Amine-functionalised aminophosphines: Synthesis, reversible co-ordination to platinum and use in heteronuclear dimer formation

Article abstract of DOI:10.1039/b005899h

Amine functionalised aminophosphines Ph₂PN(R)CH₂CH₂NMe₂ (R = H L1 or Me Lz) were prepared from the reaction of PPh₂Cl with NHRCH₂CH₂NMe₂ in the presence of the base H-butyllithium (L¹) or triethylamine (L²). Reaction of two equivalents of L14 with [PtCl2(cod)] gave the complexes c-[PtCl2L2] (L = L1 1 or L2 2), which were shown to be fluxional with one of the amine groups reversibly co-ordinating to displace a chloride. Removal of a chloride in 1 by metathesis gave cis-[PtCl(V-P)(Ll-P,N)]PF6 3 which was not fluxional on the NMR timescale. Reaction of one equivalent of L₂ with [PtCl2(cod)J gave the complex cis-[PlC₂(i?-P,N)] 4 in which L2 is acting as a bidentate ligand. The reaction of L₂ with [{Pt(dmba)(u-Cl)}₂] (Hdmba = W.W-dimethylbenzylamine) gave [Pt(dmba)C1(L²)] 5, which exists as a mixture of the two geometric isomers. Reaction of 5 with T1PF6 gave [Pt(dmba)(L2-P,A')]PF₆ 6 as a single isomer in which the phosphorus atom is co-ordinated trans to the AN-dimethylbenzylamine nitrogen atom. Complex 2 reacts with CoCl₂-6H₂O and ZnCl² to give m-[(L²-P,AOClPt(n-L²)MCl₃] (M = Co 7 or Zn 8). The zwitterionic structure of 7 was confirmed by a single-crystal X-ray analysis, which showed no metal-metal interaction between the platinum and cobalt centres. The Royal Society of Chemistry 2000.

Full text of DOI:10.1039/b005899h

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Amine-functionalised aminophosphines: synthesis, reversible
co-ordination to platinum and use in heteronuclear dimer
formation
Andrew D. Burrows,* Mary F. Mahon and Mark T. Palmer
Department of Chemistry, University of Bath, Claverton Down, Bath, UK BA2 7AY.
E-mail: a.d.burrows@bath.ac.uk
Received 21st July 2000, Accepted 8th September 2000
First published as an Advance Article on the web 2nd October 2000
Amine functionalised aminophosphines Ph2PN(R)CH2CH2NMe2 (R = H L1 or Me L2) were prepared from the
reaction of PPh2Cl with NHRCH2CH2NMe2 in the presence of the base n-butyllithium (L1) or triethylamine (L2).
Reaction of two equivalents of L1,2 with [PtCl2(cod)] gave the complexes cis-[PtCl2L2] (L = L1 1 or L2 2), which
were shown to be fluxional with one of the amine groups reversibly co-ordinating to displace a chloride. Removal
of a chloride in 1 by metathesis gave cis-[PtCl(L1-P)(L1-P,N)]PF6 3 which was not fluxional on the NMR timescale.
Reaction of one equivalent of L2 with [PtCl2(cod)] gave the complex cis-[PtCl2(L2-P,N)] 4 in which L2 is acting as a
bidentate ligand. The reaction of L2 with [{Pt(dmba)(µ-Cl)}2] (Hdmba = N,N-dimethylbenzylamine) gave [Pt(dmba)-
Cl(L2)] 5, which exists as a mixture of the two geometric isomers. Reaction of 5 with TlPF6 gave [Pt(dmba)(L2-P,N)]-
PF6 6 as a single isomer in which the phosphorus atom is co-ordinated trans to the N,N-dimethylbenzylamine
nitrogen atom. Complex 2 reacts with CoCl2ؒ6H2O and ZnCl2 to give cis-[(L2-P,N)ClPt(µ-L2)MCl3] (M = Co 7
or Zn 8). The zwitterionic structure of 7 was confirmed by a single-crystal X-ray analysis, which showed no
metal–metal interaction between the platinum and cobalt centres.
was used as the base, as in the synthesis of ether-functionalised
Introduction
aminophosphines such as Ph2PNHCH2CH2OMe.1 However,
Aminophosphines of general formula R2PNRЈRЉ have
been relatively neglected as ligands, despite a number of
potentially attractive features. The mild conditions required for
formation of the P–N bond allow facile incorporation of
the reaction of PPh2Cl with NH2CH2CH2NMe2 in the presence
of NEt3 gave, in addition to L1, appreciable amounts of (Ph2P)2-
NCH2CH2NMe2, from which it proved difficult to isolate L1.
