Palladium phosphino-iminolate complexes as metalloligands for coinage metals: A versatile, ambivalent behavior

Article abstract of DOI:10.1021/om050156d

Reactivity studies with the bis-chelated Pd(II) phosphino-iminolate complex [Pd(dmba)-(k²-P,O-PPh₂N-C(-O)Me)] (2) (dmba = orthometalated dimethylbenzylamine) have shown that it readily reacts as a metalloligand with electrophilic complexes of the coinage metals, selectively via the nitrogen atom of the P,O chelate. After examining its reaction with AgOTf (OTf = SO₃CF₃), which afforded the first 1-D coordination polymer containing Ag-Pd bonds, [{Ag(2)}OTf]_n (3·OTf), we have examined and compared its reactions with H⁺, Au(PPh₃)⁺, [AuCl(THT)], [Au(THT)]BF₄, and [Cu(NCMe)₄]BF₄. Depending on the nature of the electrophilic metal reagent used, the interaction between the iminolate N atom of 2 and the electrophile can be formally described as a dative bond involving its lone pair, which would formally place the positive charge of the complex more on the coinage metal, or as a more covalent interaction resulting in an increased carbon-oxygen bond order and thus in the pos-/baitive charge being more localized on the Pd(II) center. In the former case, the metalloligand formally behaves as a two-electron, L-type donor, whereas in the latter, as a one-electron, X-type donor ligand. This ambivalent behavior explains the formation of the heterobimetallic complexes [{Pd(dmba)(k ²-P,O-PPh₂NC(O)Me)}AuCl] (6) and [{Pd(dmba)(k ²-P,O-PPh₂NC(O)Me)}Au(PPh₃)]OTf ([Au(PPh ₃)(2)]OTf) or [{Pd(dmba)(k²-P,O-PPh ₂NC(O)Me)}Au(THT)BF₄ (7·BF₄), respectively. Double substitution of the d¹⁰ metal center by 2 afforded the Pd/Au/Pd and Pd/Cu/Pd heterotrinuclear complexes [{Pd(dmba)(k ²-P,O-PPh₂NC(O)Me)}₂Au]BF₄ (8·BF₄) and [{Pd(dmba)(k²-P,O-PPh ₂NC(O)Me)}₂Cu]BF₄ (9·BF₄), respectively. The complexes 2, 5·OTf, 6, 7·BF₄, 8·BF₄·2CH₂Cl₂, and 9·BF₄ have been structurally characterized by X-ray diffraction.

Full text of DOI:10.1021/om050156d

Organometallics 2005, 24, 3149-3157
3149
Palladium Phosphino-Iminolate Complexes as
Metalloligands for Coinage Metals: A Versatile,
Ambivalent Behavior‡
Nicola Oberbeckmann-Winter,† Pierre Braunstein,*,† and Richard Welter§
Laboratoire de Chimie de Coordination and Laboratoire DECMET, UMR 7513 CNRS,
Universite´ Louis Pasteur, 4 Rue Blaise Pascal, F-67070 Strasbourg Ce´dex, France
Received March 4, 2005
Reactivity studies with the bis-chelated Pd(II) phosphino-iminolate complex [Pd(dmba)-
(κ2-P,O-PPh2N-C(-O)Me)] (2) (dmba ) orthometalated dimethylbenzylamine) have shown
that it readily reacts as a metalloligand with electrophilic complexes of the coinage metals,
selectively via the nitrogen atom of the P,O chelate. After examining its reaction with AgOTf
(OTf ) SO3CF3), which afforded the first 1-D coordination polymer containing Ag-Pd bonds,
[{Ag(2)}OTf]n (3‚OTf), we have examined and compared its reactions with H+, Au(PPh3)+,
[AuCl(THT)], [Au(THT)]BF4, and [Cu(NCMe)4]BF4. Depending on the nature of the electro-
philic metal reagent used, the interaction between the iminolate N atom of 2 and the
electrophile can be formally described as a dative bond involving its lone pair, which would
formally place the positive charge of the complex more on the coinage metal, or as a more co-
valent interaction resulting in an increased carbon-oxygen bond order and thus in the pos-
/baitive charge being more localized on the Pd(II) center. In the former case, the metalloligand
formally behaves as a two-electron, L-type donor, whereas in the latter, as a one-electron,
X-type donor ligand. This ambivalent behavior explains the formation of the heterobimetallic
complexes [{Pd(dmba)(κ2-P,O-PPh2NC(O)Me)}AuCl] (6) and [{Pd(dmba)(κ2-P,O-PPh2NC(O)-
Me)}Au(PPh3)]OTf ([Au(PPh3)(2)]OTf) or [{Pd(dmba)(κ2-P,O-PPh2NC(O)Me)}Au(THT)BF4
(7‚BF4), respectively. Double substitution of the d10 metal center by 2 afforded the Pd/Au/
Pd and Pd/Cu/Pd heterotrinuclear complexes [{Pd(dmba)(κ2-P,O-PPh2NC(O)Me)}2Au]BF4
(8‚BF4) and [{Pd(dmba)(κ2-P,O-PPh2NC(O)Me)}2Cu]BF4 (9‚BF4), respectively. The complexes
2, 5‚OTf, 6, 7‚BF4, 8‚BF4‚2CH2Cl2, and 9‚BF4 have been structurally characterized by X-ray
diffraction.
Introduction
Some transition metal complexes can behave as met-
alloligands and are increasingly used as well-defined
building blocks for the stepwise construction of poly-
nuclear complexes. This approach is particularly inter-
esting in heterometallic chemistry, where it allows a more
rational structural design based on the predictable be-
havior of the components. However, selective and high-
yield syntheses require a good understanding of the re-
activity of these building units toward a range of metal
reagents. We have recently found that air-stable Pd(II)
phosphino-iminolate complexes of type 1 readily react
with electrophilic metal complexes to form heterodi- or
polynuclear complexes upon chemoselective metal co-
ordination at the sp2-hybridized nitrogen atom of the
P,O-chelate.1
geometry at the nitrogen. The reaction of the palladium
phosphino-iminolate complex [Pd(dmba)(κ2-P,O-PPh2-
N-C(-O)Me)] (2) (dmba ) orthometalated dimethyl-
benzylamine) with AgOTf (OTf ) SO3CF3) afforded the
first 1-D coordination/organometallic polymer contain-
ing Ag-Pd bonds [{Ag(2)}OTf]n (3‚OTf), which opens
an unprecedented access to ordered structures with
alternating metals based on heterodimetallic units.1
This results in new (µ-P,N)-bridged heterometallic
complexes, with retention of the planar coordination
‡ Dedicated to Prof. Dr. H. Schmidbaur in recognition of his brilliant
career and major contributions to chemistry.
* To whom correspondence should be addressed. E-mail: braunst@
chimie.u-strasbg.fr. Fax: (+33)3-9024-1322.
† Laboratoire de Chimie de Coordination (UMR 7513 CNRS).
§ Laboratoire DECMET (UMR 7513 CNRS).
(1) Braunstein, P.; Frison, C.; Oberbeckmann-Winter, N.; Morise,
X.; Messaoudi, A.; Be´nard, M.; Rohmer, M.-M.; Welter, R. Angew.
Chem., Int. Ed. 2004, 43, 6120.
We therefore became interested in exploring further
the reactivity of complexes of type 1 toward electrophilic
10.1021/om050156d CCC: $30.25 © 2005 American Chemical Society
Publication on Web 05/14/2005

3150 Organometallics, Vol. 24, No. 13, 2005
Oberbeckmann-Winter et al.
