New complexes of functionalised ligands bearing P/N/Se or P2Se donor sets

Article abstract of DOI:10.1039/b204005k

The new selenoether functionalised tertiary phosphines (2-Ph₂P)C₆H₄C(H)=N(CH₂) _nSePh (n = 3 1a; 4 1b) were readily prepared by condensation of (2-Ph₂P)C₆H₄C(H)=O and H₂N(CH₂)_nSePh (n = 3, 4) in absolute ethanol. Reaction of two equiv. of Ph₂PCH₂OH with H₂N(CH₂)_nSePh (n = 3, 4) affords the symmetrical ditertiary phosphines (Ph₂PCH₂)₂N(CH₂)_nSePh (n = 3 2a; 4 2b. Reaction of 1a-2b with [MCl₂(cod)] (M = Pt, Pd) gave the dichlorometal(II) chelate complexes 3a-4d in which either six-membered P,P- or P,N-ligation is observed. Chloro bridge cleavage of [{RuCl₂(p-cymene)}₂] or tht (tht = tetrahydrothiophene) substitution of [AuCl(tht)] with 2a (or 2b) gave the new complexes [{RuCl₂(p-cymene)}₂{μ-(P,P′-Ph₂PCH ₂)₂N(CH₂)_nSePh}] (n = 3 5a; 4 5b) or [{AuCl}₂{μ-(P,P′-Ph₂PCH₂) ₂N(CH₂)_nSePh}] (n = 3 6a; 4 6b) in which the ligand P,P′-bridges two metal centres. Spectroscopic evidence suggests the pendant selenoether group in 3c undergoes further reaction with [PdCl₂(MeCN)₂] affording an unusual trinuclear palladium(II) complex 7. Furthermore reaction of 3b with 1 equiv. of Ag[BF₄] in dichloromethane gave the cationic complex [PtCl(1a)][BF₄]8 in which 1a functions as a P,N,Se-tridentate ligand. All structures have been confirmed by a combination of spectroscopic, analytical and single crystal X-ray studies. The structure of 8 represents, to the best of our knowledge, an extremely rare example of a crystallographically characterised Group 10 metal complex with a P/N/Se/Cl coordination environment.

Full text of DOI:10.1039/b204005k

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New complexes of functionalised ligands bearing P/N/Se or
P2Se donor sets
Sean E. Durran, Mark R. J. Elsegood and Martin B. Smith*
Department of Chemistry, Loughborough University, Loughborough, Leics, UK LE11 3TU.
E-mail: m.b.smith@lboro.ac.uk.; Fax: +44 (0)1509 223925; Tel: +44 (0)1509 222553
Received (in London, UK) 23rd April 2002, Accepted 25th July 2002
First published as an Advance Article on the web 5th September 2002
The new selenoether functionalised tertiary phosphines (2-Ph2P)C6H4C(H)=N(CH2)nSePh (n ¼ 3 1a; 4 1b) were
readily prepared by condensation of (2-Ph2P)C6H4C(H)=O and H2N(CH2)nSePh (n ¼ 3, 4) in absolute ethanol.
Reaction of two equiv. of Ph2PCH2OH with H2N(CH2)nSePh (n ¼ 3, 4) affords the symmetrical ditertiary
phosphines (Ph2PCH2)2N(CH2)nSePh (n ¼ 3 2a; 4 2b). Reaction of 1a–2b with [MCl2(cod)] (M ¼ Pt, Pd) gave
the dichlorometal(II) chelate complexes 3a–4d in which either six-membered P,P- or P,N-ligation is observed.
Chloro bridge cleavage of [{RuCl2(p-cymene)}2] or tht (tht ¼ tetrahydrothiophene) substitution of [AuCl(tht)]
with 2a (or 2b) gave the new complexes [{RuCl2(p-cymene)}2{m-(P,P0-Ph2PCH2)2N(CH2)nSePh}] (n ¼ 3 5a; 4
5b) or [{AuCl}2{m-(P,P0-Ph2PCH2)2N(CH2)nSePh}] (n ¼ 3 6a; 4 6b) in which the ligand P,P0-bridges two metal
centres. Spectroscopic evidence suggests the pendant selenoether group in 3c undergoes further reaction with
[PdCl2(MeCN)2] affording an unusual trinuclear palladium(II) complex 7. Furthermore reaction of 3b with 1
equiv. of Ag[BF4] in dichloromethane gave the cationic complex [PtCl(1a)][BF4] 8 in which 1a functions as a
P,N,Se-tridentate ligand. All structures have been confirmed by a combination of spectroscopic, analytical and
single crystal X-ray studies. The structure of 8 represents, to the best of our knowledge, an extremely rare
example of a crystallographically characterised Group 10 metal complex with a P/N/Se/Cl coordination
environment.
