Interplay of bite angle and cone angle effects. A comparison between o-C6H4(CH2PR2)(PR′ 2) and o-C6H4(CH2PR 2)(CH2PR′2) as ligands for Pd-catalysed ethene hydromethoxycarbonylation

Article abstract of DOI:10.1039/c2dt31913f

The following unsymmetrical diphosphines have been prepared: o-C ₆H₄(CH₂P^tBu₂)(PR ₂) where R = P^tBu₂ (L_3a); PCg (L_3b); PPh₂ (L_3c); P(o-C₆H ₄CH₃)₂ (L_3d); P(o-C ₆H₄OCH₃)₂ (L_3e) and o-C₆H₄(CH₂PCg)(PCg) (L_3f) where PCg is 6-phospha-2,4,8-trioxa-1,3,5,7-tetramethyladamant-6-yl. Hydromethoxycarbonylation of ethene under commercially relevant conditions has been investigated in the presence of Pd complexes of each of the ligands L _3a-f and the results compared with those obtained with the commercially used o-C₆H₄(CH₂P ^tBu₂)₂ (L_1a). The Pd complexes of the bulkiest ligands L_3a, L_3b and L_3f are highly active catalysts but the Pd complexes of L_3c, L_3d and L_3e are completely inactive. The crystal structures of the complexes [PtCl₂(L_1a)] (1a) and [PtCl₂(L _3a)] (2a) have been determined and show that the crystallographic bite angles and cone angles are greater for L_1a than L_3a. Solution NMR studies show that the seven-membered chelate in 1a is more rigid than the six-membered chelate in 2a. Treatment of [PtCl(CH₃)(cod)] with L_3a-f gave [PtCl(CH₃)(L_3a-f)] as mixtures of 2 isomers 3a-f and 4a-f. The ratio of the products 4:3 ranges from 100:1 to 1:20, the precise proportion is apparently governed by a balance of two competing factors, steric bulk and the antisymbiotic effect. The palladium complexes [PdCl(CH₃)(L_3b)] (5b/6b) and [PdCl(CH ₃)(L_3c)] (5c/6c) react with labelled ¹³CO to give the corresponding acyl species [PdCl(¹³COCH₃)(L _3b)] (7b/8b) and [PdCl(¹³COCH₃)(L _3c)] (7c/8c). Treatment of [PdCl(¹³COCH₃)(L)] with MeOH gave CH₃¹³COOMe rapidly when L = L_3b but very slowly when L = L_3c paralleling the contrasting catalytic activity of the Pd complexes of these two ligands. The Royal Society of Chemistry 2013.

Full text of DOI:10.1039/c2dt31913f

View Online / Journal Homepage
Dynamic Article Links
Dalton
Transactions
Cite this: DOI: 10.1039/c2dt31913f
www.rsc.org/dalton
PAPER
Interplay of bite angle and cone angle effects. A comparison between
o-C6H4(CH2PR2)(PR′2) and o-C6H4(CH2PR2)(CH2PR′2) as ligands for
Pd-catalysed ethene hydromethoxycarbonylation†‡
Tamara Fanjul,a Graham Eastham,b Joelle Floure,a Sebastian J. K. Forrest,a Mairi F. Haddow,a
Alex Hamilton,a Paul G. Pringle,*a A. Guy Orpena and Mark Waughb
Received 21st August 2012, Accepted 3rd October 2012
DOI: 10.1039/c2dt31913f
The following unsymmetrical diphosphines have been prepared: o-C6H4(CH2PtBu2)(PR2) where
R = PtBu2 (L3a); PCg (L3b); PPh2 (L3c); P(o-C6H4CH3)2 (L3d); P(o-C6H4OCH3)2 (L3e) and
o-C6H4(CH2PCg)(PCg) (L3f) where PCg is 6-phospha-2,4,8-trioxa-1,3,5,7-tetramethyladamant-6-yl.
Hydromethoxycarbonylation of ethene under commercially relevant conditions has been investigated in
the presence of Pd complexes of each of the ligands L3a–f and the results compared with those obtained
with the commercially used o-C6H4(CH2PtBu2)2 (L1a). The Pd complexes of the bulkiest ligands L3a, L3b
and L3f are highly active catalysts but the Pd complexes of L3c, L3d and L3e are completely inactive. The
crystal structures of the complexes [PtCl2(L1a)] (1a) and [PtCl2(L3a)] (2a) have been determined and
show that the crystallographic bite angles and cone angles are greater for L1a than L3a. Solution NMR
studies show that the seven-membered chelate in 1a is more rigid than the six-membered chelate in 2a.
Treatment of [PtCl(CH3)(cod)] with L3a–f gave [PtCl(CH3)(L3a–f)] as mixtures of 2 isomers 3a–f and
4a–f. The ratio of the products 4 : 3 ranges from 100 : 1 to 1 : 20, the precise proportion is apparently
governed by a balance of two competing factors, steric bulk and the antisymbiotic effect. The palladium
complexes [PdCl(CH3)(L3b)] (5b/6b) and [PdCl(CH3)(L3c)] (5c/6c) react with labelled 13CO to give the
corresponding acyl species [PdCl(13COCH3)(L3b)] (7b/8b) and [PdCl(13COCH3)(L3c)] (7c/8c). Treatment
of [PdCl(13COCH3)(L)] with MeOH gave CH313COOMe rapidly when L = L3b but very slowly when
L = L3c paralleling the contrasting catalytic activity of the Pd complexes of these two ligands.
are comparable to the commercial catalysts based on L1a in
Introduction
terms of activity and chemoselectively to MeP.7,8 In addition,
The homogeneous palladium catalyst used for the first step (eqn
(1)) of the Lucite Process is based on seven-membered chelates
formed by the bulky o-diphosphinoxylene L1a.1 The bite angle2
of the diphosphine backbone and the P-substituent stereoelectro-
nic effects are key to the activity and chemoselectivity of the
catalyst.3–6 For example, while Pd catalysts based on L1a give
MeP efficiently in greater than 99.9% chemoselectivity, the cata-
lyst based on L2a sluggishly gives ethene/CO co-oligomers and
polyketone.7–9
L1c produces a longer-lived catalyst than L1a and the catalyst
based on L1b outperformed, in terms of activity, both of its sym-
metrical analogues based on L1a and L2b.
ð1Þ
We recently reported that, in the case of o-diphosphinoxy-
lenes, catalysts based on unsymmetrical ligands such as L1b–e
aSchool of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8
1TS, UK. E-mail: paul.pringle@bristol.ac.uk
bLucite International, Wilton Centre, Wilton, Redcar, Cleveland, TS10
4RF, UK
†Electronic supplementary information (ESI) available. CCDC
897390–897398. For ESI and crystallographic data in CIF or other elec-
tronic format see DOI: 10.1039/c2dt31913f
‡Dedicated to Professor David Cole-Hamilton on the occasion of his
retirement and for his outstanding contribution to transition metal
catalysis.
The favourable properties of the Pd catalysts derived from sym-
metrical and unsymmetrical o-diphosphinoxylenes L1a–e, and
This journal is © The Royal Society of Chemistry 2012
Dalton Trans.

View Online
L2b prompted us to explore the performance of the analogous
catalysts based on o-diphosphinotoluenes L3a–f (Chart 1) which
have a smaller bite angle. We report here that some of the
o-diphosphinotoluenes produce outstandingly active and selec-
tive hydromethoxycarbonylation catalysts while others show no
activity at all.
A general mechanism for the hydromethoxycarbonylation cata-
lysed by Pd complexes of unsymmetrical diphosphines is given
in Scheme 1. It shows that at each stage there is a potential bifur-
cation in the mechanism as a result of the geometric isomerism.
In previous articles,7,8 we have proposed that the high chemo-
selectivity of the catalysts derived from the unsymmetrical
o-diphosphinoxylenes L1b–e is due to the kinetic dominance of
the intermediate A1 over its isomer A2 (Scheme 1). This pro-
position was supported by observations made on model
palladium(II) and platinum(II) complexes. It was therefore of
interest to investigate if the coordination chemistry of o-diphos-
phinotoluenes L3a–f would provide insight into some of the
sharply contrasting catalytic performances of the Pd complexes
of these unsymmetrical ligands.
All of the o-diphosphinotoluenes L3a–f are ditopic due to one
donor being an aryl phosphine and the other a benzyl phosphine.
Results and discussion
Ligand synthesis
The diphosphines L3a–f are readily obtained from o-α-dibromo-
toluene (2-bromobenzyl bromide) by the routes summarised in
Scheme 2. Ligands L3a–f are new and have been fully
Chart 1
Scheme 1
Dalton Trans.
This journal is © The Royal Society of Chemistry 2012

View Online
Scheme 2
characterised (see Experimental). The intermediate I is particu-
larly versatile since it can be converted to organolithium or
Grignard reagents or used in Pd-catalysed C–P coupling reac-
tions allowing access to the range of diphosphines L3a–e. Com-
analogues L1c–e (compare Entries 3–5T with 3–5X). What the
three successful o-diphosphinotoluenes have in common, is two,
very bulky P-donors (PtBu2 or PCg). Thus the effect on the cata-
lysis of the smaller bite of the diphosphinotoluenes compared to
the diphosphinoxylenes is non-linear: with relatively small PR2
donors (as in L3c–e), the activity is zeroed whereas with bulky
PR2 donors (as in L3a, L3b and L3f), the catalysts are the most
efficient reported to date under these conditions.11
pound
J is a potentially useful intermediate to ditopic
diphosphines although we have used it only to prepare L3f.
Unlike the analogous o-diphosphinoxylenes, all of the o-diphos-
phinotoluenes have inequivalent P atoms, including L3a and
L3f. In general, two doublets were observed in the 31P NMR
3
spectra with JPP of the order of 5 Hz. Two diastereoisomers
Platinum(II) and palladium(II) coordination chemistry
would be predicted for L3f associated with the chirality of the
PCg moiety10 but only one set of singlets was observed in the
31P NMR spectrum of the purified product, implying that only
one diastereoisomer was present or that the signals for the two
diastereoisomers are coincident.
In order to gauge the stereoelectronic effects of the ligands in
L1a and L3a, the complexes [PtCl2(L1a)] (1a) and [PtCl2(L3a)]
(2a) were prepared and the crystal structures of both determined
(Fig. 1 and 2). The conformation of the 7-membered chelate in
1a is similar to those of other diphosphinoxylene complexes,
putting the phenylene ring almost orthogonal to the PtP2 plane.
The conformation of the 6-membered chelate in 2a (and the
others reported below) is approximately a half-chair and is
defined by the P–M–P–C(1) torsion angle of 25°.
The crystallographically determined bite angle for L1a in 1a is
104° and for L3a in 2a is 97° and the cone angle for L1a in 1a is
276° and for L3a in 2a is 266°. It was noted that when the half
cone angles (θ) around P(1) and P(2) in 2a were measured, there
was no significant difference between the benzyl-PtBu2 and aryl-
PtBu2. The net effect of L1a having a larger bite angle and larger
cone angle than L3a is the squeezing together of the adjacent
ligands: the Cl⋯Cl distance is ca. 3.00 Å in 1a and 3.16 Å in
2a. It might be predicted that a benzyl-PtBu2 would be a better
σ-donor and therefore have a higher trans influence than an aryl-
PtBu2. Consistent with this, in the structure of 2a, the Pt–Cl(1)
distance is slightly longer than Pt–Cl(2). However the difference
Carbonylation catalysis
Ethene hydromethoxycarbonylation to give MeP (eqn (1)) was
carried out with palladium catalysts derived from the o-diphos-
phinotoluenes L3a–f, under the conditions described in the
Experimental section and the results are given in Table 1, along
with those we previously reported8 for the corresponding
o-diphosphinoxylenes for comparison.
Two contrasting observations can be made from the catalysis
data given in Table 1. (1) The o-diphosphinotoluenes L3a, L3b
and L3f significantly outperform their o-diphosphinoxylene ana-
logues in terms of relative rate and match them in their excellent
chemoselectivity (compare Entries 1, 2 and 6T with 1, 2 and
6X). (2) The complexes derived from the mixed PtBu2/PAr2
ligands L3c–e show no detectable catalytic activity which was
unexpected in view of the high performance of their xylene
This journal is © The Royal Society of Chemistry 2012
Dalton Trans.

