Synthesis and characterisation of E,O-mixed donor (E = P, S or Se) ligand complexes of palladium(II) and platinum(II)

Article abstract of DOI:10.1016/S0020-1693(99)00493-4

New palladium(II) and platinum(II) complexes with the hybrid ligands Ph₂PNHP(O)Ph₂, [Ph₂PNP(O)Ph₂]^- or [Ph₂P(E)NP(O)Ph₂]^- (E = S or Se) have been prepared and characterised. Hence reaction of the cyclometallated dimers [{Pd(μ-Cl)(C ~ N)}₂] [C ~ N=C₁₂H₉N₂ or C₁₃H₈N] with Ph₂PNHP(O)Ph₂ gave the mononuclear compounds [PdCl(C ~ N){Ph₂PNHP(O)Ph₂-P}]. Chloride abstraction, or amine deprotonation, afforded [Pd(C ~ N){Ph₂PNHP(O)Ph₂-P,O}][BF₄] or [Pd(C ~ N){Ph₂PNP(O)Ph₂-P,O}] bearing a neutral or anionic P,O-chelating ligand, respectively. Reaction of [{Pd(μ- Cl)(C₉H₁₂N)}₂] with Ph₂PNHP(O)Ph₂ in CDCl₃ solution gave the known, rather unstable compound, [PdCl(C₉H₁₂N)-{Ph₂PNHP(O)Ph₂-P}]. Spectroscopic and analytical evidence presented here suggest that [PdCl(C₉H₁₂N){Ph₂PNHP(O)Ph₂-P}] undergoes amine deprotonation/Pd-C bond rupture to give an isomeric compound, tentatively assigned as [PdCl{Ph₂PNP(O)Ph₂-P,O}(NMe₂CH₂Ph)]. Bridge cleavage of [{Pd(μ-Cl)(C₁₂H₉N₂)}₂] with the unsymmetrical anions [Ph₂P(E)NP(O)Ph₂]^- (E = S or Se) gave the square-planar complexes [Pd(C₁₂H₉N₂){Ph₂P(E)NP(O)Ph₂-E,O}] exclusively as one isomer (E trans to N). In a similar manner the new metal(II) compounds [PtCl{Ph₂P(E)NP(O)Ph₂-E,O}(PMe₂Ph)] (E trans to Cl) and [Pd(C₉H₁₅O)-{Ph₂P(E)NP(O)Ph₂-E,O}] (E trans to olefin double bond) were synthesised. All compounds were characterised by a combination of multinuclear NMR [¹H, ³¹P{¹H}, ¹⁹⁵Pt{¹H}], IR spectroscopy and elemental analyses. Furthermore, the X-ray structures of [Pd(C₁₂H₁₂N){Ph₂PNHP(O)Ph₂-P,O}][BF₄] and [Pd(C₁₂H₁₂N){Ph₂PNP(O)Ph₂-P,O}] are reported and reveal, upon amine deprotonation, π-delocalisation within the P-N-P-O backbone of the anionic P,O-chelating ligand. (C) 2000 Elsevier Science S.A.

Full text of DOI:10.1016/S0020-1693(99)00493-4

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Inorganica Chimica Acta 299 (2000) 172–179
Synthesis and characterisation of E,O-mixed donor
(E=P, S or Se) ligand complexes of palladium(II) and
platinum(II)
Martin B. Smitha, *1, Alexandra M.Z. Slawinb, *2
a Department of Chemistry, Loughborough Uni6ersity, Loughborough, Leicestershire, LE11 3TU, UK
b School of Chemistry, Uni6ersity of St. Andrews, St. Andrews, Fife, KY16 9ST, UK
Received 15 July 1999; accepted 16 September 1999
Abstract
New palladium(II) and platinum(II) complexes with the hybrid ligands Ph2PNHP(O)Ph2, [Ph2PNP(O)Ph2]− or
[Ph2P(E)NP(O)Ph2]− (E=S or Se) have been prepared and characterised. Hence reaction of the cyclometallated dimers
[{Pd(m-Cl)(CꢀN)}2] [CꢀN=C12H9N2 or C13H8N] with Ph2PNHP(O)Ph2 gave the mononuclear compounds [PdCl(Cꢀ
N){Ph2PNHP(O)Ph2-P}]. Chloride abstraction, or amine deprotonation, afforded [Pd(CꢀN){Ph2PNHP(O)Ph2-P,O}][BF4] or
[Pd(CꢀN){Ph2PNP(O)Ph2-P,O}] bearing
a neutral or anionic P,O-chelating ligand, respectively. Reaction of [{Pd(m-
Cl)(C9H12N)}2] with Ph2PNHP(O)Ph2 in CDCl3 solution gave the known, rather unstable compound, [PdCl(C9H12N)-
{Ph2PNHP(O)Ph2-P}]. Spectroscopic and analytical evidence presented here suggest that [PdCl(C9H12N){Ph2PNHP(O)Ph2-P}]
undergoes amine deprotonation/PdꢀC bond rupture to give an isomeric compound, tentatively assigned as [PdCl{Ph2PNP(O)Ph2-
P,O}(NMe2CH2Ph)]. Bridge cleavage of [{Pd(m-Cl)(C12H9N2)}2] with the unsymmetrical anions [Ph2P(E)NP(O)Ph2]− (E=S or
