Solvent-free lanthanoid complexes derived from chelation-supported organoamide ligands

Article abstract of DOI:10.1002/1099-0682(200206)2002:6<1425::aid-ejic1425>3.0.co;2-t

Treatment of LnCl₃ with three molar equivalents of LiL [(L = N-(2-methoxyphenyl)-N-(trimethylsilyl)amide (L¹) or N-(2-phenoxyphenyl)-N-(trimethylsilyl)amide (L²)], generated in situ from LH and nBuLi, or with the isolated lithium complex [Li(L¹)(OEt₂)]₂ (for Ln = Yb) in THF afforded the solvent-free homoleptic complexes [Ln(L)₃] [Ln = Yb (1a), Er (1b), Sm (1c), Pr (1d), Nd (1e), L = L¹; Ln = Yb (2a), Y (2b), Sm (2c), Nd (2d), La (2e), L = L²). With a 2:1 LiL (generated in situ) to LnCl₃ molar ratio, the solvent-free heteroleptic complexes [Ln(L)₂(μ-Cl)]₂ were obtained for L = N,N-dimethyl-N'-trimethylsilylethane-1,2-diaminate (en′) [Ln = Yb (3a), Er (3b), Sm (3c), Nd (3d), La (3e)], but not for L¹ or L², which gave [Ln(L)₃] [Ln = Yb (1a), Nd (1e), L = L¹; Ln = Yb (2a), Nd (2d), La (2e), L = L²]. However, treatment of LnCl₃ with two molar equivalents of the isolated crystalline lithium salt [Li(L¹)(OEt₂)]₂ in THF gave, for the heavier lanthanoids, the solvent-free heteroleptic complexes [Ln(L¹)₂(μ-Cl)]₂ [Ln = Yb (4a), Er (4b), Tb (4c)], although the homoleptic complex [Nd(L¹)₃] (1e) was obtained for Nd. In contrast, similar reactions of isolated [Li(L²)(DME)] with LnCl₃ yielded the heteroleptic species [Ln(L²)₂(μ-Cl)]₂ only for Ln = Nd [5a·(PhMe)₂]. At either end of the Ln series, the homoleptic [Ln(L²)₃] complexes [Ln = Yb(2a), La (2e)] were obtained. Single crystal X-ray analyses of 1e or 2a-2e (as their PhMe or C₅H₉Me solvates) showed these complexes to be monomeric and six-coordinate (mer isomer), whereas the heteroleptic complexes 4a-4c, 5a were found to be dimeric with bridging chloride atoms. Two chelating [L¹]- or [L²]- units [trans O(Me/Ph) and cis amido groups] are bound to each lanthanoid centre completing a six-coordinate very distorted octahedral environment. The X-ray structure of [Li(L¹)(OEt₂)]₂ revealed a dimeric structure with each lithium four-coordinate and surrounded by one diethyl ether, two bridging amide nitrogens and a methoxy oxygen in a distorted tetrahedral array. Wiley-VCH Verlag GmbH, 69451 Weinheim Germany, 2002.

Full text of DOI:10.1002/1099-0682(200206)2002:6<1425::aid-ejic1425>3.0.co;2-t

FULL PAPER
Solvent-Free Lanthanoid Complexes Derived From Chelation-Supported
Organoamide Ligands[‡]
Glen B. Deacon,*[a] Craig M. Forsyth,[a] and Natalie M. Scott[a]
Keywords: N,O ligands / Lanthanides / Halides / Metathesis / Structure elucidation
Treatment of LnCl3 with three molar equivalents of LiL [(L =
N-(2-methoxyphenyl)-N-(trimethylsilyl)amide (L1) or N-(2-
phenoxyphenyl)-N-(trimethylsilyl)amide (L2)], generated in
situ from LH and nBuLi, or with the isolated lithium complex
[Li(L1)(OEt2)]2 (for Ln = Yb) in THF afforded the solvent-free
homoleptic complexes [Ln(L)3] [Ln = Yb (1a), Er (1b), Sm (1c),
was obtained for Nd. In contrast, similar reactions of isolated
[Li(L2)(DME)] with LnCl3 yielded the heteroleptic species
[Ln(L2)2(µ-Cl)]2 only for Ln = Nd [5a·(PhMe)2]. At either end
of the Ln series, the homoleptic [Ln(L2)3] complexes [Ln =
Yb(2a), La (2e)] were obtained. Single crystal X-ray analyses
of 1e or 2a−2e (as their PhMe or C5H9Me solvates) showed
Pr (1d), Nd (1e), L = L1; Ln = Yb (2a), Y (2b), Sm (2c), Nd (2d), these complexes to be monomeric and six-coordinate (mer
La (2e), L = L2). With a 2:1 LiL (generated in situ) to LnCl3
molar ratio, the solvent-free heteroleptic complexes
[Ln(L)2(µ-Cl)]2 were obtained for L = N,N-dimethyl-NЈ-tri-
methylsilylethane-1,2-diaminate (enЈ) [Ln = Yb (3a), Er (3b),
Sm (3c), Nd (3d), La (3e)], but not for L1 or L2, which gave
[Ln(L)3] [Ln = Yb (1a), Nd (1e), L = L1; Ln = Yb (2a), Nd (2d),
La (2e), L = L2]. However, treatment of LnCl3 with two molar
equivalents of the isolated crystalline lithium salt [Li(L1)(-
isomer), whereas the heteroleptic complexes 4a−4c, 5a were
found to be dimeric with bridging chloride atoms. Two che-
lating [L1]− or [L2]− units [trans O(Me/Ph) and cis amido
groups] are bound to each lanthanoid centre completing a
six-coordinate very distorted octahedral environment. The X-
ray structure of [Li(L1)(OEt2)]2 revealed a dimeric structure
with each lithium four-coordinate and surrounded by one di-
ethyl ether, two bridging amide nitrogens and a methoxy
OEt2)]2 in THF gave, for the heavier lanthanoids, the solvent- oxygen in a distorted tetrahedral array.
free heteroleptic complexes [Ln(L1)2(µ-Cl)]2 [Ln = Yb (4a), Er
(4b), Tb (4c)], although the homoleptic complex [Nd(L1)3] (1e)
( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany,
2002)
Introduction
(trimethylsilyl)amide,[15Ϫ18] benzamidinates,[19Ϫ21] amino-
tropiminates[22,23] and diazabutadienes.[24] These bulky li-
gands can block coordination sites around the metal centre
leading to monomeric, hydrocarbon soluble, electron-poor
species that display unique chemical properties. However, in
comparison to the stability offered by the cyclopentadienyl
ligand in [Ln(Cp)2(X)] (X ϭ anion), the labile nature of
organoamide ligands in such systems has often caused li-
gand redistribution, resulting in the isolation of homoleptic
derivatives.[7,15,22,25,26] The incorporation of a supporting
donor atom to give a bidentate amide ligand may improve
the stability of the heteroleptic complexes. Encouragement
for this idea came from the observation that N,N-dimethyl-
NЈ-trimethylsilylethane-1,2-diaminate (enЈ) gave not only
the homoleptic complexes [Ln(enЈ)3] (Ln ϭ Lu, Er, Eu, Sm,
Nd, La) but also a single example of a heteroleptic derivat-
ive [Er(enЈ)2Cl].[27] We now report a study of the use of the
two new mixed N,O-donor bidentate amide ligands N-(2-
methoxyphenyl)-N-(trimethylsilyl)amide (L1)[28] and N-(2-
phenoxyphenyl)-N-(trimethylsilyl)amide (L2)[28,29] for pre-
paring [Ln(L)3] and [Ln(L)2Cl] complexes, and extend the
enЈ heteroleptic series to lanthanoids other than Er. Previ-
ous studies on lanthanoid complexes containing the L1 and
L2 ligands have shown them to be capable of supporting
The 6eϪ donor cyclopentadienyl ligand (Cp) has been
extensively used as a coligand with early transition metals
for various types of catalytic transformations. Important
applications include highly active group 4 and 5 metal and
lanthanoid organometallic compounds in homogeneous
ZieglerϪNatta alkene polymerisation.[2Ϫ7] In the last dec-
ade an increasing number of investigators have turned their
attention away from cyclopentadienyl ligands to find altern-
ative systems to stabilise the metal-carbon bond for cata-
lytic work.[7Ϫ9] Alternative systems using alkoxide and
amide ligands in place of Cp have shown similar reaction
chemistry with the stabilisation of early electron-deficient
transition metals in medium to high oxidation
states.[6,7,9Ϫ14] Of these two alternatives, greater opportunit-
ies for substituent variation exist for the amide ligand.
There are numerous N-containing ligands that can stabilise
heteroleptic lanthanoid complexes, such as bis-
[‡]
Organoamido- and Aryloxo-Lanthanoids, 28. Part 27: see
Ref.[1]
[a]
School of Chemistry, Monash University,
3800 Victoria, Australia
E-mail: glen.deacon@sci.monash.edu.au
Eur. J. Inorg. Chem. 2002, 1425Ϫ1438  WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 1434Ϫ1948/02/0606Ϫ1425 $ 20.00ϩ.50/0
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G. B. Deacon, C. M. Forsyth, N. M. Scott
FULL PAPER
organo-oxo heteroleptic complexes viz. [Yb(L1)2(µ-OMe)]2 the large number of ligand bands. Asymmetric CϪOϪC
and [Yb(L2)2(OPh)(THF)] (THF ϭ tetrahydrofuran).[28]
stretching for [Ln(L1)3] [Ln ϭ Yb (1a), Er (1b), Sm (1c), Pr
(1d), Nd (1e)] gives two sets of two bands while for L1H
only one set is observed.[28] For [Ln(L2)3] [Ln ϭ Yb
Results and Discussion
{2a·(PhMe), 2a·(C5H9Me)},
Y
{2b·(C5H9Me)}, Sm
{2c·(PhMe)}, Nd {2d·(PhMe)2}, La {2e·(PhMe)}] this re-
gion displays three sets of two absorptions. This feature is
different from the behaviour of L2H, which displays only
two sets of two absorptions in this region.[28] Generally, the
1H NMR spectroscopic data for 1e, 2b·(C5H9Me),
2c·(PhMe), 2d·(PhMe)2, 2e·(PhMe) and 2e indicate that one
L environment is present in solution, in contrast to the two
L environments observed in the solid state (see below). Pre-
sumably the ligands are rapidly exchanging under these
conditions. Characteristic toluene resonances were observed
for the 2cϪ2e·(PhMe)n complexes and confirmed the num-
ber of toluene molecules of crystallisation per [LnL3] indic-
ated by microanalysis. For 2b·(C5H9Me) the 1H NMR spec-
trum is consistent with the presence of methylcyclopent-
ane,[30] although the integration indicated only half a
methylcyclopentane molecule per [Y(L2)3]. However, the X-
ray structure determination and elemental analyses indic-
A range of [Ln(L)3] complexes [L ϭ L1, Ln ϭ Yb (1a),
Er (1b), Sm (1c), Pr (1d), Nd (1e); L ϭ L2, Ln ϭ Yb (2a),
Y (2b), Sm (2c), Nd (2d), La (2e)] were prepared by treat-
ment of LnCl3 with three molar equivalents of LiL as the
isolated [Li(L1)(OEt2)]2 [Scheme 1 (i)] or generated in situ
from the reaction of LH with nBuLi in THF [Scheme 1 (ii)].
The crystalline complexes [Ln(L1)3] [Ln ϭ Yb (1a), Er (1b),
Sm (1c), Pr (1d), Nd (1e)] were isolated from hexane in
good yield after removal of the precipitated LiCl. The
[Ln(L2)3] complexes [Ln ϭ 2a·(PhMe), 2a·(C5H9Me) (from
a 1:2 mol ratio synthesis Ϫ see below), 2b·(C5H9Me),
2c·(PhMe), 2d·(PhMe)2, 2e·(PhMe)] were obtained by crys-
tallisation of the bulk products from toluene. Whilst toluene
solvates are not unusual, the isolation of methylcyclopent-
ane solvates (as identified from X-ray crystallography) was
unexpected. The latter are presumed to be derived from a
trace impurity in one of the solvents (PhMe or hexane)
used. Crystallisation of 2e·(PhMe) from diethyl ether gave
[La(L2)3] (2e), which was used for an X-ray determination,
whilst single crystals of solvent-free [Nd(L2)3] (2d) were ob-
tained by crystallisation of 2d·(PhMe)2 from hexane.
1
ated one C5H9Me per yttrium. Whilst the H NMR spec-
trum of 1e is similar to that of 2d·(PhMe)2 for structurally
common protons, the paramagnetic behaviour of Nd3ϩ
causes most backbone aromatic resonances on L1 or L2 to
shift considerably from those of diamagnetic 2e (see Exp.
Sect.). In the mass spectra of 1c and 1e, the highest metal-
containing fragment was attributable to the parent ion
[Ln(L1)3]ϩ; loss of the groups SiMe3 and OMe or OPh from
the molecular ion was observed for 1b, 2a·(PhMe) or
2a·(C5H9Me). The mass fragment [Ln(L1)2]ϩ was observed
in the spectra of all three complexes, as well as the metal-
free fragment [L1H]ϩ. The mass spectra of 2b·(C5H9Me)
and 2c·(PhMe) showed a weak molecular ion [Ln(L2)3]ϩ
and associated fragment ions (notably [Ln(L2)2]ϩ and
[Ln(L2)]ϩ) as well as an intense [L2H]ϩ ion. However for
2e·(PhMe) the highest mass ion observed was [La(L2)2]ϩ.
The UV/Vis/NIR spectrum of a solution of 1a in DME
exhibited absorptions characteristic of fǟf transitions of
the Yb3ϩ cation[31] near 1000 nm.
Scheme 1. Reagents and conditions: (i) THF, 0.33 equivalents of
YbCl3 followed by crystallisation from hexane (1a); (ii) nBuLi,
THF, 0 °C, 0.33 equivalents of LnCl3 followed by crystallisation
from hexane (1bϪ1e) or toluene (2a·(PhMe), 2a·(C5H9Me) (0.50
equivalents of YbCl3), 2b·(C5H9Me), 2c·(PhMe), 2d·(PhMe)2,
2e·(PhMe)]
Single crystal X-ray diffraction data were collected for 1e
(Figure 1), 2a·(PhMe) (Figure 2), 2d and 2e. Data were also
obtained for 2a·(C5H9Me) and 2b·(C5H9Me) and have been
Satisfactory elemental analyses (C, H N) were obtained deposited with the Cambridge Crystallographic Data
for all of the homoleptic complexes although crystallo- Centre (CCDC-174206/7). Selected bond lengths and angles
graphically characterised unsolvated 2e was not examined for 1e, 2a·(PhMe), 2b·(C5H9Me), 2d and 2e are given in
as the corresponding toluene solvate was obtained analytic- Table 1. Each of the molecules is monomeric with a six-
ally pure. In the case of 2a·(C5H9Me) the analysis fitted coordinate metal centre surrounded by three bidentate L
for solvent-free [Yb(L2)3] hence the methylcyclopentane was ligands (L ϭ L1 or L2) with the bulky amido groups ar-
evidently removed from the lattice on drying the sample ranged in a meridional configuration. The geometry is best
under vacuum. The corresponding undried yttrium com- described as a distorted octahedron (best-fit polyhedron[32]
)
plex analysed as the solvate. The infrared spectra of the with the oxygen atoms [O(1) and O(3)], nitrogen atoms
complexes were virtually identical within each series and [N(1) and N(2)], and the other donor pair [O(2) and N(3)]
indicated the presence of coordinated L1 or L2 in accord- occupying transoid sites. The mer arrangement of the L1 or
ance with the proposed compositions. For 2a·(PhMe), L2 ligands differs from that of the closely related complex
2c·(PhMe), 2d·(PhMe)2 and 2e·(PhMe) the presence of tolu- [Ln(enЈ)3] (enЈ ϭ N,N-dimethyl-NЈ-trimethylsilylethane-1,2-
ene could not be detected by infrared spectroscopy due to diaminate)[27] which has a fac orientation of the bidentate
1426
Eur. J. Inorg. Chem. 2002, 1425Ϫ1438

