Dinuclear palladium, nickel, and rhodium complexes based on 1,3-Bis[(2-(diphenylphosphino)benzylidene)-amino]propan-2-ol

Article abstract of DOI:10.1021/om970464e

A new dinucleating ligand, 1,3-bis[(2-(diphenylphosphino)benzylidene)amino]-propan-2-ol (L¹H), has been synthesized from 2-(diphenylphosphino)benzaldehyde and 1,3-diaminopropanol in 85% yield. Complexation with palladium, nickel, and rhodium salts gave the following dinuclear complexes: [M₂(L¹)(OAc)₂](BF₄) (6, M = Pd; 7, M = Ni), [Pd₂(L¹)Me₂]-(BF₄) (10), and [Rh₂(L¹)(CO)₂](BF₄) (11). In these complexes the two metals are bridged by the secondary alkoxy group of the ligand which keeps them at a fixed distance from each other. X-ray structure determinations of [Pd₂(L¹)(OAc)₂](BF₄) (6), [Pd₂(L¹)Me₂](BF₄) (10) and [Rh₂(L¹)(CO)₂](BF₄) (11) showed that both metals are in a square-planar environment and that the metal-metal distance varies from 3.5 to 3.7 ?. The related complex Pd₂(L¹H)Me₂Cl₂ (9) has also been characterized crystallographically. In palladium complex 9, the alkoxy group does not bridge the two metal centers and a much longer metal-metal distance of 7.5 ? is found. Furthermore, the ligand L¹H is capable of forming heterodinuclear complexes. Reaction of L¹H first with Pd(OAc)₂ and subsequently with Rh₂(CO)₄Cl₂ provided the heterodinuclear complex [PdRh(L¹H)(Cl)(CO)](BF₄).

Full text of DOI:10.1021/om970464e

636
Organometallics 1998, 17, 636-644
Din u clea r P a lla d iu m , Nick el, a n d Rh od iu m Com p lexes
Ba sed on 1,3-Bis[(2-(d ip h en ylp h osp h in o)ben zylid en e)-
a m in o]p r op a n -2-ol
Esther K. van den Beuken,† Nora Veldman,‡ Wilberth J . J . Smeets,‡
Anton L. Spek,‡ and Ben L. Feringa*,†
Department of Organic and Molecular Inorganic Chemistry, University of Groningen,
Nijenborgh 4, 9747 AG Groningen, The Netherlands, and Bijvoet Center for Biomolecular
Research, Department of Crystal and Structural Chemistry, Utrecht University,
Padualaan 8, 3584 CH Utrecht, The Netherlands
Received J une 4, 1997
A new dinucleating ligand, 1,3-bis[(2-(diphenylphosphino)benzylidene)amino]-propan-2-
ol (L1H), has been synthesized from 2-(diphenylphosphino)benzaldehyde and 1,3-diamino-
propanol in 85% yield. Complexation with palladium, nickel, and rhodium salts gave the
following dinuclear complexes: [M2(L1)(OAc)2](BF4) (6, M ) Pd; 7, M ) Ni), [Pd2(L1)Me2]-
(BF4) (10), and [Rh2(L1)(CO)2](BF4) (11). In these complexes the two metals are bridged by
the secondary alkoxy group of the ligand which keeps them at a fixed distance from each
other. X-ray structure determinations of [Pd2(L1)(OAc)2](BF4) (6), [Pd2(L1)Me2](BF4) (10)
and [Rh2(L1)(CO)2](BF4) (11) showed that both metals are in a square-planar environment
and that the metal-metal distance varies from 3.5 to 3.7 Å. The related complex
Pd2(L1H)Me2Cl2 (9) has also been characterized crystallographically. In palladium complex
9, the alkoxy group does not bridge the two metal centers and a much longer metal-metal
distance of 7.5 Å is found. Furthermore, the ligand L1H is capable of forming heterodinuclear
complexes. Reaction of L1H first with Pd(OAc)2 and subsequently with Rh2(CO)4Cl2 provided
the heterodinuclear complex [PdRh(L1H)(Cl)(CO)](BF4).
In tr od u ction
ladium complex catalyzes the hydration of acetonitrile
to acrylamide via a bimetallic pathway.6
The design of dinucleating ligands which can form
homo- or heterodinuclear transition-metal complexes
with well defined geometries is of considerable interest,
considering the rapidly evolving area of bimetallic
catalysis.1 Especially, dinuclear copper and iron com-
plexes are widely studied for mimicking the bimetallic
sites in various enzymes;2 e.g. Cu2 sites in hemocyanine
or tyrosinase and Fe2 sites in hemerythrin or methane
monooxygenase. Often aminomethylated phenols are
used as ligands for these types of dinuclear complexes,
in which an additional bridging donor atom, in most
cases a phenolic oxygen atom, holds the two metals at
a fixed distance from each other.2 The corresponding
thiophenols are also very useful as dinucleating ligands,
and Robson and co-workers showed that sulfur functions
as a bridging atom in dinuclear copper,3 nickel,4 and
palladium complexes.5 Interestingly, the dinuclear pal-
Instead of a (thio)phenoxy bridge in dinucleating
ligands, it is also possible to use a secondary alkoxy
bridge, which furnishes ligands of greater stereochem-
ical flexibility. These ligands can easily be synthesized
via a condensation reaction of 1,3-diaminopropan-2-ol
or 1,5-diaminopentan-3-ol and aldehydes. The struc-
tural and electronic properties of dinuclear copper,7
manganese,8 and nickel9 complexes of these ligands
have been studied extensively, and these properties
were shown to depend on the metal, the endogenous
backbone, the donor atoms, and the exogenous bridging
(4) Bond, A. M.; Haga, M.; Creece, I. S.; Robson, R.; Wilson, J . C.
Inorg. Chem. 1988, 27, 712.
(5) (a) Hoskins, B. F.; Robson, R.; Williams, G. A.; Wilson, J . C.
Inorg. Chem. 1991, 30, 4160. (b) Louey, M.; Nichols, P. D.; Robson, R.
Inorg. Chim. Acta 1980, 47, 87. (c) Louey, M.; McKenzie, C. J .; Robson,
R. Inorg. Chim. Acta 1986, 111, 107. (d) Crossley, T. E.; Hoskins, B.
F.; McDonald, I. A. S.; Robson, R. Inorg. Chim. Acta 1986, 111, 99. (e)
Hughes, J . G.; Robson, R. Inorg. Chim. Acta 1979, 35, 87.
(6) McKenzie, C. J .; Robson, R. J . Chem. Soc., Chem. Commun. 1988,
112.
† University of Groningen.
‡ Utrecht University.
(1) (a) Go¨bel, M. W. Angew. Chem., Int. Ed. Engl. 1994, 33, 1141.
(b) Steinhagen, H.; Helmchen, G. Angew. Chem., Int. Ed. Engl. 1996,
35, 2339. (c) Broussard, M. E.; J uma, B.; Train, S. G.; Peng, W.-J .;
Laneman, S. A.; Stanley, G. G. Science 1993, 260, 1784.
(2) (a) Bioinorganic Chemistry of Copper; Karlin, K. D., Tyekla´r, Z.,
Eds.; Chapman and Hall: New York, 1993. (b) Bioinorganic Catalysis;
Reedijk, J ., Ed.; Dekker: New York, 1993. (c) Sorrell, T. N. Tetrahedron
1989, 45, 3. (d) Kitajima, N.; Moro-oka, Y. Chem. Rev. (Washington,
D.C.) 1994, 94, 737. (e) Vigato, P. A.; Tamburini, S.; Fenton, D. E.
Coord. Chem. Rev. 1990, 106, 25. (f) Lubben, M.; Feringa, B. L. J . Org.
Chem. 1994, 59, 2227. (g) Lubben, M.; Hage, R.; Meetsma, A.; Bijma,
K.; Feringa, B. L. Inorg. Chem. 1995, 34, 2217.
(7) (a) Mazurek, W.; Kennedy, B. J .; Murray, K. S.; O’Connor, M.
J .; Rodgers, J . R.; Snow, M. R.; Wedd, A. G.; Zwack, P. R. Inorg. Chem.
