Synthesis and characterization of neutral and anionic carbonyl derivatives of palladium(II)

Article abstract of DOI:10.1039/c0dt00014k

The action of CO on the solvento-complexes cis-[PdR₂(thf) ₂] [R = C₆F₅ (1), C₆Cl₅ (2)] at low temperature gives cis-[PdR₂(CO)₂] [R = C ₆F₅ (3), C₆Cl₅ (4)] in good yield by simple replacement of the highly labile thf molecules. These are rare cases of Pd^II dicarbonyl compounds, whose characterization relies on spectroscopic and analytic data. The crystal structure of the square-planar platinum homologue cis-[Pt(C₆Cl₅)₂(CO) ₂] is also presented. CO can split the double bridging-system in the dinuclear species [{PdR₂}₂(μ-X)₂] ^2- giving the homologous series of anionic monocarbonyl Pd ^II derivatives with formula [cis-PdR₂X(CO)]^- (5-10: R = C₆F₅, C₆Cl₅; X = Cl, Br, I), which were isolated (except for the R = C₆F₅ and X = I) and suitably characterized. Characterization includes the crystal and molecular structure of [PPh₃Me][cis-Pd(C₆F ₅)₂Br(CO)] (6′). The anionic species [NBu ₄][cis-Pd(C₆F₅)₂Cl(CO)] (5) reacts with neutral cis-[Pd(C₆F₅)₂(CO)₂] (3) under CO extrusion, affording the dinuclear derivative [NBu ₄][{Pd(C₆F₅)₂(CO)} ₂(μ-Cl)] (11), which contains a single unsupported halide bridge (X-ray diffraction). Complex 11 can be considered as modelling a possible intermediate step in intermolecular CO substitution reactions that are easily undergone by Pd^II halo carbonyl species.

Full text of DOI:10.1039/c0dt00014k

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PAPER
www.rsc.org/dalton | Dalton Transactions
Synthesis and characterization of neutral and anionic carbonyl derivatives of
palladium(II)†‡
Irene Ara, Juan Fornie´s,* Antonio Mart´ın, L. Francisco Mart´ın, Babil Menjo´n and Helvia Miedes
Received 22nd February 2010, Accepted 17th May 2010
First published as an Advance Article on the web 30th June 2010
DOI: 10.1039/c0dt00014k
The action of CO on the solvento-complexes cis-[PdR2(thf)2] [R = C6F5 (1), C6Cl5 (2)] at low
temperature gives cis-[PdR2(CO)2] [R = C6F5 (3), C6Cl5 (4)] in good yield by simple replacement of the
highly labile thf molecules. These are rare cases of PdII dicarbonyl compounds, whose characterization
relies on spectroscopic and analytic data. The crystal structure of the square-planar platinum
homologue cis-[Pt(C6Cl5)2(CO)2] is also presented. CO can split the double bridging-system in the
dinuclear species [{PdR2}2(m-X)2]2- giving the homologous series of anionic monocarbonyl PdII
derivatives with formula [cis-PdR2X(CO)]- (5–10: R = C6F5, C6Cl5; X = Cl, Br, I), which were isolated
(except for the R = C6F5 and X = I) and suitably characterized. Characterization includes the crystal
and molecular structure of [PPh3Me][cis-Pd(C6F5)2Br(CO)] (6¢). The anionic species
[NBu4][cis-Pd(C6F5)2Cl(CO)] (5) reacts with neutral cis-[Pd(C6F5)2(CO)2] (3) under CO extrusion,
affording the dinuclear derivative [NBu4][{Pd(C6F5)2(CO)}2(m-Cl)] (11), which contains a single
unsupported halide bridge (X-ray diffraction). Complex 11 can be considered as modelling a possible
intermediate step in intermolecular CO substitution reactions that are easily undergone by PdII halo
carbonyl species.
[Pd(CO)4][Sb2F11]2 was only possible in superacidic media and in
Introduction
the absence of even moderate nucleophiles.
The synthesis and characterization of palladium(II) carbonyl
The low nucleophilicity of the metal-bound C6F5 and C6Cl5
derivatives as well as the study of their physical and chemical
groups (R) also allowed us to isolate the dicarbonyl com-
pounds cis-[PdR2(CO)2], as has been briefly communicated.9
properties have attracted the attention of chemical researchers for
a very long time.1 Shortly after the preparation of the first metal
The same principle was applied in the synthesis of a series
carbonyl derivatives, cis-[PtCl2(CO)2] and [{PtCl(CO)}2(m-Cl)2] by
of all-organometallic analogues of Zeise’s salt with formula
Schu¨tzenberger in the late 19th century,2 an extension to the lighter
2
[NBu4][M(C6F5)3(h -C2H4)] for all three Group 10 metals (M =
Ni, Pd, Pt).10 The recent synthesis of a family of square-
planar nickel(II) carbonyl compounds with formula [NBu4][cis-
Ni(C6F5)2X(CO)] (X = Cl, Br, I)11 has prompted us to complete
the series of Group 10 metal carbonyl species by preparing the
corresponding derivatives of PdII. In this paper we report on
the synthesis and characterization of a series of neutral and
anionic carbonyl derivatives of palladium(II) containing ligands
of moderate and/or reduced nucleophilic character.
element Pd was naturally attempted. Early reports on the synthesis
of the analogous Pd carbonyl compounds,3 however, were later
found to be erroneous.4 One of the factors causing confusion
in the identification of the resulting derivatives was the ease
with which PdII compounds are reduced by CO, especially in the
presence of moisture.5 The dinuclear compound [{PdCl(CO)}2(m-
Cl)2] was eventually obtained,6 but, to the best of our knowledge,
the mononuclear compound cis-[PdCl2(CO)2] has still not been
isolated. The main reason for this failure is the expected high
lability of the Pd–CO bond in the latter compound, which would
readily undergo substitution reactions. Since metal-coordinated
halo ligands, M–X, still show a considerable nucleophilic charac-
ter, revealed, for instance, in their ability to build [3c,4e]-bridges,
the range of stability of the mononuclear species relative to the
dinuclear one would be very narrow (if any). In fact, the synthesis
of the dicarbonyl derivative cis-[Pd(OSO2F)2(CO)2],7 as well as
that of the singular and highly electrophilic homoleptic species8
Synthesis and characterization of cis-[PdR2(thf)2]
The solvento-complexes cis-[PdR2(thf)2] [R = C6F5 (1), C6Cl5
(2)] are obtained by 1 : 2 reaction of the corresponding dinuclear
precursors [NBu4]2[{PdR2}2(m-X)2] with AgClO4 in thf under light
exclusion (Scheme 1). Compounds 1 and 2 are efficiently separated
from the accompanying [NBu4]ClO4 salt by Et2O extraction. This
is a key step in the isolation of 1 and 2 as pure solids. Attempts to
use safer silver salts, AgY (Y = SO3CF3, BF4, PF6), gave samples
of 1 and 2 contaminated with varying amounts of [NBu4]Y salts
due to their appreciable solubilities in Et2O. Although ineffective
when aiming to obtain pure samples of 1 and 2, these AgY salts
can still be used to prepare solutions of cis-[PdR2(thf)2]. Such thf
solutions of 1 and 2 are equally well suited as in situ prepared
reagents for many synthetic purposes.
