Synthesis spectroscopic and structural properties of transition metal complexes of the o-xylyl diphosphine o-C6H4(CH 2PPh2)2

Article abstract of DOI:10.1016/j.poly.2004.10.008

The systematic coordination chemistry of the wide-angle diphosphine o-C₆H₄(CH₂PPh₂)₂ (L ¹) has been investigated with metal ions from Groups 9-11 in order to explore the consequences of the steric demands of the phosphine and its flexibility towards different oxidation states and coordination geometries. The products isolated include the tetrahedral [CoX₂(L¹)] (X = Cl, Br or I), the very distorted square planar [Rh(L¹) ₂]⁺, [M(cod)(L¹)]⁺ (M = Rh or Ir), square planar [NiX₂(L¹)] (X = Cl or Br), [M′Cl ₂(L¹)] (M′ = Pd or Pt), the chloro-bridged [Pd ₂Cl₂(L¹)₂]²⁺, [Pd(L ¹)₂]²⁺, the tetrahedral [M″(L ¹)₂]⁺ (M″ = Cu, Ag or Au) and the dinuclear [(AuCl)₂(L¹)]. Chemical oxidation of some of the complexes are described, giving examples of Co(III), Ni(III) and Pt(IV) species. Where possible the products have been characterised by IR, UV-vis, NMR (¹H, ³¹P, ⁶³Cu and ¹⁹⁵Pt as appropriate) spectroscopies, mass spectrometry and microanalysis. Crystal structures of six representative examples confirm the coordination environments in particular species and illustrate the steric demands of L¹. L ¹ is a versatile ligand which can readily alter its chelate bite angle to accommodate a range of coordination geometries (the P?P distances within the chelate rings varies by >0.5 ?), and the presence of the rigid aromatic ring in the C₄ backbone leads to some preorganisation favouring cis chelation. It also shows a preference for low coordination numbers and this results in some unexpected products.

Full text of DOI:10.1016/j.poly.2004.10.008

Polyhedron 24 (2005) 75–87
www.elsevier.com/locate/poly
Synthesis spectroscopic and structural properties of transition
metal complexes of the o-xylyl diphosphine o-C6H4(CH2PPh2)2
*
Michael D. Brown, William Levason, Gillian Reid , Rebecca Watts
School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK
Received 20 September 2004; accepted 11 October 2004
Available online 8 December 2004
Abstract
The systematic coordination chemistry of the wide-angle diphosphine o-C6H4(CH2PPh2)2 (L1) has been investigated with metal
ions from Groups 9–11 in order to explore the consequences of the steric demands of the phosphine and its flexibility towards dif-
ferent oxidation states and coordination geometries. The products isolated include the tetrahedral [CoX2(L1)] (X = Cl, Br or I), the
very distorted square planar [Rh(L1)2]+, [M(cod)(L1)]+ (M = Rh or Ir), square planar [NiX2(L1)] (X = Cl or Br), [M0Cl2(L1)]
(M0 = Pd or Pt), the chloro-bridged [Pd2Cl2(L1)2]2+, [Pd(L1)2]2+, the tetrahedral [M00(L1)2]+ (M00 = Cu, Ag or Au) and the dinuclear
[(AuCl)2(L1)]. Chemical oxidation of some of the complexes are described, giving examples of Co(III), Ni(III) and Pt(IV) species.
Where possible the products have been characterised by IR, UV–vis, NMR (1H, 31P, 63Cu and 195Pt as appropriate) spectroscopies,
mass spectrometry and microanalysis. Crystal structures of six representative examples confirm the coordination environments in
particular species and illustrate the steric demands of L1. L1 is a versatile ligand which can readily alter its chelate bite angle to
˚
accommodate a range of coordination geometries (the Pꢀ ꢀ ꢀP distances within the chelate rings varies by >0.5 A), and the presence
of the rigid aromatic ring in the C4 backbone leads to some preorganisation favouring cis chelation. It also shows a preference for
low coordination numbers and this results in some unexpected products.
ꢀ 2004 Elsevier Ltd. All rights reserved.
Keywords: Diphosphine; Metal complexes; X-ray structures
1. Introduction
phine o-C6H4(CH2PPh2)2 have been shown to be
active catalysts for several different transformations,
e.g., platinum-tin catalysed hydroformylation [3], rho-
dium-catalysed hydrogenation of CO2 [4] and iridium-
catalysed hydrogenation of aldehydes [5]. Given the
level of interest in these systems, it is surprising that
the systematic coordination chemistry of L1 with transi-
tion metal ions has been rather neglected. Initial studies
on the complexation of L1 with medium and low valent
late transition metal centres were conducted by Venanzi
and co-workers [6,7] who reported the preparations of
some mononuclear derivatives and dinuclear halide-
and hydride-bridged complexes. Example, include the
structurally characterised [Ag2X2(L1)2] (X = Cl or I)
which involve distorted tetrahedral coordination at
Ag(I) via two halides and a chelating L1, and the Pt(0)
complex, [Pt(H2 C@CH2)(L1)] [8]. Werner et al. [9–11]
The reaction chemistry of sterically demanding wide-
angle diphosphines is attracting great interest at present
owing to the remarkably high catalytic activities exhib-
ited by some transition metal complexes involving these
ligands. Major reactions of interest are Rh-catalysed
hydroformylation of alkenes, Ni-catalysed hydrocyana-
tion and Pd-catalysed copolymerisation of CO and alk-
enes. In particular, the P–M–P bite angle plays an
important role in determining the selectivity and rates
in these catalytic reactions [1,2]. In previous studies plat-
inum metal complexes incorporating the xylyl diphos-
*
Corresponding author. Tel.: +44 2380593609; fax: +44
2380593781.
E-mail address: gr@soton.ac.uk (G. Reid).
0277-5387/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2004.10.008

76
M.D. Brown et al. / Polyhedron 24 (2005) 75–87
have reported a number of other platinum metal com-
plexes of L1 with various organic co-ligands, while sulf-
ido- and selenido-Ru and Fe carbonyl clusters, which
result from chalcogen transfer from the phosphine sul-
fide or selenide derivatives of L1 to the metal centre,
have also been reported [12,13].
In this paper we describe a systematic study of the
coordination of L1 with metal ions from Groups 9–11,
including their syntheses and spectroscopic properties.
The transition metal ions studied adopt square planar,
tetrahedral, linear and octahedral coordination geome-
tries and thus allow the ligating properties of the o-xylyl
diphosphine to be probed. Comparisons are drawn with
the ligating properties of the related flexible C4-diphos-
phine, Ph2P(CH2)4PPh2 (dppb), and the more rigid o-
phenylene derivative o-C6H4(PPh2)2.
2. Results and discussion
Fig. 1. View of the structure of [CoCl2(L1)] with numbering scheme
adopted. H atoms are omitted for clarity. Ellipsoids are shown at the
50% probability level.
The diphosphine L1 was prepared in high yield as
a white solid by a slight modification of the litera-
ture method [8] involving reaction of Ph2PLi with
o-C6H4(CH2Br)2 in thf solution. In solution L1 is quite
air-sensitive, hence all measurements and subsequent
reactions used deoxygenated solutions and Schlenk
techniques.
Table 1
1
˚
Selected bond lengths (A) and angles (ꢁ) for [CoCl2(L )]
Bond lengths
Co1–Cl2
Co1–Cl1
Co1–P2
Co1–P1
P1–C7
2.2045(15)
2.2165(15)
2.3795(16)
2.4034(16)
1.810(5)
2.1. Co, Rh and Ir complexes
P1–C1
1.811(5)
1.851(5)
Treatment of an isopropanol solution of CoX2
(X = Cl, Br or I) with one mol equiv. of L1 under N2
affords the distorted tetrahedral [CoX2(L1)] as brightly
coloured blue, green or brown-green solids, respectively,
in good yield. The formulation follows from the micro-
analytical data, 1 while magnetic measurements are con-
sistent with high spin Co(II) species. The UV–vis spectra
show absorptions consistent with tetrahedral Co(II)
[14,15], and the spectra are the same in the solid state
and in CH2Cl2 solution. The far IR spectrum of
[CoCl2(L1)] shows a broad peak at 318 cmꢁ1, consistent
with m(Co–Cl). The distorted tetrahedral coordination
with one chelating L1 is confirmed in the solid state by
a structure determination on a very small crystal of
[CoCl2(L1)] (Fig. 1, Table 1). The Co–P bond distances
P1–C25
P2–C19
P2–C13
P2–C32
1.815(5)
1.817(5)
1.840(5)
Bond angles
Cl2–Co1–Cl1
Cl2–Co1–P2
Cl1–Co1–P2
Cl2–Co1–P1
Cl1–Co1–P1
P2–Co1–P1
C7–P1–C1
109.50(6)
111.52(6)
103.26(5)
114.64(6)
111.13(6)
106.18(5)
106.1(2)
C7–P1–C25
C1–P1–C25
C7–P1–Co1
C1–P1–Co1
C25–P1–Co1
C19–P2–C13
C19–P2–C32
C13–P2–C32
C19–P2–Co1
C13–P2–Co1
C32–P2–Co1
103.1(2)
102.0(2)
115.43(17)
115.45(16)
113.18(17)
104.7(2)
˚
are 2.3795(16) and 2.4034(16) A, while d(Co–
˚
Cl) = 2.2045(15) and 2.2165(15) A.
105.1(2)
103.7(2)
107.68(16)
119.13(16)
115.25(17)
1
We note that microanalytical data for several of the complexes are
consistent with there being some CH2Cl2 solvent associated with the
compounds even after drying in vacuo. For the diamagnetic com-
plexes, there is evidence for CH2Cl2 in the 1H NMR spectra, and
indeed four of the crystal structures show two molecules of CH2Cl2 (or
CHCl3) solvent per metal ion. Thus, we conclude that the steric bulk of
the coordinated L1 probably leaves considerable voids in the lattice
which can accommodate solvent molecules.
The related, but more rigid o-phenylene diphosphine,
o-C6H4(PPh2)2, gives planar cations [Co{o-C6H4-
(PPh2)2}2][CoX4] and 5-coordinate [Co{o-C6H4-
(PPh2)2}2X]+ on reaction with Co(II) halides, reflecting