1985, 24, 3258. (b) Satcher, J . H., J r.; Balch, A. L. Inorg. Chem. 1995,
34, 3371. (c) Mazurek, W.; Berry, K. J .; Murray, K. S.; O’Connor, M.
J .; Snow, M. R.; Wedd, A. G. Inorg. Chem. 1982, 21, 3071.
(8) (a) Zhang, Z.-Y.; Brouca-Cabarrecq, C.; Hemmert, C.; Dahan, F.;
Tuchagues, J .-P. J . Chem. Soc., Dalton Trans. 1995, 1453. (b) Higuchi,
C.; Sakiyama, H.; Okawa, H.; Isobe, R.; Fenton, D. E. J . Chem. Soc.,
Dalton Trans 1994, 1097.
(9) (a) Kruger, P. E.; Moubaraki, B.; Murray, K. S.; Tiekink, E. R.
T. J . Chem. Soc., Dalton Trans. 1994, 2129. (b) Mazurek, W.; Bond,
A. M.; O’Connor, M. J .; Wedd, A. G. Inorg. Chem. 1986, 25, 906. (c)
Mikuriya, M.; Sasaki, T.; Anjiki, A.; Ikenoue, S.; Tokii, T. Bull. Chem.
Soc. J pn. 1992, 65, 334.
(3) Iliopoulos, P.; Murray, K. S.; Robson, R.; Wilson, J .; Williams,
G. A. J . Chem. Soc., Dalton Trans. 1987, 1585.
S0276-7333(97)00464-0 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 01/27/1998

Dinuclear Pd, Ni, and Rh Complexes
Organometallics, Vol. 17, No. 4, 1998 637
Sch em e 2. Com p lexa tion of L1H w ith P d (OAc)2
a n d Ni(OAc)2
F igu r e 1. General structure of complexes of dinucleating
iminophosphine ligands.
Sch em e 1. Syn th esis of 5 (L1H)
ligand. The nature of the exogenous bridging ligand can
be a single-atom donor (OR-, Cl-, etc.) or a two-atom
donor moiety (e.g. pyrazolate or acetate).
Following our interest in bimetallic complexes and
catalysis,10 we have focused on iminophosphine dinucle-
ating ligands with a secondary alkoxy bridging unit. The
new ligand 5 contains a N2P2O donor set and comprises
a compartmental dinucleating ligand system.2e Com-
plexation with palladium, nickel, and rhodium gener-
ates complexes with the general structures 1 and 2
(Figure 1).
We describe here the synthesis of 1,3-bis[(2-(diphen-
ylphosphino)benzylidene)amino]-propan-2-ol, which is a
highly effective ligand for the preparation of homodi-
nuclear palladium, nickel, and rhodium complexes as
well as for the preparation of a heterodinuclear rhodium
palladium complex. Furthermore, the crystal structures
of several new bimetallic complexes of types 1 and 2
and the initial results of these dinuclear complexes in
catalysis are reported.
the alkoxy group bridges between the two palladium
centers (Scheme 2). Crystals suitable for X-ray analysis
were obtained from CH2Cl2/pentane (vide infra).
The 31P NMR spectrum showed one absorption at 30.5
ppm, and the electrospray mass spectrum11 showed an
isotope pattern at m/z 963 characteristic for [Pd2(L1)-
(OAc)2]+ and at m/z 453 for [Pd2(L1)(OAc)]2+. When 1
equiv of trimethylsilyl triflate was added to a solution
of 6 in dichloromethane, one acetoxy group was removed
from the dinuclear palladium complex. The absorption
in the 31P NMR spectrum is shifted to 34.2 ppm and
only one signal is shown, which indicates that the two
phosphorus atoms are identical. In the 19F NMR
spectrum, two absorptions are observed at -152.3 ppm
for BF4 and at -79.7 ppm for OTf. In the electrospray
mass spectrum two isotope patterns were observed: one
at m/z 453 for [Pd2(L1)(OAc)]2+ and one at m/z 462 for
[Pd2(L1)(OAc)‚H2O]2+. No M+ peaks were found at m/z
953. These data are in accordance with dication 8, in
which one exogenous acetate ligand and the oxygen of
the endogenous ligand bridge the two palladium centers.
The dinuclear nickel complex was synthesized analo-
gously to the palladium complex 6 from L1H and Ni-
(OAc)2 in methanol. Anion exchange with NaBF4 gave
[Ni2(L1)(OAc)2](BF4) (7), which is paramagnetic. Elec-
trospray mass spectroscopy showed an isotope pattern
at m/z 867 characteristic for [Ni2(L1)(OAc)2]+. Complex
7 was furthermore characterized by elemental analysis.
The crystal structure of 6 together with the adopted
numbering scheme is shown in Figure 2. Selected bond
distances and bond angles are collected in Table 1;
details of the X-ray analysis are summarized in Table
5. In Figure 2, the pentadentate binucleating function
of the ligand is clearly shown. The palladium centers
Resu lts
Syn th esis of 1,3-Bis[(2-(d ip h en ylp h osp h in o)ben -
zylid en e)a m in o]p r op a n -2-ol (L1H). The pentaden-
tate ligand 1,3-bis[(2-(diphenylphosphino)benzylidene)-
amino]propan-2-ol (5; L1H) was synthesized by conden-
sation of 2 equiv of 2-(diphenylphosphino)benzaldehyde
(3) and 1,3-diaminopropan-2-ol (4) under Dean-Stark
conditions in toluene (Scheme 1). Crystallization from
dichloromethane/pentane gave 5 in 85% yield as a
yellow powder which was air stable. The 31P NMR
spectrum showed one absorption at -12.0 ppm. The
structure of ligand 5 was further secured by 1H and 13C
NMR spectroscopy, mass spectrometry, and elemental
analysis.
Syn th esis of [M2(L1)(OAc)2](BF 4) (M ) P d , Ni).
Complexation of L1H with 2 equiv of Pd(OAc)2 in dichlo-
romethane and subsequent anion exchange with NaBF4
provided the dinuclear palladium complex 6, in which
(10) (a) 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. (b) Gelling, O. J .; Feringa, B. L. J . Am.
Chem. Soc. 1990, 112, 7599. (c) Rispens, M. T.; Gelling, O. J .; de Vries,
A. H. M.; Meetsma, A.; van Bolhuis, F.; Feringa, B. L. Tetrahedron
1996, 52, 3521.
(11) In the electrospray mass spectrum, the observed peaks are
related to mass/charge ratio. See for more information: (a) Bruins, A.
P. Trends Anal. Chem. 1994, 13, 37. (b) Bruins, A. P. Trends Anal.
Chem. 1994, 13, 81. (c) Smith, R. D.; Light-Wahl, K. J . Biol. Mass
Spectrom. 1993, 22, 493.

638 Organometallics, Vol. 17, No. 4, 1998
van den Beuken et al.
F igu r e 3. ORTEP plot of 9 at the 50% probability level.
Sch em e 3. Syn th esis of 9
F igu r e 2. ORTEP plot of 6 at the 50% probability level.
Ta ble 1. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) of Com p ou n d 6 (Sta n d a r d Devia tion s
in P a r en th eses)
Pd(1)-O(1)
Pd(1)-N(1)
Pd(1)-P(1)
Pd(1)-O(2)
Pd(2)-O(1)
2.076(4)
1.978(6)
2.199(3)
1.986(6)
2.073(5)
Pd(2)-N(2)
Pd(2)-P(2)
Pd(2)-O(4)
Pd(1)‚‚‚.Pd(2)
2.006(6)
2.199(3)
2.017(7)
3.497(2)
P(1)-Pd(1)-O(1) 173.56(15) P(2)-Pd(2)-O(4)
86.6(2)
95.36(17)
95.2(2)
82.5(2)
175.6(3)
P(1)-Pd(1)-O(2)
P(1)-Pd(1)-N(1)
O(1)-Pd(1)-O(2)
O(1)-Pd(1)-N(1)
91.22(17) P(2)-Pd(2)-N(2)
91.04(17) O(1)-Pd(2)-O(4)
94.7(2)
83.4(2)
O(1)-Pd(2)-N(2)
O(4)-Pd(2)-N(2)
Pd(1)-O(1)-Pd(2) 114.9(2)
O(2)-Pd(1)-N(1) 172.3(2)
P(2)-Pd(2)-O(1) 175.2(2)
rings, and the torsion angle of C(1), C(6), C(7), and N(1)
is -15.6(11)°. On the other side of the molecule a
smaller torsion angle of -3.3(12)° for C(17), C(12), C(11),
and N(2) is found. The Pd-O, Pd-N, and Pd-P
distances all are in the normal range.12
adopt a square-planar geometry. The two palladium
atoms are bridged by the oxygen atom O(1) of the
secondary alkoxy substituent from the ligand. The
remaining square-planar coordination sites are occupied
by P(1), N(1), and O(2) for Pd(1) and P(2), N(2), and O(3)
for Pd(2). Remarkably, two terminal acetoxy groups are
found, not one bridging acetoxy group as is usually
observed in dinuclear nickel and copper complexes with
an endogenous secondary alkoxy ligand.7,9 In the
crystal structure, one acetate is disordered by replace-
ment of the acetate group by a chloride atom (Cl:OAc
(%) ) 10.8(9):89.2(9)). This exchange is probably due
to the fact that the initial preparation of crystalline 6
was performed in refluxing chloroform instead of dichlo-
romethane, which may have led to the incorporation of
some chloride. Therefore, later experiments were all
performed in dichloromethane, in which the probability
of halide exchange is smaller. Indeed, analytically pure,
chloride-free complex 6 was obtained in this manner.