Instituto de Ciencia de Materiales de Arago´n, Facultad de Ciencias, Uni-
versidad de Zaragoza–C.S.I.C, C/Pedro Cerbuna 12, E-50009, Zaragoza,
Spain. E-mail: juan.fornies@unizar.es
† Dedicated to Dr Francisco Mart´ınez (Universidad de Zaragoza) on the
occasion of his retirement.
‡ CCDC reference numbers 762684–762687. For crystallographic data in
CIF or other electronic format see DOI: 10.1039/c0dt00014k
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This feature will also appear in the remaining structures reported
in the present work but will not be mentioned further. The C6F5
rings are moderately tilted, forming a dihedral angle of ca. 70◦
with the coordination plane. The overall geometric arrangement
in 1 is similar to that found in the lighter homologous species
cis-[Ni(C6F5)2(thf)2],11 with Pd–ligand bond lengths ca. 15 pm
longer than the corresponding Ni–ligand ones, according to the
different radii assigned to NiII and PdII in SP-4 environments.18
Synthesis and characterization of cis-[PdR2(CO)2]
Scheme 1 Syntheses of solvento compounds 1 and 2 and mononuclear
carbonyl derivatives 3–10 of perhalophenyl-palladium(II). The anionic
species were isolated as their corresponding [NBu4]+ salts.
The thf molecules in 1 and 2 are labile and can be easily replaced
by a number of ligands and metalloligands19 and thus, compounds
1 and 2 behave as useful synthons of the “PdR2” fragments.
Moreover, those synthons usually retain their cis stereochemistry
along the processes undergone. In line with this behaviour, CO
also replaces the thf ligands at 1 and 2 affording cis-[PdR2(CO)2]
[R = C6F5 (3), C6Cl5 (4)] (Scheme 1). The reactions proceed in
good yields and without metal reduction as long as moisture
is rigorously excluded from the reaction medium. Otherwise,
formation of finely divided black Pd metal is observed and the
yields are lowered accordingly.
Compounds 1 and 2 have been identified by analytical and
spectroscopic methods (IR and NMR). The crystal and molecular
structures of 1 have also been established by single-crystal X-ray
diffraction methods. The Pd atom is in a slightly distorted
square-planar (SP-4) environment with the ligands adopting
a cis disposition (Fig. 1). The Pd–O distances compare well
with those found in other neutral thf complexes of PdII, such as
2
[Pd{(PPh2CH2)2BPh2-k P}(OSO2CF3)(thf)] (Pd–O 215.7(2) pm)12
Compounds cis-[PdR2(CO)2] [R = C6F5 (3), C6Cl5 (4)] belong
to the rare class of PdII dicarbonyl derivatives, for which just a
single additional example is known: cis-[Pd(OSO2F)2(CO)2].7 The
latter compound was obtained by reductive carbonylation of the
mixed-valence salt PdIIPdIV(SO3F)6 in fluorosulfuric acid as the
solvent, following a complex multistep procedure, which involves
various associated redox and rearrangement processes. This is in
contrast with the mild conditions under which compounds 3 and 4
are straightforwardly obtained (stereoselective ligand replacement
in non-coordinating organic solvents at low temperature). A
key factor allowing the isolation of all these cis-[PdR¢2(CO)2]
compounds is the low residual nucleophilicity of the R¢ coligands
(R¢ = C6F5, C6Cl5 or SO3F). The IR spectra of 3 and 4 show two
sharp absorptions assignable to the symmetric and asymmetric
vibration modes of the cis-Pd(CO)2 unit (Table 1). Appreciably
higher n(CO) values are observed for the pentafluoro- (2186 and
2163 cm-1) than for the pentachloro-phenyl derivative (2173 and
2152 cm-1), according to the higher electron-withdrawing ability
of C6F5 vs. C6Cl5.11 Likewise, the much higher n(CO) frequencies
observed for cis-[Pd(OSO2F)2(CO)2] (2228 and 2208 cm-1)7 denote
that the PdII centre is considerably more acidic in the cis-
Pd(OSO2F)2 fragment than in the cis-PdR2 ones. This observation
or trans-[PdCl2(L)(thf)] (Pd–O 211.2(2) pm; L = 2,6,7-trioxa-
3,5,8-tris(trichloromethyl)-1,4-diphosphabicyclo[2.2.2]octane).13
Shorter Pd–O distances were found in [Pd(phen)(thf)2](NO3)2
(average Pd–O 202.2(8) pm),14 a fact that can be related to the
cationic nature of the metal complex. On the other hand, the
longer Pd–O bond length found in the dinuclear PdI compound
[(Ph3P)Pd(m-PPh2NHPPh2)2Pd(thf)][BF4] (Pd–O 229.8(8) pm)15
can be attributed to the expected increase in size of the metal
ion on reduction. The Pd–C distances in 1 do not significantly
deviate from the standard value assigned to a PdII–C(aryl) bond
(198.1 pm).16 Acute Cortho–Cipso–Cortho angles are observed in the
C6F5 rings, as are usually found wherever electron-withdrawing
perhalophenyl groups are bound to more electropositive centres.17
Table 1 IR-active stretching n(CO) frequencies [cm-1] for the neutral and
anionic carbonyl metal complexes with formulae cis-[MR2(CO)2] and cis-
[MR2X(CO)]- (R = C6F5, C6Cl5) in CH2Cl2 solution
Formula
M = Nia
M = Pdb
M = Ptc
cis-[M(C6F5)2(CO)2]
cis-[M(C6Cl5)2(CO)2]
cis-[M(C6F5)2Cl(CO)]-
cis-[M(C6F5)2Br(CO)]-
cis-[M(C6F5)2I(CO)]-
cis-[M(C6Cl5)2Cl(CO)]-
cis-[M(C6Cl5)2Br(CO)]-
cis-[M(C6Cl5)2I(CO)]-
2162, 2138
—
2090
2084
2073
—
2186, 2163
2173, 2152
2124
2121
2114
2120
2114
2109
2174, 2143
2160, 2126
2091
2087
—
—
—
2084
Fig. 1 Thermal ellipsoid diagram (50% probability) of 1. Selected bond
lengths [pm] and angles [◦] with estimated standard deviations: Pd–C(1)
197.6(4), Pd–C(7) 196.2(4), Pd–O(1) 212.1(3), Pd–O(2) 212.0(3), C(1)–C(2)
137.3(6), C(1)–C(6) 138.1(6), C(7)–C(8) 136.9(6), C(7)–C(12) 139.3(6),
C(1)–Pd–C(7) 87.48(16), C(1)–Pd–O(1) 177.31(12), C(1)–Pd–O(2)
95.59(14), C(7)–Pd–O(1) 93.93(14), C(7)–Pd–O(2) 176.57(12),
O(1)–Pd–O(2) 83.06(11), Pd–C(1)–C(2) 124.6(3), Pd–C(1)–C(6) 120.6(3),
C(2)–C(1)–C(6) 114.8(4), Pd–C(7)–C(8) 123.8(3), Pd–C(7)–C(12)
121.5(3), C(8)–C(7)–C(12) 114.6(4).
