Organometallic complexes of scandium and yttrium supported by a bulky salicylaldimine ligand

Article abstract of DOI:10.1021/om020382c

The preparation of organometallic derivatives of scandium and yttrium supported by a bulky salicyladiminato ligand from the tris(alkyl) precursors [M(CH₂SiMe₂R)₃(THF)₂] (M = Sc, 1-Sc_R; M = Y, 1-Y_R; R = CH₃, Ph) via alkane elimination was presented. The synthesis and thermal decomposition of bis(ligand) mono(alkyl) complexes was also discussed. It was found that the ancillary ligand provides an adequate level of steric stabilization for the larger yttrium nucleus.

Full text of DOI:10.1021/om020382c

4226
Organometallics 2002, 21, 4226-4240
Or ga n om eta llic Com p lexes of Sca n d iu m a n d Yttr iu m
Su p p or ted by a Bu lk y Sa licyla ld im in e Liga n d
David J . H. Emslie,† Warren E. Piers,*,† Masood Parvez,† and Robert McDonald‡
Department of Chemistry, University of Calgary, 2500 University Drive, NW, Calgary,
Alberta, Canada T2N 1N4, and X-ray Structure Laboratory, Department of Chemistry,
University of Alberta, Edmonton, Alberta, Canada T6G 2G2
Received May 13, 2002
Organometallic derivatives of scandium and yttrium supported by a bulky salicylaldiminato
ligand were prepared from the tris(alkyl) precursors [M(CH2SiMe2R)3(THF)2] (M ) Sc, 1-ScR;
M ) Y, 1-YR; R ) CH3, Ph) via alkane elimination. The new precursors 1-MP h are convenient
alternatives to the 1-MMe derivatives, due to their higher thermal stability and crystallinity;
1-ScP h has been characterized crystallographically. Reaction of these compounds with 1 equiv
of protio ligand gives isolable mono(ligand) bis(alkyl) derivatives only for 1-Y; for other
derivatives 1-Sc, mixtures were obtained. The products of the former reaction retain either
two (2-YP h ) or one (3-YP h ) THF ligands; both of these compounds have been characterized
crystallographically. In solution, both exhibit fluxional exchange between two geometric
isomers which were characterized by variable-temperature NMR spectroscopy. Heating
solutions of either compound leads to facile ligand redistribution. Reactions of tris(alkyls) 1
with 2 equiv of protio ligand gives the five-coordinate, THF-free bis(ligand) mono(alkyl)
complexes 4-MR. These compounds are highly thermally stable, decomposing at temperatures
above 140 °C via a pathway involving metalation of one of the N-aryl isopropyl methyl groups.
The derivatives 4-ScMe and 4-YP h have been structurally characterized, as well as the product
of thermolysis of 4-ScMe, the nonorganometallic four-coordinate complex 5-Sc. Both 4-ScMe
and 4-YP h react slowly but cleanly with H2. The former yields a product, 7-Sc, derived from
transfer of the in situ formed scandium hydride to the aldimine carbon of one of the ligands.
The yttrium product, however, is the D2-symmetric dimeric µ-hydride complex 6-Y,
characterized by spectroscopic and crystallographic methods. A survey of 6-Y's reactivity
toward deuterated solvents, d2-6-Y, ethylene, (trimethylsilyl)acetylene, [HB(C6F5)2]2, ben-
zophenone, pyridine, and THF suggests that it does not dissociate into a monomeric hydride
but reacts as a dimer. Nonetheless, products from the reactions of (trimethylsilyl)acetylene,
[HB(C6F5)2]2, benzophenone, pyridine, and THF were isolated and characterized spectroscopi-
cally and, in the case of the product from the benzophenone reaction, crystallographically.
Finally, reactions of mono(alkyls) 4-ScMe and 4-YP h with a further 1 equiv of protio ligand
gave nonorganometallic tris(ligand) coordination complexes, both of which were structurally
and spectroscopically characterized. The scandium derivative 8-Sc contained an O-bound
κ1-salicylaldiminato ligand, while for 8-Y, containing the larger Y nucleus, all three ligands
were chelating in the normal κ2 bonding mode.
In tr od u ction
is effective at stabilizing Lewis base free organometallic
compounds, the two Cp donors use up two of the metal’s
three valences, limiting the number of more interesting
reactive ligands to one. The development of suitable
uninegative donors would allow for organometallic
derivatives with two hydrocarbyl or hydrido ligands and
expand the possibilities for new stoichiometric or cata-
lytic chemistry at a group 3 metal center. The avail-
ability of well-defined group 3 complexes LMR2 also
provides an avenue into group 3 alkyl cations analogous
to that for the group 4 metallocenium cations, which
are so effective as olefin polymerization catalysts.3 Thus,
in addition to the opportunity to pose fundamental
questions in the organometallic chemistry of the group
While the early development of organoscandium and
yttrium chemistry was dominated by the bis(cyclopen-
tadienyl) bent-metallocene ligand environment,1 recent
years have seen a concerted effort by several groups to
implement alternative ancillary ligand systems for
organo group 3 metal chemistry.2 In part, this stems
from the fact that, although the metallocene framework
* To whom correspondence should be addressed. Phone: 403-220-
5746. Fax: 403-289-9488. E-mail: wpiers@ucalgary.ca. S. Robert Blair
Professor of Chemistry (2000-2005); E. W. R. Steacie Memorial Fellow
(2000-2002).
† University of Calgary.
‡ University of Alberta.
(1) (a) Piers, W. E.; Shapiro, P. J .; Bunel, E. E.; Bercaw, J . E. Synlett
1990, 74. (b) Cotton, F. A. Polyhedron 1999, 18, 1691. (c) Butenschon,
H. Chem. Rev. 2000, 100, 1527. (d) Siemeling, U. Chem. Rev. 2000,
100, 1495.
(3) Guram, A. S.; J ordan, R. F. In Comprehensive Organometallic
Chemistry II; Lappert, M. F., Ed.; Elsevier Scientific: Oxford, U.K.,
1995; Vol. 4, p 589.
(2) Piers, W. E.; Emslie, D. J . H. Coord. Chem. Rev., in press.
10.1021/om020382c CCC: $22.00 © 2002 American Chemical Society
Publication on Web 08/27/2002

