Reactivity of (NBu4)[Pt(C6F5)2(acac)] toward electrophilic metal centers: Metal-metal vs metal-Cγ(acac) bond formation. Crystal structure of a complex containing a μ2-acac-O,O′ bridging ligand and a coordinated dichloromethane

Article abstract of DOI:10.1021/om950878c

The reaction between (NBu₄)[Pt(C₆F₅)₂(acac)] and AgClO₄ (1:1 molar ratio) in CH₂Cl₂ at room temperature gives the neutral tetranuclear complex [PtAg(C₆F₅)₂(acac)]₂ (1) in a good yield. The structure, which has been determined by single-crystal X-ray diffraction methods, shows two anionic fragments [Pt(C₆F₅)₂(acac)]^- linked by two Ag⁺ atoms, each silver center being bonded to a Pt atom of one fragment and to an oxygen atom of the acac ligand of the other fragment. Noteworthy structural features are the O-acac coordination of the silver atom (instead of the more usual C^γ coordination) and the unexpected presence of a dichloromethane molecule coordinated to the silver center. The reaction of 1 with tht (tht = SC₄H₈, tetrahydrothiophene) or PPh₃ gives the dinuclear complexes [PtAg(C₆F₅)₂(acac)-(L)] (L = tht (2), PPh₃ (3)) by cleavage of the O-Ag bond; alternatively, complexes 2 and 3 can be one-pot synthesized by reaction of (NBu₄)[Pt(C₆F₅)₂(acac)] and O₃ClOAgL (L = tht, PPh₃). Their structural characterization points to the presence of donor-acceptor Pt→Ag bonds. Different behavior is observed in the reaction of (NBu₄)[Pt(C₆F₅)₂(acac)] with O₃-ClOAuPPh₃, giving the dinuclear complex [PtAu(μ-acac)(C₆F₅)₂(PPh₃)] (4) in which, as can be seen from its spectroscopic data, the gold atom is bonded to C^γ of the acac ligand.

Full text of DOI:10.1021/om950878c

Organometallics 1996, 15, 1813-1819
1813
Rea ctivity of (NBu 4)[P t(C6F 5)2(a ca c)] tow a r d
Electr op h ilic Meta l Cen ter s: Meta l-Meta l vs
Meta l-Cγ(a ca c) Bon d F or m a tion . Cr ysta l Str u ctu r e of
[P tAg(C6F 5)2(a ca c)(CH2Cl2)]2, a Com p lex Con ta in in g a
µ2-a ca c-O,O′ Br id gin g Liga n d a n d a Coor d in a ted
Dich lor om eth a n e
J uan Fornie´s,* Francisco Mart´ınez, Rafael Navarro, and Esteban P. Urriolabeitia
Departamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
Received November 7, 1995X
The reaction between (NBu4)[Pt(C6F5)2(acac)] and AgClO4 (1:1 molar ratio) in CH2Cl2 at
room temperature gives the neutral tetranuclear complex [PtAg(C6F5)2(acac)]2 (1) in a good
yield. The structure, which has been determined by single-crystal X-ray diffraction methods,
shows two anionic fragments [Pt(C6F5)2(acac)]- linked by two Ag+ atoms, each silver center
being bonded to a Pt atom of one fragment and to an oxygen atom of the acac ligand of the
other fragment. Noteworthy structural features are the O-acac coordination of the silver
atom (instead of the more usual Cγ coordination) and the unexpected presence of a
dichloromethane molecule coordinated to the silver center. The reaction of 1 with tht (tht
) SC4H8, tetrahydrothiophene) or PPh3 gives the dinuclear complexes [PtAg(C6F5)2(acac)-
(L)] (L ) tht (2), PPh3 (3)) by cleavage of the O-Ag bond; alternatively, complexes 2 and 3
can be one-pot synthesized by reaction of (NBu4)[Pt(C6F5)2(acac)] and O3ClOAgL (L ) tht,
PPh3). Their structural characterization points to the presence of donor-acceptor PtfAg
bonds. Different behavior is observed in the reaction of (NBu4)[Pt(C6F5)2(acac)] with O3-
ClOAuPPh3, giving the dinuclear complex [PtAu(µ-acac)(C6F5)2(PPh3)] (4) in which, as can
be seen from its spectroscopic data, the gold atom is bonded to Cγ of the acac ligand.
In tr od u ction
The synthesis of polynuclear Pt-Ag complexes by
using (perhalophenyl)platinate substrates and silver
complexes or silver salts is well established, and a great
variety of stoichiometries and structures have been
obtained in the last few years.1 However, although
attempts to synthesize similar Pd-Ag complexes have
been carried out, we have not been successful. In the
reaction between the (perhalophenyl)palladate sub-
strates and the [AgL]+ fragment, due to the higher
lability of the palladium complexes which display a
stronger arylating capability, AgC6X5 is formed, pre-
cluding the formation of the polynuclear Pd-Ag deriva-
tives.2
In an attempt to prepare complexes containing Pd-
Ag bonds we have recently studied the reactions be-
tween (NBu4)[M(C6F5)2(acac)] (M ) Pd, Pt) and AgClO4
since, with these metalate complexes which contain a
chelating ligand and a lower number of C6F5 groups, a
decrease of the number of undesirable reaction path-
ways would be expected. In fact, the reactions in a 2:1
(M:Ag) molar ratio render the trinuclear species
(NBu4)[M2Ag(C6F5)4(acac)2] (M ) Pd, Pt) which, surpris-
ingly, display very different structures (see Figure 1).3
X Abstract published in Advance ACS Abstracts, March 1, 1996.
(1) Uso´n, R.; Fornie´s, J . Inorg. Chim. Acta 1992, 198-200, 165.
