New E-unidentate [Ph2P(O)NP(E)Ph2]- (E = S or Se) complexes of palladium(II) and platinum(II)

Article abstract of DOI:10.1016/S0277-5387(00)00311-9

Metathesis of the monochloro metal(II) complexes [MCl(dien)]Cl (M = Pd or Pt; dien = diethylenetriamine) with K[Ph₂P(O)-NP(E)Ph₂] (E = S or Se) or K[Ph₂P(O)NPPh₂] (prepared in situ from Ph₂P(O)NHPPh₂/KOBu(t)) in methanol gave the cationic, mononuclear compounds [M{Ph₂P(O)NP(E)Ph₂-E}(dien)]⁺ or [M{Ph₂P(O)NPPh₂-P}(dien)]⁺, isolated as their hexafluorophosphate salts. Ligand substitution reactions of the dichlorometal(II) precursors [MCl₂(N ~ N)] (M = Pd or Pt; N ~ N = ethane-1,2-diamine, 1,2-diaminocyclohexane) with K[Ph₂P(O)NP(E)Ph₂] or K[Ph₂P(O)NPPh₂] gave the neutral bis substituted compounds [M{Ph₂P(O)NP(E)-Ph₂-E}₂(N ~ N)] or [M{Ph₂P(O)NPPh₂-P}₂(N ~ N)] in high yields (63-89%). Reaction of the unsymmetrical palladium(II) compound [PdCl₂(ampy)] (ampy = 2-aminomethylpyridine) with K[Ph₂P(O)NP(E)Ph₂] gave [Pd{Ph₂P(O)NP(E)Ph₂-E}₂(ampy)], analogous to the recently described compound [Pd{Ph₂P(O)NP(E)Ph₂-E}₂(en)], in which both [Ph₂P(O)NP(E)Ph₂]^- ligands are exclusively Emonodentate bound. In contrast, transmetallation of K [Ph₂P(O)NP(E)Ph₂] with [PdCl₂(tmeda)] (tmeda = N,N,N',N'-tetramethylethylenediamine) gave only the O,E-chelate monocationic complexes [Pd{Ph₂P(O)NP(E)Ph₂-O,E}(tmeda)]PF₆ and not [Pd{Ph₂P(O)-NP(E)Ph₂-E}₂(tmeda)]. Under similar reaction conditions the symmetrical anions [Ph₂P(E)NP(E)Ph₂]^- (E = S or Se) gave, without exception, the known bis homoleptic complexes [M{Ph₂P(E)NP(E)Ph₂-E,E'}₂] (M = Pd or Pt) with displacement of all chloride and amine ligands. All new compounds have been characterised by a combination of multinuclear NMR (¹H, ³¹P{¹H}, ¹⁹⁵Pt{¹H}), IR spectroscopy and elemental analyses. Furthermore, the X-ray crystal structures of five compounds have been determined and reveal a range of intermolecular and intramolecular hydrogen bonding contacts. There is also evidence for π-delocalisation within the E-P-N-P-O and P-N-P-O backbones of the E-ligating or O,E-chelating ligand. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0277-5387(00)00311-9

www.elsevier.nl/locate/poly
Polyhedron 19 (2000) 695–704
New E-unidentate [Ph2P(O)NP(E)Ph2]y (EsS or Se) complexes of
palladium(II) and platinum(II)
Martin B. SmithU 1,a , Alexandra M.Z. SlawinU
2,b
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
Received 27 October 1999; accepted 21 January 2000
Abstract
Metathesis of the monochloro metal(II) complexes [MCl(dien)]Cl (MsPd or Pt; diensdiethylenetriamine) with K[Ph2P(O)-
NP(E)Ph2] (EsS or Se) or K[Ph2P(O)NPPh2] (prepared in situ from Ph2P(O)NHPPh2/KOBut) in methanol gave the cationic, mono-
nuclear compounds [M{Ph2P(O)NP(E)Ph2-E}(dien)]q or [M{Ph2P(O)NPPh2-P}(dien)]q, isolated as their hexafluorophosphate salts.
Ligand substitution reactions of the dichlorometal(II) precursors [MCl2(N;N)] (MsPd or Pt; N;Nsethane-1,2-diamine, 1,2-diami-
nocyclohexane) with K[Ph2P(O)NP(E)Ph2] or K[Ph2P(O)NPPh2] gave the neutral bis substituted compounds [M{Ph2P(O)NP(E)-
Ph2-E}2(N;N)] or [M{Ph2P(O)NPPh2-P}2(N;N)] in high yields (63–89%). Reaction of the unsymmetrical palladium(II) compound
[PdCl2(ampy)] (ampys2-aminomethylpyridine) with K[Ph2P(O)NP(E)Ph2] gave [Pd{Ph2P(O)NP(E)Ph2-E}2(ampy)], analogous to
the recently described compound [Pd{Ph2P(O)NP(E)Ph2-E}2(en)], in which both [Ph2P(O)NP(E)Ph2]y ligands are exclusively E-
monodentate bound. In contrast, transmetallation of K[Ph2P(O)NP(E)Ph2] with [PdCl2(tmeda)] (tmedasN,N,N9,N9-tetramethylethyl-
enediamine) gave only the O,E-chelate monocationic complexes [Pd{Ph2P(O)NP(E)Ph2-O,E}(tmeda)]PF6 and not [Pd{Ph2P(O)-
NP(E)Ph2-E}2(tmeda)]. Under similar reaction conditions the symmetrical anions [Ph2P(E)NP(E)Ph2]y (EsS or Se) gave, without
exception, the known bis homoleptic complexes [M{Ph2P(E)NP(E)Ph2-E,E9}2] (MsPd or Pt) with displacement of all chloride and amine
ligands. All new compounds have been characterised by a combination of multinuclear NMR (1H, 31P{1H}, 195Pt{1H}), IR spectroscopy and
elemental analyses. Furthermore, the X-ray crystal structures of five compounds have been determined and reveal a range of intermolecular
and intramolecular hydrogen bonding contacts. There is also evidence for p-delocalisation within the E–P–N–P–O and P–N–P–O backbones
of the E-ligating or O,E-chelating ligand.
q2000 Elsevier Science Ltd All rights reserved.
Keywords: Palladium(II) complexes; Platinum(II) complexes; Chloride metathesis; X-ray crystallography; Heterodifunctional ligands
1. Introduction
of acacy and its derivatives [21]. In contrast, the coordinat-
ing ability of the unsymmetrical ligands [Ph2P(O)NP-
(E)Ph2]y (EsS or Se), bearing a mismatch in donoratoms,
has been remarkably poorly studied, especially towards tran-
sition-metal ions [22–26]. Furthermore, sparse examples of
compounds with [Ph2P(O)NP(E)Ph2]y and a central s-
[27] or p-block [28–30] element have only recently been
reported. Of those examples documented, the O,E-chelating
mode of binding (I) is most prevalent [22,25,26,28–30].
