β-Diiminatolanthanoid(III) halides revisited

Article abstract of DOI:10.1016/j.ica.2009.06.025

The crystalline compounds [LnCl₂(L)(thf)₂] [Ln = Ce (1), Tb (2), Yb (3)], [NdI₂(L)(thf)₂] (4), [LnCl(L′)₂] [Ln = Tb (5), Yb (6) (a known compound)] and [YbCl(L′′)(μ-Cl)₂Li(OEt₂)₂] (7) have been prepared [L = {N(C₆H₃Prⁱ₂-2,6)C(H)}₂CPh, L′ = {N(SiMe₃)C(Ph)}₂CH, L′′ = {N(SiMe₃)C(C₆H₄Ph-4)}₂CH]. The X-ray molecular structures of 2-7 have been established; in each, the monoanionic ligand L, L′ or L′′ is N,N′-chelating and essentially π-delocalised. Each of 1-7 was prepared from the appropriate LnCl₃, or for 4 [NdI₃(thf)₂], and an equivalent portion of the appropriate alkali metal [Li for 7, Na for 2, 3 and 5, or K for 1, 4 and 6] β-diiminate in thf; the isolation of exclusively 5 and 6 (rather than the L′ analogues of 2 or 3) is noteworthy, as is the structure of 7 which has no precedent in Group 3 or 4f metal β-diiminato chemistry.

Full text of DOI:10.1016/j.ica.2009.06.025

Inorganica Chimica Acta 362 (2009) 4678–4684
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b-Diiminatolanthanoid(III) halides revisited
*
Yanxiang Cheng, Peter B. Hitchcock, Alexei V. Khvostov, Michael F. Lappert
Department of Chemistry and Biochemistry, University of Sussex, Brighton, BN1 9QJ, UK
a r t i c l e i n f o
a b s t r a c t
The crystalline compounds [LnCl2(L)(thf)2] [Ln = Ce (1), Tb (2), Yb (3)], [NdI2(L)(thf)2] (4), [LnCl(L0)2]
Article history:
[Ln = Tb (5), Yb (6) (a known compound)] and [YbCl(L00)(
l-Cl)2Li(OEt2)2] (7) have been prepared
Received 8 January 2009
Accepted 16 June 2009
Available online 21 June 2009
[L = {N(C6H3Pri2-2,6)C(H)}2CPh, L0 = {N(SiMe3)C(Ph)}2CH, L00 = {N(SiMe3)C(C6H4Ph-4)}2CH]. The X-ray molec-
ular structures of 2–7 have been established; in each, the monoanionic ligand L, L0 or L00 is N,N0-chelating and
essentially p-delocalised. Each of 1–7 was prepared from the appropriate LnCl3, or for 4 [NdI3(thf)2], and an
Keywords:
equivalent portion of the appropriate alkali metal [Li for 7, Na for 2, 3 and 5, or K for 1, 4 and 6] b-diiminate
in thf; the isolation of exclusively 5 and 6 (rather than the L0 analogues of 2 or 3) is noteworthy, as is the
structure of 7 which has no precedent in Group 3 or 4f metal b-diiminato chemistry.
Ó 2009 Elsevier B.V. All rights reserved.
N,N0-ligands
Bis(b-diiminato)metal complexes
Lanthanoid(III) derivatives
1. Introduction
b-Diiminatolanthanoid(III) halides and their scandium and yt-
trium analogues are useful precursors to a wide range of corre-
This paper deals with the synthesis and characterisation of se-
ven crystalline b-diiminatolanthanoid(III) halides [LnCl2(L)(thf)2]
[Ln = Ce (1), Tb (2), Yb (3)], NdI2(L)(thf)2] (4), [LnCl(L0)2] [Ln = Tb
sponding metal complexes. The first of these to be reported and
X-ray-characterised were [LnBr(LR)2] (Ln = Sm, Gd; R = Pri) [1a],
[GdBr2(LR)(thf)2] (R = Ph) [1b] and [NdCl(L0)2] [2]; the isoleptic
Ce, Pr, Sm, Yb chlorides have also been prepared [2]. The complex
[ScCl2(LR)(thf)2] (R = C6H3Pri2-2,6) and an analogue with But instead
of Me substituents were the forerunners of related compounds,
including 1–3 [3]. The synthesis and some reactions of
[YbCl2(LR)(thf)2] (R = C6H3Pri2-2,6) have been presented [4]. The
(5), Yb (6)] and [Yb(L00)Cl(
l
-Cl)2Li(OEt2)2] (7), including the molec-
ular structures of 2–7. The ligand L, L0 and L00 in each of 1–7 is
monoanionic, N,N0-chelating and essentially
p-delocalised, as are
LR (R = a hydrocarbyl group) in related Ln(III) compounds described
in the literature.
