Metal vapour synthesis of phospha-organometallic compounds via reaction of cobalt atoms with the phospha-alkyne tBuCP: Synthesis and structural characterisation of the sandwich compounds [Co(η5-P3C2tB

Article abstract of DOI:10.1016/S0022-328X(01)01110-X

The reaction of cobalt atoms with ^tBuCP gives the sandwich compounds [Co(η⁵-P₃C₂^tBu ₂)(η⁴-P₂C₂^tBu ₂)] and [Co(η⁵-P₂

Full text of DOI:10.1016/S0022-328X(01)01110-X

Journal of Organometallic Chemistry 635 (2001) 212–221
www.elsevier.com/locate/jorganchem
Metal vapour synthesis of phospha-organometallic compounds via
t
reaction of cobalt atoms with the phospha-alkyne BuCꢀP:
synthesis and structural characterisation of the sandwich
compounds [Co(h5-P3C2tBu2)(h4-P2C2tBu2)],
[Co(h5-P2C3tBu3)(h4-P2C2tBu2)] and the protonated
tetraphospha-barrelene complex [Co(h4-P4C4tBu4H)(h4-P2C2tBu2)],
the latter as its [W(CO)5] adduct
F. Geoffrey N. Cloke *, Peter B. Hitchcock, John F. Nixon *, David M. Vickers
School of Chemistry, Physics and En6ironmental Science, Uni6ersity of Sussex, Brighton, BN1 9QJ, Sussex, UK
Received 11 May 2001; accepted 4 July 2001
This paper is dedicated to the memory of Professor Michael J.S. Dewar, FRS, in recognition of his pioneering theoretical studies concerning
the nature of the bonding between unsaturated hydrocarbons and transition metals. Our metal vapour synthetic route to novel
t
polyphospha-organocobalt(I) complexes, no doubt initially involves an analogous interaction of the phospha-alkyne, BuCꢀP, with the cobalt
centre
Abstract
The reaction of cobalt atoms with tBuCꢀP gives the sandwich compounds [Co(h5-P3C2tBu2)(h4-P2C2tBu2)] and [Co(h5-
P2C3tBu3)(h4-P2C2tBu2)], which have both been structurally characterised by single crystal X-ray diffraction studies. The novel
protonated tetraphospha-barrelene complex [Co(h4-P4C4tBu4H)(h4-P2C2tBu2)] is also formed in the reaction and has been
structurally characterised as its [W(CO)5] adduct. Variable temperature NMR spectra of these complexes are reported and
discussed. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Metal vapour synthesis; Cobalt; Phospha-alkyne; Sandwich compounds
One of the more developed systems involves cy-
clopentadienyl ring anions in which one or more CR
units are replaced by phosphorus atoms, in particular
the 1,3-di- and 1,2,4-tri-phospholyl anions, P2C3tBu3−
and P3C2tBu−2 which show interesting electronic and
co-ordinating properties. Both P2C3tBu3− and P3C2tBu2−
rings can exhibit h5-ligation through their delocalised
6p-aromatic systems and hence can mimic the bonding
of the well-known cyclopentadienyl ligand in the for-
mation of metallocene-like sandwich compounds. A
wide range of such polyphospholyl compounds is now
known, typified by the tetra-phosphametallocenes
[M(P2C3tBu3)2] (M=Sc, Fe, Ni, Pd, Pt, Yb), penta-
1. Introduction
The past decade has seen the rapid development of a
rich new area of organometallic chemistry in which
phosphorus atoms replace CH− fragments in the more
familiar unsaturated organic ligands. There is now an
extensive range of phospha-organometallic compounds
containing phospha-alkynes, phospha-alkenes, phos-
pha-dienes, phospha-allyls, phosphacyclobutadienes,
phosphacyclopentadienyls and phospha-arenes as well
as tetraphosphacubanes and tetraphospha-barrelenes.
The area has recently been comprehensively reviewed
[1–12].
phosphametallocenes
[M%(h5-P3C2tBu2)(h5-P2C3tBu3]
* Corresponding authors.
(M%=V, Cr, Fe, Ru), [M%(h5-P3C2tBu2)(h3-P2C3tBu3]
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01110-X

F.G.N. Cloke et al. / Journal of Organometallic Chemistry 635 (2001) 212–221
213
Fig. 1. Some transition metal P3C2tBu2 and P2C3tBu3 complexes.