One very unusual example is the complex cis-[Pd{Ph2P-
(O)NP(Se)Ph2-O,Se}2] in which both six-membered Pd–
O–P–N–P–Se rings adopt distinctly different ring geometries
(X-ray evidence) [26]. Silvestru and coworkers recently
described the synthesis and X-ray crystal structure of the
dimeric compound [Na{Ph2P(O)NP(S)Ph2}P2C4H8O]2 in
which each [Ph2P(O)NP(S)Ph2]y behaves simultaneously
as an O,S-chelating and O-bridging ligand (II) [27]. In
The coordination chemistry of phosphorus containing
ligands with inorganic backbones, for example R2PNHPR2
[1–4], [R2PNPR2]y [5,6], R2P(E)NHPR2 [7,8],
[R2P(E)NPR2]y [7,8] and [R2P(E)NP(E)R2]y (EsO,
S or Se) [9–17], has been the topic of much interest espe-
cially over the last three years. Specifically [Ph2P(E)-
NP(E)Ph2]y, which coincidentally is closely related to
acacy (acetylacetonate), is an excellent ligand for complex-
ing numerousmetal ionsandfurthermorehasfoundimportant
uses as selective metal extractants [18], NMR shift reagents
[19] and more recently in catalysis [20]. This class of ligand
displays a wide range of ligation modes reminiscent to that
UCorresponding author. Tel.: q44-1509-222553; fax: q44-1509-
1
223925; e-mail: m.b.smith@lboro.ac.uk
UCorresponding author.
2
0277-5387/00/$ - see front matter q2000 Elsevier Science Ltd All rights reserved.
PII S0277-5387(00)00311-9
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contrast the ‘soft’ E-donor of [Ph2P(O)NP(E)Ph2]y can
bridge two late transition-metal centres (III), as observed in
[{Pd(h3-C3H5)[m-Ph2P(O)NP(Se)Ph2-Se]}2], forming a
central Pd2Se2 core with two pendant–P(O)Ph2 groups[23].
The [Ph2P(O)NP(E)Ph2]y can also behave as a non-coor-
dinating anion (IV) as exemplified by the unusual salt
[Pt(Ph2PC6H4NH2-P,N)(Ph2PC6H4NH-P,N)][Ph2P(O)-
NP(E)Ph2] (EsS or Se) [22]. We described in a recent
preliminary communication [24] the synthesis and char-
acterisation of [Pd{Ph2P(O)NP(E)Ph2-E}2(en)] and
[Au{Ph2P(O)NP(E)Ph2-E}{Ph2P(O)NHPPh2-P}] which
are the first reported examples in which [Ph2P(O)NP-
(E)Ph2]y adoptsan E-monodentatecoordinationmode(V).
This mode of ligation is especially noteworthy since
[Ph2P(O)NP(E)Ph2]y are ambidentate ligands capable of
binding through either O or E donor atoms depending on
whether the metal centre is ‘soft’ or ‘hard’ in character. Fur-
thermore in these rare examples there is a strong propensity
for hydrogen bonding between the ‘dangling’ –P(O)Ph2
group and the ancillary amine ligand [en, Ph2P(O)NHPPh2]
in the metal coordination sphere.
2. Experimental
2.1. General
Unless otherwise stated manipulations were carried out
in air with no special precaution taken regarding the use of
dry/distilled solvents. The potassium salts K[Ph2P(O)-
NP(E)Ph2] (EsS or Se) [26] and K[Ph2P(E)NP(E)Ph2]
(EsS or Se) [8,31] were prepared according to known
procedures whilst K[Ph2P(O)NPPh2] was prepared in situ
from Ph2P(O)NHPPh2/KOBut. The compounds [PdCl2-
(en)], [PdCl2(tmeda)], [PtCl2(C6H14N2)] (C6H14N2s
1,2-diaminocyclohexane), [PtCl2(py)2], [NH4][PF6] and
KOBut were purchased from Aldrich Chemical Co. and used
without further purification. [MCl(dien)]Cl (MsPd or Pt)
and [PdCl2(ampy)] were prepared by previous reported
methods [32–34].
Infrared spectra were recorded as KBr pellets in the range
4000–220 cmy1 on a Perkin-Elmer system 2000 Fourier-
transform spectrometer. 1H NMR spectra (250 MHz) were
recorded on a Bruker AC250 FT spectrometer with chemical
shifts d in ppm to high frequency of Si(CH3)4 and coupling
constants J in Hz; 31P{1H} NMR spectra (36.2 MHz) were
recorded on a JEOL FX90Q spectrometer with chemical
shifts d 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 d
referenced to external H2PtCl6 (in D2O/HCl). All spectra
were measured in CDCl3 unless otherwise stated. Elemental
analyses (Perkin-Elmer 2400 CHN elemental analyser)were
performed by the Loughborough University Analytical Ser-
vice within the Department of Chemistry.
Precious metal salts were provided on loan by Johnson
Matthey plc.
An understanding of the binding capabilities of these
extremely versatile, readily synthesised, ligands towardspre-
cious metals and their subsequent reactivity is important
given that complexes of acac are useful in several metal
complex catalysed reactions. Furthermore, there is consid-
erable interest in cis-[PtCl2(amine)2] for their cytotoxic
activity and their reactivity with various sulfur containing
ligands. To elucidate further the complexing properties of
[Ph2P(O)NP(E)Ph2]y (EsS or Se), their reactions with
selected metal(II) amine complexes have been investigated.
We present here our work regarding the synthesis and char-
acterisation of a series of square-planar palladium(II) and
platinum(II) complexes with didentate and tridentate amine
and monodentate E-bound [Ph2P(O)NP(E)Ph2]y ligands.
For comparison we have extendedthescopeofthesereactions
to the preparation of related complexes with P-bound
[Ph2P(O)NPPh2]y ligands. The new compounds have
been characterised by multinuclear NMR (1H, 31P{1H},
195Pt{1H}), IR spectroscopy and elemental analyses. More-
over, the molecular structures of five compounds are reported
and confirm, in three cases, that [Ph2P(O)NP(E)Ph2]y
adopts an E-unidentate mode of bonding and also a range of
intramolecular and intermolecular hydrogen bonding motifs.
