Different coordinating behaviour of the imino-phosphoranes Ph3P=NC(O)CH2Cl and Ph3P=NC(O)-2-NC5H4 towards M(II) complexes (M = Pd, Pt)

Article abstract of DOI:10.1039/a807066k

The coordination behaviour of the iminophosphorane ligands Ph₃P=NC(O)CH₂Cl and Ph₃P=NC(O)-2-NC₅H₄ towards different Pd(II) and Pt(II) substrates has been explored. The iminophosphorane Ph₃P=NC(O)CH₂Cl shows a poor coordination ability, always binding through the iminic N atom. Thus, Ph₃P=NC(O)CH₂Cl reacts with PdCl₂(NCPh)₂, [M(C / P)(NCMe)₂]ClO₄ (M = Pd, Pt) and [Pd(dmba)(NCMe)₂]ClO₄ (2:1, 1:1 and 1:1 molar ratio, respectively, C / P = ortho-CH₂C₆H₄P(o-Tol)₂-C,P; dmba = C₆H₄CH₂NMe₂- 2), resulting in the formation of trans-PdCl₂{N(=PPh₃)C(O)CH₂Cl}₂, 1, [M(C / P){N(=PPh₃)C(O)CH₂Cl}(NCMe)]ClO₄ (M = Pd, 2; Pt, 3) and [Pd(dmba){N(=PPh₃)C(O)CH₂Cl}(NCMe)]ClO₄, 4. However, the iminophosphorane Ph₃P=NC(O)-2-NC₅H₄ displays at least three different coordination modes, as a function of the starting material. The reaction of Ph₃P=NC(O)-2-NC₅H₄ with PdCl₂(NCPh)₂ or PtCl₂ (1:1 molar ratio) gives cis-Cl₂M{N(=PPh₃)C(O)-2-NC₅H₄} (M = Pd, 5; Pt, 6) in which the ligand acts as an N,N-chelate. The reaction with the bis-solvate orthometallated complexes [M(C / P)(NCMe)₂]ClO₄ (M = Pd, Pt) and [Pd(dmba)(NCMe)₂]ClO₄ (1:1 molar ratio) gives the bis-chelate complexes [M(C / P){NC₅H₄-2- C(O)N=PPh₃}]ClO₄ (M = Pd 7, Pt 8) and [Pd(dmba){NC₅H₄-2- C(O)N=PPh₃}]ClO₄, 9, in which the iminophosphorane ligand is coordinated through the pyridinic nitrogen atom and the carbonyl oxygen atom. The X-ray crystal structure of 9 has been determined. The reaction with [Pd(dmba)(PPh₃)(THF)]ClO₄ (1:1 molar ratio) gives the cationic derivative [Pd(dmba)(PPh₃){NC₅H₄-2-C(O)N=PPh₃}]ClO₄, 10, in which the iminophosphorane ligand is coordinated only through the pyridinic nitrogen atom. Finally, the iminophosphorane reacts with [Pd(μ-Cl)(dmba)]₂ (2:1 molar ratio) resulting in the cleavage of the chlorine bridging system by the pyridinic N atom and formation of [Pd(dmba)Cl{NC₅H₄-2-C(O)N=PPh₃}], 11.

Full text of DOI:10.1039/a807066k

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Di†erent coordinating behaviour of the imino-phosphoranes
Ph PxNC(O)CH Cl and Ph PxNC(O)-2-NC H towards MII
3
2
3
5 4
complexes (M = Pd, Pt)
Larry R. Falvello, Mar•a M. Garc•a, Ignacio Lazaro, Rafael Navarro* and
Esteban P. Urriolabeitia
Departamento de Qu•mica Inorganica, Instituto de Ciencia de Materiales de Aragon, Universidad
de Zaragoza- Consejo Superior de Investigaciones Cient•Ðcas, 50009 Zaragoza, Spain.
E-mail: rafanava=posta.unizar.es and esteban=posta.unizar.es
Received (in Montpellier, France) 9th September 1998, Accepted 17th November 1998
The coordination behaviour of the iminophosphorane ligands Ph PxNC(O)CH Cl and Ph PxNC(O)-2-NC H
3
2
3
5 4
towards di†erent PdII and PtII substrates has been explored. The iminophosphorane Ph PxNC(O)CH Cl shows a
3
2
poor coordination ability, always binding through the iminic N atom. Thus, Ph PxNC(O)CH Cl reacts with
3
2
2
PdCl (NCPh) , [M(C\P)(NCMe) ]ClO (M \ Pd, Pt) and [Pd(dmba)(NCMe) ]ClO (2 : 1, 1 : 1 and 1 : 1 molar
2
2
2
4
4
ratio, respectively, C\P \ ortho-CH C H P(o-Tol) -C,P; dmba \ C H CH NMe -2), resulting in the formation of
2 6
trans-PdCl MN(xPPh )C(O)CH ClN , 1, [M(C\P)MN(xPPh )C(O)CH ClN(NCMe)]ClO (M \ Pd, 2; Pt, 3) and
4
2
6
4
2
2
2
2
3
2
2
3
4
[Pd(dmba)MN(xPPh )C(O)CH ClN(NCMe)]ClO , 4. However, the iminophosphorane Ph PxNC(O)-2-NC H
3
2
4
3
5 4
displays at least three di†erent coordination modes, as a function of the starting material. The reaction of
Ph PxNC(O)-2-NC H with PdCl (NCPh) or PtCl (1 : 1 molar ratio) gives cis-Cl MMN(xPPh )C(O)-2-
3
5
4
2
2
2
2
3
NC H N (M \ Pd, 5; Pt, 6) in which the ligand acts as an N,N-chelate. The reaction with the bis-solvate
5
4
orthometallated complexes [M(C\P)(NCMe) ]ClO (M \ Pd, Pt) and [Pd(dmba)(NCMe) ]ClO (1 : 1 molar
2
4
5
2
4
ratio) gives the bis-chelate complexes [M(C\P)MNC H -2-C(O)NxPPh N]ClO (M \ Pd 7, Pt 8) and
4
3
4
[Pd(dmba)MNC H -2-C(O)NxPPh N]ClO , 9, in which the iminophosphorane ligand is coordinated through the
5
4
3
4
pyridinic nitrogen atom and the carbonyl oxygen atom. The X-ray crystal structure of 9 has been determined. The
reaction with [Pd(dmba)(PPh )(THF)]ClO (1 : 1 molar ratio) gives the cationic derivative
3
4
3
[Pd(dmba)(PPh )MNC H -2-C(O)NxPPh N]ClO , 10, in which the iminophosphorane ligand is coordinated only
through the pyridinic nitrogen atom. Finally, the iminophosphorane reacts with [Pd(l-Cl)(dmba)] (2 : 1 molar
ratio) resulting in the cleavage of the chlorine bridging system by the pyridinic N atom and formation of
3
5
4
4
2
[Pd(dmba)ClMNC H -2-C(O)NxPPh N], 11.
5
4
3
Over the last few years our research group has been interested
in the coordination chemistry of the a-stabilized phosphorus
ylides Ph PxC(H)R (R \ COMe, COPh, COOMe, CONMe ,
Prompted by the results obtained with the a-stabilized
ylides, we have undertaken a study of the coordination chem-
istry of stabilized iminophosphoranes possessing a carbonyl
group bonded to the iminic nitrogen24Èa series of com-
pounds for which there is no precedent in coordination chem-
istry. The reactivity of two of these derivatives,
Ph PxNC(O)CH Cl and Ph PxNC(O)-2-NC H , towards
3
2
CN), due to the fact that these ylides can behave as ambiden-
tate ligands.1h6 The main thrust of this work relates to the
reactivity of the aforementioned Ph PxC(H)R ylides towards
3
several ortho-metallated complexes of PdII and PtII; we have
3
2
3
5 4
observed the ambidentate character of the a-stabilized ylides
and have also seen that it is possible to predict both the coor-
dination site of the ylide (when there are two possibilities) and
the donor atom linked to the metal (O- versus C-coordination,
N- versus C-coordination), taking into account as simple an
e†ect as the antisymbiotic behaviour of the metal centre7,8
and the di†erent electronic and steric requirements of the
ylides in their di†erent coordination modes.
several palladium(II) and platinum(II) substrates has been
explored (see Scheme 1). We have chosen complexes with two
labile ligands in di†erent arrangements and with di†erent
trans atoms such as trans-MCl (NCPh) (M \ Pd, Pt),25
2
2
[M(C\P)(NCMe) ]ClO (M \ Pd,26 Pt 27) and [Pd(dmba)-
2
4
(NCMe) ]ClO 28 (C\P \ ortho-CH C H P(o-Tol) ; dmba \
2 6
C H CH NMe -2), complexes with one labile ligand such as
2
2
4
4
2
6
5
2
[Pt(C\P)(PPh )(NCMe)]ClO 5 and [Pd(dmba)(PPh )(THF)]-
3
4
3
The iminophosphoranesÈcompounds of general structure
ClO 29 and dinuclear complexes such as [M(l-Cl)(C\P)]
4
2
R PxNR@Èare an interesting class of compounds closely
(M \ Pd,30 Pt 27) and [Pd(l-Cl) (dmba)] 31 in order to
3
2
related to the ylides and which show numerous applications
explore the coordination properties (nucleophilic ability of
to organic synthesis (for instance, the formation of CxN
bonds through the AzaÈWittig reaction).9a Moreover, they can
also behave as ligands towards transition metals through, at
least, the lone pair on the N atom. In spite of these simi-
larities, their use as ligands is less developed than that of the
ylides,9 although in the past decade some interesting studies
based on the coordinative properties and the reactivity of
iminophosphoranes derived from mono- and diphosphines
have been reported.9h23
the iminic N atom and steric requirements) of these ligands in
di†erent environments. In this paper we report the
results obtained from this chemistry.