(M¦=Ni), and the hexa-phosphametallocenes [M¦(h5-
P3C2tBu2)2] (M¦=Ti, V, Cr, Mn, Fe, Ru) [13–24] (see
Fig. 1). Very recently photoelectron spectroscopic mea-
surements and density functional calculations have re-
vealed details about the electronic structures of
[M(P3C2tBu2)2] (M=Ti, Fe) [25,26].
phacyclobutadiene (P2C2tBu2) ring. Two such com-
pounds which we have previously reported [18,36] are
shown in Fig. 4.
In this paper, we describe new phospha-organometal-
lic products which are formed via the co-condensation
t
reaction of BuCꢀP with cobalt atoms.
Two major synthetic routes have been developed
namely: (i) by treatment of the appropriate metal halide
with the alkali metal salts of the P2C3tBu3− and
P3C2tBu−2 anions; or (ii) via metal vapour synthesis
directly from the appropriate transition metal and the
phosphalkyne PꢀCtBu. The recent synthesis of the pure
potassium salt of the P2C3tBu3 anion, via the remark-
able reaction involving phosphorus extrusion from the
1,3,5 triphosphabenzene P3C3tBu3 on treatment with
potassium [27], offers further synthetic potential for the
former route, while Zenneck and coworkers [28–30]
have recently reported that Ph3SnP3C2tBu2 is also a
useful ring transfer reagent and have used it to synthe-
sise the paramagnetic hexaphosphamanganocene,
[Mn(h5-P3C2tBu2)2], which interestingly has a low spin
2A1 electronic ground state.
2. Results and discussion
Co-condensation of electron beam generated cobalt
t
atoms with an excess of BuCP produces a black petrol-
soluble solid. Chromatographic work up in hexane on
deactivated alumina affords the three compounds 1–3
albeit in very low overall yield (typically 5–10%)
(Scheme 1).
Fig. 2. h5-P3C2tBu2 and h5-P2C3tBu3 complexes of indium (I).
The most commonly occurring rings in co-condensa-
t
tion experiments with BuCꢀP are the 1,3-di- and 1,2,4-
tri-phosphorus analogues of the cyclopentadienyl
ligand P2C3tBu3 and P3C2tBu2. More recently, main
group metal phospholyl derivatives, typified by the
In(I) compounds shown in Fig. 2, have also been
prepared by the MVS approach [31,32] as well as the
[M(h5-P3C2tBu2)2] compounds (M=Sr, Pb, Zn, Cd)
which were made more conventionally directly from the
P3C2tBu−2 anion [33–35].
Co-condensation experiments with transition metal
vapours have also afforded p-complexes in which the
metal is complexed to another ring system as well as the
phosphorus substituted cyclopentadienyl. These include
the novel aromatic phosphirenyl cation (PC2tBu2+) in
[Ni(h5-P3C2tBu2)(h3-PC2tBu2)] [36] and the rarely ob-
served h6-ligated 1,3,5-triphosphabenzene (P3C3tBu3) in
the novel triple decker sandwich compound [(h5-
P3C2tBu2)Sc(m-h6:h6-P3C3tBu3)Sc(h5-P3C2tBu2)] [37] (see
Fig. 3).
Fig. 3. Some mixed-ring phospha-organometallic compounds synthe-
sised via metal vapour synthesis from BuCꢀP.
t
Much less common in the co-condensation reactions
of tBuCꢀP with transition metals are p-complexes solely
containing the 4-membered 2,4-di-tert-butyl-1,3-diphos-
Fig. 4. Homoleptic h4-P2C2tBu2 complexes synthesised via MVS.

214
F.G.N. Cloke et al. / Journal of Organometallic Chemistry 635 (2001) 212–221
rus atoms of the h4-1,3-diphosphacyclobutadiene ring,
which however, showed no resolvable additional inter-
ring coupling perhaps because of line broadening ef-
fects of the quadrupolar cobalt-59 nucleus. Although
the 31P resonance of the h5-P3C2tBu2 ring shows no
temperature dependence, a variable temperature 1H-
NMR spectroscopic study on 1 gave evidence for flux-
ional behaviour in solution. At 348 K the 1H-NMR
spectrum of 1 consists of two sharp singlets correspond-
t
ing to the two types of Bu groups of the P3C2tBu2 and
P2C2tBu2 rings. Cooling the solution causes one of the
singlets to collapse into two signals at l 1.04 and 1.06
ppm, respectively (see Fig. 5) which can be assigned to
t
the two Bu groups of the P2C2tBu2 ring which are in a
t
staggered conformation with respect to the Bu groups
of the P3C2tBu2 ring. The sharp singlet of the P3C2tBu2
ring remains unchanged over this temperature range.