2.2. Preparations
2.2.1. Preparation of [Pd{Ph2P(O)NP(S)Ph2-S}(dien)]PF6
(1)
To the solids [PdCl(dien)]Cl (0.029 g, 0.103 mmol) and
K[Ph2P(O)NP(S)Ph2] (0.051 g, 0.108 mmol) was added
CH3OH (1 cm3). After stirring at ambient temperature for
ca. 2 h, the yellow solution was filtered to remove trace
amounts of solid, and a methanolic solution (ca. 0.5 cm3) of
[NH4][PF6] (0.041 g, 0.252 mmol) wasadded. Thesolution
was stirred for 15 min and distilled water was addeddropwise
to afford a yellow precipitate. The mixture was stirred for an
additional 20 min and the solid 1 isolated by suction filtration
and dried in vacuo. Yield 0.071 g, 88%. FABq MS: m/z 641
(M–PF6)q. IR: 3641 (nOH), 3319, 3268, 3202, 3112 (nNH),
1
1243 (nPNP), 562 (nPS). H NMR (CD3OD): 7.99–7.29
(arom. H), 2.89–2.54 (dien). In a similar manner the fol-
lowing complexes were prepared: [Pd{Ph2P(O)NP(Se)-
Ph2-Se}(dien)]PF6 (2) (85%). FABq MS: m/z 689
(MyPF6)q. IR: 3639(nOH), 3316, 3268, 3203, 3115(nNH),
1
1236 (nPNP), 558 (nPSe). H NMR (CD3OD): 7.96–7.34
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M.B. Smith, A.M.Z. Slawin / Polyhedron 19 (2000) 695–704
697
(arom. H), 2.90–2.55 (dien). [Pt{Ph2P(O)NP(S)Ph2-S}-
(dien)]PF6 (3) (83%). FABq MS: m/z 730 (MyPF6). IR:
3640 (nOH), 3306, 3214 (nNH), 1223 (nPNP), 559 (nPS). 1H
NMR (CD3OD): 7.95–7.35 (arom. H), 3.06–2.48 (dien).
[Pt{Ph2P(O)NP(Se)Ph2-Se}(dien)]PF6 (4) (85%).
FABq MS: m/z 777 (MyPF6)q. IR: 3651, 3636 (nOH),
3303, 3204, 3113 (nNH), 1239 (nPNP), 558 (nPSe). 1H NMR
(CD3OD): 7.97–7.36 (arom. H), 3.18–2.46 (dien).
[Pd{Ph2P(O)NPPh2-P}(dien)]PF6 (5) (71%). FABq
MS: m/z 609 (MyPF6)q. IR:3334, 3280, 3193(nNH), 1165,
conditions gave several phosphorus containing species (31P
NMR evidence).
2.2.4. Preparation of [Pd{Ph2P(O)NP(S)Ph2-S}2(ampy)]
(9)
To the solids [PdCl2(ampy)] (0.017 g, 0.070 mmol) and
K[Ph2P(O)NP(S)Ph2] (0.070 g, 0.148 mmol) was added
CH3OH (1 cm3). The solids dissolved slowly within ca. 10
min whereupon product 9 deposited. The mixture was stirred
for a further 2 h and the solid collected by suction filtration
and dried in vacuo. Yield 0.058 g, 77%. FABq MS: m/z 1079
(Mq). IR: 3227, 3176 (nNH), 1287, 1266, 1232 (nPNP), 564
1
1155 (nPNP). H NMR (CD3OD): 8.03–7.38 (arom. H),
3.08–2.63 (dien).
1
(nPS). H NMR: 8.90–6.76 (arom. H), 5.21, 3.78 (NH2,
Crystals of 1 and 2 suitable for X-ray crystallographywere
grown by slow diffusion of Et2O into a CH3OH solution over
ca. 4 days.
Reaction of [MCl(dien)]Cl (MsPd or Pt) with
K[Ph2P(E)NP(E)Ph2] (EsS or Se, 1:1 or 1:2 molar ratio)
under analogous conditions to those described above gave
the known homoleptic complexes [M{Ph2P(E)NP(E)Ph2-
E,E9}2] [42]. The 31P NMR shifts were identical to those
previously reported.
CH2). In a similar manner [Pd{Ph2P(O)NP(Se)Ph2-Se}2-
(ampy)] (10) was prepared in 87% yield. FABq MS: m/z
1174 (Mq). IR: 3231, 3189 (nNH), 1283, 1259, 1225 (nPNP),
560, 549, 540 (nPSe). 1H NMR: 9.23–6.87 (arom. H), 4.83,
3.75 (NH2, CH2). The solids 9 and 10 could be recrystallised
from CH2Cl2/OEt2.
Crystals of 9 suitable for X-ray crystallography were
grown by slow diffusion of petroleum ether (b.p. 60–808C)
into a CDCl3 solution over the course of ca. 4 days.
Reaction of [PdCl2(ampy)] with 2 equiv. of K[Ph2P-
(E)NP(E)Ph2] (EsS or Se) gave [Pd{Ph2P(E)NP(E)-
Ph2-E,E9}2] in 87% (EsS) and 63% (EsSe) yields
respectively.
2.2.2. Preparation of [Pd{Ph2P(O)NPPh2-P}2(en)] (6)
To the solids [PdCl2(en)] (0.024 g, 0.101 mmol) and
Ph2P(O)NHPPh2 (0.084 g, 0.209 mmol) was added CH3OH
(1.5 cm3). To this slurry was added KOBut (0.025 g, 0.223
mmol) and the mixture was stirred for ca. 4 h. The solid was
filtered under reduced pressure, washed with CH3OH (ca.
0.5 cm3) and dried in vacuo. Yield 0.062 g, 63%. FABq MS:
m/z 967 (Mq). IR: 3650 (nOH), 3313, 3294, 3194 (nNH),
2.2.5. Preparation of [Pd{Ph2P(O)NP(S)Ph2-O,S}-
(tmeda)]PF6 (11)
To the solids [PdCl2(tmeda)] (0.029 g, 0.099 mmol) and
K[Ph2P(O)NP(S)Ph2] (0.049 g, 0.104 mmol) was added
CH3OH (1 cm3). After stirring for 2 h, the solution was
filtered and a methanolic (ca. 0.5 cm3) solution of
[NH4][PF6] (0.040 g) was added to afford a yellow precip-
itate. The product was collected by suction filtrationanddried
in vacuo. Yield 0.073 g, 92%. FABq MS: m/z 654
1
1188, 1173 (nPNP). H NMR: 8.18–6.90 (arom. H), 2.80,
1.76 (CH2, NH2).
Crystals of 6 suitable for X-ray crystallography were
grown by slow evaporation of a CDCl3/Et2O solution over
ca. 30 days.
1
(MyPF6)q. IR: 1230 (nPNP), 581 (nPS). H NMR: 7.90–
2.2.3. Preparation of [Pt{Ph2P(O)NP(S)Ph2-S}2(C6H14N2)]
(7)
7.38 (arom. H), 2.76 (CH2), 2.63, 2.39 [N(CH3)2]. In a
similar manner [Pd{Ph2P(O)NP(Se)Ph2-O,Se}(tmeda)]-
PF6 (12) was prepared (95%). FABq MS: m/z 702
(MyPF6)q. IR: 1230 (nPNP), 539 (nPSe). 1H NMR: 7.92–
7.38 (arom. H), 2.76 (CH2), 2.60, 2.46 [N(CH3)2].
Crystals of 11 suitable for X-ray crystallography were
grown by slow diffusion of diethyl ether into a CH3OH/
CH2Cl2 solution over the course of ca. 3 days.
A slurry of [PtCl2(C6H14N2)] (0.020 g, 0.0526 mmol)
and K[Ph2P(O)NP(S)Ph2] (0.050 g, 0.106 mmol) in
CH3OH (10 cm3) was refluxed, under a nitrogenatmosphere,
for 5 h. The yellow solution was evaporated to dryness under
reduced pressure, the residue taken up in CH2Cl2 (5 cm3)
and passed through a Celite pad. The volume was reduced to
ca. 1 cm3 and petroleum ether (b.p. 60–808C, 10 cm3) added
to precipitate the product 7 which was collected by suction
filtration and dried in vacuo. Yield 0.050 g, 81%. FABq MS:
m/z 1175 (Mq). IR: 3287, 3262, 3201 (nNH), 1282, 1249,
Microanalytical and spectroscopic data are given in Tables
1 and 2.
