Synthesis of three-membered metallaphosphaheterocycles and their ring opening with Ph2PH on mixed-metal molybdenum-cobalt centres

Article abstract of DOI:10.1039/b004594m

Treatment of the alkyne-bridged molybdenum-cobalt complexes [(n'-CjHjHOQjMofu-R'CCR^CoCCCOj] (R1 = R2 = CO2Me la; R1 = H, R2 = Bu' Ib) with the phosphinoalkyne Ph2POCPh in refluxing toluene gave regiospecifically the phosphino-substituted butadiene-containing complexes [(r|5-C5H5)(OC)Mo{u-CR2=CR'CPh= C(PPh2)}Co(CO)2] (R1 = R2 = CO2Me 2a; R1 = H, R2 = Bu' 2b) in moderate yield. Single crystal X-ray diffraction studies of 2a and 2b reveal the phosphorus and molybdenum centres to be constrained into three-membered metallaphosphaheterocycles. Reaction of la with PhjPOCBu' has previously been shown to lead to P-C bond cleavage but, in contrast, reaction of Ib with this phosphinoalkyne under the same conditions affords two products, [(ri5-C5Hj)(OC)Mo{u-CBu'=CHCBu'=C(PPhj)}Co(CO)2] 2c, the analogue of 2a and 2b as the minor product, and [(n5-CjH5)(OC)Mo{u-CBu'=CHCBu'=C(PPh2O)}Co(CO)2] 3, as the major product. This major product is derived from 2c by oxidation of the phosphorus centre, with the P=O unit so formed then being incorporated into a four-membered Mo-O=P-C metallacycle. The reactivity of 2a and 2b towards diphenylphosphine has been examined and found to follow two different pathways. On reaction of 2a with Ph2PH in refluxing toluene the three-membered metallaphosphaheterocycle opens to give the vinyl-bridged complex [(ris-CJHJ)(OC)Mo{u-C(CO2Me)C(CPh=CHPPh2)C(OMe)O}(n-PPh2)Co(CO)] 4 while the vinylidene-bridged species Kn5-C5H5)(OC)Mo{u-C=CPhCH(CH2Bu')PPh2}(u-PPh2)2Co(CO)] 5 is isolated in the corresponding reaction of 2b. In addition to 2a and 2b, single crystal X-ray diffraction studies have been performed on 3,4 and 5. Possible reaction pathways for the formation of the new complexes are proposed and discussed. The Royal Society of Chemistry 2000.

Full text of DOI:10.1039/b004594m

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Synthesis of three-membered metallaphosphaheterocycles and their
ring opening with Ph2PH on mixed-metal molybdenum–cobalt
centres†
John E. Davies,a Martin J. Mays,*a Paul R. Raithby,a Koshala Sarveswarana and
Gregory A. Solanb
a Department of Chemistry, Lensfield Road, Cambridge, UK CB2 1EW.
E-mail: mjm14@cam.ac.uk
b Department of Chemistry, University of Leicester, University Road, Leicester, UK LE1 7RH
Received 8th June 2000, Accepted 16th August 2000
First published as an Advance Article on the web 13th September 2000
Treatment of the alkyne-bridged molybdenum–cobalt complexes [(η5-C5H5)(OC)2Mo(µ-R1CCR2)Co(CO)3]
1
2
1
2
t
᎐
(R = R = CO Me 1a; R = H, R = Bu 1b) with the phosphinoalkyne Ph PC᎐CPh in refluxing toluene gave
᎐
2
2
regiospecifically the phosphino-substituted butadiene-containing complexes [(η5-C H )(OC)Mo{µ-CR2᎐CR1CPh᎐
᎐
᎐
5
5
C(PPh2)}Co(CO)2] (R1 = R2 = CO2Me 2a; R1 = H, R2 = But 2b) in moderate yield. Single crystal X-ray diffraction
studies of 2a and 2b reveal the phosphorus and molybdenum centres to be constrained into three-membered
t
᎐
metallaphosphaheterocycles. Reaction of 1a with Ph PC᎐CBu has previously been shown to lead to P–C
᎐
2
bond cleavage but, in contrast, reaction of 1b with this phosphinoalkyne under the same conditions affords
two products, [(η5-C H )(OC)Mo{µ-CBut᎐CHCBut᎐C(PPh )}Co(CO) ] 2c, the analogue of 2a and 2b as the
᎐
᎐
5
5
2
2
minor product, and [(η5-C H )(OC)Mo{µ-CBut᎐CHCBut᎐C(PPh O)}Co(CO) ] 3, as the major product. This
᎐
᎐
5
5
2
2
major product is derived from 2c by oxidation of the phosphorus centre, with the P᎐O unit so formed then being
᎐
incorporated into a four-membered Mo–O᎐P–C metallacycle. The reactivity of 2a and 2b towards diphenyl-
᎐
phosphine has been examined and found to follow two different pathways. On reaction of 2a with Ph2PH in
refluxing toluene the three-membered metallaphosphaheterocycle opens to give the vinyl-bridged complex
[(η5-C H )(OC)Mo{µ-C(CO Me)C(CPh᎐CHPPh )C(OMe)O}(µ-PPh )Co(CO)] 4 while the vinylidene-bridged
᎐
5
5
2
2
2
species [(η5-C H )(OC)Mo{µ-C᎐CPhCH(CH But)PPh }(µ-PPh ) Co(CO)] 5 is isolated in the corresponding
᎐
5
5
2
2
2 2
reaction of 2b. In addition to 2a and 2b, single crystal X-ray diffraction studies have been performed on 3, 4
and 5. Possible reaction pathways for the formation of the new complexes are proposed and discussed.
of direct coupling with the bridging ligand, P–C(alkyne) bond
cleavage occurs to give, after subsequent P–C and C–C bond
forming steps, the complex [(η5-C5H5)(OC)2Mo{µ-ButCCC-
(CO2Me)=C(CO2Me)PPh2}Co(CO)2] (Fig. 1).6 Indeed, phos-
phorus–carbon(alkyne) bond cleavage reactions are a feature
1 Introduction
The reactivity of alkyne-bridged ditransition metal com-
plexes towards alkynes has long been the focus for con-
siderable research activity, due in part to the connection of
such reactions to metal-mediated cyclooligomerisation pro-
cesses.1 In some cases organometallic products are isolated
in which one, two or three molecules of the added alkyne
have coupled with the bridging alkyne to form condensed
ligands.1–5 This occurs, for instance, in the reaction of the
dimethyl acetylenedicarboxylate-bridged molybdenum–cobalt
complex [(η5-C5H5)(OC)2Mo{µ-C2(CO2Me)2}Co(CO)3] 1a
of the reactivity of phosphinoalkynes towards transition
᎐
metal carbonyl complexes, with the resulting PR and C᎐CR
᎐
2
fragments often participating in further coupling reactions.7–9
However, insertion of an intact phosphinoalkyne into a metal–
carbon bond of a bridging alkyne is, to the knowledge of the
authors, unprecedented. Moreover, studies of the reaction
chemistry of alkyne-bridged bimetallic complexes with phos-
phinoalkynes remain uncommon.6,10,11
5
᎐
with HC᎐C(CO Me) affording [(η -C H )(OC)Mo{µ-C(CO -
᎐
2
5
5
2
Me)᎐C(CO Me)C(CO Me)᎐CH}Co(CO) ], in which one
᎐
᎐
2
2
2
By simple variation in the nature of the substituent R on
molecule of the free alkyne has effectively inserted
selectively into a molybdenum–carbon(alkyne) bond in 1a
(Fig. 1).5a
Recently, we have investigated some reactions of complex 1a
with the phosphinoalkyne Ph PC᎐CBu , and found that, instead
1
2
᎐
the Ph PC᎐CR substrate, or the substituents R and R on the
᎐
2
bridging alkyne in [(η5-C5H5)(OC)2Mo(µ-R1CCR2)Co(CO)3] 1,
we have been able to effect insertion reactions to give novel
butadiene-co-ordinated molybdenum–cobalt complexes con-
taining strained three-membered metallaphosphahetero-
cycles, the reactivity of which has been probed with
diphenylphosphine.
t
᎐
᎐
2
† Dedicated to the memory of Dr Ron Snaith.
t
᎐
᎐
Fig. 1 Products from the reactions of complex 1a with HC᎐C(CO2Me) [ref. 5a] and Ph2PC᎐CBu [ref. 6].