Se) gave the square–planar complexes [Pd(C12H9N2){Ph2P(E)NP(O)Ph2-E,O}] exclusively as one isomer (E trans to N). In a
similar manner the new metal(II) compounds [PtCl{Ph2P(E)NP(O)Ph2-E,O}(PMe2Ph)] (E trans to Cl) and [Pd(C9H15O)-
{Ph2P(E)NP(O)Ph2-E,O}] (E trans to olefin double bond) were synthesised. All compounds were characterised by a combination
of multinuclear NMR [1H, 31P{1H}, 195Pt{1H}], IR spectroscopy and elemental analyses. Furthermore, the X-ray structures of
[Pd(C12H12N){Ph2PNHP(O)Ph2-P,O}][BF4] and [Pd(C12H12N){Ph2PNP(O)Ph2-P,O}] are reported and reveal, upon amine depro-
tonation, p-delocalisation within the PꢀNꢀPꢀO backbone of the anionic P,O-chelating ligand. © 2000 Elsevier Science S.A. All
rights reserved.
Keywords: Crystal structures; Palladium complexes; Cyclometallated complexes; P-ligand complexes
ligands. This property has been extensively exploited in
catalysis, e.g. the recent application of carbosilane den-
drimers with hemilabile P,O ligands as olefin hydro-
vinylation catalysts [4]. We are primarily interested in
heterofunctional ligands of the type R2PNHP(O)R2
[5,6] and [R2P(E)NP(O)R2]− (E=S or Se, R=Ph typi-
cally) [7–9] and their coordination chemistry to catalyt-
ically useful metals. A series of ligating modes have
been unveiled for these extremely versatile ligands with
the most common binding mode being P,O- or E,O-
chelation. Furthermore the amine proton in the par-
tially oxidised ligand Ph2PNHP(O)Ph2 is acidic and
undergoes smooth deprotonation affording complexes
with the unsymmetrical anion [Ph2PNP(O)Ph2]−. In-
1. Introduction
Ligands with mixed donor sets have attracted much
interest especially in recent years [1]. One particular
class that has received widespread attention is hemi-
labile ligands in which both ‘soft’ (e.g. P) and ‘hard’
(e.g. N or O) donor centres are present [2,3]. The hard
donor site coordinates only weakly to a late transition-
metal centre and can readily be displaced by other
1 *Corresponding author. Tel.: +44-1509-22 2553; fax: +44-1509-
22 3925.
2 *Corresponding author.
E-mailaddresses:m.b.smith@lboro.ac.uk(M.B.Smith),a.m.slawin@
st-andrews.ac.uk (A.M.Z. Slawin)
0020-1693/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0020-1693(99)00493-4

M.B. Smith, A.M.Z. Slawin / Inorganica Chimica Acta 299 (2000) 172–179
173
triguingly these hybrids are analogous to the carbon
2.2. Preparations
backbone systems Ph2PCH2P(E)Ph2 (E=O or S) (A),
[Ph2PCHC(O)Ph]− (B) and [MeC(S)CHC(O)Me]− (C).
Ligands such as A are efficient promoters for rhodium
catalysed methanol carbonylations [10] while nickel(II)
complexes of B and C are effective olefin oligomerisa-
tion catalysts [11,12]. Herein we report the synthesis,
spectral and structural characterisation of some new
palladium(II) and platinum(II) complexes with Ph2-
PNHP(O)Ph2, [Ph2PNP(O)Ph2]− and [Ph2P(E)NP(O)-
Ph2]− ligands.
2.2.1. [PdCl(C13H8N){Ph2PNHP(O)Ph2-P}] (1)
The compounds Ph2PNHP(O)Ph2 (0.050 g, 0.125
mmol) and [{Pd(m-Cl)(C13H8N)}2] (0.040 g, 0.0623
mmol) were allowed to react in CDCl3 (0.7 ml). After
the pale yellow solution was stirred for 5 min, it was
filtered to remove a small amount of black solid, and
addition of petroleum ether (b.p. 60–80°C, 10 ml)
afforded an off-white solid. Yield 0.066 g, 73%. FAB+
1
MS: m/z 685 [M−Cl]. IR: 3121 (wNH), 1216 (wPO). H
NMR: 9.78–6.45 (arom. H).