Results
Reactions of Ph PxNC(O)CH Cl
3
2
The reaction of trans-PdCl (NCPh) with Ph PxNC(O)-
2
2
3
CH Cl (1:2 molar ratio) in acetone at room temperature
2
New J. Chem., 1999, 227È235
227

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results in the precipitation of trans-PdCl MN(xPPh )C(O)-
+
2
3
PPh3
CH ClN , 1, according to its elemental analysis and spectro-
+
C
X
C
X
NCMe
NCMe
N
2
2
COCH2Cl
NCMe
scopic data [see below and eqn. (1)]. Under the same condi-
(2)
+
Ph3P=NC(O)CH2Cl
M
M
tions PtCl (NCPh) does not react with Ph PxNC(O)CH Cl.
2
2
3
2
The same result was observed even under more drastic condi-
tions (reÑuxing toluene) and when other precursors were used
in di†erent solvents and temperatures. It is worth noting that
similar reactions between Na [PdCl ] and the imin-
2 X = P(o-Tol)2, M = Pd
3 X = P(o-Tol)2, M = Pt
4 X = NMe2; M = Pd
2
4
ophosphoranes (C H R) PxNC H -R@ (R \ H, R@ \ m-Me,
The reaction between [Pt(C\P)(PPh )(NCMe)]ClO and
6
4
3
6 4
p-Me, p-OMe; R \ 4-Me, R@ \ p-OMe) result in the forma-
tion of the ortho-metallated derivatives32 [Pd(l-Cl)MC H -4-
3
4
Ph PxNC(O)CH Cl does not take place even in reÑuxing
3
2
THF, and the mixture of the starting compounds is recovered.
The same lack of reactivity has been observed in the reaction
of the cationic precursor [Pd(dmba)(PPh )(THF)]ClO with
6
3
R-P(C H R-4) NR@-2N] and that in these reactions com-
6
4
2
2
plexes of the type L PdCl were not isolated.
2
2
3
4
Ph PxNC(O)CH Cl. In the same way, Ph PxNC(O)CH Cl
3
2
3
2
Cl
is not able to promote the cleavage of the halide bridging
PPh3
Ph3P
(1)
PdCl2(NCPh)2 + 2 Ph3P=NC(O)CH2Cl
N
Pd
N
system in [Pd(l-Cl)(dmba)] or in [M(l-Cl)(C\P)] (M \ Pd,
2
2
COCH2Cl
ClH2COC
Pt).
Cl
1
Reactions of Ph PxNC(O)-2-NC H
5 4
3
The reaction of trans-PdCl (NCPh) with Ph PxNC(O)-2-
2 2 3
NC H (1 : 1 molar ratio) in acetone at room temperature
The reactions of the iminophosphorane Ph PxN(CO)-
3
CH Cl with other bis-solvate complexes show di†erent
2
5 4
results in the formation of cis-Cl PdMN(xPPh )C(O)-2-
2
3
behaviour from that described for the reaction giving 1.
NC H N, 5 which precipitates as an analytically pure orange
5
4
The reaction of [M(C\P)(NCMe) ]ClO (M \ Pd, Pt)
solid from the reaction mixture. Under the same conditions,
2
4
with Ph PxNC(O)CH Cl (1 : 1 molar ratio) in CH Cl
the reaction of PtCl (NCPh) with Ph PxNC(O)-2-NC H
3
2
2
2
2
2
3
5 4
at room temperature gives the cationic derivatives
gives poor yields (about 10%) of cis-Cl PtMN(xPPh )C(O)-2-
2
3
[M(C\P)(NCMe)MN(xPPh )C(O)CH ClN]ClO (M \ Pd, 2;
NC H N, 6, and most of the starting products remain
unchanged. This yield is not improved (or only slightly) if the
3
2
4
5 4
Pt, 3) [see eqn. (2)] as white solids, in analytically pure form
according with their elemental analyses and mass spectra.
Attempts to displace the remaining NCMe molecule in 2 and
3 by further addition of iminophosphorane resulted in unclear
results. If the reaction is performed under the same conditions
but using a metal : ligand molar ratio of 1 : 2, a mixture of 2
or 3 and the free iminophosphorane is obtained. Similar
results were obtained with the bis-solvate derivative
reaction is performed at reÑux temperature or if cis-
Cl Pt(COD) is used as starting material. The best yields of the
2
analytically pure product were obtained from the reaction of
PtCl with Ph PxNC(O)-2-NC H (1 : 1 molar ratio) in a
2
3
5 4
CH Cl Èacetone mixture at reÑux temperature (see
2
2
Experimental). In both complexes the iminophosphorane
ligand is N,N-bonded to the metal centre, through the pyri-
dinic N atom and through the iminic N atom (see Scheme 1).
A di†erent coordination mode is observed when other bis-
solvate derivatives are allowed to react with this ligand. The
reaction of [M(C\P)(NCMe) ]ClO (M \ Pd, Pt) with 1
[Pd(dmba)(NCMe) ]ClO . Its reaction with
1
equiv. of
2
4
Ph PxNC(O)CH Cl in CH Cl at room temperature gave
3
2
2 2
[Pd(dmba)(NCMe)MN(xPPh )C(O)CH ClN]ClO ,
4,
as
3
2
4
characterized by its elemental analysis and mass spectrum.
From 4 it was not possible to displace the NCMe ligand by
further addition of iminophosphorane [see eqn. (2)], and the
reaction of the starting product with two equivalents of imino-
phosphorane gave a mixture of 4 and free ligand. The struc-
tures of complexes 2È4 has been elucidated from their spectro-
scopic data (see below).
2
4
equiv. of Ph PxNC(O)-2-NC H results in the formation of
3
5 4
white solids of stoichiometry [M(C\P)MPh PNC(O)-
3
NC H N]ClO (M \ Pd, 7; Pt, 8) as deduced from their ele-
5
4
4
mental analyses and mass spectra (see Experimental). The
spectroscopic data (see below) suggest in this case a bonding
mode of the iminophosphorane ligand through the pyridinic
Scheme 1 Synthesis of complexes 5È11
228
New J. Chem., 1999, 227È235

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+
Ph3P
+
Ph3P
N atom and through the carbonyl oxygen, as depicted in
Scheme 1.
A behaviour similar to that described for the reactions
R
R
N
C
R
N
–
N
Ph3P
C
O
C
O
O
–
giving complexes 7,
8 is observed in the reaction of
a
b
c
[Pd(dmba)(NCMe) ]ClO with Ph PxNC(O)-2-NC H (1 : 1
2
4
3
5 4
molar ratio). The stoichiometry of the reaction product agrees
with the formulation [Pd(dmba)MPh PNC(O)NC H N]ClO ,
3
5
4
4
R
+
9, as indicated by its elemental analysis and mass spectrum,
and the spectroscopic data reveal that an N(py) ] O(carbonyl)
coordination has taken place (see Scheme 1). The determi-
nation of the crystal structure of complex 9 shows unam-
biguously that the iminophosphorane ligand is coordinated
through the pyridinic N atom and through the carbonyl
oxygen (see below).
Ph3P
N
C
O
–
d
Scheme 2 Proposed resonance forms for the iminophosphoranes
Ph PxNC(O)R (R \ CH Cl, NC H -2).
3
2
5 4
+
PPh3
+
PPh3
On the other hand, the reaction of [Pt(C\P)-
(PPh )(NCMe)]ClO with the iminophosphorane (1 : 1 molar
PPh3
–
[M]
N
[M]
N
[M]
N
R
C
R
R
C
3
4
ratio) a†ords a mixture of products in which it is possible to
identify complex 8 as the main product; that is, the chelate
e†ect is strong enough to promote the N,O-coordination.
C
O
B
–
O
A
O
C
Similar results were obtained in the reaction of [Pt(l-Cl)(C\P)]
with the iminophosphorane (1 : 2 molar ratio). In this case
Scheme 3 Proposed resonance forms for the coordinated imino-
phosphoranes Ph PxNC(O)R (R \ CH Cl, NC H -2).
2
3
2
5 4
the reaction product was identiÐed as [Pt(C\P)-
MPh PNC(O)NC H N]`Cl~ [(8`)(Cl~)]. The palladium
terms of the resonance forms a and b which result in forms A
and B. It has been proposed previously13 that the bond orders
can be conveniently described by the presence of the double
bond form A and the dipolar form B, with a higher partici-
pation of A than of B. Thus, it is sensible to assume that the
decrease in the energy of the PxN absorption could be due to
the presence of the canonical form B and the increase in the
CO absorption energy can be rationalized on the basis of the
existence of both forms A and B. Additional evidence for the
N-coordination of the iminophosphorane ligand can be found
in the 31PM1HN NMR spectrum of 1. It displays a single reso-
nance at 37.50 ppmÈthat is, shifted downÐeld by more than
16 ppm with respect to the free ligand (21.36 ppm). This
deshielding of the P atom is in good agreement with the
weakening of the PwN bond in form B, and it has been pre-
viously proposed as a proof of N-bonding.13h15
3
5 4
complex [Pd(l-Cl)(C\P)] does not react with the imin-
2
ophosphorane, even in reÑuxing THF.