View Online
Table 1 Pd-catalysed hydromethoxycarbonylation of ethenea
o-diphosphinotoluene
o-diphosphinoxylene analogue8
Entry
Ligand
Selectivity/%
TON
Rel. rate
Entry
Ligand
Selectivity/%
TON
Rel. rate
1T
2T
3T
4T
5T
6T
L3a
L3b
L3c
L3d
L3e
L3f
>99.9
>99.9
—
—
—
29 600
67 300
0
0
1.7
3.8
0
0
0
1X
2X
3X
4X
5X
6X
L1a
L1b
L1c
L1d
L1e
L2b
>99.9
>99.9
99.5
99.5
99.5
17 900
25 600
16 300
32 200
3600
1
1.4
0.9
1.8
0.2
2.2
0
>99.9
66 000
3.7
>99.9
40 200
a The data given in this Table are the average of 2 or more runs. For reaction conditions, see Experimental. TON (in mol mol−1 Pd) were calculated
from the mass gain after 3 h. The selectivity to MeP was measured by GC; the remainder was a mixture of co-oligomers. The relative rates are
calculated from the TON after 3 h and are relative to the values for L1a
.
Fig. 1 Crystal structure of [PtCl2(L1a)] (1a). Selected bond lengths (Å)
and angles (°): Pt(1)–P(1) 2.267(3); Pt(1)–P(2) 2.304(2); Pt(1)–Cl(2)
2.321(4); Pt(1)–Cl(1) 2.362(3); P(1)–C(1) 1.826(12); P(1)–C(9)
1.902(13); P(1)–C(13) 1.909(12); P(2)–C(4) 1.872(10); P(2)–C(17)
1.882(10); P(2)–C(21) 1.920(10); P(1)–Pt(1)–P(2) 104.06(10); P(1)–
Pt(1)–Cl(2) 87.24(14); P(2)–Pt(1)–Cl(1) 89.64(11); Cl(2)–Pt(1)–Cl(1)
79.51(14).
Fig. 3 Crystal Structure of [PtCl2(L3b)] (2b). Selected bond lengths
(Å) and angles (°): Pt(1)–P(1) 2.2562(16); Pt(1)–P(2) 2.2683(15);
Pt(1)–Cl(1) 2.3574(16); Pt(1)–Cl(2) 2.3525(15); P(1)–C(1) 1.836(6);
P(1)–C(8) 1.877(6); P(1)–C(12) 1.907(6); P(2)–C(3) 1.849(6); P(2)–
C(16) 1.892(6); P(2)–C(19) 1.896(5); P(1)–Pt(1)–P(2) 94.07(6); P(1)–
Pt(1)–Cl(2) 88.19(6); P(2)–Pt(1)–Cl(1) 95.87(6); Cl(2)–Pt(1)–Cl(1)
82.87(6); torsion C(1)–P(1)–Pt(1)–P(2) 20.9.
(ca. 0.02 Å) is less than the difference between the ostensibly
equivalent Pt–Cl bond lengths in 1a (ca. 0.04 Å).
A previously reported feature of the coordination chemistry of
L
1a was the chelate ring conformation and its fluxionality.8,9 It is
clear from Fig. 1 and 2 that the z-coordinates of the backbone
phenylene group render the CH2 protons and the tBu substituents
1
inequivalent in both 1a and 2a. The H NMR spectra of both
t
complexes show broad signals for the CH2 and Bu protons at
ambient temperatures and from the coalescence temperatures,
estimated from variable temperature studies (see Experimental
for details), the calculated values for ΔG‡ are 13 kcal mol−1 for
1a and 11 kcal mol−1 for 2a indicating that the 7-membered
chelate is more rigid than the 6-membered chelate.
Ligand L3b produced a more efficient catalyst than L3a
(Table 1) and therefore the complex [PtCl2(L3b)] (2b) was pre-
pared and its crystal structure determined (Fig. 3) in order to
draw structural comparisons with 2a.12 The Pt–P distances and
the Pt–Cl distances in 2a and 2b are very similar to each other.
We have previously argued that RPCg is a significantly poorer
Fig. 2 Crystal structure of [PtCl2(L3a)] (2a). Selected bond lengths (Å)
and angles (°): Pt(1)–P(1) 2.2531(9); Pt(1)–P(2) 2.2895(8); Pt(1)–Cl(1)
2.3824(9); Pt(1)–Cl(2) 2.3627(8); P(1)–C(1) 1.823(3); P(1)–C(8)
1.878(4); P(1)–C(12) 1.913(3); P(2)–C(3) 1.848(3); P(2)–C(16)
1.906(3); P(2)–C(20) 1.922(4); P(1)–Pt(1)–P(2) 96.84(3); P(1)–Pt(1)–
Cl(2) 89.52(3); P(2)–Pt(1)–Cl(1) 92.32(3); Cl(2)–Pt(1)–Cl(1) 83.65(3);
torsion C(1)–P(1)–Pt(1)–P(2) 24.9.
σ-donor than RPtBu2 but this difference is apparently too
10
subtle to be evident from the crystal structures of 2a and 2b. The
Dalton Trans.
This journal is © The Royal Society of Chemistry 2012

View Online
Scheme 3
Cl–Pt–Cl angles and Cl....Cl distances in 2b (83°, 3.12 Å) and
2a (84°, 3.16 Å) are similar which implies that the steric com-
pression by the PCg group is at least as great as the PtBu2 group.
The isomers of [PtCl(CH3)(P–P′)], where P–P′ = a chelating
unsymmetrical diphosphine can be viewed as models for key
intermediates A1/A2 (Scheme 1) since they contain a strong
σ-donor (CH3) and a relatively weak σ-donor (Cl). Thus the
complexes [PtCl(CH3)(L3a–f)] (3a–f/4a–f) were prepared
according to Scheme 3. The geometric isomers were readily dis-
tinguished from the characteristic chemical shifts and 1JPtP coup-
ling constants; e.g. δP for coordinated PtBu2 is in the +20 to
1
+40 ppm region and JPtP for the P trans to CH3 is less than
2000 Hz and trans to Cl was over 4000 Hz. The 31P NMR spec-
trum of the 3d/4d mixture showed the presence of 2 sets of
similar signals for each component which is presumed to be due
to conformers associated with restricted rotation about the P–
C(o-tolyl) bond13 (see Experimental). The ratios of the o-diphos-
phinotoluene complexes given in Scheme 3 were estimated
from integration of the 31P signals of mixtures that had been
allowed to equilibrate for at least 24 h. It is notable that the
3 ligands that produce the most active carbonylation catalysts
also produce the highest proportions of isomer 4 with the CH3
cis to the benzyl-PtBu2 donor.
The crystal structures of the major isomers of the complexes
[PtCl(CH3)(o-diphosphinotoluene)] 4a, 4b, 4f and the co-crystal-
lised mixtures 3c/4c and 3d/4d have been determined and are
shown in Fig. 4–8. The half cone angles (θ) have been measured
in each of the structures; the θ values for the PtBu2 donors are
very similar (131° 2°) in all of the structures and the θ values
for the other PR2 groups (given in Scheme 3) vary from 114° for
PPh2 to 124° for PCg. Caution should be exercised when crystal-
lographic cone angles are used as an indicator of the bulk of a
PR2 donor because small differences in the conformation of the
P–R substituent can lead to significant differences in the values
of θ. This is especially true of PAr2 groups, since changing the
orientation of the P–Ar can be a low energy process allowing θ
to compress or expand in response to, for example, the bulk of
adjacent ligands and solvation effects. Note that PtBu2 and PCg
have much less capacity to respond sterically to their
Fig. 4 Crystal Structure of [PtCl2(L3a)] (4a). Selected bond lengths
(Å) and angles (°): Pt(1)–C(1) 2.123(6); Pt(1)–P(1) 2.2307(17); Pt(1)–
P(2) 2.3926(15); Pt(1)–Cl(1) 2.4015(16); P(1)–C(2) 1.832(6); P(1)–C(9)
1.880(7); P(1)–C(13) 1.904(7); P(2)–C(4) 1.840(6); P(2)–C(21)
1.902(6); P(2)–C(17) 1.927(6); C(1)–Pt(1)–P(1) 91.11(18); C(1)–Pt(1)–
P(2) 168.32(19); P(1)–Pt(1)–P(2) 97.41(5); C(1)–Pt(1)–Cl(1) 80.24(18);
P(1)–Pt(1)–Cl(1) 161.75(6); P(2)–Pt(1)–Cl(1) 93.66(5); torsion C(2)–
P(1)–Pt(1)–P(2) 23.4.
environment because of the rotational symmetry about the P–tBu
bond and the rigidity of the PCg.
We have previously suggested7 that the ratio of the geometric
isomers of the complexes [PtCl(CH3)(o-diphosphinoxylene)] is
largely controlled by steric effects; CH3 is slightly larger than
Cl14 and therefore occupies the less congested of the two sites
on the metal. The crystal structure of 2a suggests there is no sig-
nificant difference in the steric congestion at the ditopic sites
trans to the P-donors. Thus the observed ratio for 3a : 4a of
1 : 100 appears to be due to an electronic effect, namely the anti-
symbiotic effect15 whereby the strong σ-donor CH3 has a prefer-
ence to be trans to the weaker aryl-PtBu2 donor. Similar
stereoelectronic arguments could rationalise the greater pro-
portions of 4c–f over 3c–f compared to the analogous o-diphos-
phinoxylene complexes.7,8
A fine balance of steric and
electronic effects would explain the near parity observed for the
ratios 3d : 4d and 3e : 4e.
This journal is © The Royal Society of Chemistry 2012
Dalton Trans.

View Online
Fig. 5 Crystal Structure of [PtCl2(L3b)] (4b). The thermal ellipsoid of
Cl1(A/B) was found to be very elongated and so this was modelled as
lying over two positions. Only one of these positions is shown for
clarity. Selected bond lengths (Å) and angles (°): Pt(1)–C(1) 2.131(2);
Pt(1)–P(1) 2.2372(7); Pt(1)–Cl(1B) 2.30(2); Pt(1)–P(2) 2.3478(7);
Pt(1)–Cl(1A) 2.386(4); P(1)–C(2) 1.850(3); P(1)–C(13) 1.898(3); P(1)–
C(9) 1.898(3); P(2)–C(4) 1.850(3); P(2)–C(20) 1.890(3); P(2)–C(17)
1.903(3); C(1)–Pt(1)–P(1) 89.80(7); C(1)–Pt(1)–Cl(1B) 77.5(5); P(1)–
Pt(1)–Cl(1B) 167.1(5); C(1)–Pt(1)–P(2) 165.86(8); P(1)–Pt(1)–P(2)
95.33(2); Cl(1B)–Pt(1)–P(2) 97.5(5); C(1)–Pt(1)–Cl(1A) 80.78(12);
P(1)–Pt(1)–Cl(1A) 163.50(8); Cl(1B)–Pt(1)–Cl(1A) 11.7(3); P(2)–
Pt(1)–Cl(1A) 97.02(9); torsion C(2)–P(1)–Pt(1)–P(2) 12.3.
Fig. 7 Crystal structure of [PtCl(CH3)(L3c)] (3c/4c). The crystal struc-
ture was found to be a solid solution of 3c and 4c with Cl/Me disorder at
the C28 positions, is a ratio of Me : Cl of 0.87 : 0.13 (note, in solution
the ratio was found to be 20 : 1). Selected bond lengths (Å) and angles
(°): Pt(1)–C(28) 2.136(8); Pt(1)–P(2) 2.2085(7); Pt(1)–Cl(1) 2.21(2);
Pt(1)–P(1) 2.3131(8); Pt(1)–Cl(2) 2.3658(8); P(2)–C(16) 1.823(3);
P(2)–C(22) 1.827(3); P(2)–C(3) 1.827(3); P(1)–C(1) 1.846(3); P(1)–
C(12) 1.880(3); P(1)–C(8) 1.900(3); C(28)–Pt(1)–P(2) 85.28(17); P(2)–
Pt(1)–Cl(1) 91.9(4); P(2)–Pt(1)–P(1) 94.26(3); C(28)–Pt(1)–Cl(2)
86.04(17); Cl(1)–Pt(1)–Cl(2) 79.4(4); P(1)–Pt(1)–Cl(2) 94.72(3);
torsion C(2)–P(1)–Pt(1)–P(2) 14.1.
Fig. 6 Crystal Structure of [PtCl2(L3f)] (4f). Selected bond lengths
(Å) and angles (°): Pt(1)–C(1) 2.093(3); Pt(1)–P(1) 2.2082(9); Pt(1)–
P(2) 2.3754(9); Pt(1)–Cl(1) 2.3775(9); P(1)–C(2) 1.838(2); P(1)–C(9)
1.867(3); P(1)–C(12) 1.889(3); P(2)–C(4) 1.844(2); P(2)–C(19)
1.887(3); P(2)–C(22) 1.889(3); C(1)–Pt(1)–P(1) 90.96(9); C(1)–Pt(1)–
P(2) 173.20(9); P(1)–Pt(1)–P(2) 93.27(4); C(1)–Pt(1)–Cl(1) 82.81(8);
P(1)–Pt(1)–Cl(1) 166.87(3); P(2)–Pt(1)–Cl(1) 94.08(4); torsion C(2)–
P(1)–Pt(1)–P(2) 29.5.
Fig. 8 Crystal structure of [PtCl(CH3)(L3d)] (3d/4d). The chloride and
methyl groups are disordered over the two positions. The individual posi-
tions of the methyl and chloride groups could not be modelled satisfac-
torily so they were considered to lie on the same position, although this
description is clearly inaccurate. The occupancy of C1A at the position
shown is 0.59. The tolyl group at C24 is also disordered over two posi-
tions. Only the major component (0.65) is shown. Selected bond
lengths (Å) and angles (°): Pt(1)–P(2) 2.2692(13); Pt(1)–C(1A)
2.283(3); Pt(1)–P(1) 2.2932(14); Pt(1)–Cl(1A) 2.313(2); P(1)–C(2)
1.850(6); P(1)–C(9) 1.891(6); P(1)–C(13) 1.904(6); P(2)–C(17)
1.832(5); P(2)–C(4) 1.832(5); P(2)–C(24A) 1.852(6); P(2)–C(24B)
1.861(10); P(2)–Pt(1)–C(1A) 92.34(8); P(2)–Pt(1)–P(1) 93.63(5);
C(1A)–Pt(1)–Cl(1A) 77.68(10); P(1)–Pt(1)–Cl(1A) 96.46(7); torsion
C(2)–P(1)–Pt(1)–P(2) 8.2.
In order to probe the reasons for the disparate behaviour of the
Pd catalysts derived from L3b and L3c (see Table 1), the palla-
dium coordination chemistry with model complexes of these
ligands was explored. Treatment of [PdCl(CH3)(cod)] with L3b
and L3c gave the complexes 5b/6b and 5c/6c (Scheme 4). We
tentatively assign the structures of the major isomers as 6b and
5c based on the ratios of the isomers observed for 5b/6b (1 : 40)
and 5c/6c (25 : 1) being similar to those of the unambiguously
assigned Pt analogues 3b/4b (1 : 10) and 3c/4c (20 : 1).
When solutions containing 5b/6b or 5c/6c were stirred under
an atmosphere of 13CO, the isotopic label enabled the
Dalton Trans.
This journal is © The Royal Society of Chemistry 2012