—
—
a Ref. 10. b This work. c Ref. 28.
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is in agreement with the weak coordinating ability documented for
the SO3F- ion.
We were not able to obtain good-quality single-crystals of
compounds 3 or 4, which would have been suitable for X-ray
diffraction purposes. The molecular structure of 3 would, however,
be expected to be roughly similar to that previously reported for the
isoleptic and isoelectronic species cis-[Ni(C6F5)2(CO)2],11 taking
into account the different radii of the metal centres in each case
(see above). We now report the crystal and molecular structure
of cis-[Pt(C6Cl5)2(CO)2]·3H2O, which can be considered as a valid
model for compound 4. The metal atom is in an approximately
SP-4 environment (Fig. 2), with the sum of the bond angles
defined by the atoms directly bound to Pt amounting 360.1◦.
The molecule has a crystallographically imposed C2 axis bisecting
the Pt(C6Cl5)2 and Pt(CO)2 angles. The only crystallographically
independent Pt–C6Cl5 distance (207.4(7) pm) is similar to those
found in other SP-4 pentachlorophenyl-platinum(II) derivatives,
such as [NBu4]2[Pt(C6Cl5)4] (average Pt–C 208.6(14) pm).20 The
C6Cl5 ring is tilted by 65.5◦ with respect to the coordination
plane. The Pt–CO distance (196.7(8) pm) is similar to that
found in the metallacyclic compound [Pt(C&C)(CO)2] (average
Pt–C(CO): 198(2) pm; C&C = biphenyl-2,2¢-diyl)21 and longer
than those found in the remaining dicarbonyl derivatives of
PtII for which the molecular structure has been established, viz.
cis-[Pt(OSO2CF3)2(CO)2] (average Pt–C: 188.2(3) pm)22 and cis-
[PtCl2(CO)2] (average Pt–C: 189.7(5) pm).23 The longer Pt–CO
distances found in the former cases can be attributed to the
higher trans influence of the aryl ligands with respect to the Cl
or OSO2F ones.24 The Pt–C–O unit is virtually linear (178.0(9)◦).
The insensitivity of the C–O distance in metal carbonyl derivatives
to the n(CO) value and to the nature of the coligands had already
been noted.25
Fig.
3
Schematic diagram of the zigzag arrangement of
cis-[Pt(C6Cl5)2(CO)2] units along the c axis as found in single crystals of
the trihydrate. Solvent molecules appear to be hydrogen-bonded between
them (O ◊ ◊ ◊ O separation: 0.26–0.28 nm) but, as they do not seem to
interact with the organometallic unit, they have been ◦omitted for clarity.
Relevant intermolecular distances [pm] and angles [ ]: Clortho ◊ ◊ ◊ C(CO)
340.8, Pt ◊ ◊ ◊ Pt¢ ◊ ◊ ◊ Pt¢¢ 149.8.
the C6Cl5 groups, however, seems to preclude a closer approach
of the Pt centres in our case. The observed intermetallic distance
between adjacent metal atoms along the c axis is 0.61 nm and
the Pt ◊ ◊ ◊ Pt¢ ◊ ◊ ◊ Pt¢¢ angle (149.8◦) largely deviates from linearity.
Thus, neither the intermetallic distance nor the relative geometric
disposition are appropriate to denote the existence of any ex-
tended interaction between the d8 metal centres. The absence of
intermolecular Pt ◊ ◊ ◊ Pt interactions is in keeping with the lack of
any observable pyramidalization within the individual molecules.26
Loose intermolecular interactions are, however, observed between
ortho-Cl atoms of the C6Cl5 group and the electrophilic C atom of
the CO ligand with a Cl ◊ ◊ ◊ C distance (340.8 pm) slightly shorter
than the sum of the corresponding van der Waals radii (345 pm).27
Intermolecular interactions between some neighbouring basic
centres (in the Lewis sense) and the C atom of the CO ligand
are frequently observed in metal carbonyl derivatives in which the
CO molecule acts as a mainly s-donor ligand.7,22
Fig.
2
Thermal
ellipsoid
diagram
(50%
probability)
of
cis-[Pt(C6Cl5)2(CO)2] as found in single crystals of the trihydrate.
Selected bond lengths [pm] and angles [◦] with estimated standard
deviations: Pt–C(1) 207.4(7), Pt–C(7) 196.7(8), C(1)–C(2) 140.5(11),
C(1)–C(6) 140.4(10), C(7)–O(1) 109.8(11), C(1)–Pt–C(1¢) 90.3(4),
C(1)–Pt–C(7) 86.7(3), C(1)–Pt–C(7¢) 176.5(3), C(7)–Pt–C(7¢) 96.4(5),
Pt–C(1)–C(2) 123.9(5), Pt–C(1)–C(6) 120.0(6), C(2)–C(1)–C(6) 116.1(6),
Pt–C(7)–O(1) 178.0(9).
In the crystal packing, the cis-[Pt(C6Cl5)2(CO)2] molecules
adopt an alternating zigzag arrangement along the c axis (Fig. 3),
following a roughly similar pattern to that observed for the related
species [Pt(C&C)(CO)2]21 and cis-[PtCl2(CO)2].23 The bulkiness of
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Similar structural features would be expected for the isoleptic
PdII compound 4 at molecular level. Perhaps, even a slightly longer
Pd–CO bond length would be anticipated bearing in mind: (1)
the comparable radii of the Pd2+ (64 pm) and Pt2+ (60 pm) ions
in SP-4 environments,18 and (2) the significantly higher n(CO)
value observed for the Pd derivative (Table 1). In fact, the PdII
derivatives exhibit the highest n(CO) values within the family of
metal dicarbonyl compounds cis-[MR2(CO)2] for all three Group
10 metals (M = Ni, Pd, Pt). It appears that Pd has a diminished
ability to efficiently become involved in the p-back donation
mechanism of the M–CO bond.
homogeneous variation by ca. 5 cm-1 in the n(CO) value on
changing the halogen observed in both the pentafluoro- and
pentachloro-phenyl series noted above (Table 1), makes it sensible
to assign a cis geometry to compounds 8–10.