(2) Uso´n, R.; Fornie´s, J .; Toma´s, M.; Ara, I.; Casas, J . M.; Mart´ın,
A. J . Chem. Soc., Dalton Trans. 1991, 2253.
(3) Fornie´s, J .; Navarro, R.; Toma´s, M.; Urriolabeitia, E. P. Orga-
nometallics 1993, 12, 940.
F igu r e 1. Schematic representation of (A) [Pt2Ag(C6F5)4-
(acac)2]- and (B) [Pd2Ag(C6F5)4(acac)2]-.
The platinum derivative is formed through Pt-Ag bonds
(Figure 1A), while the palladium one does not show any
0276-7333/96/2315-1813$12.00/0 © 1996 American Chemical Society

1814 Organometallics, Vol. 15, No. 7, 1996
Sch em e 1. Rea ction s P er for m ed for th e Syn th esis of Com p lexes 1-4
Fornie´s et al.
Pd-Ag bond, the silver center being connected to the
[Pd(C6F5)2(acac)]- moiety through Ag-Cγ bonds, with
the acetylacetonate acting as a bridging ligand (Figure
1B). These results not only show the different basicities
of the palladium and the platinum metal centers but
also indicate that in the [Pt(C6F5)2(acac)]- fragment at
least both the Pt center and the Cγ atom of the
acetylacetonate could act as basic centers and that by
reaction of (NBu4)[Pt(C6F5)2(acac)] and AgClO4, in ad-
equate molar ratios, complexes of higher nuclearity with
both the Pt and the Cγ atoms bonded to silver could be
obtained.
In this paper we study the reaction between (NBu4)-
[Pt(C6F5)2(acac)] and AgClO4 in a 1:1 molar ratio which
renders a tetranuclear derivative. In addition we have
also studied the reactions of (NBu4)[Pt(C6F5)2(acac)]
with O3ClOMPPh3 (M ) Ag, Au) which result in the
formation of binuclear Pt/M species which also display
different structures.
F igu r e 2. Molecular structure of complex 1. Thermal
ellipsoids represent 50% probability contours.
result of the symmetrical cleavage of the tetranuclear
unit and coordination of the ligand L to the silver center
(Scheme 1). Complexes 2 and 3 can also be obtained
directly by reacting (NBu4)[Pt(C6F5)2(acac)] with the
corresponding O3ClOAgL (L ) tht, PPh3) derivative in
CH2Cl2 at room temperature, although in lower yields.
These data suggest that 2 and 3 are the result of the
binding of the [AgL]+ fragment to the [Pt(C6F5)2(acac)]-
moiety through Pt-Ag bonds (see Scheme 1). Com-
plexes 1-3 are nonconducting in CH2Cl2 but behave as
1:1 electrolytes in acetone,4 indicating that the donor
solvent is able to cleave both the Pt-Ag and Ag-O
bonds forming the ionic species [Pt(C6F5)2(acac)]- and
[Ag(acetone)x]+ or [Ag(PPh3)(acetone)x′]+.
Resu lts a n d Discu ssion
Rea ction s betw een (NBu 4)[P t(C6F 5)2(a ca c)] a n d
AgClO4 or O3ClOAgL (L) th t, P P h 3). The reaction
of (NBu4)[Pt(C6F5)2(acac)] with the equimolecular amount
of AgClO4 in CH2Cl2 at room temperature results in the
formation of a tetranuclear complex of stoichiometry
[Pt2Ag2(C6F5)4(acac)2] (1). The structure of 1 (X-ray
diffraction; see Figure 2), which will be discussed in
detail later, indicates that, as expected, each silver
center is connected to two Pt(C6F5)2(acac) moieties. It
is therefore reasonable to assume that the reaction of
this tetranuclear complex 1 with neutral monodentate
ligands in the adequate molar ratio will result in the
formation of species of lower nuclearity. Thus, 1 reacts
with S- or P-donor ligands, such as tht (SC4H8, tetrahy-
drothiophene) or PPh3 in a 1:2 molar ratio, producing
the corresponding binuclear complexes [PtAg(C6F5)2-
(acac)(tht)] (2) or [PtAg(C6F5)2(acac)(PPh3)] (3) as a
Experimental details, analytical results and spectro-
scopic data for complexes 1-3 are given in the Experi-
mental Section. The structure of 1 has been established
by X-ray diffraction methods. The structural assign-
(4) Geary, G. Coord. Chem. Rev. 1971, 7, 81.

[PtAg(C6F5)2(acac)(CH2Cl2)]2
Organometallics, Vol. 15, No. 7, 1996 1815
Sch em e 2
Ta ble 1. Cr ysta llogr a p h ic Da ta for Com p lex 1
ments of 2 and 3 have been carried out on the basis of
their spectroscopic data.
complex
formula
M
Pt2Ag2(C6F5)4(acac)2(CH2Cl2)2
Pt2Ag2C36H18F20O4Cl4
1642.23
yellow blocks
0.4 × 0.6 × 0.7
monoclinic
P21/n
10.072(2)
12.932(3)
17.049(3)
93.74(3)
2215.92
293
Attempts to prepare similar palladium complexes
failed in all cases. Equations 1-3 in Scheme 2 sum-
marize the reactions attempted: (a) By reaction of
(NBu4)[Pd(C6F5)2(acac)] with AgClO4 (1:1 molar ratio,
CH2Cl2, room temperature) the trinuclear complex
(NBu4)[Pd2Ag(C6F5)4(acac)2], which we had prepared on
previous occasions3 (Figure 1B), was obtained together
with (NBu4)(ClO4) and unreacted AgClO4 (eq 1). (b) The
reaction between (NBu4)[Pd(C6F5)2(acac)] and O3-
ClOAgPPh3 (1:1 molar ratio, CH2Cl2, room temperature)
gave [Pd(C6F5)(acac)(PPh3)] together with (NBu4)(ClO4)
and deposition of silver. This seems to be an arylation
process in which the AgC6F5 or C6F5AgPPh3 formed
decomposes to silver under the reaction conditions (eq
2). (c) Finally, the reaction between (NBu4)[Pd2Ag-
(C6F5)4(acac)2] and PPh3 renders a mixture of (NBu4)-
[Pd(C6F5)2(acac)] and [Pd(C6F5)(acac)(PPh3)] (eq 3), the
formation of which can easily be understood by assum-
ing that the PPh3 initially produces the cleavage of the
trinuclear compound, giving (NBu4)[Pd(C6F5)2(acac)]
and [PdAg(C6F5)2(acac)(PPh3)], the latter decomposing
with a similar transarylation pathway to that the
described in eq 2.