However, the reaction of [Pd(dmba)(PPh )(THF)]ClO
3
4
[generated in situ from PdCl(dmba)(PPh ) and AgClO ] with
3
4
the iminophosphorane (1 : 1 molar ratio) results in the forma-
tion of a solid of stoichiometry [Pd(dmba)(PPh )MPh PNC
3
3
(O)NC H N]ClO , 10, as deduced from its elemental analysis
5
4
4
and mass spectrum. For this complex, the spectroscopic
parameters indicate that a di†erent coordination mode is
involved; only the pyridinic N atom is bonded to the palla-
dium centre trans to the ortho-metallated carbon atom of the
dmba ligand (see Scheme 1).
The same coordination mode of the ligand is obtained in
the reaction of [Pd(dmba)(l-Cl)] with the iminophosphorane
2
(1 : 2 molar ratio). A pale yellow solid of stoichiometry
[PdCl(dmba)MPh PNC(O)NC H N], 11, is obtained, as a
Complexes 2È4 show in their IR spectra absorptions
attributable to the presence of coordinated NCMe (about
2200 cm~1) and characteristic absorptions of the C\P 27 and
dmba28 ligands. Moreover, the IR spectra of 2È4 also show
features similar to those described for complex 1, namely a
decrease in the energy of the PxN absorption and an increase
for that of the carbonyl with respect to the free ligand. These
facts allow us to propose for 2È4 the same coordination mode
as in 1. The 31PM1HN NMR spectrum of 2 at low temperature
3
5 4
result of the cleavage of the bridging chlorine system, and it
shows similar spectroscopic features as those described for 10.
That is, the iminophosphorane is coordinated selectively
through the N(py) atom and is trans to the NMe group (see
2
Scheme 1).
Spectroscopic characterization of complexes 1–11
The IR spectrum of 1 suggests a trans arrangement of the
ligands since only one PdwCl stretch is observed at 319
cm~1. In addition, the PxN absorption undergoes a signiÐ-
(CDCl , 213 K) shows two close singlets at about 38 ppm,
3
while the spectrum of 3 shows a broad resonance at about 16
ppm with 195Pt satellites (1J \ 4334 Hz) that is attributed
PtP
cant shift to lower energies (1325 cm~1, *m \ m
to the C\P ligand, and a doublet resonance at about 40 ppm
complex
[ m
\ [ 23 cm~1) compared to the free ligand (1348
with 195Pt satellites (2J \ 62.2 Hz) that is assigned to the
ligand
PtP
cm~1). This low frequency shift indicates that the ligand is
coordinated through the lone pair of the N atom14 [(see eqn.
(1)] although the magnitude of the shift is smaller than that
described for other N-coordinated iminophosphoranes.14 A
more remarkable fact is the sizable increase in the carbonyl
stretch energy (1643 cm~1 in 1, 1602 cm~1 in the free ligand,
*m \ 41 cm~1), probably as a result of the fact that, after
coordination, the extensive conjugation of the PxN and
CxO bonds24 is partially blocked and that there is no lone
pair delocalization.
iminophosphorane ligand. These facts mean that the P
nucleus of the iminophosphorane ligand is deshielded with
respect to the free ligand, as we have described for 1, and
again points to N-coordination for this ligand. In addition,
the appearance of the latter resonance as a doublet (3J \ 5.9
PP
Hz) and the magnitude of the coupling constant suggest a
mutually trans arrangement of the P atom of the C\P ligand
and the PxN ligand around the platinum centre5 as depicted
in eqn. (2). The broad signal at 16 ppm for 3 is not resolved on
further cooling (CD Cl , 183 K) and the spectrum of 2 in
2 2
CD Cl at 183 K shows a broadening of the resonances
Scheme 2 shows the proposed resonance forms aÈd for the
free iminophosphorane. Using these forms as a point of depar-
ture, we suggest the canonical forms AÈC in Scheme 3 for the
coordinated iminophosphorane. It is clear that the forms c
and d in Scheme 2 could not contribute to the description of
the bonding, since a decrease in the energy of the CO stretch
should then be observed (for instance, in form C in Scheme 3).
Thus, the bonding in compound 1 should be described in
2
2
(compared with that at 213 K), but is not resolved, either.
Although for complex 2 we have not seen a complete splitting
of the resonances, we propose for both complexes (2 and 3)
the same structure [see eqn. (2)]. The 1H NMR spectra of 2
and 3 show the expected resonances for all of the groups
present in the molecule and do not show any unusual features.
The observed PxN-trans-P geometry is similar to that
New J. Chem., 1999, 227È235
229

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observed with phosphoylides5 and could be due to a mini-
mization of the steric interactions.
shifted to low Ðeld compared to the free ligand, but far from
the position of the phosphorus resonance in complex 5. The
1H NMR spectrum shows the expected set of resonances and
both the 31PM1HN NMR and the 1H NMR spectra show the
presence of a single isomer. The 1H-1H NOESY spectrum of
The spectroscopic characterization of 4 reveals features
similar to those described for 2 and 3 (see Experimental). Both
the 1H and the 31PM1HN NMR spectra show the expected
resonances, and we have proposed the Me N-trans-NxP
complex 9 shows an intense NOE interaction between the H
2
6
ortho proton of the dmba ligand and the H ortho proton of
6
geometry [see eqn. (2)] by analogy with the results obtained
with phosphorus ylides.2,3,6
the pyridine fragment, indicating their mutually cis disposition
The IR spectra of 5 and 6 show similar features. The cis
geometry of these complexes can be inferred from the presence
of two absorptions in the 330 cm~1 region (see Experimental).
On the other hand, the carbonyl absorption appears as a
sharp band at 1652 cm~1 for 5 and at 1659 cm~1 for 6, shifted
to higher frequencies with respect to the free ligand, which
shows a set of several close resonances in this region (1606,
(see Scheme 1).
The IR spectrum of 10 shows interesting di†erences with
respect to those described for 5È9. The carbonyl stretching
region shows the presence of four bands (1607, 1585, 1565 and
1538 cm~1) with a pattern of absorptions very similar to that
of the free ligand. Moreover, these absorptions are found at
energies very close to those observed for the free ligand. The
1590, 1580 and 1559 cm~1). The m absorption appears at
m
absorption appears at 1350 cm~1, also very close to the
PN
PN
about 1315 cm~1, while in the free ligand it appears at 1366
corresponding absorption in the free ligand. The 31PM1HN
cm~1. As described for the IR spectrum of complex 1, these
two facts together mean that the iminic N atom is bonded to
the metal centre.
NMR spectrum of 10 shows the presence of two singlet reso-
nances, one at 42.57 ppm, attributed to the PPh ligand, and
3
the other at 23.52 ppm, assigned to the iminophosphorane
In both cases, the conclusion that the iminophosphorane
acts as an N,N-chelating ligand in 5 and 6 comes from the
analysis of their NMR spectra. The 1H NMR spectrum of
ligand and which has a very similar chemical shift to that of
the free ligand. The IR and 31PM1HN NMR data imply that in
complex 10 the iminophosphorane is coordinated only
through the pyridinic nitrogen. This coordination mode leaves
complex 6 shows the resonance attributed to the H proton of
6
the pyridinic fragment as a doublet with 195Pt satellites
the fragment wCxOwNxPPh unchanged with respect to
3
(3J \ 38 Hz) and its 31PM1HN NMR spectrum shows a
the free ligand, and this could be the responsible for the
PtH
single resonance at 34.62 ppm with 195Pt satellites (2J
\
similar pattern of absorptions in the IR spectra and also for
the similarities in the phosphorus NMR resonances, when
comparing 10 and the free ligand. For instance, in complexes
PtP
146 Hz). This last resonance is deshielded, as expected, with
respect to the free ligand, which appears at 23.89 ppm, and
conÐrms the IR observations. The close similarity between the
NMR spectra of 5 and 6 allows us to propose the same struc-
ture for these complexes, as depicted in Scheme 1.
5 and 6 the wNxPPh fragment was implicated in the
3
binding, and in complexes 7È9 the CO group also participated
in the coordination, resulting in a signiÐcant change in
the pattern of absorptions on going from the free ligand to the
coordinated ligand. The 1H NMR spectrum of 10 shows the
expected resonances for the presence of the dmba and
the iminophosphorane ligands and gives information about the
The IR spectra of 7 and 8 do not show the presence of
coordinated NCMe, in good agreement with the analytical
data, and indicate that the iminophosphorane ligand acts as a
chelate. In addition, the carbonyl absorption is found at 1537
(7) and 1538 (8) cm~1, notably shifted to lower frequencies
stereochemistry of the complex. Thus, the CH N protons and
2
with respect to the free ligand. The m absorption appears at
the methyl groups of the dmba ligand are split into doublets,
PN
about 1378 cm~1, that is, shifted 10 cm~1 to higher frequency
suggesting that the PPh ligand is located trans to the NMe
3
2
with respect to the free ligand. Both shifts suggest strongly
that the ligand is no longer acting as an N,N-chelate but that
the carbonyl oxygen is now implicated in the bonding. More
structural information can be inferred from the 31PM1HN
NMR spectra of 7 and 8. In these spectra, the resonances
attributed to the iminophosphorane moiety appear at 23.56 (7)
and 23.75 (8) ppm as singlet signals. This position lies very
close to that observed in the free ligand (23.89 ppm), suggest-
ing that now the PxN fragment is not N-coordinated to the
metal centre, which is in good agreement with the IR data.
Moreover, the resonance attributed to the iminophosphorane
ligand in the spectrum of 8 does not show Pt satellites. From
these data, it is sensible to conclude that the imino-
phosphorane ligand is coordinated through the pyridinic N
atom and the carbonyl oxygen. This coordination mode (N,O-
chelating) would result in the formation of two geometric
isomers, but only one is observed in solution; that is, the reac-
tion is stereoselective. The 1H NMR spectra of 7 and 8 show a
similar pattern of resonances for both complexes and do not
show unusual features. However, the 1H-1H NOESY experi-
ment performed on compound 8 gives structural information.
