Square-planar metal(II) complexes containing ester functionalised bis(phosphino)amines: Mild P-N methanolysis and Carene-H cyclometallation

Article abstract of DOI:10.1016/j.jorganchem.2011.11.003

The synthesis of three new ester functionalised bis(phosphino)amines Ph₂PN{R}PPh₂ [R = C₆H₄(3-CO ₂Me) 1a; C₆H₃(3,5-CO₂Me)₂ 1b; C₆H₄(4-CO₂Me) 1c] upon stoichiometric reaction of Ph₂PCl and the appropriate H₂N{R} in Et ₂O is described. Reaction of 1 equiv. of 1a-c with MCl ₂(cod) (M = Pt, Pd) in CH₂Cl₂ afforded the dichlorometal(II) complexes PtCl₂(1a) 2a, PtCl₂(1b) 2b, PtCl₂(1c) 2c and PdCl₂(1b) 2'b respectively. The corresponding dibromo (and diiodo) platinum(II) complexes 3b (and 4b) were synthesised, in >80% isolated yields, from PtBr₂(cod) or PtI ₂(cod). When a suspension of 2b in MeOH was stirred at r.t. for ca. 16 h the mixed complex cis-PtCl₂[Ph₂PNH{R}](Ph ₂POMe) 5a [R = C₆H₃(3,5-CO₂Me) ₂] was cleanly generated. Metathesis of 5a using excess NaBr or NaI in MeOH/acetone afforded cis-PtBr₂[Ph₂PNH{R}](Ph ₂POMe) 5b or cis-PtI₂[Ph₂PNH{R}](Ph ₂POMe) 5c. Methanolysis of PtCl₂(1a) 2a at ambient temperature afforded, in low yield (18%), the regiospecific P,C-orthometallated complex cis-PtCl[Ph₂PNH{C₆H₃(3-CO ₂Me)}](Ph₂POMe) 6. We speculate the C-H activated complex 6 is obtained via initial formation of cis-PtCl₂[Ph ₂PNH{C₆H₄(3-CO₂Me)}](Ph ₂POMe) 7. A similar observation was also found using 2c whereupon examination of the isolated solid, by ³¹P{¹H} NMR spectroscopy, revealed formation of three complexes namely orthometallated cis-PtCl[Ph₂PNH{C₆H₃(4-CO₂Me)}] (Ph₂POMe) 9, cis-PtCl[Ph₂PNH{C₆H ₄(4-CO₂Me)}](Ph₂POMe) 10 and cis-PtCl ₂(Ph₂POMe)₂ 8. All new compounds reported here have been characterised by multinuclear NMR and IR spectroscopy, microanalysis and in six cases by single crystal X-ray crystallography. The X-ray structure of cis-PtCl[Ph₂PNH{C₆H₃(3-CO₂Me)}] (Ph₂POMe) 6 revealed selective C-H cycloplatination at the 6-position (as opposed to the 2-position) of the N-arene ring.

Full text of DOI:10.1016/j.jorganchem.2011.11.003

Journal of Organometallic Chemistry 699 (2012) 39e47
Contents lists available at SciVerse ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Square-planar metal(II) complexes containing ester functionalised bis(phosphino)
amines: Mild PꢀN methanolysis and CareneꢀH cyclometallation
,
a
b
c
Kirsty G. Gawa, Martin B. Smith a , John B. Wright , Alexandra M.Z. Slawin , Simon J. Coles ,
*
Michael B. Hursthouse c, Graham J. Tizzard c
a Department of Chemistry, Loughborough University, Loughborough, Leics, LE11 3TU, UK
b School of Chemistry, University of St. Andrews, St. Andrews, Fife, KY16 9ST, UK
c EPSRC National Crystallography Service, School of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
The synthesis of three new ester functionalised bis(phosphino)amines Ph2PN{R}PPh2 [R ¼ C6H4(3-
CO2Me) 1a; C6H3(3,5-CO2Me)2 1b; C6H4(4-CO2Me) 1c] upon stoichiometric reaction of Ph2PCl and the
appropriate H2N{R} in Et2O is described. Reaction of 1 equiv. of 1aꢀc with MCl2(cod) (M ¼ Pt, Pd) in
CH2Cl2 afforded the dichlorometal(II) complexes PtCl2(1a) 2a, PtCl2(1b) 2b, PtCl2(1c) 2c and PdCl2(1b)
2`b respectively. The corresponding dibromo (and diiodo) platinum(II) complexes 3b (and 4b) were
synthesised, in >80% isolated yields, from PtBr2(cod) or PtI2(cod). When a suspension of 2b in MeOH was
stirred at r.t. for ca. 16 h the mixed complex cis-PtCl2[Ph2PNH{R}](Ph2POMe) 5a [R ¼ C6H3(3,5-CO2Me)2]
was cleanly generated. Metathesis of 5a using excess NaBr or NaI in MeOH/acetone afforded cis-
PtBr2[Ph2PNH{R}](Ph2POMe) 5b or cis-PtI2[Ph2PNH{R}](Ph2POMe) 5c. Methanolysis of PtCl2(1a) 2a at
ambient temperature afforded, in low yield (18%), the regiospecific P,C-orthometallated complex cis-PtCl
[Ph2PNH{C6H3(3-CO2Me)}](Ph2POMe) 6. We speculate the CꢀH activated complex 6 is obtained via
initial formation of cis-PtCl2[Ph2PNH{C6H4(3-CO2Me)}](Ph2POMe) 7. A similar observation was also
found using 2c whereupon examination of the isolated solid, by 31P{1H} NMR spectroscopy, revealed
formation of three complexes namely orthometallated cis-PtCl[Ph2PNH{C6H3(4-CO2Me)}](Ph2POMe) 9,
cis-PtCl[Ph2PNH{C6H4(4-CO2Me)}](Ph2POMe) 10 and cis-PtCl2(Ph2POMe)2 8. All new compounds re-
ported here have been characterised by multinuclear NMR and IR spectroscopy, microanalysis and in six
cases by single crystal X-ray crystallography. The X-ray structure of cis-PtCl[Ph2PNH{C6H3(3-
CO2Me)}](Ph2POMe) 6 revealed selective CꢀH cycloplatination at the 6-position (as opposed to the 2-
position) of the N-arene ring.
Received 22 September 2011
Received in revised form
26 October 2011
Accepted 1 November 2011
Keywords:
Cyclometallation
Metathesis
Phosphine ligands
Square-planar complexes
X-ray crystallography
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
bearing one (or more) PꢀN bonds have recently been shown to
undergo sp2 or sp3 CꢀH cyclometallation at Ru, Rh, Ir, Ni, Pd and Pt
Cyclometallated complexes represent an important class of
compound widely encountered in modern organometallic and
coordination chemistry [1]. Various examples of CꢀH activated (sp2
or sp3) achiral [2,3] or chiral [4] metal complexes have been re-
ported and find numerous applications in areas ranging from
organic transformations [3,5], directed self-assembly [6], catalysis
[7], chemical sensing [8] and as luminescent materials [9].
