The molecular structure of a 2-aryl-1,3,2-dioxaphospholane and its coordination behaviour towards platinum(II) species; molecular structures of four platinum(II) complexes

Article abstract of DOI:10.1016/j.poly.2009.07.040

The molecular structure of the 2-aryl-1,3,2-dioxaphospholane, 2,6-(CF₃)₂-C₆H₃-P(OCH₂)₂ (1), has been determined by single-crystal X-ray diffraction at 120 K. Its reactions with the platinum

Full text of DOI:10.1016/j.poly.2009.07.040

Polyhedron 29 (2010) 606–612
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
The molecular structure of a 2-aryl-1,3,2-dioxaphospholane
and its coordination behaviour towards platinum(II) species; molecular
structures of four platinum(II) complexes
*
Keith B. Dillon, Andrés E. Goeta, Philippa K. Monks , Helena J. Shepherd
Chemistry Department, Durham University, South Road, Durham DH1 3LE, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
Available online 26 July 2009
The molecular structure of the 2-aryl-1,3,2-dioxaphospholane, 2,6-(CF3)2-C6H3-P(OCH2)2 (1), has been
determined by single-crystal X-ray diffraction at 120 K. Its reactions with the platinum(II) dimers
trans-[PtCl(l-Cl)(PEt3)]2, trans-[PtCl(l-Cl)(PPh2Me)]2, trans-[PtCl(l-Cl)(PPhMe2)]2 and trans-[PtBr(l-
Br)(PEt3)]2 have been investigated using 31P NMR solution-state spectroscopy. Monomeric trans- and
cis-Pt(II) complexes were formed; the molecular structures of cis-[PtCl2(L)(PR2R0)] (R@R0@Et (3), R@Ph,
R0@Me (7)), cis-[PtBr2L(PEt3)] (9) and cis-[PtCl2L2] (10), where L = 2,6-(CF3)2-C6H3-P(OCH2)2, have been
ascertained at 120 K.
Keywords:
Phosphonite
Phospholane
Platinum(II) complexes
Molecular structures
Phosphorus NMR
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
ene chlorophosphite [10]. The formation of 1 was confirmed using
4
both 31P{1H} (septet, 158.2 ppm, JP–F = 35 Hz) and 19F NMR spec-
4
Complexes containing chiral phosphonites have been shown
to act as catalysts for asymmetric hydrogenation [1–7] and
asymmetric hydroformylation reactions [8,9]. Some 2-aryl-1,3,2-
dioxaphospholanes (cyclic phosphonites), including 2,6-(CF3)2-C6H3-
P(OCH2)2, have previously been prepared as potential precursors,
via pyrolysis reactions, for metaphosphate intermediates [10].
With the exception of this reaction, there have been no reported
investigations into the reactivity or coordination properties of
2,6-(CF3)2-C6H3-P(OCH2)2. Contrastingly, the coordination behav-
iour of benzo-3-(2,4,6-tri–tert-butylphenyl)-1,3,2-dioxaphospho-
lane has previously been studied [11]. A gold(I) complex was
prepared, but attempts to synthesise Pt(II) complexes of this ligand
were unsuccessful, probably due to the steric bulk around the P(III)
centre. Furthermore few 1,3,2-dioxaphospholanes have been struc-
turally characterised [12–19].
troscopy (d, ꢀ55.5 ppm, JF–P = 35 Hz) [10]. Crystals suitable for
an X-ray structure determination were obtained, and the molecu-
lar structure at 120 K is shown in Fig. 1, with selected bond dis-
tances and angles listed in Table 1.
2,6-(CF3)2-C6H3-P(OCH2)2, (1), crystallises in the orthorhombic
space group Pnma. There is a mirror plane along the P1–C1 bond
which bisects both the aromatic 6-membered and the 5-membered
rings, while the 5-membered heterocycle adopts an envelope
conformation.
A few cyclic organophosphites have previously been structur-
ally characterised [12–19]. The P–O bond distances in these com-
pounds range between 1.558(3) and 1.702(2) Å, in good
agreement with 1.634(1) Å determined for 1 [12–19]. The P–C
bond distances for the cyclic organophosphites vary between
1.790(5) and 1.9135(21) Å, depending on the nature of the substi-
tuent. Hence the P–C bond length in 1 (1.894(2) Å) is also similar to
those previously reported [12–19].
It was therefore of considerable interest to investigate the struc-
ture and coordination chemistry of 3-(2,6-bis-(trifluoromethyl)-
phenyl)-1,3,2-dioxaphospholane, 2,6-(CF3)2-C6H3-P(OCH2)2, which
could act as a sterically hindered and electron-poor ligand.
