Syntheses and crystal structures of two ytterbocene complexes [Yb(η-Cp′)2I(THF)] and [Yb(η-Cp′)2(μ-Cl)2Li(THF)2] (Cp′ = C5H3(SiMe3)2-1,3)

Article abstract of DOI:10.1016/S0022-328X(00)00509-X

The ytterbocene(III) iodide [Yb(η-Cp′)₂I(THF)] (1) (Cp′ = C₅H₃(SiMe₃)₂-1,3) was synthesized by the reaction of two equivalents of Na(Cp′) with YbI₃(THF)₂ (obtained from Yb and an

Full text of DOI:10.1016/S0022-328X(00)00509-X

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 613 (2000) 105–110
Syntheses and crystal structures of two ytterbocene complexes
[Yb(h-Cp%%)2I(THF)] and [Yb(h-Cp%%)2(m-Cl)2Li(THF)2]
(Cp%%=C5H3(SiMe3)2-1,3)
Peter B. Hitchcock, Michael F. Lappert *, Sanjiv Prashar 1
Chemistry Laboratory, School of Chemistry, Physics and Molecular Science, Uni6ersity of Sussex, Brighton BN1 9QJ, UK
Received 20 May 2000; accepted 22 July 2000
Abstract
The ytterbocene(III) iodide [Yb(h-Cp%%)2I(THF)] (1) (Cp%%=C5H3(SiMe3)2-1,3) was synthesized by the reaction of two equiva-
lents of Na(Cp%%) with YbI3(THF)2 (obtained from Yb and an excess of (ICH2)2 in THF). The heterobimetallic complex
[Yb(h-Cp%%)2(m-Cl)2Li(THF)2] (2) was prepared from two equivalents of Li(Cp%%) with YbCl3. The crystal structures of 1 and 2 have
been determined. The formation of the ytterbium(II) complex [Yb(h-Cp%%)(OAr)(THF)x] (3) (OAr=OC6H2But2-2,6-Me-4) was
observed (1H- and 171Yb-NMR spectroscopy) during the reaction of either Na(Cp%%) or [Yb(h-Cp%%)2(THF)] with
[Yb(OAr)2(THF)3]. © 2000 Elsevier Science B.V. All rights reserved.
Keywords: Ytterbium; Lanthanide(III) halides; Heteroleptic lanthanide(II) complexes
1. Introduction
alkali metal) are accessible from LnCl3 and two equiva-
lents of the alkali metal (M) cyclopentadienyl in an
aprotic donor solvent [11]. Sublimation of the latter
generally gave lanthanocene(III) halides [{Ln(h-
cp)2X}2] [9a,b,c,e], MCl being eliminated.
Homoleptic lanthanide(II) complexes are numerous,
but somewhat fewer heteroleptic analogues have been
reported [12]. In some instances this was due to their
lability with respect to redistribution into homoleptic
partners. However, the following heteroleptic lan-
thanide(II) complexes have been structurally character-
In the organometallic chemistry of the 4f elements
[1], the lanthanocene(III) halides are important precur-
sors for a variety of lanthanocene(III) derivatives such
as alkyls, hydrides or amides. These have shown unique
characteristics as catalysts in hydrogenation [2],
oligomerization [3], polymerization [4], hydroamination
[5], hydrosilylation [6], silanolytic chain transfer [7] and
hydroboration [8] of a-olefins.
Lanthanocene(III) halides are available as crystalline
solvent-free, dimeric compounds [{Ln(h-cp)2X}2] (cp is
C5H5 (ꢀCp) or a derivative thereof) [9]. Monomeric
lanthanocene(III) halide complexes, [Ln(h-cp)2X(THF)]
are well known. For Ln=Eu, Sm or Yb, they are
invariably prepared by the oxidation of the appropriate
lanthanocene(II) complex by a suitable alkyl halide
[10]. Heterobimetallic Ln(III)–M complexes (M=an
ized
by
X-ray
diffraction:
[{Yb6(h-C5Me4-
(SiMe2But))6I8}{Li(THF)4}2}] [12a], [{Yb(h-Cp*)(m-
I)(THF)2}2] [12a], [{Yb(h-Cp*)(m-I)(DME)}2] [12a],
[Yb(Tp)I(THF)] [12b,c], [Yb(Tp)I(3,5-lutidine)2] [12c],
[{YbI(m-OCPh3)(DME)}2]
(DME)}2] [12d], [{Sm(NR2)(m-I)(THF)(DME)}2] [12e],
[{Sm(h-Cp*)(m-I)(THF)2}2] [12f], [{Yb(CR3)(m-I)-
(OEt2)}2] [12g], [12h,i],
[{Yb(NR2)(m-OCBut3)}2]
[Yb(Tp)(NR2)] [12b],
[12j,k],
[Yb(Tp)(CHR2)]
[12d],
[{YbI(m-OMe)-
[{Yb(CR3)(m-OEt)(OEt2)}2]
* Corresponding author. Tel.: +44-1273-678316; fax: +44-1273-
677196.
[{Sm(h-Cp*)(m-OC6H2But3-2,4,6)}2]
[12l],
E-mail addresses: m.f.lappert@sussex.ac.uk (M.F. Lappert),
sprashar@qino-cr.uclm.es (S. Prashar).