View Online
Scheme 4
unambiguous assignment from the 31P NMR spectra of the geo-
metric isomers of the products that formed. For example, in 7c,
the PtBu2 signal at δ 39.2 has a JPC of 120 Hz which is large and
typical of a trans coupling and the PPh2 signal at δ 14.6, has a
JPC of 16 Hz which is typical of a cis coupling. It was thus con-
cluded that mixtures of the acyl complexes 7b/8b (1 : 4) or 7c/8c
(9 : 1) were formed. The reactions did not go to completion after
20 min and decomposition to Pd metal occurred after prolonged
reaction. Therefore the acyl products were characterised in solu-
tion only by 31P and 13C NMR and IR spectroscopy.
The CO insertion reactions (Scheme 4) are not very stereo-
specific since they have given mixtures of geometric isomers of
the acyl complexes in ratios that are quite different from the
alkyl complex precursors 1 : 40 → 1 : 4 for the complexes of L3b
and 25 : 1 → 9 : 1 for the complexes of L3c. The mechanism for
the CO insertion reaction proposed in Scheme 5 is based on lit-
erature precedent7,8,16,17 and predicts inversion of stereo-
chemistry at Pd. However, it is likely that the insertion reaction
is under thermodynamic control because of equilibration of the
acyl products; equilibration of this type has been shown to occur
rapidly in acylpalladium o-diphosphinoxylene complexes.17
Addition of 1 equivalent of MeOH to a CH2Cl2 solution of a
7b/8b mixture gave quantitative formation of CH313COOMe (δc
176.6 ppm) within the 3 min required to acquire the NMR spec-
trum. By contrast, a 7c/8c mixture under similar conditions
reacted slowly with MeOH even upon addition of a 5-fold
excess. This contrast in the kinetics of the methanolysis of the
complexes of L3b and L3c matches the contrast in the catalytic
performance of these two ligands. A plausible mechanism for
the methanolysis involves MeOH displacement of the Cl ligand,
loss of a proton and the subsequent reductive elimination of the
ester. The fact that the major isomers have different geometries
(8b and 7c) might be significant although it is likely that equili-
bration with the minor isomers would be rapid.17 It is likely that
the reductive elimination of the ester would be promoted by
adjacent bulky groups and the two very bulky P-donors of
ligand L3b thus facilitate the methanolysis. In the catalytic
system, no halide ligands are present but the methanolysis step
Scheme 5
has been proposed to be rate-limiting6,16 and therefore similar
steric-promotion factors are likely to be key to the success of the
catalyst.
Conclusions
The homogeneous catalytic performance of palladium com-
plexes derived from ligands of the type o-C6H4(CH2PR2)(PR′2)
for the hydromethoxycarbonylation of ethene is a sensitive func-
tion of the P-substituents. Some of the o-diphosphinotoluenes
reported here produce catalysts that are the most active so far
This journal is © The Royal Society of Chemistry 2012
Dalton Trans.

View Online
reported, outstripping the commercialised Lucite catalyst based
on o-C6H4(CH2PtBu2)2 in terms of relative rate by a factor of up
to 3.8. On the other hand, complexes of some o-diphosphino-
toluenes showed zero activity. A comparative study of the coordi-
nation chemistry of analogous o-diphosphinotoluenes and
o-diphosphinoxylenes with Pd and Pt support the hypothesis that
the smaller bite angle of o-diphosphinotoluenes can switch off the
catalysis, perhaps by reducing the facility of intramolecular reac-
tions such as migratory insertions or reductive eliminations. This
negative effect of the smaller bite angle of o-diphosphinotoluene is
counteracted by the presence of very bulky PtBu2 or PCg donors
which not only restore the catalytic function but indeed lead to
catalysts which surpass their o-diphosphinoxylene analogues.
then immediately added to a solution of 2-bromobenzylbromide
(8.50 g, 34.0 mmol) at −78 °C. The mixture was then stirred at
−78 °C for 30 min before warming it to room temperature and
stirring it for 16 h. The solvent was then removed at reduced
pressure and the residue suspended in toluene (150 mL). Water
(40 mL, N2-saturated) was added followed by diethylamine
(20 mL, N2-saturated). The organic phase was then cannula
transferred into a Schlenk tube and the aqueous residues washed
with toluene (50 mL). The toluene extracts were combined and
the solvent removed under reduced pressure to give an off-white
solid (13.5 g, 96%, 95% pure). 31P{1H} NMR (162 MHz,
CDCl3): δ −26.2 (s).
Preparation of o-C6H4(CH2PtBu2)(PtBu2) (L3a)
Experimental
In a 500 mL Schlenk flask, magnesium ribbon (1.89 g,
78.0 mmol) was suspended in THF (150 mL) and iodine (4 crys-
tals) and 1,2-dibromoethane (8 drops) were then added and the
suspension was stirred at room temperature for 1 h. To this
suspension was then added dropwise a solution I (12.3 g,
39.0 mmol) in THF (50 mL). The resultant colourless solution
was then heated to reflux for 3 h. This gave a brown/orange solu-
tion with some unreacted magnesium. The Grignard solution
was then added slowly to a 500 mL Schlenk flask containing
tBu2PCl (7.04 g, 39.0 mmol), CuI (0.717 g, 3.76 mmol) and
LiBr (0.650 g, 7.49 mmol) and THF (100 mL) at 0 °C. The
resultant solution was allowed to warm up to room temperature
and stirred overnight. The solvent was then removed under
reduced pressure and the residue suspended in diethyl ether
(300 mL). Water (100 mL, N2-saturated) was then added to give
a biphasic solution. The upper (organic) phase was cannula
transferred into a Schlenk tube and the aqueous residues washed
with ether (200 mL). The ether extracts were then combined and
then dried over Na2SO4. The ether solution was then cannula
transferred into a Schlenk flask and then the solvent removed
under reduced pressure to give an off-white solid crude product
(14.2 g). The solid was suspended in methanol (50 mL) and
heated to boiling which produced a colourless solution. The
solution was then cooled to room temperature to give a white
crystalline solid. The methanol solution was then removed by
cannula and the white crystalline solid dried under vacuum and
then manipulated in a glovebox (6.8 g, 46%, 95% pure).
31P{1H} NMR (162 MHz, CD2Cl2): δ 35.0 (d, J(PP) = 3 Hz),
14.0 (d, J(PP) = 3 Hz). 1H NMR (400 MHz, CD2Cl2):
δ 7.85–7.81 (1 H, m), 7.68 (1 H, d, J(HH) = 7.7 Hz), 7.28–7.24
(1 H, m), 7.13–7.10 (1 H, m), 3.38 (CH2, dd, J(HP) = 5.6 Hz,
J(HP) = 3.8 Hz), 1.41 (3 H, d, J(HP) = 13.9 Hz), 1.21 (CH3,
18 H, d, J(HP) = 11.6 Hz), 1.15 (CH3, 18 H, d, J(HP) =
10.6 Hz). 13C{1H} NMR (100 MHz, CD2Cl2): δ 149.7 (ipso C,
dd, J(CP) = 26.5 Hz, J(CP) = 12.5 Hz), 136.7 (ipso C, dd, J(CP)
= 24.1 Hz, J(CP) = 3.1 Hz), 135.9 (d, J(CP) = 3.1 Hz), 131.4
(dd, J(CP) = 20.2 Hz, J(CP) = 4.7 Hz), 128.7 (s), 124.4 (d,
J(CP) = 2.3 Hz), 33.2 (C(CH3)3, d, J(CP) = 23.7 Hz), 32.6
(C(CH3)3, d, J(CP) = 22.6 Hz), 31.1 (PhC(CH3)3, d, J(CP) =
14.8 Hz), 30.4 (CH2C(CH3)3, d, J(CP) = 13.6 Hz), 30.4 (CH2C-
(CH3)3, d, J(CP) = 13.2 Hz), 27.9 (CH2, dd, J(CP) = 30.4 Hz,
J(CP) = 21.8 Hz). Accurate mass spectrum: Mr = 381.2845
(M + H)+ (calcd for C23H43P2 381.2835).
Unless otherwise stated, all reactions were carried out under a
dry nitrogen atmosphere using standard Schlenk-line techniques.
Dry N2-saturated solvents were collected from a Grubbs
system18 in flame and vacuum-dried glassware. MeOH was dried
over 3 Å molecular sieves, pentane was dried over 4 Å molecular
sieves and both were deoxygenated by N2 saturation. The com-
plexes [PtCl2(cod)],19 [PtCl(CH3)(cod)],20 and [PdCl(CH3)-
t
(cod)]21 were prepared by literature methods. Bu2PH in THF
t
was obtained from JCI USA Inc. and Bu2PH(BH3) from Lucite
International. CgPH and CgPH(BH3) were obtained as pre-
viously described.13 All phosphines were stored under nitrogen
at room temperature. All other reagents were used as received
from Aldrich, Strem or Lancaster. NMR spectra were recorded
on a Jeol Delta 270, Jeol Eclipse 300, Jeol Eclipse 400, Varian
400, Varian 500, or Lambda 300. Infrared spectroscopy was
carried out on a Perkin Elmer 1600 Series FTIR. Mass spectra
were recorded on a MD800 by the Mass Spectrometry Service,
University of Bristol. Elemental analyses were carried out by the
Microanalytical Laboratory of the School of Chemistry, Univer-
sity of Bristol.
Preparation of o-BrC6H4CH2PtBu2 (I)22
1-Bromo-2-(bromomethyl)benzene (3.39 g, 13.6 mmol) was
placed in a two-necked round-bottomed flask equipped with a
t
condenser and dissolved in MeOH (20 mL). Bu2PH (1.99 g,
2.52 mL, 13.6 mmol) was added dropwise to the solution at
room temperature. The reaction mixture was heated to reflux and
stirred overnight at that temperature. Then, the solution was
cooled to room temperature and NEt3 (1.38 g, 1.89 mL,
13.6 mmol) was added dropwise. The solution was stirred for
1 h and then the volatiles were removed under reduced pressure
and the crude product was redissolved in pentane. The solution
was filtered via canula and the solvent was removed under
reduced pressure affording a colourless oil (3.95 g, 92%). 31P
{1H} NMR (121 MHz, C5H12): δ 33.5 (s).
Preparation of o-BrC6H4CH2PCg (J)
CgPH(BH3) (7.75 g, 34.0 mmol) was dissolved in THF
n
(100 mL). The solution was cooled to −78 °C and BuLi (2.5M
in hexanes, 13.6 mL, 34.0 mmol) was added. This solution was
Dalton Trans.
This journal is © The Royal Society of Chemistry 2012