The clear NOE interaction between the signal at 8.79 ppm
unit and that the reaction occurs with retention of conÐgu-
ration at the palladium atom. Additional evidence is found in
the 1H-1H NOESY spectrum of 10, in which it is possible to
observe an intense NOE interaction between the H proton of
6
the pyridinic fragment and the NMe groups. Moreover, the
2
pyridine group should have a restricted rotation around the
PdwN bond since in the spectrum at room temperature
the CH N protons of the dmba ligand appear as diastereo-
2
topic hydrogens (AB spin system) and the methyl groups of
the NMe unit as a broad singlet that is resolved into two
2
sharp singlets on cooling. This means that the molecular plane
is no longer a plane of symmetry due to the asymmetry intro-
duced by the N-coordination of the ligand. The structure
depicted in Scheme 1 accounts for all of these observations.
The IR spectrum of 11 shows a pattern of absorptions in
the carbonyl region similar to that of the free ligand and of 10.
Moreover, we also observe the PdwCl stretch at 281 cm~1,
the characteristic absorptions of the dmba ligand, and the
PwN band at 1348 cm~1. The position of the PdwCl absorp-
tion is found at higher frequencies than in the starting dimer,
which is typical for Cl-trans-to-C arrangements.33 The NMR
spectra provide more structural information. The 1H NMR
(attributed to the H pyridinic proton) and the AB spin
spectrum shows the resonance attributed to the H of the
6
6
system of the PdwCH protons (about 3.6 and 3.9 ppm)
dmba ligand shifted strongly upÐeld, appearing now at 6.55
2
clearly indicates the cis disposition of these fragments. The
ppm. This is also observed in [PdCl(dmba)py]29 and the
reason for this shift is the anisotropic shielding of this proton
due to the cis pyridine ligand. We have established the mutual
cis disposition of the pyridine group and the aromatic ring of
the dmba ligand by the observation of a strong NOE inter-
action between the H (dmba) and the H (py) protons in the
structure depicted in Scheme 1 accounts for all of the experi-
mental Ðndings described.
The IR spectrum of 9 shows the carbonyl absorption at
1538 cm~1 and the PxN absorption at 1378 cm~1, both in
the same range as those described for 7 and 8. The 31PM1HN
NMR spectrum shows a singlet signal at 26.04 ppm, slightly
6
6
1H-1H NOESY spectrum of 11. The 31PM1HN NMR spectrum
230
New J. Chem., 1999, 227È235

View Article Online
Table 2 Selected bond lengths (A) and angles (¡) for 9
Pd(1)wC(1)
Pd(1)wN(1)
C(14)wC(15)
C(15)wN(3)
P(1)wC(22)
P(1)wC(16)
1.972(4) Pd(1)wN(2)
2.056(4) Pd(1)wO(1)
1.502(5) C(15)wO(1)
1.313(5) N(3)wP(1)
1.792(4) P(1)wC(28)
1.800(4)
2.056(3)
2.105(3)
1.266(5)
1.624(4)
1.794(4)
C(1)wPd(1)wN(2)
N(2)wPd(1)wN(1)
N(2)wPd(1)wO(1)
103.56(16) C(1)wPd(1)wN(1)
170.97(13) C(1)wPd(1)wO(1)
79.57(12) N(1)wPd(1)wO(1)
82.44(17)
173.66(14)
95.14(13)
N(2)wC(14)wC(15) 115.3(3)
C(13)wC(14)wC(15) 122.2(4)
O(1)wC(15)wN(3)
125.1(4)
O(1)wC(15)wC(14)
C(15)wO(1)wPd(1)
N(3)wP(1)wC(22)
117.2(4)
114.2(3)
105.2(2)
108.7(2)
108.2(2)
N(3)wC(15)wC(14) 117.7(4)
C(15)wN(3)wP(1)
N(3)wP(1)wC(28)
N(3)wP(1)wC(16)
118.4(3)
112.31(19) C(22)wP(1)wC(28)
113.7(2)
C(22)wP(1)wC(16)
C(28)wP(1)wC(16) 108.4(2)
Fig. 1 Thermal ellipsoid plot of the [Pd(dmba)MPh PNC(O)-2-
3
NC H N]` cation. H atoms and phenyl groups have been omitted for
5
4
clarity. Atoms are drawn at the 50% probability level.
than that observed in trans-TiCl [OC(Me)xC(H)PPh ]-
of 11 shows a singlet resonance at 23.14 ppm. With these data,
it is reasonable to propose for complex 11 a structure such as
that depicted in Scheme 1 in which the iminophosphorane is
coordinated only through the pyridinic nitrogen atom.
4
3
(THF) É THF [1.332(8) A],37 although it is still longer than the
CxO bond distances found in C-bound ylides.3,6 The
PdwO(1) bond distance [2.105(3) A] is shorter than that
found
in
the
O-bonded
ylide
[Pd(dmba)(py)-
MOC(Me)xC(H)PPh N]ClO [2.154(2) A].1
Crystal structure of complex 9
3
4
With respect to the iminophosphorane fragment, the
C(15)wN(3) bond distance is 1.313(5) A and the N(3)wP(1)
bond distance is 1.624(4) A. The PwN bond distance is
similar within experimental error to those found in other
uncoordinated stabilized iminophosphoranes [1.626(3) A for
Crystals of adequate quality for X-ray measurements were
grown by slow di†usion of n-hexane into a solution of 9 in
CH Cl at [30 ¡C. A drawing of the organometallic cationic
2
2
fragment is shown in Fig. 1, relevant crystallographic param-
eters are presented in Table 1 and selected bond distances and
angles are collected in Table 2.
Ph PxNC(O)Ph,34 1.603(5) and 1.607(3)
A
for
3
RPh PxNC(O)Ph],35 while the CwN bond distance is
The palladium atom is located in a slightly distorted square
planar environment, surrounded by the C and N atoms of the
dmba ligand and by the pyridinic N atom and the carbonyl
oxygen of the iminophosphorane ligand, with the latter
showing its N,O-chelating coordination mode.
2
similar within experimental error or slightly shorter than
those found in the same derivatives [1.353(5)
A
A
a
for
for
non-
Ph PxNC(O)Ph,34 and 1.326(7) and 1.350(4)
3
RPh PxNC(O)Ph]35 as can be expected for
2
coordinating disposition of this fragment. The comparison of
these bond distances in our complex with those found in
other coordinated and uncoordinated non-stabilized imino-
phosphoranes reveals that in our case there is extensive delo-
calization of the charge density through the PwNwCwO
system, which results in an elongation of the PxN bond and
in a shortening of the CwN bond. Thus, the C(15)wN(3)
bond distance is shorter than those found in the complexes
[PtCl(PPhMe )MCH(PPh xNC H CH -4) N] [1.396(7) A for
The structural parameters of the dmba ligand and the
pyridine fragment of the iminophosphorane ligand are similar
to those found in other complexes containing these
groups.1h4,6 The C(14)wC(15) bond distance [1.502(5) A] cor-
responds to a CwC single bond and the C(15)wO(1) bond
distance [1.266(5) A] indicates largely double bond character.
This CxO bond distance is similar within experimental error
to that found in the free stabilized iminophosphoranes
Ph PxNC(O)Ph [1.245(5) A] 34 or RPh PxNC(O)Ph
2
2
6
4
3
2
3
2
the uncoordinated fragment and 1.418(6) A for the coordi-
(R \ conjugated dioleÐnic group) [1.263(6) or 1.247(4) A],35 in
O-coordinated ylides such as [Pd(dmba)(py)-
[1.275(4) A]1 or trans-
nated one],22a trans-[PtCl MN(xPPh )C(C F )xCHCO EtN-
2
3
6 5
2
ME-NHxC(C F )C(xPPh )CO EtN]
[1.399(5)
A],22b
MOC(Me)xC(H)PPh N]ClO
6 5
3
2
3
4
[PtCl(PPhMe )MCH(PPh xNC H CH -4)(PPh NHC H -4-
[SnMe ClMOC(Me)xC(H)PPh N] (1.27 A) 36 and is shorter
2
2
6
4
3
2
6 4
4
3
3
Me)N] [1.388(10) A],18 [PtCl(PEt )MCH (PPh xNC H CH -
3
2
6
3
4)(PPh N@HC H -4-Me)-C,NN][PtCl (PEt )] [1.405(9) A],18
Table 1 Crystal data and structure reÐnement for 9
2
6
4
3
3
3
in the adducts Ph PxN(Me)BH [1.456(5) A] 20 or
3
Empirical formula
Formula weight
Temperature
Wavelength/A
C
722.43
150(1) K
0.71073
H
ClN O PPd
[Ph PxN(Me) ]` [1.425(7)È1.461(6) A] 20 or even in free
33 31
3 5
3
2
ligands such as 4,6-(CN) C F -1,3-bis(NxPPh CH PPh )
2 6 2
2
2
2
[1.356(5) and 1.358(5) A]21 and 4,6-(CN) C F -1-
2 6 2
(NxPPh CH PPh )-3-(NxPPh ) [1.351(6) and 1.364(6)
Crystal system, space group
P2 /c, Monoclinic
2
2
2
3
1
a/A
b/A
c/A
b/¡
10.5939(6)
A].21 On the other hand, the N(3)wP(1) bond distance is
1.624(4) A, which is similar within experimental error or
longer than those reported for the complexes, adducts or
free ligands described above (it should be kept in mind
that the PwN bond in phosphazenes, where the bond
order is formally 1.5, has been found to average 1.560(12) A
for 26 values reported recently).38 These phosphorusÈnitrogen
24.5212(15)
12.1504(9)
95.004(6)
3144.3(4)
4, 1.526
Volume/A
Ž
3
Z, Calcd density/Mg m~3
Absorption coefÐcient/mm~1
ReÑections collected/unique
Max. and min. transmission
Data/restraints/parameters
Goodness-of-Ðt on F2
0.772
5821/5515 [R \ 0.0314]
int
0.8364 and 0.7130
bond distances are 1.555(4) and 1.612(4)
A
for
5515/0/399
1.023
[PtCl(PPhMe )MCH(PPh xNC H CH -4) N],22a 1.643(3)
2
2
6
4
3
2
A
for trans-[PtCl MN(xPPh )C(C F )xCHCO EtNME-
6 5
1.613(6) for
Final R indices [I [ 2r(I)]
R \ 0.0435, wR \ 0.0984
2
3
2
1
2
NHxC(C F )C(xPPh )CO EtN],22b
A
Largest di†. peak and hole/e A
Ž
~3
0.589 and [0.468
6 5
3
2
[PtCl(PPhMe )MCH(PPh xNC H CH -4) (PPh NHC H -
R \ &pF o [ o F p/& o F o.
wR \ [&w(F2 [ F2)2/&w(F2)2]1@2.
