Reactivity of [NBu4][(C6F5) 2M(μ-PPh2)2M′(acac-O,O′)] (M, M′ = Pt, Pd) toward Silver Centers. Synthesis of Polynuclear Complexes Containing M-Ag Bonds (M = Pd, Pt)

Article abstract of DOI:10.1021/om034047f

The binuclear complexes [NBu₄][(C₆F₅) ₂M(μ-PPh₂)₂M′(acac-O.O′)] (M = M′ = Pt, la; M = Pt, M′ = Pd, Ib; M = M′ = Pd, 1c) have been prepared by reacting [NBu₄]₂(C₆F ₅)₂M(μ-PPh₂) ₂M′(μ-Cl)₂M′(μ-PPh₂) ₂M(C₆F₅)₂] with Tl(acac). Complexes 1a,b react with [Ag(OClO₃)-(PPh₃)], yielding [MPtAg(μ-PPh₂)₂(C₆F_{5 2}(acac)(PPh₃)] (M = Pt, 2a; M = Pd, 2b). The X-ray structures of both complexes are rather similar, the main difference being related with the Pt-Ag bonds. While in 2b it is clear that there are Pt-Ag and Pd-Ag bonds, in 2a it seems that only one Pt-Ag bond is connecting both Pt and AgPPh₃ moieties. The formation of a Pd-Ag bond is rather surprising, because of the known reluctance of the Pd center to engage in this sort of bonding. 1a,b react with equimolar amounts of AgClO₄ in CH ₂Cl₂ to give [PtMAg(μ-PPh₂) ₂(C₆F₅)₂(acac)]_x (M = Pt, 4a; M = Pd, 4b). The X-ray structure of 4a indicates that the Pt ₂(acac)(C₆F₅)₂(μ-PPh ₂) fragments are connected to the silver center through two Pt-Ag bonds (2.875(1), 2.864(1) A) and one C^γ-Ag bond (of the acac ligand). On the other hand, when the homodinuclear palladium derivative reacts with [Ag(OClO₃(PPh₃)] or AgClO ₄, decomposition takes place and [(C₆F ₅(PPh₃Pd(μ-PPh₃Pd(acac)] can be detected in the former reaction. These processes are in agreement with the well-known tendency of the pentafluorophenyl-palladate substrates to participate in arylating processes.

Full text of DOI:10.1021/om034047f

Organometallics 2003, 22, 5011-5019
5011
Rea ctivity of [NBu 4][(C6F 5)2M(µ-P P h 2)2M′(a ca c-O,O′)]
(M, M′ ) P t, P d ) tow a r d Silver Cen ter s. Syn th esis of
P olyn u clea r Com p lexes Con ta in in g M-Ag Bon d s
(M ) P d , P t)†
Ester Alonso,‡ J uan Fornie´s,*,‡ Consuelo Fortun˜o,‡ Antonio Mart´ın,‡,§ and
A. Guy Orpen§
Departamento de Qu´ımica Inorga´nica and Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain, and School of Chemistry,
University of Bristol, Cantocks Close, Bristol BS8 ITS, U.K.
Received J uly 17, 2003
The binuclear complexes [NBu4][(C6F5)2M(µ-PPh2)2M′(acac-O,O′)] (M ) M′ ) Pt, 1a ; M )
Pt, M′ ) Pd, 1b; M ) M′ ) Pd, 1c) have been prepared by reacting [NBu4]2[(C6F5)2M(µ-
PPh2)2M′(µ-Cl)2M′(µ-PPh2)2M(C6F5)2] with Tl(acac). Complexes 1a ,b react with [Ag(OClO3)-
(PPh3)], yielding [MPtAg(µ-PPh2)2(C6F5)2(acac)(PPh3)] (M ) Pt, 2a ; M ) Pd, 2b). The X-ray
structures of both complexes are rather similar, the main difference being related with the
Pt-Ag bonds. While in 2b it is clear that there are Pt-Ag and Pd-Ag bonds, in 2a it seems
that only one Pt-Ag bond is connecting both Pt and AgPPh3 moieties. The formation of a
Pd-Ag bond is rather surprising, because of the known reluctance of the Pd center to engage
in this sort of bonding. 1a ,b react with equimolar amounts of AgClO4 in CH2Cl2 to give
[PtMAg(µ-PPh2)2(C6F5)2(acac)]x (M ) Pt, 4a ; M ) Pd, 4b). The X-ray structure of 4a indicates
that the “Pt2(acac)(C6F5)2(µ-PPh2)” fragments are connected to the silver center through two
Pt-Ag bonds (2.875(1), 2.864(1) Å) and one Cγ-Ag bond (of the acac ligand). On the other
hand, when the homodinuclear palladium derivative reacts with [Ag(OClO3)(PPh3)] or
AgClO4, decomposition takes place and [(C6F5)(PPh3)Pd(µ-PPh2)2Pd(acac)] can be detected
in the former reaction. These processes are in agreement with the well-known tendency of
the pentafluorophenyl-palladate substrates to participate in arylating processes.
Sch em e 1
In tr od u ction
Earlier work in our laboratory has established that
anionic (perhalophenyl)platinate complexes behave as
Lewis bases and react with silver derivatives to afford
polynuclear complexes displaying donor-acceptor Pt-
Ag bonds.1 As far as the dinuclear platinate complexes
are concerned, in cases such as [NBu4]2[(C6F5)2Pt(µ-
X)2Pt(C6F5)2] (X ) Cl, C6F5) they react with silver
derivatives, yielding the trinuclear complexes [NBu4][Pt2-
Ag(µ-X)2(C6F5)4L] (Scheme 1, type A) and acting as
bidentate chelating ligands toward the silver center.2-4
In a similar way the dinuclear complexes [NBu4][(C6F5)2-
Pt(µ-dppm)(µ-X)Pt(C6F5)2] (X ) Cl, Br, OH) react with
[Ag(OClO3)L], forming trinuclear derivatives with two
Pt-Ag bonds (donor-acceptor bonds).5
† Polynuclear Homo- or Heterometallic Palladium(II)-Platinum(II)
Pentafluorophenyl Complexes Containing Bridging Diphenylphosphido
Ligands. 13. Part 12: ref 34.
‡ Universidad de Zaragoza-CSIC.
§ University of Bristol.
(1) Fornie´s, J .; Mart´ın, A. In Metal Clusters in Chemistry; Braun-
stein, P., Oro, L. A., Raithby, P. R., Eds.; Wiley-VCH: Weinheim,
Germany, 1999; Vol. 1, pp 417-443.
To our surprise, the reactions of the di- and trinuclear
phosphido complexes [NBu4]2[Pt2(µ-PPh2)2(C6F5)4] and
[NBu4]2[Pt3(µ-PPh2)4(C6F5)4] with AgClO4 result in the
formation of Ag(0) and platinum complexes with Pt in
an oxidation state higher than II, [(C6F5)2Pt(µ-PPh2)2-
Pt(C6F5)2]6 (Scheme 1, type B) and [(C6F5)2Pt(µ-PPh2)2-
Pt(µ-PPh2)2Pt(C6F5)2],7 but not in complexes with Pt-
Ag bonds.
(2) Uso´n, R.; Fornie´s, J .; Toma´s, M.; Casas, J . M.; Cotton, F. A.;
Falvello, L. R. Inorg. Chem. 1987, 26, 3482-3486.
(3) Uso´n, R.; Fornie´s, J .; Toma´s, M.; Casas, J . M.; Cotton, F. A.;
Falvello, L. R.; Llusar, R. Organometallics 1988, 7, 2279-2285.
(4) Casas, J . M.; Fornie´s, J .; Mart´ın, A.; Menjo´n, B.; Toma´s, M.
Polyhedron 1996, 15, 3599-3604.
(5) Casas, J . M.; Falvello, L. R.; Fornie´s, J .; Mart´ın, A. Inorg. Chem.
1996, 35, 7867-7872.
10.1021/om034047f CCC: $25.00 © 2003 American Chemical Society
Publication on Web 10/28/2003

5012 Organometallics, Vol. 22, No. 24, 2003
Alonso et al.