Solvent-Free Lanthanoid Complexes Derived From Organoamide Ligands
FULL PAPER
than 180°. This is presumably due to a combination of the
small bite angle of the chelated L1 or L2 ligands and the
proximity of the cis amide groups.
The geometry of [Nd(L2)3] is almost identical to that of
[Nd(L1)3] with the angles defining the coordinated atoms
differing by less than 10° (Table 1). Whilst the general ap-
pearance of the [Ln(L2)3] complexes is the same, significant
differences are apparent between the solvated and solvent-
free structures. The trans NϪLnϪN angles for unsolvated
2d and 2e are approximately 12° smaller than those for
2a·(PhMe) and 2b·(C5H9Me), and a similar, but less
marked, trend is also observed for the cis NϪLnϪN angles
(Table 1). Thus the solvates are closer to a regular octahed-
ral structure. These differences are clearly not due to the
˚
gradual change in ionic radii from La (1.03 A) to Yb (0.87
A).[33] For example, the smaller elements would be expected
˚
to be more sterically crowded causing a widening of the
cis NϪLnϪN angles through greater repulsion between the
bulky SiMe3 groups. In fact the opposite is observed. How-
ever, the cis NϪLnϪN angles are not unreasonably narrow
and still compare well with those of fac-[Ln(enЈ)3].[27]
Therefore the variation in angles is possibly associated with
differences in the crystal packing required to accommodate
solvent molecules.
Figure 1. ORTEP view of [Nd(L1)3] (1e) drawn with 50% ellipsoids;
hydrogen atoms have been omitted for clarity
A comparison of the metal-nitrogen distances with those
of other lanthanoid organoamides can be made by subtrac-
tion of the appropriate metal ionic radius (Table 2).[33] Se-
lected examples from the literature are listed in Table 2 and
the values derived for the current [Ln(L)3] complexes (L1:
2
˚
˚
1.37Ϫ1.40 A, L : 1.36Ϫ1.43 A) lie near the middle of the
˚
observed range (1.34Ϫ1.49 A) and are therefore not un-
usual. For 1e, 2a·(PhMe) and 2b·(C5H9Me) there is some
variation in the LnϪN distances with one shorter
[Ln(1)ϪN(3)] and two longer bonds, whereas the three
Ln(1)ϪN(amide) bond lengths of 2d and 2e are very similar
(Table 1). Whilst bond lengthening of the mutually trans
amides might be expected, this is not observed for any of
the complexes. Perhaps the inconsistently shorter LnϪN(3)
distance reflects extraneous factors, for example packing
forces. Subtraction values derived from the LnϪO distances
˚
(1.48Ϫ1.60 A) are significantly longer than those derived
from organolanthanoid or halolanthanoid ether complexes
Figure 2. ORTEP view of [Yb(L2)3].(PhMe) (2a·(PhMe)] drawn
with 50% ellipsoids; hydrogen atoms and toluene of crystallisation
have been omitted for clarity
[34]
˚
[LnR3(ether)n: 1.34 Ϯ 0.05 A);
LnX3(THF)n: 1.39Ϫ1.44
[35]
˚
A]
but the NdϪO distances are shorter than those
˚
[2.614(4)Ϫ2.740(4) A] in the related neodymium bidentate
enЈ amide ligands. The latter was unexpected since the very amide complex [Nd{Me2Si(OtBu)(NtBu)}3].[36] The ether
bulky NSiMe3 groups are all in a cis disposition. Thus the fragments of [Nd{Me2Si(OtBu)(NtBu)}3] and [Ln(L)3] are
NϪLnϪN angles lie in the range [104.8(5)Ϫ109.0(1)°] for bulkier than a simple ether ligand such as THF, and this
[Ln(enЈ)3] (Ln ϭ Lu, Er, Eu)[27] whereas 1e, 2a·(PhMe), 2d may account for the long LnϪO distances, although the
and 2e have two similar angles but one larger transoid angle bond lengthening may also be an indication of general
(Table 1). Even with the mer configuration, two of the steric crowding in these complexes. The contraction of the
NSiMe3 groups are pushed above and below the equatorial subtraction values for the LnϪOPh bonds from La to Yb
plane presumably to reduce steric repulsion from the other- in the [Ln(L2)3]/[Ln(L2)3]·Sn complexes (Table 2) is contrary
wise closely proximate bulky amides. The less sterically to the expected trend since the increase in steric crowding
dominating O(Me/Ph) groups occupy the trans sites with associated with the smaller size of the metal centre may
O(1)ϪLn(1)ϪO(3) angles verging on linear, although the result in metal-oxygen bond lengthening. Since there are
angles between the remaining transoid donors two distinct groups of data corresponding to the presence
N(1)ϪLnϪN(2) and N(3)ϪLnϪO(2) are significantly less or absence of a solvent of crystallisation, these variations in
Eur. J. Inorg. Chem. 2002, 1425Ϫ1438
1427