H
H
C
Ph
C
Me
R
C
Me
R
Ar
Ar
H
H
C
N
C
N
C
N
C
N
C
N
C
N
C6H3Pri2-2,6
2,6-Pri2C6H3
Me3Si
SiMe3
LR
L
L' (Ar = Ph)
L" (Ar = C6H4Ph-4)
preparation, reactions and structures of [LnCl2(LR)(thf)2]
(R = C6H3Me2-2,6) and the LR (R = Ph) analogues as well as
[LnCl2{N(C6H3Pri2-2,6)-C(Me)C(H)C(Me)NC6H4Cl-4}(thf)2] (Ln = Sm,
Yb) have been studied [5]. The hetero-binuclear compounds
* Corresponding author. Tel.: +44 1273 876687; fax: +44 1273 876687.
E-mail address: m.f.lappert@sussex.ac.uk (M.F. Lappert).
[LnCl(LR)(thf)(
l-Cl)2Li(thf)2] (Ln = Nd, Sm, Tb, Yb; R = C6H3Me2-2,6)
0020-1693/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2009.06.025

Y. Cheng et al. / Inorganica Chimica Acta 362 (2009) 4678–4684
4679
were investigated [6]. We have recently described the crystalline
diiminatoyttrium chlorides [YCl2(L)(thf)2], [YCl2(LR)(thf)2] (R =
C6H4But-2), [YCl(L0)2] and the complexes A and B [7]. The homo-
binuclear compound [SmCl(LR)( -Cl)3Sm(LR)(thf)] was obtained
l
from SmCl3 and K(LR) (R = C6H3Pri2-2,6) in thf [8].
(Lig)2
(OEt2)
Li
Li
LC H R-2
Cl
Y
6
4
Cl
Y
Cl
Cl
Cl
i
i
2-2,6
Y
LC H Pr
LC H Pr
2-2,6
6
3
6
3
Y
Cl
Cl
Cl
LC H R-2
6
4
Cl
Cl
Li
Li
(OEt2)
(Lig)2
A: R = Pri, But
B: Lig = OEt2, thf
Whilst there is now a substantial literature on b-diketiminato-
metal compounds, with more than 100 publications since 2005, lit-
tle has been published on b-dialdiminato analogues. The ligand L
first featured in Cu(I) chemistry [9a]; the X-ray structure and the
chemiluminescent behaviour of [Cu(L)(PPh3)] has been reported
[9b]. Other publications on L complexes relate to [Tl(L)] [9c] and
various indium [9d] and arsenic [9e] complexes.
Fig. 1. Molecular structure of crystalline 2 (50% thermal ellipsoids).
2. Results and discussion
The C, H, N microanalytical data, again except for 3, was grati-
fying. Detailed analysis of the 1H and 13C NMR spectra of these
paramagnetic molecules was undertaken, by Dr. A.G. Avent, only
for the terbium compound 2; the solvent selected was CDCl3 and
the assignments showed that the solution structure was consistent
with that for the solid, as revealed by X-ray diffraction. Each of 1–4
was only sparingly soluble in various hydrocarbon solvents,
including benzene.
The molecular structures of distorted octahedral 2, 3 and 4 were
determined by single crystal X-ray diffraction, as illustrated in Figs.
1–3, respectively. Table 1 lists important geometric data, together
with selected parameters for [YCl2(L)(thf)2] [7]; the latter shows
close correspondence with those of the terbium compound 2. In
each of these molecules the NCCCN0 core atoms of the L ligand
are essentially coplanar; in 2 and 3 the metal atom is only slightly
out of this plane (ca. 0.1 Å), whilst in 4 the Nd atom is displaced by
This is divided into three parts: dealing sequentially with
mono-b-dialdiminatolanthanoid(III) halides, bis(b-diketimina-
to)lanthanoid(III) chlorides, and
chloride.
a
hetero-binuclear (Yb/Li)
2.1. The synthesis and structures of the crystalline complexes 1–4
The crystalline b-dialdiminatolanthanoid(III) halides 1–4 were
prepared as shown in Scheme 1 from the appropriate LnCl3 (Ce,
Tb) or a thf-adduct LnHal3(thf)n (Yb/Cl, Nd/I). The sodium or potas-
sium, rather than lithium, b-dialdiminate was chosen as the ligand
transfer reagent, as the use of Li(L) might have favoured the forma-
tion of hetero-binuclear Ln(III)/Li complexes (cf., 7). No attempt
was made to optimise yields, and in this respect the outcome for
the ytterbium compound 3 was unsatisfactory.
Scheme 1. Synthesis of 1–4.

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Y. Cheng et al. / Inorganica Chimica Acta 362 (2009) 4678–4684
kinetically fragile LnCl2(L0)(thf)n, Eq. (1). An alternative, and possi-
bly a more likely, explanation is that upon concentrating the solu-
tion from the 1:1 reaction, the lower solubility of the products of
Eq. (1) is the driving force for the forward reaction.
thf
2LnCl2ðL0ÞðthfÞ ! ½LnClðL0Þ ꢀ þ LnCl3ðthfÞ
ð1Þ
n
2
n
Complex 6 had previously been obtained (in 57% yield) by the
more rational procedure from YbCl3 and 2K(L0) in thf [2]; its char-
acterisation was then based on good C, H and N microanalyses and
its EI-mass spectrum. It is noteworthy that the Ce analogue of 6
even with only one equivalent of Li[CH(SiMe3)2] had yielded [Ce-
{CH(SiMe3)2}2(L0)] [2], possibly via a transient Ce{CH(SiMe3)2}(L0)2.