2
2
6
4
3
2
6 4
2
1
o
c
o
2
o
c
o
4-Me)N],18 1.604(7)
A
for [PtCl(PEt )MCH(PPh x
Goodness-of-Ðt \ [&w(F2 [ F2)2/(n [ n
)]1@2.
3
o
c
obs
param
NC H CH -4)(PPh N@HC H -4-Me)-C,NN][PtCl (PEt )],18
6
4
3
2
6
4
3
3
New J. Chem., 1999, 227È235
231

View Article Online
1.605(3)
and
1.627(4),
1.624(4)
A
for
adducts
1, while in the absence of phosphine ligands, the pyridinic
fragment of the iminophosphorane behaves as a “freeÏ pyridine
Ph PxN(Me)BH 20 and [Ph PxN(Me) ]BF ,20 1.581(3)
3
3
3
2
4
and
1.569(4)
A
for
4,6-(CN) C F -1,3-bis-(Nx
and coordinates trans to the NMe group (11).29 In fact, this
2 6 2
2
PPh CH PPh )21 and 1.585(4), 1.578(4) for 4,6-(CN) C F -
tendency of the pyridine to coordinate trans to the NMe
2
2
2
2
2 6 2
1-(NxPPh CH PPh )-3-(NxPPh ).21 Thus, it is clear that
group could be the starting point for a reasonable explanation
2
2
2
3
the PxN bond distance is longer and the NwC one shorter,
not only when compared with other free iminophosphoranes
but also when the comparison is made with N-coordinated
iminophosphoranes. This gives proof of the extensive delocal-
ization of the electron density along the OwCwNwP system
and could be related to the low tendency of the iminic N atom
to behave as a nucleophile, as we have seen in complexes 1È4.
Finally, the environment around the phosphorus atom is
tetrahedral with PwC bond distances similar to those found
in ylide complexes.1,4h6
of the N,O-coordination in 9. The reactivity of a number of
N-donor ligands (including pyridines) towards [Pd(l-Cl)
(dmba)] Èand
other
C,N-cyclometallated
palladium
2
complexesÈhas been reported29 and in all cases these ligands
were coordinated trans to the NMe unit, showing a certain
reluctance to be coordinated trans to the ortho-metallated
2
carbon atom. Thus, the selective N(py) coordination trans to
the NMe group gives the explanation for the observation of a
2
single isomer. Now, there are two possible donor atoms to be
coordinatedÈthe carbonyl oxygen and the iminic N atomÈ
and the O-coordination resides probably on the consideration
of steric factorsÈthe large volume of the wNxPPh unit
Discussion
3
would prevent its coordination cis to the NMe group and
2
The observed reactivity of Ph PxNC(O)CH Cl towards bis-
thus O-coordination is preferred. Similar arguments can be
3
2
solvate complexes of palladium shows a close resemblance to
those described by us2,3,5,6 and others39 for the chemistry of
the same precursors with phosphorus ylides; that is, the dis-
placement of the two NCPh ligands from PdCl (NCPh)
considered for complexes 7 and 8; the reluctance of the pyri-
dine to coordinate trans to the carbon atom being responsible
for the existence of a single isomer, and the presence of a
bulky P(o-Tol) group responsible for the cis O-coord-
2
2
2
giving a bis-iminophosphorane derivative, and the replace-
ment of only one NCMe ligand from [M(C\P)(NCMe) ]ClO
or [Pd(dmba)(NCMe) ]ClO . This would seem to imply that
ination.41
In conclusion, the iminophosphorane Ph PxNC(O)-2-
2
4
3
NC H shows very interesting chemical behaviour and dis-
2
4
3
5 4
the iminophosphorane Ph PxNC(O)CH Cl behaves simi-
plays at least three di†erent coordination modes towards the
same metals (palladium and platinum). We think that this ver-
satility could permit the deliberate variation of the coordi-
nation mode as a function of the metal-containing precursor
and that this modulation could, moreover, result in di†erent
chemical properties and di†erent reactivity. Further studies on
the reactivity of these iminophosphoranes are now in
progress.
2
larly to the phosphorus ylides Ph PxC(H)COR (R \ Me, Ph,
3
OMe, NMe ) and that the nucleophilic ability of the iminic N
2
atom is similar to that of the ylidic carbon. Further reactivity
studies of this iminophosphorane with the other reported pre-
cursors shows that the iminic N atom is in fact less nucleo-
philic than the ylidic C atom and that this iminophosphorane
cannot behave as an ambidentate ligand.
For instance, the reaction between [Pt(C\P)(PPh )-
3
(NCMe)]ClO and Ph PxNC(O)CH Cl does not take place
4
3
2
even in reÑuxing THF, and the mixture of starting compounds
is recovered; the same lack of reactivity has been observed
Experimental
Safety Note: Caution! 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. See ref. 42.
in the reaction of [Pd(dmba)(PPh )(THF)]ClO
with
3
4
Ph PxNC(O)CH Cl. Towards the same precursors, the
3
2
ylides Ph PxC(H)COR react giving O-coordinated ylides.3,5
3
In the same way, Ph PxNC(O)CH Cl is not able to promote
cleavage of the halide bridging system in [Pd(l-Cl)(dmba)]
3
2
2
or in [M(l-Cl)(C\P)] (M \ Pd, Pt), whereas the ylides
General procedures
2
do, resulting in the formation of [PdCl(dmba)MC(H)CONMe -
2
(PPh )N] 6 or [MCl(C\P)MC(H)COR(PPh )N] 5,6 (M \ Pd,
Solvents were dried and distilled by standard methods prior
to use. Elemental analyses of C, H, N were carried out on a
PerkinÈElmer 2400 microanalyser. Infrared spectra (4000È200
cm~1) were recorded on a PerkinÈElmer 883 infrared spectro-
photometer in Nujol mulls between polyethylene sheets. 1H
(300.13 MHz) and 31PM1HN (121.49 MHz) NMR spectra were
recorded from CDCl , CD Cl or (CD ) CO solutions at
3
3
Pt). In conclusion, the N atom of the resonance-stabilized
iminophosphorane Ph Px NC(O)CH Cl is a poor nucleo-
3
2
phile, even when compared with its homologous a-stabilized
phosphoylides, probably due to the negative inÑuence of the
CxO group on the N(imine) donor ability. However, under
certain conditions it is able to displace weakly coordinated
ligands, giving the corresponding iminophosphorane deriv-
atives.
3
2
2
3 2
room temperature (unless otherwise stated) on a Bruker
ARX-300 spectrometer; 1H NMR spectra were referenced
using the solvent signal as an internal standard and 31PM1HN
NMR spectra were externally referenced to H PO (85%).
With respect to the di†erent coordination modes observed
in complexes 5È11, there are two interesting questions to be
answered. First, what drives the adoption of the N,N-chelat-
ing, the N,O-chelating or the N(py)-unidentate mode towards
a given substrate? Second, why is a single isomer observed in
all cases?
3
4
The two dimensional 1H-1H NOESY experiments for com-
plexes 8È11 were performed at a measuring frequency of
300.13 MHz. The data were acquired in a phase sensitive
mode into a 512 ] 1024 matrix, and then transformed into
1024 ] 1024 points using a sine window in each dimension.
The mixing time was in all cases 400 ms. Mass spectra
(positive ion FAB) were recorded on a VG Autospec spectro-
meter from CH Cl solutions. The starting products
It seems that, in this ligand, the N(py) is more strongly
coordinated to Pd or Pt than N(imine), and this more than
O(carbonyl). Thus, one can expect that the preferred coordi-
nation mode for Ph PxNC(O)-2-NC H would be the N,N-
3
5
4
2 2
chelating mode, and this is, in fact, the observed mode in 5
and 6. On the other hand, the higher tendency of the N(py)
atom to coordinate could explain the binding observed in
MCl (NCPh) (M \ Pd, Pt),25 [M(C\P)(NCMe) ](ClO )
2
2
2
4
(M \ Pd,26 Pt 27), [Pd(dmba)(NCMe) ](ClO ),28 [Pt(C\P)-
2
4
(PPh )(NCMe)](ClO ),5
[Pd(dmba)(PPh )(THF)]ClO ,29
3
4
3
4
complexes 10 and 11. The known reluctance40 of the PPh
ligand to be trans to the ortho-metallated carbon atom of the
dmba ligand explains the geometry proposed for 10 in Scheme
[M(l-Cl)(C\P)] (M \ Pd,30 Pt 27), [Pd(l-Cl)(dmba)] 31 and
3
2
2
Ph PxNC(O)R (R \ CH Cl, 2-py)24 were prepared accord-
3 2
ing to published methods.
