Synthesis of a dinuclear platinum-silver complex containing a reactive acetone imine prepared in situ from acetone and ammonia and stabilized by metal complexation

Article abstract of DOI:10.1021/om020197z

The synthesis of dinuclear platinum-silver complex, containing a reactive acetone imine was discussed. The imine was prepared in Situ from acetone and ammonia and stabilized by metal complexation. The stability of the dinuclear complex allowed full characterization of the acetone imine molecule and provided a route to stabilize new reactive imines.

Full text of DOI:10.1021/om020197z

4560
Organometallics 2002, 21, 4560-4563
Syn th esis of a Din u clea r P la tin u m -Silver Com p lex
Con ta in in g a Rea ctive Aceton e Im in e P r ep a r ed in Situ
fr om Aceton e a n d Am m on ia a n d Sta bilized by Meta l
Com p lexa tion
J ose´ M. Casas, J uan Fornie´s,* Antonio Mart´ın, and Angel J . Rueda
Departamento de Quı´mica Inorga´nicasInstituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
Received March 8, 2002
Summary: The highly reactive acetone imine can be
synthesized, from acetone and ammonia, and stabilized
in situ by coordination to a silver atom in a very selective
process which involves the presence of an (azaindolato)-
(pentafluorophenyl)platinum(II) complex. The stability
of the dinuclear complex allows full characterization of
the acetone imine molecule and provides a route to
stabilize new, reactive imines.
two C6F5 groups by other anionic ligands. We have thus
reported that [NBu4][Pt(C6F5)2acac] reacts with AgClO4
in a 2:1 or 1:1 molar ratio, yielding tri- or tetranuclear
complexes, respectively, in which the Pt-Ag bonds are
unsupported by any covalent bridging ligand.12,14
With this in mind, we decided to prepare the dianionic
complex [NBu4]2[Pt(C6F5)3(azaindolate)] (A) in order to
test its usefulness in the formation of these types of
polynuclear complexes, since the azaindolate ligand is
anionic and a well-known bridging ligand15-17 which
could, in addition, support the Pt-M bond if formed.
However, attempts to prepare complex A by reacting
[NBu4][Pt(C6F5)3(thf)] with tetrabutylammonium aza-
indolate resulted in the formation of a mixture of the
two isomers (the one containing the anionic aza ligand
bonded to the platinum center through the N atom of
the pyridine ring and the other with the anionic aza
ligand coordinated by the N atom of the pyrrole ring).18
To avoid this mixture, we were obliged to use a different
synthetic approach (formation of [Pt(C6F5)3(azaindole)]-
and once formed test the deprotonation of the azaindole
ligand), which resulted in the formation of a binuclear
Pt/Ag complex, both metals being supported by the
azaindolate ligand but the silver containing as well the
unusual acetone imine ligand. The formation of this
complex is the subject of the present paper.
In tr od u ction
It is well-known that the platinum center in anionic1,2
or neutral platinum3,4 complexes behaves as a Lewis
base and that this makes them very useful precursors
for the synthesis of heteropolynuclear complexes con-
taining donor-acceptor Pt-M bonds (M ) Ag, Sn, Pb,
Hg, Cd).5-11 (Perhalophenyl)platinate derivatives form,
through adequate reactions, a family of complexes
containing a PtxAg skeleton.2
One of the greatest difficulties found in the prepara-
tion of (pentafluorophenyl)platinate complexes contain-
ing Pt-Ag bonds is, however, the recurrence of arylating
processes. These result in the formation of AgC6F5, thus
preceding the formation of the corresponding complexes
with PtfAg bonds. The higher the number of C6F5
groups bonded to platinum, the higher the transmeta-
lating capability of the platinate fragment.12,13 Given
this, we considered that one of the ways to maintain
the anionic character of the platinum substrates (i.e. a
higher basic character) would be by substituting one or
Resu lts a n d Discu ssion
[NBu4][Pt(C6F5)3(HN2C7H5)] (1), containing a 7-aza-
indole ligand, has been prepared by treating [NBu4]2-
[Pt(C6F5)3Cl] with AgClO4 in THF (tetrahydrofuran) and
(1) Uso´n, R.; Fornie´s, J . Inorg. Chim. Acta 1992, 200, 165-177.
(2) Fornie´s, J .; Mart´ın, A. Metal Clusters in Chemistry;Wiley-VCH:
Weinheim, Germany, 1999; p 417.