The projection of 1 viewed down the ligand–metal–
ligand axis shown below, reveals the expected staggered
Scheme 1.
t
conformer and the equivalence of both Bu groups of
The red crystalline compound [Co(h5-P3C2tBu2)(h4-
P2C2tBu2)] (1) was isolated by fractional crystallisation
from pentane at −50 °C. The mass spectrum of 1
shows the parent ion at m/z 490 and a base peak at m/z
290 corresponding to M+−(P2C2tBu2).
t
the P3C2tBu2 ring. The two non-equivalent Bu groups
of the P2C2tBu2 ring lie on different sides of the P3C2tBu2
ring. Because the phosphorus atoms of the P2C2tBu2
ring lie on either side of the mirror plane which bisects
the molecule they remain equivalent in the 31P{1H}-
NMR spectrum at all temperatures.
The 31P{1H}-NMR spectrum of 1 gave further struc-
tural information, consisting of: (i) a doublet and a
triplet (lA 102.2 ppm, lB 99.0 ppm, J(PP)=44.8 Hz)
2
representing the [AB2] spin system of the 1,2,4-triphos-
phacyclopentadienyl ring (the PB resonance exhibiting
further small doublet coupling 2J(PP)=8.1 Hz from
coupling to the two phosphorus atoms of the 1,3-
diphosphacyclobutadiene ring; and (ii) a broad singlet
(l 60.9 ppm) attributed to the two equivalent phospho-
Fig. 5. Variable temperature 1H-NMR spectra of 1 showing the Bu resonance of the h4-ligated 1,3-P2C2tBu2 ring.
t

F.G.N. Cloke et al. / Journal of Organometallic Chemistry 635 (2001) 212–221
215
the same as those reported for [Co(h5-C5Me5)(h4-
t
,
P2C2Bu2)] (CoꢁP bond lengths 2.24 and 2.25 A and
,
CoꢁC bond lengths 2.09 and 2.08 A, respectively) [39]
indicating that replacement of the pentamethylcy-
clopentadienyl ring with a triphosphacyclopentadienyl
ring has very little effect upon the overall molecular
geometry. The 1,3-diphosphacyclobutadiene ring un-
dergoes the expected rhomboidal distortions with an
average PꢁCꢁP angle of 98.6° and an average CꢁPꢁC
angle of 81.3°.
The identity of the red crystalline compound [Co(h5-
P2C3tBu3)(h4-P2C2tBu2)] (2) was readily predicted on the
basis of mass spectroscopic data. A strong molecular
ion is observed at m/z 528 amu (70% intensity) and the
expected fragmentation patterns were observed: viz.
m/z 390 (50%) [M+−tBuCC tBu], m/z 328 (32%) [M+
Fig. 6. Molecular structure of [Co(h5-P3C2tBu2)(h4-P2C2tBu2)] (1).
1
−P2C2tBu2] and 290 (100%) [M+−P2C3tBu3]. The H-
NMR spectrum of 2 consists of the expected three
singlets in a 2:1:2 ratio which is consistent with a
staggered conformation of the rings with respect to the
tert-butyl groups. The 31P{1H}-NMR spectrum of 2 is
simple consisting of two singlets. No inter-ring coupling
is observed and the lines appear broad owing to the
close proximity of the cobalt nucleus. The availability
of only a very small quantity of material precluded
recording a meaningful 13C{1H}-NMR spectrum. A
single crystal X-ray diffraction study of 2 confirmed the
expected sandwich structure shown in Fig. 7. As in
complex 1 the two rings lie essentially parallel to one
another, with a dihedral angle of 5.9°. As expected,
steric repulsions between the tert-butyl groups of the
two different rings cause the molecule to adopt the
staggered configuration. Bond lengths around the 1,3-
diphosphacyclobutadiene ring in 2 are essentially identi-
cal, indicative of a fully delocalised ring system. The
13C{1H}-NMR spectroscopic data for 1 are also fully
consistent with the proposed staggered conformation.