᎐
᎐
DOI: 10.1039/b004594m
J. Chem. Soc., Dalton Trans., 2000, 3331–3339
3331
This journal is © The Royal Society of Chemistry 2000

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Table 1 Infrared, 1H and 31P NMR data for the new complexes 2–5
Compound
ν(CO)a/cmϪ1 a
1H NMR (δ)b
31P NMR (δ)c
2a
2037vs, 1989s, 1841br
7.7–6.8 [m, 15H, Ph], 5.10 [d, 3J(PH) 1.3,
5H, Cp], 3.76 [s, 3H, CO2Me], 3.73 [s, 3H,
CO2Me]
Ϫ31.0 [s, µ-C(CO2Me)᎐C(CO2Me)CPh᎐C(PPh2)]
᎐
᎐
2b
2c
2000vs, 1956s, 1828br
7.7–7.2 [m, 15H, Ph], 7.03 [s, 1H, CH], 5.10
Ϫ27.8 [µ-CBut᎐CHCPh᎐C(PPh2)]
᎐
᎐
[s, 5H, Cp], 1.20 [s, 9H, But]
2004vs, 1950m,
1810br
7.9–7.2 [m, 10H, Ph], 6.40 [d, 4J(PH) 4,
1H, CH], 5.00 [s, 5H, Cp], 1.31 [s, 9H, But],
1.20 [s, 9H, But]
Ϫ22.9 [µ-CBut᎐CHCBut᎐C(PPh2)]
᎐ ᎐
3
4
1986vs, 1938vs, 1115w
(P–O)
7.8–7.4 [m, 10H, Ph], 6.10 [d, 4J(PH) 6.5,
1H, CH], 4.80 [s, 5H, Cp], 1.30 [s, 9H, But],
1.01 [s, 9H, But]
63.5 [µ-CBut᎐CHCBut᎐C(PPh2O)]
᎐ ᎐
1964vs, 1916w, 1651w,
1581w
7.5–7.2 [m, 26H, Ph and µ-C(CO2Me)C(CPh-
CHPPh2)C(OMe)O], 5.47 [d, 3J(PH) 2.2,
5H, Cp], 3.67 [s, 3H, CO2Me], 3.12 [s, 3H,
CO2Me]
7.8–6.6 [m, 35H, Ph], 5.1 [s, 5H, Cp], 0.81
[m, 2H, µ-CCPhCH(CH2But)PPh2], 0.56
[dd, 3J(HH) 17.0, 2J(PH) 3.8, 1H, µ-CCPh-
CH(CH2But)PPh2], Ϫ0.05 [s, 9H, But]
136.4 [s, µ-PPh2], 63.1 [s, µ-C(CO2Me)C(CPh᎐
᎐
CHPPh2)C(OMe)O]
5
1958vs, 1924m
92.3 [d, 2J(PP) 111, µ-PPh2 trans to the ring], 89.6
[s, µ-PPh2], 78.3 [d, µ-C᎐CPhCH(CH2But)PPh2]
᎐
a Recorded in n-hexane solution. b 1H chemical shifts in ppm relative to SiMe4 (0.0 ppm), coupling constants in Hz in CDCl3 at 293 K. c 31P chemical
shifts in ppm relative to 85% external H3PO4 (0.0 ppm) (upfield shifts negative). Spectra were {1H}-gated decoupled and measured in CDCl3 at 293 K.
t
᎐
᎐
Scheme 1 Reagents and conditions: (i) Ph2PC᎐CPh, 383 K, C6H5Me; (ii) Ph2PC᎐CBu , 383 K, C6H5Me.
᎐
᎐
2 Results and discussion
(a) Reaction of [(ꢀ5-C5H5)(OC)2Mo(ꢁ-R1CCR2)Co(CO)3] with
᎐
Ph PC᎐CR
᎐
2
The reaction of [(η5-C5H5)(OC)2Mo(µ-R1CCR2)Co(CO)3] (R1 =
2
1
2
t
᎐
R = CO Me 1a; R = H, R = Bu 1b) with Ph PC᎐CPh in tolu-
᎐
2
2
ene at 383 K affords, respectively, in addition to unchanged
starting material, the complexes [(η5-C H )(OC)Mo{µ-CR2᎐
᎐
5
5
CR1CPh᎐C(PPh )}Co(CO) ] (R1 = R2 = CO Me 2a; R1 = H,
᎐
2
2
2
R2 = But 2b) as the only products in 27–33% yield (Scheme 1).
Complexes 2a and 2b have been characterised spectroscopically
(see Table 1 and Experimental section) and, in addition, their
molecular structures have been determined by single crystal
X-ray diffraction. The structures are illustrated in Figs. 2 and 3
while Table 2 lists selected bond distances and angles.
Crystals of complexes 2a and 2b suitable for X-ray diffraction
were obtained by slow evaporation of a CH2Cl2–hexane solu-
tion at 273 K. The structure of 2a consists of two independent
molecules (A and B) within the unit cell with the only appre-
ciable difference between them being the orientation of the
phenyl and CO2Me groups. The bond parameters for A and B
are essentially the same and only A will be discussed through-
out the following; bond lengths and angles are listed in Table 2
separately for the two molecules A and B. Owing to the simi-
larity of structures 2a and 2b they will be discussed together.
The metal atoms are linked by a Mo–Co bond [Mo(1)–Co(1)
2.694(1) (2a), 2.724(2) (2b) Å]12 and are bridged by an unsatur-
Fig. 2 Molecular structure of complex 2a including the atom number-
ing scheme. Hydrogen atoms have been omitted for clarity.
CR1CPh᎐C(PPh )] (R1 = R2 = CO Me 2a; R1 = H, R2 = But 2b).
᎐
2
2
The cobalt atom is bound terminally by two carbonyl groups
and the molybdenum by a carbonyl and a η5-cyclopentadienyl
ligand. The terminal carbon atoms (Cα) of the butadiene ligand
[C(1) and C(4)] are σ-bonded to Mo to give a metallacyclo-
pentadiene ring while co-ordination to the cobalt atom is
ated diphenylphosphino-substituted butadiene ligand [CR2᎐
᎐
3332
J. Chem. Soc., Dalton Trans., 2000, 3331–3339

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Table 2 Selected bond distances (Å) and angles (Њ) for [(η5-C5H5)-
(OC)Mo{µ-CR2᎐CR1CPh᎐C(PPh2)}Co(CO)2] (R1 = R2 = CO2Me 2a;
‘phospha-allene’ co-ordinated through both P᎐C and C᎐C
᎐
᎐
᎐
᎐
bonds, in that the P(1)–C(1) bond is short [1.719(7) 2a, 1.705(8)
Å 2b] indicating a bond order greater than unity.13 The C–C
bond distances within the butadiene [C(1)–C(2) 1.444(10), C(2)–
C(3) 1.423(10), C(3)–C(4) 1.443(10) 2a; 1.446(10), 1.412(11),
1.413(11) Å 2b] are similar indicating delocalisation over the
system, as previously observed for related molybdenum–cobalt
systems.5 The co-ordination of a related diphenylphosphino-
substituted butadiene ligand to a bimetallic backbone has been
reported for [Mn2(µ-PPh2CHCHCHCH)(µ-PPh2)(CO)5]; in this
case, however, the phosphine moiety is not constrained into a
three-membered ring.14 A number of examples of crystal-
lographically characterised bimetallic complexes containing the
R1 = H, R2 = But 2b)
2a
Molecule A
Molecule B
2b
Mo(1)–Co(1)
Mo(1)–P(1)
Mo(1)–C(1)
Mo(1)–C(4)
Mo(1)–C(5)
Mo(1)–(C5H5)centroid
P(1)–C(1)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
2.694(1)
2.403(2)
2.063(7)
2.175(7)
1.956(8)
2.007(7)
1.719(7)
1.444(10)
1.423(10)
1.443(10)
1.495(10)
—
2.082(7)
2.092(7)
2.071(7)
2.011(7)
1.774(9)
1.776(8)
2.710(1)
2.400(2)
2.067(7)
2.186(7)
1.966(8)
2.021(7)
1.716(8)
1.428(10)
1.432(10)
1.442(10)
1.482(10)
—
2.114(7)
2.118(7)
2.081(7)
2.011(8)
1.785(8)
1.781(8)
2.724(2)
2.416(4)
2.043(9)
2.250(8)
1.963(9)
2.010(5)
1.705(8)
1.446(10)
1.412(11)
1.413(11)
—
1.550(12)
2.032(8)
2.109(8)
2.106(9)
2.076(9)
1.753(9)
1.739(10)
diphenylphosphino fragment incorporated into
a three-
membered M–P–C ring have been reported. Notably, the
M–P–C angles in 2a and 2b fall in the bottom of the range.15
The spectroscopic properties of complexes 2a and 2b are in
accordance with the solid state properties being maintained in
solution, with a single sharp upfield resonance [δ Ϫ31.0 (2a),
Ϫ27.8 (2b)] in the 31P-{1H} NMR spectra being assigned to the
phosphorus atom of the molybdenaphosphaheterocycle. In the
13C-{1H} spectrum four separate resonances are observed for
the olefinic carbon atoms [δ 157.8, 151.1, 114.3, 114.1 (2a);
187.0, 152.6, 116.0, 112.3 (2b)] consistent with the unsym-
metrical nature of the butadiene ligand. In the case of 2b two
terminal carbonyl resonances have been resolved at δ 240.0 and
202.0, the former chemical shift being typical of a molyb-
denum-bound carbonyl group and the latter a cobalt-bound
carbonyl group.5 In the 1H NMR, in addition to signals for the
cyclopentadienyl and phenyl groups, two separate resonances
of equal integration are seen for the methyl carboxylate groups
of the butadiene ligand for 2a while for 2b two resonances of
relative integral 1:9 are seen for the CH and tert-butyl protons
at δ 7.03 and 1.20 respectively.