Scheme 1. Improved, One-Pot Syntheses of 2 and
5·OTf
Figure 1. ORTEP view of the structure of [Pd(dmba)(κ2-
P,O-PPh2N-C(-O)Me)] (2) with the atom-numbering
scheme. Only the ipso aryl carbon atoms on P are shown
for clarity. Thermal ellipsoids enclose 50% of the electron
density. Selected bond distances (Å) and angles (deg): Pd-
C(1) 1.998(4), Pd-O 2.106(3), Pd-N(1) 2.134(4), Pd-P
2.219(1), P-N(2) 1.685(4), N(2)-C(10) 1.299(6), C(10)-
C(11) 1.514(6), C(10)-O 1.293(5); C(1)-Pd-O 176.2(2),
C(1)-Pd-N(1) 82.6(2), O-Pd-N(1) 93.6(1), C(1)-Pd-P
103.1(1), O-Pd-P 80.67(9), N(1)-Pd-P 173.1(1), Pd-P-
N(2) 103.6(2), N(2)-C(10)-O 126.9(4), C(10)-O-Pd 114.9-
(3).
complexes of the coinage metals. Whereas protonation
of 1 quantitatively leads to a cationic phosphine complex
of type 4 containing formally a CdO double bond and a
dative interaction between this oxygen donor and the
metal, the situation is less straightforward with metal
complexes, even with those that are isolobal with the
proton.1
Thus, an interesting question arises about the formal
description of the interaction between the iminolate N
atom of 1 and a metal cation: is it formally going to be
a dative bond involving its lone pair, as in a type A
structure, or a more covalent interaction, as in B,
resulting in an increased carbon-oxygen bond order and
in the positive charge of the complex being more
localized on the Pd(II) center than on the coinage metal?
Intermediate situations between these limiting forms
are also conceivable.
Figure 2. ORTEP view of the structure of [Pd(dmba)(κ2-
P,O-PPh2NHC(O)Me)]+ in 5‚OTf with the atom-numbering
scheme. Only the ipso aryl carbon atoms on P are shown
for clarity. Thermal ellipsoids enclose 50% of the electron
density. Selected bond distances (Å) and angles (deg): Pd-
C(1) 1.990(2), Pd-O(1) 2.142(2), Pd-N(1) 2.130(2), Pd-P
2.2164(6), P-N(2) 1.699(2), N(2)-C(10) 1.347(3), C(10)-
O(1) 1.251(3), C(10)-C(11) 1.485(4); C(1)-Pd-N(1) 82.09-
(9), C(1)-Pd-O(1) 179.07(7), N(1)-Pd-O(1) 97.12(7), C(1)-
Pd-P 98.42(7), N(1)-Pd-P 176.45(6), O(1)-Pd-P 82.40(5),
Pd-P-N(2) 99.47(8), N(2)-C(10)-C(11) 117.6(2), N(2)-
C(10)-O(1) 120.8(2), C(10)-O(1)-Pd 116.9(2).
The crystal structure of this complex has been deter-
mined and compared with that of the corresponding
protonatedcomplex[Pd(dmba)(κ2-P,O-PPh2NHC(O)Me)]-
OTf (5‚OTf), whose original synthesis2 has also been
improved (see Scheme 1 and Experimental Section)
(Figures 1 and 2, Table 1). The structure of the latter
is very similar to that of [Pd(dmba)(κ2-P,O-PPh2NHC-
(O)Me)]BF4 (5‚BF4).3 Hydrogen bonding was found
between the NH function and either a fluorine atom
(BF4) or a oxygen atom (OTf) of the counterion, but in
contrast to the disordered BF4 anion which develops
In the present study, we have used as metalloligand
of type 1 the complex [Pd(dmba)(κ2-P,O-PPh2N-C(-O)-
Me)] (2)1 and explored its reactivity toward Au(I) and
Cu(I) electrophiles, which led to new P,N-bridged het-
erometallic complexes.
Results and Discussion
Since [Pd(dmba)(κ2-P,O-PPh2N-C(-O)Me)] (2)1 was
the main precursor complex for the present studies, an
improved, one-step synthesis was desirable (Scheme 1),
which is detailed in the Experimental Section.
(2) Braunstein, P.; Frison, C.; Morise, X.; Adams, R. D. J. Chem.
Soc., Dalton Trans. 2000, 2205.
(3) Morise, X.; Braunstein, P.; Welter, R. Inorg. Chem. 2003, 42,
7752.

Palladium Phosphino-Iminolate Complexes
Organometallics, Vol. 24, No. 13, 2005 3151
Table 1. Comparison of Bond Lengths and IR Vibration Frequencies between Related Iminolato
Complexes
Pd-O
C-O
C-N
P-N
ν(NC+CO)
2
2.106(3)
2.142(2)
1.293(5)
1.251(3)
1.299(6)
1.347(3)
1.685(4)
1.699(2)
1501sa
5+
1604sa
[AuCl(2)] (6)
2.118(4)
1.265(6)
1.347(6)
1.701(4)
1506sb
1509sb
1517sa
1508sb
[Au(THT)(2)]BF4 (7‚BF4)
2.108(5)
1.236(9)
1.342(9)
1.704(6)
[Au(PPh3)(2)]+c
[Au(2)2]BF4 (8‚BF4)
2.121(5)
2.136(4)/2.134(4)
1.273(9)
1.250(6)/1.255(6)
1.353(9)
1.344(7)/1.328(7)
1.700(6)
1.708(5)/1.709(5)
[Cu(2)2]BF4 (9‚BF4)
2.124(3)/2.113(3)
1.261(5)/1.264(5)
1.333(6)/1.336(6)
1.712(4)/1.716(4)
1492sb
[{Ag(2)}OTf]n (3‚OTf)c
2.103(3)
2.102(4)/2.110(4)
1.286(5)
1.260(7)/1.276(7)
1.342(6)
1.318 (7)/1.337(7)
1.701(4)
1.690(5)/1.706(5)
1496sa
[Ag(2)2]OTfc
1494sb
a Recorded in CH2Cl2. b Recorded as KBr disk. c From ref 1.
three NH‚‚‚F interactions (av 2.88 Å), the OTf anion was
not disordered and only one NH‚‚‚O interaction is
present (2.78(1) Å, N-H-O ) 177.4(3)°). In both cases,
the Pd,P,N,C,O chelate ring is almost planar (maximum
deviation out of this plane of 0.033(2) Å for N(2) in 2
and of 0.026(1) Å for O(1) in 5‚OTf, respectively). The
nitrogen atom N(2) in 5‚OTf has a planar coordination
environment (sum of the three bond angles of 359.0-
(2)°). It is interesting to compare the degree of electronic
delocalization within the five-membered P,O chelate
rings. A delocalized π-system is present in 2, as deduced
from the values for the N(2)-C(10) and C(10)-O bond
distances of 1.299(6) and 1.293(5) Å, respectively, which
contrasts with the more localized bonding situation in
5‚OTf, for which the corresponding values are 1.347(3)
and 1.251(3) Å, respectively (Table 1), and clearly
indicates a pronounced CdO double bond character,
consistent with the IR data (see below). In both com-
plexes, the P-N(2) distances are similar and in the
normal range for single bonds, suggesting that the P
atom in 2 is not significantly involved in the electronic
delocalization. This is also consistent with the similarity
of the 31P{1H} NMR chemical shift, 81.9 and 80.4 ppm
in CDCl3 for 2 and 5‚OTf, respectively. We have found
previously that coordination of a metal center, such as
Ag+ or Au(PPh3)+, to the iminolate nitrogen N(2) of 2
to give 3‚OTf and [Au(PPh3)(2)]OTf, respectively, results
in a partial relocalization of the electronic system,1
which emphasizes the similarities between these cat-
ionic metal fragments and H+, although significant
differences are observed in the IR spectra of the
complexes in the ν(NC+CO) region (see Table 1).
Whereas the IR absorption of 5‚OTf at 1604 cm-1
corresponds to the ν(CdO) vibration of a coordinated
ketone, the values found around 1500-1520 cm-1 for
the di- or trinuclear complexes are much more similar
to that of 1501 cm-1 assigned to ν(N-C+C-O), char-
acteristic of the delocalized system in 2. This apparent
contradiction has already been noted before in the case
of the metalation of phophino-enolate Pd(II) complexes
and was suggested to be due to the mass and/or
electronic effect of the heavy d10 metal compared to the
proton.4,5 The bond distances and angles within the Pd-
(dmba) moiety are similar to those found in the litera-
ture.3,6
contains the labile THT (tetrahydrothiophene) ligand.