1
addition of the azaindole (1:1 molar ratio). The H NMR
spectrum of complex 1 in CDCl3 at room temperature
shows a downfield-shifted signal (10.11 ppm), which
corresponds to the hydrogen bonded to the nitrogen
atom, but without platinum satellites. The other five
hydrogen atoms of the Haza ligand appear as individual
signals in the range between 6.4 and 8.5 ppm. The
hydrogen atom at the ortho position of the pyridine ring
(8.46 ppm) shows platinum satellites (J Pt-H ) 28 Hz),
(3) Kuyper, J . Inorg. Chem. 1977, 16, 2171.
(4) Chassot, L.; Zelewsky, A. Inorg. Chem. 1987, 26, 2814.
(5) Brown, P. M.; Cooper, J . S.; Frew, A. A.; Manojlovic-Muir, L.;
Muir, W. K.; Puddephatt, R. J .; Seddon, R. K. Inorg. Chem. 1981, 20,
1500.
(6) Uso´n, R.; Fornie´s, J .; Toma´s, M.; Cotton, F. A.; Falvello, L. R. J .
Am. Chem. Soc. 1984, 106, 2482.
(7) Uso´n, R.; Fornie´s, J .; Toma´s, M.; Casas, J . M.; Cotton, F. A.;
Falvello, L. R. J . Am. Chem. Soc. 1985, 107, 2556.
(8) Casas, J . M.; Fornie´s, J .; Martin, A.; Orera, V. M.; Orpen, A. G.;
Rueda, A. J . Inorg. Chem. 1995, 34, 6514.
(9) Fornie´s, J .; Mart´ın, A.; Navarro, R.; Sicilia, V.; Villarroya, P.;
Orpen, A. G. J . Chem. Soc., Dalton Trans. 1998, 3721.
(10) Yamaguchi, T.; Yamazaki, F.; Ito, T. J . Am. Chem. Soc. 1999,
121, 7405.
(11) Uso´n, R.; Fornie´s, J .; Toma´s, M. J . Organomet. Chem. 1988,
358, 525.
(12) Fornie´s, J .; Navarro, R.; Tomas, M.; Urriolabeitia, E. P.
Organometallics 1993, 12, 940-943.
(13) 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.
(14) Fornie´s, J .; Mart´ınez, F.; Navarro, R.; Urriolabeitia, E. P.
Organometallics 1996, 15, 1813-1819.
(15) Cabeza, J . A.; Oro, L. A.; Tiripicchio, A.; Tiripicchio, M. C. J .
Chem. Soc., Dalton Trans. 1988, 1437.
(16) Chan, C. K.; Guo, C. X.; Cheung, K. K.; Li, D.; Che, C. M. J .
Chem. Soc., Dalton Trans. 1994, 3677.
(17) Cotton, F. A.; Daniels, L. M.; Murillo, C. A.; Zhou, H. C. Inorg.
Chim. Acta 2000, 300, 319.
(18) See the Supporting Information.
10.1021/om020197z CCC: $22.00 © 2002 American Chemical Society
Publication on Web 09/20/2002

Notes
Organometallics, Vol. 21, No. 21, 2002 4561
thus indicating that the Haza ligand is coordinated to
the platinum atom through the pyridine ring. The 19F
NMR spectrum in CDCl3 at room temperature shows
that there are two types of C6F5 groups, the halves of
each group being equivalent (see Experimental Section).
1
The low-temperature H NMR spectrum of complex 1
in CD2Cl2 does not reveal any important differences
from the room-temperature NMR spectrum. Due to the
low temperature none of the signals show platinum
satellites. However, the 19F NMR spectra in CD2Cl2 at
low temperature show four signals for the ortho fluorine
atoms (2:1:1:2 ratio), indicating a static situation on the
NMR time scale.
In a attempt to produce the deprotonation of the
azaindole and to simultaneously prepare a polynuclear
compound, we performed the reaction of 1 in acetone
with Ag2CO3. This reagent contains the deprotonating
agent CO32- and simultaneously liberates silver cations,
which are well-recognized Lewis acids. Under these
conditions no reaction took place, probably due to the
insolubility of the Ag2CO3 in acetone. However, when a
small amount of NH3(aq) solution was added dropwise,
a reaction took place instantaneously, giving rise to an
unexpected result. From the solution the heterodinu-
clear complex [NBu4][(C6F5)3Pt(µ-aza)Ag(HNdCMe2)]
(2) was obtained. This compound, the structure of which
has been established by X-ray diffraction, contains a
molecule of acetone imine stabilized by coordination to
the silver center, as will be discussed later (eq 1).