C(4)–C(8)CO Me
2
t
C(4)–C(8)Bu
Co(1)–C(1)
Co(1)–C(2)
Co(1)–C(3)
Co(1)–C(4)
Co(1)–C(6)
Co(1)–C(7)
C–O (carbonyl)
1.137–1.176
1.127–1.161
1.137–1.169
Mo(1)–C(1)–P(1)
P(1)–Mo(1)–C(1)
Mo(1)–P(1)–C(1)
Mo(1)–C(1)–C(2)
Co(1)–Mo(1)–
78.3(3)
44.5(2)
57.2(2)
127.8(5)
160.8(6)
78.1(3)
44.4(2)
57.5(2)
128.3(5)
160.4(6)
79.7(3)
44.0(2)
56.3(3)
126.1(6)
165.1(6)
(C5H5)centroid
C(1)–C(2)–C(3)
C(2)–C(3)–C(4)
C(3)–C(4)–Mo(1)
C(51)–P(1)–C(61)
C(7)–Co(1)–C(6)
C(71)–C(2)–C(1)
107.4(6)
113.9(6)
119.5(5)
106.0(3)
93.5(4)
108.5(6)
112.1(6)
120.8(5)
105.8(3)
91.4(4)
108.1(7)
117.3(7)
114.6(6)
104.9(4)
92.1(4)
The mechanism by which complexes 2a and 2b are formed
from 1 is uncertain. However, the regiospecific insertion of the
phosphinoalkyne into a molybdenum–carbon(alkyne) bond in
a manner similar to that observed for the reactions of 1 with
alkynes5 would seem the most likely pathway. Scheme 2 shows a
127.1(6)
120.9(6)
125.3(7)
Fig. 3 Molecular structure of complex 2b including the atom number-
ing scheme. All hydrogen atoms except for H3 have been omitted for
clarity.
Scheme 2 A possible reaction pathway to account for the formation of
complex 2 from 1.
achieved through the butadiene π bonds. In addition, one Cα
atom of the organic bridging ligand [C(1)] possesses a di-
phenylphosphino group which co-ordinates to the molybdenum
atom to form a strained three-membered metallacycle [Mo(1)–
P(1)–C(1) 57.2(2) 2a, 56.3(3)Њ 2b]. Owing to the phosphine co-
ordination, the carbon atom C(1) is closer to molybdenum
[Mo(1)–C(1) 2.063(7) 2a, 2.043(9) Å 2b] than the other
σ-bonded carbon atom C(4) [Mo(1)–C(4) 2.175(7) 2a, 2.250(8)
Å 2b]. The Ph2PCCPhR [R = C2(CO2Me)2 2a, CHCBut 2b]
moiety of the bridging ligand may also be viewed as a
plausible proposal involving initial substitution of one carbonyl
ligand on each of the molybdenum and cobalt atoms in 1 by a
᎐
molecule of Ph PC᎐CR (intermediate I) which binds to both
᎐
2
metal centres through the alkyne moiety in an η2 :η2 fashion.
Insertion of the alkyne functionality of the phosphinoalkyne
into a Mo–C(alkyne) bond of I with concomitant co-ordin-
ation of the phosphino group to molybdenum affords 2.
It is noteworthy that Davidson has previously demonstrated
a related conversion of a bis(alkyne)-bridged molybdenum–
cobalt complex (cf. I) into a butadiene-bridged species.16
J. Chem. Soc., Dalton Trans., 2000, 3331–3339
3333

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Table 3 Selected bond lengths (Å) and angles (Њ) for [(η5-C5H5)-
(OC)Mo{µ-CBut᎐CHCBut᎐C(PPh2O)}Co(CO)2] 3
phosphine oxide group which binds to molybdenum to form
᎐
᎐
a four-membered metallacyclic ring Mo(1)–C(1)–P(1)᎐O(1).
᎐
The phosphorus–oxygen bond [P(1)–O(1) 1.535(2) Å] of the
ligand retains substantial multiple bond character. It is much
shorter than expected for a P–O single bond [1.71 Å]17 and
instead is in agreement with the average bond length of the P–O
bond in phosphates at 1.54 Å.18 The Mo(1)–O(1)–P(1) angle in
3 [95.7(1)Њ] is smaller than those found in crystallographically
characterised molybdenum complexes containing monodentate
(range: 142.0–171.9Њ)19 and other chelating (range: 119.7–
156.1Њ) phosphine oxide ligands,20 but compares well with the
Mn–O–P angle (92.7Њ) in the vinylphosphonato complex
[Mn{(NC) C᎐CP(OPri) ᎐O}(dppe)(CO) ].21 The rather small
angle in 3 is presumably a consequence of the requirements of
the four-membered chelate ring. The small Mo(1)–O(1)–P(1)
angle means that the phosphorus atom is held close to the
molybdenum centre and allows some direct metal–phosphorus
interaction [Mo(1) ؒ ؒ ؒ P(1) 2.859(1) Å]. Burford et al. have dis-
cussed the relationship between bond distances and angles
and the extent of pπ–dπ bonding and proposed that extensive
Mo(1)–Co(1)
Mo(1)–C(4)
Mo(1)–C(5)
Mo(1)–(C5H5)centroid
P(1)–C(1)
C(1)–C(2)
C(2)–C(3)
2.684(1)
2.185(3)
1.996(3)
1.996(3)
1.745(3)
1.401(4)
1.454(4)
1.751(3)
2.264(2)
C(3)–C(4)
C(4)–C(8)
Co(1)–C(1)
Co(1)–C(2)
Co(1)–C(3)
Co(1)–C(4)
Co(1)–C(6)
P(1)–O(1)
1.405(4)
1.560(4)
2.044(3)
2.104(3)
2.088(3)
2.086(3)
1.728(3)
1.535(2)
2.155(3)
Co(1)–C(7)
Mo(1)–O(1)
Mo(1)–C(1)
C–O (carbonyl)
1.147–1.152
᎐
᎐
2
2
2
Mo(1)–C(1)–P(1)
Co(1)–Mo(1)–
(C5H5)centroid
P(1)–Mo(1)–C(1)
Mo(1)–P(1)–C(1)
Mo(1)–C(1)–C(2)
Mo(1)–O(1)–P(1)
93.7(1)
155.9(2)
O(1)–P(1)–C(1)
C(1)–C(2)–C(3)
C(2)–C(3)–C(4)
C(3)–C(4)–Mo(1)
P(1)–C(1)–Co(1)
C(7)–Co(1)–C(6)
C(12)–C(2)–C(1)
98.9(1)
110.6(2)
119.8(3)
112.4(2)
116.4(2)
91.0(2)
37.5(2)
48.8(1)
118.8(2)
95.7(1)
129.0(2)
Mo᎐O᎐P bonding occurs in compounds where the P–O–Mo
᎐ ᎐
linkage approaches linearity.22 However, in 3 the chelate ring
necessarily disrupts the π bonding to the metal and indeed the
Mo(1)–O(1) distance [2.264(2) Å] falls at the top end of the
range for other known Mo–O distances in phosphine oxide
complexes (usually in the range: 2.09–2.24 Å).19,20
In the FAB mass spectrum of complex 3 a molecular ion
peak is observed along with fragmentation peaks correspond-
ing to the loss of up to three carbonyl groups. The IR spectrum
in hexane shows, in addition to two terminal carbonyl bands, an
intense band at 1115 cmϪ1; a band at a very similar wavenumber
has been assigned to the P–O stretch in a related complex.23 The
31P-{1H} NMR spectrum displays a singlet at δ 63.5, shifted
downfield by ca. 85 ppm when compared with that of 2c. In the
1H NMR spectrum the CH proton on the butadiene ligand is
observed as a doublet at δ 6.10 with 4J(PH) 6.5 Hz.
The origin of the oxygen atom in complex 3 is uncertain but
is probably derived from adventitious oxygen in the reaction
mixture or on work-up on silica TLC plates. It is a notable fea-
ture that only in the reaction of 1b with tert-butyl substituted
phosphinoalkyne the oxidation occurs. There is no evidence
Fig. 4 Molecular structure of complex 3. Details as in Fig. 3.
