Preparation, properties and structures of the first series of organometallic Pt(II) and Pt(IV) complexes with stibine co-ligands

Article abstract of DOI:10.1039/b514019f

The planar Pt(II) monomers [PtMe₂(L-L)] and [(PtMe ₂)₂(L′-L′)₂] dimers (L-L = R ₂Sb(CH₂)₃SbR₂, o-C₆H ₄(CH₂SbMe₂)₂; L′-L′ = R₂SbCH₂SbR₂; R = Me or Ph) are obtained in good yield via reaction of [PtMe₂(SMe₂)₂] with L-L or L′-L′ in benzene. The Pt(iv) stibines, [PtMe₃(L-L)I] (L-L = R₂Sb(CH₂)₃SbR₂, o-C ₆H₄(CH₂SbMe₂)₂ or 2 × SbPh₃, SbMePh₂ or SbMe₂Ph) are obtained by treatment of [PtMe₃I] with L-L in chloroform. These represent the first series of stable Pt(iv) stibine complexes. All of the products have been characterised by ¹H, ¹³C{¹H}, ¹⁹⁵Pt NMR spectroscopy, electrospray mass spectrometry and analysis. Crystal structure determinations on [PtMe₃{R₂Sb(CH₂) ₃SbR₂}I], [PtMe₃{o-C₆H ₄(CH₂SbMe₂)₂}I] and [PtMe ₃(SbPh₃)₂I] confirm the distorted octahedral environment at Pt, with fac Me groups and mutually cis Sb donor atoms. The Sb-Pt-Sb angle in the seven-membered chelate ring of the o-C₆H ₄(CH₂SbMe₂)₂ complex is ca. 96°, compared to <90°in the complexes with six-membered chelates. The C ₁-distibines R₂SbCH₂SbR₂ afford only the dinuclear [(PtMe₃)₂(μ-R₂SbCH ₂SbR₂)(μ-I)₂] in which the stibine ligand and two I atoms bridge two Pt atoms giving an edge sharing bioctahedral geometry which has been confirmed by a crystal structure analysis. The Pt(ii) species undergo oxidative addition with MeI to give the corresponding Pt(iv) species, while the Pt(iv) species reductively eliminate ethane upon thermolysis. The Royal Society of Chemistry 2006.

Full text of DOI:10.1039/b514019f

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PAPER
www.rsc.org/dalton | Dalton Transactions
Preparation, properties and structures of the first series of organometallic
Pt(II) and Pt(IV) complexes with stibine co-ligands
Michael D. Brown, William Levason, Gillian Reid* and Michael Webster
Received 4th October 2005, Accepted 9th November 2005
First published as an Advance Article on the web 14th December 2005
DOI: 10.1039/b514019f
The planar Pt(II) monomers [PtMe2(L–L)] and [(PtMe2)2(Lꢀ–Lꢀ)2] dimers (L–L = R2Sb(CH2)3SbR2,
o-C6H4(CH2SbMe2)2; Lꢀ–Lꢀ = R2SbCH2SbR2; R = Me or Ph) are obtained in good yield via reaction of
[PtMe2(SMe2)2] with L–L or Lꢀ–Lꢀ in benzene. The Pt(IV) stibines, [PtMe3(L–L)I] (L–L = R2Sb(CH2)3-
SbR2, o-C6H4(CH2SbMe2)2 or 2 × SbPh3, SbMePh2 or SbMe2Ph) are obtained by treatment of
[PtMe3I] with L–L in chloroform. These represent the first series of stable Pt(IV) stibine complexes.
1
All of the products have been characterised by 1H, 13C{ H}, 195Pt NMR spectroscopy, electrospray
mass spectrometry and analysis. Crystal structure determinations on [PtMe3{R2Sb(CH2)3SbR2}I],
[PtMe3{o-C6H4(CH2SbMe2)2}I] and [PtMe3(SbPh3)2I] confirm the distorted octahedral environment at
Pt, with fac Me groups and mutually cis Sb donor atoms. The Sb–Pt–Sb angle in the seven-membered
chelate ring of the o-C6H4(CH2SbMe2)2 complex is ca. 96◦, compared to <90◦ in the complexes with
six-membered chelates. The C1-distibines R2SbCH2SbR2 afford only the dinuclear [(PtMe3)2(l-
R2SbCH2SbR2)(l-I)2] in which the stibine ligand and two I atoms bridge two Pt atoms giving an edge
sharing bioctahedral geometry which has been confirmed by a crystal structure analysis. The Pt(II)
species undergo oxidative addition with MeI to give the corresponding Pt(IV) species, while the Pt(IV)
species reductively eliminate ethane upon thermolysis.
although no spectroscopic or structural data are included.10 The
Introduction
photochemical activity of the purported [PtRꢀ2(Ph2SbCH2SbPh2)]
(Rꢀ = various substituted phenyl ligands) has been reported,
Phosphines are incorporated as co-ligands in many transition
metal based homogeneous catalysts and correspondingly, the
although again the parent compounds have not been characterised
either spectroscopically or structurally.11
chemistry of these ligands with organometallic fragments has
been investigated intensively over many years and much is known
regarding the steric and electronic influences of the ligands on
the metal ion and associated reaction chemistry. In contrast,
with the exception of metal carbonyl species, the organometal-
lic chemistry of transition metal stibine complexes has been
much less studied.1,2 Key exceptions are the very elegant work
of Werner and co-workers who have demonstrated that these
species promote different reaction chemistry reflecting the very
different electronic properties of the stibine ligands.3–6 Further,
[Ni(CH2C(Me)CH2)(SbPh3)3]+ is reported to be an efficient styrene
polymerisation catalyst.7
The data available on transition metal stibine complexes clearly
show that these prefer low or medium oxidation state metal
centres. A small number of Pt(IV) stibines of general formula cis-
[PtCl4(distibine)] have been isolated in the solid state, but decom-
pose immediately in solution with chlorination of the stibine and
reduction of the Pt centre.8 With the exception of one example from
our own preliminary work in the area,9 there are no Pt(IV) stibine
complexes with alkyl co-ligands. There is an early report concern-
ing the preparation of a small number of planar Pt(II) dialkyl
and diaryl complexes involving SbPh3 ligands, cis-[PtR2(SbPh3)2]
(R = Me, Ph, o/m/p-C6H4Me), by treatment of [PtR2(C8H8)]
with two molar equivalents of SbPh3 in refluxing benzene,
In this paper we describe a systematic study of the coordination
of the distibine ligands R2Sb(CH2)3SbR2, R2SbCH2SbR2 (R =
Me or Ph) and o-C6H4(CH2SbMe2)2 with methyl Pt(II) and Pt(IV)
reagents, including their syntheses and spectroscopic properties.
