Exploring the coordination chemistry and reactivity of dialkylamino- and bis(dialkylamino)-phosphines in the coordination sphere of metals

Article abstract of DOI:10.1039/b208886j

The coordination chemistry of a range of dialkylamino- and bis(dialkylamino)-phosphines, R_xP(NR′₂) _3-x (x = 1 or 2; R = Cl, Me, Ph, C₆F₅; R′ = Et, Prⁱ), 1-7, has been studied and the resulting Group 6 tetracarbonyl and platinum dichloride bis(phosphine) complexes fully characterised. Subsequently, the reactivity of the P-N bonds of the metal-bound phosphines was probed. Treatment of R″OH (R″ = Me, Et, allyl) solutions of the bis(dialkylaminodiphenylphosphine) complexes with anhydrous HCl gas led to substitution of NR′₂ by OR″; the resulting P-alkoxy complexes were isolated in excellent yields. Acidification of ethylene glycol solutions of the aminophosphine complexes afforded the corresponding bis(chlorodiphenylphosphine) derivatives. Following reaction of trans-[W(CO)₄(P{NEt₂}Ph₂)₂] with either aqueous HCl or H₂SO₄, trans-[W(CO) ₄(P{OH}Ph₂)₂] could be isolated as its dichloromethane solvate in excellent yield (81%). Reactions of the bis(bis{dialkylamino} phenylphosphine) complexes under identical conditions yielded a range of unidentified products. Reactions of ligands 1-7 with [{RhCl(CO)₂}₂] and elemental selenium have been undertaken and the products used to assess the phosphines' donor capabilities. Depending on the substituents at phosphorus, either trans-diphosphine or cis-dicarbonyl complexes result from reaction with [{RhCl(CO)₂} ₂]. The sterically demanding phosphine P(NPr₂ ⁱ)₂Ph (5) proved unreactive towards complexation with metals, although its selenide could be prepared and isolated. In order to probe the observed lack of oxidation or complexation the molecular structure P(NPr₂ⁱ)₂(C₆F₅) has been determined by X-ray crystallography. The Royal Society of Chemistry 2003.

Full text of DOI:10.1039/b208886j

View Article Online / Journal Homepage / Table of Contents for this issue
Exploring the coordination chemistry and reactivity of
dialkylamino- and bis(dialkylamino)-phosphines in the coordination
sphere of metals
Philip W. Dyer,* John Fawcett, Martin J. Hanton, Raymond D. W. Kemmitt,* Ranbir Padda
and Narendra Singh
Department of Chemistry, University of Leicester, Leicester, UK LE1 7RH.
E-mail: p.dyer@le.ac.uk
Received 12th September 2002, Accepted 31st October 2002
First published as an Advance Article on the web 29th November 2002
The coordination chemistry of a range of dialkylamino- and bis(dialkylamino)-phosphines, RxP(NRЈ2)3 Ϫ x (x = 1 or
2; R = Cl, Me, Ph, C6F5; RЈ = Et, Pri), 1–7, has been studied and the resulting Group 6 tetracarbonyl and platinum
dichloride bis(phosphine) complexes fully characterised. Subsequently, the reactivity of the P–N bonds of the
metal-bound phosphines was probed. Treatment of RЉOH (RЉ = Me, Et, allyl) solutions of the
bis(dialkylaminodiphenylphosphine) complexes with anhydrous HCl gas led to substitution of NRЈ2 by ORЉ; the
resulting P-alkoxy complexes were isolated in excellent yields. Acidification of ethylene glycol solutions of the
aminophosphine complexes afforded the corresponding bis(chlorodiphenylphosphine) derivatives. Following reaction
of trans-[W(CO)4(P{NEt2}Ph2)2] with either aqueous HCl or H2SO4, trans-[W(CO)4(P{OH}Ph2)2] could be isolated
as its dichloromethane solvate in excellent yield (81%). Reactions of the bis(bis{dialkylamino}phenylphosphine)
complexes under identical conditions yielded a range of unidentified products. Reactions of ligands 1–7 with
[{RhCl(CO)2}2] and elemental selenium have been undertaken and the products used to assess the phosphines’ donor
capabilities. Depending on the substituents at phosphorus, either trans-diphosphine or cis-dicarbonyl complexes
result from reaction with [{RhCl(CO)2}2]. The sterically demanding phosphine P(NPri2)2Ph (5) proved unreactive
towards complexation with metals, although its selenide could be prepared and isolated. In order to probe the
observed lack of oxidation or complexation the molecular structure P(NPri2)2(C6F5) has been determined by X-ray
crystallography.
method of tuning both the ligand’s steric and electronic
Introduction
demands through variation of the amino substituents, RЈ,
Since their discovery by Michaelis, amino-substituted phos-
making them extremely versatile ligands.
phines have been the focus of considerable interest as potential
precursors to P–N backbone polymeric materials and, more
Prior to the routine application of aminophosphines B and C
in the catalysis arena however, it seems important that the
fundamentally, because of their potential to exhibit P–N
fundamental behaviour of these relatively ill-explored ligands
multiple bonding.1,2 In contrast, their coordination chemistry
should be understood in the coordination spheres of metals,
has been comparatively poorly studied, despite an initial flurry
especially as they possess potentially reactive phosphorus–
of activity3–6 and the prevalence of many such phosphines in
nitrogen linkages. Indeed, much of the early work on amino-
the literature; the amino group is often used as a convenient and
phosphines focussed on the reaction of this moiety with protic
versatile protecting/leaving group for phosphorus;7–10 amino-
reagents rather than on coordination chemistry. It is note-
phosphines exhibit antimicrobial activity;11 and sterically
worthy that one of the most studied aminophosphines is the
demanding variants have been used to protect reactive main
readily prepared secondary phosphine, (Pri2N)2PH, which was
group and organic moieties.12 Some of the reluctance to use
investigated with a view to examining the reactivity associated
aminophosphine ligands can be attributed to their perceived
with both the P–H and P–N bonds in the coordination sphere
susceptibility to protic reagents, in particular solvents. How-
of metal carbonyl fragments.22,23
ever, the advent of more robust heterocyclic systems A (Fig. 1)
Here we describe the coordination chemistry of a number of
monoamino-, diamino- and aminohalo-substituted phosphines
of types B and C. In particular, the reactivity of the potentially
has led to a dramatic upturn in their application, especially in
the asymmetric catalysis arena.13,14
labile P–N bond of the metal-bound ligands has been probed,
in conjunction with a study of the relative donor properties of
each of the ligands.
Results and discussion
Fig. 1 Aminophosphine classification. E = EЈ = NRЉ; E = O, EЈ = NRЉ.
Coordination chemistry and reactivity of aminophosphines
Recently, however, acyclic amino-functionalised phosphines
B and C have seen somewhat of a renaissance as ligands.15–20
In part, this can be attributed to the increasing demand for
libraries of metal complexes for testing in a variety of catalytic
applications and transformations.21 Aminophosphines,
A
range of simple amino-functionalised phosphines,
RxP(NRЈ2)3 (1–7), was chosen for this study (Table 1).
Ϫ
x
Derivatives 1–5, and 7 were prepared following literature
procedures or slight modifications thereof. Where ligands
were prepared through reaction of an organometallic reagent
with a chlorophosphine, the organo-lithium derivatives were
employed. In all cases, the use of the corresponding Grignards
afforded mixtures of the desired product and the reductively-
coupled diphosphines. In contrast, the previously unreported
RxP(NRЈ2)3
(x = 0–2), are particularly attractive in this
Ϫ
x
respect, as they are conveniently prepared through the reaction
of halophosphines with amines, of which there is a structurally
diverse range readily available. This obviously provides a simple
D a l t o n T r a n s . , 2 0 0 3 , 1 0 4 – 1 1 3
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3
104

View Article Online
Scheme 1 Reagents and conditions: i 2 P(NEt2)Ph2, C6H6, rt, 12 h; ii 2 P(NEt2)Ph2, CH2Cl2, rt, 2 h; iii 2 P(NEt2)Ph2, C6H6, 80 ЊC, 3 h; iv HCl (g),
CH2Cl2, rt, 15 min; v HCl (g), CH2Cl2, rt, 15 min; vi HCl (g), RЉOH, rt, 30 min; vii HCl (g), HOCH2CH2OH, rt, 15 min; viii H2SO4 (10%), CH2Cl2,
RT, 24 h, rt.
Table 1 31P{1H} NMR dataa for compounds 1–30
displacement from fac-[Cr(CO)3(MeCN)3] (following CO
scrambling) or from cis-[M(CO)4(pip)2] (M = Mo, W; pip =
g
1JMP
Hz
/
piperidine) [Scheme 1]. The substitution reactions for both
chromium and molybdenum proceeded cleanly in either
benzene or CH2Cl2 at room temperature. In contrast, the
tungsten bis(phosphine) analogue could only be prepared in
refluxing benzene. All the tetracarbonyl derivatives are readily
soluble in organic solvents and are air-stable.
Compound
δ(31P)/ppm
1 P(NEt2)Ph2
66.8
36.7i
2 P(NPri2)Ph2
3 P(NEt2)2Ph
99.0f
4 P(NPri2)2Me
39.0e
5 P(NPri2)2Ph
59.2e
One of the reactions typically associated with compounds
that possess P–N bonds is protolytic cleavage of this linkage
with acids. Hence, the reaction of the simple carbonyl com-
plexes 8–10 with a range of protic acids was investigated.
Treatment of CH2Cl2 solutions of complexes 8 and 10 with
anhydrous HCl gas afforded the complexes trans-[M(CO)4-
(P{Cl}Ph2)2] 11 (Cr, 84%)25 and 12 (W, 77%) as bright yellow,
crystalline, air stable species (Scheme 1). In contrast, an identi-
cal reaction with 9 afforded a complicated mixture of products
which contained only trace amounts of trans-[Mo(CO)4(P{Cl}-
Ph2)2] according to 31P NMR spectroscopy.26 Clearly, this
methodology provides a straightforward approach to the
preparation of the potentially synthetically versatile complex
12, for which no synthesis has previously been reported in the
literature.