G. B. Deacon, C. M. Forsyth, N. M. Scott
FULL PAPER
Table 1. Metal atom environments for [Ln(L)3] complexes
[a]
Crystallographic data for 2a·(C5H9Me) in CCDC-174206.
Table 2. Subtraction values from LnϪN, O, Cl distances for a selection of organoamidolanthanoid complexes
[a]
[a] [c]
Values derived from R. D. Shannon.[33] [b] Numbers extrapolated from values of higher coordination number from
.
Cy ϭ cyclo-
hexyl. tBuDAB ϭ di-tert-butyl-1,4-diazabutadiene. [(iPr)TP]2Ϫ ϭ 1,3-bis[2-(isopropylamino)troponiminato]propane. Value of the
[d]
[e]
[f]
YbϪµ-Cl distance only.
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Eur. J. Inorg. Chem. 2002, 1425Ϫ1438

Solvent-Free Lanthanoid Complexes Derived From Organoamide Ligands
FULL PAPER
bond lengths and angles may be a result of a packing effect more rewarding synthetically than reagents generated in
resulting from the presence or absence of the solvent.
situ.[48,49] The synthetic value of pre-isolated alkali metal
With successful coordination of bidentate organoamide alkyls has been demonstrated in routes to ytterbium(II) al-
ligands [not only in the current examples, but also the previ- kyls.[50]
ously reported [Ln(enЈ)3] complexes (Ln ϭ Lu, Er, Eu, Sm,
Nd, La)],[27] the next challenge was to prepare heteroleptic
chloride species of the type [Ln(L)2Cl]. Such complexes are
pivotal intermediates for the generation of catalytically act-
ive materials.[4,5,7] A one-pot reaction was initially re-
ported[27] to be successful for the enЈ ligand, yielding one
example of the target molecules, [Er(enЈ)2Cl]. This has now
been shown to be general across the lanthanoid series with
the preparation of the heteroleptic diorganoamidolan-
Scheme 3. Reagents and Conditions; In situ ЈLiLЈ; (ii) L ϭ L1,
thanoid complexes [Ln(enЈ)2(µ-Cl)]2 [Ln ϭ Yb (3a), Er(3b),
Ln ϭ Yb (1a), Nd (1e); L ϭ L2, Ln ϭ Yb (2a) (crystallised from
Sm (3c), Nd (3d) and La (3e)] (Scheme 2). The lanthanoid
toluene/hexane), Nd (2d), La (2e). Isolated LiL; (ii) L ϭ L1, Ln ϭ
Yb, Er, Tb, target 4aϪ4c obtained; Ln ϭ Nd gives 1e; (iii) L ϭ L2,
Ln ϭ Nd, 5a·(PhMe)2 obtained; Ln ϭ Yb, La afforded 2a, 2e; iv)
L ϭ L2, Ln ϭ La, 2e obtained
products were very soluble in hydrocarbon solvents and
were crystallised with difficulty from concentrated solutions
at Ϫ20 °C. Furthermore, the removal of LiCl from the reac-
tion mixture was tedious with numerous low temperature
extractions required in order to obtain pure [Ln(enЈ)2(µ-
Cl)]2 derivatives, which were subsequently isolated in only
low to moderate yields.
The direct formation of [Ln(L)3] from a 2:1 (Li:Ln) reac-
tion in THF would leave 0.33 equivalents of LnCl3 un-
changed, and lanthanoid halides have low solubility in this
solvent. Since all the LnCl3 dissolved, it suggests that the
heteroleptic species is formed initially, possibly stabilised as
an ‘‘ate’’ complex such as A in Scheme 4. The formation
of ‘‘ate’’ complexes has previously been observed for
other bulky organoamidolanthanoids, for example
[Yb{Me2Si(OtBu)(NtBu)}2(µ-Cl)2Li(THF)2][36]
and
Scheme 2. Reagents and Conditions; (i) nBuLi, THF, 0 °C, then
0.5 equivalents of LnCl3 (Ln ϭ Yb, Er, Sm, Nd, La) followed by
crystallisation from hexane
[Nd{(CF3)3C6H2C(NSiMe3)2}(µ-Cl)2Li(THF)2].[42] There-
fore the rearrangement presumably occurs on addition of
hexane [or for L2, Ln ϭ Yb, toluene (even with isolated
LiL2); for Ln ϭ La, also diethyl ether; Scheme 4 (iii)] with
precipitation of LiCl and LnCl3 or even LiLnCl4. This is
contrary to the in situ [Ln(enЈ)2(µ-Cl)]2 preparations where
the heteroleptic derivatives were obtained from hexane.
Crystallisation of the ‘‘ate’’ complexes (A in Scheme 4) was
unsuccessful due to the very high solubility of the reaction
products. The reasons for the difference in outcome be-
tween the use of isolated and in situ formed LiL in two
cases (L ϭ L1, Ln ϭ Yb; L ϭ L2, Ln ϭ Nd) are not clear
but plausibly the in situ reagents are less pure.
The addition of LnCl3 to two molar equivalents of LiL
(L ϭ L1, Ln ϭ Yb, Nd; L ϭ L2, Ln ϭ Yb, Nd, La), which
was generated in situ in THF, resulted in complete dissolu-
tion of the starting materials. Extraction of the evaporated
reaction mixtures with hexane gave the homoleptic com-
plexes [Ln(L)3] [L ϭ L1, Ln ϭ Yb (1a), Nd (1e); L ϭ L2,
Ln ϭ Yb (2a·(C5H9Me) (from toluene/hexane), Nd (2d), La
(2e)] instead of the target heteroleptic complexes [Ln(L)2Cl]
(Scheme 3). Subsequently, reactions using isolated crystal-
line lithium salts of L1 and L2, such as dimeric [Li(L1)(-
OEt2)]2 (below) or monomeric [Li(L2)(DME)],[29] with a
variety of LnCl3 compounds in a 2:1 Li to LnCl3 mol ratio,
were found to give LnL2Cl complexes [L ϭ L1, Ln ϭ Yb
(4a), Er (4b), Tb (4c); L ϭ L2, Ln ϭ Nd {5a·(PhMe)2}]
(Scheme 3). Typically, hexane extraction was employed for
the isolation of [Ln(L1)2(µ-Cl)]2 (4aϪ4c) species whilst tolu-
ene was used for 5a·(PhMe)2 (Scheme 3). However, the
isolation of the homoleptic products 2a and 2e from reac-
tions of LnCl3 with two equivalents of [Li(L2)(DME)][29]
was also observed. Thus these results show that for L1 and
L2 there is only a narrow window of opportunity to prepare
Scheme 4. Postulated rearrangement pathway
Elemental analyses (C, H, N and/or Ln) for the
the heteroleptic chlorides. Access to complexes of the [Ln(L)2(µ-Cl)]2 complexes (except unanalysed 3b, 3c) were
smaller lanthanoid elements Tb, Er and Yb is available with consistent with the proposed formulations and the absence
L1, but the larger neodymium gives [Nd(L1)3] (1e) whilst L2 of coordinated THF. For each ligand type the infrared spec-
yields the heteroleptic derivative for the larger Nd but not tra of the [Ln(L)2(µ-Cl)]2 complexes were almost identical,
with the lighter (La) and heavier (Yb) extremes of the lan- showing peaks attributable to the appropriate ligand and no
thanoid series. These results support the view of Lappert et evidence of THF. The spectra of 3aϪ3e were very similar to
al. that fully characterised isolated lithium complexes are those of the corresponding homoleptic species. In contrast
Eur. J. Inorg. Chem. 2002, 1425Ϫ1438
1429

G. B. Deacon, C. M. Forsyth, N. M. Scott
FULL PAPER
intense infrared absorptions of 4aϪ4c attributable to
CϪOϪC stretching of the MeOAr substituent were ob-
served as two single bands at 1100Ϫ1000 cmϪ1, whereas for
mer-[Ln(L1)3] two bands were observed in each region. This
may reflect the solely trans ether groups in 4aϪ4c (below),
whereas [Ln(L1)3] complexes have both cis and trans
(Me)OϪLnϪO(Me) arrays. Bands at 1266 and 859 cmϪ1
were observed for 5a·(PhMe)2 but not for 2d·(PhMe)2, and
a band of the latter at 802 cmϪ1 was absent in the former,
thereby distinguishing the spectra of the two complexes.
Despite the paramagnetism of 5a·(PhMe)2, 1H NMR reson-
ances attributable to the L2 ligand could be assigned (see
Exp. Sect.), whilst those of toluene were in the usual dia-
magnetic region; integrations confirmed the proposed com-
position. Only a single L2 environment was detected — con-
sistent with the single type of L2 coordination in the solid-
state structure (below) — and the general spectral features
were similar to those of 2d·(PhMe)2. The visible/near
infrared spectrum of 5a·(PhMe)2 showed absorptions char-
acteristic of Nd3ϩ [31]
Mass spectra identified a bimolecular
.
species to be present for 3aϪ3e with the highest-mass frag-
ment, except for ytterbium, being the ion [Ln2(enЈ)3Cl2]ϩ.
(For the heavier ytterbium metal only the fragment
[Yb2(enЈ)2Cl2]ϩ was detected due to limitations in the ac-
cessible mass spectrum range.) These data imply that the
complexes have a dimeric structure of the type [Ln(enЈ)2(µ-
Figure 4. ORTEP view of [Nd(L2)2(µ-Cl)]2.(PhMe)2 (5a·(PhMe)2]
drawn with 50% ellipsoids; hydrogen atoms and toluene of crys-
tallisation have been omitted for clarity
Cl)]2 and contradict an earlier proposal of a monomeric ation is present in each asymmetric unit that comprises half
structure for the Er complex also based on MS data.[27] Ve- the dimer with a crystallographic inversion centre located
rification by X-ray diffraction studies has been unsuccessful in the middle of the Nd2Cl2 plane. Selected bond lengths
owing to the difficulty in obtaining suitable crystals of the and angles for 4aϪ4c and 5a·(PhMe)2 are given in Table 3.
highly soluble complexes and an unsatisfactory data solu- Two chelating [L]Ϫ (L ϭ L1 or L2) units are bound to each
tion for the one set of apparently suitable crystals (3d).
lanthanoid centre in a similar fashion completing a six-co-
ordination environment with a very distorted octahedral
geometry. Clearly, the steric demand of two L ligands and
one chloride is not sufficient to saturate all coordination
sites on the lanthanoid metal since dimerisation takes place.
Coordination of a molecule of THF generating monomeric
[Ln(L)2Cl(THF)] may occur in THF solution prior to
workup in nonpolar solvents. The chloride-bridged dimer is
presumably less crowded than [Ln(L)2Cl(THF)] with the
steric coordination number[51] for THF (1.2) larger than
that for chloride (1.0). In addition, longer LnϪµ-Cl than
LnϪClter distances also reduce crowding. These factors fa-
vour elimination of any coordinated THF on isolation.
The coordination geometry in [Ln(L)2(µ-Cl)]2 is similar
to that of the homoleptic derivatives [Ln(L)3] (L ϭ L1, L2).
Two bridging chloride atoms in the former replace one
equatorial L ligand of [Ln(L)3]. The axial positions are oc-
cupied by the O(Me/Ph) group on L1 or L2 with
O(1)ϪLn(1)ϪO(2) angles close to the expected 180°. The
remaining NSiMe3 units and chloride atoms are located in
mutually cisoid equatorial sites with the former lying above
Figure 3. ORTEP view of one molecule of [Yb(L1)2(µ-Cl)]2 (4a)
drawn with 50% ellipsoids; hydrogen atoms have been omitted for
clarity
The molecular structures of 4a (Figure 3), 4b, 4c and and below the equatorial plane. This arrangement presum-
5a·(PhMe)2 (Figure 4) are dimeric with two lanthanoid ably minimises steric repulsion between the cis NSiMe3
atoms bridged by two chlorine atoms. The complexes groups as is also observed for the homoleptic complexes
4aϪ4c are isostructural and have the monoclinic centro- [Ln(L)3] (see above). Generally the binding of the L1 and L2
symmetric space group P21/n with one dimer comprising ligands is similar to that in the corresponding homoleptic
the asymmetric unit. For 5a·(PhMe)2 a toluene of crystallis- complexes, although there is a marginal shortening of the
1430
Eur. J. Inorg. Chem. 2002, 1425Ϫ1438