[12b],
[Yb(h-Cp*)(SiR3)(THF)2]
[12m], [{Eu(h-Cp*)(m-CꢀCPh)(THF)2}2] [12n] and
[Yb(h-C5H4R)(Tp)] [12o] (R=SiMe3, Cp*=C5Me5,
Tp=hydrotris(3-tert-butyl-5-methylpyrazolyl)borate).
1 Present address: Departamento de Qu´ımica Inorga´nica, Orga´nica
y Bioqu´ımica, Facultad de Qu´ımicas, Campus Universitario, Univer-
sidad de Castilla-La Mancha, 13071-Ciudad Real, Spain.
0022-328X/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00509-X

106
P.B. Hitchcock et al. / Journal of Organometallic Chemistry 613 (2000) 105–110
Heteroleptic lanthanide(II) complexes Ln(X)(Y) are
2.2. Synthesis of [Yb(p-Cp%%)2I(THF)] (1)
accessible by the following routes (i)–(iii): (i) LnX2+
Y−; (ii) LnX2+LnY2; or (iii) LnX2+HY.
The reaction of two equivalents of Na(Cp%%) with
YbI3(THF)2 in diethyl ether yielded [Yb(h-Cp%%)2-
I(THF)] (1) as the sole product, Eq. (2). This is surpris-
ing, since generally the reaction of M(cp) with LnX3
gives as the principal product the heterobimetallic com-
plex [Ln(h-cp)2(m-X)2M(L)2]. For example, from YCl3
and K(Cp*) in THF, [Y(h-Cp*)2Cl(THF)] was isolated
only as a minor product alongside [Y(h-Cp*)2(m-
Cl)2K(THF)2] [10]. We attribute our finding to steric
constraints, the Yb(II) radius being small and the Cp%%−
and I− ligands being sterically demanding. Consistent
with this interpretation, we note the recent reports on
the monomeric homometallic lanthanocene(III) halide
complexes [Ln(h-C5Me4Pri)2Cl(THF)] (Ln=Y, Sm or
Lu) [14] and [Sm{(h-C5Me4)2SiMe2}I(THF)] [15], ob-
tained by a similar procedure. The conventional path-
way to such compounds is via oxidation of the
lanthanocene(II) or the metal by an alkyl halide as for
the following compounds which were prepared in this
manner; [Sm(h-Cp*)2X(THF)] (X=Cl or I) [10] or
[Yb(h-Cp)2X(THF)] (X=Cl, Br or I) [16]; while [Ln(h-
Cp%%)2I(THF)] (Ln=Sm, Y, Er or Lu) or [Lu(h-
C5H4SiMe3)(h-Cp%%)I(THF)] were obtained from the
appropriate LnCl3, Na(Cp%%), Na(C5H4SiMe3) and NaI
in THF [17].
2. Results and discussion
2.1. Synthesis of YbI3(THF)2
The iodide YbI3(THF)2 was prepared in a similar
manner to its ytterbium(II) analogue [13], except that
an excess of ICH2CH2I was used (Eq. (1)). Normally in
the reactions leading to YbI2(L)n (L being a neutral
donor), an excess of the metal is used in order to
prevent subsequent Yb(II)“Yb(III) oxidation. The ti-
tle compound was isolated as a pink solid and the
quantitative yield indicated a bis-THF adduct, as evi-
dent also from the analytical data.
Yb+32ICH2CH2IT“HFYbI3(THF)2
(1)
YbI3(THF)2+2Na(Cp¦)O“Et2[Yb(h-Cp¦)2I(THF)]
(2)
2.3. X-ray crystal structure of [Yb(p-Cp%%)2I(THF)] (1)
The molecular structure and atom numbering scheme
for the crystalline complex 1 are shown in Fig. 1.
Selected bond lengths and angles are in Table 1. The
structure of 1 is typical of a bent metallocene complex
with two additional ligands. Thus 1 adopts a distorted
tetrahedral geometry about the metal, with angles de-
creasing in the sequence Cent(1)ꢀYbꢀCent(2)\Cent(1
or 2)ꢀYbꢀO]Cent(1 or 2)ꢀYbꢀI\IꢀYbꢀO [Cent(1)
and Cent(2) are the centroids of C(1)ꢀC(5) and
C(12)ꢀC(16) rings, respectively]. The YbꢀC bond dis-
Fig. 1. Molecular structure and atom-labelling scheme for [Yb(h-
Cp%%)2I(THF)] (1).
,
tances range from 2.59(2) to 2.69(2) A. The bond length
,
of YbꢀI 2.925(2) A can be compared with the YbꢀI
,
3.013(1) A for the ytterbium(II) complex [YbI2(THF)4]
[12p]. Selected data can be compared with those other
monomeric ether adducts of lanthanocene halide com-
plexes, Table 2.
Table 1
a
,
Selected bond lengths (A) and angles (°) for complex 1
YbꢀCent(1)
YbꢀCent(2)
2.321
2.330
YbꢀI
YbꢀO
2.925(2)
2.303(13)
2.4. Synthesis of [Yb(p-Cp%%)2(v-Cl)2Li(THF)2] (2)
Cent(1)ꢀYbꢀCent(2)
Cent(1)ꢀYbꢀI
Cent(1)ꢀYbꢀO
129.7
110.0
104.3
Cent(2)ꢀYbꢀI
Cent(2)ꢀYbꢀO
IꢀYbꢀO
105.7
107.8
93.3(3)
Compound 2 was prepared by the addition of two
equivalents of LiCp%% to YbCl3 in THF, Eq. (3) [19].
