Syntheses, crystal structures and reactivity of organometallic tantalum(IV) phosphinidene complexes: trans-[{Cp*TaCl(μ-PR)}2] (Cp* = C5Me5, R = Cy, tBu, Ph), cis- and trans-[{Cp*TaCl(μ-PMes)}2] (Mes = 2,4,6-Me3C6H2) and cis-[{Cp′TaCl(μ-PMes)}2]

Article abstract of DOI:10.1002/1099-0682(200211)2002:11<2975::AID-EJIC2975>3.0.CO;2-1

The reaction of [Cp*TaCl₄] (Cp* = C₅Me₅) with LiPHR (1:1 or 1:2) gives the phosphinidene-bridged tantalum(IV) complexes trans-[{Cp*TaCl(μ-PR)}₂] [R = Cy (1), tBu (2), Ph (3), 2,4,6-Me₃C₆H₂ (Mes) (4b)]. When the reaction with LiPHMes is carried out in a 1:1 ratio, cis-[{Cp*TaCl(μ-PMes)}₂] (4a) is also formed besides 4b. For comparison, cis-[{Cp′TaCl(μ-PMes)}₂] (5) was prepared from [Cp′TaCl₄] (Cp′ = C₅MeH₄) and LiPHMes (1:1). 1-5 are diamagnetic and were characterised spectroscopically (IR, MS; ¹ H, ³¹P, ¹³C NMR). Crystal structure determinations on 1-5 showed the presence of dimeric phosphinidene-bridged Ta^IV complexes. The phosphinidene-bridged complexes 1, 3 and 4b do not react with acetone, benzophenone, acetonitrile, CS₂ (1, 3), acetaldehyde (4b), or ethylaluminum dichloride (3). 3 reacts with moist acetone in the presence of traces of air to give the trinuclear cluster [{Cp*TaCl(μ₂-O)}₃(μ₃-O) (μ₂-O₂PHPh)}] (6) in very low yield. With an excess of CyNC, 3 gives [Cp*TaCl(CNCy)4]Cl (7), which was characterised by ¹H and ¹³C NMR spectroscopy and by crystal structure determination. As a minor product, [(Cp*TaCl₂)₂(μ₂-O) (η²,μ₂-P₂Cy₂)] (8) was also obtained in the reaction of [Cp*TaCl₄] with LiPHCy. 6 and 8 were only characterised by crystal structure determination. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.

Full text of DOI:10.1002/1099-0682(200211)2002:11<2975::AID-EJIC2975>3.0.CO;2-1

FULL PAPER
Syntheses, Crystal Structures and Reactivity of Organometallic Tantalum(IV
)
Phosphinidene Complexes: trans-[{Cp*TaCl(µ-PR)}2] (Cp* ؍ C5Me5, R ؍ Cy,
tBu, Ph), cis- and trans-[{Cp*TaCl(µ-PMes)}2] (Mes ؍ 2,4,6-Me3C6H2) and
cis-[{CpЈTaCl(µ-PMes)}2] (CpЈ ؍ C5H4Me)
Steffen Blaurock[a] and Evamarie Hey-Hawkins*[a]
Keywords: Tantalum / P ligands / Oxo ligands / Isocyanide ligands
The reaction of [Cp*TaCl4] (Cp* = C5Me5) with LiPHR (1:1
or 1:2) gives the phosphinidene-bridged tantalum(IV) com-
plexes trans-[{Cp*TaCl(µ-PR)}2] [R = Cy (1), tBu (2), Ph (3),
tone, benzophenone, acetonitrile, CS2 (1, 3), acetaldehyde
(4b), or ethylaluminum dichloride (3). 3 reacts with moist ace-
tone in the presence of traces of air to give the trinuclear
2,4,6-Me3C6H2 (Mes) (4b)]. When the reaction with LiPHMes cluster [{Cp*TaCl(µ2−O)}3(µ3-O)(µ2-O2PHPh)}] (6) in very low
is carried out in a 1:1 ratio, cis-[{Cp*TaCl(µ-PMes)}2] (4a) is
also formed besides 4b. For comparison, cis-[{CpЈTaCl(µ-
PMes)}2] (5) was prepared from [CpЈTaCl4] (CpЈ = C5MeH4)
and LiPHMes (1:1). 1−5 are diamagnetic and were characte-
yield. With an excess of CyNC, 3 gives [Cp*TaCl(CNCy)4]Cl
(7), which was characterised by 1H and 13C NMR spectros-
copy and by crystal structure determination. As a minor pro-
duct, [(Cp*TaCl2)2(µ2-O)(η2,µ2-P2Cy2)] (8) was also obtained
in the reaction of [Cp*TaCl4] with LiPHCy. 6 and 8 were only
characterised by crystal structure determination.
1
rised spectroscopically (IR, MS; H, 31P, 13C NMR). Crystal
structure determinations on 1−5 showed the presence of di-
meric phosphinidene-bridged TaIV complexes. The phosphi-
( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany,
nidene-bridged complexes 1, 3 and 4b do not react with ace- 2002)
Introduction
dication from the 31P NMR spectra of the formation of
tantalum phosphinidene complexes, which could, however,
not be isolated.
We now report the targeted synthesis of these and other
dimeric TaIV phosphinidene complexes, which are accessible
from [CpRTaCl4] (CpR ϭ Cp*, CpЈ) and LiPHRЈ, and some
reaction products thereof. The related tantalum()
phenylimido complex trans-[{Cp*TaCl(µ-NPh)}2] is also
known.[9]
Organometallic dialkyl- and diarylphosphanido com-
plexes of early transition metals have been studied intens-
ively, while complexes derived from functionalised phos-
phanes which exhibit a reactive phosphorus-ligand bond
have largely been neglected.[1] To date, only a few phos-
phanido derivatives of organometallic[2,3] and inorganic[4,5]
tantalum compounds, one phosphinidene-bridged dimeric
TaIV complex[3] and two stable terminal phosphinidene
complexes[5,6] have been described in the literature.
Recently, we reported the syntheses and structures of the
primary phosphane complexes [CpЈTaCl4(PH2Tipp)]
(CpЈ ϭ C5H4Me, Tipp ϭ 2,4,6-iPr3C6H2)[3] and [Cp*
MCl4(PH2R)] [Cp* ϭ C5Me5; M ϭ Nb, Ta; R ϭ tBu, Ad,
Cy, Ph, 2,4,6-Me3C6H2 (Mes)],[7] which we expected to be
suitable precursors for the preparation of phosphanido and
Results and Discussion
Synthesis and Properties of trans-[{Cp*TaCl(µ-PR)}2] [R ؍
Cy (1), tBu (2), Ph (3)], cis- and trans-[{Cp*TaCl(µ-
PMes)}2] (4a,b) and cis-[{CpЈTaCl(µ-PMes)}2] (5)
When [Cp*TaCl4][7,10] was treated with two equivalents
phosphinidene
TaCl4(PH2R)] (R ϭ tBu, Cy, Ad, Ph, Mes) were treated LiPHR low in solution) at low temperature (to reduce side
with DBU an internal redox reaction occurred with forma- reactions), the deep red phosphinidene-bridged
tion of [(DBU)H][Cp*TaCl4] (DBU 1,8-diazabicy- tantalum() complexes trans-[{Cp*TaCl(µ-PR)}2] [R ϭ Cy
complexes.