232
New J. Chem., 1999, 227È235

View Article Online
Syntheses
Obtained: 0.128 g (44% yield). The acetone solution was
evaporated to dryness and the residue treated with Et O (25
trans-PdCl {N(xPPh )C(O)CH Cl} , 1. To a solution of
2
2
2
3
2
2
mL), giving a second fraction of 5. Obtained: 0.107 g (37%
PdCl (NCPh) (0.200 g, 0.521 mmol) in 20 mL of acetone the
2
yield, total yield 81%). Anal. calcd for C
H
Cl N OPPd
iminophosphorane Ph PxNC(O)CH Cl (0.369 g, 1.04 mmol)
24 19
2 2
3
2
(559.71 g mol~1): C, 51.50; H, 3.42; N, 5.00. Found: C, 50.99;
was added. In a few seconds an orange precipitate of 1
H, 3.16; N, 4.81. IR (m, cm~1): 1652 (m ), 1316 (m ), 350, 328
appeared, which was stirred at room temperature for 5 min,
CO
PN
(m ). 1H NMR (CD Cl ): d 9.20 (d, 1H, H , NC H ,
Ðltered, washed with acetone (10 mL) and Et O (25 mL) and
air-dried. Obtained: 0.329 g (71% yield). Anal. calcd for
PdCl
3J \ 5.7 Hz), 8.11È8.00 (m, 7H, Ph ] NC H ), 7.80 (d, 1H,
HH
H , NC H , 3J \ 6.6 Hz), 7.73È7.68 (m, 3H, Ph), 7.63È7.57
HH
2
2
6
5 4
2
5
4
C
H
Cl N O P Pd (884.88 g mol~1): C, 54.29; H, 3.87; N,
3
5 4
40 34
4 2 2 2
(m, 7H, Ph ] NC H ). 31PM1HN NMR (CD Cl ): d 33.72 (s,
3.16. Found: C, 54.36; H, 3.70; N, 3.19. IR (m, cm~1): 1643
5
4
2 2
wNPPh ).
(m ), 1325 (m ), 319 (m ). 1H NMR (CD Cl ): d 7.88È7.58
3
CO
PN
PdCl
2 2
(m, 15H, Ph), 4.25 (s, 2H, CH ). 31PM1HN NMR (CD Cl ):
2
2 2
cis-Cl Pt{N(xPPh )C(O)-2-NC H }, 6. Finely ground
d 37.50 (s, wNPPh ).
2
3
5 4
3
PtCl (0.300 g, 1.13 mmol) was suspended in 35 mL of a
2
mixture of CH Cl Èacetone (9 : 1) and the iminophosphorane
Ph PxNC(O)-2-NC H (0.431 g, 1.13 mmol) was added. The
resulting mixture was reÑuxed for 48 h. During this time, most
of the platinum salt dissolved and gave an orange-brown sus-
pension. Once cooled this suspension was Ðltered over Celite
and the resulting yellow-orange solution was evaporated to
[Pd(C\P){N(xPPh )C(O)CH Cl}(NCMe)](ClO ), 2. To
a solution of [Pd(C\P)(NCMe) ](ClO ) (0.200 g, 0.338 mmol)
in 20 mL of CH Cl the iminophosphorane Ph Px
NC(O)CH Cl (0.120 g, 0.338 mmol) was added, and the
resulting solution was stirred at room temperature for 30 min.
The solvent was then evaporated to dryness and the residue
was washed with Et O (25 mL) giving 2 as a white solid,
which was collected and air-dried. Obtained: 0.155 g (51%
2
2
3
2
4
3
5 4
2
4
2
2
3
2
dryness. The residue was treated with Et O (50 mL), giving 6
2
2
as a deep-yellow solid, which was Ðltered, washed with addi-
tional Et O (20 mL) and air-dried. Obtained: 0.333 g (45%
yield). Anal. calcd for C
C, 57.13; H, 4.46; N, 3.10. Found: C, 56.63; H, 4.41; N, 2.92.
H
Cl N O P Pd (904.06 g mol~1):
2
43 40
2 2
5 2
yield). Anal. calcd for C
H
Cl N OPPt (648.40 g mol~1): C,
24 19
2 2
44.46; H, 2.95; N, 4.32. Found: C, 44.31; H, 2.96; N, 4.13. IR
IR (m, cm~1): 2306, 2278 (m
), 1647 (m ), 1321 (m ). Mass
NCMe CO PN
(m, cm~1): 1659 (m ), 1311 (m ), 346, 310 (m ). 1H NMR
spectrum (FAB]) [m/z, (%)]: 762 (15%) [M [ ClO
CO
PN
PtCl
4
(CD Cl ): d 9.52 (d, 1H, H , NC H , 3J \ 5 Hz, 3J \ 38
[ NCMe]`. 1H NMR (CDCl , 213 K): d 7.73È6.38 (m, 27H,
2
2
6
5
4
HH
PtH
3
Hz), 8.11È7.17 (m, 18H, Ph ] NC H ). 31PM1HN NMR
(CD Cl ): d 34.62 (s, wNPPh , 2J \ 146 Hz).
PtP
Ph ] o-MeC H ), 4.93 (s, 2H, CH Cl), 3.24, 2.88 (AB spin
5
4
6
4
2
system, 2H, CH wPd, 2J \ 14.1 Hz), 2.71, 2.10, 1.94 (3s,
2
2
3
2
HH
9H, 2 o-MeC H ] NCMe). 31PM1HN NMR (CDCl , 213 K):
6
4
3
[Pd(C\P){N(xPPh )C(O)-2-NC H } ](ClO ), 7. Com-
d 38.01, 37.56 (2s, wNPPh ] C\P).
3
5
4
4
3
plex
7
was synthesized in the same way as 2:
[Pd(C\P)(NCMe) ](ClO ) (0.200 g, 0.338 mmol) was reacted
[Pt(C\P){N(xPPh )C(O)CH Cl}(NCMe)](ClO ),
3.
was synthesized in the same way as 2:
[Pt(C\P)(NCMe) ](ClO ) (0.200 g, 0.294 mmol) was reacted
2
4
3
2
4
with Ph PxNC(O)-2-NC H (0.129 g, 0.338 mmol) in
Complex
3
3
5 4
CH Cl to give 7 as a white solid. Obtained: 0.231 g (77%
2
2
2
4
yield). Anal. calcd for C
H
ClN O P Pd (891.62 g mol~1):
in CH Cl with Ph PxNC(O)CH Cl (0.104 g, 0.294 mmol) to
45 39
2 5 2
2
2
3
2
C, 60.62; H, 4.41; N, 3.14. Found: C, 59.93; H, 4.19; N, 2.97.
give 3 as a white solid. Obtained: 0.212 g (73% yield). Anal.
IR (m, cm~1): 1537 (m ), 1379 (m ). Mass spectrum (FAB])
calcd for C
H
Cl N O P Pt (992.75 g mol~1): C, 52.02; H,
CO
PN
43 40
2 2
5 2
[m/z, (%)]: 791 (75%) [M [ ClO ]`. 1H NMR (CDCl , 213
4.06; N, 2.82. Found: C, 51.97; H, 3.73; N, 2.62. IR (m, cm~1):
2310, 2282 (m
(FAB]) [m/z, (%)]: 852 (40%) [M [ ClO [ NCMe]`. 1H
NMR (CDCl , 213 K):
4
3
K): d 8.78 (d, 1H, H , NC H , 3J \ 8 Hz), 8.57 (d, 1H, H ,
HH
NC H , 3J \ 4 Hz), 8.32 (t, 1H, H , NC H , 3J \ 8 Hz),
HH HH
7.92 (t, 1H, H , NC H , 3J \ 4 Hz), 7.68È6.69 (m, 27H,
HH
Ph ] o-MeC H ), 3.76, 3.63 (AB spin system, 2H, CH wPd,
), 1651 (m ), 1318 (m ). Mass spectrum
6
5
4
3
NCMe
CO
PN
5
4
5
5 4
4
d
7.82È6.31 (m, 27H, Ph ] o-
4
4
5 4
3
MeC H ), 4.92 (s, 2H, CH Cl), 3.09, 3.01 (AB spin system, 2H,
6
2
6
4
2
2J \ 13 Hz), 2.36, 1.58 (2s, 6H, 2 o-MeC H ). 31PM1HN
HH
NMR (CDCl , 213 K): d 32.73 (s, C\P), 23.56 (s, wNPPh ).
CH wPt, 2J \ 16.2 Hz), 2.72, 2.19, 1.87 (3s, 9H, 2 o-
HH
MeC H ] NCMe). 31PM1HN NMR (CDCl , 213 K): d 40.30
6
4
2
3
3
6
4
3
(d, 1P, wNPPh , 2J \ 62.2 Hz, 3J \ 5.9 Hz), 16.41 (br s,
3
PtP
PP
[Pt(C\P){N(xPPh )C(O)-2-NC H } ](ClO ), 8. Com-
C\P, 1J \ 4334 Hz).
3
5
4
4
PtP
plex
8
was synthesized in the same way as 2:
[Pt(C\P)(NCMe) ](ClO ) (0.100 g, 0.147 mmol) was reacted
[Pd(dmba){N(xPPh )C(O)CH Cl}(NCMe)](ClO ),
4.
was synthesized in the same way as 2:
[Pd(dmba)(NCMe) ](ClO ) (0.200 g, 0.474 mmol) was reacted
2
4
3
2
4
with Ph PxNC(O)-2-NC H (0.056 g, 0.15 mmol) in CH Cl
Complex
4
3
5
4
2 2
to give 8 as a white solid. Obtained: 0.109 g (76% yield). Anal.