Recrystallisation from hexane gave red, X-ray-quality
crystals.
a Cent(1) and Cent(2) are the centroids of the C(1)ꢀC(5) and
C(12)ꢀC(16) rings, respectively.

P.B. Hitchcock et al. / Journal of Organometallic Chemistry 613 (2000) 105–110
107
Table 2
Selected bond lengths and angles for monomeric yttrium and lanthanocene(III) halide complexes
,
,
,
Complex
Ln ionic radius
LnꢀCav (A) LnꢀX (A)
LnꢀO (A)
CpꢀLnꢀCp% (°)
XꢀMꢀO (°)
Reference
,
(A) [18]
[Y(h-Cp*)2Cl(THF)]
[Y(h-Cp%%)2I(THF)]
[Sm(h-Cp*)2Cl(THF)]
[Sm(h-Cp*)2I(THF)]
[Sm(h-Cp*)2I(THF)]
[Sm{(h-C5Me4)2SiMe2}
1.015
1.015
1.09
1.09
1.09
1.09
2.655
2.654
2.72
2.725
2.714
2.702
2.578(3)
2.969(1)
2.737(8)
3.048(2)
3.007(1)
3.0485(4)
2.410(7)
2.350(4)
2.46(2)
2.45(1)
2.411(9)
2.427(2)
136.4(4)
130.4
135(1)
137(1)
129.4
90.1(2)
94.2(1)
91.0(5)
89.7(3)
94.0(2)
93.24(5)
[10]
[17]
[10]
[10]
[17]
[15]
123.3
I(THF)]
[Er(h-Cp%%)2I(THF)]
[Yb(h-Cp)2I(THF)]
[Yb(h-Cp%%)2I(THF)] (1)
[Lu(h-C5Me4Pri)2Cl(THF)]
[Lu(h-C5H4SiMe3)(h-Cp%%)
1.00
0.98
0.98
0.97
0.97
2.640
2.565
2.62
2.645
2.605
2.931(1)
2.9316(7)
2.925(2)
2.516(2)
2.914(2)
2.335(7)
2.311(5)
2.303(13)
2.314(5)
2.310(10)
130.5
129.8
129.7
137.22(11)
131.3
94.1(2)
91.96(12)
93.3(3)
87.17(12)
93.5(3)
[17]
[16]
This work
[14]
[17]
I(THF)]
[Lu(h-Cp%%)2I(THF)]
0.97
2.611
2.896(1)
2.307(7)
130.7
93.8(2)
[17]
1. THF/20°C
2. hexane
YbCl3+2Li(Cp¦)ꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢁ
Initially we observed that treatment of Na(Cp%%) with
[Yb(OAr)2(THF)3] afforded 3 (l [171Yb] 206.1), but the
product was shown to be a mixture containing addi-
tionally [Yb(h-Cp%%)2(THF)2] (l [171Yb] 172.0) and
[Yb(OAr)2(THF)3] (l [171Yb] 237.7) [21]. A further mi-
nor product is believed to have been [Na(THF)x][Yb(h-
Cp%%)(OAr)2] (l [171Yb] 328.0). Synthesis of the complex
[K(THF)2][Yb(h-Cp*)2(OAr)], by the reaction of two
equivalents of K(Cp*) with [Sm(OAr)2(THF)3], has
been reported [12l].
The reaction of excess [Yb(OAr)2(THF)3] with
[Yb(h-Cp%%)2(THF)] in THF was studied by 171Yb-
NMR spectroscopy. The spectra recorded at 304 K
showed that [Yb(h-Cp%%)2(THF)2] [20] was still present
[Yb(h-Cp¦)2(m-Cl)2Li(THF)2]
(3)
2.5. X-ray crystal structure of
[Yb(p-Cp%%)2(v-Cl)2Li(THF)2] (2)2
The molecular structure and atom numbering scheme
for the crystalline complex 2 are shown in Fig. 2.
Selected bond lengths and angles are in Table 3 and are
available for comparison with those for [Nd(h-Cp%%)2(m-
Cl)2Li(THF)2] [9a]. Complex 2 has a distorted tetrahe-
dral geometry about both the ytterbium and lithium
atoms, these being bridged by two chloride ligands. The
central YbꢀCl(1)ꢀLiꢀCl(2) unit is essentially planar.
The cyclopentadienyl rings are incorporated in the typ-
ical bent metallocene arrangement. The angles about
the ytterbium atom decrease in the sequence
Cent(1)ꢀYbꢀCent(2)\Cent(1 or 2)ꢀYbꢀCl(2 or 1)\
Cent(2 or 1)ꢀYbꢀCl(1 or 2)\Cl(1)ꢀYbꢀCl(2), while
those about the lithium atom fall off in the sequence
Cl(1 or 2)ꢀYbꢀO(1 or 2)\Cl(1 or 2)ꢀYbꢀO(2 or 1):
O(1)ꢀLiꢀO(2)\Cl(1)ꢀYbꢀCl(2) [Cent(1) and Cent(2)
are the centroids of C(1)ꢀC(5) and C(12)ꢀC(16) rings,
respectively]. The YbꢀC bond lengths range from
,
2.581(2) to 2.677(6) A.