However,
when
[Cp* of LiPHR[11Ϫ14] in toluene (to keep the concentration of
ϭ
clo[5.4.0]undec-7-ene) and the corresponding diphosphane (1), tBu (2), Ph (3), Mes (4b)] were obtained after workup
(P2H2R2) or decomposition products thereof.[8] For the in 73 to 86% yield (based on [Cp*TaCl4]; Scheme 1).
aryl-substituted phosphane complexes, there was also an in-
In the 31P NMR spectra of the reaction mixtures, one
singlet is observed for the tBu, Ph and Mes derivatives,
while for the Cy derivative, two singlets are observed in the
low-field region, one of which has only a low intensity [δ ϭ
437.6 (major) and 433.7 (minor) ppm]. The major signal
[a]
Institut für Anorganische Chemie der Universität Leipzig
Johannisallee 29, 04103 Leipzig (Germany)
Fax: (internat.) ϩ 49Ϫ(0)341/9739319
E-mail: hey@rz.uni-leipzig.de
Eur. J. Inorg. Chem. 2002, 2975Ϫ2984  2002 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim 1434Ϫ1948/02/1111Ϫ2975 $ 20.00ϩ.50/0 2975

S. Blaurock, E. Hey-Hawkins
FULL PAPER
Related tantalum phosphinidene complexes include
trans-[(CpЈTaCl{µ-P(Tipp)})2] (I),[3] which was obtained by
treating [CpЈTaCl4{PH2(Tipp)}] with DBU (1:2 or 1:3), and
the
stable
terminal
phosphinidene
complexes
[N{CH2CH2N(SiMe3)}3TaϭPR] [δ(31P) ϭ 175.1 (R ϭ Cy)
and 227.3 (R ϭ tBu) ppm][6] and [(tBu3SiO)3TaϭPPh][5]
[δ(31P) ϭ 334.6 ppm]. These 31P chemical shifts indicate the
presence of a linear MPR unit (bent MPR unit: δ ϭ 660 to
800 ppm).[17] For 1؊5 and I, 31P chemical shifts of δ ϭ
390.3 ppm (for 4b) to 482.0 ppm (for 2) are observed [for I,
δ(31P) ϭ 391.5 ppm], and ∆δ (phosphane vs. phosphinidene
complex) ranges from δ ϭ 526 to 562 ppm (Table 1).
Apparently, the influence of the substituted cyclo-
pentadienyl ligand on the 31P NMR chemical shift is negli-
gible, as shown by the similar values for 4b (Cp* complex)
and I (CpЈ complex), while alkyl-substituted phosphinidene
complexes 1 and 2 exhibit low-field shifts compared to aryl-
substituted phosphinidene complexes 3؊5. The same trend
is observed for the corresponding primary phosphanes
(Table 1).
Scheme 1
In the 13C NMR spectra of 1؊4, the signals of the car-
bon atoms of the Cp* ring are shifted to high field by ∆δ ϭ
16.5Ϫ18 relative to the starting material [Cp*TaCl4] (δ ϭ
132.9 ppm).
was shown to belong to the trans isomer, while the minor
signal presumably belongs to the cis isomer.
When the reaction of [Cp*TaCl4] with LiPHMes was car-
ried out in a 1:1 ratio, cis-[{Cp*TaCl(µ-PMes)}2] (4a) was
also formed along with 4b. An additional signal was ob-
served in the 31P NMR spectrum at δ ϭ 485.8 ppm [ratio
ca. 1 (4a): 6 (4b): 3], which indicates the formation of a
terminal phosphinidene complex, [Cp*TaCl2(PMes)] (cf.
the stable terminal phosphinidene complex [Cp*
TaCl2{P(Tipp)}], which shows a singlet at δ ϭ 488.0
ppm).[15] The mesitylphosphinidene complex could, how-
ever, not be obtained in its pure form. Complexes 4a and
4b could be separated by fractional crystallisation from n-
hexane.
Molecular ion peaks were observed in the mass spectra
of 1؊4.[18] For 1, 3, and 4a, signals for monomeric [Cp*
TaCl(PR)]ϩ and fragmentation products thereof were also
observed.
In the UV/Vis spectra in pentane, 1؊4 exhibit four ab-
sorptions in the ranges 682 Ϫ 753 (ν1), 473 Ϫ 528 (ν2), 337
Ϫ 396 (ν3), and 313 Ϫ 319 nm (ν4), with molar absorption
coefficients of 102 Ϫ 103 (for ν1, d-d transition), 2·103 Ϫ
104 (for ν2 and ν3; CT transitions), and 104 Ϫ 3·104 cm2/
mol (for ν4, π -π * transition of Cp*).
For comparison, cis-[{CpЈTaCl(µ-PMes)}2] (5) was pre-
pared from [CpЈTaCl4][16] and LiPHMes (1:1). In the 31P
NMR spectrum of the reaction mixture, only one signal
was observed, which indicates the exclusive formation of
the cis isomer.
Molecular Structures of trans-[{Cp*TaCl(µ-PR)}2] [R ؍ Cy
(1), tBu (2), Ph (3), Mes (4b)], cis-[{Cp*TaCl(µ-PMes)}2]
(4a) and cis-[{CpЈTaCl(µ-PMes)}2] (5)
In these reactions, the lithium reagent acts as a reducing
Single crystals of 1؊5 were obtained from concentrated
agent, base and substitution reagent. The products of these solutions in diethyl ether (1, 3), pentane (2) or hexane (4a,b,
reactions, that is, the oxidation product P2H2R2, the free 5) at 5 °C. The trans complexes 1؊3 crystallise in the mono-
phosphane RPH2, and the corresponding TaIV phosphin- clinic space group P21/n, 4b in the monoclinic space group
idene complex were detected by 31P NMR spectroscopy.
The formation of 1؊4b was also observed when only one plexes 4a and 5 crystallise in the triclinic space group P1
equivalent of LiPHR was used, but the yield was lower. with two formula units in the unit cell (Table 2). The unit
P21/c and have two formula units per unit cell; the cis com-
¯
Table 1. Comparison of the 31P NMR spectroscopic data of compounds 1؊5 and [(CpЈTaCl{µ-P(Tipp)})2] (I)[3] (NMR in C6D6) with
the 31P{1H} NMR spectroscopic data of the corresponding primary phosphanes
1 (trans)
R ϭ Cy
437.6
2 (trans)
R ϭ tBu
482.0
3 (trans)
R ϭ Ph
403.9
4a (cis)
R ϭ Mes
399.0
4b (trans)
R ϭ Mes
390.3
5 (cis)
R ϭ Mes
396.0
I (trans)
δ(31P, ppm)
391.5
PH2Cy[39]
Ϫ111.3
PH2Bu[36b]
Ϫ80.5
PH2Ph[36b]
Ϫ122.1
PH2Mes[36b,40,41]
Ϫ153.8
PH2Mes[36b,40,41]
Ϫ153.8
PH2Mes[36b,40,41]
Ϫ153.8
PH2(Tipp)[36b]
Ϫ158.2
δ(31P, ppm)
∆ δ
549.0
562.4
526.0
552.8
544.1
549.8
549.7
2976
Eur. J. Inorg. Chem. 2002, 2975Ϫ2984

Organometallic Tantalum(IV) Phosphinidene Complexes
FULL PAPER
Table 2. Crystal data and structure refinement for 1؊8
Eur. J. Inorg. Chem. 2002, 2975Ϫ2984
2977

S. Blaurock, E. Hey-Hawkins
FULL PAPER
cell of 1 contains four noninteracting diethyl ether molec-
ules, and that of 4a two hexane molecules.
The pronounced tendency of TaIV to form binuclear com-
plexes is also evident in the molecular structures of 1؊5.
The trans complexes 1؊4b are centrosymmetric dimers in
which two Ta atoms are bound by two bridging phosphin-
idene [PCy (1) (Figure 1), PtBu (2) (Figure 2), PPh (3) (Fig-
ure 3), PMes (Figure 4)] groups. Each Ta atom also bears
a terminal chloro ligand, and a Cp* ligand completes the
coordination sphere of the Ta atom (Table 3). The four-
membered metallacycles TaϪPϪTaЈϪPЈ are planar and al-
most square (the centres of the planar Ta2P2 rings in 1؊4b
coincide with crystallographic inversion centres); this indic-
ates substantial pπ -dπ backbonding (PǞ Ta) of the phos-
phorus lone pair. Complex I exhibits comparable struc-
tural parameters.[3]
Figure 2. Molecular structure of trans-[{Cp*TaCl(µ-PtBu)}2] (2)
showing the atom numbering scheme employed (ORTEP plot, 50%
probability, SHELXTL PLUS; XP[37]). Hydrogen atoms are omit-
ted for clarity.
Figure 1. Molecular structure of trans-[{Cp*TaCl(µ-PCy)}2] (1)
showing the atom numbering scheme employed (ORTEP plot, 50%
probability, SHELXTL PLUS; XP[37]). Hydrogen atoms are omit-
ted for clarity.