As a consequence of the relatively weak P=Se bond, as in D
Introduction
[and also the diselenide {Ph2P(Se)}2NH], low valent metal
centres undergo facile oxidative addition reactions with such
compounds.13,14 There are limited reports on phosphorus(III)
ligands such as G in which a direct single P–Se bond exists
as opposed to the P=Se double bond observed in D–F.15,16
As part of continuing studies in our group developing the
use of Ph2PCH2OH17–20 as a synthon to new phosphorus
based ligands, we describe here the preparation of two classes
of ‘‘hybrid’’ ligands with P/N/Se or P2Se donor sets. The pro-
cedure employed here should enable many future variants to
be prepared using this facile method. Some initial studies on
the coordination behaviour of the ligands has been evaluated
with a range of ligating modes uncovered. In several cases
X-ray crystal structures have been determined. The X-ray
structure of 8 represents an extremely rare d8 metal complex
containing P/N/Se/Cl donor atoms. Ligands containing
phosphorus–nitrogen donors have recently been shown to be
efficient catalysts for the Heck reaction, coupling of organos-
tannanes and aryl halides, oligomerisation of ethene and allylic
alkylation.21
The chemistry of ligands bearing P/Se or P/N/Se donor sets
has surprisingly been neglected with respect to ligands bearing
P/X or P/N/X (X ¼ O, S)1,2 donor combinations. Studies of
ligands bearing primarily P and Se donor atoms (e.g. A–G
Chart 1) are sporadic yet some important features from these
examples merit discussion. Ligands such as A–C incorporate
both P and Se donors, separated by a carbon (alkyl, aryl) or
nitrogen spacer.3–9 Furthermore these ligands have been
known for some time yet surprisingly their coordination chem-
istry has only been poorly studied.7–9 By contrast, phosphine
selenides such as D–F are known and form many complexes
(especially with D) via ligation of the selenium donor atom
or, in the case of F, as an anionic N,Se-bidentate ligand.10–12
Experimental
Standard Schlenk techniques were used for ligand syntheses
whilst all other reactions were carried out in air using pre-
viously distilled solvents unless otherwise stated. The amines
H2N(CH2)nSePh (n ¼ 3, 4),22 Ph2PCH2OH23 and the metal
complexes [MCl2(cod)] (M ¼ Pd, Pt),24 [{RuCl(m-Cl)(Z6-p-
cymene)}2]25 and [AuCl(tht)]26 were prepared according to
previous known procedures. All other chemicals were obtained
from commercial sources and used directly without further
purification.
Chart 1
1402
New J. Chem., 2002, 26, 1402–1408
DOI: 10.1039/b204005k
This journal is # The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2002

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Infrared spectra were recorded as KBr pellets in the range
4000–200 cmꢀ1 on a Perkin-Elmer System 2000 Fourier-trans-
cis-[PtCl2{(2-Ph2P)C6H4C(H)=N(CH2)2SePh-P,N}] 4a. To a
CH2Cl2 (10 cm3) solution of (2-Ph2P)C6H4C(H)=N(CH2)3-
SePh (0.047 g, 0.097 mmol) was added [PtCl2(cod)] (0.036 g,
0.096 mmol). The solution was stirred for ca. 15 min, the
volume concentrated in vacuo to ca. 1–2 cm3 and diethyl
ether (15 cm3) added. The white solid was collected by suction
filtration and dried in vacuo. Yield: 0.054 g, 75%. In a similar
manner the complexes cis-[PtCl2{(2-Ph2P)C6H4C(H)=N-
(CH2)4SePh-P,N}] 4b (93%), cis-[PdCl2{(2-Ph2P)C6H4C(H)=
N(CH2)3SePh-P,N}] 4c (93%) and cis-[PdCl2{(2-Ph2P)C6H4-
C(H)=N(CH2)4SePh-P,N}] 4d (94%) were also prepared.
Selected NMR and IR data: 31P: 5.1 [1J(PtP) 3735]; 8.25
1
form spectrometer, H NMR spectra (250 MHz) on a Bruker
AC250 FT spectrometer with chemical shifts (d) in ppm to
high frequency of SiMe4 and coupling constants (J) in Hz,
31P{1H} NMR spectra were recorded on a JEOL FX90Q
(36.2 MHz) spectrometer with chemical shifts (d) in ppm to
high frequency of 85% H3PO4 and coupling constants (J) in
Hz. All NMR spectra were measured in CDCl3 unless other-
wise stated. Elemental analyses (Perkin-Elmer 2400 CHN
Elemental Analyzer) were performed by the Loughborough
University Analytical Service within the Department of Chem-
istry.
1
[3J(PtH) 102] (CHimine), H: 7.61–6.95 (arom. H), 4.72, 2.26,
Precious metal salts were provided on loan by Johnson
Matthey plc.
1.64 (CH2); nPtCl 341, 279 cmꢀ1; m/z ¼ 716 (M ꢀ Cl) for 4a.
1
31P: d 5.3 [1J(PtP) 3748]; 8.30 [3J(PtH) 103] (CHimine), H: d
7.75–6.94 (arom. H), 4.56, 2.66, 1.86, 1.28 (CH2); nPtCl 338,
281 cmꢀ1; m/z ¼ 730 (M ꢀ Cl) for 4b. 31P: d 31.0; H: d 8.08
1
Preparations
(CHimine), 7.73–6.89 (arom. H), 4.50, 2.27, 2.17 (CH2); nPdCl
1
335, 267 cmꢀ1; m/z ¼ 628 (M ꢀ Cl) for 4c. 31P: d 31.3; H: d
(2-Ph2P)C6H4C(H)=N(CH2)3SePh 1a. A mixture of (2-
Ph2P)C6H4C(H)O (0.418 g, 0.410 mmol) and H2N(CH2)3SePh
(0.299 g, 0.410 mmol) in absolute ethanol (10 cm3) was stirred
under a nitrogen atmosphere at 50 ꢁC for 3 h. The solvent was
evaporated to dryness under reduced pressure to give a yellow
oil. Yield: 0.59 g, 87%. Compound 1a was of sufficient purity
8.14 (CHimine), 7.77–6.89 (arom. H), 4.36, 2.69, 1.79, 1.28
(CH2); nPdCl 336, 269 cmꢀ1; m/z ¼ 642 (M ꢀ Cl) for 4d.