2.1. Coordination properties
2. Results and discussion
In order to investigate its coordination properties towards plat-
inum(II), 1 was reacted separately in a 2:1 molar ratio with the
The 2-aryl-1,3,2-dioxaphospholane, 2,6-(CF3)2-C6H3-P(OCH2)2
(1), was prepared as previously described in a two-step reaction
of TMEDA, nBuLi and 1,3-bis-(trifluoromethyl)benzene with ethyl-
dimeric
Cl)(PPhMe2)]2, trans-[PtCl(
complexes
trans-[PtCl(
l
-Cl)(PEt3)]2,
trans-[PtCl(
l
-
-
l-Cl)(PPh2Me)]2 and trans-[PtBr(
l
Br)(PEt3)]2 (Scheme 1). The reactions were followed by 31P NMR
solution-state spectroscopy. Monomeric platinum(II) complexes
of the general formula [PtX2(L)(PR2R0)], where L = 2,6-(CF3)2-
C6H3-P(OCH2)2, were formed as the major products in each case
* Corresponding author. Tel.: +44 (0)191 334 2084; fax: +44 (0)191 384 4737.
E-mail address: p.k.monks@durham.ac.uk (P.K. Monks).
0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.07.040

K.B. Dillon et al. / Polyhedron 29 (2010) 606–612
607
plexes are shown in Table 2. In all instances where trans/cis pairs
2
were formed, the trans isomer showed a much larger JP–P value
1
and a relatively smaller JPt–P value than the cis isomer, in accor-
dance with literature data [20,21].
The reaction of 1 with trans-[PtCl(l-Cl)(PEt3)]2 initially showed
formation of trans-[PtCl2(L)(PEt3)] (2) which converted to the cis
isomer 3 on standing. Yellow crystals of the cis isomer 3 suitable
for X-ray diffraction studies were isolated. The molecular structure
of 3 at 120 K is shown in Fig. 2, while selected bond distances and
angles are listed in Table 3.
Reaction of 1 with trans-[PtCl(l-Cl)(PPhMe2)]2 afforded a trans
2
complex, 4, as indicated by the large JP–P (691 Hz) and small
1JPt–P coupling constants (Table 2) [20,21]. Signals corresponding
to two minor products of the reaction (<5%) were also observed
in the 31P{1H} NMR spectrum. These were assigned to ligand
scrambling products, cis-[PtCl2L2] (10), where L = 2,6-(CF3)2-C6H3-
P(OCH2)2, and cis-[PtCl2(PPhMe2)2] (11) (Fig. 3, Table 2). Upon
standing 4 converted slowly to the more thermodynamically stable
product, cis-[PtCl2(L)(PPhMe2)] (5). The 31P{1H} NMR data for this
complex are shown in Table 2. Attempts to obtain crystalline mate-
rial of either 4 or 5 from the reaction mixture were unsuccessful.
Fig. 1. The molecular structure of 2,6-(CF3)2-C6H3-P(OCH2)2 (1). Thermal ellipsoids
are drawn at 50% probability.
By repeating the reaction of 1 with trans-[PtCl(l-Cl)(PPhMe2)]2,
micro-crystalline material was isolated, but was unsuitable for
analysis by X-ray diffraction. Gentle heating of the solution to
redissolve this material appeared to promote ligand scrambling,
and crystals of cis-[PtCl2L2] (10), were isolated as the major prod-
uct. The molecular structure of 10 was ascertained at 120 K, and
its structure is shown in Fig. 4, with selected bond lengths and an-
gles reported in Table 4. Although the ligand scrambling products
were initially minor products in this reaction, exchange reactions
of this type are known for similar Pt(II) complexes, where upon
prolonged standing complete ligand exchange was found to occur
[22]. Ligand scrambling has also been reported between two plat-
inum complexes PtX2L2 and PtR2L2 (where X = halide/anionic li-
gand, R = aryl/alkyl and L = tertiary phosphine/arsine) to afford
cis-[PtXRL2], which then converts to the trans isomer [23–25].
(Scheme 1). Initially the trans isomers were formed as the kinetic
products, and these converted slowly to the more thermodynami-
cally stable cis isomers on standing. 31P{1H} NMR data for the com-
Table 1
Selected bond distances (Å) and bond angles (°) for 2,6-(CF3)2-C6H3-P(OCH2)2 (1).