color
cyst size (mm)
cryst system
space group
a (Å)
b (Å)
c (Å)
â (deg)
V (Å3)
T (K)
Z
D
2
2.46
calc (g/cm3)
F(000)
1496.00
7.53
4.0-50.0
3883
µ (mm-1
)
2θ range (deg)
no. of unique data
no. of data with F > 4.0σ(F)
3000
0.0465
R
wR
0.0645
g ) 0.0018
0.001
w-1 ) 1/(σ2(F) + g(F2))
max D/S
scan type
ω-θ
largest diff peak (e Å-3
)
1.45
largest diff hole (e Å-3
transm factors
max
)
-1.39
0.0685
0.0367
292
min
no. of refined params
Rea ction betw een (NBu 4)[P t(C6F 5)2(a ca c)] a n d
O3ClOAu L (L ) th t, P P h 3). The behavior of (NBu4)-
[Pt(C6F5)2(acac)] toward AgClO4 or O3ClOAgL prompted
us to study the reaction of this platinum anionic
compound with the gold derivatives O3ClOAuL (L )
PPh3, tht). The reaction of (NBu4)[Pt(C6F5)2(acac)] with
a solution of freshly prepared O3ClOAuPPh3 (1:1 molar
ratio, CH2Cl2, room temperature) allows the dinuclear
derivative [PtAu(µ-acac)(C6F5)2(PPh3)] (4) (see Scheme
1) to be obtained, as expected. However, in spite of the
analogous stoichiometry of [PtAg(C6F5)2(acac)(PPh3)] (3)
and complex 4, some interesting differences in the
structural data (which are discussed later) indicate that
in 4 the cation [AuPPh3]+ is connected to the platinum
substrate by a Cγ-Au bond (see Scheme 1). This
different behavior in the coordination mode of [Pt-
(C6F5)2(acac)]- unity toward [AuPPh3]+ when compared
to [AgPPh3]+ is in keeping with the high tendency of
the Au(I) center to form Au-C bonds.5,6 Complex 4 is
nonconducting in CH2Cl2, and its acetone solution
presents a conductivity which is lower than the expected
for a 1:1 electrolyte. These facts indicate that the Au-C
bonds are preserved in a noncoordinating solvent al-
though in acetone these Au-C bonds are partially
dissociated. We have also studied the reaction of
(NBu4)[Pt(C6F5)2(acac)] with O3ClOAu(tht) (1:1 molar
ratio) with the aim of preparing a tetranuclear deriva-
-
tive similar to 1 by displacing both OClO3 and tht
ligands from the gold center. Unfortunately, all at-
tempts (even those carried at low temperature) resulted
in the decomposition and formation of a gold mirror.
X-r a y Cr ysta l Str u ctu r e of [P t2Ag2(C6F 5)4(a ca c)2-
(CH2Cl2)2]. A drawing of the molecule is shown in
Figure 2. Experimental details concerning data collec-
tion and structure solution and refinement are given
in Table 1 and in the Experimental Section. Selected
bond distances (Å) and angles (deg) are given in Table
2. As it can be seen, the tetrametallic compound is
formed by two anionic fragments [Pt(C6F5)2(acac)]- and
two silver ions. Each silver atom is bonded to a
platinum center of one of the anionic fragments and to
an oxygen atom of the acetylacetonato ligand of the
other fragment. Moreover, a dichloromethane molecule
is also coordinated to each silver center as a monoden-
tate ligand.
The Pt-Ag distance [Pt(1)-Ag(1a) ) 2.758(1) Å] is
slightly longer than that found in (NBu4)[Pt2Ag(C6F5)4-
(acac)2],3 although it is within the usual range found in
other complexes containing Pt-Ag bonds.1 The Pt-Ag
bond forms an angle of 9.82(2)° to the perpendicular of
(5) Schmidbaur, H. Encyclopedia of Inorganic Chemistry; King, R.
B., Ed.; J ohn Wiley & Sons: West Sussex, England, 1994; Vol. 3, p
1332.
(6) Puddephatt, R. J . The Chemistry of Gold; Clark, R. J . H., Ed.;
Elsevier: Amsterdam, 1978; p 98.

1816 Organometallics, Vol. 15, No. 7, 1996
Fornie´s et al.