2.2.2. [PdCl(C12H9N2){Ph2PNHP(O)Ph2-P}] (2)
The compounds Ph2PNHP(O)Ph2 (0.295 g, 0.735
mmol) and [{Pd(m-Cl)(C12H9N2)}2] (0.233 g, 0.361
mmol) were allowed to react in CH2Cl2 (25 ml) under a
nitrogen atmosphere. After the orange solution was
stirred for 45 min, it was concentrated in vacuo to
approx. 1–2 ml, addition of petroleum ether (b.p.
60–80°C, 30 ml) and partial reduction of the solvent by
evaporation afforded a yellow solid. The solid was
collected by suction filtration and dried in vacuo. Yield
0.520 g, 99%. FAB+ MS: m/z 688 [M−Cl]. IR: 3136
(wNH), 1218 (wPO).
2. Experimental
2.1. Materials and physical measurements
Unless otherwise stated manipulations were carried
out in air using predried solvents. The ligand Ph2-
PNHP(O)Ph2 [5] and the potassium salts K[Ph2P(E)-
NP(O)Ph2] (E=S or Se) [9] and K[Ph2P(E)NP(E)Ph2]
(E=S or Se) [13] were prepared according to known
procedures. The dimeric compounds [{Pd(m-Cl)(Cꢀ
N)}2] (HCꢀN=C9H13N, C12H10N2, C13H9N), [{Pd(m-
Cl)(C9H15O)}2] (C9H15O=8-methoxycyclooct-4-en-1-
yl) and [{PtCl(m-Cl)PMe2Ph}2] were prepared accord-
ing to previously published procedures [14–18].
Ag[BF4], KOBut and NEt3 were purchased from
Aldrich Chemical and used without further puri-
fication.
2.2.3. [Pd(C12H9N2){Ph2PNHP(O)Ph2-P,O}][BF4] (3)
To a CH2Cl2 solution (20 ml) of [PdCl(C12H9N2)-
{Ph2PNHP(O)Ph2-P}] (0.107 g, 0.148 mmol) was added
solid Ag[BF4] (0.037 g, 0.190 mmol). After stirring for 4
h, AgCl was removed by filtration through a small
Celite pad, the volume concentrated by evaporation
under reduced pressure to approx. 1–2 ml and then
diethyl ether (5 ml) added. The solid product was
collected by suction filtration and dried in vacuo. Yield
0.058 g, 50%. FAB+ MS: m/z 688 [M−BF4]. IR: 3177
1
(wNH), 1139 (wPO). H NMR: 8.27–6.60 (arom. H).
Slow diffusion of diethyl ether into a CDCl3 solution
of [Pd(C12H12N){Ph2PNHP(O)Ph2-P,O}][BF4] (4) [23]
over several days gave crystals suitable for X-ray
crystallography.
Infrared spectra were recorded as KBr pellets in the
range 4000–220 cm−1 on a Perkin–Elmer System 2000
1
Fourier-transform spectrometer. H NMR spectra (250
MHz) were recorded on a Bruker AC250 FT spectrom-
eter with chemical shifts (l) in ppm to high frequency
of SiMe4 and coupling constants (J) in Hz. 31P{1H}
NMR spectra (36.2 MHz) were recorded on a Jeol
FX90Q spectrometer with chemical shifts (l) in ppm to
high frequency of 85% H3PO4 and coupling constants
(J) in Hz. 195Pt{1H} NMR spectra (53.7 MHz) were
recorded on a Bruker AC250 FT NMR spectrometer
with l referenced to external H2PtCl6 (in D2O–HCl).
All spectra were measured in CDCl3 unless otherwise
stated. Elemental analyses (Perkin–Elmer 2400 CHN
Elemental Analyzer) were performed by the Loughbor-
ough University Analytical Service within the Depart-
ment of Chemistry. Precious metal salts were provided
on loan by Johnson–Matthey.
2.2.4. [Pd(C12H9N2){Ph2PNP(O)Ph2-P,O}] (5)
To
a suspension of [PdCl(C12H9N2){Ph2PNHP-
(O)Ph2-P}] (0.101 g, 0.139 mmol) in CH3OH (1 ml) was
added KOBut (0.018 g, 0.160 mmol) yielding an imme-
diate deep-orange solution followed by the formation
of a solid. After stirring for approx. 10 min, the
product was collected by suction filtration, washed with
a small portion of CH3OH (0.5 ml) and dried in vacuo.
Yield 0.079 g, 82%. FAB+ MS: m/z 688 [M]. IR: 1128
1
(wPO). H NMR: 8.53–6.75 (arom. H).