Using the alternative synthetic strategy of low temperature
additional functionalities, and problems caused by the sensitiv-
amine deprotonation with BuLi, followed by reaction of the
ity of this bond to hydrolysis are often eliminated on co-
lithiated amine with PPh2Cl, the desired product was formed
ordination.1 In recent years there has been a growing interest
without contamination by (Ph2P)2NCH2CH2NMe2, and from
in developing functionalised aminophosphines, and ligands
this route it proved possible to isolate L1 in reasonable yield. As
incorporating ketones,2–4 ethers,1 phosphinites5,6 and additional
with the ether-functionalised aminophosphines, care needs to
aminophosphines7–11 have been prepared and studied. As far as
be taken to exclude water from the reaction mixtures to prevent
nitrogen-donor functionalities are concerned, pyridines12,13 and
formation of Ph2PP(O)Ph2.1
imines14,15 have been incorporated into these ligands, though
Ligand L1 gave a 31P chemical shift of δ 41.6, very close to
amines16 have received less attention. In this paper we report
those observed for both Ph2PNHCH2CH2OMe (δ 42.0)1 and
the synthesis and platinum co-ordination chemistry of tertiary
amine functionalised aminophosphines. The potential of these
Ph2PNHPPh2 (δ 42.1).17 The chemical shift for L2 was observed
downfield of this, at δ 65.4. A similar chemical shift was
ligands to display hemilabile co-ordination and bridge hetero-
observed for the diphosphine Ph2PN(CH2Ph)CH2CH2N(CH2-
nuclear metal centres is demonstrated.
Ph)PPh2 (δ 65.9)9 suggesting that the difference in δ(P) is
primarily due to the presence of an alkyl group rather than
1
a hydrogen atom on the aminophosphine nitrogen atom. H
NMR spectra for L1 and L2 were as expected, with the NH
proton in L1 observed as a broad multiplet at δ 2.49.
Results and discussion
(i) Ligand synthesis
The amine-functionalised aminophosphines Ph2PN(R)CH2-
CH2NMe2 (R = H L1 or Me L2) were prepared in good yield
from PPh2Cl and NHRCH2CH2NMe2 in the presence of base
(Scheme 1) and characterised on the basis of multinuclear
NMR spectroscopy and microanalysis. For L2, triethylamine
The diphosphine (Ph2P)2NCH2CH2NMe2 was observed in
the 31P-{1H} NMR spectrum at δ 64.2. The reaction of
NH2CH2CH2NMe2 with two equivalents of PPh2Cl in the pres-
ence of NEt3 led to an increase in the proportion of (Ph2P)2-
NCH2CH2NMe2 formed, though this diphosphine was not
Scheme 1 (i) PPh2Cl, NEt3, THF, (ii) PPh2Cl, BuLi, THF, Ϫ78 ЊC.
DOI: 10.1039/b005899h
J. Chem. Soc., Dalton Trans., 2000, 3615–3619
This journal is © The Royal Society of Chemistry 2000
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Table 1 31P-{1H} NMR data for L1,2 and complexes 1–6, 8 and 9
between them is slow on the NMR timescale, as is exchange
between the phosphines in cis-[PtCl(L-P)(L-P,N)]Cl. The H
NMR spectra of 1 and 2 were broad and uninformative both at
room temperature and at Ϫ50 ЊC.
1
1J(P,Pt)/
2J(P,P)/
Hz
Compound
δ(31P)
Hz
These observations for ligands L1 and L2 are in contrast to
those previously reported for the phosphines Ph2PCH2CH2-
CH2NMe2 (L3) and Ph2PCH2CH2NMe2 (L4).18 Reaction of L3
with [PtCl2(cod)] gave cis-[PtCl2(L3)2], for which no fluxionality
was reported despite the potential formation of a 6-membered
chelate ring analogous to those in 1 and 2 at low temperature.
In contrast, reaction of L4 with [PtCl2(cod)] gave only cis-
[PtCl(L4-P)(L4-P,N)]Cl. The differences between L3 and L4 can
be related to the relative stabilities of 6- and 5-membered
chelate rings.