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg)
Pt(1)-Ag(1)
Pt(1)-O(2)
Pt(1)-C(12)
Ag(1)-O(2)
Ag(1)-Pt(1A)
O(1)-C(1)
C(1)-C(2)
C(2)-C(3)
C(18)-Cl(1)
3.072(1)
2.072(8)
2.012(12)
2.405(7)
2.758(1)
1.281(16)
1.396(19)
1.381(16)
1.608(33)
Pt(1)-O(1)
Pt(1)-C(6)
Pt(1)-Ag(1A)
Ag(1)-Cl(1)
Ag(1)-Ag(1A)
O(2)-C(3)
C(1)-C(4)
C(3)-C(5)
C(18)-Cl(2)
2.052(8)
2.014(11)
2.758(1)
2.776(8)
2.920(2)
1.297(13)
1.478(18)
1.491(17)
1.715(32)
Ag(1)-Pt(1)-O(1)
O(1)-Pt(1)-O(2)
O(1)-Pt(1)-C(6)
120.0(2)
90.3(3)
178.8(4)
132.3(3)
174.5(4)
59.8(1)
91.5(2)
94.0(3)
133.4(2)
120.2(1)
99.2(2)
81.4(2)
65.4(1)
86.3(2)
132.2(7)
Ag(1)-Pt(1)-O(2)
Ag(1)-Pt(1)-C(6)
O(2)-Pt(1)-C(6)
51.4(2)
60.4(3)
89.2(4)
90.4(4)
90.0(4)
81.1(2)
100.0(3)
42.3(2)
124.1(2)
131.7(2)
54.7(1)
Ag(1)-Pt(1)-C(12)
O(2)-Pt(1)-C(12)
Ag(1)-Pt(1)-Ag(1A)
O(2)-Pt(1)-Ag(1A)
C(12)-Pt(1)-Ag(1A)
Pt(1)-Ag(1)-Cl(1)
Pt(1)-Ag(1)-Pt(1A)
Cl(1)-Ag(1)-Pt(1A)
O(2)-Ag(1)-Ag(1A)
Pt(1A)-Ag(1)-Ag(1A)
Pt(1)-O(2)-Ag(1)
Ag(1)-O(2)-C(3)
O(1)-C(1)-C(4)
O(1)-Pt(1)-C(12)
C(6)-Pt(1)-C(12)
O(1)-Pt(1)-Ag(1A)
C(6)-Pt(1)-Ag(1A)
Pt(1)-Ag(1)-O(2)
O(2)-Ag(1)-Cl(1)
O(2)-Ag(1)-Pt(1A)
Pt(1)-Ag(1)-Ag(1A)
F igu r e 3. Environment of the silver atom in 1.
of to the Cγ atom, in spite of the well-known ability of
this ligand to involve the Cγ atom in coordination.14,15
In fact, in a similar situation for (NBu4)[Pd2Ag(C6F5)4-
(acac)2]3 the silver center is bonded to the Cγ and not to
the O atom (Figure 1B). This peculiar coordination
mode shown in 1 could be explained if we take into
account that the bonding of Ag to Pt and to O favors
the proximity of both Ag atoms, which could in this way
be involved in a Ag-Ag interaction.
Cl(1)-Ag(1)-Ag(1A) 150.9(2)
Pt(1)-O(1)-C(1)
Pt(1)-O(2)-C(3)
O(1)-C(1)-C(2)
125.2(8)
124.5(7)
125.4(11)
118.9(12)
124.9(11)
119.2(11)
128.0(8)
130.3(9)
113.0(12)
115.7(12) C(2)-C(1)-C(4)
128.4(11) O(2)-C(3)-C(2)
115.9(10) C(2)-C(3)-C(5)
119.2(8)
116.4(9)
C(1)-C(2)-C(3)
O(2)-C(3)-C(5)
Pt(1)-C(6)-C(7)
Pt(1)-C(12)-C(13)
Cl(1)-C(18)-Cl(2)
Pt(1)-C(6)-C(11)
Pt(1)-C(12)-C(17)
112.5(18) Ag(1)-Cl(1)-C(18)
It is also noteworthy that a molecule of dichloro-
methane is coordinated to each silver center through
one of the chlorine atoms; i.e., the dichloromethane (a
typical noncoordinating solvent) is acting as a mono-
dentate ligand. The Ag(1)-Cl(1) distance [2.776(8) Å]
is within the range of distances found in the literature
for the few Ag-chloroalkane complexes16,17 which con-
tain significantly covalent Ag-Cl bonds. The Ag(1)-
Cl(1)-C(18) angle is 113.0(12)°, which is slightly higher
than the Ag-Cl-C angles found in complexes contain-
ing both bidentate16 or monodentate17 chlorocarbon
ligands.
the platinum coordination plane.7 However, no metal-
metal-bonding interaction seems to be present between
the silver atom bonded to the acetylacetonato group and
the platinum center which is also bonded to this
chelating ligand [Pt(1)-Ag(1) ) 3.072(1) Å]. In addi-
tion, each silver center is bonded to one acetylacetonato
ligand although not through the Cγ atom, which is
usually the donor atom,3,8 but through one of the oxygen
atoms, which becomes three-coordinated. The acac
group remains essentially planar, showing that no
substantial structural changes have taken place in the
acetylacetonato-Pt ring after silver coordination.7 This
contrasts with the structure of (NBu4)[Pd2Ag(C6F5)4(µ2-
acac)2], which displays a nonplanar acetylacetonato-
palladium ring with a boat conformation due to the
presence of the Cγ-Ag bond.3 The dihedral angle
between the best least-square planes defined by Pt(1)-
O(1)-O(2)-C(6)-C(12) and O(1)-O(2)-C(1)-C(3) is
12.22(2)°.
The Ag(1)-O(2) distance [2.405(7) Å] is similar,
within experimental error, to that found in [AgNi-
(acac)3‚2AgNO3‚H2O]9 [2.46(7) Å]. As a result of the
O-coordination of the Ag+ center, one should expect
slightly longer Pt-O distances for the oxygen atoms
which are also bonded to the silver center [O(2)] than
for the others, although no significant differences,
within experimental errors, are observed.
Finally, as is usual in most of these pentafluorophenyl
Pt-Ag complexes,1 one of the pentafluorophenyl rings
is oriented so as to produce a short o-F‚‚‚Ag contact
[Ag(1a)‚‚‚F(10): 2.655(2) Å, F ) 1.34] which is in the
low end of the range for other complexes of this type.1
As a result of all these interactions, the silver center is
five coordinated and its environment is represented in
Figure 3.
Sp ectr oscop ic Stu d ies for Com p lexes 1-4. Two
IR-active absorptions, the νst(CO, acac)18a (about 1600
cm-1) and the Π(CH)18b (out-of-plane bending mode)
(11) Bachechi, F.; Ott, J .; Venanzi, L. M. J . Am. Chem. Soc. 1985,
107, 1760.