As anticipated, the palladium complex 2 substituted the
THT ligand and the only product formed, [{Pd(dmba)-
(κ2-P,O-PPh2NC(O)Me)}AuCl] (6), was isolated in good
yield. This new complex is stable for a few days when
kept in CDCl3 at room temperature under exclusion of
light; it neither decomposes nor rearranges. The solid-
state structure determination by X-ray diffraction (Fig-
ure 3a, Table 1) established the formation of a Au-N
bond. Its length of 2.035(4) Å is slightly shorter than in
the related cationic complex [Au(PPh3)(2)]OTf (2.085-
(6) Å).1 Formally, complex 2 has behaved as a neutral,
2e donor ligand (L-type) toward the Au(I) center which
retains its usual 14e electronic configuration. Bond
distances in this heterodimetallic complex are further
discussed below. In the solid state, the molecules are
arranged in centrosymmetrical pairs (Figure 3b), which
leads to a better packing and to an intermolecular Au-
Au separation of 3.88(1) Å, which may provide ad-
ditional stabilization, although typical d10-d10 auro-
philic interactions generally correspond to Au-Au
distances of 3.00 ( 0.25 Å.7
When [Au(THT)2]OTf, prepared in situ, was used as
a precursor with the hope that a Au/Pd coordination
polymer could form by analogy with 3‚OTf, the complex
[{Pd(dmba)(κ2-P,O-PPh2NC(O)Me)}Au(THT)]OTf (7‚
OTf) was obtained instead (Scheme 2). It was purified
by recrystallization, although it shows only limited
stability in solution and at room temperature. The
following alternative procedures yielded 7‚X (X ) OTf,
BF4) but with larger amounts of byproducts: (i) addition
of a CH2Cl2 solution of [Au(THT)]BF4 to 2 in CH2Cl2,
(ii) addition of the coordination polymer [{Ag(2)}OTf]n
in THF to a solution of [AuCl(THT)] in THF, and (iii)
mixing of 6, AgOTf, and THT in CH2Cl2. The most
abundant byproduct, [{Pd(dmba)(κ2-P,O-PPh2NC(O)-
Me)}2Au]X (8‚X) (Scheme 3), resulted from a double
(4) Andrieu, J.; Braunstein, P.; Drillon, M.; Dusausoy, Y.; Ingold,
F.; Rabu, P.; Tiripicchio, A.; Ugozzoli, F. Inorg. Chem. 1996, 35, 5986.
(5) Veya, P.; Floriani, C.; Chiesi-Villa, A.; Guastini, C.; Dedieu, A.;
Ingold, F.; Braunstein, P. Organometallics 1993, 12, 4359.
(6) Apfelbacher, A.; Braunstein, P.; Brissieux, L. Welter, R. Dalton
Trans. 2003, 1669, and references therein.
(7) Pyykko¨, P. Angew. Chem., Int. Ed. 2004, 43, 4412, and references
therein.
To examine whether complex 2 prefers to coordinate
to a metal center formally as a donor (L-type) or a
covalent (X-type) metalloligand, a helpful textbook
formalism that facilitates bookkeeping of electrons
around the metals, it was reacted in a mixture of
toluene/CH2Cl2 with 1 equiv of [AuCl(THT)], which
(8) Ahrens, B.; Jones, P. G. Z. Naturforsch., B: Chem. Sci. 2000,
55, 803.
(9) Vicente, J.; Chicote, M. T.; Guerrero, R.; Ramirez de Arellano,
M. C. Chem. Commun. 1999, 1541.
(10) Lock, C. J. L.; Wang, Z. Acta Crystallogr., Sect. C: Cryst. Struct.
Commun. 1993, 49, 1330.

3152 Organometallics, Vol. 24, No. 13, 2005
Oberbeckmann-Winter et al.
Scheme 3. Synthesis of Trinuclear Pd/M/Pd
Complexes
reaction mixture. The reduced stability of 7‚OTf com-
pared to that of [Au(PPh3)(2)]OTf1 probably results from
the presence of the weaker and more loosely bound THT
ligand compared to PPh3. However, the fact that the
THT donor remained coordinated to Au prevented the
formation of a coordination polymer analogous to that
characterized in the Pd-Ag system 3‚OTf.1 The molec-
ular structure of 7‚BF4 was determined by single-crystal
X-ray diffraction. Its Au-N and Au-S bond lengths,
2.052(6) and 2.253(3) Å, respectively, are very similar
to those in a related Au(THT) complex, where a dime-
sylamido ligand is bonded to Au (av Au-N distance:
2.06 Å, av Au-S distance: 2.26 Å).8 The metalloligand
2 behaves formally as an X-type ligand in 7+, and the
length of the Au-N bond is intermediate between those
in 6 and in [Au(PPh3)(2)]OTf, where the N-Au interac-
tion is formally dative and covalent, respectively. We
come back to this point below.
Figure 3. (a) ORTEP view of the structure of [{Pd(dmba)-
(κ2-P,O-PPh2NC(O)Me)}AuCl] (6) with the atom-numbering
scheme. Only the ipso aryl carbon atoms on P are shown
for clarity. Thermal ellipsoids enclose 50% of the electron
density. Selected bond distances (Å) and angles (deg): Au-
N(2) 2.035(4), Au-Cl 2.256(2), Pd-C(1) 2.001(5), Pd-O
2.118(4), Pd-N(1) 2.124(4), Pd-P 2.204(1), P-N(2) 1.701-
(4), N(2)-C(10) 1.347(6), C(10)-C(11) 1.497(7), C(10)-O
1.265(6); N(2)-Au-Cl 178.3(1), C(1)-Pd-O 176.9(2), C(1)-
Pd-N(1) 82.8(2), O-Pd-N(1) 95.1(2), C(1)-Pd-P 101.2(2),
O-Pd-P 81.0(1), N(1)-Pd-P 176.1(1), P-Pd-N(2) 102.5-
(2), Au-N(2)-C(10) 124.8(3), P-N(2)-Au 119.8(2), P-N(2)-
C(10) 115.4(3), N(2)-C(10)-C(11) 118.3(4), N(2)-C(10)-O
123.1(5), C(11)-C(10)-O 118.6(4), C(10)-O-Pd 116.8(3).
(b) ORTEP view of the pairwise arrangement of the
Compound 8‚BF4, which was one of the byproducts
formed during the synthesis of 7‚BF4, was obtained
directly from [Au(THT)]BF4 and 2 equiv of 2 by analogy
with the synthesis of [Ag(2)2]OTf.1 The X-ray structure
analysis revealed nearly identical bond distances within
the two Pd moieties (Figure 5, Table 1). The molecular
molecules of [{Pd(dmba)(κ2-P,O-PPh2NC(O)Me)}AuCl] (6)
in the solid state. Au-Au ) 3.88(1) Å.
Scheme 2. Behavior of 2 as an L- or X-Type
Metalloligand
Figure 4. ORTEP view of the structure of [{Pd(dmba)-
(κ2-P,O-PPh2NC(O)Me)}Au(THT)]+ in 7‚BF4 with the atom-
numbering scheme. Only the ipso aryl carbon atoms on P
are shown for clarity. Thermal ellipsoids enclose 50% of
the electron density. Selected bond distances (Å) and angles
(deg): Au-N(2) 2.052(6), Au-S 2.253(3), S-C(24) 1.77(1),
S-C(27) 1.83(1), Pd-C(1) 2.011(8), Pd-O 2.108(5), Pd-
N(1) 2.120(7), Pd-P 2.211(2), P-N(2) 1.704(6), N(2)-C(10)
1.342(9), C(10)-O 1.236(9); N(2)-Au-S 174.5(2), C(1)-
Pd-O 176.7(3), C(1)-Pd-N(1) 82.4(3), O-Pd-N(1) 94.3-
(2), C(1)-Pd-P 101.5(2), O-Pd-P 81.8(2), N(1)-Pd-P
175.7(2), Pd-P-N(2) 101.4(2), P-N(2)-Au 119.0(3), Au-
N(2)-C(10) 125.4(5), N(2)-C(10)-C(11) 117.4(7), N(2)-
C(10)-O 125.0(7), C(10)-O-Pd 116.4(5).