L1 Ph2PNHCH2CH2NMe2
L2 Ph2PNMeCH2CH2NMe2
41.6
65.4
36.0a
1
cis-[PtCl2(L1)2]
cis-[PtCl2(L2)2]
3954
38.4, 29.9b 3953, 3601 18
2
50.1a
49.6, 46.9c 4209, 3202
40.3, 33.2e 4038, 3587 20
32.8
66.4
80.3
51.2e
3904
d
3
4
cis-[PtCl(L1-P)(L1-P,N)]PF6
cis-[PtCl2(L2-P,N)]
4175
4618
2126
4880
4196, 3476
3796, 3800 27
5a [Pt(dmba)Cl(L2)]
5b
6
8
9
[Pt(dmba)(L2-P,N)]PF6
Further evidence for the presence of cis-[PtCl(L-P)(L-P,N)]ϩ
(L = L1 or L2) in solution came from the reaction of complex 1
with TlPF6 which yielded cis-[PtCl(L1-P)(L1-P,N)]PF6 3. The
chemical shifts and the coupling constants in the 31P-{1H}
NMR spectrum were comparable to those in the low temper-
ature spectra of 1 (Table 1) suggesting similar ligand arrange-
ments. However, in contrast to 1, the spectra of 3 were sharp
confirming that removal of the chloride anion prevents the
fluxional processes from occurring. The chloride can also be
abstracted using NH4PF6 or NaBF4, though it has not proved
possible to substitute the second halide to afford complexes of
the type cis-[Pt(L1-P,N)2]2ϩ. Similar observations were made
with the phosphine L3, where cis-[PtCl(L3-P)(L3-P,N)]BF4 was
the only product from the reaction of cis-[PtCl2(L3)2] with an
excess of AgBF4.18
cis-[(L2-P,N)ClPt(µ-L2)ZnCl3] 47.6, 45.4
d
[Pt(O2C6H3But)(L2)2]
55.4, 54.5
a Recorded at 25 ЊC. b Additional features observed at Ϫ50 ЊC. c Addi-
tional features observed at Ϫ40 ЊC. d Could not be determined due to
broadness. e Septet at δ Ϫ143.5 also observed [1J(P,F) 711 Hz, PF6Ϫ].
isolated from the reaction mixture. Formation of diphosphines
was not observed from the reaction of aminoethers with one
equivalent of PPh2Cl,1 so it is possible that the increased
basicity of the tertiary amine group aids deprotonation of the
aminophosphine nitrogen atom.
(ii) Platinum(II) complexes
The reaction of two equivalents of L1 or L2 with [PtCl2(cod)] in
dichloromethane gave the complexes cis-[PtCl2L2] (L = L1 1 or
L2 2) (Scheme 2), which were isolated in reasonable yield and
The reaction of [PtCl2(cod)] with one equivalent of L2 gave
the complex cis-[PtCl2(L2-P,N)] 4 in which the aminophosphine
ligand is bidentate (Scheme 2). Complex 4 was characterised on
1
the basis of 31P and H NMR spectroscopy and microanalysis.
The formation of 4 again illustrates the difference in behaviour
between L2 and L3, as the reaction of L3 with [PtCl2(cod)] gave
only cis-[PtCl2(L3)2], with no evidence for cis-[PtCl2(L3-P,N)].18
As with the results above, this indicates the easier formation of
a 6-membered chelate ring in which the phosphorus atom is
bonded to an sp2 hybridised nitrogen atom as opposed to a sp3
hybridised carbon atom.
Ligand L2 reacts with [{Pt(dmba)(µ-Cl)}2] (Hdmba = N,N-
dimethylbenzylamine), cleaving the halide bridges, to give
[Pt(dmba)Cl(L2)] 5 (Scheme 3). Complex 5 is formed as an
approximately 1:1 mixture of the two potential isomers with
the phosphorus atom trans to either the nitrogen (5a) or carbon
Scheme 2 (i) L (1 equivalent), (ii) L (2 equivalents), (iii) TlPF6, (iv)
CoCl2.
characterised by NMR and IR spectroscopy and microanalysis.
The room temperature 31P-{1H} NMR spectra of 1 and 2 con-
sisted of broad singlets with δ(P) 36.0 and 50.1 respectively. In
1
both cases the magnitude of the J(Pt,P) coupling constant,
3954 Hz for 1 and 3904 Hz for 2, is typical for a phosphine
ligand trans to chloride. The broadness of the signals suggested
the presence of fluxionality, and on recording the spectra at
Ϫ40 or Ϫ50 ЊC two distinct resonances each with 195Pt satellites
were observed in addition to the singlet observed at room tem-
perature (Table 1). These additional features are indicative of a
structure in which the two phosphorus atoms are no longer
equivalent. This is also supported by the observation of 2J(P,P)
coupling for 1, though due to the broadness of the resonances
analogous coupling was not observed for 2. The inequivalence
of the phosphorus nuclei is consistent with the presence of
structures in which one ligand is unidentate P-co-ordinated and
the other is bidentate P,N-co-ordinated, suggesting that the
species cis-[PtCl2(L-P)2] and cis-[PtCl(L-P)(L-P,N)]Cl are both
present in solution at low temperature and that exchange
Scheme 3 (i) L; (ii) TlPF6.
