Preparation and reactivity of mononuclear platinum(0) complexes containing a η2-coordinated alkynylphosphine

Article abstract of DOI:10.1039/b107015k

Displacement of ethene from [Pt(η²-C₂H₄)(dcpe)] by Ph₂PC≡CMe gives the monomeric η²-alkynylphosphine complex [Pt(η²-Ph₂PC≡CMe)(dcpe)] (5). Reaction of 5 with one equivalent of HCl forms, in benzene, the four-coordinate η¹-vinyl-platinum(II) complex [PtCl{C(=CHMe)PPh₂}(dcpe)] (6) by regiospecific addition of the proton to the alkyne carbon atom bearing the methyl group. In dichloromethane, reversible dissociation of the chloride ion from 6 takes place and the cation [Pt{C(=CHMe)PPh₂-κP,C¹}(dcpe)]⁺ (6′) that contains a three-membered methylenephosphaplatinacycle fragment can be observed. Treatment of complex 5 with methyl iodide results in the formation of a phosphonium salt [Pt{η²-C(=CH₂)=CHPPh₂Me}(dcpe)] ⁺I^-, [8]I, in which the alkynylphosphine has rearranged to the corresponding allene. The alkynylphosphine complex 5 is cleanly oxidised at phosphorus in the presence of sulfur or air to give the corresponding sulfide or oxide [Pt(η²-Ph₂P(X)C≡CMe)(dcpe)] (X = S (9), O (10)). Complexes 5, 6, 8, 9 and 10 have been structurally characterised by single-crystal X-ray diffraction analysis.

Full text of DOI:10.1039/b107015k

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Preparation and reactivity of mononuclear platinum(0) complexes
containing a ꢀ2-coordinated alkynylphosphine
Martin A. Bennett, Laurence Kwan, A. David Rae,† Eric Wenger* and Anthony C. Willis†
Research School of Chemistry, Australian National University, ACT 2000, Australia.
E-mail: wenger@rsc.anu.edu.au
Received 2nd August 2001, Accepted 5th November 2001
First published as an Advance Article on the web 17th December 2001
2
2
᎐
Displacement of ethene from [Pt(η -C H )(dcpe)] by Ph PC᎐CMe gives the monomeric η -alkynylphosphine
᎐
2
4
2
2
᎐
complex [Pt(η -Ph PC᎐CMe)(dcpe)] (5). Reaction of 5 with one equivalent of HCl forms, in benzene, the four-
᎐
2
coordinate η1-vinyl–platinum() complex [PtCl{C(᎐CHMe)PPh }(dcpe)] (6) by regiospecific addition of the proton
᎐
2
to the alkyne carbon atom bearing the methyl group. In dichloromethane, reversible dissociation of the chloride ion
from 6 takes place and the cation [Pt{C(᎐CHMe)PPh -κP, C1}(dcpe)]ϩ (6Ј) that contains a three-membered
᎐
2
methylenephosphaplatinacycle fragment can be observed. Treatment of complex 5 with methyl iodide results in the
formation of a phosphonium salt [Pt{η2-C(᎐CH )᎐CHPPh Me}(dcpe)]ϩIϪ, [8]I, in which the alkynylphosphine has
᎐
᎐
2
2
rearranged to the corresponding allene. The alkynylphosphine complex 5 is cleanly oxidised at phosphorus in the
2
᎐
presence of sulfur or air to give the corresponding sulfide or oxide [Pt(η -Ph P(X)C᎐CMe)(dcpe)] (X = S (9), O (10)).
᎐
2
Complexes 5, 6, 8, 9 and 10 have been structurally characterised by single-crystal X-ray diffraction analysis.
also formed as a result of proton addition to the carbon bear-
ing the PPh2 group instead of that carrying the substituent
Introduction
᎐
Although (alkynyl)diphenylphosphines, Ph PC᎐CR, commonly
᎐
2
R. Since five-coordination is less favoured for platinum()
than nickel(), and platinum() is larger and more basic than
nickel(), we thought it worthwhile for purposes of comparison
to examine the chemistry of an (alkynyl)diphenylphosphine
with platinum(). The results are reported here.
behave as simple P-donor ligands,1 they can also bridge a pair
of metal atoms via phosphorus and the triple bond, as in the
1
2
t
2
᎐
complexes [Ni (CO) (µ-η : η -Ph PC᎐C– Bu)], or [M(PPh )-
᎐
2
2
2
3
2
(µ-η1 : η -Ph PC᎐CCF )] (M = Pd, Pt).3 There are only a
᎐
᎐
2
3
2
few examples in which alkyne coordination is favoured, e.g.
2
4
2
᎐
[Co (CO) {µ-η -(C F ) PC᎐CR}] (R = Me, Ph), [(CpNi) (µ-η -
᎐
2
6
6
5
2
2
t
5
2
6
᎐
᎐
Results
Ph PC᎐C– Bu)] and [W(CO)(η -Ph PC᎐CPPh )(S CNEt ) ].
᎐
᎐
2
2
2
2
2 2
2
᎐
Reaction of the ethene complex [Pt(η2-C2H4)(dcpe)] with one
We have recently characterised the complexes [Ni(η -Ph PC᎐
᎐
2
CR)(dcpe)] [R = Me, Ph, CO2Me (1a–c); [dcpe = 1,2-bis(dicyclo-
hexylphosphino)ethane, (C6H11)2PCH2CH2P(C6H11)2], which
represent the first examples of this behaviour with nickel()
(3d10), and have shown that they react with HCl to form
five-coordinated nickel() complexes (2a–c) that contain a
three-membered methylenephosphanickelacycle (Scheme 1).7,8
In the cases of complexes 1b and 1c, small amounts of
isomeric four-coordinate nickel() complexes 3b and 3c are
᎐
mole equivalent of Ph PC᎐CMe in diethyl ether at 0 ЊC gives
᎐
2
initially a yellow–green solution, which is believed to contain a
platinum() complex of the P-coordinated alkynylphosphine,
1
[Pt(η -Ph PC᎐CMe) (dcpe)] (4). The 31P-{1H} NMR spectrum
᎐
᎐
2
2
of the solution exhibits two broad triplets assigned to 4 at δP
Ϫ22.9 and 36.2 [J(PP) = 53.1 Hz] with J(PtP) of 4190 and 3400
Hz, respectively, together with a singlet with 195Pt satellites at δP
72.4 [J(PtP) = 3151 Hz] due to unreacted ethene complex. The
multiplicity of the signal at δP 36.2, corresponding to coordin-
ated dcpe, suggests the presence of two coordinated alkynyl-
phosphines in 4.