View Online
Preparation of o-C6H4(CH2PtBu2)(PCg) (L3b
)
= 4.2 Hz, J(HH) = 1.5 Hz), 3.06 (CH2, 2 H, t, J(HP) = 3.7 Hz),
1.13 (CH3, 18 H, d, J(HP) = 11.0 Hz). 13C{1H} NMR
(100 MHz, CD2Cl2): δ 146.6 (ipso CCH2PPh2, dd, J(CP) =
23.8 Hz, J(CP) = 13.1 Hz), 137.5 (ipso C, d, J(CP) = 10.8 Hz),
136.9 (ipso CCH2PtBu2, dd, J(CP) = 10.0 Hz, J(CP) = 3.1 Hz),
134.6 (d, J(CP) = 20.0 Hz), 133.8 (s), 131.2 (s), 131.2 (CH, s),
131.0 (s), 130.9 (s), 126.2 (d, J(CP) = 1.6 Hz), 32.5 (C(CH3)3,
d, J(CP) = 22.3 Hz), 30.2 (C(CH3)3, d, J(CP) = 13.5 Hz), 30.1
(C(CH3)3, d, J(CP) = 13.5 Hz), 27.4 (CH2, d, J(CP) = 23.8 Hz).
Accurate mass spectrum: Mr = 421.2209 (M + H)+ (calcd for
C27H35P2 421.2209).
2-bromobenzylbromide (10.0 g, 40.0 mmol) was dissolved in
MeCN (50 mL). To this solution was added Bu2PH (8.0 mL,
t
43 mmol). The resultant solution was then stirred for 16 h. The
solvent was then removed under reduced pressure to give a white
solid. This was suspended in toluene (40 mL) and water (40 mL,
N2-saturated) was added. This was followed by diethylamine
(10 mL) to give a white suspension. Ethanol (10 mL) was added
and the resultant biphasic mixture separated. The upper (organic)
phase was cannula transferred into a Schlenk tube and the
solvent removed under reduced pressure to give a colourless oil
(10.6 g). To this oil was added DABCO (9.52 g, 84.9 mmol),
CgPH (8.25 g, 38.2 mmol) and [Pd(PPh3)4] (1.0 g, 0.87 mmol).
To this suspension was added o-xylene (50 mL, N2-saturated)
and the resultant suspension was then heated to 140 °C for 16 h.
The orange suspension was then allowed to cool to 100 °C and
was filtered at this temperature. The solution was reduced to
10 mL under reduced pressure and then methanol (40 mL) was
added. The resultant yellow/orange oily material was heated to
60 °C for 20 min before cooling to room temperature. This
resulted in the formation of a yellow crystalline material which
was then allowed to stand for 16 h. The solid was then isolated
by filtration and the dried under vacuum. The free flowing
yellow solid product (7.5 g, 39%) was manipulated in a glove-
box. 31P{1H} NMR (121 MHz, CDCl3): δ 35.8 (s), −41.6 (s).
1H NMR (300 MHz, CDCl3): δ 8.46 (1 H, m), 8.12 (1 H, m),
7.15 (1 H, m), 7.05 (1 H, m), 4.35 (1H, CH2Ar, ddd, J(HH) =
18.6 Hz, J(HP) = 9.0, 4.0 Hz), 2.57 (1H, d, CH2Ar, J(HH) =
18.6 Hz), 2.00 (1H, m, CH2), 1.67 (3H, m, CH2), 1.47 (3H, s,
CH3), 1.45 (3H, s, CH3), 1.44 (3H, s, CH3), 1.31 (3H, s, CH3),
1.18 (9H, d, CCH3)3, J(HP) = 6.0 Hz), 1.15 (9H, d, CCH3)3,
J(HP) = 6.0 Hz). 13C{1H} NMR (75 MHz, CDCl3): δ 149.2 (dd,
J(CP) = 24.0, 12.0 Hz), 133.5 (d, J(CP) = 3.0 Hz), 132.8 (dd,
J(CP) = 26.2, 3.0 Hz), 131.4 (dd, J(CP) = 18.7, 5.1 Hz), 96.8
(s), 96.1 (s), 74.5 (d, J(CP) = 15.5 Hz), 73.5 (d, J(CP) =
37.5 Hz), 46.1 (d, J(CP) = 26.2 Hz), 36.2 (s), 33.3 (s), 32.9 (s),
31.3 (s), 31.0 (s), 30.1 (d, J(CP) = 14.8 Hz), 29.9 (d, J(CP) =
15.0 Hz), 27.2 (dd, J(CP) = 29.7, 22.5 Hz), 26.4 (d, J(CP) =
11.2 Hz). Elemental analysis (calcd for C25H38O3P2): C: 66.64
(66.63), H: 9.34 (8.95).
Preparation of o-C6H4(CH2PtBu2)(P{o-CH3C6H4}2) (L3d
)
o-BrC6H4CH2PtBu2 (0.76 g, 3.30 mmol) was placed in a two-
necked round bottomed flask and dissolved in Et2O (10 mL). A
n
1.6 M solution of BuLi (2.00 mL, 3.30 mmol) in hexane was
added dropwise over 5 min at −78 °C and stirred for 20 min at
room temperature before a solution of (o-tolyl)2PCl (0.83 g,
3.30 mmol) in Et2O (3 mL) was added over 5 min at −78 °C. A
white precipitate was observed and the yellow solution was
stirred overnight at room temperature. Water (10 mL) was added
and the organic layer was separated, dried over MgSO4 and
filtered via canula. The volatiles were removed under reduced
pressure and the residue was recrystallised from the minimum
amount of boiling MeOH affording a white solid (0.19 g, 13%).
31P{1H} NMR (121 MHz, C6D6): δ 30.6 (PtBu2, d, J(PP) =
7 Hz), −30.5 (PAr2, d, J(PP) = 7 Hz). 1H NMR (300 MHz,
C6D6): δ 8.24 (1 H, quintuplet, J(HH) = 3.8 Hz), 7.28–6.94
(11 H, m), 3.27 (CH2, 2 H, br s), 2.58 (CH3Ph, 6 H, d, J(HP) =
0.9 Hz), 1.19 (C(CH3)3, 18 H, d, J(HP) = 10.8 Hz). 13C{1H}
NMR (75 MHz, C6D6): δ 143.3 (d, J(CP) = 26.5 Hz), 135.6
(d, J(CP) = 10.7 Hz), 134.3 (s), 133.8 (s), 130.9 (d, J(CP) =
4.9 Hz), 129.5 (s), 127.0 (d, J(CP) = 0.6 Hz), 126.7 (d, J(CP) =
1.4 Hz), 32.4 (C(CH3)3, br d, J(CP) = 23.4 Hz), 30.3 (C(CH3)3,
d, J(CP) = 13.9 Hz), 30.2 (C(CH3)3, d, J(CP) = 13.9 Hz), 27.4
(CH3Ph, d, J(CP) = 1.2 Hz), 21.8 (CH2, d, J(CP) = 21.9 Hz).
Accurate mass spectrum: Mr = 449.2536 (M + H)+ (calcd for
C29H39P2 449.2522).
Preparation of o-C6H4(CH2PtBu2)(P{o-CH3OC6H4}2) (L3e)
Preparation of o-C6H4(CH2PtBu2)(PPh2) (L3c)
Into a 500 mL Schlenk flask was added magnesium ribbon
(3.30 g, 136 mmol). This was suspended in THF (100 mL) and
iodine (4 crystals) was then added. The suspension was then
heated in a hot water bath for 20 min. To this suspension was
added a solution of I (21.5 g, 68.1 mmol) in THF (50 mL) drop-
wise over 1 h. The resultant colourless solution was then heated
to reflux for 4 h to give a grey suspension which was then
cooled to room temperature and stirred at room temperature for
3 d to give a brown/orange solution with some unreacted mag-
nesium. This mixture was then refluxed for 2 h before being
cooled to room temperature. The Grignard solution was then
added slowly to a 500 mL Schlenk flask containing the di-o-
methoxyphenylchlorophosphine (19.1 g, 68.1 mmol), CuI
(1.3 g, 6.8 mmol), LiBr (1.1 g, 12 mmol) and THF (150 mL) at
0 °C. The resultant solution was allowed to warm up to room
temperature and stirred for 16 h. The solvent was then removed
o-BrC6H4CH2PtBu2 (1.00 g, 4.40 mmol) was placed in a two-
necked round bottomed flask and dissolved in Et2O (10 mL). A
n
1.6 M solution of BuLi (2.75 mL, 4.40 mmol) in hexane was
added dropwise over 5 min at −78 °C and stirred for 15 min at
room temperature before Ph2PCl (0.82 mL, 4.40 mmol) was
added over 5 min at −78 °C. A white precipitate was observed
and the orange solution was stirred overnight at room tempera-
ture. Water (10 mL) was added and the organic layer was separ-
ated, dried over MgSO4 and filtered via canula. The volatiles
were removed under reduced pressure and the residue was recrys-
tallised from the minimum amount of boiling MeOH affording a
white solid (0.45 g, 24%). 31P{1H} NMR (121 MHz, CD2Cl2):
δ 32.3 (PtBu2, d, J(PP) = 4 Hz), −14.8 (PPh2, d, J(PP) = 4 Hz).
1H NMR (400 MHz, CD2Cl2): δ 7.91–7.87 (1 H, m), 7.39–7.29
(11 H, m), 7.08 (1 H, d, J(HH) = 7.5 Hz), 6.88 (1 H, dd, J(HH)
This journal is © The Royal Society of Chemistry 2012
Dalton Trans.

View Online
under reduced pressure and the residue suspended in diethyl
ether (300 mL). Water (100 mL, N2-saturated) was then added to
give a biphasic mixture. The upper (organic) phase was cannula
transferred into a Schlenk tube and the aqueous residues washed
with ether (200 mL). The ether extracts were then combined and
dried over Na2SO4. The ether solution was then cannula trans-
ferred into a Schlenk flask and the solvent removed under
reduced pressure to give the yellow/white solid crude product.
The solid was suspended in methanol (100 mL) and heated to
reflux give a cloudy solution which was then cooled to room
temperature and the methanol solution was removed by cannula.
The white crystalline solid product (6.8 g, 20%, 95% pure) was
then dried under vacuum and manipulated in a glovebox. 31P
{1H} NMR (162 MHz, CD2Cl2): δ 33.7 (PtBu2, d, J(PP) =
3 Hz), −37.8 (PAr2, d, J(PP) = 3 Hz). 1H NMR (400 MHz,
CD2Cl2): δ 7.85–7.81 (1 H, m), 7.35 (2 H, t, J(HH) = 8.3 Hz),
7.30–7.26 (1 H, m), 7.01 (1 H, t, J(HH) = 7.4 Hz), 6.94 (2 H,
dd, J(HH) = 7.8 Hz, J(HH) = 4.9 Hz), 6.86 (2 H, t, J(HH) =
7.3 Hz), 6.79 (1 H, dd, J(HH) = 7.1 Hz, J(HH) = 3.4 Hz),
6.69–6.66 (2 H, m), 3.73 (OCH3, 6 H, s), 3.09 (CH2, 2 H, br s),
1.15 (C(CH3)3, 18 H, d, J(HP) = 10.8 Hz). 13C{1H} NMR
(100 MHz, CD2Cl2): δ 162.1 (d, J(CP) = 17.1 Hz), 146.8 (dd,
J(CP) = 25.7 Hz, J(CP) = 12.5 Hz), 136.1 (d, J(CP) = 10.1 Hz),
134.6 (s), 133.6 (s), 130.8 (dd, J(CP) = 20.2 Hz, J(CP) =
3.9 Hz), 130.6 (s), 130.1 (d, J(CP) = 8.6 Hz), 128.6 (s), 127.5
(s), 125.9 (d, J(CP) = 1.6 Hz), 125.7 (d, J(CP) = 2.3 Hz), 125.3
(d, J(CP) = 13.2 Hz), 121.6 (s), 121.3 (s), 120.7 (s), 110.9 (s),
100.6 (s), 56.1 (OCH3), 32.5 (C(CH3)3, d, J(CP) = 22.6 Hz),
30.2 (C(CH3)3, d, J(CP) = 13.2 Hz), 30.1 (C(CH3)3, d, J(CP) =
13.2 Hz), 26.6 (CH2, dd, J(CP) = 26.5 Hz, J(CP) = 23.4 Hz).
Accurate mass spectrum: Mr = 497.2386 (M + O + H)+ (calcd
for C29H39O3P2 497.2369).
3.63 (CHH, 1 H, ddd, J(HH) = 14.6 Hz, J(HP) = 5.4 Hz, J(HP)
= 4.7 Hz), 2.95 (CHH, 1 H, d, J(HH) = 14.6 Hz), 2.14 (CHH,
1 H, dd, J(HH) = 13.5 Hz, J(HH) = 2.5 Hz), 2.06 (CHH, 1 H,
dd, J(HH) = 13.5 Hz, J(HH) = 3.9 Hz), 1.44–1.30 (CH3, 18 H,
m), 1.21 (CH3, 3 H, d, J(HP) = 12.2 Hz), 1.11 (CH3, 3 H, d,
J(HP) = 12.0 Hz). 13C{1H} NMR (100 MHz, CD2Cl2): δ 146.7
(dd, J(CP) = 26.1 Hz, J(CP) = 9.3 Hz), 134.7 (dd, J(CP) =
2.7 Hz, J(CP) = 1.2 Hz), 133.1 (dd, J(CP) = 28.8 Hz, J(CP) =
2.7 Hz), 131.3 (dd, J(CP) = 11.3 Hz, J(CP) = 5.1 Hz), 129.9 (s),
126.6 (d, J(CP) = 2.3 Hz), 97.4 (CO2CH3, d, J(CP) = 0.8 Hz),
97.0 (CO2CH3, d, J(CP) = 0.8 Hz), 96.6 (CO2CH3, s), 96.5
(CO2CH3, s), 74.8 (COCH3, dd, J(CP) = 8.2 Hz, J(CP) =
1.2 Hz), 74.9 (COCH3, J(CP) = 24.1 Hz), 73.7 (COCH3, d,
J(CP) = 12.1 Hz), 73.1 (COCH3, dd, J(CP) = 23.7 Hz, J(CP) =
2.7 Hz), 46.6 (CH2, d, J(CP) = 19.1 Hz), 45.4 (CH2, d, J(CP) =
15.6 Hz), 38.4 (CH2, dd, J(CP) = 6.2 Hz, J(CP) = 1.6 Hz), 36.5
(CH2, d, J(CP) = 1.6 Hz), 29.2 (CH3, d, J(CP) = 4.7 Hz), 29.0
(CH3, d, J(CP) = 4.7 Hz), 28.4 (CH3, s), 28.2 (CH3, s), 27.5
(CH2P, dd, J(CP) = 26.1 Hz, J(CP) = 24.1 Hz), 27.5 (CH3, s),
27.4 (CH3, s), 27.0 (CH3, s), 26.9 (CH3, s). Accurate mass spec-
trum: Mr = 521.2239 (M + H)+ (calcd for C27H39O6P2
521.2216).
Carbonylation catalysis
Pd(OAc)2 (22 mg, 0.10 mmol) and ligand L3a–f (0.50 mmol)
were dissolved in methanol (300 mL) and the solution was
stirred for 30 min. The addition of methane sulfonic acid
(2.92 mL, 45 mmol) completed the preparation of the catalyst
solution. The catalyst solution was added to the pre-evacuated
autoclave and heated to 100 °C, at which point the pressure gen-
erated by the solvent was 2.3 bar. The autoclave was then pres-
surised to 12.3 bar with CO : ethene (1 : 1) from a 10 L reservoir
at higher pressure. A regulatory valve ensured that the pressure
of the autoclave was maintained throughout the reaction at
12.3 bar through continual injection of gas from the reservoir.
The pressure of the reservoir and the reactor temperature were
logged throughout the reaction period of 3 h. The amount of
product at any point in the reaction could be calculated from the
drop in reservoir pressure by assuming ideal gas behaviour and
100% selectivity for methyl propionate, allowing reaction TON
with the particular ligand to be estimated. After 3 h, the auto-
clave was cooled and vented. The reaction solution was collected
from the base of the vessel and immediately placed under a N2
atmosphere. The solution was weighed so that the TON could be
calculated.
Preparation of o-C6H4(CH2PCg)(PCg) (L3f)
The intermediate J (13.5 g, 35.1 mmol) was dissolved in toluene
(60 mL) and to this solution was added DABCO (9.93 g,
88.5 mmol), CgPH (7.57 g, 35.1 mmol) and [Pd(PPh3)4] (1.0 g,
0.87 mmol). The resultant pale yellow solution was then heated
to 140 °C for 16 h to give an orange/yellow suspension. The sus-
pension was allowed to cool to 100 °C and was then filtered
through a frit containing celite to give a red/orange solution
which was concentrated under reduced pressure to 10 mL.
Methanol (40 mL) was added and the resulting solution put
aside for 16 h which led to the formation of a yellow/orange
solid. The solution was cannula transferred into a Schlenk tube
and the solvent removed under reduced pressure to give the
crude solid product. The solid was purified by dissolving in
boiling methanol (40 mL) and allowing the solution to cool to
room temperature before placing in a freezer (−10 °C) overnight.
The resulting yellow/orange crystalline material was isolated by
cannula transfer of the methanol mother liquor followed by
drying the solid product (2.6 g, 14%, 95% pure) under vacuum
and manipulating it in a glovebox. 31P{1H} NMR (162 MHz,
CD2Cl2): δ −21.4 (CH2PCg, d, J(PP) = 24 Hz), −41.9 (PCg, d,
Preparation of [PtCl2(L1a)] (1)
A solution of L1a (72 mg, 0.18 mmol) in CH2Cl2 (4 mL) was
added to a stirred solution of [PtCl2(cod)] (65 mg, 0.17 mmol)
in CH2Cl2 (4 mL) and the mixture was stirred for 96 h. The vola-
tiles were then removed under reduced pressure, the residue
washed with pentane and toluene respectively, and dried under
reduced pressure to afford a white solid (105 mg, 83%). Crystals
suitable for X-ray analysis were grown by slow vapour diffusion
of pentane into a solution of the product in CHCl3. 31P{1H}
NMR (202.4 MHz, CD2Cl2): δ 11.4 (CH2PtBu2, s, J(PPt) =
1
J(PP) = 24 Hz). H NMR (400 MHz, CD2Cl2): δ 8.18 (1 H, dt,
J(HH) = 7.6 Hz, J(HH) = 1.8 Hz), 7.52–7.49 (1 H, m), 7.30
(1 H, td, J(HH) = 7.6 Hz, J(HH) = 1.5 Hz), 7.23–7.20 (1 H, m),
Dalton Trans.
This journal is © The Royal Society of Chemistry 2012