Solvent-Free Lanthanoid Complexes Derived From Organoamide Ligands
FULL PAPER
Table 3. Metal environment in [Ln(L)2(µ-Cl)2] complexes
[a]
Symmetry transformations used to generate equivalent atoms: Ϫx ϩ 2, Ϫy ϩ 2, Ϫz ϩ 1.
LnϪN and LnϪO bond lengths consistent with the lower
steric demand of two chlorides. The near planar (4aϪ4c) or
planar [5a·(PhMe)2] Ln2Cl2 cores exhibit symmetrical
bridging of the chlorides in the L1 complexes, although
˚
there is a difference of 0.07 A between the two NdϪCl dis-
tances of 5a·(PhMe)2. The distance between the lanthanoid
centres is nonbonding (Table 3) and varies in line with the
Figure 5. Postulated dimeric representation of [Ln(enЈ)2(µ-Cl)]2
ionic radii of the respective metals (Table 2).
A notable feature of the coordination of the two L2 li-
gands to neodymium in 5a·(PhMe)2 is the noticeable tilt centre (Figure 5), although other arrangements may also
in one of the aromatic backbones [C(21)ϪC(26)]. Thus the be possible.
interplanar angle to the NdϪNϪO plane is 61.41(7)° which
Subtraction of the appropriate ionic radii from the
is almost double that of the other L2 ligand [31.49(6)°] and LnϪCl distances gives similar values to those of structur-
of the maximum observed for the homoleptic [Ln(L2)3] de- ally characterised lanthanoid µ-chloride fragments sup-
rivatives. Associated with this tilt, two of the carbon atoms ported by either amide or halide co-ligands (Table 2). For
[C(21) and C(22)] approach the metal centre with distances [Nd(L2)2(µ-Cl)]2 one value is slightly larger than in 4aϪ4c
˚
of 2.911(2) and 3.035(2) A, respectively, which are approx- complexes consistent with the greater steric crowding in the
imately 0.25 A shorter than the corresponding distances for L2 complex. Subtraction values for 4aϪ4c and 5a·(PhMe)2
˚
the other L2 ligand. The former NdϪC distances are only are similar to [Yb(Cl)2(µ-Cl)(THF)2]2 {which has an ana-
marginally longer than π-arene lanthanoid interactions in, logous donor array to [Yb(L1)2(µ-Cl)]2}[47] but are longer
for example, [Nd(η6-PhH)(AlCl4)3][52] [NdϪC distances of than those from the YbϪCl distances of [Yb(C5H5)2(µ-
2.93(2) to 2.94(2) A], and are similar to or shorter than Cl)]2,[44] consistent with the greater steric coordination
˚
intramolecular π-arene contacts [2.964(7)Ϫ3.158(9) A] in number[51] summation for [Yb(Cl)2(µ-Cl)(THF)2]2 (6.42)
˚
neodymium aryloxide complexes such as [Nd(Odpp)3] than [Yb(C5H5)2(µ-Cl)]2 (6.08). The subtraction values for
(OdppϪ ϭ 2,6-diphenylphenolate).[53] Thus, it appears that the LnϪCl bonds in [Ln(L1)2(µ-Cl)]2 are similar to those of
[46]
C(21) and C(22) form an intramolecular π-η2 interaction [Sm(C5Me5)2(µ-Cl)]3
(Table 2) suggesting a steric simil-
with Nd and this bonding accounts for the tilt of the ar- arity between L1 and C5Me5, even though the current struc-
ene backbone. tures are more like those of the unsubstituted cyclo-
For 3aϪ3e, a similar dimeric structural type would be pentadienyl
complex
[Yb(C5H5)2(µ-Cl)]2,
as
the
expected with cis-amide groups, trans-amine substituents Sm(C5Me5)2 groups are rotated by 90°.[46] This may reflect
and bridging chloride ions per six-coordinate lanthanoid both the more adaptable coordination environment of the
Eur. J. Inorg. Chem. 2002, 1425Ϫ1438
1431

G. B. Deacon, C. M. Forsyth, N. M. Scott
FULL PAPER
‘‘edge-on’’ bound bidentate organoamide ligands compared arises from the restriction of the NϪLiϪO(Me) bite angle
with the ‘‘face-on’’ cyclopentadienyl ligand.
[83.6(2)°] as well as the ligation of the bridging amide nitro-
gens, N(1) and N(1A), to Li(1,1A). The N(1)Ϫ
Li(1)ϪN(1A)ϪLi(1A) ring is essentially planar having the
bidentate L1 ligands parallel to each other, with the arene
backbone approximately perpendicular to the central
(NLi)2 plane [74.9(1)°]. In comparison with L1H,[28] binding
of L1 to lithium has little effect on the methoxy position in
relation to the arene backbone plane [torsion angle:
C(13)ϪC(12)ϪO(1)ϪC(10) 11.7(3)°]. The structure of [Li-
(L1)(OEt2)]2 can be compared with those of other sterically-
crowded [{Li(µ-L)(OEt2)}2] complexes [L ϭ 8-quinolinyl-
(trimethylsilyl)amide (qsta)[54] or N,NЈ-di-p-tolylformamid-
inate (dtf)[55]]. However, the steric requirements for L1 must
be less than that of enЈ which coordinates to lithium in an
Synthesis and Crystal Structure of [Li(L1)(OEt2)]2
The lithiation of L1H with one equivalent of nBuLi in
Et2O afforded a white precipitate of [Li(L1)(OEt2)]2. Satis-
factory elemental analyses, despite numerous attempts,
could not be obtained. The values are closer to those for
LiL1 and could suggest that loss of coordinated ether oc-
curs during the lengthy journey to the analysis laboratories.
1
However the H NMR spectrum of [Li(L1)(OEt2)]2 estab-
lished the L1 to Et2O ratio, and showed a single methoxy
ether peak and characteristic arene backbone signals (H-
7
3ϪH-6). The room temperature Li NMR spectrum of [Li-
(L1)(OEt2)]2 shows a single lithium environment with a nar-
row (∆ν1/2 ϭ 14 Hz) signal. The IR spectrum contained ab-
sorptions typical of a coordinated Et2O molecule and of
the L1 ligand.
unsymmetrical
dinuclear
configuration
in
[Li-
(enЈ)2Li(OEt2)][27] with one four-coordinate and one three-
coordinate Li. The LiϪO(1) and LiϪO(2) ether distances
1
˚
˚
Crystals of [Li(L1)(OEt2)]2 suitable for X-ray crystallo-
graphy were obtained by recrystallisation of the crude mat-
erial from diethyl ether. The structure of the complex [Li-
(L1)(OEt2)]2 is dimeric (Figure 6). Selected geometric data
are compiled in Table 4. Each four-coordinate lithium atom
is surrounded by one diethyl ether, two bridging amide ni-
trogens [N(1) and N(1A)] and a methoxy oxygen atom in a
distorted tetrahedral array. This distortion presumably
[2.000(4) A, 1.991(4) A respectively] in [Li(L )(OEt2)]2 are
˚
similar to those in related etherates (e.g. 1.94(3) A in four-
˚
coordinate [{Li(qsta)(OEt2)}2] and 1.943(6) A in three-co-
ordinate [{Li[N(SiMe3)2(OEt2)}2][49]). The lithium bridging
is not symmetrical as shown by the significant difference in
˚
the Li(1)ϪN(1) and Li(1)ϪN(1A) bond lengths of 0.129 A.
This unsymmetrical behaviour has been observed in the re-
lated
[{Li(qsta)(OEt2)}2]
complex
with
bridging
˚
LiϪN(amide) distances of 2.07(2) and 2.21(2) A and is pre-
sumably due to the steric crowding by the chelating L1 li-
gand. The sharp 7Li and 1H NMR spectra of [Li(L1)-
(OEt2)]2 are consistent with observation of only one LiL1
environment in the solid state.
Conclusions
The preparation of solvent-free lanthanoid organoamide
complexes of the type [LnL3] or [Ln(L)2(µ-Cl)]2 (L ϭ L1,
L2, enЈ) can be achieved through incorporation of a pen-
dant donor on the amide ligand. For the ether-substituted
L1 and L2 derivatives, isolation of [Ln(L)2(µ-Cl)]2 is critic-
ally dependent upon the correct choice of, and size of, the
ligand and the lanthanoid metal, since otherwise rearrange-
ment to the homoleptic complex is observed. The
[Ln(L)2(µ-Cl)]2 (L ϭ L1, L2, enЈ) complexes represent a new
class of solvent-free heteroleptic lanthanoid(III) amides
which should be capable of further functionalisation by re-
placement of the halide.
Figure 6. ORTEP view of [Li(L1)(OEt2)]2 drawn with 50% ellips-
oids; hydrogen atoms have been omitted for clarity
˚
Table 4. Selected bond lengths (A) and angles (°) with estimated
standard deviations in parentheses for [Li(L1)(OEt2)]2
Experimental Section
All reactions were carried out under dry nitrogen using dry box
and standard Schlenk techniques. Solvents were dried by distilla-
tion from sodium wire/benzophenone. IR data (4000Ϫ650 cmϪ1
)
were recorded for Nujol mulls sandwiched between NaCl plates
with a PerkinϪElmer 1600 Fourier transform infrared spectro-
meter. NMR spectra were obtained either on a Bruker AC200 MHz
(1H) or a Bruker AC 400 MHz spectrometer (7Li and 1H) as indic-
ated. Deuterated solvents were degassed and distilled from Na/K
[a]
Symmetry transformations used to generate equivalent atoms:
Ϫx, Ϫy ϩ 1, Ϫz.
1432
Eur. J. Inorg. Chem. 2002, 1425Ϫ1438