i
[{RuCl2(g6-p-MeC6H4 Pr)}2{PhSe(CH2)3N(CH2PPh2-l-P,
P0)2}] 5a. To a CH2Cl2 (10 cm3) solution of (Ph2PCH2)2-
(as determined by 31P{1H} and H NMR spectroscopy) to be
1
N(CH2)3SePh(0.088 g, 0.144 mmol) was added [{RuCl2(Z6-
p-MeC6H4 Pr)}2] (0.088 g, 0.144 mmol). The solution was
i
used directly in subsequent coordination studies. The same
preparative method was used for 1b (77%). Selected NMR
data: 31P: d ꢀ13.0; 1H: d 8.83 [4J(PH) 4.4] (CHimine), 7.94–
6.84 (arom. H), 3.56, 2.68, 1.88 (CH2); m/z ¼ 487 (M) for
stirred for ca. 15 min and the volume concentrated in vacuo
to ca. 1–2 cm3. Addition of diethyl ether (15 cm3) gave an
orange–brown solid which was collected by suction filtration
and dried in vacuo. Yield: 0.153 g, 87%. [{RuCl2(Z6-p-
1a. 31P: d ꢀ13.3; H: d 8.83 [4J(PH) 4.4] (CHimine), 7.95–6.83
1
i
MeC6H4 Pr)}2{PhSe(CH2)4N(CH2PPh2-m-P,P0)2}] 5b was
(arom. H), 3.47, 2.81, 1.57 (CH2); m/z ¼ 501 (M) for 1b.
prepared in an analogous manner (70%). Selected spectro-
scopic data: 31P: d 19.1; 1H: d 7.85–7.23 (arom. H), 3.70,
1.96, 1.55 (CH2) and additional resonances for Z6-p-
(Ph2PCH2)2N(CH2)3SePh 2a. A mixture of Ph2PCH2OH
(0.110 g, 0.509 mmol) and H2N(CH2)3SePh (0.064 g, 0.299
mmol) in chloroform (10 cm3) was stirred under a nitrogen
atmosphere for ca. 15 min. The solvent was evaporated to dry-
ness to give a yellow oil. Yield: 0.151 g, 83%. Selected NMR
data: 31P: d ꢀ28.3; 1H: d 7.38–7.20 (arom. H), 3.53 [2J(PH)
3.2], 2.93, 2.64, 1.69 (CH2); m/z ¼ 611 (M) for 2a.
i
MeC6H4 Pr at 5.06–4.95, 2.35, 1.68 and 0.84 for 5a. 31P: d
19.1; 1H: d 7.85–7.25 (arom. H), 3.67, 3.02, 1.67, 1.27
(CH2) and additional resonances for Z6-p-MeC6H4 Pr at d
i
5.05–4.93, 2.23, 1.65 and 0.83; m/z ¼ 1202 (M ꢀ Cl) for 5b.
[(AuCl)2{PhSe(CH2)3N(CH2PPh2-l-P,P0)2}] 6a. A CDCl3
(0.5 cm3) solution of [AuCl(tht)] (0.023 g, 0.0717 mmol) and
(Ph2PCH2)2N(CH2)3SePh (0.022 g, 0.0360 mmol) was moni-
tored by 31P{1H} NMR spectroscopy and showed 6a as the
only phosphorus containing species. Solid 6a was isolated
upon addition of diethyl ether (10 cm3) and collected by suc-
tion filtration. Yield: 0.021 g, 54%. Selected spectroscopic data:
(Ph2PCH2)2N(CH2)4SePh 2b. A mixture of Ph2PCH2OH
(0.390 g, 1.81 mmol) and H2N(CH2)4SePh (0.205 g, 0.900
mmol) in methanol (10 cm3) was stirred under a nitrogen
atmosphere at 50 ꢁC for 4 h. The solvent was evaporated to
dryness under reduced pressure, triturated with two portions
of cold methanol and dried in vacuo to give a yellow oil. Yield:
0.494 g, 88%. Selected NMR data: 31P: ꢀ28.2; H: 7.43–7.21
1
1
31P: d 16.3; H: d 7.68–7.25 (arom. H), 4.19, 2.96, 2.53, 1.46
(arom. H), 3.54 [2J(PH) 2.8], 2.78, 1.47 (CH2); m/z ¼ 625
(M) for 2b.
(CH2); nAuCl 329 cmꢀ1; m/z ¼ 1041 (M–Cl) for 6a. 31P: d
16.6; 1H: d 7.70–7.26 (arom. H), 4.20, 2.80, 2.65, 1.30, 1.22
(CH2); nAuCl 327 cmꢀ1; m/z ¼ 1055 (M ꢀ Cl) for 6b.
cis-[PtCl2{PhSe(CH2)3N(CH2PPh2-P,P0)2}] 3a. To a CH2Cl2
(10 cm3) solution of (Ph2PCH2)2N(CH2)3SePh (0.061 g, 0.100
mmol) was added [PtCl2(cod)] (0.037 g, 0.099 mmol). After
stirring the solution for ca. 15 min, the volume was concen-
trated in vacuo to ca. 1–2 cm3 and diethyl ether (20 cm3) added.
The white solid was collected by suction filtration and dried in
vacuo. An additional crop could be obtained from the filtrate.
Yield: 0.070 g, 81%. In a similar manner the following com-
plexes were prepared: cis-[PtCl2{PhSe(CH2)4N(CH2PPh2-P,
P0)2}] 3b (95%), cis-[PdCl2{PhSe(CH2)3N(CH2PPh2-P,P0)2}]
3c (92%) and cis-[PdCl2{PhSe(CH2)4N(CH2PPh2-P,P0)2}] 3d
(82%). Selected NMR and IR data: 31P: d ꢀ7.9 [1J(PtP)
3400]; 1H: d 7.84–20 (arom. H), 3.39 [3J(PtH) 38.1], 2.65,
2.41, 1.62 (CH2); nPtCl 316, 293 cmꢀ1; m/z ¼ 877 (M) for 3a.
31P: d ꢀ8.3 [1J(PtP) 3405]; 1H: d 7.82–7.22 (arom. H), 3.37
[3J(PtH) 37.2], 2.70, 2.53, 1.71, 1.40 (CH2); nPtCl 316, 293
cmꢀ1; m/z ¼ 891 (M) for 3b. 31P: d 8.6; 1H: d 7.87–7.23 (arom.