F igu r e 1. Perspective drawing of the [(C6F5)3Pt(µ-aza)-
Ag(HNdCMe2)]- anion.
(NHdCMe2)2][PF6]2),20 and gold ([Au(NHdCMe2)2]CF3-
SO3)21 complexes and are also similar to the values
found for the dimerized acetone imine by intramolecular
hydrogen bridges (ν(CdN), 1658, 1670 (sh) cm-1
ν(N-H), 3293 cm-1).22
;
The 1H NMR spectrum of 2 in CDCl3 at room
temperature shows, in addition to the signals due to the
NBu4+ cation, five signals which can be assigned to the
7-azaindolate (aza-) and three signals which can be
assigned to the acetone imine ligand (δ 2.20 (s, 3H,
-CH3), 2.32 (s, 3H, -CH3), 8.98 (sharp s, 1H, -NH)).
These latter signals compare well with those described
for the tungsten (δ 1.23 (s, 3H, -CH3), 2.23 (s, 3H,
-CH3), 11.47 (broad s, 1H, -NH)) and gold (δ 2.39 (d,
3H, -CH3), 2.46 (s, 3H, -CH3), 10.28 (broad-s, 1H,
-NH)) complexes. The signal due to the hydrogen
bonded to the nitrogen atom appears in 2 at a lower
chemical shift than in the other cases.
Cr ysta l Str u ctu r e of [NBu 4][(C6F 5)3P t(µ-a za )Ag-
(HNdCMe2)]. Figure 1 shows the structure of the
anion. Relevant bond distances and angles are shown
in Table 2. The platinum atom is in a square-planar
environment formed by the three pentafluorophenyl
groups and the azaindolato ligand. This acts as a bridge
between the platinum and silver centers. In addition,
there is an imino group bonded to the silver atom. The
Pt-C and Pt-N distances and angles around the metal
atom (see Table 2) are within the range usually found
for this kind of Pt(II) complex.23-25 The dihedral angle
between the platinum coordination plane and the aza-
indolato plane is 65.7(3)°. The angles between the C6F5
rings and the platinum coordination plane are 75.2(4)°
for the C1 group, 68.2(4)° for the C7 group, and 57.2-
Complex 2 is stable at room temperature in the solid
state and in the absence of light. Under similar condi-
tions, its acetone solution does not decompose for at
least 5 days.
The participation of NH3 in the reaction is crucial,
since the unreacted materials are obtained if ammonia
is not present in the solution. No evidence of the
intermediates which finally result in the formation of
2 can be obtained from the reaction mixture.
The IR spectrum of 2 shows some characteristic
absorptions of the acetone imine ligand at 3334 and
1667 cm-1 which are due to ν(N-H) and ν(CdN),
respectively. These absorptions appear at frequencies
similar to those described for the acetone imine tungsten
([W(PhCtCPh)3(NHdCMe2)]),19 ruthenium ([Ru(bpy)2-
(19) Yeh, W. Y.; Ting, C. S.; Peng, S. M.; Lee, G. H. Organometallics
1995, 14, 1417.
(20) Wong, K. Y.; Che, C. M.; Li, C. K.; Chiu, W. H.; Zhou, Z. Y.;
Mak, T. C. W. J . Chem. Soc., Chem. Commun. 1992, 754.
(21) Vicente, J .; Chicote, M.-T.; Abrisqueta, M.-D.; Guerrero, R.;
J ones, P. G. Angew. Chem., Int. Ed. 1997, 36, 1203.
(22) Findeisen, K.; Heitzer, H.; Dehnicke, K. Synthesis 1981, 702
and references given therein.
(23) Uso´n, R.; Fornies, J .; Menjo´n, B.; Su¨nkel, K.; Bau, R. J . Chem.
Soc., Chem. Commun. 1984, 751.
(24) Fornie´s, J .; Menjo´n, B.; Go´mez, N.; Toma´s, M. Organometallics
1992, 11, 1187.
