New complexes of divalent thulium with substituted phospholyl and cyclopentadienyl ligands

Article abstract of DOI:10.1002/ejic.200400784

In order to try to stabilise the Tm^II ion with phospholyl ligands lacking methyl groups at the 3 and 4 positions, the following ligand precursors were prepared: sodium 2,5-di-tert-butylphospholyl [Na(Htp)] (3) and sodium 2,5-bis(trimethylsilyl)phospholyl [Na(Hsp)] (8), Because of its similar steric bulk, we also decided to use sodium di-tert-butylcyclopentadienyl [NaCp^tt] (9) as a ligand precursor. Compound 3 was obtained by sodium cleavage of the P-P bond of 2,5,2′,5′-tetra-tert-butyl-1,1′- diphosphole (2). Halogen-lithium exchange in 1,4-diiodo-1,4-bis(trimethylsilyl) buta-1,3-diene (4) followed by reaction with PhPCl₂ afforded 1-phenyl-2,5-bis(trimethylsilyl)phosphole (5). Treatment of 5 with lithium metal followed by oxidative treatment with iodine gave 2,5,2′,5′- tetrakis(trimethylsilyl)-1,1′-diphosphole (7) which could be transformed into 8 by treatment with sodium. Treatment of 3, 8 and 9 with [TmI ₂(THF)₃] in diethylether yielded three new organothulium(II) complexes [Tm(Htp)₂(THF)] (10), [Tm(Hsp) ₂(THF)] (11) and [Tm(Cp^tt)₂(THF)] (12), respectively, which could be isolated pure as crystalline solids in low to moderate yields. Complexes 10, 11 and 12 were studied by X-ray crystallography and their structures compared with those of two previously described complexes, [Tm(Cp″)₂(THF)] 1 [Cp″ = 1,3-bis(trimethylsilyl) cyclopentadienyl] and [Tm(Dtp)₂(THF)] (13) (Dtp = 3,4-dimethyl-2,5-di-tert-butylphospholyl). Although the phospholyl ligands may be slightly more bulky than their cyclopentadienyl counterparts, the structures of 1, 10, 11 and 12 are remarkably similar and are substantially different from that of the more bulky 13. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.

Full text of DOI:10.1002/ejic.200400784

FULL PAPER
New Complexes of Divalent Thulium with Substituted Phospholyl and
Cyclopentadienyl Ligands
François Nief,*[a] Brice Tayart de Borms,[a] Louis Ricard,[a] and Duncan Carmichael[a]
Keywords: Phosphorus heterocycles / Lanthanides / Subvalent compounds / Thulium / Cyclopentadienyl ligands
In order to try to stabilise the TmII ion with phospholyl lig-
ands lacking methyl groups at the 3 and 4 positions, the fol-
lowing ligand precursors were prepared: sodium 2,5-di-tert-
butylphospholyl [Na(Htp)] (3) and sodium 2,5-bis(trimethyl-
silyl)phospholyl [Na(Hsp)] (8). Because of its similar steric
bulk, we also decided to use sodium di-tert-butylcyclopen-
tadienyl [NaCptt] (9) as a ligand precursor. Compound 3 was
obtained by sodium cleavage of the P–P bond of 2,5,2Ј,5Ј-
tetra-tert-butyl-1,1Ј-diphosphole (2). Halogen-lithium ex-
change in 1,4-diiodo-1,4-bis(trimethylsilyl)buta-1,3-diene (4)
followed by reaction with PhPCl2 afforded 1-phenyl-2,5-bi-
s(trimethylsilyl)phosphole (5). Treatment of 5 with lithium
metal followed by oxidative treatment with iodine gave
2,5,2Ј,5Ј-tetrakis(trimethylsilyl)-1,1Ј-diphosphole (7) which
could be transformed into 8 by treatment with sodium. Treat-
ment of 3, 8 and 9 with [TmI2(THF)3] in diethylether yielded
three new organothulium(II) complexes [Tm(Htp)2(THF)]
(10), [Tm(Hsp)2(THF)] (11) and [Tm(Cptt)2(THF)] (12), respec-
tively, which could be isolated pure as crystalline solids in
low to moderate yields. Complexes 10, 11 and 12 were
studied by X-ray crystallography and their structures com-
pared with those of two previously described complexes,
[Tm(CpЈЈ)2(THF)] 1 [CpЈЈ = 1,3-bis(trimethylsilyl)cyclopen-