When the solution is allowed to warm to room temperature,
the colour changes to yellow. The signals due to 4 disappear and
are replaced by a doublet of doublets at δP Ϫ11.5 and two sets
of doublets of doublets in the region δP 67–70, which are
assigned to the uncoordinated phosphorus atom and the dcpe
ligand, respectively, of the η2-coordinated species [Pt(η2-Ph2-
᎐
PC᎐CMe)(dcpe)] (5) (Scheme 2). Complex 5 can be isolated as a
᎐
colourless solid that, in contrast to its nickel() analogue 1a, is
stable almost indefinitely at room temperature in the absence of
air; its structure has been determined by single-crystal X-ray
crystallography (see below).
The 31P-{1H} NMR spectrum of 5 corresponds to a tightly
coupled ABMX spin system, and is similar to that of the nickel
2
8
᎐
analogue [Ni(η -Ph PC᎐CMe)(dcpe)]. The more deshielded
᎐
2
phosphorus atom of dcpe (δP 69.8) is probably that trans to the
alkyne carbon atom C1 bearing the PPh2 group since it shows
the larger of the two couplings with PPh2 (44.6 vs. 22.1 Hz) and
also with Pt (3281 vs. 2968 Hz); the latter values are typical of
1J(PtP) couplings in platinum()-alkyne complexes.9,10
Scheme 1
† Single crystal X-ray diffraction unit.
226
J. Chem. Soc., Dalton Trans., 2002, 226–233
This journal is © The Royal Society of Chemistry 2002
DOI: 10.1039/b107015k

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vinylphosphine but do not distinguish between the possibilities
[PtCl{η1-C(PPh )᎐CH(Me)}(dcpe)] (6) and [PtCl{η1-CMe᎐
᎐
᎐
2
CH(PPh2)}(dcpe)] (7) arising from proton addition to C2 or
C1, respectively. A single crystal X-ray diffraction study has
confirmed that the compound has structure 6 (see below); sev-
eral other observations discussed below point to the same
conclusion.
First, the 31P-{1H} NMR signal of the PPh2 group in 6 is
significantly less shielded than those in free alkenyldiphenyl-
phosphines19,20 or in the nickel()–vinyl complexes 3b (δP
Ϫ13.3) or 3c (δP Ϫ28.7), in which the PPh2 group is on the β-
carbon atom relative to the metal.8 In free alkenyldiphenyl-
phosphines, methyl group substitution on the carbon atom
bearing the PPh2 group causes a 10–20 ppm deshielding in δP,19
possibly as a consequence of a decrease in the P–C1–C2 angle,
and a bulky platinum-containing substituent would probably
have a similar effect. Second, the 31P-{1H} spectrum of 6 in
CD2Cl2 is quite different from that in C6D6. The broad signal at
δP 7.9 is absent and is replaced by a doublet with 195Pt satellites
at δP Ϫ88.3 [J(PP) = 306.5 Hz, J(PtP) = 1136 Hz]. The high
shielding of this PPh2 resonance indicates the presence of a
three-membered methylenephosphametallacycle similar to that
in the nickel compound 2a, which can only arise if the PPh2
group is on the carbon atom bonded to platinum, as in 6. Thus,
in CD2Cl2, complex 6 presumably exists as a salt-like species
[Pt{C(᎐CHMe)PPh -κC,P}(dcpe)]ϩClϪ, [6Ј]Cl, formed by par-
᎐
2
tial or complete dissociation of chloride ion from the coord-
ination sphere and its replacement by the PPh2 group. The
magnitude of 2J(PP) is consistent with the presence of mutually
trans P-donors in a planar platinum() species, though it is
somewhat less than the values of 400–500 Hz usually found
when both ligands are tertiary phosphines.21 A similar comment
applies to the magnitude of 1J(PtP).
Treatment of 5 with one mole equivalent of methyl iodide in
ether at 0 ЊC gives initially a brown precipitate, which redis-
solves at room temperature. The 31P-{1H} NMR spectrum of
the solution shows the presence of one main constituent having
doublets of doublets at δP 20.3, 68.9 and 73.7; the last two, due
to dcpe, have Pt–P couplings of 2472 and 3542 Hz, respectively.
The small values of J(PP) (12.9 and 2.0 Hz) and J(PtP)
(110 Hz) associated with the signal at δP 20.3 suggest that this
phosphorus atom is not coordinated to platinum and its
chemical shift is consistent with the presence of a quaternary
phosphonium ion, [R3PMe]ϩ.22 In agreement, the 1H NMR
spectrum contains a 3H-doublet at δH 2.13 [J(PH) = 22.0 Hz]
due to P–Me but, surprisingly, no resonance due to the expected
methyl group bonded to C2. Instead, there are three 1H-
resonances assignable to an allene fragment –CH᎐C᎐CH : a
Scheme 2
The 13C NMR chemical shifts assigned to the quaternary
carbons of the coordinated triple bond of Ph PC ᎐C C H , δ
1
2
3
᎐
᎐
2
3
C
117.60 and 145.55, are deshielded by about 40 ppm compared
with those of the free alkynylphosphine,7,11,12 as expected for
alkyne coordination to a zerovalent Group 10 metal.13 The
electron-withdrawing character of PPh2 causes C2 to be less
shielded than C1 in the free alkyne and this order of chemical
shifts is maintained on coordination to platinum. The J(PC)
values are, in general, larger than those found in η2-alkyne–
᎐ ᎐
2
triplet of doublets at δH 2.85 with a P–H coupling of 4.5 Hz that
is characteristic of a geminal coupling in such compounds,23,24
a
nickel() complexes.8,14 The IR band due to ν(C᎐C) is observed
doublet of doublets of doublets at δH 6.08, and a doublet of
quintets at δH 6.70, the last two being due to the ᎐CH group.
᎐
᎐
at 1700 cmϪ1, which is lower than that of the nickel analogue, in
᎐
2
accord with the trend noted for other alkyne complexes of
We were unable to obtain a satisfactory 13C NMR spectrum
because of the limited quantity of material available, but the IR
spectrum of the colourless solid isolated from the reaction mix-
ture shows a band at 1647 cmϪ1, which is similar to the value
nickel() and platinum().15–17
Complex 5 is unaffected by MeOH, even at 50 ЊC, but
addition of one mole equivalent of HCl in diethyl ether precip-
itates a colourless 1 : 1 adduct whose 31P-{1H} NMR spectrum
in C6D6 shows a broad signal at δP 7.9 due to PPh2 and two
broad signals, with 195Pt satellites, due to coordinated dcpe: a
singlet at δP 49.0 and a doublet at δP 61.8. The corresponding
Pt–P coupling constants are 4095 and 1821 Hz, which are char-
acteristic of phosphorus trans to Cl and σ-bonded carbon,
respectively.18 The 13C NMR spectrum shows a multiplet at δC
143.89 assigned to the metal-bonded carbon and a doublet of
doublets at δC 22.33 for the methyl group [J(PC) = 20.8, 9.7 Hz];
reported for metal–allene complexes such as [Pt(η2-CH ᎐C᎐
2᎐ ᎐
CH2)(PPh3)2];25,26 the FAB mass spectrum shows a parent ion at
m/z 856 consistent with the formulation [Pt{η2-C(᎐CH )᎐
᎐
᎐
2
CHPPh2Me}(dcpe)]ϩ (8). This structure has been confirmed
by single-crystal X-ray diffraction (see below), the allenyl frag-
ment being coordinated to the metal through carbon atoms C1
and C2.