Selected examples with monostibines are also prepared for
comparative purposes. Crystal structures of five representative
examples involving Pt(IV) are described which provide the basis
for comparisons of the Pt–Sb bonding in these species.
The synthesis and reaction chemistry of Pt(II)–dimethyl and
Pt(IV)–trimethyl fragments with a wide range of phosphine and
arsine ligands has been studied in detail,12 and hence the data on
these compounds provide a useful comparison against the new
stibine complexes reported here.
Results and discussion
Pt(II) Complexes
The light yellow Pt(II) dimethyl complex, [PtMe2{Ph2Sb(CH2)3-
SbPh2}] was obtained in good yield through treatment of
[PtMe2(cod)] with one molar equivalent of the distibine in toluene
solution for ca. 12 h at room temperature. The 1H NMR
spectrum shows clear evidence for coordination of the distibine
to the PtMe2 fragment, displaying a single Pt–Me resonance
2
1
with JPt–H 85 Hz. The 13C{ H} NMR spectrum shows the
School of Chemistry, University of Southampton, Highfield, Southampton,
UK SO17 1BJ. E-mail: gr@soton.ac.uk; Fax: +44 (0)23 80593781;
Tel: +44 (0)23 80593609
1
d(Me) resonance at −3.63 ppm with JPtC = 716 Hz, together
with resonances due to the coordinated distibine. There is no
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residual cod evident in the spectra of the product, indicating
clean substitution. The JPt–C coupling constant in the distibine
C1 linked distibines, the dimeric [(PtMe2)2(Lꢀ–Lꢀ)2] (Lꢀ–Lꢀ
Me2SbCH2SbMe2 or Ph2SbCH2SbPh2) in high yield as light yellow
solids (or in the case of Me2Sb(CH2)3SbMe2, a pale yellow oil)—
Scheme 1.
=
1
complex is significantly larger than in the directly comparable
[PtMe2{Ph2P(CH2)3PPh2}] (595 Hz),13 consistent with the stibine
being lower in the trans influence series than the phosphine. The
[PtMe2{Ph2Sb(CH2)3SbPh2}] shows a single 195Pt resonance at
−4804 ppm. Attempts to obtain the corresponding [PtMe2(L–L)]
(L–L = Me2Sb(CH2)3SbMe2 or o-C6H4(CH2SbMe2)2) by reaction
of [PtMe2(cod)] and L–L in toluene at room temperature for a
prolonged period (>24 h) resulted in only partial substitution of
the cod. Heating the reactions led to decomposition, with the
solutions turning dark brown/black. Hence, an alternative route
utilising the much more labile [PtMe2(SMe2)2] was employed.
While reaction of [PtMe2(SMe2)2] with Ph2Sb(CH2)3SbPh2 in
CH2Cl2 solution produces [PtMe2{Ph2Sb(CH2)3SbPh2}] cleanly
and in high yield (NMR evidence), the other distibines did not
react cleanly in CH2Cl2 solution. However, room temperature
reaction of a benzene solution of [PtMe2(SMe2)2] with distibine
gives the corresponding mononuclear [PtMe2(L–L)] (L–L =
Me2Sb(CH2)3SbMe2, o-C6H4(CH2SbMe2)2) or, with the short
The electrospray mass spectra (MeCN) show the major species
to be loss of a Me group from the parent complex, [P −
Me]+, in each case, providing strong supporting evidence for
the monomeric and dimeric formulations respectively. Even in
benzene solution slow decomposition was observed. This was
most notable for [(PtMe2)2(Ph2SbCH2SbPh2)2] which undergoes
decomposition quite rapidly even in the solid state, hinder-
ing analytical measurements. Spectroscopically (Table 1) these
compounds are similar to [PtMe2{Ph2Sb(CH2)3SbPh2}] above,
showing similar Pt–C and Pt–H couplings within the dialkyl–
1
Pt unit, and with the 13C{ H} NMR shift for the SbMe units
appearing to low frequency of Me4Si. The 195Pt NMR shifts are
all ca. −4800 ppm, some 400 to 500 ppm to low frequency of the
Pt(IV) complexes, [PtMe3I(distibine)] below. Little platinum-195
NMR data on stibine complexes are available; however d(195Pt) for
[PtCl2{Ph2Sb(CH2)3SbPh2}] and [PtCl2{Me2Sb(CH2)3SbMe2}]
Scheme 1
Table 1 Selected NMR spectroscopic data for Pt(II) and Pt(IV) stibine complexes
1
Complex
d(13C{ H}) (ppm)
1JPtC/Hz
d(195Pt) (ppm)
Pt(II)
[PtMe2{Ph2Sb(CH2)3SbPh2}]
[PtMe2{Me2Sb(CH2)3SbMe2}]a
[PtMe2{o-C6H4(CH2SbMe2)2}]a
[(PtMe2)2(Me2SbCH2SbMe2)2]a
−3.63 PtMe
−4.98 PtMe
−3.85 PtMe
−3.96 PtMe
716
−4804
−4722
−4687
−4802
b
726
711
Pt(IV)
[PtMe3{PhSb(CH2)3SbPh2}I]
−3.17 (1C) PtMe trans I
5.31 (2C) PtMe trans Sb
−6.20 (1C) PtMe trans I
1.85 (2C) PtMe trans Sb
−6.20 (1C) PtMe trans I
3.82 (2C) PtMe trans Sb
5.53 (2C) PtMe trans I
8.27 (1C) PtMe trans Sb
4.17 (2C) PtMe trans I
12.78 (1C) PtMe trans Sb
−3.72 (1C) PtMe trans I
10.43 (2C) PtMe trans Sb
−5.04 (1C) PtMe trans I
7.59 (2C) PtMe trans Sb
−5.87 (1C) PtMe trans I
5.16 (2C) PtMe trans Sb
616
575
628
553
611
562
655
684
692
571
606
542
611
566
643
564
−4381
−4491
−4384
−4360
−4509
−4380
−4419
−4471
[PtMe3{Me2Sb(CH2)3SbMe2}I]
[PtMe3{o-C6H4(CH2SbMe2)2}I]
[(PtMe3)2(l-Ph2SbCH2SbPh2)(l-I)2]
[(PtMe3)2(l-Me2SbCH2SbMe2)(l-I)2]
[PtMe3(SbPh3)2I]
[PtMe3(SbMePh2)2I]
[PtMe3(SbMe2Ph)2I]
a Spectra recorded in d6-benzene; others in CDCl3. b Pt–C coupling unclear.