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for
[NBu 4][P tP d (µ-P P h 2)2(C6F 5)2(a ca c)]‚Me2CO
(1b‚Me2CO)
Pt-C(1)
2.064(3)
2.3006(8)
2.2459(9)
2.075(3)
Pd-O(1)
Pd-P(2)
Pt-P(1)
Pd-O(2)
2.083(2)
2.2594(9)
2.2852(9)
2.105(2)
Pt-P(2)
Pd-P(1)
Pt-C(7)
C(1)-Pt-C(7)
C(7)-Pt-P(1)
C(7)-Pt-P(2)
O(1)-Pd-O(2)
O(2)-Pd-P(1)
O(2)-Pd-P(2)
Pd-P(1)-Pt
90.76(12)
C(1)-Pt-P(1)
C(1)-Pt-P(2)
P(1)-Pt-P(2)
O(1)-Pd-P(1)
O(1)-Pd-P(2)
P(1)-Pd-P(2)
Pd-P(2)-Pt
95.09(9)
170.03(9)
75.27(3)
94.84(7)
171.63(7)
76.85(3)
102.57(3)
172.55(9)
98.65(9)
90.07(9)
173.69(7)
98.28(7)
103.49(3)
whereas in [Pd2(µ-PPh2)2(F6acac-O,O′)2] the Pd-O dis-
tances are 2.098(5) and 2.111(4) Å and the O-Pd-O
angle is 88.8°. Also, for [Pd2(µ-PPh2)2(F6acac-O,O′)2] the
intermetallic distance (3.565(1) Å) and the M-P-M
angles (105.8(1)°) are similar to those found in 1b, but
the “Pd2(µ-PPh2)2” core is perfectly planar. In 1b, the
acac ligand has a planar configuration, forming a
dihedral angle with the best Pd square plane of 12.1(1)°.
In the case of [Pd2(µ-PPh2)2(F6acac-O,O′)2], the dihedral
angle formed by the F6acac ligand (which is also planar)
with the best palladium square plane has a value of 6.8°.
The IR spectra of complexes 1a -c show two bands
at about 800 cm-1 (X-sensitive mode of the C6F5
groups),9,10 in accordance with the presence of two
F igu r e 1. Structure of the complex anion of [NBu4][PtPd-
(µ-PPh2)2(C6F5)2(acac)] (1b).
Since, in our experience, the ability of the platinate
substrates to act as Lewis bases toward silver salts is
strongly dependent on the nature of the ancillary
ligands bonded to platinum,1 we have synthesized other
binuclear M/M′ (M, M′ ) Pd, Pt) phosphido complexes
such as [NBu4][(C6F5)2M(µ-PPh2)2M′(acac)] and studied
their reactivity toward [Ag(OClO3)(PPh3)] and AgClO4.
The results of these reactions are reported in this paper.
mutually cis C
6F5 groups, and characteristic absorptions
at ca. 1580 and 1515 cm-1 due to the acac group (see
the Experimental Section). The absorption due to the
O,O′-coordinated acac group11-13 at ca. 800 cm-1 cannot
be unambiguously assigned, due to the presence in this
region of bands of the X-sensitive mode of the C6F5
Resu lts a n d Discu ssion
Syn th esis of [NBu 4][(C6F 5)2M(µ-P P h 2)2M′(a ca c-
O,O′)] (M ) M′ ) P t, 1a ; M ) P t, M′ ) P d , 1b; M )
M′ ) P d , 1c). The reaction of [NBu4]2[(C6F5)2M(µ-
PPh2)2M′(µ-Cl)2M′(µ-PPh2)2M(C6F5)2] with Tl(acac) (1:2
molar ratio) in CH2Cl2 at room temperature results in
the precipitation of TlCl and formation of [NBu4]-
[(C6F5)2M(µ-PPh2)2M′(acac-O,O′)] (M ) M′ ) Pt, 1a ; M
) Pt, M′ ) Pd, 1b; M ) M′ ) Pd, 1c).
The structure of 1b has been determined by an X-ray
diffraction study. The structure of the anion of complex
1b together with the atom-labeling scheme is shown in
Figure 1. Selected bond distances and angles are listed
in Table 1. Complex 1b is a dinuclear complex in which
the metal centers are bridged by two diphenylphosphido
ligands. The environments of both metal atoms are
typically square planar, the dihedral angle between the
two best square planes being 16.0(1)°. The long inter-
metallic distance, 3.555(1) Å, precludes any kind of Pt‚
‚‚Pd interaction. In accordance with this observation,
the Pt-P-Pd angles are large (103.49(3) and 102.57-
(3)°, respectively). The geometry observed around the
palladium atom is very similar to that reported for the
complex [Pd2(µ-PPh2)2(F6acac-O,O′)2],8 a symmetrical
dinuclear complex which also contains PPh2 bridging
ligands. Thus, for 1b the Pd-O distances are 2.083(2)
and 2.105(2) Å and the O-Pd-O angle is 90.07(9)°,
1
groups. The H NMR spectra reveal for the acac group
two singlets, one corresponding to the CγH group and
the other to the two equivalent CH3 groups. The 19F
NMR spectra show three sets of signals corresponding
to o-F, m-F, and p-F, respectively, indicating that the
two C6F5 groups are equivalent, as are the halves of
each ring. The 31P{1H} NMR spectra show one high-
field signal, in accordance with the presence of two
equivalent PPh2 groups acting as bridging ligands
between two metal centers not joined by a metal-metal
bond.7,14 It has been established that usually the chemi-
cal shift decreases as the atomic number increases from
top to bottom in a triad.15 In agreement with this, the
chemical shifts from 1c (Pd2, -115.6 ppm) to 1b (PdPt,
-134.2 ppm) and to 1a (Pt2, -144.6 ppm) show that this
P atom is shielded upon substitution of a palladium by
a platinum center, as we have observed before.7 From
1
the platinum satellites two values of J Pt-P (1912 and
(9) Uso´n, R.; Fornie´s, J . J . Adv. Organomet. Chem. 1988, 28, 219-
297.
(10) Maslowsky, E. J . Vibrational Spectra of Organometallic Com-
pounds; Wiley: New York, 1997.
(11) Fornie´s, J .; Mart´ınez, F.; Navarro, R.; Urriolabeitia, E. Orga-
nometallics 1996, 15, 1813-1819.
(12) Fornie´s, J .; Navarro, R.; Toma´s, M.; Urriolabeitia, E. Organo-
metallics 1993, 12, 940-943.
(13) Nakamoto, K. Infrared and Raman Spectra of Inorganic and
Coordination Compounds, 4th ed.; Wiley-Interscience: New York,
1986.
(6) Alonso, E.; Casas, J . M.; Cotton, F. A.; Feng, X. J .; Fornie´s, J .;
Fortun˜o, C.; Toma´s, M. Inorg. Chem. 1999, 38, 5034-5040.
(7) Alonso, E.; Casas, J . M.; Fornie´s, J .; Fortun˜o, C.; Mart´ın, A.;
Orpen, A. G.; Tsipis, C. A.; Tsipis, A. C. Organometallics 2001, 20,
5571-5582.
(14) Alonso, E.; Fornie´s, J .; Fortun˜o, C.; Mart´ın, A.; Orpen, A. G.
Organometallics 2001, 20, 850-859.
(15) Carty, A. J .; MacLaughlin, S. A.; Nucciarone, D. Phosphorus-
31 NMR Spectroscopy in Stereochemical Analysis; VCH: Weinheim,
Germany, 1987.
(8) Bekiaris, G.; Roschenthaler, G. V.; Behrens, U. Z. Anorg. Allg.
Chem. 1992, 618, 153.

Polynuclear Complexes Containing M-Ag Bonds
Organometallics, Vol. 22, No. 24, 2003 5013
Sch em e 2a
a
Legend: (a) +[Ag(OClO3)(PPh3)], -NBu4ClO4; (b) +[Ag(OClO3)(PPh3)], -Ag(C6F5), -NBu4ClO4; (c) +AgClO4, -NBu4ClO4.
2641 Hz) for 1a and a value (1785 Hz) for 1b can be
extracted. The higher value in 1a is assigned to the
coupling with the platinum center bonded to the acac
ligand. Relevant spectroscopic data for 1a -c are given
in the Experimental Section.
Rea ction s betw een [NBu 4][(C6F 5)2M(µ-P P h 2)2M′-
(a ca c-O,O′)] a n d [Ag(OClO3)(P P h 3)] or AgClO4. The
reaction of [NBu4][(C6F5)2Pt(µ-PPh2)2M(acac)] (M ) Pt,
1a ; M ) Pd, 1b) with an equimolar amount of [Ag-
(OClO3)(PPh3)] in CH2Cl2 at room temperature results
in the formation of yellow solutions from which the
trinuclear clusters [MPtAg(µ-PPh2)2(C6F5)2(acac)(PPh3)]
(M ) Pt, 2a ; M ) Pd, 2b) are obtained (Scheme 2, path
a).
