Bidentate metalloligands containing the phosphinocyclopentadienyl ligand. New heterobimetallic complexes and crystal structure of (C5Me5)(C5H4PPh 2)Ta(CO)(μ-PPh2)Cr(CO)4

Article abstract of DOI:10.1039/a903603b

Four new kinds of metalloligands Cp*(C₅H₄PPh₂)TaL_n [L_n = (H)₃, (H)(CO), (H)₂(PPh₂), (CO)(PPh₂)] 2, 3, 4b, 5b containing the diphenylphosphinocyclopentadienyl ligand have been prepared and characterized. The trihydride complex 2 was obtained by reduction of the dichloride compound Cp*(C₅H₄PPh₂)TaCl₂ 1. Treatment of 2 under a CO atmosphere at 140°C in decane affords the monohydride complex 3. Compounds 2 and 3 easily react with chlorophosphines leading to phosphido derivatives 4b and 5b respectively. All these metalloligands act as monodentate and/or chelating bidentate ligands. Their reactivity toward unsaturated organometallic fragments [M′(CO)₅] or [M′(CO)₄] (M′ = Cr, W) has been studied. The X-ray crystal structure of Cp*(C₅H₄PPh₂)Ta(CO)(μ-PPh ₂)Cr(CO)₄ 10Cr is reported.

Full text of DOI:10.1039/a903603b

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Bidentate metalloligands containing the phosphinocyclopentadienyl
ligand. New heterobimetallic complexes and crystal structure of
(C5Me5)(C5H4PPh2)Ta(CO)(ꢀ-PPh2)Cr(CO)4
Cyril Poulard, Gilles Boni, Philippe Richard and Claude Moïse*
Laboratoire de Synthèse et d’Electrosynthèse Organométalliques (LSEO - UMR CNRS 5632),
Faculté des Sciences Gabriel, 6 Bd Gabriel, 21000 Dijon, France.
E-mail: claude.moise@u-bourgogne.fr
Received 6th May 1999, Accepted 30th June 1999
Four new kinds of metalloligands Cp*(C5H4PPh2)TaLn [Ln = (H)3, (H)(CO), (H)2(PPh2), (CO)(PPh2)] 2, 3, 4b,
5b containing the diphenylphosphinocyclopentadienyl ligand have been prepared and characterized. The
trihydride complex 2 was obtained by reduction of the dichloride compound Cp*(C5H4PPh2)TaCl2 1. Treatment
of 2 under a CO atmosphere at 140 ЊC in decane affords the monohydride complex 3. Compounds 2 and 3 easily
react with chlorophosphines leading to phosphido derivatives 4b and 5b respectively. All these metalloligands
act as monodentate and/or chelating bidentate ligands. Their reactivity toward unsaturated organometallic
fragments [MЈ(CO)5] or [MЈ(CO)4] (MЈ = Cr, W) has been studied. The X-ray crystal structure of
Cp*(C5H4PPh2)Ta(CO)(µ-PPh2)Cr(CO)4 10Cr is reported.
The study of heterobimetallic complexes is of great interest in
the main fields of the application of organometallic chemistry,
namely catalysis.1 Part of the increasing interest in this research
is the hope that such heterobimetallic structures might
exhibit unusual catalytic activity due to a cooperative reactivity
between electron-deficient and electron-rich metals.2
Bridging ligands have been widely developed to maintain the
two metal sites in a close proximity and to prevent breaking
of the bimetallic framework. Among these linking ligands,
the heterodifunctional diphenylphosphinocyclopentadienyl has
received significant attention in the last few years and numerous
examples of its ability to join two different metallic centers have
been reported.3
In the course of our work on binuclear complexes, we have
already reported various hydrido and/or phosphido bridged
systems. A series of bimetallic polyhydrides4 and of µ-hydrido
µ-phosphido cyclic structures5 has been obtained which prove
hydrido and phosphido bridges to be efficient in tying two
metal centers.
Scheme 1
spectrum characteristic of bis(cyclopentadienyl) tantalum()
derivatives.7 Treatment of 1 with NaAl(H)2(OCH2CH2OMe)2
in toluene over a period of three hours affords a red solu-
tion which, on hydrolysis, gives the trihydride metallocene 2.
Heating of 2 in decane under an atmosphere of carbon
monoxide leads to the purple carbonyl derivative 3 (Scheme 2).
In this paper, we report on the combination of the coordin-
ating ability of a diphenylphosphinocyclopentadienyl ligand
and that of a terminal phosphido or a hydrido functionality in
the synthesis of new bimetallic tantalum–chromium and
tantalum–tungsten complexes. The synthesis of the bidentate
metalloligands proceeds in two main steps: firstly the
diphenylphosphinocyclopentadienyl ligand is involved in the
preparation of a Cp-phosphino functionalised tantalocene
dichloride. Then, the hydrido or phosphino coordination site
is introduced on the tantalum center by chemical transform-
ations. The X-ray crystal structure of a tantalum–chromium
compound is reported.
Scheme 2 (i) NaAl(H)2(OCH2CH2OMe)2, toluene; (ii) CO, decane,
130 ЊC.