[Pd(C13H8N){Ph2PNP(O)Ph2-P,O}] (6) was prepared
in a similar manner (73%). FAB+ MS: m/z 685 [M].
1
IR: 1136 (wPO). H NMR: 9.30–7.05 (arom. H).

174
M.B. Smith, A.M.Z. Slawin / Inorganica Chimica Acta 299 (2000) 172–179
Slow diffusion of petroleum ether (b.p. 60–80°C)
1H NMR: 8.03–7.22 (arom. H). [Pd(C12H9N2)-
{Ph2P(Se)NP(Se)Ph2-Se,Se%}] (12) (90%). IR: 544 (wPSe).
1H NMR: 8.08–7.22 (arom. H). [PtCl{Ph2P(S)-
NP(O)Ph2-S,O}(PMe2Ph)] (13) (92%). IR: 576 (wPS),
314 (wPtCl). 1H NMR: 7.94–7.31 (arom. H), 1.61
(PMe2Ph). [PtCl{Ph2P(Se)NP(O)Ph2-Se,O}(PMe2Ph)]
into a CH2Cl2 solution of [Pd(C12H12N){Ph2PNP-
(O)Ph2-P,O}] (7) [23] over several days gave crystals
suitable for X-ray crystallography.
2.2.5. [PdCl{Ph2PNP(O)Ph2-P,O}(NMe2CH2Ph)] (8)
The compounds Ph2PNHP(O)Ph2 (0.070 g, 0.174
mmol) and [{Pd(m-Cl)(C9H12N)}2] (0.045 g, 0.0815
mmol) were allowed to react in CDCl3 (1 ml). After
stirring the orange solution for 2 h, petroleum ether
(b.p. 60–80°C, 25 ml) was added. A small amount of
solid was removed by filtration (approx. 0.010 g) and
slow evaporation of the solvent to approx. 5 ml gave an
orange solid, which was collected by suction filtration
and dried in vacuo. Yield 0.073 g, 66%. IR: 1132 (wPO).
1H NMR: 8.00–7.14 (arom. H), 3.78 [4J(PH) 3.4 Hz,
CH2], 2.56 [4J(PH) 2 Hz, NMe2].
1
(14) (88%). IR: 557 (wPSe), 313 (wPtCl). H NMR: 7.96–
7.31 (arom. H), 1.66 (PMe2Ph).
2.2.7. [Pd(C9H15O){Ph2P(Se)NP(O)Ph2-Se,O}] (16)
To a suspension of [{Pd(m-Cl)(C9H15O)}2] (0.039 g,
0.0694 mmol) in CH3OH (1 ml) was added solid
K[Ph2P(Se)NP(O)Ph2] (0.075 g, 0.145 mmol). The mix-
ture was stirred for 10 min and the solid isolated by
1
suction filtration. Yield 0.071 g, 71%. IR: 560 (wPSe). H
NMR: 7.95–7.37 (arom. H), 5.92, 5.49, 3.42–3.16,
2.33–1.83 (C9H15O).
[Pd(C9H15O){Ph2P(S)NP(O)Ph2-S,O}] (15) was pre-
pared in a similar manner (67%). IR: 577 (wPS). 1H
NMR: 7.98–7.36 (arom. H), 5.92, 5.51, 3.38–3.24,
2.40–1.83 (C9H15O). The solids 15 and 16 were recrys-
tallised from CH2Cl2–petroleum ether (b.p. 60–80°C).
Microanalytical and spectroscopic data are given in
Tables 1 and 2.
2.2.6. [Pd(C12H9N2){Ph2P(S)NP(O)Ph2-S,O}] (9)
To a suspension of [{Pd(m-Cl)(C12H9N2)}2] (0.045 g,
0.070 mmol) in thf (5 ml) was added solid K[Ph2-
P(S)NP(O)Ph2] (0.068 g, 0.141 mmol). After stirring for
30 min the orange solution was evaporated to dryness
under reduced pressure. The residue was extracted into
CH2Cl2 (4 ml) and filtered through a small Celite pad
whereupon the volume was reduced in vacuo to approx.
1 ml and petroleum ether (b.p. 60–80°C, 15 ml) added.
The solid was isolated by suction filtration and dried in
vacuo. Yield 0.072 g, 72%. FAB+ MS: m/z 719 [M].
2.3. X-ray crystallography
The crystal structures of 4 and 7 were determined
using either a Rigaku AFC7S serial diffractometer with
graphite-monochromated (Cu Ka) radiation (u=1.541
1
IR: 577 (wPS). H NMR: 7.97–7.12 (arom. H).