In order to confirm that the cis geometry is maintained in
the solid state and also to enable a meaningful comparison with
the known Ni homologous species,11 the crystal and molecular
structures of the salt [PMePh3][cis-Pd(C6F5)2Br(CO)] (6¢) were
established by X-ray diffraction methods. The [PMePh3][cis-
M(C6F5)2Br(CO)] salts (M = Ni, Pd) were found to be isomor-
¯
phous (triclinic, P1) and isostructural. The angles around the Pd
atom in the anion of 6¢ (Fig. 4) are similar to those found in the Ni
species. The metal–ligand bond lengths are longer by ca. 15 pm for
Pd than for Ni, according to the different size of each metal centre
(see above).18 Despite the elongated metal–ligand distances in 6¢,
the corresponding cell volume (1.48999(14) nm3) is comparable to
that of the isomorphous Ni compound (1.5044(6) nm3). Thus, the
fine structural differences in the metal coordination environments
do not have any significant effect in the interionic separation. The
Pd–C(aryl) distances are slightly longer in 6¢ (202.8(4) pm average
value) than in 1 (196.9(4) pm average value), probably due to the
anionic nature of the former. The Pd–Br distance (248.21(5) pm)
compares well with the mean value derived from a number of four-
coordinate compounds with terminal Pd–Br bonds (245.0 pm).16
On the other hand, the Pd–CO distance (196.1(4) pm) is longer
than usually found in terminal carbonyl derivatives of PdII as will
be commented later on.
Synthesis and characterization of
[NBu4][cis-PdR2X(CO)]
The reaction of the dinuclear compounds [NBu4]2[{PdR2}2(m-X)2]
(R = C6F5, C6Cl5; X = Cl, Br, I) with CO (1 atm) takes place
in so-called “non-coordinating” solvents at room temperature
under splitting of the double halide-bridging system (Scheme 1).
Given the known precedents in the chemistry of perhalophenyl-
derivatives of Ni and Pt,11,28 it is sensible to assume that CO coor-
dination also takes place with stereoretention in the Pd case. The
whole series of monocarbonyl derivatives [NBu4][cis-PdR2X(CO)]
(5–10) are observed to form in solution under a CO atmosphere
(IR spectroscopy), but they revert to the corresponding parent
species at reduced CO pressure. The intermolecular substitution
process leading to the reversible formation of the starting materials
can be prevented in all cases but one, by slow addition of a CO-
saturated precipitating agent at low temperature (-78 ◦C). Under
these conditions we succeeded in isolating compounds 5, 6 and
8–10 (Scheme 1) in reasonable yields. Our attempts to isolate
[NBu4][cis-Pd(C6F5)2I(CO)] (7) invariably led to the dinuclear
compound [NBu4]2[{Pd(C6F5)2}2(m-I)2].
Compounds 5, 6 and 8–10 have been identified by analyti-
cal and spectroscopic methods. The IR spectra of compounds
5–10 in solution show single, sharp absorptions in the 2100 cm-1
region (Table 1) corresponding to the only IR-active n(CO)
vibration mode. This spectroscopic behaviour is compatible with
both possible cis and trans geometries. However, the presence of
two equally intensive absorptions assignable to the X-sensitive
vibration modes in the pentafluorophenyl derivatives 5 and 6
points to a cis arrangement, as initially assumed.§ An increase
of ca. 5 cm-1 in the n(CO) value is observed on changing the
halogen in order of increasing electronegativity: I < Br < Cl.
According to the behaviour observed in the dicarbonyl derivatives
3 and 4 (see above), slightly higher n(CO) values are observed for
the pentafluoro- than for the pentachloro-phenyl derivatives for
a given halogen within the [PdR2X(CO)]- series. The presence of
two chemically inequivalent C6F5 groups in the 19F NMR spectra
of 5–7 in solution allows a cis geometry to be unambiguously
assigned to this set of compounds. The low solubility of the
perchlorophenyl compounds 8–10 in poorly coordinating organic
solvents—especially at the low temperatures required to prevent
their dimerisation under CO extrusion (Scheme 1)—precluded
the acquisition of good-quality 13C NMR spectra. However, the
Fig.
4
Thermal ellipsoid diagram (50% probability) of the
[cis-Pd(C6F5)2Br(CO)]- anion in 6¢. Selected bond lengths [pm] and
angles [◦] with estimated standard deviations: Pd–C(1) 202.4(4),
Pd–C(7) 203.2(4), Pd–C(13) 196.1(4), Pd–Br 248.21(5), C(1)–C(2)
137.8(5), C(1)–C(6) 137.9(5), C(13)–O 110.4(4), C(7)–C(8) 137.0(5),
C(7)–C(12) 137.0(5), C(1)–Pd–C(7) 86.27(13), C(1)–Pd–C(13) 176.23(14),
C(1)–Pd–Br 89.56(10), C(7)–Pd–C(13) 90.18(14), C(7)–Pd–Br 175.83(10),
C(13)–Pd–Br 93.99(10), Pd–C(1)–C(2) 123.3(3), Pd–C(1)–C(6) 121.8(3),
C(2)–C(1)–C(6) 114.9(3), Pd–C(7)–C(12) 121.8(3), Pd–C(7)–C(8) 122.4(3),
C(8)–C(7)–C(12) 115.8(3), Pd–C(13)–O 177.9(3).
Synthesis and characterization of
[NBu4][{Pd(C6F5)2(CO)}2(l-Cl)] (11)
We sought to exploit the residual nucleophilicity of the halocar-
bonyl derivatives of PdII in a productive way. For this purpose,
we reacted [NBu4][cis-Pd(C6F5)2Cl(CO)] (5) with the dicarbonyl
§ Although two IR-active X-sensitive absorptions would also be expected
for the trans isomers, their experimental relative intensities are usually so
different that one of them is barely observable, if at all.28
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derivative cis-[Pd(C6F5)2(CO)2] (3), a process resulting in the for-
mation of the dinuclear compound [NBu4][{Pd(C6F5)2(CO)}2(m-
Cl)] (11) in good yield (Scheme 2). In this reaction, the anion [cis-
Pd(C6F5)2Cl(CO)]- of 5 acts as a metalloligand towards neutral
complex 3, in which it causes the replacement of one of the CO
ligands.
