Addition of diphenylphosphine to molybdenum alkynyl complexes

Article abstract of DOI:10.1016/S0022-328X(01)01042-7

The reaction of [CpMo(CO)₃(CCR)] (Cp=η-C₅H₅) with PPh₂H in the presence of Me₃NO gives the expected substituted complex [CpMo(CO)₂(PPh₂H)(CCPh)] as the major product when R=Ph. The phosphine ligand in this compound can be subjected to a deprotonation-alkylation sequence to afford [CpMo(CO)₂(PPh₂Me)(CCPh)]. In contrast, when R=CO₂Me, treatment of [CpMo(CO)₃(CCR)] with PPh₂H and Me₃NO leads directly to [CpMo(CO)₂(PPh₂C=CHCO₂Me)] by addition of the P-H bond across the alkynyl triple bond; this compound has been structurally characterised and contains a three-membered (MoPC) ring with an exocyclic =CHCO₂Me group.

Full text of DOI:10.1016/S0022-328X(01)01042-7

Journal of Organometallic Chemistry 633 (2001) 125–130
www.elsevier.com/locate/jorganchem
Addition of diphenylphosphine to molybdenum alkynyl complexes
Harry Adams, Matthew T. Atkinson, Michael J. Morris *
Department of Chemistry, Uni6ersity of Sheffield, Sheffield S3 7HF, UK
Received 18 April 2001; accepted 11 May 2001
Abstract
The reaction of [CpMo(CO)3(CꢀCR)] (Cp=h-C5H5) with PPh2H in the presence of Me3NO gives the expected substituted
complex [CpMo(CO)2(PPh2H)(CꢀCPh)] as the major product when R=Ph. The phosphine ligand in this compound can be
subjected to a deprotonation–alkylation sequence to afford [CpMo(CO)2(PPh2Me)(CꢀCPh)]. In contrast, when R=CO2Me,
treatment of [CpMo(CO)3(CꢀCR)] with PPh2H and Me3NO leads directly to [CpMo(CO)2(PPh2CꢁCHCO2Me)] by addition of the
PꢂH bond across the alkynyl triple bond; this compound has been structurally characterised and contains a three-membered
(MoPC) ring with an exocyclic ꢁCHCO2Me group. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Molybdenum; Alkyne; Phosphide; Crystal structures
1. Introduction
bonds. For example, we have shown that migration of
acyl ligands from molybdenum to phosphorus can be
induced by deprotonation of [CpMo(CO)2(PPh2H)-
(COMe)], a process which we proposed to occur via an
intermediate containing a three-membered MoPC ring
formed by nucleophilic attack of the phosphido group
on the acyl carbonyl [2]. We have also demonstrated
that both anionic and neutral phosphido ligands are
sufficiently nucleophilic to attack electron-deficient
alkynes to form vinylphosphine ligands or in some
cases metallacycles [3]. A logical further step was there-
fore to investigate the attack of phosphido groups on
coordinated alkyne or acetylide ligands. In this paper
we show that by varying the electronic character of the
acetylide ligand, addition of a PꢂH functionality to its
triple bond can be readily induced.
Phosphine ligands are ubiquitous in homogeneous
transition metal catalyst systems. The ability to confer a
variety of properties on the resulting complexes by
changing the electronic, steric and stereochemical prop-
erties of the ligand through its substituents allows al-
most unlimited variation on the theme: recent areas of
development include water-soluble phosphines, poly-
mer-bound phosphines, and chiral bidentate phosphines
for asymmetric synthesis. Under the relatively harsh
conditions of many catalytic reactions, however, slow
deactivation of catalysts occurs, often involving PꢂC
bond cleavage in the phosphine ligand to form phos-
phido groups which then either lead to formation of
inactive polynuclear compounds or undergo undesir-
able side-reactions with coordinated organic species.
Examples of this are particularly prevalent in hydro-
formylation catalysis [1].