The observed quaternisation of the free phosphorus atom
in 5 by methyl iodide prompted us to examine briefly other
oxidation reactions. Addition of sulfur to 5 gives the η2-
1
a multiplet at δH 6.72 in the H NMR spectrum is assigned to
a vinylic CH group and a ν(C᎐C) band at 1580 cmϪ1 in the
coordinated alkynylphosphine sulfide complex [Pt{η2-Ph2-
᎐
᎐
IR spectrum also indicates the presence of a vinyl group. The
spectroscopic data, therefore, suggest that the compound is
a planar chloroplatinum() complex bearing a σ-C-bonded
P(S)C᎐CMe}(dcpe)] (9), whose structure has been determined
᎐
by X-ray crystallography (see below). Complex 9 can be pre-
pared independently by reaction of the phosphine sulfide with
J. Chem. Soc., Dalton Trans., 2002, 226–233
227

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[Pt(η2-C2H4)(dcpe)]. The NMR and IR spectroscopic proper-
ties of 9 generally resemble those of 5; the 31P chemical shift
of the phosphorus atom of P(S)Ph2 group, δP 29.1, is almost
identical to that of Z-Ph P(S)CH᎐CHMe.20
᎐
2
Solutions of 5 in benzene or diethyl ether are oxidised in air
over a period of hours to give the corresponding phosphine
2
᎐
oxide complex [Pt{η -Ph P(O)C᎐CMe}(dcpe)] (10), which also
᎐
2
has been characterised by X-ray diffraction (see below). The
᎐
compound can also be prepared by reaction of Ph P(O)C᎐CMe
᎐
2
with [Pt(η2-C2H4)(dcpe)] in diethyl ether. Although its spectro-
scopic data are generally as expected, the 31P NMR chemical
shift of the P(O)Ph2 group (δP 12.3) is surprisingly shielded in
comparison with the values for Z-Ph P(O)CH᎐CHMe and
᎐
2
Ph P(O)CH᎐CH ,20,27 which are in the region of δP 21–22. This
᎐
2
2
may be a consequence of the apparent hydrogen bond between
the P᎐O group of compound 10 and the α-CH bond of one of
᎐
the cyclohexyl groups (see below). This attraction would lead to
an increase in the P–C1–C2 angle, resulting in a shielding of the
phosphorus atom as seen for the free alkenyldiphenylphos-
phines discussed above.19
2
᎐
Molecular structures of [Pt(ꢀ -Ph PC᎐CMe)(dcpe)] (5), [PtCl-
᎐
2
{ꢀ1-C(᎐CHMe)PPh }(dcpe)] (6), [Pt{ꢀ2-C(᎐CH )᎐CHPPh -
Me}(dcpe)]I ([8]I) and [Pt(ꢀ -Ph P(X)C᎐CMe)(dcpe)]
᎐
᎐
᎐
2
2
2
2
᎐
Fig. 2 An ORTEP diagram of one conformer of [PtCl{η1-C(᎐CH-
᎐
2
᎐
[X ؍ S (9), O (10)]
Me)PPh2}(dcpe)] 6 with selected atom labelling and 30% probability
ellipsoids; hydrogen atoms have been omitted for clarity.
The molecular geometries of 5, 6, 8, 9 and 10 are shown,
together with the atom labelling, in Figs. 1 to 5, respectively;
selected values of bond lengths and angles are listed in Table 1.‡
Fig. 3 An ORTEP diagram of [Pt(η2-MePh2PCH᎐C᎐CH2}(dcpe)]ϩ
with selected atom labelling and 30% probability ellipsoids; only
hydrogen atoms on C(1) and C(3) are shown.
8
᎐
᎐
2
᎐
Fig. 1 An ORTEP diagram of [Pt(η -Ph2PC᎐CMe)(dcpe)] 5 with
᎐
selected atom labelling and 30% probability ellipsoids; hydrogen atoms
have been omitted for clarity.
29
᎐
[1.206(2) Å]§ and Ph PC᎐CPPh [1.207(5) Å], or in P-coord-
᎐
2
2
The structures of complexes 5, 9 and 10 display trigonal
planar coordination typical of metal(d10)–alkyne complexes,28
the coordinated carbon atoms being displaced slightly (0.07–
0.20 Å) above the PtP2 plane. The Pt–C distances fall in the
range 2.01–2.05 Å, ca. 0.13 Å greater than the Ni–C bond
inated phosphinoalkynes.12 The bend-back angles of the alkyne
substituents are generally in the usual range (140–145Њ) and are
2
᎐
slightly smaller than those in [Ni(η -Ph PC᎐CMe)(dcpe)] (1a)
᎐
2
(see Table 1). The exceptionally large C(2)–C(1)–P(3) angle of
151.1(2)Њ in complex 10 may be associated with the surprisingly
short distance of 3.288(3) Å between the oxygen atom O(1) of
the phosphine oxide and one of the P-bonded cyclohexyl car-
bon atoms, C(30), which is within the range quoted for electro-
static C–H ؒ ؒ ؒ O hydrogen bonds30 (the H ؒ ؒ ؒ O distance
using a calculated position for the hydrogen atom is ca 2.45 Å,
see Fig. 6).
8
᎐
lengths in the nickel compound 1a. The coordinated C᎐C bond
᎐
lengths are equal within experimental error [1.295(4)–1.300(6)
Å]; these distances are slightly greater than that in 1a [1.280(4)
᎐
Å] and significantly greater than those in free Ph PC᎐CMe
᎐
2
‡ The numbering scheme of the bonded carbon atoms in the structures
of complexes 5, 8, 9 and 10 is identical to that used in the NMR discus-
1
2
1
2
᎐
3
᎐
sion, viz. Ph2P–C ᎐C –Me or Ph2P–C H᎐C ᎐C H2. However, it should
᎐
᎐
be noted that this numbering is reversed from that used in the deposited
CCDC structures or in the reported molecular structures of the
§ This work; this structure is not discussed in this paper but has been
deposited with the Cambridge Crystallographic Data Centre as CCDC
reference number 168392.
8
3
2
1
3
2
1
᎐
nickel() analogues, viz. Ph2P–C ᎐C –C H3 or Ph2P–C H᎐C ᎐C H2.
᎐
᎐
᎐
228
J. Chem. Soc., Dalton Trans., 2002, 226–233

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2
᎐
Fig. 4 An ORTEP diagram of [Pt{η -Ph2P(S)C᎐CMe}(dcpe)] 9 with
᎐
selected atom labelling and 30% probability ellipsoids; hydrogen atoms
have been omitted for clarity.