Phosphorus based compounds such as tertiary phosphines [10],
phosphinites [11], phosphites [12], iminophosphoranes [3,13] and
PCP-pincer ligands [14] have widely been studied in a range of CꢀH
activation processes. In contrast trivalent phosphorus ligands
metal centres affording bidentate [15], tridentate [16] or tetra-
dentate [17] carbometallated complexes. We have demonstrated in
previous work that functionalised (phosphino)amines undergo
thermally induced orthometallation at PtII and RhIII metal centres
affording rare examples of thermally stable MꢀPꢀNꢀCareneꢀCarene
five-membered metallacycles [15e]. In this work we wished to
explore whether chelating bis(phosphino)amines of the type
(Ph2P)2N{R} would themselves undergo CꢀH metallation, a reac-
tion that has previously been observed for (Ph2P)2CH2 [1]. We
report here the synthesis of three bis(phosphino)amines bearing
one (or two) eCO2Me groups and a brief survey of their coordina-
tion chemistry at PdII and PtII metal centres. A general feature of
(phosphino)amine chemistry is their air/moisture sensitivity due to
the reactive nature of the heterolytic PꢀN bond [18]. We demon-
strate here the selective methanolysis of a PꢀN bond [19] for some
* Corresponding author. Tel.: þ44 (0)1509 222553; fax: þ44 (0)1509 223925.
E-mail address: m.b.smith@lboro.ac.uk (M.B. Smith).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.11.003

40
K.G. Gaw et al. / Journal of Organometallic Chemistry 699 (2012) 39e47
of these strained four-membered ester functionalised bis(phos-
phino)amine complexes and furthermore disclose a facile CꢀH
bond activation under remarkably mild conditions. Six single
crystal X-ray structure determinations have been undertaken.
2.3.2. PtCl2(1a) 2a and complexes 2b, 2c, 2`b, 3b, 4b
To a CH2Cl2 (10 mL) solution of PtCl2(cod) (0.095 g, 0.254 mmol)
was added 1a (0.132 g, 0.254 mmol) as a solid in one portion. The
pale yellow solution was stirred for 20 min and the volume
concentrated to w1 mL under reduced pressure. Addition of Et2O
(30 mL) gave a solid which was collected by suction filtration,
washed with Et2O (10 mL) and dried in vacuo. Yield: 0.191 g, 96%.
Selected data for 2a: 31P{1H} NMR (CDCl3): 21.4 ppm, 1JPtP 3334 Hz.
2. Experimental
2.1. Materials
1H NMR:
d
7.90e6.67 (m, 24H, arom. H), 3.75 (s, 3H, CO2Me). FTꢀIR:
nCO 1724, nPtCl 314, 292 cmꢀ1. Found C, 49.19; H, 3.59; N, 1.53%.
C32H27NO2P2PtCl2 (785.5) requires C, 48.93; H, 3.47; N, 1.78%. In
a similar manner the following dihalometal(II) complexes were
synthesised using PtCl2(cod) (for 2b, 2c), PdCl2(cod) (for 2`b),
PtBr2(cod) (for 3b) or PtI2(cod) (for 4b): Selected data for 2b (99%
Standard Schlenk techniques were used for the syntheses
of ligands 1aꢀc whilst all other reactions were performed
under aerobic conditions using previously distilled solvents
unless otherwise stated. The compounds H2NC6H4(3-CO2Me),
H2NC6H4(4-CO2Me) and H2NC6H3(3,5-CO2Me)2 were obtained
from commercial suppliers and used directly. The complexes
MX2(cod) (M ¼ Pt, Pd; X ¼ Cl, Br, I) were prepared according to
literature methods [20].
isolated yield): 31P{1H} NMR (CDCl3): 22.5 ppm, JPtP 3339 Hz. 1H
1
NMR:
d
8.39e7.35 (m, 23H, arom. H), 3.78 (s, 6H, CO2Me). 195Pt
NMR: ꢀ4056 ppm. FTꢀIR: nCO 1733,1720, nPtCl 307, 290 cmꢀ1. Found
C, 48.16; H, 3.61; N, 1.63%. C34H29NO4P2PtCl2 (843.5) requires C,
48.41; H, 3.47 N, 1.66%. Selected data for 2c (86% isolated yield): 31P
{1H} NMR (CDCl3): 21.3 ppm, JPtP 3330 Hz. 1H NMR:
d 7.88e6.57
2.2. Instrumentation
1
(m, 24H, arom. H), 3.83 (s, 3H, CO2Me). FTꢀIR: nCO 1721, nPtCl 307,
290 cmꢀ1. Found C, 48.98; H, 3.55; N, 1.92%. C32H27NO2P2PtCl2
(785.5) requires C, 48.93; H, 3.47; N, 1.78%. Selected data for 2`b
(91% isolated yield): 31P{1H} NMR (CDCl3): 36.1 ppm. 1H NMR:
Infrared spectra were recorded as KBr pellets in the range
4000ꢀ200 cmꢀ1 on
a PerkineElmer System 2000 Fourier-
transform spectrometer, 1H NMR spectra (250 or 400 MHz) were
recorded on a Bruker AC250 or DPX-400 FT spectrometer with
d
8.38e7.44 (m, 23H, arom. H), 3.79 (s, 6H, CO2Me). FTꢀIR: nCO 1733,
1720, nPdCl 314, 296 cmꢀ1. Found C, 53.71; H, 4.04; N, 1.83%.
chemical shifts (d) in ppm to high frequency of external Si(CH3)4
and coupling constants (J) in Hz, 31P{1H} NMR spectra (36.2 MHz,
C34H29NO4P2PdCl2 (754.8) requires C, 54.10; H, 3.88; N, 1.86%.
Selected data for 3b (89% isolated yield): 31P{1H} NMR (CDCl3):
101.3 or 162.0 MHz) were recorded either on a Jeol FX90Q, Bruker
21.3 ppm, JPtP 3260 Hz. 1H NMR:
d 8.37e7.37 (m, 23H, arom. H),
AC250 or DPX-400 FT spectrometer with chemical shifts (
d) in ppm
1
to high frequency of external 85% H3PO4. All 195Pt{1H} NMR spectra
(53.7 MHz) were recorded on a Bruker AC250 FT NMR spectrometer
3.78 (s, 6H, CO2Me). FTꢀIR: nCO 1733, 1721 cmꢀ1. Found C, 44.01; H,
3.32; N, 1.36%. C34H29NO4P2PtBr2 (932.4) requires C, 43.79; H, 3.14;
N, 1.50%. Selected data for 4b (85% isolated yield): 31P{1H} NMR
with
d referenced to external H2PtCl6 (in D2O/HCl). NMR spectra
(CDCl3): 17.4 ppm, JPtP 3066 Hz. 1H NMR:
d 8.30e7.32 (m, 23H,
were measured in CDCl3 unless otherwise stated. Elemental anal-
yses (PerkineElmer 2400 CHN Elemental Analyzer) were per-
formed by the Loughborough University Analytical Service within
the Department of Chemistry.