substitution at the gold center by 2, and its direct
synthesis will be discussed below. Another byproduct
often observed was 5+, whose direct formation from 2
is explained by the presence of traces of acid in the

Palladium Phosphino-Iminolate Complexes
Organometallics, Vol. 24, No. 13, 2005 3153
Figure 5. ORTEP view of the structure of [{Pd(dmba)-
(κ2-P,O-PPh2NC(O)Me)}Au]+ in 8‚BF4‚2CH2Cl2 with the
atom-numbering scheme. Only the ipso aryl carbon atoms
on P are shown for clarity. Thermal ellipsoids enclose 50%
of the electron density. Selected bond distances (Å) and
angles (deg): Au-N(2) 2.033(4), Au-N(4) 2.034(4), Pd(1)-
C(1) 1.995(6), Pd(1)-O(1) 2.136(4), Pd(1)-N(1) 2.138(5), Pd-
(1)-P(1) 2.204(2), P(1)-N(2) 1.708(5), N(2)-C(10) 1.344(7),
C(10)-O(1) 1.250(6), Pd(2)-C(24) 1.995(5), Pd(2)-N(3)
2.131(5), Pd(2)-O(2) 2.134(4), Pd(2)-P(2) 2.206(2), P(2)-
N(4) 1.709(5), N(4)-C(33) 1.328(7), C(33)-O(2) 1.255(6);
N(2)-Au-N(4) 178.2(2), C(1)-Pd(1)-O(1) 178.7(2), C(1)-
Pd(1)-N(1) 82.1(2), O(1)-Pd(1)-N(1) 98.1(2), C(1)-Pd(1)-
P(1) 98.8(2), O(1)-Pd(1)-P(1) 81.1(1), N(1)-Pd(1)-P(1)
177.0(2), Pd(1)-P(1)-N(2) 102.7(2), P(1)-N(2)-Au 116.5-
(2), Au-N(2)-C(10) 128.2(4), N(2)-C(10)-C(11) 117.5(5),
N(2)-C(10)-O(1) 124.1(5), C(10)-O(1)-Pd(1) 116.8(4),
C(24)-Pd(2)-O(2) 177.7(2), C(24)-Pd(2)-N(3) 82.2(2),
O(2)-Pd(2)-N(3) 98.2(2), C(24)-Pd(2)-P(2) 99.3(2), O(2)-
Pd(2)-P(2) 80.5(1), N(3)-Pd(2)-P(2) 176.8(2), Pd(2)-P(2)-
N(4) 102.6(2), P(2)-N(4)-Au 115.8(2), Au-N(4)-C(33)
128.5(4), N(4)-C(33)-C(34) 117.6(5), N(4)-C(33)-O(2)
123.4(5), C(33)-O(2)-Pd(2) 117.2(4).
Figure 6. ORTEP view of the structure of [{Pd(dmba)-
(κ2-P,O-PPh2NC(O)Me)}2Cu]+ in 9‚BF4 with the atom-
numbering scheme. Only the ipso aryl carbon atoms on P
are shown for clarity. Thermal ellipsoids enclose 50% of
the electron density. Selected bond distances (Å) and angles
(deg): Cu-N(2) 1.873(3), Cu-N(4) 1.877(4), Pd(1)-C(1)
1.993(5), Pd(1)-O(1) 2.124(3), Pd(1)-N(1) 2.130(4), Pd(1)-
P(1) 2.203(2), P(1)-N(2) 1.712(4), N(2)-C(10) 1.333(6),
C(10)-O(1) 1.261(5), Pd(2)-C(24) 1.997(5), Pd(2)-O(2)
2.113(3), Pd(2)-N(3) 2.134(4), Pd(2)-P(2) 2.218(1), P(2)-
N(4) 1.716(4), N(4)-C(33) 1.336(6), C(33)-O(2) 1.264(5);
N(2)-Cu-N(4) 178.0(2), C(1)-Pd(1)-O(1) 176.1(2), C(1)-
Pd(1)-N(1) 82.8(2), O(1)-Pd(1)-N(1) 95.8(1), C(1)-Pd(1)-
P(1) 100.7(2), O(1)-Pd(1)-P(1) 80.98(9), N(1)-Pd(1)-P(1)
173.7(1), Pd(1)-P(1)-N(2) 103.0(1), P(1)-N(2)-Cu 117.4-
(2), Cu-N(2)-C(10) 128.0(3), N(2)-C(10)-C(11) 118.4(4),
N(2)-C(10)-O(1) 124.8(4), C(10)-O(1)-Pd(1) 116.5(3),
C(24)-Pd(2)-O(2) 176.9(2), C(24)-Pd(2)-N(3) 82.3(2),
O(2)-Pd(2)-N(3) 94.9(2), C(24)-Pd(2)-P(2) 101.8(2), O(2)-
Pd(2)-P(2) 80.9(1), N(3)-Pd(2)-P(2) 174.0(1), Pd(2)-P(2)-
N(4) 102.1(1), P(2)-N(4)-Cu 120.5(2), Cu-N(4)-C(33)
124.3(3), N(4)-C(33)-C(34) 118.9(4), N(4)-C(33)-O(2)
123.6(4), C(33)-O(2)-Pd(2) 117.4(3).
structure of 8‚BF4 and in particular the Au-N bond
lengths of 2.033(4) and 2.034(4) Å are comparable with
those of complexes in which a gold center is coordinated,
for example, by two pyrimidine moieties (av Au-N
distance: 2.04 Å)9 or two imidazole moieties (av Au-N
distance: 2.01 Å).10
Although attempts to isolate Pd/Tl complexes from the
reactions between 2 and TlPF6 or between 5‚OTf and
TlOEt or TlOAc failed, Cu(I) could be used to form a
linear complex with two metalloligands 2 and the
7‚BF4 are rather surprising since in the former case the
metalloligand 2 behaves as a neutral, 2e donor ligand,
in contrast to the latter case, where a more covalent
Au-N bonding was expected. This could indicate that
in the latter complex a mesomeric structure in which
the positive charge of the complex is formally more
localized on the Au(I) center represents a strong con-
tribution to the bonding (Scheme 2). One could have
expected the Au-N bond lengths in complexes 6, 7‚BF4,
and 8‚BF4 to reflect the bonding situation within the
Pd fragment, whether it behaves more like an L-type
(A) or X-type (B) metalloligand. But surprisingly, there
are no significant differences between the Au-N dis-
tances, of 2.035(4) Å in 6, 2.052(6) Å in 7‚BF4, and 2.033-
(4)/2.034(4) Å, in 8‚BF4. The linear geometry around the
gold center is retained throughout the series 6 (Cl-Au-
N(2) ) 178.3(1)°), 7‚BF4 (S-Au-N(2) ) 174.5(2)°), and
8‚BF4 (N(2)-Au-N(4) ) 178.2(2)°). The π-system within
the phosphino iminolate appears to be rather localized
for these three compounds, with a more pronounced
double-bond character for the CdO than for the C-N
bond: the CdO bond lengths of 1.265(6) Å in 6, 1.236-
(9) Å in 7‚BF4, and 1.250(6)/1.255(6) Å in 8‚BF4 are
similar to that in complex 5‚OTf (1.251(3) Å), and all
C-N bond lengths are nearly identical within the
standard deviation (1.347(3) Å in 5‚OTf, 1.347(6) Å in
6, 1.342(9) Å in 7‚BF4, and 1.344(7)/1.328(7) Å in 8‚BF4).
These values compare very well with those in 9‚BF4,
trinuclear Pd/Cu/Pd complex [{Pd(dmba)(κ2-P,O-PPh2NC-
(O)Me)}2Cu]BF4 (9‚BF4) was obtained in good yield from
the reaction between [Cu(NCMe)4]BF4 and 2 equiv of
2. The reaction between [Cu(NCMe)4]BF4 and only 1
equiv of 2 led to three products: the reprotonated form
5‚BF4, the bis-substituted complex 9‚BF4, and a third
product (10‚BF4) with probably a 1:1 Pd/Cu stoichiom-
etry were detected in the 31P{1H} NMR spectrum, but
further purification remained unsuccessful and only 5‚
BF43 was crystallized. An X-ray analysis was performed
on single crystals of 9‚BF4 and showed a structure
related to those of [Ag(2)2]OTf1 and of the analogous Au
complex 8‚BF4 (Figure 6, Tables 1). The two Pd moieties
in 9‚BF4 have again similar bond distances and the two
Cu-N bond lengths are almost identical at 1.873(3) and
1.877(4) Å. This structure is further discussed below.
A comparison of the main bond distances in complexes
6, 7‚BF4, and [Au(PPh3)(2)]OTf 1 and 8‚BF4 is provided
in Table 1. Whereas the data for 7+ indicate, as
expected, a bonding scheme similar to that in 5+, the
structural and spectroscopic similarities between 6 and

3154 Organometallics, Vol. 24, No. 13, 2005
Oberbeckmann-Winter et al.
which has CdO distances of 1.261(5)/1.264(5) Å and
C-N distances of 1.333(6)/1.336(6) Å (Scheme 3, Table 1).
product. Low-temperature 31P{1H} NMR studies showed
that at 181 K the signal was split into two signals
corresponding to 2 and 5‚OTf. The occurrence of a
dynamic equilibrium between these precursors and the
desired adduct is further supported by the observation
that when the reaction mixture was enriched with one
of the two precursors, the 31P{1H} NMR signal shifted
toward its chemical shift value.