(25) Uso´n, R.; Fornie´s, J .; Tomas, M.; Ara, I.; Casas, J . M.; Martin,
A. J . Chem. Soc., Dalton Trans. 1991, 2253.

4562 Organometallics, Vol. 21, No. 21, 2002
Notes
Ta ble 1. Cr ysta l Da ta a n d Str u ctu r e
Refin em en t Deta ils for
[NBu 4][(C6F 5)3P t(µ-a za )Ag(HNdCMe2)] (2)
In addition, H3 forms a N3-H3‚‚‚F12 hydrogen
bridging bond, the H3-F12 distance being 2.117 Å. The
position of the H3 atom was geometrically generated
on the basis of its N3 parent atom, with a N3-H3
distance fixed at 0.900 Å.
empirical formula
unit cell dimens
a (Å)
C44H48AgF15N4Pt
11.939(4)
As far as the Ag environment is concerned, it can be
said that the silver center is two-coordinate, the Ag-N
distances being equal within experimental error and
similar to (imidazole and succinimide N-donor lig-
ands)28-30 or shorter than (pyridine and amine ligands)31
those found in other complexes containing Ag-N bonds.
The N2-Ag-N3 angle is, however, only 160.1(6)°.
Whether this perceptibly bent angle is due to a weak
Ag‚‚‚Pt interaction (3.004(2) Å)32 or to the geometrical
constraints imposed by the bulkiness of the ligands in
the molecules, the existence of an intramolecular N-H‚‚‚
F bridging bond, or both remains unclear.
b (Å)
c (Å)
14.143(4)
15.686(5)
65.66(2)
87.270(14)
74.612(12)
2321.1(13), 2
0.710 73
R (deg)
â (deg)
γ (deg)
V (Å3), Z
wavelength (Å)
temp (K)
radiation
200(1)
graphite-monochromated Mo KR
triclinic
cryst syst
space group
cryst dimens (mm)
P1h
0.27 × 0.15 × 0.11
abs coeff (mm-1
)
3.528
transmissnfactors
abs cor
diffractometer
1.000, 0.567
ψ scans
Siemens STOE/AED2
The reaction described to give complex 2 is notewor-
thy, since direct synthesis of -NH ketone imines from
ketones and ammonia requires drastic conditions and
the acetone imine is a very short-lived molecule that
polymerizes even in dilute solutions at temperature
around 200 K. N-Unsubstituted imines are very reactive
substances under normal conditions (300 K, 1 bar, air)
and suffer immediate polymerization, oxidation, or
hydrolysis.33-36 Aliphatic imines of low molecular weight
containing a N-H bond polymerize spontaneously at
temperatures below 273 K; however, imines with bulky
or electronegative substituents are much more stable.
Some examples of the formation and stabilization of
imines through deprotonated amido species of Co(III),
Ru(III), and Pt(IV) have been described by Sargeson et
al.,37-39 although in most of them the imine ligand
contains large substituents and the chelate effect aids
its stabilization. The formation and incorporation of the
acetone imine molecule acting as a ligand has been
reported recently.19-21 In two of the cases19,20 a C-N
bond was already present in the organic precursor
ligand: Yeh et al. have prepared the complex [W(PhCt
CPh)3(NHdCMe2)] by reduction with MeLi of the ac-
etonitrile coordinated to tungsten and subsequent hy-
drolysis,19 while Wong et al obtained [Ru(bpy)2(NHd
CMe2)2][PF6]2 by the electrochemical oxidation of 2,3-
dimethyl-2,3-diaminobutane coordinated to ruthenium
in a pH-dependent route.20 Very recently the acetone
imine gold complex [Au(NHdCMe2)2]CF3SO3 has been
2θ range for data collen (deg) 4.1-47.0 ((h, (k, +l)
no. of rflns collected
no. of indep rflns
7144
6853 (R(int) ) 0.0595)
full-matrix least squares on F2
1.086
refinement method
goodness of fit on F2
final R indices (I > 2σ(I))a
R1 ) 0.0693
wR2 ) 0.1647
R1 ) 0.0983
R indices (all data)a
wR2 ) 0.1882
wR2 ) [∑w(Fo - Fc2)2/∑wFo
]
0.5; R1 ) ∑||Fo| - |Fc||/∑|Fo|.