1
The H NMR spectrum of 2 exhibits, in the region of the
metal hydrides, a doublet of triplets and a doublet of doublets
[J(H–H) = 11.2 Hz, J(P–H) = 1.9 Hz; J(H–H) = 11.2 Hz,
J(P–H) = 5.9 Hz] corresponding to the central and lateral
hydrides respectively. Noteworthy for the monohydride com-
plex 3 is the doublet resonance at δ Ϫ5.9 [J(P–H) = 5.8 Hz] as
well as the νCO absorption at 1882 cmϪ1.
The reaction of the trihydride 2 with PPh2Cl in toluene
results in the rapid insertion of the chlorophosphine into the
central Ta–H bond affording quantitatively the ionic com-
Results and discussion
The synthesis of complex 1 Cp*(C5H4PPh2)TaCl2 is adapted
from Bercaw’s method6 as outlined in Scheme 1.
Complex 1 is isolated in good yield (95%) as a green solid
soluble in halogenated solvents. It displays the eight-line ESR
J. Chem. Soc., Dalton Trans., 1999, 2725–2730
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plex [Cp*(C5H4PPh2)Ta(H)2(PPh2H)]ϩClϪ 4a as depicted in
Scheme 3.5,8 Complex 4a is very sparingly soluble in hydro-
material 2 indicating the presence of a tungsten coordinated
phosphorus. The IR spectrum in thf solution shows the
expected three νCO bands for the monosubstituted octahedral
W(CO)5 moiety.
When exposed to MЈ(CO)4L2 fragments (MЈ = Cr, L2 = nbd ;
MЈ = W, L = MeCN), the trihydride complex 2 behaves as a
bidentate ligand through the hydrogen and phosphorus atoms,
leading to the substitution of L2 ligands with formation of cyclic
compounds Cp*(C5H4PPh2)Ta(H)2(µ-H)MЈ(CO)4 7(Cr,W).
Very characteristic of these structures is the bridging central
hydride resonance which exhibits a high-field signal.5 As for
complex 6, the deshielded 31P resonance is indicative of the
coordinated phosphorus. The IR spectra of 7(Cr,W) show the
typical four band pattern of the cis-MЈ(CO)4 fragments.
A photochemical process was carried out in order to convert
complex 6W to the cyclic compound 7W. Surprisingly this
attempt did not lead to the expected complex since the
reaction product is the tantalum() derivative Cp*-
Scheme 3
carbon and aromatic solvents. However, it is sufficiently soluble
in acetone to allow NMR spectra to be recorded. The 1H NMR
spectrum exhibits a unique resonance for the two Ta–H protons
(doublet of doublets of doublets) indicative of the central
position of the PPh2H group. The hydrogen signal of the P–H
bond is displayed as a doublet of triplets at δ 7.8 [J(H–H) =
4.9 Hz, J(P–H) = 393 Hz]. Notably, no exchange process with
the phosphorus of the cyclopentadienyl ring is detected. This
trend confirms previous observations on the enhanced basicity
of a metal-bonded phosphido group with respect to a classical
organic phosphine.9 The salt 4a is quantitatively deprotonated
by sodium hydroxide leading to the corresponding dihydride
phosphido complex Cp*(C5H4PPh2)Ta(H)2(PPh2) 4b. The form-
ation of the phosphido derivative 4b rather than the phosphino
one suggests that the P–H bond is a more acidic site than the
Ta–H bond.
According to a procedure previously described, the carbonyl
monohydride Cp*(C5H4PPh2)TaH(CO) 3 quickly reacts with
chlorodiphenylphosphine.10 In a first step, the metallophos-
phonium salt [Cp*(C5H4PPh2)Ta(CO)(PPh2H)]ϩClϪ 5a is
formed, probably by a nucleophilic substitution at the phos-
phorus atom followed by Hϩ transfer onto the basic
phosphorus center; deprotonation of this salt is achieved by
hydroxide anion and leads to the corresponding neutral phos-
phido derivative Cp*(C5H4PPh2)Ta(CO)(PPh2) 5b (Scheme 4).
(C5H4PPh2)Ta(CO)(µ-H)W(CO)4 8aW which results from the
migration of a carbon monoxide fragment to the Ta center.
The structure of this complex is proposed on the basis of IR,
1H and 31P NMR data. The 1H NMR spectrum of 8aW shows a
unique shielded hydride resonance at δ Ϫ15.0 [J(H–W) = 40
Hz] characteristic of a hydrido bridge. The tungsten coordin-
ated phosphorus is evidenced by the 31P NMR singlet resonance
at δ 8.2 [J(P–W) = 226 Hz]. The IR spectrum of 8aW exhibits
five CO absorptions: four attributed to the cis disubstituted
[W(CO)4] fragment and one for the tantalum coordinated
carbonyl.
In a similar way, the reactivity of 3 was investigated. When
opposed to [W(CO)5], the monohydride 3 leads to a mixture of
the phosphido linked complex 8bW and the cyclic structure
8aW. The formation of the hydrido bridge in 8aW results from
an easy loss of one CO ligand at the tungsten site.
Unfortunately, complexes 8aW and 8bW are not separable
from their mixture either by crystallisation or by column
chromatography. However, when monohydride 3 is reacted with
the [W(CO)4] moiety, the cyclic structure 8aW is obtained as
the sole product.