The intramolecular Pd‚‚‚Pd distance of 3.497(2) Å is
slightly longer than the metal-metal distance found in
dinuclear nickel and copper complexes with a secondary
alkoxy bridge and a bridging exogenous ligand.7,9 The
deviations from the least-squares plane through the Pd-
(1), P(1), O(1), O(2), and N(1) atoms are 0.0303(6), 0.079-
(2), 0.087(4), 0.093(5), and -0.103(5) Å, respectively, and
the equivalent values for the Pd(2), P(2), O(1), O(4), and
N(2) plane are -0.060(3), 0.021(3), 0.023(4), 0.008(7),
and 0.008(6) Å, respectively. The dihedral angle be-
tween the two planes is 115.38(19)°, showing a consid-
erable bending of the two square-planar coordination
sites toward each other. The Pd-O-Pd angle, which
is sensitive to the twisting of the molecule and which
becomes smaller upon increased bending,9c is 114.9(2)°.
The imine moieties are not in the plane of the phenyl
Com p lexa tion of L1H w ith P d (cod )MeCl (cod )
1,5-Cycloocta d ien e). The reaction of L1H with 2 equiv
of Pd(cod)MeCl in THF yielded a white-yellow precipi-
tate (Scheme 3). Crystallization from dichloromethane/
pentane provided pale yellow crystals (43% yield) of
dinuclear palladium complex 9, which were suitable for
X-ray analysis (vide infra). In the 31P NMR spectrum
one absorption was obtained at 35.3 ppm. In the 1H
NMR spectrum, the hydroxyl proton was observed as a
broad signal at 4.1 ppm, which indicates that the oxygen
atom of the ligand does not bridge the two palladium
centers. The methyl resonance appears as a doublet at
0.55 ppm (J ) 2.93 Hz). The magnitude of this proton-
phosphorus coupling indicates a cis relationship be-
tween the methyl group and phosphorus, which is due
to the fact that both groups have a large trans influ-
ence.13
The crystal structure of 9 with adopted numbering
scheme is shown in Figure 3, and selected bond dis-
tances and bond angles are collected in Table 2. The
crystal structure of 9 showed C2 symmetry. For C(8)
and C(9), two orientations are found.
From Figure 3, the extended conformation of the
molecule is apparent and the secondary hydroxy group
does not bridge the two palladium centers. Therefore,
a very large Pd‚‚‚Pd distance of 7.0529(5) Å is observed.
Each palladium is in a square-planar environment, and
(12) Yang, H.; Khan, M. A.; Nicholas, K. M. J . Chem. Soc., Chem.
Commun. 1992, 210.
(13) (a) Hartley, F. R. The Chemistry of Platinum, Palladium;
Applied Science: London, 1973; p 300. (b) Hartley, F. R. Chem. Soc.
Rev. 1973, 2, 163.

Dinuclear Pd, Ni, and Rh Complexes
Organometallics, Vol. 17, No. 4, 1998 639
Ta ble 2. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) of Com p ou n d 9 (Sta n d a r d Devia tion s
in P a r en th eses)
Pd(1)-Cl(1)
Pd(1)-P(1)
2.3837(9)
2.2024(9)
Pd(1)-N(1)
Pd(1)-C(42)
2.172(3)
2.037(4)
Cl(1)-Pd(1)-P(1)
Cl(1)-Pd(1)-N(1)
172.89(3) P(1)-Pd(1)-N(1)
90.97(9) P(1)-Pd(1)-C(42)
86.50(9)
93.86(11)
Cl(1)-Pd(1)-C(42) 88.76(11) N(1)-Pd(1)-C(42) 179.11(12)
Sch em e 4. Syn th esis of 10
F igu r e 4. ORTEP plot of 10 at the 50% probability level.
The bridging moiety is disordered. O(1) is hydrogen-bonded
to Cl(1).
Ta ble 3. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) of Com p ou n d 10 (Sta n d a r d
Devia tion s in P a r en th eses)
Pd(1)-O(1)
Pd(1)-N(1)
Pd(1)-P(1)
Pd(1)-C(42)
Pd(2)-O(1)
2.093(4)
2.087(4)
2.1758(14)
2.041(5)
2.096(4)
Pd(2)-N(2)
Pd(2)-P(2)
Pd(2)-C(43)
Pd(1)‚‚‚Pd(2)
2.076(4)
2.1763(14)
2.040(5)
3.7598(5)
the four coordination sites are occupied by P(1), N(1),
Cl(1), and C(42). The chloride atom is situated trans
to phosphorus, and the methyl group is trans to nitro-
gen, as was also indicated by NMR spectroscopy (vide
supra). The deviations of the least-squares plane of Pd-
(1), P(1), N(1), Cl(1), and C(42) are 0.04672(19), -0.0887-
(9), 0.062(3), -0.0821(9), and 0.062(3) Å, respectively.
The crystal structure shows intramolecular hydrogen
bonds of 3.139(5) Å between the hydroxy hydrogen and
both chlorides. Only one of the hydrogen bridges is
shown. The Pd-N, Pd-P, Pd-C, and Pd-Cl bond
distances in dinuclear complex 9 are all in the normal
range found for mononuclear Pd-Me complexes.14
To obtain [Pd(L1)Me2](BF4) (10), in which the alkoxide
moiety bridges the two palladium centers, the hydroxy
group of L1H was first deprotonated with potassium tert-
butoxide in dichloromethane. Subsequently, 2 equiv of
Pd(cod)MeCl was added and, after an anion exchange
reaction with NaBF4, complex 10 was isolated (Scheme
4). Crystals suitable for X-ray analysis were obtained
via crystallization from dichloromethane/pentane. In
the 31P NMR spectrum, one absorption was seen at 39.8
ppm, which is shifted significantly compared to the
absorption for the phosphine moiety found in
Pd2(L1H)Me2Cl2 (9). In 10, the methyl group is also
positioned cis toward the phosphorus atom and in the
1H NMR spectrum a doublet for the methyl group was
obtained at 0.49 ppm with J PH ) 1.96 Hz.
P(1)-Pd(1)-O(1)
P(1)-Pd(1)-N(1)
P(1)-Pd(1)-C(42)
O(1)-Pd(1)-N(1)
O(1)-Pd(1)-C(42)
N(1)-Pd(1)-C(42) 174.25(18) Pd(1)-O(1)-Pd(2) 127.66(17)
P(2)-Pd(2)-O(1) 172.18(11)
173.99(10) P(2)-Pd(2)-N(2)
93.78(11) P(2)-Pd(2)-C(43)
91.62(15) O(1)-Pd(2)-N(2)
81.75(14) O(1)-Pd(2)-C(43)
94.47(11)
91.06(15)
82.32(14)
92.33(17)
92.73(18) N(2)-Pd(2)-C(43) 174.38(18)
Sch em e 5. Syn th esis of 11
maximum deviation from the least-squares plane of Pd-
(1), P(1), O(1), N(1), and C(42) is 0.0434(3) Å. The
related value for the Pd(2), P(1), N(2), O(1), and C(43)
plane is 0.0839(11) Å. The bending of the two coordina-
tion planes with respect to each other is 118.02(14)°,
and the Pd-O-Pd angle of 127.66(17)° is slightly larger
than that found in [Pd2(L1)(OAc)2](BF4). The imine
moieties are not in the plane of the phenyl rings, and
the torsion angles for C(1), C(6), C(7), and N(1) and for
C(17), C(12), C(11), and N(2) are -12.4(8) and 3.0(7)°,
respectively.