Fig. 6 Simplified view of the X-ray structure of [Pt{η2-Ph2P(O)-
᎐
᎐
C᎐CMe}(dcpe)] 10 showing the postulated C–H ؒ ؒ ؒ O hydrogen bond;
the phenyl and cyclohexyl rings not involved in the interaction have
been omitted for clarity.
than that to the one bearing the ᎐CH group [Pt–C(2) = 2.004(4)
᎐
2
Å]. A similar effect occurs in the allene complex [Pt(η2-
C H )(PPh ) ] (11), in which the Pt–CH and Pt–C(᎐CH ) dis-
᎐
3
4
3
2
2
2
tances are 2.13(3) and 2.03(3) Å, respectively.31 The coordinated
C᎐C bond length [C(1)–C(2) = 1.477(5) Å], is greater than the
᎐
uncoordinated C᎐C distance [C(2)–C(3) = 1.303(6) Å], these
᎐
values being similar to those found in complex 11. Coordin-
ation causes the usually linear allene to bend away from the
metal centre [C(1)–C(2)–C(3) = 137.9(4)Њ, cf. 142(5)Њ in 11].
Finally, as expected for an allene, the plane of the two protons
on C(3) is almost perpendicular to that containing the atoms on
C(1) [the proton H(3) and P(3)], as illustrated by the dihedral
angle C(3)–C(2)–C(1)–P(3) of 69.5Њ.
Discussion
The Pt(dcpe) fragment resembles its nickel() analogue in
2
᎐
stabilising η -alkyne coordination of Ph PC᎐CMe although in
᎐
2
both cases a P-coordinated species is the kinetic product. It is
not yet known whether the driving force for the rearrangement
is the electron-donating ability or the steric bulk of the M(dcpe)
Fig. 5 An ORTEP diagram of the major conformer of [Pt{η2-Ph2P(O)-
᎐
ellipsoids; hydrogen atoms have been omitted for clarity.
᎐
C᎐CMe}(dcpe)] 10 with selected atom labelling and 30% probability
unit. The only comparable reported reaction of an alkynyl-
᎐
phosphine is that of Ph PC᎐CCF with [M(PPh ) ] (M = Pd,
᎐
2
3
3 4
᎐
Pt), which gives dinuclear products in which both C᎐C and
᎐
In complex 6, platinum() is coordinated in a planar array by
the phosphorus atoms of dcpe, chloride, and a η1-C(PPh )᎐
PPh2 are coordinated3 (see Introduction).
The first step in the protonation of platinum()–alkyne com-
᎐
2
2
᎐
CHMe group in which the PPh2 and methyl groups are mutu-
ally cis. The chlorine atom Cl(1) and the carbon atom C(1) are,
respectively, ca. 0.29 and 0.05 Å out of the plane defined by
Pt(1), P(1) and P(2). The Pt–C(1) distance [2.108(5) Å] is typical
of a Pt–C(sp2) interaction and the C–C distances within the
vinyl group are unexceptional. The vinylphosphine unit is
almost planar, the dihedral angle C(3)–C(2)–C(1)–P(3) being
only Ϫ4.0Њ, and is almost perpendicular to the PtP2 plane as
shown by a dihedral angle P(2)–Pt(1)–C(1)–C(2) of 78.7Њ.
In complex 8, an allenylphosphine unit is coordinated to
trigonal-planar platinum() through carbon atoms C(1) and
C(2), these two atoms lying ca. 0.08 and 0.20 Å from the PtP2
plane. The Pt–C distance to the carbon atom bearing the
[PMePh2]ϩ group [Pt–C(1) = 2.133(4) Å] is significantly greater
plexes [Pt(η -RC᎐CR)(PPh ) ] by HCl is probably oxidative
᎐
3
2
addition to the metal atom,32 and the same is likely to hold for
complex 5 as shown in Scheme 3. The hydride in the resulting
adduct 12 then migrates from platinum to the more electron-
᎐
deficient carbon atom of the coordinated Ph PC᎐CMe, forming
᎐
2
a vinyl group in which the PPh2 and Me groups have a Z-
configuration. Related vinyl–platinum() complexes have been
obtained from the addition of alkynylphosphine oxides and
alkynylphosphonium salts to [PtH(PEt3)2(THF)]ϩ.33,34 As in the
case of 1a,8 there is no evidence for migration of hydride to the
β-carbon atom to give a complex [PtCl{η1-C(Me)᎐CH(PPh )}-
᎐
2
(dcpe)]. Although the regioselectivity is the same for nickel and
platinum, the resulting vinyl-phosphine group is, in the solid
state, κ-P, C-bonded in the case of nickel and η1-C-bonded in
J. Chem. Soc., Dalton Trans., 2002, 226–233
229

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Table 1 Selected bond lengths (Å) and bond angles (Њ) for the molecular structures of 5, 6, 8–10, and for the nickel analogue 1aa
5 (M = Pt)
6 (M = Pt)
8 (M = Pt)
9 (M = Pt)
10 (M = Pt)
1a (M = Ni)a
M(1)–P(1)
M(1)–P(2)
M(1)–C(1)
M(1)–C(2)
C(1)–C(2)
C(2)–C(3)
P(3)–C(1)
P(3)–Xb
2.253(1)
2.265(1)
2.047(5)
2.029(5)
1.296(7)
1.498(8)
1.779(6)
—
2.300(2)
2.216(1)
2.108(5)
—
1.304(8)
1.565(10)
1.804(6)
—
2.2541(8)
2.3057(9)
2.133(4)
2.004(4)
1.477(5)
1.303(6)
1.742(4)
1.793(4)
—
2.256(1)
2.280(1)
2.053(4)
2.016(4)
1.300(6)
1.483(7)
1.747(5)
1.960(2)
—
2.2511(7)
2.2666(7)
2.037(3)
2.032(3)
1.295(4)
1.489(5)
1.760(3)
1.484(2)
—
2.1478(8)
2.1613(9)
1.913(3)
1.869(3)
1.280(4)
1.489(5)
1.763(3)
—
Pt(1)–Cl(1)
—
2.370(2)
—
P(1)–M(1)–P(2)
P(1)–M(1)–C(2)
P(2)–M(1)–C(1)
C(1)–C(2)–C(3)
P(3)–C(1)–C(2)
M(1)–C(1)–C(2)
P(1)–Pt(1)–Cl(1)
C(1)–P(3)–Xb
87.36(5)
117.8(2)
117.7(2)
141.8(6)
145.2(4)
70.7(3)
—
87.5(1)
—
87.11(3)
111.6(1)
119.4(1)
137.9(4)
119.1(3)
64.5(2)
—
87.54(4)
116.4(1)
118.6(1)
140.9(5)
140.8(4)
69.8(3)
—
87.49(3)
123.17(9)
112.13(8)
141.8(3)
151.1(2)
71.2(2)
91.46(3)
110.2(1)
118.8(1)
147.6(3)
154.9(3)
68.4(2)
—
92.7(1)
128.0(6)
116.1(4)
117.3(4)
91.7(1)
—
—
116.0(1)
—
111.4(2)
115.2(2)
—
a Data taken from ref. 8. b X = C(4) for 8, S(1) for 9, and O(1) for 10.
arene)M(CO) (η2-Ph PCH᎐C᎐CH )]ϩ (M = Cr,41 Mo42) and
᎐ ᎐
2
3
2
[(η5-C H )Mn(CO) (η2-Ph PCH᎐C᎐CH )]ϩ 41 are known, com-
᎐ ᎐
5
5
2
3
2
plex 8 appears to be the first structurally characterised example.
