The reactions of [M(dppe)2] (M = Pd, Pt) with elemental selenium or tellurium: Preparation and structure of the platinum polyselenide [PtSe4 (dppe)]

Article abstract of DOI:10.1016/S0277-5387(00)00303-X

Reaction of [Pt(dppe)₂] (dppe= 1,2-bis(diphenylphosphino)ethane) with elemental selenium in toluene under reflux, or of [PtCl₂(dppe) ] with lithium polyselenide in tetrahydrofuran, leads in good yield to the complex [PtSe₄(dppe)] whose structure has been determined by X-ray crystallography. Reaction of [Pt(dppe)₂] with elemental tellurium, followed by treatment with dichloromethane, leads to isolation of the salt [Pt₃(μ₃-Te)₂(dppe)₃]Cl₂. [Pd(dppe)₂] reacts with elemental selenium to give [Pd₂(μ-Se)₂(dppe)₂] or [Pd₃(μ₃-Se)₂(dppe)₃]C1₂, depending on the conditions. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0277-5387(00)00303-X

www.elsevier.nl/locate/poly
Polyhedron 19 (2000) 751–756
The reactions of [M(dppe)2] (MsPd, Pt) with elemental selenium or
tellurium: preparation and structure of the platinum polyselenide
[PtSe4(dppe)]
b
Mark R. Lewtas a, Christopher P. Morley a, , Massimo Di Vaira
*
a Department of Chemistry, University of Wales Swansea, Singleton Park, Swansea SA2 8PP, UK
b
`
Dipartimento di Chimica, Universita degli Studi di Firenze, Via Maragliano 75/77, 50144 Florence, Italy
Received 1 November 1999; accepted 14 January 2000
Abstract
Reaction of [Pt(dppe)2] (dppes1,2-bis(diphenylphosphino)ethane) with elemental selenium intolueneunderreflux, orof[PtCl2(dppe)]
with lithium polyselenide in tetrahydrofuran, leads in good yield to the complex [PtSe4(dppe)] whose structure has been determined by X-
ray crystallography. Reaction of [Pt(dppe)2] with elemental tellurium, followed by treatment with dichloromethane, leads to isolation of the
salt [Pt3(m3-Te)2(dppe)3]Cl2. [Pd(dppe)2] reacts with elemental selenium to give [Pd2(m-Se)2(dppe)2] or [Pd3(m3-Se)2(dppe)3]Cl2,
depending on the conditions.
q2000 Elsevier Science Ltd All rights reserved.
Keywords: Palladium; Platinum; Selenium; Tellurium
1. Introduction
Further treatment of [PtS4(PPh3)2] with dimethylacetyl-
ene dicarboxylate leads to the dithiolene [Pt{S2C2(CO2-
Me)2}(PPh3)2] (Eq. 2) [6].
Investigations of the reactions of low-valent transition
metal compounds with elemental selenium or tellurium are
rare [1,2]. We are interested in the use of such reactions for
the preparation of metal polychalcogenides, andthereactivity
of the products towards activated alkynes to yield diseleno-
lenes or ditellurolenes. These are the selenium and tellurium
analogues of dithiolenes, which already have a variety of
applications in materials chemistry [3]. The incorporation of
heavier chalcogen atoms is an attractive synthetic targetsince
this should lead to a smaller HOMO–LUMO gap, and an
increase in the strength of intermolecular interactions in the
solid state.
The platinum(0) and palladium(0) complexes
[M(PPh3)4] and [M(dppe)2] react with sulfur at room tem-
perature, to yield both tetrasulfides [MS4L2] and dinuclear
disulfides [M2S2L4], depending on the conditions (Eq. 1)
[4,5].