1
arom. H), 3.74 (s, 6H, CO2Me). FTꢀIR: nCO 1728 cmꢀ1. Found C, 39.42;
H, 2.78; N, 1.30%. C34H29NO4P2PtI2 (1026.4) requires C, 39.78; H,
2.85; N, 1.36%.
2.3. Syntheses
2.3.3. cis-PtCl2[Ph2PNH{C6H3(3,5-CO2Me)2}](Ph2POMe) 5a and
complexes 5b, 5c, 5d
2.3.1. Ph2PN{C6H4(3-CO2Me)}PPh2 1a and bis(phosphino)amines
1b, 1c
A suspension of 2b (0.218 g, 0.258 mmol) in MeOH (60 mL)
was stirred at ambient temperature for approx. 16 h. The solid was
filtered under reduced pressure, washed with MeOH (8 mL) and
dried in vacuo. Yield: 0.178 g, 79%. Selected data for 5a: 31P{1H}
To a stirred suspension of H2N{C6H4(3-CO2Me)} (0.840 g,
5.56 mmol) in NEt3 (2.559 g, 25.3 mmol) and Et2O (100 mL) was
added Ph2PCl (2.800 g, 12.7 mmol) in Et2O (20 mL) dropwise over
20 min whilst the temperature was maintained at approx. 0 ꢁC. The
mixture was stirred at ambient temperature for w7 d and the
solvent evaporated to dryness under reduced pressure. After
addition of degassed distilled water (70 mL), the solid was collected
by suction filtration and washed with hexane (50 mL) and absolute
EtOH (50 mL) to afford 1a. Yield: 2.493 g, 85%. Selected data for 1a:
1
1
NMR (CDCl3): 81.4 ppm, JPtP 4332 Hz; 30.1 ppm, JPtP 3960 Hz;
2
2JPP 16 Hz 1H NMR:
d 8.33 (d, JPH 10.5 Hz, 1H, NH), 8.06e7.33 (m,
3
23H, arom. H), 3.80 (s, 6H, CO2Me), and 2.81 (d, JPH 11.5 Hz, 3H,
OMe). 195Pt NMR: ꢀ4315 ppm. FTꢀIR (KBr): nNH 3239, nCO 1732,
1725, nPtCl 316, 284 cmꢀ1. Found C, 48.00; H, 3.61; N, 1.58.
C35H33NO5P2PtCl2 (875.6) requires C, 48.01; H, 3.81; N, 1.60%. The
platinum(II) complexes 5b (98% isolated yield) and 5c (96% iso-
lated yield) were synthesised by metathesis of 5a with either NaBr
or NaI in MeOH/acetone. Selected data for 5b: 31P{1H} NMR
31P{1H} NMR (CDCl3): 69.0 ppm. 1H NMR:
d 7.64e6.83 (m, 24H,
arom. H), 3.74 (s, 3H, CO2Me). FTꢀIR: nCO 1722 cmꢀ1. FABꢀMS: m/z
519 [Mþ]. Found C, 72.57; H, 5.27; N, 2.62. C32H27NO2P2$0.5H2O
(528.5) requires C, 72.71; H, 5.35; N, 2.65%. In a similar manner
Ph2PN{C6H3(3,5-CO2Me)2}PPh2 (1b) and Ph2PN{C6H4(4-CO2Me)}
PPh2 (1c) were prepared in 82% and 58% isolated yields respec-
tively. Selected data for 1b: 31P{1H} NMR (CDCl3): 69.0 ppm. 1H
1
1
2
(CDCl3): 80.6 ppm, JPtP 4268 Hz; 30.6 ppm, JPtP 3934 Hz; JPP
21 Hz. 1H NMR:
d
8.15 (d, 2JPH 10.6 Hz, 1H, NH), 8.08e7.32 (m, 23H,
3
arom. H), 3.81 (s, 6H, CO2Me) and 2.80 (d, JPH 11.6 Hz, 3H, OMe).
195Pt NMR: ꢀ4556 ppm. FTꢀIR (KBr): nNH 3233, nCO 1726 cmꢀ1
.
FABꢀMS: m/z 884 [MꢀBr]. Found C, 42.73; H, 3.11; N, 1.31.
C35H33NO5P2PtBr2$0.25CH2Cl2 (985.7) requires C, 42.95; H, 3.40;
N, 1.42%. Selected data for 5c: 31P{1H} NMR (CDCl3): 80.4 ppm,
NMR:
d
7.89e7.24 (m, 23H, arom. H), 3.74 (s, 3H, CO2Me). FTꢀIR: nCO
1727 cmꢀ1. FABꢀMS: m/z 578 [Mþ]. Found C, 69.63; H, 5.06; N, 2.53.
C34H29NO4P2$0.5H2O (586.6) requires C, 69.62; H, 5.17; N, 2.39%.
Selected data for 1c: 31P{1H} NMR (CDCl3): 68.5 ppm. 1H NMR:
1JPtP 4110 Hz; 29.9 ppm, JPtP 3789 Hz; JPP 9 Hz. 1H NMR:
1
2
d
8.08e7.32 (m, 24H, arom. H and NH), 3.81 (s, 6H, CO2Me) and
3
d
7.66e6.77 (m, 24H, arom. H), 3.83 (s, 3H, CO2Me). FTꢀIR: nCO
2.79 (d, JPH 11.3 Hz, 3H, OMe). 195Pt NMR: ꢀ5074 ppm. FTꢀIR
(KBr): nNH 3194, nCO 1725 cmꢀ1. FABꢀMS: m/z 931 [MꢀI]. Found C,
40.06; H, 3.27; N, 1.25. C35H33NO5P2PtI2 (1058.5) requires C, 39.71;
H, 3.15; N, 1.32%. Selected data for 5d: 31P{1H} NMR (CDCl3): 108.2,
1717 cmꢀ1. FABꢀMS: m/z 536 [M þ O]. Found C, 72.65; H, 5.41; N,
2.63. C32H27NO2P2$0.5H2O (528.5) requires C, 72.71; H, 5.35; N,
2.65%.

K.G. Gaw et al. / Journal of Organometallic Chemistry 699 (2012) 39e47
41
2
2
3
50.8 ppm, JPP 24 Hz. 1H NMR:
d
8.36 (d, JPH 12.3 Hz, 1H, NH),
10.6 Hz, 1H, NH), 3.72 (s, 3H, CO2Me) and 2.77 (d, JPH 11.6 Hz,
3H, OMe).