The crystal structures of complexes 2a ,b have been
determined by X-ray diffraction, and they are shown in
Figures 2 and 3, respectively. Selected bond distances
and angles are listed in Tables 2 and 3, respectively.
The structures of the two complexes are very similar.
For descriptive purposes, they can be regarded as the
union of the dinuclear “(C6F5)2Pt(µ-PPh2)2M(acac)” frag-
ment with the “Ag(PPh3)” moiety through only Pt- or
Pd-Ag donor-acceptor bonds. In the first fragment the
metal atoms are linked by two diphenylphosphido
ligands, but their separation (Pt(1)-Pt(2) ) 3.515(1) Å
in 2a and Pt-Pd ) 3.478(1) Å in 2b) allows us to
exclude any kind of metal-metal bond. In both struc-
tures, the Pt and Pd atoms lie in typical square-planar
environments, but the dinuclear “(C6F5)2Pt(µ-PPh2)2M-
(acac)” fragments are not planar. The dihedral angles
between the best least-squares planes are 19.3(1)° for
2a and 33.5(1)° for 2b (compare with the value of this
parameter, 16.0(1)°, in the starting material 1b). The
acac ligands are essentially planar and almost coplanar
F igu r e 2. Structure of the complex [Pt2Ag(µ-PPh2)2(C6F5)2-
(acac)(PPh3)] (2a ).
with the square-planar environment of Pt(2) (2a , the
dihedral angle is 3.4(1)°) or Pd (2b, 5.7(1)°).
The Pt-Ag distances found in 2a are rather different.
While the Pt(1)-Ag distance is 2.793(1) Å, a value
within the range found for Pt-Ag donor-acceptor
bonds, the Pt(2)-Ag distance is somewhat long, 3.098(1)
Å, for this kind of bond.1,16 On the other hand, the Pt-
(1)-Ag vector forms an angle with the perpendicular
of the best least-squares Pt(1) plane of 21.3(1)°, while

5014 Organometallics, Vol. 22, No. 24, 2003
Alonso et al.
the M centers adopt an “open book” disposition in order
to favor the formation of the two Pt-M bonds as close
as possible to perpendicular. In this way a better overlap
2
between the filled 5dz platinum orbital and the empty
orbitals of the Lewis acidic M center can be achieved.2-5
When these facts are taken into account, it can be
concluded that in 2a there is only a Pt(1)-Ag donor-
acceptor bond and that Pt(2) is only weakly interacting
(if at all) with the Ag center.
The M-Ag distances in complex 2b are rather sur-
prising. The Pt-Ag distance, 2.733(1) Å, is similar to
the analogous length in 2a , but the Pd-Ag distance,
2.886(1) Å, is ca. 0.21 Å shorter than the Pt(2)-Ag
distance in 2a . Also, while in 2b the Pt-Ag vector forms
an angle of 18.8(1)° with the perpendicular of the best
square platinum coordination plane, a value similar to
the analogous value in 2a , the corresponding angle
involving the Pd atom is 24.3(1)°, significantly less than
the analogous value in 2a , 32.4(1)°. As mentioned above,
the dihedral angle between the two square planes of the
complex is larger for 2a than for 2b and, thus, the “book
is more closed” in the latter. All these geometrical
observations for 2b (i.e. the shorter Pd-Ag distance, the
more nearly perpendicular Pd-Ag vector, and the more
bent disposition of the “(C6F5)2Pt(µ-PPh2)2Pd(acac)”
fragment) prompt us to conclude that in 2b the silver
center is connected to the dinuclear Pt/Pd moiety
through Pt-Ag and Pd-Ag donor-acceptor bonds of
similar strength. This is a surprising result, and at this
moment no explanation for the different behaviors of
1a and 1b toward [Ag(PPh3)]+ can be given.
F igu r e 3. Structure of the complex [PtPdAg(µ-PPh2)2-
(C6F5)2(acac)(PPh3)] (2b).
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [P t2Ag(µ-P P h 2)2(C6F 5)2(a ca c)(P P h 3)]‚CHCl3
(2a ‚CHCl3)
Pt(1)-C(7)
Pt(1)-P(2)
Pt(2)-O(1)
Pt(2)-Ag
Pt(1)-C(1)
Pt(1)-Ag
2.072(8)
2.324(2)
2.078(5)
3.098(1)
2.087(9)
2.793(1)
Pt(2)-P(1)
Ag-P(3)
Pt(1)-P(1)
Pt(2)-O(2)
Pt(2)-P(2)
2.252(2)
2.392(2)
2.317(2)
2.075(5)
2.252(2)
C(7)-Pt(1)-C(1)
C(1)-Pt(1)-P(1)
C(1)-Pt(1)-P(2)
O(2)-Pt(2)-O(1)
O(1)-Pt(2)-P(1)
O(1)-Pt(2)-P(2)
P(3)-Ag-Pt(1)
Pt(1)-Ag-Pt(2)
Pt(2)-P(2)-Pt(1)
87.5(3)
172.5(3)
97.8(2)
89.5(2)
175.6(2)
96.7(2)
164.8(1)
73.0(1)
100.3(1)
C(7)-Pt(1)-P(1)
C(7)-Pt(1)-P(2)
P(1)-Pt(1)-P(2)
O(2)-Pt(2)-P(1)
O(2)-Pt(2)-P(2)
P(1)-Pt(2)-P(2)
P(3)-Ag-Pt(2)
Pt(2)-P(1)-Pt(1)
98.3(2)
174.3(2)
76.3(1)
94.7(2)
172.6(2)
79.0(1)
In addition, it has to be pointed out that although we
have tried very hard to synthesize complexes with Pd-
Ag bonds, in no case were such complexes obtained.11,17,18
This is presumably because other secondary processes,
probably related to the lability of the palladate com-
plexes, took place, preventing the formation of the Pd-
Ag-bonded complexes. The Pd-Ag distance observed in
2b is one of the shortest reported in the literature. Only
a few polynuclear Pd/Ag complexes have been reported,
but in most cases the Pd-Ag distances are longer than
3 Å,19-26 and only in two cases are the Pd-Ag distances
less than 2.9 Å: [Pd(H2O)LAg]2+ (2.884(2) Å)25 and
[Mn2Pd2Ag(µ-Cl)(µ-PPh2)2(µ-dppm)(CO)8] (2.7259(6) and
2.8014(6) Å).26 In the first case a presumably weak Pd-
C(aryl)-Ag interaction is stabilized by peripheral co-
ordination of the silver center to three oxygen atoms of
122.0(1)
100.6(1)
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for
[P tP d Ag(µ-P P h 2)2(C6F 5)2(a ca c)(P P h 3)]‚2.5CH2Cl2
(2b‚2.5CH2Cl2)
Pt-C(1)
Pt-P(2)
Pd-O(2)
Pd-Ag
Pt-C(7)
Pt-Ag
2.062(6)
2.333(2)
2.069(5)
2.886(1)
2.085(7)
2.733(1)
Pd-P(1)
Ag-P(3)
Pt-P(1)
Pd-O(1)
Pd-P(2)
2.252(2)
2.372(2)
2.297(2)
2.065(5)
2.274(2)
C(1)-Pt-C(7)
C(7)-Pt-P(1)
C(7)-Pt-P(2)
O(1)-Pd-O(2)
O(2)-Pd-P(1)
O(2)-Pd-P(2)
P(3)-Ag-Pt
Pt-Ag-Pd
88.9(2)
C(1)-Pt-P(1)
C(1)-Pt-P(2)
P(1)-Pt-P(2)
O(1)-Pd-P(1)
O(1)-Pd-P(2)
P(1)-Pd-P(2)
P(3)-Ag-Pd
Pd-P(1)-Pt
94.16(17)
167.37(18)
74.23(6)
98.08(14)
173.56(14)
76.25(7)
176.88(19)
102.65(18)
90.26(19)
170.24(14)
95.67(14)
166.26(5)
76.43(2)
(17) Falvello, L. R.; Fornie´s, J .; Mart´ın, A.; Sicilia, V.; Villarroya,
P. Organometallics 2002, 21, 4604-4610.
(18) Uso´n, R.; Fornie´s, J .; Toma´s, M.; Ara, I.; Casas, J . M.; Mart´ın,
A. J . Chem. Soc., Dalton Trans. 1991, 2253-2264.
(19) Yew-Chin-Neo; Vittal, J . J .; Hor, T. S. A. J . Chem. Soc., Dalton
Trans. 2002, 337-342.