View Online
1
3646 Hz). H NMR (500 MHz, CD2Cl2): δ 7.39–7.37 (2H, m),
37.5 Hz), 53.5 (s), 43.5 (d, J(CP) = 7.5 Hz), 39.8 (d, J(CP) =
15 Hz), 39.6 (d, J(CP) = 7.5 Hz), 32.2 (s), 29.9 (s), 27.6 (s),
26.9 (s), 25.3 (d, J(CP) = 7.5 Hz). EI mass spectrum: Mr = 681
(M − Cl)+, 646 (M − 2Cl)+. Elemental analysis (calcd for
C25H38Cl2O3P2Pt), C: 41.03 (41.91), H: 5.52 (5.63).
7.23–7.21 (2H, m), 3.61 (CH2 4H, br), 1.54 (CH3, 36H, br, s).
13C{1H} NMR (125 MHz, CDCl3): δ 135.2 (s), 132.7 (s), 127.3
(s), 100.0 (CH2, s), 32.0 (CCH3, s), 30.9 (CCH3, s). Accurate
mass spectrum: Mr
= 624.2256 (M −
Cl)+ (calcd for
C23H42P2PtCl 624.2255). Elemental analysis (calcd for
C24H44Cl2P2Pt.2CHCl3): C: 35.44 (34.72) H: 5.15 (5.16).
Preparation of [PtCl(CH3)(L3a)] (3a/4a)
A solution of L3a (74 mg, 0.19 mmol) in CH2Cl2 (1 mL) was
added dropwise over 30 s to a stirred solution of [PtCl(CH3)-
(cod)] (64 mg, 0.18 mmol) in CH2Cl2 (1 mL). The mixture was
stirred overnight. The volatiles were removed under reduced
pressure and the residue was washed with pentane and dried
under reduced pressure affording a white solid (91 mg, 81%).
Crystals suitable for X-ray analysis were grown by slow vapour
diffusion of hexane into a solution of the product in CH2Cl2.
The product was obtained as a mixture of two isomers in a
1 : 100 ratio (3a : 4a) at room temperature. 31P{1H} NMR
(162 MHz, CD2Cl2): For 3a: δ 40.1 (CH2PtBu2, d, J(PPt) =
4328 Hz, J(PP) = 17 Hz), 35.2 (PtBu2, d, J(PPt) = 1820 Hz,
J(PP) = 17 Hz). For 4a: δ 36.4 (PtBu2, d, J(PPt) = 4458 Hz,
J(PP) = 15 Hz), 36.1 (CH2PtBu2, d, J(PPt) = 1755 Hz, J(PP) =
15 Hz). 1H NMR (400 MHz, CD2Cl2): For 3a: δ 7.82–7.79
(1 H, m), 7.42–7.16 (3 H, m), 2.53–2.21 (CH2, 2 H, m), 1.38
(CH3, 18 H, d, J(HP) = 13.6 Hz), 1.24 (CH3, 18 H, d, J(HP) =
12.7 Hz), 0.88 (CH3-Pt, br t, J(HPt) not discernible, J(HPtrans)
= J(HPcis) = 6.2 Hz). For 4a: δ 8.04–8.01 (1 H, m), 7.38–7.36
(2 H, m), 7.27–7.22 (1 H, m), 2.53–2.21 (CH2, 2 H, m), 1.51
(CH3, 18 H, d, J(HP) = 13.1 Hz), 1.31 (CH3, 18 H, d, J(HP) =
13.2 Hz), 0.99 (CH3-Pt, 3 H, br d, J(HPt) = 49.9 Hz, J(HPtrans)
= 4.9 Hz, J(HPcis) not resolved). 13C{1H} NMR (125 MHz,
CD2Cl2): δ 143.6 (dd, J(CP) = 14.0 Hz, J(CP) = 3.9 Hz), 136.8
(d, J(CP) = 1.6 Hz), 133.9 (s), 130.8 (d, J(CP) = 2.3 Hz), 127.5
(dd, J(CP) = 22.6 Hz, J(CP) = 3.9 Hz), 126.6 (dd, J(CP) =
4.7 Hz, J(CP) = 1.6 Hz), 39.6 (C(CH3)3, d, J(CP) = 13.2 Hz),
39.0 (C(CH3)3, d, J(CP) = 26.5 Hz), 38.9 (C(CH3)3, d, J(CP) =
26.5 Hz), 32.9 (C(CH3)3, d, J(CP) = 4.7 Hz), 31.1 (C(CH3)3, d,
J(CP) = 2.3 Hz), 28.9 (CH2, J(CP) = 26.5 Hz, J(CP) = 14.0 Hz).
Accurate mass spectrum: Mr = 590.2661 (M − Cl)+ (calcd for
C24H45P2Pt 590.2639). Elemental analysis (calcd for
C24H45ClP2Pt): C: 45.58 (46.04), H: 7.01 (7.24).
Preparation of [PtCl2(L3a)] (2a)
A solution of L3a (79 mg, 0.20 mmol) in CH2Cl2 (4 mL) was
added to a stirred solution of [PtCl2(cod)] (73 mg, 0.20 mmol)
in CH2Cl2 (4 mL) and the mixture was stirred for 48 h. The vola-
tiles were then removed under reduced pressure and the residue
was washed with pentane and dried under reduced pressure to
afford a yellow solid (112 mg, 90%). Crystals suitable for X-ray
analysis were grown by slow vapour diffusion of hexane into a
solution of the product in CH2Cl2. 31P{1H} NMR (202.4 MHz,
CDCl3): δ 33.4 (CH2PtBu2, d, J(PPt) = 3656 Hz, J(PP) =
15 Hz), 31.5 (PtBu2, d, J(PPt) = 3706 Hz, J(PP) = 15 Hz).
1H NMR (500 MHz, CDCl3): δ 8.11–8.07 (1 H, m), 7.46–7.44
(2 H, m), 7.30–7.27 (1 H, m), 3.60 (CH2, 2 H, d, J(HP) =
12.1 Hz. J(HPt) = 60.8 Hz), 1.65 (CH3, 18 H, d, J(HP) =
14.9 Hz), 1.47 (CH3, 18 H, d, J(HP) = 14.3 Hz). 13C{1H} NMR
(125 MHz, CDCl3): δ 141.6 (dd, J(CP) = 9.7 Hz, J(CP) =
3.9 Hz), 134.5 (d, J(CP) = 1.8 Hz), 133.7 (d, J(CP) = 6.5 Hz),
1.33.6 (d J(CP) = 6.7 Hz), 131.5 (d, J(CP) = 2.3 Hz), 126.7 (dd,
J(CP) = 6.9 Hz, J(CP) = 1.8 Hz), 40.6 (C(CH3)3, d, J(CP) =
25.5 Hz), 39.2 (C(CH3)3, d, J(CP) = 26.3 Hz), 33.3 (C(CH3)3, d,
J(CP) = 2.6 Hz), 30.9 (C(CH3)3, d, J(CP) = 1.6 Hz), 27.8 (CH2,
dd, J(CP) = 26.9 Hz, J(CP) = 9.4 Hz). Accurate mass spectrum:
Mr = 610.2114 (M − Cl)+ (calcd for C23H42P2PtCl 610.2093).
Elemental analysis (calcd for C23H42Cl2P2Pt.CH2Cl2): C: 38.86
(39.41), H: 5.61 (6.06).
Preparation of [PtCl2(L3b)] (2b)
A solution of L3a (126 mg, 0.280 mmol) in CH2Cl2 (2 mL) was
added dropwise over 30 s to a stirred solution of [PtCl2(cod)]
(105 mg, 0.280 mmol) in CH2Cl2 (2 mL). The mixture was
stirred for 1 h after which the volatiles were removed under
reduced pressure and then Et2O (60 mL) added to the residue to
give a white solid product (174 mg, 87%) which was then
filtered off, was washed with Et2O and dried under reduced
pressure. Crystals suitable for X-ray analysis were grown by
slow diffusion of diethyl ether into a solution of the product in
CH2Cl2. 31P{1H} NMR (121 MHz, CDCl3): δ 46.9 (PtBu2, d,
J(PPt) = 3425 Hz, J(PP) = 18 Hz), −12.4 (PCg, d, J(PPt) =
3698 Hz, J(PP) = 18 Hz). 1H NMR (400 MHz, CDCl3):
δ 8.75–7.36 (4 H, m), 4.95 (CH2Ar, dd, 1H, J(HH) = 17.0 Hz
J(HP) = 2.0 Hz), 3.98 (CH2Ar, m, 1H), 3.52 (CH2Ar, dd, 1H,
J(HH) = 17.0 Hz J(HP) = 12.1 Hz), 1.94 (CH3, 3H, d, J(HP) =
16.0 Hz), 1.70 (C(CH3)3, 9H, d, J(HP) = 16.0 Hz), 1.59 (CH3,
3H, d, J(HP) = 16.0 Hz), 1.44 (CH3, 3H, s), 1.31 (CH3, 3H, s),
1.13 (C(CH3)3, 9H, d, J(HP) = 16.0 Hz). 13C{1H} NMR
(75 MHz, CDCl3): δ 140.4 (m), 134.3 (m), 128.4 (d, J(CP) =
15 Hz), 124.5 (d, J(CP) = 15 Hz), 123.9 (d, J(CP) = 15 Hz),
97.1 (s), 96.6 (s), 77.5 (d, J(CP) = 37.5 Hz), 75.5 (d, J(CP) =
Preparation of [PtCl(CH3)(L3b)] (3b/4b)
A solution of L3b (101 mg, 0.23 mmol) in toluene (1.5 mL) was
added dropwise over 30 s to a stirred solution of [PtCl(CH3)-
(cod)] (82 mg, 0.23 mmol) in toluene (1.5 mL). The mixture
was stirred overnight. The volatiles were removed under reduced
pressure and the residue was washed with pentane and dried
under reduced pressure affording an off-white solid (46 mg,
29%). Crystals suitable for X-ray analysis were grown by slow
vapour diffusion of hexane into a solution of the product in
CH2Cl2. The product was obtained as a mixture of two isomers
in a 1 : 10 ratio (3b : 4b). 31P{1H} NMR (121 MHz, CD2Cl2):
For 3b: δ 50.2 (PtBu2, d, J(PPt) not discernible, J(PP) = 19 Hz),
−8.2 (PCg, d, J(PPt) not discernible, J(PP) = 19 Hz). For 4b:
δ 47.5 (PtBu2, d, J(PPt) = 4252 Hz, J(PP) = 14 Hz), −5.5 (PCg,
d, J(PPt) = 1539 Hz, J(PP) = 14 Hz). 1H NMR (400 MHz,
This journal is © The Royal Society of Chemistry 2012
Dalton Trans.