8.02e7.32 (m, 23H, arom. H), 3.76 (s, 6H, CO2Me), and 2.76 (d, 3JPH
11.3 Hz, 3H, OMe). FTꢀIR (KBr): nNH 3205, nCO 1732, 1726, nPdCl 317,
285 cmꢀ1
obtained.
. An analytically pure sample of 5d could not be
2.4. X-ray crystallography
Crystals of 2a$0.75CHCl3, suitable for X-ray crystallography, were
grown over several days by allowing Et2O to diffuse slowly into
a CDCl3 solution. Suitable crystals of 4b were prepared upon vapour
diffusion of diethyl ether into a CDCl3 solution of PtI2(cod) and Ph2PN
{C6H4(3-CO2Me)}PPh2 over the course of several days. Suitable crys-
tals of 5a$CHCl3 or 5c$CH2Cl2 were obtained by slow diffusion of Et2O
into a CDCl3/CH2Cl2 (for 5a) or CH2Cl2 (for 5c) solution whereas
crystals of 6 were obtained upon allowing a CH3OH filtrate to stand.
Crystals of 9$CHCl3$CH3OH were grown byallowing CH3OH to diffuse
slowly into a CDCl3 solution of a mixture of 8ꢀ10.
2.3.4. cis-PtCl[P,C-Ph2PNH{C6H3(3-CO2Me)}](Ph2POMe) 6
A suspension of 2a (0.099 g, 0.126 mmol) in MeOH (15 mL) was
stirred at ambient temperature for 27 h. Unreacted starting mate-
rial was removed by suction filtration and the solid washed with
a small portion of MeOH (5 mL) to give 2a (0.072 g recovered). The
methanol filtrate was left to slowly concentrate over 14 d yielding
a small crop of pale yellow crystals. Yield: 0.018 g, 18%. Selected
1
data for 6: 31P{1H} NMR (CDCl3): 117.3 ppm, JPtP 2292 Hz;
2
71.7 ppm, 1JPtP 4421 Hz; JPP 20 Hz. 1H NMR:
d 8.39e7.29 (m, 23H,
2
3
arom. H), 4.73 (d, JPH 2.7 Hz, JPtH 86 Hz, 1H, NH), 3.76 (s, 3H,
CO2Me) and 2.85 (d, 3JPH 11.1 Hz, 3H, OMe). FTꢀIR (KBr): nOH 3413,
nNH 3310, nCO 1696 cmꢀ1. Found C, 49.95; H, 3.88; N, 1.86.
C33H30NO3P2PtCl$CH3OH (813.1) requires C, 50.22; H, 4.22; N,
1.72%.
Details of the crystal data for 2a$0.75CHCl3, 4b, 5a$CHCl3,
5c$CH2Cl2, 6 and 9$CHCl3$CH3OH along with a summary of data
collection parameters are given in Table 1. Measurements for
2a$0.75CHCl3 and 5a$CHCl3 were determined using a Rigaku AFC7S
diffractometer with graphite-monochromated (Mo-Ka) radiation
(
l
¼ 0.71073 Å) and
u scans. Empirical absorption corrections
2.3.5. cis-PtCl[P,C-Ph2PNH{C6H3(4-CO2Me)}](Ph2POMe) 9
(DIFABS) [21] were applied. The structures were solved by the
heavy-atom method [22] and all of the non-hydrogen atoms
refined anisotropically. The H on N(1) in 5a$CHCl3 was located from
A suspension of 2c (0.032 g, 0.041 mmol) was heated under
reflux in MeOH (15 mL) for 16 h. The solvent was removed in
vacuo and the resulting residue examined by 31P{1H} NMR spec-
troscopy. The residue was resuspended in MeOH (15 mL) and
heated under reflux for a further 68 h. The solvent was removed in
vacuo, CH2Cl2 (1 mL) added and an off-white solid (0.035 g) iso-
lated by precipitation with Et2O (30 mL). Three PtII complexes
were observed, the major species present were identified as 9 and
10 along with a trace amount of 8. Selected spectroscopic data for
9: 31P{1H} NMR (CDCl3): 117.5 ppm, 1JPtP 2314 Hz; 72.7 ppm, 1JPtP
a
DF map and allowed to refine isotropically with no distance
restraint. All other H atoms were idealised and fixed (CꢀH 0.95 Å).
No additional constraints or restraints were applied. Refinement
was by full-matrix least-squares methods. Calculations were per-
formed using TEXSAN [23].
Data were collected (for 4b and 6) using a Nonius
detector diffractometer mounted at the window of a rotating
molybdenum anode. scans were employed such that 95% of the
unique data were recorded at least once. Data collection and pro-
cessing were carried out using the programs COLLECT [24], DENZO
[25], and maXus [26] and an empirical absorption correction was
applied using SORTAV [27]. The structures were solved via direct
methods [28] and refined by full-matrix least-squares [29] on F2.
k CCD area
U
2
2
3
4434 Hz; JPP 17.6 Hz. 1H NMR:
d 8.94 (dt, JPH 7.7 Hz, JPtH 41 Hz,
1H, arom. H), 4.91 (d, 2JPH 3.2 Hz, 3JPtH 86 Hz, 1H, NH), 3.73 (s, 3H,
CO2Me) and 2.87 (d, 3JPH 11.2 Hz, 3H, OMe). Selected spectroscopic
data for 10: 31P{1H} NMR (CDCl3): 80.9 ppm, JPtP 4337 Hz;
1
28.7 ppm, JPtP 3950 Hz; JPP 13.2 Hz. 1H NMR:
d 8.29 (d, JPH
1
2
2
Table 1
Crystallographic data for 2a$0.75CHCl3, 4b, 5a$CHCl3, 5c$CH2Cl2, 6 and 9$CHCl3$CH3OH.