The metalloligands 4b and 5b combine the coordinating
abilities of a metallophosphine with those of an organic phos-
phine. Toward [MЈ(CO)4] moieties, they behave as chelating
ligands affording two types of Ta() 9Cr or Ta() 10(Cr,W)
heterobimetallic systems (Scheme 6).
The formation of of 9Cr and 10(Cr,W) is ascertained by the
noticeable deshielding found for the 31P resonances with respect
to that observed in the parent metallodiphosphines. Further-
more, in the two chromium derivatives 9Cr and 10Cr, the low
field signals fall in the same range (δ 59.7 and 65.5 respect-
ively) and therefore can be attributed to the phosphorus nuclei
of the CpPPh2 ligand. In 9Cr and 10W, the weak J(P–P) value
(10 Hz) is indicative of a cis configuration for the two phos-
phorus nuclei.11 As expected, the two 31P resonances of 10W
are surrounded by the 183W satellites [J(P–W) = 249 Hz and
J(P–W) = 151 Hz]. No coupling effect between the two phos-
phorus atoms is detected in 10Cr. The crystal structure of the
bimetallic complex 10Cr is shown in Fig. 1. The compound
crystallized with two chloroform solvate molecules. Selected
bond lengths and bond angles are reported in Table 1. The
structure consists of two fragments: a tantalocene moiety
linked to a chromium-carbonyl unit by two phosphorus atoms
leading to a five membered chelate ring. The same structural
features were reported for the Re, Rh diphosphido bridged
Scheme 4
The four previous kinds of metalloligand derivatives (2, 3,
4b, 5b) are able to act as monodentate and/or chelating biden-
tate ligands. The trihydride complex Cp*(C5H4PPh2)Ta(H)3 2
may bond to other metal fragments in different ways, through
phosphorus or through both hydrogen and phosphorus. In
order to check its coordinating abilities, complex 2 was reacted
with the tungsten pentacarbonyl fragment [W(CO)5]. The
reaction proceeds at room temperature over a period of 20
complex (PPh3)(C5H4PPh2)Re(NO)(µ-PPh2)Rh(nbd).12 In both
cases the five membered ring adopts a similar distorted “envel-
ope” conformation13 the tantalum atom and the ipso-cyclo-
pentadienyl carbon C(1) lying 0.207 Å and 0.664 Å below
the P(1)–Cr–P(2) plane. The structural parameters of the
tantalocene moiety are similar to those reported for several
min, affording Cp*(C5H4PPh2)Ta(H)3W(CO)5 6 (Scheme 5).
The structure of this complex was determined by a combin-
ation of elemental analysis, IR and NMR spectral data. The
31P NMR spectrum shows a deshielded resonance [δ = 16.1;
J(W–P) = 256 Hz] with respect to that observed for the starting
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Scheme 5
Table 1 Selected bond distances (Å) and bond angles (Њ) for 10Cr
Cr–C(17)
1.843(4)
1.887(4)
1.838(5)
1.885(5)
2.3671(12)
2.5288(14)
Ta–Ct(1)
Ta–Ct(2)
Ta–C(16)
Ta–P(1)
2.06
2.10
2.025(4)
2.6695(11)
1.807(4)
Cr–C(18)
Cr–C(19)
Cr–C(20)
Cr–P(2)
P(2)–C(1)
Cr–P(1)
C(16)–Ta–P(1)
Ct(1)–Ta–Ct(2)
Ct(1)–Ta–C(16)
Ct(2)–Ta–C(16)
Ct(1)–Ta–P(1)
Ct(2)–Ta–P(1)
P(1)–Cr–P(2)
C(17)–Cr–P(1)
C(17)–Cr–P(2)
C(17)–Cr–C(18)
C(17)–Cr–C(19)
C(17)–Cr–C(20)
90.65(12)
135.1
103.1
101.5
104.4
C(18)–Cr–P(1)
C(18)–Cr–P(2)
C(18)–Cr–C(19)
C(18)–Cr–C(20)
C(19)–Cr–P(1)
C(19)–Cr–P(2)
C(19)–Cr–C(20)
C(20)–Cr–P(1)
C(20)–Cr–P(2)
Cr(1)–P(1)–Ta
C(1)–P(2)–Cr
87.92(12)
88.00(13)
88.5(2)
172.2(2)
176.1(2)
93.51(14)
87.4(2)
95.97(14)
98.82(14)
119.68(4)
113.13(12)
112.4
Scheme 6
87.95(4)
92.79(14)
177.87(14)
90.0(2)
85.6(2)
83.1(2)
length is 2.367(1) Å and compares to those usually observed for
PCr(CO)n groups.15 In contrast, the P(1)–Cr distance is remark-
ably long: 2.5288(14) Å. This distance is close to the sum of the
covalent radii of Cr (1.48 Å)16 and P (1.10 Å).17 Such long
distances (>2.50 Å) have already been reported for some crystal
structures involving a M–P–Cr(CO)n bridge.18
Experimental
General
Nuclear magnetic resonance spectra were recorded on a Bruker
AC 200 instrument at 200 MHz for 1H and 81 MHz for 31P. The
chemical shifts are reported in ppm relative to SiMe4 (1H) and
external H3PO4 (3lP-{1H}). Infrared spectra were obtained with
a Nicolet 250 spectrometer, with the sample in a solution of thf.