CH2 Cl2
[PtS4 (PPh3)2 ]qMeO2 CC^CCO2 Me ™
D
(2)
[Pt{S2 C2(CO2 Me)2}(PPh3)2]
We have previously reported the results of the reactions of
[M(PPh3)4] with selenium. Whilst only decomposition was
observed for MsPd, when MsPt the product is the dinu-
clear diselenide [Pt2(m-Se)2(PPh3)4] [7], which reacts
further with dichloromethane to yield a novel methane-
diselenolate complex (Eq. 3) [8]. No reaction was observed
between [M(PPh3)4] (MsPd, Pt) and tellurium.
Benzene
[Pt(PPh3)4 ]qS8
™
RT
(1)
(3)
We have now studied the analogous reactions of
[M(dppe)2] (MsPd, Pt) and find significant differences
from our work with [M(PPh3)4].
[Pt2(m-S)2(PPh3)4]q[PtS4(PPh3)2]
* Corresponding author. Tel.: q44-1792-295273; fax: q44-1792-
295747; e-mail: c.p.morley@swan.ac.uk
0277-5387/00/$ - see front matter q2000 Elsevier Science Ltd All rights reserved.
PII S0277-5387(00)00303-X
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2. Results and discussion
Coupling to 31P could not be resolved. Compound 1b behaves
as a 1:2 electrolyte in dichloromethane solution.
The platinum compound [Pt(dppe)2] reacts with vitreous
selenium in a visually similar manner. The product isolated
after extraction of the residue with dichloromethane is,
however, in this case the polyselenide [PtSe4(dppe)] (2)
(Eq. 5).
Heating a toluene solution containing [Pd(dppe)2] with
an excess of powdered vitreous selenium to reflux overnight
leads to dissolution of some of the selenium, and formation
of a brown–black precipitate. This may be isolated by filtra-
tion and purified by treatment with triphenylphosphine,
which reacts with any selenium still present. The residue is
insoluble in all common organic solvents, but, on the basis
of microanalysis, infrared and visible spectroscopy may be
identified as [Pd2(m-Se)2(dppe)2] (1a), or a polymeric
form thereof (Eq. 4a). It is notable that compound 1a, unlike
the analogous compound containing platinum and triphenyl-
phosphine (see above), does not appear to react with
dichloromethane.
Carrying out the reaction of [Pd(dppe)2] with selenium
at lower temperature (858C) leads to a different product.
Filtration of the reaction mixture and extraction of the residue
with dichloromethane leads to the isolation of compound 1b,
which has been identified as the salt [Pd3(m3-Se)2-
(dppe)3]Cl2 (Eq. 4b).
Toluene
[Pt(dppe)2 ]qSex ™ [PtSe4(dppe)]qdppeSe2
(5)
D
2
The crystal structure of compound 2 has been determined
by X-ray diffraction (Fig. 1). One molecule of the recrystal-
lisation solvent (dichloromethane) wasincorporatedperfour
formula units. Selected bond lengths and angles are listed in
Table 1. The platinum atom is approximately square planar
coordinated. There is, however, a significant distortion of the
coordination geometry towards tetrahedral, as indicated by
the deviations of the donor atoms from the least-squaresplane
˚
through the PtSe2P2 unit: Se(1), y0.04 A; Se(4), q0.04
˚
˚
˚
A; P(1), q0.30 A; P(2), y0.27 A. This is presumably in
part brought about by the need to accommodate the obtuse
angle subtended by the polyselenide ligand at the Pt atom,
Se(1)–Pt–Se(2) (98.18), the bite angle of the chelating
diphosphine being relatively fixed. A similar distortion has
been noted in [Pt(Se4)2]2y [16]. Preliminary extended
Toluene
[Pd(dppe)2 ]qSex ™ [Pd2(m-Se)2(dppe)2]qdppeSe2
D
1a
(4a)
¨
Huckel calculations indicate that electronic factors (relating
to the bonding in the Se42y fragment) are also important in
determining the observed geometry. The Pt–Se and Pt–P
bond lengths are similar to those reported previously: e.g.