The molecular structures of the isomorphous crystalline com-
pounds 5 and 6 were established by single crystal X-ray diffraction,
as illustrated in Fig. 4 for 6 and the selected geometric data listed in
Table 2, which includes earlier results for the isoleptic neodymium
compound [2]. For the new compound 5, additional Supporting
information relates to its satisfactory C, H and N microanalyses
and IR and EI-mass spectral data; attempts to record 1H NMR spec-
tra in C4D8O failed. For 6, the earlier data [2] has now been supple-
mented by 1H and 13C{1H} NMR solution data in C4D8O; the former
spectrum was closely similar to that previously recorded in C7D8
[2]. The geometry around the metal in each of these molecules is
that of a distorted trigonal bipyramid, with one of the nitrogen
atoms of each of the b-diketiminato ligands (N1 and N4) occupying
Fig. 2. Molecular structure of crystalline 3 (50% thermal ellipsoids).
an axial position. As for 2–4, the
p-delocalised NCCCN’ core atoms
of the ligands are almost coplanar.
2.3. The synthesis and structure of the crystalline complex 7
The crystalline heterobimetallic Yb/Li complex 7 was obtained
as the monoetherate in modest yield from equivalent portions of
YbCl3 and Li(L”)(thf) in thf and subsequent crystallisation from
diethyl ether, Scheme 3. Its molecular structure is illustrated in
Fig. 5 and selected geometrical parameters are listed in Table 3.
The ytterbium atom is at the centre of a much distorted square
pyramid, the basal plane of which comprises the atoms
N1N2Cl2Cl1. Thus the widest angles subtended at the ytterbium
atom are N2–Yb–Cl1 and N1–Yb–Cl2 and the narrowest are N1–
Yb–N2 and C1–Yb–Cl2. The core of the Yb-L00 moiety,
YbN1C1C2C3N2, has a boat conformation in which the angle be-
tween the N1C1C3N2 and N1YbN2 or C1C2C3 planes is 106 and
160°, respectively. The lithium atom is at the centre of the dis-
torted Cl1O1O2Cl2 tetrahedron, in which the angles most deviant
from sp3 values are Cl1–Li–Cl2 and Cl1–Li–O2 at 96.2(3) and
119.5(4)°, respectively. Heterobimetallic Ln/Li complexes related
to 7 are well established for cyclopentadienyls, as first demon-
Fig. 3. Molecular structure of crystalline 4 (50% thermal ellipsoids).
strated for [Nd{
has just one antecedent in Group 3 or 4f metal b-diiminato chem-
istry, [NdCl(LC6H3Me2-2,6)(
-Cl)2Li(thf)2] [6], although alternative
g l-Cl)2Li(thf)2] [10], but 7
5-C5H3(SiMe3)2-1,3}2(
l
0.868(5) Å off the NC1C10N0 plane. It is evident that there is very
substantial
-delocalisation in the NCCCN0 moiety; this is particu-
larly clear for 4, since that molecule lies on a crystallographic mir-
ror plane; and for 2 and 3 the pairs of M–N, N–C and C –Cb bond
geometries are established as shown in A and B [7]. The bond
lengths for the Yb-L00 core and the Yb–Clterminal bond are available
for comparison with those in 3 and 6; whilst there is broad similar-
ity, the Yb–N and Yb–Cl bonds are somewhat shorter for 7, whilst
p
a
a
lengths are closely similar (the largest deviation being for the N–C
values for 3) and each of the latter two pairs has an intermediate
bond distance between a single and double NC and CC bond.
a
the C –Cb bonds for 7 are longer.
a
In conclusion, the synthesis of seven (6 previously known) crys-
talline b-diiminatolanthanoid(III) halides and the molecular struc-
tures of six of them are reported. In each of these, the ligand is
N,N0-chelating and substantially
p
-delocalised. Whilst the struc-
2.2. The synthesis and structures of the crystalline complexes 5 and 6
tures of 2–6 are unexceptional, that of [YbCl(L00)(
l-Cl)2Li(OEt2)2]
The crystalline bis(b-diketiminato)lanthanoid chlorides 5 and 6
were prepared as shown in Scheme 2 from Na(L0) or K(L0) with two
equivalents of TbCl3 or [YbCl3(thf)2], respectively. This unexpected
outcome is attributed to the rapid redistribution of the appropriate
(7) has just a single precedent amongst Group 3 or 4f metal b-dii-
minates. The exclusive formation of [LnCl(L0)2] [Ln = Tb (5), Yb (6)]
from the appropriate LnCl3 precursor and only one equivalent of
M(L0) (M = Na, K) is also noteworthy.

Y. Cheng et al. / Inorganica Chimica Acta 362 (2009) 4678–4684
4681
Table 1
Selected bond lengths (Å) and angles (°) for 2, 3, 4 and [YCl2(L)(thf)2] [7].