H), 3.34, 2.71, 2.43, 1.63 (CH2); nPdCl 291 cmꢀ1; m/z ¼ 766
cis-[(PdCl2)3{PhSe(CH2)3N(CH2PPh2)2-P,P,Se}2] 7. To a
stirred solution of [PdCl2(MeCN)2] (0.005 g, 0.019 mmol) in
CHCl3 (1 cm3) was added 3c (0.030 g, 0.038 mmol) as a solid
in one portion. After stirring the solution for ca. 15 min the
volume was concentrated in vacuo to ca. 1–2 cm3 and diethyl
ether (10 cm3) added. The solid was collected by suction filtra-
tion and dried in vacuo. Yield: 0.025 g, 75%. Selected spectro-
1
scopic data: 31P: d 8.6. H: d 7.88–7.38 (arom. H), 3.33, 2.71,
2.47, 1.61 (CH2); nPdCl 357, 292 cmꢀ1; m/z ¼ 1715 (M ꢀ Cl).
[PtCl{(2-Ph2P)C6H4C(H)=N(CH2)3SePh-P,N,Se}]BF4 8. To
a CH2Cl2 (10 cm3) suspension of Ag[BF4] (0.029 g, 0.149
mmol) was added [PtCl2{(2-Ph2P)C6H4C(H)=N(CH2)3SePh-
P,N}] (0.099 g, 0.132 mmol) and the mixture stirred in the dark
for 2 h. The AgCl was removed by filtration through a Celite
plug and the yellow solution evaporated to dryness. The resi-
due was taken up in CH2Cl2 (2 cm3) and addition of diethyl
ether (15 cm3) gave a pale yellow solid 8 which was collected
by suction filtration, washed with diethyl ether (5 cm3) and
1
(M ꢀ Cl) for 3c. 31P: d 8.2; H: d 7.87–7.26 (arom. H), 3.33,
2.74, 2.57, 1.74, 1.40 (CH2); nPdCl 292 cmꢀ1 for 3d.
New J. Chem., 2002, 26, 1402–1408
1403

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dried in vacuo. Yield: 0.088 g, 83%. Selected spectroscopic
data: 31P [CDCl3/(CH3)2SO]: d 7.6 [1J(PtP) 3427 Hz]; 1H
(CD3CN): d 8.43 [3J(PtH) 112] (CHimine), 7.96–7.27 (arom.
H), 4.13, 3.54, 1.91 (CH2); nCN 1619, nBF 1060, nPtCl 334
cmꢀ1; m/z ¼ 717 (M ꢀ BF4).
another half-occupied CHCl3 molecule is also present. The dis-
order in the Se-containing chain correlates with the disorder in
the solvent molecules such that the structure comprises a solid
solution of 4dꢂ2CHCl3 with 4dꢂ3CHCl3 , giving 4dꢂ2.5CHCl3 as
the overall composition.
Programs used were Bruker AXS SMART and SAINT for
diffractometer control and frame integration,27 Bruker
SHELXTL for structure solution, refinement and molecular
graphics28 and local programs.
X-Ray crystallography
Suitable crystals of 3b, 3cꢂCHCl3 , 4dꢂ2.5CHCl3 and 6a were
grown by vapour diffusion of diethyl ether into chloroform
solutions over several days. For 4b, suitable crystals were
obtained by slow diffusion of diethyl ether into dichloro-
methane solutions over several days. For 8, good quality crys-
tals were obtained by vapour diffusion of diethyl ether into
acetonitrile solutions over several days. All measurement were
made on a Bruker AXS SMART 1000 CCD area-detector dif-
fractometer, at 150 K, using graphite-monochromated Mo-Ka
CCDC reference numbers 190642–190647. See http://
www.rsc.org/suppdata/nj/b2/b204005k/ for crystallographic
files in CIF or other electronic format.
Results and discussion
Schiff base condensation reactions of (2-Ph2P)C6H4C(H)=O
with various amines has previously been reported and shown
to represent a useful entry to functionalised tertiary phosphine
ligands.1,29 We find that (2-Ph2P)C6H4C(H)=O reacts
smoothly with the primary amines H2N(CH2)nSePh (n ¼ 3,
4)22 in ethanol at 50 ꢁC to give, in high yields (as oils), the
new selenoether functionalised ligands 1a and 1b (eqn. (1)).
The purity of these compounds was ascertained from spectro-
scopic and MS studies (see Experimental section) and were
found to be sufficiently pure for their coordination chemistry
to be studied (see below). The 31P{1H} NMR spectra show sin-
gle resonances at ca. d(P) ꢀ13 (CDCl3) shifted marginally with
respect to that found for (2-Ph2P)C6H4C(H)=O [d(P) ꢀ11.6 (in
ꢁ
˚
radiation (l ¼ 0.71073 A) and narrow frame exposures (0.3 )
in o. Cell parameters were refined from the observed (o)
angles of all strong reflections in each data set. Intensities were
corrected semiempirically for absorption based on symmetery-
equivalent and repeated reflections. The structures were solved
by direct methods (Patterson synthesis for 4d and 6a) and
refined on F2 values for all unique data by full-matrix least-
squares. Table 1 gives further details. All non-hydrogen atoms
were refined anisotropically. Hydrogen atoms were included in
a riding model with Uiso set to be 1.2 times Ueq of the carrier
atom. For 3b there were clear indications that the data were
twinned, but no satisfactory twin law(s) could be established.
Four of the five largest residual peaks are close to the N atoms,
two in each molecule. However, these were not in chemically
reasonable positions attributable to a minor compound of a
different composition, nor could they be successfully refined
as partially occupied atoms. We therefore conclude that these
peaks are artifacts of the unmodelled twinning. There are two
molecules in the asymmetric unit, in one atom Se(1) is disor-
dered over two sites with relative occupancies 82.0:18.0(4)%.