(4b)
Sulfido species of the type [M3(m3-S)2(PR3)6]2q have
been reported for: MsNi, R3sEt3 [9]; MsPd, R3sMe3
or MePh2 [10]; MsPt, R3sMe2Ph [4,11]. Analogous
selenides are known only for MsNi [12,13]. They are usu-
ally prepared, either directly or indirectly, via nucleophilic
attack of the bridging chalcogenide ligands in [M2(m-
E)2(PR3)4] (EsS or Se) on cis-[MCl2(PR3)2]. In the case
of compound 1b, the mechanism is presumably similar, with
the [PdCl2(dppe)] being generated in situ by the action of
dichloromethane on an unidentified intermediate.
Compound 1b has been characterised by microanalysis,
NMR, UV–Vis and IR spectroscopy, and by mass spectrom-
etry. It is a brown microcrystalline air-stable solid, readily
soluble in polar organic solvents. An intense cluster of peaks
is observed in the FAB mass spectrum, corresponding to the
ion [Pd3(m3-Se)2(dppe)3Cl]q. The 77Se resonance is at
unusually high field (y41 ppm), but chemical shifts for
triply bridging selenides are known to cover a wide range,
i.e. from 796 ppm for [CoFe2(m3-Se)(h-C5H5)(CO)6]
[14] to y483 ppm for [Fe2Pt(m3-Se)(CO)6(PPh3)2][15].
Fig. 1. Molecular stucture of compound 2 in [PtSe4(dppe)]P0.25CH2Cl2.
Table 1
˚
Selected bond lengths (A) and angles (8) for [PtSe4(dppe)]P0.25CH2Cl2
Pt–P(1)
Pt–Se(1)
Se(1)–Se(2)
Se(3)–Se(4)
2.246(5)
2.445(3)
2.352(3)
2.338(4)
Pt–P(2)
Pt–Se(4)
Se(2)–Se(3)
2.242(5)
2.448(2)
2.303(4)
P(1)–Pt–Se(1)
Se(4)–Pt–P(2)
89.19(16) Se(1)–Pt–Se(4)
87.69(15) P(2)–Pt–P(1)
98.09(8)
86.31(20)
Pt–Se(1)–Se(2)
Se(2)–Se(3)–Se(4)
105.93(10) Se(1)–Se(2)–Se(3)
97.50(13) Se(3)–Se(4)–Pt
97.13(12)
104.34(11)
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753
˚
˚
2.426 (av.) A and 2.282 (av.) A, respectively, in
[Pt(Se2CH2)(PPh3)2] [8]. There is an alternation amongst
the Se–Se distances in the polyselenide ligand, with Se(2)–
ever, react with [PdCl2(dppe)] under the same conditions,
the starting material being recovered largely unchanged in
this case.
˚
Se(3) being the shortest(byabout0.04A). Thisisacommon
THF
feature in the structures of tetraselenide complexes [17].
Compound 2 is a red crystalline, air-stable solid, soluble
in a wide range of organic solvents. It has been further char-
acterised by microanalysis, NMR, UV–Vis and IR spectros-
copy, and by mass spectrometry. The colour of compound 2
is associated with the tail of an intense UV absorption
(lmaxs260 nm) which has significant intensity up toawave-
length of approximately 470 nm.
[PtCl2 (dppe)]qLi2 Sex ™[PtSe4 (dppe)]qLiCl
(6)
D
2
Tellurium is not as reactive as selenium in this system. No
change is observed on heating a mixture of [Pd(dppe)2] and
tellurium powder for a prolonged period in toluene under
reflux. [Pt(dppe)2] does react with tellurium, but a tetratel-
luride analogous to compound 2 is not formed. Treatment of
a toluene solution of [Pt(dppe)2]withanexcessofpowdered
tellurium leads to the eventual precipitation of a yellow solid.
Filtration of the reaction mixture and extraction of the residue
with dichloromethane yields compound 3, identified as
[Pt3(m3-Te)2(dppe)3]Cl2 (Eq. 7).