M.D. Brown et al. / Polyhedron 24 (2005) 75–87
77
both the stronger ligand field imposed and the 5-mem-
bered chelate rings present [15], whereas larger chelate
rings give tetrahedral Co(II) (as in [CoX2(L1)] above)
[16]. We note that an early assignment [16] of the prod-
uct from reaction of CoCl2 with dppe (Ph2PCH2-
CH2PPh2) as [CoCl2(dppe)] was in error and the
compound was subsequently shown to be the phosphine
oxide complex [17].
Low temperature oxidation of a CH2Cl2 solution of
[CoCl2(L1)] with NOCl gives the Co(III) species
[CoCl3(L1)] as a deep blue-green solid. The electronic
spectrum of this product is characteristic of the rare 5-
coordinate geometry and the Cl3P2 donor set [18]. The
far IR spectrum shows the three Co–Cl bands expected.
The Co(III) compound decomposes slowly in CH2Cl2
solution at room temperature.
for a planar Rh(I) derivative with more s-orbital charac-
ter in the Rh(I)–P bond (sp2d hybridisation). This result
prompted us to seek X-ray structural data to authenti-
cate our assignment of the product as [Rh(L1)2]BF4.
Orange single crystals were obtained by layering a
CHCl3 solution of the complex with hexane. The struc-
ture shows (Fig. 2, Table 2) two chelating L1 units
bound to the Rh centre in a distorted square planar
arrangement, with no evidence for other co-ligands.
One BF4 anion and two CHCl3 solvent molecules also
occupy general positions in the asymmetric unit, consis-
tent with a Rh(I) complex. The Rh–P bond distances are
˚
in the range 2.31–2.34 A. These are in accord with d(Rh–
P) in other Rh(I) phosphine complexes, e.g., [RhCl-
ꢁ
˚
(PPh3)3] d(Rh–PtransP) = 2.304–2.338 A [19,20]. The
sum of the P–Rh–P angles is 370ꢁ, indicating a signifi-
cant tetrahedral distortion, which probably results from
the significant steric requirements of the two bulky L1 li-
gands. The P1ꢀ ꢀ ꢀP2 and P3ꢀ ꢀ ꢀP4 distances within the
In an attempt to explore the coordination chemistry
of rhodium with L1 we reacted RhCl3 Æ3H2O with two
molar equivalents of L1 in EtOH solution in the pres-
ence of a few drops of 40% aqueous HBF4. Stirring at
room temperature for approximately 30 min gave an or-
ange solution and concentration of this solution in
vacuo afforded an orange solid. The IR spectrum shows
˚
chelates are 3.28 and 3.37 A, and the P1–Rh–P2 and
˚
P3–Rh–P4 angles are 90.05(3) and 92.31(3) A,
respectively.
The formation of the bis-diphosphine Rh(I) cation un-
der these reaction conditions is unexpected as this is the
method used to obtain the Rh(III) species [RhCl2-
(L-L)2]+ (L-L = Ph2PCH2CH2PPh2, o-C6H4-(PPh2)2)
[21,22]. The different reaction course may also be a con-
sequence of the steric bulk imposed by the wide angle
diphosphine L1, which disfavours formation of the
6-coordinate Rh(III) dichloro derivative. The prepara-
tion of the very well known Wilkinsonꢀs compound,
[RhCl(PPh3)3], is however readily achieved by reaction
of RhCl3 Æ3H2O with excess PPh3 in ethanol [23].
We note also that a CCl4 suspension of the
[Rh(L1)2]BF4 is not oxidised when treated with Cl2 sat-
urated CCl4 at room temperature (monitored by 31P
NMR spectroscopy).
peaks associated with coordinated L1 and BF4 anion.
ꢁ
Inspection of the far IR region did not reveal any signif-
icant peaks due to Rh–Cl bonds. The electrospray mass
spectrum (MeCN) shows peaks with the correct isotope
distribution for [Rh(L1)2]+ and [Rh(L1)]+, however
again there is no evidence for any Cl containing species
or significant higher mass peaks.
1
The H NMR spectrum shows the ligand resonances
shifted to high frequency upon coordination, while the
31P{1H} NMR spectrum of this product is a sharp dou-
blet at +11.6 ppm, indicative of one P environment, with
1JRhP = 140 Hz. This large coupling constant, together
with the mass spectrometry data were unexpected for a
Rh(III) species, but more in line with the values expected
Fig. 2. View of the structure of the [Rh(L1)2]+ cation with numbering scheme adopted. H atoms and phenyl rings (except the ipso C atoms) are
omitted for clarity. Ellipsoids are shown at the 50% probability level.