2.3. X-ray crystallography
1
1235 (nPNP), 560 (nPS). H NMR: 7.89–7.24 (arom. H),
5.46, 4.40, 1.80–0.80 (C6H14N2). In a similar manner
[Pt{Ph2P(O)NP(Se)Ph2-Se}2(C6H14N2)] (8) was pre-
pared in 89% yield. FABq MS: m/z 1269 (Mq). IR: 3293,
3266, 3205 (nNH), 1243 (nPNP), 545 (nPSe). 1H NMR: 7.91–
7.26 (arom. H), 5.35, 4.40, 1.81–0.86 (C6H14N2). Attempts
to prepare [Pt{Ph2P(O)NP(E)Ph2-E}2(py)2] under similar
The crystal structures of complexes 1, 2, 6, 9 and 11 were
determined using either a Rigaku AFC7S serial diffracto-
meter with graphite-monochromated (Cu Ka) radiation
˚
(ls1.541 78 A) and v-scans or a Bruker SMART diffrac-
tometer with graphite-monochromated (Mo Ka) radiation
˚
(ls0.710 37 A). Details of the crystal data collections and
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Table 1
Microanalytical data for compounds 1–12 a
Compound
C
H
N
1 b
2 c
3
41.70 (41.70)
39.40 (40.20)
38.00 (38.40)
36.15 (36.45)
44.45 (44.55)
60.90 (60.95)
55.00 (55.25)
51.20 (51.15)
58.95 (59.10)
54.15 (54.45)
44.85 (45.05)
42.50 (42.55)
4.25 (4.55)
3.80 (4.00)
3.60 (3.80)
3.55 (3.60)
4.45 (4.40)
4.85 (5.15)
4.85 (4.65)
4.35 (4.30)
4.45 (4.60)
4.10 (4.25)
4.30 (4.55)
4.25 (4.30)
7.25 (6.85)
5.95 (6.45)
6.05 (6.40)
5.95 (6.05)
7.05 (7.40)
5.55 (5.70)
4.60 (4.75)
4.10 (4.40)
5.00 (5.10)
4.35 (4.70)
5.70 (5.25)
4.95 (4.95)
4
5
6 d
7
8
9 d
10 d
11
12
a Calculated values in parentheses.
b As H2OP0.5CH3OH solvate.
c As CH3OH solvate.
d As H2O solvate.
Table 2
Selected NMR data for compounds 1–12
Compound d(PE) a
J(PtPE) J(PSe) d(PO)
J(PP) d(Pt)
1
2
3
4
5
29.1 b
14.6 b
26.4 b
11.5 b
32.1
16.5
17.3
16.6
17.4
497
484
96.8
101.2
y3084
y3135
19.8
21.7
6
35.5
18.2
17.6
7
8
9
10
11
12
25.9
10.4
28.1, 27.4
14.0, 13.3
34.8 b
20.2 b
94.5
105.6
15.0
15.6
15.1, 10.3
y3226
y3399
514
488, 519 16.3, 11.7
37.6
475
38.9
a EsS or Se.
b Recorded in CDCl3/CH3OH.
refinements are given in Table 3. For the SMART data, inten-
sities were collected using 0.38 or 0.158 width v steps accu-
mulating area detector frames spanning a hemisphere of
reciprocal space for all structures (data were integratedusing
the SAINT [35] program) and for the Rigaku AFC7S data
collections by v scans over a single quadrant of reciprocal
space. All data were corrected for Lorentz, polarisation and
long-term intensity fluctuations. Absorption effectswerecor-
rected on the basis of multiple equivalent reflections or by
empirical methods [36].
Structures were solved by direct methods and refined by
full-matrix least-squares against F (TEXSAN [37]) or F2
(SHELXTL [38]) for all data with I)2s(I). Standard
SHELXTL weighting scheme was used for 2, 6, 9 and 11
whilst in the case of 1 the weighting scheme for the Rigaku/
TEXSAN structure was as previously reported [26]. For 1
the O–H hydrogen atoms on both the H2O and CH3OH sol-
vent molecules were located from DF maps. In compound 2
the N(3)–H hydrogen atom was not located. For 6 the hydro-
s
a
b
g
m
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699
gen atoms on the H2O solvent molecule were located from
DF maps with these hydrogen atoms and those on N(49) and
N(50) refined isotropically. One mole of H2O for each inde-
pendent molecule of 9 (two H2O moleculesintheasymmetric
unit) was located and all O–H hydrogen atoms found. In all
structures the remaining hydrogen atoms (including those on
the solvent molecules in 1 and 2) were assigned isotropic
displacement parameters and were constrained to idealised
geometries. The chirality of 2 was tested by a Flackparameter
refinement which refined to y0.007(13) indicating the cor-
rect absolute stereochemistry. Refinements converged to
residuals given in Table 3. All calculations were made with
programs of the TEXSAN [37] or SHELXTL [38] systems.
Section 2. Particularly informative was 31P{1H} NMR which
showed single metal complexes as inferred by resonances at
d(PS) 29.1 (for 1) and 26.4 ppm (for 3) and d(PSe) 14.6
(for 2) and 11.5 ppm (for 4). In the case of 3 (and 4) the
PS and PSe resonances were flanked by 195Pt satellites
(1J(PtP) coupling constant of ca. 100 Hz). Furthermore
d(PO) was observed at ca. 17 ppm and implied that the
phosphoryl group was not involved in coordination with the
metal(II) centre. These observations are consistent with B
and C adopting an E-monodentate mode of binding through
either the ‘soft’ S or Se donor atom. Pasini and coworkers
recently described a series of related complexes of formula
[Pt(L-S)(dien)]q (Lsmethylsulfanyl- and methylsulfi-
nyl-acetate, benzoate and phenolate ligands) and confirmed
by NMR and IR the absence of any carboxylate interaction
with the metal centre [39,40]. The 195Pt{1H} NMR spectra
of 3 (and 4) appeared as broad, poorly resolved signals at
ca. d(Pt) y3100 ppm and in the range anticipated for com-
plexes with a PtN3S core [40,41]. The 1H NMR spectra for
1–4 (recorded in CD3OD) have chemical shifts that lie in a
very similar range, indicating congruous structures. Treat-
ment of 1 in CDCl3/CH3OH with concentrated HCl resulted
in smooth conversion to the parent acid Ph2P(O)NHP-
(S)Ph2 and [PdCl(dien)]Cl (31P{1H} NMR evidence).
