = 10 Hz), 73.30 (d, 2 C,
JPC = 13 Hz) (CH of fc); 73.06 (d, 1JPC = 117 Hz, C-PPh2 of fc), 79.70
(d, 4 C, 2JPC = 20 Hz) (2 ꢁ CHortho of PPh2); 138.40 (d, 2 C, 1JPC
=
15 Hz) and 139.12 (d, 2 C, 1JPC = 10 Hz) (2 ꢁ Cipso of PPh2). 31P{1H}
NMR (CDCl3): δ ꢀ16.2 (s, fcPPh2), ꢀ11.4 (s, CH2PPh2). IR (neat):
3069 m, 3051 m, 3027 w, 3014 w, 3000 w (νCH); 1954, 1888, 1813,
1749, 1662 (all m; νCdC aromatics); 1585 m, 1479 s, 1433 vs, 1307 m,
1192 m, 1160 s, 1068 m, 1026 s, 924 m, 828 s br, 813 m, 743 vs, 699 vs,
632 m, 496 s br, 456 m cmꢀ1. HR MS (ESI+): calcd for C35H3056FeP2
(M+) 568.1168, found 568.1163.
1-(Diphenylphosphinoyl)-10-[(diphenylphosphino)methyl]-
ferrocene (5). Alcohol 3(416 mg, 1.0 mmol) and NaI (300 mg, 2.0 mmol)
were dissolved in dry acetonitrile (20 mL). The resultant solution was treated
with chlorotrimethylsilane (0.3 mL, ca. 2.4 mmol). A white precipitate formed
immediately. After stirring for 5 min, neat diphenylphosphine (0.45 mL,
2.5 mmol) was added and stirring was continued overnight. The reaction
mixture was quenched with brine and diluted with diethyl ether. The clear,
orange organic layer was separated, dried over MgSO4, and evaporated with
chromatographic alumina. The preadsorbed crude product was transferred
onto the top of a chromatographic column, and the column was eluted first
with hexane/ethyl acetate (1:1) to remove excess Ph2PH and then with ethyl
acetate to elute the product. After evaporation of the second fraction under
vacuum, the product was chromatographed once again on silica gel using ethyl
acetate to give, after evaporation, pure compound 5 as an orange solid. Yield:
392 mg (67%). 1HNMR(CDCl3):δ2.90 (s, 2 H, CH2), 3.98 and 4.03 (2 ꢁ
vt, J0 ≈ 1.8 Hz, 2 H, fc); 4.28 and 4.42 (2 ꢁ vq, J0 ≈ 1.9 Hz, 2 H, fc);
7.27ꢀ7.67 (m, 20 H, PPh2). 13C{1H} NMR (CDCl3): δ 29.36 (d, 1JPC = 15
Hz, CH2), 69.09 (2 C), 70.73 (d, 2 C, JPC = 4 Hz), 72.52 (d, 2 C, JPC = 10
Hz) (CH of fc); 72.81 (d, 1JPC = 118 Hz, C-P(O)Ph2 of fc), 73.03 (d, 2 C,
JPC = 13 Hz, CH of fc); 85.85 (d, 2JPC = 16 Hz, C-CH2PPh2 of fc), 128.13 (d,
4 C, 3JPC = 12 Hz, CHmeta of P(O)Ph2), 128.24 (d, 4 C, 3JPC = 7 Hz, CHmeta
of PPh2), 128.60 (2 C, CHpara of PPh2), 131.40 (d, 4 C, 2JPC =10Hz,CHortho
of P(O)Ph2), 131.40 (d, 2 C, 4JPC = 3 Hz, CHpara of P(O)Ph2), 132.85 (d,
4 C, 2JPC = 19 Hz, CHortho of PPh2), 134.47 (d, 2 C, 1JPC = 106 Hz, Cipso of
(d, 2JPC = 3 Hz, C-CH2PPh2 of fc), 128.20 and 128.39 (2 ꢁ d, 4 C, 3JPC
=
12 Hz, CHmeta of PPh2); 131.20 (d, 4 C, 2JPC = 9 Hz) and 131.39 (d, 4 C,
2JPC = 10 Hz) (CHortho of PPh2); 131.49 and 131.68 (2 ꢁ d, 2 C, 4JPC
=
3 Hz, CHpara of PPh2); 132.38 (d, 2 C, 1JPC = 98 Hz) and 134.37 (d, 2 C,
1JPC = 106 Hz) (2 ꢁ Cipso of PPh2). 31P{1H} NMR (CDCl3): δ 28.9 and
29.3 (2 ꢁ s, P(O)Ph2). HR MS (ESI+): calcd for C35H3156FeO2P2 ([M
+ H]+) 601.1143, found 601.1144.