The only significant structural difference between the
three analogous compounds [M(2)2]+, where M is Cu,
Ag, or Au, was found in the dihedral angle formed by
the two Pd,P,N,C,O planes: 79(1)° (M ) Cu), 67(1)° (M
) Ag),1 and 61(1)° (M ) Au). These differences are due
to packing effects since rotations of small amplitude of
the molecular fragments about the N-M-N axis should
be facile both electronically (σ-bond) and sterically. The
average M-N bond distances of 1.875(4) Å for M ) Cu,
2.118(5) Å for M ) Ag, and 2.033(4) Å for M ) Au follow
the same trend as the sums of the covalent radii for N
in a single bond (0.70 Å)11 and the two-coordinated
metals:12 1.13 + 0.70 ) 1.83 Å for Cu-N, 1.33 + 0.70 )
2.03 Å for Ag-N, and 1.25 + 0.70 ) 1.95 Å for Au-N,
respectively. The coordination number of 2 in complexes
8‚BF4 and 9‚BF4 is not unusual for AuI, which appears
in ca. 80% of its complexes in a linear coordination
geometry, whereas CuI is found in only ca. 10% with
this coordination number.13 For comparison, less than
25% of the silver complexes have the metal in a
coordination number of 2.13 Although the coordination
geometry around the metal center in [Ag(2)2]OTf is
almost linear (N(2)-Ag-N(4) ) 175.4(2)), a weak
electrostatic interaction between a triflate oxygen and
Ag+ of 2.82(1) Å was noted.1
Conclusion
We have shown in this work that the palladium phos-
phino-iminolate complex 2 readily behaves as an elemen-
tary building block toward electrophilic coinage metal
complexes to form heterodi- or trinuclear complexes.
This occurs by selective coordination of the metal to the
sp2-hybridized nitrogen atom of the P,O chelate. The na-
ture of the resulting metal-nitrogen bond can be inter-
preted according to two limiting forms, represented by
A and B, respectively. Although the structural param-
eters clearly reflect the higher electronic delocalization
within the N-C-O moiety of 2 compared to 5+, in which
the CdO bond order is higher, no significant differences
were observed in the heterometallic complexes between
the P-N, N-C, or C-O bond distances within the
metalloligand as a function of its behavior as a formal
L- or X-type ligand. This emphasizes the bonding
versatility of this synthon. Related studies with phos-
phino-enolate complexes have shown that soft metal
centers bind to their carbon, as in 11, whereas harder
ions can coordinate to the oxygen donors of the P,O
chelates, as in 12.4
A comparison between the ν(NC+CO) vibration fre-
quencies of 2 and 5‚OTf with those of the complexes in
which 2 behaves as a metalloligand (measured in KBr
for a better resolution, Table 1) reveals no obvious
correlation with the N(2)-C, C-O, and N(2)-M bond
orders. Similar observations have been made previously
in the case of related phosphino-enolate complexes.14
Here we observe that the ν(NC+CO) vibration frequen-
cies are similar in our complexes and comparable to that
of the precursor 2. None of the heterometallic complexes
show a ν(NC+CO) frequency similar to that of com-
pound 5‚OTf.
Considering the isolobal relationship between H+ and
[Au(L)]+, we wondered whether formation of a homodi-
In these cases, the dichotomy encountered in the
present work did not apply since the carbon-metal bond
was formally only of a covalent type.
nuclear complex of the type [{Pd(dmba)(κ2-P,O-PPh2NC-
(O)Me)}2H]OTf with a central N-H-N unit would be
possible since a molecule of 2 could behave as a base
toward a molecule of 5‚OTf. When mixing equimolar
amounts of compounds 2 and 5‚OTf, the 31P{1H} NMR
spectrum in CD2Cl2 showed only one signal at a chemi-
cal shift value average between those of the two
reagents. Upon crystallization from a CH2Cl2 or THF
solution layered with pentane, only the more polar 5‚
OTf began to crystallize. This result contrasts with the
behavior of related compounds where a proton was
trapped, for example, between two pyridine or imidazole
moieties.15 Changing the counterion to PF6 and using
more polar solvents such as THF or a THF/MeCN
mixture did not lead to the isolation of the desired
Experimental Section
General Procedures. All manipulations were carried out
under inert dinitrogen atmosphere, using standard Schlenk-
line conditions and dried and freshly distilled solvents. The
1H, 1H{31P}, 13C{1H}, 19F{1H}, and 31P{1H} NMR spectra were
recorded unless otherwise stated on a Bruker Avance 300
instrument at 300.13, 75.47, 282.40, and 121.49 MHz, respec-
tively, using TMS, CFCl3, or H3PO4 (85% in D2O) as external
standards with downfield shifts reported as positive. All NMR
spectra were measured at 298 K, unless otherwise specified.
The assignment of the signals was made by 1H,1H-COSY and
1H,13C-HMQC experiments. IR spectra in the range 4000-400
cm-1 were recorded as KBr pellets on a FT-IR IFS66 Bruker
spectrometer. Elemental C, H, and N analyses were performed
by the “Service de Microanalyses”, Universite´ Louis Pasteur,
Strasbourg.
(11) Holleman, A. F.; Wiberg, E. Lehrbuch der Anorganischen
Chemie, 91-100. ed.; de Gruyter: Berlin, 1985; p 133.
(12) Tripathi, U. M.; Bauer, A.; Schmidbaur, H. J. Chem. Soc.,
Dalton Trans. 1997, 2865.
(13) Carvajal, M. A.; Novoa, J. J.; Alvarez, S. J. Am. Chem. Soc.
2004, 126, 1465.
(14) Veya, P.; Floriani, C.; Chiesi-Villa, A.; Guastini, C.; Dedieu, A.;
Ingold, F.; Braunstein, P. Organometallics 1993, 12, 4359.
(15) See for example: (a) Glidewell, C.; Holden, H. D. Acta Crys-
tallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. 1982, 38, 667. (b)
Potrzebowski, M. J.; Cypryk, M.; Michalska, M.; Koziol, A. E.; Ka-
zmierski, S.; Ciesielski, W.; Klinowski, J. Phys. Chem. B 1998, 102,
4488. (c) Mautner, F. A.; Goher, M. S. A.; Grech. Polyhedron 1999, 18,
553.

Palladium Phosphino-Iminolate Complexes
Organometallics, Vol. 24, No. 13, 2005 3155
When BF4 was used as a counterion, the 19F{1H} spectra
To a solution of [AuCl(THT)] (0.10 g, 0.31 mmol) in CH2Cl2
(20 mL) were added THT (2 mL) and solid AgOTf (0.08 g, 0.31
mmol). An off-white precipitate was formed immediately, and
the mixture was stirred for 1 h at room temperature. After
filtration via cannula the solvent was removed in vacuo to yield
[Au(THT)2]OTf as a yellow powder (0.13 g, 0.25 mmol, 81%
based on Au). The residue was redissolved in CH2Cl2 (10 mL),
and a CH2Cl2 (10 mL) solution of 2 (0.11 g, 0.25 mmol) was
added. The mixture was stirred for 1 h, and the solvent was
removed in vacuo. The composition of the residue was con-
trolled by 31P{1H} NMR spectroscopy, and the three phosphorus-
containing fragments 5+, 7+ and 8+ were found in a ratio 1:15:
4, respectively. 31P{1H} NMR (CD2Cl2): δ 79.7 (s, PPh2 in 5+),
92.7 (s, PPh2 in 7+), 94.0 (s, PPh2 in 8+).
-
provided the appropriate signal with the pattern typical for
B10-F19 and B11-F19 shifts.16 The following compounds were
synthesized according to literature procedures or improved
syntheses: [Pd(dmba)(κ2-P,O-PPh2NC(O)Me)] (2),1 [Pd(dmba)-
(κ2-P,O-PPh2NHC(O)Me)]OTf (5‚OTf),2 [AuCl(THT)],17 [Cu-
(NCMe)4]BF4.18 Other chemicals were commercially available
and used as received. All yields given are based on Pd unless
otherwise stated.