Only a single broad resonance at 640 ppm is observed in
the 77Se NMR spectrum. This is surprising, as a-Se and b-
Se generally have quite different chemical shifts in tetra-
selenide complexes. For example, the 77Se NMR spectrum
of [Pt(Se4)2]2y has peaks at 680 and 790 ppm [16]. It may
be that the resonance for the metal-bound selenium atoms in
compound 2 is not observed as a result of the broadening due
to coupling to 31P and 195Pt. The satellite structure of the 31
P
resonance for compound 2 is shown in Fig. 2(a). The inner
lines are due to coupling to 13C. It has not been possible to
analyse this spectrum completely, as too few of the eight lines
expected for each AA9X pattern have been observed, but the
presence of coupling to at least one 77Se is clear.
(7)
Compound 2 may also be prepared by the action of a
polyselenide solution on [PtCl2(dppe)] (Eq. 6). This
method avoids the formation of dppe diselenide, which must
be separated from the product in the reaction of [Pt(dppe)2]
with selenium, and proceeds in comparable yield. A tetra-
furan (THF) solution of lithium polyselenide does not, how-
Compound 3 is analogous to the triethylphosphine deriv-
ative [Pt3(m3-Te)2(PEt3)6][PF6]2, previously reported by
Dahl and co-workers [18]. It is presumably formed by the
same mechanism as the tripalladium diselenide (1b) via
[Pt2(m-Te)2(dppe)2] and [PtCl2(dppe)]. Compound 3 is a
yellow microcrystalline solid, readily soluble inpolarorganic
solvents. It has been characterised by microanalysis, NMR,
UV–Vis and IR spectroscopy, and by mass spectrometry.The
electronic spectrum of compound 3 is similar to that of com-
pound 2 in having three absorption maxima in the ultraviolet
region; the difference in colour arises because absorption
attenuates more rapidly at higher wavelengths. An intense
cluster of peaks is observed in the FAB mass spectrum, cor-
responding to the ion [Pt3(m3-Te)2(dppe)3Cl]q, and, like
compound 1b, it behaves as a 2:1 electrolyte in dichlorome-
thane solution. In contrast to the selenium-containing com-
pound, however, compound 3 is prone to decomposition in
solution, depositing tellurium after a few hours at room tem-
perature or above.
The satellite structure of the 31P resonance for compound
3 is shown in Fig. 2(b). Coupling to 125Te is clearly visible.
The spectrum is, however, deceptively simple. This is the A
and A9 part of an A3A93X system: simulation using estimated
values for the coupling constants (based on data for compa-
rable compounds) shows that it consists of a total of 46 lines.
The 31P resonance is significantly further upfield (ds41.4
ppm), and the platinum–phosphorus coupling constant
(3147 Hz) much greater than those for the mononuclear
tetrachalcogenides [PtE4(dppe)] (EsS: ds49.6 ppm,
1J(195Pt–31P)s2809 Hz; EsSe (2): ds47.1 ppm,
Fig. 2. Satellite structure of 31P resonance for compounds 2 (a) and 3 (b).
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M.R. Lewtas et al. / Polyhedron 19 (2000) 751–756
1J(195Pt–31P)s2805 Hz). The same trend is also evident
from a comparison of the chemical shifts of the tripalladium
diselenide (1b) (50.9 ppm) and [PdS4(dppe)] (57.2 ppm).
cm3) was heated to 858C for 18 h. The product was collected
by filtration, washed with toluene and extracted into dichlo-
romethane. Removal of the solvent by evaporation under
reduced pressure left a crystalline brown solid.
1
The magnitude of J(195Pt–31P) for compound 3 is similar
to that observed in the analogous complexes [Pt3(m3-
Te)2(PEt3)6][PF6]2 (3238 Hz) [18] and [Pt3(m3-S)2-
(PMe2Ph)6][BF4]2 (3202 Hz) [11].