Another prototypical reaction associated with P–N bonds is
their cleavage by alcohols. Thus, it was somewhat surprising to
find that suspensions of complexes 8–10 could be stirred in
methanol for 12 h at rt without reaction or decomposition,
although similar resistance to alcoholysis has recently been
reported for certain sterically demanding bis(dialkylamino)-
phosphine complexes.20
6 P(NPri2)2(C6F5)
48.7f
7 P(Cl)(NPri2)2
140.6f
132.5d
97.2d
8 trans-[Cr(CO)4(P{NEt2}Ph2)2]
9 trans-[Mo(CO)4(P{NEt2}Ph2)2]
10 trans-[W(CO)4(P{NEt2}Ph2)2]
11 trans-[Cr(CO)4(P{Cl}Ph2)2]
12 trans-[W(CO)4(P{Cl}Ph2)2]
13 trans-[W(CO)4(P{OMe}Ph2)2]
14 trans-[W(CO)4(P{OEt}Ph2)2]
15 trans-[W(CO)4(P{OCH2CHCH2}Ph2)2]
16 trans-[W(CO)4(P{OH}Ph2)2]ؒCH2Cl2
17 cis-[PtCl2(P{NEt2}Ph2)2]
18 trans-[PtCl2(PNPri2{Ph}2)2]
19 cis-[PtCl2(P{OMe}Ph2)2]
20 cis-[PtCl2(P{OEt}Ph2)2]
21 cis-[PtCl2(P{OCH2CHCH2}Ph2)2]
22 cis-[PtCl2(P{Cl}Ph2)2]
23 trans-[PtCl2(P{Cl}Ph2)2]
24 trans-[PtCl2(P{NEt2}2Ph)2]
25 trans-[PtCl2(P{NPri2}2Me)2]
26 trans-[RhCl(CO)(P{NEt2}Ph2)2]
27 trans-[RhCl(CO)(P{NPri2}Ph2)2]
28 cis-[RhCl(CO)2(P{NEt2}2Ph)]
29 trans-[RhCl(CO)(P{NPri2}2Me)2]
30 cis-[RhCl(CO)2(P{NPri2}2Ph)]
85.1d
298
169.6d
101.6d
129.5d
124.6d
126.8d
107.5d
55.9d
323
322
317
313
269
3994
2759
4185
4185
4175
4116
3213
2926
2755
131
60.3d
84.9b, d
81.1b, d
83.1b, d
71.2b, d
47.2b, d
88.0f
86.0f
78.3e
70.3f
131
147
136
146
97.3f
110.0f
107.2e
In contrast, reaction at the P–N linkage could be induced by
bubbling anhydrous HCl gas through suspensions of 10 in a
range of alcohols. This afforded the corresponding alkyl
diphenylphosphinite complexes, trans-[W(CO)4(P{ORЉ}Ph2)2]
(13–15) in reasonable yields as air-sensitive solids; the com-
plexes slowly darken and decompose over the period of a week
in air. Treating a suspension of 10 in ethylene glycol with HCl
gas resulted in only the formation of the chlorophosphine com-
plex 12 (according to 31P NMR spectroscopy), rather than the
expected hydroxyethylphosphinite. In view of the ease and
efficiency of these substitution reactions, it is surprising that
there are only a few reports of this type of functional group
interconversion in the literature.27,28
Conversely, it was found that treating suspensions of either
the chromium (8) or the molybdenum (9) complexes in alcohols
or ethylene glycol with gaseous HCl resulted in the formation
of mixtures of species that included the trans-[M(CO)4-
(P{Cl}Ph2)2] complexes as only a minor component in each
case, according to 31P NMR spectroscopy.
a CDCl3. b CD2Cl2. c C6D6. d 24.0 MHz. e 101.3 MHz. f 121.9 MHz.
h 3
g M = W, Pt, or Rh.
J
= 47 Hz. i See ref. 29.
PF
phosphine 6 was prepared through reaction of (Pri2N)2PCl with
(F5C6)MgBr and isolated in good yield (80%).24 †
Tetracarbonyl complexes. In order to assess the reactivity of
the P–N linkage of aminophosphines in the coordination
sphere of a metal, it was desirable to study systems where
potential reaction of the protic reagents with the metal centre
was minimised. Hence, in the first instance, the Group 6 tetra-
carbonyl derivatives, trans-[M(CO)4(P{NEt2}Ph2)2] {M = Cr
(8), Mo (9), W (10)}, were prepared through simple ligand
† The Grignard is considerably safer to handle than the corresponding
perfluoroaryl lithium which has a tendancy to eliminate lithium fluoride
spontaneously at ambient temperatures.
D a l t o n T r a n s . , 2 0 0 3 , 1 0 4 – 1 1 3
105

View Article Online
Scheme 2 Reagents and conditions: i 2 P(NEt2)Ph2, CH2Cl2, rt, 2 h; ii 2 P(NPri2)Ph2, CH2Cl2, rt, 2 h; iii HCl (g), RЉOH, rt, 30 min; iv HCl (g),
RЉOH, rt, 15 min; v HCl (g), HOCH2CH2OH, rt, 30 min; vi HCl (g), CH2Cl2, rt, 30 min; vii C7H8, 120 ЊC, 5 d.
Since complex 10 reacted cleanly with alcohols in the pres-
ence of HCl, it was of interest to try a similar reaction with
water in the hope that a complex of diphenylphosphinous acid,
P(OH)Ph2, could be isolated, this hydroxy derivative being an
attractive precursor for further functionalisation. Treatment of
10 with either excess aqueous HCl or aqueous H2SO4 afforded a
single major product in both cases, according to 31P{1H} NMR
spectroscopy (ca. ϩ106 ppm, 1JPW 269 Hz).‡ Following workup,
trans-[W(CO)4(P{OH}Ph2)2].CH2Cl2 (16) could be isolated as a
purple solid in excellent yield (81%). Although the absence of
result of chloride ion catalysis.32–34 An attempt to convert 22
into 23 by thermal methods resulted in only partial isomeris-
ation (toluene, reflux, 5 d; 22 : 23 = 45 : 55 according to 31P
NMR spectroscopy). However, addition of a catalytic quantity
of [Pri2NH2]Cl to a toluene solution of 22 followed by therm-
olysis (toluene, reflux 5 d) resulted in an enhanced cis/trans-
ratio, 22 : 23 = 25 : 75, something that supports the role of ClϪ
in isomerisation of these [PtCl2(PR3)2] complexes.
To further probe the coordination chemistry and subsequent
reactivity of the aminophosphine complexes, it was of interest
to investigate some of the corresponding diamino derivatives.
The complexes trans-[PtCl2(P{NEt2}2Ph)2] (24) and trans-
[PtCl2(P{NPri2}2Me)2] (25) were readily prepared from [PtCl2-
(COD)] and the corresponding diaminophosphines P(NEt2)2Ph
(3) and P(NPri2)2Me (4) in 81 and 74% yield, respectively. In
contrast, no Group 6 or Pt() complexes of the bis(diisopro-
pylamino) derivative P(NPri2)2Ph (5) could be prepared despite
either prolonged heating at reflux or sonication.
1
the –NEt2 moiety was clearly confirmed by H NMR spectro-
scopy, no resonance attributable to the OH proton could be
detected. However, its presence could be inferred through
treatment of a sample of 16 with D2O, which led to the appear-
ance of a characteristic signal for HOD at ca. δ 4.20 ppm.
Further evidence for the presence of the hydroxyl group comes
from the observation of a broad, weak band at 2300 cmϪ1 in the
IR spectrum of 16.
Since reaction at the P–N bonds of metal-bound amino-
phosphines proceed extremely smoothly, identical reactions
were attempted with complexes 24 and 25 bearing bis(amino-
phosphine) ligands. Addition of anhydrous HCl to MeOH or
CH2Cl2 solutions of 24 led to the formation of a variety of
unidentified phosphorus-containing products in both cases,
according to 31P NMR spectroscopy. In contrast, complex 25
proved inert to HCl-induced P–N bond cleavage at room
temperature, while decomposition occurred following
prolonged heating at reflux in either MeOH or CH2Cl2;
Platinum dichloride complexes. The study of the Group 6
bis(aminophosphine) tetracarbonyl derivatives provided a
comparatively inert framework in which to probe the reactivity
of the P–N linkage, yet is of limited significance to many
industrially relevant catalytic processes. With this in mind,
similar investigations were undertaken for platinum() com-
plexes of ligands 1 and 2.
Reaction of cis-[PtCl2(COD)] with ca. 2 equivalents of either
1 or 2, afforded the bis(phosphine) complexes cis-17 (88%) and
trans-18 (81%), respectively, under identical reaction conditions
(Scheme 2). The differences in geometry about platinum, were
readily apparent from an examination of the magnitudes of the
O᎐P(H)(NPri ) was identified as the major product.35 It is
᎐
2
2
interesting to note that no complexes could be prepared by
direct reaction of P(Cl)(NPri2)2 (7) with labile Group 6 or Pt()
precursors. It should be noted however that reaction of
[M(CO)5(P{NEt2}2Ph)] (M = Cr, Mo) with HCl has been shown
to afford the corresponding bis{PCl(NEt2)(Ph)} complexes in
reasonable yields.36
1
respective JPPt coupling constants (Table 1), and presumably
reflect differences in the steric demands of phosphines 1 and 2.30
Treatment of alcoholic solutions of either cis-17 or trans-18
with HCl gas at room temperature led to the formation of the
exclusively cis-bis(diphenylphosphinite) complexes 19–21 as
white, air stable solids in excellent yields. The known bis(chloro-
diphenylphosphine) complex cis-[PtCl2(P{Cl}Ph2)2] (22) was
obtained by bubbling gaseous HCl through ethylene glycol
solutions of 17 and 18 or through a CH2Cl2 solution of 18.31
In contrast to the reactivity associated with the tungsten tetra-
carbonyl derivative 10, complexes 17 and 18 proved inert
towards an aqueous solution of H2SO4. However, the cis-chloro-
phosphine derivative 22 was formed in low yield following
reaction of 17 with aqueous 1 M HCl, according to 31P NMR
spectroscopy.
Mechanistic considerations
From the studies outlined above, it was deduced that in order to
bring about P–N bond cleavage in the coordination sphere of
metals, the presence of acid is essential. Previously it has been
reported that [M(CO)5(P{Cl}{NR2}{RЈ})] (M = Cr, Mo, W)
can be prepared from reaction of the corresponding
{P(NR2)2RЈ} complexes by addition of HCl and elimination of
[R2NH2]Cl.6,36 This clearly accounts for the formation of 11, 12
and 22. Furthermore, it seems reasonable to suggest that the
amino-alkoxy exchange process observed here (13–15 and
19–21) follows a similar pathway, whereby initial protonation at
nitrogen occurs prior to formal nucleophilic substitution,
resulting in elimination of ammonium chloride and formation
of the corresponding phosphinite complex (Scheme 3). How-
ever, it remains unclear why attempts to instigate amino-alkoxy
exchange for the Cr and Mo systems (8 and 9, respectively) were
Notably, for all the P–N bond cleavage reactions associated
with 18, the stereochemistry of the resultant products necessi-
tates an efficient trans- to cis-isomerisation, presumably as a
‡ The exact value of the 31P NMR chemical shift obtained from the
crude reaction mixture varies slightly ( 2 ppm) depending on the exact
concentration of aqueous acid employed.