Moreover, the alkynylphosphine to allenylphosphine rearrange-
ment in the coordination sphere of a transition metal atom has
not been observed previously, although the base-catalysed
rearrangement of the free ligand is well established.43 There are
several examples of the formation of η2-coordinated allene
complexes from alkyne precursors, e.g. [ReCl(η2-CH ᎐C᎐
2᎐ ᎐
44
᎐
CHPh)(dppe)2] from [ReCl(N2)(dppe)2] and PhC᎐CMe,
᎐
[Rh(η5-C H )(PiPr )(η2-CH ᎐C᎐CHMe)] by isomerisation of
2᎐ ᎐
5
5
3
the corresponding but-2-yne complex on an alumina column,45
[Mn(η5-C5H5)(CO)2(η2-1,2-cyclooctadiene)] from the corre-
sponding cyclooctyne complex,46 and [Re(η5-C5R5)(CO)2(η2-
CH ᎐C᎐CHMe)] (R = H, Me) by an alumina- or acid-catalysed
2᎐ ᎐
process from its but-2-yne precursor.47,48 A detailed study has
shown that the acid-catalysed rearrangement of [Re(η5-C5-
2
᎐
Me )(CO) (η -MeC᎐CMe)] proceeds via a rhenacyclopropene
᎐
5
2
intermediate. On this basis, we suggest an intramolecular trans-
fer of the proton via a platinacyclopropene intermediate 13
(pathway a in Scheme 3). Alternatively, the strongly electron-
withdrawing [PMePh2]ϩ substituent could induce a prototropic
rearrangement via a neutral η2-allenylylide–platinum() com-
plex (14
15
8, pathway b), the proton lost from C3
re-adding at C1.
In conclusion, we have shown that the platinum()–dcpe
fragment can stabilise η2-alkyne coordination of the ligand
Scheme 3
᎐
Ph PC᎐CMe, the product being similar to, but more stable
᎐
2
than, its nickel() analogue. It is also possible to induce an
alkyne to allene rearrangement by quaternisation of the
uncoordinated phosphorus atom. The resulting complexes may
be capable of insertion reactions leading to functionalisation of
the unsaturated centre.
the case of platinum, reflecting the greater tendency of the
divalent 3d-element to achieve five-coordination. The balance is
evidently delicate in solution, since ionisation of ClϪ from 6
allows the vinyl phosphine to become κ-P, C -bonded, and the
rather broad 31P resonances of 6 in benzene at room temp-
erature may be caused by reversible loss of ClϪ. As in the
nickel() complex 2a,8 and in several complexes of molyb-
denum and tungsten,35–38 the resulting three-membered ring
shows a characteristic 31P-NMR shielding that is ca. 70 ppm
greater than those of known phosphaplatinacyclopropane
complexes, PtCR2PPh2-κP, C .39,40 This phenomenon has been
attributed to decrease in the C–P–M angle resulting from the
presence of the sp2 hybridised methylene carbon atom in the
metallacycle.8
Experimental
General
All experiments, unless otherwise specified, were carried out
under nitrogen with use of standard Schlenk techniques. All
solvents were dried and degassed before use. NMR spectra
were recorded on a Varian XL-200E (1H at 200 MHz, 13C at
50.3 MHz, 31P at 81.0 MHz), a Varian Gemini 300BB or Inova-
300 (1H at 300 MHz, 13C at 75.4 MHz, 31P at 121.4 MHz), or a
Varian Inova-500 instrument (1H at 500 MHz, 13C at 125.7
MHz) at 298K unless otherwise specified. The chemical shift (δ)
Methyl iodide quaternises the free phosphorus atom of 5
rather than undergoing oxidative addition to the platinum
centre, the reaction being accompanied by an alkyne to allene
rearrangement that yields an η2-allenyl–platinum() complex.
Although η2-allenylphosphonium complexes of the type [(η6-
1
for H and 13C are given in ppm relative to residual signals of
the solvent, and to external 85% H3PO4 for 31P. The spectra of
230
J. Chem. Soc., Dalton Trans., 2002, 226–233

View Article Online
1
1
all nuclei (except H) were H-decoupled. The coupling con-
stants (J) are given in Hz with an estimated error for the values
measured from 31P and 13C NMR spectra of 0.2 Hz unless
otherwise stated. The numbering scheme used in the description
of the 13C NMR data of the alkynylphosphine complex 5 is
1H, ᎐CH), 6.98–7.28 (m, 6H), 8.51 (t, 4H, J(HH) 7.3, Ph). δ
᎐
C
(125.7 MHz, C6D6) 20.12 (dd, J(PC) 24.7, 11.5, PCH2), 22.33
(dd, J(PC) 20.8, 9.7, Me), 25.28 (dd, J(PC) 34.4, 16.5, PCH2),
26.20–29.30 (m, CH2 of C6H11), 33.78 (d, J(PC) 24.5, CH of
C6H11), 35.01 (d, J(PC) 33.2, CH of C6H11), 127.41 (s, aromatic
CH), 127.87 (d, J(PC) 8.0, aromatic CH), 136.10 (d, J(PC)
20.2, aromatic CH), 137.73 (m, aromatic C), 143.89 (m, C1),
C2H could not be located. δP (80.96 MHz, C6D6) 7.9 (br s),
49.1 (br s, J(PtP) 4096), 61.8 (d, J(PP) 10.5, J(PtP) 1822).
δP (80.96 MHz, CD2Cl2) Ϫ88.3 (br d, J(PtP) 307, J(PtP)
1136), 72.0 (d, J(PP) 307, J(PtP) 2518), 73.2 (br s, J(PtP) 2416).
FAB-MS (tetraglyme, C41H62ClPtP3): m/z 843 [M Ϫ Cl]ϩ.
1
2
3
᎐
Ph PC ᎐C C H and the same numbering order has been used
᎐
2
3
for its derivatives. Infrared spectra were measured on Perkin–
Elmer FT-1800 or Spectrum One instruments. Mass spectra
were obtained on a ZAB-2SEQ spectrometer by fast-atom
bombardment (FAB).