Solvent-Free Lanthanoid Complexes Derived From Organoamide Ligands
FULL PAPER
1
alloy prior to use. H NMR spectra were referenced to the solvent 734 (Ͻ1) [Sm(L1)3]ϩ, 630 (Ͻ1) [Sm(L1)2NC6H4]ϩ, 540 (Ͻ1)
7
(C6D6 and C7D8) signals; the chemical shift for the Li spectrum
is given relative to external 0.1  LiCl in D2O at room temperature.
Mass spectra were recorded with a VG Trio-1 GC mass spectro-
[Sm(L1)2]ϩ, 464 (Ͻ1) [Sm(L1)(C6H4NSi)]ϩ, 195 (35) [(L1H)]ϩ, 180
(20) [(L1H) Ϫ Me]ϩ, 165 (100) [(L1H) Ϫ 2Me]ϩ, 150 (35) [(L1H) Ϫ
3Me]ϩ, 135 (20) [C6H5ONSi]ϩ, 73 (20) [SiMe3]ϩ, 58 (10) [SiMe2]ϩ.
meter. Each listed m/z value for metal-containing ions is the most C30H48N3O3Si3Sm (734.21): calcd. C 49.13, H 6.60, N 5.73; found
intense peak of a cluster pattern in good agreement with the calcu-
lated pattern. Elemental analyses (C, H N) were determined by
the Campbell Microanalytical Service, University of Otago, New
Zealand. Lanthanoid analyses were by complexometric titration
with [Na2EDTA].[53,56] [LnCl3(THF)n],[35] LnCl3,[57] L1H,[28]
L2H,[28,29] enЈH,[27] [Li(L2)(DME)][29] were each prepared accord-
ing to a reported procedure. nBuLi (1.6 ) (Aldrich) was used un-
standardised but transferred to and stored in a Schlenk flask under
nitrogen immediately on opening a new batch.
C 48.55, H 6.67, N 5.67.
[Pr(L1)3] (1d): A similar preparation method to that used for com-
pound 1b gave green crystals of 1d (0.49 g, 57%). IR (Nujol): ν˜ ϭ
1590 vs, 1561 vs, 1484 s, 1449 s, 1320 vs, 1285 vs, 1246 br. s, 1210
s, 1164 vs, 1117 vs, 1058 w, 1050 s, 1011 s, 1002 vs, 915 br. s, 841
br. s, 768 s, 743 s, 674 s, 625 s, 597 s cmϪ1. C30H48N3O3PrSi3
(723.21): calcd. C 49.78, H 6.68, N 5.80; found C 49.56, H 6.71,
N 5.97.
[Nd(L1)3] (1e). Method 1: A similar preparation method to that
used for compound 1b gave blue crystals of 1e (0.57 g, 65%). IR
(Nujol): ν˜ ϭ 1590 vs, 1560 m, 1484 s, 1319 vs, 1285 vs, 1246 m,
1209 s, 1163 s, 1117 vs, 1058 w, 1050 s, 1011 s, 1002 vs, 914 br. s,
841 br vs, 767 s, 743 vs, 675 m, 625 s, 597 s cmϪ1. MS: m/z (%) ϭ
726 (10) [144Nd(L1)3]ϩ, 622 (5) [144Nd(L1)2C6H4N]ϩ, 532 (30)
[Yb(L1)3] (1a). Method 1: [Li(L1)(OEt2)]2 (0.62 g, 1.12 mmol) was
added to a stirred suspension of [YbCl3(THF)3] (0.37 g, 0.75 mmol)
in THF (40 mL) and the resulting mixture was stirred for 12 h.
The solvent was removed under vacuum and hexane added (30 mL)
giving a white precipitate. The red solution was filtered and the
filtrate concentrated to 15 mL. A red crystalline product was ob-
tained on standing for 2 h (0.41 g, 72%). IR (Nujol): ν˜ ϭ 1593 vs,
1561 vs, 1485 s, 1465 m, 1321 vs, 1294 vs, 1283 s, 1245 vs, 1209 s,
1159 w, 1059 w, 1051 s, 1012 s, 1000 vs, 913 br. s, 843 br vs, 822 s,
787 m, 770 s, 743 s, 681 s, 629 s, 598 s cmϪ1. Vis/near IR (DME):
λmax (ε) ϭ 431 (185), 874 (9), 911 (14), 945 (6), 978 (35) nm (dm3
molϪ1). C30H48N3O3Si3Yb (756.23): calcd. C 47.66, H 6.40, N 5.56;
found C 47.88, H 6.44, N 5.63.
[
144Nd(L1)2]ϩ, 305 (5) [142Nd(L1) Ϫ OMe]ϩ, 195 (40) [(L1H)]ϩ, 180
(15) [(L1H) Ϫ Me]ϩ, 165 (70) [(L1H) Ϫ 2Me]ϩ, 150 (30) [(L1H) Ϫ
3Me], 135 (25) [C6H5ONSi]ϩ, 73 (100) [SiMe3]ϩ, 58 (35) [SiMe2]ϩ.
1H NMR (300 MHz, C6D6, 298 K): δ ϭ Ϫ16.98 (br. s, 9 H, OMe),
Ϫ4.20 (br. s, 27 H, SiMe3), 1.14 (s, 3 H, H-4 or H-5), 7.88 (s, 3 H,
H-4 or H-5), 14.18 (s, 3 H, H-3 or H-6), 23.60 (s, 3 H, H-3 or H-
6). C30H48N3NdO3Si3 (724.21): calcd. C 49.55, H 6.65, N 5.78;
found C 49.85, H 6.81, N 5.73.
Method 2 [2:1 Li to Ln mol ratio (in situ)]: nBuLi was slowly added
(2.31 mL, 3.70 mmol) to
Method 2 [using 1:2 Ln to L1 mol ratio (in situ)]: nBuLi (2.31 mL,
3.70 mmol) was slowly added to a stirred solution of compound
L1H (0.71 g, 3.60 mmol) in THF (40 mL) at 0 °C and the resulting
solution was warmed to room temperature over ca. 1 h.
[NdCl3(THF)2] (0.71 g, 1.80 mmol) was added to the resulting solu-
tion, and the reaction mixture was stirred rapidly for 12 h. The
solvent was removed in vacuo, and hexane (30 mL) was added af-
fording a white precipitate. The blue solution was filtered and the
filtrate volume was reduced to ca. 2 mL under vacuum. Blue crys-
tals deposited on standing overnight. The infrared spectrum was
similar to that of 1e (Method 1). Unit Cell data [C30H48N3NdO3Si3,
a
stirred solution of L1H (0.71 g,
3.60 mmol) in THF (40 mL) at 0 °C and the resulting solution was
warmed to room temperature over ca. 1 h. [YbCl3(THF)2] (0.76 g,
1.80 mmol) was added to the resulting solution and the reaction
mixture rapidly stirred for 12 h. The solvent was removed in vacuo,
and hexane (30 mL) was added affording a white precipitate. The
red solution was filtered and the filtrate volume reduced to ca.
2 mL under vacuum . Red crystals of [Yb(L1)3] (1a) were deposited
on standing overnight. The infrared spectrum was identical to that
of 1a obtained from Method 1.
[Er(L1)3] (1b): nBuLi (2.30 mL, 3.70 mmol) was added to a stirred
solution of compound L1H (0.72 g, 3.70 mmol) in THF (40 mL) at
0 °C, and the resulting solution was warmed to room temperature
over ca. 1 h. [ErCl3(THF)3.5] (0.63 g, 1.20 mmol) was then added
and the reaction mixture stirred for 15 h. The solvent was then
removed under vacuum and hexane (30 mL) was added giving a
white precipitate. The light pink solution was filtered and the fil-
trate volume reduced to 10 mL under vacuum. The light pink crys-
tals deposited on standing for 12 h (0.43 g, 48%). IR (Nujol): ν˜ ϭ
1593 vs, 1561 vs, 1485 s, 1464 m, 1321 vs, 1284 vs, 1240 s, 1209 s,
1156 vs, 1117 vs, 1058 w, 1051 s, 1011 s, 1000 vs, 911 br. s, 841 br
vs, 784 s, 768 s, 735 s, 681 s, 627 s, 597 s cmϪ1. MS: m/z (%) ϭ 646
(Ͻ1) [Er(L1)2NC6H4]ϩ, 556 (Ͻ1) [Er(L1)2]ϩ, 480 (Ͻ1)
[Er(L1)(C6H4NSi)]ϩ, 195 (35) [(L1H)]ϩ, 180 (20) [(L1H) Ϫ Me]ϩ,
165 (100) [(L1H) Ϫ 2Me]ϩ, 150 (35) [(L1H) Ϫ 3Me]ϩ, 135 (20)
[C6H5ONSi]ϩ, 73 (20) [SiMe3]ϩ, 58 (10) [SiMe2]ϩ. C30H48Er-
N3O3Si3 (748.22): calcd. C 48.03, H 6.45, N 5.60; found C 48.16,
H 6.70, N 5.73.
M ϭ 724.2, monoclinic, a ϭ 10.121(1), b ϭ 18.876(1), c ϭ 18.814(1)
A; α ϭ 90°, β ϭ 104.37(1)°, γ ϭ 90°; V ϭ 3500.2 A , T ഠ 123 K]
were in agreement with those of [Nd(L1)3] from Method 1 (Table 5).
3
˚
˚
Method 3 [using 1:2 Ln to Li (isolated) ratio)]: [NdCl3(THF)2]
(0.30 g, 0.75 mmol) and [Li(L1)(OEt2)]2 (0.42 g, 0.75 mmol) were
stirred together in THF (40 mL). After 12 h, the pale yellow solu-
tion was evaporated to dryness under reduced pressure and hexane
added. The resulting white solid was filtered and the filtrate evapor-
ated to dryness under vacuum affording a blue crystalline material
(0.20 g, 55%). Infrared and 1H NMR spectra were identical to
those of 1e (Method 1).
[Yb(L2)3]·(PhMe) [2a·(PhMe)]: nBuLi (1.88 mL, 3.00 mmol) was
added to a stirred solution of L2H (0.77 g, 3.00 mmol) in THF
(40 mL) at 0 °C, and the resulting solution was warmed to room
temperature over ca. 1 h. [YbCl3(THF)2] (0.42 g, 1.0 mmol) was
then added and the reaction mixture was stirred for 12 h. The solv-
ent was then removed under vacuum and toluene (30 mL) was ad-
ded giving a white precipitate. The red solution was filtered at Ϫ78
°C and the filtrate volume reduced to 25 mL under vacuum. Red
crystals of good X-ray quality were deposited on standing over-
[Sm(L1)3] (1c): A similar preparation method to that used for com-
pound 1b gave yellow crystals of 1c (0.36 g, 41%). IR (Nujol): ν˜ ϭ
1585 vs, 1559 vs, 1481 s, 1307 vs, 1279 vs, 1237 s, 1211 s, 1173 vs, night (0.70 g, 68%). IR (Nujol): ν˜ ϭ 1593 vs, 1558 m, 1480 s, 1278
1117 vs, 1076 vs, 1058 w, 1050 vs, 1030 vs, 937 s, 919 s, 842 s, 825 vs, 1241 vs, 1186 vs, 1152 vs, 1097 s, 1072 w, 1051 s, 1020 m, 1005
s, 772 vs, 741 vs, 735 s, 662 vs, 616 s, 597 s cmϪ1. MS: m/z (%) ϭ w, 906 s, 858 sh w, 840 s, 824 s, 802 s, 778 m, 728 s, 692 vs, 626 w,
Eur. J. Inorg. Chem. 2002, 1425Ϫ1438
1433