Elemental analyses were performed on an EA 1108 CHNS-O
FISONS Instruments apparatus.
All reactions were carried out under an atmosphere of
argon using standard Schlenk line techniques and conventional
glass vessels. The solvents were dried over suitable reagents and
freshly distilled under argon before use. Li(C5H4PPh2),19
Cp*TaCl4,6 Cr(CO)4(nbd),20 W(CO)4(MeCN)2 21 and MЈ(CO)5-
(thf)22 (MЈ = Cr, W) were prepared according to literature
methods.
Fig. 1 ORTEP24 view of Cp*(C5H4PPh2)Ta(CO)(µ-PPh2)Cr(CO)4
10Cr. The chloroform solvate molecules are omitted for clarity.
monophosphido bridged derivatives, i.e. CpЈCpTa(CO)(µ-
PMe2)W(CO)4L (L = (o-anisyl)methylphenylphosphine), Cp2-
Ta(CO)(µ,η1 :η1-PMe2S)W(CO)5 and Cp*CpTa(CO)(µ-PPh-
OMe)Cr(CO)5.14 The main differences observed between the
mono bridged complex Cp*CpTa(CO)(µ-PPhOMe)Cr(CO)5
and 10Cr result from the cyclic nature of the bridge in 10Cr,
thus the Ta–P(1)–Cr angle is smaller in 10Cr than in the
mono bridged compound (119.68(4)Њ vs. 127.1(1)Њ) leading to a
smaller Ta ؒ ؒ ؒ Cr distance in 10Cr than in the mono bridged
complex (4.495 Å for 10Cr vs. 4.646 Å). The P(2)–Cr bond
Syntheses
Cp*(C5H4PPh2)TaCl2 1. Compound
1 was synthesized
according to Bercaw’s method reported for Cp*CpTaCl2 6 with
minor modifications. 4.58 g (10 mmol) of Cp*TaCl4 was
J. Chem. Soc., Dalton Trans., 1999, 2725–2730
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reduced with 0.5 equiv. of Mg in thf in the presence of 1 equiv.
of PMe3. Removal of the solvent afforded a red residue. This
crude product was treated with 2.49 g (10 mmol) Li(C5H4PPh2)
in toluene at 100 ЊC. After 12 h of stirring, extraction and
crystallization in acetone afforded 6.04 g (95%) of the green
paramagnetic product 1 (Found: C, 50.69; H, 4.52. C27H29-
Cl2PTa requires C, 50.96; H, 4.59%). The ESR spectrum in
of toluene. The solvent was removed and the green product was
dried in vacuo to yield 0.62 g of 5b (65%) (Found: C, 61.47; H,
5.12. C40H39P2OTa requires C, 61.70; H, 5.05%). FT IR (thf,
cmϪ1): 1910s (νCO). NMR (CD3COCD3): 1H, δ 8.20–8.05
(m, Ph), 7.56–6.77 (m, Ph), 5.35 (m, C5H4), 5.23 (m, C5H4), 4.21
(m, C5H4), 2.91 (m, C5H4), 1.87 (s, Me); 31P-{1H}, δ Ϫ5.6 (s),
Ϫ12.3 (s).
toluene showed an eight-line spectrum: giso = 1.9306; ATa,
122.18 G.
=
iso
Cp*(C5H4PPh2)Ta(H)3W(CO)5 6. To a thf solution (20 cm3)
of Cp*(C5H4PPh2)Ta(H)3 2 (0.57 g, 1 mmol) was added an
excess (20%) of W(CO)5(thf). The mixture was stirred for 20
min at room temperature (the reaction was monitored by IR
spectroscopy). The solvent was removed under vacuum, and the
crude reaction product was crystallized from acetone affording
0.66 g (75%) of 6 (Found: C, 43.11; H, 3.66. C32H32O5PTaW
requires C, 43.07; H, 3.61%). FT IR (thf, cmϪ1): 2070m, 1940vs,
1895s (νCO). NMR (CD3COCD3): 1H, δ 8.00–7.28 (m, Ph), 5.23
(m, C5H4), 5.08 (m, C5H4), 1.95 (s, Me), Ϫ0.46 (td, 5.9, 9.8 Hz,
H), Ϫ1.91 (dd, 4.9, 9.8 Hz, H); 31P-{1H}, δ 16.07 [s, J(W–P) =
256 Hz].
Cp*(C5H4PPh2)Ta(H)3 2. 3.18 g of 1 (5 mmol) was reduced
by 5 cm3 of NaAlH2(OCH2CH2OMe)2 (2 M in toluene, 10
mmol) in 50 cm3 of toluene at 0 ЊC. After 3 h of stirring, the
brown-red solution was hydrolyzed slowly by 10 cm3 of
degassed water. The organic layer was decanted and extracted.
Evaporation of the solvent, followed by washing with pentane
gave 1.48 g (52%) of complex 2 (Found: C, 56.86; H, 5.71.