1-(Diphenylthiophosphinoyl)-10-[(diphenylthiophosphinoyl)-
methyl]ferrocene (8). Compound 1 (114 mg, 0.20 mmol) and sulfur
(25.5 mg, 0.80 mmol) were mixed with dry toluene (10 mL). The
resulting solution was heated at gentle reflux for 90 min, cooled, and
filtered through a pad of silica gel, eluting with diethyl ether. The filtrate
was evaporated, and the residue was dissolved in hot glacial acetic acid
(20 mL). The solution was diluted with hot water (5 mL) and allowed to
crystallize by slow cooling first to room temperature and then to 4 °C.
The separated product was filtered off, washed successively with 50%
acetic acid and water, and dried under vacuum. Yield of solvate
8 AcOH: 107 mg (77%), yellow-brown needles. Note: Depending on
3
the crystallization conditions, the compound separates either unsolvated
or in the form of acetic acid solvate, 8 AcOH.
3
1
P(O)Ph2), 138.29 (d, 2 C, JPC = 15 Hz, Cipso of PPh2). 31P{1H} NMR
1H NMR (CDCl3): δ 3.64 (d, 2JPH = 11.7 Hz, 2 H, CH2), 3.86 (vt, J0 =
1.8 Hz, 2 H, fc), 4.08 (br m, 2 H, fc), 4.31 and 4.47 (2 ꢁ vq, J0 ≈ 1.8 Hz,
2 H, fc), 7.34ꢀ7.86 (m, 20 H, PPh2). 13C{1H} NMR (CDCl3): δ 35.99
(d, 1JPC = 51 Hz, CH2), 69.39 (2 C), 72.30 (d, 2 C, JPC = 10 Hz), 72.44
(d, 2 C, JPC = 2 Hz), 74.02 (d, 2 C, JPC = 13 Hz) (CH of fc); 75.30 (d,
1JPC = 98 Hz, C-PPh2 of fc), 79.62 (C-CH2PPh2 of fc), 128.21 and
(CDCl3): δ ꢀ11.1 (s, PPh2), 29.2 (s, P(O)Ph2). HR MS (ESI+): calcd for
C35H3156FeOP2 ([M + H]+) 585.1194, found 585.1195.
1-(Diphenylthiophosphinoyl)-10-[(diphenylphosphino)-
methyl]ferrocene (6). Compound 4 was prepared similarly from
alcohol 9 (432.5 mg, 1.0 mmol), NaI (453 mg, 3.0 mmol), chloro-
trimethylsilane (0.35 mL, ca. 3 mmol), and diphenylphosphine (0.7 mL,
4 mmol) in dry MeCN (20 mL). The reaction mixture was worked up as
described for 5, and the preadsorbed crude product was transferred onto
the top of a chromatographic column. The column was eluted first with
hexane to remove unreacted Ph2PH and then with hexane/diethyl ether
(1:1, v/v) to wash out the product. Evaporation of the second fraction
afforded 6 as an orange solid. Yield: 374 mg (62%).
128.40 (2 ꢁ d, 4 C, 3JPC = 12 Hz, CHmeta of PPh2); 131.34 (d, 2 C, 4JPC
=
3 Hz) and 131.41 (d, 2 C, 4JPC = 2 Hz) (2 ꢁ CHpara of PPh2); 131.57 (d,
4 C, 2JPC = 11 Hz) and 131.64 (d, 4 C, 2JPC = 10 Hz) (CHortho of PPh2);
132.24 (d, 2 C, 1JPC = 79 Hz) and 134.37 (d, 2 C, 1JPC = 87 Hz) (2 ꢁ
Cipso of PPh2). 31P{1H} NMR (CDCl3): δ 41.3 and 42.2 (2 ꢁ s,
P(S)Ph2). HR MS (ESI+): calcd for C35H3156FeP2S2 ([M + H]+)
633.0686, found 633.0690.
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ARTICLE
1-(Diphenylphosphinoyl)-10-[(diphenylthiophosphinoyl)-
methyl]ferrocene (9). Compound 5 (59 mg, 0.10 mmol) and sulfur
(5 mg, ca. 0.16 mmol) were dissolved in toluene (2 mL). The solution
was stirred overnight, whereupon it deposited a yellow precipitate. The
reaction mixture was evaporated to dryness, and the residue was
dissolved in warm ethyl acetate (5 mL). Crystallization by addition of
hexane (5 mL) as a top layer and standing for several days afforded
orange-brown needles of 9, which were filtered off, washed with pentane,
and dried under vacuum. Yield: 44 mg (71%).
1 h, filtered (PTFE syringe filter, 0.45 μm), and layered with diethyl ether
(12 mL). Crystallization by liquid-phase diffusion at 4 °C over several days
afforded red crystals, which were filtered off, washed with pentane, and dried
under vacuum to afford 12 0.2CH2Cl2 as a brick red solid. Yield: 64 mg
3
(84%).
