Rare earth complexes of bulky 2,6-diphenylphenolates containing additional, potentially buttressing 3,5-substituents

Article abstract of DOI:10.1002/1099-0682(200106)2001:6<1505::AID-EJIC1505>3.0.CO;2-V

The rare earth aryloxide complexes, [Yb(OAr^tBu)₃-(THF)]·THF, [Sc(OAr^tBu)₃(THF)]·THF, [Yb(OAr^Me)₃(THF)], and [Sm(OAr^Ph)₃(THF)₂] (OAr^R = 2,6-diphenyl-3,5-di-R-phenolate), have been prepared by redox transmetallation/ligand exchange between the rare earth metal, bis(pentafluorophenyl) mercury, and HOAr^R in tetrahydrofuran. This reaction also provided [Yb(OAr^Ph)₃(DME)]·3/2THF by incorporation of adventitious 1,2-dimethoxyethane. A similar reaction between Yb metal, diphenylmercury, and HOAr^Me gave [Yb(OAr^Me)₂(THF)₃]. The homoleptic complexes [Yb(OAr^Ph)₃] and [Sc(OAr^H)₃] have been prepared by direct reaction of the rare earth element with HOAr^R in a sealed tube in the presence of mercury at elevated temperatures (200-250 °C) and the latter was converted into [Sc(OAr^H)₃(THF)] by treatment with THF. X-ray crystal structure determinations of [Yb(OAr^tBu)₃(THF)]·THF, [Sc(OAr^tBu)₃(THF)]·THF, and [Yb(OAr^Me)₃(THF)] show the complexes to be monomeric and four coordinate with a trigonal pyramidal stereochemistry. These structures provide clear evidence that groups meta to the phenolate donor can modify the coordination behaviour of the 2,6-diphenylphenolate ligand. In [Yb(OAr^Ph)₃(DME)]·3/2THF a distorted square pyramidal stereochemistry is observed. The divalent complex [Yb(OAr^Me)₂(THF)₃] exhibits a distorted trigonal bipyramidal arrangement of the oxygen donor atoms with apical THF ligands. The homoleptic scandium 2,6-diphenylphenolate has three oxygen atoms in a triangular array with additional π-η¹Ph···Sc interactions above and below the ScO₃ plane [C-Sc-C = 154.2(8)°], providing a new type of binding of this aryloxide ligand.

Full text of DOI:10.1002/1099-0682(200106)2001:6<1505::AID-EJIC1505>3.0.CO;2-V

FULL PAPER
Rare Earth Complexes of Bulky 2,6-Diphenylphenolates Containing Additional,
Potentially Buttressing 3,5-Substituents[‡]
Glen B. Deacon,*[a] Phillip E. Fanwick,[b] Alex Gitlits,[a] Ian P. Rothwell,[b]
Brian W. Skelton,[c] and Allan H. White[c]
Keywords: Mercury / Lanthanides / O ligands / Ytterbium
The rare earth aryloxide complexes, [Yb(OArtBu)3-
(THF)]·THF, [Sc(OArtBu)3(THF)]·THF, [Yb(OArMe)3(THF)],
= 2,6-diphenyl-3,5-di-R-
phenolate), have been prepared by redox transmetallation/
ligand exchange between the rare earth metal, bis(penta-
ture
determinations
of
[Yb(OArtBu)3(THF)]·THF,
[Sc(OArtBu)3(THF)]·THF, and [Yb(OArMe)3(THF)] show the
complexes to be monomeric and four coordinate with a tri-
gonal pyramidal stereochemistry. These structures provide
clear evidence that groups meta to the phenolate donor can
and [Sm(OArPh)3(THF)2] (OArR
fluorophenyl)mercury, and HOArR in tetrahydrofuran. This modify the coordination behaviour of the 2,6-diphenylph-
reaction also provided [Yb(OArPh)3(DME)]·3/2THF by in-
enolate ligand. In [Yb(OArPh)3(DME)]·3/2THF a distorted
corporation of adventitious 1,2-dimethoxyethane. A similar square pyramidal stereochemistry is observed. The divalent
reaction between Yb metal, diphenylmercury, and HOArMe
gave [Yb(OArMe)2(THF)3]. The homoleptic complexes
[Yb(OArPh)3] and [Sc(OArH)3] have been prepared by direct
reaction of the rare earth element with HOArR in a sealed
tube in the presence of mercury at elevated temperatures
(200−250 °C) and the latter was converted into
[Sc(OArH)3(THF)] by treatment with THF. X-ray crystal struc-
complex [Yb(OArMe)2(THF)3] exhibits a distorted trigonal bi-
pyramidal arrangement of the oxygen donor atoms with ap-
ical THF ligands. The homoleptic scandium 2,6-diphenylph-
enolate has three oxygen atoms in a triangular array with
additional π-η1-Ph···Sc interactions above and below the
ScO3 plane [C−Sc−C = 154.2(8)°], providing a new type of
binding of this aryloxide ligand.
Introduction
Amongst rare earth aryloxides and alkoxides,[1] 2,6-di-
tert-butyl-4-X-phenolates (X ϭ H, Me, tBu) have been sem-
inal in stabilising low coordination numbers,[2] especially in
homoleptic complexes.[2aϪ2c,2h,2i] With the less bulky[3a,3b]
2,6-diphenylphenolate, low coordination number complexes
can still be obtained,[4] but the homoleptic lanthanoid(II or
III) 2,6-di-phenylphenolates are noteworthy for intramolec-
ular π-Ph···Ln interactions (η1; η2; η3; η4; η6)[4a,4c,5] in addi-
tion to oxygen coordination, which can be quite irregu-
lar.[5a] One way of potentially increasing the bulkiness of
2,6-diphenylphenolate ligands[3b] is to add 3,5-substituents,
which should reduce the flexibility of the phenyl groups and
cause them to shield the donor atoms more. A range of
such ligands is now available (e.g. 1bϪc) and exploration of
their d-block and main group coordination chemistry has
commenced.[6]
We now examine the effect of buttressing substituents in
rare earth chemistry with the synthesis and structural study
of complexes with ligands 1bϪ1d. In addition the homolep-
tic scandium complex with the parent ligand 1a has been
prepared and the structure determined. Previous studies of
[Ln(OArH)3] complexes[5b] did not extend to the smaller
(and much more expensive) Sc. It is of interest to determine
the effect of reduced metal size on intramolecular π-Ph···Ln
coordination, so far observed in [Ln(OArH)3] complexes as
η6 ϩ η3 (Ln ϭ La) and η6 ϩ η1 (Ln ϭ Ce, Pr, Nd, Y,
Yb, Lu).[4a,4c,5b]
[‡]
Organoamido- and Aryloxo-lanthanoids, 25. Ϫ Part 24:
G. B. Deacon, A. Gitlits, P. W. Roesky, M. R. Bürgstein,
K. C. Lim, B. W. Skelton, A. H. White, Chem. Eur. J. 2001,
7, 127Ϫ138.
[a]
Monash University, School of Chemistry,
P. O. Box 23, Victoria 3800, Australia
Fax: (internat.) ϩ61-3/9905-4597
Results and Discussion
E-mail: Glen.Deacon@sci.monash.edu.au
[b]
Department of Chemistry, 1393 Brown Building, Purdue
University,
Syntheses
West Lafayette, IN 47907Ϫ1393, USA
Fax: (internat.) ϩ1-765/494-0239
Reaction of lanthanoid metals with bis(pentafluorophen-
yl)mercury, and 2,6-diphenyl-3,5-di-R-phenols 1bϪ1d in
tetrahydrofuran yielded the complexes [Yb(OArR)3THF]
[c]
Department of Chemistry, University of Western Australia,
Nedlands, WA 6907, Australia
Fax: (internat.) ϩ61-8/9281-1005
Eur. J. Inorg. Chem. 2001, 1505Ϫ1514
WILEY-VCH Verlag GmbH, 69451 Weinheim, 2001
1434Ϫ1948/01/0606Ϫ1505 $ 17.50ϩ.50/0
1505

G. B. Deacon, P. E. Fanwick, A. Gitlits, I. P. Rothwell, B. W. Skelton, A. H. White
FULL PAPER
(R ϭ Me or tBu), [Sm(OArPh)3(THF)2], and [Sc(OArtBu)3- for
(THF)] [Equation (1)].
[Yb(OArtBu)3(THF)]·THF,
[Yb(OArMe)3(THF)],
[Sc(OArtBu)3(THF)]·THF,
and
[Yb(OArPh)3(DME)]·
1.5THF, as well as the analytically satisfactory [Yb(O-
ArMe)2(THF)3] and [Sc(OArH)3] (next section). In contrast,
complexes of the OArH ligand do not normally present ana-
lytical difficulties.[4,5] Microanalyses and metal analyses for
(1)
From an analogous reaction with ytterbium metal and
HOArPh, the product was found to contain fortuitously in-
corporated DME, even though it was isolated as a THF
solvate, [Yb(OArPh)3(DME)]·1.5THF [Equation (1); R ϭ
Ph]. The complex was also obtained as a DME solvate from
a similar reaction in DME, but could not be obtained pure
(see Experimental Section). When diphenylmercury was
bulk [Ln(OArtBu)3(THF)]·THF (Ln
ϭ Sc, Yb) and
[Yb(OArMe)3(THF)] dried for 1Ϫ2 h under vacuum at room
temperature, though somewhat divergent from calculated C
values, suggested that these drying conditions did not re-
move coordinated THF or THF of solvation. This was sup-
ported by NMR integrations in the case of the scandium
complex, although meaningful spectra could not be ob-
tained for the paramagnetic YbIII complexes. Both
[Ln(OArtBu)3(THF)]·THF complexes have infrared absorp-
tions at ca. 910 and 860 cmϪ1 plausibly attributable[10,11] to
ring stretching of free (e.g. solvent of crystallisation) and
used in place of Hg(C6F5)2 in the reaction with HOArMe
,
the divalent complex [Yb(OArMe)2(THF)3] was obtained
[Equation (2)].