In the cis complexes 4a (Figure 5) and 5 (Figure 6), a
butterfly-type central Ta2P2 ring is observed [dihedral angle
for 4a: Ta(1)ϪP(1)ϪTa(2)/Ta(1)ϪP(2)ϪTa(2) 27.61(6)°, 5:
Ta(1)ϪP(1)ϪTa(2)/Ta(1)ϪP(2)ϪTa(2) 10.4(2)°]. Due to
geometric requirements, the aryl rings in 4a are almost per-
pendicular to the Ta2P planes [dihedral angles 89.9(4)° and
88.9(4)°]. This structure is also retained in solution, as in-
Figure 3. Molecular structure of trans-[{Cp*TaCl(µ-PPh)}2] (3)
showing the atom numbering scheme employed (ORTEP plot, 50%
probability, SHELXTL PLUS; XP[37]). Hydrogen atoms are omit-
ted for clarity.
dicated by two signals for the nonequivalent meta-H atoms
Complexes 1؊5 are diamagnetic, thus the presence of a
1
(1H NMR) and the ortho-methyl groups in the H and 13C TaϪTa single bond can be assumed. For other dimeric com-
NMR spectra. In 5, both mesityl rings are also almost per- plexes it was observed that the TaϪTa bond length[19] is
pendicular to the Ta2P planes [dihedral angles 86.6(4)° for strongly dependent on the number and type of ligands (e.g.,
P(2)-mesityl and 73.8(4)° for P(1)-mesityl]. However, in this hydrido-bridged complexes generally have shorter TaϪTa
case free rotation around the PϪCipso(Mes) bond is possible bonds than comparable halogen-bridged complexes[20]). A
˚
in solution, as indicated by the presence of only one broad comparable value of 3.165
A
was observed for
signal for the equivalent meta-H atoms and the ortho- [{TaCl3(SMe2)(µ-SPh)}2],[21] in which a TaϪTa single bond
methyl groups (1H NMR).
2978
is present according to theoretical calculations.[22]
Eur. J. Inorg. Chem. 2002, 2975Ϫ2984

Organometallic Tantalum(IV) Phosphinidene Complexes
FULL PAPER
Figure 5. Molecular structure of cis-[{Cp*TaCl(µ-PMes)}2] (4a)
showing the atom numbering scheme employed (ORTEP plot, 50%
probability, SHELXTL PLUS; XP[37]). Hydrogen atoms are omit-
ted for clarity.
Figure 4. Molecular structure of trans-[{Cp*TaCl(µ-PMes)}2] (4b)
showing the atom numbering scheme employed (ORTEP plot, 50%
probability, SHELXTL PLUS; XP[37]). Hydrogen atoms are omit-
ted for clarity.
˚
Table 3. Selected bond lengths [A] and angles [°] of compounds
1؊5 and [(CpЈTaCl{µ-P(Tipp)})2] (I)[3]
Compound
TaϪP
TaϪTa
TaϪCl
TaϪPϪTa
PϪTaϪP
1
2.334(2), 2.336(2)
2.354(1), 2.357(1)
2.345(1), 2.344(1)
3 ϫ 2.344(2),
3.132(1)
2.358(2)
2.360(1)
2.357(1)
2.347(2), 2.352(2)
84.26(6)
84.78(4)
85.92(4)
82.31(5), 82.39(5)
95.74(6)
95.22(4)
94.08(4)
93.87(5), 94.00(5)
2
3.1759(8)
3.1957(6)
3.0881(3)
3
4a
2.349(1)
4b
5
2.328(2), 2.331(2)
2.348(3), 2.358(3)
2.336(3), 2.357(3)
2.317(6), 2.338(2)
3.0773(5)
3.1253(7)
2.364(2)
2.351(3), 2.365(3)
82.68(7)
83.0(1),
83.7(1)
97.32(7)
95.9(1), 96.3(1)
I
3.100(3)
2.350(2)
83.51(8)
96.49(8)
The TaϪP bond lengths in 1؊5 are similar to those of (sum of bond angles ca. 360°) indicates that the PR group
I[3] (Table 3) and the terminal phosphinidene complex acts as a three-electron donor. In the cis complexes 4a and
[(tBu3SiO)3TaϭPPh][5] [2.317(4) A] with a bent TaPC ar- 5, the P atoms also have a trigonal-planar environment
˚
rangement
[TaϪPϪC
110.2(4)°],
while [sum of bond angles 4a: P(1): 358.0(2)°, P(2): 357.8(2)°, 5:
[N{CH2CH2N(SiMe3)}3TaϭPCy][6] has a linear TaPC ar- P(1): 356.8(4)°, P(2): 358.8(4)°].
˚
rangement and a shorter TaϪP bond of 2.145(7) A. How-
The TaϪCl bonds in 1؊5 (Table 3) are shorter than those
ever, all these distances are shorter than the sum of the co- in the Ta chloro phosphane complexes (e.g., [{TaCl2(µ-
[23]
˚
valent radii of Ta and P (2.44 A). Longer bonds are ob- Cl)(µ-PMe2CH2PMe2)}2], TaϪCl (terminal) 2.435(7),
[24]
˚
served for bridging phosphanido ligands (e.g., 2.457(6) A;
[{CpЈTa(PPh2)(µ-PPh2)}2], TaϪPbr 2.486(2), 2.458(2) A].
trans-[CpTaCl2(CO)(PMe2Ph)2], TaϪCl
[3]
[25]
˚
˚
2.518(4), 2.539(4) A; [Cp*TaCl3(PMe3)], TaϪCl 2.395(3)
[26]
˚
The trigonal-planar geometry of the P atoms of the to 2.416(3) A;
cis-[Cp*TaCl2(CO)2(PMe3)], TaϪCl
bridging phosphinidene group in the trans complexes 1؊4b 2.504(2), 2.512(2) A[26]).
˚
Eur. J. Inorg. Chem. 2002, 2975Ϫ2984
2979

S. Blaurock, E. Hey-Hawkins
FULL PAPER
Complex 6 crystallises as yellow prismatic crystals in the
monoclinic space group P21/n with four molecules of acet-
one in the unit cell. The central structural fragment is a
Ta3O4 cluster, in which the TaV and O atoms alternatingly
occupy the corners of a heterocubane with one missing cor-
ner (Figure 7). Related clusters have been reported for Zr,
Nb, Ta and Mo.[28] Each Ta atom is coordinated by a Cp*
and one terminal chloro ligand. Two Ta atoms have a coor-
dination number of six [Ta(1) and Ta(2)]; Ta(3) is five-co-
ordinate. The TaϪTa distances range from 3.1185(3) to
˚
3.3378(3) A. There are two types of O atoms: one triply-
bridging [O(6)] and three doubly-bridging oxo ligands
˚
[O(3), O(4), and O(5); TaϪO 1.910(3) to 2.003(3) A].
The latter TaϪO bond lengths are in the range for single
bonds,[28a,28b] while the TaϪO(6) bond lengths differ by
Figure 6. Molecular structure of cis-[{CpЈTaCl(µ-PMes)}2] (5)
showing the atom numbering scheme employed (ORTEP plot, 50%
probability, SHELXTL PLUS; XP[37]). Hydrogen atoms are omit-
ted for clarity.
Reactivity of 1, 3 and 4
While terminal electrophilic phosphinidene complexes
are highly reactive,[27] 1؊5 are air-stable as solids for at least
several hours. 1, 3 and 4b also exhibit a remarkable stability
towards acetone, benzophenone, acetonitrile, CS2 (1 and 3),
acetaldehyde (4b), or EtAlCl2 (3), even at elevated temper-
atures.
Complex 3 reacts with moist acetone (50-fold excess) in
the presence of traces of air to give the trinuclear cluster
[{Cp*TaCl(µ2-O)}3(µ3-O)(µ-O2PHPh)}] (6) in very low
yield (Scheme 2). 6 was only characterised by crystal struc-
ture determination.