1H NMR (CDCl3): δ 2.74 (dd, 2 H, 2JPH = 11.2, 4JPH = 1.8 Hz, CH2),
3.41 (br t, 2 H), 4.13 (vt, J0 = 1.8 Hz, 2 H), 4.68 (d of vt, J0 = 0.9, 1.9 Hz, 2
H), 5.11 (br s, 2 H) (CH of fc), 7.33ꢀ7.89 (m, 20 H, PPh2). 31P{1H}
NMR (CDCl3): δ 18.2, 24.6 (2 ꢁ s). ESI ( MS: m/z 709/711
1H NMR (CDCl3): δ 3.56 (d, 2JPH = 11.8 Hz, 2 H, CH2), 3.98 (vt,
J0 ≈ 1.9 Hz, 2 H), 4.12 (m, 2 H), 4.26 and 4.45 (2 ꢁ vq, J0 ≈ 1.9 Hz, 2 H)
(CH of fc); 7.35ꢀ7.83 (m, 20 H, PPh2). 13C{1H} NMR (CDCl3): δ
36.02 (d, 1JPC = 51 Hz, CH2), 69.39 (2 C), 71.85 (d, 2 C, JPC = 2 Hz),
([Pd(1)Cl]+); 781 ([Pd(1)Cl3]ꢀ). Anal. Calcd for C35H30Cl2FeP2Pd
0.2CH2Cl2 (762.7): C 55.43, H 4.02. Found: C 55.25, H 4.04.
3
Dichlorido{1-(diphenylphosphino)-10-[(diphenylphosphino)-
methyl]ferrocene-j2P,P0}platinum(II) (13). A solution of 1 (59 mg,
0.10 mmol) in dichloromethane (6 mL) was added to solid [PtCl2(cod)]
(37.5 mg, 0.10 mmol). The resulting yellow solution was stirred for 1 h,
filtered (PTFE syringe filter, 0.45 μm), and layered with diethyl ether (ca.
10 mL). Subsequent crystallization at room temperature over several days
afforded beautiful yellow crystals, which were filtered off, washed with
pentane, and dried under vacuum. During isolation in the air, the crystals
became opaque and then disintegrated due to extensive desolvation, finally
affording the product as a nonstoichiometric solvate. Yield: 80 mg (94%) of
1
72.30 (d, 2 C, JPC = 10 Hz) (CH of fc); 73.02 (d, JPC = 117 Hz, C-
P(O)Ph2 of fc), 73.26 (d, 2 C, JPC = 13 Hz, CH of fc); 79.61 (C-
CH2P(S)Ph2 of fc), 128.21 and 128.38 (2 ꢁ d, 4 C, 3JPC = 12 Hz, CHmeta
of P(O/S)Ph2); 131.38 (d, 4 C, 3JPC = 10 Hz, CHmeta of P(O/S)Ph2),
4
131.41 and 131.50 (2 ꢁ d, 2 C, JPC = 3 Hz, CHpara of P(O/S)Ph2),
131.62 (d, 4 C, 3JPC = 10 Hz, CHmeta of P(O/S)Ph2), 132.20 (d, 2 C,
1JPC = 79 Hz, Cipso of P(S)Ph2), 134.35 (d, 2 C, 1JPC = 106 Hz, Cipso of
P(O)Ph2). 31P{1H} NMR (CDCl3): δ 29.3 (s, P(O)Ph2), 41.4 (s,
P(S)Ph2). HR MS (ESI+): calcd for C35H3156FeOP2S ([M + H]+)
617.0915, found 617.0915.
13 0.15CH2Cl2, a yellow powdery solid.
3
2
1H NMR (CDCl3): δ 2.83 (d, JPH = 11.5 Hz with 195Pt-satellites:
3JPtH ≈ 47 Hz, 2 H, CH2), 3.36 (br s, 2 H, fc), 4.11 (vt, J0 = 1.8 Hz, 2 H,
1-(Diphenylthiophosphinoyl)-10-[(diphenylphosphinoyl)-
methyl]ferrocene (10). A solution of compound 6 (60 mg, 0.10
mmol) in acetone (2 mL) was treated with 30% aqueous hydrogen
peroxide (0.1 mL) while stirring in air and cooling in an ice bath. After
30 min, saturated aqueous Na2S2O3 (1 mL) was added, and stirring was
continued for another 15 min to decompose an excess of H2O2. The
organic layer was separated and the aqueous residue was washed with
diethyl ether. The combined organic layers were dried over MgSO4 and
evaporated, leaving a residue, which was taken up with ethyl acetate and
crystallized by addition of hexane (5 mL each). The orange-brown
fc), 4.69 (m, 2 H, fc), 5.11 (br s, 2 H, fc), 7.32ꢀ7.89 (m, 10 H, PPh2).