G. B. Deacon, C. M. Forsyth, N. M. Scott
FULL PAPER
Table 5. Crystallographic and refinement parameters for [Ln(L)3] complexes
591 s, 568 w cmϪ1. MS: m/z (%) ϭ 942 (Ͻ1) [Yb(L2)3]ϩ, 849 (Ͻ1)
ent was removed in vacuo, and toluene (20 mL) added affording a
white precipitate. The red solution was filtered and the filtrate vol-
[Yb(L2)3(C6H4NSiMe3)]ϩ, 776 (16) [Yb(L2)2(C6H4N)]ϩ, 686 (35)
[Yb(L2)2]ϩ, 671 (15) [Yb(L2)2
Ϫ
Me]ϩ, 609 (18) ume reduced to ca. 2 mL under vacuum. Hexane (15 mL) was ad-
[Yb(L2)(OC6H4NSiMe3)]ϩ, 593 (3) [Yb(L2)(C6H4NSiMe3)]ϩ, 523 ded to the oily residue resulting in an immediate precipitation of
(4) [Yb(L2)OC6H5]ϩ, 430 (30) [Yb(L2)]ϩ, 415 (35) [Yb(L2) Ϫ Me]ϩ, LiCl and a red solution. Red crystals deposited on standing and
400 (7) [Yb(L2) Ϫ 2Me]ϩ, 353 (3) [Yb(OC6H4NSiMe3)]ϩ, 337 (5) were dried at room temperature under vacuum. The infrared spec-
[Yb(C6H4NSiMe3)]ϩ, 257 (20) [(L2H)]ϩ, 242 (16) [(L2H) Ϫ Me]ϩ,
226 (10) [(L2) Ϫ 2Me]ϩ, 165 (50) [OC6H4NHSiMe2]ϩ, 150 (15)
[C6H4ONHSiMe]ϩ, 73 (100) [SiMe3]ϩ. C52H62N3O3Si3Yb
(1034.36): calcd. C 60.38, H 6.04, N 4.06; found C 59.69, H 6.42,
N 4.35.
[Yb(L2)3]·(C5H9Me) [2a·(C5H9Me)]. Method 1 (using a 1:2 Ln:Li 1049 s, 1020 m, 1004 w, 911 br. s, 860 w, 824 s, 776 s, 735 vs, 692
ratio): THF (40 mL) was added to the solids [Li(L2)(DME)] vs, 675 w, 625 w, 592 s, 560 w cmϪ1. MS: m/z (%) ϭ857 (Ͻ1)
(0.53 g, 1.50 mmol) and [YbCl3(THF)2] (0.32 g, 0.75 mmol) and the [Y(L2)3]ϩ, 601 (20) [Y(L2)2]ϩ, 524 (5) [Y(L2)(OC6H4NSiMe3)]ϩ,
trum was similar to that of 2a·(C5H9Me) above.
[Y(L2)3]·(C5H9Me) [2b·(C5H9Me)]: A similar procedure to that
used for compound 2a·(PhMe) gave colourless crystals of the title
complex (0.61 g, 71%). IR (Nujol): ν˜ ϭ 1592 vs, 1582 s, 1557 m,
1489 s, 1278 vs, 1239 vs, 1210 s, 1170 s, 1152 vs, 1099 vs, 1071 m,
resulting mixture was stirring for 12 h. The solvent was then re-
moved under vacuum and toluene (25 mL) added giving a white
precipitate. The red solution was filtered at Ϫ78 °C and the filtrate
volume reduced to 20 mL under vacuum. Red crystals of
[Yb(L2)3]·(C5H9Me) (suitable for X-ray analysis) deposited on
standing overnight (0.15 g, 24% [based on L2]). IR (Nujol): ν˜ ϭ
438 (5) [Y(L2)(OC6H5)]ϩ, 330 (5) [Y(L2) Ϫ Me]ϩ, 257 (40)
[(L2H)]ϩ, 242 (20) [(L2H) Ϫ Me]ϩ, 164 (60) [OC6H4NSiMe2]ϩ, 149
(25) [C6H4ONSiMe]ϩ, 73 (100) [SiMe3]ϩ. 1H NMR (300 MHz,
C6D6, 298 K): δ ϭ 0.43 (s, 27 H, SiMe3), 0.89Ϫ1.45 (complex m,
3
4
6 H, C5H9Me), 5.97Ϫ6.15 (dd, J ϭ 7.1, J ϭ 1.2 Hz, 3 H, H-6),
4
6.20Ϫ6.30 (bd, 3J ϭ 6.9, J ϭ 1.5 Hz, 3 H, H-5), 6.40Ϫ6.97 (br.
1593 vs, 1560 m, 1480 sh w, 1307 w, 1280 s, 1242 s, 1152 s, 1185 s, m, 21 H, H-3,H-4,H-2Ј-6Ј). C51H66N3O3Si3Y (solvate) (941.35):
1098 s, 1072 m, 1052 s, 1020 m, 1004 w, 908 s, 858 sh w, 840 s, 824 calcd. C 65.01, H 7.06, N 4.46. C45H54N3O3Si3Y ([Y(L2)3])
s, 802 s, 780 m, 726 s, 691 s, 618 s cmϪ1. MS: m/z (%) ϭ 776 (Ͻ1) (857.25): calcd. C 62.99, H 6.34, N 4.90; found C 65.70, H 7.49,
[Yb(L2)2(C6H4N)]ϩ, 686 (4) [Yb(L2)2]ϩ, 507 (4) [Yb(L2)(OC6H5)]ϩ,
430 (10) [Yb(L2)]ϩ, 415 (10) [Yb(L2) Me]ϩ, 353 (10)
N 4.46.
Ϫ
[Sm(L2)3]·(PhMe) (2c): A similar preparation method to that used
for compound 2a·(PhMe) (Method 1) gave yellow crystals of the
title complex (0.56 g, 56%). IR (Nujol): ν˜ ϭ 1591 vs, 1557 w, 1480
s, 1283 vs, 1248 vs, 1186 vs, 1155 vs, 1102 vs, 1071 w, 1053 s, 1021
w, 1005 w, 915 s, 826 s, 802 vs, 774 s, 727 vs, 694 vs, 676 w, 622
s, 593 s cmϪ1. MS: m/z (%) ϭ 922 (Ͻ1%) [Sm(L2)3]ϩ 827 (Ͻ1),
[Sm(L2)2(C6H4NSiMe3)]ϩ, 757 (Ͻ1) [Sm(L2)2(OC6H5)]ϩ, 664 (10)
[Sm(L2)2]ϩ, 587 (Ͻ1) [Sm(L2)(OC6H4NSiMe3)]ϩ, 408 (3)
[Yb(OC6H4NSiMe3)]ϩ, 337 (10) [Yb(C6H4NSiMe3)]ϩ, 257 (45)
[(L2H)]ϩ, 242 (40) [(L2) Ϫ Me]ϩ, 226 (5) [(L2) Ϫ 2Me]ϩ, 165 (100)
[OC6H4NSiMe2]ϩ, 150 (35) [C6H4ONSiMe]ϩ, 73 (50) [SiMe3]ϩ.
C51H66N3O3Si3Yb (solvate) (1026.37): calcd. C 59.68, H 6.48, N
4.09. C45H54N3O3Si3Yb ([Yb(L2)3]) (942.27): calcd. C 57.36, H
5.78, N 4.46; found C 57.47, H 6.01, N 4.22.
Method 2 [2:1 Li to Ln mol ratio (in situ)]: nBuLi (1.65 mL,
2.60 mmol) was slowly added to a stirred solution of compound
[Sm(L2)]ϩ,
392
(3)
[Sm(L2)
Ϫ
MeH]ϩ,
331
(4)
L2H (0.64 g, 2.50 mmol) in THF (40 mL) at 0 °C and the resulting [Sm(OC6H4NSiMe3)]ϩ, 315 (5) [Sm(C6H4NSiMe3)]ϩ, 257 (100)
solution was warmed to room temperature over ca. 1 h.
[YbCl3(THF)3.5] (0.66 g, 1.25 mmol) was added to the resulting so-
lution, and the reaction mixture stirred rapidly for 12 h. The solv-
[(L2H)]ϩ, 242 (100) [(L2H) Ϫ Me]ϩ, 226 (20) [(L2) Ϫ 2Me]ϩ, 165
(100) [OC6H4NHSiMe2]ϩ, 150 (40) [C6H4ONHSiMe]ϩ, 73 (70)
[SiMe3]ϩ. H NMR (300 MHz, C6D6, 298 K): δ ϭ Ϫ1.63 (s, 27 H,
1
1434
Eur. J. Inorg. Chem. 2002, 1425Ϫ1438