(12) Uso´n, R.; Fornie´s, J .; Menjo´n, B.; Cotton, F. A.; Falvello, L. R.;
Toma´s, M. Inorg. Chem. 1985, 24, 4651 and references given therein.
(13) Housecroft, C. E. Coord. Chem. Rev. 1992, 115, 141 and
references therein.
(14) Rigby, W.; Lee, H.; Bailey, P. M.; McCleverty, J . A.; Maitlis, P.
M. J . Chem. Soc., Dalton Trans. 1979, 387.
(15) Smith, M. E.; Hollander, F. J .; Andersen, R. A. Angew. Chem.,
Int. Ed. Engl. 1993, 32, 1294.
(16) Colsman, M. R.; Newbound, T. D.; Marshall, L. J .; Noirot, M.
D.; Miller, M. M.; Wulfsberg, G. P.; Frye, J . S.; Anderson, O. P., Strauss,
S. H. J . Am. Chem. Soc. 1990, 112, 2349 and references therein.
(17) Van Seegen, D. M.; Anderson, O. P.; Strauss, S. H. Inorg. Chem.
1992, 31, 2987.
(18) (a) Bock, B.; Flatau, K.; J unge, H.; Kuhr, M.; Musso, H. Angew.
Chem., Int. Ed. Engl. 1971, 10, 225. (b) Lewis, J .; Long, R. F.; Oldham,
C. J . Chem. Soc. A 1965, 6740.
The distance between both silver atoms [Ag(1)-
Ag(1a) ) 2.920(2) Å] is slightly longer than that found
in the metallic silver (2.8894 Å)10 and falls within the
range of distances found for other complexes with
silver-silver interactions (2.82 - 2.99 Å).11-13
It is somewhat surprising that the silver center is
bonded to one of the O atoms of the acac ligand instead
(7) Nardelli, M. Comput. Chem. 1983, 7, 95.
(8) Kawaguchi, S. Coord. Chem. Rev. 1986, 70, 51.
(9) Watson, W. H. J .; Lin, C. T. Inorg. Chem. 1966, 5, 1074.
(10) CRC Handbook of Chemistry and Physics, 61st ed.; Chemical
Rubber Publishing Co.: Cleveland, OH, 1980; p F219.

[PtAg(C6F5)2(acac)(CH2Cl2)]2
Organometallics, Vol. 15, No. 7, 1996 1817
Ta ble 3. Releva n t IR (ν, cm -1) a n d 13C{1H} NMR (δ,
indicating that dissociative processes are probably tak-
ing place in the NMR time scale. The 19F NMR spectra
of 1-3, at room temperature, undergo a systematic
change upon addition of (NBu4)[Pt(C6F5)2(acac)]. The
pattern remains similar but the chemical shifts of all
resonances are changed, and those due to Fpara suffer
more significant modifications than the others. No
signals of free [Pt(C6F5)2(acac)]- are observed. All these
facts indicate that in the CD2Cl2 solutions of 1-3 partial
dissociative processes involving [Pt(C6F5)2(acac)]- are
operating at room temperature.
p p m ) Da ta
compd
νst(CO) Π(CH) δ(Cγ) δ(CO)
(NBu4)[Pt(C6F5)2(acac)]
(NBu4)[Pd(C6F5)2(acac)]
1580
1587
780 101.34 183.16
770 99.40 185.86
(NBu4)[Pt2Ag(C6F5)4(acac)2] (A) 1570
(NBu4)[Pd2Ag(C6F5)4(acac)2] (B) 1600
795 101.89 185.39
84.05 193.51
[Pt2Ag2(C6F5)4(acac)2] (1)
1581
1564
1565
1610
a
88.72 192.61
[PtAg(C6F5)2(acac)(tht)] (2)
[PtAg(C6F5)2(acac)(PPh3)] (3)
[PtAu(C6F5)2(acac)(PPh3)] (4)
800 101.14 186.20
790 102.68 186.24
95.83 197.97
a
See text.
The 19F NMR spectra of complexes 2 and 3 remain
unalterated at low temperature (CD2Cl2, -90 °C).
However the 19F NMR spectrum of 1 under the same
conditions shows that the resonance corresponding to
the ortho-F is split into two resonances while only one
resonance of Fpara is observed. This means at low
temperature (a) that at least the species [Pt(C6F5)2(acac)]-
is not participating in the dissociative process, (b) that
1 is not present in solution since two inequivalent C6F5
and CH3 groups would be observed, and (c) that the
species in solution should present, on the NMR time
scale, a mirror plane containing the Pt, Ag, and Cγ
atoms. However, the species present in solution cannot
be unambiguously established with these spectroscopic
data.
The 19F NMR spectrum of 4, at room temperature,
reveals the usual pattern of three resonances (AA′MM′X
spin system) showing that both pentafluorophenyl
groups and both halves of each C6F5 group behave as
equivalents. A CD2Cl2 solution of 4 behaves as 1 upon
addition of (NBu4)[Pt(C6F5)2(acac)] so that a reasonable
explanation could be partial dissociation. At low tem-
perature (CD2Cl2, -90 °C) the signal corresponding to
Fortho splits into two resonances showing that the
dissociative process is not taking place under these
conditions.
The 13C{1H} NMR spectrum (see Table 3) of 1 shows,
at room temperature, an important upfield shift of the
Cγ and a downfield shift of the carbonyl resonances with
respect to (NBu4)[Pt(C6F5)2(acac)]. Similar behavior has
been observed previously in (NBu4)[Pd2Ag(C6F5)4(acac)2]
when compared to the starting compound (NBu4)[Pd-
(C6F5)2(acac)]. In this case, these shifts were understood
to be a result of the higher keto character of the acac
ligand in the trinuclear complex compared to that of the
mononuclear one due to the Cγ-Ag interaction (Figure
1B). Therefore, the 13C{1H} NMR spectrum of 1 seems
to indicate that species with Cγ-Ag interactions must
be present in solution. For complex 4 the Au-Cγ
interaction could account for the similar shifts observed
(upfield shift for Cγ and downfield shift for the carbonyl).