Bond distances (Å)
P(1)–O(1)
P(1)–O(1A)
P(1)–C(4)
F(1)–C(5)
O(1)–C(6)
C(1)–C(2)
1.634(1)
1.634(1)
1.894(2)
1.340 (2)
1.439(2)
1.382(2)
Reaction of 1 with trans-[PtCl(l-Cl)(PPh2Me)]2 initially afforded
Bond angles (°)
O(1)–P(1)–O(1A)
O(1A)–P(1)–C(4)
O(1)–P(1)–C(4)
93.87(7)
98.41(5)
98.41(5)
four platinum-containing complexes, including both the trans
(10%) (6) and cis (50%) (7) complexes (Scheme 1). The 31P{1H}
NMR data for these two complexes are shown in Table 2. The other
Scheme 1. Reaction of 2,6-(CF3)2-C6H3-P(OCH2)2 (1) with trans-[PtX(l
-X)(PR2R0)]2.

608
K.B. Dillon et al. / Polyhedron 29 (2010) 606–612
Table 2
31P NMR data for complexes (2)–(12) (PB corresponds to (L)).
Complex
dPA, ppm
dPB, ppm
1JPt–PA, Hz
1JPt–PB, Hz
2JPA–PB, Hz
trans-[PtCl2(L)(PEt3)] (2)
cis-[PtCl2(L)(PEt3)] (3)
14.6
18.8
ꢀ6.9
ꢀ9.4
4.7
144.2
115.5
142.5
113.0
140.4
111.7
141.0
112.4
114.1
–
2521
3102
2547
3192
2594
3280
2441
3051
–
3581
5670
3681
5573
3766
5538
3468
5591
5180
–
651
21
691
23
687
21
647
17
–
trans-[PtCl2(L)(PPhMe2)] (4)
cis-[PtCl2(L)(PPhMe2)] (5)
trans-[PtCl2(L)(PPh2Me)] (6)
cis-[PtCl2(L)(PPh2Me)] (7)
trans-[PtBr2(L)(PEt3)] (8)
cis-[PtBr2(L)(PEt3)] (9)
cis-[PtCl2L2] (10)
cis-[PtCl2(PPhMe2)2] (11)
cis-[PtCl2L(PPh2Me)2] (12)
1.1
10.1
18.4
–
ꢀ21.8
3700
3600
–
–
0.1
–
–
two complexes were assigned to the ligand scrambling products,
mer, cis-[PtBr2(L)(PEt3)] (9), upon standing. Crystals suitable for
X-ray diffraction studies were obtained of 9, with the resulting
molecular structure being shown in Fig. 6; selected bond distances
and angles are listed in Table 3.
1
cis-[PtCl2L2] (10) (s, 114.0 ppm, JPt–P = 5180 Hz) and cis-
1
[PtCl2(PPh2Me)2] (12) (s, 0.1 ppm, JPt–P = 3600 Hz), the data for
the latter being in good agreement with those in the literature
[26]. Crystals of 7 suitable for single-crystal X-ray diffraction stud-
ies were isolated; the resulting molecular structure is shown in
Fig. 5, with selected bond lengths and angles in Table 3.
For the cis-[PtX2(L)(PR2R0)] complexes 3, 7 and 9, the geometry
around the Pt centre is approximately square planar, with the an-
gles around Pt varying from 85.66(3)° to 95.33(3)°, 85.91(2)° to
95.21(2)° and 86.07(3)° to 95.08(4)°, respectively, the larger
P(1)–Pt(1)–P(2) angle to accommodate the bulk of the phosphane
groups. The Pt(1)–P(2) bond lengths in 3 and 9 (2.264(1) Å and
2.276(1) Å, respectively) are similar in magnitude to those ob-
served for other [PtCl2(P1)(P2)] complexes where (P2) = PEt3 (e.g.
2.264(2) and 2.261(2) Å in cis-[PtCl2(PEt3)2] [27], 2.315(4) in
trans-[PtBr2(PEt3)2] [28], 2.298(18) in trans-[PtCl2(PEt3)2] [28], or
2.305(6) Å in cis-[PtCl2(PCy3)(PEt3)]) [29]. Similarly, the Pt(1)–
P(2) bond length in (7) (2.262(1) Å) is comparable to those ob-
Reaction of 1 with trans-[PtBr(l-Br)(PEt3)]2 was carried out in
order to synthesise a bromo analogue of 3 and 4. Initially the trans
complex, trans-[PtBr2(L)(PEt3)] (8) formed. However, as in previous
reactions of 1 with other Pt(II) dimers, this converted to the cis iso-
Fig. 2. The molecular structure of cis-[PtCl2(L)(PEt3)] (3), showing the numbering
scheme for the key atoms. Thermal ellipsoids are drawn at 50% probability.
Fig. 3. Ligand scrambling products.