2. Results and discussion
For some years we have been investigating the inter-
action of phosphido ligands with coordinated organic
fragments at molybdenum and iron centres, utilising the
nucleophilic properties of the ligand to form new PꢂC
The acetylide complex [CpMo(CO)3(CꢀCPh)] (1a) is
readily prepared by the reaction of [CpMo(CO)3Cl]
with phenylacetylene in diethylamine solvent in the
presence of CuI catalyst [4]. No change was observed
when a solution of 1a in MeCN was stirred overnight at
room temperature with one equivalent of PPh2H, but
on addition of Me3NO, a rapid reaction ensued to
afford two products which were separated by column
* Corresponding author. Tel.: +44-114-2229363; fax: +44-114-
2738673.
E-mail address: m.morris@sheffield.ac.uk (M.J. Morris).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01042-7

126
H. Adams et al. / Journal of Organometallic Chemistry 633 (2001) 125–130
chromatography (Scheme 1). The major complex
formed (42% yield) was the expected substitution
product [CpMo(CO)2(PPh2H)(CꢀCPh)] (2a). This com-
pound displayed two absorptions (1960 and 1878
cm−1) in its IR spectrum in an intensity ratio charac-
teristic of a cis-dicarbonyl structure, and also a weaker
base DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) under
similar conditions to those used previously for [Cp-
Mo(CO)2(PPh2H)(COMe)], followed by treatment with
MeI afforded
a
77% yield of [CpMo(CO)2-
(PPh2Me)(CꢀCPh)] (4) arising from simple deprotona-
tion and alkylation at the phosphorus atom [5].
However, a small amount of 3a was also produced,
demonstrating that there is some degree of attack on
the acetylide ligand; presumably the resulting anion is
reprotonated by DBUH+ in the solution, abstracts a
proton from further 2a, or is reprotonated during the
work-up procedure. Complex 4 displayed very similar
spectroscopic characteristics to 2a (see Section 3) and
its identity was also confirmed by independent synthesis
from 1a and PPh2Me in 68% yield.
1
absorption due to w(CꢀC) at 2085 cm−1. The H-NMR
spectrum showed the presence of only one isomer; the
expected doublet due to the PꢂH proton was discernible
even though one of its components was partially
masked by the phenyl protons. The 31P{1H}-NMR
spectrum comprised a single peak in a position typical
of terminal phosphine ligands.
The minor product of this reaction also displayed a
cis-dicarbonyl pattern in its IR spectrum, but the CꢀC
1
absorption was absent. Moreover the H-NMR spec-
In previous work we have observed that phosphido
ligands are sufficiently nucleophilic to attack activated
alkynes such as dmad (MeO2CCꢀCCO2Me) or methyl
propiolate, but react poorly with simple alkynes such as
acetylene itself [3]. We therefore decided to introduce
an electron-withdrawing substituent into the acetylide
ligand in the hope of inducing PꢂC bond formation
with the phosphido group. Unfortunately the prepara-
tion of the acetylide complex [CpMo(CO)3-
(CꢀCCO2Me)] (1b) cannot be achieved in the same way
as that of 1a because the activated alkyne methyl
propiolate itself reacts rapidly with the diethylamine
solvent. Therefore we used a route involving deproto-
nation of the alkyne with BuLi in THF followed by
reaction with [CpMo(CO)3Cl], which gave the desired
product as a yellow solid, typically in 30% yield. In its
IR spectrum the compound showed two strong car-
bonyl absorptions (2048 and 1972 cm−1), a peak at
2108 cm−1 due to the acetylide functionality, and a
trum contained an unexpected doublet at l 8.67 (J=
12.5 Hz) and the 31P chemical shift of −87.7 ppm was
also distinctly unusual; such a figure is characteristic of
the presence of a three-membered ring. By comparison
with the compound crystallographically characterised
below, we can identify this complex as [Cp-
Mo(CO)2(PPh2CꢁCHPh)] (3a) in which addition of the
PꢂH bond across the CꢀC bond of the acetylide ligand
has occurred to produce an a-phosphinovinyl moiety.
The compound consists of a single isomer (the Z-iso-
mer, in which the PPh2 and H are situated cis to each
other) as shown by the magnitude of the PꢂH coupling
1
in the H-NMR spectrum (12.5 Hz) as discussed below.