The corresponding reaction with the symmetrical ligands
K[Ph2P(E)NP(E)Ph2] (EsS or Se) gave only the known
neutral metal(II) complexes [M{Ph2P(E)NP(E)Ph2-
E,E9}2] [42]. The compound [Pd{Ph2P(O)NPPh2-P}-
(dien)]PF6 (5) was likewise prepared from [PdCl-
(dien)]Cl and K[Ph2P(O)NPPh2] in 71% yield and the
spectroscopic data are in full agreement with the structure
proposed. The 31P{1H} NMR spectrum showed a pair of
doublets centred at 32.1 and 21.7 ppm (2J(PPO) 19.8 Hz)
3. Results and discussion
The cationic compounds [MCl(dien)]Cl (MsPd, Pt)are
useful precursors in which the tridentate dien ligand leaves a
single vacant coordination site for ligand exchange reactions
as illustrated by the recent synthesis of [Pt(O2CCH2SMe-
S)(dien)]Cl (A) [39]. Hence metathesis of [MCl(dien)]-
Cl with 1 equiv. of K[Ph2P(O)NP(E)Ph2] (EsS B; Es
Se C) in CH3OH, followed by addition of methanolic
[NH4][PF6] and precipitationwithwater, gavethefollowing
series of metal(II) complexes (Scheme 1): [M{Ph2P-
(O)NP(E)Ph2-E}(dien)]PF6 (MsPd, EsS 1; MsPd,
EsSe 2; MsPt, EsS 3; MsPt, EsSe 4). Compounds 1–
4 were isolated in good yields (83–88%) as air-stable,yellow
(1 and 2) orwhite (3 and 4)solids, insolubleinhydrocarbons
(e.g. toluene) and water but appreciably soluble in CH2Cl2
and CH3OH. The pertinent spectroscopicandmicroanalytical
data for these compounds are given in Tables 1 and 2 and
Scheme 1. (i) [MCl(dien)]Cl, [NH4][PF6], (ii) [MCl2(N;N)], (iii) [PdCl2(ampy)], (iv) [PdCl2(tmeda)], [NH4][PF6].
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Table 4
indicating two non-equivalent phosphorus environments.
Attempts to prepare the platinum(II) compound
[Pt{Ph2P(O)NPPh2-P}(dien)]PF6 from [PtCl(dien)]Cl
have so far proved unsuccessful.
˚
Selected bond distances (A) and angles (8) for compounds 1 and 2
1 (EsS) a
2 (EsSe)
The crystal structure of 1 (Fig. 1, Table 4) reveals an
approximate square planar environment around the palla-
dium(II) metal centre (N(3)–Pd(1)–N(4) 85.0(5), N(2)–
Pd(1)–N(3) 85.3(5), S(1)–Pd(1)–N(4) 94.5(3), S(1)–
Pd(1)–N(2) 95.0(4)8, molecule 1; N(33)–Pd(31)–N(34)
84.5(5), N(32)–Pd(31)–N(33) 84.9(5), S(31)–Pd(31)–
N(32) 94.8(3), S(31)–Pd(31)–N(34) 95.8(3)8, molecule
Pd(1)–E(1)
E(1)–P(1)
P(1)–N(1)
N(1)–P(2)
P(2)–O(2)
Pd(1)–N(2)
Pd(1)–N(3)
Pd(1)–N(4)
2.315(4) [2.334(4)]
2.053(5) [2.046(5)]
1.57(1) [1.55(1)]
1.58(1) [1.59(1)]
1.516(9) [1.512(9)]
2.05(1) [2.05(1)]
2.03(1) [2.03(1)]
2.07(1) [2.06(1)]
2.4475(7)
2.215(2)
1.604(6)
1.599(5)
1.515(5)
2.058(6)
2.061(5)
2.058(6)
˚
2) with the Pd lying 0.08 (molecule 1) and 0.05 A (molecule
Pd(1)–E(1)–P(1)
E(1)–P(1)–N(1)
P(1)–N(1)–P(2)
N(1)–P(2)–O(2)
E(1)–Pd(1)–N(2)
E(1)–Pd(1)–N(3)
E(1)–Pd(1)–N(4)
N(2)–Pd(1)–N(3)
N(2)–Pd(1)–N(4)
N(3)–Pd(1)–N(4)
100.6(2) [98.3(2)]
118.8(5) [117.7(4)]
137.9(9) [137.6(8)]
116.3(6) [115.6(5)]
95.0(4) [94.8(3)]
178.1(4) [179.7(4)]
94.5(3) [95.8(3)]
85.3(5) [84.9(5)]
168.2(4) [168.1(4)]
85.0(5) [84.5(5)]
109.20(5)
119.2(2)
129.8(3)
119.0(3)
90.67(14)
172.6(2)
102.16(14)
84.2(2)
2) out of the plane of its four donor centres. The ligandadopts
an E-monodentate coordination mode with long P–S and
short P–N bonds consistent with some degree of delocalisa-
tion. There is extensive hydrogen bonding in 1, consisting of
(i) intramolecular PO∆HN hydrogen bonding (O(2)∆
˚
N(2) 3.04, O(2)∆H(2A) 2.30 A, O(2)∆H(2A)–N(2)
165.6(2)
83.5(2)
1398, molecule 1; O(32)∆N(32) 2.84, O(32)∆H(32A)
˚
1.81 A, O(32)∆H(32A)–N(32) 1758, molecule 2), (ii)
intermolecular hydrogen bonding to CH3OH and H2O
a Equivalent parameters for thesecond molecule are given insquarebrackets.
solvate molecules (O(2)∆O(60) 2.70, O(2)∆H(60)
˚
1.64 A, O(2)∆H(60)–O(60) 1578, N(3)∆O(60*) 2.84,
˚
O(60*)∆H(3) 1.87 A, O(60*)∆H(3)–N(3) 1468,
˚
A,
N(4)∆O(33)
2.95,
N(4)∆H(33A)
2.11
N(4)∆H(33A)–O(33) 1648, molecule 1; O(32)∆O(36)
˚
2.68, O(32)∆H(36A) 1.89 A, O(32)∆H(36A)–O(36)
˚
1228, O(36)∆N(33) 2.82, O(36)∆H(33) 1.82 A,
O(36)∆H(33)–N(33) 1438, molecule 2).
The X-ray structure of 2 (Fig. 2, Table 4) shows the
palladium metal centre to be roughly square planar (N(3)–
Pd(1)–N(4) 83.5(2), N(2)–Pd(1)–N(3) 84.2(2),
N(2)–Pd(1)–Se(1) 90.67(14), N(4)–Pd(1)–Se(1)
102.16(14)8). The PdN3Se core embraces a tridentate dien
ligand and an Se-bound [Ph2P(O)NP(Se)Ph2]y ligandwith
the palladium lying approximately in the plane of its four
Fig. 2. Crystal structure of [Pd{Ph2P(O)NP(Se)Ph2-Se}(dien)]PF6P
CH3OH (PF6y anion and CH protons omitted for clarity). Hydrogen bond-
ing is indicated by thin dashed lines.