116.02(5)
99.74(7)
Pd-P(2)-Pt
98.02(7)
(20) Ebihara, M.; Tsuchiya, M.; Yamada, M.; Tokoro, K.; Kawamura,
T. Inorg. Chim. Acta 1995, 231, 35-43.
(21) Glaum, M.; Klaui, W.; Skelton, B. W.; White, A. H. Aust. J .
Chem. 1997, 50, 1047-1052.
the Pt(2)-Ag vector forms an angle of 32.4(1)° with the
perpendicular of the best least-squares Pt(2) plane. It
is now well established that, for this kind of complex,
the stronger Pt-Ag bonds are achieved when these
bonds are nearer to perpendicular to the platinum
square coordination plane1 and that the dinuclear
platinate substrates which act as bidentate ligands to
(22) Uso´n, R.; Uso´n, M. A.; Herrero, S. Inorg. Chem. 1997, 36, 5959-
5961.
(23) Ebihara, M.; Tokoro, K.; Maeda, M.; Ogami, M.; Imaeda, K.;
Sakurai, K.; Masuda, H.; Kawamura, T. J . Chem. Soc., Dalton Trans.
1994, 3621-3635.
(24) Ardizzoia, G. A.; La Monica, G.; Cenini, S.; Moret, M.; Mascio-
cchi, N. J . Chem. Soc., Dalton Trans. 1996, 1351-1358.
(25) Kickman, J . E.; Loeb, J . J . Organometallics 1995, 14, 3584-
3587.
(16) Yamaguchi, T.; Yamazaki, F.; Ito, T. J . Am. Chem. Soc. 2001,
123, 743-744.
(26) Liu, Y.; Lee, K. H.; Vittal, J . J .; Hor, T. S. A. J . Chem. Soc.,
Dalton Trans. 2002, 2747-2751.

Polynuclear Complexes Containing M-Ag Bonds
Organometallics, Vol. 22, No. 24, 2003 5015
3
the ligand, while in the Mn/Pd/Ag cluster the silver
center is exclusively bonded to the four other metal
centers.
groups, the line width being larger than J P-P, and so
the coupling with PPh3 cannot be observed in this
3
signal. The J P-P coupling observed also indicates that
in CDCl3 a dissociative process between [AgPPh3]+ and
[(C6F5)2Pt(µ-PPh2)2M(acac)]- does not takes place in any
of the complexes.
In 2a ,b the planar three-coordination of the silver
center is completed by a PPh3 ligand. The angles around
the Ag atom are very different, the Pt(1)-Ag-P(3) angle
in 2a and the analogous Pt-Ag-P(3) angle in 2b being
very broad, 164.8(1) and 166.3(1)°, respectively.
Moreover, the 31P{1H} NMR spectrum of 2a in deu-
terioacetone has been recorded. The signal due to the P
atom of the PPh3 group appears as two doublets (two
doublets of triplets were observed in CDCl3). Addition-
ally, when the spectrum is recorded with [Ag(OClO3)-
(PPh3)] added, the pattern is the same and no signals
due to free [Ag(OClO3)(PPh3)] are observed. Both these
observations are in agreement with a dissociative
process in acetone.
The signals in the 1H NMR spectra as well as the
absorptions in the IR spectra due to the acac ligand of
2a ,b are similar to those observed for complexes 1a ,b.
Experimental details, analytical results, and spectro-
scopic data for complexes 2a ,b are given in the Experi-
mental Section.
The 19F NMR spectra of 2a ,b are very informative.
The spectrum of 2a at room temperature (CDCl3 solu-
tion) reflects the solid-state structure. It shows four
broad signals: two signals corresponding to o-F atoms
(1:1 intensity ratio), a signal corresponding to p-F atoms
(intensity ratio of 1), and a signal for the m-F atoms
(intensity ratio of 2). This pattern indicates the equiva-
lence of the two C6F5 groups and the inequivalence of
the halves of each C6F5 ring, m-F atoms being isochro-
nous. When the spectrum is measured at low temper-
ature, the pattern is the same and the signals are well
resolved. Nevertheless, the spectrum of 2b at room
temperature (CDCl3 solution) reveals three broad sig-
nals (2:1:2 intensity ratio), which correspond to o-F, p-F,
and m-F, respectively, showing that in solution a
dynamic process which makes equivalent both halves
of each C6F5 group is operating. At 213 K, the o-F signal
is split into two resonances and the pattern is the same
that for 2a . Variable-temperature 19F NMR spectra for
2b reveal the coalescence of the two o-F signals at 278
K. The approximation to Eyring’s equation gives a ∆Gq
value of 51 kJ mol-1 at the coalescence temperature.
The spectrum (CDCl3, room temperature) of 2b upon
addition of 1b shows signals due to both 2b and 1b,
indicating that fully dissociative processes which afford
1b and “AgPPh3” species can be ruled out in CDCl3. The
spectra of 2a ,b in deuterioacetone at room temperature
show two (2a , 2:3 intensity ratio, o-F and p + m-F,
respectively) or three (2b, 2:1:2 intensity ratio, o-F, p-F,
and m-F, respectively) signals, and thus, a dynamic
process which renders equivalent the halves of each
C6F5 group is operating for both complexes in deuterio-
acetone solution. For 2b the spectra at low temperature
reveal that the dynamic process is operating even at 183
K. When the spectrum of 2b is measured (deuterio-
acetone, room temperature) with 1b added, the pattern
remains similar; the chemical shifts of all resonances
are changed but no signals due to free 1b are observed.
These facts indicate that in deuterioacetone solution a
dissociative process which gives 1b and “AgPPh3” may
be operating.
The reaction between the homodinuclear palladium
complex 1c and [Ag(OClO3)(PPh3)] under similar condi-
tions takes place with decomposition (Scheme 1, path
b). The heteronuclear palladium and silver complex, if
formed, is not stable enough and the binuclear pal-
ladium complex [(C6F5)(PPh3)Pd(µ-PPh2)2Pd(acac)] (3)
is identified in the solid by H, 19F, and 31P{1H} NMR
1
spectroscopy (see the Experimental Section). As we have
previously found, the palladium complex 1c displays a
stronger arylating capability than 1a ,b. The reaction
process is probably carried out with formation of AgC6F5,
which decomposes to silver, precluding the formation
of a polynuclear palladium and silver derivative. The
same process had been observed earlier in the reaction
of other palladium complexes with [Ag(OClO3)(PPh3)].11,18
The behavior of 1a -c toward [AgPPh3]+ deserves
some comment. Obviously, and as we have observed
previously, the arylating capability (probably due to the
higher lability) of the “(C6F5)2M(µ-PPh2)2” fragment is
stronger for the Pd (1c) than for the Pt or Pt/Pd (1a ,b)
complex. In this respect, differences between 1a and 1b
are imperceptible, presumably since in this case the Pd
center is not bonded to the C6F5 groups but to a
chelating ligand (acac).
In addition, it is also surprising that despite previous
observations1 which point to the apparent reluctance of
the Pd center to engage in Pd-Ag bonds, in these
trinuclear complexes a stronger (acac)M-Ag interaction
is observed in 2b (Pd) than in 2a (Pt), which results
not only in clearly shorter M-Ag distances but also in
the fact that the booklike structure of the bidentate
metalate ligand is more closed in 2b (Pt, Pd) that in 2a
(Pt, Pt) in order to favor the M-Ag bond.
The reaction of 1a ,b with equimolecular amounts of
AgClO4 in CH2Cl2 at room temperature gives (Scheme
2, path c) yellow solutions from which yellow solids of
general formula [PtMAg(µ-PPh2)2(C6F5)2(acac)]x (M )
Pt, 4a ; M ) Pd, 4b) are obtained. These complexes show
similar IR spectra, but unlike complexes 1a -c and 2a ,b,
the absorptions due to the acac group are different. The
IR spectra of 4a ,b show two absorptions in the 1570-
1590 cm-1 region (a broad absorption in this region is
observed for 1a -c and 2a ,b) while the absorption
The 31P{1H} NMR spectra of 2a ,b in CDCl3 show
similar patterns at both room and low temperature. The
signal due to the PPh3 group appears as two doublets
of triplets by coupling with the 107,109Ag atoms (51.8%
and 48.2%, respectively) and with the two equivalent P
atoms of the PPh2 groups. From this signal the two
3
1J Ag-P and the J P-P couplings can be calculated. The
signal is slightly broadened on the base due to poorly
separated platinum satellites. The signal due to the two
equivalent PPh2 groups appears in the high-field region
as a singlet with platinum satellites, as expected for the
presence of two PPh2 groups acting as bridging ligands
between two metal centers not joined by a metal-metal
bond. This singlet is broad, as is usual in all such
derivatives in which the PPh2 groups are trans to C6F5

5016 Organometallics, Vol. 22, No. 24, 2003
Alonso et al.
environments is 25.5(1)° and the Pt(1)-Pt(2) distance
is 3.478(1) Å, precluding the existence of a Pt-Pt bond.
