Synthesis and structure of alkali metal 'ate' complexes in the yttrium/2,6-dimethylphenoxide system

Article abstract of DOI:10.1016/S0022-328X(97)00635-9

The neutral complex Y(OAr)₃(THF)₃, 1, (Ar=C₆H₃Me₂-2,6) prepared from Y[N(SiMe₃)₂]₃ and HOAr, can be converted to the ionic 'ate' salts [(DME)Li]₂[(μ-OAr)₄Y(OAr)], 2, [(THF)₃K][(μ-OAr)₂Y(OAr)₂(THF)₂], 3, and [Na(THF)₆][(C₅Me₅)Y(OAr)₃], 4, with the alkali metal reagents LiOAr, KOAr, and NaC₅Me₅ (DME=dimethoxyethane). The yttrium center in complex 2 is square pyramidal with the terminal aryloxide ligand in the apical position and no agostic interactions. The octahedral coordination environment around yttrium in 3 is formed by two bridging aryloxides, two terminal aryloxides and two THF molecules. This complex has close K-C(ipso) contacts of 3.288(9) and 3.400(10) A. Complex 4 contains an isolated hexasolvated cation and a formally 6-coordinate yttrium atom in which the three aryloxide oxygen atoms and the η⁵-C₅Me₅ ring centroid describe a distorted tetrahedron.

Full text of DOI:10.1016/S0022-328X(97)00635-9

Ž
.
Journal of Organometallic Chemistry 553 1998 141–148
Synthesis and structure of alkali metal ‘ate’ complexes in the
yttriumr2,6-dimethylphenoxide system
a
a
b
William J. Evans a,), Mohammad A. Ansari , Joseph W. Ziller , Saeed I. Khan
a
Department of Chemistry, UniÕersity of California, IrÕine, CA 92697-2025, USA
Department of Chemistry and Biochemistry, UniÕersity of California, Los Angeles, CA 90095, USA
b
Received 19 May 1997; received in revised form 3 September 1997
Abstract
Ž
. Ž
.
Ž
Ž
.x
.
w Ž
. x
. x
The neutral complex Y OAr THF , 1, ArsC6H3Me2-2,6 prepared from Y N SiMe3
and HOAr, can be converted to the
3
3
wŽ
.
x wŽ
.
wŽ
.
xwŽ
.
Ž
. Ž
2 w3
Ž
. xwŽ
. Ž
. x
ionic ‘ate’ salts DME Li
m-OAr Y OAr , 2, THF 3K m-OAr Y OAr THF , 3, and Na THF
C5Me5 Y OAr , 4, with
2
4
2
2
2
6
3
Ž
.
the alkali metal reagents LiOAr, KOAr, and NaC5Me5 DMEsdimethoxyethane . The yttrium center in complex 2 is square pyramidal
with the terminal aryloxide ligand in the apical position and no agostic interactions. The octahedral coordination environment around
Ž
.
yttrium in 3 is formed by two bridging aryloxides, two terminal aryloxides and two THF molecules. This complex has close K–C ipso
˚
Ž .
Ž .
contacts of 3.288 9 and 3.400 10 A. Complex 4 contains an isolated hexasolvated cation and a formally 6-coordinate yttrium atom in
which the three aryloxide oxygen atoms and the h5-C5Me5 ring centroid describe a distorted tetrahedron. q 1998 Elsevier Science S.A.
Keywords: Yttrium; Alkoxide; ‘Ate’ complex; Pentamethylcyclopentadienide; Alkali metal
1. Introduction
Recent developments in materials science 1–4 and
property of making not one, but two neutral complexes
free of alkali metals, oxides and halides, as shown in
w
x
Ž .
Ž .
w x
Eqs. 1 and 2 31 .
w
x
organometallic chemistry 5–8 have spurred interest in
alkoxide complexes of yttrium and the lanthanide met-
als. Alkoxides may be useful in assembling molecular
precursors for materials applications and may function
as solubilizing, stabilizing ligands alternative to the
common cyclopentadienyl groups. Although alkoxide
compounds of these metals have been known for many
YCl3 THF 3 q3NaOAr
Ž
.
™ Y OAr THF 3 q3NaCl
.3Ž
1
Ž .
Ž
.
1
2Y OAr THF
.3Ž
Ž
.
3
| Y m-OAr OAr THF 2 q4THF
2
Ž .
Ž
. Ž
.2Ž
.
w
x
years 9–11 , the extensive variation in structure and
1a
composition possible with this class is only now being
This is unusual since formation of anionic ‘ate’ salts by
incorporation of alkali metals with halide, alkoxide, or
1
w
x
revealed 12,13 . Products of varying structure and
composition are observed depending on the
metalrligand combination and the particular starting
materials used. Many of the variations observed are due
to the incorporation of alkali metals, halides, and ox-
ides.
w
x
oxide units is a very common result 18,29 .