C27H32PTa requires C, 57.05; H, 5.67%). NMR (CD3COCD3):
1H, δ 7.47–7.15 (m, Ph), 5.19 (t, J = 2.4 Hz, C5H4), 4.56 (q,
J = 2.4 Hz [JH–H = JP–H], C5H4), 1.99 (s, Me), Ϫ0.54 (dt, J = 1.9,
11.2 Hz, H), Ϫ1.77 (dd, J = 5.9, 11.2 Hz, H); 3lP-{1H}, δ Ϫ11.4
(s).
Cp*(C5H4PPh2)Ta(H)2(ꢀ-H)MЈ(CO)4 (MЈ ؍ Cr, W) 7(Cr,
W). Cr(CO)4(nbd) or [W(CO)4(MeCN)2] was added to a thf
solution (30 cm3) of 2 (0.3 g, 0.53 mmol). The orange solution
was stirred for 2 h at 50 ЊC. The solvent was removed under
reduced pressure and the resulting residue washed with pentane
(10 cm3) and dried in vacuo. The solid was crystallized from
acetone affording the product 7 (70–74%).
Cp*(C5H4PPh2)Ta(H)(CO) 3. 2 g of 2 was stirred in 30 cm3
of decane at 140 ЊC under a carbon monoxide atmosphere for
3 h. The solvent was then removed under reduced pressure and
the residue was dried in vacuo. Crystallization from pentane
yielded 1.25 g (60%) of the green compound 3 (Found: C,
56.27; H, 5.02. C28H30POTa requires C, 56.57; H, 5.09%). FT
1
IR (thf, cmϪ1): 1882s (νCO). NMR (CD3COCD3): H, δ 7.63–
Cp*(C5H4PPh2)Ta(H)2(µ-H)Cr(CO)4 7Cr. (Found: C,
50.83; H, 4.46. C3lH32O4PTaCr requires C, 50.83; H, 4.40%). FT
IR (thf, cmϪ1): 2006s, 1898s, 1844s (νCO). NMR (CD3COCD3):
1H, δ 8.00–7.77 (m, Ph), 7.54–7.32 (m, Ph), 5.78 (m, C5H4), 5.02
(m, C5H4), 2.21 (s, Me), 0.03 (d, J = 11.8 Hz, H), Ϫ15.35 (t,
J = 11.8 Hz, H); 31P-{1H), δ 55.06.
7.19 (m, Ph), 5.25 (m, C5H4), 4.80 (m, C5H4), 4.20 (m, C5H4),
4.00 (m, C5H4), 1.88 (s, Me), Ϫ5.94 (d, J = 5.8 Hz, H); 3IP-{1H},
δ Ϫ12.5 (s).
[Cp*(C5H4PPh2)Ta(H)2(PPh2H)]؉Cl؊ 4a. To a toluene solu-
tion (30 cm3) of 2 (1 g, 1.76 mmol) was added PPh2Cl (0.39 g,
1.76 mmol). A precipitate was immediately formed. After 30
min of stirring, it was filtered off, washed with pentane, and
dried under vacuum affording 0.83 g (80%) of a white powder
(Found: C, 58.96; H, 5.58. C39H42P2ClTa requires C, 59.36; H,
5.36%). NMR (CD3COCD3): 1H, δ 8.24–7.11 (m, Ph), 7.85 (td,
J = 4.9, 393 Hz, PPh2H), 5.90 (m, C5H4), 4.67 (m, C5H4), 2.04 (s,
Me), 0.30 (ddd, J = 5.1, 5.9 Hz, J = 72 Hz, Ta–H); 31P-{1H},
δ 2.2 (s), Ϫ16.2 (s).
Cp*(C5H4PPh2)Ta(H)2(µ-H)W(CO)4 7W. (Found: C,
42.80; H, 3.91. C31H3204PTaW requires C, 43.08; H, 3.73%). FT
IR (thf, cmϪ1): 2011s, 1937s, 1894s, 1847s (νCO). NMR
(CD3COCD3): 1H, δ 8.00–7.78 (m, Ph), 7.61–7.33 (m, Ph), 5.86
(m, C5H4), 5.09 (m, C5H4), 2.21 (s, Me), 0.03 (d, J = 12 Hz, H),
Ϫ12.56 (td, J = 12, 5 Hz, H); 31P-{1H}, 11.43.
Cp*(C5H4PPh2)Ta(CO)(ꢀ-H)W(CO)4 8aW. Procedure A. A
thf solution (100 cm3) of Cp*(C5H4PPh2)Ta(H)3W(CO)5 6 (0.50
g, 0.56 mmol) was irradiated with a HANAU TQ 150 lamp for
3 h at room temperature. The solvent was evaporated to give a
green powder. The crude product was chromatographed over a
silica gel (70–230 mesh) column (toluene eluant) affording 0.30
g (60%) of 8aW. Procedure B. To a thf solution of Cp*(C5H4-
PPh2)Ta(H)(CO) 3 (0.25 g, 0.42 mmol) was added 1 equiv. of
W(CO)4(MeCN)2. The mixture was stirred for 2 h at 40 ЊC and
the reaction was monitored by IR spectroscopy. The solvent
was removed and the crude product was crystallised from
acetone leading to an analytically pure sample of 8aW (57%).
Procedure C. To a thf solution of Cp*(C5H4PPh2)Ta(H)(CO) 3
(0.25 g, 0.42 mmol) was added an excess (20%) of W(CO)5(thf).