N3Se-donor atoms. The Pd(1)–Se(1) distance of 2.4475(7)
˚
A is similar to that observed in other complexes with
[Ph2P(O)NP(Se)Ph2]y, e.g. [{Pd(h3-C3H5)[m-Ph2P-
˚
(O)NP(Se)Ph2-Se]}]2 (Pd–Se 2.477(2), 2.475(2) A)
[23] but longer than that observed in cis-[Pd{Ph2P-
˚
(O)NP(Se)Ph2-O,Se}2] (Pd–Se 2.381(7), 2.383(8) A)
[26]. A comparison of bond distances and angles within the
Se(1)–P(1)–N(1)–P(2)–O(2) backbone is especially
noteworthy. The Se(1)–P(1), P(1)–N(1) and N(1)–P(2)
bond lengths indicate some degree of delocalisation within
the [Ph2P(O)NP(Se)Ph2]y ligand and are similar to those
reported for [{Pd(h3-C3H5)[m-Ph2P(O)NP(Se)Ph2-
Se]}]2 [23], [Pd{Ph2P(O)NP(Se)Ph2-Se}2(en)][24]and
Fig. 1. Crystal structure of [Pd{Ph2P(O)NP(S)Ph2-S}(dien)]PF6P
H2OP0.5CH3OH showing one of the independent cations (PF6y anion and
CH protons omitted for clarity). Hydrogen bonding is indicated by thin
dashed lines.
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701
Table 5
cis-[Pd{Ph2P(O)NP(Se)Ph2-O,Se}2] [26], whilst the P–
N–P angle (129.8(3)8) is smaller in magnitude compared
with 1 (137.9(9)8 for molecule 1; 137.6(8)8 for molecule
˚
Selected bond distances (A) and angles (8) for compound 6
Pd(1)–P(2)
Pd(1)–P(4)
P(2)–N(1)
N(1)–P(1)
P(1)–O(1)
P(4)–N(3)
N(3)–P(3)
P(3)–O(3)
Pd(1)–N(49)
Pd(1)–N(50)
2.2644(6)
2.2721(6)
1.604(2)
1.601(2)
1.492(2)
1.599(2)
1.593(2)
1.499(2)
2.145(2)
2.144(2)
˚
2). The P(2)–O(2) bond length (1.515(5) A) in 2 is similar
to that observed for Ph2P(O)NHP(S)Ph2 (average P–O
˚
1.503(4) A) which exists in the solid state as a hydrogen-
bonded polymeric chain [27]. There is a CH3OH solvate
which displays a close contact with N(3) of the coordinated
˚
dien ligand (N(3)∆O(30) 2.93, N(3)∆H(30) 2.22 A,
N(3)∆H(30)–O(30) 1448). There isalsoanintramolecular
hydrogen bond between the PO functionality and N(4)–
˚
H(4b) (N(4)∆O(2) 2.85, H(4b)∆O(2) 1.99 A, N(4)–
Pd(1)–P(2)–N(1)
P(2)–N(1)–P(1)
N(1)–P(1)–O(1)
Pd(1)–P(4)–N(3)
P(4)–N(3)–P(3)
N(3)–P(3)–O(3)
N(50)–Pd(1)–N(49)
N(50)–Pd(1)–P(2)
N(49)–Pd(1)–P(2)
N(50)–Pd(1)–P(4)
N(49)–Pd(1)–P(4)
P(2)–Pd(1)–P(4)
116.88(8)
126.89(14)
119.64(11)
116.61(8)
130.88(14)
119.92(11)
81.11(8)
172.39(6)
91.30(6)
89.41(6)
H(4b)∆O(2) 1608) and an intermolecular N(2)–
H(2b)∆O(2*) hydrogen bond (N(2)∆O(2*) 2.84,
˚
H(2b)∆O(2*) 1.96 A, N(2)–H(2b)∆O(2*) 1668).
We recently described the preparation and characterisation
of [Pd{Ph2P(O)NP(E)Ph2-E}2(en)] [24] containing two
E-monodentate bound [Ph2P(O)NP(E)Ph2]y ligands.
Using this metathetical procedure we have synthesised
the complex [Pd{Ph2P(O)NPPh2-P}2(en)] (6) from
[PdCl2(en)] and 2 equiv. of K[Ph2P(O)NPPh2] in metha-
nol. The d(PO) chemical shift for 6 is similar to that for 5
and the previously reported values for the mixed PIII/PV
ligand Ph2P(O)NHPPh2 (d(PO) 21.4 ppm) and Ph2P(O)-
NHP(O)Ph2 (d(PO) 20.7 ppm), suggesting no phosphoryl
interaction with the PdII metal centre [43].
170.47(6)
98.19(2)
In the X-ray structure of 6 (Table 5, Fig. 3) the palladium
centre is bound by two terminal [Ph2P(O)NPPh2]y ligands
and a didentate H2NCH2CH2NH2 ligandinaslightlydistorted
square planar geometry with coordination angles in the range
81.11(8)–98.19(2) and 170.47(6)–172.39(6)8. The Pd–P
˚
distances in 6 (2.264(1) and 2.272(1) A) are at the higher
end of the range found in the corresponding complexes
[Pd(o-C6H4CH2NMe2-C,N)-{Ph2P(O)NPPh2-P,O}]PCH3-
˚
OH (2.242(1) A) and [PdCl{Ph2P(O)NPPh2-P,O}(Ph2-
˚
POCH3)]P0.5CH2Cl2 (2.255(3) A) [44] but shorter than
that found in [{Pd(h3-C3H5)[m-Ph2P(O)NPPh2-P,O]}2]
˚
(2.293(1) A) [45]. The P–N bond lengths in 6 (P(1)–N(1)
1.601(2), N(1)–P(2) 1.604(2), P(3)–N(3) 1.593(2),
Fig. 3. Crystal structure of [Pd{Ph2P(O)NPPh2-P}2(en)]PH2O (only the
ipso and methylene carbons and solvent are shown for clarity). Hydrogen
bonding is indicated by thin dashed lines.
˚
N(3)–P(4) 1.599(2) A) are similar to those described pre-
viously for metal complexes with [Ph2P(O)NPPh2]y and
indicate some degree of delocalisation within the P–N–P
backbone. The P(1)–O(1) and P(3)–O(3) bond lengths
A second intermolecular N–H∆O hydrogen bond is also
observed between H(49B) and an adjacent water molecule
˚
(1.492(2) and 1.499(2) A) are similar in magnitude to that
˚
observed for Ph2P(O)NHPPh2 (1.508(2) A) which exists
˚
(N(49)∆O(60A) 3.15, H(49B)∆O(60A) 2.29 A and
in the solid state as a hydrogen-bonded dimer pair [43]. Both
[Ph2P(O)NPPh2]y ligands are involved in intramolecular
N–H∆OP hydrogen bonding with H2NCH2CH2NH2
N(49)–H(49B)∆O(60A) 1468).