View Online
CD2Cl2): δ 8.66–8.62 (1 H, m), 7.45–7.37 (2 H, m), 7.32–7.29
(1 H, m), 4.75 (CHH, 1 H, dd, J(HH) = 13.8 Hz, J(HP) =
3.1 Hz), 3.99 (CHHP, 1 H, td, J(HPt) = 89.9 Hz, J(HH) =
14.3 Hz, J(HP) = 5.7 Hz), 3.41 (CHHP, 1 H, dd, J(HPt) =
44.9 Hz, J(HH) = 14.3 Hz, J(HP) = 9.1 Hz), 1.79 (CH3, 3 H, d,
J(HP) = 13.8 Hz), 1.70 (CHH, 1 H, dd, J(HH) = 22.9 Hz, J(HH)
= 13.8 Hz), 1.63–1.55 (CH2, 2 H, m), 1.51 (C(CH3)3, 9 H, d,
J(HP) = 13.4 Hz), 1.37 (CH3, 6 H, s), 1.28 (CH3, 3 H, s), 1.04
(CH3-Pt, 3 H, dd, J(HPt) = 53.3 Hz, J(HPtrans) = 7.1 Hz,
J(HPcis) = 2.9 Hz), 1.03 (C(CH3)3, 9 H, d, J(HP) = 13.9 Hz).
13C{1H} NMR (100 MHz, CD2Cl2): δ 155.9 (ipso C, s), 141.5
(ipso C, dd, J(CP) = 13.8 Hz, J(CP) = 3.8 Hz), 134.8 (CH, d,
J(CP) = 1.9 Hz), 134.2 (CH, dd, J(CP) = 7.3 Hz, J(CP) =
5.4 Hz), 130.9 (CH, br s), 128.5 (CH, dd, J(CP) = 4.8 Hz, J(CP)
= 2.1 Hz), 97.4 (CO2CH3, d, J(CP) = 0.8 Hz), 96.7 (CO2CH3, d,
J(CP) = 1.2 Hz), 78.7 (COCH3, dd, J(CP) = 10.6 Hz, J(CP) =
1.3 Hz), 74.9 (COCH3, d, J(CP) = 19.2 Hz), 43.9 (CH2, d, J(CP)
= 6.2 Hz), 40.1 (CH2, s), 39.1 (C(CH3)3, dd, J(CP) = 24.2 Hz,
J(CP) = 0.8 Hz), 38.7 (C(CH3)3, dd, J(CP) = 29.6 Hz, J(CP) =
1.2 Hz), 31.9 (C(CH3)3, d, J(CP) = 2.3 Hz), 30.9 (CH2P, dd,
J(CP) = 24.2 Hz, J(CP) = 14.6 Hz), 30.3 (C(CH3)3, d, J(CP) =
2.3 Hz), 29.7 (CH3, d, J(CP) = 10.0 Hz), 28.1 (CH3, s), 27.6
(CH3, s), 25.5 (CH3, d, J(CP) = 5.8 Hz), 2.3 (CH3-Pt, dd,
J(CPtrans) = 88.6 Hz, J(CPcis) = 7.9 Hz). Accurate mass spec-
trum: Mr = 660.2348 (M − Cl)+ (calcd for C26H43O3P2Pt
660.2330).
630.2013). Elemental analysis (calcd for C28H37ClP2Pt): C:
50.07 (50.49), H: 5.61 (5.60).
Synthesis of [PtCl(CH3)(L3d)] (3d/4d)
A solution of L3d (60 mg, 0.13 mmol) in CH2Cl2 (1 mL) was
added dropwise over 30 s to a stirred solution of [PtCl(CH3)-
(cod)] (47 mg, 0.13 mmol) in CH2Cl2 (1 mL). The mixture was
stirred overnight. The volatiles were removed under reduced
pressure and the residue was washed with pentane and dried
under reduced pressure affording a white solid (37 mg, 41%).
Crystals suitable for X-ray analysis were grown from a saturated
solution of the product in CH2Cl2. The product was obtained as
a mixture of four isomers in a 2 : 2 : 3 : 1 ratio (3d : 3d′ : 4d : 4d′)
at room temperature. 31P{1H} NMR (121 MHz, C2D2Cl4): For
3d: δ 52.6 (PtBu2, d, J(PPt) = 1842 Hz, J(PP) = 20 Hz), 14.9
(PAr2, d, J(PPt) = 4392 Hz, J(PP) = 20 Hz). For 3d′: δ 46.9
(PtBu2, d, J(PPt) = 1766 Hz, J(PP) = 20 Hz), 0.0 (PAr2, d,
J(PPt) = 4213 Hz, J(PP) = 20 Hz). For 4d: δ 48.8 (PtBu2, d,
J(PPt) = 4222 Hz, J(PP) = 18 Hz), 12.5 (PAr2, d, J(PPt) = 1593
Hz, J(PP) = 18 Hz). For 4d′: δ 53.1 (PtBu2, d, J(PPt) = 4278 Hz,
J(PP) = 18 Hz), 18.4 (PAr2, d, J(PPt) = 1695 Hz, J(PP) =
18 Hz). 1H NMR (300 MHz, CD2Cl2, 0 °C): δ 8.94 (td, J(HH) =
18.6 Hz, J(HH) = 7.1 Hz), 7.47–6.32 (m), 6.04 (s), 3.81–3.40
(CH2), CH3(C6H5): 2.97 (s), 2.87 (s), 2.62 (s), 2.34 (s),
1.47–1.05 (C(CH3)3, m), 0.27 (CH3-Pt, J(HPt) = 54.6 Hz,
J(HPtrans) = 6.4 Hz, J(HPcis) = 4.4 Hz), 0.12 (CH3-Pt, J(HPt)
= 38.4 Hz, J(HPtrans) = 7.1 Hz, J(HPcis) = 5.0 Hz). 13C{1H}
NMR (75 MHz, CD2Cl2): δ 134.0–130.3 (br), 127.6–125.5 (br),
113.6 (br s), 84.2 (s), 37.5–36.8 (br), 32.1 (s), 31.9 (s), 31.7 (s),
30.6–29.4 (br), 28.2 (br s), 25.2–24–9 (br), 24.1–23.6 (br),
0.8 (s). Accurate mass spectrum: Mr = 658.1978 (M − Cl)+
(calcd for C30H37P2Pt 658.1964).
Preparation of [PtCl(CH3)(L3c)] (3c/4c)
A solution of L3c (66 mg, 0.16 mmol) in CH2Cl2 (1 mL) was
added dropwise over 30 s to a stirred solution of [PtCl(CH3)
(cod)] (55 mg, 0.16 mmol) in CH2Cl2 (1 mL). The mixture was
stirred overnight. The volatiles were removed under reduced
pressure and the residue was washed with pentane and dried
under reduced pressure affording a white solid (46 mg, 54%).
Crystals suitable for X-ray analysis were grown by slow vapour
diffusion of hexane into a solution of the product in CH2Cl2.
The product was obtained as a mixture of two isomers in a 20 : 1
ratio (3c : 4c) at room temperature. 31P{1H} NMR (121 MHz,
CD2Cl2): For 3c: δ 49.8 (PtBu2, d, J(PPt) = 1797 Hz, J(PP) = 21
Hz), −14.4 (PPh2, d, J(PPt) = 4307 Hz, J(PP) = 21 Hz). For 4c:
δ 51.0 (PtBu2, d, J(PPt) not discernible, J(PP) = 21 Hz), −14.1
(PPh2, d, J(PPt) not discernible, J(PP) = 21 Hz). 1H NMR
(270 MHz, CD2Cl2): For 3c: δ 7.54–7.11 (13 H, m), 6.75–6.67
(1 H, m), 3.20–3.03 (CH2, 2 H, br m), 1.29 (C(CH3)3, 18 H, d,
J(HP) = 12.9 Hz), 0.28 (CH3-Pt, 3 H, dd, J(HPt) = 53.6 Hz,
J(HPtrans) = 6.9 Hz, J(HPcis) = 4.3 Hz). For 4c: δ Peaks
obscured by 3c signals, 0.99 (CH3-Pt, 3 H, dd, J(HPt) not dis-
cernible, J(HPtrans) = 7.4 Hz, J(HPcis) = 1.8 Hz). 13C{1H}
NMR (100 MHz, CD2Cl2): δ 142.5 (d, J(CP) = 10.8 Hz), 135.0
(d, J(CP) = 16.1 Hz), 134.7 (d, J(CP) = 11.5 Hz), 133.1 (dd,
J(CP) = 8.5 Hz, J(CP) = 4.6 Hz), 133.8 (d, J(CP) = 2.3 Hz),
129.1 (s), 128.9 (d, J(CP) = 11.5 Hz), 128.7 (d, J(CP) =
10.0 Hz), 127.7 (d, J(CP) = 8.5 Hz), 37.7 (C(CH3)3, d, J(CP) =
13.1 Hz), 30.4 (C(CH3)3, d, J(CP) = 3.8 Hz), 26.1 (CH2, dd,
J(CP) = 16.9 Hz, J(CP) = 10.0 Hz), 14.3 (CH3-Pt, dd,
J(CPtrans) = 92.2 Hz, J(CPcis) = 5.4 Hz). Accurate mass spec-
trum: Mr = 630.2014 (M − Cl)+ (calcd for C28H37P2Pt
Preparation of [PtCl(CH3)(L3e)] (1e/2e)
A solution of L3e (62 mg, 0.13 mmol) in CH2Cl2 (1 mL) was
added dropwise over 30 s to a stirred solution of [PtCl(CH3)-
(cod)] (45 mg, 0.13 mmol) in CH2Cl2 (1 mL). The mixture was
stirred overnight. The volatiles were removed under reduced
pressure and the residue was washed with pentane and dried
under reduced pressure affording a white solid (71 mg, 75%).
The product was obtained as a mixture of two isomers in a 1 : 1
ratio (3e : 4e) at room temperature. 31P{1H} NMR (121 MHz,
CD2Cl2, −40 °C): For 3e: δ 48.0 (PtBu2, d, J(PPt) = 1853 Hz,
J(PP) = 21 Hz), 7.7 (PAr2, d, J(PPt) = 4469 Hz, J(PP) = 21 Hz).
For 4e: δ 48.7 (PtBu2, d, J(PPt) = 4251 Hz, J(PP) = 21 Hz), 10.9
(PAr2, d, J(PPt) = 1768 Hz, J(PP) = 21 Hz). 1H NMR
(400 MHz, CD2Cl2): For 3e or 4e: δ 8.79 (1 H, br s), 7.52–6.79
(7 H, m), 3.68–2.23 (OCH3 + CH2, 7 H, br m), 1.46 (C(CH3)3,
9 H, d, J(HP) = 12.5 Hz), 1.39 (C(CH3)3, 9 H, d, J(HP) =
12.5 Hz), 0.98–0.83 (CH3-Pt, 3 H, m). For 3e or 4e: δ 8.79 (1 H,
br s), 7.52–6.79 (7 H, m), 3.68–2.23 (OCH3 + CH2, 7 H, br m),
1.19 (C(CH3)3, 9 H, d, J(HP) = 12.7 Hz), 1.18 (C(CH3)3, 9 H, d,
J(HP) = 12.7 Hz), −0.04 (CH3-Pt, 3 H, br s, J(HPt) = 52.8 Hz).
13C{1H} NMR (100 MHz, CD2Cl2): δ 162.5 (s), 161.4 (br s),
143.6 (br s), 140.8 (br s), 135.4–134.1 (br signals), 132.9 (br s),
132.2 (br s), 131.6 (br s), 130.5 (br s), 129.9 (br s), 129.1 (s),
Dalton Trans.
This journal is © The Royal Society of Chemistry 2012