D a l t o n T r a n s . , 2 0 0 3 , 1 0 4 – 1 1 3
106

View Article Online
Table
2
Comparison of νCO for various trans-[M(CO)4(PR3)2]
surprisingly, little difference was observed between the values of
complexes
νCO obtained for these aminophosphine derivatives and those
possessing triphenylphosphine ligands (entries 2, 4, and 6).
However, as expected, the chlorodiphenylphosphine complexes
11 and 12 exhibited higher frequency νCO bands as a result of
the ϪI effect of chlorine.
Since this approach appeared relatively insensitive to
variations in the framework of the phosphorus-based ligand, a
more detailed investigation using the more widely employed
approach, namely an examination of the CO stretching
frequencies of trans-[RhCl(CO)(PR3)2] complexes, was under-
taken.44–46
Entry
Complex
νCO a, b/cmϪ1
1
2
3
4
5
6
7
8
9
8
1880
1878
1890
1892
1878
1880
1918
1918
1882
1890
1898
1895
trans-[Cr(CO)4(PPh3)2]c
9
trans-[Mo(CO)4(PPh3)2]c
10
trans-[W(CO)4(PPh3)2]c
11
12
13
14
15
16
10
11
12
Reactions with [{RhCl(CO)2}2]. The trans-[RhCl(CO)-
{PR1 R2}2)] complexes 26, 27 and 29 were prepared by treating
2
a Eu symmetry band only. b KBr, Nujol. c Prepared as for 8 and 9 using
PPh3.
CDCl3 solutions of [{RhCl(CO)2}2] with four equivalents of
ligands 1, 2 and 4, respectively. After initial evolution of CO
had ceased, the reaction vessel was sealed under 1 atmosphere
of CO to prevent both ligand dissociation and decomposition
in solution, as has been reported previously.46 § In solution
(CDCl3/1 atm CO) complexes 26, 27 and 29 are stable for weeks,
each exhibiting a single doublet resonance in their 31P{1H}
1
NMR spectra, with both chemical shifts and JPRh coupling
constants (ca. 133 Hz) being comparable to those previously
reported in the literature for similar species (Table 1). The
13C{1H} NMR spectra of 26, 27 and 29 showed a single
carbonyl environment in each case.¶ At ambient probe temper-
atures, the CO resonance was a sharp singlet for 26
(which broadened significantly on lowering the temperature to
Ϫ50 ЊC but was never completely resolved), was considerably
broadened at rt for complexes 27 (suggesting rapid CO
exchange), and appeared as a well-resolved doublet of triplets
for 29 (1JRhC 77.9 Hz, 2JPC 15.7 Hz).
An examination of the data for analogous Rh() carbonyl
complexes of other phosphines indicates that ligands 1 and 2
are comparable donors to PPh3 (Entry 16, Table 3), something
that is entirely consistent with the results obtained for the tetra-
carbonyl complexes 8–10 (vide supra). This suggests that N to
P lone pair donation offsets any effect of the electron withdraw-
ing amino substituents on the donor ability of 1 and 2, however
this does not take into account any differences in π-acceptor
behaviour between the ligands. The extent of this latter com-
ponent is hard to quantify with any certainty. Significantly, the
carbonyl stretching frequency for the complex with ligand 4
(Entry 4) is consistent with it being a donor comparable to
either P(NMe2)3 or P(Npyrr)2Ph (Entries 10 and 12, respect-
ively), something that agrees with previous claims that for
bis- or tris-aminophosphines, the third substituent is merely a
spectator.16
Somewhat surprisingly, no reaction was observed to occur
between [{RhCl(CO)2}2] and 6 while an intractable mixture of
products resulted when the same reaction was attempted with 7.
To probe this lack of coordination in greater detail, crystals of
6 were obtained and its structure investigated by X-ray crystal-
lography. This revealed an essentially pyramidal phosphorus
centre (Σangles 315.6Њ) with the plane of the C6F5 ring lying at an
angle of 81.4Њ to the N2P plane (Fig. 2, Table 4). The amino
nitrogen atoms N(1) and N(2) are near trigonal planar (Σangles
359.1 and 359.6Њ, respectively) while the two P–N bond
distances are near-equivalent [P(1)–N(1) 1.683(3) Å and P(1)–
N(2) 1.669(4) Å]. These values are significantly shorter than
those associated with true P–N single bonds, something
Scheme 3
unsuccessful, affording only trace quantities of trans-
[M(CO)4(P{Cl}Ph2)2] (M = Cr, Mo), whereas 10 reacts cleanly
as expected. Indeed, an examination of the heteropolar single
bond energies (P–N: 293 kJ molϪ1; P–Cl: 331 kJ molϪ1; P–O:
360 kJ molϪ1) would suggest that the formation of the
diphenylphosphinite derivatives would be thermodynamically
more favourable.37 Since the values of νCO for complexes 8–10
differ little from those of their corresponding PPh3 complexes,
it is reasonable to propose that P(NEt2)Ph2 exerts the same
electronic influence in each of 8–10 (Table 2). Thus, it is unlikely
that there is a significant variation in P–N bond strength
(arising from variation in P–N multiple bonding) between
complexes 8–10.
The poor selectivity in the reactions of complex 24 (ligand 3)
and the lack of any reaction of complex 25 (ligand 4) with HCl/
ROH merits some comment. Since phosphine 3 possesses a
phenyl substituent (ϪI) and 4 an Me group (ϩI), the latter is
likely to exhibit a greater degree of P–N multiple bonding (and
hence greater P–N bond strength). This combined with the
greater steric bulk about the N atoms of 25 may account for its
lack of reactivity compared with that of 24. The origins of the
low selectivity of reactions of complex 24 remain elusive.
Lewis basicity studies
The disparity in the reactivity observed for the various amino-
phosphines clearly merits some further investigation. It is
understandable that steric demands are likely to be significant,
but it was intriguing to see if there was also any correlation with
the electronic nature of the various phosphines. Indeed, the
recent interest in amino-substituted phosphines has, in part,
arisen from the potential variation in donor properties possible
for such ligands.15,16,19,42,43
Although the energy associated with νCO of Group 6 tetra-
carbonyl complexes is not generally used to quantify ligand
basicity, a comparison of the IR spectroscopic data of the
various complexes 8–16 was undertaken (Table 2). Somewhat
§ Each of the rhodium complexes was isolated as an orange solid that
was stable for months under an atmosphere of nitrogen in the solid
state.
¶ In order to facilitate obseravtion of the CO resonances, it was found
essential to acquire 13C NMR spectra with samples prepared under
1 atm CO.
D a l t o n T r a n s . , 2 0 0 3 , 1 0 4 – 1 1 3
107

View Article Online
1
Table 3 Comparison of νCO for trans-[RhCl(CO){PR1 R2}2] (26, 27, 29), cis-[RhCl(CO)2{PR1 R2}] (28, 30) and JPSe for Se᎐PR1 R2 of various
2
2
᎐
2
monodentate P-based ligands
Ligand
R1
Rh Complex
Se᎐PR1 R2
᎐
2
Entry
R2
νCO/cmϪ1
δ(31P)/ppm
1JPSe/Hz
Ref.
f
f
f
f
f
f
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Ph
Ph
NEt2 (1)
NPri2 (2)
Ph (3)
Me (4)
Ph (5)
F5C6 (6)
Cl (7)
NMe2
Me
NMe2
Ph
Ph
NEt2
Me
Me
1974a (26)
67.1b
59.7b
77.6b
56.6b
746
744
761
761
1973a (27)
NEt2
NPri2
NPri2
NPri2
NPri2
Me
NMe2
NMe2
NMe2
Npyrre
NEt2
Npyrre
Me
2091, 2007a (28)
1955a (29)
2089, 2004a (30)
70.2b
759
c
c
c
53.0b
59.0b, f
80.5b, f
81.2b, f
84.0b, f
70.8b, f
77.1
884
720
767
805
790
759f
794
735
684
736
963
1027
38f
39
39
19, 40
39
15
41
15
19, 39
19, 39
19, 39
19, 40
c
—
—
1959
—
1949
—
1947
1966
1978
1998
2016
66.0a
8.0
Ph
OMe
OPh
Ph
OMe
OPh
34.1b
77.5
58.6
a CDCl3. b CDCl3, 101.3 MHz. c No reaction observed with either Se or {Rh(CO)2Cl}2. d No clean reaction observed with [{Rh(CO)2Cl}2]. e Npyrr =
pyrrolydinyl. f This work.
fluorine atoms are the major factor in preventing coordination
of phosphine 6 to metals.
Surprisingly, rather than the desired bis(phosphine) com-
plexes, the reaction of four equivalents of either ligand 3 or 5
with [{RhCl(CO)2}2] led to the formation of cis-[RhCl-
(CO)2(P{NR2}2Ph)] {R = Et (28), Pri (30)}. Complexes with
identical analytical data can be prepared through direct
reaction of [{RhCl(CO)2}2] with two equivalents of 3 or 5.
The coordination of 5 to rhodium() contrasts with the lack
of reactivity observed towards the Group 6 carbonyls and
PtCl2(L2), something that reflects the lability of the Rh()
complex.
Despite a number of attempts, neither crystals of 28 or 30
suitable for a molecular structure determination could be
obtained. The presence of only one phosphorus-containing
Fig. 2 Molecular structure of diaminophosphine 6 with the thermal
ligand is however evident from elemental analysis and IR
ellipsoids set at the 30% probability level.
spectroscopy, the latter exhibiting two intense carbonyl bands
at ca. 2090 and 2006 cmϪ1. Furthermore, two resonances are
Table 4 Selected bond lengths (Å) and angles (Њ) for 6
observed in the carbonyl region of the 13C NMR spectrum of
1
2
P(1)–N(1)
P(1)–N(2)
P(1)–C(1)
C(1)–C(2)
C(1)–C(6)
1.683(3)
1.669(4)
1.896(5)
1.385(6)
1.387(6)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
1.375(6)
1.379(7)
1.366(7)
1.379(6)
30 (δ 184.4 {br}, 182.4 {dd, JRhC 143.0 Hz, JPC 57.0 Hz}),
although only a severely broadened CO resonance was detected
for 28 (δ 183.1). These data are in good agreement with those
reported for an analogous complex cis-[RhCl(CO)2(PPh3)]
characterised in situ.52 Notably, the 31P NMR chemical shifts for
complexes 28 and 30 are comparable to those for the bis(phos-
N(2)–P(1)–N(1)
N(2)–P(1)–C(1)
N(1)–P(1)–C(1)
C(8)–N(1)–C(11)
C(8)–N(1)–P(1)
109.17(19)
108.0(2)
98.41(18)
116.3(3)
125.5(3)
C(11)–N(1)–P(1)
C(14)–N(2)–C(17)
C(14)–N(2)–P(1)
C(17)–N(2)–P(1)
117.3(3)
114.4(4)
128.3(3)
116.9(3)
1
phine) complexes 26, 27 and 29, while the associated JPRh
coupling constants are only slightly greater at ca. 147 Hz.