,
The following compounds were prepared in a similar
manner: [Pd(C12H9N2){Ph2P(Se)NP(O)Ph2-Se,O}] (10)
(92%). FAB+ MS: m/z 767 [M]. IR: 560 (wPSe). 1H
NMR: 7.96–7.07 (arom. H). [Pd(C12H9N2){Ph2P-
(S)NP(S)Ph2-S,S%}] (11) (95%). IR: 584, 577, 570 (wPS).
78 A) and ꢀ-scans or a Bruker SMART diffractometer
with graphite-monochromated (Mo Ka) radiation (u=
,
0.710 37 A). Details of the crystal data collections and
refinements are given in Table 3. For the SMART data,
intensity data were collected using 0.3 or 0.15° width ꢀ
steps accumulating area detector frames spanning a
hemisphere of reciprocal space for all structures (data
were intergrated using the SAINT [19] program) and for
the Rigaku AFC7S data collections by ꢀ scans over a
single quadrant of reciprocal space. All data were cor-
rected for Lorentz, polarisation and long-term intensity
fluctuations. Absorption effects were corrected on the
basis of multiple equivalent reflections or by empirical
methods [20].
Table 1
Microanalysis data for complexes 1–3, 5, 6, 8–16 a
Analysis (%)
C
H
N
1
2
3
61.35 (61.60)
59.10 (59.70)
55.15 (55.75)
61.35 (61.25)
64.45 (64.85)
58.10 (58.50)
59.80 (60.05)
56.00 (56.40)
58.20 (58.75)
51.90 (52.10)
47.80 (47.95)
45.05 (45.30)
57.20 (58.45)
54.20 (54.65)
4.15 (4.05)
4.30 (4.20)
3.80 (3.90)
4.05 (4.45)
4.05 (4.15)
4.65 (4.90)
3.70 (4.05)
3.60 (3.80)
3.85 (4.00)
3.40 (3.55)
3.75 (3.90)
3.45 (3.70)
4.95 (5.20)
4.65 (4.90)
3.70 (3.90)
5.35 (5.80)
5.30 (5.40)
5.85 (5.95)
3.95 (4.10)
3.60 (4.15)
5.60 (5.85)
5.20 (5.50)
5.85 (5.70)
4.85 (5.05)
1.15 (1.75)
1.55 (1.65)
1.60 (2.05)
1.55 (1.95)
5 b
6
Structures were solved by direct methods and refined
by full-matrix least-squares against F (TEXSAN [21]) or
F2 (SHELXTL [22]) for all data with I\2|(I). A stan-
dard SHELXTL weighting scheme was used for 7 whilst
in the case of 4 the weighting scheme for the Rigaku/
TEXSAN was as previously reported [9]. The NꢀH pro-
ton in 4 was located from a DF map. All other
hydrogen atoms were assigned isotropic displacement
parameters and were constrained to idealised geo-
metries. Refinements converged to residuals given in
Table 3. All calculations were made with programs of
the TEXSAN or SHELXTL systems.
8
9
10
11
12
13
14
15
16
a Calculated values in parentheses.
b As H2O solvate.

M.B. Smith, A.M.Z. Slawin / Inorganica Chimica Acta 299 (2000) 172–179
175
Table 2
Selected NMR data for complexes 1–16
a
l(PE)
l(PO)
J(PEPO)
J(PSe)
l(PMe2Ph)
l(Pt)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
72.3
69.4
21.1
21.9
53.9
59.0
54.5
52.2
50.2
58.8
27.3
27.6
33
31
22
35
22
20
20
9
73.3
67.8 b
70.3
68.8
68.7 b
65.8
32.8
17.3
506
39.1, 37.2
29.0, 26.0
25.9 (123) c
9.6 (127) c
32.8
572, 519
475
31.0
31.1
25.2
25.4
−23.4 (3968) d
−25.1 (3964) d
−3817 e
−3915 e
4
2
18.1
510
a E=nothing, S or Se.
b Taken from Ref. [23].
c 2J(PtPE).
d 1J(PtP).
e Doublet-of-doublets.
3. Results and discussion
tive showing a significant downfield shift for PO [l(PO)
53.9 ppm] and a small change in l(P) for the coordi-
nated PIII centre (Table 2). This is fully consistent with
P,O-chelation and hence formation of a five-membered
PdꢀPꢀNꢀPꢀO metallacycle. To our knowledge no X-
ray structures of cyclometallated metal complexes
3.1. Palladium(II) complexes of Ph2PNHP(O)Ph2 and
[Ph2PNP(O)Ph2]−
Reaction of the cyclometallated dimers [{Pd(m-
Cl)(CꢀN)}2] [CꢀN=C13H8N, C12H9N2] with Ph2-
PNHP(O)Ph2 in either CDCl3 or CH2Cl2 afforded in
good yield, the chloro-bridge cleaved products [Pd-
Cl(CꢀN){Ph2PNHP(O)Ph2-P}] [CꢀN=C13H8N (1);
CꢀN=C12H9N2 (2)]. The spectroscopic and analytical
data (Tables 1 and 2, Section 2) are in full agreement
with the proposed structures (Scheme 1). Hence the
31P{1H} NMR spectra of both 1 and 2 show an AX
spin system in accordance with two inequivalent P
nuclei. The downfield resonance [l(P) 72.3 ppm for 1;
l(P) 69.4 ppm for 2] corresponds to the metal bound
PIII centre, whereas the doublet centred at approx. 20
ppm is typical for a non-coordinated phosphoryl group.