approximately SP-4 environment, connected by a single bridging
chloro ligand. The coordination planes of the two Pd atoms form
a dihedral angle of 76.3◦. The Pd(1)–Cl–Pd(2) bridging unit forms
almost a right angle: 91.21(3)◦, which is a suitable geometry to
enable the m-Cl atom to make optimal use of its p orbitals.29 The
intramolecular Pd(1) ◊ ◊ ◊ Pd(2) separation (344.5 pm) is too long to
denote the existence of any metal–metal bonding interaction. The
two Pd(C6F5)2(CO) units adopt a mutual transoidal disposition
so that intramolecular non-bonded repulsions are minimized. The
C6F5 groups are tilted and form dihedral angles in the range 63.4–
73.0◦ with the corresponding metal coordination plane. The Pd–
Cl distances are indistinguishable and compare well with those
found in four-coordinate PdII compounds containing bridging Cl
ligands (mean value: 240.4 pm).16 All four Pt–C(aryl) distances
are also virtually identical and do not appreciably deviate from
those found in the mononuclear halocarbonyl derivative 6¢ (see
above). The Pd–CO distances in 11 (198.3(5) pm) are similar to that
observed in 6¢ (196.1(4) pm) and longer than those usually found
in other structurally characterized four-coordinate PdII derivatives
containing terminal carbonyl groups. Even in the cationic and
highly electrophilic tetracarbonyl derivative [Pd(CO)4][Sb2F11]2 the
Pd–CO distances (mean value: 199.2(6) pm) are comparable with
those found in 11.8
The presence of two chemically inequivalent types of C6F5
groups in the 19F NMR spectrum of 11 in solution is in keeping
with the solid state structure just described. The IR spectrum of
11 in CH2Cl2 solution shows a single, sharp n(CO) absorption
at 2134 cm-1. The increase of 10 cm-1 with respect to the value
observed in the mononuclear parent compound 5 (Table 1)
evidences the lowered donor ability of the bridging vs. terminal
Cl ligand.
Scheme 2 Synthesis of the dinuclear carbonyl-palladium(II) derivative 11
(R = C6F5) isolated as its [NBu4]+ salt.
Compound 11 is stable enough to allow its isolation and
characterization by X-ray diffraction methods. A drawing of the
dinuclear anion [{Pd(C6F5)2(CO)}2(m-Cl)]- as found in single crys-
tals of 11 is given in Fig. 5. It consists of two Pd atoms, each in an
Dinuclear d8 metal compounds with bridging halo ligands
usually adopt a doubly bridging M(m-X)2M¢ pattern.30 Homo-
or hetero-dimetallic compounds containing a single bridging halo
core M(m-X)M¢ are far less common. These kinds of compounds
are of interest because of their mechanistic implications. They
act as formal models for the synthetically useful process taking
place under splitting of the doubly bridging M(m-X)2M¢ system,
as well as for the reverse reaction. They have also been found to
be involved in halide abstraction processes.31 Compound 11 is of
particular relevance in the reaction leading to the mononuclear
derivatives 5–10, and also in the counter-reaction causing their
decomposition (Scheme 1). Most of the structurally characterized
precedents of d8 metal compounds with unsupported single bridg-
ing halo ligands contain additional polydentate or p-coordinated
ligands, that probably contribute to their stabilization.32 As far as
we know, the only previous case with just monodentate ligands
is [{trans-PtH(PiPr3)2}2(m-I)][B{C6H3(CF3)2-3,5}4],33 for which a
very wide Pt–I–Pt angle was observed: 170.14(9)◦.
Fig. 5 Structural drawing (with 50% probability thermal ellipsoids
for the heavy atoms) of the dinuclear [{Pd(C6F5)2(CO)}2(m-Cl)]-
anion in 11·CH2Cl2. Selected bond lengths [pm] and angles [◦]
with estimated standard deviations: Pd(1)–C(1) 202.7(4), Pd(1)–C(7)
201.0(4), Pd(1)–C(25) 198.3(5), Pd(1)–Cl(1) 240.9(1), Pd(2)–C(13)
202.4(4), Pd(2)–C(19) 201.5(4), Pd(2)–C(26) 198.2(5), Pd(2)–Cl(1)
241.2(1), C(25)–O(1) 112.1(5), C(26)–O(2) 112.2(5), C(1)–Pd(1)–
Concluding remarks
Dicarbonyl-palladium(II) compounds with formula cis-
[PdR2(CO)2] [R = C6F5 (3), C6Cl5 (4)] have been prepared
in good yield by replacing the labile thf ligands in the solvento-
complexes cis-[PdR2(thf)2] [R = C6F5 (1), C6Cl5 (2)] by CO under
mild conditions. Isolation of these compounds has been possible,
among other reasons, because of the small residual nucleophilicity
of the metal-bound perhalophenyl groups, together with the
C(7)
84.3(2),
C(1)–Pd(1)–C(25)
174.0(2),
C(1)–Pd(1)–Cl(1)
91.7(1), C(7)–Pd(1)–C(25) 92.6(2), C(7)–Pd(1)–Cl(1) 173.5(1),
C(25)–Pd(1)–Cl(1) 92.2(1), Pd(1)–C(25)–O(1) 175.5(4), Pd(1)–Cl(1)–Pd(2)
91.21(3), C(13)–Pd(2)–C(19) 85.5(2), C(13)–Pd(2)–C(26) 175.1(2),
C(13)–Pd(2)–Cl(1) 91.8(1), C(19)–Pd(2)–C(26) 90.9(2), C(19)–Pd(2)–Cl(1)
176.2(1), C(26)–Pd(2)–Cl(1) 91.9(1), Pd(2)–C(26)–O(2) 176.5(4).
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reluctance of the M–R bonds to undergo CO insertion. The high
frequency values observed for the IR-active n(CO) vibration
modes in compounds 3 and 4 are to be attributed to the marked
electron-withdrawing character of the R groups. According to the
IR data (Table 1), the electron-withdrawing ability of the C6F5
group is even greater than that of the C6Cl5 one.
Synthesis of cis-[Pd(C6F5)2(thf)2] (1)
Compound 1 was prepared following a previously reported
method.19e Elemental analysis calcd (%) for C20H16F10O2Pd: C
˜
41.1, H 2.7; found: C 40.8, H 2.9. IR (Nujol): nmax 1638 (m),
1603 (w), 1496 (s), 1362 (m), 1355 (m), 1256 (w), 1058 (s), 1037
(s), 954 (vs; nCF), 884 (vs; thf: C–O–C),37 802 (s; C6F5: X-sensitive
vibr.),36 792 cm-1 (s; C6F5: X-sensitive vibr.).36 1H NMR ([2H]-
chloroform): d 3.79 (4H, a-CH2), 1.82 (4H, b-CH2) ppm. 19F
NMR ([2H]-chloroform): d -117.3 (4F, o-F), -159.8 (2F, p-F),
-163.4 (4F, m-F) ppm.