Clearly the nature of the substituent R on the substrate
᎐
that a similar reaction occurs for 1a or 1b with Ph PC᎐CPh.
᎐
2
᎐
Ph PC᎐CR influences the type of reaction products isolated.
᎐
2
This is most clearly shown by the contrasting reaction of com-
t
(b) Reaction of [(ꢀ5-C H )(OC)Mo{ꢁ-CR2᎐CR1CPh᎐C(PPh )}-
Co(CO)2] with Ph2PH
᎐
᎐
5
5
2
᎐
᎐
plex 1a with Ph PC᎐CPh as compared to Ph PC᎐CBu . While
᎐
᎐
2
2
coupling of the bridging alkyne with the β-carbon of the
᎐
The reactions of [(η5-C H )(OC)Mo{µ-CR2᎐CR1CPh᎐
᎐ ᎐
5 5
᎐
phosphinoalkyne occurs with Ph PC᎐CPh (Schemes 1 and 2),
2
C(PPh2)}Co(CO)2] (R1 = R2 = CO2Me 2a; R1 = H, R2 = But 2b)
with diphenylphosphine in refluxing toluene for 24 h gave
cleavage of the P–C(alkyne) bond occurs in the reaction with
t
6
᎐
Ph PC᎐CBu (Fig. 1). Based on these observations it might
᎐
2
have been anticipated that the reaction of [(η5-C5H5)-
(OC) Mo(µ-HCCBu )Co(CO) ] 1b with Ph PC᎐CBu would
[(η5-C H )(OC)Mo{µ-C(CO Me)C(CPh᎐CHPPh )C(OMe)O}-
᎐
5
5
2
2
t
t
᎐
(µ-PPh2)Co(CO)]
4
and [(η5-C H )(OC)Mo{µ-C᎐CPhCH-
᎐
2
3
2
᎐
5
5
(CH2But)PPh2}(µ-PPh2)2Co(CO)] 5 respectively as the sole
products in yields of between 36 and 38%. In the case of the
reaction of 2b the yield was maximised by employing two
equivalents of Ph2PH (Scheme 3). Both complexes have been
characterised by 1H, 31P-{1H}, 13C-{1H} NMR, IR spectro-
scopy and by mass spectrometry and microanalysis (see Table 1
and Experimental section). In addition they have been the
subject of single crystal X-ray diffraction studies.
give a product analogous to that obtained in the reaction of 1a
with this phosphinoalkyne. However, the reaction in toluene at
383 K instead affords [(η5-C H )(OC)Mo{µ-CBut᎐CHCBut᎐
᎐
᎐
5
5
C(PPh2)}Co(CO)2] 2c, the analogue of 2a and 2b, as the minor
product (11%) and [(η5-C H )(OC)Mo{µ-CBut᎐CHCBut᎐
᎐
᎐
5
5
C(PPh2O)}Co(CO)2] 3 as the major product (24%) (Scheme 1).
Complex 2c has been characterised on the basis of the close
similarity in its spectroscopic properties to those of 2a and 2b
(see Table 1 and Experimental section) while 3 has been the
subject of a single crystal X-ray diffraction study.
The molecular structure of complex 4 is shown in Fig. 5,
while selected bond distances and angles are listed in Table 4.
The molecule consists of (η5-C5H5)(OC)Mo and Co(CO) units
linked by a single Mo(1)–Co(1) bond [2.654(2) Å].12 This bond
is bridged asymmetrically by the phosphido group [Mo(1)–
P(1) 2.433(2), Co(1)–P(1) 2.189(2) Å] and by a vinyl group in
which the α-carbon is σ-bonded to molybdenum [Mo(1)–C(5)
2.181(6) Å] and the carbon–carbon double bond is π-bonded to
cobalt [Co(1)–C(5) 1.927(6), Co(1)–C(6) 2.072(6) Å].
The molecular structure of complex 3 is depicted in Fig. 4;
Table 3 lists selected bond distances and angles. The mole-
cule comprises (η5-C5H5)(OC)Mo and Co(CO)2 units linked by
a Mo–Co bond [Mo(1)–Co(1) 2.684(1) Å]12 and bridged by a
diphenylphosphine oxide-substituted butadiene ligand [µ-CBut᎐
᎐
CHCBut᎐C(PPh O)]. The butadiene σ-bonds to molybdenum
᎐
2
via C(1) and C(4) and π-bonds to cobalt via the butadiene
double bonds [C(1)᎐C(2) and C(3)᎐C(4)] in a fashion similar to
᎐
᎐
The β-carbon of the vinyl group has two substituents
namely methyl carboxylate and vinylphosphine. The former
that in 2a and 2b and elsewhere.5 The substituent on C(1) is a
3334 J. Chem. Soc., Dalton Trans., 2000, 3331–3339

View Article Online
Scheme 3 Reagents and conditions: (i) Ph2PH, 383 K, C6H5Me; (ii) 2Ph2PH, 383 K, C6H5Me.
Table 4 Selected bond lengths (Å) and angles (Њ) for [(η5-C5H5)-
(OC)Mo{µ-C(CO2Me)C(CPh᎐CHPPh2)C(OMe)O}(µ-PPh2)Co(CO)] 4
᎐
Mo(1)–C(5)
Mo(1)–P(1)
Co(1)–C(5)
Co(1)–P(1)
C(4)–O(4)
C(5)–C(6)
C(6)–C(7)
O(6)–C(7)
Mo(1)–(C5H5)centroid
Co(1)–C(2)
2.181(6)
2.433(2)
1.927(6)
2.189(2)
1.217(8)
1.446(8)
1.442(9)
1.255(7)
1.986(5)
1.762(8)
Mo(1)–O(6)
Mo(1)–Co(1)
Co(1)–C(6)
Co(1)–P(2)
C(4)–C(5)
O(5)–C(7)
C(6)–C(9)
2.219(4)
2.654(2)
2.072(6)
2.205(2)
1.467(8)
1.320(7)
1.512(8)
1.338(9)
1.998(8)
C(9)–C(10)
Mo(1)–C(1)
C(5)–Mo(1)–O(6)
O(6)–Mo(1)–P(1)
P(1)–Mo(1)–Co(1)
C(1)–Co(1)–P(1)
P(1)–Co(1)–Mo(1)
Co(1)–Mo(1)–
(C5H5)centroid
Co(1)–P(1)–Mo(1)
C(6)–C(5)–C(4)
75.8(2)
130.4(1)
50.8(1)
88.9(2)
54.1(2)
159.7(3)
C(7)–C(6)–C(9)
P(1)–Co(1)–P(2)
P(2)–Co(1)–Mo(1)
C(9)–C(10)–P(2)
Co(1)–C(5)–Mo(1)
C(10)–P(2)–Co(1)
C(10)–C(9)–C(6)
C(7)–O(6)–Mo(1)
C(6)–C(6)–C(9)
119.8(5)
119.7(1)
153.3(1)
118.8(5)
80.2(2)
100.2(2)
119.2(6)
112.8(4)
123.1(5)
69.9(1)
121.4(6)
Fig. 5 Molecular structure of complex 4 including the atom number-
ing scheme. All hydrogen atoms except for H10 have been omitted for
clarity.
Table 5 Selected bond lengths (Å) and angles (Њ) for species [(η5-
C5H5)(OC)Mo{µ-C᎐CPhCH(CH2But)PPh2}(µ-PPh2)2Co(CO)] 5
᎐
co-ordinates to molybdenum via the oxygen atom [Mo(1)–O(6)
2.219(4) Å] to form a slightly puckered five-membered molyb-
Mo(1)–Co(1)
Mo(1)–P(1)
Co(1)–C(51)
Co(1)–P(1)
P(3)–C(49)
C(48)–C(49)
C(50)–C(51)
Mo(1)–C(1)
2.600(2)
2.439(3)
1.982(11)
2.208(4)
1.869(11)
1.56(2)
Mo(1)–C(51)
Mo(1)–P(2)
Co(1)–P(3)
2.116(13)
2.406(4)
2.158(4)
2.218(3)
1.57(2)
1.51(2)
1.998(2)
1.754(13)
denacyclic ring Mo–C᎐C–C᎐O [C(5) sitting 0.45 Å out of
᎐
᎐
Mo(1)C(6)C(7)O(6) plane]24 while the latter co-ordinates to
cobalt via the phosphorus atom to form a seven-membered
Co(1)–P(2)
C(47)–C(48)
C(49)–C(50)
Mo(1)–(C5H5)centroid
Co(1)–C(2)
dimetallacyclic Mo–C᎐C–C᎐C–P–Co ring. Unlike the unsat-
᎐
᎐
urated double bonds in complexes 2a and 2b the non-co-
ordinated carbon–carbon double bond [C(9)–C(10)] in 4
maintains its double bond character [1.338(9) Å].