3616
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Table 2 Selected bond lengths (Å) and angles (Њ) for complex 7
Pt(1)–N(2)
Pt(1)–P(1)
Pt(1)–P(2)
Pt(1)–Cl(1)
Co(1)–N(4)
2.167(5)
2.247(2)
2.271(2)
2.365(2)
2.118(6)
Co(1)–Cl(3)
Co(1)–Cl(4)
Co(1)–Cl(5)
P(1)–N(1)
2.214(2)
2.246(2)
2.249(2)
1.673(5)
1.657(5)
P(2)–N(3)
N(2)–Pt(1)–P(1)
N(2)–Pt(1)–P(2)
P(1)–Pt(1)–P(2)
N(2)–Pt(1)–Cl(1)
P(1)–Pt(1)–Cl(1)
P(2)–Pt(1)–Cl(1)
90.85(13)
170.38(13)
97.44(6)
88.23(13)
169.30(6)
84.53(6)
N(4)–Co(1)–Cl(3)
N(4)–Co(1)–Cl(4)
Cl(3)–Co(1)–Cl(4)
N(4)–Co(1)–Cl(5)
Cl(3)–Co(1)–Cl(5)
Cl(4)–Co(1)–Cl(5)
104.8(2)
108.7(2)
115.71(10)
106.9(2)
113.91(9)
106.44(8)
N(1) and N(2) which, at 354 and 360Њ respectively, show a high
degree of sp2 character. The two P–N bond lengths are similar,
so involvement in the six-membered chelate ring has not signifi-
cantly affected the P–N bond distance, though the P(1)–N(1)–
C(26) angle within the chelate ring is reduced [119.1(5)Њ] relative
to the equivalent angle in the P-bonded ligand [123.1(4)Њ]. Mol-
ecules of 7 stack along the b axis with intermolecular Pt ؒ ؒ ؒ Co
distances of 6.3 Å, similar to those observed within the indi-
vidual molecules (6.0 Å). Closer intermolecular contact of the
metal centres is prevented by the presence of the phenyl groups
on the ligands.
Fig. 1 Molecular structure of complex 7 with the thermal ellipsoids
represented at the 30% probability level.
Complex 7 dissolves in methanol to give a pale pink solution,
suggesting that co-ordination of solvent molecules leads to
octahedral geometry around the cobalt centre. This solvent
co-ordination is reversible and on removal of methanol in vacuo
the complex reverts to the initial blue colour. The molecular
ion of 7 was not observed in the FAB mass spectrum; the
highest molecular mass peak observed was at m/z 803, and can
be assigned to [M Ϫ CoCl3]ϩ. Microanalytical data suggest
the zinc compound to be the isostructural species cis-[(L2-
P,N)ClPt(µ-L2)ZnCl3] 8. The 31P-{1H} NMR spectrum of 8
was broad, but both the chemical shifts and the coupling
constants are similar to those observed in the low temperature
spectrum of 2 suggesting similar geometries around the plat-
inum centre, i.e. one bidentate and one unidentate L2 ligand
and a chloride.
atom of the dmba ligand (5b). The 31P-{1H} signals can readily
be assigned on the basis of the J(Pt,P) coupling constants,
1
which reflect the differing trans influences of the two donors.
Thus 5a is observed at δ 66.4 (1J(Pt,P) = 4618 Hz) and 5b at
δ 80.3 (1J(Pt,P) = 2126 Hz). These assignments are confirmed
by observation of 4J(P,H) coupling in the 1H NMR spectrum19
for the isomer with the larger 1J(Pt,P) coupling constant, which
can be isolated on recrystallisation. Reaction of complex 5 with
TlPF6 gave [Pt(dmba)(L2-P,N)]PF6 6, which was characterised
1
on the basis of 31P-{1H} and H NMR spectroscopy. Only one
1
isomer of 6 was observed, and the value of J(Pt,P) suggests
that the compound has the phosphorus atom trans to the
nitrogen atom of the dmba ligand (Scheme 3).
In order to investigate the possibility of both aminophos-
phine ligands bridging to the cobalt centre, giving species of
general formula [X2Pt(µ-L2)2CoCl2] it was decided to use a
bidentate dianionic ligand in order to prevent halide transfer
from platinum to cobalt. One potential ligand for this is a
catecholate, and consequently [Pt(O2C6H3But)(L2)2] 9 was pre-
pared from the reaction between L2 and [Pt(O2C6H3But)(cod)],
with the latter formed in situ from [PtCl2(cod)], 4-tert-
butylcatechol and the base DBU (1,8-diazabicyclo[5.4.0]undec-
7-ene).20 Complex 9 was isolated as an orange powder and
characterised on the basis of microanalysis and 31P-{1H} and
1H NMR spectroscopy. The 31P-{1H} NMR spectrum shows an
AB system with 195Pt satellites, the second order spectrum a
result of the similar chemical environments of the two phos-
phorus atoms, which differ only due to the presence of the tert-
butyl group on the catecholate. The reaction of 9 with CoCl2ؒ
6H2O gave a blue crystalline product, but this did not prove to
be a doubly bridged species. Instead, the product was identified
on the basis of microanalysis and IR spectroscopy as 7.
Hence, reaction of 9 with CoCl2ؒ6H2O leads to displacement
of catecholate by chloride.