The crystal structure of 10 together with the adopted
numbering scheme is shown in Figure 4, and selected
bond distances and angles are collected in Table 3. In
complex 10, the two palladium centers are indeed
bridged by the oxygen atom of the endogenous ligand.
Therefore, the Pd‚‚‚Pd distance of 3.7598(5) Å is much
shorter than that found in complex 9 (7.0529(5) Å) with
the nonbridging hydroxyl group. The Pd‚‚‚Pd distance
is slightly longer than that found in the corresponding
complex [Pd2(L1)(OAc)2](BF4) (6). The two palladium
atoms are in a square-planar environment, and the
Syn th esis of [Rh 2(L1)(CO)2](BF 4) (11). Complex-
ation of L1H with Rh2(CO)4Cl2 in dichloromethane in
the presence of 1 equiv of diisopropylethylamine and
subsquent anion exchange with NaBF4 gave the di-
nuclear rhodium dicarbonyl complex [Rh2(L1)(CO)2]-
(BF4) (11) in 73% yield (Scheme 5). Crystals suitable
for X-ray analysis were obtained via crystallization from
dichloromethane/pentane.
(14) Dekker, G. P. C. M.; Buijs, A.; Elsevier: C. J .; Vrieze, K.; van
Leeuwen, P. W. N. M.; Smeets, W. J . J .; Spek, A. L.; Wang, Y. F.; Stam,
C. H. Organometallics 1992, 11, 1937.
In the 31P NMR spectrum a doublet was observed at
51.7 ppm with a rhodium-phosphorus coupling of 159

640 Organometallics, Vol. 17, No. 4, 1998
van den Beuken et al.
Sch em e 6. Syn th esis of 13
F igu r e 5. ORTEP plot of 11 at the 50% probability level.
Ta ble 4. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) of Com p ou n d 11 (Sta n d a r d
Devia tion s in P a r en th eses)
Rh(1)-O(1)
Rh(1)-N(1)
Rh(1)-P(1)
Rh(1)-C(42)
Rh(2)-O(1)
2.088(4)
2.054(5)
2.1962(16)
1.882(6)
2.104(4)
Rh(2)-N(2)
Rh(2)-P(2)
Rh(2)-C(43)
Rh(1)‚‚‚Rh(2)
2.054(5)
2.1938(17)
1.954(7)
3.4605(7)
interesting because of the different functions which can
be performed by the two metals in the catalytic cycle.
An elegant example has been published by Sawamura
and co-workers, in which a two-component rhodium
palladium system catalyzes the allylic alkylation of
activated nitriles.16 To investigate the feasibility of
obtaining a heterodinuclear complex with the ligand
L1H, we focused on the synthesis of a rhodium pal-
ladium mixed system.
P(1)-Rh(1)-O(1)
P(1)-Rh(1)-N(1)
P(1)-Rh(1)-C(42)
O(1)-Rh(1)-N(1)
O(1)-Rh(1)-C(42)
N(1)-Rh(1)-C(42) 170.2(3)
P(2)-Rh(2)-O(1) 171.07(12)
171.43(12) P(2)-Rh(2)-N(2)
92.33(13) P(2)-Rh(2)-C(43)
89.40(18) O(1)-Rh(2)-N(2)
81.70(17) O(1)-Rh(2)-C(43)
89.13(16)
91.74(18)
81.78(19)
97.2(2)
97.5(2)
N(2)-Rh(2)-C(43) 176.5(2)
Rh(1)-O(1)-Rh(2) 111.27(18)
Hz. The coordination of the carbonyl to rhodium was
evident from IR spectroscopy, which gave a vibration
at 2016 cm-1, and from 13C NMR spectroscopy, which
gave a CO absorption at 190.0 ppm (J Rh-C ) 75.2 Hz,
J P-C ) 20.2 Hz).
For the synthesis of rhodium palladium complex 13,
L1H was first complexed with 1 equiv of Pd(OAc)2 in
dichloromethane (Scheme 6). This reaction probably
results in the mononuclear complex Pd(L1)(OAc) (12),
for which the coordination mode is not known at the
present. In the 31P NMR spectrum one broad signal was
obtained at 30.7 ppm. Subsequently, 0.5 equiv of
Rh2(CO)4Cl2 was added and finally an anion exchange
was performed with NaBF4 to provide complex 13. In
dinuclear complex 13, the acetate group is replaced by
a chloride which is derived from Rh2(CO)4Cl2. In a
reverse sequence, where L1H was first complexed with
Rh(CO)4Cl2, a mononuclear rhodium complex was formed
which did not react with Pd(OAc)2.
The crystal structure of 11 together with the adopted
numbering scheme is shown in Figure 5. Selected bond
distances and bond angles are collected in Table 4. The
two rhodium atoms are bridged by the secondary alkoxy
group of the endogenous ligand O(1), and the Rh‚‚‚Rh
distance is 3.4605(7) Å. Both rhodium centers adopt a
square-planar geometry, and the other coordinating
atoms to the rhodium atoms are P(1), N(1), and C(42)
for Rh(1) and P(2), N(2), and C(43) for Rh(2). The
maximum deviation from the Rh(1), P(1), N(1), O(1), and
C(42) least-squares plane is 0.144(5) Å, and the devia-
tion for the Rh(2), P(2), N(2), O(1), and C(43) plane is
0.038(5) Å. The angle between the square-planar
rhodium coordination sites is 109.0(2)°, and the Rh-
O-Rh angle is 111.27(18)°, which is the highest bending
thus found in these types of complexes.9c
In the 31P NMR spectrum, two absorptions were
observed: i.e. a singlet at 33.7 ppm derived from the
phosphorus atom which coordinates to palladium and
a doublet at 52.1 ppm with J Rh-P ) 162 Hz, which is
derived from the phosphorus atom coordinating to
1
rhodium. In the H NMR spectrum, the five hydrogen
atoms from the propanol backbone are observed sepa-
rately, which shows clearly the dissymmetry of complex
13. In contrast, in the symmetric homodinuclear com-
plexes (vide supra) the methylene groups were identical.
For 13 four doublets of doublets (at 4.38, 4.15, 4.05, 3.85
ppm) were obtained which are derived from the CH2
groups and one broad absorption (4.27 ppm) was due
to the CH moiety. Furthermore, the two imine protons
were found at 8.80 and 8.51 ppm. In the electrospray
mass spectrum a M+ peak was obtained at m/z 907,
which is in agreement with [PdRh(L1)(CO)Cl]+. In
addition, one peak was observed at m/z 879, which
The torsion angles of C(1), C(6), C(7), N(1), and C(17),
C(12), C(11), N(2) are -10.1(12), and -16.6(9)°, respec-
tively. The Rh-P, Rh-N, Rh-O, and Rh-C distances
all are in the normal range for rhodium complexes.15
Syn t h esis of t h e H et er od in u clea r Com p lex
[P d Rh (L1)(CO)Cl](BF 4) (13). So far, it has been
shown that L1H is an excellent ligand for the synthesis
of homodinuclear transition-metal complexes. In cata-
lytic reactions two similar metals might cooperate with
each other, lowering the transition states during ca-
talysis. Complexes with two distinct metals are also
(15) (a) Clegg, W.; Akhter, L.; Garner, D. J . Chem. Soc. Chem.
Commun. 1984, 101. (b) Dunbar, K. R.; Matonic, J . H.; Saharan, V. P.
Inorg. Chem. 1994, 33, 25.
(16) Sawamura, M.; Sudoh, M.; Ito, Y. J . Am. Chem. Soc. 1996, 118,
3309.