2 (M = Tb, Hal = Cl)
3 (M = Yb, Hal = Cl)
4 (M = Nd, Hal = I)
[YCl2(L)(thf)2] [7]
M–N
N–C
2.392(2), 2.399(2)
1.315(3), 1.321(3)
1.401(3), 1.402(3)
2.6046(6), 2.5941(6)
2.393(2), 2.428(2)
79.22(6)
2.330(7), 2.334(7)
1.308(12), 1.336(11)
1.399(13), 1.386(13)
2.544(2), 2.536(2)
2.356(6), 2.4950(15)
81.8(3)
2.4369(17)
1.322(3)
1.393(2)
3.0963(3), 3.0688(3)
2.4950(15)
73.68(8)
2.3766(17), 2.3746(18)
1.324(3), 1.320(3)
1.400(3), 1.400(3)
2.5724(6), 2.5823(6)
2.3586(16), 2.381(4)
80.52(6)
a
C –Cb
a
M–Hal
M–O
N–M–N’
M–N–C
128.20(5), 128.02(14)
129.2(2), 129.0(2)
126.1(2)
126.8(6), 126.5(6)
129.2(9), 129.7(9)
126.0(8)
126.92(14)
127.7(2)
124.0(3)
126.88(14), 126.91(14)
129.3(2), 129.3(2)
126.5(2)
a
N–C –Cb
a
C –Cb–C
a
a
’
N–M–O
175.38(16), 173.40(6)
96.07(6), 97.59(6)
100.62(4), 100.40(5)
93.00(4), 92.98(5)
162.49(2)
176.2(3), 175.4(3)
95.8(3), 97.6(3)
100.0(2), 99.49(19)
92.6(2), 92.26(19)
163.89(8)
170.10(6)
97.17(6)
100.16(14)
91.93(4)
161.055(8)
82.34(4)
84.49(4)
176.80(13), 175.88(6)
96.45(6), 97.70(13)
99.87(4), 99.69(5)
92.75(4), 92.63(4)
163.63(2)
N–M–Hal
Hal–M–Hal’
Hal–M–O
82.80(4), 84.27(4)
83.30(4), 84.37(4)
83.91(18), 83.95(18)
84.13(18), 84.29(18)
83.29(4), 83.18(10)
84.83(10), 84.65(4)
Symmetry transformations used to generate equivalents atoms for 4: x, ꢁy + 1/2, z.
Scheme 2. Synthesis of 5 and 6.
The solvents used were reagent grade or better and were freshly
distilled under dry nitrogen gas and freeze/thaw degassed prior
to use. Diethyl ether and thf were dried and distilled from sodium
benzophenone. C6D6, C7D8 and C4D8O for NMR spectroscopy were
stored over molecular sieves (4 Å) under an argon atmosphere. Ele-
mental analyses were provided by the University of North London.
Melting points were taken in sealed capillaries. The 1H and 13C
NMR spectra were recorded in a deuterated solvent and were ref-
erenced internally to residual solvent resonances, at ambient tem-
perature using a Bruker DPX 300 machine. Electron impact mass
spectra were taken from solid samples using a Kratos MS 80 RF
instrument. IR spectra were measured on a Perkin–Elmer 1720
FT spectrometer, as KBr discs. The complexes Li(L00) [11], Na(L0)
and K(L0) [12], Na(L) [9c] and K(L) [9e] were prepared by published
procedures. The compounds LnCl3 (Ln = Ce, Tb, Yb), [YbCl3(thf)3]
and [NdI3(thf)2] were purchased and were rigorously dried before
use.
3. Experimental
3.1. General remarks
Syntheses were carried out under an atmosphere of argon or in
a vacuum, using Schlenk apparatus and vacuum line techniques.
3.2. Preparations of [CeCl2(L)(thf)2] (1)
A solution of K(L) (1.19 g, 2.36 mmol) in thf (30 cm3) was added
to a solution of CeCl3 (0.56 g, 2.27 mmol) in thf (20 cm3) at ambient
temperature, whereafter the mixture was heated under reflux for
24 h. Volatiles were then removed in vacuo and the residue was ex-
tracted with diethyl ether (60 cm3). The light orange filtered ex-
tract was concentrated to ca. 20 cm3; after one day, small orange
crystals of 1 (1.56 g, 84%) (C41H57CeCl2N2O2 requires C, 60.0; H,
7.00; N, 3.41. Found: C, 60.1; H, 7.12; N, 3.51%), mp 181–182 °C
(decomp.) were obtained. EI-MS [m/e (assignment and rel.
Fig. 4. Molecular structure of crystalline 6 (50% thermal ellipsoids).

4682
Y. Cheng et al. / Inorganica Chimica Acta 362 (2009) 4678–4684
Table 2
Selected bond lengths (Å) and angles (°) for 5, 6 and [NdCl(L0)2] [2].