tadienyl] and [Tm(Dtp)2(THF)] (13) (Dtp = 3,4-dimethyl-2,5-
di-tert-butylphospholyl). Although the phospholyl ligands
may be slightly more bulky than their cyclopentadienyl
counterparts, the structures of 1, 10, 11 and 12 are remarka-
bly similar and are substantially different from that of the
more bulky 13.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
gand[12] thus yielding MIII complexes. They are also able to
reduce aromatic hydrocarbons[6,13] or acetonitrile.[14] Inter-
estingly, reduction of HoIII or YIII amides in the presence
of nitrogen also yields products in which N2 has been acti-
vated.[15]
Introduction
For a long time, the coordination chemistry of divalent
lanthanide (Ln) ions has been limited to the classical EuII,
YbII and SmII.[1] Although other LnII species can exit in
the solid state, these ions were until recently considered too
reactive to be isolated as molecular compounds.[2]
In the case of TmII, however, after some unsuccessful
attempts, Evans et al. isolated the first structurally charac-
However, this statement has been challenged very re-
cently by the isolation of molecular solvates of the type
[MI2(solv.)n] where M = Nd, Dy or Tm and solv. is a donor
solvent such as THF or dimethoxyethane (DME).[3–7] As
expected, these species are highly reducing. While solvated
terised
organometallic
complex
of
thulium(ii),
[TmCpЈЈ2(THF)] (1) [CpЈЈ = C5H3(SiMe3)2].[8] Since then,
by using very bulky phospholyl or arsolyl ligands, we have
been able to isolate several other TmII compounds[16,17] in-
cluding a homoleptic complex.[17] The chemistry of the
“new” divalent lanthanides has been very recently re-
viewed.[18]
[3,4]
[6]
[7]
TmI2
is reasonably stable, solvated DyI2 and NdI2
are highly reactive complexes which are only stable below
room temperature.
The phospholyl and arsolyl ligands appear particularly
suitable for the stabilisation of low-valent complexes be-
cause of their reduced π-donating ability. So far, we have
In coordination chemistry, no other complexes of NdII
and DyII have been isolated up to now although their tran-
sient nature has been postulated in trapping reactions. Like-
wise, some transient TmII complexes have also been ob-
served this way. For instance the MII cations can be trapped
with nitrogen, forming [µ-(N22–)] complexes[8–10] or by oxi-
dative splitting of the coordinated solvent[8,11] or the li-
used the following ligands around TmII: Dsp
PC4Me2(Tms)2, Dsas = AsC4Me2(Tms)2 and Dtp
=
=
PC4Me2tBu2. These ligands differ from the CpЈЈ ligand by
the presence of the heteroatom in the ring but also by their
higher bulkiness due to the presence of two extra methyl
groups as substituents.
At this point, we wanted to expand the scope of TmII
chemistry by synthesising new complexes which would be
sterically more similar to that of Evans (1).[8] Thus, we de-
cided to attempt to stabilise the TmII ion with phospholyl
[a]
Laboratoire Hétéroéléments et Coordination, CNRS UMR
7653, DCPH, Ecole Polytechnique,
91128 Palaiseau, France
Fax: +33-1-69333990
E-mail: nief@poly.polytechnique.fr
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DOI: 10.1002/ejic.200400784
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F. Nief, B. Tayart de Borms, L. Ricard, D. Carmichael
FULL PAPER
ligands lacking the two methyl groups on the rings which new ligand precursor [Na(Htp)] (3) was simply obtained in
are present in Dsp and Dtp. These ligands are Hsp = good yield by sodium cleavage of the P–P bond in 2
PC4H2(Tms)2 and Htp = PC4H2tBu2. In order to have a (Scheme 2).