Dinuclear Pd, Ni, and Rh Complexes
Organometallics, Vol. 17, No. 4, 1998 641
Sch em e 7. Hyd r osilyla tion of Acetop h en on e
Sch em e 8. Hyd r obor a tion of 1-Hexen e a n d
Cycloh exen e
corresponds to the M+ complex minus a carbon monox-
ide, i.e. [PdRh(L1)Cl]+. In the IR spectrum a strong
The hydroboration reaction of 1-hexene catalyzed by
11 gave, after 20 min of reaction time followed by a
standard workup procedure (NaOH, H2O2), 80% conver-
sion to 1-hexanol. Due to the isomerization reaction also
catalyzed by 11, 20% of internal hexenes was obtained.
The rhodium palladium complex 13 gave even more
isomerization, and the ratio of internal hexenes to
1-hexanol was 1:1.
Because of the relatively high isomerization activity
of 11 and 13, cyclohexene was used, as it remains
unchanged upon isomerization. In comparison to 1-hex-
ene, the hydroboration reaction of cyclohexene is much
slower because cyclohexene is an internal alkene. The
hydroboration reaction of cyclohexene catalyzed by 11
gave after oxidative workup 90% conversion to cyclo-
hexanol after 24 h. The rates are comparable with
hydroboration reactions by mononuclear catalysts known
in the literature.17
carbonyl absorption was observed at 2012 cm-1
.
Ca ta lysis. The palladium complexes [Pd2(L1)(OAc)2]-
(BF4) (6) and [Pd2(L1)(Me)2](BF4) (10) were unfortu-
nately not active in oligomerization reactions of ethyl-
ene.17 Also, no activity was found in the copolymerization
reaction of ethylene and carbon monoxide.18
The dinuclear rhodium complex 11 was used in the
hydrosilylation reaction19 of acetophenone (Scheme 7).
In this catalytic reaction, one of the Si-H moieties of
diphenylsilane adds to the carbonyl carbon to give silyl
ether 15, which can be hydrolyzed to 1-phenylethanol.
As a byproduct a small amount of silyl enol ether 16
might be obtained, which after hydrolysis is converted
to the starting material. The hydrosilylation reaction
of 14, catalyzed by 11 (0.5 mol %), gave after 3 days in
toluene a conversion of 93%, which is rather slow
compared to reported catalytic systems.19 Unexpect-
edly, a 3:7 ratio of the products 15 and 16 was found,
which implies that 16 is the main product. Therefore,
complex 11 is not very effective for the reduction of
ketones to alcohols by hydrosilylation. However, it
appears that a very mild catalytic method has been
found for the synthesis of enol ethers.20
Furthermore, the homodinuclear rhodium complex 11
and the heterodinuclear rhodium palladium complex 13
were tested in the hydroboration reaction of alkenes
with catecholborane (Scheme 8). Additions of catechol-
borane to alkenes without catalyst are generally very
slow, but they are accelerated enormously using a cata-
lytic amount of transition-metal complexes.21 Further-
more, the selectivity changes such that addition occurs
exclusively at the CdC bond, instead of addition at more
reactive functional groups such as ketones and nitriles.22
Con clu sion s
The new compartmental dinucleating ligand 5 (L1H)
with a PNONP donor set has been synthesized in 85%
yield. Complexation with palladium, nickel, and rhod-
ium gave the dinuclear complexes [M2(L1)(OAc)2](BF4)
(M ) Pd, 6; M ) Ni, 7), [Pd2(L1)(Me)2](BF4) (10), and
[Rh2(L3)(CO)2](BF4) (11). In these complexes, the oxy-
gen atom of the dinucleating ligand functions as a
bridging atom between the two metals and binds them
at a fixed distance with respect to each other, i.e. 3.5-
3.8 Å, as confirmed by X-ray analysis. In the related
complex Pd2(L1H)(Me)2Cl2, in which the oxygen atom
of the ligand does not bridge, the two metal centers have
a much larger M‚‚‚M distance of 7.5 Å. Finally, the
highly interesting heterodinuclear complex [PdRh(L1)-
(CO)Cl](BF4) has been synthesized by sequential com-
plexation with Pd(OAc)2 and with Rh2(CO)4Cl2. Pre-
liminary results on applications of these new dinuclear
complexes in catalysis are also given.
(17) (a) J ohnson, L. K.; Killian, C. M.; Brookhart, M. J . Am. Chem.
Soc. 1995, 117, 6414. (b) Killian, C. M.; Tempel, D. J .; J ohnson, L. K.;
Brookhart, M. J . Am. Chem. Soc. 1996, 118, 11664. (c) van den Beuken,
E. K., Smeets, W. J . J .; Spek, A. L.; Feringa, B. L. Submitted for
publication.
(18) Drent, E.; Budzelaar, P. H. M. Chem. Rev. (Washington, D.C.)
1996, 96, 663.
(19) (a) Brunner, H.; Riepl, G.; Weitzer, H. Angew. Chem., Int. Ed.
Engl. 1983, 22, 331. (b) Brunner, H.; Becker, R.; Riepl, G. Organome-
tallics 1984, 3, 1354. (c) Brunner, H.; Obermann, U. Chem. Ber. 1989,
122, 499. (d) Faller, J . W.; Chase, K. J . Organometallics 1994, 13, 989.
(e) Hayashi, T.; Hayashi, C.; Uozumi, Y. Tetrahedron: Asymmetry
1995, 6, 2503. (f) Nishiyama, H.; Yamaguchi, S.; Kondo, M.; Itoh, K.
J . Org. Chem. 1992, 57, 4306.
Exp er im en ta l Section
All operations were carried out under an atmosphere of
argon. 2-(Diphenylphosphino)benzaldehyde23 and Pd(cod)-
MeCl24 were prepared by literature procedures. 1,3-Diamino-
propan-2-ol was obtained from Fluka, and Pd(OAc)2, Ni(OAc)2,
Rh2Cl2(CO)4, and Me3SiOTf were obtained from Aldrich and
(20) The scope and limitations will be investigated and the results
published separately.
(21) (a) Burgess, K.; Ohlmeyer, M. J . Chem. Rev. (Washington, D.C.)
1991, 91, 1179. (b) Brown, J . M.; Hulmes, D. I.; Layzell, T. P. J . Chem.
Soc., Chem. Commun. 1993, 1673. (c) Westcott, S. A.; Blom, H. P.;
Marder, T. B.; Baker, R. T. J . Am. Chem. Soc. 1992, 114, 8863. (d)
Gridnev, I. D.; Miyaura, N.; Suzuki, A. Organometallics 1993, 12, 589.
(e) Westcott, S. A.; Blom, H. P.; Marder, T. B.; Baker, R. T.; Calabrese,
J . C. Inorg. Chem. 1993, 32, 2175.
(22) Ma¨nnig, D.; No¨th, H. Angew. Chem., Int. Ed. Engl. 1985, 24,
878.
(23) Hoots, J . E.; Rauchfuss, T. B.; Wrobleski, D. A. Inorg. Synth.
1982, 21, 175.
(24) Ru¨lke, R. E.; Ernsting, J . M.; Spek, A. L.; Elsevier: C. J .; van
Leeuwen, P. W. N. M.; Vrieze, K. Inorg. Chem. 1993, 32, 5769.

642 Organometallics, Vol. 17, No. 4, 1998
van den Beuken et al.
were used as received. 1H, 31P, and 13C NMR spectra were
recorded at 200, 81, and 50 MHz, respectively, with a Varian
Gemini 200 FT NMR spectrometer. Chemical shifts are
reported in ppm and referenced to the residual deuterated
solvent signals for 1H and 13C and external triphenyl phos-
phate (δ -18 ppm) for 31P. IR spectra were measured using a
Perkin-Elmer 841 spectrometer. Electron ionization mass
spectra (EI-MS) were measured on a AEI-MS-902 spectrom-
eter; for electrospray MS (ES-MS) we used a Nermag-R-30-10
spectrometer. Elemental analyses were determined in the
microanalytical department of the University of Groningen.