5 (M = Tb)
6 (M = Yb)
[NdCl(L0)2] [2]
M–N1 (M–N4)
M–N2 (M–N3)
N1–C1 (N4–C24)
N2–C3 (N3–C22)
C1–C2 (C24–C23)
C2–C3 (C23–C22)
M–Cl
2.379(2), 2.383(2)
2.332(2), 2.330(2)
1.328(4), 1.325(4)
1.331(4), 1.336(4)
1.421(4), 1.432(4)
1.412(4), 1.408(4)
2.5872(8)
78.99(8), 79.42(8), 99.88(8)
178.35(8), 125.44(9), 102.63(8)
124.2(3), 98.19(17)
100.99(18), 99.50(18)
124.2(3), 123.5(3)
123.1(3), 123.4(3)
89.24(6), 89.83(6)
114.07(6), 120.47(6)
2.314(3), 2.318(3)
2.282(3), 2.271(3)
1.330(4), 1.329(4)
1.337(4), 1.344(4)
1.418(4), 1.420(4)
1.410(5), 1.410(5)
2.5154(8)
80.69(9), 81.17(9), 97.99(9)
179.16(10), 124.23(9), 99.75(9)
102.4(2), 99.55(19)
101.5(2), 102.62(19)
124.0(3), 123.4(3)
123.2(3), 123.3(3)
89.84(7), 90.61(7)
115.31(7), 120.45(7)
2.447(6), 2.464(6)
2.397(6), 2.410(6)
1.334(9), 1.304(9)
1.334(9), 1.309(9)
1.455(10), 1.431(10)
1.372(11), 1.416(10)
2.655(2)
77.6(2), 76.5(2), 104.3(2)
178.6(2), 124.1(2), 110.9(2)
112.3, 111.1
N–M–N0
M–N–C
a
N–C –Cb
122.9(6), 123.4(6)
124.4(6), 124.8(7)
90.4(1), 90.4(1)
a
N–M–Cl
114.2(1), 121.6(1)
Scheme 3. Synthesis of 7.
intensity, %)]: 675 ([Mꢁ2thf]+, 6), 640 ([CeCl(L)]+, 2), 615 ([Ce(L)]+,
4). Compound 1 (like 2, 3 and 4) was sparingly soluble in C6D6.
from light brown to orange. The mixture was heated at 60 °C under
reflux for ca. 12 h. Volatiles were removed in vacuo and the residue
was extracted with diethyl ether (60 cm3). The filtered extract was
concentrated to ca. 20 cm3 and set aside at 15 °C for 12 h, whereaf-
ter light yellow crystals of 2 (1.39 g, 85%) (C41H57Cl2N2O2Tb re-
quires C, 58.6; H, 6.84; N, 3.34. Found: C, 58.7; H, 6.85; N, 3.28%),
mp 109–110 °C (decomp.) were obtained. For 1H and 13C NMR data
in CDCl3, see Section 3.4. IR [KBr disc; mmax (strong bands only)]:
2960, 1634, 1548, 1284, 757 cmꢁ1. EI-MS [m/e (assignment and
rel. intensity,%)]: 694 ([Mꢁ2thf]+, 62).
3.3. Preparation of [TbCl2(L)(thf)2] (2)
A solution of Na(L) (0.97 g, 1.98 mmol) in thf (30 cm3) was
added to
a suspension of TbCl3 (0.52 g, 1.96 mmol) in thf
(20 cm3) at ambient temperature. The terbium chloride disap-
peared in about 10 min and the colour of the mixture changed
Table 3
Selected bond lengths (Å) and angles (°) for 7.
Yb–N1
Yb–N2
N1–C1
N2–C3
C1–C2
C2–C3
N1–Si1
N2–Si2
Li–O1
2.250(3)
2.263(3)
1.334(5)
1.325(5)
1.440(6)
1.422(6)
1.760(4)
1.765(3)
1.923(9)
C1–C10
C3–C22
Yb–Cl1
Yb–Cl2
Yb–Cl3
Li–Cl1
1.491(6)
1.505(6)
2.5890(11)
2.6054(12)
2.4860(12)
2.370(8)
Li–Cl2
Li–O2
2.362(8)
1.940(9)
N1–Yb–N2
Yb–N1–C1
Yb–N2–C3
N1–C1–C2
N2–C3–C2
C1–C2–C3
C1–N1–Si1
C3–N2–Si2
N1–C1–C10
N2–C3–C22
82.18(12)
95.8(3)
96.5(2)
121.9(4)
124.0(4)
127.5(4)
130.2(3)
130.4(3)
122.3(4)
121.7(4)
N1–Yb–Cl1
N2–Yb–Cl2
N1–Yb–Cl2
N2–Yb–Cl1
N1–Yb–Cl3
N2–Yb–Cl3
Cl2–Yb–Cl3
Cl1–Yb–Cl3
Cl1–Li–Cl2
Cl1–Yb–Cl2
90.74(9)
88.28(9)
150.15(9)
153.71(9)
104.99(9)
104.42(9)
104.77(4)
101.87(4)
85.41(4)
85.41(4)
Fig. 5. Molecular structure of crystalline 7 (20% thermal ellipsoids).