78
M.D. Brown et al. / Polyhedron 24 (2005) 75–87
31P NMR shift is also similar, further supporting the
earlier assignments.
Table 2
1
˚
Selected bond lengths (A) and angles (ꢁ) for [Rh(L )2]BF4 Æ2CHCl3
Bond lengths
The analogous reaction using [Ir2Cl2(cod)2] with 0.5
mol equiv. of L1 in CH2Cl2 and NH4PF6 gives the cor-
responding Ir(I) complex [Ir(cod)(L1)]PF6 as an orange-
red solid in good yield (d31P = ꢁ1.8 (L1); electrospray
MS m/z 775 [Ir(cod)(L1)]+.
Rh1–P2
Rh1–P1
Rh1–P4
Rh1–P3
P1–C7
2.3099(10)
2.3269(10)
2.3352(10)
2.3427(10)
1.818(4)
1.833(4)
1.855(4)
1.830(4)
1.837(4)
1.847(4)
1.840(4)
1.842(4)
1.855(4)
1.828(4)
1.833(4)
1.854(4)
P1–C1
P1–C25
P2–C19
P2–C32
P2–C13
P3–C39
P3–C33
P3–C57
P4–C45
P4–C51
P4–C64
2.2. Ni, Pd and Pt complexes
The hydrated Ni(II) halides NiX2 ÆxH2O (X = Cl or
Br) react with one mol equiv. of L1 in isopropanol to
give deep red solids with formation [NiX2(L1)] in good
yield. These are similar to the species described previ-
ously by Venanzi and co-workers, who assigned them
as tetrahedral apparently on the basis that they did
not give NMR spectra [7,8]. However, from the diffuse
reflectance electronic spectra which show one d–d tran-
sition, we assign them as square planar compounds. The
far IR spectra show two peaks which are assigned as Ni–
X stretching vibrations, indicative of a cis-NiX2 unit.
Bond angles
P2–Rh1–P1
P2–Rh1–P4
P1–Rh1–P4
P2–Rh1–P3
P1–Rh1–P3
P4–Rh1–P3
C7–P1–C1
90.05(3)
158.54(3)
92.70(3)
93.98(3)
155.45(4)
92.31(3)
1
These data, together with H NMR and microanalyses,
confirm the assignment of these compounds as square
planar Ni(II) species with a chelating L1 and mutually
cis halides.
102.58(17)
97.91(17)
102.09(17)
115.19(12)
122.96(12)
112.54(12)
103.10(16)
95.41(16)
105.02(17)
116.97(12)
119.44(12)
113.61(12)
98.12(16)
103.34(19)
102.59(17)
104.85(13)
121.61(12)
122.25(12)
105.85(17)
96.21(17)
99.38(17)
112.34(13)
121.99(12)
117.36(12)
C7–P1–C25
C1–P1–C25
C7–P1–Rh1
C1–P1–Rh1
C25–P1–Rh1
C19–P2–C32
C19–P2–C13
C32–P2–C13
C19–P2–Rh1
C32–P2–Rh1
C13–P2–Rh1
C39–P3–C33
C39–P3–C57
C33–P3–C57
C39–P3–Rh1
C33–P3–Rh1
C57–P3–Rh1
C45–P4–C51
C45–P4–C64
C51–P4–C64
C45–P4–Rh1
C51–P4–Rh1
C64–P4–Rh1
The square planar geometry identified for [NiX2(L1)]
is somewhat unexpected given that the corresponding
Ni(II) complexes with the flexible dppb ligand,
[NiX2(dppb)] (also incorporating a 7-membered chelate
ring) [24] adopt tetrahedral geometries. Therefore, it ap-
pears that the increased rigidity of L1 over dppb results
in a preference for square planar coordination. The o-
phenylene diphosphine in [NiX2{o-C6H4(PPh2)2}] (5-
membered chelate ring) which exerts a strong ligand
field, leads to square planar coordination at Ni(II) [25].
An attempt to generate the 5-coordinate Ni(II) spe-
cies [NiI(L1)2](ClO4) through reaction of NiI2 and Ni-
(ClO4)2 Æ6H2O with four mol equiv. of L1, using the
method described by Meek and co-workers [26] for
other diphosphines was unsuccessful. Similarly, we were
unable to isolate the square planar bis-L1 species
[Ni(L1)2](ClO4)2.
The deep orange-brown, unstable Ni(III) species
[NiCl3(L1)] was obtained by NOCl oxidation of
[NiCl2(L1)]. The formulation follows from the electronic
spectrum, which is characteristic of the 5-coordinate
molecule, and the IR spectrum which shows m(Ni–Cl)
in the same region as previously reported Ni(III) species
[27].
The reaction of L1 with 0.5 mol equiv. of the Rh(I)
dimer [Rh2Cl2(cod)2] in CH2Cl2 solution in the presence
of NH4PF6 yields, after work-up, the Rh(I) species
[Rh(cod)(L1)]PF6 as an orange solid in good yield. Thꢁe
IR spectrum confirms the presence of the anionic PF6
as well as coordinated L1. Phosphorus-31 NMR spec-
troscopy of this species shows a sharp doublet at
+10.3 ppm (1JRhP = 146 Hz) and a septet at ꢁ145 ppm
Dissolution of Na2[PdCl4] in EtOH followed by addi-
tion of one mol equiv. of L1 results in formation of a
cream
coloured
precipitate
with
formulation
ꢁ
[PdCl2(L1)]. The far IR spectrum of this compound
from the PF6 anion. Evidence for the cod ligation
comes from the 1H NMR spectrum which also confirms
a 1:1 L1:cod ratio. The Rh–P coupling constant is com-
parable to that for [Rh(L1)2]+ described above, and the
shows two peaks in the region expected for m(Pd–Cl),
indicative of a cis-PdCl2 unit. The H NMR spectrum
is unexceptional, showing small high frequency shifts
1

M.D. Brown et al. / Polyhedron 24 (2005) 75–87
79
upon coordination of L1, while the 31P{1H} NMR spec-
trum shows a singlet at 16.4 ppm, in accord with the
data obtained by Venanzi and co-workers [8] and
assigned as [PdCl2(L1)]. The crystal structure of this
compound (Fig. 3, Table 3) confirms a distorted square
planar coordination environment at Pd(II) through one
chelating L1 ligand and mutually cis Cls. The molecule
has crystallographic m symmetry, with d(Pd–P) =
demand when the metal centre only needs to accommo-
date one L1 rather than two. The P1ꢀ ꢀ ꢀP10 distance of
1
+
˚
3.46 A is larger than in [Rh(L )2] above.
Attempts to abstract both the Clꢀs from [PdCl2(L1)] in
MeCN solution using 2.1 mol equiv. of TlPF6 were not
successful – the only identifiable Pd-containing species
after work-up being the dinuclear [Pd2Cl2(L1)2](PF6)2.
This complex was prepared in good yield by reaction
of [PdCl2(NCMe)2] with one mol equiv. of L1 and one
mol equiv. of TlPF6 in MeCN/CH2Cl2. Removal of
the TlCl precipitate left a light yellow solution from
which the complex was obtained as a yellow solid
following work-up. The IR, 1H NMR spectroscopic
and microanalytical data are consistent with the formu-
lation [Pd2Cl2(L1)2](PF6)2. The 31P{1H} NMR spectrum
of this compound shows a singlet at 27.3 ppm, signifi-
cantly to high frequency of the mononuclear [PdCl2(L1)]
above.
0
˚
2.2572(11) and d(Pd–Cl) = 2.3536 A. The P1–Pd–P1
angle in the chelate of 100.04(6)ꢁ is much more obtuse
than those seen in the Rh(I) species described above,
reflecting the considerable reduction in steric
The structure of [Pd2Cl2(L1)2](PF6)2. 2CH2Cl2 shows
(Fig. 4, Table 4) a dinuclear (l2-Cl)2 palladium dication
with a chelating L1 bound to each Pd centre to give a
distorted square planar geometry. The dication is cen-
trosymmetric, the centre of inversion in the middle of
the Pd2Cl2 core. The Pd–P bond distances are
˚
2.2481(10) and 2.2657(10) A, very similar to d(Pd–P)
in the mononuclear complex above. The P1–Pd–P2 an-
˚
gle in this species is 98.00(4)ꢁ and d(P1ꢀ ꢀ ꢀP2) is 3.41 A.
The homoleptic bis-ligand ion [Pd(L1)2]2+ was subse-
quently prepared by addition of an aqueous solution of
Pd(NO3)2 to two mol equiv. of L1 in EtOH/CH2Cl2
solution, followed by addition of aqueous HBF4. The
IR spectrum of the yellow solid isolated shows peaks
consistent with coordinated L1 and ionic BF4ꢁ, with
no evidence for any remaining nitrate or H2O/OHꢁ in
the product. The H NMR spectrum only shows reso-
nances due to L1. These are shifted to high frequency
of the ꢁfreeꢀ ligand. The 31P{1H} NMR spectrum of this
Fig. 3. View of the structure of [PdCl2(L1)] with numbering scheme
adopted. Ellipsoids are drawn at 50% probability and H atoms are
1
0
omitted for clarity (symmetry operation: , x, 1/2 ꢁ y, z).
Table 3
1
˚
Selected bond lengths (A) and angles (ꢁ) for [PdCl2(L )]
Bond lengths
Pd1–P1
Pd1–Cl1
P1–C1
2.2572(11)
2.3536(11)
1.813(4)
P1–C7
P1–C13
1.818(4)
1.835(4)
Bond angles
P1–Pd1–P10
P1–Pd1–Cl10
P1–Pd1–Cl1
Cl1–Pd1–Cl10
C1–P1–C7
100.04(6)
174.91(4)
84.95(4)
90.04(5)
108.26(19)
102.1(2)
103.3(2)
C1–P1–C13
C7–P1–C13
C1–P1–Pd1
C7–P1–Pd1
C13–P1–Pd1
111.79(14)
109.05(14)
121.43(14)
Fig. 4. View of the structure of the centrosymmetric [Pd2Cl2(L1)2]2+
cation with numbering scheme adopted. H atoms are omitted for
clarity. Ellipsoids are drawn at 50% probability (symmetry operation:
0, ꢁ x, 2 ꢁ y, 1 ꢁ z).
0
Symmetry operation: , x, 1/2 ꢁ y, z.