Figure 7. Molecular structure of [{Cp*TaCl(µ2-O)}3(µ3-O)(µ2-
O2PHPh)}] (6) showing the atom numbering scheme employed
(ORTEP plot, 50% probability, SHELXTL PLUS; XP[37]). Hydro-
˚
gen atoms are omitted for clarity. Bond lengths [A] and angles [°]:
Ta(1)ϪO(4) 1.960(3), Ta(1)ϪO(3) 1.991(3), Ta(1)ϪO(1) 2.127(3),
Ta(1)ϪO(6) 2.148(3), Ta(2)ϪO(5) 1.964(3), Ta(2)ϪO(3) 2.003(3),
Ta(2)ϪO(2) 2.117(3), Ta(2)ϪO(6) 2.136(3), Ta(3)ϪO(5) 1.910(3),
Ta(3)ϪO(4) 1.915(3), Ta(3)ϪO(6) 2.058(3), Ta(1)ϪCl(1) 2.506(1),
Ta(2)ϪCl(2) 2.491(1), Ta(3)ϪCl(3) 2.429(1), Ta(1)ϪTa(3)
3.1185(3), Ta(1)ϪTa(2) 3.3378(3), Ta(2)ϪTa(3) 3.1206(3),
P(1)ϪO(1) 1.510(4), P(1)ϪO(2) 1.514(4), P(1)ϪC(31) 1.778(6);
O(4)ϪTa(1)ϪO(3)
O(3)ϪTa(1)ϪO(1)
O(3)ϪTa(1)ϪO(6)
O(4)ϪTa(1)ϪCl(1)
O(1)ϪTa(1)ϪCl(1)
O(5)ϪTa(2)ϪO(3)
O(3)ϪTa(2)ϪO(2)
O(3)ϪTa(2)ϪO(6)
O(5)ϪTa(2)ϪCl(2)
O(2)ϪTa(2)ϪCl(2)
O(5)ϪTa(3)ϪO(6)
O(5)ϪTa(3)ϪCl(3)
O(6)ϪTa(3)ϪCl(3)
O(1)ϪP(1)ϪC(31)
P(1)ϪO(1)ϪTa(1)
Ta(1)ϪO(3)ϪTa(2)
Ta(3)ϪO(5)ϪTa(2)
Ta(3)ϪO(6)ϪTa(1)
98.6(1),
86.6(1),
71.2(1),
86.9(1),
77.1(1),
97.7(1),
86.2(1),
71.2(1),
87.6(1),
77.5(1),
76.9(1),
86.0(1),
136.68(9),
109.4(3),
123.7(2),
113.4(2),
107.3(2),
95.7(1),
O(4)ϪTa(1)ϪO(1)
O(4)ϪTa(1)ϪO(6)
O(1)ϪTa(1)ϪO(6)
O(3)ϪTa(1)ϪCl(1)
O(6)ϪTa(1)ϪCl(1)
O(5)ϪTa(2)ϪO(2)
O(5)ϪTa(2)ϪO(6)
O(2)ϪTa(2)ϪO(6)
O(3)ϪTa(2)ϪCl(2)
O(6)ϪTa(2)ϪCl(2)
O(4)ϪTa(3)ϪO(6)
O(4)ϪTa(3)ϪCl(3)
O(1)ϪP(1)ϪO(2)
O(2)ϪP(1)ϪC(31)
P(1)ϪO(2)ϪTa(2)
Ta(3)ϪO(4)ϪTa(1)
Ta(3)ϪO(6)ϪTa(2)
Ta(2)ϪO(6)ϪTa(1)
155.9(1),
74.0(1),
85.7(1),
148.8(1),
81.05(9),
156.1(1),
74.0(1),
85.1(1),
148.7(1),
80.91(9),
77.0(1),
85.4(1),
112.5(2),
109.2(2),
124.8(2),
107.2(2),
96.1(1),
102.4(1),
Scheme 2
2980
C(36)ϪC(31)ϪP(1) 122.1(5), C(32)ϪC(31)ϪP(1) 120.0(5).
Eur. J. Inorg. Chem. 2002, 2975Ϫ2984

Organometallic Tantalum(IV) Phosphinidene Complexes
FULL PAPER
˚
ca. 0.1 A [Ta(3)ϪO(6) 2.058(3), Ta(1)ϪO(6) 2.148(3), by crystal structure determination. A molecular ion peak
˚
Ta(2)ϪO(6) 2.136(3) A]. For Ta(1) and Ta(2), the trans ef- was observed for the cation in 7 by FAB-MS (3-nitrobenzal-
fect of the Cp* ligand apparently affects the TaϪO bond dehyde as matrix) at m/z ϭ 786. In the 31P NMR spectrum
lengths. Similar structural data were found for [(Cp* of the reaction mixture, signals for the oxidation products
TaCl)3(µ2-Cl)(µ2ϪO)2(µ3-O)(µ-O2SitBu2)].[28b]
(PPh)n (n ϭ 4Ϫ6)[29] were observed. In addition, two doub-
Ϫ
In addition, a P(H)(Ph)O2 ligand, the anion of phenyl lets (δ ϭ Ϫ57.8 ppm and Ϫ121.4 ppm, 1JPP ϭ 311 Hz) were
phosphinic acid, bridges Ta(1) and Ta(2). However, the PH observed, which we could not assign.
proton could not be localised. Due to the small amount of
Complex 7 crystallises as orange rhombic crystals from
6 available, no 31P NMR spectrum could be obtained to THF in the monoclinic space group P21/n. In the cation
verify the presence of the PH proton. However, since tan- (Figure 8), the NC group occupies the axial position in
talum(v) is present in this cluster, the presence of an anionic three of the four cyclohexyl groups of the isocyanide li-
Ϫ
P(H)(Ph)O2 ligand must be assumed. The PϪO bond gands. The reason for this unexpected arrangement is the
[28f]
˚
lengths indicate multiple bond character (ca. 1.51 A).
formation of hydrogen bonds between the hydrogen atom
While no reaction of 3 with one or two equivalents of of the α-C atom C(26) of the isocyanide ligand in which the
CyNC was observed, a 10-fold excess of CyNC gave the NC group is in the equatorial position and the hydrogen
tantalum() complex [Cp*TaCl(CNCy)4]Cl (7) (Scheme 3), atom on the β-C atom of an isocyanide ligand of a second
which was characterised by 1H, 13C NMR spectroscopy and molecule to a chloride anion (Figure 9). However, in solu-
tion the four isocyanide ligands are equivalent (13C NMR).
Scheme 3
Figure 9. Hydrogen bonding in [Cp*TaCl(CNCy)4]Cl (7) (ORTEP
plot, 50% probability, SHELXTL PLUS; XP[37]).
For the TaCN group, two mesomeric structures can be
formulated (as for carbonyl groups):
Figure 8. Molecular structure of [Cp*TaCl(CNCy)4]Cl (7) showing
the atom numbering scheme employed (ORTEP plot, 50% probab-
ility, SHELXTL PLUS; XP[37]). Only the cation is shown. Hydro-
˚
gen atoms are omitted for clarity; selected bond lengths [A] and
angles [°]: Ta(1)ϪC(11) 2.179(4), Ta(1)ϪC(32) 2.185(4),
Ta(1)ϪC(18) 2.187(4), Ta(1)ϪC(25) 2.187(4), Ta(1)ϪCl(1)
2.5146(9), N(1)ϪC(11) 1.151(5), N(1)ϪC(12) 1.460(5), N(2)ϪC(18)
1.147(5), N(2)ϪC(19) 1.452(5), N(3)ϪC(25) 1.154(5), N(3)ϪC(26)
1.452(5),
N(4)ϪC(32)
1.152(5),
N(4)ϪC(33)
1.459(5);
C(11)ϪTa(1)ϪC(32) 84.69(13), C(11)ϪTa(1)ϪC(18) 87.54(14),
C(32)ϪTa(1)ϪC(18) 153.37(13), C(11)ϪTa(1)ϪC(25) 153.23(13),
C(32)ϪTa(1)ϪC(25) 86.15(13), C(18)ϪTa(1)ϪC(25) 89.51(14),
C(11)ϪTa(1)ϪCl(1) 76.99(10), C(32)ϪTa(1)ϪCl(1) 76.98(10),
C(18)ϪTa(1)ϪCl(1) 76.46(10), C(25)ϪTa(1)ϪCl(1) 76.45(10),
C(11)ϪN(1)ϪC(12) 165.6(4), C(18)ϪN(2)ϪC(19) 166.5(4),
C(25)ϪN(3)ϪC(26) 174.6(4), C(32)ϪN(4)ϪC(33) 175.5(4),
N(1)ϪC(11)ϪTa(1)
176.1(3),
N(2)ϪC(18)ϪTa(1) 176.0(3),
N(3)ϪC(25)ϪTa(1) 177.2(3), N(4)ϪC(32)ϪTa(1) 177.7(3).
Scheme 4
Eur. J. Inorg. Chem. 2002, 2975Ϫ2984
2981

S. Blaurock, E. Hey-Hawkins
FULL PAPER
act with P2H2R2 (formed in the redox reaction which gives
1) to yield the observed product (Scheme 4).
Complex 8 crystallises in the monoclinic space group Cc.