1668 | Dalton Trans., 2006, 1667–1674
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are −4556 and −4553 respectively, some 250 ppm to high
the proton and/or carbon-13 NMR spectra, e.g. in [(PtMe3)2(l-
Me2SbCH2SbMe2)(l-I)2] where three bond Pt–H couplings of 3–
4 Hz are clearly evident on the SbMe and SbCH2 resonances in
the 1H NMR spectrum.
frequency of the Pt(II) methyl analogues in this work.14
The Pt(IV) species each show a single 195Pt NMR resonance
at ca. −4400 ppm, some 400 ppm to high frequency of the
corresponding dimethyl–Pt(II) species (Table 1). The 195Pt NMR
shifts for related methyl Pt(II) and -(IV) phosphines and arsines
show similar trends with oxidation state, although the nature of
the Group 15 donor atom type has a significant effect. Thus, the
d(195Pt) values for [PtMe3I(PMe2Ph)2] and [PtMe3I(SbMe2Ph)2]
respectively are −4277 ppm and −4471 ppm, while those for
[PtMe3I(PMePh2)2] and [PtMe3I(SbMePh2)2] are −4227 and
−4582 ppm respectively,16 consistent with incorporation of the
heavier Sb atom in place of P. The d(195Pt) values for the dinuclear
[(PtMe3)2(l-R2SbCH2SbR2)(l-I)2] (R = Ph, −4360; R = Me,
−4509 ppm) are not significantly shifted from the mononuclear
[PtMe3I(L–L)], despite the different donor set (Me3I2Sb in the
former vs. Me3ISb2 in the latter). This suggests that replacement
of a heavy I ligand by another heavy atom (Sb) has a negligible
electronic effect. This so-called ‘heavy atom effect’ has been seen
before in e.g. [PtI3(SbMe3)]− (I3Sb coordination; d195Pt = −5642)
and [PtI2(SbMe3)2] (I2Sb2 coordination; d195Pt = −5815).17 The
1JPt–C coupling constants in this series of Pt(IV) stibines are ca. 550
to 650 Hz, the larger couplings usually occurring for the Me ligand
trans to iodine as expected.
Detailed studies have been undertaken by Puddephatt and
co-workers and others on the chemistry of alkyl–Pt complexes
with phosphine ligands. They have shown that oxidative addition
of MeI to dimethyl–Pt(II) phosphine species invariably yield
the corresponding [PtMe3I(diphosphine)]. These trimethyl–Pt(IV)
phosphine complexes then readily undergo reductive elimination
of ethane upon thermolysis.18 We have also found that treating
a solution of [PtMe2{Me2Sb(CH2)3SbMe2}] with MeI in d6-
benzene leads to essentially quantitative conversion (by 1H NMR
spectroscopy) to [PtMe3I{Me2Sb(CH2)3SbMe2}]. Also, thermo-
gravimetric analysis of [PtMe3I(SbPh3)2] shows a mass loss at
ca. 170 ◦C consistent with reductive elimination of ethane. Thus,
despite the anticipated fragility of the Sb–C linkages, the stibine
ligands do support both Pt(II) and Pt(IV) centres, readily giving
the products in high yields. These can then undergo oxidative
addition/reductive elimination reaction chemistry. This contrasts
with previous work on the Pt(IV) tetrachloro distibine complexes,
[PtCl4(distibine)], which are extremely unstable. The difference in
Pt(IV) Complexes
Reaction of [PtMe3I] with one molar equivalent of L–L in refluxing
CHCl3 solution affords pale yellow solutions from which the
neutral, highly soluble Pt(IV) complexes [PtMe3(L–L)I] (L–L =
R2Sb(CH2)3SbR2; R = Me or Ph; o-C6H4(CH2SbMe2)2 or L–
L = 2 × SbPh3, SbPh2Me or SbPhMe2) and the iodo-bridged
[(PtMe3I)2(R2SbCH2SbR2)] dinuclear species were obtained in
high yield as air-stable powdered solids—Scheme 2.
The formation of the ligand bridged dinuclear species
[(PtMe3)2(l-R2SbCH2SbR2)(l-I)2] is presumably a consequence of
the short methylene linkage between the Sb centres, which hinders
chelation. This is the product isolated even when a 1 : 1 Pt :
distibine ratio is used. The related [(PtMe3)2(l-Ph2PCH2PPh2)(l-
I)2] has been described by Puddephatt and co-workers.15
The products are extremely soluble in organic solvents and
hence isolation of powdered solids required trituration of the
oily materials with a small volume of cold hexane. For the
Pt(IV) complexes with chelating distibines electrospray mass
spectrometry (MeCN) generally shows that the only significant
species in each case are [PtMe(L–L)]+ and [PtMe(L–L)(MeCN)]+.
However, for those complexes with either monodentate stibines
or bridging distibines, the only significant fragments evident by
electrospray mass spectrometry are [PtMe3(MeCN)n]+ (n = 1, 2
and 3), indicating easy cleavage of the Pt–Sb bonds in these systems
under the MS conditions.