Organometallic Complexes of Scandium and Yttrium
Organometallics, Vol. 21, No. 20, 2002 4227
3 metals, there is also potential for breakthroughs on
problems of considerable practical interest.
sis, alkane elimination,12 and amine elimination.13 Of
these, alkane elimination conveniently provides orga-
nometallic derivatives directly and avoids the problems
with salt occlusion that beset salt elimination routes.
To date, the thermally unstable trialkyl complexes
We have recently introduced the uninegative â-di-
ketiminato ligand framework into organoscandium chem-
istry4 and made significant inroads in the chemistry of
organoscandium cations.5 However, for reasons that are
not yet entirely clear, we have been unable to enlist this
ligand for use in analogous organoyttrium chemistry.
In considering alternatives, we turned to a bulky
salicylaldiminato ligand recently employed in nickel-
based olefin polymerization catalysts by Grubbs et al.,6
I. This general ligand family has also found recent
[M(CH2SiMe3)3(THF)2]14 (M ) Sc, 1-ScMe; M ) Y, 1-YMe
)
are the most widely used starting materials for alkane
elimination and are usually prepared in situ. However,
use of more bulky CH2SiMe2Ph groups has allowed us
to prepare the thermally more robust analogues [M(CH2-
SiMe2Ph)3(THF)2] (M ) Sc, 1-ScP h ; M ) Y, 1-YP h ),
which are isolable in excellent yields (Sc, 75%; Y, 87%)
as crystalline solids. These tris(alkyls) are stable at 45
°C (24 h) in d8-toluene, but after 24 h at 65 °C,
decomposition resulted to give Me3SiPh and an uniden-
tified, insoluble brown precipitate.
These new tris(alkyl) complexes are amenable to
large-scale synthesis (g2 g) and may be stored indefi-
nitely at -35 °C. Their availability allows for quick
screening of reaction conditions via NMR-tube-scale
experiments and for better control of reaction stoichi-
ometry in preparatory-scale reactions. The -CH2SiMe2-
Ph groups have also been found to impart higher
stability to LMR2 and L2MR complexes and generally
lead to lower solubility and increased crystallinity in
the products. Disadvantages are that LiCH2SiMe2Ph is
not commercially available and the Me3SiPh byproduct
of alkane elimination reactions is less volatile than
SiMe4 (bp 170 vs 27 °C), although of similarly high
solubility.
In toluene solution, complexes 1-MP h exist as a single
isomer (+40 to -80 °C) in which all three alkyl groups
are equivalent, implying a trigonal-bipyramidal geom-
etry with THF axially coordinated. The solid-state
structure of the scandium complex 1-ScMe is consistent
with the solution data, showing a nearly regular trigonal
bipyramid (O-Sc-O ) 175.43(5)°, C(1)-Sc-C(10) )
119.23(8)°, C(10)-Sc-C(19) ) 119.91(7)°, C(19)-Sc-
C(1) ) 120.86(8)°) with the equatorial alkyl groups
arranged in a pinwheel array (Figure 1). The Sc-C bond