All the new complexes were isolated as sticky, crystalline
solids that tenaciously retained organic solvents. This property,
together with the limited amounts of sample, frustrated
attempts to obtain satisfactory elemental analyses. However,
the compounds have been characterised unambiguously by
spectroscopic measurements and single-crystal X-ray diffrac-
tion analyses.
[Pt{ꢀ2-C(᎐CH )᎐CHPPh Me}(dcpe)]I, [8]I. A solution of 5,
᎐
᎐
2
2
freshly prepared from [Pt(η2-C2H4)(dcpe)] (150 mg, 0.23 mmol)
3
᎐
and Ph PC᎐CMe (53 mg, 0.24 mmol) in diethyl ether (10 cm ),
᎐
2
was cooled to 0 ЊC. A solution of methyl iodide in diethyl ether
(0.23 mmol) was added dropwise, initially forming a brown pre-
cipitate and a green solution. After 30 min at room temper-
ature, the solid had redissolved and the solution had turned
purple. The solvent volume was reduced by evaporation in
vacuo, and the salt [8]I was obtained as colorless, air-stable crys-
tals by diffusion of hexane into the concentrated reaction mix-
Starting materials
᎐
(Prop-1-ynyl)diphenylphosphine, Ph PC᎐CMe, and its chalco-
᎐
2
᎐
genide derivatives, Ph P(X)C᎐CMe (X = O, S), were prepared
᎐
2
by published procedures.49–51 The complex [Pt(η2-C2H4)(dcpe)]
has been made previously by treating [Pt(cod)2] with dcpe in
ethene-saturated hexane.52 We prepared it by reducing a THF
solution of [PtCl2(dcpe)] with 1% sodium amalgam in an atmos-
phere of ethene; a similar procedure employing dihydrogen in
place of ethene gives [PtH(dcpe)]2.53
ture at 0 ЊC. IR (KBr) 2923 (s), 2850 (m), 1647 (w, C᎐C), 1436
᎐
(m), 744 (m) cmϪ1. δH (500 MHz, CD2Cl2) 1.00–2.05 (m, 48H,
CH2 and CH of dcpe), 2.13 (d, 3H, J(PH) 22.0, PMe), 2.85 (td,
1H, J 13.5, 4.5, J(PtH) 78.0, C1H), 6.08 (ddd, 1H, J 19.5, 10.5,
5.5, J(PtH) 73.0, Z–C3H), 6.70 (app. d of qnt, 1H, J 38.0, 4.5,
J(PtH) 133.0, E–C3H), 7.58–7.93 (m, 10H, Ph). δP (80.96 MHz,
CD2Cl2) 20.3 (dd, 3J(PP) 12.9, 2.0, J(PtP) 110.1), 68.9 (dd,
Preparations
2
᎐
᎐
᎐
2J(PP) 32.6, J(PP) 12.7, J(PtP) 2472), 73.7 (dd, J(PP) 32.6,
3J(PP) 2.0, J(PtP) 3542). FAB-MS (NOPE, C42H65IP3Pt):
m/z 856 [8]ϩ.
[Pt(ꢀ -Ph PC᎐CMe)(dcpe)], 5. Ph PC᎐CMe (112 mg, 0.5
3
2
᎐
2
2
mmol) was added at 0 ЊC to a stirred suspension of [Pt(η2-
C2H4)(dcpe)] (320 mg, 0.496 mmol) in diethyl ether (20 cm3).
After 30 min, 31P NMR monitoring of the yellow solution
indicated that the reaction was complete, and the solution was
evaporated to dryness in vacuo. The residue was rinsed with
2
᎐
᎐
᎐
[Pt{ꢀ -Ph P(S)C᎐CMe}(dcpe)], 9. Solid Ph P(S)C᎐CMe
᎐
2
2
2
(10 mg, 0.04 mmol) was added to a suspension of [Pt(C2H4)-
᎐
hexane and, after drying, [Pt(η -Ph PC᎐CMe)(dcpe)] (5)
(359 mg, 85%) was obtained as a white solid. Colorless crystals
suitable for X-ray analysis were obtained from a toluene solu-
tion layered with hexane at 0 ЊC. The compound is stable
indefinitely in the absence of air. IR (THF) 1700 (m, C᎐C),
᎐
2
(dcpe)] (20 mg, 0.04 mmol) in diethyl ether (5 cm3) at room
temperature. Monitoring of the resulting yellow solution by 31
P
NMR spectroscopy showed the reaction to be quantitative.
Crystals suitable for X-ray analysis were obtained by layering a
toluene solution of 9 with MeOH at Ϫ20 ЊC.
᎐
᎐
742 (s), 695 (s) cmϪ1. δH (300 MHz, C6D6) 1.05–2.15 (m, 48H,
CH2 and CH of dcpe), 2.94 (d, 3H, J(PH) 7.7, J(PtH) 39.8,
Me), 7.03–7.25 (m, 6H), 7.94 (br t, 4H, J(HH) 7.1, Ph). δC
(125.7 MHz, C6D6) 19.56 (t, J(PC) 10.3, Me), 24.01 (dd, J(PC)
25.9, 15.4, PCH2), 25.4 (dd, J(PC) 27.0, 16.3, PCH2), 26.25–
30.20 (m, CH2 of C6H11), 34.86 (ddd, J(PC) 21.1, 3.7, 1.8, CH
of C6H11), 35.89 (dd, J(PC) 22.9, 4.1, CH of C6H11), 117.61
(ddd, J(PC) 71.5, 42.4, 7.1, C1), 127.77 (s, aromatic CH), 128.21
(d, J(PC) 21.5, aromatic CH) 134.02 (d, J(PC) 20.2, aromatic
CH), 142.89 (dd, J(PC) 14.4, 5.0, aromatic C), 145.55 (ddd,
J(PC) 69.9, 11.0, 6.9, C2). δP (80.96 MHz, C6D6) Ϫ11.5 (dd,
When a solution of 5 in C6D6 in an NMR tube was treated at
room temperature with an excess of sulfur, complex 9 was
formed instantly and quantitatively, as shown by 31P NMR
spectroscopy. IR (KBr): 3050 (w), 2922 (s), 2847 (s), 1697 (s,
C᎐C), 1445 (s), 1435 (s), 1098 (m), 645 (s) cmϪ1. δH (300 MHz,
᎐
᎐
C6D6) 0.95–2.00 (m, 48H, dcpe), 2.78 (dd, 3H, J(PC) 8.1, 2.7,
J(PtH) 40.8, Me), 6.90–7.15 (m, 6H), 8.21–8.31 (m, 4H, Ph). δC
(50.3 MHz, C6D6) 19.72 (t, J(PC) 9.8, Me), 23.85 (dd, J(PC)
25.7, 14.6, PCH2), 25.66 (dd, J(PC) 28.1, 15.6, PCH2), 26.20–
30.20 (m, CH2 of C6H11), 35.45 (br dd, J(PC) 23.0, 3.4, CH of
C6H11), 35.95 (dd, J(PC) 23.9, 3.9, CH of C6H11), 119.25 (ddd,
J(PC) 75.5, 74.2, 3.0, C1), 128.03 (d, J(PC) 28.5, aromatic CH),
129.95 (d, J(PC) 3.0, aromatic CH), 132.12 (d, J(PC) 10.5,
aromatic CH), 138.44 (dd, J(PC) 83.4, 2.9, aromatic C), 158.23
(ddd, J(PC) 71.1, 7.5, 3.6, J(PtC) 338.4, C2). δP (80.96 MHz,
3J(PP) 44.7, 22.1, J(PtP) 35.3), 67.8 (dd, J(PP) 49.4, J(PP)
22.1, J(PtP) 2968), 69.8 (dd, J(PP) 49.5, J(PP) 44.6, J(PtP)
3281). FAB-MS (tetraglyme, C41H61PtP3) m/z 842 [MH]ϩ.