2
3
4
calcd for C
H
ClN O P Pt (980.31 g mol~1): C, 55.13; H,
in CH Cl with Ph PxNC(O)CH Cl (0.168 g, 0.474 mmol) to
45 39
2 5 2
2
2
2
4.01; N, 2.86. Found: C, 55.17; H, 3.68; N, 2.88. IR (m, cm~1):
give 4 as a white solid. Obtained: 0.236 g (68% yield). Anal.
1538 (m ), 1378 (m ). Mass spectrum (FAB]) [m/z, (%)]: 880
calcd for C
H
Cl N O PPd (734.89 g mol~1): C, 50.66; H,
CO
PN
4
31 32
2 3 5
(100%) [M [ ClO ]`. 1H NMR (CDCl , 213 K): d 8.79 (d,
4.39; N, 5.72. Found: C, 49.99; H, 4.25; N, 5.29. IR (m, cm~1):
3
1H, H , NC H , 3J \ 7.5 Hz), 8.46 (t, 1H, H , NC H ,
HH
3J \ 8 Hz), 7.98 (m, 2H, H ] H , NC H ), 7.68È6.65 (m,
HH
27H, Ph ] o-MeC H ), 3.91, 3.58 (AB spin system, 2H,
2329 (m
), 1636 (m ), 1332 (m ). Mass spectrum (FAB])
6
5
4
5
5 4
NCMe
CO
PN
[m/z, (%)]: 595 (45%) [M [ ClO [ NCMe]`. 1H NMR
4
3
5 4
4
(CDCl ): d 7.76È7.69 (m, 6H, Ph), 7.67È7.61 (m, 3H, Ph), 7.53È
6
4
3
CH wPt, 2J \ 15 Hz), 2.39, 1.60 (2s, 6H, 2 o-MeC H ).
7.47 (m, 6H, Ph), 6.94 (td, 1H, C H , 3J \ 7.3 Hz, 4J
\
2
HH
6 4
6
4
HH
HH
31PM1HN NMR (CDCl , 213 K): d 23.75 (s, wNPPh ), 14.63
1.2 Hz), 6.90È6.74 (m, 3H, C H ), 5.45, 5.39 (AB spin system,
3
(s, C\P, 1J \ 4251 Hz).
PtP
3
6
4
2H, CH Cl, 2J \ 15.7 Hz), 3.69, 3.32 (AB spin system, 2H,
HH
CH N, 2J \ 13.7 Hz), 2.70, 2.31 (2s, 6H, NMe ), 1.93 (s, 3H,
HH
NCMe). 31PM1HN NMR (CDCl ): d 38.18 (wNPPh ).
2
2
2
[Pd(dmba){N(xPPh )C(O)-2-NC H } ](ClO ), 9. Com-
3
5
4
4
3
3
plex
9
was synthesized in the same way as 2:
cis-Cl Pd{N(xPPh )C(O)-2-NC H }, 5. To a solution of
[Pd(dmba)(NCMe) ](ClO ) (0.100 g, 0.237 mmol) was reacted
2
3
5
4
2
3
4
[PdCl (NCPh) ] (0.200 g, 0.521 mmol) in 20 mL of acetone
in CH Cl with Ph PxNC(O)-2-NC H (0.091 g, 0.24 mmol)
2
2
2
2
5 4
the iminophosphorane Ph PxNC(O)-2-NC H (0.199 g,
to give 9 as a white solid. Obtained: 0.148 g (87% yield). Anal.
3
5 4
0.521 mmol) was added. After a few minutes, an orange solid
precipitated, which was collected, washed with additional
calcd for C
H
ClN O PPd (722.43 g mol~1): C, 54.86; H,
33 31
3 5
4.32; N, 5.81. Found: C, 54.62; H, 4.21; N, 5.71. IR (m, cm~1):
acetone (10 mL), Et O (25 mL), air-dried and identiÐed as 5.
1538 (m ), 1378 (m ). Mass spectrum (FAB]) [m/z, (%)]: 622
2
CO
PN
New J. Chem., 1999, 227È235
233

View Article Online
(100%) [M [ ClO ]`. 1H NMR (CDCl ): d 8.69 (d, 1H, H ,
aromatic carbon atoms, and of the CH and CH groups were
constrained to idealized geometries, and the isotropic dis-
placement parameter of each of these hydrogen atoms was set
to a value of 1.2 times the equivalent isotropic displacement
parameter of its parent carbon atom. The hydrogen atoms of
4
3
3
2
NC H , 3J \ 5 Hz), 8.64 (dd, 1H, H , NC H , 3J \ 8
HH HH
Hz, 4J \ 1.2 Hz), 8.28 (td, 1H, H , NC H , 4J \ 1.4 Hz),
HH HH
7.77È7.68 (m, 10H, Ph ] NC H ), 7.63È7.59 (m, 6H, Ph), 7.07È
5
4
6
5 4
5
5 4
5
4
6.74 (m, 4H, C H ), 3.95 (s, 2H, CH N), 2.41 (s, 6H, NMe ).
31PM1HN NMR (CDCl ): d 26.04 (wNPPh ).
6
4
2
2
the CH groups were also constrained to idealized geometries
3
3
3
and the isotropic displacement parameter of each of these
[Pd(dmba)(PPh ){N(xPPh )C(O)-2-NC H } ](ClO ), 10.
hydrogen atoms was set to a value of 1.5 times the equivalent
isotropic displacement parameter of its parent carbon atom.
The data-to-parameter ratio in the Ðnal reÐnement was 13.8.
3
3
5
4
4
To a THF solution (25 mL) of PdCl(dmba)(PPh ) (0.200 g,
3
0.371 mmol), AgClO (0.077 g, 0.37 mmol) was added. The
4
resulting suspension was stirred at room temperature in the
The structure was reÐned on F 2, and all reÑections were used
0
dark for 30 min, then Ðltered. To the freshly obtained solution
of [Pd(dmba)(PPh )(THF)](ClO ) the iminophosphorane
in the least squares calculation.45 The residuals and other per-
tinent parameters are summarized in Table 1. Crystallo-
graphic calculations were done on a Local Area VAXCluster
(VAX/VMS V5.5-2). Data reduction was done by the program
XCAD4B.46
3
4
Ph PxNC(O)-2-NC H (0.131 g, 0.371 mmol) was added,
3
5 4
and the resulting pale yellow solution was stirred at room
temperature for 30 min. The solvent was then evaporated to
half-volume, resulting in the precipitation of 10, which was
Ðltered, washed with Et O (25 mL) and air-dried. Obtained:
0.309 g (84% yield). Anal. calcd for C
CCDC reference number 440/082. See http://www.rsc.org/
suppdata/nj/1999/227/ for crystallographic Ðles in .cif format.
2
H
ClN O P Pd
51 46
3 5 2
(984.75 g mol~1): C, 62.20; H, 4.71; N, 4.27. Found: C, 61.97;
H, 5.01; N, 4.34. IR (m, cm~1): 1607, 1585, 1565, 1538 (m ),
Acknowledgements
CO
1350 (m ). Mass spectrum (FAB]) [m/z, (%)]: 884 (10%)
PN
We would like to thank the Direccion General de Ensenanza
Superior (Spain) for Ðnancial support (Projects PB95-0792
and PB95-0003-C02-01) and Prof. J. Fornies for his invaluable
logistical support.
[M [ ClO ]`, 622 (100%) [M [ ClO [ PPh ]`. 1H NMR
4
4
3
(CDCl , 213 K): d 8.80 (d, 1H, H , NC H , 3J \ 5 Hz),
3
3
5
4
HH
8.34 (d, 1H, H , NC H , 3J \ 8 Hz), 7.93È7.40 (m, 17H,
HH
Ph ] NC H ), 6.98 (d, 1H, C H , 3J \ 7.2 Hz), 6.82 (t, 1H,
HH
C H , 3J \ 7.8 Hz), 6.35 (t, 1H, C H , 3J \ 7.8 Hz), 6.27
HH HH
(t, 1H, C H , 3J + 4J \ 6 Hz), 4.16, 3.53 (AB spin system,
HH PH
2H, CH N, 2J \ 13.2 Hz), 2.65, 1.88 (2s, 6H, NMe ).
HH
6
5 4
5
4
6 4
6
4
6 4
6
4
Notes and references
1 L. R. Falvello, S. Fernandez, R. Navarro and E. P. Urriolabeitia,
Inorg. Chem., 1996, 35, 3064.
2 L. R. Falvello, S. Fernandez, R. Navarro and E. P. Urriolabeitia,
Inorg. Chem., 1997, 36, 1136 and references therein.
3 L. R. Falvello, S. Fernandez, R. Navarro, I. Pascual and E. P.
Urriolabeitia, J. Chem. Soc., Dalton T rans., 1997, 763 and refer-
ences therein.
4 L. R. Falvello, S. Fernandez, R. Navarro and E. P. Urriolabeitia,
New J. Chem., 1997, 21, 909.
5 S. Fernandez, M. M. Garc•a, R. Navarro and E. P. Urriolabeitia,
J. Organomet. Chem., 1998, 561, 67.
6 I. C. Barco, L. R. Falvello, S. Fernandez, R. Navarro and E. P.
Urriolabeitia, J. Chem. Soc., Dalton T rans., 1998, 1699.