Single crystals of 1 suitable for X-ray diffraction purposes were
obtained by slow diffusion of an n-hexane (5 cm3) layer into a
solution of 30 mg of 1 in 2 cm3 of CH2Cl2 at -30 ◦C.
Splitting of the double-bridging system in the dinuclear com-
pounds [NBu4]2[{PdR2}2(m-X)2] (X = Cl, Br, I) by CO leads
to the formation of the monocarbonyl-palladium(II) compounds
[NBu4][cis-PdR2X(CO)] (5–10) in solution. With the synthesis of
these Pd compounds, we have completed a family of homologous
compounds of formula [cis-MR2X(CO)]- for all three Group 10
metals (M = Ni, Pd, Pt). We have found that the n(CO) frequency
values are higher for Pd than for Ni or Pt. The n(CO) values also
depend upon the cis influence of the halo ligands, following the
decreasing order of electronegativity: Cl > Br > I. The range of
stability of the monocarbonyl derivatives of Ni and Pd is rather
limited because of the considerable residual nucleophilicity of the
metal-bound halo ligands, M–X. The readiness of these com-
pounds to extrude CO following an intermolecular substitution
process, which is the reverse of the procedure leading to their
synthesis (Scheme 1), hinders their isolation. Thus, we did not
managed to isolate compound 7 (R = C6F5; X = I). The higher
stability of the corresponding Pt compounds is probably due to a
combination of thermodynamic (intrinsically more stable Pt–CO
bonds) and kinetic (slower decomposition reaction rates) reasons.
The residual nucleophilicity of the Pd-bound Cl atom at
the [cis-Pd(C6F5)2Cl(CO)]- anion enables this unit to act as
a metalloligand towards the dicarbonyl derivative 3 affording
[NBu4][{Pd(C6F5)2(CO)}2(m-Cl)] (11) in reasonable yield. This
dinuclear derivative consists of two symmetric SP-4 units sharing a
vertex. The Pd–Cl–Pd angle [91.21(3)◦] closely approaches a right
angle, which is considered to be the most appropriate geometry to
enable an optimal use of the p orbitals on the single bridging
halo ligand. Compound 11 can be taken as a model of the
intermediate species presumably involved in the splitting of the
double bridging halide system in complexes [NBu4]2[{PdR2}2(m-
X)2] by CO (Scheme 1).
Synthesis of cis-[Pd(C6Cl5)2(thf)2] (2)
Compound 2 was prepared following a previously reported
method.19e Elemental analysis calcd (%) for C20H16Cl10O2Pd: C
˜
32.05, H 2.1; found: C 31.7, H 2.6. IR (Nujol): nmax 1334 (s), 1313
(s), 1289 (s), 1260 (m), 1208 (m), 1150 (m), 1088 (m), 1046 (s),
1028 (s), 1003 (m), 875 (s; thf: C–O–C),37 841 (s; C6Cl5: X-sensitive
vibr.),36 832 (s; C6Cl5: X-sensitive vibr.),36 788 (m), 673 (vs), 627 (m;
n
Pt–C),38 617 cm-1 (m; nPt–C).38 1H NMR ([2H]-dichloromethane): d
3.72 (4H, a-CH2), 1.78 (4H, b-CH2) ppm.
Synthesis of cis-[Pd(C6F5)2(CO)2] (3)
◦
A CH2Cl2 (10 cm3) solution of 1 (0.19 g, 0.32 mmol) at -78 C
was allowed to react for 30 min with CO at atmospheric pressure,
whereupon a white solid started to form. Addition of n-hexane
(30 cm3) at -78 ◦C caused the precipitation of a larger amount
of white solid, which was filtered at -78 ◦C and vacuum-dried
at -40 ◦C (3: 0.14 g, 0.29 mmol, 90% yield). Due to its high
instability, no satisfactory elemental analyses could be obtained
˜
for 3. IR (Nujol): nmax 2186 (vs; nCO), 2163 (vs; nCO), 1640 (m),
1610 (w), 1511 (vs), 1084 (s), 1067 (s), 962 (vs; nCF), 798 (s; C6F5:
X-sensitive vibr.),36 786 (s; C6F5: X-sensitive vibr.),36 448 (m),◦422
(m), 382 (w), 330 cm-1 (w). 19F NMR ([2H]-chloroform, -50 C):
d -116.3 (4F, o-F), -155.4 (2F, p-F), -160.8 (4F, m-F) ppm.
No cis/trans isomerization has been observed in any of the pro-
cesses reported in this paper that take place with stereoretention.
Synthesis of cis-[Pd(C6Cl5)2(CO)2] (4)
Compound 4 was prepared from 2 (0.27 g, 0.36 mmol) by using
a similar procedure to that just described for the synthesis of 3.
Complex 4 was obtained as a white solid (0.13 g, 0.20 mmol,
56% yield). Elemental analysis calcd (%) for C14Cl10O2Pd: C 25.4;
Experimental
General procedures and materials
˜
found: C 25.1. IR (Nujol): nmax 2173 (vs; nCO), 2152 (vs; nCO), 1327
Unless otherwise stated, the reactions and manipulations were
carried out under purified argon using Schlenk techniques.
Solvents were dried using an MBraun SPS-800 System. Com-
pounds [NBu4]2[{Pd(C6F5)2}2(m-X)2] (X = Cl, Br, I)34 and
[NBu4]2[{Pd(C6Cl5)2}2(m-X)2] (X = Cl, Br, I)35 were obtained
following the appropriate published methods. Elemental analyses
were carried out with a Perkin-Elmer 2400-Series II microanalyzer.
IR spectra of CH2Cl2 solution samples, Nujol mulls or KBr
discs were recorded on a Perkin-Elmer 883 spectrophotometer
(4000–200 cm-1). NMR spectra were recorded on any of the
following spectrometers: Varian Unity-300, Bruker ARX 300
or Bruker ARX 400. Unless otherwise stated, the spectroscopic
measurements were carried out at room temperature.
(vs), 1321 (vs), 1295 (vs), 840 (sh; C6Cl5: X-sensitive vibr.),36 833 (s;
C6Cl5: X-sensitive vibr.),36 670 (vs), 619 (sh; nPt–C),38 614 (s; nPt–C),38
482 (s), 444 (m), 412 (m), 384 (w), 370 (w), 339 (w), 323 cm-1 (w).