The two Pt-Ag bonds are of virtually the same length
(distances are Pt(1)-Ag ) 2.875(1) Å and Pt(2)-Ag )
2.864(1) Å). In this case, the angles formed by the Pt-
Ag bond lines and the perpendicular to the best square
planes are similar, 27.3(1)° for Pt(1) and 21.8(1)° for
Pt(2). All these parameters indicate that, in this com-
plex, both Pt-Ag bonds are of similar strength.
The presence of ClO4- in the reaction could have led
to the formation of a trinuclear complex, similar to 2a ,
with the perchlorate anion coordinated to the silver
center. Despite the low coordination capacity of the
perchlorate anion, complexes containing the Ag-OClO3
moiety are well-known.17,27,28 Nevertheless, in 4a the
Ag atoms complete their coordination environment by
forming a bond with the Cγ (C(14′)) carbon atom of the
acac ligand. The Ag-C(14′) distance is 2.318(11) Å,
which is slightly longer than those found in the anion
[Pd2Ag(acac)2(C6F5)4]-, which also shows the silver atom
bonded to the Cγ carbon atom of the acac ligand (the
Ag-C distance is 2.237(7) Å).12 For 4a , the Ag atom and
the three atoms bonded to it are coplanar, and the Pt-
Ag-C(14′) angles are similar (145.1(3)° for Pt(1) and
140.3(3)° for Pt(2)) and very different from the Pt(1)-
Ag-Pt(2) angle.
Due to the formation of the Ag-C(14′) bond, the acac
ligand loses its planarity. Thus, while Pt(1), O(1), O(2),
C(13), and C(15) are virtually in the same plane, the
methyl carbon atoms C(16) and C(17) deviate ca. 0.34
Å in the opposite direction to the Ag atom, and the C(14)
atom approaches the Ag atom and deviates 0.21 Å from
this plane. Nevertheless, the distortion of the acac
ligand in 4a from the noncoordinated configuration, as
found in 2a ,b (see above), is less pronounced than that
described for [NBu4][Pd2Ag(acac)2(C6F5)4].12 This fact
could be explained by taking into account that for this
complex the silver atom is two-coordinated, whereas in
4a it is three-coordinated, and thus the strength of the
Ag-C interactions is likely to be reduced, as reflected
in the longer bond length.
F igu r e 4. Structure of the complex [Pt2Ag(µ-PPh2)2(C6F5)2-
(acac)]2 (4a ).
Ta ble 4. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [P t2Ag(µ-P P h 2)2(C6F 5)2(a ca c)]2‚5.4CHCl3
(4a ‚5.4CHCl3)a
Pt(1)-O(2)
Pt(1)-Ag
Pt(2)-P(2)
Ag-C(14′)
Pt(1)-P(1)
2.092(7)
2.875(1)
2.303(3)
2.318(11)
2.267(3)
Pt(2)-C(1)
Pt(2)-P(1)
Pt(1)-P(2)
Pt(2)-C(7)
Pt(2)-Ag
2.051(11)
2.306(3)
2.269(3)
2.063(11)
2.864(1)
O(2)-Pt(1)-O(1)
O(1)-Pt(1)-P(1)
O(1)-Pt(1)-P(2)
C(1)-Pt(2)-C(7)
C(7)-Pt(2)-P(2)
C(7)-Pt(2)-P(1)
89.2(3)
96.4(2)
171.2(2)
90.2(4)
173.1(3)
97.7(3)
O(2)-Pt(1)-P(1)
O(2)-Pt(1)-P(2)
P(1)-Pt(1)-P(2)
C(1)-Pt(2)-P(2)
C(1)-Pt(2)-P(1)
P(2)-Pt(2)-P(1)
171.5(2)
96.1(2)
77.58(10)
95.8(3)
171.5(3)
76.13(10)
The 31P{1H} NMR (CD2Cl2 or CDCl3 solution) spec-
troscopic data of 4a ,b are analogous to those of the
starting material, as expected. The 19F NMR spectra of
4a ,b (CD2Cl2 or CDCl3 solution, room temperature)
show the same pattern: five signals of the same
intensity. Two of them at lower field and with platinum
satellites are assigned to the o-F atoms, and three
signals at higher field are due to m- and p-F atoms.
These spectra indicate the equivalence of the four C6F5
groups and the inequivalence of both halves of each C6F5
C(14′)-Ag-Pt(2) 140.3(3)
C(14′)-Ag-Pt(1) 145.1(3)
Pt(1)-P(1)-Pt(2) 99.03(11)
Pt(2)-Ag-Pt(1)
Pt(1)-P(2)-Pt(2)
74.61(3)
99.07(11)
a
Symmetry transformations used to generate equivalent (primed)
atoms: 1/2 - x, 5/2 - y, -z.
observed at approximately 1510-1520 cm-1 for 1a -c
and 2a ,b is not observed. Moreover, new absorptions
in the 850-840 cm-1 region are observed for 4a ,b.
Absorptions in this region have been observed for
complexes which contain the acac group coordinated
through the Cγ atom.13 These data seem to indicate that
for complexes 4a ,b the coordination mode of the acac
ligands is different than in 1a -c and 2a ,b. The struc-
ture of 4a has been elucidated by an X-ray diffraction
study (see Figure 4). Selected bond distances and angles
are listed in Table 4. The molecular formula of the
complex is [Pt2Ag(C6F5)2(PPh2)2(acac)]2. It has an inver-
sion center, and therefore, the geometries of the “Pt2-
Ag(C6F5)2(PPh2)2(acac)” halves are identical. 4a is a
hexanuclear complex, which, for description purposes,
can be regarded as two “Pt2(acac)(C6F5)2(µ-PPh2)2” frag-
ments joined by two silver atoms. In the former the
dihedral angle between the two platinum square-planar
1
ring. The H NMR (CD2Cl2 or CDCl3 solution) spectra
show in both cases a singlet for the equivalent CH3
groups of the acac ligand. The CγH protons appear as a
broad signal centered at 5.9 ppm for complex 4a and as
a doublet (9 Hz) centered at 5.7 ppm for 4b. This doublet
can be attributed to the coupling with the 107,109Ag
nuclei. Since the difference of magnetogyric ratios of
107Ag and 109Ag is small (γ(107Ag)/γ(109Ag) ) 1.15), it is
assumed that 2J (107Ag-H) ≈ 2J (109Ag-H) ≈ 9 Hz.
2
Similar coupling constants of J Ag-H have been re-
(27) Falvello, L. R.; Fornie´s, J .; Fortun˜o, C.; Dura´n, F.; Mart´ın, A.
Organometallics 2002, 21, 2226-2234.
(28) Ara, I.; Fornie´s, J .; Go´mez, J .; Lalinde, E.; Merino, R. I.; Moreno,
M. T. Inorg. Chem. Commun. 1999, 2, 62-65.

Polynuclear Complexes Containing M-Ag Bonds
Organometallics, Vol. 22, No. 24, 2003 5017
2
ported.29 In complex 4a the J Ag-H value is small and
plexes and silver salts could well be related to the
lability of the palladate substrate, which transfers R
groups to the silver and thereby prevents the formation
of the Pd-Ag bonds. The substrate 1b, in which the Pd
center is not bonded to C6F5 groups, does not produce
such transference and forms the Pd-Ag bond. Although
it seems reasonable to think that the formation of the
Pd-Ag bond is additionally favored by the chelate effect
of the metallo ligand, it is rather surprising that such
an effect is not operating in complex 2a , which does not
display two Pt-Ag bonds. We have not been able to find
a plausible explanation for this fact.
Finally, it is not surprising that 1c is not able to
produce complexes with Pd-Ag bonds in any case, since
arylating processes, which militate against the forma-
tion of Pd-Ag bonds, are operating in the reaction of
1c with Ag+ or [Ag(PPh3)]+, because one of the pal-
ladium centers is bonded to two C6F5 groups.
the coupling is not resolved. All these data are in
accordance with the solid-state structure of 4a .