80
M.D. Brown et al. / Polyhedron 24 (2005) 75–87
[PtCl4(L1)] as a yellow solid. This formulation follows
Table 4
1
˚
Selected bond lengths (A) and angles (ꢁ) for [Pd2Cl2(L )2](PF6)2 Æ
2CH2Cl2
from the far IR spectrum and the microanalysis. The
Pt(IV) complex readily reverts to [PtCl2(L1)] in solu-
tion (as observed by 31P NMR spectroscopy), and
Bond lengths
Pd1–P1
Pd1–P2
Pd1–Cl1
P1–C1
2.2481(10)
2.2657(10)
2.3917(10)
1.818(4)
1.821(4)
1.821(4)
1.802(4)
1.818(4)
1.830(4)
the 31P{1H} NMR spectrum measured in CH2Cl2
1
solution in the presence of Cl2 shows d ꢁ4.8, JPtP
=
2170 Hz, consistent with a PtCl4(L1) composition
[28,29]. Similar treatment of [PdCl2(L1)] did not result
in a colour change, and the 31P{1H} NMR spectrum
is unchanged.
P1–C7
P1–C25
P2–C13
P2–C19
P2–C32
2.3. Cu, Ag and Au complexes
Bond angles
P1–Pd1–P2
P1–Pd1–Cl1
P2–Pd1–Cl1
P1–Pd1–Cl10
P2–Pd1–Cl10
Cl1–Pd1–Cl10
Pd1–Cl1–Pd10
C1–P1–C7
98.00(4)
168.73(4)
90.93(4)
Reaction of [Cu(NCMe)4]BF4 or AgBF4 with two
molar equivalents of L1 in CH2Cl2 solution in the dark
affords colourless solutions from which the homoleptic
phosphine complexes [Cu(L1)2](BF4) and [Ag(L1)2](BF4)
were obtained in high yield. The 2:1 L1:M composition
follows from microanalyses and from the magnitude of
the 107/109Ag–31P coupling constants in the 31P{1H}
NMR spectra – below. Electrospray mass spectrometry
(MeCN) shows the only significant species in each case is
[M(L1)2]+, with much weaker fragment peaks corre-
88.11(4)
172.66(4)
83.52(4)
96.48(3)
106.36(19)
108.45(19)
100.83(18)
108.46(14)
109.03(13)
122.51(14)
107.65(19)
104.80(18)
104.87(18)
114.78(14)
103.67(13)
120.10(13)
C1–P1–C25
C7–P1–C25
C1–P1–Pd1
C7–P1–Pd1
C25–P1–Pd1
C13–P2–C19
C13–P2–C32
C19–P2–C32
C13–P2–Pd1
C19–P2–Pd1
C32–P2–Pd1
1
sponding to [M(L1)]+. The H NMR spectra for these
compounds each show small high frequency shifts in
the CH2 resonance compared to L1 itself, and the
aromatic protons appear as a broad overlapping multi-
plet. The 31P{1H} NMR spectrum of the Cu(I) complex
shows a single broad resonance at ꢁ8.7 ppm, giving a
small high frequency coordination shift. A pseudo-tetra-
hedral bis-L1 coordination environment at Cu(I) is con-
firmed by the observation of a broad 63Cu NMR
resonance at +193 ppm which does not change signifi-
cantly upon cooling. Phosphorus–copper coupling is
not observed in either the 31P{1H} or 63Cu NMR
spectra. This chemical shift is typical of a P4-donor set
at Cu(I) and compares with +150 ppm for [Cu-
(Ph2PCH2CH2PPh2)2]+ and +231 ppm for [Cu(dppp)2]+,
although no 63Cu NMR resonance has been observed
for [Cu(dppb)2]+ between 300 and 175 K, probably
due to reversible chelate ring-opening [30]. The
31P{1H} NMR spectrum of the Ag(I) complex reveals
two overlapping doublets at room temperature at
ꢁ1.5 ppm, giving 1J(107Ag–31P) = 226 Hz and
1J(109Ag–31P) = 257 Hz, indicating that ligand exchange
and/or dissociation are slow on the NMR time-scale.
Furthermore, the magnitude of the coupling constants
provides a good indication of the coordination environ-
ment at Ag. In this species the coupling constants are
consistent with tetrahedral P4-coordination in solution
(compare for example the tetrahedral [Ag(dppe)2]+
J(107Ag–31P) = 231 and J(109Ag–31P) = 266 Hz) [31].
The dihalo-bridged complexes [Ag2Cl2(L1)2] (distorted
tetrahedral P2Cl2 coordination) give J(107Ag–31P) =
359 and J(109Ag–31P) = 413 Hz, small reductions in the
J values occur as the Cl is replaced by Br or I [6].
0
Symmetry operation: , 2 ꢁ x, 2 ꢁ y, 1 ꢁ z.
P4-coordinated species shows a singlet at 7.1 ppm. These
data, together with microanalyses, are consistent with
the formulation [Pd(L1)2](BF4)2. The Pd(II) centre is
likely to be rather crowded, however this formulation
is not unreasonable given the structural evidence for dis-
torted planar [Rh(L1)2]+ cation described above.
The Pt(II) species [PtCl2(L1)] is formed in high yield
by addition of a solution of K2[PtCl4] to one mol equiv.
of L1 in CH2Cl2/EtOH. Acetone was then added to give
a homogeneous solution which was stirred for 72 h be-
fore filtering and concentrating the filtrate in vacuo to
1
give a white solid. The H NMR spectrum is unexcep-
tional and the far IR spectrum shows two peaks, indicat-
ing a cis-PtCl2 unit. The 31P{1H} NMR spectrum shows
a singlet at ꢁ1.8 ppm with 195Pt satellites (J = 3584 Hz),
consistent with the literature data [8]. Confirmation that
the product is indeed the neutral [PtCl2(L1)] and not the
dinuclear [Pt2Cl2(L1)2]Cl2 (cf. the Pd analogue above)
comes from conductivity measurements which show that
in MeNO2 solution the complex is a non-electrolyte. The
195Pt NMR spectrum shows a triplet at ꢁ4503 ppm, in
accord with a P2Cl2 donor set at Pt(II) [28].
Treatment of a CCl4 suspension of [PtCl2(L1) with
excess Cl2 saturated CCl4 gives the Pt(IV) species