Synthesis of [NBu4][cis-Pd(C6F5)2Cl(CO)] (5)
A solution of [NBu4]2[{Pd(C6F5)2}2(m-Cl)2] (0.201 g, 0.140 mmol)
in CH2Cl2 (8 cm3) at 0 ◦C was allowed to react with CO. The colour
of the solution gradually faded. After 1 h of stirring, the solution
was cooled to -78 C and CO-saturated n-hexane (15 cm3) was
added, causing the precipitation of a white solid, which was filtered
at -78 ◦C and dried at the same temperature in an Ar stream (5:
0.181 g, 0.243 mmol, 87% yield). Elemental analysis calcd (%) for
◦
7306 | Dalton Trans., 2010, 39, 7301–7309
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C29H36ClF10NOPd: C 46.7, H 4.9, N 1.9; found: C 47.1, H 5.3, N
the synthesis of 5. Complex 10 was obtained as a white solid
(0.059 g, 0.059 mmol, 57% yield). Elemental analysis calcd (%) for
C29H36Cl10INOPd: C 34.7, H 3.6, N 1.4; found: C 34.9, H 3.8, N
˜
2.0. IR (KBr): nmax 2967 (s), 2878 (s), 2114 (vs; nCO), 1498 (vs), 1459
(vs), 1380 (w), 1360 (m), 1055 (s), 955 (vs; nCF), 881 (m; [NBu4]+),
795 (s; C6F5: X-sensitive vibr.),36 781 (s; C6F5: X-sensitive vibr.),36
739 cm-1 (m). 19F NMR ([2H]-chloroform, -20 ◦C): d -115.7 (2F,
o-F), -116.2 (2F, o-F), -160.4 (1F, p-F), -161.7 (1F, p-F), -163.6
(2F, m-F), -164.1 (2F, m-F) ppm.
˜
1.6. IR (KBr): nmax 2963 (s), 2875 (s), 2104 (vs; nCO), 1479 (s), 1380
(m), 1313 (vs), 1283 (vs), 1219 (m), 1151 (w), 881 (m; [NBu4]+),
816 (w; C6Cl5: X-sensitive vibr.),36 739 (m), 669 (vs), 614 (s; nPt–C),38
582 cm-1 (m).
Synthesis of [NBu4][cis-Pd(C6F5)2Br(CO)] (6)
Synthesis of [NBu4][{Pd(C6F5)2(CO)}2(l-Cl)] (11)
Compound 6 was prepared from [NBu4]2[{Pd(C6F5)2}2(m-Br)2]
(0.163 g, 0.107 mmol) by using the procedure described for
the synthesis of 5. Complex 6 was obtained as a white solid
(0.127 g, 0.161 mmol, 75% yield). Elemental analysis calcd (%) for
C29H36BrF10NOPd: C 44.0, H 4.6, N 1.8; found: C 43.9, H 4.5, N
A
CH2Cl2 solution (10 cm3) of
5 was prepared from
[NBu4]2[{Pd(C6F5)2}2(m-Cl)2] (0.14 g, 0.10 mmol) as described
above and was cooled to -40 ◦C. To this solution generated in
situ was added 3 (0.10 g, 0.20 mmol) dissolved in CH2Cl2 at the
same temperature and the mixture was allowed to slowly warm to
0 ◦C, while several vacuum/Ar cycles were applied. Then n-hexane
(40 cm3) was overlaid. After standing at -30 ◦C overnight, a white
solid formed which was filtered at -40 ◦C and vacuum dried (11:
0.12 g, 0.10 mmol, 50% yield). Elemental analysis calcd (%) for
C42H36ClF20NO2Pd2: C 41.5, H 3.0, N 1.1; found: C 41.4, H 3.0, N
˜
1.8. IR (KBr): nmax 2968 (s), 2880 (s), 2113 (vs; nCO), 1497 (vs), 1458
(vs), 1381 (w), 1361 (m), 1056 (s), 956 (vs; nCF), 881 (m; [NBu4]+),
794 (s; C6F5: X-sensitive vibr.),36 780 (s; C6F5: X-sensitive vibr.),36
738 cm-1 (m). 19F NMR ([2H]-chloroform, -20 ◦C): d -115.6 (2F,
o-F), -115.8 (2F, o-F), -160.3 (1F, p-F), -161.8 (1F, p-F), -163.4
(2F, m-F), -164.2 (2F, m-F) ppm.
˜
1.1. IR (KBr): nmax 2145 (vs; nCO), 1504 (vs), 1464 (vs), 1361 (m),
1059 (s), 959 (vs; nCF), 880 (w; [NBu4]+), 798 (s; C6F5: X-sensitive
vibr.),36 789 cm-1 (s; C6F5: X-sensitive vibr.).36 19F NMR ([2H]-
Spectroscopic detection of [NBu4][cis-Pd(C6F5)2I(CO)] (7)
◦
dichloromethane, -80 C): d -116.1 (2F, o-F), -117.1 (2F, o-F),
-159.6 (1F, p-F), -160.1 (1F, p-F), -163.2 (2F, m-F), -163.5 (2F,
m-F) ppm.
Single crystals of 11 suitable for X-ray diffraction purposes were
obtained by slow diffusion of an n-hexane (8 cm3) layer into a
solution of 40 mg of 11 in 2 cm3 of CH2Cl2 at -30 ◦C.
The synthesis of
7
was attempted starting from
[NBu4]2[{Pd(C6F5)2}2(m-I)2] (0.108 g, 0.067 mmol) using the
procedure described for the synthesis of 5. Although compound
7 was observed to form in solution by IR (Table 1) and 19F NMR
spectroscopies, our attempts to isolate it rendered ca. 75% of the
dinuclear starting material. 19F NMR ([2H]-chloroform, -20 ◦C):
d -114.3 (2F, o-F), -116.3 (2F, o-F), -160.3 (1F, p-F), -162.0 (1F,
p-F), -163.3 (2F, m-F), -164.4 (2F, m-F) ppm.
Single crystals of cis-[Pt(C6Cl5)2(CO)2]·3H2O
Single crystals suitable for X-ray diffraction purposes with formula
cis-[Pt(C6Cl5)2(CO)2]·3H2O were obtained by slow diffusion of an
n-hexane (5 cm3) layer into a solution of cis-[Pt(C6Cl5)2(CO)2]28
(30 mg) in CH2Cl2 (2 cm3) at -30 ◦C.
Synthesis of [NBu4][cis-Pd(C6Cl5)2Cl(CO)] (8)
Compound 8 was prepared from [NBu4]2[{Pd(C6Cl5)2}2(m-Cl)2]
(0.065 g, 0.037 mmol) using the procedure described for the
synthesis of 5. Complex 8 was obtained as a white solid
(0.033 g, 0.036 mmol, 50% yield). Elemental analysis calcd (%)
for C29H36Cl11NOPd: C 38.2, H 4.0, N 1.6; found: C 37.8, H 4.2,
X-Ray structure determinations†
Crystal data and other details of the structure analysis are
presented in Table 2. Crystals were mounted on quartz fibres
in a random orientation and held in place with fluorinated oil.