Y. Cheng et al. / Inorganica Chimica Acta 362 (2009) 4678–4684
4683
3.4. Assignment of the 1H and 13C NMR spectra in CDCl3 of 2 (by Dr.
A.G. Avent)
(20 cm3) at ambient temperature. After 48 h, the brown mixture
was concentrated to ca. 5 cm3 and extracted with Et2O (50 cm3).
The orange extract was concentrated to ca. 20 cm3 and after one
day at 15 °C furnished red crystals of 4 (0.68 g, 70%), mp 175–
176 °C (C41H57I2N2NdO2 requires C, 48.9; H, 5.70; N, 2.78. Found:
C, 48.7; H, 5.84; N, 2.76%). 1H NMR (C7D8): d 53.0 (s, 2 H), 14.85
(s, 2 H), 12.6 (br, 8 H), 10.4 (s, 2 H), 9.15 (s, 1 H), 7.78 (br, 8 H),
5.13 (s, 6 H), 3.35 (s, 12 H), ꢁ6.58 (s, 12 H), ꢁ9.20 (br, 4 H) ppm;
13C{1H} NMR (C7D8): d 159.6, 146.1, 142.4, 132.4, 130.6, 125.8,
119.1, 74.6 (br), 37.0, 29.4, 23.7, 15.7, 14.5 (br) ppm.
17
18
16
15
19
14
3
4
2
3.7. Preparation of [TbCl(L0)2] (5)
A solution of Na(L’) (1.80 g, 4.63 mmol) in thf (40 cm3) was
added to a stirred suspension of TbCl3 (1.14 g, 4.30 mmol) in thf
(30 cm3) at room temperature. Stirring was continued for ca.
48 h, whereafter the mixture was filtered. The yellow filtrate was
concentrated to ca. 20 cm3 and set aside at 15 °C for ca. 12 h, to
give yellow microcrystals of 5 (1.28 g, 64.3%, based on TbCl3).
(C42H58ClN4Si4Tb requires C, 54.5; H, 6.32; N, 6.05. Found: C,
54.3; H, 6.42; N, 5.90%), mp 226 °C (decomp.). IR [KBr disc; mmax
(strong bands only)]: 2956, 1614, 1536, 1252, 842, 756 cmꢁ1. EI-
MS [m/e (assignment and rel. intensity, %)]: 925, ([M]+, 28), 890
([Tb(L0)2]+, 4), 559 ([TbCl(L0)]+, 57). An attempt to record 1H NMR
spectra failed; the paramagnetism of 5 in thf-d8 was too pro-
nounced to lock the field. X-ray quality crystals of 5 were grown
from thf/Et2O.
5
1
N
N
10
9
6
Tb
7
12
8
11
13
X
For the purpose of assignment, the 13C (1H) atom labels are
shown in X (the thf CH2’s are excluded). Consistent with this struc-
ture, nine 1H (in intensity ratios: 24:8:8:1) and thirteen 1H-coupled
13C peaks were observed in the NMR spectra in CDCl3. Of the seven
CH’s only five appeared as doublets, two being singlets (because
their protons were relaxing too rapidly): at sites 2/4, 8/10, 9, 11,
15/19, 16/18, and 17. The 1H signal at d ꢁ86.6 ppm and the 13C at
ꢁ30.5 ppm are assigned to 8/10 because of the 1H intensity (4)
and the sp2 1J coupling. The other intense (4) 1H signals must be
the methine at C11 at d ꢁ128.6 ppm, but this was relaxing too rap-
idly to couple to its 13C nucleus. The d (1H) at d ꢁ63.6 ppm and the
13C at d ꢁ1.9 ppm is assigned to sites 2/4, because of the large
1J(13C–1H) of 190 Hz. The 1H at d 69.1 ppm and the 13C at d
206.3 ppm is assigned to site 17 on the basis of the 1H intensity,
although the 1J(13C–1H) of 110 Hz is smaller than expected. This
leaves three CH’s at sites 9, 15/19, and 16/18 as the protons at d
156.2 ppm (coupled to 13C at d 271.4 ppm), 139.0 ppm (relaxing
too fast to couple), and d 64.7 ppm (coupled to 13C at d 229.2 ppm).
Finally, the six 13C singlets comprise the four quaternary car-
bons (6, 7, 3, 14) and two CH’s with rapidly relaxing protons (11
and ANO) which are at d 863.4, 611.7, 419.1, ꢁ90.0, ꢁ160.7, and
ꢁ163.1 ppm.