The reaction of 1a with PPh2H was also investigated
under thermal conditions; although the yields of 2a and
3a were virtually unchanged, other products were also
formed which made separation more difficult. Use of
freshly sublimed Me3NO as opposed to the commercial
dihydrate also did not improve the yield of 2a.
weaker peak due to the ester carbonyl at 1687 cm−1
;
We then investigated the behaviour of 2a on deproto-
nation to ascertain whether an anionic phosphido
group could attack the phenylacetylide ligand. Depro-
tonation of the phosphine ligand of 2a with the organic
the NMR spectra were as expected. After we had
prepared this complex, an alternative synthesis was
published which involves reaction of [CpMo(CO)3]−
with ClCꢀCCO2Me, giving 1b in 64% yield [6]; although
the yield of our procedure is lower, it does avoid the
preparation of the potentially explosive chloroalkyne.
The reaction of 1b with PPh2H in MeCN again did
not proceed until the addition of Me3NO to the mix-
ture. In this case only one identifiable product, [Cp-
Mo(CO)2(PPh2CꢁCHCO2Me)]
(3b)
was
formed
(Scheme 2), though a small amount of a minor product
was observed which may be the analogue of 2a, i.e.
[CpMo(CO)2(PPh2H)(CꢀCCO2Me)]. The fact that no
reaction occurs without Me3NO shows that substitution
of the carbonyl ligand occurs before addition of the
PꢂH bond across the alkynyl functionality. Complex 3b
again shows two CO bands in its IR spectrum, but no
acetylide peak. Inspection of the 1H-NMR spectrum
revealed the presence of two isomers: the major one (Z)
has the phosphorus atom situated cis to the H on the
exocyclic double bond, and gives rise to a doublet at l
Scheme 1. Synthesis of complexes derived from [CpMo(CO)3(CCPh)]
(1a). Reagents and conditions: (i) PPh2H, Me3NO, MeCN; (ii)
PPh2Me, Me3NO, MeCN; (iii) DBU, then MeI.

H. Adams et al. / Journal of Organometallic Chemistry 633 (2001) 125–130
127
which there could be free rotation about the
CꢂCH2CO2Me single bond, followed by loss of the
proton.
A closely related complex, [CpW(CO)2(PPh2CꢁCH2)],
has been prepared by Kreißl and co-workers by depro-
tonation of [CpW(CO)2(PPh2CMe)]+ [7]. For compari-
1
son the H-NMR spectrum of this complex in CD2Cl2
contained peaks for the methylene group at l 7.12 with
J(PH)=13.7 Hz and l 6.05 with J(PH)=37.6 due to
the protons cis and trans to phosphorus, respectively; a
small J(HH) of 1.2 Hz was also observed. The 31P-
NMR shift was −124.1 ppm. Very recently, Ipaktschi
and co-workers have reported the addition of PPh2Cl to
the vinylidene complexes [CpW(CO)(NO)(ꢁCꢁCHR)]
(R=H, Me, Ph) to afford [CpW(NO)(Cl)-
(PPh2CꢁCHR)], which also display very similar spectro-
scopic properties; in the cases where R is not H, two
interconverting isomers are again observed, with the
E:Z ratios being 3:1 and 1:1.2 for R=Me and Ph,
respectively [8]. The similarity of these data to those
obtained for the two isomers of 3b reinforces our view
that the isomers differ in the stereochemistry about the
exocyclic double bond.
Scheme 2. Synthesis of complexes derived from [CpMo(CO)3-
(CCCO2Me)] (1b). Reagents and conditions: (i) PPh2H, Me3NO,
MeCN.
Crystallisation of 3b by diffusion of diethyl ether into
a dichloromethane solution provided large rectangular
blocks suitable for structure determination. The result
is shown in Fig. 1, with selected bond lengths and
angles collected in Table 1. Only the Z isomer is present
in the crystal selected for study. The molecule consists
of a standard four-legged piano stool arrangement in
which the basal positions are occupied by two cis
carbonyl groups and the a-phosphinovinyl ligand. The
latter forms a three-membered ring involving Mo(1),
P(1) and C(20) in which the P(1)ꢂC(20) bond is rather
Fig. 1. Molecular structure of complex 3b in the crystal showing the
atomic numbering scheme.