However, no displacement of these signals was observed
for 2 and 3, thus indicating, as expected, that the acac
ring does not interact with the silver atom. Similar
behavior has been observed previously in (NBu4)[Pt2-
Ag(C6F5)4(acac)2] when it was compared with the start-
ing compound (NBu4)[Pt(C6F5)2(acac)].3
(about 800 cm-1) of the acac ligand in these complexes
provide important structural information concerning the
coordination mode of M+ or ML+ cations to the platinum
fragment. Table 3 shows the νst(CO, acac) and the Π-
(CH) absorptions for 1-4, together with the correspond-
ing absorptions for the platinum starting materials. In
addition, the absorptions of (NBu4)[Pt2Ag(C6F5)4(acac)2]
(A) (Figure 1A) and (NBu4)[Pd2Ag(C6F5)4(acac)2] (B)
(Figure 1B), which were prepared on a previous occa-
sion,3 and which were characterized by X-ray diffraction
methods, are also given in Table 3. As can be seen, A
(which contains Pt-Ag bonds) shows the Π(CH) absorp-
tion at about 800 cm-1, while we observe a decrease of
the wavenumber of ν(CO) compared to the correspond-
ing absorptions in the starting material (NBu4)[Pt-
(C6F5)2(acac)]. Since ν(CO) and Π(CH) of 2 and 3 behave
in a similar way, it can be inferred that bonding between
the anionic and the cationic fragments in these com-
plexes is through Pt-Ag bonds (see Scheme 1). For
complex B, which contains Cγ-Ag bonds instead of the
Pd-Ag ones (Figure 1B), an increase of the absorption
due to ν(CO) and the disappearance of the Π(CH) (a
change of the hybridization of the Cγ atom from sp2 to
sp3 takes place) can be observed and this behavior is
similar to that observed for ν(CO) and Π(CH) in 4,
showing that in the latter the [AuPPh3]+ fragment is
connected to the platinum one through a Cγ-Au bond.
For complex 1, which contains Pt-Ag and Ag-O bonds,
no change in the ν(CO) is observed. The Π(CH) absorp-
tion, which should appear at about 800 cm-1, is not
observed, probably because it is overlapped by the
nearest internal absorptions of the C6F5 groups,19 since
this Π(CH) absorption has to be IR active due to the
planarity of the acac ring (X-ray structure).
The 1H NMR spectra of complexes 1-4 at room
temperature reveal two singlets, one corresponding to
the CγH and the other to the CH3 protons of the acac
group. In addition, resonances of the tht ligand (two
broad multiplets) were found for complex 2 and a set of
multiplets (7-8 ppm) indicates the presence of Ph
groups in complexes 3 and 4. The 31P{1H} NMR
spectrum of 3 shows the presence of a resonance as a
doublet of doublets due to the coupling of the 31P nucleus
with the two active silver isotopes. A singlet resonance
at 33.46 ppm is observed in the 31P{1H} NMR spectrum
of 4.
The 19F NMR spectra of 1-3 at room temperature
The mass spectra of complexes 1-4 provide additional
information about their behavior in solution. Thus, in
no case was the molecular peak observed in these
spectra and peaks corresponding to species such as
[Pt(C6F5)2(acac)]- (in all spectra), [Pt2Ag(C6F5)4(acac)2]-
(in 1-3), [Pt2Au(C6F5)4(acac)2]- (in 4), or even [Pt3Ag2-
(C6F5)6(acac)3]- were observed in the negative FAB
show three sets of signals which correspond to Fortho
,
Fpara, and Fmeta, with a typical AA′MM′X spin system.
Both the 1H and the 19F NMR spectra of 1 at room
temperature do not reflect the solid-state structure,
(19) Uso´n, R.; Fornie´s, J . Adv. Organomet. Chem. 1988, 28, 219 and
references therein.

1818 Organometallics, Vol. 15, No. 7, 1996
Fornie´s et al.
[P tAg(C6F 5)2(a ca c)(th t)] (2). Meth od a . To a solution
of (NBu4)[Pt(C6F5)2(acac)] (0.250 g, 0.287 mmol) in 25 mL of
CH2Cl2 was added O3ClOAg(tht) (0.085 g, 0.287 mmol), and
the mixture was stirred at room temperature for 30 min with
exclusion of light. The resulting colorless solution was evapo-
rated to dryness, and Et2O (20 mL) was added. The insoluble
(NBu4)(ClO4) was separated, the solution was evaporated to
dryness, and the oily residue was treated with n-hexane (20
mL) and stirried continuously, giving 2 (0.191 g, 81% yield)
as a white solid.
spectra. In addition, peaks corresponding to species
such as [Ag(PPh3)]+ or [Ag(PPh3)2]+ (for 3) and [Au-
(PPh3)]+ or [Au(PPh3)2]+ (for 4) were observed in the
positive FAB spectra. The presence of these species in
solution is in keeping with the existence of partial
dissociative processes, as we have postulated on the
basis of the NMR data.
Con clu sion
Meth od b. [Pt2Ag2(C6F5)4(acac)2] (1) (0.100 g, 0.068 mmol)
was dissolved in 15 mL of Et2O, and tht (12 µL, 0.136 mmol)
was added. The solution was stirred at room temperature for
30 min with exclusion of light and then evaporated to dryness.