a
2
4
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [NBu 4][(C6F 5)3P t(µ-a za )Ag(HNdCMe2)] (2)
Pt-C(1)
2.052(14)
2.079(14)
2.092(15)
1.303(23)
Pt-C(7)
Pt-N(1)
Ag-N(3)
2.007(12)
2.116(11)
2.096(16)
Pt-C(13)
Ag-N(2)
N(3)-C(26)
C(7)-Pt-C(13)
C(13)-Pt-N(1)
C(13)-Pt-C(1)
90.2(5)
93.2(5)
177.4(6)
C(7)-Pt-N(1)
C(7)-Pt-C(1)
N(1)-Pt-C(1)
172.0(5)
88.4(5)
87.8(5)
(5)° for the C13 group. The short N3-C26 distance,
1.303(23) Å, is in keeping with the multiplicity of this
CdN bond.26 Moreover, the angles around N3 (Ag-N3-
C26 ) 125.3(16)°) and C26 atoms (N3-C26-C27 )
120.3(23)°, N3-C26-C28 ) 119.9(21)°, C27-C26-C28
) 119.7(21)°) are those expected for sp2-hybridized
atoms. The C26-C27 and C26-C28 distances (1.443-
(29) and 1.537(31) Å, respectively) are those expected
for C-C single bonds. The C-N distance is the usual
one for a CdN double bond and is very similar to those
observed in the tungsten (1.284(7) Å)19 and gold deriva-
tives (1.271(7) and 1.285(8) Å)21,27 but longer than the
distance found in the ruthenium complex (1.16(2) Å).20
The range of angles around these carbon atoms is
characteristic of sp2 hybridization and quite similar to
that observed in the tungsten (116.6(5)-122.6(5)°) and
gold complexes (116.9(6)-120.4(7)°), in sharp contrast
to the range of values obtained for the ruthenium
complex (99-148°). Some differences are also observed
between the three complexes in the M-NdC angles,
these being 159(1), 136.2(4), and 125.3(16)° for ruthe-
nium, tungsten, and platinum complexes, respectively,
possibly forced by the metal environment.
(28) Gagnon, C.; Hubert, J .; Rivest, R.; Beauchamp, A. L. Inorg.
Chem. 1977, 16, 2469.
(29) Antti, C. J .; Lundberg, B. K. S. Acta Chem. Scand. 1984, 25,
1758.
(30) Perron, J .; Beauchamp, A. L. Inorg. Chem. 1984, 23, 2853.
(31) Orpen, A. G.; Brammer, L.; Allen, F. H.; O., K.; Watson, D. G.;
Taylor, R. J . Chem. Soc. Dalton Trans. 1989, S1.
(32) Shorter Pt-Ag distances have been found in a large number
of complexes containing Pt-Ag bonds. See for example: Uso´n, R.;
Fornie´s, J .; Toma´s, M.; Casas, J . M.; Cotton, F. A.; Falvello, L. R. J .
Am. Chem. Soc. 1985, 107, 2556-2557.
(33) Bock, H.; Dammel, R. Angew. Chem., Int. Ed. Engl. 1987, 26,
504.
(34) Bock, H.; Dammel, R. J . Am. Chem. Soc. 1988, 110, 5261.
(35) Sandler, S. R.; Caro, W. Organic Functional Groups Prepara-
tions; Academic Press: New York, 1971.
(36) The Chemistry of the CdN Double Bond; Interscience: London,
1970.
(37) Gainsford, A. R.; Pizer, R. D.; Sargeson, A. M.; Whimp, P. O.
J . Am. Chem. Soc. 1981, 103, 792.
(26) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,
A. G.; Taylor, R. J . Chem. Soc., Perkin Trans. 1987, S1.
(27) Vicente, J .; Chicote, M. T.; Guerrero, R.; Ram´ırez de Arellano,
M. C. Chem. Commun. 1999, 1541-1542.
(38) Golding, B. T.; Harrowfield, J . M. B.; Sargeson, A. M. J . Am.
Chem. Soc. 1974, 96, 3003.
(39) Harrowfield, J . M. B.; Sargeson, A. M. J . Am. Chem. Soc. 1979,
101, 1514.

Notes
Organometallics, Vol. 21, No. 21, 2002 4563
prepared by reaction of NH3 with ketones21 in a pathway
which also requires CdN bond formation. Some other
acetone imine gold complexes have been obtained from
this compound.27,40
The stabilization reaction of the acetone imine de-
scribed in this paper is highly selective. The Ag2CO3
and [NBu4][Pt(C6F5)3(Haza)] salts are both necessary.
Ag2CO3 does not react appreciably with the acetone/
ammonia solution under the described conditions in the
absence of the platinum complexes (see Experimental
Section), and the platinum complexes remain unreacted
and can be recovered from the acetone/ammonia solu-
tion if the silver salt is not present.