The conversion of the trisolvated monomer,
Ž
. Ž
.
w Ž
Y OAr THF , 1, to the monosolvated dimer, Y m-
3
.Ž
. Ž3
.
x2
OAr OAr THF
,
1a, suggests that this
2
yttriumr2,6-dimethylphenoxide system provides access
to a reactive, coordinatively unsaturated intermediate
with less than three THF ligands per yttrium which can
add THF but should add other ligands as well. We have
examined the possibility of making organometallic
derivatives of this YrOAr system by adding anionic
Our studies of the 2,6-dimethylphenoxide ligand,
Ž
.
OC6 H3Me2-2,6 OAr in this paper , have shown that in
combination with yttrium this group has the favorable
)
w
Ž
alkyl and cyclopentadienyl reagents to Y m-
.Ž . Ž
Corresponding author.
Only some reviews and leading Ref. 14–31 are given here.
1
.
x
in toluene. However, these reac-
w
x
OAr OAr THF
2
2
0022-328Xr98r$19.00 q 1998 Elsevier Science S.A. All rights reserved.

(
)
142
W.J. EÕans et al.rJournal of Organometallic Chemistry 553 1998 141–148
[(
)
][(
) (
) (
) ]
tions repeatedly led to the formation of alkali metal
‘ate’ salt products. To learn more about such com-
pounds and this crucial aspect of the synthetic chem-
istry, we have studied the deliberate synthesis and struc-
tural characterization of representative ‘ate’ salts for this
metalrligand combination.
2.3. THF 3 K m-OAr 2Y OAr 2 THF 2 , 3
Ž
.
KOAr 80 mg, 0.5 mmol was added to a solution of
1 337, 0.5 mmol in 10 ml of THF. The reaction was
stirred for 10 h and centrifuged. A small amount of
solid was obtained and discarded. The volume of the
solution was reduced to half and the solution was
layered with a few drops of hexanes and cooled to
Ž
.
Ž
2. Experimental section
y388C. Large block-shaped colorless crystals 320 mg,
.
66% formed in 24 h. Anal. Calcd. for C52 H76O9 KY:
All the complexes described in Sections 2.1, 2.2, 2.3,
2.4, 2.5, 2.6 and 2.7 were handled with rigorous exclu-
sion of air and moisture using standard Schlenk, vac-
uum line, and glove box techniques. Solvents were
dried and physical measurements obtained as previously
1
Ž
.
Ž
w
x
w
x
w
Ž
.
x w
x
described 32 . YCl3 33 and Y N SiMe3
34 were
2
3
prepared according to the literature. 2,6-Dimethylphenol
Ž
.
Aldrich was sublimed before use. NMR spectra were
recorded using a General Electric QE-300 spectrometer
at 208C.
[(
) (
) ][
(
) ]
2.4. C5 Me5 Y OAr 3 Na THF 6 , 4
(
) ( [ ]
)
Ž
2.1. ImproÕed synthesis of Y OAr 3 THF 3 , 1 31
A 5 ml THF solution of NaC5Me5 158 mg, 1.0
.
Ž
mmol was added to a 10 ml THF solution of 1 667
mg, 1.0 mmol . The reaction was stirred for 16 h and
Ž
.
mmol was added to
570 mg, 1.0 mmol in 20 ml of THF.
.
HOAr 366 mg,
2 x3
3
w
Ž
.
Ž
.
Y N SiMe3
was centrifuged. The volume of the solution was re-
duced to half, the solution was layered with a few drops
of hexanes, and the solution was cooled to y388C to
The clear colorless solution was stirred for 24 h and
centrifuged. The solution was evaporated to dryness and
the resulting solid was recrystallized from THFrhexanes
Ž
.
produce colorless crystals 750 mg, 72% . Anal. Calcd.
for C58 H90O9 NaY: C, 66.78; H, 8.7; Na, 2.20; Y, 8.52.
Ž
at room temperature to form 1 as colorless crystals 610
1
1
.
mg, 90% . The H NMR spectrum was identical to that
Found: C, 68.78; H, 6.03; Na, 2.38; Y, 9.06. H NMR
benzene-d6 7.06 d, 6H, C6 H3Me2 , 6.74 t, 3H,
C6 H3Me2 , 3.32 m, 24H, THF , 2.35 s, 18H,
w
x
Ž
.
Ž
.
Ž
reported earlier 31 .
.
Ž
.
Ž
[(
)
] [(
m-
.
Ž
.
Ž
.
2.2. Synthesis of
OAr 4Y OAr , 2
MeOCH2 CH2 OMe Li
C6 H3 Me2 , 2.11 s, 15H, C5 Me5 , 1.27 m, 24H, THF .
2
13C NMR benzene-d6 161.0, 128.4, 125.0, 116.4
) (
)]
Ž
.