complete picture, we also decided to use the well known
Cptt ligand [Cptt = C5H3tBu2] (Scheme 1). Interestingly,
Lappert has recently characterised an unusual LaII anionic
complex with this ligand, namely [K(18-crown-6)(η-
C6H6)2][(LaCptt2)2(µ-C6H6)] by reduction of the trivalent
precursor [(LaCptt2)3].[19]
Scheme 2. Synthesis of Na(Htp) (3); reagents and conditions: a)
excess Na, THF, room temp., 85%
The Hsp ring has not been described in the literature
although Sato et al. have recently described a silole (silacy-
clopentadiene) possessing the same substituents on the het-
erocyclic ring. These authors, using trimethylsilylacetylene
as a starting material, employed TiII-based chemistry in or-
der to prepare 1,4-diiodo-1,4-bis(trimethylsilyl)buta-1,3-di-
ene (4) as a key intermediate. Further iodine-lithium ex-
change followed by treatment with Si(OEt)4 allowed them
to isolate 1,1-dimethoxy-2,5-bis(trimethylsilyl)silole.[21]
Compound 4 was prepared with slight modifications to
the original procedure due to scale-up. Iodine-lithium ex-
change in 4 with nBuLi in Et2O followed by treatment with
PhPCl2 gave 1-phenyl-2,5-bis(trimethylsilyl)phosphole (5) in
fair yield. Further treatment of 5 with potassium metal un-
der the conditions previously used for the synthesis of
[K(Dsp)][16] was less satisfactory and although [K(Hsp)] (6)
was obtained as the major product, it was invariably con-
taminated with up to 20% of a product resulting from desi-
lylation, i.e. [K{PC4H3(SiMe3)}] (31P NMR: δ = 116 ppm).
Although repeated extraction of the crude solid with Et2O
could reduce the side product content of 6 to less than 10%,
we nevertheless sought a better synthesis of the Hsp anion.
Scheme 1. Ligands and complexes in TmII chemistry
In this paper we report the synthesis of the new ligand
Hsp, the synthesis of three new TmII complexes with the
Hsp, Htp and Cptt ligands, and a structural study of these
complexes by comparison with that of 1.
Results and Discussion
Ligands
The synthesis of 2,5,2Ј,5Ј-tetra-tert-butyl-1,1Ј-diphos- We found that no concomitant desilylation took place when
phole (Htp)2 (2) has been described in the literature.[20] The 4 was treated with lithium instead of potassium and the
Scheme 3. Synthesis of Na(Hsp) (8); reagents and conditions: a) Ti(OiPr)4 + iPrMgCl, Et2O, –78 °C to –50 °C, 2 h, then I2, –50 °C to
room temp., 2 h, 67%; b) 2 nBuLi, Et2O, –78° to room temp., 1h, then PhPCl2, –78° to room temp., 30 min, 42%; c) excess K, DME,
70 °C, 2h; d) excess Li, THF, room temp., 3 h, then AlCl3, 0 °C, 30 min, then I2, room temp., 15min, 66%; e) excess Na, THF, room
temp., 79%
638
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New Complexes of Divalent Thulium
FULL PAPER
resultant [Li(Hsp)] could be transformed, in situ, into
(Hsp)2 (7) by treatment with iodine. Pure [Na(Hsp)] (8) was
then obtained by treatment of 7 with sodium in THF
(Scheme 3).