(iii) Mixed metal complexes
Since complexes 1, 2 and 3 contain unco-ordinated amine
nitrogen atoms they can potentially act as ligands to other
metal centres, thus allowing formation of heteronuclear dimers
through bridging aminophosphine ligands. In order to assess
this 2 was treated with one equivalent of either CoCl2ؒ6H2O or
ZnCl2 in acetone. Recrystallisation of the products from
dichloromethane–hexane gave blue and colourless crystals
respectively, that in the case of cobalt were suitable for a single
crystal X-ray analysis. The X-ray study confirmed the identity
of this compound as the zwitterionic complex cis-[(L2-P,N)-
ClPt(µ-L2)CoCl3] 7 for which the platinum centre is formally
cationic and the cobalt centre anionic. The asymmetric unit,
shown in Fig. 1, demonstrates the different co-ordination
modes of the two aminophosphine ligands, with one chelating
to the platinum centre in a bidentate mode, and the other bridg-
ing between the platinum and cobalt centres. Selected bond
lengths and angles are given in Table 2.
The co-ordination geometry around the platinum centre is
distorted square planar, with cis angles ranging from 84.53(6)
to 97.44(6)Њ, whereas that around the cobalt is distorted
tetrahedral with angles ranging from 104.8(2) to 115.7(1)Њ. The
shorter Pt(1)–P(1) bond length relative to the Pt(1)–P(2)
distance reflects the relative trans influence of the chloride and
Conclusion
The results described demonstrate that amine-functionalised
aminophosphines can readily be prepared and can act as
both uni- and bi-dentate ligands on platinum. Moreover,
compounds containing P-bound ligands have unco-ordinated
nitrogen atoms which can act as ligands to other metals thus
affording heteronuclear bimetallic compounds such as 7.
1
tertiary amine ligands, which is also mirrored in the J(Pt,P)
coupling constants for complex 3. The two P–N bond distances
are shorter than expected for a single bond, suggesting a degree
of double bond character, in common with other aminophos-
phine ligands. This is also reflected in the sum of angles around
J. Chem. Soc., Dalton Trans., 2000, 3615–3619
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N, 6.19. C34H46Cl2N4P2PtؒC4H8O requires C, 50.1; H, 5.98; N,
6.15%). H NMR (CD2Cl2, ϩ25 ЊC): δ 7.46–7.20 (m, Ar), 3.20
Experimental
1
Reactions were routinely carried out using Schlenk-line tech-
niques under pure dry dinitrogen using dry dioxygen-free
solvents unless noted otherwise. Microanalyses (C, H and N)
were carried out by Mr Alan Carver (University of Bath
Microanalytical Service). Infrared spectra were recorded on a
Nicolet 510P spectrometer as KBr pellets, Nujol mulls or
dichloromethane solutions in KBr cells. 1H, 13C-{1H} and
31P-{1H} NMR spectra were recorded on a JEOL JNM-EX270
spectrometer operating at 270 MHz referenced to TMS, 67.8
MHz referenced to TMS and 109.4 MHz referenced to H3PO4,
respectively. FAB mass spectra were recorded on a VG
AutoSpec-Q spectrometer using 3-nitrobenzyl alcohol as the
matrix. [PtCl2(cod)]21 and [{Pt(dmba)(µ-Cl)}2]22 were prepared
by standard literature methods. 31P-{1H} NMR data are given
in Table 1.
(m (br), 2 H, CH2NP), 2.68 (m (br), 2 H, CH2N), 2.51 (d, 3 H,
3J(H,P) 10 Hz, CH3NP) and 2.39 (s (br), 6 H, CH3N).
cis-[PtCl(L1-P)(L1-P,N)]PF6 3. TlPF6 (0.260 g, 0.75 mmol)
was added with stirring to a solution of complex 1 (0.200 g, 0.25
mmol) in dichloromethane. After 3 hours the solution was
filtered, the solvent removed in vacuo and the product recrystal-
lised from dichloromethane–pentane, then methanol–diethyl
ether. Yield 0.16 g (69%) (Found: C, 41.6; H, 4.71; N, 5.84.
C32H42ClF6N4P3Pt requires C, 41.8; H, 4.60; N, 6.09%). 1H
NMR (CD2Cl2): δ 7.73–7.58 (m, Ar), 7.47 (m, Ar), 7.34 (m, Ar),
3.47 (br, CH2), 3.32 (m, NH), 3.07 (m (br), CH2), 2.99 (m,
4J(H,P) 3 Hz, CH3NPt), 2.45 (m, CH2), 2.26 (br, CH2) and 2.06
(s, CH3N). IR (KBr, cmϪ1): 3367, 3212 [m, ν(NH)] and 840 [vs,
ν(PF6)].
cis-[PtCl2(L2-P,N)] 4. As for complex 1 using [PtCl2(cod)]
(0.228 g, 0.61 mmol) and L2 (0.175 g, 0.61 mmol). Yield 0.25 g
(75%) (Found: C, 37.1; H, 4.22; N, 4.85. C17H23Cl2N2PPt
requires C, 37.0; H, 4.20; N, 5.07%). 1H NMR (CDCl3): δ 7.83
(m, 4 H, Ar), 7.46 (m, 6 H, Ar), 3.32 (m (br), 2 H, CH2), 3.27
(s (br), 2 H, CH2), 3.12 (m (br), 6 H, CH3N) and 2.38 (d, 2 H,
3J(H,P) 8 Hz, CH3NP).