Ž
.
Ž
.
Ž
.
Ž
.
C6 H3Me2 , 116.8 C5Me5 , 67.5 THF , 25.2 THF ,
Ž
.
Ž
.
Ž
.
Ž
.
LiOAr 128 mg, 1.0 mmol was added to a solution
17.9 C6 H3 Me2 , 10.5 C5 Me5 . IR Nujol 1590 m,
1462 s, 1377 m, 1295 m, 1241 w, 1088 m, 1047 m, 913
Ž
.
of 1 334 mg, 0.5 mmol in 10 ml of THF. The reaction
mixture was stirred for 24 h at ambient temperature and
centrifuged. The solution was dried on a rotary evapora-
tor to yield a white powder. X-ray quality crystals 340
mg, 76% were grown by layering MeOCH2CH2OMe
w, 864 m, 782 w, 755 w, 710 w cmy1
.
Ž
2.5. X-ray data collection and structure refinement for
[( ) ] [( ) ( )]
.
DME Li m-OAr 4Y OAr , 2
2
Ž
.
DME and hexanes on a THF solution at y388C. Anal.
Calcd. for C48 H65O9 Li2Y: C, 64.86; H, 7.37; Y, 10.0.
A crystal of dimensions 0.20=0.25=0.30 mm
1
Ž
Found: C, 65.41, H, 8.69, Y, 11.2. H NMR crude
product before addition of DME, THF-d8 d 6.81 d,
10H, C6 H3Me2 , 6.34 t, 5H, C6 H3Me2 , 2.39 s, 30H,
C6 H3 Me2 . H NMR crystalline 2, THF-d8 6.77 d,
mounted in a Lindeman capillary under dinitrogen in a
dry box was placed in the cold nitrogen stream of a
Picker diffractometer modified at UCLA which was
.
Ž
.
Ž
.
Ž
1
.
Ž
.
Ž
Ž .
operating at a temperature of 156 2 K. Intensity data
.
Ž
.
Ž
10H, C6 H3Me2 , 6.15 t, 5H, C6 H3Me2 , 3.50 s, 8H,
were collected with graphite monochromated Mo Ka
radiation up to maximum 2u of 508. Of the 2241 total
reflections collected only 970 were observable above
.
,
3
Ž
s, 1 2 H ,
C H O C H 2 C H 2 O C H
3 .3 3
3
C H3OCH2CH2OC H3 , 2.19 s, 30H, C6 H3 Me2 . 13C
.
Ž
.
Ž
.
Ž
3
.
.
Ž .
Table 1.
NMR THF-d8 166.6, 128.2, 125.2, 111.6 C6 H3Me2 ,
C H 3 O C H 2 C H 2 O C H
CH3OCH2CH2OCH3 , 18.5 C6 H3 Me2 . IR Nujol
1461 s, 1376 m, 1270 s, 1231 m, 1193 w, 1117 w, 1086
w, 1072 m, 1022 w, 872 w, 848 m, 758 w, 746 m, 691
I)2s I . Other details of data collection are given in
Ž
.
,
7 2 .7
Ž
5 8 .9
.
Ž
Ž
.
The structure was solved by heavy atom methods
using SHELX86 35 . The complex crystallizes in the
orthorhombic space group P22121. The structure was
refined using SHELX76 36 . All of the hydrogen atoms
w
x
m cmy1
.
w
x

(
)
W.J. EÕans et al.rJournal of Organometallic Chemistry 553 1998 141–148
143
Table 1
Crystallographic data for DME Li
wŽ
.
x wŽ
.
Ž
.x
wŽ
.
xwŽ
.
Ž
. Ž . x
m-OC6 H3Me2-2,6 Y OC6 H3Me2-2,6 , 2, THF 3K m-OC6 H3Me2-2,6 Y OC6 H3Me2-2,6 THF ,
2
2
4
2
2
w
Ž
. xwŽŽ
. Ž
. x
3, and Na THF
C5Me5 Y OC6 H3Me2-2,6 , 4
6
3
Compound
2
3
4
Formula
Formula weight
Space group
C48 H65O9 Li2Y
888.79
P22121
Ž .
12.537 2
Ž .
12.947 2
C52 H76O9 KY
973.1
C58 H90O9 NaY
1043.24
P21rn
14.301 6
P21rn
˚
Ž .
Ž .
a, A
14.610 2
Ž .
20.846 3
˚
Ž .
19.623 6
b, A
˚
Ž .
14.609 2
Ž .
97.99 3
Ž .
92.67 1
c, A
18.599 8
Ž .
19.451 2
Ž .
b, 8
Z
2
4
4
3
˚
Ž .
Ž .
Ž .