The NMR spectroscopic data for these, the first stable Pt(IV)
stibine complexes, are summarised in Table 1. The general trends in
the chemical shifts and coupling constants replicate those observed
previously for phosphine and arsine derivatives.16 The H NMR
spectra for these compounds each show two Pt–Me resonances
consistent with the above formulations. The JPt–H values are in
1
2
accord with the trends seen in phosphine and arsine complexes
derived from [PtMe3I], with larger couplings occurring for the Me
ligand trans to the iodo ligand. Two SbMe resonances are evident
both in the 1H and 13C{ H} NMR spectra for the Me-substituted
1
distibine complexes, consistent with the distinct environments
experienced by the SbMe groups, one oriented towards a Me
ligand, the other towards the iodo ligand. In some cases the 195Pt
coupling through the quadrupolar antimony centres is evident in
Scheme 2
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◦
◦
˚
˚
Table 2 Selected bond lengths (A) and angles ( ) for [PtMe3{Ph2Sb-
(CH2)3SbPh2}I]
Table 3 Selected bond lengths (A) and angles ( ) for [PtMe3{Me2Sb-
(CH2)3SbMe2}I]a
Pt1–C30
Pt1–C28
Pt1–Sb2
Sb1–C1
Sb1–C13
Sb2–C22
2.069(13)
2.106(12)
2.6342(11)
2.120(12)
2.162(12)
2.136(11)
Pt1–C29
Pt1–Sb1
Pt1–I1
Sb1–C7
Sb2–C16
Sb2–C15
2.098(11)
2.6025(11)
2.7830(11)
2.122(12)
2.109(13)
2.159(11)
Pt1–C5
Pt1–Sb1
Sb1–C1
Sb1–C3
2.081(9)
2.6217(7)
2.117(7)
2.133(6)
Pt1–C6
Pt1–I1
Sb1–C2
2.145(6)
2.7850(11)
2.130(6)
C5–Pt1–C6
C5–Pt1–Sb1
C6a–Pt1–Sb1
C5–Pt1–I1
Sb1–Pt1–I1
C1–Sb1–C3
C1–Sb1–Pt1
C3–Sb1–Pt1
86.9(3)
C6–Pt1–C6a
C6–Pt1–Sb1
Sb1–Pt1–Sb1a
C6–Pt1–I1
C1–Sb1–C2
C2–Sb1–C3
C2–Sb1–Pt1
84.2(4)
177.11(18)
89.63(3)
90.54(18)
100.0(3)
98.3(3)
93.91(19)
93.08(19)
176.6(3)
88.524(16)
100.4(3)
116.3(2)
117.08(19)
C30–Pt1–C29
C29–Pt1–C28
C29–Pt1–Sb1
C30–Pt1–Sb2
C28–Pt1–Sb2
C30–Pt1–I1
87.7(5)
84.4(5)
92.8(3)
92.2(4)
95.1(3)
179.2(3)
91.5(4)
87.29(4)
99.8(5)
120.8(3)
117.4(3)
101.8(5)
117.4(3)
117.0(3)
C30–Pt1–C28
C30–Pt1–Sb1
C28–Pt1–Sb1
C29–Pt1–Sb2
Sb1–Pt1–Sb2
C29–Pt1–I1
Sb1–Pt1–I1
C1–Sb1–C7
C7–Sb1–C13
C7–Sb1–Pt1
C16–Sb2–C22
C22–Sb2–C15
C22–Sb2–Pt1
88.0(5)
91.8(3)
177.2(3)
179.5(3)
87.68(3)
92.8(4)
88.79(3)
98.4(4)
102.4(5)
114.7(3)
98.3(4)
121.0(2)
C28–Pt1–I1
Sb2–Pt1–I1
1
2
a Symmetry operation: a = x, − y, z.
C1–Sb1–C13
C1–Sb1–Pt1
C13–Sb1–Pt1
C16–Sb2–C15
C16–Sb2–Pt1
C15–Sb2–Pt1
100.5(4)
118.5(3)
stability is therefore attributed to significantly stronger ligand field
effects in the Pt–methyl complexes reported here.
Crystal structures
Crystal structure determinations have been undertaken on five
representative examples of the Pt(IV) stibine complexes to pro-
vide unambiguous assignment of their geometries and to allow
comparisons between these, the first structurally characterised
examples of stibine complexes involving a formally Pt(IV) centre,
and literature examples incorporating Pt(II) centres. The struc-
ture of [PtMe3{Ph2Sb(CH2)3SbPh2}I] shows (Fig. 1, Table 2)
a distorted octahedral Pt(IV) centre coordinated to three fac
Me groups, one I ligand and two Sb atoms from a chelating
distibine. [PtMe3{Me2Sb(CH2)3SbMe2}I] adopts a very similar
arrangement (Fig. 2, Table 3), although in this species the Pt
centre, C4, C5 and I1 occupy a crystallographic mirror plane
which bisects the distibine ligand. Very similar geometries are
observed for [PtMe3{o-C6H4(CH2SbMe2)2}I] (Fig. 3, Table 4) and
[PtMe3(SbPh3)2I] (Fig. 4, Table 5).
Fig. 2 View of the structure of [PtMe3{Me2Sb(CH2)3SbMe2}I] with
numbering scheme adopted. H atoms are omitted for clarity. Ellipsoids
are shown at the 50% probability level. There is a mirror plane passing
1
through Pt1, I1, C4 and C5. Symmetry operation: a = x, − y, z.
2
Fig. 3 View of the structure of [PtMe3{o-C6H4(CH2SbMe2)2}I] with
numbering scheme adopted. H atoms are omitted for clarity. Ellipsoids
are shown at the 50% probability level.
Fig. 1 View of the structure of [PtMe3{Ph2Sb(CH2)3SbPh2}I] with
numbering scheme adopted. H atoms are omitted for clarity. Ellipsoids
are shown at the 50% probability level.
ficantly longer than in the Pt(II) distibines,19 e.g. [PtCl2{o-
˚
C6H4(CH2SbMe2)2}] (2.4860(7), 2.4931(8) A) and [Pt{o-
C6H4(CH2SbMe2)2}2]2+ (2.5690(8)–2.5802(8) A)—although of
˚
The Sb–Pt(IV) bond distances in all of the chelated distib-
course the higher coordination number in the Pt(IV) species and
˚
ine complexes lie in the range 2.6025(11)–2.6342(11) A, signi-
the strong trans influence of the Me groups will both have a
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◦