Compound
2a$0.75CHCl3
32.75H27.75Cl4.25NO2P2Pt
875.00
Monoclinic
P21/n
8.792(4)
25.034(4)
16.521(4)
4b
5a$CHCl3
5c$CH2Cl2
6
9$CHCl3$CH3OH
Empirical Formula
Formula weight
Crystal system
Space group
a [Å]
C
C32H27I2NO2P2Pt
968.38
Monoclinic
P21/n
9.2343(18)
19.414(4)
18.236(4)
C36H34Cl5NO5P2Pt
994.92
Monoclinic
P21/n
9.2043(3)
15.2574(5)
27.4992(9)
C36H35Cl2I2NO5P2Pt
1143.38
Triclinic
Pꢀ1
C33H30ClNO3P2Pt
781.06
Monoclinic
P21/c
10.647(2)
17.517(4)
16.715(3)
C35H35Cl4NO4P2Pt
932.47
Monoclinic
P21/c
13.6757(5)
11.7451(4)
23.2206(16)
9.583(4)
15.294(6)
15.682(7)
113.982(7)
105.088(4)
97.402(5)
1954.4(14)
2
b [Å]
c [Å]
a
b
g
ꢀ[]
ꢀ[]
ꢀ[]
98.34(2)
97.67(3)
92.6590(10)
105.06(3)
105.299(7)
Volume [Å3]
3597.8(19)
4
3239.9(11)
4
3857.7(2)
4
3010.3(10)
4
3597.6(3)
4
Z
l
0.71073
293(2)
1.615
0.71073
150(2)
1.985
0.71073
293(2)
1.713
0.71073
93(2)
1.943
5.429
Prism; yellow
0.10 ꢂ 0.05 ꢂ 0.03
2.26e25.34
12,433
0.71073
150(2)
1.723
0.71073
100(2)
1.722
T/K
Density (calc.) [Mg/m3]
Absorption coeff. [mmꢀ1
Crystal habit and colour
Crystal size [mm3]
]
4.334
6.364
4.109
4.892
4.326
Plate; colourless
0.70 ꢂ 0.30 ꢂ 0.14
2.62e25.00
6786
Needle; yellow
0.22 ꢂ 0.04 ꢂ 0.04
3.06e27.50
29,864
Tablet; colourless
0.20 ꢂ 0.10 ꢂ 0.08
1.48e23.25
16,528
Plate; colourless
0.40 ꢂ 0.10 ꢂ 0.03
3.01e27.47
34,591
Plate; colourless
0.04 ꢂ 0.03 ꢂ 0.01
3.09e27.48
33,376
q
range ꢀ[]
Reflections collected
Independent reflections
6349
7387
5527
6891
6881
8243
[Rint ¼ 0.0442]
[Rint ¼ 0.0610]
[Rint ¼ 0.0301]
[Rint ¼ 0.0719]
[Rint ¼ 0.0603]
[Rint ¼ 0.0498]
Completeness (%)
No. of parameters
99.9
99.4
99.7
96.6
99.7
99.9
399
0.059, 0.157
363
0.035, 0.063
456
0.033, 0.073
449
0.076, 0.184
373
0.036, 0.108
430
0.037, 0.091
Final Ra, Rw
b
P
P
a
R ¼ jjFojꢀjFcjj/ jFoj.
P
P
b
wR2 ¼ [ [w(F2oꢀF2c)2]/ [w(Fo2)2]]1/2
.

42
K.G. Gaw et al. / Journal of Organometallic Chemistry 699 (2012) 39e47
Non-hydrogen atoms were refined anisotropically and hydrogen
atoms were treated using a riding model.
Data were collected (for 5c$CH2Cl2) using a Rigaku 007 gener-
ator with a Mercury detector on Mo radiation.
The crystallographic data collection for 9$CHCl3$CH3OH was
performed using a Rigaku AFC12 Kappa 3-circle CCD diffractometer
with Mo-Ka radiation
(l
¼
0.71073 Å) controlled by the
CrystalClear-SM Expert 2.0 [30] software package and an Oxford
Cryosystem N2 open flow cryostat at 100(2) K. The data were pro-
cessed and semi-empirical absorption corrections were applied
using FS_PROCESS [31] in CrystalClear-SM Expert 2.0. The struc-
tures were solved by charge flipping and refined by full-matrix
least-square procedures on F2 using SUPERFLIP [32] and SHELXL-
97 [33] respectively. All non-hydrogen atoms were refined aniso-
tropically and H-atoms were refined isotropically at calculated
positions using a riding model.
3. Results and discussion
Fig. 1. X-ray structure of 2a. The CHCl3 solvent of crystallisation and all hydrogen
atoms have been removed for clarity.
3.1. Ligand synthesis
in excellent yield (typically w90%) according to Scheme 1. The 31P
The synthesis of a range of ester functionalised bis(phosphino)
amines followed a similar experimental protocol to that previously
reported by ourselves [15e,34c] and others [34a,34b,34d]. Hence
the new bis(phosphino)amines 1aꢀc were prepared by straight-
forward condensation of Ph2PCl and the appropriate primary amine
with NEt3 as base (Eqn. (1)). Compounds 1aLc exhibited a single
1
{1H} NMR spectra (in CDCl3) showed singlets at
d(P) 21 with JPtP
coupling constants of w3300 Hz consistent with the phosphorus
ligand trans to chloride [34a,34c,34d]. In the FTꢀIR spectra bands
attributed to nCO, nPN and nPtCl were observed for all three complexes
(see Experimental Section for characterising data). The dibromo-
3b and diiodoplatinum(II) 4b analogues were prepared from
1 equiv. of 1b and PtBr2(cod) or PtI2(cod) respectively. Furthermore
the dichloropalladium(II) complex 2`b was prepared from
31P{1H} NMR resonance (in CDCl3) at w
other known examples [34a,34c]. In their 1H NMR spectra the
methyl protons resonate around
d(P) 69 in accordance with
d(H) 3.8 whereas the FTꢀIR
1
spectra (pressed KBr discs) displayed strong absorptions in the
range 1727ꢀ1717 cmꢀ1 (CO stretch) and 927ꢀ891 cmꢀ1 (PN
stretch). The positive-ion FAB mass spectra gave the anticipated
parent ions for all three ligands with an additional [M þ O] ion
observed for the 3- and 4-isomeric bis(phosphino)amines.
PdCl2(cod). A reduction in the magnitude of the JPtP coupling
constants from approx. 3300 Hz in the chlorides 2aꢀc to 3260 Hz
(for 3b) and 3066 Hz (for 4b) is consistent with the observation of
increasing trans influence of the halide ligand on going from
Cl > Br > I. Other selected characterising data is given in the
Experimental Section.
Compound 2a$0.75CHCl3 was characterised by X-ray crystallog-
raphyand the molecular structure shown in Fig.1 with selected bond
lengths and angles given in Table 2. The geometry around the plat-
inum centre is distorted square-planar as reflected by the bond
angles [P(1)ꢀPt(1)ꢀP(2) 72.68(11), P(2)ꢀPt(1)ꢀCl(2) 98.80(12),
Cl(1)ꢀPt(1)ꢀCl(2) 91.32(13), P(1)ꢀPt(1)ꢀCl(1) 97.34(12)ꢁ] which
agree with previous literature values [34a,34c]. The four-membered
PtP2N ring is essentially planar while the PtꢀP/PꢀN distances
compare well with those of known PtCl2[Ph2PN{R}PPh2] compounds
[34a,34c]. Finally the PtꢀCl bond lengths [2.346(3) Å and 2.349(3) Å]
are typical for a P-donor centre trans to a chloride ligand.