31P{1H} NMR (CDCl3): δ 0.6 (d, JPP = 18 Hz with 195Pt-satellites:
2
1JPtP = 3537 Hz), 5.0 (d, 2JPP = 18 Hz with 195Pt-satellites: 1JPtP = 3655
Hz). ESI+ MS: m/z 799 ([Pt(1)Cl]+), 762 ([Pt(1) ꢀ H]+). Anal. Calcd
for C35H30Cl2FeP2Pt 0.15CH2Cl2 (847.1): C 49.83, H 3.61. Found: C
3
49.79, H 3.67.
{μ-1jP:2kP0-1-(Diphenylphosphino)-10-[(diphenylphosphino)-
methyl]ferrocene}bis{[(2-(dimethylamino-kN)methyl)phenyl-
kC1]palladium(II)} (14). A solution of 1 (58 mg, 0.10 mmol) in
dichloromethane (2 mL) was added to solid [{(LNC)Pd(μ-Cl)}2] (55 mg,
0.10 mmol). The resulting clear orange solution was stirred for 1 h and
then slowly added to pentane (ca. 30 mL). The precipitated product was
filtered off, washed successively with diethyl ether/pentane (1:1) and
pentane, and dried under vacuum to give 14 as an orange solid in
quantitative yield (110 mg).
crystals of solvate 10 H2O were filtered off, washed with pentane, and
3
dried under vacuum. Yield: 45 mg (71%).
1H NMR (CDCl3): δ 3.39 (d, 2JPH = 12.2 Hz, 2 H, CH2), 3.87 (vt,
J0 ≈ 1.9 Hz, 2 H), 4.12 (m, 2 H), 4.30 and 4.47 (2 ꢁ vq, J0 ≈ 1.9 Hz, 2 H)
(CH of fc); 7.345ꢀ7.75 (m, 20 H, PPh2). 13C{1H} NMR (CDCl3): δ
32.41 (d, 1JPC = 67 Hz, CH2), 69.50 (2 C), 72.10 (d, 2 C, JPC = 2 Hz),
72.39 (d, 2 C, JPC = 10 Hz), 74.02 (d, 2 C, JPC = 12 Hz) (CH of fc); 75.31
1H NMR (CDCl3): δ 2.72 (d, 4JPH = 2.7 Hz, 6 H, NMe2), 2.80 (d,
4JPH = 2.6 Hz, 6 H, NMe2), 3.69 (d, 2JPH = 10.1 Hz, 2 H, PCH2), 3.93 (d,
4JPH = 2.2 Hz, 2 H, NCH2), 3.96 (d, 4JPH = 2.1 Hz, 2 H, NCH2), 4.19
(vq, J0 = 2.0 Hz, 2 H), 4.24 (br vt, 2 H), 4.27 (d of vt, J0 ≈ 0.5 and 1.8 Hz,
2 H), 4.44 (vt, J0 = 1.8 Hz, 2 H) (CH of fc); 6.24ꢀ6.32 (m, 2 H, C6H4),
6.40 (tt, J ≈ 7.6, 2.0 Hz, 2 H, C6H4), 6.77 (td, J = 7.3, 1.1 Hz, 1 H, C6H4),
6.84 (td, J = 7.3, 1.1 Hz, 1 H, C6H4), 6.92 (dd, J = 7.4, 1.1 Hz, 1 H,
C6H4), 7.00 (dd, J = 7.4, 1.1 Hz, 1 H, C6H4), 7.24ꢀ7.66 (m, 20 H,
PPh2). 31P{1H} NMR (CDCl3): δ 33.0 and 36.6 (2 ꢁ s). ESI+ MS: m/z
1083/1085 ([(1)(LNC)2Pd2Cl]+), 808 ([(1)(LNC)2Pd2]+). Anal. Calcd
C53H54Cl2FeN2P2Pd2 (1120.47): C 56.81, H 4.86, N 2.50. Found: C
56.82, H 5.22, N 2.36.
1
2
(d, JPC = 98 Hz, C-P(S)Ph2 of fc), 79.69 (d, JPC = 2 Hz, C-
3
CH2P(O)Ph2 of fc), 128.19 and 128.41 (2 ꢁ d, 4 C, JPC = 12 Hz,
CHmeta of P(O/S)Ph2); 131.21 (d, 2 C, 4JPC = 3 Hz, CHpara of P(O/
S)Ph2), 131.22 and 131.58 (2 ꢁ d, 4 C, 3JPC = 10 Hz, CHmeta of P(O/
S)Ph2), 131.68 (d, 2 C, 4JPC = 3 Hz, CHpara of P(O/S)Ph2), 132.39 (d, 2
C, 1JPC = 98 Hz, Cipso of P(O)Ph2), 134.42 (d, 2 C, 1JPC = 87 Hz, Cipso of
P(S)Ph2). 31P{1H} NMR (CDCl3): δ 28.8 (s, P(O)Ph2), 42.2 (s,
P(S)Ph2). HR MS (ESI+): calcd for C35H3156FeOP2S ([M + H]+)
617.0915, found 617.0915.