Table 3
Selected bond distances (Å) and bond angles (°) for (3), (7) and (9).
cis-[PtCl2(L)(PEt3)] (3) (X@Cl)
Bond distances (Å)
cis-[PtCl2(L)(PPh2Me)] (7) (X@Cl)
cis-[PtBr2(L)(PEt3)] (9) (X@Br)
Pt(1)–P(1)
Pt(1)–P(2)
Pt(1)–X(1)
Pt(1)–X(2)
P(1)–C(1)
P(1)–O(1)
P(1)–O(2)
2.183(1)
2.264(1)
2.356(1)
2.353 (1)
1.851(4)
1.603(2)
1.598(3)
2.189(1)
2.262(1)
2.337(1)
2.361 (1)
1.856(2)
1.601(2)
1.600 (2)
2.192(1)
2.276(1)
2.487(1)
2.483 (1)
1.845(5)
1.603(3)
1.603(3)
Bond angles (°)
P(1)–Pt(1)–P(2)
P(1)–Pt(1)–X(2)
P(2)–Pt(1)–X(1)
X(1)–Pt(1)–X(2)
O(1)–P(1)–O(2)
O(1)–P(1)–C(1)
O(2)–P(1)–C(1)
95.33(3)
90.12(3)
85.66(3)
88.82(3)
96.81(13)
100.79(15)
102.91(15)
95.21(2)
91.46(2)
85.91(2)
87.27(2)
96.87(8)
101.75(9)
103.88(9)
95.08(4)
90.32(3)
86.07(3)
88.54(2)
96.82(17)
100.5(2)
102.91(19)

K.B. Dillon et al. / Polyhedron 29 (2010) 606–612
609
Fig. 4. The molecular structure of cis-[PtCl2L2] (10), showing the numbering scheme for the key atoms. Thermal ellipsoids are drawn at 50% probability.
Table 4
Selected bond distances (Å) and bond angles (°) for cis-[PtCl2L2] (10).
Bond distances (Å)
Pt(1)–P(1)
Pt(1)–P(2)
Pt(1)–Cl(1)
Pt(1)–Cl(2)
P(1)–C(1)
P(1)–O(1)
P(1)–O(2)
P(2)–C(11)
P(2)–O(3)
P(2)–O(4)
2.206(4)
2.204(4)
2.337(4)
2.349(4)
1.823(13)
1.587(9)
1.591(11)
1.874(14)
1.577(10)
1.584(10)
Bond angles (°)
P(1)–Pt(1)–P(2)
P(2)–Pt(1)–Cl(1)
P(1)–Pt(1)–Cl(2)
Cl(1)–Pt(1)–Cl(2)
O(1)–P(1)–O(2)
O(3)–P(2)–O(4)
O(1)–P(1)–C(1)
O(2)–P(1)–C(1)
O(3)–P(2)–C(11)
O(4)–P(2)–C(11)
91.77(14)
90.59(12)
90.87(13)
87.15(13)
97.6(5)
Fig. 6. The molecular structure of cis-[PtBr2(L)(PEt3)] (9), showing the numbering
scheme for the key atoms. Thermal ellipsoids are drawn at 50% probability.
97.4(5)
104.2(6)
103.8(6)
103.2(6)
103.2(6)
served for other [PtClX(PPh2Me)2] complexes that range between
2.239(2) and 2.3589(9) Å [30–34]. However, the Pt(1)–P(1) bond
length for each complex is much shorter (2.183(1) Å (3), 2.189(1)
1
(7) and 2.192(1) (9)), which is consistent with the larger JPt–P(1)
coupling constant observed for these three complexes (Table 2)
[35–37]. This stronger bond probably arises from the more electro-
negative nature of the 2-aryl-1,3,2-dioxaphospholane ligand.
The complex cis-[PtCl2L2] (10), crystallises in the orthorhombic
space group P212121. The geometry around the Pt centre is approx-
imately square planar, with the angles around Pt varying from
87.15(13)° to 91.77(14)°, the larger angle being the P(1)–Pt(1)–
P(2) angle to accommodate the bulk of the phosphane groups.
The Pt–P distances (2.206(4) and 2.204(4) Å) are slightly longer
than those observed in complexes (3), (7) and (9) (2.183(1),
2.189(1) and 2.192(1) Å, respectively), and the P(1)–Pt(1)–P(2) an-
gle is smaller at 91.77(13)°.
In 1 the O(1)–C(6)–C(6A)–O(1A) torsion angle is 0° as a conse-
quence of the symmetry imposed by the mirror plane, which bi-
sects the two carbon atoms in the 5-membered ring. There are
no intermolecular short contacts present between the components
of the 5-membered ring and any other part of the molecule,
although there are intramolecular interactions between C6–
H6Aꢁ ꢁ ꢁF20, and C6–H6Bꢁ ꢁ ꢁC20 of adjacent molecules. The angle be-
tween the planes defined by O–P–O and that of the O–C–C–O of
the 5-membered ring (‘envelope’ angle) in 1 is 26°.