V, A
2371.4 7
1.24
5169 4
1.25
5917 1
1.17
D, calculated, g cmy3
Radiation, l
0.7107
1.285
0.063
0.062
4
0.71073
1.26
0.089
0.097
3
0.7107
1.045
0.079
0.081
3
Abs. coefficient, m, mmy1
RF
RŽw.F
Ž<
<
Fo )=s
Ž< <..
Fo , xs
GOF
1.58
1.46
2.853
were calculated and attached to appropriate carbon atoms
at a fixed distance with a fixed isotropic U. Aryloxide
groups were refined as rigid groups.
ters led to convergence with RF s8.9%, RwF s9.7%
and GOFs1.46 for 569 variables refined against those
<
<
Ž
<
<.
4651 data with Fo )3.0s Fo . A final difference-
Ž
.
Fourier map was devoid of significant features, r max
y3
˚
s1.20 e A
2.6. X-ray data collection and structure refinement for
[(
)
][(
) (
) (
) ]
THF 3 K m-OAr 2Y OAr 2 THF 2 , 3
2.7. X-ray data collection and structure refinement for
Na THF 6 C5 Me5 Y OAr 3 , 4
A colorless crystal of approximate dimensions 0.40
[
(
) ][(
) (
) ]
=0.80=0.83 mm was mounted on a Siemens P4
Ž .
diffractometer operating at a temperature of 156 2 K.
Intensity data were collected with graphite monochro-
mated Mo K a radiation up to a maximum 2u of 458.
Of the 5902 total reflections collected only 4651 were
observable above 3s . Details of data collection are
given in Table 1.
A crystal of dimensions 0.1=0.2=0.2 mm was
handled as described for 2 in Section 2.5. Intensity data
were collected up to a maximum 2u of 558. Of the 4477
total reflections collected only 2664 were observable
above 3s . Details of data collection are given in Table
1.
All crystallographic calculations were carried out
using either our locally modified version of the UCLA
The structure was solved by heavy atom methods
Ž
w x
Crystallographic Computing Package C. Strouse, Uni-
using SHELX86 35 . The complex crystallizes with
w
Ž
.Ž
.
xyw 6 xq
Ž
.
versity of California, Los Angeles, CA, 1981, personal
one Y C5Me5 OAr
Na THF
ion pair per
3
.
communication or the SHELXTL PLUS program set
asymmetric unit in monoclinic space group P21rn. The
w
x
w x
37 . The analytical scattering factors for neutral atoms
were used throughout the analysis 38 ; both the real
Df and imaginary iDf components of anomalous
dispersion 38 were included. The quantity minimized
structure was refined using SHELX76 36 . All of the
hydrogen atoms were calculated and attached to appro-
priate carbon atoms with a fixed isotropic U. The
w
x
X
Y
Ž
.
Ž
.
w
x
Ž .
phenoxide group involving O 3 was found to be disor-
2
Ž
<
<
<
<.
during least-squares analysis was Ýw Fo y F where
c
dered and was refined at two different orientations. The
large thermal parameters associated with many atoms of
the THF groups showed partial disorder. Three of these
wy1 ss 2 Fo q0.002 Fo
.
<.
2
Ž
<
<
.
Ž
<
The structure was solved by direct methods and
refined by full-matrix least-squares techniques. Hydro-
Ž
.
Ž
.
disordered THF groups, those involving O 40 , O 45 ,
Ž
.
gen atoms were included using a riding model with
and O 55 , were refined at more than one orientation
with constrained bond lengths and fixed temperature
factors. In the final cycle of least-squares refinement, all
of the THF and disordered aryloxide atoms were kept
isotropic and the remaining atoms were refined with
anisotropic temperature factors.
2
˚
˚
Ž
.
Ž
.
d C–H s0.96 A and U iso s0.08 A . The diffraction
symmetry was 2rm with systematic absences 0k0 for
ks2nq1, and h0l for hqls2nq1. The cen-
trosymmetric space group P21rn is therefore uniquely
defined. Refinement of positional and thermal parame-

(
)
144
W.J. EÕans et al.rJournal of Organometallic Chemistry 553 1998 141–148
[(
) ] [(
) (
)]
3. Results and discussion
3.2. Structure of DME Li
m-OAr 4Y OAr , 2
2
3.1. Reaction with lithium 2,6-dimethylphenyloxide
Bond distances and angles in 2 are given in Table 2.
Complex 2 contains a C2 axis which is coincident with
the Y–O 3 –C 17 vector. The five aryloxide ligands
are arranged in a square pyramidal geometry around
Ž
. Ž
.
3
Y OC6 H3Me2-2,6 THF , 1, reacts with 1 equiva-
3
Ž .
Ž
.
lent of LiOC6 H3Me2-2,6 in THF to give a colorless
powder which does not crystallize readily from THF.
Ž .