Preparation of [Pd(dmba)(K2-P,O-PPh2N-C(-O)Me)]
(2). Improved Synthesis. The product can be directly
synthesized in a one-pot reaction from 0.5 equiv of [Pd(dmba)-
(µ-Cl)]2, 1 equiv of PPh2NHC(O)Me, and 1 equiv of KOt-Bu in
THF and stirring overnight. After removing the solvent in
vacuo and extraction of the residue with CH2Cl2, purification
can be done as published to receive the product in g80% yield.
Purification was achieved by recrystallization from a CH2-
Cl2 solution layered with pentane at 5 °C overnight (0.14 g,
0.15 mmol, 60%). 1H NMR (CD2Cl2): δ 2.06 (br s, 4H, CH2,
THT), 2.45 (d, 3H, 4JP-H ) 1.0 Hz, C(O)CH3), 2.88 (d, 6H, 4JP-H
) 2.7 Hz, N(CH3)2), 3.44 (br s, 4H, SCH2, THT), 4.00 (d, 2H,
4JP-H ) 2.1 Hz, NCH2), 6.55-6.70 (m, 2H, aryl-CH, dmba),
6.90-7.05 (m, 2H, aryl-CH, dmba), 7.50-7.60 (m, 4H, m-aryl,
PPh2), 7.60-7.70 (m, 2H, p-aryl, PPh2), 7.85-8.00 (m, 4H,
4
1H NMR (CDCl3): δ 2.22 (d, 3H, JP-H ) 0.9 Hz, C(O)CH3),
2.85 (d, 6H, 4JP-H ) 2.1 Hz, N(CH3)2), 3.92 (d, 2H, 4JP-H ) 1.7
Hz, NCH2), 6.65-6.70 (m, 1H, aryl-CH, dmba), 6.80-6.95 (m,
2H, aryl-CH, dmba), 7.00-7.05 (m, 1H, aryl-CH, dmba), 7.35-
7.50 (m, 6H, m-, p-aryl, PPh2), 7.70-7.80 (m, 4H, o-aryl, PPh2).
31P{1H} NMR (CDCl3): δ 81.9 (s, PPh2).
Preparation of [Pd(dmba)(K2-P,O-PPh2NHC(O)Me)]-
OTf (5‚OTf). Improved Synthesis. The product can also be
directly synthesized in a one-pot reaction from 1 equiv of PPh2-
NHC(O)Me, 0.5 equiv of [Pd(dmba)(µ-Cl)]2, and 1 equiv of
AgOTf in CH2Cl2. The workup was done as described and the
product isolated in g80% yield.2
3
o-aryl, PPh2). 13C{1H} NMR (CD2Cl2): δ 25.9 (d, JP-C ) 7.5
Hz, C(O)CH3), 30.7 (s, CH2, THT), 39.8 (br s, SCH2, THT), 49.9
3+4
(d, 3JP-C ) 2.7 Hz, N(CH3)2), 70.6 (d,
J
) 3.4 Hz, NCH2),
P-C
123.4 (s, aryl, dmba), 125.1 (s, aryl, dmba), 126.3 (d, JP-C
)
5.5 Hz, aryl, dmba), 129.3 (d, 3JP-C ) 11.2 Hz, m-aryls, PPh2),
1
4
131.0 (d, JP-C ) 57.7 Hz, ipso-aryls, PPh2), 132.7 (d, JP-C
)
[Pd(dmba)(κ2-P,O-PPh2NHC(O)Me)]PF6 (5‚PF6) can be pre-
pared analogously by the use of TlPF6 instead of AgOTf. H
2.5 Hz, p-aryls, PPh2), 133.4 (d, 2JP-C ) 13.6 Hz, o-aryls, PPh2),
1
137.6 (d, JP-C ) 10.6 Hz, aryl, dmba), 145.0 (s, Cq-dmba), 149.4
4
2+3
NMR (CDCl3): δ 2.44 (d, 3H, JP-H ) 0.6 Hz, C(O)CH3), 2.93
(d, JP-C ) 1.8 Hz, Cq-dmba), 187.7 (d,
J
) 4.9 Hz, CO);
P-C
(d, 6H, 4JP-H ) 3.0 Hz, N(CH3)2), 4.07 (d, 2H, 4JP-H ) 2.4 Hz,
NCH2), 6.60-6.65 (m, 1H, aryl-CH, dmba), 6.75-6.80 (m, 1H,
aryl-CH, dmba), 7.00-7.10 (m, 2H, aryl-CH, dmba), 7.50-7.65
(m, 6H, m-, p-aryl, PPh2), 7.80-7.90 (m, 4H, o-aryl, PPh2),
10.75 (br s, 1H, NH). 19F{1H} NMR (CDCl3): δ -78.8 (s, OTf).
31P{1H} NMR (CDCl3): δ 80.4 (s, PPh2).
the CF3 of OTf could not be assigned. 19F{1H} NMR (CD2Cl2):
δ -79.2 (s, OTf). 31P{1H} NMR (CD2Cl2): δ 92.7 (s, PPh2). 31P-
{1H} NMR (CDCl3): δ 92.7 (s, PPh2). IR (KBr, select.):
ν(NC+CO) 1509 s cm-1. Anal. Calcd for C28H33AuF3N2O4PPdS2
(917.06): C, 36.67; H, 3.63; N, 3.05. Found: C, 36.90; H, 3.94;
N, 2.89.
Preparation and Spectroscopic Data for [{Pd(dmba)-
Method B. A solution of [{Ag(2)}OTf]n, prepared in situ by
addition of solid AgOTf (0.09 g, 0.35 mmol) to a solution of 2
(0.17 g, 0.36 mmol) in THF (15 mL) and stirring for 2 h at
room temperature, was filtered into a solution of [AuCl(THT)]
(0.11 g, 0.11 mmol) in THF (15 mL). An off-white precipitate
was formed immediately, and the mixture was stirred for 2 h.
After removing all volatiles in vacuo, the composition of the
residue was controlled by 31P{1H} NMR spectroscopy and the
phosphorus-containing fragments 7+ and 8+ were found in a
ratio 1:1, respectively. 31P{1H} NMR (CDCl3): δ 92.7 (s, PPh2
in 7+), 94.1 (s, PPh2 in 8+).
Method C. THT (2 mL) and solid AgOTf (0.12 g, 0.47 mmol)
were added to a solution of 6 (0.33 g, 0.46 mmol) in CH2Cl2
(15 mL). An off-white precipitate was formed immediately, and
the mixture was stirred for 1 h at room temperature. After
removing all volatiles in vacuo, the composition of the residue
was controlled by 31P{1H} NMR spectroscopy and three
phosphorus-containing fragments were found in a ratio 2:4:1,
respectively. 31P{1H} NMR (CD2Cl2): δ 48.7 (s, unidentified
product), 92.5 (s, PPh2 in 7+), 94.1 (s, PPh2 in 8+).
(K2-P,O-PPh2NC(O)Me)}AuCl] (6). Solid [AuCl(THT)] (0.20
g, 0.62 mmol) was suspended in toluene (15 mL), and CH2Cl2
(ca. 1 mL) was added to ensure dissolution. Solid 2 (0.30 g,
0.62 mmol) was dissolved in toluene (20 mL) and added slowly
to the solution of [AuCl(THT)]. A colorless precipitate was
formed after 5 min, and the mixture was stirred for 15 min.
After filtration, the residue was washed with toluene (5 mL)
and dried in vacuo (0.33 g, 0.46 mmol, 74%). Single crystals
suitable for X-ray diffraction were obtained by layering a
CDCl3 solution with pentane. 1H NMR (CDCl3): δ 2.48 (d, 3H,
4
4JP-H ) 0.5 Hz, C(O)CH3), 2.86 (d, 6H, JP-H ) 2.6 Hz,
N(CH3)2), 3.96 (d, 2H, JP-H ) 1.7 Hz, NCH2), 6.65-6.75 (m,
4
2H, aryl-CH, dmba), 6.90-7.05 (m, 2H, aryl-CH, dmba), 7.40-
7.60 (m, 6H, m-, p-aryl, PPh2), 7.90-8.10 (m, 4H, o-aryl, PPh2).