2.6. Formation of [Yb(p-Cp%%)(OAr)(THF)x] (3)
(OAr=OC6H2But2-2,6-Me-4)
The use of 171Yb-NMR spectroscopy in the study of
ytterbium(II) complexes [20] has allowed us to monitor
the formation of complex 3 via two synthetic pathways.
2 Note added in proof: crystals of 2 have independently been
X-ray-characterised in a paper which appeared after the submission
of this manuscript. The results are close to those reported here [27].
Fig. 2. Molecular structure and atom-labelling scheme [Yb(h-
Cp%%)2(m-Cl)2Li(THF)2] (2).

108
P.B. Hitchcock et al. / Journal of Organometallic Chemistry 613 (2000) 105–110
Table 3
3.3. Preparation of [Yb(p-Cp%%)2I(THF)] (1)
a
,
Selected bond lengths (A) and angles (°) for complex 2
YbI3(THF)2 (1.83 g, 2.62 mmol) was added as a solid
to a suspension of Na(Cp%%) (1.22 g, 5.24 mmol) in
diethyl ether (200 ml); the mixture was stirred for 20 h
at 20°C. The red suspension was filtered and the solvent
removed from the filtrate in vacuo to give a brown solid
which was extracted into hexane (50 ml). Cooling this
solution to −30°C afforded brown X-ray-quality single
crystals of 1 (1.53 g, 74%). Anal. Found: C, 39.2; H,
6.39. Calc. for C26H50ISi4Yb: C, 39.5; H, 6.37%.
YbꢀCent(1)
YbꢀCent(2)
LiꢀCl(1)
2.331
2.339
2.337(14)
2.330(13)
YbꢀCl(1)
YbꢀCl(2)
LiꢀO(1)
LiꢀO(2)
2.575(2)
2.582(2)
1.896(15)
1.979(15)
LiꢀCl(2)
Cent(1)ꢀYbꢀCent(2) 127.7
Cent(2)ꢀYbꢀCl(1) 110.5
Cent(2)ꢀYbꢀCl(2) 107.1
Cl(1)ꢀYbꢀCl(2)
Cl(1)ꢀLiꢀO(1)
Cl(2)ꢀLiꢀO(1)
O(1)ꢀLiꢀO(2)
YbꢀCl(1)ꢀLi
Cent(1)ꢀYbꢀCl(1)
Cent(1)ꢀYbꢀCl(2)
Cl(1)ꢀLiꢀCl(2)
Cl(1)ꢀLiꢀO(2)
Cl(2)ꢀLiꢀO(2)
YbꢀCl(1)ꢀLi
107.3
110.9
95.7(5)
104.9(6)
119.7(6)
89.1(3)
85.15(5)
123.2(7)
108.3(6)
106.0(7)
89.9(3)
a Cent(1) and Cent(2) are the centroids of the C(1)ꢀC(5) and
C(12)ꢀC(16) rings, respectively. Some comparisons with average bond
lengths (A) and angles (°) in [Nd(h-Cp%%)2(m-Cl)2Li(THF)2]: NdꢀClav
2.744, LiꢀClav 2.405, ClꢀNdꢀCl% 82.1(3), ClꢀLiꢀCl% 97.2(9) [9a].
3.4. Preparation of [Yb(p-Cp%%)2(v-Cl)2Li(THF)2] (2)
,
Ytterbium(III) chloride (0.93 g, 3.33 mmol) was
added to a solution of Li(Cp%%) (1.45 g, 6.72 mmol) in
THF (250 ml). The resultant mixture was stirred for 20
h at 20°C. The volatiles were removed in vacuo, to give
a red solid which was extracted into hexane (100 ml).
The extract was concentrated to ca. 50 ml. Cooling to
−30°C yielded X-ray quality crystals of 2 (1.76 g,
65%). Anal. Found: C, 44.1; H, 7.17. Calc. for
C30H58Cl2LiO2Si4Yb: C, 44.3; H, 7.18%.
in solution (l [171Yb] 172.0), along with 3 (l [171Yb]
206.1) and the unreacted ytterbium aryloxide complex
(l [171Yb] 237.7). Even with an excess of one or other of
the two starting components, ligand redistribution from
complex 3 still seemed to be taking place, with 3
existing in equilibrium with its parent precursor com-
plexes. Such behaviour has also been reported for
[Yb(OAr)I(THF)x] [12p]. The minor product observed
in the above preparative scale experiment was not
observed.
3.5. Preparation of [Yb(p-Cp%%)(OAr)(THF)x] (3)
Method A. To a solution of [Yb(OAr)2(THF)3] (2.36
g, 3.03 mmol) in THF (200 ml), a molar equivalent of
Na(Cp%%) (0.69 g, 2.97 mmol) was added and the resul-
tant mixture was stirred for 8 h at 20°C. The suspen-
sion was filtered and solvent removed from the filtrate
in vacuo to yield a red oil.
3. Experimental
3.1. General procedures
All manipulations were carried out under vacuum or
argon by Schlenk techniques. Solvents were dried and
distilled over potassium–sodium alloy under argon
prior to use. The following compounds were prepared
by published procedures: Na(Cp%%) [22], [Yb(OAr)2-
(THF)3] [23] and [Yb(h-Cp%%)2(THF)] [24]. Ytterbium
metal and YbCl3 were donated by Johnson Mathey
PLC. Microanalyses were carried out in the micro-ana-
lytical department of the University of Sussex. NMR
Spectra were recorded using Bruker WM360 or Bruker
500 spectrometers.