Generally, rhodium() dicarbonyl phosphine complexes, cis-
[RhCl(CO)2(L)] (L = PR3), can only be identified in solution as
they are unstable towards loss of CO, evolving to dimeric
[Rh(µ-Cl)(CO)(L)]2.52–54 In contrast, complexes in which ligand
L is an amine, phosphine oxide, or enamine, are stable and
can be isolated, presumably as a consequence of their lower
π-acceptor and greater σ-donor character, relative to tertiary
phosphines.55–57 Hence, the fact that complexes 28 and 30 are
isolable, is in good accord with the elevated basicity and poor
π-acceptance expected for bis(dialkylamino)-phosphines.15,19
However, why bridge splitting reactions of [{RhCl(CO)2}2]
should lead to monophosphine complexes for ligands 2 and 5
remains unclear.
indicative of a degree of P–N multiple bond character.47 The
P(1)–C(1) bond distance of 1.896(5) Å that is relatively long
compared to a typical P–C single bond, lying between the
distances observed in P(C6F5)3, Ph2PC6F5 (P–CArF distances
1.834 and 1.846 Å, respectively) and (Pri2N)2P–fluorenyl
[1.99(7) Å].48–50 Together these data suggest that the elongation
of the P–C bond in 6 must largely be ascribed to a negative
hyperconjugation effect through N(nσ)
P(1)–C(1)σ*
donation.51
The metric parameters about phosphorus are consistent with
other examples of metal-bound P(NPri2)2-derived phosphines
that have been reported in the literature.20 Thus it appears that
steric constraints imposed by the two amino groups and ortho-
Interestingly, complex 29 (ligand 4, entry 4, Table 3) exhibits
a value of νCO (1955 cmϪ1) that lies in the zone typical of a
tris(amino)phosphine, but is also remarkably similar to that
D a l t o n T r a n s . , 2 0 0 3 , 1 0 4 – 1 1 3
108

View Article Online
determined for the rhodium complex of di-tert-butylpyrrol-
idinylphosphine.16 The value of νCO for the latter (1955
cmϪ1), consistent with unexpectedly poor donor character, was
believed to arise from steric constraints upon the interaction of
the nitrogen with the phosphorus centre.
Since not all the ligands discussed here afforded trans-
[RhCl(CO){PR3}2)] complexes suitable for comparison by IR
spectroscopy and because it is difficult to separate σ-donor/
π-acceptor contributions using this approach, an alternative
strategy was sought in order to probe variations in the electronic
nature of the various phosphine ligands.
Pt- or W-bound dialkylaminophosphines can only be induced,
albeit cleanly, in the presence of gaseous HCl, affording a simple
route for the preparation of either the analogous phosphinite or
the synthetically versatile chlorophosphine complexes. These
observations open the way to the use of the extremely diverse
range of acyclic aminophosphines B and C in catalysis.
It has been demonstrated that the 31P NMR spectroscopic
data for related trans-[RhCl(CO)2(PR3)] and trans-[RhCl-
(CO)(PR3)2] complexes are extremely similar and can not be
used to distinguish between the two structures. Since there has
been considerable recent interest in the use of these types of
Rh() chloro-monocarbonyl complex as probes to measure
ligand basicity, it should be noted that it is essential that either
elemental analyses or 13C NMR data consistent with the
formulation of the bis(phosphine) complex, have been obtained
before any meaningful comparison of νCO frequencies can be
made. The preparation of selenium adducts of phosphines and
examination of the attendant 1JPSe coupling constants provides
a simple, yet complementary technique for estimating the
σ-donor ability of phosphines, especially where the desired
rhodium() carbonyl complexes are inaccessible.
Phosphine selenides. There exists a well established corre-
1
lation between the magnitude of JPSe coupling constants
and the basicity of phosphines.58–62 It has been demonstrated
1
that the greater the JPSe coupling constant the greater the
s-character of the P lone pair, meaning that poorly donating
phosphines will exhibit values of 1JPSe that are larger than those
for electron-rich phosphines.
The selenium derivatives of phosphines 1–5 and 7 were pre-
pared as solutions in CDCl3 by addition of a slight excess of
‘grey’ selenium followed by sonication, then subsequently char-
acterised in situ by multinuclear NMR spectroscopy. In each
case a single new resonance was observed by 31P NMR spectro-
scopy that exhibited coupling to 77Se (Table 3), except with
phosphine 6 where, despite both prolonged heating and sonica-
tion, no reaction was observed to occur. This lack of reactivity
is presumed to reflect an inaccessibility of the phosphorus lone
pair on steric grounds combined with the electron withdrawing
effect of the pentafluorophenyl substituent (vide supra).
Thus, using the criteria outlined above, the aminophosphines
1–5 and 7 can be ordered in terms of decreasing donor capabil-
ity: 1, 2 (1JPSe ≈ 745 Hz) > 3–5 (1JPSe ≈ 760 Hz) > 7 (1JPSe = 884
Experimental
General considerations
All manipulations of air and/or water sensitive materials were
performed under an atmosphere of nitrogen using standard
Schlenk and cannula techniques or in a conventional nitrogen-
filled glove box (unless stated otherwise). Solvents were freshly
distilled under nitrogen from sodium–benzophenone (tetra-
hydrofuran, diethyl ether, toluene, dme), from calcium hydride
(dichloromethane), from sodium (hexane, pentane, 40–60 PE)
or from P2O5 (C6D6 and CDCl3) and degassed prior to use.
Elemental analyses were performed by C.H.N. Analyses Ltd.,
Butterworth Laboratories Ltd., or by S. Boyer at the University
of North London. NMR spectra were recorded on a Bruker
AM 250, AMX 300, AMX 400, Varian EM 390 or JEOL JNM-
FX 90Q; chemical shifts were referenced to residual protio
impurities in the deuterated solvent (1H), to the deuterated
solvent (13C), external CFCl3 (19F), or to external aqueous 85%
H3PO4 (31P). All spectra were obtained at ambient probe tem-
peratures unless stated otherwise. Infrared spectra were
recorded (Nujol mulls [KBr windows], KBr discs, or in solution
[KBr windows]) on a Perkin-Elmer 1600 spectrophotometer;
Nujol was dried over sodium wire. Mass spectra were recorded
on a Kratos Concept 1H instrument and are reported in m/z.
Sonication was achieved by suspending the desired reaction
vessel in a water-filled Grant Ultrasonic Bath XB2.
Hz). For the series Se᎐PRЈ x(NRЉ2)x (x = 0–3; RЈ = Me, Ph;
᎐
3
Ϫ
RЉ = alkyl), as the number of amino groups (ϪI effect) increase,
1
so the magnitude of JPSe increases, making these phosphines
progressively less electron-rich, as expected. This agrees with
donor strength predications made from an examination of νCO
for the rather limited set of rhodium complexes possible 26
(1974 cmϪ1), 27 (1973 cmϪ1) and 29 (1955 cmϪ1), 1 ≈ 2 > 4.
There is no significant difference in the magnitudes of the
1JPSe coupling constants between phosphine 4, the related
P(Npyrr)2Ph (Entry 12, Table 3), 3 and 5 (all ca. 760 Hz),
suggesting that the potential donor capability of each system
is comparable. Since only the latter two phosphines afford
cis-[RhCl(CO)2(L)] it suggests that steric rather than electronic
factors are most significant in determining the outcome of their
reactions with [{RhCl(CO)2}2].
1
A significantly smaller magnitude of JPSe coupling constant
cis-[Mo(CO)4(pip)2], fac-[Cr(CO)3(NCCH3)3], (F5C6)MgBr,63
PNPri2(Ph)2 (2),29 P{NEt2}2Me,8 P(NPri2)2Me (4),64 and
P{NPri2}2Ph (5)8 were prepared according to literature pro-
cedures. PNEt2(Ph)2 was prepared by treating Ph2PCl with 2
equivalents of diethylamine in refluxing toluene for 3 h. The
desired phosphine was obtained, sufficiently pure for further
reaction following removal of volatiles in vacuo, extraction with
dme and subsequent removal of solvent under vacuum: δH
(301.2 MHz, CDCl3) 7.28–7.45 (10H, m, PPh2), 3.08 (4H, dq,
3JPH 9.7 Hz, 3JHH 7.0 Hz, NCH2CH3), 0.92 (6H, t, 3JHH 7.0 Hz,
NCH2CH3); δP {1H} (122.0 MHz, CDCl3) ϩ66.8 (s).
P{NEt2}2Ph was prepared by a modification of the literature
procedure through reaction of PCl(NEt2)2 with PhLi: δP {1H}
(122.0 MHz, CDCl3) ϩ99.0 (s).65,66 All other chemicals were
obtained commercially and used as received. Melting points
were obtained in sealed glass tubes under nitrogen, using a Gal-
lenkamp Melting Point apparatus and are uncorrected.
(735 Hz) is observed for the known phosphine selenide Se᎐
᎐
P(Npyrr)2Me compared with that of its phenyl counterpart
(759 Hz) as would be expected from the relative inductive
effects of Me versus Ph, ϩI and ϪI, respectively (Entries 14 and
12, Table 3). However, the values of νCO for the rhodium carb-
onyl complexes of these two phosphines are comparable (1949
and 1947 cmϪ1, respectively).
Together these observations emphasise that measurement of
1
either νCO or JPSe alone, are not sufficient to predict the
behaviour of aminophsophines. Somewhat unsurprisingly,
trends in the reactivity of the P–N linkages of bound amino-
phosphines are thus subject to both steric and electronic effects.