Ž .
yttrium with 145.32 5 and 145.80 5 8 O–Y–O angles
w
Ž
. x wŽ
Addition of DME gave crystals of DME Li m-
2
Ž .
between the basal aryloxides and 107.10 2 and
107.34 2 8 Y–O–Y angles between the axial aryloxide
.
Ž
.x
OAr Y OAr , 2. The reaction was repeated with the
4
Ž .
stoichiometry appropriate for 2 and a yield of )70%
and the basal positions. The two unique bridging arylox-
Ž .
was obtained according to Eq. 3 .
˚
Ž .
Ž .
ide Y–O distances, 2.179 8 and 2.221 8 A, are longer
˚
Ž .
than the 2.098 1 A Y–O distance for the unique termi-
nal aryloxide as expected. In comparison, Y m-
Y OAr THF 3 q2LiOAr
.3Ž
Ž
.
w
Ž
1
˚
Ž .
.Ž
. Ž
.
x
Ž .
OAr OAr THF 2 , 1a, has 2.275 6 and 2.277 5 A
THFrDME
2
™
DME Li
m-OAr Y OAr
3
Ž .
Ž
.
Ž
.
Ž
.
Ž .
Ž .
4
bridging Y–O bond lengths and 2.049 6 and 2.075 6
2
2
˚
w
x
A terminal distances 31 .
1H NMR spectroscopy shows that all of the aryloxide
groups in 2 are equivalent on the NMR time scale at
down to y608C. Since the data were not structurally
definitive, an X-ray diffraction study was carried out.
Complex 2 crystallizes as the trimetallic species,
The Li atoms are located in a distorted tetrahedral
coordination environment formed by the two bridging
aryloxide ligands and a bidentate DME ligand. No
˚
Li PPP C agostic interactions were observed within 4 A
˚
Ž .
of Li. The 1.927 3 A average Li–OAr distance is in the
1.811 17 –1.995 12 A range found in the literature
39–43 . The 76.71 1 8 O DME –Li–O DME angle is
˚
.
w
Ž
.
x w
Ž
.
Ž
.
x
Ž
.
Ž
DME Li
m-OAr Y OAr , 2, which contains both
2
4
w
x Ž . Ž .
Ž .
bridging and terminal aryloxide ligands, Fig. 1.
wŽ
.
x wŽ
.
Ž
4
.x
Fig. 1. Structure of DME Li m-OC6 H3Me2-2,6 Y OC6 H3Me2-2,6 , 2, with thermal ellipsoids drawn at the 50% probability level.
2

(
)
W.J. EÕans et al.rJournal of Organometallic Chemistry 553 1998 141–148
145
Table 2
Important angles deg and distances
˚
Ž
.
Ž .
wŽ
.
x wŽ
.
Ž
.x
wŽ
.
xwŽ
A
for
DME Li
m-OC6 H3Me2-2,6 Y OC6 H3Me2-2,6 , 2,
THF 3K m-OC6 H3Me2-
4
.
Ž
. Ž
. x
w Ž
.Ž 2
. Ž
.x
2,6 Y OC6 H3Me2-2,6 THF , 3, and Y m-OC6 H3Me2-2,6 OC6 H3Me2-2,6 THF 2 , 5
2
2
2
2
2
3
5
Ž .
Ž .
Ž . Ž .
bridging Y 1 -O 2 2.213 6
Ž .
Ž .
bridging Y-O 2.277 5
bridging Y-O 1 2.221 8
bridging Y 1 -O 1 2.197 6
Ž . Ž .
Ž . Ž . Ž .
Ž .
2.275 6
bridging Y-O 2 2.179 8
Ž . Ž .
terminal Y-O 3 2.098 1
Ž . Ž . Ž .
terminal Y 1 -O 4 2.122 6
Ž .
terminal Y-O 2.075 5
terminal Y 1 -O 3 2.153 6
Ž . Ž . Ž .
Ž .
2.046 6
Ž . Ž . Ž
Y 1 -O 6 THF
.
.
Ž .
Y 1 -O 5 THF
Ž . Ž . Ž
2.453 6
Ž .
2.484 6
Ž .
Li-O 2
Ž .
1.925 3
Ž . Ž .
K 1 -O 2
Ž .
2.661 6
Li-O 1
1.928 3
K 1 -O 1
Ž . Ž .
Ž .
Ž .
Ž .
2.668 6
Ž . Ž
.
Ž .
Ž . Ž . Ž
.
Ž .
Li-O 4 DME 2.025 3
K 1 -O 7 THF 2.744 9
Ž . Ž Ž .
.
Ž . Ž . Ž Ž .
.
Li-O 5 DME 2.015 3
K 1 -O 8 THF 2.693 10
Ž . Ž . Ž
.
Ž .
K 1 -O 9 THF 2.756 9
Ž . Ž . Ž .
K 1 -C 1
3.288 9
Ž .
3.400 10
Ž . Ž .
K 1 -C 9
Ž .