Method B. [Yb(OAr)2(THF)3] (2.53 g, 3.06 mmol) in
THF (100 ml) was added to a solution of [Yb(h-
Cp%%)2(THF)] (0.41 g, 0.62 mmol) in THF (100 ml). The
solution was stirred for 8 h at 20 °C and solvent was
removed under reduced pressure to yield a red oil.
[Yb(h-Cp%%)(OAr)(THF)x]
(3)
NMR:
1H
(C4H8OꢀC6D5CD3, 250.13 MHz), l 0.16 (s, 18H,
SiMe3), 1.32 (s, 18H, But), 1.58 (br s, b-CH2 (THF)),
2.19 (s, 3H, Me), 3.74 (br s, a-CH2 (THF)), 6.76 (m,
1H, C5H3), 6.84 (m, 2H, C5H3), 7.01 (s, 2H, C6H2);
171Yb-{1H} (C4H8OꢀC6D5CD3, 87.51 MHz, 25°C), l
206.1.
3.2. Preparation of YbI3(THF)2
[Yb(h-Cp%%)2(THF)2] NMR: 1H (C4H8OꢀC6D5CD3,
250.13 MHz), l 0.22 (s, 36H, SiMe3), 1.58 (br s, b-CH2
(THF)), 3.74 (br s, a-CH2 (THF)), 6.92 (m, 2H, C5H3),
6.98 (m, 4H, C5H3); 171Yb-{1H} (C4H8OꢀC6D5CD3,
87.51 MHz, 25°C), l 172.0.
Ytterbium metal powder (0.47 g, 2.72 mmol) was
added as a solid to a solution of ICH2CH2I (3.86 g,
13.70 mmol) in THF (250 ml); the mixture was stirred
for 20 h at 20°C, then filtered to give the pink precipi-
tate which was dried under vacuum to afford the
free-flowing powder of YbI3(THF)2 (1.83 g, 96%).
Anal. Found: C, 13.4; H, 2.22. Calc. for C8H16I3O2Yb:
C, 13.8; H, 2.31%.
[Yb(OAr)2(THF)3] NMR: 1H (C4H8OꢀC6D5CD3,
250.13 MHz), l 1.35 (s, 36H, But), 1.58 (br s, b-CH2
(THF)), 2.26 (s, 6H, Me), 3.74 (br s, a-CH2 (THF)),
6.92 (s, 4H, C6H2); 171Yb-{1H} (C4H8OꢀC6D5CD3,
87.51 MHz, 25°C), l 237.7.

P.B. Hitchcock et al. / Journal of Organometallic Chemistry 613 (2000) 105–110
109
3.6. X-ray structure determinations for
4. Supplementary material
[Yb(p-Cp%%)2I(THF)] (1) and
[Yb(p-Cp%%)2(v-Cl)2Li(THF)2] (2)
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 144235 for compound 1 and
CCDC no. 144236 for compound 2. Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge CB2
1EZ, UK (Fax: +44-1223-336033; e-mail: de-
posit@ccdc.cam.ac.uk or www: http//www.ccdc.cam.ac.
uk).
In both cases unique data were collected, using a
crystal sealed in a capillary under argon on an Enraf–
Nonius CAD4 diffractometer in the q−2q mode with
,
monochromated Mo–Ka radiation (u=0.71069 A).
For 1 two standard reflections showed a decrease in
intensity of 9.2% and a correction for this was applied.
Data were corrected for Lorentz and polarisation ef-
fects and also for absorption using DIFABS [25] after
isotropic refinement. Reflections with ꢀF2ꢀ\3|(F2),
where |(F2)={|2(I)+(0.04I)2}1/2/Lp were considered
observed. The structure was solved using the heavy
atom routines of SHELXS-86 [26]. Hydrogen atoms were
held fixed at calculated positions with Uiso=1.3 Ueq for
the parent atom.
Acknowledgements
We thank Johnson Matthey PLC for gifts of YbCl3
and ytterbium metal and for a CASE award for S.P.,
SERC for financial support, Dr G.A. Lawless for
recording 171Yb-NMR spectra, and Drs I. Lo´pez-Solera
and A.M. Rodriguez for useful discussion.
For 1, non-hydrogen atoms were refined with
isotropic thermal parameters by full-matrix least-
squares, with Yb and I anisotropic, using programs
from the Enraf–Nonius SDP-PLUS package. For 2, non-
hydrogen atoms were refined anisotropically by full-
matrix least-squares, except for the C atoms of the
THF groups which became non-positive and were
therefore refined isotropically. This probably reflects
slight conformational disorder in the THF groups. Fur-
ther details are given in Table 4.
References
[1] For recent leading organolanthanide reviews, see: (a) R. Anwan-
der, W.A. Herrmann, in: Topics in Current Chemistry, vol. 179,
Springer-Verlag, Berlin, 1996, pp. 1–32. (b) F.T. Edelmann, in:
Topics in Current Chemistry, vol. 179, Springer-Verlag, Berlin,
1996, pp. 247–276. (c) F.T Edelmann, in: E.W. Abel, F.G.A.