1.35(2)
2.010(13)
The spectroscopic properties of complex 4 are consistent
with the solid-state properties being maintained in solution.
The IR spectrum displays, in addition to terminal carbonyl
bands, two absorptions at 1651 and 1581 cmϪ1 corresponding to
carbonyl bands of the ester group. The band at lower wave-
number can be attributed to the ester group co-ordinated to
the molybdenum atom.12b The FAB mass spectrum shows a
molecular ion peak and sequential fragmentation peaks result-
C(1)–Mo(1)–C(51)
Co(51)–Mo(1)–P(1)
P(1)–Mo(1)–Co(1)
P(1)–Co(1)–P(2)
P(3)–Co(1)–Mo(1)
P(2)–Co(1)–Mo(1)
Co(1)–P(2)–Mo(1)
Co(1)–Mo(1)–
127.8(5)
67.8(3)
51.9(1)
119.1(1)
133.5(1)
59.3(1)
68.2(1)
151.3(7)
C(50)–C(51)–Mo(1) 155.7(9)
C(51)–Mo(1)–P(2)
P(2)–Mo(1)–P(1)
P(2)–Mo(1)–Co(1)
P(3)–Co(1)–P(1)
P(3)–Co(1)–P(2)
P(1)–Co(1)–Mo(1)
Co(1)–P(1)–Mo(1)
C(50)–C(49)–P(3)
C(51)–C(50)–C(49)
C(50)–C(51)–Co(1)
69.3(4)
103.9(1)
52.4(1)
117.8(1)
108.3(1)
60.3(1)
67.8(1)
(C5H5)centroid
C(51)–C(50)–C(52)
C(52)–C(50)–C(49)
102.4(8)
119.4(10)
125.6(9)
1
124.4(11)
116.2(10)
ing from the loss of two carbonyl groups. The H NMR spec-
trum shows multiplets in the region δ 7.5–7.2 attributable to the
phenyl hydrogen atoms of the phosphido, phosphine and the
3
olefinic hydrogen. The doublet at δ 5.47 with J(PH) 2.2 Hz is
assigned to the cyclopentadienyl ring on the molybdenum atom
while the singlets at δ 3.67 and 3.12 are assigned respectively
to the co-ordinated and unco-ordinated methyl carboxylate
groups. Two signals are seen in the 31P-{1H} NMR spectrum at
δ 63.1 and 136.4, the downfield signal being assigned to a bridg-
ing phosphido group and the upfield signal to the phosphorus
atom incorporated into a metallacycle.12b,c,h
The molecular structure of complex 5 is depicted in Fig. 6,
while selected bond distances and angles are listed in Table 5.
The structure consists of a short molybdenum–cobalt bond
[2.600(2) Å]12 linking the (η5-C5H5)(OC)Mo and Co(CO) units
and bridged by two phosphido groups and by C(51) which
forms part of a phosphine-substituted vinylidene ligand
[C᎐CPhCH(CH But)PPh ]. This vinylidene ligand wraps
᎐
2
2
J. Chem. Soc., Dalton Trans., 2000, 3331–3339
3335

View Article Online
Fig. 6 Molecular structure of complex 5 including the atom number-
ing scheme. All hydrogen atoms except for H49, H48A and H48B have
been omitted for clarity.
around to co-ordinate through the phosphorus centre to cobalt
so as to form a five-membered [Co(1)–C(51)᎐C(50)–C(49)–
᎐
P(3)] chelate ring. The C(51) atom is asymmetrically bound to
the two metals, the Co(1)–C(51) bond distance being 1.982(11)
Å as compared to the Mo(1)–C(51) distance of 2.116(13) Å.
The C(51)–C(50) bond distance of 1.35(2) Å is typical of C᎐C
᎐
bond distances in other µ-vinylidene ligands.25 Further evidence
of the sp2 hybridised nature of the C(50) carbon atom comes
from the angles around C(50). The C(49)–C(50)–C(51) angle is
119.4(10)Њ, C(49)–C(50)–C(52) is 116.2(10)Њ and C(52)–C(50)–
C(51) is 124.4(11)Њ, close to those required for idealised sp2
Scheme 4 A possible reaction pathway to account for the formation of
complex 4 from 2a (Cp = η5-C5H5).
hybridisation. The Co(1)–C(51)᎐C(50)–C(49)–P(3) chelate ring
᎐
is almost planar (maximum deviation from planarity, C(49)
0.147 Å) and the remaining bond distances within the ring are
consistent with single bonds.
The solution state spectroscopic data for complex 5 are con-
sistent with the solid-state structure being maintained in solu-
tion. Three phosphorus resonances are seen in the 31P-{1H}
NMR spectrum, the more downfield signals at δ 92.3 and 89.6
being assigned to the phosphido groups, the former of which
takes the form of a doublet [2J(PP) 111 Hz] and has further
been assigned to the phosphido group trans to the ring phos-
phorus. The more upfield doublet at δ 78.3 is assigned to the
ring phosphorus atom. In the 1H NMR spectrum, in addi-
tion to phenyl, cyclopentadienyl and tert-butyl resonances,
3
2
a doublet of doublets at δ 0.56 with J(HH) 17.0 and J(PH)
3.8 Hz is assigned to the µ-C᎐CPhCH(CH But)PPh proton.
᎐
2
2
A multiplet at δ 0.81 is assigned to the methylene protons of
the µ-C᎐CPhCH(CH But)PPh ligand, the complexity of which
᎐
2
2
results from the overlapping of signals due to inequivalent
coupled C(Ha)(Hb) protons.
The explanation as to why the reactions of complexes 2a and
2b with diphenylphosphine do not follow the same course is
uncertain. Possible reaction pathways for the formation of 4
and 5 are illustrated in Schemes 4 and 5 respectively. In Scheme
4 ring opening of the metallaphosphaheterocycle in 2a occurs
on co-ordination of a molecule of Ph2PH to the molyb-
denum centre to give A. This is followed by oxidative addition
of the P–H bond at the molybdenum to form PPh2 and H
ligands; reductive elimination and migration of the H atom to
the phosphino-substituted terminal vinyl carbon atom of the
butadiene ligand leads to B. A ligand rearrangement occurs
with the ketonic oxygen atom of the CO2Me substituent dis-
placing the molybdenum-bound vinyl group to give C, this
being followed by co-ordination of the pendant phosphino
group to cobalt and concomitant CO loss to afford 4.
In Scheme 5 complex 2b undergoes similar initial Ph2PH
substitution (intermediate D) and oxidative addition steps. In
Scheme 5 A possible reaction pathway to account for the formation of
complex 5 from 2b.
3336
J. Chem. Soc., Dalton Trans., 2000, 3331–3339

View Article Online
contrast to that in Scheme 4, migration of the resultant H
ligand occurs to the non-phosphino-substituted terminal vinyl
carbon atom of the butadiene ligand to give E. Substitu-
tion of a terminal cobalt carbonyl group by a second mole-
cule of Ph2PH gives F which is then followed by regiospecific
insertion of the π-bonded vinyl group into the P–H bond of
the co-ordinated phosphine to give G. Ring opening of the
metallaphosphaheterocycle in G by scission of the P–C bond
and ligand rearrangement gives H which may be followed by
co-ordination of the terminal phosphide in H to the cobalt to
afford the co-ordinatively saturated species 5.
C(CO2Me)CPhC(PPh2)}Co(CO)2] 2a (0.58 g, 33%). FAB
mass spectrum: m/z 732 (Mϩ) and Mϩ Ϫ nCO (n = 1–3). NMR
(CDCl3): 13C (1H composite pulse decoupled), δ 177.1 [s,
CO2Me], 167.0 [d, 3J(PC) 5, CO2Me], 157.8 [d, 2J(PC) 11,
µ-C(CO Me)᎐C(CO Me)CPhC(PPh )], 151.1 [d, 3J(PC) 4,
᎐
2
2
2
µ-C(CO Me)᎐C(CO Me)CPhC(PPh )], 127–136 [m, Ph], 114.3
᎐
2
2
2
2
[d, J(PC) 11, µ-C(CO Me)᎐C(CO Me)CPhC(PPh )], 114.1 [d,
᎐
᎐
2
2
2
1J(PC) 18 Hz, µ-C(CO Me)᎐C(CO Me)CPhC(PPh )], 93.2 [s,
2
2
2
C5H5], 52.5 [s, CO2Me] and 51.5 [s, CO2Me].