Fig. 5. The molecular structure of cis-[PtCl2(L)(PPh2Me)] (7), showing the number-
ing scheme for the key atoms. Thermal ellipsoids are drawn at 50% probability.

610
K.B. Dillon et al. / Polyhedron 29 (2010) 606–612
There are also no intermolecular interactions between the 5-
range from 1.565(7) to 1.622(6) Å [1,8,9,39–42]. This is in good
agreement with those found in complexes 3, 7, 9 and 10 (Tables
3 and 4). However, a search of the Cambridge Structural Database
revealed no pairs of a structurally characterised dioxyphospholane,
and its platinum complexes, therefore no comparison can be made
of the changes to bond distances and angles of the ligands upon
complexation [43].
membered ring and any other part of the molecule in complexes
3, 7, 9 and 10. Complexes 3 and 9 are isostructural, with similar
intermolecular interactions involving the dioxaphospholane moi-
ety. One of the two ligands in 10 also shares a similar network of
intermolecular short contacts; the envelope angles in these com-
plexes are comparable to that observed in 1 – approximately 27°
in all three complexes.
In complex 7 and the second dioxaphospholane ligand in 10, the
intramolecular interactions differ, resulting in a significant change
in the ‘envelope’ angle, to approximately 20°. In addition to the
change in this angle, there are considerable differences in the O–
C–C–O torsion angle in these instances where the non-bonding
interactions differ. These observations suggest that the geometry
of the 5-membered ring is largely a result of intramolecular
interactions.
Complexation of 1 results in a decrease in the P–O bond lengths
in each case, and a widening of the O–P–O and O–P–C bond angles
(Tables 1, 3 and 4). This is entirely in keeping with complexation
via the lone pair on P to Pt, reducing the repulsion from the lone
pair to the bonding pairs around the phosphorus centre. The P–C
distance is also slightly reduced in 3, 7 and 10, although it is
slightly larger in the trans complex 9, possibly arising from greater
steric interactions. The Pt–P distances are also slightly larger in 9
than in 3 or 7. It is also of interest to note that the non-bonding
O–O distances in 1, and the four complexes 3, 7, 9 and 10 are very
similar (2.380(10)–2.398(4) Å). This parallels the findings by
Gillespie in, for example, BFn and CFn groups, where the Fꢁ ꢁ ꢁF inter-
ligand distances are remarkably constant, despite variation in both
bond distance and bond angle [38]. This again shows the impor-
tance of non-bonding interactions in influencing the structures of
compounds.
3. Conclusions
Using single-crystal X-ray diffraction studies, the molecular
structure of 2,6-(CF3)2-C6H3-P(OCH2)2 (1) has been ascertained at
120 K. The coordination behaviour of this phosphane towards
some Pt(II) dimers has been investigated, resulting in the synthesis
of the first transition metal complexes of 2,6-(CF3)2-C6H3-
P(OCH2)2, which have been characterised using 31P{1H} NMR spec-
troscopy and single-crystal X-ray diffraction.
For each reaction of 1 with the platinum(II) dimers trans-
[PtCl(l-Cl)(PEt3)]2, [PtCl(
l
-Cl)(PPh2Me)]2, [PtCl(
l
-Cl)(PPhMe2)]2
and
[PtBr( -Br)(PEt3)]2,
l
monomeric Pt(II)
complexes
([PtX2(L)(PR2R0)]) were formed. The trans isomer formed initially
as the kinetic product of the reaction, but over time this converted
to the more thermodynamically stable cis isomer. For each reac-
tion, the chemical shift of the chlorophosphane ligand of the trans
complex was always to higher frequency than for the cis. For the cis
1
complexes, large values of JPt–P were observed (3051–5670 Hz)
along with small values of JP–P (17–23 Hz) compared with the
2
2
trans complexes, where the JP–P values are much larger (647–
1
691 Hz) and JPt–P values are much smaller (2441–3766 Hz). This
is comparable with the data reported by Pidcock et al. [20] and
Grim et al. [21] for other Pt(II) complexes.
Several similar Pt(II) complexes containing organophosphonite
ligands and two chlorides have been previously structurally char-
acterised [1,8,9,39–42]. The P–O bond lengths in these complexes
For reactions of 1 with trans-[PtCl(
trans-[PtCl( -Cl)(PPh2Me)]2, ligand scrambling products were ob-
served as a minor component of the crude reaction mixtures. In
l-Cl)(PPhMe2)]2 and with
l
Table 5
Experimental data from crystallographic studies of compounds (1), (3), (7), (9) and (10).