Nevertheless, the H and 19F NMR spectra measured
1
in deuterioacetone are different. The 19F NMR spectra
of 4a ,b in deuterioacetone show one signal with plati-
num satellites for the o-F atoms and a signal for the m-
+ p-F atoms (intensity ratio 2:3), indicating the equiva-
lence of both halves in each C6F5 ring. The 1H NMR
spectra in deuterioacetone show the signal due to the
CγH protons as a sharp singlet. Moreover, the spectra
of 4b have been measured at 183 K and they are the
same as those at room temperature. The 19F and 1H
spectra of both 4a and 4b undergo a change upon
addition of the starting materials 1a and 1b, respec-
tively. The pattern remains similar, but the chemical
shifts of resonances have changed, and no signals due
to 1a or 1b are observed. All these facts are in agree-
ment with a dissociative process involving the starting
material; i.e., in the donor solvent both the Pt-Ag and
Ag-C bonds are cleaved, leading to formation of the
ionic species [(C6F5)2Pt(µ-PPh2)2Pt(acac)]- and [Ag-
(acetone)x]+.
Exp er im en ta l Section
Gen er a l Com m en ts. Literature methods were used to
prepare the starting material [NBu4]2[(C6F5)2M(µ-PPh2)2M′(µ-
Cl)2M′(µ-PPh2)2M(C6F5)2].30 C, H, and N analyses and IR and
NMR spectra were performed as described elsewhere.31 Molar
conductances were carried out on a Philips PW9509 conduc-
timeter in acetone and dichloromethane solutions (5 × 10-4
M).
The molar conductivities of complexes 2a ,b and 4a ,b
in dichloromethane and in acetone (see the Experimen-
tal Section) are in agreement with the dissociative
processes proposed from the NMR data.
Ca u tion ! Perchlorate salts of metal complexes with organic
ligands are potentially explosive. Only small amounts of
material should be prepared, and these should be handled with
great caution.
The reaction of [NBu4][(C6F5)2Pt(µ-PPh2)2Pt(acac)]
(1a ) and AgClO4 in a 1:2 molar ratio (CH2Cl2, room
temperature) in an attempt to form a derivative with
dicoordinated silver only gives complex 4a . On the other
hand, the reaction in a 2:1 molar ratio intended to form
a pentanuclear derivative with two [(C6F5)2Pt(µ-PPh2)2-
Pt(acac)]- fragments bonded to one silver center gives
a mixture, which contains 4a and the platinum starting
material. Both facts point to the stability of the hexa-
nuclear derivative containing three-coordinated silver.
The hexanuclear derivative 4a reacts, as expected,
with PPh3 (1:2 molar ratio), yielding the trinuclear
complex [Pt2Ag(µ-PPh2)2(C6F5)2(acac)(PPh3)] (2a), through
the selective breaking of the C-Ag bonds.
Syn th esis of [NBu 4][(C6F 5)2M(µ-P P h 2)2M′(a ca c-O,O′)].
M ) M′ ) P t (1a ). To a solution of [NBu4]2[(C6F5)2Pt(µ-PPh2)2-
Pt(µ-Cl)2Pt(µ-PPh2)2Pt(C6F5)2] (0.495 g, 0.180 mmol) in CH2-
Cl2 (25 mL) was added Tl(acac) (0.109 g, 0.360 mmol). The
mixture was stirred for 4 h, and then the solid (TlCl) was
filtered off. The resulting solution was evaporated to ca. 2 mL,
i
and PrOH (15 mL) was added. The white solid obtained, 1a ,
i
was filtered off, washed with PrOH (3 × 1 mL), and dried
under vacuum (0.449 g, 87%). Anal. Found (calcd) for C57F10H63
-
NO2P2Pt2: C, 47.7 (47.7); H, 4.8 (4.4); N, 1.1 (1.0). IR (cm-1):
781 and 773 (X-sensitive C6F5); 1579 (broad) and 1519 (ν(Cd
1
C), ν(CdO) acac). ΛM ) 71 (acetone) Ω-1 cm2 mol-1. H NMR
As previously observed, 1c does not react with AgClO4
(CH2Cl2) to form a similar hexanuclear derivative, but
decomposition and formation of Ag(0) results.
([2H]acetone, δ): 5.2 (1H, CγH, acac), 1.8 (6H, CH3, acac) ppm.
3
19F NMR ([2H]acetone, δ): -113.9 (4 o-F, J Pt,F ) 297 Hz),
-166.2 (4 m-F), -167.1 (2 p-F) ppm. 31P{1H} NMR ([2H]-
acetone, δ): -144.6 (1J Pt,P ) 2641 and 1912 Hz) ppm.
M ) P t, M′ ) P d (1b). Complex 1b was prepared similarly
from [NBu4]2[(C6F5)2Pt(µ-PPh2)2Pd(µ-Cl)2Pd(µ-PPh2)2Pt(C6F5)2]
(0.500 g, 0.195 mmol) and Tl(acac) (0.118 g, 0.389 mmol). 1b
was obtained as a yellow solid (0.368 g, 70%). Anal. Found
(calcd) for C57F10H63NO2P2PdPt: C, 50.8 (50.8); H, 4.8 (4.7);
N, 1.1 (1.0). IR (cm-1): 782 and 773 (X-sensitive C6F5); 1582
(broad) and 1512 (ν(CdC), ν(CdO) acac). ΛM ) 96 Ω-1 cm2
mol-1 (acetone). 1H NMR ([2H]acetone, δ): 5.2 (1H, CγH, acac),
1.7 (6H, CH3, acac) ppm. 19F NMR ([2H]acetone, δ): -114.0 (4
o-F, 3J Pt,F ) 321 Hz), -166.2 (4 m-F), -166.9 (2 p-F) ppm. 31P-
{1H} NMR ([2H]acetone, δ): -134.2 (1J Pt,P ) 1785 Hz) ppm.
M ) M′ ) P d (1c). Complex 1c was prepared in a manner
similar to that for 1a from [NBu4]2[(C6F5)2Pd(µ-PPh2)2Pd(µ-
Cl)2Pd(µ-PPh2)2Pt(C6F5)2] (0.350 g, 0.146 mmol) and Tl(acac)
(0.089 g, 0.293 mmol). 1c was obtained as a yellow solid (0.290
g, 78%). Anal. Found (calcd) for C57F10H63NO2P2Pd2: C, 53.9
(54.4); H, 5.1 (5.0); N, 1.0 (1.1). IR (cm-1): 775 and 769 (X-
Con clu d in g Rem a r k s
The reaction of [NBu4][(C6F5)2Pt(µ-PPh2)2M(acac)]
with [Ag(OClO3)(PPh3)] and AgClO4 gives tri- or hexa-
nuclear complexes in which the metalate fragments act
either as bidentate or as tridentate ligands. The donor
centers Pt and Pd in the former and Pt, Pd, and C (of
the acac group) in the latter are bonded to the silver
fragment.
This result is in sharp contrast with the behavior of
[NBu4]2[(C6F5)2Pt(µ-PPh2)2Pt(C6F5)2], which with Ag-
ClO4 produces the oxidation to the Pt(III) derivative
[(C6F5)2Pt(µ-PPh2)2Pt(C6F5)2] and formation of Ag0.
The formation of 2b, which contains Pt-Ag and Pd-
Ag donor-acceptor bonds, seems to indicate that the
impossibility of synthesizing complexes with Pd-Ag
bonds through the reaction of anionic palladate com-
(30) Fornie´s, J .; Fortun˜o, C.; Navarro, R.; Mart´ınez, F.; Welch, A.
J . J . Organomet. Chem. 1990, 394, 643-658.
(31) Alonso, E.; Fornie´s, J .; Fortun˜o, C.; Mart´ın, A.; Orpen, A. G.
Organometallics 2000, 19, 2690-2697.
(29) Wang, S.; Fackler, J . P. J .; Carlson, T. F. Organometallics 1990,
9, 1973-1975.

5018 Organometallics, Vol. 22, No. 24, 2003
Alonso et al.