Syntheses
Ph2PNHCH2CH2NMe2 L1. n-Butyllithium in hexane (6.96
cm3, 1.6 M, 11 mmol) and PPh2Cl (2.46 g, 11 mmol) were added
sequentially with stirring to a solution of NH2CH2CH2NMe2
(0.980 g, 11 mmol) in THF (40 cm3) at Ϫ78 ЊC. The reaction
mixture was stirred for 2 hours and then slowly warmed to
room temperature. The solvent was removed under reduced
pressure and the product extracted with ice cold diethyl ether.
The resulting solution was evaporated under reduced pressure
to give a pale yellow moisture-sensitive oil. Yield 2.28 g (75%)
(Found: C, 71.1; H, 7.68; N, 9.60. C16H21N2P requires C, 70.6;
[Pt(dmba)Cl(L2)] 5. The complex [{Pt(dmba)(µ-Cl)}2] (0.204
g, 0.28 mmol) was added to a solution of L2 (0.160 g, 0.56
mmol) in dichloromethane (30 cm3). The solution was stirred
for 1 hour, after which it was concentrated under reduced
pressure, filtered and diethyl ether added, to give 5. Yield 0.34 g
(93%, mixture of isomers) (Found: C, 48.1; H, 5.57; N, 6.87.
H, 7.77; N, 10.3%). 31P-{1H} NMR (CDCl3): δ 41.6. H NMR
(CDCl3): δ 7.41–7.37 (m, 4 H, Ar), 7.30–7.15 (m, 6 H, Ar),
2.89 (dt, 2 H, J(H,P) 14, J(H,H) 6, CH2NP), 2.49 (m, 1 H,
1
3
3
1
C26H35ClN3PPt requires C, 48.0; H, 5.42; N, 6.45%). H NMR
3
NH), 2.24 (t, 2 H, J(H,H) 6 Hz, CH2N) and 2.08 (s, 6 H,
(CD2Cl2): δ 7.85 (m, 4 H, Ar), 7.38 (m, 6 H, Ar), 7.10 (m, Ar),
6.97 (t, Ar), 6.69 (t, Ar), 4.05 (m, 2 H, 4J(H,P) 3, CH2N
(dmba)), 3.38 (m, 2 H, CH2NP), 2.95 (m, 6 H, 4J(H,P) 3, CH3N
(dmba)), 2.75 (d, 3 H, 3J(H,P) 11, CH3NP), 2.49 (t, 2 H,
3J(H,H) 8 Hz, CH2N) and 2.14 (s, 6 H, CH3N).
CH3). 13C-{1H} NMR (CDCl3): δ 140.9 (d, J(C,P) 13, Cipso),
1
2
3
130.7 (d, J(C,P) 20, Cortho), 127.5 (d, J(C,P) 7, Cmeta), 127.3
3
(s, Cpara), 60.3 (d, J(C,P) 7, CH2N), 44.6 (s, CH3) and 42.3 (d,
2J(C,P) 11 Hz, CH2NP). IR (KBr, cmϪ1): 3370 [m (br), ν(NH)].
Ph2PNMeCH2CH2NMe2 L2. Triethylamine (1.13 g, 11 mmol)
and PPh2Cl (2.46 g, 11 mmol) were added sequentially with
stirring to a solution of NHMeCH2CH2NMe2 (1.14 g, 11
mmol) in THF (20 cm3). The reaction mixture was stirred for 30
minutes and then filtered to remove NEt3HCl. The resulting
solution was evaporated under reduced pressure and the
product extracted with diethyl ether at Ϫ78 ЊC. The resulting
solution was evaporated under reduced pressure to give a
colourless moisture-sensitive oil. Yield 2.37 g (76%) (Found: C,
71.1; H, 7.96; N, 9.31. C17H23N2P requires C, 71.3; H, 8.10; N,
[Pt(dmba)(L2-P,N)]PF6 6. TlPF6 (0.072 g, 0.21 mmol) was
added to a solution of complex 5 (0.103 g, 0.16 mmol) in
dichloromethane (10 cm3) and the mixture stirred overnight.
The resulting solution was filtered, the residue washed with
dichloromethane and the filtrate and washings were combined.