Stone, G. Wilkinson (Eds.), Comprehensive Organometallic
Chemistry II, vol.4, Pergamon Press, Oxford, 1995, pp. 11–212
(d) F.T Edelmann, Angew. Chem. Int. Ed. Engl. 34 (1995) 2466.
(e) H. Schumann, J.A. Meese-Marktscheffel, L. Esser, Chem.
Rev. 95 (1995) 865. (f) C.J. Schaverien, Adv. Organomet. Chem.
36 (1994) 283. (g) G.A. Molander, Chemtracts: Org. Chem. 11
(1998) 237.
Table 4
Crystal data and structure refinement
[Yb(h-Cp%%)2-
I(THF)] (1)
[Yb(h-Cp%%)2(m-Cl)2-
Li(THF)2] (2)
[2] (a) P.W. Roesky, U. Denninger, C.L. Stern, T.J. Marks,
Organometallics 16 (1997) 4486. (b) G.A. Molander, J.O.
Hoberg, J. Org. Chem. 57 (1992) 3266. (c) G. Jeske, H. Lauke,
H. Mauermann, P.N. Swepston, H. Schumann, T.J. Marks, J.
Am. Chem. Soc. 107 (1985) 8091. (d) W.J. Evans, I. Bloom,
W.E. Hunter, J.L. Atwood, J. Am. Chem. Soc. 105 (1983) 1401.
[3] (a) M.E. Thompson, S.M. Baxter, A.R. Bulls, B.J. Burger, M.C.
Nolan, B.D. Santarsiero, W.P. Schaefer, J.E. Bercaw, J. Am.
Chem. Soc. 109 (1987) 203. (b) W.E. Piers, J.E. Bercaw, J. Am.
Chem. Soc. 112 (1990) 9406. (c) K.H. den Hann, Y. Wielstra,
J.H. Teuben, Organometallics 6 (1987) 2053. (d) G. Jeske, L.E.
Schock, P.N. Swepston, H. Schumann, T.J. Marks, J. Am.
Chem. Soc. 107 (1985) 8103. (e) H.J. Heeres, J.H. Teuben,
Organometallics 10 (1991) 1980.
Empirical formula
Formula weight
Crystal system
Space group
Unit cell dimensions
C
26H50IOSi4Yb
C30H58Cl2LiO2Si4Yb
814.0
Monoclinic
P21/c
791.0
Orthorhombic
P212121
,
a (A)
10.930(2)
16.244(5)
20.033(5)
12.932(5)
19.530(5)
16.739(3)
99.22(2)
4224.3
4
,
b (A)
,
c (A)
i (°)
3
,
V (A )
Z
3556.9
4
Dcalc (g cm−3
)
1.48
36.3
1572
0.3×0.3×0.2
1.28
24.7
1668
0.8×0.4×0.4
7668
[4] (a) P.L. Watson, J. Am. Chem. Soc. 105 (1983) 6491. (b) P.L.
Watson, D.C. Roe, J. Am. Chem. Soc. 104 (1982) 6471. (c) G.
Jeske, H. Lauke, H. Mauermann, H. Schumann, T.J. Marks, J.
Am. Chem. Soc. 107 (1985) 8111. (d) C.J. Schaverien,
Organometallics 13 (1994) 69. (e) W.E. Piers, P.J. Shapiro, E.E.
Bunel, J.E. Bercaw, Synlett. (1990) 74. (f) P.J. Shapiro, E.E.
Bunel, W.P. Schaefer, J.E. Bercaw, Organometallics 9 (1990)
867. (g) R.E. Marsh, W.P. Schaefer, E.B. Caughlin, J.E. Bercaw,
Acta Cryst. C48 (1992) 1773. (h) M.A. Giardello, Y. Yamamoto,
L. Brard, T.J. Marks, J. Am. Chem. Soc. 117 (1995) 3276. (i) X.
Yang, A.M. Seyam, P.-F. Fu, T.J. Marks, Macromolecules 27
(1994) 4625. (j) H. Yasuda, E. Ihara, Macromol. Chem. Phys.
v(Mo–Ka) (cm−1
F(000)
)
Crystal size (mm)
Total unique reflections 3518
qmax (°)
25
2111
25
4797
Significant reflections
ꢀF2ꢀ\3|ꢀF2ꢀ
Variables
143
0.047, 0.059
321
0.031, 0.043
R, R% a
a R=S w(ꢀFoꢀ−ꢀFcꢀ)/(S wꢀFoꢀ); R%=[S w(ꢀFoꢀ−ꢀFcꢀ)2/(S wꢀFoꢀ )]1/2
.
2

110
P.B. Hitchcock et al. / Journal of Organometallic Chemistry 613 (2000) 105–110
196 (1995) 2417. (k) E. Ihara, M. Nodono, H. Yasuda, Macro-
mol. Chem. Phys. 197 (1996) 1909.
(g) C. Eaborn, P.B. Hitchcock, K. Izod, J.D. Smith, J. Am.
Chem. Soc. 116 (1994) 12071. (h) J.R. van den Hende, P.B.
Hitchcock, M.F. Lappert, J. Chem. Soc. Chem. Commun. (1994)
1413. (i) J.R. van den Hende, P.B. Hitchcock, M.F. Lappert, J.
Chem. Soc. Dalton Trans. (1995) 2251. (j) P.B. Hitchcock, S.A.