(2)
coordinated
THF,
respectively.
Tris(2,3,5,6-tetra-
In previous redox transmetallation/ligand exchange reac-
tions with Hg(C6F5)2, YbIII complexes have been obtained
with HOArH [4a] whereas YbII derivatives have been isolated
with 2,6-di-tert-butylphenolate ligands,[2dϪ2f] despite the
general use of an excess of lanthanoid metal. However, in
redox transmetallation/ligand exchange reactions of ytter-
bium with 3,5-di-tert-butylpyrazole, use of Hg(C6F5)2 gave
trivalent complexes[7] whereas HgPh2 provided divalent
compounds,[8] a relationship now seen with 2,6-diphenyl-
3,5-dimethylphenol. Electrochemical studies[9] as well as
synthetic behaviour[7,8,10] show that Hg(C6F5)2 is a more
powerful oxidant than HgPh2.
The synthesis of homoleptic complexes was also at-
tempted by direct reaction of metals with HOArR (R ϭ Ph
or tBu) at elevated temperature in the presence of mercury.
In general, decomposition products were obtained or the
resulting lanthanoid complexes could not be crystallised,
viz. from Yb/HOArtBu at 250 °C, Yb/HOArPh at 300 °C and
at 200Ϫ220 °C, and Nd/HOArPh at 200Ϫ300 °C. However,
reaction of Yb with HOArPh strictly at 200 °C (i.e. below
the ligand melting point) allowed [Yb(OArPh)3] to be pre-
pared in good yield [Equation (3), Ln ϭ Yb, R ϭ Ph].
phenylphenolato)samarium(III) was isolated with satisfact-
ory analyses for a bis(THF) species. Since the sample was
dried at 80 °C under vacuum, it is plausible that both ether
molecules are coordinated, an effect of the larger size of
Sm3ϩ than Yb3ϩ [12]
Aryloxide IR absorptions at 910Ϫ850
.
cmϪ1 (see [Yb(OArPh)3]) rule out the use of IR spectroscopy
to ascertain the nature of THF in the Sm complex. Single
crystals of [Sc(OArH)3(THF)] could not be grown, but it
seems uncontentious that THF is coordinated in view of
the structure of [Sc(OArtBu)3(THF)]·THF with a bulkier
phenolate ligand, and since THF is retained on drying at
150 °C under vacuum. Moreover, the THF resonances are
shifted from the ‘‘free’’ values consistent with coordination
in solution (see Experimental Section). The analyses of the
bulk sample of [Yb(OArPh)3(DME)] dried at 80 °C are mar-
ginally closer for this composition than for
[Yb(OArPh)3(DME)]·1.5THF, which is the composition of
the undried single crystals. An IR absorption at 1044 cmϪ1
,
not observed for [Yb(OArPh)3], is indicative of coordinated
DME.[4d,13] A sample of the complex prepared in DME and
dried at room temperature under vacuum was not obtained
analytically pure but the analyses (especially for Yb) fa-
voured the composition [Yb(OArPh)3(DME)]·DME. The
divalent complex [Yb(OArMe)2(THF)3] gave satisfactory
(3)
This contrasts with the corresponding reaction of Yb
with HOArH, which yields [Yb(OArH)2]2 and the mixed ox-
idation state complex [Yb2II(OArH)3][YbIII(OArH)4].[5a] In
addition, [Sc(OArH)3] was obtained by reaction (3) (Ln ϭ
Sc, R ϭ H), showing that for the 2,6-diphenylphenolate li-
gand, the method is applicable to the smallest rare earth
metal. Crystallization from THF gave the solvate
[Sc(OArH)3(THF)].
1
analyses and the H NMR spectrum in C6D6 is consistent
with this composition. However, the detection of two
methyl resonances, a single, very broad THF resonance, and
underlying broadness in the aromatic region suggests that
an equilibrium occurs in C6D6 [Equation (4)] with both
complexes detectable by their Me resonances.
(4)
Properties and Characterisation
Complexes of both compositions have been observed for
Because of the difficulty in obtaining entirely satisfactory the bulky 2,6-di-tert-butylphenolate ligands.[2e,2f,2i]
microanalyses for Ln(OArR)3 (R ϭ Me, tBu, Ph), a feature
The mass spectra of several representative complexes
previously noted for complexes of these buttressed ligands[6] were recorded. Surprisingly, ions with three OArR ligands
and attributed to carbide formation,[6a] knowledge of the were detected only for [Yb(OArMe)3(THF)]. In other cases,
composition of the complexes is particularly dependent on as well as for [Yb(OArMe)2(THF)3], [Ln(OArR)2]ϩ was the
X-ray structure determinations. These have been carried out highest structurally significant feature. Near infrared ab-
1506
Eur. J. Inorg. Chem. 2001, 1505Ϫ1514

Rare Earth Complexes of Bulky 2,6-Diphenylphenolates
FULL PAPER
sorption at 900Ϫ1000 nm was observed for the YbIII com-
plexes, as expected,[14] but appropriately was absent for
[Yb(OArMe)2(THF)3].
Molecular Structures
The Complexes [Ln(OArtBu)3(THF)]·THF (Ln ؍ Yb or Sc)
and [Yb(OArMe)3(THF)]
The structures of these complexes are closely related. Two
representative structures in which the metal size and the
aryloxide ligand are varied are shown in Figure 1 and 2,
with Ln-based distances and angles in Table 1. All three
complexes are four-coordinate monomers, displaying a ste-
reochemistry substantially distorted from tetrahedral, sim-
ilar to that of [Yb(OC6H2tBu3-2,4,6)3(THF)].[2g] The strik-
ing reduction in coordination number from five in
[Yb(OArH)3(THF)2],[4a] especially given the further THF
present as solvent of crystallisation, indicates that OArR
(R ϭ tBu, Me and presumably also Ph) ligands can be con-
sidered bulkier than the simple 2,6-diphenylphenolate, con-
sistent with buttressing of the 2,6-diphenyl substituents by
the 3,5-substituents. There are no unusual features in the
packing of the 2,6-diphenyl substituents, which are com-
mon to the three compounds, and they do not appear to
have any overriding influence on the stereochemistry. Thus
the interplanar angles involving the phenyl substituents
(Table 2) vary markedly between the three complexes. Some
similarity is evident between the two complexes with OArtBu
Figure 2. Molecular projection of [Yb(OArMe)3(THF)]
Table 1. Metal atom environments, [Ln(OArR)3(THF)]; the three
values in each entry are for Ln/R ϭ Sc/tBu, Yb/Me and Yb/tBu,
respectively; in this and subsequent tables, r is the metalϪligand
distance; other entries are the angles subtended at the metal by the
ligands, but there are still some significant differences relevant atoms at the head of the row and column
(Table 2).
The LnϪOArR bond lengths (Table 1) show little vari-
ation for each compound and between the two
[Yb(OArR)3(THF)] (R ϭ tBu or Me) complexes. Subtrac-
tion of an extrapolated radius (from data in ref.[12]) for four
Atom
r
O(21)
O(31)
O(41)
O(11)
1.913(3)
2.032(4)
2.038(3)
111.5(1)
106.4(2)
111.8(1)
116.8(1)
121.7(1)
122.39(9)
106.4(1)
106.8(1)
104.3(1)
coordinate Sc3ϩ or Yb3ϩ (0.62 and 0.75 A, respectively)
˚
O(21)
O(31)
1.914(3)
2.033(4)
2.029(3)
117.9(1)
117.6(1)
113.5(1)
100.6(1)
100.7(2)
99.34(9)
1.922(3)
2.045(4)
2.042(3)
100.7(1)
100.7(2)
101.6(1)
O(41)
(THF)
2.118(2)
2.247(4)
2.236(2)
R
˚
from ϽLnϪOAr Ͼ gives 1.29Ϫ1.30 A, which is within the
usual range for bulky lanthanoid aryloxides, including
[2g]
˚
[Yb(OC6H2tBu3-2,4,6)3(THF)] (1.28 A).
However, the
latter compound shows a wider variation in LnϪOAr bond
[2g]
˚
lengths [1.97(1)Ϫ2.09(1) A].