Furthermore 1 and 2 display similar l(PO) to the free
ligand Ph2PNHP(O)Ph2 and the palladium(II) com-
plexes [PdCl2{Ph2PNHP(O)Ph2-P}2] and [PdCl(CꢀN)-
{Ph2PNHP(O)Ph2-P}] [CꢀN=C9H12N, C10H8N,
C12H12N), in which the phosphine oxide moiety is
‘dangling’ [5,23].
Table 3
Details of the X-ray data collections and refinements for complexes 4
and 7
4
7
Empirical formula C36H33BN2OF4P2Pd C36.25H32.50Cl0.50N2OP2Pd
Formula weight
Crystal system
Space group
764.82
monoclinic
P21/c
698.21
triclinic
P1
(
Unit cell dimensions
,
a (A)
12.247(3)
17.501(2)
16.1626(9)
9.3228(1)
18.1784(2)
21.7966(2)
110.95(1)
98.705(1)
90.734(1)
3400.99(6)
298(2)
,
b (A)
,
c (A)
h (°)
i (°)
97.40(1)
k (°)
3
,
U (A )
3435(1)
293
4
5.81
5579
T (K)
Z
4 a
0.709
14436
v (mm−1
)
Measured
reflections
Compound 2 undergoes chloride abstraction with
Ag[BF4] in CH2Cl2 to give the monocation [Pd(C12H9-
N2){Ph2PNHP(O)Ph2-P,O}][BF4] (3) in reasonable
yield. We have previously used this procedure [23] to
induce P,O-chelation as exemplified by the synthesis of
[Pd(C12H12N){Ph2PNHP(O)Ph2-P,O}][BF4] (4). The
31P{1H} NMR spectrum of 3 was particularly informa-
Independent
reflections (Rint
Observed
reflections
(I\2.0|(I))
Final R, R%
5302 (0.082)
3055
9459 (0.0324)
9409
)
0.043, 0.045
0.042, 0.104
a Two independent molecules.

176
M.B. Smith, A.M.Z. Slawin / Inorganica Chimica Acta 299 (2000) 172–179
Scheme 1. (i) Ph2PNHP(O)Ph2; (ii) Ag[BF4]; (iii) KOBut; (iv) NEt3; (v) Ph2PNHP(O)Ph2, 2 h.
bearing a neutral P,O-chelating Ph2PNHP(O)Ph2 have
been described (vide infra) although the h3-allyl com-
plex [Pd(h3-C3H5){Ph2PNHP(O)Ph2-P,O}][BF4] has
been structurally characterised [6].
addition of petroleum ether (b.p. 60–80°C), showed
two 31P signals at l(P) 65.8 and 58.8 ppm [J(PPO)
9 Hz]. This clearly implies that the phosphoryl group
is involved in P,O-chelation and moreover, the 31P
NMR data compare well with related palladium(II)
compounds displaying this mode of ligation [5,23].
The IR spectrum shows no wNH absorption, also mir-
The amine proton in either 1 (or 2) can readily be
removed upon treatment with KOBut in CH3OH af-
fording the mixed chelate complexes [Pd(CꢀN)-
{Ph2PNP(O)Ph2-P,O}] [CꢀN=C12H9N2 (5); CꢀN=
C13H8N (6)]. A similar procedure was previously de-
scribed for the related complex [Pd(C12H12N){Ph2-
PNP(O)Ph2-P,O}] (7) [23]. Alternatively we find that
treatment of CDCl3 solutions of 2 (or 3) with excess
NEt3 gave 5 (31P{1H} NMR evidence). Compound 5
was characterised by the usual spectroscopic and ana-
lytical methods (Tables 1 and 2). Amine deprotonation
of the coordinated Ph2PNHP(O)Ph2 ligand in 5 and 6
was confirmed by the loss of the wNH band in the IR
spectrum. Furthermore a fall of approx. 80–90 cm−1 in
wPO supported a P,O-chelation mode.