2
3
2
3
[PtCl{C(᎐CHMe)PPh }(dcpe)], 6. A solution of 5, freshly
᎐
2
3
prepared from [Pt(η2-C2H4)(dcpe)] (250 mg, 0.39 mmol) and
C6D6) 29.1 (dd, J(PP) 50.1, 45.9, J(PtP) 50.9, P(S)Ph2), 67.6
3
(dd, 2J(PP) 41.7, 3J(PP) 45.9, J(PtP) 2951, dcpe), 69.0 (dd,
2J(PP) 41.7, 3J(PP) 50.1, J(PtP) 3376, dcpe). FAB-MS (NOPE,
C41H61P3PtS): m/z 875 [MH]ϩ, 791 [MH Ϫ Cy]ϩ.
᎐
Ph PC᎐CMe (90 mg, 0.4 mmol) in diethyl ether (20 cm ), was
᎐
2
cooled to 0 ЊC, and treated dropwise with a solution of HCl in
diethyl ether (0.39 mmol). A white precipitate formed as the
reaction mixture was allowed to warm to room temperature.
The solvent was removed and the residue was washed with
hexane. The 31P NMR spectrum of the solid indicated complete
disappearance of 5. Complex 6 was obtained in quantitative
yield and colourless, air-stable crystals suitable for X-ray crys-
tallography were obtained from diffusion of hexane into a sol-
ution in CH2Cl2 at 0 ЊC. IR (KBr) 3048(w), 2920(s), 2848(s),
2
᎐
[Pt{ꢀ -Ph P(O)C᎐CMe}(dcpe)], 10. Solutions of 5 in diethyl
᎐
2
ether or C6D6 were stirred in air at room temperature for 2–4 h.
Monitoring of the reactions by 31P NMR spectroscopy showed
that 10 was formed quantitatively. Single crystals suitable for
X-ray analysis were obtained by slow evaporation of an ether
solution.
1580(w, C᎐C), 1445(m), 746(m), 694(m) cmϪ1. δH (300 MHz,
C6D6) 1.05–2.90 (m, 51H, CH2, CH of dcpe and Me), 6.72 (m,
When a solution of Ph P(O)C᎐CMe (14 mg, 0.05 mmol) in
᎐
᎐
᎐
2
ether (5 cm3) was added to a suspension of [Pt(C2H4)(dcpe)]
J. Chem. Soc., Dalton Trans., 2002, 226–233
231

View Article Online
᎐
Table 2 Crystal and structure refinement data for compounds Ph2PC᎐CMe, 5, 6, 8, 9 and 10
᎐
᎐
Compound
Ph2PC᎐CMe
5
6
8
9
10
᎐
Chemical formula
M
Crystal system
Space group
a/Å
b/Å
c/Å
C15H13P
224.25
Monoclinic
P21/n (no. 14)
8.0665(1)
7.8531(1)
19.9037(4)
C41H61P3Pt
841.94
Monoclinic
P21/n (no. 14)
10.1711(2)
21.4981(4)
18.1159(4)
C41H62ClP3Pt
878.41
Monoclinic
P21/c (no. 14)
15.7234(1)
13.0059(1)
19.9130(2)
C42H64P3PtϩIϪؒCH2Cl2 C41H61P3PtS
C41H61OP3Pt
857.94
Triclinic
1068.82
874.00
Monoclinic
P21/c (no. 14)
12.0184(1)
20.6516(2)
19.0894(2)
Monoclinic
P21/n (no. 14)
10.0314(1)
22.3462(2)
17.5937(2)
P1 (no. 2)
9.5663(1)
10.39139(1)
20.3829(2)
97.0342(5)
100.9522(5)
95.5804(4)
1959.15(3)
1.454
α/Њ
β/Њ
96.5081(6)
100.6444(9)
96.7321(3)
103.5680(3)
91.7507(4)
γ/Њ
U/Å3
1252.72(3)
1.189
3893.0(1)
1.436
4044.07(5)
1.443
4605.75(7)
1.541
3942.03(6)
1.473
Dx/g cmϪ3
Z
4
4
4
4
4
2
µ (Mo Kα)/mmϪ1
Total reflections
Unique reflections (Rint
Observed reflections
Absorp. corr.
(trans. factors)
No. of parameters
R(observed data)
Rw (observed data)
0.188
28529
2859 (0.054)
2230 [I > 3σ(I )]
integration
(0.948 to 0.983)
197
3.740
39277
6888 (0.054)
6043 [I > 2σ(I )]
integration
(0.569 to 0.777)
406
3.667
97423
11854 (0.041)
9407 [I > 3σ(I )]
integration
(0.568 to 0.687)
192
3.953
96374
10687 (0.048)
9658 [I > 3σ(I )]
integration
(0.616 to 0.756)
470
3.747
72750
9024 (0.073)
7877 [I > 2σ(I )]
integration
(0.781 to 0.893)
415
3.719
57797
11489 (0.043)
10491 [I > 2σ(I )]
integration
(0.544 to 0.751)
440
)
0.0387
0.0514
0.0403
0.0487
0.0484
0.0904
0.0365
0.0425
0.0453
0.0460
0.0328
0.0376
(30 mg, 0.05 mmol) in diethyl ether (5 cm3) at room temper-
ature, the solution turned yellow instantly. The mixture was
stirred for 1 h, and the 31P NMR spectrum of the solution
In the crystal structure of 6, the molecular species was dis-
ordered and present in two possible conformations in a 1 : 1
ratio. The program RAELS0059 was used for constrained
refinement and in the final cycle 192 variables were used to
refine the 9407 observed reflections. The structure was modelled
so that the phenyl rings C(4)–C(9) and C(10)–C(15), C(16) and
the two cyclohexyl groups C(18)–C(23) and C(24)–C(29) were
disordered, while the remainder of the molecule was not. All
phenyl rings were constrained to have equal geometry relative
to the atom P(3) and similar constraint was applied to the two
cyclohexyl rings relative to P(1).60 Restraints on some bond
lengths were also imposed. Pt(1), Cl(1), C(16), C(16Ј) and
C(17) were refined as isolated anisotropic atoms, while rigid
body thermal parametrisations were used for the remaining
non-hydrogen atoms.60 Hydrogen atoms were located in geo-
metrically sensible positions after each refinement cycle. The
maximum and minimum peaks in the final difference Fourier
map were 2.02 and Ϫ1.69 e ÅϪ3, respectively.