There are similar
YbϪO(THF) distances for the two Yb compounds, and
subtraction of the four-coordinate ionic radius from
˚
LnϪO(THF) values gives 1.49Ϫ1.50 A for the three
[Ln(OArR)3(THF)] complexes, at the low end of the range
˚
(1.49Ϫ1.59 A) for THF complexes of bulky lanthanoid aryl-
Figure 1. Molecular projection of [Sc(OArtBu)3(THF)]
oxides.[2f,2g,4c,4d]
Eur. J. Inorg. Chem. 2001, 1505Ϫ1514
1507

G. B. Deacon, P. E. Fanwick, A. Gitlits, I. P. Rothwell, B. W. Skelton, A. H. White
FULL PAPER
R
˚
Table 2. Ligand descriptors (A, degrees) for the complexes [Ln(OAr )n(L)m]; θ values are dihedral angles between the C6 ring planes [c:
central; p2,6: peripheral; O3: O(n1)3]; δLnc and δLnO3 are the deviations of the metal atoms from the central and O3 planes; R indicates
the substituents at the 3- and 5-positions of the central ring; L (co-ligands if present) ϭ THF or DME; Σ(OϪLnϪO) is the sum of the
angles defined by the phenolate oxygen atoms about the metal[a]
Ln/R
Ligand Lm
Sc/tBu
THF
Yb/Me
THF
Yb/tBu
THF
Yb/Ph
DME
YbII/Me
(THF)3
Sc/H
Ϫ
[a]
Ligand 1
O(11)ϪC(11)
LnϪO(11)ϪC(11)
θc/p2
θc/p6
θp2/p6
1.357(6)
162.3(3)
74.6(2)
78.8(2)
61.8(2)
66.2(1)
0.803(8)
1.347(6)
157.0(3)
57.6(2)
67.7(2)
82.2(2)
50.2(2)
0.77(1)
1.349(5)
161.1(2)
74.5(1)
85.7(2)
62.4(2)
64.7(1)
0.862(8)
1.35(1)
170.3(6)
67.8(5)
71.4(5)
60.2(6)
68.1(3)
0.40(2)
1.31(1)
157.9(5)
56.4(3)
79.2(4)
69.1(5)
Ϫ
1.38(3)
144(2)
58.2(9)
57.4(10)
56.6(9)
83.6(8)
0.02(3)
θc/O3
δLnc
0.23(2)
Ligand 2
O(21)ϪC(21)
LnϪO(21)ϪC(21)
θc/p2
θc/p6
θp2/p6
1.354(5)
167.3(3)
80.8(2)
70.1(2)
65.0(2)
45.6(1)
0.434(8)
1.342(6)
163.0(3)
58.7(2)
68.9(2)
49.4(2)
63.7(2)
0.57(1)
1.348(4)
166.8(3)
86.6(2)
71.7(2)
61.6(2)
46.5(1)
0.529(8)
1.34(1)
161.8(7)
53.8(4)
54.5(4)
88.9(4)
45.6(3)
0.06(2)
1.314(9)
175.8(5)
47.1(5)
70.8(4)
49.8(6)
Ϫ
1.38(3)
144(2)
55.5(9)
56.0(9)
57.1(9)
79.4(8)
0.27(5)
θc/O3
δLnc
0.09(2)
Ligand 3
O(31)ϪC(31)
LnϪO(31)ϪC(31)
θc/p2
θc/p6
θp2/p6
1.349(4)
157.6(3)
70.1(2)
74.0(2)
62.3(2)
46.7(1)
0.887(8)
1.341(6)
153.8(4)
78.0(2)
71.5(2)
64.1(2)
47.8(2)
1.15(1)
1.340(4)
154.5(3)
71.9(2)
74.3(1)
64.7(2)
47.4(1)
1.026(7)
1.35(1)
171.7(7)
54.2(5)
50.5(6)
57.7(6)
34.0(3)
0.11(2)
1.36(2)
178(2)
45.0(10)
43.7(10)
78.3(9)
33.4(7)
0.12(6)
θc/O3
δLnc
Σ(OϪLnϪO)
δLnO3
346.2
0.416(1)
345.7
0.448(1)
347.7
0.417(1)
319.6
0.772(1)
360.0
0.011(9)
[a]
Dihedral angles of the second disordered component of substituent ring 6 to its associated central and other peripheral planes are
68.6(6), 49.8(6), and to its first component 2.8(5)°. In [Yb(OArPh)3(DME)], 3,5-substituent C6 planes in the three ligands lie at 55.6(6),
55.3(5); 57.9(5), 52.7(4); 57.1(6), 49.5(5)° to their central C6 planes.
There are significant variations of the OϪLnϪO angles O(11) as the apex, and cisoid aryloxides and DME in the
within each of the three structures (Table 1), indicating con- base. It is thus very similar to the structures of
siderable distortion from tetrahedral stereochemistry. The [Ln(OArH)3(DME)] (Ln ϭ Yb or Nd).[4d] Thus, the 3,5-
sum of the OArRϪLnϪOArR angles in all three structures substituents do not affect the coordination number in con-
(Table 2) approaches 360°, whereas the sums of the trast to complexation with THF (above). This is because a
O(THF)ϪLnϪOArR angles are below the 328.5° expected chelating DME has less steric demand than two THF li-
for tetrahedral angles. Thus, the data suggest that four coor- gands.[3a]
dination in the three structures can be considered near tri-
Since the ArPhOϪYbϪOArPh angles (Table 3) lie close to
angular pyramidal. The LnϪOϪC angles in the three struc-
tetrahedral values (cf. Σ ArORϪYbϪOArR, Table 2), there
tures are appreciably nonlinear (Table 2) and are compar-
is an approximately tetrahedral array of aryloxide oxygens
able with the average (156.7°) found for the more crowded
and the centre of the O···O vector of the DME. The cisoid
[Yb(OC6H2tBu3-2,4,6)3(THF)].[2g] The deviation of the rare
aryloxide angle in the square plane [O(21)ϪYbϪO(31)
109.0(3)°] is surprisingly smaller than the corresponding cis-
earth ions from the LnO3 (aryloxide) plane (Table 2) is mar-
˚
ginally more than 0.392(1) A for [Yb(OC6H2tBu2-2,6-Me-
oid angles in [Ln(OArH)(DME)] [Ln ϭ Nd (120.3(2) and
4)3(THF)].[2g]
Yb (113.3(2)°].[4d] Although the O(DME)ϪYbϪO(DME)
and the YbϪO(n1)ϪC(n1) (n ϭ 1 and 2) angles are similar
The Complex [Yb(OArPh)3(DME)]·1.5THF
in the two complexes (R
ϭ
H[4d] or Ph), the
This complex has a five-coordinate array of three arylox- YbϪO(31)ϪC(31) angle in [Yb(OArPh)3(DME)]·1.5THF is
ide and two DME oxygens (Figure 3). The best fit[15] poly- 23.4° [Yb(OArH)3-
greater (Table 3) than in
hedron is a square pyramid (though very distorted) with (DME)]·0.5DME.[4d] Thus, the bond angles present no
1508
Eur. J. Inorg. Chem. 2001, 1505Ϫ1514

Rare Earth Complexes of Bulky 2,6-Diphenylphenolates
FULL PAPER
Figure 4. Molecular projection of [Yb(OArMe)2(THF)3]
Figure 3. Molecular projection of [Yb(OArPh)3(DME)]
Table
4.
Ytterbium
environment,
[Yb(OArMe)2(THF)3];
O(31)ϪO(51) are derivatives of the THF ligands
Table 3. Ytterbium environment, [Yb(OArPh)3(DME)]; O(2,5)
from DME[a]
Atom
r
O(21)
O(31)
O(41)
O(51)
Atom
r
O(21)
O(31)
O(2)
O(5)
O(11)
O(21)
O(31)
O(41)
O(51)
C(126)
2.218(6)
2.202(6)
2.397(6)
2.426(6)
2.436(7)
3.177(9)
140.9(2)
95.8(2)
100.7(2)
100.7(2)
117.1(2)
78.7(2)
91.1(2)
87.6(2)
156.7(3)
78.1(3)
O(11)
O(21)
O(31)
O(2)
2.038(7)
2.048(7)
2.043(8)
2.379(9)
2.349(9)
101.8(3)
108.8(3)
109.0(3)
97.3(3)
84.1(3)
146.9(3)
111.2(3)
137.4(3)
85.3(3)
66.1(3)
O(5)
[a]
Torsions in the DME ring (only bonds specified): YbϪO(2,5)
5.6(9), 22(1); O(2)ϪC(3) Ϫ28(1); O(5)ϪC(4) Ϫ48(2); C(3)ϪC(4)
48(2); O(5)ϪYbϪO(2)ϪC(1) 161(1); O(2)ϪYbϪO(5)ϪC(6)
Ϫ147(1)°.
O(11)ϪYbϪO(21) angle without postulation of an Yb···H
interaction. Certainly, the large angle cannot be explained
by repulsion between the bulky aryloxide ligands as cisoid
ArROϪYbϪOArR angles are well established, for example
clear picture as to the effect of 3,5-disubstitution on DME
complexation. The ϽYbϪOArϾ and ϽYbϪO(DME)Ͼ
distances of [Yb(OArPh)3(DME)]·1.5THF correspond
closely to those of [Yb(OArH)3(DME)]·0.5DME (0.02, 0.03
in
[Yb(OArH)2(THF)3] is also distorted trigonal bipyramidal,
the aryloxide ligands are apical [ArHOϪYbϪOArH
164.6(3)°] with highly distorted angles between the equator-
ial THF ligands [OϪYbϪO 83.7(4), 138.8(3),
[Yb(OArPh)3(DME)]
(Table 3).
Although
ϭ
[4d]
˚
A difference).
ϭ
The Complex [Yb(OArMe)2(THF)3]
137.5(3)°].[4d] In this case, aryl hydrogens intrude into both
There is a five coordinate YbII centre in [Yb(O- of the large O(THF)ϪYbϪO(THF) angles, though at
ArMe)2(THF)3] (Figure 4), and the best fit polyhedron[15] of greater distances [Yb···H ϭ 3.1, 3.2 A; nearest associated C
˚
the donor atoms is a trigonal bipyramid with the THF oxy- at 3.45(1) A] than for [Yb(OArMe)2(THF)3].