The solvent was then evaporated under reduced pressure to give
a yellow solid, which was recrystallised from dichloromethane–
hexane. Yield 0.049 g (41%). 1H NMR (CD2Cl2): δ 7.85 (m, Ar),
7.48 (m, Ar), 6.82 (d, 1 H, Ar), 6.63 (t, 1 H, Ar), 6.40 (m, 1 H,
Ar), 6.21 (t, 1 H, Ar), 3.99 (m (br), 2 H, CH2N (dmba)), 3.26
(br, 4 H, CH2N/CH2NP), 2.90 (s, 6 H, CH3N), 2.88 (m, 6 H,
1
9.78%). 31P-{1H} NMR (CDCl3): δ 65.4. H NMR (CDCl3):
δ 7.41–7.34 (m, 4 H, Ar), 7.33–7.28 (m, 6 H, Ar), 3.22–3.12 (m,
3
4J(H,P) 3, CH3N (dmba)) and 2.44 (d, 2 H, J(H,P) 9 Hz,
3
2 H, CH2NP), 2.52 (d, 3 H, J(H,P) 6, CH3NP), 2.35 (t, 2 H,
CH3NP).
3J(H,H) 7 Hz, CH2N) and 2.17 (s, 6 H, CH3N). 13C-{1H} NMR
1
2
cis-[(L2-P,N)ClPt(ꢀ-L2)CoCl3] 7. CoCl2ؒ6H2O (0.069 g, 0.29
mmol) was added with stirring to a solution of complex 2
(0.244 g, 0.29 mmol) in acetone. After 30 min the solution was
filtered, the solvent removed in vacuo and the product recrys-
tallised from dichloromethane–diethyl ether. Yield 0.16 g
(55%) (Found: C, 40.9; H, 4.76; N, 5.45. C34H46Cl4CoN4P2Ptؒ
1/2CH2Cl2 requires C, 41.0; H, 4.69; N, 5.54%). FAB-MS: m/z
803, [M Ϫ CoCl3]ϩ.
(CDCl3): δ 139.0 (d, J(C,P) 16, Cipso), 131.5 (d, J(C,P) 20,
Cortho), 127.8 (s, Cpara), 127.6 (d, 3J(C,P) 7, Cmeta), 58.1 (d, 2J(C,P)
6, CH2N), 54.2 (d, 2J(C,P) 29 Hz, CH2NP), 45.3 (s, CH3N) and
36.9 (s, CH3NP).
cis-[PtCl2(L1)2] 1. [PtCl2(cod)] (0.332 g, 0.86 mmol) was
added with stirring to a solution of L1 (0.470 g, 1.73 mmol)
in dichloromethane. After 30 min the solvent was removed
in vacuo and the crude product recrystallised from dichloro-
methane–diethyl ether. Yield 0.50 g (70%) (Found: C, 47.1; H,
5.21; N, 6.41. C32H42Cl2N4P2Pt requires C, 47.4; H, 5.22; N,
cis-[(L2-P,N)ClPt(ꢀ-L2)ZnCl3] 8. As for complex 7 using
ZnCl2 (0.074 g, 0.54 mmol) and 2 (0.455 g, 0.54 mmol).
Recrystallisation from dichloromethane–diethyl ether gave a
colourless crystalline material (Found: C, 40.1; H, 4.60; N, 5.22.
C34H46Cl4N4P2PtZnؒCH2Cl2 requires C, 39.7; H, 4.56; N,
5.29%).
1
6.91%). H NMR (d6-acetone): δ 7.80 (m, Ar), 7.57 (m, Ar),
7.50 (m, Ar), 4.69 (br, NH), 2.66 (br, CH2), 2.25 (br, CH2)
and 2.12 (br, CH3). IR (KBr, cmϪ1): 3370 [m (br), ν(NH)].
cis-[PtCl2(L2)2] 2. As for complex 1 using [PtCl2(cod)] (0.136
g, 0.36 mmol) and L2 (0.214 g, 0.75 mmol). Recrystallised from
THF–hexane. Yield 0.15 g (50%) (Found: C, 49.8; H, 5.99;
[Pt(O2C6H3But)(L2)2] 9. L2 (0.306 g, 0.82 mmol) was added to
a solution of [Pt(O2C6H3But)(cod)] formed in situ from [PtCl2-
3618
J. Chem. Soc., Dalton Trans., 2000, 3615–3619

View Article Online
2 T. Hosokawa, Y. Wakabayashi, K. Hosokawa, T. Tsuji and S.-I.
Murahashi, Chem. Commun., 1996, 859.
3 K. G. Gaw, A. M. Z. Slawin and M. B. Smith, Organometallics,
1999, 18, 3255.