(c) Reaction of [(ꢀ5-C5H5)(OC)2Mo(ꢁ-HCCBut)Co(CO)3] 1b
It is noteworthy that we have recently reported the conversion
᎐
with Ph PC᎐CPh
᎐
2
of a bridging Ph PCR᎐CR group into a Ph PCR᎐CHR ligand
᎐
᎐
2
2
The complex [(η5-C5H5)(OC)2Mo(µ-HCCBut)Co(CO)3] 1b
by thermally induced P–H bond cleavage of a terminally bound
diphenylphosphine ligand and migration of the resultant
hydrogen atom to the α-carbon of the co-ordinated vinyl group,
a step that relates to the conversion of A/D into B/E
respectively.26
(0.70 g, 1.50 mmol) was dissolved in toluene (70 cm3) and
᎐
Ph PC᎐CPh (0.44 g, 1.53 mmol) introduced. After stirring at
᎐
2
383 K for 2 h the volatiles were removed under reduced pres-
sure. The resulting brown residue was absorbed onto the mini-
mum amount of silica, added to the top of a chromatography
column and purified with hexane–ethyl acetate (5:1) as eluent.
This gave the brownish yellow crystalline complex [(η5-C5H5)-
(OC)Mo{µ-CButCHCPhC(PPh2)}Co(CO)2] 2b (0.28 g, 27%)
(Found: C, 59.9; H, 4.5. C34H30CoMoO3P requires C, 60.7; H,
4.5%). FAB mass spectrum: m/z 672 (Mϩ) and Mϩ Ϫ nCO
(n = 1–3). NMR (CDCl3): 13C (1H composite pulse decoupled),
3 Conclusion
By variation of either the nature of the R substituent on
᎐
the phosphinoalkyne Ph PC᎐CR or of the substituents on the
᎐
2
bridging alkyne ligand in complex 1, the selective insertion of
᎐
a molecule of Ph PC᎐CR into a molybdenum–carbon(alkyne)
᎐
2
δ 240.0 [s, Mo–CO], 202.0 [s, Co–CO], 187.0 [s, µ-CBut᎐
᎐
bond can be achieved to give butadiene-co-ordinated complexes
containing highly strained three-membered metallaphospha-
heterocycles; the facility for ring opening has been probed with
diphenylphosphine and found to follow two different reaction
pathways.
CHCPh᎐C(PPh )], 152.6 [s, µ-CBut᎐CHCPh᎐C(PPh )], 137–
᎐
᎐
᎐
2
2
127 [m, Ph], 116.0 [s, µ-CBut᎐CHCPh᎐C(PPh )], 112.3 [d,
᎐
᎐
2
3J(PC) 19, µ-CBut᎐CHCPh᎐C(PPh )], 91.6 [s, C H ], 43.2 [s,
᎐
᎐
2
5
5
CMe3] and 33.5 [s, CMe3].
(d) Reaction of [(ꢀ5-C5H5)(OC)2Mo(ꢁ-HCCBut)Co(CO)3] 1b
t
4 Experimental
᎐
with Ph PC᎐CBu
᎐
2
To a solution of [(η5-C5H5)(OC)2Mo(µ-HCCBut)Co(CO)3] 1b
(a) General techniques
3
t
᎐
(0.49 g, 1.10 mmol) in toluene (70 cm ) was added Ph PC᎐CBu
᎐
All reactions were carried out under a nitrogen atmosphere
using standard Schlenk techniques. Solvents were distilled
under nitrogen from appropriate drying agents and degassed
prior to use.27 Infrared spectra were recorded in hexane solu-
tion in 0.5 mm NaCl cells using a Perkin-Elmer 1710 Fourier-
transform spectrometer, fast atom bombardment (FAB) mass
spectra on a Kratos MS 890 instrument using 3-nitrobenzyl
alcohol as a matrix and proton (reference to SiMe4) and 31P
NMR spectra on either a Bruker WM250 or AM400 spec-
trometer, 31P-NMR chemical shifts being referenced to 85%
H3PO4. Preparative thin-layer chromatography (TLC) was
carried out on commercial Merck plates with a 0.25 mm layer
of silica, or on 1 mm silica plates prepared at the University
Chemical Laboratory, Cambridge. Column chromatography
was performed on Kieselgel 60 (70–230 or 230–400 mesh).
Products are given in order of decreasing Rf values. Elemental
analyses were performed at the University Chemical Labora-
tory, Cambridge.
2
(0.30 g, 1.12 mmol) and the resulting solution stirred at 383 K
for 6 h. After removal of the volatiles under reduced pressure,
the residue was purified by preparative TLC using hexane–
ethyl acetate (5:1) as eluent. This gave orange complex [(η5-
C5H5)(OC)Mo{µ-CButCHCButC(PPh2)}Co(CO)2] 2c (0.08 g,
11%) and brown complex [(η5-C5H5)(OC)Mo{µ-CButCHCBut-
C(PPh2O)}Co(CO)2] 3 (0.16 g, 24%). Complex 2c (Found: C,
58.1; H, 5.2. C32H34CoMoO3PؒCH2Cl2 requires C, 58.9; H,
5.3%): FAB mass spectrum m/z 654 (Mϩ) and Mϩ Ϫ nCO
(n = 1–3); NMR (CDCl3) 13C (1H composite pulse decoupled),
δ 240.4 [s, Mo–CO], 203.3 [s, Co–CO], 187.3 [s, µ-CBut᎐
᎐
CHCBut᎐C(PPh )], 167.7 [s, µ-CBut᎐CHCBut᎐C(PPh )], 149.9
᎐
᎐
᎐
2
2
[s, µ-CBut᎐CHCBut᎐C(PPh )], 135–125 [m, Ph], 112.3 [d,
᎐
᎐
2
3J(PC) 21 Hz, µ-CBut᎐CHCBut᎐C(PPh )], 91.5 [s, C H ], 43.0
᎐
᎐
2
5
5
[s, CMe3], 38.7 [s, CMe3], 33.5 [s, CMe3] and 32.4 [s, CMe3].
Complex 3 (Found: C, 56.9; H, 5.38. C32H34CoMoO4P requires
C, 57.5; H, 5.13%): FAB mass spectrum m/z 668 (Mϩ) and
Mϩ Ϫ nCO (n ᎐ 1–3). NMR (CDCl ) 13C (1H composite pulse
᎐
Unless otherwise stated all reagents were obtained from
commercial suppliers and used without further purification.
The syntheses of [(η5-C5H5)(OC)2Mo(µ-R1CCR2)Co(CO)3]
3
decoupled), δ 205.0 [s, Co–CO], 191.5 [s, µ-CBut᎐CHCBut᎐
᎐
᎐
C(PPh O)], 133–127 [m, Ph], 109.1 [d, J(PC) 10 Hz, µ-CBut᎐
3
᎐
2
CHCBut᎐C(PPh O)], 92.0 [s, C H ], 45.1 [s, CMe ], 36.7 [s,
(R1 = R2 = CO2Me 1a; R1 = H, R2 = But 1b)5a and Ph PC᎐CR
2
5
5
3
᎐
᎐
᎐
2
(R = But or Ph)28 have been reported previously.
CMe3], 34.8 [s, CMe3] and 32.1 [CMe3].
(b) Reaction of [(ꢀ5-C5H5)(OC)2Mo{ꢁ-C2(CO2Me)2}Co(CO)3]
(e) Reaction of [(ꢀ5-C5H5)(OC)Mo{ꢁ-C(CO2Me)C(CO2Me)-
CPhC(PPh2)}Co(CO)2] 2a with Ph2PH
᎐
1a with Ph PC᎐CPh
᎐
2
To a solution of [(η5-C5H5)(OC)2Mo{µ-C2(CO2Me)2}Co(CO)3]
To a solution of [(η5-C5H5)(OC)Mo{µ-C(CO2Me)C(CO2Me)-
CPhC(PPh2)}Co(CO)2] 2a (0.33 g, 0.45 mmol) in toluene (50
cm3) was added diphenylphosphine (0.10 cm3, 0.57 mmol).