Using more forcing conditions (reflux, 5 h) we were able
to prepare the platinum(II) complexes [Pt{Ph2P(O)NP-
(E)Ph2-E}2(C6H14N2)] (EsS 7; EsSe 8) 3 whereas
attempts to obtain analogues with [Ph2P(E)NP(E)Ph2]y
gave only [M{Ph2P(E)NP(E)Ph2-E,E9}2]. Reaction of B
with [PtCl2(py)2] (2:1 molar ratio) in refluxing CH3OH
˚
(N(49)∆O(1) 2.85, H(49A)∆O(1) 1.92 A and N(49)–
H(49A)∆O(1) 1588; N(50)∆O(3) 2.80, H(50B)∆O(3)
˚
1.85 A and N(50)–H(50B)∆O(3) 1628). This leads to a
spirocyclic arrangement composed of two seven-membered
rings about a central palladium(II) metal centre. An inter-
molecular O–H∆O hydrogen bond is observed between
O(3) and H(60A) of a water molecule (O(3)∆O(60)2.77,
3 Crystals of 7 have also been isolated but refinement of the X-ray data
only resulted in a value of Rs13.2%. Nevertheless the refinement again
indicated an S-bound arrangement of the [Ph2P(O)NP(S)Ph2]y ligands.
˚
O(3)∆H(60A) 1.79 A and O(3)∆H(60A)–O(60) 1768).
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gave, after solvent evaporation, a solid whose 31P{1H} NMR
spectrum clearly showed a mixture of phosphorus containing
species. Two major compounds identified were [Pt{Ph2P-
(O)NP(S)Ph2-O,S}2(py)2] (d(PS) 25.7 ppm, 1J(PtP)
88 Hz; d(PO) 11.3 ppm, 2J(PSPO) 5 Hz) and Ph2P(O)NHP-
(S)Ph2, but attempts to isolate the platinum(II) complex by
recrystallisation have so far proved unyielding.
The reaction of [PdCl2(ampy)] with B (and C) was of
particular interest since it has previously been shown that,
depending on the choice of [PdCl2(amine)2], different
products were obtained. Hence when [PdCl2(bipy)] was
employed the O,E-chelate complexes [Pd{Ph2P(O)NP-
(E)Ph2-O,E}(bipy)]PF6 were isolated in high yields, but
in contrast [PdCl2(en)] gave [Pd{Ph2P(O)NP(E)Ph2-
O,E}2(en)] with E-monodentate ligands [24,25]. Trans-
metallation of B (or C) with [PdCl2(ampy)] in methanol
gave the neutral compounds [Pd{Ph2P(O)NP(E)Ph2-
O,E}2(ampy)] (EsS 9; EsSe 10) and hence the reactivity
seen hereresemblesthatof[PdCl2(en)]. Four31Presonances
were observed in the 31P{1H} NMR spectra of 9 (and 10)
consistent with four unique phosphorus environments (i.e.
two E-monodentate [Ph2P(O)NP(E)Ph2]y ligands trans to
the divergent nitrogen donor atoms of ampy). Furthermore
d(PO) was indicative of a ‘dangling’ PO functionality(Table
2).
Fig. 4. Crystal structure of [Pd{Ph2P(O)NP(S)Ph2-S}2(ampy)]PH2O
showing one of the independent molecules (solvent and CH protons omitted
for clarity). Hydrogen bonding is indicated by thin dashed lines.
Table 6
a
˚
Selected bond distances (A) and angles (8) for compound 9
Pd(1)–S(1)
Pd(1)–S(3)
S(1)–P(1)
S(3)–P(3)
P(1)–N(1)
P(3)–N(2)
N(1)–P(2)
N(2)–P(4)
P(2)–O(2)
P(4)–O(4)
Pd(1)–N(3)
Pd(1)–N(4)
2.304(2) [2.299(2)]
2.324(2) [2.314(2)]
2.039(3) [2.028(3)]
2.042(3) [2.032(3)]
1.590(6) [1.579(6)]
1.575(6) [1.557(6)]
1.602(6) [1.596(6)]
1.589(6) [1.600(6)]
1.494(5) [1.499(5)]
1.485(5) [1.495(5)]
2.070(7) [2.071(7)]
2.030(6) [2.048(6)]
The X-ray structure of 9 (Fig. 4, Table 6) reveals two
independent molecules and shows the palladium metal cen-
tres to be roughly square planar (N(3)–Pd(1)–N(4)
82.2(3), N(4)–Pd(1)–S(1) 90.7(2), S(1)–Pd(1)–S(3)
91.74(8), N(3)–Pd(1)–S(3) 95.5(2)8, molecule 1;
N(63)–Pd(2)–N(64) 82.1(3), N(64)–Pd(2)–S(61)
90.1(2), S(61)–Pd(2)–S(63) 92.85(8), N(63)–Pd(2)–
S(63) 94.9(2)8, molecule 2). The PdN2S2 core is composed
of a didentate 2-aminomethylpyridine ligand and two S-
bound [Ph2P(O)NP(S)Ph2]y ligands with the palladium
lying essentially in the plane of its four constituents (for
both independent molecules). The Pd(1)–N(3) distance
Pd(1)–S(1)–P(1)
Pd(1)–S(3)–P(3)
S(1)–P(1)–N(1)
S(3)–P(3)–N(2)
P(1)–N(1)–P(2)
P(3)–N(2)–P(4)
N(1)–P(2)–O(2)
N(2)–P(4)–O(4)
N(3)–Pd(1)–N(4)
N(3)–Pd(1)–S(1)
N(3)–Pd(1)–S(3)
N(4)–Pd(1)–S(1)
N(4)–Pd(1)–S(3)
S(1)–Pd(1)–S(3)
103.86(12) [102.45(12)]
104.53(11) [104.24(12)]
119.9(3) [118.8(3)]
118.7(3) [121.1(3)]
132.6(5) [135.7(5)]
137.2(4) [138.4(4)]
117.0(3) [117.5(3)]
121.0(4) [120.6(3)]
82.2(3) [82.1(3)]
172.4(2) [172.2(2)]
95.5(2) [94.9(2)]
90.7(2) [90.1(2)]
177.2(2) [176.9(2)]
91.74(8) [92.85(8)]
˚
(2.070(7) for molecule 1; 2.071(7) A for molecule 2) is
longer than that reported for [Pd(cbdca)(ampy)]P2H2O
˚
(1.989(12) A) (cbdcascyclobutane-1,1-dicarboxylate)
whereas the Pd(1)–N(4) bond length (2.030(6) for mole-
˚
cule 1; 2.048(6) A for molecule 2) is similar to that in
a Equivalent parameters for thesecond molecule are given insquarebrackets.
˚
[Pd(cbdca)(ampy)]P2H2O (2.024(12) A) [34]. The Pd–
˚
S distances of 2.304(2) and 2.324(2) A (molecule 1) and
˚
molecule 2) forming a pseudo eight-membered ring. This
may account for the enlarged P(3)–N(2)–P(4) (137.2(4),
molecule 1; 138.4(4)8, molecule 2) angle with respect to
P(1)–N(1)–P(2) (132.6(5), molecule 1; 135.7(5)8, mol-
ecule 2). There is also additional intermolecular hydrogen
bonding with a water solvent molecule (N(4)∆O(71) 3.06,
2.299(2) and 2.314(2) A (molecule 2) are similar to those
in 1 (2.315(4), molecule 1; 2.334(4), molecule 2) and 11
˚
(2.3315(8) A). Within the S–P–N–P–O backbone there is
evidence for some electron delocalisation with long S–P and
short P–N/N–P bonds. The P–O bond lengths (1.494(5),
˚
˚
1.485(5) A, molecule 1; 1.499(5), 1.495(5) A, molecule
2) are similar to that observed in Ph2P(O)NHP(S)Ph2 [27].