Ta ble 5. Cr ysta l Da ta a n d Str u ctu r e Refin em en t Deta ils for [NBu 4][P tP d (µ-P P h 2)2(C6F 5)2(a ca c)]‚Me2CO
(1b‚Me2CO), [P t2Ag(µ-P P h 2)2(C6F 5)2(a ca c)(P P h 3)]‚CHCl3 (2a ‚CHCl3),
[P tP d Ag(µ-P P h 2)2(C6F 5)2(a ca c)(P P h 3)]‚2.5CH2Cl2 (2b‚2.5CH2Cl2), a n d [P t2Ag(µ-P P h 2)2(C6F 5)2(a ca c)]2‚5.4CHCl3
(4a ‚5.4CHCl3)
1b‚Me2CO
2a ‚CHCl3
2b‚2.5CH2Cl2
4a ‚5.4CHCl3
empirical formula
C
57H82F10NO2P2PdP‚
Me2CO
C
59H42AgF10O2P3Pt2‚
CHCl3
C
59H41F10O2P3AgPdPt‚
2.5CH2Cl2
C
82H52F20O4P4Ag2Pt4‚
5.4CHCl3
unit cell dimens
a (Å)
b (Å)
22.9957(13)
12.0462(6)
21.6125(12)
100.2130(10)
5892.0(6), 4
13.261(5)
22.962(7)
20.048(7)
96.63(3)
12.3204(18)
23.828(4)
20.266(3)
93.780(3)
5936.5(15), 4
30.086(5)
14.088(2)
26.994(4)
106.892(8)
10948(3), 4
c (Å)
â (deg)
V (Å3), Z
wavelength (Å)
temp (K)
radiation
6064(4), 4
0.710 73
100(1)
293(1)
100(1)
graphite monochromated
Mo KR
173(1)
cryst syst
monoclinic
space group
P21/c
P21/n
P21/n
C2/c
cryst dimens (mm)
0.45 × 0.44 × 0.40
0.50 × 0.40 × 0.30
0.41 × 0.31 × 0.29
0.50 × 0.45 × 0.40
abs coeff (mm-1
)
2.807
5.206
3.313
5.975
transmissn factors
abs cor
diffractometer
2θ range for data
collecn (deg)
1.000-0.875
SADABS33
Bruker SMART
0.90-25.03
0.601-0.481
Ψ scans
Siemens P3m
1.75-25.00
1.000-0.805
SADABS33
Bruker SMART
1.32-25.03
0.943-0.560
SADABS33
Siemens SMART
1.41-23.26
no. of rflns collected
no. of indep rflns
refinement method
goodness of fit on F2
final R indices (I > 2σ(I))a
31 413
10 386 (R(int) ) 0.0246)
11 181
10 688 (R(int) ) 0.0302)
34 674
22 693
7814 (R(int) ) 0.0532)
10 483 (R(int) ) 0.0350)
full-matrix least-squares on F2
1.040
1.253
1.011
1.514
R1 ) 0.0230
wR2 ) 0.0524
R1 ) 0.0284
wR2 ) 0.0602
R1 ) 0.0413
wR2 ) 0.0968
R1 ) 0.0626
wR2 ) 0.1146
R1 ) 0.0412
wR2 ) 0.1288
R1 ) 0.0504
wR2 ) 0.1334
R1 ) 0.0512
wR2 ) 0.1287
R1 ) 0.0688
wR2 ) 0.1418
R indices (all data)
R1 ) ∑(|Fo| - |Fc|)/∑|Fo|; wR2 ) [∑w(Fo - Fc2)2/∑w(Fc2)2]0.5
.
a
2
sensitive C6F5); 1581 and 1512 (ν(CdC), ν(CdO) acac). ΛM
)
(2 p-F), -163.3 (4 m-F) ppm. 31P{1H} NMR (CDCl3, 218 K, δ):
-122.4 (PPh2,1J Pt,P ) 1367 Hz), 9.3 (PPh3, 1J Ag,P ) 772 (109Ag)
84 Ω-1 cm2 mol-1 (acetone). 1H NMR ([2H]acetone, δ): 5.1 (1H,
CγH, acac), 1.7 (6H, CH3, acac) ppm. 19F NMR ([2H]acetone,
δ): -110.9 (4 o-F, Hz), -165.3 (4 m-F), -165.9 (2 p-F) ppm.
31P{1H} NMR ([2H]acetone, δ): -115.6 ppm.
3
and 649 (107Ag) Hz, J P,P ) 27 Hz) ppm.
Rea ction of 1c w ith [Ag(OClO3)(P P h 3)]. Following a
procedure similar to that for 2a , the reaction of 1c (0.100 g,
0.079 mmol) and an equimolecular amount of [Ag(OClO3)-
(PPh3)] (0.037 g, 0.079 mmol) gives a brown solid in which
[(C6F5)(PPh3)Pd(µ-PPh2)2Pd(acac)] (3) is identified. 1H NMR
(CDCl3, 293 K, δ): 5.2 (1H, CγH, acac), 1.7 (3H, CH3, acac),
1.6 (3H, CH3, acac) ppm. 19F NMR (CDCl3, 293 K, δ): -115.1
(2 o-F), -163.4 (3 m- + p-F) ppm. 31P{1H} NMR (CDCl3, 293
P r ep a r a tion of [P tMAg(µ-P P h 2)2(C6F 5)2(a ca c)(P P h 3)].
M ) P t (2a ). To a solution of 1a (0.125 g, 0.087 mmol) in 10
mL of CH2Cl2 was added [Ag(OClO3)(PPh3)] (0.041 g, 0.087
mmol), and the solution was stirred at room temperature for
2 h with exclusion of light. The yellow solution was evaporated
to dryness, and Et2O (10 mL) was added. The insoluble NBu4-
ClO4 was separated, the solution was evaporated to 2 mL,
n-hexane (10 mL) was added, and the mixture was stirred
vigorously, giving 2a (0.095 g, 70%) as a yellow solid. Anal.
Found (calcd) for AgC59F10H42O2P3Pt2: C, 45.5 (45.3); H, 2.6
(2.7). IR (cm-1): 787 and 780 (X-sensitive C6F5); 1560 and 1520
(ν(CdC), ν(CdO) acac). ΛM ) 1 Ω-1 cm2 mol-1 (CH2Cl2), 64
2
K, δ): 23.3 (d, PPh3, J (P,P)trans ) 354 Hz), -97.3 (dd, PPh2,
2
2J (P,P)trans ) 354 Hz, J (P,P)cis ) 153 Hz) ppm, -114.0 (d, PPh2,
2J (P,P)cis ) 153 Hz) ppm.
P r ep a r a tion of [P t2M2Ag2(µ-P P h 2)4(C6F 5)4(a ca c)2]. M )
P t (4a ). To a colorless solution of 1a (0.100 g, 0.069 mmol) in
CH2Cl2 (25 mL) was added AgClO4 (0.029 g, 0.138 mmol), and
the mixture was stirred at room temperature for 1 h and then
filtered. The yellow solution was evaporated to 1.5 mL and
left in the freezer for 3 h. A yellow solid of 4a crystallized,
which was filtered off, washed with cold CH2Cl2 (2 × 0.5 mL),
and dried under vacuum; yield 0.072 g, 80%. Anal. Found
(calcd) for Ag2C82F20H54O4P4Pt4: C, 38.0 (37.8); H, 2.3 (2.1).
IR (cm-1): 788 and 781 (X-sensitive C6F5); 1574 and 1570
(ν(CdC), ν(CdO) acac); 851 broad (acac). ΛM ) 4 Ω-1 cm2 mol-1
(CH2Cl2), 61 Ω-1 cm2 mol-1 (acetone). 1H NMR (CD2Cl2, 293
K, δ): 5.9 (2H, CγH, acac), 2.1 (12H, CH3, acac) ppm. 19F NMR
1
Ω-1 cm2 mol-1 (acetone). H NMR (CDCl3, 218 K, δ): 5.6 (1H,
CγH, acac), 2.0 (6H, CH3, acac) ppm. 19F NMR (CDCl3, 293 K,
3
3
δ): -115.9 (2 o-F, J Pt,F ) 473 Hz), -118.3 (2 o-F, J Pt,F ≈ 300
Hz), -164.1 (2 p-F), -164.6 (4 m-F) ppm. 19F NMR (CDCl3,
3
3
218 K, δ): -115.9 (2 o-F, J Pt,F ) 480 Hz), -118.1 (2 o-F, J Pt,F
) 254 Hz), -163.0 (2 p-F), -163.6 (4 m-F) ppm. 31P{1H} NMR
(CDCl3, 218 K, δ): -136.3 (PPh2,1J Pt,P ) 2269 and 1455 Hz),
6.1 (PPh3, J Ag,P ) 764 (109Ag) and 662 (107Ag) Hz, J P,P ) 29
1
3
Hz) ppm.