In 8, two Cp*TaCl2 fragments are bridged by one oxo li-
gand and a diphosphanediyl group P2Cy22Ϫ; this indicates
the presence of TaV (Figure 10). In general, free diphos-
phenes P2R2 are only stable when sterically demanding R
groups are present;[31] however, unstable derivatives can be
stabilised by coordination to a transition metal.[32] The
TaϪP bond lengths [Ta(2)ϪP(1) 2.580(2), Ta(2)ϪP(2)
˚
2.600(2), Ta(1)ϪP(2) 2.578(2), Ta(1)ϪP(1) 2.602(2) A] are
in the range observed for other tantalum diphosphene com-
[32]
˚
plexes [2.602(5) to 2.632(5) A].
˚
In 8, the P(1)ϪP(2) bond length of 2.188(3) A indicates
a single bond. In the tantalum diphosphene complexes
[Cp2TaH(η2-P2R2)] (R ϭ Cy, H) the PϪP bond lengths are
[30]
˚
shorter [2.131(3) and 2.136(6) A].
Experimental Section
Figure 10. Molecular structure of [(Cp*TaCl2)2(µ2-O)(η2,µ2-
P2Cy2)] (8) showing the atom numbering scheme employed (OR-
TEP plot, 50% probability, SHELXTL PLUS; XP[37]). Hydrogen All experiments were carried out under purified dry argon. Solvents
˚
atoms are omitted for clarity. Bond lengths [A] and angles [°]:
Ta(2)ϪO(1) 1.974(6), Ta(2)ϪCl(3) 2.413(2), Ta(2)ϪCl(4) 2.425(2),
Ta(2)ϪP(1) 2.580(2), Ta(2)ϪP(2) 2.600(2), Ta(1)ϪO(1) 1.978(6),
Ta(1)ϪCl(2) 2.407(2), Ta(1)ϪCl(1) 2.413(2), Ta(1)ϪP(2) 2.578(2),
were dried and freshly distilled under argon. The NMR spectra
were recorded with an AVANCE DRX 400 spectrometer (Bruker),
1H NMR: internal standard solvent (benzene or CDCl3), external
Ta(1)ϪP(1) 2.602(2), P(1)ϪC(21) 1.884(9), P(1)ϪP(2) 2.188(3), standard SiMe4. 13C NMR: external standard SiMe4, internal
standard solvent. 31P NMR: external standard 85% H3PO4. The IR
spectra were recorded with a FT-IR spectrometer PerkinϪElmer
System 2000 in the range 350Ϫ4000 cmϪ1. UV/Vis spectra were
P(2)ϪC(27)
1.864(9);
O(1)ϪTa(2)ϪCl(3)
94.31(18),
O(1)ϪTa(2)ϪCl(4) 148.73(17), Cl(3)ϪTa(2)ϪCl(4) 88.86(9),
O(1)ϪTa(2)ϪP(1)
Cl(4)ϪTa(2)ϪP(1)
Cl(3)ϪTa(2)ϪP(2)
P(1)ϪTa(2)ϪP(2)
69.02(17),
88.01(8),
88.14(8),
49.97(8),
Cl(3)ϪTa(2)ϪP(1)
O(1)ϪTa(2)ϪP(2)
Cl(4)ϪTa(2)ϪP(2)
O(1)ϪTa(1)ϪCl(2)
137.96(8),
67.73(17),
81.33(8), recorded in pentane with a LAMBDA 900 (PerkinϪElmer) in an
94.81(17),
inert-gas cuvette. The melting points were determined in sealed ca-
pillaries under argon and are uncorrected. LiPHCy,[11] LiPHtBu,[12]
LiPHPh,[13] LiPHMes,[14] [CpЈTaCl4][16] and [Cp*TaCl4][10] were
O(1)ϪTa(1)ϪCl(1) 148.85(16), Cl(2)ϪTa(1)ϪCl(1) 90.28(8),
O(1)ϪTa(1)ϪP(2)
Cl(1)ϪTa(1)ϪP(2)
Cl(2)ϪTa(1)ϪP(1)
P(2)ϪTa(1)ϪP(1)
C(21)ϪP(1)ϪTa(2)
C(21)ϪP(1)ϪTa(1)
Ta(2)ϪP(1)ϪTa(1)
C(27)ϪP(2)ϪTa(1)
C(27)ϪP(2)ϪTa(2)
68.17(17),
87.57(7),
87.88(8),
49.97(8),
138.1(3),
131.2(3),
87.02(7),
138.2(3),
131.0(3),
Cl(2)ϪTa(1)ϪP(2)
O(1)ϪTa(1)ϪP(1)
Cl(1)ϪTa(1)ϪP(1)
C(21)ϪP(1)ϪP(2)
P(2)ϪP(1)ϪTa(2)
P(2)ϪP(1)ϪTa(1)
C(27)ϪP(2)ϪP(1)
P(1)ϪP(2)ϪTa(1)
P(1)ϪP(2)ϪTa(2)
137.60(8),
68.49(16),
81.04(8), prepared by literature procedures.
111.3(4),
General Procedure for the Preparation of trans-[{Cp*TaCl(µ-PR)}2]
65.49(9),
64.45(9),
111.2(3),
65.57(9),
64.55(9),
[R ؍ Cy (1), tBu (2), Ph (3), Mes (4b)]: A suspension of [Cp*TaCl4]
in toluene (30 mL) was cooled to Ϫ70 °C, and two equivalents of
LiPHR were added to the stirred reaction mixture over 2 h. The
resulting suspension was slowly warmed to room temperature and
stirred overnight. The solvent was removed and the solid dissolved
in diethyl ether (1, 3), pentane (2), or hexane (4b). The mixture was
filtered. Deep red crystals were obtained by cooling the filtrate to
5 °C.
Ta(1)ϪP(2)ϪTa(2) 87.10(7), Ta(2)ϪO(1)ϪTa(1) 129.1(3).
As the TaϪC bond lengths of the isocyanide ligands
˚
[2.179(4) to 2.187(4) A] are in the range of TaϪC single
bonds and the CϪNϪC(Cy) groups are almost linear
[165.6(4)° to 175.5(4)°], mesomeric structure A can be as-
The TaIV phosphinidene complex (Table 1) and the oxidation prod-
ucts P2H2R2 (or their decomposition products: cyclic oligophos-
phanes and the free phosphane RPH2) were detected by 31P NMR
spectroscopy. The following signals were observed for the oxida-
tion products:
˚
sumed. The Ta atom is located 0.502(2) A above the plane
of the four isocyanide carbon atoms.
As a minor product, [(Cp*TaCl2)2(µ2-O)(η2,µ2ϪP2Cy2)]
(8) was also obtained in the reaction of [Cp*TaCl4] with one
equivalent of LiPHCy. 8 was only characterised by crystal
structure determination; in the 31P NMR spectrum of the
reaction mixture a singlet of low intensity at δ ϭ 538.6 ppm
was observed, which could be attributed to 8 or a precursor
complex thereof. As two doublets are observed in the high-
field region of the 31P NMR spectrum of [Cp2TaH(η2-
P2R2)] (R ϭ Ph:[2a,30] δ ϭ Ϫ145.1 ppm and Ϫ162.8 ppm,
R ϭ Cy:[30] δ ϭ Ϫ123.1 ppm and Ϫ143.3 ppm) the latter
seems more likely.
tBu: δ ϭ Ϫ57.5 ppm [s, (PtBu)4],[29] Ϫ71.7 (d) and Ϫ108.0 (t)
(PtBu)3 ppm.[33]
Cy: δ ϭϪ68.3 (s, PCy)4, Ϫ84.3 and Ϫ87.5 (m, rac- and meso-
P2H2Cy2),[29] Ϫ111.0 (t, PH2Cy) ppm.
Ph: δ ϭ ca. 3 [m, (PPh)5], Ϫ21.3 [s, (PPh)6], Ϫ47.6 [s, (PPh)4][29,34]
Ϫ67.4, Ϫ70.9 (m, meso- and rac-P2H2Ph2; the signal for the un-
stable diphosphane disappears after two days),[35,36] Ϫ122.1 (t,
PH2Ph) ppm.