3.8. Preparation of [YbCl(L0)2] (6)
A mixture of K(L0 (0.46 g, 1.14 mmol) and [YbCl3(thf)3] (0.52 g,
1.05 mmol) suspended in thf (40 cm3) was stirred for ca. 24 h at
ambient temperature, then filtered. The filtrate was concentrated
(to ca. 10 cm3) and Et2O (10 cm3) was added. The resulting bright
yellow solution was cooled to ꢁ7 °C and maintained at that tem-
perature for ca. 12 h, whereafter yellow crystals of 6 [0.23 g, 43%
based on K(L0], mp 159 °C (decomp.) were obtained. 1H NMR
(C4D8O): d 11.1 (br, 4 H), 10.4 (br, 8 H), 7.3 (s, 2 H), ꢁ0.04 (s, 4
H), ꢁ18.0 (br, 36 H) ppm; 13C{1H} NMR (C4D8O): d 171.0, 144.2,
138.8, 136.1, 135.4, 129.1, 128.7, 127.8, 102.7, 15.7, 1.9,
ꢁ21.9 ppm. IR [KBr disc; mmax (strong bands only)]: 2960, 1536,
1488, 1254, 842, 756 cm-1. EI-MS [m/e (assignment and rel. inten-
sity, %)]: 939, ([M]+, 7), 831 ([Yb(L0)2–SiMe3]+, 5), 574 ([YbCl(L0)]+,
7.5).
3.9. Preparation of [YbCl(L00)(
l-Cl)2Li(OEt2)2] (7)
3.5. Preparation of [YbCl2(L)(thf)2] (3)
YbCl3 (1.22 g, 4.37 mmol) was added to a stirred solution of
[Li(L00)(thf)] (2.60 g, 4.36 mmol) in thf (150 cm3). The resulting yel-
low solution was set aside for 24 h at ambient temperature. The
volatiles were removed in vacuo; the solid residue was extracted
with Et2O. The extract was concentrated and cooled to ꢁ27 °C, fur-
nishing yellow crystals of 7ꢂ(OEt2) (1.38 g, 31%). Repeated at-
tempts to obtain C, H, N analyses failed, possibly because of
decomposition in transit.
A solution of Na(L) (0.88 g, 1.80 mmol) in thf (20 cm3) was
added to a solution of [YbCl3(thf)3] (0.85 g, 1.71 mmol) in thf
(20 cm3) at ambient temperature; the colour of the mixture had
changed from light brown to red. The mixture was heated under
reflux at 60 °C for ca. 12 h. Volatiles were then removed in vacuo
and the residue was extracted with Et2O (60 cm3). The filtered ex-
tract, containing a trace of cyclohexane, was cooled to ꢁ25 °C and
maintained at that temperature for ca. 3 d, then yielding red crys-
tals of 3 (0.21 g, 13%) (C41H57Cl2N2O2Yb requires C, 61.0; H, 7.62; N,
2.90. Found: C, 59.1; H, 8.28; N, 3.26%), mp 78–79 °C (decomp.). IR
[KBr disc; mmax (strong bands only)]: 2961, 1635, 1549, 1303,
756 cmꢁ1. EI-MS [m/e (assignment and rel. intensity, %)]: 709
([Mꢁ2thf]+, 6.5), 673 ([YbCl(L)]+, 4), 637 ([Yb(L)]+, 1).
3.10. X-Ray crystallographic studies for 2–7
Diffraction data were collected on a Nonius Kappa CCD diffrac-
tometer using monochromated Mo K
a radiation, k 0.71073 Å at
173(2) K. Crystals were coated in oil and then directly mounted
on the diffractometer under a stream of cold nitrogen gas. The
structures were refined on all F2 using SHELXL 97 [13]. Absorption
corrections (not for 6) were applied using MULTISCAN. The program
package WINGX and drawing by ORTEP-3 for Windows, were used.
For 3, there were two independent molecules of cyclohexane
3.6. Preparation of [NdI2(L)(thf)2] (4)
A solution of K(L) (0.49 g, 0.96 mmol) in thf (20 cm3) was added
to a stirred suspension of [NdI3(thf)2] (0.81 g, 1.04 mmol) in thf

4684
Y. Cheng et al. / Inorganica Chimica Acta 362 (2009) 4678–4684
Table 4
Crystal data and structure refinement for 2–7.
Compound
2
3
4
5
6
7
Formula
M
C41H57Cl2N2O2Tb C41H57Cl2N2O2YbꢃC6H12ꢃ0.5(C4H10O) C41H57I2N2NdO2 C42H58ClN4Si4Tb C42H58ClN4Si4Yb C41H55Cl3LiN2O3Si2Ybꢃ(C4H10O)
839.71
975.04
1007.93
925.65
939.77
1024.50
Crystal system
Space group
monoclinic
C2/c (No. 15)
triclinic
orthorhombic
Pnma (No. 62)
triclinic
triclinic
monoclinic
P21/c (No. 14)
P1 (No. 2)
11.3034(3)
13.6439(4)
16.2675(5)
82.626(2)
89.300(1)
69.405(1)
2327.59(12)
2
P1 (No. 2)
11.8796(3)
12.4596(3)
15.7938(3)
84.715(1)
86.132(1)
89.969(1)
2322.44(9)
2
P1 (No. 2)
11.8361(2)
12.4762(3)
15.7197(5)
84.423(1)
86.175(2)
84.832(2)
2305.17(10)
2
a (Å)
b (Å)
c (Å)
34.5476(3)
11.3686(1)
23.4472(2)
90
116.62
90
17.6472(3)
18.2785(3)
13.2142(2)
90
90
90
15.4756(4)
18.3363(5)
18.7743(5)
90
108.132(1)
90
a
(°)
b (°)
c
(°)
V (Å3)
8233.10(12)
8
4262.43(12)
4
5062.9(2)
4
Z
Absorption coefficient 1.88
(mmꢁ1
Unique reflections, Rint 7619, 0.040
2.16
2.70
1.72
2.22
2.09
)
6717, 0.093
5854
3877, 0.040
3646
8059, 0.045
7348
8014, 0.048
7097
8912, 0.058
6766
Reflections with
I > 2 (I)
Final R indices
[I > 2 (I)], R1, wR2
6833
r
0.023, 0.052
0.065, 0.141
0.079, 0.146
0.019, 0.046
0.021, 0.047
0.027, 0.062
0.032, 0.064
0.029, 0.058
0.038, 0.061
0.040, 0.084
0.063, 0.092
r
R indices (all data) R1, 0.028, 0.054
wR2
[3] (a) L.W.M. Lee, W.E. Piers, M.R.J. Elsegood, W. Clegg, M. Parvez,
Organometallics 18 (1999) 2947;
solvate, both on inversion centres, and also one molecule of diethyl
ether disordered across an inversion centre for which 1,2 and 1,3
distance restraints were applied; for the ether solvent atoms, a
common Uiso was used. The molecule 4 lies on a crystallographic
mirror plane. Further details are in Table 4.