Identification code
(1)
(3)
(7)
(9)
(10)
Complex
L
cis-[PtCl2(L)(PEt3)]
C16H22Cl2F6O2P2Pt
688.27
120(2)
monoclinic
Pn
8.6707(6)
12.5959(9)
10.0326(7)
90.814(1)
1095.60(13)
2
cis-[PtCl2(L)(PPh2Me)]
C23H20Cl2F6O2P2Pt
770.32
120(2)
monoclinic
P21/c
14.1043(7)
12.8346(7)
15.1574(8)
110.943(1)
2562.6(2)
cis-[PtBr2(L)(PEt3)]
C16H22Br2F6O2P2Pt
777.19
120(2)
monoclinic
Pn
8.9108(4)
12.5588(5)
10.1267(4)
90.587(1)
1133.21(8)
2
cis-[PtCl2L2]
C21H15Cl5F12O4P2Pt
993.61
120(2)
orthorhombic
P212121
13.1502(16)
13.9552(17)
16.580(2)
Empirical formula
Formula weight
Temperature
Crystal system
Space group
a (Å)
C10H7F6O2P
304.12
120(2)
orthorhombic
Pnma
9.1335(6)
9.8055(6)
12.9490(8)
b (Å)
c (Å)
b (°)
V (Å3)
1159.69(13)
4
1.742
3042.7(6)
4
2.169
Z
4
Dcalc (mg/mm3)
2.086
6.854
1.997
5.873
2.278
9.917
m/mmꢀ1
0.312
5.260
F(0 0 0)
608
660
1480
732
1896
Crystal size (mm)
h Range for data collection
Index ranges
0.19 ꢂ 0.17 ꢂ 0.16
2.61–28.35°
ꢀ12 6 h 6 12
ꢀ13 6 k 6 11
ꢀ15 6 l 6 17
10638
0.19 ꢂ 0.16 ꢂ 0.11
1.62–28.33°
ꢀ11 6 h 6 11
ꢀ16 6 k 6 16
ꢀ13 6 l 6 13
16293
0.25 ꢂ 0.21 ꢂ 0.2
1.55–26.37°
ꢀ17 6 h 6 17
ꢀ16 6 k 6 16
ꢀ18 6 l 6 18
31919
0.21 ꢂ 0.17 ꢂ 0.11
1.62–25.02°
ꢀ10 6 h 6 10
ꢀ13 6 k 6 14
ꢀ7 6 l 6 12
6309
0.17 ꢂ 0.14 ꢂ 0.13
1.91–25.02°
ꢀ14 6 h 6 15
ꢀ16 6 k 6 15
ꢀ19 6 l 6 19
16480
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness-of-fit (GOF) on F2
1519 [Rint = 0.0268]
1519/0/106
1.068
5351 [Rint = 0.0317]
5351/2/265
0.823
5234 [Rint = 0.0217]
5234/0/326
1.045
3327 [Rint = 0.0221]
3327/2/265
0.935
5375 [Rint = 0.0970]
5375/0/232
1.014
Final R indexes [I > 2
r
(I)]
R1 = 0.0296
wR2 = 0.0761
R1 = 0.0343
wR2 = 0.0790
0.397/ꢀ0.281
R1 = 0.0184
wR2 = 0.0394
R1 = 0.0200
wR2 = 0.0400
0.914/ꢀ0.419
0.021(4)
R1 = 0.0147
wR2 = 0.0360
R1 = 0.0166
wR2 = 0.0372
1.173/ꢀ0.636
R1 = 0.0180
wR2 = 0.0382
R1 = 0.0185
wR2 = 0.0384
0.907/ꢀ0.588
0.019(5)
R1 = 0.0551
wR2 = 0.1150
R1 = 0.0962
wR2 = 0.1322
2.610/ꢀ2.683
0.030(13)
Final R indexes [all data]
Largest differential in peak/hole
Flack parameter

K.B. Dillon et al. / Polyhedron 29 (2010) 606–612
611
both reactions cis-[PtCl2L2], where L = 2,6-(CF3)2-C6H3-P(OCH2)2,
(10) was observed, along with the corresponding cis-[PtCl2(PR2R’)2]
complex (R@Me, R0@Ph (11) and R@Ph, R0@Me (12)). Crystals of the
bis-(2,6-(CF3)2-C6H3-P(OCH2)2) ligand scrambling product 10 were
causing the formation of a yellow precipitate. The solution was fil-
tered to isolate the yellow solid. Yield = 4.93 g (77%) (C16H22Cl4P2Pt2
requires C, 23.78; H, 2.74; N, 0.00. Found: C, 23.76; H, 2.75; N, 0.00%).