7 R. G. Pearson, Inorg. Chem., 1973, 12, 712.
8 J. A. Davies and F. R. Hartley, Chem. Rev., 1981, 81, 79.
9 (a) A. W. Johnson, W. C. Kaska, K. A. O. Starzewski and D. A.
Dixon, Y lides and Imines of Phosphorus, Wiley, New York, 1993,
ch. 13 and references given therein. (b) J. Vicente, M. T. Chicote, J.
2
2
31PM1HN NMR (CDCl , 213K): d 42.57 (s, PdwPPh ), 23.52
3
3
(s, wNPPh ).
3
[Pd(dmba)Cl{N(xPPh )C(O)-2-NC H } ], 11. To a solu-
3
5 4
tion of [Pd(l-Cl)(dmba)] (0.100 g, 0.181 mmol) in CH Cl (25
2
2 2
mL) the iminophosphorane Ph PxNC(O)-2-NC H (0.138 g,
0.362 mmol) was added, and the resulting solution was stirred
at room temperature for 1 h. The solvent was then evaporated
3
5 4
to dryness and the oily residue treated with Et O (30 mL),
2
giving 11 as a pale yellow solid. Obtained: 0.198 g (83% yield).
Anal. calcd for C
H
ClN OPPd (658.46 g mol~1): C, 60.19;
33 31
3
H, 4.74; N, 6.38. Found: C, 59.78; H, 4.45; N, 6.24. IR (m,
cm~1): 1604, 1588, 1562, 1538 (m ), 1348 (m ), 281 (m ). 1H
CO
PN
PdCl
NMR (CDCl ): d 8.86 (d, 1H, H , NC H , 3J \ 5 Hz), 8.35
3
3
5
4
HH
(d, 1H, H , NC H , 3J \ 7.5 Hz), 8.11 (t, 1H, H , NC H ,
HH
3J \ 7.5 Hz), 7.81È7.68 (m, 7H, Ph ] NC H ), 7.63È7.55 (m,
HH
3H, Ph), 7.52È7.42 (m, 6H, Ph), 6.98È6.76 (m, 3H, C H ), 6.55
6
5
4
5
5 4
5
4
Fernandez-Baeza, F. J. Lahoz and J. A. Lo
30, 3617 and references given therein.
 pez, Inorg. Chem., 1991,
6
4
(d, 1H, H , C H , 3J \ 6.6 Hz), 3.74 (s, 2H, CH N), 2.44 (s,
10 K. A. O. Starzewski and H. T. Dieck, Inorg. Chem., 1979, 18, 3307.
11 K. V. Katti and R. G. Cavell, Inorg. Chem.. 1989, 28, 413.
12 K. V. Katti and R. G. Cavell, Organometallics, 1989, 8, 2147.
13 K. V. Katti, R. J. Batchelor, F. W. B. Einstein and R. G. Cavell,
Inorg. Chem., 1990, 29, 808.
6
2
6
4
HH
2
6H, NMe ). 31PM1HN NMR (CDCl ): d 23.14 (wNPPh ).
3
3
Crystallography
X-ray data collection. A pale yellow crystal of 9 was
mounted on a quartz Ðbre and covered with epoxy. Normal
procedures were used for the determination of the unit cell
constants and for the measurement of intensity data. After
preliminary indexing and transformation of the cell to a con-
ventional setting, axial photographs were taken of the a, b, c
and [1 1 1] axes to verify the lattice dimensions and Laue
group. Unit cell dimensions were determined from 25 centred
reÑections in the range 21.9 O 2h O 33.7¡. For intensity data
collection, pure x-scans were used with *x\1.15]0.35 tan h.
Three monitor reÑections were measured after every 30 min of
beam time, and the orientation of the crystal was checked
after every 500 intensity measurements. Absorption
corrections43 were based on azimuthal scans of 15 reÑections.
The reÑections used for this purpose had their bisecting posi-
tion v values distributed in the range of 5È90¡.
14 P. Imho†, R. van Asselt, C. J. Elsevier, M. C. Zoutberg and C. H.
Stam, Inorg. Chim. Acta, 1991, 184, 73.
15 K. V. Katti and R. G. Cavell, Organometallics, 1991, 10, 539.
16 K. V. Katti, B. D. Santarsiero, A. A. Pinkerton and R. G. Cavell,
Inorg. Chem., 1993, 32, 5919.
17 M. S. Balakrishna, B. D. Santarsiero and R. C. Cavell, Inorg.
Chem., 1994, 33, 3079.
18 M. W. Avis, K. Vrieze, H. Kooijman, N. Veldman, A. Spek and
C. J. Elsevier, Inorg. Chem., 1995, 34, 4092.
19 A. Mahieu, A. Igau, J. Jaud and J. P. Majoral, Organometallics,
1995, 14, 944.
20 W. K. Holley, G. E. Ryschkewitsch, A. E. Koziol and G. J.
Palenik, Inorg. Chim. Acta, 1995, 239, 171.
21 J. Li, R. McDonald and R. G. Cavell, Organometallics, 1996, 15,
1033.
22 (a) M. W. Avis, K. Vrieze, J. M. Ernsting, C. J. Elsevier, N.
Veldman, A. Spek, K. V. Katti and C. L. Barnes, Organometallics,
1996, 15, 2376. (b) J. Vicente, M. T. Chicote, M. A. Beswick and
M. C. Ram•rez de Arellano, Inorg. Chem., 1996, 35, 6592. For other
new iminophosphorane complexes, see: (c) P. Molina, A. Arques,
A. Garc•a and M. C. Ram•rez de Arellano, T etrahedron L ett.,
1997, 38, 7613. (d) J. Vicente, A. Arcas, D. Bautista and M. C.
Ram•rez de Arellano, Organometallics, 1998, 17, 1564.
Solution and reÐnement. The structure was solved and
developed by Patterson and Fourier methods using SHELX-
86.44 All non-hydrogen atoms were reÐned with anisotropic
displacement parameters. The hydrogen atoms bonded to the
234
New J. Chem., 1999, 227È235

View Article Online
23 R.-Z. Ku, D.-Y. Chen, G.-H. Lee, S.-M. Peng and S.-T. Liu,
Angew. Chem., Int. Ed. Engl., 1997, 36, 2631.
36 J. Buckle, P. G. Harrison, T. J. King and J. A. Richards, J. Chem.
Soc., Chem. Comm., 1972, 1104.
37 J. A. Albanese, D. A. Staley, A. L. Rheingold and J. L. Burmeister,
Inorg. Chem., 1990, 29, 2209.
38 H. R. Allock, A. A. Dembek, M. N. Mang, G. H. Riding, M.
Parzev and K. B. Visscher, Inorg. Chem., 1992, 31, 2734.
39 See, for instance: (a) E. T. Weleski, J. L. Silver, M. D. Jansson and
J. L. Burmeister, J. Organomet. Chem., 1975, 102, 365. (b) J.
Vicente, M. T. Chicote and J. Fernandez-Baeza, J. Organomet.
Chem., 1989, 364, 407 and references cited in ref. 3.
40 J. Vicente, A. Arcas, D. Bautista and P. G. Jones, Organometallics,
1997, 16, 2127 and references therein.
24 S. Bittner, Y. Assaf, P. Krief, M. Pomerantz, B. T. Ziemnicka and
C. G. Smith, J. Org. Chem., 1985, 50, 1712.
25 G. K. Anderson and M. Lin, Inorg. Synth., 1990, 28, 60.
26 The complex [Pd(C\P)(NCMe) ]ClO was prepared in a way
2
4
similar to that described in ref. 27 for [Pt(C\P)(NCMe) ]ClO ,
2
4
with the exception that the reaction was performed starting from
[Pd(l-Cl)(C\P)] (see ref. 30) under nitrogen atmosphere in dry
2
NCMe: P. Villarroya, Ph.D. Thesis, University of Zaragoza, 1998.
27 J. Fornies, A. Mart•n, R. Navarro, V. Sicilia and P. Villarroya,
Organometallics, 1996, 15, 1826.
28 J. Fornies, R. Navarro and V. Sicilia, Polyhedron, 1988, 7, 2659.
29 A. J. Deeming, I. P. Rothwell, M. B. Hursthouse and L. New,
J. Chem. Soc., Dalton T rans., 1978, 1490.
41 We thank one of the referees for stimulating suggestions and
helpful discussions.
42 W. C. Wolsey, J. Chem. Educ., 1973, 50, A335.
30 (a) W. A. Herrmann, C. Brossmer, K. Ofele, C.-P. Reisinger, T.
Priermeier, M. Beller and H. Fischer, Angew. Chem., Int. Ed. Engl.
1995, 34, 1844. (b) L. R. Falvello, J. Fornies, A. Mart•n, R.
Navarro, V. Sicilia and P. Villarroya, Inorg. Chem., 1997, 36, 6166.
31 A. C. Cope and E. C. Friedrich, J. Am. Chem. Soc. 1968, 90, 909.
32 H. Alper, J. Organomet. Chem. 1977, 127, 385.
33 (a) E. L. Weinberg, B. K. Hunter and M. C. Baird, J. Organomet.
Chem., 1982, 240, 95. (b) B. Crociani, T. Boschi, R. Pietropaolo and
U. Belluco, J. Chem. Soc. (A), 1970, 531.
43 Absorption corrections and molecular graphics were done using
the commercial package SHELXTL-PLUS, Release 4.21/V: (
1990, Siemens Analytical X-ray Instruments, Inc., Madison,
Wisconsin.
44 G. M. Sheldrick, Acta Crystallogr., Sect. A, 1990, 46, 467.
45 G. M. Sheldrick, SHEL XL -97: FORT RAN Program for the
ReÐnement of Crystal Structures from Di†raction Data, Gottingen
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