˚
˚
gens O(31) and O(51) apical and the aryloxide oxygens and
O(41) (THF) equatorial. The stereochemistry is severely with those (2.21Ϫ2.22 A) of [Yb(OAr )2(THF)3]
The average YbϪOAr distance (2.21 A) is in agreement
H
[4d]
˚
and
distorted with a 156.7(3)° angle between the axial donors square pyramidal [Yb(OC6H2tBu2-2,6-X-4)2(THF)3]. THF
and considerable variation [100.7(2)Ϫ140.9(2)°] (Table 4) in (X ϭ Me, tBu).[2e,2f] Whilst ϽYbϪO(THF)Ͼ (2.42 A)
˚
the equatorial angles, though their sum is 358.7°.
agrees with that of [Yb(OArH)2(THF)3],[4d] it is shorter than
˚
There is also a close approach of a carbon atom those (2.48, 2.46 A) of the two 2,6-di-tert-butylphenolate
[Yb···C(126) ϭ 3.177(9) A] adjudged just on or outside the complexes.[2e,2f] Subtraction of the ionic radius for five co-
˚
limit for meaningful binding. If viewed as six coordinate, ordinate Yb2ϩ gives 1.46 A, rather lower than the usual
˚
subtraction of the appropriate Yb2ϩ ionic radius[12] from range 1.48Ϫ1.60 A for THF in bulky aryloxide complexes
˚
the Yb···C distance gives 2.16 A, which is the upper limit of YbII/YbIII [2f,2g,4a,4d]
.
(It would be even lower if YbII were
˚
for significant intramolecular π-C(Ph)···Ln interactions,[16] to be taken as six coordinate). Despite the similarity in
whereas subtraction of the extrapolated five coordinate ϽYbϪO(THF)Ͼ values between [Yb(OArR)2(THF)3] (R ϭ
radius gives 2.22 A, beyond the range. The calculated H[4d] or Me) derivatives, the present complex shows a much
˚
˚
˚
position of H(126) is even closer to Yb [2.9(est.) A] and smaller range of lengths (0.039 A) than the earlier complex
intrudes into and can explain the large [140.9(2)°] (0.15 A).[4d] The YbϪOArRϪC angles are similar in the two
˚
Eur. J. Inorg. Chem. 2001, 1505Ϫ1514
1509

G. B. Deacon, P. E. Fanwick, A. Gitlits, I. P. Rothwell, B. W. Skelton, A. H. White
FULL PAPER
structures (Table 2 and ref.[4d]) despite the different arrange- coordinate Sc3ϩ radius from Sc···C(122) gives values within
1
˚
ment of ligands.
the 2.16 A limit. With two π-η -Ph···Sc interactions, the
capping phenyls have a different coordination mode than in
[Ln(OArH)3] (Ln ϭ Ce, Pr, Nd, Y, Yb, Lu) (η6 ϩ η1)[4a,4c,5b]
or [La(OArH)3] (η6 ϩ η3),[5b] attributable to the small size
[Sc(OAr)3]
Single crystals of homoleptic [Yb(OArPh)3] could not be
obtained and hence the effect of 3,5-disubstitution on the
structure of homoleptic lanthanoid 2,6-diphenylphenolates
could not be determined. However, the complex
[Sc(OArH)3] has been shown to be monomeric (Figure 5),
with the coordination sphere comprising a triangular array
of phenolate oxygens and capping π-η1-Ph···Sc interactions
above and below the ScO3 plane (see below). Unlike [Ce-
(OC6H3tBu2-2,6)3][2b] and [Ln(OArH)3] (Ln ϭ Y, La, Ce,
Nd, Pr, Yb, Lu)[4a,4c,5b] complexes, in which the LnO3 units
are distorted from triangular planar towards trigonal pyr-
amidal, [Sc(OArH)3] is triangular planar (OϪScϪO devi-
ation from 120°: Յ 2.3°; Σ OϪScϪO 360°) with minimal
deviation of Sc from the O3 plane (Table 2), much like
of Sc3ϩ [12]
The similar Sc···C binding modes and bond
lengths transoid to the O3 plane probably account for the
.
triangular ScO3 arrangement and minimal deviation
[0.011(9) A] of Sc from the O3 plane {cf. [Ln(OArH)3]:
˚
0.150(1)Ϫ0.353(1) A (LaϪLu)}.[4a,4c,5b] Although the trans-
˚
oid C(122)ϪScϪC(222) angle [145.2(8)°] deviates consider-
ably from linear, the ring centroids are nearer linear
[C(120)ϪScϪC(220) ϭ 165.7°]), although still less than the
range 173.2Ϫ177.2° for the other structurally characterised
[Ln(OArH)3] complexes.[4a,4c,5b] The inclinations of the cap-
ping phenyl rings 12n and 22n to the ScO3 plane [30.8(8)°,
28.9(8)° Table 5] are similar to those [28.1(2)Ϫ30.1°] of the
π-η1-Ph···Ln bonded rings of [Ln(OArH)3] (Ln ϭ Ce, Pr,
Nd, Yb, Lu).[4a,4c,5b] On the other hand, the rings are in-
clined to each other at 59.2(6)°, quite different from the
dihedral angle of the η6 and η3 rings of [La(OArH)3]
[19.9(3)°] or of the η6 and η1 rings of [Lu(OArH)3]
[38.8(3)°].[5b]
[Ln(OC6H2tBu2-2,6-Me-4)3] (Ln
ϭ
Sc, Y).[2a,2c] The
˚
ϽScϪOϾ distance is 1.93 A and is somewhat longer than
that of [Sc(OC6H2tBu2-2,6-Me-4)3][2a] (1.87 A), presumably
˚
owing to the higher coordination number of Sc in
[Sc(OArH)3] due to the C···Sc interactions.
Table 5. Scandium environment, [Sc(OArH)3]
Atom
r
O(21)
O(31)
C(122)
C(222)
O(11)
O(21)
O(31)
C(122)
C(222)
1.92(2)
1.97(2)
122.1(7)
117.7(7)
120.2(7)
77.8(8)
84.7(8)
107.2(9)
86.0(8)
78.2(8)
107.5(9)
145.2(8)
1.91(1)
2.62(3)[a]
2.68(3)[a]
[a]
Next closest Sc···C contacts: Sc···C(121, 123; 221, 223) are
˚
3.12(3), 3.08(3); 3.12(3), 3.19(3) A. Planes 12n, 22n lie at 30.8(8),
28.9(8) to the O3 plane and 59.2(6)° to each other; Sc lies 2.56(2)
˚
and 2.63(2) A out of them.
Further examination of the [Sc(OArH)3] structure shows
that the ScϪO(11)ϪC(11) and ScϪO(21)ϪC(21) angles (li-
gands 1 and 2) are much smaller than 180° while
ScϪO(31)ϪC(31) is nearly linear (Table 2). Furthermore,
the dihedral angles (Table 2) between the C6 central
(phenolate) plane and the O3 plane (θc/O3) are 83.6(8) and
79.4(8)° for ligands 1 and 2 respectively, whilst only 33.4(7)°
for ligand 3 (Table 2). Moreover, the angles between the
central C6 ring and the phenyl substituent planes of ligands
1 and 2 average 57.8 and 55.8°, whilst the average value for
ligand 3 is 44.4°. The interplanar angles between the 2- and
6-phenyl rings for ligands 1 and 2 also differ from that of
ligand 3 (Table 2). These data, in conjunction with the sub-
stantial bending of the ScϪOϪC angles of ligands 1 and 2,
demonstrate the deviation of ligands 1 and 2 towards Sc
associated with binding of their phenyl substituents.
Figure 5. Molecular projection of [Sc(OArH)3]
The phenyl rings 12n and 22n approach the ScO3 plane
from above and below such that C(122) and C(222) are
closer to Sc than the next nearest C atoms of the rings by
˚
ca. 0.45 A (Table 5). The Sc···C(122) and Sc···C(222) dis-
tances (Table 5) are not greatly lengthened from the π-η1-
[17]
˚
CpϪSc bridging bonds [2.629(4), 2.519(4) A] of [ScCp3]n,
for which the next closest contacts from the η1-bonded
˚
rings are more distant by ca. 0.4Ϫ0.6 A. Subtraction of an
extrapolated (from data of ref.[12]) radius (0.68 A) for five
˚
coordinate Sc3ϩ from Sc···C of [Sc(OArH)3] gives 1.94 and
˚
˚
2.00 A, well within the upper limit (2.16 A) for significant
intramolecular π-Ph···Ln interactions.[16] Accordingly,
C(122) and C(222) are considered to be weakly bound to
Conclusions
The reduction in coordination number from five in
Sc by π-η1-Ph···Sc interactions. Even subtraction of a three [Yb(OArH)3(THF)2][4a] to four in [Yb(OArR)3(THF)] (R ϭ
1510
Eur. J. Inorg. Chem. 2001, 1505Ϫ1514

Rare Earth Complexes of Bulky 2,6-Diphenylphenolates
FULL PAPER
C82H95O4Yb [Yb(OArtBu)3(THF)] (1317.62): calcd. C 74.74, H
7.27, Yb 13.13. Ϫ C86H103O5Yb (title compound) (1389.72): calcd.
C 74.32, H 7.47, Yb 12.45; found C 73.36, H 7.44, Yb 11.33.
tBu or Me) (see Figure 2) indicates that the addition of 3,5-
substituents to the 2,6-diphenylphenolate ligand is consist-
ent with an increase in ligand bulk, possibly by buttressing
the phenyl groups. This reduction in coordination number
is foreshadowed by the anomalous ‘‘4.5 coordination’’ in
Tris(2,6-diphenyl-3,5-dimethylphenolato)(tetrahydrofuran)ytterbium-
(III):
A mixture of 2,6-diphenyl-3,5-dimethylphenol (0.82 g,
[Ln(OArH)3(THF)2] (Ln ϭ La and Nd).[4b,4c] In contrast, 3.00 mmol), bis(pentafluorophenyl)mercury(II) (0.80 g, 1.50 mmol)
and ytterbium chips (0.52 g, 3.01 mmol) was stirred in THF
(60 mL) at ambient temperature for 21 h. Filtration gave a bright
yellow solution, which was partially evaporated and a small volume
of hexane (10 mL) added. Large yellow crystals formed which were
used for X-ray structure determination. The solution was then fur-
ther reduced in volume producing more crystalline material which
was dried under vacuum at room temperature (combined yield
0.43 g, 40%). Ϫ M.p. (sealed tube/N2): 228Ϫ231 °C, prelim. dec.