The two ring quaternary carbons of the P3C2tBu2 ring
give rise to one signal, however, the quaternary carbons
of the P2C2tBu2 ring are present as two distinct triplets
1
(l 116.6 and 120.3 ppm, JPꢁC=54.6 and 57.0 Hz) and
t
this behaviour is also repeated by the Bu quaternary
t
and Bu methyl carbon resonances for both rings. The
resonances of the quaternary carbons for both rings
give rise to the expected splitting patterns. The P3C2tBu2
ring carbons appear as the A part of an [AMXY] spin
system {X−, Y and M are the ring phosphorus atoms
of the P3C2tBu2 ring in the 1, 2 and 4 positions, respec-
tively} and the spectrum has been successfully simu-
lated (lA 166.8 ppm, JAM=80.3 Hz, JAX+JAY=100
Hz).
A single crystal X-ray crystallographic structural de-
termination of 1 was carried out and the molecular
structure is shown in Fig. 6. The structure confirms that
the complex contains a central cobalt atom sandwiched
between an h5-1,3,4-triphosphacyclopentadienyl ring
and an h4-1,3-diphosphacyclobutadiene ring. Both
rings lie essentially parallel to each other (dihedral
angle 3.1°). Bond lengths within the P2C2tBu2 ring of 1
,
average CꢁP bond length of 1.78 A is similar to that of
5
,
1 and to the reported value of 1.80 A for [Co(h -
C5Me5)(h4-P2C2tBu2)] [38]. Similarities between com-
pounds 1 and 2 also exist with respect to both CoꢁC
and CoꢁP distances and also in the rhomboidal distor-
tion angles within the P2C2tBu2 ring.
The third product 3 from the co-condensation reac-
t
,
are essentially identical, ranging from 1.778 to 1.798 A,
tion of cobalt atoms with BuCꢀP was a purple–red oil,
consistent with a fully delocalised ring system similar to
that previously observed in the complex [Co(h5-
C5R5)(h4-P2C2tBu2)] (R=H, Me) [38,39] but very dif-
ferent from the long-(1.820) short-(1.748) long-(1.836)
after chromatographic work up of the crude product,
which could not be successfully isolated in a pure form.
Mass spectra data, however, showed the major sub-
limable component had the formula ‘Co(tBuCP)6H’
from the observation of the a parent ion peak at m/z
660 amu. No successful interpretation of the fragmenta-
tion pattern could be made and although extensive
NMR spectroscopic studies were undertaken structural
interpretations were ambiguous. However, subsequent
derivatisation of 3 by treatment with [W(CO)5THF]
(Fig. 8), readily led to its characterisation as the purple
crystalline [W(CO)5] adduct 4. We have previously suc-
cessfully applied this technique of adding a [W(CO)5]
,
short-(1.749 A) PꢁC distances which are exhibited by
[Ti(h8-C8H8)(h4-P2C2tBu2)] [40]. In the latter complex
the localised 1,3-diphosphacyclo-butadiene ring exhibits
a marked shift to higher frequency of l 213 ppm in
sharp contrast to the value of l 60.9 ppm observed for
the delocalised ring in complex 1.
The metal to phosphorus bond lengths of 2.26 and
,
2.25 A and metal to carbon bond lengths of 2.09 and
,
2.13 A in the four-membered ring of 1 are essentially

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F.G.N. Cloke et al. / Journal of Organometallic Chemistry 635 (2001) 212–221
Fig. 7. Molecular structure of [Co(h5-P2C3tBu3)(h4-P2C2tBu2)] (2).
fragment to afford crystalline material in the structural
characterisation of the phosphirenyl cationic complex
[Ni(h5-P3C2tBu2)(h3-PC2tBu2)] [36].
The resulting single crystal X-ray diffraction study on
4 (see Fig. 9) established that 3 is [Co(h4-P4C4tBu4H)-
(h4-P2C2tBu2)], containing the novel protonated 1,3,5,7-
tetraphosphabarrelene (Fig. 9a).
respectively. Steric strain around the [W(CO)5] unit is
also apparent with cis CO ligands bending away from
idealised octahedral geometry by 6° from the rest of the
molecule. Interestingly a reduction in the rhomboidal
distortion of the (P2C2tBu2) ring is observed compared
with 1 and 2. Average CPC and PCP ring angles in 4
are closer to 90° (84.1 and 96.1°, respectively, cf. 1 and
2 81.3 and 98.6° (for 1) and 81.2 and 98.8° (for 2).
Compounds 3 and 4 represent rare examples of com-
plexes containing the protonated form of the 1,3,5,7-te-
traphosphabarrelene ligand. Recently Binger et al.