Solvent-Free Lanthanoid Complexes Derived From Organoamide Ligands
FULL PAPER
3
4
3
4
SiMe3), 2.10 (s, 3 H, PhMe), 4.26 (br. s, 6 H, H-2Ј,H-6Ј), 5.31Ϫ5.45 (dd, J ϭ 7.6, J ϭ 1.2 Hz, 3 H, H-6), 6.26 (td, J ϭ 7.5, J ϭ 1.6
(br. s, 6 H, H-3Ј, H-5Ј), 5.49Ϫ5.60 (br. s, 3 H, H-4Ј), 6.30Ϫ6.50 (d,
Hz, 3 H, H-5), 6.72Ϫ6.90 (m, 21 H, H-3,H-4, H-2Ј-6Ј).
3J ϭ 7.5 Hz, 3 H, H-3 or H-6), 6.90Ϫ7.10 (m, 5 H, PhMe),
Method 3 [2:1 Li to Ln ratio (in situ)]: nBuLi (1.65 mL, 2.60 mmol)
was slowly added to a stirred solution of compound L3H (0.64 g,
2.50 mmol) in THF (40 mL) at 0 °C and the resulting solution was
warmed to room temperature over ca. 1 h. [LaCl3(THF)2] (0.49 g,
1.25 mmol) was added to the resulting solution, and the reaction
mixture stirred rapidly for 12 h. The solvent was removed in vacuo,
and hexane (30 mL) added affording a white precipitate. The pale
yellow solution was filtered and the filtrate volume reduced to ca.
15 mL under vacuum. Light yellow crystals were deposited on
standing. The infrared spectrum was identical with that of [La(L2)3]
[2e (Method 2)].
3
3
7.40Ϫ7.46 (t, J ϭ 7.5 Hz, 3 H, H-4 or H-5), 8.28Ϫ8.31 (t, J ϭ
3
7.4 Hz, 3 H, H-4 or H-5), 10.67Ϫ10.70 (d, J ϭ 8.0 Hz, 3 H, H-3
or H-6). C52H62N3O3Si3Sm (1012.33): calcd. C 61.73, H 6.18, N
4.15; found C 62.83, H 6.74, N 4.22.
[Nd(L2)3]·(PhMe)2 [2d·(PhMe)2]. Method 1: A similar preparation
method to that used for compound 2a·(PhMe) gave blue crystals
of the title complex (0.68 g, 62%). IR (Nujol): ν˜ ϭ 1591 vs, 1557
w, 1481 s, 1337 vs, 1285 vs, 1249 vs, 1187 vs, 1155 vs, 1103 vs, 1070
w, 1052 s, 1020 w, 1005 w, 916 vs, 826 s, 802 s, 773 s, 728 vs, 694
vs, 676 w cmϪ1 1H NMR (300 MHz, C6D6, 298 K): δ ϭ Ϫ8.05
.
(br. s, 6 H, H-2Ј,H-6Ј), Ϫ1.22 (br. s, 27 H, SiMe3), 0.48 (br. s, 6 H,
H-3Ј,H-5Ј), 0.90 (s, 3 H, H-4 or H-5), 1.20 (br. s, 3 H, H-4Ј), 2.11
(s, 6 H, PhMe), 6.97Ϫ7.14 (m, 13 H, H-4 or H-5 and PhMe), 13.90
(br. s, 3 H, H-3 or H-6), 23.28 (br. s, 3 H, H-3 or H-6).
C59H70N3NdO3Si3 (1094.38): calcd. C 64.56, H 6.43, N 3.83; found
C 64.48, H 6.54, N 4.13. Recrystallisation of [Nd(L2)3]·(PhMe)2
from hexane afforded crystals of solvent free [Nd(L2)3] (2d) used
for X-ray crystallography.
[Yb(enЈ)2(µ-Cl)]2 (3a): nBuLi (3.75 mL, 6.00 mmol) was slowly ad-
ded to a stirred solution of enЈH (0.88 g, 1.00 mL, 5.50 mmol) in
THF (50 mL) at 0 °C and the resulting solution was warmed to
room temperature over ca. 1 h. [YbCl3(THF)3] (1.36 g, 2.75 mmol)
was added to this solution, and the reaction mixture was rapidly
stirred for 12 h. The solvent was removed in vacuo, and hexane
added affording a white precipitate. The orange solution was fil-
tered and the filtrate volume reduced to ca. 2 mL under vacuum.
Orange crystals deposited on standing overnight (0.79 g, 55%). IR
(Nujol): ν˜ ϭ 1401 w, 1351 m, 1270 w, 1258 m, 1238 m, 1176 w,
1160 w, 1105 m, 1091 m, 1078 m, 1031 w, 1010 s, 952 s, 925 s, 858
s, 832 m, 778 w, 740 m, 679 w, 665 w cmϪ1. MS: m/z (%) ϭ 736
Method 2 [2:1 Li to Ln mol ratio (in situ)]: nBuLi (1.65 mL,
2.60 mmol) was slowly added to a stirred solution of compound
L2H (0.64 g, 2.50 mmol) in THF (40 mL) at 0 °C and the resulting
solution was warmed to room temperature over ca. 1 h.
[NdCl3(THF)2] (0.49 g, 1.25 mmol) was added to the resulting solu-
tion, and the reaction mixture was rapidly stirred for 12 h. The
solvent was removed in vacuo, and hexane (30 mL) added affording
a white precipitate. The blue solution was filtered and the filtrate
volume reduced to ca. 15 mL under vacuum. Blue crystals of
[Nd(L2)3] (2d) deposited on standing. (Infrared identification) Unit
Cell data [C45H54N3NdO3Si3, M ϭ 910.3, monoclinic, a ϭ
(Ͻ1) [M(dimer)
Ϫ
(2 L)]ϩ, 701 (Ͻ1) [Yb2(L)2Cl]ϩ, 527 (2)
[Yb(L)2Cl]ϩ, 333 (50) [Yb(L)]ϩ, 73 (45) [SiMe3]ϩ, 58 (100)
[SiMe2]ϩ. C28H76Cl2N8Si4Yb2 (1054.32): calcd. C 31.90, H 7.27, N
10.66, Yb 32.83; found C 31.35, H 7.28, N 9.60, Yb 33.18.
[Er(enЈ)2(µ-Cl)]2 (3b): A similar preparation method to that used
for compound 3a gave pink crystals of 3b (0.76 g, 53%). IR in satis-
factory agreement with that reported for an analytically pure
sample.[27] MS: m/z (%) ϭ 883 (Ͻ1) [M(dimer) Ϫ (L)]ϩ, 724 (1)
[M(dimer) Ϫ (2 L)]ϩ, 521 (1) [Er(L)2Cl]ϩ, 325 (25) [Er(L)]ϩ, 73 (35)
[SiMe3]ϩ, 58 (100) [SiMe2]ϩ.
˚
16.154(1), b ϭ 15.459(1), c ϭ 17.992(1) A; α ϭ 90°, β ϭ 103.0(1°),
3
˚
γ ϭ 90°; V ϭ 4378.1 A , T ഠ 123 K] were in agreement with those
obtained for crystals from Method 1 (Table 5).
[La(L2)3]·(PhMe) (2e·(PhMe)]. Method 1: A similar preparation
method to that used for compound 2a·(PhMe) gave yellow crystals
of the title complex (0.35 g, 35%). IR (Nujol): ν˜ ϭ 1589 vs, 1557
m, 1480 s, 1287vs, 1249 vs, 1188 vs, 1155 vs, 1103 vs, 1070 w, 1050
s, 1020 m, 1004 w, 919 s, 858 w, 824 m, 803 vs, 770 vs, 694 vs, 675
w, 618 s, 592 s, 562 w cmϪ1. MS: m/z (%) ϭ 651 (3) [La(L2)2]ϩ, 395
(Ͻ1) [La(L2)]ϩ, 257 (70) [(L2H)]ϩ, 242 (65) [(L2H) Ϫ Me]ϩ, 226
(15) [(L2) Ϫ 2Me]ϩ, 165 (100) [OC6H4NHSiMe2]ϩ, 150 (40)
[C6H4ONHSiMe]ϩ, 135 (30) [C6H4OSiNH]ϩ, 73 (50) [SiMe3]ϩ. 1H
NMR (300 MHz, C6D6, 298 K): δ ϭ 0.36 (s, 27 H, SiMe3), 2.10 (s,
[Sm(enЈ)2(µ-Cl)]2 (3c): A similar procedure to that used for com-
pound 3a gave yellow crystals of 3c (0.58 g, 42%). IR (Nujol): ν˜ ϭ
1401 w, 1349 m, 1310 w, 1258 m, 1246 s, 1195 w, 1169 w, 1156 sh
w, 1103m, 1087 m, 1079 m, 1035 w, 1020 s, 953 m, 924 s, 859 s, 828
br. s, 779 sh m, 735 m, 676 w, 662 m, 619 w, 554 w cmϪ1. MS: m/
z (%) ϭ 689 (Ͻ1) [M(dimer) Ϫ (2 L)]ϩ, 507 (1) [Sm(L)2Cl]ϩ, 348
(20) [Sm(L)Cl]ϩ, 311 (15) [Sm(L)]ϩ, 281 (25) [Sm(L) Ϫ 2Me]ϩ, 73
(50) [SiMe3]ϩ, 58 (100) [SiMe2]ϩ.
[Nd(enЈ)2(µ-Cl)]2 (3d): A similar procedure to that used for com-
pound 3a gave blue crystals of 3d (0.70 g, 51%). IR (Nujol): ν˜ ϭ
1348 m, 1259 m, 1246 s, 1168 w, 1104 m, 1079 m, 1154 m, 1036 w,
1020 s, 952 w, 938 s, 924 s, 851 s, 827 br. s, 780 sh m, 734 m, 676
w, 662 m, 554 w cmϪ1. MS: m/z (%) ϭ 835 (Ͻ1) [{144Nd(L)2(µ-
Cl)}2 Ϫ (L)]ϩ, 676 (Ͻ1) [{144Nd(L2(µ-Cl)}2 Ϫ (2 L)]ϩ, 482 (1)
3
4
3 H, PhMe), 6.11 (dd, J ϭ 8.1, J ϭ 1.4 Hz, 3 H, H-6), 6.28 (td,
4
3J ϭ 7.2, J ϭ 1.3 Hz, 3 H, H-5), 6.74Ϫ6.90 (m, 21 H, H-3, H-4,
H-2ЈϪ6Ј), 6.97Ϫ7.13 (m, 5 H, PhMe). C52H62LaN3O3Si3 (999.32):
calcd. C 62.44, H 6.25, N 4.20; found C 62.27, H 6.35, N
4.32. Method 2 [La(L2)3] (2e) (using a 1:2 Ln to Li ratio): LaCl3
(0.18 g, 0.75 mmol) and [Li(L2)(DME)] (0.53 g, 1.50 mmol) were
stirred together in THF (40 mL). After 12 h, the pale yellow solu-
tion was evaporated to dryness under reduced pressure and toluene
was added. The resulting white solid was filtered, the filtrate was
evaporated to dryness and Et2O was added (20 mL). The solution
was concentrated to ca. 10 mL and on standing for two days col-
ourless crystals of 2e (suitable for an X-ray crystallographic study)
were deposited (0.35 g, 77%). IR (Nujol): ν˜ ϭ 1590 vs, 1557 m,
[
144Nd2(L)Cl]ϩ, 338 (50) [144Nd(L)Cl]ϩ, 73 (45) [SiMe3]ϩ, 58 (100)
[SiMe2]ϩ. C28H76Cl2N8Nd2Si4 (990.28): calcd. Nd 28.94; found
Nd 29.15.
[La(enЈ)2(µ-Cl)]2 (3e): A similar preparation to that for compound
3a gave colourless crystals of 3e (0.63 g, 46%). IR (Nujol): ν˜ ϭ
1439 w, 1348 w, 1314 w, 1239 br. s, 1160 s, 1121 s, 1092 s, 1077 w,
1037 w, 1021 w, 998 m, 962 m, 923 m, 848 s, 830 br. s, 748 w, 725
1480 s, 1444 s, 1288 vs, 1251 vs, 1189 vs, 1155 vs, 1102 vs, 1072 w, m, 694 m, 664 w, 541 w cmϪ1. MS: m/z (%) ϭ 825 (5) [M(dimer)
1052 s, 1020 m, 1004 w, 964 w, 917 s, 858 w, 826 m, 801 s, 771 s,
Ϫ (L)]ϩ, 457 (30) [La(L)2]ϩ, 333 (80) [La(L)Cl]ϩ, 73 (20) [SiMe3]ϩ,
1H 58 (100) [SiMe2]ϩ. C28H76Cl2La2N8Si4 (984.28): calcd. La 28.17;
found La 28.02.
735 s, 722 s, 695 s, 674 w, 632 w, 622 s, 594 s, 559 w cmϪ1
.
NMR (300 MHz, C6D6, 298 K): δ ϭ 0.35 (s, 27 H, SiMe3), 6.10
Eur. J. Inorg. Chem. 2002, 1425Ϫ1438
1435