Ph
Ph
Ph
Ph
P
P
NH2
R2
N
Ph2PCl/NEt3
R3
R1
R3
R1
R2
R2=R3=H, R1=CO2Me 1a
R2=H, R1=R3=CO2Me
1b
R1=R3=H, R2=CO2Me
1c
3.2. Coordination studies
The X-ray structure of 4b is shown in Fig. 2 (Table 3) and the
metric parameters are broadly as expected. Only two other crys-
tallographic examples of analogous complexes with short-bite
PeNeP ligands have been reported [35].
Reaction of 1aꢀc with PtCl2(cod) proceeded smoothly, with
facile displacement of cod, to give the P,P0-chelate complexes 2aꢀc
X
X
Cl
Ph
Cl
Ph
Ph
Ph
P
M
N
P
Pt
N
Ph
Ph
Ph
Ph
Ph
N
Ph
P
P
P
P
MCl2(cod)
PtX2(cod)
Ph
Ph
R3
R1
R3
CO2Me
R2
R1
MeO2C
R2
R2=R3=H, R1=CO2Me, M=Pt
R2=H, R1=R3=CO2Me, M=Pt
R1=R3=H, R2=CO2Me, M=Pt
R2=H, R1=R3=CO2Me, M=Pd
2a
1a
1b
1c
1b
X=Br 3b
4b
X=I
2b
2c
2`b
Scheme 1. Synthesis of compounds 2ae4b.

K.G. Gaw et al. / Journal of Organometallic Chemistry 699 (2012) 39e47
43
Table 2
Cl
Cl
P
X
X
P
M
Pt
Selected bond lengths and angles for 2a$0.75CHCl3.
Ph
Ph
Ph
Ph
Ph
Ph
P
NaBr
P
or NaI
MeOH
r.t.
Ph
Ph
Bond length/Å
2b
2`b
NH MeO
NH MeO
Pt(1)ꢀP(1)
2.192(3)
r.t.
Pt(1)ꢀP(2)
2.209(3)
2.346(3)
2.349(3)
1.721(8)
1.706(9)
1.185(16)
1.300(15)
Pt(1)ꢀCl(1)
CO2Me
CO2Me
MeO2C
MeO2C
Pt(1)ꢀCl(2)
P(1)ꢀN(1)
M=Pt
M=Pd
5a
5d
X=Br 5b
X=I
5c
N(1)ꢀP(2)
C(19)ꢀO(19)
Scheme 2. Synthesis of compounds 5ae5d.
C(19)ꢀO(20)
Bond angle/ꢁ
P(1)ꢀPt(1)ꢀP(2)
P(1)ꢀPt(1)ꢀCl(1)
P(2)ꢀPt(1)ꢀCl(1)
P(1)ꢀPt(1)ꢀCl(2)
P(2)ꢀPt(1)ꢀCl(2)
Cl(1)ꢀPt(1)ꢀCl(2)
Pt(1)ꢀP(1)ꢀN(1)
P(1)ꢀN(1)ꢀP(2)
N(1)ꢀP(2)ꢀPt(1)
72.68(11)
97.34(12)
169.71(12)
170.70(11)
98.80(12)
91.32(13)
94.2(3)
Examples of PꢀC bond cleavage in coordinated phosphines are
known and this reaction can be performed using either base [36]
or a low molecular weight alcohol [37,38]. This feature has also
been observed [19,34b,39] for PꢀN bond(s), in both free and
complexed (phosphino)amines, which are susceptible to attack by
MeOH. We find, using 2b in the first instance, a clean and selective
bond cleavage of one PꢀN bond affording the mixed platinum(II)
species 5a (Scheme 2). When a suspension of 2b was stirred for
16 h in MeOH a colourless solid 5a was isolated in 79% yield and
has been fully characterised. The 31P{1H} NMR spectrum of 5a
showed two doublets, each with associated 195Pt satellites, indic-
ative of inequivalent phosphorus environments. The downfield
99.1(5)
94.0(3)
resonance at
the upfield resonance at
d
(P) 81.1 is assigned to the coordinated Ph2POMe and
(P) 30.0 assigned [19a,34b] to the ligated
d
monodentate (phosphino)amine Ph2PNH{R} [R
¼
C6H3(3,5-
CO2Me)2]. A small 2JPP coupling constant of 13 Hz implies a mutu-
ally cis arrangement of both coordinated ligands. In the 1H NMR
spectrum the expected resonances for the aromatic and ester
groups were observed in addition to a doublet at d
(H) 8.33 (2JPH
12 Hz) which was assigned to the amine proton and a doublet at
d
(H) 2.8 (3JPH 12 Hz) for the Ph2POMe [37]. The FTꢀIR spectrum
showed two absorptions in the nPtCl region providing further
support for a cis configuration and a weak band at 3239 cmꢀ1
consistent with the presence of a eNH group. This reaction,
although relatively uncommon, has previously been observed for
other PeNeP type systems [19c,35b,39]. It has been shown in this
work, using Ph2PN{3,5-C6H3(CO2Me)2}PPh2, mild conditions
(MeOH/r.t.) are sufficient. Stirring a MeOH suspension of 2`b for
16 h gave the mixed palladium complex cis-PdCl2[Ph2PNH
{C6H3(3,5-CO2Me)2}](Ph2POMe) 5d along with some cis-
PdCl2(Ph2POMe)2 and unreacted 2`b. 31P{1H} NMR spectroscopy
revealed 5d to be the major species present (w80%) in the crude
solid and displayed the expected AX pattern. Prolonged reflux
times only increased the amount of cis-PdCl2(Ph2POMe)2 resulting
from a second PꢀN cleavage.
Fig. 2. X-ray structure of 4b. All hydrogen atoms have been removed for clarity.
The molecular structure of 5a$CHCl3 (Fig. 3, Table 4), as deter-
mined by X-ray crystallography, showed the platinum to be in
a slightly distorted square-planar environment with the coordi-
nation sphere occupied by two chloride and two monodentate
phosphorus ligands Ph2POMe and Ph2PNH{C6H3(3,5-CO2Me)2} in
a cis configuration. The PtꢀCl bond lengths [2.3704(16) Å and
2.3500(14) Å] and PtꢀP [2.2517(14) Å and 2.2209(15) Å] compare
Table 3
Selected bond lengths and angles for 4b.
Bond length/Å
Pt(1)ꢀP(1)
2.2100(13)
2.2105(13)
2.6380(6)
2.6544(7)
1.715(4)
1.709(4)
1.206(5)
1.333(5)
Pt(1)ꢀP(2)
Pt(1)ꢀI(1)
Pt(1)ꢀI(2)
P(1)ꢀN(1)
well
with
literature
values
e.g.
cis-PtCl2[S-Ph2PNH
N(1)ꢀP(2)
{C(H)(Me)(Ph)}](Ph2POMe) [2.374(2) Å and 2.356(2) Å for PtꢀCl
and 2.214(3) and 2.244(2) Å for PtꢀP] [39]. The structural param-
eters of the Ph2POMe ligand are also similar to those found in
related complexes containing this group. The P(1)ꢀN(1) bond
length [1.679(5) Å] is shorter than the accepted value for a PꢀN
single bond implying partial double bond character. There is also an
intramolecular hydrogen bond between a metal bound chloride
ligand and the NꢀH hydrogen [N(1).Cl(1) 3.032(5) Å; H(1N).