80Ϫ90 °C. Ϫ IR: ν˜ ϭ 1598m, 1572w, 1554m, 1323s, 1169w, 1152w,
1089s, 1067m, 1027m, 1009m, 967m, 912w, 862m, 836m, 785w,
similar five coordinate structures are observed in
[Yb(OArR)3(DME)] [R ϭ H[4d] or Ph (Figure 3)]. In five
coordinate [Yb(OArR)2(THF)3], there is a change from ap-
ical aryloxides (R ϭ H)[4d] to (surprisingly) apical THF li-
gands (R ϭ Me) (Figure 4) in their distorted trigonal bipyr-
amidal stereochemistry. In homoleptic [Sc(OArH)3], the co-
ordination motif, ScO3 ϩ two π-η1-Ph···Sc interactions, is
new and differs from the ligation in other [Ln(OArH)3] com-
plexes.[4a][4c][5b]
749s, 704s, 664s cmϪ1. Ϫ Vis/near IR (THF): λmax (ε) ϭ 372 (364),
Ϫ1
911 (14), 980 (50) nm (dm3 mol
cmϪ1). Ϫ MS (70 eV, EI): m/z
(%) ϭ 994 (37) [Yb(OArMe
) ) Ϫ
ϩ H]ϩ, 979 (2) [Yb(OArMe
3
3
Experimental Section
CH2]ϩ, 720 (100) [Yb(OArMe)2]ϩ, 705 (2) [Yb(OArMe
)
Ϫ Me]ϩ,
2
447 (18) [Yb(OArMe)]ϩ, 428 (2) [Yb(OArMe) Ϫ MeH Ϫ 3H]ϩ, 371
General: Rare earth aryloxides are extremely air- and water-sensit-
ive hence all operations were carried out under an inert atmosphere
(purified Ar or N2). Handling methods, analytical procedures, and
solvent purifications were generally as described previously,[5b,18]
with the exception of some infra red spectra and the 1H NMR
spectrum of [Yb(OArMe)2(THF)3] which were recorded using a
PerkinϪElmer Spectrum 2000 FTIR and a Varian Associates Gem-
ini-200 spectrometer, respectively. IR data (4000Ϫ650 cmϪ1) are for
compounds as Nujol mulls. 1H chemical shifts are referenced to
internal solvent resonances and reported relative to SiMe4. In as-
(3) [Yb(OArMe
) Ϫ
C6H4]ϩ, 274 (28) [ArOMeH]ϩ, 273 (35)
[ArOMe]ϩ. Ϫ C64H59O4Yb (1065.15): calcd. C 72.16, H 5.58, Yb
16.25; found C 70.08, H 5.67, Yb 15.64.
Tris(2,6-diphenyl-3,5-di-tert-butylphenolato)(tetrahydrofuran)-
scandium(III) -Tetrahydrofuran (1/1): A mixture of 2,6-diphenyl-
3,5-di-tert-butylphenol (1.08 g, 3.01 mmol), bis(pentafluorophen-
yl)mercury(II) (0.80 g, 1.50 mmol), small scandium chunks
(0.36 g, 8.01 mmol) and mercury (2 drops) in THF (50 mL) was
ultrasonicated at ambient temperature for 227 h. The reaction mix-
ture was filtered through a Celite pad, giving a clear very pale yel-
low solution which was evaporated to 10 mL. Small colourless crys-
tals appeared in a few hours, and these were used for X-ray crystal-
lography. Bulk crystalline solid deposited from the decanted mother
liquor on further standing, and was dried under vacuum at room
temperature. More solid crystallised from the filtrate and was sim-
ilarly treated (combined yield 0.57 g, 45%). Ϫ M.p. (sealed tube/
1
signments of H NMR spectra involving the OArH ligand, primed
numbers refer to phenyl protons. In the mass spectra, each listed
m/z value for metal-containing ions (where the metal has more than
one isotope) is the most intense peak of a cluster with an isotope
pattern in good agreement with the calculated pattern. Those com-
plexes containing OArR (R ϭ tBu, Ph) ligands for which data are
not reported did not display any metal-containing ions in their
mass spectra. Microanalyses were either by the Campbell Microan-
alytical Service, University of Otago, New Zealand or by Microan-
alytical services, Department of Chemistry at Purdue University,
Indiana, USA. Complexes with THF or DME lose solvent on be-
ing heated in sealed capillaries under N2 hence melting points have
little significance (see examples below). 2,6-Diphenylphenol was
purchased from Aldrich, while HOArR reagents were prepared by
previously reported procedures (R ϭ Me,[6b,19] tBu,[20] Ph[21]). Rare
earth metals were obtained as powders or chunks from
˜ ϭ 1597m,
N2): 203Ϫ205 °C (dec.), prelim. dec. ca. 150 °C Ϫ IR: ν
1576m, 1522m, 1288s, 1238m, 1200m, 1171m, 1070m, 1027m,
1012s, 998s, 912m, 870m, 819w 780w, 761m, 708s, 658s cmϪ1. Ϫ
1H NMR (C6D6): δ ϭ 1.28 (s, 54 H, tBu), 1.41 [br s, 8 H, β-
H(THF)], 3.56 [br s, 8 H, α-H(thf)], 6.88Ϫ7.58 (m, 33 H, ArH). Ϫ
MS (70 eV, EI): m/z (%) ϭ 759 (1) [Sc(OArtBu)2]ϩ, 743 (3)
[Sc(OArtBu)2 Ϫ MeH]ϩ, 727 (1) [Sc(OArtBu)2 Ϫ 2MeH]ϩ, 711 (Ͻ1)
[Sc(OArtBu)2 Ϫ 3MeH]ϩ, 671 (Ͻ1) [Sc(OArtBu)2 Ϫ MeH Ϫ Me Ϫ
Bu]ϩ, 655 (Ͻ1) [Sc(OArtBu
)
Ϫ 2 MeH Ϫ Me Ϫ Bu]ϩ, 641 (Ͻ1)
2
[Sc(OArtBu
)
2
Ϫ 3Me Ϫ MeH Ϫ Bu]ϩ, 358 (55) [ArtBuOH]ϩ, 57
ˆ
RhoneϪPoulenc, Phoenix, USA.
(100) [Bu]ϩ. Ϫ C86H103O5Sc, (1262.64): calcd. C 81.87, H 8.23, Sc
Tris(2,6-diphenyl-3,5-di-tert-butylphenolato)tetrahydro-
furanytterbium(III)-Tetrahydrofuran (1/1): A 100 mL Schlenk flask
was charged with ytterbium powder (0.52 g, 3.01 mmol), bis-
(pentafluorophenyl)mercury(II) (1.07 g, 2.00 mmol), 2,6-diphenyl-
3.56; found C 80.89, H 8.26, Sc 4.13.
Tris(2,3,5,6-tetraphenylphenolato)bis(tetrahydrofuran)samarium-
(III): A mixture of 2,3,5,6-tetraphenylphenol, (1.32 g, 3.31 mmol),
3,5-di-tert-butylphenol (1.43 g, 3.99 mmol) and THF (50 mL). The bis(pentafluorophenyl)mercury(II) (0.89 g, 1.66 mmol) and samar-
reaction mixture was stirred for 10 h at 80 °C yielding a dark red-
brown solution upon filtration. The volume of the solution was
reduced to 15 mL and yellow prismatic single crystals formed over-
night which were used for X-ray crystal structure determination.
ium powder (1.00 g, 6.65 mmol) was stirred in THF (40 mL) at
room temperature for 29 h. Filtration gave a pale yellow solution
which was evaporated to 10 mL. Pale yellow crystals formed in a
few hours. The solid was dried under vacuum at 80 °C for 1 h
More yellow crystals formed on storing the saturated solution at giving a colourless-pale yellow powder (0.89 g, 54%). Ϫ IR: ν˜ ϭ
ambient temperature for several days. These were dried under vac-
uum at room temperature (0.75 g, 40%). Ϫ IR: ν˜ ϭ 1597w, 1576w,
1597m, 1577w, 1531w, 1341s, 1307s, 1274m, 1138s, 1068m, 1025m,
1010m, 946s, 908w, 859w, 792w, 757s, 698s, 668s cmϪ1. Ϫ 1H NMR
1525w, 1296s, 1239w, 1171w, 1069m, 1027m, 1011m, 998s, 851w, (C7D8): δ ϭ Ϫ0.05 [br s, 8 H, β-H(THF)], 0.85 [br s, 8 H, α-
818w, 780w, 760m, 707s cmϪ1. Ϫ Vis/near IR (THF): λmax (ε) ϭ H(THF)], 6.26Ϫ7.61 (complex m, 63 H, ArH). Ϫ C94H71O4Sm
395 (52), 758 (25), 912 (3), 979 (10) nm (dm3 molϪ1 cmϪ1). Ϫ [Sm(OArPh)3(THF)] (1414.91): C 79.79, H 5.05, Sm 10.63. Ϫ
Eur. J. Inorg. Chem. 2001, 1505Ϫ1514
1511

G. B. Deacon, P. E. Fanwick, A. Gitlits, I. P. Rothwell, B. W. Skelton, A. H. White
C98H79O5Sm (1487.01): calcd. C 79.15, H 5.36, Sm 10.11; found C 1531w, 1513w, 1347s, 1307m, 1276m, 1140m, 1070w, 1027w, 1010w,
FULL PAPER
78.32, H 5.44, Sm 10.02.