Finally, 1,3-di-tert-butylcyclopentadiene (HCptt) was
prepared by literature methods[22] and transformed into
[NaCptt] (9) by treatment with NaNH2 in THF.[23]
New Complexes of Thulium(II
)
Scheme 4. Synthesis of TmII phospholyl complexes
We then tried to synthesise TmII complexes of the Htp,
Hsp and Cptt ligands by utilising their sodium salts (3, 8, high field which were difficult to integrate accurately due to
and 9, respectively) in reactions with [TmI2(THF)3], in a 2:1 their large width and baseline roll. In order to simplify this
mole ratio, at 0 °C and with diethylether as a solvent. With situation, we decided to prepare an analogue of 10 in which
the phospholyl anions 3 and 8, the reaction mixtures the THF was replaced by perdeuterated THF. This was ac-
quickly turned dark green. After 1 hour, the solutions were complished by allowing 3 to react with unsolvated TmI2
checked by 31P NMR spectroscopy and the spectra showed in diethylether in the presence ofca. 0.1 mL of [D8]THF.
complete disappearance of the starting anions and the pres- Afterstandard workup, [Tm(Htp)2([D8]THF)] (10-d) could
ence of two new, broad peaks at δ = –290 and –235 ppm, be isolated and its proton spectrum is presented below to-
respectively, with Htp and Hsp as the ligands. These signals gether with that of 10 (Figure 1).
provided good evidence for the presence of TmII phospholyl
A comparison of these spectra suggests that the signals
complexes, their chemical shifts being similar to those of around –30 ppm and –45 ppm in 10 belong to the THF
the already described [Tm(Dtp)2(THF)] and [Tm(Dsp)2- solvent and that the peak at highest field around –70 ppm
(THF)].[16] Complexes formulated as [Tm(Htp)2(THF)] corresponds to the β-protons on the phospholyl ring. The
(10) and [Tm(Hsp)2(THF)] (11) could be subsequently iso- assignment of the high-field signals in the spectrum of 11
lated as dark green crystalline powders from pentane at was inferred accordingly (see experimental section). Finally,
–30 °C (Scheme 4).
magnetic susceptibility measurements confirmed the +II
Complexes 10 and 11 exhibit reasonably well-resolved oxidation state of thulium in 10 and 11.
(and quite similar) proton NMR spectra in C6D6. Whilst
The reaction of 9 with [TmI2(THF)3] proceeded similarly
the methyl groups could be clearly identified at low field (δ to those described above but the solution colour was pur-
= 57 ppm for 10 and 43 ppm for 11), the remaining signals plish-red. Evaporation to dryness of the filtered solution
(corresponding to the coordinated THF and the β-protons induced some apparent decomposition of the product since
on the ring) were present as three sets of broad humps at further extraction with pentane invariably resulted in the
Figure 1. Proton NMR spectra (C6D6 solutions, ppm values) of 10–d (upper trace) and 10 (lower trace) (s = C6D5 H, d = diamagnetic
impurities)
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F. Nief, B. Tayart de Borms, L. Ricard, D. Carmichael
FULL PAPER
precipitation of large amounts of white, insoluble material X-ray Crystal Structures
(this was not the case with the phospholyl compounds). We
Suitable crystals of 10, 11 and 12 were obtained by low-
found that a red crystalline solid, formulated as [Tm(Cptt)2-
(THF)] (12) could be obtained in low yield by concentrating
the filtered reaction mixture by evaporation of diethylether
and allowing the solution to stand at –30 °C for two days.
The proton NMR spectra of a solution of these crystals
in [D6]benzene or [D12]cyclohexanedisplayed a peak at δ =
63 ppm which can reasonably be attributed to the methyl
groups but the other parts of the spectra were less clear. We
found that for 12 µeff= 4.6 µB, a value which is compatible
with TmII (Scheme 5).
temperature crystallisation. A summary of the X-ray data
is presented in Table 1 and Figure 2 shows ORTEP plots of
one molecule each of 10, 11 and 12, respectively.
In the structures of 11 and 12, the Tm–O bond coincides
with a crystallographic symmetry axis. In addition, in 12,
the coordinated THF molecule is disordered over two posi-
tions and only one is presented in Figure 2. Table 2 displays
relevant distances and angles for 10, 11 and 12 together
with relevant data for 1[8] (the trimethylsilyl analogue of 12)
and [Tm(Dtp)2(THF)] 13[16] (analogue of 10 with two
methyl substituents on the phospholyl ring).