Y-O 2 -Li
Ž .
98.84 1
Ž . Ž . Ž .
O 1 -Y 1 -O 3
Ž .
81.1 2
Y-O 1 -Li
97.35 1
O 1 -Y 1 -O 2
Ž . Ž . Ž .
Ž .
Ž .
Ž .
104.0 2
Ž .
Ž .
Ž .
Ž . Ž . Ž .
Ž .
105.9 2
O 4 -Li-O 5
Ž . Ž .
76.71 1
O 1 -Y 1 -O 4
Ž .
Ž . Ž . Ž .
Ž .
79.1 2
O 1 -Y-O 2
74.45 4
O 1 -Y 1 -O 5
Ž . Ž .
Ž .
Ž . Ž . Ž .
Ž .
161.6 2
O 1 -Y-O 1 A 145.32 5
O 1 -Y 1 -O 6
Ž . Ž . Ž .
Ž . Ž . Ž .
Ž .
108.5 2
O 1 -Y-O 2 A 95.32 4
O 2 -Y 1 -O 3
Ž . Ž . Ž .
Ž . Ž . Ž .
Ž .
103.1 2
O 1 -Y-O 3 107.34 2
O 2 -Y 1 -O 4
Ž . Ž . Ž .
Ž . Ž . Ž .
Ž .
159.8 2
O 2 -Y-O 3 107.10 2
O 2 -Y 1 -O 5
Ž . Ž . Ž .
Ž .
O 2 -Y 1 -O 6
Ž . Ž . Ž .
80.7 2
Ž .
39.2 2
O 3 -Y 1 -O 4
Ž . Ž . Ž .
Ž .
80.1 2
Ž .
79.5 2
Ž .
79.0 2
Ž .
80.7 2
Ž .
119.2 2
Ž .
65.1 2
Ž .
145.5 5
Ž .
141.3 5
O 3 -Y 1 -O 5
Ž . Ž . Ž .
O 3 -Y 1 -O 6
Ž . Ž . Ž .
O 4 -Y 1 -O 5
Ž . Ž . Ž .
O 4 -Y 1 -O 6
Ž . Ž . Ž .
O 5 -Y 1 -O 6
Ž . Ž . Ž .
O 1 -K 1 -O 2
Ž . Ž . Ž .
Y 1 -O 1 -C 1
Ž . Ž . Ž .
Y 1 -O 2 -C 9
Ž .
Ž
.
Ž
.
Ž .
Ž .
smaller than the 87.41 1 8 O OAr –Li–O OAr angle
through O 1 and O 3 are bridging to an alkali metal
Ž .
due to the chelation of the DME ligand.
and the aryloxide bound through O 4 is terminal. How-
ever, instead of completing the coordination sphere with
two more bridging groups as in 2, the remaining ligands
on yttrium are two THF molecules and a terminal
aryloxide. Hence, a six coordinate complex is found
rather than a five coordinate compound.
3.3. Reaction with potassium 2,6-dimethylphenyloxide
In contrast to the system above, the reaction of 1
w
Ž
.
xwŽ
with one equivalent of KOAr produces THF K m-
3
.
Ž
. Ž
. x
OAr Y OAr THF , 3, which crystallizes easily from
The geometry is quite distorted from octahedral with
2
2
2
Ž .
THFrhexanes in )60% yield according to Eq. 4 .
Ž .
Ž .
O–Y–O angles ranging from 79.1 2 to 108.5 2 8 be-
Ž .
tween cis ligand donor atoms and from 139.2 2 to
Ž .
Y OAr THF 3 qKOAr
.3Ž
Ž
.
161.6 2 8 between trans ligands. Complex 3 has
1
˚
Ž .
Ž .
2.197 6 and 2.213 6 A bridging Y–O bond lengths
and 2.122 6 and 2.153 6 A terminal Y–O distances
THF
˚
Ž .
Ž .
™
THF K
m-OAr Y OAr THF
.2Ž
4
Ž .
Ž
.
Ž
.
Ž
.
3
2
2
3
which fall in the normal ranges compared to 2 and 1a.
˚
Ž .
Ž .
Ž
.
The 2.493 6 and 2.484 6 A Y–O THF distances are
Since the NMR spectra of 3 were similar to those of 2
and not structurally definitive, 3 was also characterized
˚
Ž
.
longer than the 2.417 12
Y3 OCMe3 8Cl THF 27 , the 2.36 2 –2.45 2 A dis-
tances in Y3 OCMe3 7Cl2 THF 28 , and the 2.33 4 –
2.37 3 A distances in Y14 OCMe3 24Cl10O2 THF 28 ,
A
analogs in
˚
Ž
.
Ž
.
.
w
x
Ž .
Ž .
Ž
.
by X-ray diffraction Fig. 2 .
2
Ž
Ž
.
w
x
Ž .
2
˚
Ž .