Addition of n-hexane (20 mL) and continuous stirring gave 2
(0.080 g, 71% yield). Anal. Calc for C21H15AgF10O2PtS: C,
30.59; H, 1.83; S, 3.89. Found: C, 30.71; H, 1.70; S, 4.12. ΛM
(Ω-1 cm2 mol-1): 2.70 (CH2Cl2), 101.3 (acetone). IR (cm-1):
1502, 1062, 960 (vs, C6F5), 1275 (w, tht), 811, 802 (s, X-
sensitive C6F519). 1H NMR: δ 5.40 (s, 1H, CH, acac), 3.02 (m,
4H, R-CH2, tht), 2.00 (m, 4H, â-CH2, tht), 1.82 (s, 6H, CH3,
The work reported in this paper has shown the
polydentate character of the anionic platinate complex
(NBu4)[Pt(C6F5)2(acac)] which can act as a metallo
ligand toward electrophilic substrates. With silver
derivatives, bimetallic complexes containing Pt-Ag
bonds are obtained and, using an adequate molar ratio
of the reactants, a tetrametallic complex containing both
Pt-Ag and Ag-O(acac) bonds is formed. In reaction
with gold derivatives only the Cγ(acac) atom acts as a
base, forming Au-C bonds. The X-ray structure of the
tetranuclear derivative shows two unusual features:
Ag-O(acac) coordination as a result of the silver-silver
interaction and coordination of a molecule of dichlo-
romethane to each silver center.
acac). 19F NMR: δ -120.76 (d, 2F, Fortho
,
3J Pt-F ) 499 Hz),
o
-162.35 (t, 1F, Fpara), -164.89 (m, 2F, Fmeta). 13C{1H} NMR:
δ 150.08 (1J F-C ) 216 Hz), 137.50 (1J F-C ) 242 Hz), 135.93
(1J F-C ) 250 Hz) (C6F5), 36.32 (R-CH2, tht), 31.38 (â-CH2, tht),
27.60 (CH3, acac).
[P tAg(C6F 5)2(a ca c)(P P h 3)] (3). Meth od a . To a solution
of (NBu4)[Pt(C6F5)2(acac)] (0.300 g, 0.344 mmol) in 25 mL of
CH2Cl2 was added O3ClOAgPPh3 (0.161 g, 0.344 mmol), and
the resulting solution was stirred at room temperature for 1
h, with exclusion of light. Complex 3 (0.244 g, 71% yield) was
isolated as a white powder following the same workup as that
described for complex 2 in method a.
Meth od b. To a solution of [Pt2Ag2(C6F5)4(acac)2] (1) (0.100
g, 0.069 mmol) in 15 mL of Et2O was added PPh3 (0.036 g,
0.136 mmol), and the resulting solution was stirred at room
temperature for 30 min with exclusion of light. Following the
same workup as that described for complex 2 in method b, 3
was isolated (0.075 g, 56% yield). Anal. Calc for
Exp er im en ta l Section
Solvents were dried and distilled under nitrogen prior to
use: diethyl ether over benzophenone ketyl, dichloromethane
over P2O5, and n-hexane over sodium. Elemental analyses
were carried out on a Perkin-Elmer 240-B microanalyzer.
Molar conductances were carried out on a Philips PW9509
conductivity meter in acetone and dichloromethane solutions
(5 × 10-4 M). IR spectra (4000-200 cm-1) were recorded on a
Perkin-Elmer 883 infrared spectrophotometer in Nujol mulls
between polyethylene sheets. NMR spectra were recorded in
CDCl3 or CD2Cl2 at room temperature (otherwise specified)
on Varian Unity 300 and on Bruker ARX 300 spectrometers.
1H and 13C{1H} NMR spectra were referenced to the residual
protons of the solvent as an internal standard, 19F to CFCl3
and 31P{1H} to H3PO4 (85%). Mass spectra were recorded on
a V.G. Autospec. (NBu4)[M(C6F5)2(acac)]20 (M ) Pd, Pt), O3-
C
35H22AgF10O2PPt: C, 42.10; H, 2.22. Found: C, 42.07; H,
2.03. ΛM (Ω-1 cm2 mol-1): 3.52 (CH2Cl2), 89.0 (acetone). IR
(cm-1): 1505, 1063, 959 (vs, C6F5), 812, 802 (s, X-sensitive
C6F519), 541, 517, 503 (s, PPh3). 1H NMR: δ 8.0-7.0 (m, 15
H, Ph), 5.45 (s, 1H, CH, acac), 1.84 (s, 6H, CH3, acac). 19F
3
22
ClOAgL21 (L ) PPh3, tht), and ClAuPPh3 were prepared
NMR: δ -121.10 (d, 2F, Fortho, J Pt-F ) 470 Hz), -161.70 (t,
o
1F, Fpara), -164.50 (m, 2F, Fmeta). 31P{1H} NMR: δ 12.26 (dd,
according to published methods. Sa fety n ote: Perchlorate
salts of metal complexes with organic ligands are potentially
explosive! Only small amounts of these materials should be
prepared, and they should be handled with great caution.
[P t2Ag2(C6F 5)4(a ca c)2] (1). To a solution of (NBu4)[Pt-
(C6F5)2(acac)] (0.216 g, 0.248 mmol) in 25 mL of CH2Cl2 was
added AgClO4 (0.052 g, 0.248 mmol) and the mixture was
stirred at room temperature for 3 h. The solution was then
evaporated to dryness, and the residue was treated with 30
mL of Et2O and stirred continuously. A white solid of (NBu4)-
(ClO4) remained insoluble and was filtered off. The resulting
solution was evaporated to dryness and the yellow residue was
stirred with n-hexane, giving 1 (0.158 g, 87% yield) as a yellow
solid. Anal. Calc for C34H14Ag2F20O4Pt2: C, 27.73; H, 0.96.