M.D. Brown et al. / Polyhedron 24 (2005) 75–87
81
Table 5
The coordination environment at Ag(I) was subse-
quently confirmed by a crystal structure determination
on [Ag(L1)2](BF4)ÆCH2Cl2. The structure of the cation
shows (Fig. 5, Table 5) two L1 ligands coordinated in
a bidentate manner to Ag(I), giving a distorted tetrahe-
dral coordination environment, consistent with the solu-
tion spectroscopic studies. The Ag–P bond distances are
1
˚
Selected bond lengths (A) and angles (ꢁ) for [Ag(L )2]BF4
Bond lengths
Ag1–P1
Ag1–P4
Ag1–P2
Ag1–P3
P1–C1
2.4691(9)
2.4787(9)
2.5222(9)
2.5385(9)
1.821(4)
1.827(4)
1.856(4)
1.825(4)
1.829(4)
1.856(4)
1.830(4)
1.833(4)
1.857(4)
1.821(4)
1.826(4)
1.863(4)
˚
P1–C7
in the range 2.47–2.54 A, while the P1–Ag–P2 and P3–
P1–C49
P2–C13
P2–C19
P2–C56
P3–C25
P3–C31
P3–C57
P4–C43
P4–C37
P4–C64
Ag–P4 chelate angles are 102.88(3)ꢁ and 104.21(3)ꢁ, only
slightly larger than those observed in the 1:1 Pd:L1 com-
plexes above, but some 10ꢁ–12ꢁ larger than in the bis-L1
complex [Rh(L1)2]BF4. The obtuse angles within the
chelate rings in [Ag(L1)2]+ are also confirmed by the
˚
P1ꢀ ꢀ ꢀP2 and P3ꢀ ꢀ ꢀP4 distances of 3.90 and 3.96 A,
˚
respectively. These are over 0.5 A larger than in
[Rh(L1)2]+, reflecting the structural flexibility of the
7-membered chelate ring incorporating the somewhat
rigid o-xylyl unit.
Bond angles
P1–Ag1–P4
P1–Ag1–P2
P4–Ag1–P2
P1–Ag1–P3
P4–Ag1–P3
P2–Ag1–P3
C1–P1–C7
124.76(3)
102.88(3)
The structures of the Ag(I) complexes [Ag2X2(L1)2]
(X = Cl or I) have been described previously. These both
show distorted tetrahedral coordination at Ag(I) via two
bridging X ligands and a chelating L1, with d(Ag–P)
very similar to those seen here for [Ag(L1)2]+ (X = Cl:
108.32(3)
110.69(3)
104.21(3)
104.37(3)
101.21(17)
104.64(16)
104.40(17)
117.74(12)
114.77(12)
112.52(12)
102.14(17)
102.08(16)
105.35(17)
123.17(13)
112.89(12)
109.45(12)
101.35(17)
104.86(17)
100.45(17)
112.36(12)
124.87(13)
110.74(12)
104.34(17)
102.05(16)
102.88(17)
119.38(12)
116.37(12)
109.72(12)
˚
d(Ag–P) = 2.446(1), 2.450(2) A; X = I: d(Ag–P) =
˚
2.487(1), 2.493(2) A), although the P–Ag–P angles
C1–P1–C49
C7–P1–C49
C1–P1–Ag1
C7–P1–Ag1
C49–P1–Ag1
C13–P2–C19
C13–P2–C56
C19–P2–C56
C13–P2–Ag1
C19–P2–Ag1
C56–P2–Ag1
C25–P3–C31
C25–P3–C57
C31–P3–C57
C25–P3–Ag1
C31–P3–Ag1
C57–P3–Ag1
C43–P4–C37
C43–P4–C64
C37–P4–C64
C43–P4–Ag1
C37–P4–Ag1
C64–P4–Ag1
within the chelate rings are closer to the ideal tetrahedral
value in the halo-bridged complexes. Again, this proba-
bly reflects the reduction in steric bulk when only one L1
is present on the Ag centre [6].
The analogous Au(I) complex [Au(L1)2]PF6 was ob-
tained in good yield as a white solid by reaction of
[AuCl(tht)] with two mol equiv. of L1 and one mol
equiv. of TlPF6 in CH2Cl2 solution. The electrospray
mass spectrum reveals a cluster of peaks with the correct
isotope distribution at ca. 1145, consistent with
[Au(L1)2]+, with a lower intensity cluster corresponding
to a fragment ion derived from loss of one L1, while the
IR spectrum shows the presence of ionic PF6ꢁ, but no
Au–Cl unit. The 31P{1H} NMR spectrum shows a sin-
glet at +0.8 ppm due to coordinated L1 and a septet
ðPF6ꢁÞ at ꢁ143.9 ppm with a 4:1 integral ratio. The
coordination environment is confirmed from a crystal
structure of the complex. The structure of [Au(L1)2]P-
F6 Æ2CH2Cl2 shows a distorted tetrahedral cation (Fig.
6, Table 6) derived from two chelating L1 ligands and
˚
giving Au–P bond lengths in the range 2.40–2.43 A.
These bond distances compare very well with the range
˚
2.39–2.42 A reported for [Au(Ph2PCH2CH2PPh2)2]
(flattened tetrahedron) [32].
Fig. 5. View of the structure of the [Ag(L1)2]+ cation with numbering
scheme adopted. Ellipsoids are drawn at 50% probability and H atoms
and phenyl rings (except the ipso C atoms) are omitted for clarity.
+

82
M.D. Brown et al. / Polyhedron 24 (2005) 75–87
Table 6
1
˚
Selected bond lengths (A) and angles (ꢁ) for [Au(L )2]PF6 Æ2CH2Cl2
Bond lengths
Au1–P4
Au1–P1
Au1–P2
Au1–P3
Cl1–C65
Cl2–C65
Cl3–C66
Cl4–C66
P1–C1
2.4006(7)
2.4086(7)
2.4255(7)
2.4301(7)
1.756(4)
1.746(4)
1.726(6)
1.745(5)
1.822(3)
1.824(3)
1.853(3)
1.826(3)
1.830(3)
1.855(3)
1.820(3)
1.828(3)
1.862(3)
1.827(3)
1.830(3)
1.849(3)
P1–C7
P1–C25
P2–C19
P2–C13
P2–C32
P3–C33
P3–C39
P3–C57
P4–C45
P4–C51
P4–C64
Fig. 6. View of the structure of the [Au(L1)2]+ cation with numbering
scheme adopted. Ellipsoids are drawn at 50% probability and H atoms
and phenyl rings (except the ipso C atoms) are omitted for clarity.
The chelate angles subtended at Au are 103.62(2)ꢁ
and 103.65(2)ꢁ, with d(P1ꢀ ꢀ ꢀP2) and d(P3ꢀ ꢀ ꢀP4) = 3.78
˚
A. Comparison of this structure with the Ag(I) analogue
above reveals a small but significant shortening of the
metal–phosphorus bond distances in the 5d Au(I) com-
plex. Similar observations have been made on other re-
lated systems [33].
Bond angles
P4–Au1–P1
P4–Au1–P2
P1–Au1–P2
P4–Au1–P3
P1–Au1–P3
P2–Au1–P3
C1–P1–C7
116.16(2)
115.81(2)
103.62(2)
103.65(2)
114.22(2)
102.94(2)
105.50(14)
101.16(13)
102.43(13)
116.95(9)
114.35(9)
114.61(9)
101.77(13)
104.33(13)
100.13(13)
112.74(10)
122.67(10)
112.98(10)
102.42(13)
105.29(13)
101.65(13)
114.18(9)
117.67(10)
113.96(9)
103.92(13)
101.18(13)
100.63(13)
118.84(9)
117.08(10)
112.58(9)
A similar reaction between [AuCl(tht)] and L1 in a 2:1
ratio and in the absence of TlPF6 also gives a white, light
sensitive solid. The IR spectrum of this compound
clearly indicates the presence of terminal Au–Cl units
(319 cmꢁ1), and its 31P{1H} NMR spectrum is a singlet
at 3ꢁ0.5 ppm, very significantly to high frequency of the
PF6 salt above. The 31P{1H} NMR spectrum of the re-
lated [Au2Cl2(Ph2PCH2CH2PPh2)] displays a similar
coordination shift, giving d(31P) = +31.5 [32]. These data
together with 1H NMR data confirm the formulation as
[(AuCl)2(L1)], probably involving linear Au–Cl coordi-
nation at each P atom of a bridging diphosphine.
C1–P1–C25
C7–P1–C25
C1–P1–Au1
C7–P1–Au1
C25–P1–Au1
C19–P2–C13
C19–P2–C32
C13–P2–C32
C19–P2–Au1
C13–P2–Au1
C32–P2–Au1
C33–P3–C39
C33–P3–C57
C39–P3–C57
C33–P3–Au1
C39–P3–Au1
C57–P3–Au1
C45–P4–C51
C45–P4–C64
C51–P4–C64
C45–P4–Au1
C51–P4–Au1
C64–P4–Au1
3. Conclusions
These results show that L1 is an effective ligand for a
range of late transition metal ions, functioning routinely
as a chelating bidentate. The steric demands of L1 fa-
vour the formation of lower coordination numbers,
and indeed the only bis-L1 complexes we have isolated
involve either distorted square planar or tetrahedral
coordination environments and are sterically quite hin-
dered. This factor may also be responsible for formation
of the unusual Cl-bridged dimer [Pd2Cl2(L1)2]2+, as the
Pd(II) centre can more readily accommodate one L1
and two relatively small Cl ligands rather than two che-
lating L1ꢀs. The presence of the aromatic unit in the li-
gand backbone leads to increased rigidity relative to
the aliphatic dppb, a greater tendency to chelate, and
promotes coordination chemistry more akin to the rigid
o-phenylene analogue o-C6H4(PPh2)2. The flexibility of
L1 is also evident from the wide range of Pꢀ ꢀ ꢀP distances
measured within the chelate rings from the six crystal
structures.
4. Experimental
Infrared spectra were recorded as either Nujol mulls
between CsI plates or as CsI disks using a Perkin–Elmer