For 4dꢂ2.5CHCl3 the end of the Se-containing chain, includ-
ing C(23), Se(1) and the terminal phenyl group, was disordered
over two sets of positions, modelled as equally occupied. Addi-
tionally, one CHCl3 solvent molecule is disordered over two
sets of equally occupied positions with one Cl atom common
to both. When one of these sets of positions is occupied,
1
CDCl3)]. Further confirmation came from H NMR spectro-
scopy which clearly showed, for (2-Ph2P)C6H4C(H)=O, the
absence of a doublet signal at d(H) 10.530 [C(H)=O proton].
By contrast an imine proton resonance at d 8.83 was observed
4
as a doublet as a result of J(PH) coupling (4.4 Hz). The E-
conformer was assigned by simple analogy with other imino-
phosphine based ligands bearing different functional motifs.1,29
We,17–20 and others,31 have shown that Ph2PCH2OH is a
versatile precursor for synthesising new tertiary phosphines
Table 1 Details of the X-ray data collections and refinements for compounds 3b, 3cꢂCHCl3 , 4b, 4dꢂ2.5CHCl3 , 6a and 8
Compound
3b
3cꢂCHCl3
4b
4dꢂ2.5CHCl3
6a
8
Empirical formula
C
36H37Cl2N
P2PtSe
C35H35Cl2NP2PdSeꢂ
CHCl3
907.21
C29H28Cl2
NPPtSe
766.44
C29H28Cl2NPPdSeꢂ
2.5CHCl3
976.17
C35H35Au2
Cl2NP2Se
1075.37
Trigonal
P32
C28H26BClF4
NPPtSe
803.78
M
Crystal system
Space group
890.56
Triclinic
¯
P1
Monoclinic
P21/c
Monoclinic
P21/c
Triclinic
¯
P1
Monoclinic
P21/c
˚
a/A
11.2388(7)
14.3914(8)
21.7918(13)
100.185(2)
90.251(2)
99.638(2)
3418.0(4)
4
14.6694(10)
11.6913(8)
22.9159(16)
90
19.9268(7)
10.3898(4)
26.4969(10)
90
10.2746(8)
14.3334(11)
14.3424(11)
98.698(2)
108.957(2)
100.683(2)
1911.5(3)
2
9.5384(4)
9.5384(4)
33.0881(16)
90
9.8693(7)
23.8471(17)
11.7404(8)
90
˚
b/A
˚
c/A
a/ꢁ
b/ꢁ
g/ꢁ
102.898(2)
90
92.509(2)
90
90
120
99.652(2)
90
3
˚
U/A
3831.0(5)
4
1.89
5480.5(4)
8
6.72
2607.1(2)
3
9.75
2724.0(3)
4
6.69
Z
m/mmꢀ1
Measured reflections
Independent
5.45
24506
11930 (0.0234)
2.17
15524
8565 (0.0331)
29211
7530 (0.0535)
47536
13305 (0.0325)
22423
8193 (0.0217)
23695
6526 (0.0447)
reflections (Rint
Reflections with
F2 > 2s(F2)
)
10135
5274
10564
6163
7867
4923
Final R,a Rw
0.033, 0.079
0.053, 0.155
0.025, 0.057
0.044, 0.121
0.018, 0.035
0.034, 0.082
b
a
b
2
R ¼ SkFo| ꢀ |Fck/S|Fo| based on observed data. Rw ¼ [S[w(Fo ꢀ Fc2)2]/S[w(Fo2)2]]1/2 based on all data.
1404
New J. Chem., 2002, 26, 1402–1408

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Table 2 Microanalytical data for compounds 3–8a
Analysis (%)
Compound
C
H
N
3ab
3bb
3cb
3dc
4a
64.85 (64.40)
47.35 (47.00)
50.90 (51.35)
50.90 (50.90)
44.75 (44.70)
45.80 (45.45)
50.30 (50.65)
49.40 (49.20)
52.90 (52.70)
50.05 (50.50)
39.00 (39.10)
39.05 (39.75)
47.60 (47.95)
42.00 (41.85)
4.00 (3.95)
3.90 (4.10)
4.35 (4.40)
4.45 (4.40)
3.80 (3.50)
3.65 (3.70)
4.20 (3.95)
3.95 (4.05)
4.90 (5.10)
5.15 (4.90)
3.20 (3.30)
3.35 (3.45)
4.05 (4.00)
3.30 (3.25)
1.65 (1.50)
1.55 (1.50)
1.90 (1.70)
1.70 (1.65)
1.85 (1.85)
1.65 (1.85)
2.10 (2.10)
1.80 (1.95)
1.15 (1.10)
0.95 (1.05)
1.25 (1.30)
1.25 (1.30)
1.55 (1.60)
1.60 (1.75)
4b
4c
4db
5ab
5bd
6a
6b
7
8
Scheme 1 (i) [MCl2(cod), 1 equiv. 2, CH2Cl2 (ii) [{RuCl(m-Cl)(Z6-p-
cymene)}2], 1 equiv. 2, CH2Cl2 or [AuCl(tht)], 0.5 equiv. 2, CH2Cl2
a
b
Calculated values in parentheses.
Contains 0.5 mol CH2Cl2 .
c
d
Contains 0.5 mol CHCl3 . Contains 1.0 mol CHCl3 .
by virtue of the reactive primary hydroxo group. Condensa-
tion of Ph2PCH2OH (2 equiv.) with H2N(CH2)nSePh (n ¼ 3,
4) gave (as oils) the new ditertiary phosphines (Ph2PCH2)2-
N(CH2)nSePh 2a (n ¼ 3) and 2b (n ¼ 4) containing a selo-
noether group in the ligand backbone (eqn. (2)). So far we
have been unable to isolate intermediates of the type
(Ph2PCH2)NH(CH2)nSePh bearing a single ‘‘Ph2PCH2’’ group
although we have observed, by 31P{1H} NMR, their transient
formation in solution [d(P) ca. ꢀ20]. The 31P chemical shifts
are comparable to (Ph2PCH2)2NPh [d(P) ꢀ21.3] and related
systems and in accord with bis substitution.31
moreover, in the case of the platinum(II) complexes, 1J(PtP)
was typically around 3400 Hz (for 3a, 3b) compared with ca.