Found: C, 28.11; H, 1.07. ΛM (Ω-1 cm2 mol-1): 3.5 (CH2Cl2),
90.8 (acetone). IR (cm-1): 1508, 1066, 958 (vs, C6F5), 815, 806
(s, X-sensitive C6F519). 1H NMR: δ 5.77 (s, 1H, CH, acac), 2.14
1
1
109
107
J
) 784.8 Hz, J
) 680.6 Hz). 13C{1H} NMR: δ
Ag-P
Ag-P
150.20 (1J F-C ) 220 Hz), 137.86 (1J F-C ) 242 Hz), 136.28 (1J F-C
) 252 Hz) (C6F5), 134.14 (2J P-C ) 16 Hz), 131.96, 129.82 (3J P-C
) 10 Hz), 129.43 (1J P-C ) 65 Hz) (PPh3), 27.71 (CH3, acac).
[P tAu (µ-a ca c)(C6F 5)2(P P h 3)] (4). To a solution of 0.345
mmol of O3ClOAuPPh3 in 25 mL of CH2Cl2 (prepared from
0.170 g of ClAuPPh3 and 0.072 g of AgClO4) was added (NBu4)-
[Pt(C6F5)2(acac)] (0.270 g, 0.310 mmol), and the colorless
solution was stirred at room temperature for 30 min. The
resulting solution was evaporated to dryness, and the residue
was treated with Et2O (30 mL). After separation of the
insoluble (NBu4)(ClO4), the ether solution was evaporated to
dryness and the residue was treated with n-hexane (25 mL)
yielding 4 (0.156 g, 50%). Anal. Calc for C35H22AuF10O2PPt:
C, 38.65; H, 2.04. Found: C, 38.37; H, 1.86. ΛM (Ω-1 cm2
mol-1): 9.77 (CH2Cl2), 24.08 (acetone). IR (cm-1): 1500, 1060,
958 (vs, C6F5), 811, 800 (s, X-sensitive C6F519), 540, 505 (s,
PPh3). 1H NMR: δ 8.0-7.0 (m, 15 H, Ph), 5.23 (s, 1H, CH,
acac), 2.17 (s, 6H, CH3, acac). 19F NMR: δ -119.75 (d, 2F,
(s, 6H, CH3, acac). 19F NMR: δ -121.50 (d, 2F, Fortho, J Pt-F
3
o
) 496 Hz), -157.98 (t, 1F, Fpara), -162.30 (m, 2F, Fmeta). 13C-
{1H} NMR: δ 149.90 (1J F-C ) 225 Hz), 138.79 (1J F-C ) 243
Hz), 136.58 (1J F-C ) 250 Hz) (C6F5), 28.56 (CH3, acac).
Fortho
,
3J Pt-Fo ) 478 Hz), -163.50 (t, 1F, Fpara), -165.96 (m,
2F, Fmeta). 31P{1H} NMR: δ 33.46. 13C{1H} NMR: δ 150.53
(1J F-C ) 229 Hz), 137.18 (1J F-C ) 242 Hz), 136.05 (1J F-C
)
(20) Uso´n, R.; Gimeno, J .; Fornie´s, J .; Mart´ınez, F. Inorg. Chim. Acta
1981, 50, 173.
(21) Cotton, F. A.; Falvello, L. R.; Uso´n, R.; Fornie´s, J .; Toma´s, M.;
Casas, J . M.; Ara, I. Inorg. Chem. 1987, 26, 1366.
(22) Bruce, M. I.; Nicholson, B. K.; Shawkataly, O. B. Inorg. Synth.
1989, 26, 325.
241 Hz) (C6F5), 134.58 (2J P-C ) 14 Hz), 132.72, 129.86 (3J P-C
) 11 Hz), 128.39 (1J P-C ) 61 Hz) (PPh3), 29.13 (CH3, acac).
P r ep a r a tion of Cr ysta ls for X-r a y Str u ctu r e Deter m i-
n a tion . Suitable crystals for X-ray purposes were obtained

[PtAg(C6F5)2(acac)(CH2Cl2)]2
Organometallics, Vol. 15, No. 7, 1996 1819
by slow diffusion of n-hexane into a CH2Cl2 solution of complex
1 (typically 40-60 mg of 1 in 2 mL of CH2Cl2) at -18 °C.
X-r a y Str u ctu r e An a lysis. Diffraction data were collected
on a Siemens/STOE-AED2 diffractometer with graphite-mono-
chromated Mo KR radiation and were corrected for Lorentz
and polarization effects. The refined cell constants and the
most relevant data for this complex are collected in Table 1.
The SHELXTL PLUS23 crystallographic software package was
used. A total of 4323 reflections were collected in the range
of 4° < 2θ < 50° (hkl: 0 to 12, 0 to 15, -20 to 20) using ω-θ
scans. Absorption correction was based on ψ-scan solutions
(heavy metal atom) (maximum and minimum transmission
factors: 0.0685 and 0.0367, respectively). The structure was
solved by the Patterson method and refined to R ) 0.0465 and
wR ) 0.0645 [3000 reflections with F > 4.0σ(F) and 292
variables]. The hydrogen atoms were not located. All atoms
(except for the solvent) were refined with anisotropic displace-
ment parameters. The highest peak on the final difference
Fourier map corresponds to 1.45 e Å-3 (largest difference hole
-1.39 e Å-3), and it is located close to the uncoordinated
chlorine atom of the CH2Cl2 molecule. However, attempts to
refine it as disordered CH2Cl2 failed. Selected bond distances
and bond angles are given in Table 2.
Ack n ow led gm en t. We thank the Direccio´n General
de Investigacio´n Cient´ıfica y Te´cnica (Spain) for finan-
cial support (Project PB92-0364).
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates and U values, complete bond distances and angles,
and anisotropic thermal parameters for 1 (4 pages). Ordering
information is given on any current masthead page.
(23) Siemens Analytical X-Ray Instruments, Inc., SHELXTL PLUS
Software Package, Release 4.11/V, Madison, WI, 1990.
OM950878C