949m, 908w, 873, 863, and 855vw, 800w, 775w, 758s, 722m, 698s,
672m cmϪ1. Ϫ Vis/near IR (THF): λmax (ε) ϭ 348 (1634), 913 (8),
980 (40) nm (dm3 molϪ1 cmϪ1). Ϫ C90H63O3Yb (1365.44): calcd.
C 79.16, H 4.65, Yb 12.67; found C 79.51, H 4.89, Yb 12.12.
Adventitious Synthesis of Tris(2,3,5,6-tetraphenylphenolato)(1,2-di-
methoxyethane)ytterbium(III):
A
mixture of 2,3,5,6-tetrap-
henylphenol, (1.59 g, 3.99 mmol), bis(pentafluorophenyl)mercur-
y(II) (1.07 g, 2.00 mmol) and ytterbium powder (0.35 g, 2.02 mmol)
was stirred in THF (50 mL) at 80 °C for 5 h. Filtration gave a dark
red-brown solution which was evaporated to 20 mL and kept at
Ϫ20 °C for 2 h. A very fine yellow crystalline solid, and later or-
ange-yellow powder formed. This was dissolved in a minimal vol-
ume of hot toluene which was contaminated with a substantial
amount of 1,2-dimethoxyethane. Meanwhile more crude product
was obtained from the original THF solution. This was dissolved
in hot toluene and the two toluene solutions were combined and
left to stand at room temperature for several days resulting in initial
formation of a large yellow crystal, which was cut in three and used
Tris(2,6-diphenylphenolato)scandium(III): A mixture of scandium
chips (0.36 g, 8.01 mmol) and 2,6-diphenylphenol (0.99 g,
4.02 mmol) was heated in the presence of mercury (2 drops) in a
sealed Carius tube at 200Ϫ250 °C for 160 h. The reaction mixture
was worked up in toluene (70 mL) and filtered while hot giving a
colourless solution, which was evaporated to 5 mL. Some colour-
less single crystals formed overnight which were used for an X-ray
crystal structure determination. Further standing gave a colourless
microcrystalline solid which was isolated and dried at 80 °C for 1 h
(0.44 g, 42%). Ϫ M.p. Ͼ220 °C. Ϫ IR: ν˜ ϭ 1579m, 1411s, 1307m,
1282s, 1248s, 1172m, 1162w, 1154w, 1112w, 1094w, 1068m, 1026w,
1010w, 990w, 970w, 890s, 867s, 804w, 763s, 702s, 634s, 610s cmϪ1
.
for
X-ray
crystal
structure
identification
as
[Yb(OArPh)3(DME)]·1.5THF, and then bulk yellow microcrystal-
line product which was dried under vacuum at 80 °C for 1 h. More
microcrystalline yellow product deposited from the filtrate, and was
collected and dried as before {combined yield 0.31 g, 16% for
[Yb(OArPh)3(DME)]}. Ϫ IR: ν˜ ϭ 1597m, 1578w, 1530m, 1345s,
1306m, 1275m, 1142s, 1091w, 1071w, 1044m, 1001w, 994w, 952s,
908w, 870w, 846w, 793w, 758s, 698s, 871s cmϪ1. Ϫ Vis/near IR
(THF): λmax (ε) ϭ 399 (161), 912 (7), 980 (43) nm (dm3 molϪ1
cmϪ1). Ϫ C100H85O6.5Yb ([Yb(OArPh)3(DME)]·1.5THF] (1563.72):
calcd. C 76.80, H 5.48, Yb 11.07. Ϫ C94H73O5Yb (THF-free)
(1455.56): calcd. C 77.56, H 5.06, Yb 11.89; found C 78.72, H 5.44,
Yb 11.43.
Ϫ 1H NMR (C6D6): δ ϭ 6.86Ϫ6.96 (m, 21 H, H4, H3Ј, H4Ј, H5Ј),
3
3
7.19 (d, JH-H ϭ 7.5 Hz, 6 H, H3, H5), 7.31 (dd, JH-H ϭ 7.0 Hz,
4JH-H ϭ 1.4 Hz, 12 H, H2Ј, H6Ј). Ϫ MS (70 eV, EI): m/z (%) ϭ
535 (21) [Sc(OArH)2]ϩ, 246 (100) [HOArH]ϩ. Ϫ C54H39O3Sc
(780.81): calcd. C 83.06, H 5.03, Sc 5.76; found C 82.88, H 5.19,
Sc 5.65.
Tris(2,6-diphenylphenolato)(tetrahydrofuran)scandium(III): Tris(2,6-
diphenylphenolato)scandium was prepared as above and on the
same scale, but THF (90 mL) was used rather than toluene to work
up the reaction mixture. Filtration gave a colourless solution, which
was evaporated to 2 mL, but no solid formed. THF was then re-
moved completely leaving a white solid. Crystallisation from tolu-
ene (20 mL) gave a white microcrystalline solid, which was dried
under vacuum at 150 °C for 1 h (0.72 g, 63%). Ϫ M.p. (sealed tube/
N2): 218Ϫ220 °C, prelim. dec. ca. 170 °C. Ϫ IR: ν˜ ϭ 1595m,
1580m, 1410s, 1308m, 1281m, 1258s, 1172w, 1157w, 1085w, 1070m,
1025w, 1004w, 972w, 957w, 884s, 859s, 804w, 769m, 733m, 704s,
635s cmϪ1. Ϫ 1H NMR (C6D6): δ ϭ 0.57 [s, 4 H, β-H(THF)], 2.12
[s, 4 H, α-H(THF)], 6.84Ϫ7.04 (m, 21 H, H4, H3Ј, H4Ј, H5Ј), 7.23
Bis(2,6-diphenyl-3,5-dimethylphenolato)tris(tetrahydrofuran)-
ytterbium(II):
A
mixture of 2,6-diphenyl-3,5-dimethylphenol
(1.10 g, 4.01 mmol), diphenylmercury(II) (0.71 g, 2.00 mmol), yt-
terbium chips (0.69 g, 3.99 mmol) and mercury (2 drops) was
stirred in THF at 50 °C for 29 h. Filtration gave a dark red-brown
solution, which was evaporated to 5 mL and layered with hexane
yielding a dark red crystalline product from which single crystals
for X-ray structure determination were derived. The remaining
bulk crystalline material was dried under vacuum at ambient tem-
perature (0.83 g, 44%). Ϫ IR: ν˜ ϭ 1598m, 1551m, 1325s, 1296s,
1239w, 1153w, 1089s, 1068s, 966w, 916m, 879w, 788w, 750m, 704s
cmϪ1. Ϫ Vis/near IR (THF): no absorptions occurred near
3
3
4
(d, JH-H ϭ 7.5 Hz, 6 H, H3, H5), 7.34 (dd, JH-H ϭ 7.5 Hz, JH-
ϭ 1.4 Hz, 12 H, H2Ј, H6Ј). Ϫ C58H47O4Sc, (852.92): calcd. C
H
81.67, H 5.55, Sc 5.27; found C 81.57, H 5.84, Sc 5.29.
Attempted Preparation of Tris(2,3,5,6-tetraphenylphenolato)(1,2-di-
1
methoxyethane)ytterbium(III):
A
mixture of 2,3,5,6-tetra-
1000 nm. Ϫ H NMR (C6D6): δ ϭ 0.90 (s, 6 H, CH3), 1.25 (s, 6 H,
phenylphenol, (2.17 g, 5.45 mmol), bis(pentafluorophenyl)mercur-
y(II) (1.46 g, 2.73 mmol) and ytterbium powder (0.63 g, 3.64 mmol)
was stirred in DME (50 mL) at room temperature for 5 h. The reac-
tion mixture turned brown-orange and was stirred for a further
24 h at 70 °C. Filtration gave a dark brown solution which was
reduced in volume. Yellow needle-like crystals formed overnight
and were dried under vacuum at room temperature (0.65 g, 23%
for [Yb(OArPh)3(DME)]·DME). Ϫ IR: ν˜ ϭ 1597m, 1578w, 1531m,
1346s, 1306s, 1275m, 1143s, 1110m, 1072m, 1043m, 1025m, 952s,
917w, 869w, 840w, 794w, 758s, 699s, 672s cmϪ1. Ϫ Vis/near IR
(THF): λmax (ε) ϭ 410 (197), 912 (2), 980 (38) nm (dm3 molϪ1
cmϪ1). Ϫ C94H73O5Yb [Yb(OArPh)3(DME)] (1299.56): calcd. C
77.56, H 5.06, Yb 11.89; Ϫ C98H83O7Yb [Yb(OArPh)3(DME)2]
(1545.68): calcd. C 76.14, H 5.41, Yb 11.19; found C 72.51, H 5.43,
Yb 11.20.
CH3), 2.04 [br s, 24 H, CH2 (THF)], 6.63Ϫ7.08 (m, 22 H, ArH).
Integrations are approximate owing to the broadness of the THF
peak, the complexity and underlying broadness of the aromatic res-
onances, and the proximity of strong solvent absorptions to the
aromatic resonances. Ϫ MS (70 eV, EI): m/z (%) ϭ 720 (13)
[Yb(OArMe)2]ϩ, 447 (3) [Yb(OArMe)]ϩ, 274 (100) [ArOMeH]ϩ. Ad-
ditional clusters centred on m/z ϭ 795, 748, and 733 of very low
intensity (Ͻ1%) did not have a recognizable isotope pattern and
could not be assigned. Ϫ C52H58O5Yb (936.02): calcd. C 66.72, H
6.25, Yb 18.49; found C 66.38, H 6.02, Yb 18.70.