1
3700 Hz (for 4a–4c). This former J(PtP) coupling compares
well with that found for [PtCl2(dppp)] [d(P) ꢀ5.5, 1J(PtP)
3409 Hz (CDCl3)] indicating a negligible difference between
N(R) and CH2 groups in the backbone of the ditertiary phos-
phine.
The X-ray structures of 3b (Fig. 1) and 3cꢂCHCl3 (Fig. 2)
have been determined with selected bond lengths and angles
given in Table 3. Both complexes display a cis configuration
with respect to the two phosphorus donors, the metal(II) centre
in a near square planar geometry [Cl(1)–Pt(1)–P(1) 86.03(5),
Cl(2)–Pt(1)–P(2) 89.19(5), Cl(1)–Pt(1)–Cl(2) 89.50(5), P(1)–
Pt(1)–P(2) 94.79(5)ꢁ and Cl(3)–Pt(2)–P(3) 86.96(5), Cl(4)–
Pt(2)–P(4) 88.91(5), Cl(3)–Pt(2)–Cl(4) 89.50(5) and P(3)–
Pt(2)–P(4) 94.70(5)ꢁ for the two independent molecules I
and II in 3b; Cl(2)–Pd(1)–P(2) 88.87(6), Cl(1)–Pd(1)–P(1)
89.09(6), Cl(1)–Pd(1)–Cl(2) 90.13(6) and P(1)–Pd(1)–P(2)
92.24(6)ꢁ for 3cꢂCHCl3]. The M–Cl and M–P bond distances
Reaction of either 1 equiv. of 1 or 2 with [MCl2(cod)]
(M ¼ Pd, Pt) gave the new complexes [MCl2(1)] 3a–3d or
[MCl2(2)] 4a, 4b respectively in high yields (Schemes 1 and 2).
The new complexes were characterised by 1H and 31P{1H}
NMR spectroscopy, IR (Experimental section) and micro-
analysis (Table 2). Downfield d(P) shifts were observed and
Fig. 1 X-Ray crystal structure of 3b showing one of the two indepen-
dent molecules. The second independent molecule has a different orien-
tation of the selenoether group. Both molecules have similar bond
lengths and angles. Hydrogen atoms omitted for clarity.
Scheme 2 (i) [MCl2(cod), 1 equiv. 1, CH2Cl2 (ii) Ag[BF4], CH2Cl2
New J. Chem., 2002, 26, 1402–1408
1405

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Fig. 3 X-Ray crystal structure of 4b showing one of the two indepen-
dent molecules. The second independent molecule has a different orien-
tation of the selenoether group. Both molecules have similar bond
lengths and angles. Most of the H-atoms omitted for clarity.
Fig. 2 X-Ray crystal structure of 3cꢂCHCl3 . Solvent molecule and
H-atoms omitted for clarity.
are unexceptional and compare well, in the case of 3cꢂCHCl3 ,
N(2)–Pt(2)–Cl(3) 91.31(8) and N(2)–Pt(2)–Cl(3) 91.31(8)ꢁ for
the two independent molecules I and II in 4b; [Cl(1)–Pd(1)–
Cl(2) 89.76(4), N(1)–Pd(1)–P(1) 86.94(9), N(1)–Pd(1)–Cl(1)
91.66(9) and P(1)–Pd(1)–Cl(2) 91.93(4)ꢁ for 4dꢂ2.5CHCl3].
The M–Cl distances are different as a consequence of the rela-
tive trans influences of N and P. Hence for 4dꢂ2.5CHCl3 the
Pd–Cl bond distances are 2.2816(10) (Cl trans to N) and
2.3911(11) A (Cl trans to P) whereas this difference is less pro-
nounced for 4b [2.2918(8) and 2.3021(9) (Cl trans to N);
˚
2.3698(8) and 2.3633(9) A (Cl trans to P)]. In 4b the coordina-
tion environment around each platinum centre is different i.e.
in I the five atoms (inclusive of Pt) are essentially planar
with those of [PdCl2{(Ph2PCH2)2NPh}].32 Furthermore the
˚
˚
long Mꢂ ꢂ ꢂN separation (av. 3.671 A for 3b; 3.775 A for
3cꢂCHCl3) indicates no significant bonding between these
two atoms. The conformation of the M–P–C–N–C–P six-
membered ring in 3cꢂCHCl3 is best described as an envelope
with N(1) out of the plane [mean plane Pd(1), P(1), P(2),
˚
C(1), C(2) ꢃ 0.152 A]. It is noteworthy that the pendant sele-
˚
noether group is clearly amenable to further coordination
chemistry.
The X-ray crystal structures of 4b (Fig. 3) and 4dꢂ2.5CHCl3
(Fig. 4) have been determined with selected bond lengths and
angles given in Table 4. Both structures show the presence of
a chelating iminophosphine ligand and two chloride ligands
with the metal(II) centre being in a near square planar geo-
metry [N(1)–Pt(1)–P(1) 87.07(7), Cl(1)–Pt(1)–Cl(2) 87.77(3),
˚
˚
(ꢃ0.043 A) whilst in II, the five atoms are much more distorted
(ꢃ0.152 A). By contrast, the coordination surrounding Pd in
˚
4dꢂ2.5CHCl3 is intermediate (ꢃ0.109 A) between that observed
for the two independent molecules in 4b. Within the M–P–C–
C–C–N six-membered rings the plane defined by C(13)–C(18)–
C(19) [or C(42)–C(47)–C(48)] is folded out of this plane with
respect to the N–M–P plane. This general conformation is pre-
sumably enforced by the presence of a more rigid phenylene
group in the backbone of the P,N-chelating ligand.