Mes: δ ϭϪ43.2 [s, (PMes)4], Ϫ109.3 (d), Ϫ143.9 (t) (PMes)3,
Ϫ110.4, Ϫ117.5 (m, meso- and rac-P2H2Mes2), Ϫ153.8 (t,
A possible route for the formation of 8 is hydrolysis of
[Cp*TaCl4] to give [(Cp*TaCl3)2(µ-O)], which can then re- PH2Mes) ppm.
2982
Eur. J. Inorg. Chem. 2002, 2975Ϫ2984

Organometallic Tantalum(IV) Phosphinidene Complexes
FULL PAPER
1: (0.45 g, 0.98 mmol) [Cp*TaCl4], (0.48 g, 1.96 mmol) LiPHCy,
room temperature and stirred overnight. The solvent was removed
rhombohedral deep red crystals of 1·2 Et2O, yield: 0.40 g (81% rel. in vacuo, and the solid recrystallised twice from n-hexane. Yield:
[Cp*TaCl4]), m.p. 319 °C (dec.). 1H NMR (400 MHz, C6D6, 25 0.19 g (43.5% rel. LiPHMes), rhombohedral orange-red crystals;
3
°C): δ ϭ 1.12 [t, JH,H ϭ 7.0 Hz, 6 H, CH3 in ether], 1.38 (m, 4 H, m.p. 276 °C (dec.). 1H NMR (400 MHz, C6D6, 25 °C): δ ϭ 2.00
4-H in Cy), 1.46 (m, 8 H, 3-H/5-H in Cy), 1.76 (m, 8 H, 2-H/6-H
(s, 6 H, C5MeH4), 2.34 (s, 6 H, p-Me in Mes), 2.49 (br, 12 H, o-
in Cy), 2.00 (m, 2 H, 1-H in Cy), 2.20 (s, 30 H, CH3 in Cp*), Me in Mes), 5.72 (t, JH,H ϭ 2.6 Hz, 4 H, C5MeH4), 6.27 (t, JH,H ϭ
3
3.27 [q, JH,H ϭ 7.0 Hz, 4 H, CH2 in ether] ppm. 13C{1H} NMR 2.6 Hz, 4 H, C5MeH4), 6.64 (br, 4 H, m-H in Mes) ppm.
(100.61 MHz, C6D6, 25 °C): δ ϭ 14.0 (CH3 in C5Me5), 16.2 (CH3
C30H36Cl2P2Ta2 (891.33): C 40.4, H 4.1, Cl 8.0; found C 40.6, H
3
in ether), 27.5 (C-4 in Cy), 30.0 [d, JP,C ϭ 19 Hz; C-3/C-5 in Cy], 4.2, Cl 7.7.
2
35.9 [d, JP,C ϭ 79 Hz; C-2/C-6 in Cy], 52.1 (br; C-1 in Cy), 66.6
Synthesis of [Cp*TaCl(CNCy)4]Cl (7): Cyclohexyl isocyanide
(CH2 in ether), 114.9 (C5Me5) ppm. Solvent-free 1, C32H52Cl2P2Ta2
(931.51): C 41.3, H 5.6, Cl 7.6; found C 40.4, H 5.3, Cl 7.2.
(0.17 g, 1.6 mmol) was added to a solution of 3 (0.15 g, 0.16 mmol)
in toluene (20 mL). Over 3 days, the red solution turned orange.
The solvent was removed under vacuum, and the solid recrys-
tallised from THF to give 7 as rhombic orange crystals (0.10 g,
2: (0.40 g, 0.87 mmol) [Cp*TaCl4], (0.17 g, 1.77 mmol) LiPHtBu,
yield: 0.33 g (86% rel. [Cp*TaCl4]), m.p. 341 °C (dec.), prismatic
1
1
38% rel. to 3); m.p. 345 °C (dec.). H NMR (400 MHz, CDCl3, 25
deep red crystals. H NMR (400 MHz, C6D6, 25 °C): δ ϭ 1.48 [d,
3JP,H ϭ 14 Hz, 18 H, tBu], 2.18 (s, 30 H, CH3 in Cp*) ppm.
13C{1H} NMR (100.61 MHz, C6D6, 25 °C): δ ϭ 14.8 (CH3 in
C5Me5), 35.1 [C(CH3)3], 35.6 [C(CH3)3], 116.4 (C5Me5) ppm.
C28H48Cl2P2Ta2 (879.40): calcd. C 38.3, H 5.5, Cl 8.1; found C
38.8, H 5.6, Cl 8.1.
°C): δ ϭ ca. 1.3 (m, 24 H, 3-H, 4-H, 5-H in Cy), ca. 1.7 (m, 16 H,
2-H, 6-H in Cy), 2.29 (s, 15 H, CH3 in Cp*), 4.45 (br, 4 H, 1-H in
Cy) ppm. 13C{1H} NMR (100.61 MHz, CDCl3, 25 °C): δ ϭ 13.7
(CH3 in C5Me5), 23.5 (C-4 in Cy), 26.1 (C-3 and C-5 in Cy), 33.5
(C-2 and C-6 in Cy), 55.4 (C-1 in Cy), 70.3 (CNCy) 102.2 (C5Me5)
ppm. C38H59Cl2N4Ta (823.74): C 55.4, H 7.2, Cl 8.6; found C 55.0,
H 7.8, Cl 8.4.
3: (0.50 g, 1.09 mmol) [Cp*TaCl4], (0.25 g, 2.20 mmol) LiPHPh,
yield: 0.42 g (85% rel. [Cp*TaCl4]), m.p. 341 °C (dec.), rhombo-
1
Data Collection and Structural Refinement of 1؊8: Details of the
hedral deep red crystals. H NMR (400 MHz, C6D6, 25 °C): δ ϭ
data collection and crystal structure refinement are summarised in
2.03 (s, 30 H, CH3 in Cp*), 6.97 (br, 2 H, p-H in Ph), 7.36 [pseudo
3
3
3
˚
Table 2. Data (Mo-Kα , λ ϭ 0.71073 A) were collected with a Sie-
t, JH,H ϭ 14, JP,H ϭ 14 Hz, 4 H, o-H in Ph], 8.17 [t, JH,H
ϭ
14 Hz, 4 H, m-H in Ph] ppm. 13C{1H} NMR (100.61 MHz, C6D6,
25 °C): δ ϭ 13.6 (CH3 in C5Me5), 115.3 (C5Me5), 129.7 (p-C in
Ph), 125.2 (m-C in Ph), 136.0 (o-C in Ph), 148.6 (ipso-C in Ph)
ppm. C32H40Cl2P2Ta2 (919.38): calcd. Cl 7.7; found Cl 8.1.
mens CCD (SMART). All observed reflections were used for deter-
mination of the unit cell parameters. The structures were solved by
direct methods (SHELXTL PLUS[37]) and subsequent difference
Fourier syntheses and refined by full-matrix least-squares on F2
(SHELXTL PLUS[37]). Restrictions for 1؊8: Ta, Cl, C, O, N and
P atoms anisotropic, H atoms located or in calculated positions
4b: (0.40 g, 0.87 mmol) [Cp*TaCl4], (0.28 g, 1.8 mmol) LiPHMes,
yield: 0.32 g (73% rel. [Cp*TaCl4]), m.p. 321 °C (dec.), rhombo-
and refined isotropically. Absorption correction with SADABS[38]
.
1
hedral deep red crystals. H NMR (400 MHz, C6D6, 25 °C): δ ϭ
CCDC-181631 (1), Ϫ181629 (2), Ϫ181627 (3),- 181633 (4a),
Ϫ181635 (4b), Ϫ181632 (5), Ϫ181630 (6), Ϫ181628 (7) and CCDC-
181634 (8) contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge at
www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge
Crystallographic Data Centre, 12, Union Road, Cambridge
CB2 1EZ, UK; Fax: (internat.) ϩ44-1223/336-033; E-mail:
deposit@ccdc.cam.ac.uk].
2.01 (s, 30 H, CH3 in Cp*), 2.22 (s, 6 H, p-Me in Mes), 2.72 (s, 12
H, o-Me in Mes), 7.01 (s, 4 H, m-H in Mes) ppm. 13C{1H} NMR
(100.61 MHz, C6D6, 25 °C): δ ϭ 13.3 (CH3 in C5Me5), 22.0 (p-Me
in Mes), 25.9 (o-Me in Mes), 115.2 (C5Me5), 130.5 (m-C in Mes),
132.9 (p-C in Mes), 139.4 (o-C in Mes), 144.8 (ipso-C in Mes) ppm.