3
13C{1H} NMR (CDCl3): δ 26.1 (d, JP-C ) 8.2 Hz, C(O)CH3),
3
3+4
50.0 (d, JP-C ) 2.7 Hz, N(CH3)2), 70.8 (d,
J
) 3.3 Hz,
P-C
NCH2), 123.0 (s, aryl, dmba), 124.9 (s, aryl, dmba), 126.3 (d,
JP-C ) 4.9 Hz, aryl, dmba), 129.0 (d, 3JP-C ) 11.8 Hz, m-aryls,
1
PPh2), 130.9 (d, JP-C ) 59.6 Hz, ipso-aryls, PPh2), 132.3 (d,
2
4JP-C ) 2.9 Hz, p-aryls, PPh2), 133.8 (d, JP-C ) 14.3 Hz,
Preparation and Spectroscopic Data for [{Pd(dmba)-
o-aryls, PPh2), 138.1 (d, JP-C ) 9.9 Hz, aryl, dmba), 146.0 (s,
(K2-P,O-PPh2NC(O)Me)}Au(tht)]BF4 (7‚BF4). A solution of
[Au(THT)]BF4, prepared in situ at -60 °C by addition of solid
AgBF4 (0.13 g, 0.67 mmol) to a solution of [AuCl(THT)] (0.20
g, 0.63 mmol) in CH2Cl2 (15 mL), was filtered at -60 °C via
cannula into a solution of 2 (0.30 g, 0.62 mmol) in THF (25
mL). An off-white precipitate was formed immediately, and
the mixture was stirred for 2 h while slowly reaching room
temperature. After removing all volatiles in vacuo, the com-
position of the residue was controlled by 31P{1H} NMR
spectroscopy and three phosphorus-containing fragments were
found in a 1:1:1 ratio. 31P{1H} NMR (CDCl3): δ 80.3 (s, PPh2
in 5+), 92.6 (s, PPh2 in 7+), 94.1 (s, PPh2 in 8+).
2+3
Cq-dmba), 148.9 (d, JP-C ) 1.9 Hz, Cq-dmba), 187.9 (d,
J
P-C
) 3.9 Hz, CO). 31P{1H} NMR (CDCl3): δ 94.1 (s, PPh2). 31P-
{1H} NMR (CD2Cl2): δ 93.9 (s, PPh2). IR (KBr, select.):
ν(NC+CO) 1506 s cm-1. Anal. Calcd for C23H25AuClN2OPPd
(715.27): C, 38.62; H, 3.52; N, 3.92. Found: C, 38.95; H, 3.74;
N, 3.53.
Preparation and Spectroscopic Data for [{Pd(dmba)-
(K2-P,O-PPh2NC(O)Me)}Au(tht)]OTf (7‚OTf). Method A.
(16) Kuhlmann, K.; Grant, D. M. J. Phys. Chem. 1964, 68, 3208.
(17) Uson, R.; Laguna, A.; Laguna, M. Inorg. Synth. 1989, 26, 85.
(18) Kubas, G. J. Inorg. Synth. 1979, 19, 90.

3156 Organometallics, Vol. 24, No. 13, 2005
Oberbeckmann-Winter et al.
Table 2. Selected Crystallographic Data for Complexes 2, 5‚OTf, 6, 7‚BF4, 8‚BF4‚2CH2Cl2, and 9‚BF4
2
5‚OTf
6
7‚BF4
8‚BF4‚2CH2Cl2
9‚BF4
formula
C
23H25N2OPPd
C23H26N2OPPd,
CF3SO3
632.90
triclinic
P1h
9.258(1)
10.199(1)
14.834(2)
80.986(5)
73.696(5)
78.136(5)
1308.3(3)
2
C
23H25AuClN2OP
Pd
C
27H33AuN2OP
Pd S, BF4
C
46H50AuN4O2P2
C
46H50CuN4O2P
Pd2, BF4
Pd2,BF4 2(CH2Cl2)
fw
482.82
monoclinic
P21/n
9.105(1)
24.945(5)
9.626(1)
90
99.16(5)
90
2158.4(5)
4
715.24
triclinic
P1h
854.76
monoclinic
P21/c
9.7620(2)
19.4120(5)
15.5880(4)
90
98.5530(9)
90
2921.1(1)
4
1419.27
triclinic
P1h
1115.99
monoclinic
P21/n
12.130(2)
18.709(3)
20.621(3)
90
90.93(5)
90
4679(1)
4
cryst syst
space group
a (Å)
9.2940(2)
11.4570(2)
11.6150(3)
86.9000(8)
80.4300(7)
72.980(1)
1166.14(4)
2
10.0860(1)
13.2050(2)
21.2590(3)
90.27(5)
92.78(4)
99.31(9)
2790.6(7)
2
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
cryst size
(mm3)
color
0.15 × 0.13 × 0.09 0.10 × 0.09 × 0.08 0.10 × 0.09 × 0.08 0.03 × 0.02 × 0.01 0.10 × 0.09 × 0.08
0.08 × 0.07 × 0.05
yellow
1.486
colorless
1.607
colorless
2.037
yellow
1.944
colorless
1.689
colorless
1.584
Dcalc
(g‚cm-3
)
µ (mm-1
T (K)
)
0.949
173(2)
984
0.905
173(2)
640
7.255
293(2)
684
5.808
173(2)
1656
3.562
173(2)
1392
1.337
173(2)
2248
F(000)
θ limits
(deg)
1.63/30.01
1.44/27.87
1.78/30.04
1.69/30.02
1.82/30.03
1.47/29.95
no. of data
measd
no. of data
(I > 2σ(I))
no. of
6011
4249
253
6204
5087
329
6789
5936
271
8529
4259
352
16 323
11 545
610
13 529
8539
559
params
R1
0.0404
0.0355
0.0323
0.0546
0.0492
0.0803
wR1
0.1290
0.0814
0.1127
0.1614
0.1430
0.1449
GOF
1.177
0.610/-0.868
1.057
0.505/-0.958
1.062
1.375/-2.913
0.969
1.127/-1.153
0.987
1.435/-1.267
1.104
1.008/-0.710
max./min.
res
dens (e‚Å-3
)
Single crystals of 7‚BF4 suitable for X-ray diffraction were
Preparation and Spectroscopic Data for [{Pd(dmba)-
obtained by layering a CDCl3 solution with pentane.
Preparation and Spectroscopic Data for [{Pd(dmba)-
(K2-P,O-PPh2NC(O)Me)}2Cu]BF4 (9‚BF4). Solid 2 (0.31 g,
0.64 mmol) was dissolved in THF (25 mL), and [Cu(NCMe)4]-
BF4 (0.10 g, 0.32 mmol) was added in one portion. A white
precipitate was formed after 5 min, and the mixture was
stirred for 2 h. After filtration, the residue was washed with
THF (5 mL) and dried in vacuo to yield the product as a
colorless powder (0.31 g, 0.28 mmol, 88%). Single crystals
suitable for X-ray diffraction were obtained by layering a CH2-
Cl2 solution with pentane. 1H NMR (CDCl3): δ 1.80 (s, 2 ×
3H, C(O)CH3), 2.84 (d, 2 × 6H, 4JP-H ) 2.5 Hz, N(CH3)2), 3.95
(K2-P,O-PPh2NC(O)Me)}2Au]BF4 (8‚BF4). A solution of [Au-
(THT)]BF4, prepared in situ at -60 °C by addition of solid
AgBF4 (0.06 g, 0.31 mmol) to a solution of [AuCl(THT)] (0.10
g, 0.31 mmol) in CH2Cl2 (15 mL), was filtered at -60 °C via
cannula into a solution of 2 (0.30 g, 0.62 mmol) in THF (25
mL). An off-white precipitate was formed immediately, and
the mixture was stirred for 3 h while slowly reaching room
temperature. After removing all volatiles in vacuo, the residue
was washed with THF (2 × 5 mL) and dried again in vacuo to
yield an off-white powder, which was found to be the desired
product as CH2Cl2 adduct (0.32 g, 0.24 mmol, 77%). Single
crystals suitable for X-ray diffraction were obtained by layering
4
(d, 2 × 2H, JP-H ) 1.9 Hz, NCH2), 6.50-6.55 (m, 2 × 1H,
aryl-CH, dmba), 6.60-6.70 (m, 2 × 1H, aryl-CH, dmba), 6.90-
7.00 (m, 2 × 2H, aryl-CH, dmba), 7.35-7.45 (m, 2 × 4H,
m-aryl, PPh2), 7.50-7.60 (m, 2 × 2H, p-aryl, PPh2), 7.60-7.70
(m, 2 × 4H, o-aryl, PPh2). 13C{1H} NMR (CDCl3): δ 24.9 (d,
1
a CH2Cl2 solution with pentane. H NMR (CDCl3): δ 1.90 (d,
3
3JP-C ) 9.3 Hz, C(O)CH3), 50.1 (d, JP-C ) 2.4 Hz, N(CH3)2),
4
4
2 × 3H, JP-H ) 0.6 Hz, C(O)CH3), 2.86 (d, 2 × 6H, JP-H
)
3+4
2.6 Hz, N(CH3)2), 3.97 (d, 2 × 2H, 4JP-H ) 2.1 Hz, NCH2), 5.30
(s, 2H, CH2Cl2), 6.45-6.55 (m, 2 × 1H, aryl-CH, dmba), 6.60-
6.70 (m, 2 × 1H, aryl-CH, dmba), 6.85-7.00 (m, 2 × 2H, aryl-
CH, dmba), 7.40-7.50 (m, 2 × 4H, m-aryl, PPh2), 7.55-7.65
(m, 2 × 2H, p-aryl, PPh2), 7.70-7.80 (m, 2 × 4H, o-aryl, PPh2).