1,3-Bis[(2-(d ip h en ylp h osp h in o)b en zylid en e)a m in o]-
p r op a n -2-ol (5). A solution of 1,3-diaminopropan-2-ol (564
mg, 6.25 mmol) and 2-(diphenylphosphino)benzaldehyde (4.0
g, 13.8 mmol) in toluene (50 mL) was refluxed under Dean-
Stark conditions for 5 h. The solution was evaporated to
dryness, and the product was crystallized from CH2Cl2/
pentane, yielding a yellow powder. Yield: 3.39 g (85%). Mp:
153.9-154.0 °C. Anal. Calcd for C41H36N2OP2: C, 77.59; H,
5.72; N, 4.41; P, 9.76. Found: C, 77.32; H, 5.74; N, 4.38; P,
9.62. 31P NMR (CDCl3): δ -12.0 (s). 1H NMR (CDCl3): δ 8.7
(d, J ) 3.9 Hz, 2 H, HCdN), 7.8 (m, 2H, Ar H), 7.5-7.2 (m,
24H, Ar H), 6.9 (m, 2H, Ar H), 3.8 (m, 1H, CH), 3.4 (d, J ) 6.0
Hz, 4H, CH2), 2.5 (d, J ) 5.1 Hz, 1H, OH). 13C NMR: δ 161.6
(d, 3J PC ) 14.9 Hz, CH), 139.2 (d, 1J PC ) 16.8 Hz, C), 137.2 (d,
P d 2(L1H)Me2Cl2 (9). Pd(cod)MeCl (84 mg, 0.32 mmol) was
added to a solution of L1H (100 mg, 0.16 mmol) in THF (2 mL),
and the mixture was stirred for 1 h. The white precipitate
was collected and crystallized from CH2Cl2/pentane, yielding
crystals suitable for X-ray analysis. Yield: 65 mg (43%). Anal.
Calcd for C43H42Cl2N2OP2Pd2‚0.5CH2Cl2: C, 52.72; H, 4.37; N,
2.82. Found: C, 53.06; H, 4.43; N, 2.80. 31P NMR (CDCl3): δ
35.3 (s). 1H NMR (CDCl3): δ 8.36 (s, 2H, HCdN), 7.65-7.03
(m, 28H, Ar H), 4.55 (br d, J ) 11.7 Hz, 2H, CH2), 3.89 (br,
2H, CH, OH), 3.87 (dd, J ) 10.5 Hz, J ) 5.86 Hz, 2H, CH2),
0.55 (d, J ) 2.93 Hz, 6H, CH3). 13C NMR (CDCl3): δ 165.6 (d,
3J PC ) 4.9 Hz, CH), 137.2 (d, 2J PC ) 14.9 Hz, C), 136.5 (d, 2J PC
) 9.2 Hz, CH), 134.0 (d, 2J PC ) 12.9 Hz, CH), 133.9 (CH), 133.7
(d, 2J PC ) 12.3 Hz, CH), 132.1 (d, 3J PC ) 6.9 Hz, CH), 131.5 (d,
4
3J PC ) 1.5 Hz, CH), 131.2 (d, J PC ) 1.9 Hz, CH), 131.0 (d,
4J PC ) 1.9 Hz, CH), 128.8 (d, 1J PC ) 53.2 Hz, C), 128.6 (d, 1J PC
3
3
) 55.0 Hz, C), 128.8 (d, J PC ) 7.6 Hz, CH), 128.6 (d, J PC
)
7.6 Hz, CH), 125.3 (d, 1J PC ) 42.7 Hz, C), 71.0 (CH), 66.5 (CH2),
1.9 (CH3).
[P d 2(L1)Me2](BF 4) (10). KOBut (17.6 mg, 0.16 mmol) was
added to a solution of L1H (100 mg, 0.16 mmol) in CH2Cl2 (5
mL). After the mixture was stirred for 30 min, Pd(cod)MeCl
(84 mg, 0.32 mmol) was added and this mixture was stirred
for 1 h. Then, NaBF4 (17.6 mg, 0.16 mmol) was added and
the reaction mixture was stirred for another 12 h. The solution
was added dropwise to pentane (25 mL). The resulting
precipitate was collected, washed with pentane and dried
under vacuum, yielding a yellow powder. Crystals suitable
for X-ray analysis were obtained by crystallization from
CH2Cl2/pentane. Yield: 52 mg (34%). Anal. Calcd for
C43H41BF4N2OP2Pd2‚CH2Cl2: C, 50.41; H, 4.31; N, 2.78.
Found: C, 49.99; H, 4.12; N, 2.61. 31P NMR (CDCl3): δ 39.8
(s). 1H NMR (CDCl3): δ 8.73 (s, 2H, HCdN), 7.87 (m, 2H, Ar
H), 7.67 (t, J ) 7.6 Hz, 2H, Ar H), 7.63-7.23 (m, 24H, Ar H),
4.5 (br, 1H, CH), 4.1 (m, 4H, CH2), 0.49 (d, J ) 1.97 Hz, 6H,
2J PC ) 11.8 Hz, C), 137.0 (t, 1J PC ) 9.2 Hz, C), 134.0 (d, 2J PC
)
3.8 Hz, CH), 133.6 (CH), 133.5 (CH), 130.0 (CH), 128.8 (d, 2J PC
3
) 4.2 Hz, CH), 128.6 (CH), 128.4 (d, J PC ) 6.9 Hz, CH), 70.3
(CH), 64.2 (CH2). EI-MS: m/z 634 (M+). HRMS: calcd m/z
634.230, found m/z 634.230.
[P d 2(L1)(OAc)2](BF 4) (6). Pd(OAc)2 (177 mg, 0.79 mmol)
was added to a solution of L1H (250 mg, 0.39 mmol) in CH2Cl2
(5 mL), and the mixture was refluxed for 2 h. Then NaBF4
(43.3 mg, 0.39 mmol) was added and the solution was refluxed
for another 30 min. The solution was cooled and filtered, and
the filtrate was added dropwise to hexane (30 mL). The
resulting precipitate was filtered off, washed with hexane, and
dried under vacuum, yielding a yellow-brown powder (373 mg,
91%). Suitable crystals for X-ray analysis were obtained by
2
CH3). 13C NMR (CDCl3): δ 162.9 (CH), 137.9 (d, J PC ) 9.8
2
Hz, CH), 136.8 (d, J PC ) 15.8 Hz, C), 135.0 (CH), 133.6 (d,
2J PC ) 13.4 Hz, CH), 132.6 (d, 3J PC ) 7.3 Hz, CH), 132.2 (CH),
1
131.2 (CH), 131.0 (CH), 130.2 (d, J PC ) 29.3 Hz, C), 129.4 (d,
3
1J PC ) 28.1 Hz, C), 128.8 (d, J PC ) 11.0 Hz, CH), 128.7 (d,
crystallization from CH2Cl2/pentane. Anal. Calcd for C45H41
-
1
2J PC ) 12.2 Hz, CH), 123.8 (d, J PC ) 46.4 Hz, C), 76.8 (CH),
BF4N2O5P2Pd2‚2CH2Cl2: C, 46.22; H, 3.71; N, 2.29. Found: C,
46.18; H, 3.84; N, 2.40. 31P NMR (CDCl3): δ 30.5 (s). 1H NMR
(CDCl3): δ 8.5 (s, 2 H, HCdN), 7.9 (m, 2H, Ar H), 7.8-7.2 (m,
28 H, Ar H), 4.5 (m, 1H, CH), 3.2 (m, 4H, CH2), 1.4 (s, 6H,
CH3). ES-MS: m/z 963 (M+), 453 [(M+ - OAc)2+].
66.4 (CH2), 2.3 (CH3); 1 CH was not resolved due to overlap.
ES-MS: m/z 877 (M+).
[Rh 2(L1)(CO)2](BF 4) (11). Rh2(CO)4Cl2 (50 mg, 0.13 mmol)
and Et3N (18 µL, 0.13 mmol) were added to a solution of L1H
(82 mg, 0.13 mmol) in CH2Cl2 (2 mL), and the mixture was
stirred for 1 h. Then NaBF4 (14.1 mg, 0.13 mmol) was added
and the mixture was stirred for another 12 h. Crystals
suitable for X-ray analysis were obtained by crystallization
from CH2Cl2/pentane. Yield: 72 mg (73%). Anal. Calcd for
[Ni2(L1)(OAc)2](BF 4) (7). Ni(OAc)2‚4H2O (225 mg, 0.79
mmol) was added to a solution of L1H (250 mg, 0.39 mmol) in
methanol (10 mL), and the mixture was refluxed for 1 h. Then
NaBF4 (43.3 mg, 0.39 mmol) was added, and the solution was
refluxed for another 30 min. Cooling the solution to -20 °C
yielded 7 as a red-brown powder. Yield: 212 mg (56%). Anal.