M.D. Brown et al. / Polyhedron 24 (2005) 75–87
83
983G spectrometer over the range 4000–200 cmꢁ1. UV/
4.4. [CoI2(L1)]
vis spectra were recorded either as solids by diffuse
reflectance or in CH2Cl2 solution using 1 cm path length
quartz cells using a Perkin–Elmer Lambda19 spectrom-
eter. Mass spectra were run by electron impact on a VG-
70-SE Normal geometry double focusing spectrometer
or by positive ion electrospray (MeCN solution) using
a VG Biotech platform. 1H NMR spectra were recorded
using a Bruker AC300 spectrometer. 13C{1H}, 31P{1H],
63Cu and 195Pt{1H} NMR spectra were recorded using a
Bruker DPX400 spectrometer operating at 100.6, 162.0,
106.11 or 85.62 MHz, respectively, and are referenced to
TMS, external 85% H3PO4, [Cu(NCMe)4]BF4 and 1 mol
dmꢁ3 Na2[PtCl6], respectively. Microanalyses were
undertaken by the University of Strathclyde microana-
lytical service.
Method as above, but using CoI2. Brown-green solid
(yield 55%). Required for [C32H28CoI2P2]Æ1.5CH2Cl2:
C, 44.0; H, 3.4. Found: C, 43.7; H, 3.1%. UV/vis (diffuse
reflectance): m 6610, 7350, 12770, 14045, 14730, 20830
sh, 2500 sh cmꢁ1; (CH2Cl2 solution): 12805 (emol 920
cmꢁ1 molꢁ1 dm3), 13965 (885), 14840 (770) cmꢁ1. Mag-
netic moment = 4.84 lB.
4.5. [Rh(L1)2]BF4
RhCl3 Æ3H2O (0.0416 g, 0.158 mmol) was dissolved in
EtOH (20 cm3). Two equivalents of L1 (0.15 g, 0.316
mmol) dissolved in CH2Cl2 (10 cm3) was then added, to-
gether with 40% aqueous HBF4 (1 cm3). The resulting
mixture was stirred at room temperature for 30 min.
Concentrating the mixture in vacuo gave an orange pre-
cipitate, which was filtered, washed with diethyl ether
and dried in vacuo (yield 52%). Required for
[C64H56BF4P4Rh]Æ2CHCl3: C, 57.5; H, 4.2. Found: C,
C, 58.3; H, 4.6%. 1H NMR (CDCl3): 7.00–7.40 (m)
[40H] (Ph), 6.90 (m) [4H] (o-C6H4), 6.35 (m) [4H] (o-
C6H4), 3.65 (br s) [8H] (CH2). 31P{1H} NMR
Solvents were dried prior to use and all preparations
were undertaken using standard Schlenk techniques un-
der a N2 atmosphere. The ligand L1 was prepared as de-
scribed previously [8].
4.1. [CoCl2(L1)]
CoCl2 Æ6H2O (0.075 g, 0.316 mmol) was dissolved in
isopropanol (20 cm3). One molar equivalent of L1
(0.150 g, 0.316 mmol) dissolved in CH2Cl2 (10 cm3)
was added and the reaction mixture was stirred for ca.
30 min. to give a turquoise solid. The solvent was con-
centrated to ca. 5 cm3 in vacuo and the solid was col-
lected by filtration, washed with isopropanol and dried
in vacuo (yield 67%). Required for [C32H28Cl2CoP2]Æ1/
4CH2Cl2: C, 61.9; H, 4.6. Found: C, 62.4; H, 4.3%.
UV/vis (diffuse reflectance): m 6120, 7750, 13460,
15080, 16155, 25700 sh cmꢁ1; (CH2Cl2 solution): m
13590 (emol 1000 cmꢁ1 molꢁ1 dm3), 15625 (900),
1
(CH2Cl2/CDCl3): 11.6 ppm (d, JRhP = 140 Hz). IR
spectrum (Nujol mull): m 1060 s, 506 s cmꢁ1. Electro-
spray MS (MeCN): m/z 1051 [Rh(L1)2]+, 557
[Rh(L1)]+, 475 [L1 + H]+.
4.6. [Rh(cod)(L1)]PF6
[RhCl(cod)]2 (0.077 g, 0.158 mmol) was dissolved in a
degassed solution of CH2Cl2 (20 cm3). NH4PF6 (0.057 g,
0.35 mmol) and L1 (0.15 g, 0.316 mmol) were added to
the mixture and the reaction was stirred under nitrogen
for 30 min. The reaction mixture changed from yellow
to red and the white precipitate (NH4Cl) was filtered
off. The solution was reduced in volume to ꢂ5 cm3 in va-
cuo. Upon addition of diethyl ether (10 cm3) an orange
precipitate formed which was filtered and washed with
diethyl ether (2 · 10 cm3). The orange solid (0.145 g,
16920 (1060) cmꢁ1. IR (Nujol mull): m 318 br cmꢁ1
Magnetic moment = 4.68 lB.
.
4.2. [CoCl3(L1)]
Treatment of a CH2Cl2 solution of [CoCl2(L1)] with a
stream of NOCl at ca. ꢁ15 ꢁC leads to immediate for-
mation of a deep green-blue solution which, upon
pumping to dryness in vacuo affords a green-blue solid.
IR (Nujol mull): m 349, 321, 311 cmꢁ1. UV/vis (CH2Cl2
55%)
was
dried
in
vacuo.
Required
for
[C40H40F6P3Rh]Æ1/2CH2Cl2: C, 55.7; H, 4.7. Found:
1
C, 56.1; H, 3.9%. H NMR (CDCl3): d 7.70–7.50 (m)
[20H] (Ph), 6.85 (m) [2H] (o-C6H4), 6.40 (m) [2H] (o-
C6H4), 4.40 (br m) [4H] (cod CH), 3.90 (br m) [4H]
(L1CH2), 2.0–2.2 (m) [8H] (cod CH2). 31P{1H} NMR
solution): m 6580, 16130, 16530 sh, 28570 cmꢁ1
.
4.3. [CoBr2(L1)]
1
(CH2Cl2/CDCl3): 10.3 ppm (d, JRhP = 146 Hz) [2P],
ꢁ143.8 (septet, PF6ꢁ) [1P]. IR (Nujol mull): 840 s, 557
Method as above, but using CoBr2 Æ6H2O. Green
solid (yield 62%). Required for [C32H28Br2CoP2]: C,
55.4; H, 4.1. Found: C, 55.4; H, 3.7%. UV/vis (diffuse
s cmꢁ1
.
reflectance): m 6540, 7605, 13265, 15130, 15875 cmꢁ1
;
4.7. [Ir(cod)(L1)]PF6
(CH2Cl2 solution): 13280 (emol 1580 cmꢁ1 molꢁ1 dm3),
15040 (1560), 16050 (1460) cmꢁ1. IR (Nujol mull): m
243 br cmꢁ1. Magnetic moment = 4.41 lB.
Method as above, using [Ir2Cl2(cod)2], giving an or-
ange-red solid (yield 55%).