1
31P (121.40 MHz, CDCl3): d ꢀ17.0 ppm (s, JPt–P = 3928 Hz) (litera-
1
isolated after heating the reaction of
1
with trans-[PtCl(
l
-
ture data: d ꢀ18.5 ppm (s, JPt–P = 3930 Hz) [44], d ꢀ18.7 ppm (s,
Cl)(PPhMe2)]2, and its structure was confirmed by single-crystal
X-ray diffraction at 120 K.
1JPt–P = 3934 Hz) [45]).
Further studies on the reactivity and applications of these inter-
esting systems are currently in progress.
4.4. Synthesis of trans-[PtBr(l-Br)(PEt3)]2
PtBr2 (3.2860 g, 9.26 mmol) and PEt3 (1.33 mL, 9.01 mmol)
were added to p-chlorotoluene (20 mL) and the mixture was
heated at reflux for 150 min. The solvent was then removed in va-
cuo to afford a dark brown solid. CH2Cl2 (20 mL) was then added
and the solution was filtered through Celite. The solid was washed
with further quantities of CH2Cl2 until the filtrate ran clear. Upon
standing overnight bright orange crystals formed which were
recrystallised from DCM. Yield = 6.40 g (73%). (C12H30Br4P2Pt2 re-
quires C, 15.23; H, 3.20; N, 0.00. Found: C, 15.10; H, 3.07; N,
0.00%). 31P (161.9 MHz, CDCl3): d 11.0 ppm (s, 1JPt–P = 3696 Hz) (lit-
4. Experimental
All manipulations, including NMR sample preparation, were
carried out either under an inert atmosphere of dry nitrogen or
in vacuo, using standard Schlenk line or glovebox techniques.
Chemicals of the best available commercial grade were used, in
general without further purification. The 31P NMR spectra of all
phosphorus-containing starting materials were recorded, to verify
that no major impurities were present. 31P NMR spectra were
obtained on Varian Unity 300, Mercury 400 or Inova 500 Fourier-
transform spectrometers at 121.40, 161.91 or 202.3 MHz, respec-
tively; chemical shifts are referenced to 85% H3PO4, with the high
frequency direction taken as positive. Microanalyses were per-
formed by the microanalytical services of the Department of
Chemistry, Durham University.
1
erature data: d 10.9 ppm (s, JPt–P = 3701 Hz) [46]).
4.5. Synthesis of 2,6-(CF3)2-C6H3-P(OCH2)2
A solution of ethylene chlorophosphite (6.3 g, 50 mmol) in
diethylether (50 mL) was prepared [10]. TMEDA (5.69 g, 49 mmol)
and a solution of n-butyllithium (1.6 M in hexanes, 29.2 mL) were
added to a solution of 1,3-bis-(trifluoromethyl)benzene (10.0 g,
46.7 mmol) in hexane (30 mL) at 0 °C. The solution was stirred
overnight at room temperature. The solution was then added drop-
wise to the ethylene chlorophosphite solution. The resulting solu-
tion was filtered to remove lithium salts and the solvents were
removed in vacuo. Upon standing colourless crystals were ob-
tained. Yield 8.2 g (54%) (C10H7F6O2P requires C, 39.49; H, 2.32;
4.1. Synthesis of trans-[PtCl(l-Cl)(PEt3)]2
PtCl2 (4.53 g, 17.1 mmol) and PEt3 (2.4 mL, 16.0 mmol) were
added to p-chlorotoluene (15 mL) and the mixture was heated at
reflux for 120 min [44]. The solvent was then removed in vacuo
to afford a dark brown solid. CH2Cl2 (20 mL) was then added and
the solution was filtered through Celite. The solid was washed with
further quantities of DCM until the filtrate ran clear. Upon standing
overnight, bright orange crystals formed. These were recrystallised
from CH2Cl2. Yield = 10.56 g (80%) (C12H30Cl4P2Pt2 requires C,
18.76; H, 3.94; N, 0.00. Found: C, 18.89; H, 3.95; N, 0.00%). 31P
N, 0.00. Found: C, 39.09; H, 2.61; N, 0.00%). 31P{1H} (CDCl3,
4
161.9 MHz):
d
158.2 ppm (septet, JP–F = 35 Hz); 19F (CDCl3,
376 MHz): ꢀ55.5 ppm (d, JF–P = 35 Hz). (literature data: 31P (sep-
4
tet, 158.2 ppm, JP–F = 35 Hz);19
[10]).