[41,42] obtained zirconium(0) and hafnium(0) com-
h1-Ligation of the [W(CO)5] fragment is to the
P2C2tBu2 ring rather than to the more sterically encum-
bered protonated 1,3,5,7-tetraphospha-barrelene ligand.
The H atom in the PꢁH bond, was successfully located
on a difference map and refined isotropically as part of
the overall crystal structure determination. Both ligands
relieve steric strain within the molecule by adopting a
staggered conformation and the [W(CO)5] fragment
causes a slight twist of the P2C2tBu2 ring relative to the
plane described by P3, P4 and H3.
Although no comparable structural data exist for
1,3,5,7-tetraphosphabarrelene complexes, the geometry
around the P2C2tBu2 ring gives some information on
this ligand relative to cyclopentadienyl and phosphorus
substituted cyclopentadienyl ligands in both 1 and 2
and [Co(h5-C5Me5)(h4-P2C2tBu2)] [39]. The CoꢁC and
CoꢁP bond lengths within the h4-P2C2tBu2 ring in 4 lie
Fig. 8. Preferential ligation of [W(CO)5] to the h4-ligated 1,3-P2C2tBu2
ring of 3.
,
within the expected ranges 2.09–2.03 and 2.25–2.26 A,

F.G.N. Cloke et al. / Journal of Organometallic Chemistry 635 (2001) 212–221
217
The 31P-NMR spectrum contains a doublet of the
1
same JPꢁH coupling at l −31.6 ppm which in the
proton-decoupled 31P-NMR spectrum reverts to a sin-
glet. The 31P{1H}-NMR spectrum of 4 contains six
separate signals reflecting the low overall symmetry of
the complex. NMR evidence was obtained of rapid
exchange of the two pairs of tert-butyl groups at room
temperature. Unfortunately quadrupolar effects of the
cobalt-59 nucleus results in broad 31P line widths and
precluded any determination of PꢁP coupling constants.
Some structural information can be obtained, however,
from the pseudo quartet observed at l 421.8 ppm,
strongly characteristic of the 1,3,5,7-tetraphosphabarre-
lene ligand, which is assigned to the apical phosphorus
atom P4. Likewise the doublet at l 26.3 ppm clearly
exhibits tungsten satellites (1JPW=214.5 Hz). The free
rotation of the 1,3,5,7-tetraphosphabarrelene and 1,3-
diphosphacyclobutadiene ligands at room temperature,
may be stopped at low temperature.
2.1. Preparation of
[Co(p4-P2C2tBu2W(CO)5)(p5-P3C2tBu2)] (5)
Fig. 9. Molecular structure of [Co(h4-P4C4tBu4H)(h4-P2C2tBu2)-
(W(CO)5)], 4.
Treatment of 1 with [W(CO)5THF] in THF solution
(Fig. 12) yields a dark oil. Chromatographic work-up
on deactivated alumina with hexane eluant affords a
red crystalline solid which mass spectroscopic data
show to be [Co(h4-P2C2tBu2W(CO)5)(h5-P3C2tBu2)] (5).
The mass ion for 5 at m/z 814 amu shows the
expected isotopic ratios and also shows losses of 28
amu corresponding to sequential loss of five CO
molecules from the parent ion. The expected site of
ligation to the [W(CO)5] fragment [1,2], namely via one
of the PꢁP bonded phosphorus atoms of the P3C2tBu2
ring did not occur, instead the metal bonds to one of
the P atoms of the 1,3-diphosphacyclobutadiene ring.
This is clearly shown by the 31P{1H}-NMR spectrum of
5, shown in Fig. 13, which consists of four resonances:
the doublet and triplet representing the three phospho-
rus atoms of the P3C2tBu2 ring and two separate singlets
at l 20.1 and 53.0 ppm for the two phosphorus atoms
of the P2C2tBu2 ring only the latter resonance showing
183W satellites (1JPꢁW=226.7 Hz). Several examples are
known of secondary h1-ligation of complexes contain-
ing h1-bonded 1,3-diphosphacyclobutadiene rings to
transition metal centres [43–46].
Fig. 10. 1,3,5,7-Tetraphosphabarrelene complexes of zerovalent Zr
and Hf.
plexes of 1,3,5,7-tetraphosphabarrelene, [M(h8-C8H8)-
(tBu4C4P4] (M=Zr, Hf), shown in Fig. 10, by treat-
ment of the corresponding cyclo-octatetraene com-
plexes [M(h8-C8H8)2] (M=Zr, Hf) with tBuCꢀP.