After stirring at 383 K for 24 h, the volatiles were removed
under reduced pressure and the residue purified by preparative
TLC using hexane–ethyl acetate (3:1) as eluent. This gave, in
addition to a small amount of unchanged starting material, the
greenish crystalline complex [(η5-C5H5)(OC)Mo{µ-C(CO2Me)-
C(CPhCHPPh2)C(OMe)O}(µ-PPh2)Co(CO)] 4 (0.14 g, 36%)
3
᎐
1a (1.20 g, 2.4 mmol) in toluene (70 cm ) was added Ph PC᎐
᎐
2
CPh (0.71 g, 2.5 mmol) and the resulting solution stirred at
383 K for 4 h. After removal of the volatiles under reduced
pressure, the mixture was absorbed onto the minimum quantity
of silica, added to the top of a chromatography column and
purified with hexane–ethyl acetate (4:1) as eluent. This gave, in
addition to a small amount of starting material, the brownish
yellow crystalline complex [(η5-C5H5)(OC)Mo{µ-C(CO2Me)-
J. Chem. Soc., Dalton Trans., 2000, 3331–3339
3337

View Article Online
Table 6 Crystallographic and data processing parameters for complexes 2a, 2b, 3, 4 and 5
2a
2b
3
4
5
Empirical formula
C34H26CoMoO7P
C34H30CoMoO3P
C32H34CoMoO4P
C45H37CoMoO6P2ؒ
CH2Cl2ؒCH3OH
1007.52
C57H52CoMoO2P3ؒ
CH2Cl2ؒ1.5C6H14
1230.95
Formula weight
732.39
672.42
668.43
Crystal system
Space group
Triclinic
P1
Monoclinic
P21/c
Monoclinic
P21/n
Monoclinic
P21/c
Triclinic
P1
¯
¯
a/Å
b/Å
c/Å
α/Њ
15.502(2)
21.848(3)
10.290(1)
91.85(1)
108.33(1)
71.29(1)
3124.3(7)
4
1.031
10.771(19)
28.163(12)
11.014(12)
10.989(4)
12.810(7)
21.045(3)
20.676(7)
18.323(4)
12.021(6)
15.460(5)
18.534(5)
11.506(5)
103.78(3)
91.12(3)
76.21(3)
3107(2)
β/Њ
119.27(5)
102.80(2)
102.79(3)
γ/Њ
U/Å3
2914(6)
4
1.088
7863
5102 (Rint = 0.051)
0.0701, 0.1743
0.1059, 0.2035
2888.9(12)
4
1.099
4441(3)
4
0.899
10808
7844 (Rint = 0.057)
0.0569, 0.1085
0.1412, 0.1449
Z
2
µ(Mo-Kα)/mmϪ1
Reflections collected
Independent reflections
Final R1, wR2 I > 2σ(I )
all data
0.674
19369
10516 (Rint = 0.123)
0.1044, 0.2871
0.1962, 0.3402
11453
6969
11008 (Rint = 0.058)
0.0531, 0.1095
0.1353, 0.1596
6629 (Rint = 0.029)
0.0387, 0.0932
0.0543, 0.1019
Data in common: graphite-monochromated Mo-Kα radiation, λ = 0.71073 Å, 180(2) K, refinement based on F2.
(Found: C, 57.8; H, 4.2. C45H37CoMoO6P2ؒCH2Cl2 requires
C, 60.2; H, 4.6%). FAB mass spectrum: m/z 890 (Mϩ) and
Mϩ Ϫ nCO (n = 1 or 2). NMR (CDCl3): 13C (1H composite pulse
decoupled), δ 209.7 [s, Mo–CO], 201.4 [s, Co–CO], 185.3 [s,
CO2Me], 182.5 [s, CO2Me], 166.4 [d, 2J(PC) 22, µ-C(CO2-
CCDC reference number 186/2147.
Seehttp://www.rsc.org/suppdata/dt/b0/b004594m/forcrystal-
lographic files in .cif format.
Acknowledgements
Me)᎐C(CPh᎐CHPPh )C(OMe)O], 139–126 [m, Ph and µ-
᎐
᎐
2
We thank the EPSRC for funding for the X-ray diffractometer
and for financial support to J. E. D. We are also grateful to the
Cambridge Commonwealth Trust and Professor B. F. G.
Johnson for funding to K. S.
C(CO Me)᎐C(CPh᎐CHPPh )C(OMe)O], 92.5 [s, C H ], 53.6
[s, CO2Me] and 49.6 [CO2Me].
᎐
᎐
2
2
5
5
(f) Reaction of [(ꢀ5-C5H5)(OC)Mo{ꢁ-CButCHCPhC(PPh2)}-
Co(CO)2] 2b with Ph2PH
To a solution of [(η5-C5H5)(OC)Mo{µ-CButCHCPhC(PPh2)}-
Co(CO)2] 2b (0.30 g, 0.44 mmol) in toluene (50 cm3) was added
diphenylphosphine (0.20 cm3, 1.15 mmol). The solution was
stirred at 383 K for 24 h. After removal of the volatiles under
reduced pressure, the mixture was purified by preparative TLC
using hexane–ethyl acetate (3:1) as eluent. This gave, in addi-
tion to a small amount of unchanged starting material, the
reddish crystalline complex [(η5-C5H5)(OC)Mo{µ-CCPhCH-
References
1 R. S. Dickson and P. J. Fraser, Adv. Organomet. Chem., 1974, 12,
323; R. S. Dickson and G. R. Tailby, Aust. J. Chem., 1971, 23, 229;
U. Krüerke and W. Hübel, Chem. Ber., 1961, 94, 2829; E. M. Arnett,
J. Am. Chem. Soc., 1964, 86, 4729.
2 S. Slater and E. L. Muetterties, Inorg. Chem., 1980, 19, 3337;
S. A. R. Knox, R. F. D. Stansfield, F. G. A. Stone, M. J. Winter
and P. Woodward, J. Chem. Soc., Dalton Trans., 1982, 173; A. M.
Boileau, A. G. Orpen, R. F. D. Stansfield and P. Woodward,
J. Chem. Soc., Dalton Trans., 1982, 187; R. J. Baxter, G. R. Knox,
P. L. Pauson and M. D. Spicer, Organometallics, 1999, 18, 197.
3 M. J. Winter, in The Chemistry of the Metal–Carbon Bond,
eds. R. R. Hartley and S. Patai, John Wiley & Sons, Chichester,
1985, vol. 3, pp. 259–294; M. J. Winter, Adv. Organomet. Chem.,
1989, 29, 101.
(CH2But)PPh2}(µ-PPh2)2Co(CO)]
5 (0.18 g, 38%). FAB
mass spectrum: m/z 1016 (Mϩ) and Mϩ Ϫ nCO (n = 1 or 2).
NMR (CDCl3): 13C (1H composite pulse decoupled), δ 136–125
[m, Ph], 91.6 [s, µ-C᎐CPhCH(CH But)PPh ], 88.2 [s, C H ], 64.5
᎐
2
2
5
5
2
[s, µ-C᎐CPhCH(CH But)PPh ], 42.7 [s, CMe ], 30.0 [d, J(PC)
᎐
2
2
3
28 Hz, µ-C᎐CPhCH(CH But)PPh ] and 29.7 [s, CMe ].
᎐
2
2
3
4 Q. Feng, M. L. H. Green and P. Mountford, J. Chem. Soc., Dalton
Trans., 1992, 217.
(g) Crystal structure determinations of complexes 2a, 2b, 3,
4 and 5
5 (a) R. Yanez, N. Lugan and R. Mathieu, Organometallics, 1990,
9, 2998; (b) F.-E. Hong, I.-R. Lue, S. C. Lo and C. C. Lin,
J. Organomet. Chem., 1995, 495, 97; (c) W. Hirpo, M. D. Curtis and
J. W. Kampf, Organometallics, 1994, 13, 3360.
6 J. E. Davies, M. J. Mays, P. R. Raithby, K. Sarveswaran and
G. P. Shields, J. Organomet. Chem., 1999, 573, 180.
7 A. J. Carty, Pure Appl. Chem., 1982, 54, 113; A. A. Cherkas, L. H.
Randall, S. A. MacLaughlin, G. N. Mott, N. J. Taylor and A. J.
Carty, Organometallics, 1988, 7, 969; A. J. Carty, D. Nucciarone,
S. A. MacLaughlin and N. J. Taylor, Organometallics, 1988, 7, 106.
8 M. H. A. Benvenutti, M. D. Vargas, D. Braga, F. Grepioni,
E. Parisini and B. E. Mann, Organometallics, 1993, 12, 2955;
M. H. A. Benvenutti, M. D. Vargas, D. Braga, F. Grepioni,
B. E. Mann and S. Naylor, Organometallics, 1993, 12, 2947;
M. D. Vargas, R. M. S. Periera, D. Braga and F. Grepioni, J. Chem.
Soc., Chem. Commun., 1993, 1008.
9 B. J. Bobbie, N. J. Taylor and A. J. Carty, J. Chem. Soc., Chem.
Commun., 1991, 1511; E. Sappa, A. Pasquinelli, A. Tiripicchio and
M. Tiripicchio Camellini, J. Chem. Soc., Dalton Trans., 1989, 601.
10 J. C. Jeffery, R. M. S. Pereira, M. D. Vargas and M. J. Went, J. Chem.
Soc., Dalton Trans., 1995, 1805.
X-Ray intensity data were collected with Rigaku AFC5R (com-
plexes 2a and 4) and AFC7R diffractometers (2b and 3) and
a Rigaku RAXIS-IIC image plate (5). Details of data collec-
tion, refinement and crystal data are listed in Table 6. All data
were corrected for Lorentz-polarisation factors. Semi-empirical
absorption corrections based on φ scans29 were applied to the
data for 2a, 2b, 3 and 4; no absorption correction was applied to
the data for 5.