Reaction of [{Pd(m-Cl)(C9H12N)}2] with Ph2PNHP-
(O)Ph2 was previously shown to give [PdCl(C9H12N)-
{Ph2PNHP(O)Ph2-P}] [23]. Upon standing in CDCl3
solution for approx. 20 min 31P resonances attributed
to [PdCl(C9H12N){Ph2PNHP(O)Ph2-P}] diminish and a
new set of resonances appears, one of these at signifi-
cantly higher frequency. Here we suggest a structure
for the species 8 based on spectroscopic and micro-
analytical data (Tables 1 and 2). The 31P{1H} NMR
spectrum of 8, isolated from CDCl3 solution upon
1
rored in the H NMR spectrum, suggesting a deproto-
nated [Ph2PNP(O)Ph2]− ligand is present within the
metal coordination sphere. The 1H NMR spectrum
confirms the presence of PhCH2NMe2, as opposed to
a cyclometallated ligand, with the remaining co-
ordination site presumably occupied by a chloride. In
contrast there is some literature precedence for
compounds with a carbon s-bonded CꢀN ligand
[24] formed by similar bridge cleavage reactions of
ortho-metallated dimers with tertiary phosphines (four
equiv.) [24]. We apparently do not observe this re-
activity here and believe that traces of acid may be
responsible for protonation of the PdꢀC bond. Moni-
toring the reaction of 8 with one equiv. of Ph2-
PNHP(O)Ph2 in the presence of NEt3 by 31P{1H} NMR
showed the predominant species to be the known bis
chelate [Pd{Ph2PNP(O)Ph2-P,O}2] [5]. The exact iso-
mer of 8 formed is uncertain and could not clearly be
established from NMR data. Attempts to grow suitable
crystals of 8 for an X-ray analysis have so far been
unsuccessful.

M.B. Smith, A.M.Z. Slawin / Inorganica Chimica Acta 299 (2000) 172–179
177
3.2. Crystal structures of [Pd(C12H12N){Ph2PNHP-
(O)Ph2-P,O}][BF4] and [Pd(C12H12N){Ph2PNP-
(O)Ph2-P,O}]·0.5CH2Cl2
The X-ray structure of 4 (Fig. 1, Table 4) shows
the palladium centre is bound by chelating
a
Ph2PNHP(O)Ph2 and an anionic cyclometallated ligand
in a slightly distorted square–planar geometry. The
coordination angles are in the range 84.4(3)–96.3(2)°
,
and the Pd is 0.05 A out of the plane of its four donor
Fig. 1. Crystal structure of [Pd(C12H12N){Ph2PNHP(O)Ph2-P,O}]-
[BF4]. Thermal ellipsoids are drawn at 50% probability. All CH
protons and the BF4− anion are omitted for clarity.
substituents. The PdꢀPꢀNꢀPꢀO five-membered ring is
,
slightly puckered [O(1) lies 0.32 A below the PdP2NO
ring]. The molecular structure confirms an arrangement
in which the PIII centre is trans to the nitrogen of the
cyclometallated ring. There is also an intermolecular
,
N(1)ꢀH(1)···F(1) hydrogen bond [N(1)···F(1) 2.84 A,
Table 4
−
,
H(1)···F(1) 2.11 A, N(1)ꢀH(1)···F(1) 130°] to the BF4
,
Selected bond distances (A) and angles (°) for complexes 4 and 7
counterion.
a
The X-ray structure of 7 (Fig. 2, Table 4) reveals that
the palladium centre is bound by two bidentate anionic
[Ph2PNP(O)Ph2]− and C12H12N ligands in a slightly
distorted square–planar geometry with coordination
angles in the range 83.8(2)–101.54(14)° (molecule 1)
and 84.1(2)–100.3(2)° (molecule 2). The PdꢀPꢀNꢀPꢀO
4
7
Bond lengths
Pd(1)ꢀP(2)
P(2)ꢀN(1)
N(1)ꢀP(1)
P(1)ꢀO(1)
O(1)ꢀPd(1)
Pd(1)ꢀC(1)
Pd(1)ꢀN(8)
2.226(2)
1.690(6)
1.658(6)
1.512(4)
2.151(5)
1.970(7)
2.112(5)
2.2608(12) [2.2600(13)]
1.630(4) [1.633(4)]
1.586(4) [1.602(4)]
1.528(4) [1.525(4)]
2.130(3) [2.158(3)]
1.996(5) [1.986(5)]
2.145(4) [2.160(4)]
,
ring conformation in 7 is nearly planar [N(1) lies 0.03 A
,
out of the plane (molecule 1); 0(41) lies 0.12 A out of
the plane (molecule 2)]. Furthermore the PIII centre of
[Ph2PNP(O)Ph2]− is again trans to the nitrogen of the
cyclometallated ring.