70.7 (d,
J
) 3.2 Hz, NCH2), 123.2 (s, aryls, dmba), 125.0
P-C
(s, aryls, dmba), 126.2 (d, JP-C ) 5.2 Hz, aryls, dmba), 129.3
(d, 3JP-C ) 11.3 Hz, m-aryls, PPh2), 131.3 (d, 1JP-C ) 57.7 Hz,
ipso-aryls, PPh2), 132.3 (d, 4JP-C ) 2.0 Hz, p-aryls, PPh2), 133.1
2
(d, JP-C ) 13.4 Hz, o-aryls, PPh2), 137.6 (d, JP-C ) 10.2 Hz,
3
13C{1H} NMR (CDCl3): δ 25.4 (d, JP-C ) 7.6 Hz, C(O)CH3),
aryls, dmba), 145.5 (s, aryls, Cq-dmba), 149.1 (d, JP-C ) 1.7
2
Hz, aryls, Cq-dmba), 187.7 (d, JP-C ) 2.2 Hz, CO). 19F{1H}
50.1 (d, 3JP-C ) 2.8 Hz, N(CH3)2), 53.5 (CH2Cl2), 70.7 (d,
J
3+4
P-C
NMR (CDCl3): δ -154.6 (s, BF4). 31P{1H} NMR (CDCl3): δ
89.2 (s, PPh2). 31P{1H} NMR (CD2Cl2): δ 89.0 (s, PPh2). IR
(KBr, select.): ν(NC+CO) 1492 s cm-1. Anal. Calcd for C46H50-
BCuF4N4O2P2Pd2 (1116.06): C, 49.51; H, 4.52; N, 5.02.
Found: C, 49.20; H, 4.75; N, 4.67.
) 2.8 Hz, NCH2), 123.3 (s, aryls, dmba), 125.1 (s, aryls, dmba),
3
126.3 (d, JP-C ) 5.5 Hz, aryls, dmba), 129.2 (d, JP-C ) 11.1
Hz, m-aryls, PPh2), 130.7 (d, 1JP-C ) 61.1 Hz, ipso-aryls, PPh2),
132.4 (d, 4JP-C ) 2.8 Hz, p-aryls, PPh2), 133.4 (d, 2JP-C ) 13.8
Hz, o-aryls, PPh2), 137.6 (d, JP-C ) 10.4 Hz, aryls, dmba), 145.4
(d, JP-C ) 1.4 Hz, aryls, Cq-dmba), 149.1 (d, JP-C ) 1.4 Hz,
aryls, Cq-dmba), 187.6 (s, CO). 19F{1H} NMR (CDCl3): δ -154.4
(s, BF4). 31P{1H} NMR (CDCl3): δ 94.1 (s, PPh2). IR (KBr,
select.): ν(NC+CO) 1508 s cm-1. Anal. Calcd for C46H50-
AuBF4N4O2P2Pd2‚CH2Cl2 (1334.41): C, 42.30; H, 3.93; N, 4.20.
Found: C, 41.85; H, 4.04; N, 4.13.
Reaction between [Pd(dmba)(K2-P,O-PPh2NC(O)Me)]
(2) and [Cu(NCMe)4]BF4 to Yield 10‚BF4. Solid 2 (0.24 g,
0.50 mmol) was dissolved in THF (20 mL), and [Cu(NCMe)4]-
BF4 (0.15 g, 0.48 mmol) was added in one portion. A white
precipitate was formed after 5 min, and the mixture was
stirred for 3 h. After removing the volatiles in vacuo, the

Palladium Phosphino-Iminolate Complexes
Organometallics, Vol. 24, No. 13, 2005 3157
composition of the residue was controlled by 31P{1H} NMR
spectroscopy and three phosphorus-containing compounds
were found in a 4:1:2 ratio, respectively. 31P{1H} NMR
(CDCl3): δ 80.3 (s, PPh2 in 5+), 88.9 (s, PPh2 in 10+), 89.2 (s,
PPh2 in 9+).
tion was corrected empirically (with Sortav) for compounds 2,
6, and 8‚BF4‚2CH2Cl2.19 All non-hydrogen atoms except those
from CH2Cl2 in 8‚BF4‚2CH2Cl2 were refined with anisotropic
parameters. The hydrogen atoms were included in their
calculated positions and refined with a riding model in
SHELXL97.20
The crystallographic material can be obtained from the
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK (fax: (44) 1223-336-033; e-mail:
deposit@ccdc.cam.ac.uk), under deposition numbers CCDC
261460-261465.
Reaction between [Pd(dmba)(K2-P,O-PPh2NC(O)Me)]
(2) and [Pd(dmba)(K2-P,O-PPh2NHC(O)Me]OTf (5‚OTf).
Solid 2 (0.12 g, 0.25 mmol) and 5‚OTf (0.16 g, 0.25 mmol) were
dissolved in THF (20 mL) or CH2Cl2/toluene (20 mL), and the
mixture was stirred for 1 h. After removing the solvent in
vacuo, the composition of the residue was controlled by means
of 31P{1H} NMR spectroscopy. Analogously, the reaction can
1
Acknowledgment. This work was supported by the
CNRS and the Ministe`re de la Recherche. We are
grateful to the European Commission for support in the
COST D-30 Action and to a Marie Curie fellowship
(HPMF-CT-2002-01659) and to the French Embassy in
Berlin and the Ministe`re des Affaires Etrange`res (Paris)
for a postdoctoral grant to N.O.-W. The authors also
wish to thank Anne Degre´mont for experimental sup-
port.
be done using 2 and 5‚PF6. H NMR (CDCl3): δ 2.34 (s, 2 ×
3H, C(O)CH3), 2.89 (d, 2 × 6H, 4JP-H ) 2.6 Hz, N(CH3)2), 4.00
4
(d, 2 × 2H, JP-H ) 2.0 Hz, NCH2), 6.60-6.70 (m, 2 × 2H,
aryl-CH, dmba), 6.90-7.05 (m, 2 × 2H, aryl-CH, dmba), 7.40-
7.60 (m, 2 × 6H, m-, p-aryl, PPh2), 7.75-7.85 (m, 2 × 4H,
o-aryl, PPh2). 31P{1H} NMR (CDCl3): δ 81.0 (s, PPh2). 31P{1H}
NMR (CD2Cl2): δ 80.8 (s, PPh2). 31P{1H} NMR (CD2Cl2, 181
K): δ 81.6 (s, PPh2), 83.6 (s, PPh2).
X-ray Collection and Structure Determinations. The
diffraction data were collected on a Nonius Kappa-CCD area
detector diffractometer (Mo KR, λ ) 0.71070 Å; phi scan). The
relevant data are summarized in Table 2. The cell parameters
were determined from reflections taken from one set of 10
frames (1.0° steps in phi angle), each at 20 s exposure. The
structures were solved using direct methods (SHELXS97) and
refined against F2 using the SHELXL97 software. The absorp-
Supporting Information Available: Crystallographic
information files (CIF) and ORTEP plots of all the structures.
This material is available free of charge via Internet at
http://pubs.acs.org.
OM050156D
(20) Sheldrick, G. M. SHELXL97, Program for the refinement of
crystal structures; University of Go¨ttingen: Germany, 1997.
(19) Blessing, R. H. Crystallogr. Rev. 1987, 1, 3.