-117.98 (1F), -118.62 (1F), -119.65 (2F); m-F and p-F,
-164.67 (6F), -166.58 (3F).
Syn t h esis of [NBu 4][(C6F 5)3P t (µ-a za )Ag(H NdCMe2)]
(2). To a solution of 0.200 g (0.189 mmol) of 1 in 30 mL of
acetone was added 0.052 g (0.095 mmol) of Ag2CO3 (2:1 molar
ratio), and then 1 mL of a aqueous solution of ammonia (7.6
M) was added dropwise to this suspension, producing immedi-
ate dissolution of the Ag2CO3. After 2 h of stirring in the
absence of light the colorless solution was evaporated to
dryness. The addition of 20 mL of n-hexane rendered a white
solid (2), which was filtered off. Yield: 73%. Anal. Found
(calcd): C, 42.93 (43.29); H, 4.06 (3.96); N, 4.46 (4.58). IR
(Nujol; cm-1): C6F5, X-sensitive mode,43 805 m, 785 w, 766 m;
others, 1605 m, 1496 vs, 1053 s, 951 s; aza: 1594 m, 793 m;
HNdC(CH3)2, ν(CdN) 1667 m, ν(N-H) 3334 m; other 476 m;
NBu4, 883 m. 1H NMR (CDCl3, room temperature): δ aza, 8.51
(d, 1H), 7.69 (d, 1H), 7.33 (m, 1H), 6.54 (dd, 1H), 6.32 (m, 1H);
HNdC(CH3)2: 8.98 (s, 1H, NH), 2.20 (s, 3H, CH3), 2.32 (s, 3H,
CH3); NBu4, 0.89 (t, 12H, -CH3), 1.26 (sext., 8H, R-CH2), 1.44
(m, 8H, â-CH2), 2.87 (m, 8H, γ-CH2). 19F NMR (CDCl3, room
temperature): δ -116.88 (m, o-F, 4F), -117.44 (m, o-F, 2F);
-166.3 (m, m-F + p-F, 6F); -167.6 (t, p-F, 1F); -168.1 (m,
m-F, 2F).
To check the generality of the formation and stabili-
zation of the acetone imine, we have also carried out
reactions between complex 1 and NiCO3 or CuCO3
under similar conditions (acetone/ammonia solution)
without success.
Exp er im en ta l Section
Rea ction betw een Ag2CO3 a n d Aqu eou s Am m on ia in
Aceton e. To a suspension of 0.150 g (0.270 mmol) of Ag2CO3
in 30 mL of acetone was added 1 mL of aqueous solution of
ammonia (7.6 M) dropwise. After 2 h of stirring in the absence
of light the remaining suspension was filtered off and 0.132 g
of unreacted Ag2CO3 was recovered (88% of the starting
material).
Gen er a l Meth od s. C, H, and N analyses were carried out
with a Perkin-Elmer 240B microanalyzer. The IR spectra were
recorded over the range 4000-200 cm-1 on a Perkin-Elmer
883 spectrophotometer using Nujol mulls between polyethyl-
ene sheets. The 1H, 13C, and 19F NMR spectra were recorded
on a Varian XL-200 or a Unity-300 instrument in CDCl3 or
acetone-d6 solutions. All reactions in which silver salts are
involved were carried out with exclusion of light. 7-Azaindole
was used as received from Aldrich. [NBu4]2[Pt(C6F5)3Cl]41 and
Cr ysta l Str u ctu r e An a lysis for [NBu 4][(C6F 5)3P t(µ-
a za )Ag(HNdCMe2)] (2). Crystal data and other details of the
structure analysis are presented in Table 1. Suitable crystals
of 2 were obtained by slow diffusion of n-pentane into a
solution of complex 2 in CH2Cl2 (3 mL) at -30 °C, and one of
them was mounted at the end of a glass fiber. The unit cell
dimensions were determined from 60 centered reflections in
the range 21.5 < 2θ < 29.7°. An absorption correction was
applied based on 360 azimuthal scan data. Lorentz and
polarization corrections were applied for both structures.
The structure was solved by Patterson and Fourier methods.