Holmes, M.F. Lappert, S. Tian, J. Chem. Soc. Chem. Commun.
(1994) 2691. (k) J.R. van den Hende, P.B. Hitchcock, S.A.
Holmes, M.F. Lappert, J. Chem. Soc. Dalton Trans. (1995)
3933. (l) Z. Hou, Y. Zhang, T. Yoshimura, Y. Wakatsuki,
Organometallics 16 (1997) 2963. (m) M.M. Corradi. A.D. Frank-
land, P.B. Hitchcock, M.F. Lappert, G.A. Lawless, Chem. Com-
mun. (1996) 2323. (n) J.M. Boncella, T.D. Tilley, R.A.
Andersen, J. Chem. Soc. Chem. Commun. (1984) 710. (o) G.M.
Ferrence, R. McDonald, M. Morissette, J. Takats, J.
Organomet. Chem. 596 (2000) 95. (p) J.R. van den Hende, P.B.
Hitchcock, S.A. Holmes, M.F. Lappert, W.-P. Leung, T.C.W.
Mak, S. Prashar, J. Chem. Soc. Dalton Trans. (1995) 1427. (q)
J.R. van den Hende, P.B. Hitchcock, S.A. Holmes, M.F. Lap-
pert, J. Chem. Soc. Dalton Trans. (1995) 1435. (r) L.N.
Bochkarev, M.N. Kholodilova, S.F. Zhiltsov, T.V. Guseva,
M.N. Bochkarev, G. Razuvaev, A. Zh. Obshch. Khim. 56(3)
(1986) 723. (s) F.G.N. Cloke, C.I. Dalby, P.B. Hitchcock, H.
Karamallakis, G.A. Lawless, J. Chem. Soc. Chem. Commun.
(1991) 779. (t) S.J. Swamy, H. Schumann, J. Organomet. Chem.
334 (1987) 1. (u) D.F. Evans, G.V. Fazakerley, R.F. Phillips, J.
Chem. Soc. Chem. Commun. (1970) 244.
[5] (a) M.R. Gagne´, C.L. Stern, T.J. Marks, J. Am. Chem. Soc. 114
(1992) 275. (b) Y. Li, T.J. Marks, J. Am. Chem. Soc. 118 (1996)
9295. (c) M.A. Giardello, V.P. Conticello, L. Brard, M.R.
Gagne´, T.J. Marks, J. Am. Chem. Soc. 116 (1994) 10241. (d)
M.R. Gagne´, L. Brard, V.P. Conticello, M.A. Giardello, C.L.
Stern, T.J. Marks, Organometallics 11 (1992) 2003. (e) Y. Li,
T.J. Marks, Organometallics 15 (1996) 3770. (f) Y. Li, T.J.
Marks, J. Am. Chem. Soc. 118 (1996) 707. (g) G.A. Molander,
E.D. Dowdy, J. Org. Chem. 63 (1998) 8983. (h) V.M. Arre-
dondo, F.E. McDonald, T.J. Marks, J. Am. Chem. Soc. 120
(1998) 4871. (i) Y. Li, T.J. Marks, J. Am. Chem. Soc. 120 (1998)
1757. (j) P.W. Roesky, C.L. Stern, T.J. Marks, Organometallics
16 (1997) 4705. (k) S. Tian, V.M. Arredondo, F.E. McDonald,
T.J. Marks, Organometallics 18 (1999) 2568. (l) V.M. Arre-
dondo, S. Tian, F.E. McDonald, T.J. Marks, J. Am. Chem. Soc.
121 (1999) 3633.
[6] (a) G.A. Molander, W.H. Retsch, Organometallics 14 (1995)
4570. (b) P.-F. Fu, L. Brard, Y. Li, T.J. Marks, J. Am. Chem.
Soc. 117 (1995) 7157. (c) G.A. Molander, M. Julius, J. Org.
Chem. 57 (1992) 6347. (d) T. Sakakura, H.-J. Lautenschlager,
M. Tanaka, J. Chem. Soc. Chem. Commun. (1991) 40.
[7] (a) P.-F. Fu, T.J. Marks, J. Am. Chem. Soc. 117 (1995) 10747.
(b) K. Koo, P.-F. Fu, T.J. Marks, Macromolecules 32 (1999)
981.
[8] (a) K.N. Harrison, T.J. Marks, J. Am. Chem. Soc. 114 (1992)
9220. (b) E.A. Bijpost, R. Duchateau, J.H. Teuben, J. Mol.
Catal. 95 (1995) 121.
[13] (a) P.L. Watson, T.H. Tulip, I. Williams, Organometallics 9
(1990) 1999. (b) P. Girard, J.L. Namy, H.B. Kagan, J. Am.
Chem. Soc. 102 (1980) 2693.
[9] (a) M.F. Lappert, A. Singh, J.L. Atwood, W.E. Hunter, J.
Chem. Soc. Chem. Commun. (1981) 1190. (b) R.E. Maginn, S.
Manastyrskyj, M. Dubeck, J. Am. Chem. Soc. 85 (1963) 672. (c)
J.N. John, M. Tsutsui, Inorg. Chem. 20 (1981) 1602. (d) T.J.
Marks, G.W. Grynkewich, Inorg. Chem. 15 (1976) 1302. (e) E.