Tris(2,3,5,6-tetraphenylphenolato)ytterbium(III): A mixture of yt-
terbium chips (0.52 g, 3.01 mmol) and 2,3,5,6-tetraphenylphenol
(0.60 g, 1.51 mmol) was heated at 200 °C in the presence of mer-
cury (2 drops) in a sealed tube under vacuum for 24 h. The reaction
mixture was extracted in hot toluene (70 mL) and filtered giving
an orange solution. The volume of the solution was reduced to Structure Determinations: Full spheres of CCD area-detector data
2 mL and pentane was layered on top. A microcrystalline yellow were measured at the specified temperature (Bruker AXS instru-
solid formed overnight. This was isolated, washed with hexane ment; 2θmax as specified; monochromatic Mo-Kα radiation, λ ϭ
˚
(2 mL) and dried at 60 °C under vacuum (0.52 g, 76%). Ϫ M.p. 0.71073 A) yielding Nt(otal) reflections, reducing to N unique (Rint
˜ ϭ 1597w, 1581w, 1574w, quoted) after ‘‘empirical’’/multiscan absorption correction
(sealed tube/N2): 282Ϫ285 °C. Ϫ IR: ν
1512
Eur. J. Inorg. Chem. 2001, 1505Ϫ1514

Rare Earth Complexes of Bulky 2,6-Diphenylphenolates
FULL PAPER
3
V ϭ 3970 A . Dc ϭ 1.306 g cmϪ3. µMo ϭ 2.3 cmϪ1; specimen: 0.25
ϫ 0.15 ϫ 0.03 mm; ЈTЈmin.,max ϭ 0.59, 0.88. 2θmax ϭ 50°; Nt ϭ
19251, N ϭ 6895 (Rint ϭ 0.21), No ϭ 1394; R ϭ 0.088, Rw ϭ 0.097.
˚
(proprietary software), No with F Ͼ 4σ(F) being considered ‘‘ob-
served’’ and used in the full-matrix least-squares refinement (aniso-
tropic thermal parameter forms for the non-hydrogen atoms; (x, y,
z, Uiso H
constrained at estimated values). Conventional residuals |∆ρmax| ϭ 0.86(6) e AϪ3. T ca. 153 K. Weak and limited data from
˚
)
R, Rw (weights: [σ2(F) ϩ 0.0004 F2)Ϫ1] are quoted on |F| at conver-
a very fragile leaf-like specimen would support meaningful aniso-
gence. Neutral atom complex scattering factors were employed
within the context of the Xtal 3.4 program system.[22] Pertinent
results are given in the figures and tables. In the figures 20% dis-
placement amplitudes are shown for the structures determined at
low temperature, 50% for room temperature. Hydrogen atoms have
tropic thermal parameter form refinement for Sc only, isotropic
forms for C, O.
Crystallographic data (excluding structure factors) for the struc-
tures reported in this paper have been deposited with the Cam-
bridge Crystallographic Data Centre. The supplementary publica-
tion nos. CCDC-153631, -153627, -153628, -153629, -153626,
-153630 apply sequentially to the compounds in the Crystal/Refine-
ment Data section. Copies of the data can be obtained free of
charge on application to CCDC 12 Union Road, Cambridge
CB2 1EZ, UK [Fax: (internat.) ϩ44-1223/336-033; E-mail:
deposit@ccdc.cam.ac.uk].
˚
arbitrary radii of 0.1 A. Individual variations in procedure, idiosyn-
crasies, difficulties are noted below.
Crystal/Refinement Data
[Yb(OArtBu)3(THF)]·THF: C86H103O5Yb, M ϭ 1389.8. Triclinic,
1
¯
space group P1 (Ci , no. 2), a ϭ 14.930(1), b ϭ 16.601(1), c ϭ
˚
17.281(1) A, α ϭ 110.491(1)°, β ϭ 99.703(1)°, γ ϭ 104.169(1)°, V ϭ
3735 A . Dc (Z ϭ 2) ϭ 1.236 g cmϪ3. µMo ϭ 13.0 cmϪ1; specimen:
3
˚
0.55 ϫ 0.40 ϫ 0.15 mm; ЈTЈmin.,max ϭ 0.61, 0.83. 2θmax ϭ 58°; Nt ϭ
Acknowledgments
43419, N ϭ 18211 (Rint ϭ 0.029), No ϭ 12973; R ϭ 0.038, Rw
ϭ
0.039. |∆ρmax| ϭ 1.37(9) e AϪ3. T ca. 300 K. Displacement para-
meters of the lattice solvent were very large; site occupancy was set
at unity after trial refinement.
˚
We are grateful to the Australian Research Council for support and
for an Australian Postgraduate Award and a Monash University
travel grant to A. G.; I. P. R. acknowledges the National Science
Foundation for financial support of this research.
[Sc(OArtBu)3(THF)]·THF: C86H103O5Sc, M ϭ 1261.7. Triclinic,
˚
3
¯
space group P1, a ϭ 14.805(2), b ϭ 16.208(2), c ϭ 17.042(2) A,
˚
α ϭ 109.649(2)°, β ϭ 99.719(2)°, γ ϭ 103.981(2)°, V ϭ 3595 A .
Dc (Z ϭ 2) ϭ 1.166 g cmϪ3. µMo ϭ 1.5 cmϪ1; specimen: 0.25 ϫ
0.20 ϫ 0.04 mm; ЈTЈmin.,max ϭ 0.67, 0.82. 2θmax ϭ 58°; Nt ϭ 39461,
N ϭ 18825 (Rint ϭ 0.079), No ϭ 7579; R ϭ 0.062, Rw ϭ 0.055.
[1]
[1a]
For reviews
Metal Alkoxides (Academic Press, London 1978). Ϫ
Mehrotra, A. Singh, U. M. Tripathi, Chem. Rev. 1991, 91,
D. C. Bradley, R. C. Mehrotra, D. P. Gaur,
[1b]
R. C.
[1c]
1287Ϫ1303. Ϫ
W. J. Evans, New. J. Chem. 1995, 19,
L. G. Hubert-Pfalzgraf, New. J. Chem. 1995,
|∆ρmax| ϭ 0.67(6) e AϪ3. T ca. 153 K. All hydrogen atoms except
˚
[1d]
525Ϫ533. Ϫ
those associated with the uncoordinated THF were refined in (x,
y, z, Uiso).
19, 727 Ϫ750. Ϫ [1e] L. G. Hubert-Pfalzgraf, Coord. Chem. Rev.
1998, 178Ϫ180, 967Ϫ997. Ϫ [1f] M. N. Bochkarev, L. N. Zakh-
[Yb(OArMe)3THF]: C64H59O4Yb, M ϭ 1065.2. Triclinic, space
arov and G. S. Kalinina, Organoderivatives of the Rare Earth
[1g]
Elements, Kluwer Academic, Dordrecht, 1995. Ϫ
D. C.
˚
¯
group P1, a ϭ 11.154(1), b ϭ 11.818(1), c ϭ 20.371(2) A, α ϭ
Bradley, R. C. Mehrotra, I. P. Rothwell, A. Singh, Alkoxo and
Aryloxo Derivatives of Metals, Academic Press, London, 2001.
3
˚
76.824(2)°, β ϭ 77.809(2)°, γ ϭ 78.415(2)°, V ϭ 2522 A . Dc (Z ϭ
2) ϭ 1.402 g cmϪ3. µMo ϭ 19.0 cmϪ1; specimen: 0.35 ϫ 0.17 ϫ
0.10 mm; ЈTЈmin.,max ϭ 0.66, 0.83. 2θmax ϭ 58°; Nt ϭ 29447, N ϭ
12359 (Rint ϭ 0.028), No ϭ 11025; R ϭ 0.046, Rw ϭ 0.065.
[2] [2a]
P. B. Hitchcock, M. F. Lappert, A. Singh, J. Chem. Soc.,
[2b]
Chem. Commun. 1983, 1499Ϫ1501. Ϫ
H. A. Stetcher, A.
Sen, A. L. Rheingold, Inorg. Chem. 1988, 27, 1130Ϫ1132. Ϫ
|∆ρmax| ϭ 2.4(1) e AϪ3. T ca. 153 K.
˚
[2c]
P. B. Hitchcock, M. F. Lappert, R. G. Smith, Inorg. Chim.
[2d]
Acta 1987, 139, 183Ϫ184. Ϫ
G. B. Deacon, C. M. Forsyth,
[Yb(OArPh)3DME]·1.5THF: C100H85O6.5Yb, M ϭ 1563.8. Mono-
[2e]
R. H. Newnham, Polyhedron 1987, 6, 1143Ϫ1144. Ϫ
G.
clinic, space group P21/c (C52h, no. 14), a ϭ 13.0079(9), b ϭ
B. Deacon, P. B. Hitchcock, S. A. Holmes, M. F. Lappert, P.
3
˚
˚
32.407(2), c ϭ 24.860(2) A, β ϭ 91.798(1)°, V ϭ 10474 A . Dc (Z ϭ
4) ϭ 0.992 g cmϪ3. µMo ϭ 9.4 cmϪ1; specimen: 0.30 ϫ 0.25 ϫ
0.10 mm; ЈTЈmin.,max ϭ 0.62, 0.86. 2θmax ϭ 58°; Nt ϭ 114947, N ϭ
18408 (Rint ϭ 0.098), No ϭ 11241; R ϭ 0.060, Rw ϭ 0.090.
MacKinnon, R. H. Newnham, J. Chem. Soc., Chem. Commun.
[2f]
1989, 935Ϫ937. Ϫ
G. B. Deacon, T. Feng, P. MacKinnon,
R. H. Newnham, S. Nickel, B. W. Skelton, A. H. White, Aust.
[2g]
J. Chem. 1993, 46, 387Ϫ399. Ϫ
G. B. Deacon, T. Feng, S.
|∆ρmax| ϭ 1.54(6) e AϪ3. T ca. 300 K. Lattice solvent residues were
˚
Nickel, M. I. Ogden, A. H. White, Aust. J. Chem. 1992, 45,
[2h]
671Ϫ683. Ϫ
J. R. van den Hende, P. B. Hitchcock, M. F.
modelled as 0.5THF at each of three sites, with constrained geo-
metries and isotropic thermal parameter forms.