The mixture was stirred for 2 h at room temperature and the
reaction was monitored by IR spectroscopy. The solvent was
removed in vacuo and the crude reaction product was chrom-
atographed over a silica gel column (70–230 mesh). Impurities
were first eliminated by eluting with toluene–pentane (90:10).
Further elution with toluene gave a large band corresponding
to a mixture of 8aW and 8bW (42:58).
Cp*(C5H4PPh2)Ta(H)2(PPh2) 4b.
A saturated aqueous
solution of KOH (10 cm3) was added to the dried salt
[Cp*(C5H4PPh2)Ta(H)2(PPh2H)]ϩClϪ 4a (1 g, 1.27 mmol). The
mixture was stirred for 30 min. The product was extracted with
2 × 15 cm3 of toluene, and the organic layer was separated and
evaporated giving 0.57 g (60%) of the white product 4b
(Found: C, 61.98; H, 5.22. C39H41P2Ta requires C, 62.24; H,
5.49%). NMR (CD3COCD3): 1H, δ 7.63–6.86 (m, Ph), 5.33
(t, J = 2.46 Hz, C5H4), 4.51 (m, C5H4), 1.89 (s, Me), 0.63 (dd,
J = 5.9, 61 Hz, Ta–H); 31P-{1H}, δ Ϫ12.0 (s), Ϫ16.4 (s).
[Cp*(C5H4PPh2)Ta(CO)(PPh2H)]؉Cl؊ 5a. To
a toluene
solution (30 cm3) of 3 (1 g, 1.68 mmol) was added 1 equiv. of
PPh2Cl. The white precipitate was filtered, washed with toluene
(10 cm3) and pentane (2 × 10 cm3), and dried in vacuo to yield
1.16 g (85%) of 5a (Found: C, 59.13; H, 4.64. C40H40P2OClTa
requires C, 58.94; H, 4.95%). FT IR (thf, cmϪ1): 1894 s (νCO).
1
NMR (CD3COCD3): H, δ 8.22–7.05 (m, Ph), 7.77 (d, J = 378
Hz, PPh2H), 6.48 (m, C5H4), 5.28 (m, C5H4), 4.99 (m, C5H4),
3.24 (m, C5H4), l.9s (s, Me); 31P-{1H}, δ 11.2 (s), Ϫ13.4 (s).
Cp*(C5H4PPh2)Ta(CO)(µ-H)W(CO)4 8aW. (Found: C,
42.73; H, 3.40. C32H30O5PTaW requires C, 43.14; H, 3.40%). FT
IR (thf, cmϪ1): 2007s, l919s, 1889s, 1883s, 1847s (νCO). NMR
(CD3COCD3): 1H, δ 8.04–7.34 (m, Ph), 5.36 (m, C5H4), 4.99 (m,
C5H4), 4.82 (m, C5H4), 2.13 (s, Me), Ϫ15.05 [s, J(H–W) = 40 Hz,
H]; 31P-{1H}, δ 8.22 [J(W–P) = 226 Hz].
Cp*(C5H4PPh2)Ta(CO)(PPh2) 5b. To the dried salt 5a (1 g,
1.23 mmol) was added a saturated aqueous solution of KOH
(10 cm3) followed by 15 cm3 of toluene. The green organic layer
was separated and the aqueous layer was extracted with 15 cm3
2728
J. Chem. Soc., Dalton Trans., 1999, 2725–2730

View Article Online
with full-matrix least-squares methods23 based on |F2|. All
Table 2 Crystal data and structure refinement for 10Cr
non-hydrogen atoms were refined with anisotropic thermal
parameters. Hydrogen atoms of the complex were included in
their calculated positions and refined with a riding model. The
rather large residual peak and hole in the final Fourier differ-
ence map are located close (<1 Å) to the Ta atom. Selected
bond distances and angles are collected in Table 1.
CCDC reference number 186/1549.
Formula
M
T/K
Crystal system
Space group
a/Å
b/Å
c/Å
C44H39O5P2CrTaؒ2CHCl3
1181.38
293(2)
Triclinic
¯
P1
11.095(2)
11.395(2)
20.220(2)
79.86(3)
See http://www.rsc.org/suppdata/dt/1999/2725/ for crystallo-
graphic files in .cif format.
α/Њ
β/Њ
80.42(3)
γ/Њ
72.31(3)
2380.0(6)
V/Å3
References
Z
2
µ/mmϪ1
2.974
1 R. Choukroun, D. Gervais, J. Jaud, P. Kalck and F. Senocq,
Organometallics, 1986, 5, 67; M. J. Hostetler, M. D. Butts and R. G.
Bergman, J. Am. Chem. Soc., 1993, 115, 2743; Y. Yamaguchi,
N. Suzuki, T. Mise and Y. Wakatsuki, Organometallics, 1999, 18, 996
and references therein.
2 D. W. Stephan, Coord. Chem. Rev., 1989, 95, 41; R. T. Baker,
W. C. Fultz, T. B. Morder and I. D. Williams, Organometallics,
1990, 9, 2357; R. M. Bullock and C. P. Casey, Acc. Chem. Res., 1987,
20, 167.