C38H52Cl2P2Ta2 (1003.54): calcd. C 45.5, H 5.2; Cl 7.1; found C
45.9, H 5.4, Cl 7.0.
Synthesis of cis-[{Cp*TaCl(µ-PMes)}2] (4a): A suspension of one
equivalent of [Cp*TaCl4] (0.5 g, 1.09 mmol) in toluene (30 mL) was
cooled to Ϫ70 °C, and one equivalent of LiPHMes (0.17 g,
1.09 mmol) was added to the stirred reaction mixture over 3 h. The
resulting suspension was stirred at Ϫ70 °C for 2 h, and then slowly
warmed to room temperature and stirred overnight. The solvent
was removed under vacuum, and the solid recrystallised twice from
n-hexane. Yield: 80 mg (29% rel. LiPHMes); m.p. 289 °C (dec.). 1H
NMR (400 MHz, C6D6, 25 °C): δ ϭ 2.05 (s, 30 H, CH3 in Cp*),
2.26 (s, 6 H, p-Me in Mes), 2.39 (s, 6 H, o-Me in Mes), 2.56 (s, 6
H, o-Me in Mes), 6.91 (s, 2 H, m-H in Mes), 6.97 (s, 2 H, m-H in
Mes) ppm. 13C{1H} NMR (100.61 MHz, C6D6, 25 °C): δ ϭ 12.9
(CH3 in C5Me5), 21.8 (p-Me in Mes), 23.1 (o-Me in Mes), 24.3 (o-
Me in Mes), 115.5 (C5Me5), 128.0 (m-C in Mes), 130.9 (m-C in
Mes),139.7 (p-C in Mes), 142.1 (o-C in Mes), 145.7 (o-C in Mes),
149.3 (ipso-C in Mes) ppm. C38H52Cl2P2Ta2 (1003.54): calcd. C
45.5, H 5.2; Cl 7.1; found C 45.8, H 6.0, Cl 6.8.
Acknowledgments
We gratefully acknowledge support of this work by the Landesgra-
duiertenförderung Sachsen (scholarship for S. B.). We thank the
company H. C. Starck GmbH & Co. KG for a generous donation
of TaCl5.
[1]
Eds. E. W. Abel, F. G. A. Stone, G. Wilkinson, Comprehensive
Organometallic Chemistry II, Volumes 4 and 5, Pergamon
Press, 1995.
[2] [2a]
J. C. Leblanc, C. Mo¨ıse, J. Organomet. Chem. 1989, 364,
[2b]
C3ϪC4.
R. T. Baker, J. C. Calabrese, R. L. Harlow, I. D.
[2c]
Williams, Organometallics 1993, 12, 830Ϫ841.
G. I. Ni-
konov, L. G. Kuzmina, P. Mountford, D. A. Lemenovskii, Or-
ganometallics 1995, 14, 3588Ϫ3591. [2d] G. Bonnet, O. Lavastre,
[2e]
J. C. Leblanc, C. Mo¨ıse, New. J. Chem. 1988, 12, 551Ϫ552.
C. Poulard, G. Boni, P. Richard, C. Mo¨ıse, J. Chem. Soc., Dal-
[2f]
ton Trans. 1999, 2725Ϫ2730.
O. Lavastre, G. Bonnet, G.
Synthesis of cis-[{CpЈTaCl(µ-PMes)}2] (5):
A suspension of
Boni, M. M. Kubicki, C. Mo¨ıse, J. Organomet. Chem. 1997,
[CpЈTaCl4] (0.4 g, 0.99 mmol) in toluene (20 mL) was cooled to
Ϫ70 °C, and one equivalent of LiPHMes (0.15 g, 0.98 mmol) was
added to the stirred reaction mixture over 3 h. The resulting sus-
pension was stirred at Ϫ70 °C for 2 h, and then slowly warmed to
[2g]
547, 141Ϫ147.
P. Sauvageot, O. Blacque, M. M. Kubicki,
S. Juge, C. Mo¨ıse, Organometallics 1996, 15, 2399Ϫ2403. [2h] S.
Challet, O. Lavastre, C. Mo¨ıse, J.-C. Leblanc, New J. Chem.
1994, 18, 1155Ϫ1161.
Eur. J. Inorg. Chem. 2002, 2975Ϫ2984
2983

S. Blaurock, E. Hey-Hawkins
FULL PAPER
[3]
[27g]
G. A. A. Hadi, K. Fromm, S. Blaurock, S. Jelonek, E. Hey-
2001, 7, 3551Ϫ3557.
M. J. M. Vlaar, A. W. Ehlers, F. J. J.
de Kanter, M. Schakel, A. L. Spek, M. lutz, N. Sigal, Y. Ape-
Hawkins, Polyhedron 1997, 16, 721Ϫ731.
P. J. Domaille, B. M. Foxmann, T. J. McNeese, S. S. Wreford,
[4]
loig, K. Lammertsma, Angew. Chem. 2000, 112, 4296Ϫ4299;
[27h]
J. Am. Chem. Soc. 1980, 102, 4114Ϫ4120.
J. B. Bonanno, P. T. Wolczanski, E. B. Lobkovsky, J. Am.
Angew. Chem. Int. Ed. 2000, 39, 4127Ϫ4130.
M. J. M.
[5]
Vlaar, F. J. J. de Kanter, M. Schakel, A. L. Spek, M. Lutz, K.
Lammertsma, J. Organomet. Chem. 2001, 617Ϫ618, 311Ϫ 317.
[27i] M. J. M. Vlaar, S. G. A. van Assema, F. J. J. de Kanter, M.
Chem. Soc. 1994, 116, 11159Ϫ11160.
C. C. Cummins, R. R. Schrock, W. M. Davis, Angew. Chem.
[6]
1993, 105, 758Ϫ761; Angew. Chem. Int. Ed. Engl. 1993, 32,
Schakel, A. L. Spek, M. Lutz, K. Lammertsma, Chem. Eur. J.
[27j]
756Ϫ759.
2002, 8, 58Ϫ65.
M. J. M. Vlaar, A. W. Ehlers, M. Schakel,
[7]
S. Blaurock, E. Hey-Hawkins, Z. Anorg. Allg. Chem., in press.
S. Blaurock, E. Hey-Hawkins, Z. Anorg. Allg. Chem. 2002,
628, 37Ϫ40.
M. Culmsee, T. Kruck, G. Meyer, M. S. Wickleder, Z. Anorg.
Allg. Chem. 2001, 627, 1111Ϫ1112.
R. D. Sanner, S. T. Carter, W. J. Bruton, Jr., J. Organomet.
S. B. Clendenning, J. F. Nixon, M. Lutz, A. L. Spek, K. Lam-
[8]
[27k]
mertsma, Chem. Eur. J. 2001, 7, 3545Ϫ3549.
J. B. M. Wit,
G. Th. van Eijkel, F. J. J. de Kanter, M. Schakel, A. W. Ehlers,
M. Lutz, A. L. Spek, K. Lammertsma, Tetrahedron 2000, 56,
137Ϫ141. [27l] J. B. M. Wit, G. Th. van Eijkel, F. J. J. de Kanter,
M. Schakel, A. W. Ehlers, M. Lutz, A. L. Spek, K. Lam-
mertsma, Angew. Chem. 1999, 111, 2716Ϫ2719; Angew. Chem.
Int. Ed. 1999, 38, 2596Ϫ2599. (and references therein)
[9]
[10]
Chem. 1982, 240, 157Ϫ162.
[11]
E. Hey-Hawkins, S. Kurz, Phosphorus, Sulfur, and Silicon 1994,
[28] [28a]
90, 281Ϫ284.
P. Jernakoff, C. de Meric de Bellefon, G. L. Geoffroy, A.
[12]
E. Hey-Hawkins, S. Kurz, J. Sieler, G. Baum, J. Organomet.
L. Rheingold, S. J. Geib, Organometallics 1987, 6, 1362Ϫ1364.
[28b]
Chem. 1995, 486, 229Ϫ235.
H.-J. Gosink, H. W. Roesky, H.-G. Schmidt, M. Nolteme-
[13]
C. Frenzel, E. Hey-Hawkins, Phosphorus, Sulfur 1998, 143,
yer, E. Irmer, R. Herbst-Irmer, Organometallics 1994, 13,
[28c]
1Ϫ17.
3420Ϫ3426.