G. B. Deacon, C. M. Forsyth, N. M. Scott
FULL PAPER
[Yb(L1)2(µ-Cl)]2 (4a): [Li(L1)(OEt2)]2 (0.76 g, 1.37 mmol) was ad-
ded to a stirred suspension of [YbCl3(THF)3] (0.68 g, 1.37 mmol)
in THF (40 mL). The solution was stirred for 15 h, the solvent was
removed under vacuum and hexane (30 mL) was added. After heat-
ing the stirred solution for 2 h, the warm mixture was filtered and
on cooling to room temperature the filtrate afforded red crystals
(suitable for X-ray analysis) of the title complex (0.51 g, 63%). IR
(Nujol): ν˜ ϭ 1594 s, 1563 w, 1318 w, 1290 s, 1277 s, 1242 vs, 1210
m, 1158 s, 1117 vs, 1051 m, 1002 s, 917 s, 844 vs, 826 s, 792 w, 768
m, 730 vs, 679 m, 627 w, 597 w cmϪ1. Vis/near IR (DME): λmax
(ε) ϭ 457 (156), 935 (4), 982 (18), 985 (17) nm (dm3 molϪ1).
C40H64Cl2N4O4Si4Yb2 (1194.30): calcd. C 40.23, H 5.40, N 4.69;
found C 39.15, H 5.57, N 4.72.
under vacuum (ca.15 mL). Upon standing overnight single blue
crystals suitable for X-ray crystallography formed (0.35 g, 72%). IR
(Nujol): ν˜ ϭ 1585 s 1294 s, 1266 m, 1243 s, 1185 s, 1160 s, 1100 s,
1074 w, 1036 m, 1022 w, 936 vs, 859 m, 828 br. s, 774 m, 746 s, 727
s, 690 s, 679 w, 623 w cmϪ1. Vis/near IR (DME): λmax (ε) ϭ 527
(55), 586 (75), 755 (25), 811 (28), 885 (22) nm (dm3 molϪ1). 1H
NMR (300 MHz, C6D6, 298 K): δ ϭ Ϫ8.73 (br. s, 8 H, H-2Ј,H-6Ј),
Ϫ5.04 (br. s, 36 H, SiMe3), 0.08 (s, 8 H, H-3Ј,H-5Ј), 1.18 (s, 4 H,
H-4Ј), 1.49 (br. s, 8 H, H-4, H-5), 2.10 (s, 6 H, PhMe), 7.02Ϫ7.20
(m, 10 H, PhMe), 15.4 (br. s, 4 H, H-3 or H-6), 30.95 (br. s, 4 H,
H-3 or H-6). C74H88Cl2N4Nd2O4Si4 (1569.22): calcd. C 54.64, H
5.65, N 3.57; found C 54.47, H 5.53, N 3.63.
[Li(L1)(OEt2)]2: nBuLi (32 mL, 0.05 mol) was added dropwise to a
stirred solution of L1H (0.05 mol, 10 g) in Et2O (80 mL) at 0 °C,
and the resulting solution was warmed to room temperature over
ca. 1 h. The resulting white precipitate was cooled to Ϫ78 °C,
washed with hexane (40 mL) and dried under vacuum (11.9 g,
86%). A small amount of [Li(L1)(OEt2)]2 was redissolved in Et2O
whereupon light-sensitive colourless crystals of good X-ray quality
formed. IR (Nujol): ν˜ ϭ 1585vs, 1558s, 1280s, 1239s, 1212s, 1171s,
1117vs, 1052s, 1029vs, 934s, 840s, 821s, 734vs, 660s, 594s cmϪ1. MS:
m/z (%) ϭ 201 (100) [LiL1]ϩ, 195 (25) [L1H]ϩ, 165 (60) [L1H Ϫ
2Me]ϩ, 150 (25) [L1H Ϫ 3Me]ϩ, 135 (20) [C6H5ONSi]ϩ, 73 (40)
[SiMe3]ϩ, 58 (20) [SiMe2]ϩ. 1H NMR (300 MHz, C7D8, 298 K):
[Er(L1)2(µ-Cl)]2 (4b): Addition of [Li(L1)(OEt2)]2 (0.55 g,
1.00 mmol) to a suspension of [ErCl3(THF)2] (0.42 g, 1.00 mmol)
in THF (40 mL) resulted in precipitation of a white solid and
formation of a pink solution. The solvent was removed under va-
cuum and hexane added (30 mL). The mixture was then warmed
and filtered. The filtrate was concentrated to ca. 25 mL affording
X-ray quality pink crystals of 4b (0.36 g, 61%). IR (Nujol): ν˜ ϭ
1593 s, 1563 w, 1318 w, 1291 s, 1277 m, 1242 s, 1210 w, 1158 s,
1116 vs, 1051 m, 1001 s, 916 vs, 843 vs, 822 s, 788 m, 768 m, 729 vs,
679 m, 626 s, 597 s cmϪ1. C40H64Cl2Er2N4O4Si4 (1182.73): calcd. C
40.62, H 5.45, N 4.74; found C 39.79, H 5.54, N 4.96.
3
[Tb(L1)2(µ-Cl)]2 (4c): A similar preparation method to that used
for compound 4a gave large pale yellow crystals of 4c (0.40 g, 68%).
IR (Nujol): ν˜ ϭ 1593 s, 1563 w, 1504 s, 1320 w, 1293 s, 1265 s, 1240
s, 1210 w, 1158 s, 1115 vs, 1051 m, 1001 s, 914 vs, 842 vs, 826 sh
w, 783 m, 766 m, 727 vs, 669 m, 625 s, 596 s cmϪ1. C40H64Cl2N4O4-
Si4Tb2 (1166.06): calcd. C 41.20, H 5.53, N 4.80; found C 41.42, H
5.39, N 4.76.
δ ϭ 0.11 (s, 18 H, SiMe3), 1.04 [t, J ϭ 7.0 Hz, 12 H, Me (OEt2)],
3.26 [q, 3J ϭ 7.0 Hz, 8 H, CH2 (OEt2)], 3.35 (s, 6 H, OMe),
3
6.50Ϫ6.57 (dd, J ϭ 7.2, 4J ϭ 1.6 Hz, 2 H, H-6), 6.62Ϫ6.68 (td,
4
3
3J ϭ 7.0, J ϭ 1.5 Hz, 2 H, H-5), 6.85Ϫ6.95 (td, J ϭ 7.0, 4J ϭ
3
4
1.6 Hz, 2 H, H-4), 6.96Ϫ7.04 (dd, J ϭ 7.2, J ϭ 1.7 Hz, 2 H, H-
3). 7Li NMR (155.51 MHz, C7D8, 298 K): δ ϭ 1.85. C28H52Li2-
N2O4Si2 (550.79) (solvate): calcd. C 61.06, H 9.52, N 5.09.
C10H16LiNOSi (201.27) (LiL2): calcd. C 59.68, H 8.01, N 6.96;
found C 58.92, 59.08, H 8.84, 8.67, N 5.82, 6.01.
[Nd(L2)2(µ-Cl)]2·(PhMe)2 [5a·(PhMe)2]: [Li(L2)(DME)] (0.72 g,
2.00 mmol) was added to a stirred solution of [NdCl3(THF)2]
(0.40 g, 1.00 mmol) in THF (40 mL). The resulting blue solution
Structure Determinations: Data for the crystallographic structure
was evaporated to dryness and toluene was added (30 mL). The determinations of compounds 1e, 2a·(PhMe), 2d and 2e are given
reaction mixture was filtered and the filtrate volume was reduced
in Table 5 while similar data for 4aϪ4c, 5a·(PhMe)2 and [Li(L1)-
Table 6. Crystallographic and refinement parameters for [Ln(L)2(µ-Cl)]2 and [Li(L1)(OEt2)]2 complexes
1436
Eur. J. Inorg. Chem. 2002, 1425Ϫ1438

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