N(1)–Pt(1)–Cl(2)
91.03(7),
P(1)–Pt(1)–Cl(1)
and Cl(3)–Pt(2)–Cl(4) 88.70(3), P(2)–Pt(2)–Cl(4) 90.07(3),
94.19(3)ꢁ
ꢁ
˚
Table 3 Selected bond distances (A) and angles ( ) for compounds 3b,
3cꢂCHCl3 and 6a (equivalent parameters for independent molecules are
given in parentheses)
Ligands such as 1 can also adopt bridging coordination
modes by appropriate reaction with either [{RuCl(m-Cl)(Z6-
p-cymene)}2] or [AuCl(tht)]. The complexes 5 and 6 could be
3cꢂCHCl3
3b (M ¼ Pt)
(M ¼ Pd)
6a (M ¼ Au)
M(1)–P(1)
M(1)–P(2)
M(1)–Cl(1)
M(1)–Cl(2)
M(2)–Cl(2)
P(1)–C(1)
C(1)–N(1)
N(1)–C(2)
C(2)–P(2)
2.2269(14) [2.2269(14)]
2.2334(14) [2.2305(14)]
2.3482(14) [2.3604(13)]
2.3684(14) [2.3708(13)]
2.2459(17)
2.2409(17)
2.3580(17)
2.3697(16)
2.2335(9)
2.2347(9)
2.2903(9)
2.2979(9)
1.842(4)
1.480(4)
1.459(4)
1.845(3)
1.837(6) [1.829(5)]
1.437(7) [1.453(7)]
1.473(7) [1.465(7)]
1.829(6) [1.836(5)]
1.827(6)
1.478(8)
1.452(8)
1.840(6)
P(1)–M(1)–P(2)
P(1)–M(1)–Cl(1)
P(1)–M(1)–Cl(2)
Cl(1)–M(1)–P(2)
Cl(2)–M(1)–P(2)
Cl(2)–M(2)–P(2)
Cl(1)–M(1)–Cl(2)
M(1)–P(1)–C(1)
P(1)–C(1)–N(1)
C(1)–N(1)–C(2)
N(1)–C(2)–P(2)
C(2)–P(2)–M(1)
94.79(5) [94.70(5)]
86.03(5) [86.96(5)]
172.75(5) [172.08(5)]
177.88(5) [178.29(5)]
89.19(5) [88.91(5)]
92.24(6)
89.09(6)
169.99(6)
177.83(7)
88.87(6)
171.09(4)
178.13(3)
89.80(5) [89.50(5)]
116.2(2) [117.32(18)]
109.5(4) [111.6(4)]
111.0(4) [109.9(4)]
110.4(4) [112.0(4)]
117.18(18) [117.71(18)]
90.13(6)
118.2(2)
112.6(4)
109.4(5)
112.0(4)
118.8(2)
115.45(11)
110.5(2)
110.5(3)
Fig. 4 X-Ray crystal structure of 4dꢂ2.5CHCl3 . Disorder in the Se-
containing chain, solvent molecules and most of the H-atoms omitted
for clarity.
113.5(2)
111.25(11)
1406
New J. Chem., 2002, 26, 1402–1408

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ꢁ
˚
Table 4 Selected bond distances (A) and angles ( ) for compounds 4b,
4dꢂ2.5CHCl3and 8 (equivalent parameters for independent molecules
are given in parentheses)
a negligible shift in d(P) (7.6 cf. 5.1 for 4a) and a reduction
in 1J(PtP) of ca. 300 Hz, consistent with the change in the trans
ligand [PhSe(CH2)3N vs. Cl]. In addition, we observe a 2J(PSe)
of 163 Hz and in keeping with a trans disposition of P and Se
donor atoms. The 1H NMR spectrum shows an imine reso-
nance at d 8.43 flanked by 195Pt satellites [3J(PtH) 112 Hz].
Other supporting data are given in the Experimental section.
The X-ray structure of 8 (Table 4, Fig. 6(a)) clearly shows
the platinum(II) to be in a near square planar geometry
[Cl(1)–Pt(1)–Se(1) 83.69(4), N(1)–Pt(1)–P(1) 87.50(13), P(1)–
Pt(1)–Cl(1) 93.06(5), N(1)–Pt(1)–Se(1) 95.74(12)ꢁ] and coordi-
nated by P, N, Se and Cl donor centres (five atoms are essen-
4dꢂ2.5CHCl3
4b (M ¼ Pt)
(M ¼ Pd)
8 (M ¼ Pt)
M(1)–P(1)
M(1)–N(1)
M(1)–Cl(1)
M(1)–Cl(2)
N(1)–C(19)
M(1)–Se(1)
2.2100(8) [2.1992(9)]
2.047(3) [2.037(3)]
2.2918(8) [2.3633(9)]
2.3698(8) [2.3021(9)]
1.286(4) [1.278(4)]
2.2175(10)
2.054(3)
2.2407(14)
2.028(4)
2.3085(13)
2.3911(11)
2.2816(10)
1.279(5)
1.283(7)
2.4889(6)
˚
P(1)–M(1)–N(1)
P(1)–M(1)–Cl(1)
P(1)–M(1)–Cl(2)
N(1)–M(1)–Cl(1)
N(1)–M(1)–Cl(2)
Cl(1)–M(1)–Cl(2)
M(1)–N(1)–C(19)
N(1)–M(1)–Se(1)
P(1)–M(1)–Se(1)
Cl(1)–M(1)–Se(1)
87.07(7) [90.95(8)]
94.19(3) [171.37(4)]
177.63(3) [90.07(3)]
177.12(8) [91.31(8)]
91.03(7) [173.02(8)]
87.77(3) [88.70(3)]
125.8(2) [128.3(3)]
86.94(9)
172.64(4)
91.93(4)
91.66(9)
177.32(9)
89.76(4)
126.9(3)
87.50(13)
93.06(5)
tially planar i.e. ꢃ0.011 A). Surprisingly only one other
coordination environment33 of this type has been observed
previously.34 The Pt(1)–P(1) bond length [2.2407(14) A] is
˚
178.80(13)
slightly longer than that found in the related complex 4b
˚
[2.2100(8) and 2.1992(9) A] and broadly as expected for the
different trans influences of the Se and Cl donor atoms. The
127.1(4)
95.74(12)
176.74(4)
83.69(4)
˚
N(1)–C(19) bond distance [1.283(7) A] is similar to that
˚
observed in 4b [1.286(4) and 1.278(4) A], 4dꢂ2.5CHCl3
˚
[1.2789(5) A] and previously reported uncomplexed iminopho-
sphine ligands.1a,30 The tridentate ligand forms two stable six-
membered chelate rings. The two six-membered rings adopt
slight different ring geometries, the Pt(1)–P(1)–C(13)–C(18)–
C(19)–N(1) ring is ostensibly similar to that seen in 4b and
4dꢂ2.5CHCl3 , whilst the Pt(1)–N(1)–C(20)–C(21)–C(22)–Se(1)
ring adopts a boat conformation. Cations pair up (Fig. 6(b))
into weakly bound dimers via Ptꢂ ꢂ ꢂCl interactions
isolated in good yield, and in the case of 6a, an X-ray structure
determination undertaken (Fig. 5, Table 3). The structure con-
firms that 1a bridges two (AuCl) metal fragments and are anti
with respect to each other. The geometry about each gold(I)
centre is essentially linear [Cl(1)–Au(1)–P(1) 171.09(4); Cl(2)–
Au(2)–P(2) 178.13(3)ꢁ].