Graphite monochromated Mo-Ka radiation (l = 71.073 pm) was
used in all cases. For 1 and 6¢ diffraction data were collected on
a Bruker Smart Apex CCD diffractometer, and the diffraction
frames were integrated using the SAINT package39 and corrected
for absorption with SADABS.40 For cis-[Pt(C6Cl5)2(CO)2]·3H2O,
data collection was performed on a Enraf Nonius CAD4 diffrac-
tometer, and an absorption correction was applied based on
310 azimuthal scan data. For 11·CH2Cl2, data collection was
performed on a Oxford Diffraction Xcalibur CCD diffractometer,
and the diffraction frames were integrated and corrected for
absorption using the CrysAlis RED package.41 Lorentz and
polarisation corrections were applied for all the structures.
˜
N 1.5. IR (KBr): nmax 2962 (s), 2875 (s), 2113 (vs; nCO), 1472 (s),
1381 (m), 1327 (vs), 1316 (vs), 1289 (vs), 1221 (m), 1155 (w), 881
(m; [NBu4]+), 837 (m; C6Cl5: X-sensitive vibr.),36 738 (m), 673 (vs),
611 (s; nPt–C),38 458 cm-1 (m).
Synthesis of [NBu4][cis-Pd(C6Cl5)2Br(CO)] (9)
Compound 9 was prepared from [NBu4]2[{Pd(C6Cl5)2}2(m-Br)2]
(0.068 g, 0.036 mmol) using the procedure described for the
synthesis of 5. Complex 9 was obtained as a white solid
(0.032 g, 0.033 mmol, 46% yield). Elemental analysis calcd (%)
for C29H36BrCl10NOPd: C 36.4, H 3.8, N 1.5; found: C 36.2, H 3.7,
˜
N 1.3. IR (KBr): nmax 2962 (s), 2874 (s), 2109 (vs; nCO), 1480 (s),
1379 (m), 1327 (vs), 1316 (vs), 1288 (vs), 1221 (m), 1150 (w), 881
(m; [NBu4]+), 835 (m; C6Cl5: X-sensitive vibr.),36 738 (m), 673 (vs),
609 (s; nPt–C),38 457 cm-1 (m).
The structures were solved by Patterson and direct methods. All
non-hydrogen atoms of the complexes were assigned anisotropic
displacement parameters. For cis-[Pt(C6Cl5)2(CO)2]·3H2O, the
hydrogen atoms were not located in the density map and were
not included in the refinement. For the remaining structures,
the hydrogen atoms were constrained to idealised geometries
Synthesis of [NBu4][cis-Pd(C6Cl5)2I(CO)] (10)
Compound 10 was prepared from [NBu4]2[{Pd(C6Cl5)2}2(m-I)2]
(0.102 g, 0.052 mmol) by using the procedure described for
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Table 2 Crystal data and structure refinement for complexes 1, cis-[Pt(C6Cl5)2(CO)2]·3H2O, 6¢ and 11·CH2Cl2
1
cis-[Pt(C6Cl5)2(CO)2]·3H2O
6¢
11·CH2Cl2
Formula
FW
C20H16F10O2Pd
584.73
C14Cl10O2Pt·3H2O
C32H18BrF10OPPd
825.74
C42H36ClF20NO2Pd2·CH2Cl2
803.78
1299.89
Orthorhombic
Pbca
Crystal system
Space group
a/pm
Triclinic
Monoclinic
C2/c
2020.6(2)
1251.90(15)
1182.45(13)
90
122.90(1)
90
2.5114(5)
4
2.126
293(2)
6.675
1512
3.44–24.99
1844
1844
Triclinic
¯
¯
P1
P1
928.30(6)
956.52(6)
1279.16(8)
69.777(1)
74.253(1)
83.994(1)
1.02572(11)
2
1107.37(6)
1143.35(6)
1395.72(8)
113.680(1)
107.883(1)
95.584(1)
1.48999(14)
2
1812.82(5)
1825.09(8)
2960.36(8)
90
90
90
9.7945(6)
8
1.763
100(1)
1.012
5136
4.52–25.06
27 465
8559
0.0320
0.0442, 0.1043
0.0554, 0.1100
1186, -911
1.091
b/pm
c/pm
a/◦
b/◦
g /◦
V/nm3
Z
Dc/g cm-3
T/K
1.893
100(2)
1.010
576
1.75–23.29
6830
2960
1.841
100(2)
2.107
808
1.72–23.29
9935
4297
m/mm-1
F(000)
q range/◦
Collected reflections
Unique reflections
Rint
0.0279
0
0.0196
R1a, wR2 (I > 2s(I))
0.0398, 0.1061
0.0428, 0.1079
1583, -1051
1.006
0.0348, 0.0913
0.0370, 0.0929
972, -851
1.092
0.0285, 0.0738
0.0339, 0.0754
481, -513
1.020
b
R1a, wR2 b(all data)
Max, min Dr/e nm-3
GOF (F2)c
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
a R1 = (|Fo| - |Fc|)/ |Fo|. b wR2 = [ w(Fo - Fc2)2/ w(Fo2)2]1/2
.
c Goodness-of-fit =[ w(Fo - Fc2)2/(nobs - nparam)]1/2
.
2
2
and assigned isotropic displacement parameters equal to 1.2 or
1.5 times the Uiso values of their respective parent atoms. Full-
matrix least-squares refinement of these models against F2 using
the SHELXL-9342 (cis-[Pt(C6Cl5)2(CO)2]·3H2O) or SHELXL-9743
(1, 6¢ and 11·CH2Cl2) programs converged to final residual indices
given in Table 2.
13 Y. Kim and J. G. Verkade, J. Organomet. Chem., 2003, 669,
32.
14 H. Huang and S.-Y. Yu, Jiegou Huaxue, 2003, 22, 547.
15 C. S. Browning, D. H. Farrar, D. C. Frankel and J. J. Vittal, Inorg. Chim.
Acta, 1997, 254, 329.
16 A. G. Orpen, L. Brammer, F. H. Allen, O. Kennard, D. G. Watson and
R. Taylor, J. Chem. Soc., Dalton Trans., 1989, S1.
17 J. A. Hermoso, F. H. Cano and M. Mart´ınez-Ripoll, J. Chem.
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Acknowledgements
This work was supported by the Spanish MICINN (DG-
PTC)/FEDER (Project CTQ2008-06669-C02-01/BQU) and the
Gobierno de Arago´n (Grupo de Excelencia: Qu´ımica Inorga´nica y
de los Compuestos Organometa´licos).
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