All refinements were carried out using the SHELXL-93
program.44 All non-hydrogen atoms were assigned anisotropic
displacement parameters and refined without positional con-
straints. For complex 2, all hydrogen atoms were constrained
to idealized geometries and assigned a common isotropic
displacement parameter of 0.1058. Full-matrix least-squares
refinement of these models against F2 converged to the final
residual indices given in Table 1. Final difference electron
density maps showed seven features above 1 e/Å3 (maximum/
minimum +2.86/-1.81 e/Å3), being closer than 1 Å to the
platinum atom.
42
Ag2CO3 were prepared as described elsewhere.
Sa fety Note. Perchlorate salts are potentially explosive.
Only small amounts of material should be prepared, and these
should be handled with great caution.
Syn th esis of [NBu 4][P t(C6F 5)3(HN2C7H5)] (1). To a solu-
tion of 1.000 g (0.822 mmol) of [NBu4]2[Pt(C6F5)3Cl] in 25 mL
of thf was added 0.170 g (0.822 mmol) of AgClO4. The solution,
protected from the light, was stirred at room temperature for
30 min. The AgCl was separated by filtration, and the solution
was evaporated to dryness. The residue was dissolved in 30
mL of CH2Cl2, and 0.097 g (0.822 mmol) of 7-azaindole was
added to the resulting solution. After 1 h of stirring the
solution was evaporated to dryness and the residue was
treated with 20 mL of iPrOH, yielding a white solid (1) which
was filtered off and washed with n-hexane. Yield: 76%. Anal.
Found (calcd): C, 46.52 (46.59); H, 4.18 (4.00); N, 4.31 (3.97).
IR (Nujol; cm-1): C6F5, X-sensitive mode,43 800 m, 788 m, 773
m; other, 1633 m, 1607 m, 1496 vs, 1055 s, 954 s; Haza (N-
H), 3433 m; other, 1667 m, 804 m, 522 m, 476 m, 447 w; NBu4,
883 m. 1H NMR (CDCl3, room temperature): δ Haza, 10.11
(s,1H), 8.46 (d, 1H, J Pt-H ) 28 Hz), 7.78 (d, 1H), 7.33 (t, 1H),
6.86 (dd, 1H), 6.43 (t, 1H); NBu4, 0.95 (t, 12H, -CH3), 1.38
(sext, 8H, R-CH2), 1.61 (m, 8H, â-CH2), 3.12 (m, 8H, γ-CH2).
19F NMR (CDCl3, room temperature): δ o-F, -116.95 (d, 2F,
J Pt-o-F ) 527 Hz), -117.85 (d, 4F, J Pt-o-F ) 357 Hz); m-F,
-164.83 (m, 4F), -165.03 (m, 2F); p-F, -164.98 (t, 1F),
Ack n ow led gm en t. We thank the Spanish Comisio´n
Interministerial de Ciencia y Tecnolog´ıa (CICYT) for its
financial support (Project PB98-1595-C02-01) and for a
grant to A.J .R.
Su p p or tin g In for m a tion Ava ila ble: Tables of all atomic
positional and equivalent isotropic displacement parameters,
anisotropic displacement parameters, bond distances and bond
angles, hydrogen coordinates, and anisotropic displacement
parameters for the crystal structure of complex 2. This
material is available free of charge via the Internet at
http://pubs.acs.org.
1
-166.79 (t, 2F). H NMR (CD2Cl2, -90 °C): δ Haza, 9.94 (d,
1H), 8.42 (d 1H), 7.86 (t, 1H), 7.36 (d, 1H), 6.92 (m, 1H), 6.48
(d, 1H). 19F NMR (CD2Cl2, -90 °C): δ o-F, -117.40 (2F),
(40) Vicente, J .; Chicote, M. T.; Guerrero, R.; Saura-Llamas, I. M.;
J ones, P. G.; Ram´ırez de Arellano, M. C. Chem. Eur. J . 2001, 7, 638-
646.
(41) Uso´n, R.; Fornie´s, J .; Toma´s, M.; Fandos, R. J . Organomet.
Chem. 1984, 263, 253.
OM020197Z
(42) Poyer, L.; Fielder, M.; Harrison, H.; Bryant, B. E. Inorganic
Syntheses; Moeller, T., Ed.;, McGraw-Hill: New York, 1957; Vol. 19.
(43) Uso´n, R.; Fornie´s, J . Adv. Organomet. Chem. 1988, 28, 188.
(44) Sheldrick, G. M. SHELXL 93; University of Go¨ttingen, Go¨ttin-
gen, Germany, 1993.