4 D. J. Birdsall, J. Green, T. Q. Ly, J. Novosad, M. Necas, A. M. Z.
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(cod)] (0.200 g, 0.53 mmol), 4-tert-butylcatechol (0.089 g, 0.53
mmol) and DBU (0.17 cm3, 0.173 g, 1.14 mmol). The mixture
was stirred for 30 minutes after which the solvent was removed
under reduced pressure and the product extracted with hexane
(40 cm3). The solution was then cooled to Ϫ78 ЊC to precipitate
the product as an orange powder. Yield 0.41 g (83%) (Found: C,
56.2; H, 6.34; N, 6.04. C44H58N4O2P2Pt requires C, 56.7; H,
6.27; N, 6.01%). 1H NMR (CDCl3): δ 7.60 (m, Ar), 7.38 (m, Ar),
7.22 (m, Ar), 6.85 (m, Ar), 6.71 (m, Ar), 6.56 (m, Ar), 3.34 (m
(br), 2 H, CH2NP), 2.83 (m, 3 H, CH3NP), 2.43 (m, 2 H,
CH2N), 2.15 and 2.12 (s, 6 H, CH3N) and 1.40 (s, 9 H, t-Bu).
7 J.-M. Brunel and G. Buono, Tetrahedron Lett., 1999, 40, 3561.
8 P. A. Bella, O. Crespo, E. J. Fernández, A. K. Fischer, P. G. Jones,
A. Laguna, J. M. López-de-Luzuriaga and M. Monge, J. Chem.
Soc., Dalton Trans., 1999, 4009.
Crystallography
Single crystals of complex 7 were prepared by recrystallisation
from dichloromethane–diethyl ether. A crystal of approximate
dimensions 0.18 × 0.18 × 0.15 mm was used for the data
collection. C34H46Cl4CoN4P2Pt, M = 968.51, monoclinic,
space group P21/c, T = 293(2) K, a = 16.710(3), b = 12.160(2),
c = 19.666(5) Å, β = 104.82(2)Њ, U = 3863.1(14) Å3, Z = 4,
µ(Mo-Kα) = 4.436 mm–1. 7270 reflections measured. 5156 F2
data [Fo > 4σ(Fo)] gave R1 = 0.0367 and wR2 = 0.0838. Data
were collected on an Enraf-Nonius CAD4 automatic four-circle
diffractometer in the range 2.10 < θ < 24.99Њ and corrected for
Lorentz and polarisation effects, in addition to 12% decay of
the sample in the X-ray beam. The structure solution and
refinement were undertaken using SHELXS 8623 and SHELXL
9324 respectively. The plot of the asymmetric unit was produced
using ORTEX.25
9 M. S. Balakrishna, R. M. Abhyankar and J. T. Mague, J. Chem.
Soc., Dalton Trans., 1999, 1407.
10 F.-Y. Zhang, C.-C. Pai and A. S. C. Chan, J. Am. Chem. Soc., 1998,
120, 5808.
11 T. Q. Ly, A. M. Z. Slawin and J. D. Woollins, J. Chem. Soc., Dalton
Trans., 1997, 1611.
12 S. M. Aucott, A. M. Z. Slawin and J. D. Woollins, Phosphorus,
Sulfur, Silicon Relat. Elem., 1997, 124–125, 473.
13 W. Schirmer, U. Flörke and H.-J. Haupt, Z. Anorg. Allg. Chem.,
1987, 545, 83.
14 W.-K. Wong, C. Sun and W.-T. Wong, J. Chem. Soc., Dalton Trans.,
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15 G. M. Gray, A. L. Zell and H. Einspahr, Inorg. Chem., 1986, 25,
2923.
16 I. C. F. Vasconcelos, N. P. Rath and C. D. Spilling, Tetrahedron:
Asymmetry, 1998, 9, 937.
17 G. T. Andrews, I. J. Colquhoun and W. McFarlane, Polyhedron,
1983, 2, 783.
CCDC reference number 186/2180.
18 G. K. Anderson and R. Kumar, Inorg. Chem., 1984, 23, 4064.
19 P. Braunstein, D. Matt, Y. Dusausoy, J. Fischer, A. Mitschler and
L. Ricard, J. Am. Chem. Soc., 1981, 103, 5115.
20 J. M. Clemente, C. H. Wong, P. Bhattacharyya, A. M. Z. Slawin,
D. J. Williams and J. D. Woollins, Polyhedron, 1994, 13, 261.
21 D. Drew and J. R. Doyle, Inorg. Synth., 1972, 13, 48.
22 A. C. Cope and E. C. Friedrich, J. Am. Chem. Soc., 1968, 90,
909.
See http://www.rsc.org/suppdata/dt/b0/b005899h/ for crystal-
lographic files in .cif format.
Acknowledgements
The University of Bath is thanked for a studentship to M. T. P.
23 G. M. Sheldrick, Acta Crystallogr., Sect. A, 1990, 46, 467.
24 G. M. Sheldrick, SHELXL, a computer program for crystal
structure refinement, University of Göttingen, 1993.
25 P. McArdle, J. Appl. Crystallogr., 1995, 28, 65.
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J. Chem. Soc., Dalton Trans., 2000, 3615–3619
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