Cl(1) 2.25(4) Å; N(1)ꢀH(1N).Cl(1) 138(5)ꢁ] [35b].
C(19)ꢀO(1)
C(19)ꢀO(2)
Bond angle/ꢁ
P(1)ꢀPt(1)ꢀP(2)
P(1)ꢀPt(1)ꢀI(1)
P(2)ꢀPt(1)ꢀI(1)
P(1)ꢀPt(1)ꢀI(2)
P(2)ꢀPt(1)ꢀI(2)
I(1)ꢀPt(1)ꢀI(2)
Pt(1)ꢀP(1)ꢀN(1)
P(1)ꢀN(1)ꢀP(2)
N(1)ꢀP(2)ꢀPt(1)
72.89(4)
92.54(3)
164.95(3)
170.26(3)
97.71(3)
96.995(12)
93.41(12)
100.15(18)
93.55(12)
Attempts to prepare cis-PtX2[Ph2PNH{C6H3(3,5-CO2Me)2}]
(Ph2POMe) (X ¼ Br 5b or I 5c) by stirring a MeOH suspension of 3b

44
K.G. Gaw et al. / Journal of Organometallic Chemistry 699 (2012) 39e47
Fig. 3. X-ray structure of 5a. The CHCl3 solvent of crystallisation and all hydrogen atoms except on N(1) have been removed for clarity.
coordination sphereoccupied by two iodides, Ph2POMe and Ph2PNH
Table 4
Selected bond lengths and angles for 5a$CHCl3 and 5c$CH2Cl2.
{C6H3(3,5-CO2Me)2} ligands bound in a cis configuration. Similar to
5a, there is also an intramolecular hydrogen bond between a metal
bound iodide ligand and the NꢀH hydrogen [N(1).I(1) 3.283(10) Å;
H(1N).I(1) 2.41(7) Å; N(1)ꢀH(1N).I(1) 149(10)ꢁ].
Bond length/Å
5a$CHCl3 (X ¼ Cl)
5c$CH2Cl2 (X ¼ I)
2.281(3)
2.228(3)
2.6781(11)
2.6598(12)
1.679(9)
Pt(1)ꢀP(1)
2.2517(14)
2.2209(15)
2.3704(16)
2.3500(14)
1.679(5)
1.602(4)
1.203(7)
1.330(7)
1.181(8)
Pt(1)ꢀP(2)
Pt(1)ꢀX(1)
When the same procedure was extended to 2a and 2c, high
recovery of the unreacted platinum(II) starting materials was
observed. However upon leaving a MeOH filtrate of 2a to stand for
w2 weeks a small crop of pale yellow crystals (18% isolated yield)
were obtained and shown, by single crystal X-ray crystallography,
to be the cyclometallated platinum(II) complex cis-PtCl[Ph2PNH
{C6H3(3-CO2Me)}](Ph2POMe) 6 (Eqn. (2)). The 31P{1H} NMR spec-
Pt(1)ꢀX(2)
P(1)ꢀN(1)
P(2)ꢀO(2)
1.590(8)
C(19)ꢀO(19)
C(19)ꢀO(20)
C(21)ꢀO(21)
C(21)ꢀO(22)
Bond angle/ꢁ
1.206(15)
1.297(14)
1.203(14)
1.355(14)
1.311(8)
trum of 6 showed two doublets at
2292 and 4421 Hz respectively. The upfield resonance at
d
(P) 117.3 and 71.7 with a 1JPtP of
(P) 71.7
P(1)ꢀPt(1)ꢀP(2)
P(1)ꢀPt(1)ꢀX(1)
P(2)ꢀPt(1)ꢀX(1)
P(1)ꢀPt(1)ꢀX(2)
P(2)ꢀPt(1)ꢀX(2)
X(1)ꢀPt(1)ꢀX(2)
Pt(1)ꢀP(1)ꢀN(1)
O(2)ꢀP(2)ꢀPt(1)
94.03(5)
92.94(5)
171.49(6)
173.98(6)
85.96(5)
87.63(6)
108.99(17)
110.53(15)
92.56(11)
94.53(8)
170.96(8)
175.26(7)
87.00(9)
86.39(4)
108.6(4)
109.3(3)
d
indicates the phosphorus is within a five-membered chelate ring
1
and the JPtP suggests the phosphorus is trans to chloride. In
contrast, for the resonance at d
(P) 117.3, the small 1JPtP suggests the
phosphorus is trans to a high trans influence ligand, in this case an
orthometallated arene group [15e]. The small 2JPP coupling of 20 Hz
suggests that these phosphorus ligands are mutually cis. The 1H
NMR spectra showed, in addition to the anticipated aromatic, NH
and e CO2Me resonances, a doublet at d
(H) 2.85 (2JPH 11.1 Hz)
or 4b gave predominantly unreacted starting materials. Refluxing
these solutions produced mainly cis-PtX2(Ph2POMe)2 (X ¼ Br or I)
instead and little spectroscopic evidence for the mixed compounds
5b/5c. However clean metathesis of 5a with NaBr (or NaI) in
(CH3)2CO/MeOH afforded the desired complexes 5b and 5c in
excellent yields. Characterising data for these compounds are given
in the Experimental Section.
assigned to the Ph2POMe methyl protons. The FTꢀIR spectrum
showed one absorption assigned to nPtCl with an additional band at
3310 cmꢀ1
(nNH) supporting cleavage and protonation of a single
PꢀN bond. Bands assigned to nCO and nPN were observed at
1696 cmꢀ1 and 923 cmꢀ1 respectively. When 2a was heated under
reflux in MeOH for 16 h three major compounds were identified by
1
31P NMR including cycloplatinated 6, 7 [
d
(P) 81.0, JPtP 4342 Hz;
The molecular structure of 5c$CH2Cl2 (Fig. 4, Table 4), as deter-
mined by X-ray crystallography, showed the platinum to be in
1
2
29.3, JPtP 3950 Hz, JPP 17.6 Hz] and cis-PtCl2(PPh2OMe)2 8 [
d(P)
85.5, 1JPtP 4179 Hz].
a
slightly distorted square-planar environment with the
Fig. 4. X-ray structure of 5c. The CH2Cl2 solvent of crystallisation and all hydrogen atoms except on N(1) have been removed for clarity.