(b) P.G. Hayes, W.E. Piers, L.W.M. Lee, L.K. Knight, M. Parvez, M.R.J. Elsegood,
W. Clegg, Organometallics 20 (2001) 2533.
[4] (a) Y.-M. Yao, Y. Zhang, Q. Shen, K.-B. Yu, Organometallics 21 (2002) 819;
(b) Q. Shen, Y.-M. Yao, J. Organomet. Chem. 647 (2002) 180.
[5] (a) Y.-M. Yao, Y.-J. Luo, R. Jiao, Q. Shen, K.-B. Yu, L.-H. Wong, Polyhedron 22
(2003) 441;
(b) Y.-M. Yao, M.-Q. Xue, Y.-J. Luo, Z.-Q. Zhang, R. Jiao, Y. Zhang, Q. Shen, W.-T.
Wong, K.-B. Yu, J. Sun, J. Organomet. Chem. 678 (2003) 108;
(c) Y.-J. Luo, Y.-M. Yao, Y. Zhang, Q. Shen, K.-B. Yu, Chin. J. Chem. 22 (2004) 187;
(d) Y. Zhang, Y.-M. Yao, Y.-J. Luo, Q. Shen, Y. Cui, K.-B. Yu, Polyhedron 22 (2003)
1241.
Acknowledgements
For postdoctoral fellowships we thank the Royal Society (a Sino-
British Fellowship for Y.C.) and EPSRC (A.V.K.), the late Dr. A.G.
Avent for his contribution (Section 3.4) and Dr. A.V. Protchenko
for useful discussions.
[6] (a) Z.-Q. Zhang, Y.-M. Yao, Y. Zhang, Q. Shen, W.-T. Wong, Inorg. Chim. Acta 357
(2004) 3173;
(b) Z.-Q. Zhang, Q. Shen, Y. Zhang, Y.-M. Yao, J. Liu, Inorg. Chem. Commun. 7
(2004) 305.
[7] X.-H. Wei, Y.-X. Cheng, P.B. Hitchcock, M.F. Lappert, Dalton Trans. (2008) 5235.
[8] C. Cui, A. Shafir, J.A.R. Schmidt, A.G. Oliver, J. Arnold, Dalton Trans. (2005) 1387.
[9] (a) D.J.E. Spencer, N.W. Aboelella, A.M. Reynolds, P.L. Holland, W.B. Tolman, J.
Am. Chem. Soc. 124 (2002) 2108;
Appendix A. Supplementary data
CCDC 714961–714966 for complexes 2–7 contains the supple-
mentary crystallographic data for this paper. These data can be ob-
tained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.ica.2009.06.025.
(b) X.-W. Li, J.-Q. Ding, W.-Q. Jin, Y.-X. Cheng, Inorg. Chim. Acta 362 (2009) 233;
(c) Y.-X. Cheng, P.B. Hitchcock, M.F. Lappert, M.-S. Zhou, Chem. Commun.
(2005) 752;
(d) Y.-X. Cheng, D.J. Doyle, P.B. Hitchcock, M.F. Lappert, Dalton Trans. (2006)
4449;
(e) P.B. Hitchcock, M.F. Lappert, G. Li, A.V. Protchenko, Chem. Commun. (2009)
428.
[10] M.F. Lappert, A. Singh, J.L. Atwood, W.E. Hunter, J. Chem. Soc., Chem. Commun.
(1981) 1191.
[11] A.G. Avent, P.B. Hitchcock, D.-S. Liu, R. Sablong, Chem. Commun. (2002) 1920.
[12] P.B. Hitchcock, M.F. Lappert, R. Sablong, Dalton Trans. (2006) 4146.
[13] G. M. Sheldrick, SHELXL-97, Program for Crystal Structure Refinement,
University of Göttingen, Germany, 1997.
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