Calcd for C45H41BF4N2O5P2Ni2‚CH3OH: C, 55.92; H, 4.59; N,
2.83. Found: C, 56.04; H, 4.53; N, 2.76. ES-MS: m/z 867 (M+).
[P d 2(L1)(OAc)](BF 4)(OTf) (8). Me3SiOTf (8.1 µL, 42 µmol)
was added to a solution of [Pd2(L1)(OAc)2](BF4) (45 mg, 42
µmol) in CH2Cl2 (3 mL). The reaction mixture was stirred for
1 h, filtered, and poured in pentane. The resulting precipitate
was collected, washed with pentane, and dried under vacuum,
yielding a brown powder. Yield: 40 mg (83%). 31P NMR
(CDCl3): δ 30.5 (s). 19F NMR (CDCl3): δ -152.3 (s), -79.7
(s). 1H NMR (CDCl3): δ 8.78 (s, 2H, CHdN), 8.12 (m, 2H, Ar
H), 7.78-7.38 (m, 26H, Ar H), 4.54-4.20 (m, 5H, CH2, CH),
2.03 (s, 3H, CH3). 13C NMR (CDCl3): δ 181.9 (C), 168.3 (d,
C
43H35BF4N2O3P2Rh2: C, 52.58; H, 3.59; N, 2.85. Found: C,
52.51; H, 3.74; N, 2.83. 31P NMR (CDCl3): δ 51.7 (d, J Rh-P
)
159 Hz). 1H NMR (CDCl3): δ 9.1 (2H, s, HCdN), 7.9-7.2
(28H, m, Ar H), 4.3 (1H, br, CH), 4.1 (4H, br, CH2). 13C NMR
(CDCl3): δ 190.0 (dd, 1J RhC ) 75.2 Hz, 2J PC ) 20.2 Hz, C), 166.6
(d, 3J PC ) 6.9 Hz, CH), 137.8 (d, 2J PC ) 8.4 Hz, CH), 136.0 (dd,
1J PC ) 16.8 Hz, J RhC ) 1.9 Hz, C), 133.4 (d, J PC ) 12.2 Hz,
2
2
1
3
CH), 133.0 (CH), 132.5 (d, J PC ) 14.5 Hz, C), 131.8 (d, J PC
1.5 Hz, CH), 131.4 (d, J PC ) 14.1 Hz, C), 131.1 (CH), 128.8
(d, J PC ) 2.7 Hz, CH), 128.5 (d, J PC ) 2.7 Hz, CH), 124.6 (d,
1J PC ) 44.6 Hz, C), 73.7 (CH), 67.5 (CH2). 1 CH was not
resolved. IR (CHCl3): νmax/cm-1 (CO) 2016 (s). ES-MS: m/z
895 (M+).
)
2
3
3
3
3J PC ) 6.5 Hz, CH), 139.5 (d, J PC ) 9.2 Hz, CH), 135.9 (d,
P dRh (L1)(CO)(Cl)(BF4) (13). Pd(OAc)2 (58 mg, 0.26 mmol)
was added to a solution of L1H (163 mg, 0.26 mmol) in CH2Cl2
(5 mL). The solution was refluxed for 1 h. Then Rh2(CO)4Cl2
(50 mg, 0.13 mmol) was added and the mixture was stirred
for 1 h. Finally NaBF4 (28.2 mg, 0.26 mmol) was added and
the reaction mixture was stirred for another 30 min. The
solution was added dropwise to hexane (25 mL). The resulting
precipitate was collected, washed with hexane, and dried under
2
2J PC ) 17.6 Hz, C), 135.2 (d, J PC ) 8.0 Hz, CH), 134.0 (CH),
2
2
133.4 (d, J PC ) 12.2 Hz, CH), 133.3 (d, J PC ) 12.2 Hz, CH),
3
3
133.1 (CH), 129.7 (d, J PC ) 6.1 Hz, CH), 129.4 (d, J PC ) 5.7
1
1
Hz, CH), 124.7 (d, J PC ) 60.3 Hz, C), 124.2 (d, J PC ) 60.3
1
Hz, C), 117.8 (d, J PC ) 56.1 Hz, C), 73.1 (CH), 71.2 (CH2),
23.5 (CH3); 2 CH’s were not resolved due to overlap. ES-MS:
m/z 462 (M2+ + H2O), 453 (M2+).

Dinuclear Pd, Ni, and Rh Complexes
Organometallics, Vol. 17, No. 4, 1998 643
Ta ble 5. Su m m a r y of Cr ysta llogr a p h ic Da ta
6
9
10
11
Crystal Data
chem formula
C
45H41N2O5P2Pd2BF4‚2CH2Cl2
C43H42Cl2N2OP2Pd2
C43H41N2OP2Pd2BF4‚
2CH2Cl2
1133.27
C43H35N2O3P2Rh2BF4‚
2CH2Cl2
1152.19
[-0.108 (C2H3O2) + 0.108 (Cl)]
mol wt
cryst syst
space group
a, Å
b, Å
c, Å
1218.74
triclinic
948.51
monoclinic
C2/c (No. 15)
22.0020(14)
10.4889(6)
17.4192(11)
90
92.643(5)
90
4015.7(4)
1.569
triclinic
triclinic
P1h (No. 2)
13.4207(12)
13.7895(8)
14.0514(8)
102.068(4)
99.063(6)
100.789(6)
2445.1(3)
1.655
P1h (No. 2)
11.0224(15)
11.884(4)
18.862(3)
105.34(2)
99.845(11)
97.54(2)
2306.8(10)
1.632
2
P1h (No. 2)
13.0693(9)
13.4963(9)
14.0695(9)
101.822(5)
97.726(5)
100.113(5)
2353.6(3)
1.626
R, deg
â, deg
γ, deg
V, Å3
D
Z
calcd, g cm-3
2
4
2
F(000)
1221
10.9
yellowish
0.10 × 0.18 × 0.50
1912
11.4
1136
11.3
colorless
0.15 × 0.40 × 0.65
1152
10.5
red
0.30 × 0.30 × 0.30
µ(Mo KR), cm-1
color
yellowish
0.15 × 0.25 × 0.40
cryst size, mm
Data Collection
T, K
150
150
150
150
radiation (Mo KR), Å
0.710 73
1.5, 26.0
ω, 0.71 + 0.35 tan θ
-17 to +17;
-17 to +17; 0-18
0.710 73
1.9, 27.5
0.710 73
1.1, 27.6
0.710 73
1.5, 27.5
ω, 1.39 + tan θ
θ
min, θmax, deg
scan type and range, deg
data set
ω, 0.64 + 0.35 tan θ
-28 to +28;
0-13; 0-22
4748, 4605
3725
ω, 1.54 + 0.35 tan θ
-14 to +14; -15 to +10; -16 to +16;
-23 to +24
12 574, 10 623
7697
0-17; -18 to +17
10 933, 10 494
7255
total and unique no. of data 10 018, 9602
no. of obsd data (I > 2.0σ(I)) 5536
Refinement
4605, 256
0.0363
N
ref, Npar
8950, 615
0.0646
10 622, 589
0.0473
0.1072
10 493, 568
0.0598
0.1560
Ra
wR2b
wc
0.1298
0.0849
1/[σ2(Fo2) + (0.0351P)2]
1/[σ2(Fo2) + (0.0377P)2 1/[σ2(Fo2) + (0.0428P)2
1/[σ2(Fo2) + (0.0677P)2
+ 6.9539P]
1.03
+ 4.1816P]
1.06
+ 3.0562P]
1.01
S
1.04
max and av shift/error
0.00, 0.00
-0.91, 0.74
0.001, 0.000
-0.43, 0.64
0.01, 0.00
-0.72, 0.87
0.001, 0.000
-1.06, 1.75
min, max resd dens e/Å3
a
b
2
2
R ) ∑(|Fo| - |Fc|)/∑|Fo|. wR2 ) {∑w(Fo - Fc2)2]/∑[w(Fo2)2]}1/2
.
c P ) (Fo + 2Fc2)/3.