The structures of 1, 10, 11 and 12 are strikingly similar.
The Tm–O bond lengths and the ligand bending, as indi-
cated by both the centroid-Tm-centroid angles and the dihe-
dral angles between the mean planes of the π-ligands (re-
ferred to as ligand plane angles in Table 2), are almost iden-
tical in these four complexes. The main difference between
the phospholyl complexes 10 and 11 and their cyclopen-
tadienyl analogues (12 and 1, respectively) is that in 10 and
11 the C–Tm bonds are longer. This is probably due to the
fact that the phospholyl complexes have to accommodate a
Scheme 5. Synthesis of a TmII cyclopentadienyl complex
Diethyl ether solutions of 10, 11 and 12 were then ex- long P–Tm bond in the TmII coordination sphere. Inciden-
posed to 1atm. of nitrogen. In the case of 10 and 11, no tally, this bond length in 10 and 11 falls in the range of the
reaction had taken place after 24h at room temperature. In tabulated values for YbII–P bonds[24] (the ionic radii of YbII
contrast, in the case of 12, a colour change to light brown and TmII are similar). On these grounds, the steric bulk of
occurred within a few minutes. Unfortunately, however, de- the Hsp and Htp ligands should be larger than their all-
spite several attempts, we could not isolate any crystalline carbon counterparts (CpЈЈ and Cptt, respectively). However,
product from this reaction mixture. Thus, no definite com- this is not reflected by the Tm–O distances and ligand bend-
pounds could be isolated from the reaction of our new TmII ing in 1, 10, 11 and 12. On the contrary, in 13, all param-
complexes with N2. Nevertheless, we can confirm that coor- eters relevant to steric crowding (Tm–O and Tm–C bond
dination of the phospholyl ligand considerably lessens the lengths, cnt–Tm–cnt and ligand plane angles) are higher
reactivity of thulium(ii).
than in 1, 10, 11 and 12. This is most likely due to inter-
Table 1. Crystallographic data and data collection parameters
Compound
10
11
12
Mol. formula
Mol. mass
Crystal habit
Crystal size [mm]
Crystal system
Space group
a [Å]
C28H48OP2Tm
631.53
C24H48OP2Si4Tm
695.85
C30H50OTm
595.63
green block
0.20 × 0.18 × 0.18
monoclinic
P21/n (No.14)
11.2140(10)
17.0150(10)
15.4690(10)
91.0540(10)
2951.1(4)
4
green block
0.20 × 0.20 × 0.20
monoclinic
C2/c (No.15)
20.2000(10)
11.1120(10)
14.9950(10)
98.7800(10)
3326.4(4)
4
deep red block
0.18 × 0.16 × 0.16
orthorhombic
Pbcn (No.60)
10.9610(10)
15.2930(10)
17.1860(10)
90
2880.8(4)
4
1.373
1228
3.098
b [Å]
c [Å]
β [°]
V [Å3]
Z
d [g cm–3]
F(000)
1.421
1292
3.132
1.389
1420
2.922
µ [cm–1]
Maximum θ [°]
Reflections measured
Unique data
Rint
Reflections used
wR2 (all data)
R1
30.00
14403
8577
0.0176
7111
0.0714
0.0275
30.03
13656
4849
0.0663
3826
0.0912
0.0374
30.03
7936
4221
0.0279
2778
0.1549
0.0544
GoF
1.034
0.965
1.102
640
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New Complexes of Divalent Thulium
FULL PAPER
Figure 2. ORTEP plots of 10, 11 and 12 together with the numbering schemes used (50% probability ellipsoids, H atoms omitted)
Table 2. Selected distances [Å] and angles [°] for complexes 1, 10, 11, 12 and 13
Distances [Å]
1[8]
10
11
12
13[16]
Tm–O
Tm–C (min./av./max.)