For all the complexes the positions of the metal atoms and
most non-hydrogen atoms were located from direct methods,
and the remaining non-hydrogen atoms revealed from sub-
sequent Fourier difference syntheses. Refinement was based on
F2.30 Hydrogen atoms were placed in idealised positions and
refined using a riding model or as rigid methyl groups.
In complex 5 two molecules of poorly resolved hexane
solvate were observed in the asymmetric unit and one was
modelled as disordered over two sites; extensive common dis-
tance constraints had to be applied to both molecules during
the refinement process in order to preserve sensible geometry.
11 R. S. Dickson, T. de Simone, R. J. Parker and G. D. Fallon,
Organometallics, 1997, 16, 1531.
12 Single metal–metal bond distances for organo-bridged Co–Mo
bimetallic complexes range from 2.68 to 2.90 Å. See refs. 5 and 6
3338
J. Chem. Soc., Dalton Trans., 2000, 3331–3339

View Article Online
1986, 25, 3624; F. A. Cotton, M. Kohli, R. L. Luck and J. V.
Silverson, Inorg. Chem., 1993, 32, 1868; C. D. Garner, N. C.
Howlader, F. E. Mabbs, A. T. McPhail and K. D. Onan, J. Chem.
Soc., Dalton Trans., 1978, 1848; C. Limberg, M. Büchner, K. Heinz
and O. Walter, Inorg. Chem., 1997, 36, 872; J. Chatt, R. Choukroun,
J. Dilworth, J. Hyde, P. Vella and J. Zubieta, Transition Met. Chem.,
1979, 4, 59.
and (a) G. Barrado, J. Li, D. Miguel, J. A. Perez-Martinez,
V. Riera, C. Bois and Y. Jeannin, Organometallics, 1994, 13, 2330;
(b) A. Martin, M. J. Mays, P. R. Raithby and G. A. Solan, J. Chem.
Soc., Dalton Trans., 1993, 1431; (c) S. L. Ingham, M. J. Mays,
P. R. Raithby, G. A. Solan, B. V. Sundavadra, G. Conole and
M. Kessler, J. Chem. Soc., Dalton Trans., 1994, 3607; (d) S. D.
Jensen, B. H. Robinson and J. Simpson, Organometallics, 1986,
5, 1690; (e) L. C. Song, J.-Y. Shen, Q.-M. Hu, B.-S. Han, R.-J.
Wang and H.-G. Wang, Inorg. Chim. Acta, 1994, 219, 93; ( f )
J.-C. Tsai, R. A. Wheeler, M. A. Khan and K. M. Nicholas,
Organometallics, 1991, 10, 1344; (g) M. Gruselle, H. El Hafa,
M. Nikolski, G. Jaouen, J. Vaissermann, L.-J. Li and M. J.
McGlinchey, Organometallics, 1993, 12, 4917; (h) J. D. King, M. J.
Mays, G. E. Pateman, P. R. Raithby, M. A. Rennie, G. A. Solan,
N. Choi, G. Conole and M. McPartlin, J. Chem. Soc., Dalton Trans.,
1999, 4447.
20 T. Tanase, T. Igoshi and Y. Yamamoto, Inorg. Chim. Acta, 1997, 256,
61; P. K. Baker, M. G. B. Drew and M. M. Meehan, J. Chem. Soc.,
Dalton Trans., 1999, 765; M. A. Bakar, A. Hill, D. L. Hughes
and G. J. Leigh, J. Chem. Soc., Dalton Trans., 1989, 1417; P. M.
Boorman, H. -B. Kraatz and M. Parvez, Polyhedron, 1993, 12, 601;
A. Herbowski, T. Lis and E. A. Deutsch, J. Organomet. Chem.,
1993, 460, 25; P. Dahlke, J. C. Jeffery, M. D. Mortimer and F. G. A.
Stone, Polyhedron, 1992, 11, 1587.
21 M. G. Newton, N. S. Pantaleo, R. B. King and S. P. Diefenbach,
J. Chem. Soc., Chem. Commun., 1979, 55.
22 N. Burford, B. W. Royan, R. E. V. H. Spence, T. S. Cameron,
A. Linden and R. D. Rogers, J. Chem. Soc., Dalton Trans., 1990,
1521.
13 N. J. Grist, G. Hogarth, S. A. R. Knox, B. R. Lloyd, D. A. V.
Morton and A. G. Orpen, J. Chem. Soc., Chem. Commun., 1988,
673.
14 L. Manojlovic-Muir, M. J. Mays, K. W. Muir and K. W. Woulfe,
J. Chem. Soc., Dalton Trans., 1992, 1531; D. Braga, A. J. M. Caffyn,
M. C. Jennings, M. J. Mays, L. Manojlovic-Muir, P. R. Raithby,
P. Sabatino and K. W. Woulfe, J. Chem. Soc., Chem. Commun., 1989,
1401.
15 M–P–C angles range from 56.3 to 68.7Њ, see for example ref. 13 and
G. M. Dawkins, M. Green, J. C. Jeffery and F. G. A. Stone, J. Chem.
Soc., Chem. Commun., 1980, 1120; G. M. Dawkins, M. Green,
J. C. Jeffery, C. Sambale and F. G. A. Stone, J. Chem. Soc., Dalton
Trans., 1983, 499; J. A. Clucas, M. M. Harding, B. S. Nicholls and
A. K. Smith, J. Chem. Soc., Dalton Trans., 1985, 1835; F. A. Cotton,
J. A. M. Canick, R. L. Luck and K. Vidyasagar, Organometallics,
1991, 10, 352; K.-B. Shiu, S.-W. Jean, H.-J. Wang, S.-L. Wang,
F.-L. Liao, J.-C. Wang and L.-S. Liou, Organometallics, 1997, 16,
114; A. D. Horton, M. J. Mays and P. R. Raithby, J. Chem. Soc.,
Chem. Commun., 1985, 247.
23 S. L. Brock and J. M. Mayer, Inorg. Chem., 1991, 30, 2138.
24 For related M–C᎐C–C᎐O rings see D. Mantlo, J. Suades, F. Dahan
᎐
᎐
and R. Mathieu, Organometallics, 1990, 9, 2933; G. R. Doel,
N. D. Feasey, S. A. R. Knox, A. G. Orpen and J. Webster, J. Chem.
Soc., Chem. Commun., 1986, 542; A. J. P. Domingos, B. F. G.
Johnson, J. Lewis and G. M. Sheldrick, J. Chem. Soc., Chem.
Commun., 1973, 912; F. J. Garcia Alonso, V. Riera, M. A. Ruiz,
A. Tiripicchio and M. Tiripicchio Camellini, Organometallics, 1992,
11, 370; A. J. M. Caffyn, M. J. Mays, G. Conole, M. McPartlin and
H. R. Powell, J. Organomet. Chem., 1992, 436, 83; I. Moldes, J. Ros,
R. Mathieu, X. Solans and M. Font-Bardia, J. Organomet. Chem.,
1992, 423, 65.
25 M. I. Bruce, Chem. Rev., 1991, 91, 197.
26 J. D. King, M. J. Mays, C. -Y. Mo, P. R. Raithby, M. A. Rennie,
G. A. Solan, T. Adatia and G. Conole, J. Organomet. Chem., 2000,
601, 271.
16 J. L. Davidson, J. Chem. Soc., Dalton Trans., 1983, 1667.
17 D. W. J. Cruickshank, J. Chem. Soc., 1961, 5486.
18 D. E. C. Corbridge, Phosphorus: An Outline of its Chemistry,
Biochemistry, and Technology, 3rd edn., Elsevier, Amsterdam, 1985,
ch. 1.
27 W. L. F. Armarego and D. D. Perrin, Purification of Laboratory
Chemicals, Butterworth Heinemann, Oxford, 4th edn., 1996.
28 A. J. Carty, N. K. Hota, T. N. Ng, H. A. Patel and T. J. O’Connor,
Can. J. Chem., 1971, 49, 2706.
19 R. J. Butcher, B. R. Penfold and E. Sinn, J. Chem. Soc., Dalton
Trans., 1979, 668; D. M. Baird, P. E. Fanwick and T. Barwick, Inorg.
Chem., 1985, 24, 3753; F. A. Cotton and R. Poli, Inorg. Chem.,
29 A. C. T. North, D. C. Phillips and F. S. Matthews, Acta Crystallogr.,
Sect. A, 1968, 24, 351.
30 G. M. Sheldrick, SHELXL 93, University of Göttingen, 1993.
J. Chem. Soc., Dalton Trans., 2000, 3331–3339
3339