84
M.D. Brown et al. / Polyhedron 24 (2005) 75–87
Required for [C40H40F6IrP3]ÆCH2Cl2: C, 49.0; H, 4.2.
7.60 (m) [20H] (Ph), 6.88 (m) [2H] (o-C6H4), 6.15 (m)
[2H] (o-C6H4), 3.75 (br d, J = 10 Hz) [4H] (CH2).
31P{1H} NMR (CH2Cl2/CDCl3): d 16.4 ppm. IR (CsI
disk): m 3064 w, 2971 w, 2933 w, 1586 w, 1481 m, 1433
s, 1360 m, 1188 w, 1103 s, 1073 w, 1027 w, 1000 m,
867 w, 837 m, 746 s, 700 s, 504 s, 452 w, 316 m, 304 m
Found: C, 48.3; H, 3.7%. 1H NMR (CDCl3): d 7.70–7.30
(m) [20H] (Ph), 6.85 (m) [2H] (o-C6H4), 6.40 (m) [2H] (o-
C6H4), 4.18 (br m) [4H] (cod CH), 3.92 (br m) [4H]
(L1CH2), 1.7–2.0 (m) [8H] (cod CH2). 31P{1H} NMR
(CH2Cl2/CDCl3): ꢁ1.8 ppm (s) [2P], ꢁ143.8 (septet,
PF6ꢁ) [1P]. IR (Nujol mull): 841 s, 557 s cmꢁ1. Electro-
spray MS (MeCN): m/z 775 [Ir(cod)(L1)]+.
cmꢁ1
.
4.12. [Pd2Cl2(L1)2](PF6)2
4.8. [NiCl2(L1)]
PdCl2 (0.056 g, 0.316 mmol) was dissolved in MeCN
(20 cm3), by refluxing for 1 h. One equivalent of L1 (0.15
g, 0.316 mmol) was added to the reaction mixture, fol-
lowed by, one equivalent of TlPF6 (0.11 g, 0.316 mmol).
The resulting reaction mixture was stirred overnight and
then filtered. The yellow filtrate was reduced to ꢂ5 cm3.
Cold diethyl ether (ꢂ10 cm3) was added dropwise to
precipitate a yellow solid, which was filtered and dried
in vacuo (yield 44%). Required for [C64H56Cl2F12P6Pd2]:
NiCl2 Æ6H2O (0.075 g, 0.316 mmol) was dissolved in
isopropanol (20 cm3) and one mol equiv. of L1 (0.15 g,
0.316 mmol) was added. Stirring the reaction mixture
for 1 h afforded a deep pink solid which was filtered
and dried in vacuo. Recrystallisation from CH2Cl2 gave
a
deep pink solid (yield 76%). Required for
[C32H28Cl2NiP2]Æ1.5CH2Cl2: C, 55.0; H, 4.3. Found:
1
C, 55.5; H, 5.0%. H NMR (CDCl3): d 6.90–7.40 (br
1
m) [20H] (Ph), 6.70 (br m) [2H] (o-C6H4), 6.30 (br m)
[2H] (o-C6H4), 3.40 (br m) [4H] (CH2) ppm. UV/vis (dif-
fuse reflectance): 20325, 29415, 37310 cmꢁ1; (CH2Cl2
solution): 20410 (emol 510 cmꢁ1 molꢁ1 dm3). IR (Nujol
C, 50.5; H, 3.7. Found: C, 50.9; H, 3.8%. H NMR
(CDCl3): d 7.40–7.90 (m) [40H], (Ph), 6.80 (m) [4H] (o-
C6H4), 6.20 (m) [4H] (o-C6H4), 3.90 (br d, J = 12 Hz)
[8H], (CH2). 31P{1H} NMR (CH2Cl2/CDCl3): d 27.3
(s) [4P] (–P–Ph), ꢁ143.7 (septet) [2P] ðPF6ꢁÞ ppm. IR
(CsI disk): m 3082 w, 3067 w, 3031 w, 2932 w, 1587 w,
1485 w, 1437 s, 1356 m, 1185 w, 1167 w, 1106 m, 1068
w, 1002 m, 843 br s, 777 m, 746 m, 696 m, 561 s, 501
m, 457 m, 374 w, 315 m cmꢁ1. Electrospray MS
(MeCN): m/z 617 [PdCl(L1)]+, 658 [PdCl(L1)(MeCN)]+.
mull): m 337 m, 322 m cmꢁ1
.
4.9. [NiCl3(L1)]
Treatment of a CH2Cl2 solution of [NiCl2(L1)] with a
stream of NOCl at ca. ꢁ50 ꢁC gave a deep orange-
brown solution, from which an orange brown solid
was obtained upon pumping to dryness in vacuo. IR
(Nujol mull): m 340, 312, 300 sh cmꢁ1. UV/vis (CH2Cl2
4.13. [Pd(L1)2](BF4)2
solution): 12900 v br, 21050, 28570 cmꢁ1
.
L1 (0.15 g, 0.316 mmol) was dissolved in a mixture of
EtOH (20 cm3) and CH2Cl2 (10 cm3). Pd(NO3)2 (0.036
g, 0.158 mmol) was dissolved in deionised H2O (ꢂ10
cm3) and added forming an orange solution. An excess
of 40% aqueous HBF4 (2 cm3) was then added, and
the reaction was stirred for 1 h. The solution was
reduced in volume until a yellow precipitate formed
which was filtered and dried in vacuo (yield 69%).
Required for [C64H56B2F8P4Pd]: C, 62.5; H, 4.6. Found:
4.10. [NiBr2(L1)]
Prepared as above with NiBr2 Æ3H2O (0.086 g, 0.316
mmol) and L1 (0.15 g, 0.316 mmol) to afford a brick
red solid (yield 87%). Required for [C32H28Br2Ni-
P2]Æ1.5CH2Cl2: C, 49.0; H, 3.8. Found: C, 48.3; H,
4.9%. 1H NMR (CDCl3): d 6.70–7.50 (br m) [24H]
(Ar–CH), 3.80 (br m) [4H] (CH2) ppm. UV/vis (diffuse
reflectance): 19600, 24040, 29240 cmꢁ1; (CH2Cl2 solu-
tion): 19920 (emol 450 cmꢁ1 molꢁ1 dm3), 25000 (1485),
1
C, 63.0; H, 4.9%. H NMR (CDCl3): d 7.30–7.80 (m)
[40H] (Ph), 6.20–6.80 (m) [8H] (o-C6H4), 3.70 (br m)
ppm [8H] (CH2). 31P{1H} NMR (CH2Cl2/CDCl3): d
30675 (3140) cmꢁ1. IR (Nujol mull): 282 w, 262 cmꢁ1
.
7.1 ppm. IR (Nujol mull): m 1067 s, 505 s cmꢁ1
.
4.11. [PdCl2(L1)]
4.14. [PtCl2(L1)]
Na2PdCl4 (0.093 g, 0.316 mmol) was dissolved in
EtOH (20 cm3). One equivalent of L1 (0.15 g, 0.316
mmol) was added in EtOH (ꢂ5 cm3). The reaction mix-
ture was stirred overnight, and a pale cream precipitate
formed. After filtering and drying in vacuo a cream solid
(yield 58%) was recovered. Required for [C32-
H28Cl2P2Pd]ÆCH2Cl2: C, 53.8; H, 4.1. Found: C, 54.2;
H, 4.2%. 1H NMR (CDCl3): d 7.85–7.98 (m), 7.44–
K2PtCl4 (0.13 g, 0.316 mmol) was dissolved in deion-
ised H2O (10 cm3) and added to EtOH (20 cm3) whilst
stirring. One equivalent of L1 (0.15 g, 0.316 mmol) dis-
solved in CH2Cl2 (10 cm3) was added. The reaction mix-
ture was stirred for 3 h, and the subsequent two layers
were combined with the addition of acetone (10 cm3).
After stirring for 72 h, the mixture was filtered and then
reduced in volume until a cream precipitate formed