One of the [Ph2P(O)NP(S)Ph2]y ligands is involved in
intramolecular hydrogen bonding with H2NCH2C5H3N
˚
H(4B)∆O(71) 2.21 A, N(4)–H(4B)∆O(71) 1568, mol-
˚
ecule 1; N(64)∆O(72) 3.03, H(64B)∆O(72) 2.15 A,
N(64)–H(64B)∆O(72) 1668, molecule 2).
˚
(N(4)∆O(2) 2.85, H(4C)∆O(2) 1.97 A, N(4)–
We have also attempted to prepare E-monodentate ana-
logues of [PdCl2(tmeda)] but were only able to isolate the
O,E-chelate complexes [Pd{Ph2P(O)NP(E)Ph2-O,E}-
H(4C)∆O(2) 1648, molecule 1; N(64)∆O(62) 2.85,
˚
H(64C)∆O(62) 1.96 A, N(64)–H(64C)∆O(62) 1668,
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M.B. Smith, A.M.Z. Slawin / Polyhedron 19 (2000) 695–704
703
(tmeda)]PF6 (EsS 11; EsSe 12) in high yields ()90%).
´
Lopez and coworkers recently described the synthesis of
the cationic complex [Pd(acac)(tmeda)]q (D) from the
hydroxo palladium dimer [{Pd(m-OH)(tmeda)}2]2q and
the protic acid Hacac [46]. The 31P{1H} NMR spectra of 11
and 12 showed that d(PO) was shifted downfield by ca. 20
ppm with respect to 1–4, 7–10, suggesting an O,E-chelation
mode of binding. This was further corroborated by 1H NMR
which showed two well resolved N(CH3)2 resonances at
2.63, 2.39 (for 11) and 2.60, 2.46 ppm (for 12). Further-
more, the IR spectra of 11 and 12 showed the absence of nPdCl
(326 cmy1) for [PdCl2(tmeda)], consistent with meta-
thesis of both Pd–Cl ligands by an O,E-chelating
[Ph2P(O)NP(E)Ph2]y anion. The reaction of [PdCl2-
(tmeda)] with 2 equiv. of B in CH3OH was monitored by
31P{1H} NMR spectroscopy and showed that both 11 and
unreacted B were present with no evidence for a neutral
complex such as [Pd{Ph2P(O)NP(S)Ph2-S}2(tmeda)].
This difference in reactivity may be ascribed to the use of a
more sterically hindered diamine, the absence of suitable
centres for hydrogen bonding or a combination of both fac-
tors. Attempts to prepare a corresponding complex from
[PdCl2(tmeda)] and K[Ph2P(O)NPPh2] (1:1 molar ratio)
gave instead the known bis homoleptic compound cis-
[Pd{Ph2P(O)NPPh2-P,O}2] [43].
Fig. 5. Crystal structure of [Pd{Ph2P(O)NP(S)Ph2-O,S}(tmeda)]PF6
(CH protons omitted for clarity).
Table 7
˚
Selected bond distances (A) and angles (8) for compound 11
Pd(1)–S(1)
Pd(1)–O(2)
S(1)–P(1)
P(1)–N(1)
N(1)–P(2)
P(2)–O(2)
Pd(1)–N(25)
Pd(1)–N(26)
2.3315(8)
2.027(3)
2.0359(10)
1.573(3)
1.587(3)
1.529(3)
2.055(3)
2.104(3)
Pd(1)–S(1)–P(1)
S(1)–P(1)–N(1)
P(1)–N(1)–P(2)
N(1)–P(2)–O(2)
P(2)–O(2)–Pd(1)
O(2)–Pd(1)–N(25)
O(2)–Pd(1)–N(26)
N(25)–Pd(1)–N(26)
O(2)–Pd(1)–S(1)
N(25)–Pd(1)–S(1)
N(26)–Pd(1)–S(1)
104.35(4)
116.96(11)
128.0(2)
118.58(14)
134.2(2)
172.09(12)
87.22(10)
85.89(12)
96.05(7)
91.31(10)
171.52(7)
The X-ray structure of 11 (Fig. 5, Table 7) shows the
palladium metal centre to be surrounded by a chelating
Me2NCH2CH2NMe2 and [Ph2P(O)NP(S)Ph2]y ligand in a
slightly distorted square planar geometry with coordination
angles in the range 85.89(12)–96.05(7) and 171.52(7)–
ligands are readily accessible via transmetallation reactions.
In contrast the use of symmetrical anions [Ph2P(E)-
NP(E)Ph2]y leads exclusively to the formation of
[M{Ph2P(E)NP(E)Ph2-E,E9}2] with displacement of all
chloride and amine ligands. This disparity can presumably
be traced to the dissimilar donor properties of the asymmet-
rical ligands. In this context the rare coordination mode dis-
played by [Ph2P(O)NP(E)Ph2]y may well mean that these
ligands have a role in catalysis and in the synthesis of
heterobimetallic compounds.
˚
172.09(12)8. The palladium lies 0.05 A out of the plane of
its four N2OS donor constituents. The Pd(1)–N bond lengths
reflect the nature of the trans donor atom (Pd(1)–N(25)
˚
2.055(3), P trans to O; Pd(1)–N(26) 2.104(3) A, P trans
to S). Furthermore Pd(1)–N(25) is at the lower end of
the range previously reported for the aryl- and alkoxide
complexes cis-[Pd(CH3)(OR)(tmeda)] (2.060(5) (Rs
˚
p-C6H4NO2) to 2.080(2) A (RsCH(CF3)2)) [47]. The
six-membered Pd–O–P–N–P–S ring conformation in 11 can
be most readily described as pseudo-boat with S(1) at the
˚
Supplementary data
prow (0.88 A above the plane) and P(2) at the stern (0.21
˚
A above the plane) of the ‘boat’. In 11 the Pd(1)/P(1)/
N(1)/O(2) atoms are approximately coplanar (maximum
deviation from the mean plane 0.2 A for N(1)). Within the
PdOP2NS metallacycle the bond lengths are consistent with
a fair degree of delocalisation.
Crystallographic data (excluding structure factors) for the
structures in this paper have been deposited with the Cam-
bridge Crystallographic Data Centre as supplementary pub-
lication nos. CCDC 136068 (for 1), 136069 (for 2), 136070
(for 6), 136071 (for 9) and 136072 (for 11). Copies of the
data can be obtained, free of charge, on application to CCDC,
˚
We have shown that new complexes of palladium(II) and
platinum(II) with E-monodentate [Ph2P(O)NP(E)Ph2]y
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704
M.B. Smith, A.M.Z. Slawin / Polyhedron 19 (2000) 695–704
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