Conclusion
Historically, the envisaged susceptibility of aminophosphine
ligands to air, moisture and protic solvents such as alcohols has
long been regarded as a limitation to their potential use.
However, by and large, complexes of the simple acyclic amino-
functionalised phosphines described here, show considerable
stability. Selective substitution reactions of the amino group of
Syntheses and reactions
P(NPri2)2(C6F5) 6. To a stirred, cooled (Ϫ78 ЊC) suspension
of PCl(Pri2N)2 (0.53 g, 2.00 mmol) in Et2O (25 cm3) was added
D a l t o n T r a n s . , 2 0 0 3 , 1 0 4 – 1 1 3
109

View Article Online
(F5C6)MgBr (0.8 M, Et2O, 3.2 mL, 2.50 mmol). The reaction
mixture was stirred at Ϫ78 ЊC for 2 h and the vessel was then
left to warm to rt and stirred at rt for 18 h. Extraction of the
product with hexane (20 cm3), followed by removal of solvent
in vacuo gave 6 as a white solid (0.64 g, 80%), (Found: C, 54.4;
H, 7.0; N, 7.0. C18H28N2F5P requires: C, 54.3; H, 7.1; N, 7.1%);
min. The 31P{1H} NMR spectrum of the crude, bright yellow
reaction mixture displayed numerous signals, one of which
could be attributed to the desired complex trans-[Mo(CO)4-
(P{Cl}Ph2)2], present as a minor component and identified
by comparison with the chemical shift of an authentic sample
prepared according to literature procedures.
3
δH (250.1 MHz; CDCl3) 3.48 [4H, sept, JHH 6.6 Hz,
3
PNCH(CH3)2], 1.27 [12H, d, JHH 6.7 Hz, PNCH(CH3)2], 1.04
trans-[W(CO)4(P{Cl}Ph2)2] 12. Anhydrous HCl gas was
bubbled through a CH2Cl2 solution (20 cm3) of 10 (0.20 g, 0.25
mmol) for 30 min to give a lemon yellow solution. Volatile
components were removed in vacuo and the residue extracted
with Et2O (60 cm3). The resulting solution was concentrated
and afforded bright yellow crystals of 12 on standing (0.14 g,
77%), mp 148–150 ЊC, (Found: C, 45.5; H, 2.8; N, 0.0.
C28H20Cl2O4P2W requires C, 45.6; H, 2.7; N, 0.0%); δH (90.0
MHz, CDCl3) 7.50–7.30 (20H, m, PPh2); δC{1H} (75.5 MHz,
CDCl3) 200.1 (t, CO, 2JCP 6.8 Hz).
3
[12H, d, JHH 6.7 Hz, PNCH(CH3)2]; δC{1H} (75.8 MHz;
CDCl3) C6F5 not observed,|| 49.17 [d, 2JPC 13.8, PNCH(CH3)2],
3
3
23.85 [d, JPC 7.2, PNCH(CH3)2], 23.48 [d, JPC 7.8,
PNCH(CH3)2].
trans-[Cr(CO)4(P{NEt2}Ph2)2] 8. A solution of PNEt2(Ph)2
(1.2 g, 4.67 mmol) in benzene (10 cm3) was added to a stirred
suspension of [Cr(CO)3(MeCN)3] (0.4 g, 1.54 mmol) in benzene
(25 cm3). The reaction mixture was stirred overnight, filtered
and the solvent removed in vacuo. Addition of excess Et2O
precipitated a yellow crystalline solid from the oily residue. This
was filtered, washed with light petroleum and dried in vacuo to
afford 8 (0.49 g, 70% based on CO groups), mp 135–137 ЊC,
(Found: C, 63.5; H, 6.0; N, 4.1. C36H40N2O4P2Cr requires C,
63.7; H, 5.9; N, 4.1%); δH (90.0 MHz, CDCl3) 7.42–7.28 (20H,
trans-[W(CO)4(P{OMe}Ph2)2] 13. Anhydrous HCl gas was
bubbled through a stirred suspension of 10 (0.40 g, 0.50 mmol)
in MeOH (15 cm3) for 30 min. A cream coloured material was
formed. Following removal of volatile components in vacuo, the
residue was extracted with Et2O (60 cm3). The resulting solution
was concentrated and afforded an off-white solid 13 on stand-
ing (0.23 g, 64%), mp 156–157 ЊC, (Found: C, 48.8; H, 3.6; N,
0.0. C30H26O6P2W requires C, 49.5; H, 3.6; N, 0.0%); ν/cmϪ1,
1882 (vs, CO); δH (300.0 MHz, CDCl3) 7.45–7.26 (20H, m,
3
m, PNEt2Ph2), 3.15 (8H, m, CH2CH3), 0.73 (12H, t, JHH 6.1
2
Hz, CH2CH3); δC{1H} (75.5 MHz, CDCl3) 223.0 (t, CO, JCP
13.4 Hz).
3
5
trans-[Mo(CO)4(P{NEt2}Ph2)2] 9. A solution of P(NEt2)Ph2
(0.40 g, 1.60 mmol) in CH2Cl2 (10 cm3) was added to a stirred
suspension of [Mo(CO)4(pip)2] (0.30 g, 0.79 mmol) in CH2Cl2
(20 cm3) and the reaction mixture was stirred for 2 h. The
solution was concentrated to ca. 10 cm3. Addition of Et2O gave
a creamy white precipitate of 9 that was dried in vacuo (0.45 g,
79%), mp 156–158 ЊC, (Found: C, 59.9; H, 5.60; N, 3.9.
C36H40N2O4P2Mo requires C, 59.8; H, 5.5; N, 3.9%); δH (90.0
MHz, CDCl3) 7.40–7.29 (20H, m, PNEt2Ph2), 2.85 (8H, m,
PPh2), 3.45 (6H, second order d, JPH ϩ JPH 13.2 Hz, OMe);
δC{1H} (75.5 MHz, CDCl3) 201.6 (t, CO, 2JCP 7.1 Hz).
trans-[W(CO)4(P{OEt}Ph2)2] 14. A similar procedure to that
used for the preparation of 13 was adopted, passing HCl gas
through a suspension of 10 (0.40 g, 0.50 mmol) in EtOH
(10 cm3) for 30 min. Complex 14 was isolated as a yellow solid
(0.21 g, 56%), mp 156–157 ЊC, (Found: C, 50.5; H, 3.9; N, 0.0.
C32H30O6P2W requires C, 50.8; H, 4.0; N, 0.0%); δH (90.0 MHz,
CDCl3) 7.65–7.32 (20H, m, PPh2), 4.02 (4H, m, CH2CH3), 1.58
3
CH2CH3), 0.65 (12H, t, JHH 6.3 Hz, CH2CH3); δC{1H} (75.5
MHz, CDCl3) 216.0 (t, CO, 2JCP 12.0 Hz).
3
(6H, t, JHH 6.1 Hz, CH2CH3); δC{1H} (75.5 MHz, CDCl3)
200.9 (t, CO, 2JCP 7.9 Hz).
trans-[W(CO)4(P{NEt2}Ph2)2] 10. A solution of P(NEt2)Ph2
(0.34 g, 1.32 mmol) in benzene (10 cm3) was added to a stirred
suspension of of [W(CO)4(pip)2] (0.30 g, 0.64 mmol) in benzene
(20 cm3) and the reaction mixture was heated at reflux for 3 h
to afford a dirty yellow solution, which was filtered and all
volatiles removed in vacuo. Recrystallisation from CH2Cl2–Et2O
afforded yellow microcrystals of 10 that were dried in vacuo
(0.43 g, 64%), mp 162–165 ЊC, (Found: C, 53.3; H, 5.0; N, 3.4.
C36H40N2O4P2W requires C, 53.1; H, 4.9; N, 3.5%); δH (90.0
MHz, CDCl3) 7.5–7.28 (20H, m, PNEt2Ph2), 3.23 (8H, m,
trans-[W(CO)4(P{OCH2CHCH2}Ph2)2] 15. A similar pro-
cedure to that used for the preparation of 13 was adopted,
passing HCl gas through a suspension of 10 (0.40 g, 0.50 mmol)
in allyl alcohol (6 cm3) for 30 min. Complex 15 was isolated as a
bright yellow solid (0.27 g, 70%), mp 121–122 ЊC, (Found: C,
51.1; H, 3.8; N, 0.0. C32H30O6P2W requires C, 52.2; H, 3.8; N,
0.0%); δH (90.0 MHz, CDCl3) 7.60–7.28 (20H, m, PPh2), 5.70
(2H, m, OCH2CHCH2), 5.18 (4H, m, OCH2CHCH2), 4.02 (4H,
3
d, JHH 6.1 Hz, OCH2CHCH2); δC{1H} (75.5 MHz, CDCl3)
3
CH2CH3), 0.85 (12H, t, JHH 6.3 Hz, CH2CH3); δC{1H} (75.5
201.5 (t, CO, 2JCP 7.3 Hz).
MHz, CDCl3) 203.5 (t, CO, 2JCP 6.3 Hz).
Reaction of 10 with ethylene glycol in the presence of HCl gas.
Using a procedure analogous to that used above, HCl gas was
bubbled through a suspension of 10 (0.40 g, 0.44 mmol) in
ethylene glycol (6 cm3) for 30 min. The 31P NMR spectrum of
the resulting yellow solution revealed only the presence of 12.
trans-[Cr(CO)4(P{Cl}Ph2)2] 11. Anhydrous HCl gas was
bubbled through a CH2Cl2 solution (20 cm3) of 8 (0.20 g, 0.77
mmol) for 15 min during which time the colour changed from
pale yellow to bright yellow. Volatile components were removed
in vacuo and the residue extracted with Et2O (30 cm3). The
resulting solution was concentrated and afforded bright yellow
crystals of 11 on standing (0.15 g, 84%), mp 155–157 ЊC,
(Found: C, 55.0; H, 3.4; N, 0.0. C28H20Cl2O4P2Cr requires C,
55.5; H, 3.3; N, 0.0%); δH (90.0 MHz, CDCl3) 7.52–7.30 (20H,
trans-[W(CO)4(P{OH}Ph2)2]ؒCH2Cl2 16. H2SO4 (10%, 5 cm3)
was added to a solution of 10 (0.5 g, 0.62 mmol) in CH2Cl2
(5 cm3). The emulsion was stirred for 24 h. The CH2Cl2 layer
was separated, washed with several portions of degassed water,
and dried over anhydrous MgSO4. The solvent was removed in
vacuo, the residue washed with Et2O (20 cm3), and the product
dried in vacuo. Complex 16 was isolated as a purple, micro-
crystalline solid (0.35 g, 81%), mp 97–102 ЊC, (Found: C, 44.5;
H, 3.1; N, 0.0. C29H24Cl2O6P2W requires C, 45.2; H, 3.0; N,
0.0%); δH (90.0 MHz, CDCl3) 7.50–7.31 (20H, m, PPh2), 5.30
(2H, s, CH2Cl2); OH not observed, but addition of D2O led
to appearance of a signal due to HOD at δ 4.20 ppm; δC{1H}
(75.5 MHz, CDCl3) 200.8 (t, CO, 2JCP 16.9 Hz).