Tm–P
Tm–centroid (cnt)
Angles [°]
2.365(5)
2.65/2.68/2.71
2.393(2)
2.72/2.76/2.80
2.941(2) (av.)
2.45 (av.)
2.398(3)
2.72/2.75/2.79
2.921(1)
2.388(7)
2.65/2.68/2.74
2.455(2)
2.77/2.83/2.90
2.95(1) (av.)
2.53 (av.)
–
2.39
–
2.40
2.46
Cnt–Tm–cnt
Ligand planes
135
133
135
131
130
128
136
131
145
146
mental analyses were performed at the Service de microanalyse du
CNRS, Gif-sur-Yvette, France, and at the Service de microanalyse
de lЈuniversité de Dijon, Dijon, France.
ring steric repulsion of the methyl groups in 13. Thus, add-
ing methyl groups to the ring induces more structural
changes than a CH ↔ P substitution.
Phospholyl 3: To a solution of diphosphole 2[20] (1.5 g, 3.84 mmol)
in THF (30 mL) at room temperature was added excess sodium in
small pieces (0.35 g). After 3 h, the remaining sodium was removed
from the reaction mixture which was then evaporated to dryness
under vacuum. The residue was rinsed with hexane and sodium 2,5-
di-tert-butylphospholyl (3) was obtained as an air-sensitive white
powder which was dried in vacuo (1.43 g, 6.55 mmol, 85%). 1H
NMR (300 MHz, [D8]THF): δ = 1.32 (s, 18 H, CH3), 6.47 ppm (d,
JHP = 4 Hz, 2 H, CH). 13C NMR (75.5 MHz, [D8]THF): δ = 35.2
Conclusions
In this report, we have described access to the new 2,5-
bis(trimethylsilyl)phospholyl (Hsp) ring system and the suc-
cessful isolation of two new TmII phospholyl complexes,
[Tm(Htp)2(THF)] (10) and [Tm(Hsp)2(THF)] (11) as well
as the second TmII cyclopentadienyl complex, [Tm(Cptt)2-
(THF)] (12). Preliminary studies seem to indicate that the
reactivity of 12 is higher than that of 10 and 11.
We feel that organothulium(ii) π complexes can no
longer be considered as rarities. They are not especially dif-
ficult to isolate as long as the ligands provide adequate ste-
ric protection of the TmII environment and oxygen, nitro-
gen and water are excluded during their synthesis. We are
convinced that many more TmII compounds can be made,
thus opening the way to more studies of the chemistry of
divalent thulium.
(d, JCP = 18 Hz, C), 35.3 (d, JCP = 8 Hz, CH3), 113.1 (d, JCP
=
2 Hz, C3), 160.3 ppm (d, JCP = 47 Hz, C2). 31P NMR (122 MHz,
[D8]THF): δ = 56 ppm.
Diiodide 4:[21] This was prepared by a modification of the literature
procedure. To a diethylether (300 mL) solution of Ti(OiPr)4
(18 mL, 17.28 g, 60.7 mmol) and TmsCCH (14 mL, 9.94 g,
103 mmol) at –70 °C was added an ether solution of iPrMgCl
(60 mL of 2 m soln., 120 mmol) The mixture was warmed to –50 °C
over 1 h. After stirring for an additional 1 h, I2 (31.75g, 125 mmol)
was added as a solid to the mixture at –50 °C. The mixture was
warmed to room temperature and stirred for 2 h. A saturated aque-
ous solution of Na2S2O3 was then added and the mixture was ex-
tracted with hexane. The extract was dried with MgSO4, filtered
and evaporated whereupon the resultant oil partially crystallised.