Dichlorido{1-(diphenylphosphino)-10-[(diphenylphosphino)-
methyl]ferrocene-j2P,P0}nickel(II) (11). A solution of 1 (59 mg,
0.10 mmol) in acetone (3 mL) was added to a suspension of [NiCl2-
(dme)] (22 mg, 0.10 mmol) in absolute ethanol (3 mL). The reaction
mixture turned brown, and the product started to separate. The mixture
was stirred at room temperature for 30 min and then stored at 0 °C
overnight. The solid product was filtered off, washed with diethyl ether
and pentane, and dried under vacuum to afford complex 11 as a dark
olive green microcrystalline solid. Yield: 66.5 mg (95%).
Reaction of [(LNC)Pd(MeCN)2]ClO4 with 1. Complex [(LNC)-
Pd(MeCN)2]ClO4 (42.5 mg, 0.10 mmol) and 1 (58 mg, 0.10 mmol)
were dissolved in dichloromethane (3 mL). After stirring for 90 min, the
mixture was filtered through a pad of Celite and the filtrate was evaporated
under vacuum, leaving a residue, which was washed with diethyl ether
and pentane and dried under vacuum. Yield: 91 mg (quant.), ochre
powdery solid.
ESI+ MS: m/z 661 ([NiCl(1)]+), 627. Anal. Calcd for (%) for
C35H30Cl2FeNiP2 (698.0): C 60.22, H 4.33. Found: C 60.17, H 4.39.
Dichlorido{1-(diphenylphosphino)-10-[(diphenylphosphino)-
methyl]ferrocene-j2P,P0}palladium(II) (12). A solution of 1 (58 mg,
0.10 mmol) in dichloromethane (4 mL) was added to solid [PdCl2(cod)]
(28.5 mg, 0.10 mmol). The resulting deep red-orange solution was stirred for
31P{1H} NMR (CDCl3): δ 2.4 and 27.7 (2 ꢁ d, 2JPP = 40 Hz; isomer
A); 8.0 and 34.4 (2 ꢁ d, 2JPP = 42 Hz; isomer B). IR (Nujol): 1645 m,
1580 m, 1163 m, ν3(ClO4) 1097 vs, 1026 w, 998 w, 839 m, 725 s, 698 s,
ν4(ClO4) 623 s, 487 s cmꢀ1. ESI+ MS: m/z 808 ([(LNC)Pd(1)]+), 675
([Pd(1) + H]+). Anal. Calcd for C44H42ClFeNO4P2Pd (908.4): C
58.17, H 4.66, N 1.54. Found: C 57.81, H 4.85, N 1.72.
4400
dx.doi.org/10.1021/om2004805 |Organometallics 2011, 30, 4393–4403

Organometallics
ARTICLE
SuzukiꢀMiyaura Cross-Coupling with Phenylboronic Acid.
A Schlenk tube was charged with 4-bromacetophenone (398 mg,
2.0 mmol), phenylboronic acid (293 mg, 2.4 mmol), potassium carbonate
(663 mg, 4.8 mmol), bis(2-methoxyethyl) ether (internal standard; 134 mg,
1.0 mmol), and dioxane (10 mL). Palladium precatalyst (2.0 or 0.2 μmol)
was added as a stock solution in 1,2-dichloroethane, and the reaction
mixture was heated at 100 °C in an oil bath for 24 h under an argon
atmosphere. Conversions were determined by 1H NMR spectroscopy. The
reactions with 4-chloroacetophenone were carried out similarly using
4-chloracetophenone (155 mg, 1.0 mmol), phenylboronic acid (146 mg,
1.2 mmol), potassium carbonate (332 mg, 2.4 mmol), and bis(2-meth-
oxyethyl) ether (67 mg, 0.5 mmol) in dioxane (5 mL). Palladium
precatalyst (10 μmol) was introduced as a solution in 1,2-dichloroethane
(0.25 mL), and the reaction mixture was heated at 100 °C in an oil bath for
24 h under an argon atmosphere. “Instant” catalysts were prepared by
stirring the Pd source (10 μmol of Pd) with the appropriate ligand (11 μmol)
in 1,2-dichloroethane (0.25 mL) for 5 min.