Bond angles
Pd(1)ꢀP(2)ꢀN(1)
P(2)ꢀN(1)ꢀP(1)
N(1)ꢀP(1)ꢀO(1)
P(1)ꢀO(1)ꢀPd(1)
O(1)ꢀPd(1)ꢀP(2)
O(1)ꢀPd(1)ꢀN(8)
O(1)ꢀPd(1)ꢀC(1)
C(1)ꢀPd(1)ꢀN(8)
C(1)ꢀPd(1)ꢀP(2)
N(8)ꢀPd(1)ꢀP(2)
103.1(2)
117.9(3)
108.4(3)
113.8(2)
87.7(1)
91.5(2)
172.9(2)
84.4(3)
105.74(14) [106.14(14)]
118.1(2) [116.7(2)]
115.1(2) [116.4(2)]
114.4(2) [112.1(2)]
86.38(9) [86.11(9)]
88.57(14) [89.44(13)]
171.9(2) [173.1(2)]
83.8(2) [84.1(2)]
A brief comparison of the PdP2NO metallacycles is
especially noteworthy. In 4 the PꢀN, NꢀP and PꢀO
distances are 1.690(6), 1.658(6) and 1.512(4) A, respec-
tively and similar to those in the free ligand
Ph2PNHP(O)Ph2 which exists in the solid state as a
hydrogen-bonded dimer pair [5]. Within the anionic
ligand [Ph2PNP(O)Ph2]− in 7 there is a significant
shortening of the PꢀN bonds and a small lengthening of
the PꢀO bond as a consequence of deprotonation.
,
96.3(2)
178.8(2)
101.54(14) [100.3(2)]
171.48(11) [175.55(11)]
a Equivalent parameters for the second molecule are given in
square brackets.
3.3. Palladium(II) and platinum(II) complexes of
[Ph2P(E)NP(O)Ph2]−
Reaction of the cyclopalladated azobenzene dimer
[{Pd(m-Cl)(C12H9N2)}2] with K[Ph2P(E)NP(O)Ph2]
[E=S (I); E=Se (II)] in thf, gave after work-up, the
mononuclear complexes [Pd(C12H9N2){Ph2P(E)NP(O)-
Ph2-E,O}] [E=S (9); E=Se (10)] (Scheme 2) in good
yields as yellow and orange solids, respectively. 31P{1H}
NMR clearly establishes that a single isomer is present
in CDCl3 solution since two resonances were observed
consistent with two inequivalent phosphorus nuclei. No
isomerism was observed even after allowing CDCl3
solutions to stand for 4 days. The 31P chemical shift for
PE moves upfield on going from E=S [l(PS) 32.8 ppm
for 9] to E=Se [l(PSe) 17.3 ppm for 10] whereas l(PO)
in both compounds is very similar (approx. 27 ppm).
Fig. 2. Crystal structure of [Pd(C12H12N){Ph2PNP(O)Ph2-P,O}]·
0.5CH2Cl2 showing one of the independent molecules only. Thermal
ellipsoids are drawn at 50% probability. All CH protons and the
solvent molecules are omitted for clarity.

178
M.B. Smith, A.M.Z. Slawin / Inorganica Chimica Acta 299 (2000) 172–179
Scheme 2. (i) [{Pd(m-Cl)(CꢀN)}2]; (ii) [{PtCl(m-Cl)(PMe2Ph)}2]; (iii) [{Pd(m-Cl)(C9H15O)}2].
By analogy with related compounds [23] this isomer has
an arrangement in which E is trans to N. We have also
prepared, for comparison, the organometallic com-
plexes [Pd(C12H9N2){Ph2P(E)NP(E)Ph2-E,E%}] [E=S
(11); E=Se (12)] (see Tables 1 and 2 and Section 2 for
characterising data).
displacement parameters, listings of bond lengths and
angles and hydrogen atom coordinates.
Acknowledgements
This general procedure was extended to the synthesis
of [PtCl{Ph2P(E)NP(O)Ph2-E,O}(PMe2Ph)] [E=S (13);
E=Se (14)] and [Pd(C9H15O){Ph2P(E)NP(O)Ph2-E,O}]
[E=S (15); E=Se (16)] in yields ranging from 67–92%
(Scheme 2). Spectroscopic and analytical data are given
in Tables 1 and 2 and Section 2. The NMR data reveal,
in all cases, the presence of one isomer in solution [25].
In the platinum(II) complexes 13 and 14 J(PtP) are
very similar (3968 Hz for 13; 3984 Hz for 14) suggesting
that the PMe2Ph ligand is trans to the same donor atom
(i.e. oxygen). The 195Pt{1H} NMR spectra show a
doublet-of-doublets at l(Pt) −3817 ppm (13) and
−3915 (14) ppm.
We should like to thank the EPSRC for support and
the EPSRC Mass Spectrometry Service Centre at
Swansea.
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The crystallographic data of the structures described
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