Subsequent reaction of these compounds with hex-
achloroethane yields the uncoordinated 1,3,5,7-tetra-
phosphabarrelene, which has also been fully struc-
turally characterised.
1
1
The solution H-NMR spectrum of 4 at room tem-
The H-NMR spectrum of 5 consists of two singlets
perature was in accord with the solid state structure,
giving the expected four singlets in a 2:1:2:1 ratio for
the four different types of tert-butyl groups and most
significantly a doublet of relative intensity 1 at l 7.80
ppm attributable to a PꢁH hydrogen (1JPꢁH=454.4
and remain unchanged on cooling the solution, suggest-
ing either rapid ring rotation or a symmetrical structure
containing a mirror plane.
1
Hz). At 253 K the H-NMR spectrum, in the tert-butyl
3. Experimental
region (Fig. 11), consists of six singlets indicative of a
molecular conformation of very low symmetry in which
all the tert-butyl groups become non-equivalent.
All manipulations, unless otherwise stated, were con-
ducted in an inert atmosphere of Ar or dinitrogen using

218
F.G.N. Cloke et al. / Journal of Organometallic Chemistry 635 (2001) 212–221
Fig. 11. Variable temperature 1H-NMR spectra of 4.

F.G.N. Cloke et al. / Journal of Organometallic Chemistry 635 (2001) 212–221
219
impact (EI) mass spectra were recorded in a Kratos
MS80RF instrument in the School of Chemistry at the
University of Sussex by Dr A. Abdul-Sada. Micro-
analyses were performed by Medac Ltd (UK) or Cana-
dian Microanalytical Services Ltd (Canada).
t
3.1. Reaction of cobalt atoms with BuCP
Fig. 12. Reaction of 1 with [W(CO)5THF].
Co-condensation at 77 K of electron beam vaporised
(500 W) cobalt (0.96 g, 16 mmol) with an excess of
tBuCP over 2 h resulted in the formation of a deep red
matrix which was allowed to warm to room tempera-
ture under vacuum. The apparatus was then opened to
a dual vacuum/Ar (or dinitrogen) line, employing con-
ventional Schlenk line techniques, or by use of either a
Miller–Howe or mBraun glove box under an atmo-
sphere of dinitrogen. Solvents were pre-dried by distilla-
tion under dinitrogen over the appropriate drying agent
and subsequently degassed and stored in glass am-
poules under Ar in the presence of a sodium (or potas-
sium) mirror. All glassware, cannulae and Celite were
stored in an oven (\373 K) and glassware and Celite
were flame-dried in vacuo immediately prior to use.
Cobalt for the electrongun vaporisation MVS experi-
ment was degassed prior to use. Deuteriated solvents
were purchased from M.S.D. Isotopes, Ltd. and Goss
Scientific. They were degassed by the freeze–thaw
method, refluxed in vacuo over molten potassium or
sodium (according to boiling point) and then vacuum
transferred to a glass ampoule fitted with a Young’s tap
prior to storage in the glove box. Solution NMR spec-
tra were recorded on Bru¨ker ACP250, WM360,
DMX300, DMX400 or AMX500 instruments at ambi-
ent temperature unless otherwise stated. Coupling con-
stants are given in Hz, and chemical shift (l) in ppm is
relative to the residual proton chemical shift of the
deuteriated solvent (1H), the carbon chemical shift of
the deuteriated solvent (13C), and H3PO4 (31P). Electron
t
an external trapping system and unreacted BuCP was
collected in an external trap at 77 K. After 4 h the
reaction vessel was refilled with dinitrogen and the
matrix washed into a Schlenk receiver with petrol (40–
60). The crude reaction mixture was then filtered
through a flame-dried bed of Celite to remove colloidal
metal and solvent removed in vacuo. The resultant
black solid yielded three products following chromato-
graphic workup (deactivated alumina {4% m/m H2O},
petrol eluant). The primary fraction (red band) yielded
two compounds [Co(h5-P3C2tBu2)(h4-P2C2tBu2)] (1) and
[Co(h5-P2C3tBu3)(h4-P2C2tBu2)]
(2),
subsequently
purified by fractional crystallisation. In order to obtain
sufficient quantities of material, the chromatographic
stages of the preparation were repeated up to five times.