showed the formation of 10 to be quantitative. IR (KBr): 3052
᎐
(w), 2926 (s), 2849 (s), 1699 (m br, C᎐C), 1446 (m), 1436(m),
᎐
1188 (m), 719(m) cmϪ1. δH (300 MHz, C6D6) 0.95–2.05 (m, 48H,
dcpe), 2.87 (dd, 3H, J(PC) 7.2, 1.8, J(PtH) 36, Me), 7.00–7.15
(m, 6H), 7.98 (ddd, 2H, J 12.9, 6.6, 2.7), 8.12 (dd, 2H, J 10.2,
6.3, Ph). δP (75.4 MHz, C6D6) 20.00 (t, J(PC) 10.4, Me), 23.80
(dd, J(PC) 25.0, 14.8, PCH2), 25.55 (dd, J(PC) 27.4, 16.6,
PCH2), 26.00–30.10 (m, CH2 of C6H11), 35.22 (dd, J(PC) 21.4,
4.4, CH of C6H11), 35.88 (dd, J(PC) 22.5, 5.5, CH of C6H11),
118.32 (app. dd, J(PC) 111.2, 63.7, C1), 128.00 (d, J(PC) 11.8,
aromatic CH), 130.03 (d, J(PC) 2.5, aromatic CH), 131.80 (d,
J(PC) 9.9, aromatic CH), 139.03 (dd, J(PC) 103.6, 3.0, aromatic
C), 158.41 (app. d, J(PC) 64.6, C2). δP (80.96 MHz, C6D6) 12.3
3
2
(dd, J(PP) 38.5, 35.4, J(PtP) 67.8, P(O)Ph2), 68.5 (dd, J(PP)
44.4, 3J(PP) 38.5, J(PtP) 2981, dcpe), 69.0 (dd, 2J(PP)
44.4, 3J(PP) 35.4, J(PtP) 3343, dcpe). FAB-MS (NOPE,
C41H61OP3Pt): m/z 858 [MH]ϩ.
In the crystal structure of [8]IؒCH2Cl2, the cationic molecular
species and the iodide were clearly defined, but the solvent
molecule was partially disordered. The non-hydrogen atoms of
8 were refined anisotropically by full-matrix least-squares. The
hydrogen atoms H(1), H(2) and H(3) were located in a differ-
ence electron density map and refined positionally, but the
other hydrogen atoms were included at calculated positions
(C–H 0.95Å) and not refined. The maximum and minimum
peaks in the final difference Fourier map were 1.60 and Ϫ1.32 e
X-Ray crystallography
Crystal data, details of data collection, data processing, struc-
ture analysis and structure refinement are in Table 2. All crys-
tals were mounted in silicone oil on a glass fibre and the data
collected at Ϫ73 ЊC on a Nonius KappaCCD diffractometer
(Mo Kα radiation, λ = 0.7107 Å) with use of the crystallo-
graphic software package maXus.54 The intensities of the reflec-
tions were processed by use of the computer programs Denzo
Å
Ϫ3, respectively.
In the structure of 9, the non-hydrogen atoms were refined
anisotropically by full-matrix least-squares. Hydrogen atoms
were included at calculated positions (C–H 0.95Å) and period-
ically recalculated, but not refined. The hydrogen atoms of the
methyl group were orientated to best-fit peaks in the difference
electron density map. The maximum and minimum peaks in the
and Scalepak.55 The structures of Ph PC᎐CMe and 5 were
᎐
᎐
2
solved by direct methods (SIR92),56 while the molecular struc-
tures of 6, 8–10 were solved by the Patterson method
(PATTY).57 The structures were refined by use of the software
package TEXSAN58 unless stated otherwise.
final difference Fourier map were 1.16 and Ϫ1.41 e ÅϪ3
,
᎐
The non-hydrogen atoms of Ph PC᎐CMe were refined
respectively.
᎐
2
anisotropically, while the hydrogen atoms were observed in a
difference electron density map and refined with isotropic dis-
placement factors. The maximum and minimum peaks in the
final difference Fourier map were 0.21 and Ϫ0.24 e ÅϪ3, respect-
ively. The non-hydrogen atoms of 5 were refined anisotropically
by full-matrix least-squares. Hydrogen atoms were included at
calculated positions (C–H 0.95Å) and periodically recalculated,
but not refined. The maximum and minimum peaks in the final
difference Fourier map were 0.85 and Ϫ1.26 e ÅϪ3, respectively.
In the crystal structure of 10, one cyclohexyl ring of the dcpe
ligand was disordered and appeared to be distributed over
two sites in a 0.7 : 0.3 ratio. Refinement was originally carried
out isotropically with restraints imposed upon the C–C bond
distances for this ring, but the major conformation was sub-
sequently refined with anisotropic displacement parameters.
Hydrogen atoms were included at calculated positions (C–H
0.95Å) and periodically recalculated; those of the disordered
ring were calculated for the major orientation only with an
232
J. Chem. Soc., Dalton Trans., 2002, 226–233

View Article Online
27 T. A. Albright, W. J. Freeman and E. E. Schweizer, J. Org. Chem.,
occupancy of 0.7. The hydrogen atoms of the methyl group
were orientated to best-fit the difference electron density
map. The maximum and minimum peaks in the final difference
Fourier map were 0.84 and Ϫ1.30 e ÅϪ3, respectively.
The neutral atom scattering factors, ∆f Ј and ∆f Љ values and
mass attenuation coefficients were taken from ref. 61 for all
structures.
CCDC reference numbers 168392–168397.
See http://www.rsc.org/suppdata/dt/b1/b107015k/ for crystal-
lographic data in CIF or other electronic format.
1975, 40, 3437.
28 S. D. Ittel and J. A. Ibers, Adv. Organomet. Chem., 1976, 14, 33.
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Acknowledgements
34 A. C. Dema, X. Li, C. M. Lukehart and M. D. Owen,
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L. K. gratefully acknowledges the receipt of a Summer
Research Scholarship from the Research School of Chemistry,
ANU, and E. W. thanks to the Australian Research Council for
the award of a QEII Research Fellowship. The authors are
grateful to Dr Christopher J. Cobley for the preparation of
(prop-1-ynyl)diphenylphosphine.
38 J. Ipaktschi, T. Klotzbach and A. Dülmer, Organometallics, 2000,
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