View Online
Preparation of [PdCl(CH3)(L3c)] (5c/6c)
128.2 (br s), 127.7 (br s), 126.7 (br s), 126.2 (br s), 120.9 (d,
J(CP) = 14.0 Hz), 120.8 (d, J(CP) = 14.8 Hz), 120.5 (br s),
120.3 (br s), 115.6 (s), 114.0 (s), 112.2 (br d, J(CP) = 27.3 Hz),
56.1 (br s), 55.8 (br s), 55.2 (br s), 37.6 (br d, J(CP) = 10.9 Hz),
37.4 (br d, J(CP) = 15.6 Hz), 32.4 (s), 31.1 (br s), 31.0 (br s),
30.2 (br s), 30.1 (br d, J(CP) = 3.9 Hz), 28.5 (s), 27.6 (br s),
25.9 (br s), 22.9 (s), 14.4 (dd, J(CPtrans) = 94.2 Hz), J(CPcis) =
28.0 Hz), 12.1 (dd, J(CPtrans) = 65.4 Hz, J(CPcis) = 33.5 Hz).
Accurate mass spectrum: Mr = 690.2241 (M − Cl)+ (calcd for
C30H41O2P2Pt 690.2224). Elemental analysis (calcd for
C30H41ClO2P2Pt): C: 49.99 (49.62), H: 5.91 (5.69).
A solution of L3c (95 mg, 0.22 mmol) in CH2Cl2 (1 mL) was
added dropwise over 30 s to a stirred solution of [PdCl(CH3)
(cod)] (40 mg, 0.22 mmol) in CH2Cl2 (1 mL). The solution was
stirred overnight and then filtered through Celite® to remove
Pd(0). The volatiles were removed under reduced pressure and
the residue was washed with pentane and dried under reduced
pressure affording a pale brown solid (91 mg, 72%). The product
was obtained as a mixture of two isomers in a 25 : 1 ratio
(5c : 6c) at room temperature. 31P{1H} NMR (162 MHz,
CD2Cl2): For 5c: δ 47.3 (PtBu2, d, J(PP) = 45 Hz), 34.5 (PPh2,
d, J(PP) = 45 Hz). For 6c: 75.2 (PtBu2, d, J(PP) = 41 Hz), 9.0
(PPh2, d, J(PP) = 41 Hz). 1H NMR (400 MHz, CD2Cl2): For 5c:
δ 7.58–7.18 (13 H, m), 6.76–6.72 (1 H, m), 2.90 (CH2, br d,
J(HP) = 5.4 Hz), 1.29 (C(CH3)3, 18 H, d, J(HP) = 12.7 Hz),
0.54 (CH3-Pd, dd, J(HPtrans) = 7.3 Hz, J(HPcis) = 3.7 Hz). For
6c: δ 7.58–6.72 (obscured by 5c), 3.01 (CH2, 2 H, br m), 1.09
(C(CH3)3, 18 H, d, J(HP) = 11.0 Hz), 1.04 (CH3-Pd, 3 H, dd,
J(HPtrans) = 7.8 Hz, J(HPcis) = 2.0 Hz). 13C{1H} NMR
(100 MHz, CD2Cl2): δ 142.7 (d, J(CP) = 12.5 Hz), 134.8 (br s),
134.7 (br s), 134.5 (d, J(CP) = 13.2 Hz), 134.3 (d, J(CP) = 13.6
Hz), 133.3 (dd, J(CP) = 8.2 Hz, J(CP) = 4.3 Hz), 131.8 (d,
J(CP) = 2.3 Hz), 131.5 (d, J(CP) = 2.3 Hz), 129.2 (d, J(CP) =
11.3 Hz), 127.8 (dd, J(CP) = 7.8 Hz, J(CP) = 2.3 Hz), 36.9
(C(CH3)3, d, J(CP) = 4.7 Hz), 30.2 (C(CH3)3, d, J(CP) =
4.7 Hz), 27.0 (CH2, dd, J(CP) = 11.7 Hz, J(CP) = 8.2 Hz), 17.7
(CH3-Pd, dd, J(CPtrans) = 100.0 Hz, J(CPcis) = 1.6 Hz). Accu-
rate mass spectrum (ESI): Mr = 541.1414 (M − Cl)+ (calcd for
C28H37P2Pd 541.1400). Elemental analysis (calcd for
C28H37ClP2Pt): C: 59.68 (58.24), H: 6.72 (6.46).
Preparation of [PtCl(CH3)(L3f)] (3f/4f)
A solution of L3f (46 mg, 0.090 mmol) in CH2Cl2 (1 mL) was
added dropwise over 30 s to a stirred solution of [PtCl(CH3)-
(cod)] (31 mg, 0.090 mmol) in CH2Cl2 (1 mL). The mixture was
stirred overnight. The volatiles were removed under reduced
pressure and the residue was washed with pentane and dried
under reduced pressure affording a pale yellow solid (59 mg,
85%). 31P{1H} NMR (121 MHz, CD2Cl2): δ 11.3 (PCH2Cg, d,
J(PPt) = 4328 Hz, J(PP) = 13 Hz), −6.1 (PCg, d, J(PPt) =
1403 Hz, J(PP) = 13 Hz). The 31P NMR spectrum of the product
showed the presence of only one isomer (4f) and from the signal
to noise ratio, it was therefore deduced that the ratio 4f : 3f was
at least 30 : 1. Accurate mass spectrum: Mr = 730.2030
(M − Cl)+ (calcd for C28H41O6P2Pt 730.2021).
Preparation of [PdCl(CH3)(L3b)] (5b/6b)
A solution of L3b (70 mg, 0.16 mmol) in CH2Cl2 (2 mL) was
added dropwise over 30 s to a stirred solution of [PdCl(CH3)-
(cod)] (43 mg, 0.16 mmol) in CH2Cl2 (2 mL). The solution was
stirred overnight and then filtered through Celite® to remove
Pd(0). The volatiles were removed under reduced pressure and
the residue was washed with pentane and dried under reduced
pressure affording an orange solid (49 mg, 50%). The product
was obtained as a mixture of two isomers in a 1 : 37 ratio
(5b : 6b) at room temperature. 31P{1H} NMR (162 MHz,
CD2Cl2): For 5b: δ 60.5 (PtBu2, d, J(PP) = 9 Hz), −39.4 (PCg,
d, J(PP) = 9 Hz). For 6b: δ 70.3 (PtBu2, d, J(PP) = 34 Hz),
Generation of [PdCl(13COCH3)(L3b)] (7b/8b)
A three-necked flask provided with a stirring bar was connected
to a 13CO gas cylinder and a Schlenk line via a T-shape connec-
tor with an oil bubbler. When the system was under 13CO atmos-
phere,
a solution of [PdCl(CH3)(L3b)] (5b/6b) (60 mg,
0.10 mmol) in CD2Cl2 (0.7 mL) was placed and the mixture was
stirred for 20 min. 31P{1H} NMR (121 MHz, CD2Cl2): Data
only discernible for major isomer 8b: δ 59.4 (PtBu2, br d, J(PP)
= 48 Hz, J(13CPcis) not resolved), −21.4 (PCg, dd, J(13CPtrans)
= 101 Hz, J(PP) = 48 Hz). 13C{1H} NMR (75 MHz, CD2Cl2):
δ 228.4 ({13C(O)(CH3)}-Pd, dd, J(13CPtrans) = 101.0 Hz,
J(13CPcis) = 14.5 Hz). IR (cm−1): νCO 1638.
1
−16.7 (PCg, d, J(PP) = 34 Hz). H NMR (400 MHz, CD2Cl2):
For 5b: δ 7.55–7.09 (4 H, m), 4.65 (CH2, 2 H, dd, J(HH) =
13.9 Hz, J(HP) = 3.9 Hz), 3.30–3.19 (CH2P, 2 H, m), 1.94–0.89
(37 H, m). For 6b: δ 8.77–8.73 (1 H, m), 8.63–8.59 (1 H, m),
8.18 (1 H, d, J(HH) = 8.0 Hz), 7.94–7.90 (1 H, m), 4.87 (CH2,
2 H, dd, J(HH) = 13.9 Hz, J(HP) = 2.5 Hz), 3.66–3.54 (CH2P,
2 H, m), 1.94–0.89 (37 H, m). 13C{1H} NMR (100 MHz,
CD2Cl2): δ 142.1 (d, J(CP) = 10.1 Hz), 139.0 (s), 135.0 (s),
134.3–134.2 (m), 130.8 (d, J(CP) = 1.5 Hz), 128.6–128.5 (m),
97.6 (CO2CH3, s), 96.7 (CO2CH3, s), 77.4 (COCH3, s), 75.3
(COCH3, d, J(CP) = 11.7 Hz), 43.6 (CH2, d, J(CP) = 7.8 Hz), 39.2
(CH2, s), 32.2 (C(CH3)3, d, J(CP) = 1.6 Hz), 31.9 (C(CH3)3, d,
J(CP) = 2.3 Hz), 31.6 (C(CH3)3, d, J(CP) = 3.1 Hz), 30.5 (C(CH3)3,
d, J(CP) = 3.1 Hz), 29.7 (CH2P, d , J(CP) = 12.5 Hz), 28.0 (CH3,
s), 27.6 (CH3, s), 27.2 (CH3, s), 26.2 (CH3, d, J(CP) = 7.0 Hz),
4.7 (CH3-Pd, dd, J(CPtrans) = 88.0 Hz, J(CPcis) = 5.5 Hz). ESI
mass spectrum: m/z 457.1 (M − Cl)+.
Generation of [PdCl(13COCH3)(L3c)] (7c/8c)
A three-necked flask provided with a stirring bar was connected
to a 13CO gas cylinder and a Schlenk line via a T-shape connec-
tor with an oil bubbler. When the system was under 13CO atmos-
phere,
a solution of [PdCl(CH3)(L3c)] (5c/6c) (50 mg,
0.09 mmol) in CD2Cl2 (0.7 mL) was placed and the mixture was
stirred for 30 min. The product was obtained as a mixture of two
isomers in a 9 : 1 ratio (7c : 8c) at room temperature. 31P{1H}
NMR (121 MHz, CD2Cl2): For 7c: δ 39.2 (PtBu2, dd,
J(13CPtrans) = 120 Hz, J(PP) = 71 Hz), 14.6 (PPh2, dd, J(PP) =
71 Hz, J(13CPcis) = 16 Hz). For 8c: δ 63.9 (PtBu2, dd, J(PP) =
68 Hz, J(13CPcis) = 16 Hz), 5.6 (PPh2, dd, J(13CPtrans) =
This journal is © The Royal Society of Chemistry 2012
Dalton Trans.

View Online
Table 2 Crystallographic data
Compound
1a·CH2Cl2
2a·CH2Cl2
2b·CH2Cl2
3c/4c
Colour, habit
Size/mm
Empirical formula
M
Colourless plate
0.4 × 0.4 × 0.05
C25H45Cl5P2Pt
779.89
Colourless plate
0.2 × 0.1 × 0.05
C24H44Cl4P2Pt
731.42
Yellow block
0.15 × 0.15 × 0.05
C26H42Cl4O3P2Pt
801.43
Colourless rhomboid
0.49 × 0.47 × 0.15
C27 87
. H36.61Cl1.13P2Pt
668.70
Crystal system
Space group
Monoclinic
P21/c
Monoclinic
P21/c
Triclinic
P1
Monoclinic
P21/n
ˉ
a/Å
b/Å
c/Å
a/°
7.4494(2)
22.2352(7)
18.5251(6)
90.00
9.4152(5)
21.846(1)
15.4768(7)
90.00
12.461(3)
15.187(3)
17.334(4)
85.45(3)
11.4182(1)
15.7441(1)
15.0578(1)
90.00
b/°
95.723(2)
90.00
3053.18(16)
4
115.504(3)
90.00
2873.1(2)
4
79.62(3)
77.63(3)
3148.8(12)
4
4.923
103.5301(8)
90.00
2631.80(3)
4
g/°
V/Å3
Z
m/mm−1
5.152
5.379
5.582
T/K
qmin,max
Completeness
Reflections: total/independent
Rint
120
293
173
100
2.24, 30.10
0.999 to q = 30.10°
142 333/7730
0.0458
2.39, 32.43
0.962 to q = 32.43°
10 671/10 671
0.0000a
1.73, 27.54
0.997 to q = 27.54°
48 854/6613
0.0225
1.20, 27.48
0.994 to q = 27.48°
36 228/14 356
0.0564
Final R1 and wR2
Largest peak, hole/eÅ−3
rcalc/g cm−3
0.0837, 0.1808
5.077, −4.063
1.697
0.0216, 0.0566
1.171, −1.801
1.691
0.0426, 0.0881
3.402, −2.557
1.691
0.0254, 0.0592
3.368, −1.200
1.688
Compound
3d/4d
4a
4b
4f·CH2Cl2
Colour, habit
Size/mm
Empirical Formula
M
Crystal system
Space group
a/Å
b/Å
0.12 × 0.10 × 0.08
C30H41ClP2Pt
694.10
Monoclinic
P21/c
10.9460(5)
15.7116(6)
18.9402(7)
90.00
120.965(3)
90.00
Colourless block
0.12 × 0.12 × 0.07
C48H90Cl2P4Pt2
1252.16
Monoclinic
P21/c
15.9715(7)
20.0553(8)
18.7186(8)
90.00
118.759(3)
90.00
Colourless block
0.27 × 0.21 × 0.19
C26H43ClO3P2Pt
696.07
Monoclinic
P21/c
11.0658(1)
14.8858(1)
17.0888(2)
90.00
102.379(1)
90.00
Colourless block
0.33 × 0.26 × 0.08
C29H43Cl3O6P2Pt
851.01
Monoclinic
P21
10.588(4)
14.583(5)
11.873(4)
90.00
116.01(2)
90.00
c/Å
a/°
b/°
g/°
2793.1(2)
4
5.251
V/Å3
5256.2(4)
4
5.571
2749.48(4)
4
5.342
1647.6(10)
2
4.638
Z
m/mm−1
100
T/K
qmin,max
2.51, 27.58
0.994 to q = 27.58°
81 357/6438
0.0610
0.0393, 0.0871
1.600, −2.065
1.651
100
173
100
1.45, 27.52
0.996 to q = 27.52°
54 476/12 047
0.0814
0.0405, 0.0954
1.792, −1.340
1.582
2.43, 30.11
0.997 to q = 30.11°
140 525/8071
0.0468
0.0243, 0.0637
3.137, −0.947
1.682
2.57, 30.52
0.997 to q = 30.52°
24 888/9839
0.0262
0.0197, 0.0402
1.666, −0.920
1.715
Completeness
Reflections: total/independent
Rint
Final R1 and wR2
Largest peak, hole/eÅ−3
rcalc/g cm−3
Flack parameter
0.006(3)
a Non-merohedral twin.
1
128 Hz, J(PP) = 68 Hz). H NMR (300 MHz, CD2Cl2): For 7c:
δ 7.71–7.01 (13 H, m), 6.72–6.67 (1 H, m), 2.81 (CH2, 2 H, br
d, J(HP) = 6.3 Hz), 2.04 (CH313C(O), 3 H, br dd, J(H13C) =
5.6 Hz, J(HPtrans) = 1.2 Hz), 1.25 (C(CH3)3, 18 H, d, J(HP) =
12.6 Hz). For 8c: δ 8.37–8.29 (1 H, m), 7.71–7.01 (13 H, m),
3.48 (CH2, 2 H, br d, J(HP) = 11.1 Hz), 2.66 (CH313C(O), 3 H,
br dd, J(H13C) = 5.5 Hz, J(HPtrans) = 1.0 Hz), 1.39 (C(CH3)3,
18 H, d, J(HP) = 14.8 Hz). 13C{1H} NMR (75 MHz, CD2Cl2):
For 7c: δ 242.0 ({13C(O)(CH3)}-Pd, dd, J(13CPtrans) = 120.4
Hz, J(13CPcis) = 16.4 Hz), 142.6 (d, J(CP) = 13.4 Hz),
135.5–134.6 (br), 134.3–134.2 (br), 133.8–133.5 (br),
133.1–132.8 (br), 132.5–131.6 (br), 130.6 (br s), 129.9–128.8
(br), 127.9–127.7 (br), 40.5 (br s), 40.3 (br s), 36.3–36.2 (br),
30.7 (br s), 30.1 (s), 30.0 (s), 27.0 (s). For 8c: δ 241.4 ({13C(O)
(CH3)}-Pd, dd, J(13CPtrans) = 126.4 Hz, J(13CPcis) = 13.2 Hz).
Crystal structure determinations
All X-ray diffraction experiments were carried out using Mo-Ka
radiation (λ = 0.71073 Å). Diffraction data for 2b were collected
on a Bruker SMART diffractometer at 173 K. Collections for 1a,
2a, 3d/4d, 4a and 4f were carried out at 100 K on a Bruker
APEX II diffractometer. Collections for 3c/4c and 4b were
carried out using an Oxford Diffraction Gemini diffractometer,
Dalton Trans.
This journal is © The Royal Society of Chemistry 2012