Ž
.
Ž
.
w
x
[(
)
][(
) (
) (
) ]
3.4. Structure of THF 3 K m-OAr 2Y OAr 2 THF 2 ,
4
all of which contain six coordinate yttrium.
3
The potassium in 3 is ligated by seven donor atoms,
three oxygen atoms from THF molecules, two oxygen
atoms of the bridging aryloxides, and the ipso carbon
The coordination environment of 3 has some similar-
ities to that of 2 in that the aryloxide groups bound

(
)
146
W.J. EÕans et al.rJournal of Organometallic Chemistry 553 1998 141–148
wŽ
.
xwŽ
.
Ž
. Ž
. x
2
Fig. 2. Structure of THF 3K m-OC6 H3Me2-2,6 Y OC6 H3Me2-2,6 THF , 3, with thermal ellipsoids drawn at the 30% probability level.
2
2
w
Ž . xw
Na THF
6
Ž
. Ž
.
x
Ž .
atoms of the aryl rings in the bridging aryloxides. The
2.693 10 –2.756 9 A K–O THF distances are in the
C5Me5 Y OAr , 4. As shown in Eq. 5 ,
3
˚
Ž
.
Ž .
Ž
.
the C5Me5 ligand effectively replaces three THF
˚
Ž .
w
x
Ž .
normal range 44,45 , but the 2.661 6 and 2.668 6 A
molecules in 1.
Ž
.
K–O OAr distances are shorter than the analogous
i
NaC Me qY OAr THF
Ž
.3Ž
.
˚
3
w
Ž
.
4 x
Ž
Ž .
Ž .
.
w
x
5
5
distances in K Nd OC6 H3Pr -2,6
2.760 8 A 46
3x2n
Ž
Ž .
1
t
w
Ž
.
and KSm OC6 H3Bu2-2,6
2.778 6 and 2.967 9
THF
˚
.
A
˚
w
x
Ž .
Ž
.
Ž
.
.
47 . The 3.288 9 and 3.400 10 A K–C ipso
™ Na THF
C Me Y OAr
4
5
Ž
.
Ž
.
Ž
.
Ž .
. Ž .
3xy
The C5Me5 Y OAr anion is rare in that most
anionic alkoxide and aryloxide complexes of yttrium
and the lanthanides are homoleptic not heteroleptic and
the anions are connected to the cations by bridging
6
3
5
5
Ž
distances in 3 are similar to the analogous K–C ipso
i
˚
. w x
w
Ž
.
.
4 x
Ž
Ž .
distances in K Nd OC6 H3Pr2
3.256 9 A 46 , and
w
Ž
t
˚
. w x
w
Ž
3xn
Ž
Ž . Ž .
3.310 10 and 3.534 13 A 47 .
KSm OC6 H3Bu2
In comparison, in the extended structure of KBPh4, the
˚
Ž .
w x
K–C distances average 3.191 5 A 48 and the average
K–C C5 H5 distances in K m-C5 H5 2 Nd m-O-
Ž
.
Ä
w
Ž
.
Ž
x
.
2 x
4
w
x
w
Ž
.
Ž
x w
C6 H3Me2-2,6
49 , K C5H4 SiMe3
50 , and
w
Ž
.
nx
w
x
.
Ž .
K C5 CH2C6 H5 P3THF 51 are 3.17 13 , 3.00 2 ,
Table 3
Important angles
wŽ . Ž
5
˚
Ž .
A
Ž
.
˚
deg
and distances
ion in 4
for the
Ž .
and 3.04 4 A, respectively.
. xy
C5Me5 Y OC6 H3Me2-2,6
3
Ž . Ž .
Y 1 -O 2 2.087 11
Ž
.
.
.
Ž . Ž . Ž . Ž .
O 1 -Y 1 -O 2 106.4 2
O 1 -Y 1 -O 3 106.3 2
Y 1 -O 1 2.092 10
3.5. Reaction with sodium pentamethylcyclopentadi-
enide
Ž . Ž .
Ž
Ž . Ž . Ž .
Ž .
Ž . Ž .
Ž
Ž .
Ž . Ž . Ž . Ž .
Y 1 -O 3 2.103 10
O 2 -Y 1 -O 3 103.4 2
Ž . Ž .
Ž . Ž .
Y 1 -C 1 2.65 2
O 1 -Y 1 -cent 112.1
NaC5Me5 reacts with 1 in THF to form a toluene
Ž . Ž . Ž .
Ž . Ž .
Y 1 -C 3 2.64 2
O 2 -Y 1 -cent 111.4
1
Ž . Ž . Ž .
Ž . Ž .
Y 1 -O 1 -C 11 161.9 2
soluble product which has a simple H NMR spectrum
Y 1 -C 5 2.65 2
Ž . Ž . Ž .
O 3 -Y 1 -cent 116.3
Ž . Ž .