vacuum, yielding a red powder which was crystallized from
CH2Cl2/pentane. Yield: 64 mg (25%). 31P NMR (CDCl3): δ
52.1 (d, J Rh-P ) 162 Hz), 33.7 (s). 1H NMR (CDCl3, 500
MHz): δ 8.80 (d, J PC ) 2.3 Hz, 1H, CHdN), 8.50 (s, 1H,
CHdN), 8.12 (m, 1H, Ar H), 7.81-7.76 (m, 2H, Ar H), 7.67-
7.36 (m, 23H, Ar H), 7.26-7.16 (m, 2H, Ar H), 4.38 (dd, J )
13.5 and 3.7 Hz, 1H, CH2), 4.27 (br, 1H, CH), 4.15 (dd, J )
13.4 and 5.2 Hz, 1H, CH2), 4.05 (dd, J ) 13.4 and 3.9 Hz, 1H,
CH2), 3.86 (dd, J ) 13.4 and 7.5 Hz, 1H, CH2). 13C NMR
(CDCl3, 500 MHz): δ 189.8 (d, 1J RhC ) 56.0 Hz, C), 166.8 (CH),
5.5 (s, 1H, SiH),a 5.8 (s, 1H, SiH),b 7.1-8.0 (m, Ar H) (a ) 15,
b ) 16, c ) 14, d ) diphenylsilane, e ) toluene).
Hyd r obor a tion of Alk en es. A 5-mm NMR tube was
charged with olefin (0.30 mmol), catecholborane (64 µL, 0.60
mmol), benzene-d6 (0.3 mL), and catalyst precursor 11 or 13
1
(10 µmol). The progress of the reaction was monitored by H
NMR spectroscopy. After all alkene had been consumed, the
mixture was quenched with 3 M NaOH (0.25 mL) and 30%
H2O2 (0.50 mL) and subsequently heated to 50 °C for 3 h. The
organic layer was separated and analyzed by 1H NMR spec-
troscopy and GC, and the products were compared with
independent samples.
X-r a y Str u ctu r e Deter m in a tion s. X-ray data were col-
lected on an Enraf-Nonius CAD4-T diffractometer on a rotating
anode (Mo KR, graphite monochromator). Unit-cell dimen-
sions were derived from the SET425 setting angles of 25
reflections. Unit cells were checked for higher symmetry with
the program LEPAGE.26 All structures were refined on F2
with SHELXL.27 Geometrical calculations and the ORTEP
illustrations were done with PLATON.28 Crystal data are
presented in Table 5.
3
3
165.2 (CH), 139.4 (d, J PC ) 8.6 Hz, CH), 138.3 (d, J PC ) 8.6
2
2
Hz, CH), 136.7 (d, J PC ) 17.1 Hz, C), 136.6 (d, J PC ) 14.7
2
Hz, C), 135.4 (CH), 135.4 (CH), 135.0 (d, J PC ) 8.6 Hz, CH),
2
2
134.7 (d, J PC ) 12.3 Hz, CH), 134.6 (d, J PC ) 11.0 Hz, CH),
2
2
134.5 (d, J PC ) 12.3 Hz, CH), 134.3 (d, J PC ) 12.3 Hz, CH),
134.2 (CH), 134.1 (CH), 133.9 (CH), 132.9 (CH), 132.7 (d, 1J PC
3
) 56.3 Hz, C), 132.5 (CH), 131.8 (CH), 129.8 (d, J PC ) 11.0
3
3
Hz, CH), 129.7 (d, J PC ) 12.3 Hz, CH), 129.4 (d, J PC ) 11.0
3
1
Hz, CH), 129.3 (d, J PC ) 11.0 Hz, CH), 128.0 (d, J PC ) 62.5
1
1
Hz, C), 127.8 (d, J PC ) 62.5 Hz, C), 126.0 (d, J PC ) 42.9 Hz,
1
C), 120.4 (d, J PC ) 50.2 Hz, C), 75.5 (CH), 71.9 (CH2), 67.6
(CH2); 1 C and 1 CH were not resolved due to overlap. IR
(CHCl3): νmax/cm-1 (CO) 2012 (s). ES-MS: m/z 907 (M+) 879
(M+ - CO).
X-r a y Str u ctu r e Deter m in a tion of 6. The structure was
solved by automated Patterson techniques using DIRDIF.29
One of the Pd coordination sites shows substitutional disorder.
A 0.892/0.108 C2H3O/Cl disorder model (including a corre-
sponding splitting of the Pd site, to accommodate the slightly
Hyd r osilyla tion of Acetop h en on e. A mixture of aceto-
phenone (0.25 mL, 2 mmol) and rhodium complex 11 (9.8 mg,
0.01 mmol) in toluene (0.5 mL) was stirred for 10 min. Then,
diphenylsilane (0.4 mL, 2 mmol) was added and the mixture
was stirred for 3 days at room temperature and analyzed by
NMR. δH (CDCl3): 1.5 (d, J ) 7.0 Hz, 3H, CH3),a 2.4 (s, 3H,
CH3),e 2.6 (s, 3H, CH3),c 4.5 (d, J ) 2.5 Hz, 1H, CH2),b 4.8 (d,
J ) 2.5, 1H, CH2),b 4.9 (s, 2H, H2Si),d 5.0 (q, J ) 7.0, 1H, CH),a
(25) de Boer, J . L.; Duisenberg, A. J . M. Acta Crystallogr. 1984, A40,
C410.
(26) Spek, A. L. Acta Crystallogr. 1990, A46, C34.
(27) Sheldrick, G. M. SHELXL93, Program for crystal structure
refinement; University of Go¨ttingen, Go¨ttingen, Germany, 1993.
(28) Spek, A. L. J . Appl. Crystallogr. 1988, 21, 578.

644 Organometallics, Vol. 17, No. 4, 1998
van den Beuken et al.
deviating Pd coordination plane) was used in the refinement.
The minor Cl disorder form is found in the usual square-planar
position at 2.28 Å from Pd. The chlorine sits in the pocket
occupied by an acetate anion for the major disorder form. The
low occupancy (0.11) of the Cl site excludes detection of other
scattering matter in the “acetate pocket”. Hydrogen atoms
were introduced at calculated positions and refined riding on
their carrier atoms. The largest residual density in the final
difference map is near Pd.
X-r a y Str u ctu r e Deter m in a tion of 9. The structure was
solved by direct methods using SHELXS86.30 The central part
(between the two N atoms) of the molecule appears to be
disordered and was refined with a disorder model (50:50).
Additional data were collected to investigate the possibility
that the unit cell is primitive and not C-centered. The result
was negative: the average I/σ(I) was found to be 0.44 (i.e. well
below the noise level), and the maximum I/σ(I) was only 5.9
for reflection (0,7,-3). Attempts to refine the structure in the
spacegroup P21/c were, as was expected, unstable and point
to the same disorder described above. Hydrogen atoms were
included in calculated positions. The structure contains small
voids (at 0.5, 0.177, 0.250 and symmetry-related sites) of
28 Å3. However, no residual electron density was found
there.
X-r a y Str u ctu r e Deter m in a tion of 10. The structure was
solved by automated Patterson techniques using DIRDIF.25
An empirical correction for absorption was done with PLA-
TON/DELABS (correction range 0.799-1.188). Reflection
profiles were structured and were found unsuitable for the
collection of reliable ψ-scan data and their use for a ψ-scan-
based correction for absorption. Hydrogen atoms were in-
cluded in calculated positions.
X-r a y Str u ctu r e Deter m in a tion of 11. The structure was
solved by automated Patterson techniques using DIRDIF.25
Hydrogen atoms were included in calculated positions. The
highest residual density in the difference map is found in the
CH2Cl2 solvent area (indicating some unresolved disorder) and
near rhodium (absorption artifacts).
(29) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;
Garc´ıa-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla, C. The
DIRDIF Program System; Technical Report of the Crystallography
Laboratory, University of Nijmegen, Nijmegen, The Netherlands, 1992.
(30) Sheldrick, G. M. SHELXS86, Program for Crystal Structure
Solution; University of Go¨ttingen, Go¨ttingen, Germany, 1986.
Su p p or tin g In for m a tion Ava ila ble: X-ray crystallo-
graphic files for 6 and 9-11, in CIF format, are available.
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OM970464E