2
m, PPh2); δC{1H} (75.5 MHz, CDCl3) 218.7 (t, CO, JCP 13.9
Hz).
Reaction of 9 with anhydrous HCl gas. A similar procedure
was employed to that used for the preparation of 11 and
bubbling HCl through a solution of 9 (0.20 g, 0.28 mmol) for 20
|| The aromatic carbon signals could not be observed, presumably due
to extensive coupling with both fluorine and phosphorus.
D a l t o n T r a n s . , 2 0 0 3 , 1 0 4 – 1 1 3
110

View Article Online
cis-[PtCl2(P{NEt2}Ph2)2] 17. A solution of PNEt2(Ph)2 (0.4 g,
1.56 mmol) in CH2Cl2 (10 cm3) was added to a solution of
[PtCl2(cod)] (0.25 g, 0.67 mmol) in CH2Cl2 (20 cm3). A clear,
pale yellow solution was obtained after stirring for 2 h at rt. The
solvent was removed in vacuo and the residue washed with
hexane. Recrystallisation from CH2Cl2 and hexane afforded 17
as a white crystalline material (0.46 g, 88%), mp 113–114 ЊC
(Found: C, 50.1; H, 5.6; N, 3.4. C32H40N2Cl2P2Pt requires C,
49.2; H, 5.1; N, 3.6%); δH (90.0 MHz, CDCl3) 7.38–7.26
(20H, m, PPh2NEt2), 3.37 (8H, m, CH2CH3), 0.93 (12H, t, 3JHH
6.1 Hz, CH2CH3).
g, 0.26 mmol) in ethylene glycol (6 cm3) for 30 min. 31P NMR
spectroscopy revealed only the formation of the cis-chloro-
phosphine derivative 22.
Reaction of 18 with MeOH in the presence of HCl gas. HCl
gas was bubbled through a stirred MeOH solution (15 cm3) of
18 (0.15 g, 0.18 mmol) for 15 min. Using the same procedure as
before a white microcrystalline compound identified as cis-19.
Reaction of 18 with EtOH in the presence of HCl gas. HCl gas
was bubbled through a stirred EtOH solution (15 cm3) of 18
(0.15 g, 0.18 mmol) for 15 min. Using the same procedure as
before a white microcrystalline compound identified as cis-20.
trans-[PtCl2(P{NPri2}Ph2)2] 18. In a similar procedure to that
used above, reaction of Ph2PNPri2 (0.4 g, 1.4 mmol) with
[PtCl2(cod)] (0.25 g, 0.7 mmol) in CH2Cl2 (25 cm3) gave 18 as
yellow crystals (0.45 g, 81%), mp 149–150 ЊC (Found: C, 51.7;
H, 5.8; N, 3.3. C36H48N2Cl2P2Pt requires C, 51.7; H, 5.7; N,
3.4%); δH (90.0 MHz, CDCl3) 7.49–7.29 (20H,m, PPh2), 4.18
(4H, m, CHMe2), 1.25 (24H, d, 3JHH 6.6 Hz, CH2Me2).
Reaction of 14 with CH2CHCH2OH in the presence of HCl
gas. HCl gas was bubbled through a stirred CH2CHCH2OH
solution (10 cm3) of 18 (0.15 g, 0.18 mmol) for 15 min. Using
the same procedure as before a white microcrystalline com-
pound identified as cis-21.
Reaction of 13 with HCl gas. HCl gas was bubbled through a
stirred CH2Cl2 solution (20 cm3) of 17 (0.2 g, 0.26 mmol) for 15
min. The solvent was removed in vacuo and the white residue
extracted with THF (20 cm3). The solution was concentrated
and addition of Et2O afforded a white microcrystalline com-
pound identified as cis-[PtCl2(PPh2Cl)2] (22) by comparison
with data obtained from an authentic sample.
Reaction of 18 with HOCH2CH2OH in the presence of HCl.
As above, HCl gas was bubbled through a suspension of
18 (0.15 g, 0.18 mmol) in ethylene glycol (6 cm3) for 15 min.
31P NMR spectroscopy revealed only the formation of the
cis-chlorophosphine derivative 22.
Attempted isomerisation of cis-[PtCl2(PPh2Cl)2] (22). A
toluene solution of 22 (0.1 g, 0.14 mmol) was heated at reflux
for 5 d and afforded a mixture of cis-(22) and trans-(23)
isomers, in a ratio of 45 : 55%, respectively, deduced from
the integration of the 31P{1H} NMR spectrum of the crude
reaction mixture.
Reaction of 18 with HCl gas. HCl gas was bubbled through a
stirred CH2Cl2 solution (20 cm3) of 18 (0.25 g, 0.3 mmol) for 30
min. Using the same procedure as before a white microcrystal-
line compound identified as the cis-complex 22 by comparison
with data obtained from an authentic sample.
Attempted Cl-ion-catalysed isomerisation of cis-[PtCl2-
(PPh2Cl)2] (22). A toluene solution of 22 (0.1 g, 0.14 mmol)
containing a catalytic quantity of [Pri2NH2]Cl (2 mg, 0.01
mmol) was heated at reflux for 5 d. The 31P{1H} NMR
spectrum of the crude reaction mixture revealed a cis/trans-
ratio, 22 : 23, of 25 : 75%.
Reaction of 17 with MeOH in the presence of HCl. HCl gas
was bubbled through a stirred MeOH suspension (15 cm3) of 17
(0.2 g, 0.26 mmol) for 30 min. During which time the white
suspension changed to a clear solution. The solvent was
removed in vacuo and the white residue washed with H2O
(10 cm3). The residue was redissolved in CH2Cl2 (15 cm3) and
dried over MgSO4. The solution was concentrated and addition
of hexane afforded a white microcrystalline compound identi-
fied as cis-[PtCl2(P{OMe}Ph2)2] (19) (0.14 g, 78%), mp >230 ЊC
(Found: C, 45.0; H, 3.8. C26H26O2Cl2P2Pt requires C, 44.7; H,
3.8%); δH (90.0 MHz, CD2Cl2) 7.55–7.30 (20H, m, PPh2), 3.36
(6H, d, 3JHP 12.4, CH3).
Attempted reaction of 17 with H2SO4 (aq.). Complex 17
(0.2 g, 0.78 mmol) was dissolved in CH2Cl2 (8 cm3) and stirred
with H2SO4 (aq.) (8 cm3) of varying concentrations (10–50%
v/v) for 3 h. Only unreacted starting material was isolated in
each case, as shown by 31P{1H} NMR spectroscopy.
Attempted reaction of 17 with 1.0 M HCl. Treatment of 13
(0.2 g, 0.78 mmol) in water (10 cm3) with HCl (1.0 M, 10 cm3)
afforded only unreacted starting material according to 31P{1H}
NMR spectroscopy.
Reaction of 17 with EtOH in the presence of HCl. HCl gas
was bubbled through a stirred EtOH suspension (15 cm3) of 17
(0.2 g, 0.26 mmol) for 30 min. The solvent was removed in
vacuo and the white residue extracted with THF (20 cm3). The
solution was concentrated and addition of Et2O afforded a
white microcrystalline compound identified as cis-[PtCl2(P{O-
Et}Ph2)2] (20) (0.15 g, 81%), mp >230 ЊC (Found: C, 46.2; H,
4.2. C28H30O2Cl2P2Pt requires C, 46.3; H, 4.2%); δH (90.0 MHz,
CD2Cl2) 7.6–7.29 (20H, m, PPh2), 3.8 (4H, m, CH2CH3), 1.08
(6H, t, 3JHH 6.1 Hz, CH2CH3).
Attempted reaction of 18 with H2SO4 (aq.) and HBF4 (50% in
H2O). Complex 18, under identical conditions to those used for
17, did not react with either acid according to 31P{1H} NMR
spectroscopy.
Reaction of 18 with 1.0 M HCl. Treatment of 18 (0.2 g, 0.16
mmol) in water (10 cm3) with HCl (1.0 M, 10 cm3) afforded
the cis-chlorophosphine complex 22 (ca. 10%) in addition to
unreacted 18 and a number of unidentifiable phosphorus-
containing products according to 31P{1H} NMR spectroscopy.
Reaction of 17 with CH2CHCH2OH in the presence of HCl.
As above, HCl gas was bubbled through a suspension of 17 (0.2
g, 0.26 mmol) in allyl alcohol (15 cm3) for 30 min. Recrystallis-
ation from CH2Cl2–hexane yielded a crystalline compound
identified as cis-[PtCl2(P{OCH2CHCH2}Ph2)2] (21) (0.14 g,
73%), mp 157–158 ЊC (Found: C, 47.6; H, 4.0. C30H30O2Cl2P2Pt
requires C, 48.0; H, 4.0%); δH (90.0 MHz, CDCl3) 7.50–7.29
(20H, m, PPh2), 5.50 (2H, m, CH2CHCH2), 5.05 (4H, m,
CH2CHCH2), 4.20 (4H, m, POCH2).
trans-[PtCl2(P{NEt2}2Ph)2] 24. Using a procedure analogous
to that for the preparation of 18, reaction of P(NEt2)2Ph
(0.25 g, 1.0 mmol) with [PtCl2(cod)] (0.17 g, 0.5 mmol) in
CH2Cl2 (15 cm3) gave 24 as yellow crystals (0.45 g, 81%), mp
148–150 ЊC (Found: C, 43.9; H, 6.6; N, 7.1 C28H50N4Cl2P2Pt
requires C, 43.6; H, 6.5; N, 7.3%); δH (301.2 MHz, CDCl3)
7.39–7.23 (10H, m, PPh), 3.40 (16H, m, CH2CH3), 0.96 (24H, t,
3JHH 6.1 Hz, CH2CH3).
Reaction of 17 with HOCH2CH2OH in the presence of HCl.