The reactions of the polyselenide (2) with activated
alkynes to yield diselenolenes are currently under study and
the results will be reported separately [19].
Yield: 0.03 g, 52%. M.p. 3428C. Anal. Found: C, 50.7; H
1
4.21. C78H72Cl2P6Pd3Se2 requires: C, 53.7; H, 4.16%. H
NMR: d 7.34 (m, 36H), 7.07 (m, 24H), 2.49 (m, 12H). 13
C
NMR: d 132.9 [J(13C–31P) not resolved], 131.7, 129.6
[average J(13C–31P) 23 Hz], 128.9 [J(13C–31P) not
resolved], 26.6 [J(13C–31P) not resolved]. 31P NMR: d 50.9.
77Se NMR: d y41 [J(77Se–31P) not resolved]. UV–Vis
(CH2Cl2), lmax (´, dm3 cmy1 moly1): 230 (55000), 280
(35000), 300 (31000), 360 (20000), 370 (16000), 470
(1500) nm. IR (KBr disk) (cmy1): n 3056s, 2960m, 2928s,
1620m, 1482m, 1434vs, 1307w, 1186w, 1101s, 1026m,
998m, 876m, 820m, 746m, 705s, 691vs, 531vs, 480s. MS:
m/z 1707 [{MyCl}q].
3. Experimental
All reactions were performed using standard Schlenk
techniques and pre-dried solvents under an atmosphere of
dinitrogen. 1H and 13C NMR spectra: Bruker AC400, tetra-
methylsilane as internal standard. 31P and 77Se NMR spectra:
Bruker WM250, 85% phosphoric acid or dimethyl selenide
as external standard. IR spectra: Perkin-Elmer 1725X. UV–
Vis spectra: Perkin-Elmer Lambda 9. Mass spectra were
recorded by the EPSRC Mass Spectrometry Centre, using
fast atom bombardment (FAB). Values of m/z quoted are
for isotopomers containing 35Cl, 80Se, 106Pd, or 195Ptasappro-
priate; expected isotope distribution patterns were observed.
Elemental analyses were performed by the AnalyticalService
of the University of Wales, Cardiff.
3.3. Bis(diphenylphosphino)ethane(tetraselenido-Se, Se)-
platinum (2)
(a) A mixture of [Pt(dppe)2] (0.25 g, 0.25 mmol) and
powdered vitreous selenium (0.20 g, 2.5 mmol) in toluene
(50 cm3) was heated under reflux for 5 h. After cooling
overnight, the product was collected by filtration, washed
with toluene and extracted into dichloromethane. Removal
of the solvent by evaporation under reduced pressure left a
crystalline red solid. Yield: 0.16 g (70%).
(b) A mixture of LiBEt3H (3.0 cm3 of a 1 M solution in
THF, 3.0 mmol) and powdered vitreous selenium (0.43 g,
5.4 mmol) in THF (150 cm3) was heated under reflux for 1
h. A hot suspension of [PtCl2(dppe)] (0.66 g, 1.0 mmol) in
THF (150 cm3) was added to the purple solution of Li2Sex
thus formed, and the mixture was heated under reflux for a
further 2 h. The solvent was removed by evaporation under
reduced pressure. The black residue was Soxhlet extracted
with dichloromethane to yield an orange solution. Removal
of the solvent in vacuo left a red crystalline solid, which was
washed with cold toluene and dried. Yield: 0.64 g (70%).
M.p. 2078C (dec.). Anal. Found: C, 34.1; H, 2.83.