RC = Reflections Collected
IRC = Independent RC
IRCGT = IRC and [I > 2σ(I)]
R for IRCGT
10879
9653 [Rint = 0.0141]
8407
R1a = 0.0318, wR2b = 0.0800
R1a = 0.0451, wR2b = 0.0855
R for IRC
a R1 = Σ(|Fo| Ϫ |Fc|)/Σ|Fo|. b wR2 = [Σw(Fo2 Ϫ Fc2)2/Σ[w(Fo )2]1/2 where
2
2
2
w = 1/[σ2(Fo ) ϩ (0.0491P)2 ϩ 2.03P] where P = (Max(Fo , 0) ϩ 2Fc2)/3.
3 X. Dong He, A. Maisonnat, F. Dahan and R. Poilblanc,
Organometallics, 1989, 8, 2618; W. Tikkanen, Y. Fujita and J. L.
Petersen, Organometallics, 1986, 5, 888; R. M. Bullock and C. P.
Casey, Acc. Chem. Res., 1987, 20, 167; F. T. Ladipo, G. K. Anderson
and N. P. Rath, Organometallics, 1994, 13, 4741; J. Szymoniak,
M. M. Kubicki, J. Besançon and C. Moïse, Inorg. Chim. Acta, 1991,
180, 153.
4 J. F. Reynoud, J. C. Leblanc and C. Moïse, J. Organomet. Chem.,
1985, 296, 377; V. I. Bakhmutov, E. V. Vorontsov, G. Boni and
C. Moïse, Inorg Chem, 1997, 36, 4055.
Cp*(C5H4PPh2)Ta(H)(CO)W(CO)5 8bW. (Identified from
the mixture of 8aW and 8bW.) FT IR (thf, cmϪ1): 2071s, 1939s,
1913s, 1892s (νCO). NMR (CD3COCD3): H, δ 7.76–6.76 (m,
Ph), 4.96 (m, C5H4), 4.41 (m, C5H4), 4.00 (m, C5H4), 3.83 (m,
C5H4), 1.65 (s, Me), Ϫ5.52 (d, J = 14.8 Hz, H); 31P-{1H}, δ 11.83
[J(W–P) = 261 Hz].
1
5 G. Bonnet, O. Lavastre, G. Boni, J. C. Leblanc and C. Moïse, C.R.
Acad. Sci. Paris, Ser. II, 1994, 319, 1293; O. Lavastre, G. Bonnet,
G. Boni, M. M. Kubicki and C. Moïse, J. Organomet. Chem., 1997,
547, 141; C. Barré, P. Boudot, M. M. Kubicki and C. Moïse, Inorg.
Chem., 1995, 34, 284; V. Comte, O. Blacque, M. M. Kubicki and
C. Moïse, Organometallics, 1997, 16, 5763.
6 V. C. Gibson, J. E. Bercaw, W. J. Burton, Jr. and R. D. Sanner,
Organometallics, 1986, 5, 976.
7 M. L. H. Green, J. A. McCleverty, L. Pratt and G. Wilkinson,
J. Chem. Soc., 1961, 4854; F. N. Tebbe and G. W. Parshall, J. Am.
Chem. Soc., 1971, 93, 3793.
Cp*(C5H4PPh2)Ta(H)2(ꢀ-PPh2)Cr(CO)4 9Cr. The procedure
described earlier for complex 7Cr was performed but starting
from (0.20 g, 0.26 mmol) Cp*(C5H4PPh2)Ta(H)2(PPh2) and 1
equiv. of Cr(CO)4(nbd). The crude product obtained after
removal of solvent was recrystallised from acetone leading to
0.16 g of 9Cr (65%) (Found: C, 56.01; H, 4.38. C43H41O4P2-
TaCr requires C, 56.32; H, 4.51%). FT IR (thf, cmϪ1): 1993s,
1
1908s, 1872s, 1858s (νCO). NMR (CDCl3): H, δ 8.22–7.96 (m,
Ph), 7.57–7.02 (m, Ph), 6.26 (m, C5H4), 4.67 (m, C5H4), 2.47
(d, J = 54 Hz, H), 1.69 (s, Me); 31P-{1H}, δ 59.7 (d, J = 10 Hz),
Ϫ1.4 (d, J = 10 Hz).
8 G. I. Nikonov, D. A. Lemenovskii and J. Lorberth, Organometallics,
1994, 13, 3127; G. I. Nikonov, Y. K. Grishin, D. A. Lemenovskii,
N. B. Kazennova, L. G. Kuzmina and J. A. K. Howard,
J. Organomet. Chem., 1997, 547, 183.
9 G. Bonnet, M. M. Kubicki, C. Moïse, R. Lazzaroni, P. Salvadori
and G. Vitulli, Organometallics, 1992, 11, 964; W. E. Buhro, B. D.
Zwick, S. Georgiou, J. P. Hutchinson and J. A. Gladysz, J. Am.
Chem. Soc., 1988, 110, 2427; G. Boni, M. M. Kubicki and C. Moïse,
Bull. Soc. Chim. Fr., 1994, 131, 895.