,
short, 1.748(3) A, a phenomenon previously noted in
7.70 with J(PH)=11.3 Hz due to the CH group,
whereas the minor one (E) has the PPh2 and H trans to
each other as revealed by the larger coupling constant,
J(PH)=32.3 Hz, for a doublet at l 6.68. The 31P{1H}-
NMR spectrum contains peaks at −71.5 and −90.0
ppm for the E and Z isomers, respectively. The mass
spectrum and 13C{1H}-NMR spectrum of 3b confirmed
the above findings, though the CHCO2Me carbon sig-
nals of both isomers were obscured by the phenyl
region.
other phosphinovinyl complexes and suggestive of the
possible contribution of a phospha-allene canonical
form (Ph2PꢁCꢁCHCO2Me) [9]. In fact the bond lengths
Table 1
,
Selected bond lengths (A) and angles (°) for complex 3b
Bond lengths
Mo(1)ꢂC(2)
Mo(1)ꢂC(20)
P(1)ꢂC(20)
O(2)ꢂC(2)
1.954(3)
2.143(3)
1.748(3)
1.146(4)
1.467(4)
Mo(1)ꢂC(1)
Mo(1)ꢂP(1)
O(1)ꢂC(1)
1.977(3)
2.4131(8)
1.153(3)
1.346(4)
The two isomers of 3b interconvert slowly in solu-
C(20)ꢂC(21)
1
tion. A H-NMR spectrum of the sample from which
C(21)ꢂC(22)
the crystal used for the structure determination was
selected (see below) showed that the isomer ratio was
4.2:1 in favour of the Z-isomer. After standing in
solution for 24 h, the ratio had changed to 0.7:1. The
interconversion may take place through opening of the
three-membered ring, but another possibility is that
protonation by traces of acid could occur at the exo-
cyclic methylene group to give a cationic species in
Bond angles
C(2)ꢂMo(1)ꢂC(1)
C(1)ꢂMo(1)ꢂC(20) 117.74(10) C(2)ꢂMo(1)ꢂP(1)
C(1)ꢂMo(1)ꢂP(1)
C(20)ꢂP(1)ꢂMo(1)
O(2)ꢂC(2)ꢂMo(1)
C(21)ꢂC(20)ꢂMo(1) 147.5(2)
C(20)ꢂC(21)ꢂC(22) 122.4(2)
82.80(12) C(2)ꢂMo(1)ꢂC(20) 79.04(11)
103.94(8)
44.62(7)
84.83(8) C(20)ꢂMo(1)ꢂP(1)
59.47(9) O(1)ꢂC(1)ꢂMo(1) 178.3(2)
176.8(3) C(21)ꢂC(20)ꢂP(1) 136.4(2)
P(1)ꢂC(20)ꢂMo(1) 75.91(10)

128
H. Adams et al. / Journal of Organometallic Chemistry 633 (2001) 125–130
and angles within this ring are almost identical to those
found in the dinuclear complex [Mo2Cl2(m-PPh2)(m-
Ph2PCꢁCHMe)Cp2] which contains a similar arrange-
and used without further purification. Anhydrous
Me3NO was prepared by sublimation or by azeotropic
distillation from toluene. Light petroleum refers to the
fraction boiling in the range 60–80 °C.
,
ment. The C(20)ꢂC(21) distance of 1.346 A is within the
range expected for a double bond, but there is also
some shortening of the C(21)ꢂC(22) bond to 1.467(4)
3.1. Reaction of [CpMo(CO)3(CꢀCPh)] with PPh2H
,
A. A canonical form in which a negative charge was
localised on the carbonyl oxygen and a positive charge
on the MoPC ring could account for this. Additional
weight is given to this idea by the fact that the CO2Me
group is coplanar with the MoPC ring in the solid state.