Table 4 Selected bond lengths (A) and angles (◦) for [PtMe3{o-
a
˚
˚
Table 5 Selected bond lengths (A) and angles ( ) for [PtMe3(SbPh3)2I]
C6H4(CH2SbMe2)2}I]
Pt2–C78
Pt2–C77
Pt2–Sb4
Sb3–C40
Sb3–C46
Sb4–C58
2.098(9)
2.5679(14)b
2.6551(7)
2.137(8)
2.143(9)
2.132(9)
Pt2–C76
Pt2–I2
2.102(9)
2.6302(12)b
2.6651(7)
2.143(8)
2.131(8)
2.149(8)
Pt1–C14
Pt1–C15
Pt1–Sb1
Sb1–C1
Sb1–C3
Sb2–C11
2.078(5)
2.113(5)
2.6204(5)
2.119(5)
2.154(4)
2.138(5)
Pt1–C13
Pt1–Sb2
Pt1–I1
Sb1–C2
Sb2–C12
Sb2–C10
2.108(5)
2.6052(4)
2.7808(5)
2.146(5)
2.126(5)
2.144(4)
Pt2–Sb3
Sb3–C52
Sb4–C70
Sb4–C64
C78–Pt2–C76
C76–Pt2–C77
C76–Pt2–I2
85.3(4)
87.0(4)b
85.5(4)b
171.4(3)
95.31(3)b
91.7(3)
C78–Pt2–C77
C78–Pt2–I2
C77–Pt2–I2
C76–Pt2–Sb4
I2–Pt2–Sb4
C76–Pt2–Sb3
I2–Pt2–Sb3
87.4(4)b
86.8(4)b
C14–Pt1–C13
C13–Pt1–C15
C13–Pt1–Sb2
C14–Pt1–Sb1
C15–Pt1–Sb1
C14–Pt1–I1
C15–Pt1–I1
Sb1–Pt1–I1
C1–Sb1–C3
C1–Sb1–Pt1
C3–Sb1–Pt1
C12–Sb2–C10
C12–Sb2–Pt1
C10–Sb2–Pt1
84.8(2)
89.2(2)
C14–Pt1–C15
C14–Pt1–Sb2
C15–Pt1–Sb2
C13–Pt1–Sb1
Sb2–Pt1–Sb1
C13–Pt1–I1
Sb2–Pt1–I1
C1–Sb1–C2
C2–Sb1–C3
C2–Sb1–Pt1
C12–Sb2–C11
C11–Sb2–C10
C11–Sb2–Pt1
86.9(2)
170.81(4)b
86.7(3)
94.71(16)
176.95(15)
175.98(14)
95.246(11)
94.21(15)
83.901(15)
100.4(2)
100.50(19)
120.18(14)
101.9(2)
C78–Pt2–Sb4
C77–Pt2–Sb4
C78–Pt2–Sb3
C77–Pt2–Sb3
Sb4–Pt2–Sb3
C40–Sb3–C52
C52–Sb3–C46
C52–Sb3–Pt2
C70–Sb4–C58
C58–Sb4–C64
C58–Sb4–Pt2
88.42(14)
96.50(15)
87.11(15)
178.33(16)
94.41(15)
84.562(11)
98.93(19)
113.82(15)
119.35(12)
100.71(18)
113.54(14)
117.24(13)
89.46(3)b
174.3(3)
99.21(3)b
88.07(3)b
96.48(2)
98.1(3)
C40–Sb3–C46
C40–Sb3–Pt2
C46–Sb3–Pt2
C70–Sb4–C64
C70–Sb4–Pt2
C64–Sb4–Pt2
98.1(3)
115.3(2)
124.0(2)
100.2(3)
111.4(2)
120.6(2)
99.6(3)
117.1(2)
98.8(3)
101.3(3)
120.7(2)
100.7(2)
119.84(15)
a Bond lengths and angles for the second molecule involving Pt1, I1, Sb1,
Sb2 and C1–C39 are similar and also have disorder in the trans I1–Pt1–
C fragment. b Disordered group I2/C77A–Pt2–C77/I2A with chemically
unreliable bond lengths and angles (see text). This is most marked in the
Pt2–C77 bond length when compared with other Pt–C distances.
open by up to ca. 8◦ upon coordination to a medium oxidation
state transition metal centre, a consequence of the rehybridisation
which takes place at antimony upon coordination to a metal
centre.20 Comparison of the data reported vs. the C–Sb–C angles
in known Pt(II) stibines show that the angles are essentially
unaffected by the change in oxidation state.
The structure of [(PtMe3I)2(Ph2SbCH2SbPh2)] confirms (Fig. 5,
Table 6) that the distibine ligand bridges two PtMe3 fragments,
with two bridging iodo ligands completing the distorted octahe-
dral coordination environment at each Pt centre, giving an edge
shared bioctahedral structure. This is consistent with the solution
structure deduced from the NMR spectroscopic data. The Pt–Sb
˚
bond distances of 2.6530(5) and 2.6793(5) A are longer (by ca.
Fig. 4 View of the structure of one of the crystallographically independent
molecules of [PtMe3(SbPh3)2I] with numbering scheme adopted (the other
molecule in the asymmetric unit is essentially indistinguishable). H atoms
are omitted for clarity. Ellipsoids are shown at the 50% probability level.
There is disorder in the I2–Pt2–C77 unit (see text). The figure shows the
major component.
˚
0.05 A) than those in the mononuclear species above. This may
significant effect on d(Pt–Sb). The Sb–Pt–Sb angles in the Pt(IV)
stibine complexes reflect the different chelate ring sizes, with the
o-C6H4(CH2SbMe2)2 ligand (seven-membered ring chelate) giving
a wide angle of 95.246(11)◦, whereas the Sb–Pt–Sb angles within
the six-membered chelates are <90◦. The same trend is seen in
the non-bonded Sb · · · Sb distances within the chelates. Thus,
˚
d(Sb · · · Sb) is ca. 0.17 A greater for the o-C6H4(CH2SbMe2)2
complex vs. the R2Sb(CH2)3SbR2 complexes. The Pt–Sb dista◦nces
˚
(2.6457(7)–2.6656(7) A), Sb–Pt–Sb angles (96.48(2), 96.74(2) ) in
[PtMe3I(SbPh3)2] are similar to those in the wide-angle xylyl–
distibine complex, consistent with the substantial steric require-
ments of the bulky SbPh3 groups in the former.
˚
The Pt–CtransSb distances are all ca. 2.1 A, and longer than
d(Pt–C)trans I, consistent with the stibine exerting a stronger trans
influence than iodide. We have observed previously that the C–Sb–
C angles within the stibine ligands SbPh3 and Ph2SbCH2SbPh2
Fig. 5 View of the structure of [(PtMe3I)2(Ph2SbCH2SbPh2)] with
numbering scheme adopted. H atoms are omitted for clarity. Ellipsoids
are shown at the 50% probability level.