F
(d, ꢀ55.5 ppm, JF–P = 35 Hz)
4
4
1
(121.40 MHz, CDCl3): d 11.5 ppm (s, JPt–P = 3839 Hz) (literature
data: d 9.78 ppm (s, JPt–P = 3845 Hz) [44]).
1
4.6. Synthesis of trans- and cis-[PtCl2(L)(PEt3)], where L = 2,6-(CF3)2-
C6H3-P(OCH2)2
4.2. Synthesis of trans-[PtCl(l-Cl)(PPh2Me)]2
A solution was prepared containing trans-[PtCl(l-Cl)(PEt3)]2
PtCl2 (2.11 g, 7.96 mmol) and PPh2Me (1.4 mL, 7.41 mmol) were
added to p-chlorotoluene (10 mL) and the mixture was then heated
to reflux for 90 min. The solvent was removed in vacuo to afford a
dark brown solid. CH2Cl2 (20 mL) was then added and the solution
was filtered through Celite. The solid was washed with further
quantities of CH2Cl2 until the filtrate ran clear. The yellow filtrate
was then concentrated to approximately 10 mL and pentane
(40 mL) added, which resulted in the formation of a yellow precip-
itate. The solution was removed by filtration to leave the yellow so-
lid. Yield = 6.12 g (82%) (C26H26Cl4P2Pt2 requires C, 33.49; H, 2.81;
(0.0253 g, 0.033 mmol) in CDCl3 (1 mL). This solution was added
to 2,6-(CF3)2-C6H3-P(OCH2)2 (0.0202 g, 0.066 mmol). A 31P NMR
spectrum was recorded soon after this addition. Slow evaporation
of the solvent afforded crystalline material suitable for X-ray anal-
ysis. (C16H22Cl2F6O2P2Pt requires C, 27.92; H, 3.22; N, 0.00. Found:
C, 27.54; H, 3.39; N, 0.00%).
4.7. Synthesis of trans- and cis-[PtCl2(L)(PPhMe2)], where L = 2,6-
(CF3)2-C6H3-P(OCH2)2
N, 0.00. Found: C, 33.19; H, 2.87; N, 0.00%). 31P (121.40 MHz,
1
CDCl3):
d
ꢀ6.4 ppm (s, JPt–P = 4003 Hz) (literature data:
d
A solution was prepared containing trans-[PtCl(l-Cl)(PPhMe2)]2
ꢀ4.2 ppm (s, 1JPt–P = 3911 Hz) [45]).
(0.0323 g, 0.04 mmol) in CDCl3 (1 mL). This solution was added to
2,6-(CF3)2-C6H3-P(OCH2)2 (0.0240 g, 0.08 mmol). A 31P NMR spec-
trum was recorded soon after this addition.
4.3. Synthesis of trans-[PtCl(l-Cl)(PPhMe2)]2
PtCl2 (2.1 g, 7.96 mmol) and PPhMe2 (1.4 mL, 7.41 mmol) were
added to p-chlorotoluene (10 mL) and the mixture was heated at re-
flux for 90 min [44]. The solvent was removed in vacuo to afford a
dark brown solid. CH2Cl2 (30 mL) was then added and the solution
was filtered through Celite. The solid was washed with further quan-
tities of CH2Cl2 until the filtrate ran clear. The filtrate was concen-
trated to approximately 10 mL and pentane (40 mL) added,
4.8. Synthesis of trans- and cis-[PtCl2(L)(PPh2Me)], where L = 2,6-
(CF3)2-C6H3-P(OCH2)2
A solution was prepared containing trans-[PtCl(l-Cl)(PPh2Me)]2
(0.0606 g, 0.075 mmol) in CDCl3 (1 mL). This solution was then
added to 2,6-(CF3)2-C6H3-P(OCH2)2 (0.0454 g, 0.15 mmol). A 31P
NMR spectrum was recorded soon after this addition. Slow evapo-

612
K.B. Dillon et al. / Polyhedron 29 (2010) 606–612
ration of the solvent afforded crystalline material suitable for X-ray
analysis.
and A.M. Kenwright, C.F. Heffernan and I. McKeag for their assis-
tance in recording some of the NMR spectra.
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Acknowledgements
[48] SMART
Instruments Inc., Madison, WI, USA, 2000.
[49] SAINT Data Reduction Software, version 6.1, Bruker Analytical X-ray
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We would like to thank the EPSRC for a research studentship (to
HJS), the Maria da Graça Memorial Research Fund/Chemistry
Department, Durham University, for financial support (to PKM),
Johnson Matthey plc. for their generous loan of platinum salts,
Instruments Inc., Madison, WI, USA, 2000.
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