In conclusion, we have shown that addition of the
PꢂH bond of a coordinated phosphine ligand to an
alkynyl ligand can be induced simply by changing the
substituent on the latter from Ph to CO2Me. The
mechanism of formation of 3 from 1 presumably in-
volves CO substitution as its first step (as shown by the
requirement for Me3NO and the isolation of 2) fol-
lowed by transfer of the hydrogen from the phosphine
to the b-carbon of the acetylide and attack of the
nucleophilic phosphido group on the a-carbon. It is
possible that the presence of NMe3 in the reaction
mixture (arising from the decarbonylation reaction) has
a bearing on the outcome; for example it is conceivable
that the presence of the electron-withdrawing CO2Me
substituent in 1b renders the phosphine ligand in the
putative substituted complex 2b more prone to deproto-
nation by this weak base, resulting in direct and com-
plete conversion to 3b by attack of the phosphido
group on the more activated acetylide ligand.
The complex [CpMo(CO)3(CꢀCPh)] (0.203 g, 0.587
mmol) was dissolved in MeCN (25 ml) and treated with
Me3NO·2H2O (65.2 mg, 0.587 mmol) followed by
diphenylphosphine (0.17 ml, 0.853 mmol). After stirring
for 30 min, the solvent was removed in vacuo and the
residue adsorbed onto a small amount of silica, which
was then loaded onto a silica column. Elution with
CH2Cl2–light petroleum (1:3) afforded a small yellow
band due to [CpMo(CO)2(PPh2CꢁCHPh)] (3a) (44.1
mg, 15%). Continued elution with a 1:1 mixture of the
same solvents gave [CpMo(CO)2(PPh2H)(CꢀCPh)] (2a)
as a bright yellow powder (124.0 mg, 42%).
2a: M.p. 133–136 °C. IR w(CꢀC) 2085w; w(CO)
1
1960s, 1878s cm−1. H-NMR: l 7.65–6.79 (m, 15H,
Ph), 6.87 (d, J(PH)=382 Hz, 1H, PH), 5.30 (s, 5H,
Cp). 13C{1H}-NMR: l 250.9 (d, J=31 Hz, CO), 236.9
(d, J=2 Hz, CO), 136.4 (d, J=37 Hz, Cipso), 134.0–
125.1 (m, Ph), 105.8, 105.3 (both s, CꢀC), 92.5 (s, Cp).
31P{1H}-NMR: l 37.5 (s). Anal. Found: C, 63.89; H,
4.27. Calc. for C27H21MoO2P: C, 64.28; H, 4.17%. Mass
spectrum: m/z 507 [M+H+], 450 [M−2CO]+.
3a: M.p. 185–188 °C. IR w(CO) 1951s, 1876s cm−1
.
1H-NMR: l 8.67 (d, J=12.5 Hz, 1H, CH), 7.80–7.13
(m, 15H, Ph), 5.26 (s, 5H, Cp). 31P{1H}-NMR: l
−87.7 (s, PPh2). Anal. Found: C, 64.00; H, 4.14. Calc.
for C27H21MoO2P: C, 64.28; H, 4.17%. Mass spectrum
m/z 506 [M+], 450 [M−2CO]+.
3. Experimental
General experimental techniques were as detailed in
recent papers from this laboratory [10]. Infra-red spec-
tra were recorded in CH2Cl2 solution on a Perkin–
Elmer 1600 FTIR machine using 0.5 mm NaCl cells.
1H-, 13C{1H}- and 31P{1H}-NMR spectra were ob-
tained in CDCl3 solution on a Bruker AC250 machine
with automated sample-changer or on an AM250 spec-
trometer. Chemical shifts are given on the l scale
relative to SiMe4=0.0 ppm. The 13C{1H}-NMR spec-
tra were recorded using an attached proton test tech-
nique (JMOD pulse sequence). The 31P{1H}-NMR
spectra were referenced to 85% H3PO4=0.0 ppm with
downfield shifts reported as positive. Mass spectra were
recorded on a Kratos MS 80 instrument operating in
fast atom bombardment mode with 3-nitrobenzyl alco-
hol as matrix. Elemental analyses were carried out by
the Microanalytical Service of the Department of
Chemistry.