K.G. Gaw et al. / Journal of Organometallic Chemistry 699 (2012) 39e47
45
R2
R2
R1
R1
Cl
P
Cl
P
Cl
P
Cl
P
Cl
MeOH
r.t. or
Pt
Pt
Pt
2a
HN
MeO
+
+
HN
Ph
Ph
Ph
Ph
Ph
Ph
or 2c
P
P
MeO
D
Ph Ph
Ph Ph
MeO
Ph Ph
MeO
6
7
R1=CO2Me, R2=H
R1=H, R2=CO2Me
R1=CO2Me, R2=H
R1=H, R2=CO2Me
8
9
10
Since the exact structure of 6 could not be readily ascertained
from NMR spectroscopy alone, i.e. the data could not allow for
accurately distinguishing between which regioisomer [2-(6`) or 6-
positioned (6)] had formed, a single crystal X-ray analysis was
undertaken. This confirmed that platination had occurred specifi-
cally at the less sterically hindered 6-position [40] on the N-arene
ring of Ph2PNH{C6H3(3-CO2Me)}. The X-ray structure of 6 (Fig. 5,
Table 5) revealed an approximate square-planar coordination of the
platinum [P(1)ꢀPt(1)ꢀC(1) 83.08(11), Cl(1)ꢀPt(1)ꢀC(1) 93.20(11),
Cl(1)ꢀPt(1)ꢀP(2) 86.57(4), P(2)ꢀPt(1)ꢀP(1) 96.97(4)ꢁ] within the
five-membered chelate ring. The two phosphorus ligands adopt
a cis configuration with typical PtꢀP [2.1951(11) and 2.2855(10) Å]
bond lengths. The observation of different PtꢀP bond distances
clearly reflect the different trans ligands present.
over 10 (4:1 ratio) as judged by 31P{1H} NMR in addition to a small
1
amount of cis-PtCl2(PPh2OMe)2
8
[
d(P) 85.6, JPtP 4175 Hz]
presumably as a consequence of PꢀN cleavage of the platinum(II)
bound (phosphino)amine. The 1H NMR spectrum confirmed the
presence of eNH [
10.6 Hz)], eCO2Me [
d
(H) 4.91 (2JPH 3.2 Hz, 3JPtH 86 Hz) and 8.29 (2JPH
d
11.6 Hz) and 2.77 (3JPH 11.2 Hz)] groups in 9 and 10 respectively.
Although PꢀN bond cleavage using higher boiling linear alcohols
has not been attempted in our work, Urriolabeitia and co-workers
have shown that related mixed platinum(II) complexes can be
synthesised [39].
(H) 3.73 and 3.72] and OMe [d
(H) 2.87 (3JPH
The X-ray structure of 9 (Fig. 6, Table 5) revealed similar metric
parameters to 6 including an approximate square-planar coordina-
tion of the platinum [P(1)ꢀPt(1)ꢀC(1) 83.00(14), Cl(1)ꢀPt(1)ꢀC(1)
92.69(14), Cl(1)ꢀPt(1)ꢀP(2) 88.05(4), P(2)ꢀPt(1)ꢀP(1) 96.17(4)ꢁ]
within the five-membered chelate ring. Likewise the two phos-
phorus ligands in 9 adopt a cis configuration with typical PtꢀP
[2.1935(12) and 2.2916(12) Å] bond lengths. Dimer pairs are formed
through intermolecular H-bonding with CH3OH [N(1).O(1S)
2.997(6) Å; H(1).O(1S) 2.14 Å; N(1)ꢀH(1).O(1S) 163ꢁ and O(1S).
O(1) 2.830(7) Å; H(1S1).O(1) 2.04(2) Å; O(1S)ꢀH(1S1).O(1)
Refluxing PtCl2[Ph2PN{C6H4(4-CO2Me)}PPh2] 2c in MeOH for
16 h gave a 1:1 mixture of the orthometallated complex PtCl
1
[Ph2PNH{C6H3(4-CO2Me)}](Ph2POMe) 9 [
d
(P) 117.5, JPtP 2314 Hz;
1
2
72.7, JPtP 4434 Hz, JPP 17.6 Hz] and cis-PtCl[Ph2PNH{C6H4(4-
1
1
CO2Me)}](Ph2POMe) 10
[d(P) 80.9, JPtP 4337 Hz; 28.7, JPtP
3950 Hz, JPP 13.2 Hz] as indicated by 31P{1H} NMR spectroscopy.
2
Further refluxing (up to 68 h) in MeOH favoured formation of 9
Table 5
Selected bond lengths and angles for 6 and 9$CHCl3$CH3OH.
Bond length/Å
6
9$CHCl3$CH3OH
Pt(1)ꢀP(1)
2.1951(11)
2.2855(10)
2.3590(11)
2.062(3)
2.1935(12)
2.2916(12)
2.3652(11)
2.075(4)
Pt(1)ꢀP(2)
Pt(1)ꢀCl(1)
Pt(1)ꢀC(1)
P(1)ꢀN(1)
1.663(3)
1.671(4)
P(2)ꢀO(3)
1.606(3)
1.611(3)
C(X)ꢀO(1)
1.211(5)a
1.331(5)a
1.232(6)b
1.328(7)b
C(X)ꢀO(2)
Bond angle/ꢁ
P(1)ꢀPt(1)ꢀP(2)
P(1)ꢀPt(1)ꢀCl(1)
P(2)ꢀPt(1)ꢀCl(1)
P(1)ꢀPt(1)ꢀC(1)
P(2)ꢀPt(1)ꢀC(1)
Cl(1)ꢀPt(1)ꢀC(1)
Pt(1)ꢀP(1)ꢀN(1)
Pt(1)ꢀP(2)ꢀO(3)
96.97(4)
174.84(3)
86.57(4)
83.08(11)
176.98(10)
93.20(11)
103.94(12)
109.90(10)
96.17(4)
173.01(4)
88.05(4)
83.00(14)
178.74(14)
92.69(14)
104.29(15)
109.55(13)
a
Fig. 5. X-ray structure of 6. All hydrogen atoms except on N(1) have been removed for
clarity.
X ¼ C(5).
b
X ¼ C(7).

46
K.G. Gaw et al. / Journal of Organometallic Chemistry 699 (2012) 39e47
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In summary, we have shown new functionalised bis(phosphino)
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to various mixed platinum(II) complexes containing R2PNH{R} and
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Acknowledgements
We are extremely grateful to Johnson-Matthey for their kind
donation of precious metals. The EPSRC National Crystallography
Service at the University of Southampton for the collection of data for
4b,6and9$CHCl3$CH3OHareacknowledged. WealsothanktheEPSRC
for a studentship (KGG) and Infineum UK Ltd for financial support.
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Appendix A. Supplementary material
CCDC 216325, 843540e843543, 849491; contains a complete set
of X-ray crystallographic structural data for compounds
2a$0.75CHCl3, 4b, 5a$CHCl3, 5c$CH2Cl2, 6 and 9$CHCl3$CH3OH. These
data can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
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