E. Benory, A. Bino, D. Gibson, F. A. Cotton,
[14]
[28d]
E. Hey, F. Weller, J. Chem. Soc., Chem. Commun. 1988,
782Ϫ783.
U. Segerer, R. Felsberg, S. Blaurock, G. A. Hadi and E. Hey-
Hawkins, Phosphorus, Sulfur 1999, 144Ϫ146, 477Ϫ480; S.
Blaurock, Dissertation, Universität Leipzig, 2000; S. Blaurock,
G. A. Hadi, E. Hey-Hawkins, Angew. Chem. (in preparation).
M. J. Bunker, A. de Cian, M. L. H. Green, J. J. E. Moreau, N.
Siganporia, J. Chem. Soc., Dalton Trans. 1980, 2155Ϫ2161.
P. B. Hitchcock, M. F. Lappert, W. P. Leung, Chem. Commun.
Z. Dori, Inorg. Chim. Acta 1985, 99, 137Ϫ142.
D. T.
Richens, L. Helm, P.-A. Pittet, A. E. Merbach, F. Nicolo˜, G.
Chapuis, Inorg. Chem. 1989, 28, 1394Ϫ1402. [28e] F. Boutonnet,
M. Zablocka, A. Igau, J. Jaud, J.-P. Majoral, J. Schamberger,
[15]
G. Erker, S. Werner, C. Krüger, J. Chem. Soc., Chem. Commun.
[28f]
´
J. de la Mata, R. Fandos, M. Gomez, P.
1995, 823Ϫ824.
[16]
´
Gomez-Sal, S. Martinez-Carrera, P. Royo, Organometallics
1990, 9, 2846Ϫ2850.
[28g]
N. Wiberg, Lehrbuch der Anorgan-
[17]
ischen Chemie, Walter de Gruyter & Co., Berlin, 1985.
]M. Baudler, K. Glinka, Chem. Rev. 1993, 93, 1623Ϫ1667.
N. Etkin, M. T. Benson, S. Courtenay, M. J. McGlinchey, A.
D. Bain, D. W. Stephan, Organometallics 1997, 16, 3504Ϫ3510.
M. Yoshifuji, I. Shima, N. Inamoto, K. Hirotsu, T. Higuchi, J.
Am. Chem. Soc. 1981, 103, 4587Ϫ4589.
[29]
[30]
1987, 1282Ϫ1283.
[18]
EI for 1؊3, FAB for 4a, 4b. The mass spectra were recorded
with a Varian MAT 711 (EI, 70 eV, source temperature 180 °C.
[31]
FAB in nitrobenzaldehyde as matrix).
[19] [19a]
J. A. M. Canich, F. A. Cotton, Inorg. Chem. 1987, 26,
3473Ϫ3478. [19b] F. A. Cotton, M. P. Diebold, W. J. Roth, Poly-
J. C. Green, M. L. H. Green, G. E. Morris, J. Chem. Soc.,
[32] [32a]
[19c]
[32b]
hedron 1985, 4, 1103Ϫ1108.
A. J. Scioly, M. L. Luetkens,
Chem. Commun. 1974, 212Ϫ213.
P. S. Elmers, M. L.
R. B. Wilson, J. C. Huffmann, A. P. Sattelberger, Polyhedron
A. P. Sattelberger, R. B. Wilson Jr., J.
C. Huffmann, Inorg. Chem. 1982, 21, 4179Ϫ4184.
Scudder, B. O. West, J. Organomet. Chem. 1976, 122, 281Ϫ288.
[19d]
[32c]
1987, 6, 741Ϫ757.
B. Deppisch, H. Schäfer, Acta Crystallogr., Sect. B 1982,
[19e]
[32d]
F. A.
38, 748Ϫ751.
Soc. 1984, 106, 1495Ϫ1496.
Pidcock, C. P. Warrens, K. R. Dixon, J. Chem. Soc., Chem.
Commun. 1982, 932Ϫ933.
M. M. Olmstead, P. P. Power, J. Am. Chem.
[32e]
Cotton, M. P. Diebold, S. A. Duraj, W. J. Roth, Polyhedron
1985, 4, 1479Ϫ1484.
J. Chatt, P. B. Hitchcock, A.
[20]
[21]
[32f]
L. Messerle, Chem. Rev. 1988, 88, 1229Ϫ1254.
G. C. Campbell, J. A. M. Canich, F. A. Cotton, S. A. Duraj,
J. F. Haw, Inorg. Chem. 1986, 25, 287Ϫ290.
M. B. Hall, R. F. Fenske, Inorg. Chem. 1972, 11, 768Ϫ775.
L. Pauling, Die Natur der chemischen Bindung, Verlag Chemie,
Weinheim, 1962.
A. R. Chakravarty, F. A. Cotton, M. P. Diebold, D. B. Lewis,
W. J. Roth, J. Am. Chem. Soc. 1986, 108, 971Ϫ976.
R. J. Burt, G. J. Leigh, D. L. Hughes, J. Chem. Soc., Dalton
Trans. 1981, 793Ϫ799.
A. H. Cowley, J. E. Kilduff, J.
G. Lasch, N. C. Norman, M. Pakulski, F. Ando, T. C. Wright,
Organomet. 1984, 3, 1044Ϫ1050. [32g] S. Kurz, E. Hey-Hawkins,
J. Organomet. Chem. 1993, 462, 203Ϫ207.
[22]
[23]
[33]
M. Baudler, J. Hahn, H. Dietsch, G. Fürstenberg, Z. Natur-
forsch., Teil B 1976, 31, 1305Ϫ1310.
[34] [34a]
[24]
[25]
[26]
M. Baudler, B. Carlsohn, W. Böhm, G. Z. Reuschenbach,
Z. Naturforsch., Teil B 1976, 31, 558Ϫ564. [34b] M. Baudler, G.
Reuschenbach, Z. Anorg. Allg. Chem. 1980, 464, 9Ϫ16.
M. Baudler, B. Carlson, D. Koch, P. K. Medda, Chem. Ber.
1978, 111, 1210Ϫ1216.
[35]
V. C. Gibson, T. P. Kee, W. Clegg, J. Chem. Soc., Dalton Trans.
1990, 3199Ϫ3210.
[36] [36a] G. Becker, M. Rössler, E. Schneider, Z. Anorg. Allg. Chem.
[27] [27a] D. W. Stephan, Angew. Chem. 2000, 112, 322Ϫ328; Angew.
1978, 439, 121Ϫ133.
Leipzig, 1999.
C. Frenzel, Dissertation, Universität
[36b]
[27b]
Chem. 2000, 39, 314Ϫ329.
F. Mathey, Multiple Bonds and
[37]
Low Coordination in Phosphorus Chemistry, M. Regitz, O. J.
SHELXTL PLUS, Siemens Analyt. X-ray Inst. Inc., 1990, XS:
Program for Crystal Structure Solution, XL: Program for Crys-
tal Structure Determination, XP: Interactiv Molecular Graphics.
R. H. Blessing, Acta Crystallogr., Sect. A 1995, 51, 33Ϫ38.
S. Kurz, Dissertation, Universität Leipzig, 1994.
D. Feitler, G. M. Whitesides, Inorg. Chem. 1976, 15, 466Ϫ469.
A. Cowley, N. C. Norman, M. Pakulski, Inorg. Syn. 1990, 27,
235Ϫ240.
[27c]
Scherer (eds), Thieme, Stuttgart, 1990, p.38.
F. Mathey,
Angew. Chem. 1987, 99, 285Ϫ296; Angew. Chem. Int. Ed. Engl.
[27d]
[38]
[39]
[40]
[41]
1987, 26, 275Ϫ286.
K. D. Dillon, F. Mathey, J. F. Nixon,
Phosphorus: The Carbon Copy, Wiley, Chichester, 1998, p.19.
[27e] M. J. M. Vlaar, A. W. Ehlers, F. J. J. de Kanter, M. Schakel,
A. L. Spek, K. Lammertsma, Angew. Chem. 2000, 112,
[27f]
3071Ϫ3074; Angew. Chem. Int. Ed. 2000, 39, 2943Ϫ2945.
M. J. M. Vlaar, P. Valkier, A. W. Ehlers, F. J. J. de Kanter, M.
Received March 15, 2002
Schakel, A. L. Spek, M. Lutz, K. Lammertsma, Chem. Eur. J.
[I02138]
2984
Eur. J. Inorg. Chem. 2002, 2975Ϫ2984