3.2. Preparation of [CpMo(CO)2(PPh2Me)(CꢀCPh)] (4)
from 2a
Complex 2a (101.9 mg, 0.20 mmol) was dissolved in
THF (15 ml) and treated with 1.1 equivalent of DBU
(0.033 ml, 2.23 mmol) After stirring at room tempera-
ture (r.t.) for 15 min, methyl iodide (0.0126 ml, 0.20
mmol) was added and stirring continued for a further 3
h. After removal of the solvent in vacuo the residue was
chromatographed to afford three yellow bands which
were eluted with a 1:1 mixture of CH2Cl2 and light
petroleum. The first consisted of a small amount of
complex 3a and the second of unreacted starting mate-
rial, while the third contained [CpMo(CO)2(PPh2Me)-
(CꢀCPh)] (4). Yield=81.0 mg, 77%.
3.3. Preparation of [CpMo(CO)2(PPh2Me)(CꢀCPh)] (4)
from 1a
Literature methods were used to prepare [Cp-
Mo(CO)3Cl] [11] and [CpMo(CO)3(CꢀCPh)] [4]. The
alkynes, phosphine ligands, trimethylamine-N-oxide,
methyl iodide and DBU were all obtained from Aldrich
The complex [CpMo(CO)3(CꢀCPh)] (441.6 mg, 1.28
mmol) was dissolved in MeCN (50 ml) and treated with

H. Adams et al. / Journal of Organometallic Chemistry 633 (2001) 125–130
129
1
PPh2Me (0.26 ml, 1.40 mmol) and anhydrous trimethy-
lamine-N-oxide (126.7 mg, 1.69 mmol). The solution
changed colour from orange to deep red and gas evolu-
tion was observed. The reaction was stirred for 1.5 h.
After removal of the solvent under vacuum and absorp-
tion of the residue onto silica, the product was chro-
matographed to afford 4 as a bright yellow powder
(447.9 mg, 68.4%) which was eluted with a 1:1 mixture
of CH2Cl2 and light petroleum.
3b: IR: w(CO) 1967s, 1895s cm−1. H-NMR: Z-iso-
mer: 7.70 (d, J(PH)=11.3 Hz, 1H, CH), 5.36 (s, 5H,
Cp), 3.77 (s, 3H, Me); E-isomer: 6.68 (d, J(PH)=32.3,
1H, CH), 5.28 (s, 5H, Cp), 3.55 (s, 3H, Me). 13C{1H}-
NMR: Z-isomer: l 232.3 (d, J(PC)=17 Hz, CO),
178.9 (d, J(PC)=32 Hz, PCC), 169.3 (d, J(PC)=21
Hz, CO2Me), 133.2–127.4 (m, Ph), 90.0 (s, Cp), 50.9 (s,
Me); E-isomer: l 232.3 (d, J(PC)=17 Hz, CO), 177.0
(d, J(PC)=23 Hz, PCC), 161.1 (d, J(PC)=6 Hz,
CO2Me), 133.2–127.4 (m, Ph), 91.4 (s, Cp), 50.8 (s,
Me). 31P{1H}-NMR: E-isomer l −71.5, Z-isomer l
−90.0 (s, PPh2). Anal. Found: C, 56.87; H, 3.99; Calc.
for C23H19MoO4P: C, 56.76; H, 3.91%. Mass spectrum
m/z 488, 460, 432 [M−nCO]+ (n=0–2).
4: M.p.176–179 °C. IR w(CꢀC) 2085w, w(CO) 1958s,
1
1875s cm−1. H-NMR l 7.62–6.83 (m, 15H, Ph), 5.29
(s, 5H, Cp), 2.22 (d, J(PH)=8.2 Hz, 3H, Me).
13C{1H}-NMR: l 251.7 (d, J=29 Hz, CO), 238.6 (s,
CO), 139.0 (d, J=42 Hz, Cipso), 136.2 (d, J=47 Hz,
Cipso), 132.8–124.9 (m, Ph), 107.9, 107.5 (both s, CꢀC),
92.5 (s, Cp), 19.5 (d, J=34 Hz, Me). 31P{1H}-NMR: l
40.7. Anal. Found: C, 64.56; H, 4.34. Calc. for
C28H23MoO2P: C, 64.86; H, 4.44%. Mass spectrum m/z
521 [M+H+], 492, 464 [M−nCO]+ (n=1–2).