1: MS (70 eV); 490 (100, [M+]), 290 (63, [M+−
(P2C2tBu2)])
1H-NMR (d8-toluene) {298 K}: l=1.02 (s, 18H,
t
tBu), 1.48 (s, 18H, Bu), {−35 °C}: l=1.04 (s, 9H,
t
t
tBu), 1.06 (s, 9H, Bu), 1.51 (s, 18H, Bu). 31P{1H}-
NMR (d8-toluene) {−35 °C}: l=60.9 (s, PC), 99.0
Fig. 13. The 31P{1H}-NMR spectra of 1 and 5.

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F.G.N. Cloke et al. / Journal of Organometallic Chemistry 635 (2001) 212–221
2
2
1
(dt, J(PP)=44.8 Hz, J(PP)=8.1 Hz, PB), 102.2 (t,
2J(PP)=44.8 Hz PA). 13C{1H}-NMR (d8-toluene) {−
30 °C}: l=32.0 (s, C3H3), 32.7 (s, C3H3), 35.6 (t,
26.3 (m, J(PW)=214.5 Hz, P2), 28.1 (s, P1), 421.8 (m,
P4).
31P-NMR (d8-toluene) {253 K}: l= −157.5 (m, P5
or P6), −144.4 (m, P5 or P6), −31.6 (d, J(PH)=
454.4 Hz, P3), 26.3 (m, J(PW)=214.5 Hz, P2), 28.1 (s,
2J(CP)=7.05 Hz, C2), 36.2 (t, J(CP)=6.6 Hz, C2),
2
1
36.7 (s, C6H3), 39.7 (a part of AMXX’ spin system,
1
J
AM=17.5 Hz, JAX+JAX%=26.0 Hz, C5), 116.5 (t,
P1), 421.8 (m, P4).
1J(CP)=54.6 Hz, C1), 120.2 (t, J(CP)=57.0 Hz, C1),
MS (70 eV); 984 (5, [M+]), 956(3, [M+−CO]), 660
(20, [M+−W(CO)5]). Anal. Found: C 42.86, H 5.54;
Calc. for C 42.7, H 5.6%.
1
166.83 (a part of AMXY spin system JAM=80.3 Hz,
J
AX+JAY=100 Hz, C4). Anal. Found: C, 49.24; H,
7.25; Calc. for C, 48.99; H, 7.40%.
3.3. Reaction of [Co(p5-P3C2tBu2)(p4-P2C2tBu2)] with
[W(CO)5THF]
To [W(CO)5THF] generated in situ from [W(CO)6]
(0.10 g) in THF (25 ml) was added a THF solution of
[Co(h5-P3C2tBu2)(h4-P2C2tBu2)] (1) (60 mg, 0.12 mmol)
and the mixture stirred for 4 h. The solvent was re-
moved in vacuo to yield a red solid. Extraction of the
oil into petrol (40–60) followed by chromatographic
work up on Kieselgel 60 GF254 with petrol (40–60) as
eluant, afforded [Co(h5-P3C2tBu2)(h4-P2C2tBu2W(CO)5)]
(5) as a micro-crystalline powder on removal of solvent.
Recrystallisation from pentane (−50 °C) afforded red
crystals.
2: MS (70 eV); 528 (65, [M+]), 390 (50, [M+−2tBu]),
328 (32, [M+−(P2C2tBu2]), 290 (100, [M+−2tBu−
(PCtBu)]).
1H-NMR (d6-benzene) {298 K}: l=1.28 (s, 18H,
t
t
tBu), 1.56 (s, 9H, Bu), 1.63 (s, 18H, Bu). 31P{1H}-
NMR (d6-benzene): l=46.6 (s), 60.3 (s).
3: Red oil. Attempts at purification by recrystallisa-
tion, sublimation (10−6 mbar 20–200 °C) and column
chromatography were unsuccessful. Interpretation of
complex data is inferred by analysis of characterising
data of derivatives (vide infra).
MS (70 eV); 814 (7, [M+]), 758 (2, [M+−2CO]), 730
(4, [M+−3CO]), 674 (4, [M+−5CO]), 490 (100, [M+
−W(CO)5]).
1H-NMR (d8-toluene), {298 K}: l=1.07 (s 18H,
t
tBu), 1.44 (s, 18H, Bu).
31P{1H}-NMR (d8-toluene), {298 K}: l=20.1 (s,
1
2
PD), 53.0 (s, J(PW)=227 Hz, PC), 102.7 (d, J(PP)=
MS 70 eV; 660 (30, [Co(Me3CCP)6H]+).