As above, HCl gas was bubbled through a suspension of 17 (0.2
D a l t o n T r a n s . , 2 0 0 3 , 1 0 4 – 1 1 3
111

View Article Online
trans-[PtCl2(P{NPri2}2Me)2] 25. An NMR tube fitted with a
J. Young’s valve was charged under nitrogen with [PtCl2(cod)]
(18.8 mg, 0.05 mmol) and a solution of MeP{NPri2}2 (25 mg,
0.10 mmol) in CDCl3 (0.5 cm3) added. On standing at rt for 2 h,
the sample was transferred under nitrogen to a Schlenk line, all
volatiles removed in vacuo to give an off white solid. Washing
with 40–60 PE (3 × 2 cm3) gave 25 as a white solid (28 mg, 74%),
mp 155–157 ЊC, (Found: C, 41.5; H, 8.3; N, 7.3 C26H62N4-
Cl2P2Pt requires C, 41.2; H, 8.2; N, 7.4%); δH (250.1 MHz,
spectroscopies and was subsequently isolated as an orange
solid, 118 mg, 83%. (Found: C, 49.7; H, 9.3; N, 8.3.
C27H62Cl1N4O1P2Rh requires C, 49.2; H, 9.5; N, 8.5%); δH
(250.1 MHz, CDCl3) 4.16 [8H, sept, 3JHH 6.9 Hz, NCH(CH3)2],
2
3
1.94 (6H, t, JPH 2.3 Hz, PCH3), 1.40 [24H, d, JHH 6.9 Hz,
NCH(CH3)2], 1.22 [24H, d, JHH 6.9 Hz, NCH(CH3)2]; δC{1H}
3
(75.8 MHz, CDCl3) 189.9 (dt, 1JRhC 77.9 Hz, 2JPC 15.7 Hz, CO),
48.1 [t, 2JPC 5.1 Hz, NCH(CH3)2], 25.8 [s, NCH(CH3)2], 25.0 [s,
NCH(CH3)2], 23.6 (m, PCH3).
3
CDCl3) 4.23 [8H, sept., JHH 6.9 Hz, CH(CH3)2], 1.78 (6H,
3
pseudo t, PCH3), 1.42 [24H, t, JHH 6.9 Hz, CH(CH3)2], 1.30
Attempted synthesis of trans-[RhCl(CO)(P{NPri2}2Ph)2]. An
analogous procedure to that employed for the preparation of 26
was followed using [{RhCl(CO)2}2] (12.0 mg, 0.03 mmol) and a
solution of PhP(NPri2)2 (38 mg, 1.23 mmol) in CDCl3 (0.5 cm3).
Removal of all volatile components under reduced pressure
followed by washing with hexane (3 × 2 cm3) afforded the
monophosphine complex cis-[RhCl(CO)2(P{NPri2}2Ph)] (30) as
an orange solid, 23 mg, 77%. (Found: C, 46.49; H, 6.69; N, 5.73.
C19H33O2N2ClPRh requires C, 46.50; H, 6.78; N, 5.71%); δH
(250.1 MHz, CDCl3) 7.75–7.66 (2H, m, o-Ph), 7.30–7.24 (3H,
3
[24H, t, JHH 6.9 Hz, CH(CH3)2]; δC{1H} (62.9 MHz, CDCl3)
2
47.7 [pseudo t, JCP 4.4 Hz, CH(CH3)2], 25.5 [s, CH(CH3)2],
24.9 [s, CH(CH3)2], 19.0 (pseudo t, 2JCP 22.4 Hz, PCH3).
trans-[RhCl(CO)(P{NEt2}Ph2)2] 26. An NMR tube fitted
with a J. Young’s valve was charged under nitrogen with
[{RhCl(CO)2}2] (12.5 mg, 0.03 mmol) and a solution of
PNEt2(Ph)2 (33.0 mg, 0.19 mmol) in CDCl3 (0.5 cm3) added. An
immediate change in colour and evolution of gas was observed
to occur. After 30 minutes, when gas evolution had finished,
the tube was transferred to a Schlenk line, the solution was
freeze/thaw degassed, let down to a CO atmosphere and sealed.
3
3
m, m-/p-Ph), 4.03 [4H, d sept., JHH 7.0 Hz, JPH 2.5 Hz,
3
NCH(CH3)2], 1.33 [12H, d, JHH 7.0 Hz, NCH(CH3)2], 1.24
[12H, d, 3JHH 7.0 Hz, NCH(CH3)2]; δC{1H} (75.8 MHz, CDCl3)
Complex 26 formed as the only product according to IR and 31
P
1
2
184.1 (br, CO), 182.4 (dd, JRhC 143.0 Hz, JPC 57.0 Hz, CO),
139.1 (dd, 1JPC 54.5 Hz, 2JPC 4.0 Hz, ipso-Ph), 131.4 (d, 2JPC 14.0
NMR spectroscopies and was isolated after removal of all
volatile components in vacuo as an orange solid, 38 mg, 87%.
(Found: C, 58.28; H, 6.02; N, 4.05. C33H40ON2ClPRh requires
C, 58.20; H, 5.92; N, 4.11%); δH (250.1 MHz, CDCl3) 7.58
(8H, br, o-Ph), 7.24 (12H, m, m-/p-Ph), 3.28 (8H, br, CH2CH3),
4
3
Hz, o-Ph), 130.6 (d, JPC 1.0 Hz, p-Ph), 128.1 (d, JPC 11.0 Hz,
m-Ph), 50.8 [d, 2JPC 10.0 Hz, NCH(CH3)2], 25.9 [d, 3JPC 3.0 Hz,
NCH(CH3)2], 25.6 [d, 3JPC 3.0 Hz, NCH(CH3)2]; IR (νmax/cmϪ1,
CDCl3) 2089, 2004.
3
0.90 (12H, t, JHH 7.0 Hz, CH2CH3); δC{1H} (75.8 MHz,
1
CDCl3) 187.3 (s, CO), 136.1 (pseudo t, JPC 24.0 Hz, ipso-Ph),
Reaction of PCl(NPri2)2 with {RhCl(CO)2}2. An analogous
procedure to that employed for the preparation of 26 was
followed using [{RhCl(CO)2}2] (12 mg, 0.03 mmol) and a solu-
tion of PCl(NPri2)2 (33 mg, 1.23 mmol) in CDCl3 (0.5 cm3). The
31P NMR spectrum of the crude reaction mixture displayed
three sets of signals in a 2 : 1 : 1 ratio: δ 144.8 (d, 1JPRh 186 Hz),
136.2 (s, PCl{NPri2}2), and 130.5 (d, 1JPRh 192 Hz). No further
evolution was observed after 3 d at rt. Heating the mixture to 40
ЊC led to the formation an unidentifiable mixture of products
according to 31P NMR spectroscopy.
132.9 (br, o-Ph), 129.7 (s, p-Ph), 127.9 (br, m-Ph), 44.1
(s, CH2CH3), 14.1 (s, CH2CH3).
trans-[RhCl(CO)(P{NPri2}Ph2)2] 27. An analogous procedure
to that employed for the preparation of 26 was followed using
[{RhCl(CO)2}2] (13 mg, 0.03 mmol) and a solution of PNPri2-
(Ph)2 (38 mg, 1.34 mmol) in CDCl3 (0.5 cm3). Complex 27
formed as the only product according to IR and 31P NMR
spectroscopies and was subsequently isolated as an orange
solid, 42 mg, 86%. δH (250.1 MHz, CDCl3) 7.75–7.69 (8H, m,
o-Ph), 7.35–7.18 (12H, m, m-/p-Ph), 3.99 [4H, br, NCH(CH3)2],
Representative preparation of Se᎐PMe(NPri ) . An NMR
3
1.15 [24H, d, JHH 6.7 Hz, NCH(CH3)2]; δC{1H} (75.8 MHz,
᎐
2
2
tube fitted with a J. Young’s valve was charged with grey Se (26
mg, 0.28 mmol), PMe(NPri2)2 (66 mg, 2.66 × 10Ϫ4 mol) and
CDCl3 (0.5 mL) under nitrogen. The reaction mixture was
subject to sonication until complete reaction had occurred
according to 31P NMR spectroscopy.
CDCl3) 184.1 (br, CO), 136.8 (pseudo t, JPC 23.4 Hz, ipso-Ph),
133.4 (s, o-Ph), 129.5 (m, m-Ph), 127.6 (s, p-Ph), 52.2
[s, NCH(CH3)2], 24.9 [s, NCH(CH3)2].
Attempted synthesis of trans-[RhCl(CO)(P{NEt2}2Ph)2]. An
analogous procedure to that employed for the preparation of 26
was followed using [{RhCl(CO)2}2] (8 mg, 0.02 mmol) and a
solution of P(NEt2)2Ph (20 mg, 0.08 mmol) in CDCl3 (0.5 cm3).
Following removal of volatile components and washing with
hexane (3 × 2 cm3) the monophosphine complex cis-[RhCl-
(CO)2(P{NEt2}2Ph)] (28) was isolated as an orange solid, 16
mg, 87%; (Found: C, 42.9; H, 5.6; N, 6.2. C16H25N2O2ClPRh
requires C, 43.0; H, 5.6; N, 6.3%); δH (301.2 MHz, CDCl3)
7.70–7.61 (4H, m, o-Ph), 7.47–7.42 (6H, m, m-/p-Ph), 3.30
(16H, dq, 3JHH 7.0 Hz, 3JPH 10.2 Hz, NCH2CH3), 1.15 (24H, t,
3JHH 7.0 Hz, NCH2CH3); δC{1H} (75.8 MHz, CDCl3) 183.1
(br, CO), 136.3 (d, JPC 67.1 Hz, ipso-Ph), 133.4 (d, 2JPC 12.5 Hz,
Crystallography
Single crystals of phosphine 6 were obtained as colourless
plates following prolonged cooling (Ϫ30 ЊC) of a saturated
hexane solution. C18H28N2F5P, M = 398.39, orthorhombic,
space group Pbca, a = 12.9383(15), b = 10.3076(19), c =
29.874(3) Å, V = 3984.1(10) Å3, Z = 8, Dc = 1.328 Mg mϪ3,
µ(Mo-Kα) = 0.143 mmϪ1, F(000) = 1680, T = 183(2) K; 0.12 ×
0.40 × 0.42 mm, Bruker SMART 1000 diffractometer with
CCD area detector, ꢀ- and ω-scans, 1688 measured, 1092
independent reflections (Rint = 0.0336). The structure was solved
by direct methods and all non-hydrogen atoms were refined
anisotropically using full matrix least-squares based on F 2 to
give R1 = 0.0316, wR2 = 0.0668 (all data) for 783 independent
observed reflections [I > 2σ(I ), 2θ ≤ 52.62Њ] and 243 parameters.