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◦
˚
Table 6 Selected bond lengths (A) and angles ( ) for [(PtMe3I)2(Ph2SbCH2SbPh2)]
Pt1–C2
Pt1–C3
Pt1–I2
Pt2–C30
Pt2–C29
2.057(5)
2.066(6)
2.7929(4)
2.070(6)
2.076(6)
Pt1–C1
Pt1–Sb1
Pt1–I1
Pt2–C31
Pt2–Sb2
2.065(6)
2.6530(5)
2.7979(5)
2.070(6)
2.6793(5)
Pt2–I1
2.7957(4)
2.132(5)
2.139(5)
2.140(5)
Pt2–I2
2.8034(5)
2.136(5)
2.120(5)
2.142(5)
Sb1–C4
Sb1–C16
Sb2–C16
Sb1–C10
Sb2–C17
Sb2–C23
C2–Pt1–C1
C1–Pt1–C3
C1–Pt1–Sb1
C2–Pt1–I2
C3–Pt1–I2
C2–Pt1–I1
C3–Pt1–I1
I2–Pt1–I1
87.7(2)
85.0(2)
C2–Pt1–C3
C2–Pt1–Sb1
C3–Pt1–Sb1
C1–Pt1–I2
Sb1–Pt1–I2
C1–Pt1–I1
Sb1–Pt1–I1
C30–Pt2–C31
C31–Pt2–C29
C31–Pt2–Sb2
C30–Pt2–I1
88.5(2)
C31–Pt2–I1
Sb2–Pt2–I1
C31–Pt2–I2
Sb2–Pt2–I2
89.94(18)
90.224(12)
91.36(18)
85.759(12)
94.184(12)
101.04(19)
100.3(2)
118.30(14)
100.4(2)
93.96(18)
115.89(14)
C29–Pt2–I1
C30–Pt2–I2
C29–Pt2–I2
I1–Pt2–I2
176.42(18)
179.34(17)
95.00(18)
85.556(12)
94.123(12)
99.01(19)
117.90(14)
116.88(14)
100.29(19)
120.13(14)
121.29(14)
93.22(17)
93.66(18)
88.56(17)
90.593(12)
92.92(17)
88.383(12)
88.0(2)
86.5(3)
177.09(18)
94.26(17)
178.38(17)
174.89(18)
94.67(17)
90.99(17)
177.92(18)
85.713(12)
85.1(3)
Pt2–I1–Pt1
Pt1–I2–Pt2
C4–Sb1–C10
C10–Sb1–C16
C10–Sb1–Pt1
C17–Sb2–C16
C16–Sb2–C23
C16–Sb2–Pt2
C4–Sb1–C16
C4–Sb1–Pt1
C16–Sb1–Pt1
C17–Sb2–C23
C17–Sb2–Pt2
C23–Sb2–Pt2
C30–Pt2–C29
C30–Pt2–Sb2
C29–Pt2–Sb2
94.88(17)
93.34(18)
be a consequence of the short C1-linked distibine ligand having
difficulty in spanning the two Pt centres. The rather open Sb1–
C16–Sb2 angle (116.2(2)◦) is also consistent with this.
Required for [C29H32PtSb2]: C, 42.5; H, 3.9. Found: C, 42.6; H,
3.8%. 1H NMR: 1.05 (s, 6H, Me 2JPtH = 85 Hz), 2.40–2.15 (m, 6H,
1
CH2), 7.1–7.6 (m, 20H, Ph). 13C{ H} NMR: −3.63 (2C, Me, 1JPtC
=
716 Hz), 18.57 (2C, CH2Sb), 23.99 (1C, CH2CH2CH2), 129.21,
130.04, 131.41, 135.91 (Ph).
Conclusions
Method b. [Me2Pt(SMe2)2] (0.060 g, 0.17 mmol) and
Ph2Sb(CH2)3SbPh2 (0.1 g, 0.17 mmol) were dissolved in dry CHCl3
(15 cm3) and stirred at RT for 1 h. The excess solvent was removed
under reduced pressure, and the residues were triturated with
hexane to afford a pale yellow solid. This was then dried in vacuo.
These results show that stibine ligands can bond effectively to
organometallic fragments in both high and medium oxidation
states, affording the first series of alkyl Pt(II) and Pt(IV) stibines
which readily undergo oxidative addition of MeI or reductive
elimination of ethane respectively. The high yield formation of
this series of stable trimethyl Pt(IV) stibine complexes contrasts
with the very unstable tetrachloro Pt(IV) species [PtCl4(distibine)].
Further work to examine in more detail the reaction chemistry of
distibine ligands with organometallic reagents is underway—an
area of work very much in its infancy.
1
1H and 13C{ H} NMR spectroscopy as for method a.
[PtMe2{Me2Sb(CH2)3SbMe2}]. [Me2Pt(SMe2)2] (0.060 g,
0.17 mmol) and Me2Sb(CH2)3SbMe2 (0.058 g, 0.17 mmol) were
dissolved in dry C6H6 (5 cm3) and stirred at RT for 15 minutes.
The excess solvent was removed under reduced pressure, and the
residues were triturated with hexane to afford a pale yellow oil
which was dried in vacuo (yield: 65%). ES+ MS (MeCN): 555
([195PtMe{Me2121Sb(CH2)3123SbMe2}]+ 556). 1H NMR (C6D6):
Experimental
3
0.70 (s, 12H, SbMe, JPtH = 7 Hz), 1.14 (m, 6H, CH2), 1.48 (s,
Mass spectra were run by positive ion electrospray (MeCN
1
6H, Me, 2JPtH = 83 Hz). 13C{ H} NMR (C6D6): −6.1 (4C, SbMe),
1
solution) using a VG Biotech platform. H NMR spectra were
−4.98 (2C, Me), 15.26 (2C, CH2Sb), 24.47 (1C, CH2CH2CH2).
recorded in CDCl3 (unless otherwise stated) using a Bruker AV300
1
1
spectrometer. 13C{ H} and 195Pt{ H} NMR spectra (ppm) were
recorded in CDCl3 (unless otherwise stated), using a Bruker
DPX400 spectrometer operating at 100.6 or 85.62 MHz respec-
tively and are referenced to TMS and external 1 mol dm−3
Na2[PtCl6] respectively. Microanalyses were undertaken by the
University of Strathclyde microanalytical service.
[PtMe2{o-C6H4(CH2SbMe2)2}]. Method as for [PtMe2-
{Me2Sb(CH2)3SbMe2}]. Pale yellow solid (yield: 63%). Required
for [C14H26PtSb2]·0.5C6H14: C, 30.2; H, 4.9. Found: C, 30.3; H,
4.1%. ES+ MS (MeCN): 658 ([195Pt{o-C6H4(CH2121/123SbMe2)2}-
(MeCN)]+ 659), 617 ([195PtMe{o-C6H4(CH2121/123SbMe2)2}]+ 618).
1H NMR (C6D6): 0.73 (s, 12H, SbMe, 3JPtH = 9 Hz), 1.26 (s, 6H,
2
Me, JPtH = 82 Hz), 2.88 (br, 4H, CH2), 6.6–6.9 (m, 4H, Ar–H).