10 G. Bonnet, M. M. Kubicki, J. C. Leblanc and C. Moïse, New
J. Chem., 1988, 12, 551; G. Boni, P. Sauvageot and C. Moïse,
J. Organomet. Chem., 1995, 489, C32; G. Boni, P. Sauvageot,
E. Marpeaux and C. Moïse, Organometallics, 1995, 14, 5652.
11 F. Mercier, C. Hugel le Goff and F. Mathey, Organometallics, 1988,
7, 955; P. S. Pregosin and R. W. Kunz, in 31P and 13C NMR of
transition metal phosphine complexes, Springer-Verlag, Berlin, 1979,
p. 116.
Cp*(C5H4PPh2)Ta(CO)(ꢀ-PPh2)MЈ(CO)4 (MЈ ؍ Cr, W)
10(Cr, W). The procedure described earlier for complex 7Cr
was performed but starting from 0.2 g (0.26 mmol) Cp*(C5H4-
PPh2)Ta(CO)(PPh2) and 1 equiv. of Cr(CO)4(nbd) or W(CO)4-
(MeCN)2. The crude product was chromatographed over a
silica gel (70–230 mesh) column (toluene eluant) affording a
deep red powder (70-75%) of 10(Cr, W).
Cp*(C5H4PPh2)Ta(CO)(µ-PPh2)Cr(CO)4 10Cr. (Found:
C, 55.54; H, 4.41. C44H39CrO5P2Ta requires C, 56.06; H,
4.17%). FT IR (thf, cmϪ1): 1993s, 1906s, l900s, 1879s, 1854s
1
(νCO). NMR (CDCl3): H, δ 7.96–7.67 (m, Ph), 7.60–6.96 (m,
12 B. D. Zwick, A. M. Arif, A. T. Patton and J. A. Gladysz, Angew.
Chem., Int. Ed. Engl., 1987, 26, 910.
13 B. Fuchs, Top. Stereochem., 1978, 10, 1.
Ph), 5.66 (m, C5H4), 5.05 (m, C5H4), 4.19 (m, C5H4), 1.57 (s,
Me); 31P-{1H), δ 65.5 (s), 18.8 (s).
Cp*(C5H4PPh2)Ta(CO)(µ-PPh2)W(CO)4 10W. (Found: C,
49.04; H, 3.76. C44H39O5P2TaW requires C, 49.18; H, 3.66%).
FT IR (thf, cmϪ1): 2003s, l909s, 1898s, 1880s, 1853s (νCO). NMR
14 P. Sauvageot, O. Blacque, M. M. Kubicki, S. Jugé and C. Moïse,
Organometallics, 1996, 15, 2399; S. Challet, M. M. Kubicki, J. C.
Leblanc, C. Moïse and B. Nuber, J. Organomet. Chem., 1994, 483,
47; S. Challet, O. Lavastre, C. Moïse, J. C. Leblanc and B. Nuber,
New J. Chem., 1994, 18, 1155.
15 Data obtained for 20 crystal structures from the Cambridge
Crystallographic Data base.
16 F. A. Cotton and D. C. Richardson, Inorg. Chem., 1986, 5, 1851.
17 L. Pauling, in Grundlagen der Chemie, Verlag Chemie, Weinheim,
1973, p. 170.
18 E. Hey, A. C. Willis and S. B. Wild, Z. Naturforsch., Teil B, 1989,
44, 1041; L. Weber, R. Kirchhoff and R. Boese, J. Chem. Soc.,
Chem. Commun., 1992, 1182; F. Lindenberg, T. Gelbrich and
E. Hey-Hawkins, Z. Anorg. Allg. Chem., 1995, 621, 771; P. Oudet,
D. Perrey, G. Bonnet, C. Moïse and M. M. Kubicki, Inorg. Chem.
Acta, 1995, 237, 79.
1
(CDCl3): H, δ 7.91–7.57 (m, Ph), 7.52–6.96 (m, Ph), 5.62 (m,
C5H4), 5.09 (m, C5H4), 4.40 (m, C5H4), 1.58 (s, Me); 31P-{1H},
δ
32.2 [d, J = 10, J(P–W) = 249 Hz], Ϫ9.0 [d, J = 10,
J(P–W) = 151 Hz].
Crystal structure analysis
A crystal of 10Cr (red; 0.30 × 0.25 × 0.20 mm3) was mounted
on an Enraf Nonius CAD4 diffractometer. Experimental
details are summarized in Table 2. The structure was solved via
a Patterson search program23 and refined (space group P1)
¯
J. Chem. Soc., Dalton Trans., 1999, 2725–2730
2729

View Article Online
19 F. Mathey and J. P. Lampin, Tetrahedron, 1975, 31, 2685.
20 M. A. Bennet, L. Pratt and G. J. Wilkinson, J. Chem. Soc. A, 1961,
2037.
23 G. M. Sheldrick, SHELXS and SHELX97, University of
Göttingen, Göttingen, Federal Republic of Germany, 1997.
24 C. K. Johnson, ORTEP, Report ORNL-5138, Oak Ridge National
Laboratory, Oak Ridge, TN, 1976.
21 I. W. Stolz, G. R. Dobson and R. K. Sheline, Inorg. Chem., 1963, 2,
323.
Paper 9/03603B
22 W. Strohmeier and F. J. Mueller, Chem. Ber., 1969, 102, 3608.
2730
J. Chem. Soc., Dalton Trans., 1999, 2725–2730