M.D. Brown et al. / Polyhedron 24 (2005) 75–87
85
which was filtered and dried in vacuo (yield 98%). Re-
quired for [C32H28Cl2P2Pt]: C, 51.9; H, 3.8. Found: C,
51.1; H, 3.9%. 1H NMR (CDCl3): d 7.90–8.00 (m),
7.45–7.60 (m) [20H] (Ph), 6.90 (m) [2H] (o-C6H4), 6.20
(m) [2H] (o-C6H4), 3.95 (br d, J = 11 Hz) [4H] (CH2)
ppm. 31P{1H} NMR (CH2Cl2/CDCl3): d ꢁ1.8 ppm,
Hz). IR (Nujol mull): m 326 w, 304 w cmꢁ1. Conductivity
KM/Xꢁ1 cm2 molꢁ1 (10ꢁ3 mol dmꢁ3 MeNO2): 11.0.
Electrospray MS (MeCN): m/z 745 [PtCl(L1)(MeCN)]+.
31P {1H} NMR (CH2Cl2/CDCl3): d ꢁ1.5 (2 · d,
1J
¼ 226 Hz; 1J
¼ 257 Hz).
Electro-
107Ag–31
P
109Ag–31
P
spray MS (MeCN): m/z 1055 [107Ag(L1)2]+, 1057
[
109Ag(L1)2]+. IR (Nujol mull): m 1059 m, 504 m cmꢁ1
.
4.18. [Au(L1)2]PF6
1
1JPt–P = 3584 Hz. 195Pt NMR: ꢁ4503 (t, JPtP = 3584
L1 (0.15 g, 0.316 mmol) was dissolved in CH2Cl2 (20
cm3). AuCl(tht) (0.051 g, 0.158 mmol) was added to the
reaction vessel, followed by TlPF6 (0.055 g, 0.158
mmol). The vessel was wrapped in foil to exclude light.
This was stirred for 1 h, and filtered to remove TlCl. The
volume was reduced to ꢂ5 cm3 and a white precipitate
formed, which was filtered and dried in vacuo. The
resulting fine white powder (yield 66%) was stored in a
sample bottle excluding light. Required for
[C64H56AuF6P5]ÆCH2Cl2: C, 56.7; H, 4.2. Found: C,
57.3; H, 3.9%. 1H NMR (CDCl3): d 7.10–7.35 (m)
[40H] (Ph), 6.40 (m) [4H] (o-C6H4), 5.83 (m) [4H] (o-
C6H4), 3.75 (br s) [8H], (CH2) ppm. 31P{1H} NMR
(CH2Cl2/CDCl3): d 0.8 (s) [4P] (P–Ph), ꢁ143.9 (sep)
[1P] (PF6) ppm. Electrospray MS (MeCN): m/z 1145
[Au(L1)2]+, 671 [Au(L1)]+. IR (Nujol mull): m 850 br s,
4.15. [PtCl4(L1)]
Treatment of a CH2Cl2 solution of [PtCl2(L1)] with
Cl2 in CCl4 gave a bright yellow solution, which upon
concentrating in vacuo gave a bright yellow solid.
Required for [C32H28Cl4P2Pt]ÆCH2Cl2: C, 44.2; H, 3.4.
Found: C, 44.8; H, 3.4%. 31P{1H} NMR (CH2Cl2/
CDCl3): d ꢁ4.8 ppm, 1JPt–P = 2160 Hz. IR (Nujol mull):
m 344, 299, 288 cmꢁ1
.
4.16. [Cu(L1)2](BF4)
[Cu(NCMe)4](BF4) (0.044 g, 0.158 mmol) was
dissolved in CH2Cl2 (20 cm3) and stirred. Two equiva-
lents of L1 (0.15 g, 0.316 mmol) were added, and the
reaction was stirred for 2 h. The solution was reduced
in volume to ꢂ5 cm3 and hexane (15 cm3) was added
to precipitate a solid. This was filtered and the white so-
lid (yield 92%) was dried in vacuo. Required for
[C64H56BCuF4P4]Æ2CH2Cl2: C, 62.5; H, 4.8. Found: C,
560 s cmꢁ1
.
4.19. [(AuCl)2(L1)]
L1 (0.072 g, 0.152 mmol) was dissolved in CH2Cl2 (20
cm3). AuCl(tht) (0.098 g, 0.304 mmol) was added and
the vessel was wrapped in foil to exclude light. The reac-
tion mixture was stirred for 30 min at room tempera-
ture, and then reduced in volume to ꢂ5 cm3. The
resulting white precipitate was filtered and dried in va-
cuo to afford a fine white powder (yield 23%), which
was placed in a foil wrapped container. 1H NMR
(CDCl3): d 7.30–7.60 (m) [20H] (Ph), 6.86 (m) [2H] (o-
C6H4), 6.35 (m) [2H] (o-C6H4), 3.92 (br) [4H] (CH2)
ppm. 31P {1H} NMR (CH2Cl2/CDCl3): d 30.5 (s) ppm.
1
62.5; H, 4.9%. H NMR (CDCl3): d 7.70–6.80 (br m)
[44H] (Ar–CH), 6.30 (br m) [4H] (o-C6H4) 3.65 (br m)
[8H] (CH2). 31P{1H} NMR: d ꢁ8.7 (s) ppm. 63Cu
NMR: d +193 ppm. Electrospray MS (MeCN): m/z
1011 [Cu(L1)2]+, 578 [Cu(L1)](MeCN)]+, 537 [Cu(L1)]+.
IR (CsI disk): m 3059 w, 2964 w, 2927 w, 1590 w, 1482
m, 1437 s, 1359 w, 1272 w, 1186 m, 1159 w, 1096 s,
1062 br s, 1003 w, 865 m, 842 m, 766 m, 735 s, 700 s,
IR (Nujol mull): m 319 m cmꢁ1
.
504 s, 486 s, 445 w, 342 w cmꢁ1
.
4.17. [Ag(L1)2](BF4)
5. X-ray crystallography
AgBF4 (0.031 g, 0.158 mmol) was dissolved in
CH2Cl2 (20 cm3) in a foil wrapped reaction vessel to ex-
clude light, at 0 ꢁC. Two equivalents of L1 (0.15 g, 0.316
mmol) were dissolved in CH2Cl2 (10 cm3) and added
dropwise whilst stirring to the reaction mixture, keeping
the temperature at 0 ꢁC. After stirring for 2 h, the white
precipitate was recovered by filtration, and dried in va-
cuo to afford a white solid (yield 82%). The solid was
stored in a foil wrapped container to exclude light. Re-
quired for [C64H56AgBF4P4]Æ1.5CH2Cl2: C, 61.9; H,
4.7. Found: C, 62.4; H, 5.1%. 1H NMR (CDCl3): d
6.95–7.30 (m) [40H] (Ph), 6.65 (br m) [4H] (o-C6H4),
6.20 (br m) [4H] (o-C6H4), 3.65 (br s) [8H] (CH2) ppm.
Details of the crystallographic data collection and
refinement parameters are given in Table 7. Small blue
crystals of [CoCl2(L1)] were obtained by vapour diffu-
sion of diethyl ether into a CH2Cl2 solution of the
complex. Orange crystals of [Rh(L1)2]BF4 Æ2CHCl3 were
obtained by liquid diffusion of hexane into a solution
of the complex in CHCl3, while yellow crystals
of [PdCl2(L1)]Æ2CH2Cl2 and [Pd2Cl2(L1)2](PF6)2 and
colourless crystals of [Ag(L1)2]BF4 Æ2CH2Cl2 and
[Au(L1)2]PF6 Æ2CH2Cl2 were grown by liquid diffusion of
hexane into a CH2Cl2 solution of the appropriate com-
plex. Data collection used a Nonius Kappa CCD diffrac-
tometer (T = 120 K) and with graphite-monochromated

86
M.D. Brown et al. / Polyhedron 24 (2005) 75–87
˚
Mo Ka X-radiation (k = 0.71073 A). Structure solution
and refinement were routine [34,35]. Selected bond
lengths and angles are given in Tables 1–6.
6. Supplementary material
Crystallographic data for the structural analyses have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 240478 (Co), 240479 (Rh),
240480 (Pd monomer), 240481 (Pd dimer), 240482
(Ag), 240483 (Au). Copies of this information may be
obtained free of charge from The Director, CCDC, 12
Union Road, Cambridge CD2 1EZ, UK (fax: +44
1223 336033; email: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
Acknowledgements
We thank the EPSRC for support and Johnson-
Matthey plc for loans of precious metal salts. We also
thank Professor M.B. Hursthouse for access to the
Nonius Kappa CCD diffractometer.
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