View Online
Kluwer Academic Publishers, Dordrecht, 2003; (b) G. Kiss, Chem. Rev.,
2001, 101, 3435.
6 (a) E. Zuidema, P. W. N. M. van Leeuwen and C. Bo, Organometallics,
2005, 24, 3703; (b) E. Zuidema, C. Bo and P. W. N. M. van Leeuwen,
J. Am. Chem. Soc., 2007, 129, 3989.
7 (a) T. Fanjul, G. R. Eastham, N. Fey, A. Hamilton, A. G. Orpen,
P. G. Pringle and M. Waugh, Organometallics, 2010, 29, 2292;
(b) T. Fanjul Solares, G. R. Eastham, P. G. Pringle and M. Waugh, World
Patent, 2010, WO2010001174 (to Lucite).
also at 100 K. Data collections were performed using a CCD
area detector from a single crystal mounted on a glass fibre.
Intensities were integrated23,24 from several series of exposures
measuring 1° (3c/4c, 4b) or 0.5° (all others) in ω or ϕ. Absorp-
tion corrections were based on equivalent reflections using Crys-
Alis RED24 (3c/4c, 4b), TWINABS (1) or SADABS.25 The
2
structures were solved using SHELXS and refined against all Fo
8 T. Fanjul, G. R. Eastham, M. F. Haddow, A. Hamilton, P. G. Pringle,
A. G. Orpen, T. P. W. Turner and M. Waugh, Catal. Sci. Technol., 2012,
2, 937.
9 V. de la Fuente, M. Waugh, G. R. Eastham, J. A. Iggo, S. Castillon and
C. Claver, Chem.–Eur. J., 2010, 16, 6919.
data with hydrogen atoms riding in calculated positions using
SHELXL.26 Crystal structure and refinement data are given in
Table 2. The crystal of 1a was a non-merohedral twin with two
domains. These were indexed independently and integrated
simultaneously using the APEX II software. Refinement
proceeded smoothly to give the structure shown and a ratio of
0.53 : 0.47 for the different domains.
10 (a) P. Jankowski, C. L. McMullin, I. D. Gridnev, A. G. Orpen and
P. G. Pringle, Tetrahedron: Asymmetry, 2010, 21, 1206; (b) D. L. Dodds,
J. Floure, M. Garland, M. F. Haddow, T. R. Leonard, C. L. McMullin,
A. G. Orpen and P. G. Pringle, Dalton Trans., 2011, 40, 7137;
(c) J. Hopewell, P. Jankowski, C. L. McMullin, A. G. Orpen and
P. G. Pringle, Chem. Commun., 2010, 46, 100; (d) J. H. Downing,
J. Floure, K. Heslop, M. F. Haddow, J. Hopewell, M. Lusi, H. Phetmung,
A. G. Orpen, P. G. Pringle, R. I. Pugh and D. Zambrano-Williams, Orga-
nometallics, 2008, 27, 3216; (e) R. A. Baber, M. L. Clarke,
K. M. Heslop, A. C. Marr, A. G. Orpen, P. G. Pringle, A. Ward and
D. E. Zambrano-Williams, Dalton Trans., 2005, 1079; (f) P. G. Pringle
and M. B. Smith, in Phosphorus(III) Ligands in Homogeneous Catalysis,
ed. P. C. J. Kamer and P. W. N. M. van Leeuwen, Wiley, 2012.
11 G. Eastham, World Patent, 2005, WO2005118519.
Acknowledgements
We are grateful to Lucite, Shell and EPSRC for studentships, the
Royal Society, and COST action CM0802 “PhoSciNet” for sup-
porting this work, and Johnson Matthey for a loan of precious
metal compounds. We thank Oxford Diffraction (now Agilent
Technologies) for the loan of an Oxford Gemini instrument.
12 The crystal structure of the palladium analogue [PdCl2(L3b)] has also
been determined and details are deposited in the ESI.†
13 R. A. Baber, A. G. Orpen, P. G. Pringle, M. J. Wilkinson and
R. L. Wingad, Dalton Trans., 2005, 659.
References
1 (a) G. R. Eastham, R. P. Tooze, X. L. Wang and K. Whiston, World
Patent, 1996, 96/19434; (b) W. Clegg, G. R. Eastham, M. R. J. Elsegood,
R. P. Tooze, X. L. Wang and K. Whiston, Chem. Commun., 1999, 1877.
2 P. W. N. M. van Leeuwen, M. A. Zuideveld, B. H. G. Swennenhuis,
Z. Freixa, P. C. J. Kamer, K. Goubitz, J. Fraanje, M. Lutz and
A. L. Spek, J. Am. Chem. Soc., 2003, 125, 5523.
14 A. Bondi, J. Phys. Chem., 1964, 68, 441.
15 R. G. Pearson, Inorg. Chem., 1973, 12, 712.
16 (a) E. Drent, J. A. M. Broekhoven and P. H. M. Budzelaar, Applied
Homogeneous Catalysis with Organometallic Compounds, ed. B. Cornils
and W. A. Herrman, VCH, 1996; (b) C. Bianchini, A. Meli and
W. Oberhauser, Dalton Trans., 2003, 2627; (c) G. R. Eastham,
R. P. Tooze, M. Kilner, D. F. Foster and D. J. Cole-Hamilton, J. Chem.
Soc., Dalton Trans., 2002, 1613; (d) I. Tóth, T. Kégl, C. J. Elsevier and
L. Kollár, Inorg. Chem., 1994, 33, 5708; (e) P. W. N. M. van Leeuwen,
C. F. Roobeek and H. van der Heijden, J. Am. Chem. Soc., 1994, 116,
12117.
17 (a) W. Clegg, G. R. Eastham, M. R. J. Elsegood, B. T. Heaton,
J. A. Iggo, R. P. Tooze, R. Whyman and S. Zacchini, Organometallics,
2002, 21, 1832; (b) J. Liu, B. T. Heaton, J. A. Iggo and R. Whyman,
Chem. Commun., 2004, 1326; (c) S. M. A. Donald, S. A. Macgregor,
V. Settels, D. J. Cole-Hamilton and G. R. Eastham, Chem. Commun.,
2007, 562; (d) J. Liu, B. T. Heaton, J. A. Iggo and R. Whyman, Angew.
Chem., Int. Ed., 2004, 43, 90; (e) G. R. Eastham, B. T. Heaton,
J. A. Iggo, R. P. Tooze, R. Whyman and S. Zacchini, Chem. Commun.,
2000, 609; (f) W. Clegg, G. R. Eastham, M. R. J. Elsegood,
B. T. Heaton, J. A. Iggo, R. P. Tooze, R. Whyman and S. Zacchini,
J. Chem. Soc., Dalton Trans., 2002, 3300; (g) J. Wolowska,
G. R. Eastham, B. T. Heaton, J. A. Iggo, C. Jacob and R. Whyman,
Chem. Commun., 2002, 2784.
3 (a) E. Drent and K. Kragtwijk, Eur. Patent, 1992, EP 495548 (to Shell);
(b) J. C. L. Suykerbujk, E. Drent and P. G. Pringle, World Patent, 1997,
WO 98/42717; (c) V. Gee, A. G. Orpen, H. Phetmung, P. G. Pringle and
R. I. Pugh, Chem. Commun., 1999, 901; (d) R. I. Pugh, E. Drent and
P. G. Pringle, Chem. Commun., 2001, 1476; (e) E. Drent, P. G. Pringle
and R. I. Pugh, World Patent, 2001, WO 2001028972 (to Shell);
(f) E. Drent, R. H. van der Made and R. I. Pugh, World Patent, 2003,
WO2003070679 (to Shell); (g) J. G. Knight, S. Doherty, A. Harriman,
E. G. Robins, M. Betham, G. R. Eastham, R. P. Tooze,
M. R. J. Elsegood, P. Champkin and W. Clegg, Organometallics, 2000,
19, 4957; (h) S. Doherty, E. G. Robins, J. G. Knight, C. T. Newman,
B. Rhodes, P. A. Champkin and W. Clegg, J. Organomet. Chem., 2001,
640, 182; (i) O. V. Gusev, A. M. Kalsin, M. G. Peterleitner,
P. V. Petrovskii, K. A. Lyssenko, N. G. Akhmedov, C. Bianchini, A. Meli
and W. Oberhauser, Organometallics, 2002, 21, 3637; ( j) R. I. Pugh and
E. Drent, Adv. Synth. Catal., 2002, 344, 837; (k) O. V. Gusev,
A. M. Kalsin, P. V. Petrovskii, K. A. Lyssenko, Y. F. Oprunenko,
C. Bianchini, A. Meli and W. Oberhauser, Organometallics, 2003, 22,
913; (l) G. Smith, N. R. Vautravers and D. J. Cole-Hamilton, Dalton
Trans., 2009, 872; (m) N. R. Vautravers and D. J. Cole-Hamilton, Dalton
Trans., 2009, 2130; (n) G. R. Eastham and I. Butler, World Patent, 2008,
WO 2008065448 (to Lucite); (o) G. R. Eastham, C. Jimenez and
D. Cole-Hamilton, World Patent, 2004, WO 2004014834 (to Lucite);
(p) G. R. Eastham, P. A. Cameron, R. P. Tooze, K. J. Cavell,
P. G. Edwards and D. L. Coleman, World Patent, 2004, WO 2004014552
(to Lucite); (q) G. R. Eastham, World Patent, 2005, WO 2005079981
(to Lucite).
18 A. B. Pangborn, M. A. Giardello, R. H. Grubbs, R. K. Rosen and
F. J. Timmers, Organometallics, 1996, 15, 1518.
19 H. C. Clark and L. E. Manzer, J. Organomet. Chem., 1973, 59, 411.
20 H. C. Clark and L. E. Manzer, J. Organomet. Chem., 1973, 59, 411.
21 R. E. Rulke, I. M. Han, C. J. Elsevier, K. Vrieze, P. W. M. N. van
Leeuwen, C. F. Roobeek, M. C. Zoutberg, Y. F. Wang and C. H. Stam,
Inorg. Chim. Acta, 1990, 169, 5.
22 H.-P. Abicht and K. Issleib, J. Organomet. Chem., 1980, 185, 265.
23 Bruker-AXS SAINT V7.65 or 7.68A, Madison, Wisconsin.
24 Oxford Diffraction. CrysAlis RED V1.171.32.5, Oxford Diffraction Ltd,
Abingdon, England, 2007.
4 (a) C. Bianchini, A. Meli, W. Oberhauser, P. W. N. M. van Leeuwen,
M. A. Zuideveld, Z. Freixa, P. C. J. Kamer, A. L. Spek, O. V. Gusev and
A. M. Kalsin, Organometallics, 2003, 22, 2409; (b) Z. Freixa and
P. W. N. M. van Leeuwen, Dalton Trans., 2003, 1890.
25 G. M. Sheldrick, SADABS V2008/1 or TWINABS V2008/4, University of
Göttingen, Germany.
5 (a) D. J. Cole-Hamilton and R. A. M. Robertson, in Catalytic Synthesis
of Alkene-Carbon Monoxide Copolymers and Cooligomers, ed. A. Sen,
26 G. M. Sheldrick, Acta Crystallogr., Sect. A: Found. Crystallogr., 2008,
64, 112–122.
This journal is © The Royal Society of Chemistry 2012
Dalton Trans.