Solvents were dried prior to use and all preparations were
undertaken using standard Schlenk techniques under a N2 at-
mosphere. [PtMe3I]4,21 [PtMe2(cod)],22 [PtMe2(SMe2)2]23 and the
stibine ligands were prepared as described previously.24–26
1
13C{ H} NMR (C6D6): −5.55 (4C, SbMe), −3.85 (2C, Me, 1JPtC
=
726 Hz), 23.15 (2C, CH2).
[(PtMe2)2(Ph2SbCH2SbPh2)2]. Method as for [PtMe2{Me2-
Sb(CH2)3SbMe2}]. Pale yellow solid (yield: 70%). Required for
[C54H56Pt2Sb4]·0.5C6H6: C, 42.2; H, 3.7. Found: C, 42.4; H,
3.6%. ES+ MS (MeCN): 1569 ([195Pt2Me3(Ph2121SbCH2123SbPh2)2]+
Platinum(II) compounds
[PtMe2{Ph2Sb(CH2)3SbPh2}]
1
1567), 1341 ([195PtMe(Ph2121SbCH2123SbPh2)2]+ 1342). H NMR
Method a. [Me2Pt(cod)] (0.042 g, 0.125 mmol) and Ph2Sb-
(CH2)3SbPh2 (0.075 g, 0.125 mmol) were dissolved in toluene
(15 cm3) and stirred under N2 for 12 h. The resulting yellow
solution was filtered, reduced in volume to ∼1 cm3 and hexane
(10 cm3) was added to precipitate a solid. The solution was
decanted off and the yellow solid dried in vacuo (yield: 70%).
(C6D6): 1.43 (s, 6H, Me, 2JPtH = 82 Hz), 2.20 (br, 2H, CH2), 6.9–
7.4 (m, 20H, Ph).
[(PtMe2)2(Me2SbCH2SbMe2)2]. Method as for [PtMe2{Me2-
Sb(CH2)3SbMe2}]. Pale yellow solid (yield: 55%). ES+ MS
(MeCN): 1071 ([195Pt2Me3(Me2121SbCH2123SbMe2)2]+ 1071), 845
1672 | Dalton Trans., 2006, 1667–1674
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1
([195PtMe(Me2121SbCH2123SbMe2)2]+ 846). H NMR (C6D6): 0.95
(s, 12H, SbMe, 3JPtH = 6 Hz), 1.17 (s, 6H, Me, 2JPtH = 80 Hz), 1.27
1
(s, 2H, CH2). 13C{ H} NMR (C6D6): −5.89 (4C, SbMe), −3.96
(2C, Me, 1JPtC = 711 Hz), −3.46 (1C, CH2).
Platinum(IV) compounds
[PtMe3{Ph2Sb(CH2)3SbPh2}I]. Me3PtI (0.065 g, 0.177 mmol)
and Ph2Sb(CH2)3SbPh2 (0.105 g, 0.177 mmol) were dissolved
in dry CHCl3 (20 cm3) under argon and refluxed for 4 h. The
light yellow solution was then pumped to dryness in vacuo to
give a light yellow waxy solid which was triturated with hexane
to produce a light yellow powder (yield: 80 mg, 50%). Required
for [C30H35IPtSb2]·0.5CHCl3: C, 35.9; H, 3.5. Found: C, 36.4; H,
4.0%. 1H NMR: 1.20 (s, 3H, Me trans I, 72 Hz), 1.70 (s, 6H, Me
trans Sb, 65 Hz), 2.10–2.80 (m, 6H, CH2), 7.20–7.75 (m, 20H,
1
Ph). 13C{ H} NMR: −3.17 (C, Me trans I, 616 Hz), 5.31 (2C, Me
trans Sb, 575 Hz), 18.30 (2C, SbCH2), 24.12 (1C, CH2CH2CH2),
127.23–136.90 (Ph).
[PtMe3{Me2Sb(CH2)3SbMe2}I]. Method as above. Yellow
solid (yield: 45%). Required for [C10H27IPtSb2]: C, 16.8; H, 3.8.
Found: C, 16.3; H, 3.9%. ES+ MS (MeCN): 596 ([195PtMe-
{Me2121Sb(CH2)3123SbMe2}(MeCN)]+ 597), 555 ([195PtMe{Me2
-
121
Sb(CH2)3123SbMe2}]+ 556). 1H NMR: 0.97 (s, 6H, SbMe), 1.07 (s,
3H, Me trans I, 78 Hz), 1.27 (s, 6H, SbMe), 1.45 (s, 6H, Me trans
1
Sb, 65 Hz), 2.0 (m, 6H, CH2). 13C{ H} NMR: −11.22 (2C, SbMe),
−7.58 (2C, SbMe), −6.20 (C, Me trans I, 628 Hz), 1.85 (2C, Me
trans Sb, 553 Hz), 14.31 (2C, SbCH2), 24.30 (1C, CH2CH2CH2).
[PtMe3{o-C6H4(CH2SbMe2)2}I]. Method as above. Yellow
solid (yield: 60%). Required for [C15H29IPtSb2].1 C6H14: C, 24.9;
4
1
H, 4.1. Found: C, 24.7; H, 3.7%. H NMR: 0.78 (s, 6H, SbMe),
0.82 (s, 3H, Me trans I, 76 Hz), 1.20 (s, 6H, Me trans Sb, 65 Hz),
1.31 (s, 6H, SbMe), 3.12 (m, 2H, CH2), 4.08 (d, 2H, CH2), 6.88–
1
7.05 (m, 4H, o-C6H4). 13C{ H} NMR: −11.57 (2C, SbMe), −6.20
(C, Me trans I, 611 Hz), −6.05 (2C, SbMe), 3.82 (2C, Me trans Sb,
562 Hz), 21.37 (2C, SbCH2), 126.16, 130.53, 136.45 (o-C6H4).
[(PtMe3I)2(Ph2SbCH2SbPh2)]. Method as above, using a Pt :
Ph2SbCH2SbPh2 ratio of 2 : 1. Yellow solid (yield: 50%). Required
for [C31H40I2Pt2Sb2]: C, 28.6; H, 3.1. Found: C, 29.4; H, 3.1%. 1H
NMR: 1.36 (s, 12H, Me trans I, 76 Hz), 2.25 (s, 6H, Me trans Sb,
1
69 Hz), 2.92 (2H, CH2), 7.10–7.40 (m, 20H, Ph). 13C{ H} NMR:
5.53 (2C, Me trans I, 655 Hz), 8.27 (C, Me trans Sb, 694 Hz), 14.70
(1C, SbCH2), 138.8–128.8 (Ph).