Ž
Ž
.
.
Ž .
Y 1 -C 7 2.62 2
Ž . Ž . Ž .
containing two singlets attributable to the methyl groups
in C5Me5 and OC6 H3Me2. X-ray crystallography
was carried out to determine that the solid state
structure of this product was the ion pair
Ž . Ž . Ž .
Y 1 -C 9 2.68 2
Y 1 -O 2 -C 19 168.8 2
a
Ž .
Ž . Ž . Ž .
Ž .
Y 1 -cent 2.369
Y 1 -O 3 -C 27 144.1 2
aCent is the C5Me5 ring centroid.

(
)
W.J. EÕans et al.rJournal of Organometallic Chemistry 553 1998 141–148
147
Fig. 3. Structure of the C5Me5 OC6 H3Me2-2,6 - ion in 4 with thermal ellipsoids drawn at the 30% probability level.
wŽ
.Ž
. x
3
t
Ž
.
Ž
.
w x
56 ,
2
ligands. Previously reported heteroleptic alkoxide an-
the neutral compounds C5Me5 Ce OC6 H3Bu2
w
Ž
w
Ž
. Ž
.Ž
.
x2
Ž
ions are limited to the bridged species K m-
C5R5 Y m-OCMe3 OCMe
,
C5R5 s C5Me5,
.
Ž
.
3 M e 2 - 2 ,6
2
x n
w
x
.
w3 2 x
w
Ž
.
x
Ž
C p N d m - O C
H
4 9 ,
C 9 R 7 , C 5 H SiM e 3
52 ,
C 5 H 5 2Y m -
2
6
Ž
w
Ž
w
.
Ž
.
Ž
.
w
x
.
Ž 4
. Ž
.
x
w
C 5 H 4 SiM e 3 Y m-OCM e 3 2 Li THF
52 ,
O C M e 3 2Y C H
Ž
O C M e 3
5 2 , a n d
2
.
5
5
Ž
.
x2
Ž
.
Ž
w
x
.
Ž
.
Ž
. w
x
M e 3 Si 2 C H Y m -O C M e 2 Li TH F
53 ,
C5H4SiMe3 2Y m-OCMe3 2 Li THF 52 .
2
2
.
w
Ž
.
xw3
Ž
.
Ž
.
2 x2
Me SiCH Y m-CH2 2 SiMe2 m-OCMe3 Li THF
x 3
w 2
Ž
.
x
Ž
.
Ž
. w x
54 , and Me3C CO Nd m-Cl Li THF 26 .
3
3
3
4. Conclusion
[
(
) ][(
) (
) ]
3.6. Structure of Na THF 6 C5 Me5 Y OAr 3 , 4
The two ions comprising complex 4 are sufficiently
separated in the solid state that they are non-interacting.
Bond distances and angles are given in Table 3 and the
anion is shown in Fig. 3. The centroid of the C5Me5
ring and the three oxygen atoms of the OC6 H3Me2
ligands form a distorted tetrahedron around yttrium with
The 2,6-dimethylphenoxide ligand can make a vari-
ety of complexes with yttrium. Although neutral alkali
metal free complexes can be readily made, as shown in
Ž .
Ž .
Eqs. 1 and 2 , in the presence of the appropriate
alkali metal reagents, addition reactions to form anionic
Ž . Ž .
‘ate’ salts can also readily occur, Eqs. 3 – 5 . The
Ž .
Ž .
parameters in 4 are not exceptional: the 2.087 11 to
angles ranging from 103.4 4 to 116.3 4 8. The bonding
2,6-dimethylphenoxide ligand can support five and six
coordination at yttrium in both terminal and bridging
modes. It is clear from the differences in complexes 2
and 3, that variations in preferred structures can be
influenced quite easily by factors beyond the immediate
coordination sphere of yttrium. Choice of alkali metal
and recrystallization solvent can have critical influences
on the structures obtained.
Ž
.
˚
.
Ž
2.103 10 A Y–O distances are in the range typical of
Ž .
terminal yttrium 2,6-dimethylphenoxides and the 2.62 2
˚
Ž .
Ž
.
w x
to 2.68 2 A Y-C C5Me5 distances are normal 55 .
A lthough com plexes of general form ula
are very reasonable for yttrium and
the lanthanides, the closest examples in the literature are
w
Ž
. Ž .
3xy
C5R5 Y OR

(
)
148
W.J. EÕans et al.rJournal of Organometallic Chemistry 553 1998 141–148
w
x
27 W.J. Evans, M.S. Sollberger, T.P. Hanusa, J. Am. Chem. Soc.
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.
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x
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.
28 W.J. Evans, M.S. Sollberger, Inorg. Chem. 27 1988 4417.
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For support of this research, we thank the Division of
Chemical Sciences of the Office of Basic Energy Sci-
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