˚
A
weak aurophilic interaction
ꢁ
˚
[Pt(1)ꢂ ꢂ ꢂCl(1) 3.624 A, Pt(1)–Cl(1)ꢂ ꢂ ꢂPt(1A) 93.3 ].
[Au(1)ꢂ ꢂ ꢂAu(2) 3.408 A] is evident between adjacent gold cen-
The synthesis of new ‘‘hybrid’’ ligands bearing P/N/Se
or P2/Se donor sets has been demonstrated and represent
an extremely uncommon family of ligands bearing this
donor set combination. Our approach here is both simple,
˚
tres, the closest intermolecular Auꢂ ꢂ ꢂAu contact being 8.01 A.
A
preliminary study of the reaction of 3c with
[PdCl2(MeCN)2] in CHCl3 was undertaken to ascertain
whether the pendant Se group can be used in further com-
plexation. A solid was isolated in 75% yield and whose
NMR data are similar to those of 3c. The mass spectrum
and microanalytical data suggest a compound of composition
‘‘(PdCl2)3(2a)2’’ and IR spectroscopy indicates a cis configura-
tion at each palladium centre. Further studies are currently in
progess.
In order to probe whether intramolecular selonoether
coordination can be induced, reaction of 4a with approxi-
mately one equiv. of Ag[BF4] in dichloromethane gave the
cationic complex [PtCl{(2-Ph2P)C6H4C(H)=N(CH2)3SePh-
P,N,Se}]BF4 8 in 83%. The 31P{1H} NMR spectrum showed
Fig. 5 X-Ray crystal structure of 6a. Hydrogen atoms omitted for
clarity.
Fig. 6 (a) X-Ray crystal structure of 8 (b) weak dimer pair associa-
tion. The [BF4]ꢀ counter ion and most H-atoms omitted for clarity.
New J. Chem., 2002, 26, 1402–1408
1407

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16 W.-W. du Mont, S. Kubiniok, L. Lange, S. Pohl, W. Saak and
I. Wagner, Chem. Ber., 1991, 124, 1315.
17 S. E. Durran, M. B. Smith, A. M. Z. Slawin and J. W. Steed,
J. Chem. Soc., Dalton Trans., 2000, 2771.
18 S. J. Coles, S. E. Durran, M. B. Hursthouse, A. M. Z. Slawin and
M. B. Smith, New J. Chem., 2001, 25, 416.
19 S. E. Durran, M. B. Smith, A. M. Z. Slawin, T. Gelbrich, M. B.
Hursthouse and M. E. Light, Can. J. Chem, 2001, 79, 780.
20 M. B. Smith and M. R. J. Elsegood, Tetrahedron Lett., 2002, 43,
1299.
reproducible and permits a facile route to reasonable quanti-
ties of these ligands. In preliminary studies their ligating ability
has been demonstrated to give complexes broadly as expected.
Halide abstraction was found to induce complexation of the
selenoether group affording a P,N,Se-terdentate bound ligand.
We are presently investigating the use of complexes such as 3–6
as ‘‘metalloligands’’ for preparing new homo and hetero-
nuclear metal complexes. Further studies are in progress and
will be reported in due course.
21 (a) E. Shirakaw and T. Hiyama, J. Organomet. Chem., 1999, 576,
169; (b) K. R. Reddy, K. Surekha, G.-H. Lee, S.-M. Peng and
S.-T. Liu, Organometallics, 2000, 19, 2637; (c) E. K. van den
Beuken, W. J. J. Smeets, A. L. Spek and B. L. Feringa, Chem. Com-
Acknowledgements
mun., 1998, 223; (d ) R. E. Rulke, V. E. Kaasjager, P. Wehman, C. J.
¨
We should like to thank the EPSRC mass spectrometry service
at Swansea. Johnson Matthey are gratefully acknowledged for
loans of precious metals.
Elsevier, P. W. N. M. van Leeuwen, K. Vrieze, J. Fraanje,
K. Goubitz and A. L. Spek, Organometallics, 1996, 15, 3022; (e)
P. Pelagatti, A. Bacchi, M. Carcelli, M. Costa, A. Fochi, P. Ghidini,
E. Leporati, M. Masi, C. Pelizzi and G. Pelizzi, J. Organomet.
Chem., 1999, 583, 94; ( f ) T. Fukuda, A. Takehara and M. Iwao,
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Y. Honda, E. Shirakawa and T. Hiyama, Chem. Commun., 2001,
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