The data : parameter ratio is poor (4.49), while the ratio of
unique/expected reflections was only 27% as a result of particu-
larly weak data.
3
o-Ph), 130.8 (s, p-Ph), 128.6 (d, JPC 21.5 Hz, m-Ph), 42.8
2
3
(d, JPC 6.2 Hz, NCH2), 14.5 (d, JPC 3.5 Hz, NCH2CH3); IR
(νmax/cmϪ1, CDCl3) 2091, 2007.
trans-[RhCl(CO)(P{NPri2}2Me)2] 29. An analogous pro-
cedure to that employed for the preparation of 26 was followed
using [{RhCl(CO)2}2] (42 mg, 0.11 mmol) and a solution of
P(NPri2)Me (106 mg, 0.43 mmol) in CDCl3 (0.5 cm3). Complex
29 formed as the only product according to IR and 31P NMR
CCDC reference number 193475.
See http://www.rsc.org/suppdata/dt/b2/b208886j/ for crystal-
lographic data in CIF or other electronic format.
D a l t o n T r a n s . , 2 0 0 3 , 1 0 4 – 1 1 3
112

View Article Online
30 P. S. Pregosin and R. W. Kunz, in 31P, 13C NMR of Transition
Acknowledgements
Metal Phosphine Complexes, eds. P. Diehl, E. Fluck and R. Kosfeld,
Springer-Verlag, Berlin, 1979.
31 P. Braunstein, Pierre, D. Matt, O. Bars, M. Louër, D. Grandjean,
J. Fischer and A. Mitschler, J. Organomet. Chem., 1981, 213, 79.
32 M. K. Cooper and J. M. Downes, Inorg. Chem., 1978, 17, 880.
33 R. Roulet and C. Barbey, Helv. Chim. Acta, 1973, 56, 2179.
34 W. J. Louw, Inorg. Chem., 1977, 16, 2147.
The Royal Society and The Nuffield Foundation are thanked
for grants to P. W. D. Johnson Matthey Plc. is thanked for the
loan of platinum salts. Financial support from the EPSRC,
Lubrizol Ltd. (CASE award M. J. H.), and The University of
Leicester is gratefully acknowledged.
35 E. H. Wong, M. M. Turnbull, K. D. Hutshinson, C. Valdez,
E. J. Gabe, F. L. Lee and Y. Le Page, J. Am. Chem. Soc., 1988, 110,
8422.
36 K. Diemert, W. Kuchen and D. Lorenzen, J. Organomet. Chem.,
1989, 378, 17.
References
1 A. Michaelis, Ann. Chem., 1903, 326, 129.
2 C. Rømming and J. Songstad, Acta Chem. Scand., Ser. A, 1978, 32,
689.
37 D. E. C. Corbridge, Phosphorus: An Outline of its Chemistry and
Biochemistry, 5th edn., Elsevier, Amsterdam, 1995, p. 51.
38 N. Burford, R. E. v. H. Spence and R. D. Rogers, J. Chem. Soc.,
Dalton Trans., 1990, 3611.
39 W. McFarlane and D. S. Rycroft, J. Chem. Soc., Dalton Trans., 1973,
2162.
3 See for example: J. G. Verkade and K. J. Coskram, in
Organophosphorus Compounds, eds. G. M. Kosolapoff and L. Maier,
Wiley, New York, 1972, vol. 2, p. 1; A. H. Cowley, R. E. Davies and
K. Remadna, Inorg. Chem., 1981, 20, 2146; R. B. King, Inorg.
Chem., 1963, 2, 936; S. A. Katz, V. S. Allured and A. D. Norman,
Inorg. Chem., 1994, 33, 1762.
40 E. Krawczyk, A. Skowronska and J. Michalski, J. Chem. Soc., Perkin
Trans. 2, 2000, 1135.
4 G. Ewart, D. S. Payne, A. L. Porte and A. P. Lane, J. Chem. Soc.,
1962, 3984.
5 D. S. Payne and A. P. Walker, J. Chem. Soc. C, 1966, 498.
6 M. Höfler and W. Marre, Angew. Chem., Int. Ed. Engl., 1971, 10,
187.
7 S. Singh and K. M. Nicholas, Chem. Commun., 1998, 149.
8 Y. Hayakawa, M. Hirose, M. Hayakawa and R. Noyori, J. Org.
Chem., 1995, 60, 925.
9 J.-J. Brunet, R. Chauvin, J. Chiffre, S. Huguet and P. Leglaye,
J. Organomet. Chem., 1998, 566, 117.
10 S. Juge, M. Stephan, J. A. Laffitte and J. P. Genet, Tetrahedron Lett.,
1990, 31, 6357.
11 N. R. Price and J. Chambers, in The Chemistry of Organophosphorus
Compounds, ed. F. R. Hartley, Wiley, Chichester, 1990, vol. 1,
p. 649.
12 Y. L. Bennani and S. Hanessian, Chem. Rev., 1997, 97, 3161.
13 H. Tye, D. Smyth, C. Eldred and M. Wills, Chem. Commun., 1997,
1053.
41 S. M. Godfrey, S. L. Jackson, C. A. McAuliffe and R. G. Pritchard,
J. Chem. Soc., Dalton Trans., 1998, 4201.
42 S. Serron, S. P. Nolan and K. G. Moloy, Organometallics, 1996, 15,
4301.
43 A. Huang, J. E. Marcone, K. L. Mason, W. J. Marshall,
K. G. Moloy, S. Seron and S. P. Nolan, Organometallics, 1997, 16,
3377.
44 D. De Montauzon and R. Poilblanc, J. Organomet. Chem., 1975, 93,
397.
45 T. Sakakura, T. Sodeyama, K. Sasaki, K. Wada and M. Tanaka,
J. Am. Chem. Soc., 1990, 112, 7221.
46 S. Vastag, B. Heil and L. Markó, J. Mol. Catal., 1979, 5, 189.
47 P–N single bond = 1.8 Å: L. Pauling, Nature of the Chemical Bond,
Cornell University Press, New York, 1960.
48 A. Karipides and C. M. Cosio, Acta Crystallogr., Sect. C, 1989, 45,
1743.
49 O. B. Shawkataly, M.-L. Chong, H.-K. Fun and K. Sivakumar, Acta
Crystallogr., Sect. C, 1996, 52, 1725.
14 J. Ansell and M. Wills, Chem. Soc. Rev., 2002, 31, 259.
15 M. L. Clarke, D. J. Cole-Hamilton, A. M. Z. Slawin and
J. D. Woollins, Chem. Commun., 2000, 2065.
16 M. L. Clarke, G. L. Holliday, A. M. Z. Slawin and J. D. Woollins,
J. Chem. Soc., Dalton Trans., 2002, 1093.
17 J. M. Brunel, A. Heumann and G. Buono, Angew. Chem., Int. Ed.,
2000, 39, 1946.
18 M. P. Magee, W. Luo and W. H. Hersh, Organometallics, 2002, 21,
362.
19 K. G. Moloy and J. L. Petersen, J. Am. Chem. Soc., 1995, 117, 7696.
20 F. Dahan, P. W. Dyer, M. J. Hanton, M. Jones, D. M. P. Mingos,
A. J. P. White, D. J. Williams and A.-M. Williamson, Eur. J. Inorg.
Chem., 2002, 737.
21 R. Kranich, K. Eis, O. Geis, S. Mühle, J. W. Bats and H. G. Schmalz,
Chem. Eur. J., 2000, 6, 2874.
22 R. B. King and P. M. Sundaram, J. Org. Chem., 1984, 49, 1784.
23 See for example: R. B. King and W.-K. Fu, Inorg. Chem., 1986, 25,
2384.
24 W. E. Piers and T. Chivers, Chem. Soc. Rev., 1997, 26, 345.
25 W.-K. Wong and F.-W. Lee, Polyhedron, 1992, 11, 863.
26 E. H. Wong and F. C. Bradley, Inorg. Chem., 1981, 20, 2333.
27 F. Mercier and F. Mathey, J. Chem. Soc., Chem. Commun., 1984,
782.
50 N. Burford, J. A. C. Clyburne, S. V. Sereda, T. S. Cameron,
J. A. Pincock and M. Lumsden, Organometallics, 1995, 14, 3762.
51 N. Poetschke, M. Nieger, M. A. Khan, E. Niecke and M. T. Ashby,
Inorg. Chem., 1997, 36, 4087.
52 E. Rotondo, G. Battaglia, G. Giordano and F. P. Cusmano,
J. Organomet. Chem., 1993, 450, 245.
53 P. Uguagliati, G. Deganello and U. Belluco, Inorg. Chim. Acta, 1974,
9, 203.
54 D. F. Steele and T. A. Stephenson, J. Chem. Soc., Dalton Trans.,
1972, 2161.
55 D. N. Lawson and G. Wilkinson, J. Chem. Soc., 1965, 1900.
56 G. Bandoli, D. Clemente, G. Deganello, G. Carturan, P. Uguagliati
and U. Belluco, J. Organomet. Chem., 1974, 71, 125.
57 J. W. Kang and P. M. Maitlis, Can. J. Chem., 1968, 46, 897.
58 N. G. Anderson and B. A. Keay, Chem. Rev., 2001, 101, 997.
59 C. Glidewell and E. J. Leslie, J. Chem. Soc., Dalton Trans., 1977, 527.
60 D. W. Allen and B. F. Taylor, J. Chem. Res. (S), 1981, 220.
61 R. D. Kroshefsky, R. Weiss and J. G. Verkade, Inorg. Chem., 1979,
18, 469.
62 D. W. Allen and B. R. Taylor, J. Chem. Soc., Dalton Trans., 1982, 51.
63 E. Nield, R. Stephens and J. C. Tatlow, J. Chem. Soc., 1959, 166.
64 Y. Hayakawa, M. Hirose, M. Hayakawa and R. Noyori, J. Org.
Chem., 1995, 60, 925.
28 K. Diemert, A. Hinz, W. Kuchen and D. Lorenzen, J. Organomet.
Chem., 1990, 393, 379.
29 H.-J. Cristau, A. Chêne and H. Christol, Synthesis, 1980, 7, 551.
65 R. M. Moriarty, J. Hiratake and K. Liu, J. Am. Chem. Soc., 1990,
112, 8575.
66 W. Hawes and S. Trippett, J. Chem. Soc. C, 1969, 1465.
D a l t o n T r a n s . , 2 0 0 3 , 1 0 4 – 1 1 3
113