All geometric calculations were performed with a recent version of the
PLATON program, and the numerical values are rounded with respect
to their estimated standard deviations given with one decimal. CCDC-
822092ꢀ822098 contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
’ ASSOCIATED CONTENT
S
Supporting Information. Crystal structure of 3, conven-
b
tional displacement ellipsoid plots for all crystal structures
presented in this article, additional plots of magnetochemical
data, a summary of X-ray crystallographic data, and CIF files for
all structurally characterized compounds. This material is avail-
able free of charge via the Internet at http://pubs.acs.org.
SuzukiꢀMiyaura Cross-Coupling Reactions with Butyl-,
2-Phenylethyl-, and Styrylboronic Acids. A Schlenk tube was
charged with 4-bromacetophenone (19.9 mg, 0.1 mmol), appropriate
boronic acid (0.12 mmol), potassium carbonate (33.2 mg, 0.24 mmol),
bis(2-methoxyethyl) ether (internal standard; 6.7 mg, 0.05 mmol), and
dry dioxane (1 mL). Palladium precatalyst (5.0 μmol) was dissolved in
1,2-dichloroethane (0.25 mL) and added to the mixture, and the
reaction vessel was transferred to an oil bath preheated to 100 °C.
The reaction mixture was analyzed by standard proton NMR spectros-
copy. When palladium(II) acetate or tris(dibenzylideneacetone)-
dipalladium(0) were employed as the Pd source, the precatalyst was
generated in situ by reacting the Pd-precursor (5.0 μmol) with the
appropriate ligand (5.5 μmol) in 1,2-dichloroethane (0.25 mL) for 5 min.
Pd-Catalyzed Cyanation of Aryl Bromides. A pressure Schlenk
tube was charged with aryl halide (1.0 mmol), Na2CO3 (106 mg;
’ AUTHOR INFORMATION
Corresponding Author
*E-mail: stepnic@natur.cuni.cz.
’ ACKNOWLEDGMENT
This work was financially supported by the Czech Science
Foundation (project no. P207/10/0176). Special thanks are due
to Dr. Jana Poltierovꢁa Vejpravovꢁa from Institute of Physics,
Academy of Sciences of the Czech Republic, and the Department
of Inorganic Chemistry, Faculty of Science, Charles University in
Prague, for magnetic measurements.
’ DEDICATION
1.0 mmol), and K4[Fe(CN)6] 3H2O (106 mg; 0.25 mmol). A solution
3
of catalyst precursor (5 μmol) in dry DMF (3 mL) was added, and the
reaction vessel was sealed and heated in an oil bath maintained at 130 °C for
16 h. Conversions were determined from 1H NMR spectra.
Dedicated to Professor Jaroslav Podlaha on the occasion of his
75th birthday.
X-ray Crystallography. Single crystals suitable for X-ray diffrac-
tion measurements were grown by cooling solutions in warm aqueous
acetic acid (8: yellow-orange prism, 0.10 ꢁ 0.13 ꢁ 0.30 mm3) or ethyl
acetate/hexane (3: orange plate, 0.20 ꢁ 0.26 ꢁ 0.62 mm3; 9: orange
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dx.doi.org/10.1021/om2004805 |Organometallics 2011, 30, 4393–4403

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39, 2751. (e) Fihri, A.; Meunier, P.; Hierso, J.-C. Coord. Chem. Rev. 2007,
251, 2017.
(16) Dppf was first reported in 1965: Sollot, G. P.; Snead, J. L.;
Portnoy, S.; Peterson W. R. Mertwoy, H. E. U. S. Dept. Com., Office Tech.
Serv., PB Rep. 1965, vol. II, pp 441ꢀ452; Chem. Abstr. 1965, 63, 18174.
(17) Yamamoto, Y.; Tanase, T.; Mori, I.; Nakamura, Y. J. Chem. Soc.,
Dalton Trans. 1994, 3191.
(9) Ph2PfcPR2, R = alkyl or cycloalkyl: (a) Cullen, W. R.; Kim, T. J.;
Einstein, F. W. B.; Jones, T. Organometallics 1985, 4, 346. (b) Kahn, S. L.;
Breheney, M. K.; Martinak, S. L.; Fosbenner, S. M.; Seibert, A. R.; Kassel,
W. S.; Dougherty, W. G.; Nataro, C. Organometallics 2009, 28, 2119.
(c) Milton, E. J.; Fuentes, J. A.; Clarke, M. L. Org. Biomol. Chem. 2009,
7, 2645. (d) Liu, L. K.; Lin, S. C. Bull. Inst. Chem., Acad. Sin. 1992, 39, 31.
Chem. Abstr. 1993, 118, 234207 and refs 5a, 5c, 6b, 7a, and 8l.
Ph2PfcPR2, R = an aryl group different from C6H5:. (e) Yamashita,
M.; Vicario, J. V. C.; Hartwig, J. F. J. Am. Chem. Soc. 2003, 125, 16347.