[(PtMe3I)2(Me2SbCH2SbMe2)]. Method as above, using a Pt :
Me2SbCH2SbMe2 ratio of 2 : 1. Yellow solid (yield: 55%). Required
for [C11H32I2Pt2Sb2].1/3 C6H14: C, 14.4; H, 3.4. Found: C, 14.6; H,
1
3.6%. H NMR: 1.18 (s, 12H, SbMe, 3 Hz), 1.23 (s, 12H, Me
trans I, 76 Hz), 2.04 (s, 6H, Me trans Sb, 67 Hz), 2.28 (2H, CH2,
1
4.5 Hz). 13C{ H} NMR: −6.91 (4C, SbMe), −0.05 (C, SbCH2),
4.17 (2C, Me trans I, 925 Hz), 12.78 (1C, Me trans Sb, 571 Hz).
Method as above, giving a light yellow oil (yield: 70%). 1H
NMR: 0.93 (s, 3H, Me trans I, 71 Hz), 1.21 (s, 6H, SbMe), 1.43 (s,
1
6H, Me trans Sb, 66 Hz), 7.30–7.40 (m, 10H, Ph). 13C{ H} NMR:
−5.87 (1C, Me trans I, 643 Hz), −2.98 (2C, SbMe), 5.16 (2C, Me
trans Sb, 564 Hz), 129.23, 129.92, 134.73 (Ph).
[PtMe3(SbMePh2)2I]. Method as above. Yellow solid (yield:
55%). Required for [C29H35IPtSb2]: C, 36.7; H, 3.7. Found: C,
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36.2; H, 3.7%. 1H NMR: 1.08 (s, 3H, Me trans I, 71 Hz), 1.38 (s,
3H, SbMe), 1.55 (s, 6H, Me trans Sb, 67 Hz), 7.10–7.40 (m, 20H,
3 H. Werner, Angew. Chem., Int. Ed., 2004, 43, 938.
4 H. Werner, D. A. Ortmann and O. Gevert, Chem. Ber., 1996, 129,
411.
5 H. Werner, C. Grunwald, P. Steinert, O. Gevert and J. Wolf,
J. Organomet. Chem., 1998, 565, 231.
1
Ph). 13C{ H} NMR: −5.05 (1C, Me trans I, 611 Hz), −1.73 (1C,
SbMe), 7.60 (2C, Me trans Sb, 566 Hz), 129.0–136.9 (Ph).
6 M. Mattias, J. Wolf, M. Laubender, M. Teichert, D. Stalke and H.
Werner, Chem. Eur. J., 1997, 3, 1442.
7 M. Jiminez-Tenorio, M. C. Puerta, I. Salcedo, P. Valerga, S. L.
Costa, P. T. Gomes and K. Mereiter, Chem. Commun., 2003,
1168.
8 D. J. Gulliver, W. Levason and K. G. Smith, J. Chem. Soc., Dalton
Trans., 1981, 2153.
[PtMe3(SbPh3)2I]. Method as above. Yellow solid (yield: 70%).
Required for [C39H39IPtSb2]: C, 43.6; H, 3.7. Found: C, 43.4; H,
3.4%. 1H NMR: 1.27 (s, 3H, Me trans I, 70 Hz), 1.83 (s, 6H, Me
1
trans Sb, 68 Hz), 7.05–7.50 (m, 30H, Ph). 13C{ H} NMR: −3.72
(1C, Me trans I, 606 Hz), 10.43 (2C, Me trans Sb, 542 Hz), 129.3–
9 M. D. Brown, W. Levason, G. Reid and M. Webster, unpublished
work.
136.9 (Ph).
10 C. R. Kistner, J. D. Blackman and W. C. Harris, Inorg. Chem., 1969, 8,
X-Ray crystallography
2165.
11 H.-A. Brune, R. Klotzbucher and G. Schmidtberg, J. Organomet.
Chem., 1989, 371, 113.
Details of the crystallographic data collection and refinement
parameters are given in Table 7. Pale yellow crystals of
[PtMe3{Ph2Sb(CH2)3SbPh2}I], [PtMe3{Me2Sb(CH2)3SbMe2}I],
[PtMe3{oC6H4(CH2SbMe2)2}I], [PtMe3(SbPh3)2I] and [(PtMe3I)2-
(Ph2SbCH2SbPh2)] were obtained by liquid diffusion of hexane
into a CH2Cl2 solution of the compound. Data collection used
a Nonius Kappa CCD diffractometer (T = 120 K) and with
12 For examples see: F. R. Hartley, in Comprehensive Organometallic
Chemistry I, ed. G. Wilkinson, F. G. A. Stone and E. W. Abel,
Pergamon, Oxford, 1982, vol. 6, ch. 39, p. 421; G. K. Anderson,
in Comprehensive Organometallic Chemistry II, ed. G. Wilkinson,
F. G. A. Stone and E. W. Abel, Pergamon, Oxford, 1995, vol. 9,
ch. 7, p. 391.
13 S. Hietkamp, D. J. Stufkens and K. Vrieze, J. Organomet. Chem., 1979,
169, 107.
˚
graphite-monochromated Mo-Ka X-radiation (k = 0.71073 A).
14 E. G. Hope, W. Levason and T. Kemmitt, Inorg. Chim. Acta, 1986, 115,
187.
Structure solution and refinement were largely routine,27,28 except
for [PtMe3(SbPh3)2I] both molecules of which revealed some
disorder of the trans-I–Pt–Me unit. This was modelled using
partial atom positions, with the sum of the occupancies of the two
I and two C components each being one. Distinct partial C atoms
and partial I atoms could not be identified, hence these units were
refined with identical atomic coordinates and atomic displacement
parameters. Consequently the Pt–I and Pt–C distances in the
trans-I–Pt–C units are weighted averages, and should not be
used in comparative studies. The H atoms associated with the
disordered Me groups were not included in the final structure
factor calculation.
15 M. Rashidi, Z. Fakhroeian and R. J. Puddephatt, J. Organomet. Chem.,
1990, 406, 261.
16 J. D. Kennedy, W. McFarlane, R. J. Puddephatt and P. J. Thompson,
J. Chem. Soc., Dalton Trans., 1976, 874.
17 P. L. Goggin, R. J. Goodfellow, S. R. Haddock, B. F. Taylor and I. R. H.
Marshall, J. Chem. Soc., Dalton Trans., 1976, 459.
18 For
examples
see:
P.
P.
Brown,
R.
J.
Puddephatt and C. E. E. Upton, J. Chem. Soc., Dalton Trans.,
1974, 2457; M. Crespo and R. J. Puddephatt, Organometallics, 1987,
6, 2548; S. S. M. Ling, I. R. Jobe, L. Manojlovic-Muir, K. W. Muir
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1674 | Dalton Trans., 2006, 1667–1674
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