The residue was recrystallised from methanol at 0 °C and 1,4-di-
iodo-1,4-bis(trimethylsilyl)buta-1,3-diene (4) (15.15g, 33.6 mmol,
Experimental Section
General Remarks: All manipulations involving lanthanide com-
plexes were performed on a vacuum line or in a drybox under ar-
gon using dry, oxygen-free solvents. All other reactions were per-
formed in Schlenk glassware under nitrogen. Diphosphole (2)[20]
1
67%) was obtained as tan crystals. H NMR (300 MHz, C6D6): δ
= 0.14 (s, 18 H, CH3), 7.31 ppm (s, 2 H, CH).
[17]
and TmI2 were prepared as described previously. [TmI2(THF)3]
Phosphole 5: A solution of diiodide 4 (9 g, 20 mmol) in diethylether
(80 mL) was cooled to –78 °C and a solution of nBuLi in hexane
(30 mL of 1.33 m soln., 40 mmol) was added dropwise. After 1 h
stirring at this temperature, a solution of PhPCl2 (4.5 g, 25 mmol)
was obtained by extraction of TmI2 with THF. All other reagents
were commercial and used as received from the suppliers. Magnetic
susceptibility data were obtained by the Evans NMR method. Ele-
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F. Nief, B. Tayart de Borms, L. Ricard, D. Carmichael
FULL PAPER
in hexane (20 mL) was added dropwise and the reaction mixture
was allowed to warm to room temperature. The solution was then
evaporated to dryness and taken up in a 1:1 hexane/satd. aq.
NaHCO3 mixture (200 mL). This mixture was decanted, the aque-
ous phase extracted with hexane, the combined organic phases
dried with MgSO4 and the solvents evaporated to dryness. The resi-
due was chromatographed on silica gel using hexane as the eluent.
The compound 1-phenyl-2,5-bis(trimethylsilyl)phosphole (5) was
obtained as a colourless oil (2.55 g, 8.37 mmol, 42%). 1H NMR
(300 MHz, C6D6): δ = 0.11 (s, 18 H, CH3) 6.95 (m, 3 H, Ph), 7.21
(d, JHP = 19.5 Hz, 2 H, CH), 7.25 ppm (m, 2 H, Ph). 13C NMR
(75.5 MHz, C6D6): δ = 0.18 (d, JCP = 2.5 Hz, CH3), 128.4 (d, JCP
= 9.0 Hz, C meta-Ph), 129.8 (d, JCP = 1.5 Hz, C para-Ph), 131.0
(d, JCP = 8.5 Hz, C ipso-Ph), 135.0 (d, JCP = 20.5 Hz, C ortho-Ph),
144.9 (d, JCP = 10.5 Hz, C3), 158.4 ppm (d, JCP = 31.5 Hz, C2).
31P NMR (122 MHz, C6D6): δ = 38.5 ppm. MS (70 eV, CI/NH3):
m/z (%) 305 [M + H]+ (100). C16H25PSi (304.5): calcd. C 63.1, H
8.3; found C 63.0, H 8.3.
pentane. The pentane solution was filtered, concentrated to a small
volume and cooled to –30 °C whereupon the product crystallised.
Complex 11 was obtained as dark green crystals (0.067 g,
1
0.096 mmol, 48%). H NMR (300 MHz, C6D6): δ = –63 (br., 4 H,
CH), –52 (br., 4 H, THF), –34 (br., 4 H, THF), 43 ppm (br., 36 H,
CH3). 31P NMR (122 MHz, C6D6): δ = –240 ppm (br. s). µeff
4.7 µB.
=
Complex 12: This was prepared from TmI2(THF)3 (0.200 g,
0.31 mmol) and 9 (0.26 g, 0.62 mmol). The purplish-red solution
was filtered and concentrated to a small volume and this solution
was kept for 2 days at –30 °C whereupon the product crystallised.
Complex 11 was obtained as a dark reddish-purple powder
(0.036 g, 0.06 mmol, 19%). 1H NMR (300 MHz, C6D6): δ = 63 ppm
(br. s, CH3). Other small peaks were present at 89, 83 and –77 ppm.
µeff= 4.6 µB.