Ph2PfcP(OR)2:(f) Laly, M.; Broussier, R.; Gautheron, B. Tetrahedron
Lett. 2000, 41, 1183. (g) Hierso, J.-C.; Lacassin, F.; Broussier, R.;
Amardeil, R.; Meunier, P. J. Organomet. Chem. 2004, 689, 766.
(10) Another approach toward desymmetrization of dppf is repre-
sented by semioxidation to dppfE (E = O or S). For representative
(18) Compounds similar to A, bearing the phosphorus atoms in
β-positions with respect to the ferrocene unit, were prepared from
fulvenes: (a) [Fe(η5-C5H4CMe2PPh2)2]): Kettenbach, R. T.; Bonrath,
W.; Butensch€on, H. Chem. Ber. 1993, 126, 1657. (b) [Fe(η5-C5Me2Ph2-
(CH2PPh2))2]): Donovalova, J.; Jackson, C. R.; Mintz, E. A. J. Organo-
met. Chem. 1996, 512, 85. (c) [Fe(η5-C5Me4CH(Me)PPh2)2]):
Bensley, D. M., Jr.; Mintz, E. A. J. Organomet. Chem. 1988, 353, 93.
(d) [Fe(η5-C5H4CR2PMe2)2]) (R2 = (CH2)5 or Me2), [Fe(η5-
C5Me4CH2PMe2)2]): Bellabarba, R. M.; Clancy, G. P.; Gomes, P. T.;
Martins, A. M.; Rees, L. H.; Green, M. L. H. J. Organomet. Chem. 2001,
640, 93. They are also accessible via nucleophilic substitution from 1,10-
bis(1-hydroxylalkyl)ferrocenes:(e) [Fe(η5-C5H4CH(Me)PPh2)2]):
Watanabe, M. Tetrahedron Lett. 1995, 36, 8991. (f) [Fe(η5-C5H4CH-
(Ph)PPh2 BH3)2]): Schwink, L.; Knochel, P. Chem.—Eur. J. 1998,
3
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Organometallics
ARTICLE
4, 950. (g) [Fe(η5-C5H4CH(Ph)PPh2)2]): Lu, Y.; Plocher, E.; Hu, Q.-S.
Adv. Synth. Catal. 2006, 348, 841.
(19) Stꢀepniꢀcka, P.; Baꢀse, T. Inorg. Chem. Commun. 2001, 4, 682.
2009, 351, 643. (d) Sundermeier, M.; Zapf, A.; Beller, M. Eur. J. Inorg.
Chem. 2003, 3513 (review).
(39) A. Suzuki was awarded the Nobel Prize in 2010 (together with
E. Negishi and R. F. Heck) “for the development of palladium-catalyzed
cross coupling”.
ꢀ
(20) Olah, G. A.; Narang, S. C. Tetrahedron 1982, 38, 2225.
(21) For application of this methodology in ferrocene
ꢀ
ꢀ
ꢀ
chemistry, see: (a) Sebesta, R.; Toma, S.; Saliꢀsovꢁa, M. Eur. J. Org. Chem.
(40) Littke, A. F.; Fu, G. C. Angew. Chem., Int. Ed. 2002, 41, 4176
(review).
2002, 692. (b) Lamaꢀc, M.; Císaꢀrovꢁa, I.; Stꢀepniꢀcka, P. J. Organomet. Chem.
2005, 690, 4285. (c) Sebesta, R.; Bilꢀcík, F.; Horvꢁath, B. Eur. J. Org. Chem.
ꢀ
(41) Drew, D.; Doyle, J. R. Inorg. Synth. 1972, 13, 47.
(42) Cope, A. C.; Friedrich, E. C. J. Am. Chem. Soc. 1968, 90, 909.
2008, 5157.
ꢀ
(22) The crystal structure of 3 is presented in the Supporting
Information (Figure S1).
(43) Stꢀepniꢀcka, P.; Lamaꢀc, M.; Císaꢀrovꢁa, I. Polyhedron 2004, 23, 921.
(44) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G. L.;
Giacovazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Polidori, G.; Spagna,
R. J. Appl. Crystallogr. 1999, 32, 115.
(45) Sheldrick, G. M. SHELXL97: Program for Crystal Structure
Solution from Diffraction Data; University of G€ottingen: G€ottingen,
Germany, 1986.
(23) dppfO2: (a) Pilloni, G.; Corain, B.; Degano, M.; Longato, B.;
Zanotti, G. J. Chem. Soc., Dalton Trans. 1993, 1777. dppfS2: (b) Pilloni,
G.; Longato, B.; Bandoli, G.; Corain, B. J. Chem. Soc., Dalton Trans.