Lappert, J. Chem. Soc., Chem. Commun. 1994, 1413Ϫ1414. Ϫ
[2i]
J. R. van den Hende, P. B. Hitchcock, S. A. Holmes, M. F.
[Yb(OArMe)2(THF)3]: C52H58O5Yb, M ϭ 936.1. Monoclinic, space
Lappert, J. Chem. Soc., Dalton Trans. 1995, 1435Ϫ1439.
[3] [3a]
group Cc (C4s, no. 9), a ϭ 19.945(1), b ϭ 11.8084(5), c ϭ 19.193(1)
J. Marc¸alo, A. Pires De Matos, Polyhedron 1989, 8,
˚
˚
2431Ϫ2437. Ϫ [3b]J. Marc¸alo, unpublished results, cited in
3
A, β ϭ 97.416(3)°, V ϭ 4482 A . Dc (Z ϭ 4) ϭ 1.387 g cmϪ3
.
refs.[4b] and
.
[4c]
µMo ϭ 21.2 cmϪ1; specimen: 0.17 ϫ 0.15 ϫ 0.08 mm; ЈTЈmin.,max
ϭ
[4] [4a]
G. B. Deacon, S. Nickel, P. MacKinnon, E. R. T. Tiekink,
0.50, 0.85. 2θmax ϭ 53°; Nt ϭ 23259, N ϭ 7519 (Rint ϭ 0.11; ЈFrie-
del pairsЈ retained distinct), No ϭ 6338; R ϭ 0.053, Rw ϭ 0.093.
[4b]
Aust. J. Chem. 1990, 43, 1245Ϫ1257. Ϫ
G. B. Deacon, B.
M. Gatehouse, Q. Shen, G. Ward, E. R. T. Tiekink, Polyhedron
|∆ρmax| ϭ 0.9 e AϪ3. T ca 193 K. Data were measured using a
˚
1993, 12, 1289Ϫ1294. Ϫ [4c] G. B. Deacon, T. Feng, B. W. Skel-
[4d]
Nonius Kappa CCD instrument. Refinement was carried out using
the SHELX-97 system.[23] The phenyl ring pendant at C(26) was
modelled as disordered over two sets of sites of equal occupancy,
with isotropic thermal parameter refinement for the carbon atoms.
The absolute structure was indeterminate.
ton, A. H. White, Aust. J. Chem. 1995, 48, 741Ϫ756. Ϫ
G.
B. Deacon, T. Feng, P. C. Junk, B. W. Skelton, A. H. White,
Chem. Ber./Recueil 1997, 130, 851Ϫ857.
[5]
[5a] G. B. Deacon, C. M. Forsyth, P. C. Junk, B. W. Skelton, A.
H. White, Chem. Eur. J. 1998, 5, 1452Ϫ1459. Ϫ[5b] G. B. Dea-
con, T. Feng, C. M. Forsyth, A. Gitlits, D. C. R. Hockless, Q.
Shen, B. W. Skelton, A. H. White, J. Chem. Soc., Dalton Trans.
2000, 961Ϫ966.
[Sc(OArH)3]: C54H39O3Sc, M ϭ 780.9. Monoclinic, space group
˚
P21/c, a ϭ 11.261(8), b ϭ 20.10(1), c ϭ 17.81(1) A, β ϭ 100.02(1)°,
Eur. J. Inorg. Chem. 2001, 1505Ϫ1514
1513

G. B. Deacon, P. E. Fanwick, A. Gitlits, I. P. Rothwell, B. W. Skelton, A. H. White
FULL PAPER
[6]
[13]
[6a] R. W. Chestnut, L. D. Durfee, P. E. Fanwick, I. P. Rothwell,
J. E. Cosgriff, G. B. Deacon, G. D. Fallon, B. M. Gatehouse,
H. Schumann, R. Weimann, Chem. Ber. 1996, 129, 953Ϫ958.
W. T. Carnall, in The Absorption and Fluorescence Spectra of
Rare Earth Ions in Solution, in Handbook on the Physics and
Chemistry of Rare Earths, Vol. 3 (Eds.: K. A. Gschneidner, L.
Eyring), North-Holland, Amsterdam, 1979, chapter 24.
M. Johnson, J. C. Taylor, G. W. Cox, J. Appl. Crystallogr. 1980,
13, 188Ϫ189.
G. B. Deacon, Q. Shen, J. Organomet. Chem. 1996, 511, 1Ϫ17.
J. L. Atwood, K. D. Smith, J. Am. Chem. Soc. 1973, 95,
1488Ϫ1491.
G. B. Deacon, C. M. Forsyth, B. M. Gatehouse, A. Philosof,
B. W. Skelton, A. H. White, P. A. White, Aust. J. Chem. 1997,
50, 959Ϫ970.
K. Folting, J. C. Huffman, Polyhedron 1987, 6, 2019Ϫ2026. Ϫ
[6b]
[14]
J. S. Vilardo, M. A. Lockwood, L. G. Hanson, J. R. Clark,
B. C. Parkin, P. E. Fanwick, I. P. Rothwell, J. Chem. Soc., Dal-
[6c]
ton Trans. 1997, 3353Ϫ3362. Ϫ
J. S. Vilardo, M. G. Thorn,
P. E. Fanwick, I. P. Rothwell, Chem. Commun. 1998,
[6d]
[15]
2425Ϫ2426. Ϫ
J. S. Vilardo, P. E. Fanwick, I. P. Rothwell,
Polyhedron 1998, 17, 769Ϫ771. Ϫ [6e] P. N. Riley, M. G. Thorn,
[16]
[17]
J. S. Vilardo, M. A. Lockwood, P. E. Fanwick, I. P. Rothwell,
[6f]
Organometallics 1999, 18, 3016Ϫ3024. Ϫ
J. S. Vilardo, M.
M. Salberg, J. R. Parker, P. E. Fanwick, I. P. Rothwell, Inorg.
Chim. Acta 2000, 299, 135Ϫ141.
[7a] J. E. Cosgriff, G. B. Deacon, B. M. Gatehouse, H. Hemling,
[18]
[19]
[7]
[8]
H. Schumann, Angew. Chem. 1993, 105, 906Ϫ907; Angew.
[7b]
A. Galan, A. J. Sutherland, P. Ballester, J. Rebek, Jr., Tetrahed-
ron Lett. 1994, 35, 5359Ϫ5362.
Chem. Int. Ed. Engl. 1993, 32, 874Ϫ875. Ϫ
J. E. Cosgriff,
G. B. Deacon, B. M. Gatehouse, H. Hemling, H. Schumann,
[20] [20a]
D. H. R. Barton, D. M. X. Donnely, P. J. Guiry, J. H.
Reibenspies, J. Chem. Soc., Chem. Commun. 1990, 1110Ϫ1111.
Aust. J. Chem. 1994, 47, 1223Ϫ1235.
[8a] G. B. Deacon, E. E. Delbridge, B. W. Skelton, A. H. White,
Eur. J. Inorg. Chem. 1998, 543Ϫ545. Ϫ [8b] G. B. Deacon, E. E.
Delbridge, B. W. Skelton, A. H. White, Eur. J. Inorg. Chem.
1999, 751Ϫ761.
[20b]
Ϫ
D. H. R. Barton, N. Y. Bhatnagar, J.-C. Blazejewski, B.
Charpiot, J.-P. Finet, D. J. Lester, W. B. Motherwell, M. T. B.
Papoula, S. P. Stanforth, J. Chem. Soc., Perkin Trans. 1 1985,
2657Ϫ2665.
[9] [9a]
K. P. Butin, A. N. Kashin, I. P. Beletskaya, L. S. German,
[21] [21a]
P. Yates, J. R. Hyre, J. Org. Chem. 1962, 27, 4101Ϫ4103.
[9b]
V. R. Polishchuk, J. Organomet. Chem. 1970, 25, 11Ϫ16. Ϫ
K. P. Butin, I. P. Beletskaya, A. N. Kashin, O. A. Reutov, J.
Organomet. Chem. 1967, 10, 197Ϫ210.
[21b]
Ϫ
A. S. Hay, R. F. Clark, Macromolecules 1970, 3,
533Ϫ535. Ϫ [21c] H. Yang, A. S. Hay, Synthesis 1992, 467Ϫ472.
[21d]
Ϫ
D. E. Dana, A. S. Hay, Synthesis 1982, 164Ϫ165.
[10]
J. E. Cosgriff, G. B. Deacon, B. M. Gatehouse, H. Hemling,
H. Schumann, Aust. J. Chem. 1994, 47, 1223Ϫ1235; and refer-
ences therein.
R. J. H. Clark, J. Lewis, D. J. Machin, R. S. Nyholm, J.
J. Lewis, J. R. Miller, R. L.
Richards, A. Thompson, J. Chem. Soc. 1965, 5850Ϫ5860.
[22]
[23]
The Xtal 3.4 UserЈs Manual (Eds.: S. R. Hall, G. S. D. King, J.
M. Stewart), University of Western Australia, Lamb: Perth,
1995.
G. M Sheldrick, SHELXS-97: A Program for Crystal Structure
Refinement, University of Göttingen, 1997.
Received November 29, 2000
[11] [11a]
[11b]
Chem. Soc. 1963, 379Ϫ387. Ϫ
[12]
R. D. Shannon, Acta Crystallogr., Sect. A 1976, 32, 751Ϫ767.
[I00458]
1514
Eur. J. Inorg. Chem. 2001, 1505Ϫ1514