X-ray Crystallographic Study: Suitable single-crystals of 10 and 11
were obtained from saturated pentane solutions at –30 °C and
those of 12 were obtained from a saturated diethylether solution
at –30 °C. X-ray intensities were measured with a Nonius Kap-
paCCD diffractometer at 150(1) K using graphite monochromated
Mo-Kα radiation (λ = 0.71073 Å). A summary of the crystal struc-
ture determinations is presented in Table 1. CCDC-250697–250699
contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_requ-
est/cif.
Diphosphole 7: A solution of phosphole 5 (1 g, 3.28 mmol) in THF
(30 mL) was treated with lithium metal (0.18 g, excess). After 3 h
at room temperature, the excess lithium was removed and the solu-
tion was treated with AlCl3 (0.15 g, 1.1 mmol). After 30min at
room temperature, solid iodine (0.42 g, 1.64 mmol) was added to
the reaction mixture which was then evaporated to dryness under
vacuum. The crystalline residue was dissolved in hexane, the solu-
tion was evaporated and the resultant solid recrystallised from
methanol. The product 2,5,2Ј,5Ј-tetrakis(trimethylsilyl)-1,1Ј-dipho-
sphole (7) was obtained as pale yellow crystals (0.49 g, 2.16 mmol,
66%). 1H NMR (300 MHz, C6D6): δ = 0.27 (s, 36 H, CH3), 7.22
ppm (pseudo-t, JHP(app.) = 22 Hz, 4 H, CH). 13C NMR (75.5 MHz,
C6D6): δ = 0.63 (s, CH3) 144.6 (pseudo-t, JCP(app.) = 16 Hz, C3),
152.1 ppm (pseudo-t, JCP(app.) = 37 Hz, C2). 31P NMR (122 MHz,
C6D6): δ = –3 ppm. MS (70 eV, CI/NH3) m/z (%) 455 [M + H]+
(100). C20H40P2Si4 (454.8): calcd. C 52.8, H 8.9; found C 52.7, H
9.0.
Acknowledgments
Financial support from CNRS and Ecole Polytechnique is grate-
fully acknowledged.
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Phospholyl 8: This was prepared similarly to 3 by cleavage of dipho-
sphole 7 (0.3 g, 0.66 mmol) with sodium (0.15 g, excess) in THF
solution (10 mL). Yield: 0.26 g (1.04 mmol, 79%) of sodium 2,5-
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1H NMR (300 MHz, [D8]THF): δ = 0.19 (s, 18 H, CH3), 7.14 ppm
(d, JHP = 8.5 Hz, 2 H, CH). 13C NMR (75.5 MHz, [D8]THF): δ =
2.50 (d, JCP = 2 Hz, CH3) 127.5 (d, JCP = 2 Hz, C3), 144.4 ppm
(d., JCP = 67.5 Hz, C2). 31P NMR (122 MHz, [D8]THF): δ = 145
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7.6.
General Method for the Synthesis of the TmII Complexes: Dry di-
ethylether was condensed at –78 °C onto a mixture of TmI2-
(THF)3 (1 equiv.) and the anions 3, 8 or 9 (2 equiv.). The reaction
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Complex 10: This was prepared from TmI2(THF)3 (0.150 g,
0.23 mmol) and 3 (0.102 g, 0.47 mmol). The dark green solution
was evaporated to dryness and the residue extracted with pentane.
The pentane solution was evaporated to dryness and the residue
rinsed with cold pentane. Yield 0.056 g of 6 as dark green crystals
(0.089 mmol, 38%). 1H NMR (300 MHz, C6D6): δ = –68 (br., 4 H,
CH), –44 (br., 4 H, THF), –32 (br., 4 H, THF), 57 ppm (br., 36
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=
Complex 11: This was prepared from TmI2(THF)3 (0.128 g,
0.200 mmol) and 8 (0.100 g, 0.40 mmol). The dark green solution
was filtered, evaporated to dryness and the residue dissolved in
642
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 637–643

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Received: September 22, 2004
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