3.6. Crystal structure determination
Crystal data for [CpMo(CO)2(PPh2CꢁCHCO2Me)]
(3b) are collected in Table 2. Three-dimensional, r.t.
X-ray data were collected in the q range shown on a
Siemens P4 diffractometer by the v-scan method. Of
3.4. Preparation of [CpMo(CO)3(CꢀCCO2Me)] (1b)
The alkyne methyl propiolate (0.68 ml, 7.65 mmol)
was dissolved in THF (20 ml) and cooled to −78 °C.
Butyl lithium (5.3 ml of a 1.6 M solution in hexanes,
8.48 mmol) was added and the solution was allowed to
stir for 10 min. The complex [CpMo(CO)3Cl] (2.1277 g,
7.6 mmol) was added as a solid, and the solution was
allowed to warm to r.t. The solvent was evaporated to
dryness and the residue chromatographed. The
product, [CpMo(CO)3(CꢀCCO2Me)], was recovered as
a yellow band by elution with CH2Cl2. Yield 31%. M.p.
98–102 °C. IR: w(CꢀC) 2108w, w(CO) 2048s, 1972s
Table 2
Summary of crystallographic data for complex 3b
Identification code
Empirical formula
Formula weight
Temperature (K)
Wavelength (A)
Crystal system
Space group
ma062
C
23H19MoO4P
486.29
293(2)
0.71073
Triclinic
,
(
P1
Unit cell dimensions
,
a (A)
8.012(2)
9.728(2)
13.951(2)
79.68(2)
86.21(2)
78.130(10)
1046.4(4)
2
,
b (A)
1
cm−1. H-NMR: l 5.57 (s, 5H, Cp), 3.67 (s, 3H, Me).
,
c (A)
These data correspond with those recently published
[6].
h (°)
i (°)
k (°)
3
,
V (A )
Z
3.5. Reaction of [CpMo(CO)3(CꢀCCO2Me)] with
PPh2H
Dcalc (Mg m−3
)
1.543
0.729
492
Absorption coefficient (mm−1
F(000)
)
The complex [CpMo(CO)3(CꢀCCO2Me)] (0.75 g, 2.3
mmol) was dissolved in MeCN (20 ml) and treated with
1.1 equivalent of Me3NO·2H2O (0.28 g, 2.52 mmol).
After stirring for 10 min, diphenylphosphine (0.45 ml,
2.59 mmol) was added. After removal of the solvent in
vacuo and absorption of the residue onto silica the
product was separated by chromatography. A minor
product, tentatively identified as [CpMo(CO)2(PPh2H)-
(CꢀCCO2Me)] (2b) by comparison with 2a, was eluted
as a small yellow band with a 2:3 mixture of CH2Cl2
and light petroleum [w(CꢀC) 2083w, w(CꢀO) 1969s,
1896s cm−1]. Unfortunately, contamination of this
complex by oily phosphine-containing material pre-
vented the acquisition of further data. Elution with
CH2Cl2 gave a further yellow band of [CpMo(CO)2-
(PPh2CꢁCHCO2Me)] (3b) (581 mg, 52%).
Crystal size (mm)
Theta range for data collection
(°)
0.73×0.43×0.32
2.17–25.00
Index ranges
−15h59, −115k511,
−165l516
4554
3695 [Rint=0.0452]
Psi scans
0.9467 and 0.3977
Full-matrix least-squares on
F2
3695/0/262
1.034
R1=0.0292, wR2=0.0785
R1=0.0331, wR2=0.0818
Reflections collected
Independent reflections
Absorption correction
Max/min transmission
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I\2|(I)]
R indices (all data)
Largest difference peak and hole 0.483 and −0.615
−3
,
(e A
)

130
H. Adams et al. / Journal of Organometallic Chemistry 633 (2001) 125–130
References
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Crystallographic data for the structure determination
of complex 3b have been deposited with the Cambridge
Crystallographic Data Centre, CCDC no. 161950.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (Fax: +44-1223-336033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
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Acknowledgements
We thank Iain Chapman for additional experiments
and the University of Sheffield for support.
.