1997, 819. (c) Fang, Z.-G.; Hor, T. S. A.; Wen, Y.-S.; Liu, L.-K.; Mak,
T. C. W. Polyhedron 1995, 14, 2403.
(24) To decide whether any correction for diamagnetic contribution
to the magnetic susceptibility is necessary, the molar susceptibility data,
calculated from the temperature dependence of magnetization, were
critically evaluated. The diamagnetic contribution (field-independent)
was found to be about 2 orders of magnitude lower than the para-
magnetic signal, which is far below experimental error. Therefore, no
additional correction was made to the molar magnetic susceptibility
before further analysis.
(46) Sheldrick, G. M. SHELXL97: Program for Crystal Structure
Refinement from Diffraction Data; University of G€ottingen: G€ottingen,
Germany, 1997.
(47) van der Sluis, P.; Spek, A. L. Acta Crystallogr., Sect. A, Fundam.
Crystallogr. 1990, 46, 194.
(48) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7.
(25) [NiCl2(PPh3)2]: (a) μ = 3.07 μB: Venanzi, L. M. J. Chem. Soc.
1958, 719. (b) μ = 3.39 μB at 273 K: Cotton, F. A.; Faut, O. D.;
Goodgame, D. M. L. J. Am. Chem. Soc. 1961, 83, 344. (c) The value
reported for [NiCl2(dppf)] is much higher (μ = 3.7 μB): Corain, B.;
Longato, B.; Favero, G.; Ajꢂo, D.; Pilloni, G.; Russon, U.; Kreissl, F. R.
Inorg. Chim. Acta 1989, 157, 259.
(26) Casellato, U.; Ajꢁo, D.; Valle, G.; Corain, B.; Longato, B.;
Graziani, R. J. Crystallogr. Spectrosc. Res. 1988, 18, 583.
(27) The value was calculated from the data deposited at the
Cambridge Crystallographic Data Centre (refcode KADXAO).
(28) The perpendicular distance of P2 from the Cp2 plane is
0.165(1) Å.
(29) (a) Pregosin, P. S.; Kunz, R. W. 31P and 13C NMR of Transition
Metal Phosphine Complexes. In NMR Basic Principles and Progress;
Diehl, P., Fluck, E., Kosfeld, R., Eds.; Springer Verlag: Heidelberg, 1979:
Vol. 2, Chapter E, p 16. (b) Hartley, F. R. The Chemistry of Platinum and
Palladium; Applied Science: London, 1973; Chapter 7, pp 136ꢀ140.
(30) Reaction between A and any “PtCl2” source has not been
studied.
(31) Hayashi, T.; Konishi, M.; Kobori, Y.; Kumada, M.; Higuchi, T.;
Hirotsu, K. J. Am. Chem. Soc. 1984, 106, 158.
(32) Butler, I. R.; Cullen, W. R.; Kim, T.-J.; Rettig, S. J.; Trotter, J.
Organometallics 1985, 4, 972.
(33) Clemente, D. A.; Pilloni, G.; Corain, B.; Longato, B.; Tiripicchio-
Camellini, M. Inorg. Chim. Acta 1986, 115, L9.
(34) Muller, A. Acta Crystallogr., Sect. E: Struct. Rep. Online 2007,
63, m210.
(35) Perpendicular distances of P2 atoms from the Cp2 ring planes
are 0.751(1) Å for 12 and 0.805(1) Å for 13. These values are
considerably larger than for the Ni(II) complex 11, which corresponds
with the trend in the P1 P2 distances: 3.391(1) Å (12) ≈ 3.396(1) Å
3 3 3
(13) , 3.847(2) Å (11).
(36) Ma, J.-F.; Yamamoto, Y. Inorg. Chim. Acta 2000, 299, 164.
(37) (a) Miyaura, N. Metal Catalyzed Cross-Coupling Reactions of
Organoboron Compounds with Organic Halides. In Metal-Catalyzed
Cross-Coupling Reactions, 2nd ed.; de Meijere, A., Diederich, F., Eds.;
Wiley-VCH: Weinheim, 2004; Vol. 1, pp 41ꢀ123. (b) Miyaura, N.;
Suzuki, A. Chem. Rev. 1995, 95, 2457. (c) Suzuki, A. J. Organomet. Chem.
1999, 576, 147. (d) Miyaura, N. J. Organomet. Chem. 2002, 653, 54
(historical note).
(38) (a) Schareina, T.; Zapf, A.; Beller, M. Chem. Commun.
2004, 1388. (b) Schareina, T.; Zapf, A.; M€agerlein, W.; M€uller, N.;
Beller, M. Tetrahedron Lett. 2007, 48, 1087. (c) Schareina, T.; Jackstell,
R.; Schulz, T.; Zapf, A.; Cotte, A.; Gotta, M.; Beller, M. Adv. Synth. Catal.
4403
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