Dornberger, R. Klenze, B. Kanellakopulos, Inorg. Nucl. Chem.
Lett. 14 (1978) 319. (f) M.F. Lappert, P.I.W. Yarrow, J.L.
Atwood, R. Shakir, J. Chem. Soc. Chem. Commun. (1980) 987.
(g) W.J. Evans, R. Dominguez, T.P. Hanusa, Organometallics 5
(1986) 1291. (h) H. Lueken, J. Schmitz, W. Lamberts, P. Hanni-
bal, K. Handrick, Inorg. Chim. Acta 156 (1989) 119. (i) W.
Lamberts, H. Lueken, B. Hassner, Inorg. Chim. Acta 134 (1987)
155. (j) H. Lueken, W. Lamberts, P. Hannibal, Inorg. Chim.
Acta 132 (1987) 111. (k) W. Lamberts, H. Lueken, U. Elsenhans,
Inorg. Chim. Acta 121 (1986) 81.
[10] W.J. Evans, J.W. Grate, K.R. Levan, I. Bloom, T.T. Peterson,
R.J. Doedens, H. Zhang, J.L. Atwood, Inorg. Chem. 25 (1986)
3614.
[11] (a) M.F. Lappert, A. Singh, J.L. Atwood, W.E. Hunter, J.
Chem. Soc. Chem. Commun. (1981) 1191. (b) J.L. Atwood,
W.E. Hunter, R.D. Rogers, J. Holton, J. McMeeking, R. Pearce,
M.F. Lappert, J. Chem. Soc. Chem. Commun. (1978) 140. (c)
T.D. Tilley, R.A. Andersen, Inorg. Chem. 20 (1981) 3267. (d)
P.L. Watson, J.F. Whitney, R.L. Harlow, Inorg. Chem. 20
(1981) 3271.
[14] H. Schumann, M.R. Keitsch, J. Winterfeld, S. Mu¨hle, G.A.
Molander, J. Organomet. Chem. 559 (1998) 181.
[15] W.J. Evans, D.A. Cano, M.A. Greci, J.W. Ziller, Organometal-
lics 18 (1999) 1381.
[16] G.B. Deacon, S.C. Harris, G. Meyer, D. Stellfeldt, D.L. Wilkin-
son, G. Zelesny, J. Organomet. Chem. 525 (1996) 247.
[17] Z. Xie, Z. Liu, F. Xue, Z. Zhang, T.C.W. Mak, J. Organomet.
Chem. 542 (1997) 285.
[18] D.R. Lide (Ed.), C.R.C. Handbook of Chemistry and Physics,
Chemical Rubber Publishing Company, 78th ed., Boca Raton,
Florida, 1997–98, pp. 4–121.
[19] M.F. Lappert, A. Singh, Inorg. Synth. 27 (1990) 168.
[20] A.G. Avent, M.A. Edelman, M.F. Lappert, G.A. Lawless, J.
Am. Chem. Soc. 111 (1989) 3423.
[21] [Yb(h-Cp%%)2(THF)] in THF forms the bis-THF adduct [Yb(h-
Cp%%)2(THF)2] in a reversible process similar to that previously
observed for [Sm(h-Cp%%)2(THF)]. P.B. Hitchcock, M.F. Lappert,
S. Prashar, J. Organomet. Chem. 413 (1991) 79.
[22] P.B. Hitchcock, J.A.K. Howard, M.F. Lappert, S. Prashar, J.
Organomet. Chem. 437 (1992) 177.
[23] G.B. Deacon, P.B. Hitchcock, S.A. Holmes, M.F. Lappert, P.I.
MacKinnon, R.H. Newnham, J. Chem. Soc. Chem. Commun.
(1989) 935.
[24] P.B. Hitchcock, M.F. Lappert, S. Prashar, J.A.K. Howard, in:
W.A. Herrmann (Ed.), Synthetic Methods of Organometallic
Chemistry, vol. 6, Thieme Verlag, Stuttgart, 1997, pp. 60–62
Chapter 2.
[25] N. Walker, D. Stuart, Acta Crystallogr. Sect A 39 (1983) 158.
[26] G.M. Sheldrick, in: G.M. Sheldrick, C. Kru¨ger, R Goddard
(Eds.), Crystallographic Computing 3, Oxford University Press,
London, 1985, pp. 175–189.
[12] (a) S.P. Constantine, G.M. De Lima, P.B. Hitchcock, J.M.
Keates, G.A. Lawless, Chem. Commun. (1996) 2421. (b) L.
Hasinoff, J. Takats, X.W. Zhang, J. Am. Chem. Soc. 116 (1994)
8833. (c) G.H. Maunder. A. Sella, D.A. Tocher, J. Chem. Soc.
Chem. Commun. (1994) 2689. (d) D.J. Duncalf, P.B. Hitchcock,
G.A. Lawless, Chem. Commun. (1996) 269. (e) W.J. Evans,
D.K. Drummond, H. Zhang, J.L. Atwood, Inorg. Chem. 27
(1988) 575. (f) W.J. Evans, J.W. Grate, H.W. Choi, I. Bloom,
W.E. Hunter, J.L. Atwood, J. Am. Chem. Soc. 107 (1985) 941.
[27] H.-S. Chan, Q. Yang, T.C.W. Mak, Z. Xie, J. Organomet.
Chem. 601 (2000) 160.
.