C26H24P2PtSe4 requires: C, 34.3; H, 2.66%. 1H NMR: d 7.71
(m, 8H), 7.43 (m, 12H), 2.41 (m, 4H). 13C NMR: d 133.2
[average J(13C–31P) 6 Hz], 131.7, 129.9 [average J(13C–
31P) 31 Hz], 128.8 [average J(13C–31P) 6 Hz], 29.0 [eight
peaks]. 31P NMR: d 47.1 [J(195Pt–31P) 2805 Hz]. 77Se
NMR: d 640 [J(77Se–31P) not resolved]. IR (KBr disk)
(cmy1): n 3050m, 2963m, 2927m, 1639m, 1618m, 1483m,
1435s, 1408m, 1385m, 1308w, 1262m, 1187w, 1160w,
1103s, 1027m, 998w, 879w, 820m, 749m, 715m, 706m,
691s, 657w, 617w, 533vs, 484m, 405w. UV–Vis (CH2Cl2),
lmax (´, dm3 cmy1 moly1) 230 (36000), 250 (7500), 260
(7000) nm. MS: m/z 913 [Mq].
Bis[bis(diphenylphosphino)ethane]palladium [20,21]
and -platinum [22] and [bis(diphenylphosphino)ethane]-
dichloroplatinum [23] were prepared by literature
procedures.
3.1. Bis[bis(diphenylphosphino)ethane]di-m2-
selenidodipalladium (1a)
A mixture of [Pd(dppe)2] (0.45 g, 0.5 mmol) and pow-
dered vitreous selenium (0.40 g, 5.0 mmol) in toluene (50
cm3) was heated under reflux for 18 h. After this time a
microcrystalline brown–black solid had been formed. This
was collected by filtration and purified by treatment with
triphenylphosphine (13.1 g, 50 mmol) in toluene under
reflux for 2 days. The product was a brown–black solid,
insoluble in all common solvents.
Yield 0.24 g, 82%. M.p. 3008C (dec.). Anal. Found: C,
51.9; H, 4.11. C52H48P4Pd2Se2 requires: C, 53.5; H, 4.14%.
Vis (diffuse reflectance), absorption across the whole of the
visible region apart from 435–450, 480–495 and 585–700
nm. IR (KBrdisk) (cmy1):n3044m, 2963m, 2920s,2851m,
1637m, 1436m, 1401w, 1385m, 1262w, 1188s, 1102vs,
1052m, 879w, 818m, 694m, 569w, 531s, 490w.
3.2. Tris[bis(diphenylphosphino)ethane]di-m3-
selenidotripalladium dichloride (1b)
3.4. Tris[bis(diphenylphosphino)ethane]di-m3-
telluridotriplatinum dichloride (3)
A mixture of [Pd(dppe)2] (0.09 g, 0.1 mmol) and pow-
dered vitreous selenium (0.79 g, 1.0 mmol) in toluene (50
A mixture of [Pt(dppe)2] (0.25 g, 0.25 mmol) and tel-
lurium powder (0.32 g, 2.5 mmol) in toluene (50 cm3) was
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755
heated under reflux for 3 h. The solution became deep red in
colour and some of the tellurium gradually dissolved. After
cooling overnight, a yellow solid had been deposited. The
product was collected by filtration, washed with toluene and
extracted into dichloromethane to yield an orange solution.
Removal of the solvent by evaporation under reduced pres-
sure left a yellow oily solid, which could be further purified
by passage of a dichloromethane solution through a bed of
Celite. The product was unstable in solution and decomposed
after a few hours at room temperature with the deposition of
tellurium.
Yield: 0.09 g, 51%. M.p. 1688C (dec.). Anal. Found: C,
53.4; H 3.11. C78H72Cl2P6Pt3Te2 requires: C, 44.5; H, 3.44%.
1H NMR: d 7.43 (m, 12H), 7.35 (m, 24H), 7.18 (m, 24H),
2.54 (m, 12H). 13C NMR: d 132.8 [average J(13C–31P) 5
Hz], 131.8, ipso-C not observed, 128.8 [average J(13C–31P)
5 Hz], 27.7 [average J(13C–31P) 20 Hz]. 31P NMR: d 41.4
[J(195Pt–31P) 3147 Hz]. UV–Vis (CH2Cl2), lmax (´, dm3
cmy1 moly1): 230 (21000), 250 (13000), 260 (11000)
nm. IR (KBr disk) (cmy1): n 3056s, 2960m, 2928s, 1637vs,
1619vs, 1435m, 1385m, 1262w, 1103s, 803w, 749m, 692vs,
669s, 618s, 534vs, 483vs. MS: m/z 2071 [{MyCl}q].