M ) P d (2b). Complex 2b was prepared similarly from 1b
(0.100 g, 0.074 mmol) and [Ag(OClO3)(PPh3)] (0.035 g, 0.074
3
(CD2Cl2, 293 K, δ): -115.5 (4 o-F, J Pt,F ) 479 Hz), -117.3 (4
3
o-F, J Pt,F ) 271 Hz), -162.6 (4 p-F), -163.3 (4 m-F), -163.7
mmol); yield 0.082 g, 75%. Anal. Found (calcd) for AgC59F10
-
(4 m-F) ppm. 31P{1H} NMR (CD2Cl2, 293 K, δ): -121.2 (1J Pt,P
) 2154 and 1523 Hz) ppm.
H
42O2P3PdPt: C, 48.3 (48.0); H, 2.95 (2.9). IR (cm-1): 787 and
780 (X-sensitive C6F5); 1577 and 1514 (ν(CdC), ν(CdO) acac).
ΛM ) 1 Ω-1 cm2 mol-1 (CH2Cl2), 39 Ω-1 cm2 mol-1 (acetone).
1H NMR (CDCl3, 218 K, δ): 5.4 (1H, CγH, acac), 1.8 (6H, CH3,
acac) ppm. 19F NMR (CDCl3, 293 K, δ): -117.0 (4 o-F, the
M ) P d (4b). Complex 4b was prepared similarly from 1b
(0.102 g, 0.076 mmol) in CH2Cl2 (40 mL) and AgClO4 (0.018 g,
0.087 mmol). From the dark yellow solution 4b crystallized
as a yellow solid; yield 0.056 g, 61%. Anal. Found (calcd) for
Ag2C82F20H54O4P4Pd2Pt2: C, 40.8 (40.6); H, 2.4 (2.2). IR (cm-1):
790 and 782 (X-sensitive C6F5); 1591 and 1581 (ν(CdC),
3
signal is broad and J Pt,F cannot be measured), -163.2 (2 p-F),
-163.8 (4 m-F) ppm. 19F NMR (CDCl3, 218 K, δ): -116.6 (2
3
3
o-F, J Pt,F ) 494 Hz), -118.5 (2 o-F, J Pt,F ) 245 Hz), -162.6

Polynuclear Complexes Containing M-Ag Bonds
Organometallics, Vol. 22, No. 24, 2003 5019
ν(CdO) acac); 847 and 837 (acac). ΛM ) 2 Ω-1 cm2 mol-1 (CH2-
SHELXL-93.32 All non-hydrogen atoms were assigned aniso-
tropic displacement parameters and refined without positional
constraints, except as noted below. All hydrogen atoms were
constrained to idealized geometries and assigned isotropic
displacement parameters 1.2 times the Uiso value of their
attached carbon atoms (1.5 times for methyl hydrogen atoms).
For 2b, constraints in the C-Cl distances were applied for the
half-occupancy dichloromethane solvent molecule. For 4a ,
restraints in the bond distances for the solvent molecules were
applied. Full-matrix least-squares refinement of these models
against F2 converged to the final residual indices given in Table
4. Final difference electron density maps showed no features
above 1 e/Å3 (maximum/minimum 0.90/-0.64 e/Å3) for 1b, no
features above 1 e/Å3 (maximum/minimum 0.81/-0.77 e/Å3)
for 2a , 41 features above 1 e/Å3 (maximum/minimum 2.97/-
2.90 e/Å3, the largest of which lie close to the heavy and solvent
atoms for 2b (these latter features are consistent with the
presence of systematic errors in the intensity data). Variations
in the integration proceduresschanging integration “shoebox”
sizes etc.sand in the absorption correction methods did not
improve the R(int) or final wR2 values or reduce the size of
features in the final difference map. In addition, the molecular
geometry determined remained essentially invariant through-
out). In 4a ‚5.4CHCl3 there is one feature above 1 e/Å3
(maximum/minimum 1.25/-1.40 e/Å3) close to one of the
platinum atoms.
1
Cl2), 89 Ω-1 cm2 mol-1 (acetone). H NMR (CDCl3, 293 K, δ):
2
2
107
109
5.7 (2H, J
≈ J
≈ 9 Hz, CγH, acac), 2.0 (12H, CH3,
Ag,H
Ag,H
acac) ppm. 19F NMR (CDCl3, 293 K, δ): -117.0 (4 o-F, J Pt,F
)
3
499 Hz), -118.1 (4 o-F, 3J Pt,F ) 276 Hz), -162.1 (4 p-F), -163.0
(4 m-F), -163.9 (4 m-F) ppm. 31P{1H} NMR (CDCl3, 293 K,
δ): -105.3 (1J Pt,P ) 1383 Hz) ppm.
Rea ction of 4a w ith P P h 3. To a yellow solution of 4a
(0.050 g, 0.019 mmol) in 10 mL of CH2Cl2 was added PPh3
(0.010 g, 0.038 mmol), and the solution was stirred at room
temperature for 30 min with exclusion of light. The solution
was evaporated almost to dryness, n-hexane (10 mL) was
added, and the mixture was stirred vigorously, giving 2a (0.045
g, 76%).
Cr ysta l Str u ctu r e An a lyses of [NBu 4][P tP d (µ-P P h 2)2-
(C6F 5)2(a ca c)]‚Me2CO (1b‚Me2CO), [P t2Ag(µ-P P h 2)2(C6F 5)2-
(acac)(P P h 3)]‚CHCl3 (2a‚CHCl3), [P tP dAg(µ-P P h 2)2(C6F5)2-
(a ca c)(P P h 3)]‚2.5CH2Cl2 (2b‚2.5CH2Cl2), a n d [P t2Ag(µ-
P P h 2)2(C6F 5)2(a ca c)]2‚5.4CHCl3 (4a ‚5.4CHCl3). Crystal data
and other details of the structure analysis are presented in
Table 5. Suitable crystals of 1a , 2a , 2b, and 4a were obtained
by slow diffusion of n-hexane into an acetone (1b), CHCl3 (2a
and 4a ), or CH2Cl2 (2b) solution of the complex. Crystals were
mounted at the end of a glass fiber. For 1b, unit cell
dimensions were initially determined from the positions of 729
reflections in 90 intensity frames measured at 0.3° intervals
in ω and subsequently refined on the basis of positions of 7422
reflections from the main data set. An absorption correction
was applied on the basis of 2942 symmetry-equivalent reflec-
tion intensities. For 2a , unit cell dimensions were determined
from 50 centered reflections in the range 15.0 < 2θ < 28.5°.
An absorption correction was applied on the basis of 504
azimuthal scan data. For 2b, unit cell dimensions were initially
determined from the positions of 408 reflections in 90 intensity
frames measured at 0.3° intervals in ω and subsequently
refined on the basis of positions of 6552 reflections from the
main data set. An absorption correction was applied on the
basis of 4063 symmetry-equivalent reflection intensities. For
4a , unit cell dimensions were initially determined from the
positions of 282 reflections in 90 intensity frames measured
at 0.3° intervals in ω and subsequently refined on the basis of
positions of 5556 reflections from the main data set. An
absorption correction was applied on the basis of 15505
symmetry-equivalent data. Lorentz and polarization correc-
tions were applied for all the structures.
Ack n ow led gm en t. We wish to thank the Ministerio
de Ciencia Tecnolog´ıa y Fondos FEDER (Project BQU-
2002-03997-C02-02). E.A. and A.M. acknowledge the
Diputacio´n General de Arago´n and the GES (Spain),
respectively, for their grants.
Su p p or tin g In for m a tion Ava ila ble: Further details of
the structure determinations of 1b ‚Me2CO, 2a ‚CHCl3, 2b ‚
2.5CH2Cl2, and 4a ‚5.4CHCl3, including tables of atomic coor-
dinates, bond distances and angles, and thermal parameters;
these data are also available as CIF files. This material is
available free of charge via the Internet at http://pubs.acs.org.
OM034047F
(32) Sheldrick, G. M. SHELXL-93, a Program for Crystal Structure
Determination; University of Gottingen, Gottingen, Germany, 1993.
(33) Sheldrick, G. M. SADABS Empirical Absorption Program;
University of Gottingen, Gottingen, Germany, 1996.
(34) Alonso, E.; Fornie´s, J .; Fortun˜o, C.; Mart´ın, A.; Orpen, A. G.
Organometallics 2003, 22, 2723-2728.
The structures were solved by Patterson and Fourier
methods. All refinements were carried out using the program