42.8 Hz, PB), 108.2 (t, J(PP)=42.8 Hz, PA).
2
31P{1H}-NMR (d6-benzene): l= −148 (m), −34.5
(m), 59.4 (m).
3.2. Reaction of [Co(tBuCP)6H] (3) with [W(CO)5THF]
4. Crystallography
To [W(CO)5THF] generated in situ from [W(CO)6]
(0.10 g) in THF (25 ml) was added a THF solution of
[Co(tBuCP)6H] (3) (approximately 0.03 g) and the mix-
ture stirred for 4 h. The solvent was removed in vacuo
to yield a dark red oil. Extraction of the oil into petrol
(40–60) followed by chromatographic work up on
Kieselgel 60 GF254 with petrol (40–60) as eluant af-
forded [Co(tBuCP)6H(W(CO)5] (4) as a micro-crys-
talline powder on removal of solvent. Recrystallisation
from pentane (−50 °C) afforded analytically pure
red–purple crystals. (0.025 g, 60%), which were suitable
for an X-ray crystal structure determination.
Intensity data were measured on an Enraf–Nonius
CAD4 using Mo–Ka radiation.
Crystal data for 1: C20H36P5Co, M=490.3, mono-
clinic, space group P2I/c (no. 14), a=10.428(3), b=
,
11.846(3),
c=19.778(4)
A,
i=95.95(2)°,
3
,
V=2430.0(11) A , T=173(2) K, Z=4, v=1.039
mm−1, u=0.71073 A, F(000) 1032; 4516 reflections
,
collected, 4276 independent (Rint=0.0601), 3094 reflec-
tions with I\2|I, R1=0.0760, wR2=0.1953; R1=
0.1062, wR2=0.2227 for all data.
Crystal data for 2: C25H45P4Co, M=528.5, mono-
clinic, space group P2I/c (no. 14), a=14.152(4), b=
1H-NMR (d8-toluene) {298 K}: l=1.14 (s, 18H,
10.902(3), c=18.527(11) A, i=103.46(3)°, V=2780(2)
,
t
t
3
tBu), 1.24 (s, 9H, Bu), 1.30 (s, 18H, Bu), 1.50 (s, 9H,
A , T=173(2) K, Z=4, u=0.71073 A, F(000)
1128.5365 reflections collected, 5166 independent
(Rint=0.02), 3655 reflections with I\2|I, R1=0.045,
wR2=0.091 for I\2|I, R1=0.054, R1=0.061.
,
,
tBu), 7.80 (d, 1J(P,H)=454.4 Hz, HꢁP). {253 K}:
t
t
l=1.13 (s, 9H, Bu), 1.15 (s, 9H, Bu), 1.20 (s, 9H,
t
t
tBu), 1.33 (s, 9H, Bu), 1.35 (s, 9H, Bu), 1.53 (s, 9H,
tBu).
Crystal data for 3: C35H55O5P6CoW, M=984.4,
monoclinic, space group P2I/n (non-standard. 14), a=
31P{1H}-NMR (d8-toluene) {253 K}: l= −157.5
(m, P5 or P6), −144.4 (m, P5 or P6), −31.6 (m, P3),
,
12.903(2), b=19.556(4), c=16.651(5) A, i=91.52(2)°,

F.G.N. Cloke et al. / Journal of Organometallic Chemistry 635 (2001) 212–221
−1
221
3
[19] P.L. Arnold, F.G.N. Cloke, J.F. Nixon, J. Chem. Soc. Chem.
Commun. (1998) 797.
,
V=4200(2) A , T=173(2) K, Z=4, v=3.40 mm
,
,
u=0.71073 A, F(000) 1984; 7712 reflections collected,
7373 independent (Rint=0.0345), 5830 reflections with
I\2|I, R1=0.040, wR2=0.087; R1=0.061, wR2=
0.096 for all data.
[20] F.G.N. Cloke, K.R. Flower, P.B. Hitchcock, J.F. Nixon, J.
Chem. Soc. Chem. Commun. (1995) 1659.
[21] F.G.N. Cloke, K.R. Flower, J.F. Nixon, D. Vickers, unpub-
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Soc. Chem. Commun. (1999) 1731.
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J. Organomet. Chem. 487 (1995) C21.
[24] D.J. Wilson, PhD Thesis, University of Sussex, Sussex, UK,
1999.
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 162997, 162998 and 162999
for compounds 1, 2 and 3, respectively. 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
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We thank the EPSRC for their support for this work.
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