Crystals diffracted poorly; the sample used for the final data
collection was cut from a bigger piece. Lattice parameters
were determined from the settings of 24 reflections at
12FuF14. No decay of intensities was observed at data
collection time. An empirical correction for absorption was
applied to the data, with DIFABS [24] (correction factors
range 0.677–1.419). Structure solution was by direct meth-
ods with SIR97 [25], and Fourier cycles with SHELXL-93
[26], which was also used for structure refinements. The
final refinement cycles were performed against F2 with all
non-hydrogen atoms anisotropic and with hydrogen atoms in
calculated positions. Phenyl rings were treatedasrigidgroups
with idealized geometry; refinement of the light atoms para-
meters suffered from the poor quality of the data (probably
caused in part by disordered solvent) and from the presence
of heavy atoms. The presence of dichloromethane solvate
molecules disorderly arranged about a 2-fold axis was sug-
gested by difference Fouriers. The occupancy factor of the
site was assigned based on the results of refinements in which
the solvent molecule, geometrically constrained throughout,
was applied an overall temperature factor.
Supplementary data
3.5. X-ray crystallography
Crystallographic data for compound 2 have been deposited
with the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge, CB2 1EZ, UK (fax: q44-1223-336033;
e-mail: deposit@ccdc.cam.ac.uk), and are available on
request quoting the deposition number CCDC 136385.
Details of the crystal structure determination of compound
2 are given in Table 2. Measurements were carried out at
room temperature with an Enraf-Nonius CAD4 diffracto-
meter, using graphite-monochromated Mo Ka radiation.
Table 2
Crystallographic data for [PtSe4(dppe)]P0.25CH2Cl2 (2)
Acknowledgements
Formula
C26.25H24.50Cl0.50P2PtSe4
M
930.55
orthorhombic
Pbnb (alternative setting of Pccn, no. 56)
We thank EPSRC for the provision of a research student-
ship to M.R.L., Johnson Matthey plc for the gift of palladium
Crystal system
Space group
a (A)
b (A)
c (A)
U (A )
`
˚
˚
˚
˚
and platinum salts, and the Ministero dell’Universita e della
15.513(6)
17.881(8)
20.442(14)
5670(5)
8
2.180
0.30=0.40=0.60
10.26
Ricerca Scientifica e Tecnologica for financial support to
M.d.V.
3
Z
Dc (g cmy3
)
References
Crystal size (mm)
m (mmy1
)
[1] S.M. Stuczynski, Y.U. Kwon, M.L. Steigerwald, J. Organomet. Chem.
449 (1993) 167.
[2] S.J. Hibble, D.A. Rice, M.J. Almond, K.A.H. Mohammed, S.P.Pearse,
J.R. Sagar, J. Mater. Chem. 2 (1992) 1237.
˚
Radiation
Data collected
Scan type
2u Range (8)
Reflections collected
Unique reflections
Mo Ka (ls0.71069 A)
hG0, kG0, y1FlF20
v–2u
5–50
¨
[3] U.T. Muller-Westerhoff, B. Vance, in: G. Wilkinson (Ed.), Compre-
4435
4084 (Rints0.035)
hensive Coordination Chemistry, vol. 2, Pergamon, Oxford, 1988,
p. 595.
Unique observed reflections, 2123
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Howarth, Heteroat. Chem. 6 (1995) 519.
with I)2s(I)
No. parameters
R1 (observed reflections)
R1 (all unique reflections)
wR2
Goodness of fit
Largest features (max., min.) 1.00, y1.65
in final DF map (e A
278 (201 restraints)
0.059
0.169
0.144
1.046
y3
˚
)
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