lengths (2.248(2), 2.250(2), and 2.254(2) Å) are es-
sentially identical and fall within the usual range for
Sc-C bonds.,4a,15-17 In contrast, the Sc-O bond lengths
application in catalysts based on Cr(III)7 and Ti(IV)8 and
in the Zr(IV)-based Mitsui catalysts.9 Key design fea-
tures of the specific ligand I include the ubiquitous 2,6-
diisopropylaryl groups on the aldimine nitrogen to block
space above and below the ligand plane and the bulky
ortho tert-butyl group on the phenoxide portion of the
ligand. The latter feature provides steric bulk which lies
in the chelating plane of the ligand near the metal
center.
Herein we describe the coordination chemistry of this
ligand with both organoscandium and yttrium deriva-
tives. While synthesis of a lanthanum salicylaldiminato
complex has been described some time ago,10 the
compounds reported here are the first organometallic
group 3 compounds supported by the salicylaldiminato
ligand ancillary. We use an alkane elimination ligand
attachment procedure and also describe some useful
new scandium and yttrium tris(alkyl) derivatives for use
as starting materials in such procedures. Part of this
work has been communicated.11
Resu lts a n d Discu ssion
Tr is(a lk yl) Com p lexes. Three main protocols exist
for ligand attachment to group 3 metals: salt metathe-
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(12) (a) Mu, Y.; Piers, W. E.; MacQuarrie, D. C.; Zaworotko, M. J .;
Young, V. G. Organometallics 1996, 15, 2720. (b) Putzer, M. A.; Rogers,
J . S.; Bazan, G. C. J . Am. Chem. Soc. 1999, 121, 8112. (c) Schaverien,
C. J .; Meijboom, N.; Orpen, A. G. J . Chem. Soc., Chem. Commun. 1992,
124.
(13) (a) Mu, Y.; Piers, W. E.; MacDonald, M. A.; Zaworotko, M. J .
Can. J . Chem. 1995, 73, 2233. (b) Gorlitzer, H. W.; Spiegler, M.;
Anwander, R. Eur. J . Inorg. Chem. 1998, 1009. (c) Anwander, R.;
Gorlitzer, H. W.; Gerstberger, G.; Palm, C.; Runte, O.; Spiegler, M. J .
Chem. Soc., Dalton Trans. 1999, 3611.
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126.
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Appl. Chem. 1991, 63, 845. (b) Fryzuk, M. D.; Haddad, T. S.; Rettig,
S. J . Organometallics 1991, 10, 2026. (c) Fryzuk, M. D.; Haddad, T.
S.; Rettig, S. J . Organometallics 1992, 11, 2967. (d) Fryzuk, M. D.;
Love, J . B.; Rettig, S. J . J . Am. Chem. Soc. 1997, 119, 9071. (e) Fryzuk,
M. D.; Giesbrecht, G. R.; Rettig, S. J . Can. J . Chem. 2000, 78, 1003.
(f) Fryzuk, M. D.; J afarpour, L.; Kerton, F. M.; Love, J . B.; Rettig, S.
J . Angew. Chem., Int. Ed. 2000, 39, 767. (g) Fryzuk, M. D.; J afarpour,
L.; Kerton, F. M.; Love, J . B.; Patrick, B. O.; Rettig, S. J . Organome-
tallics 2001, 20, 1387. (h) Fryzuk, M. D.; Yu, P.; Patrick, B. O. Can. J .
Chem. 2001, 79, 1194.
(9) Matsui, S.; Mitani, M.; Saito, J .; Tohi, Y.; Makio, H.; Matsukawa,
N.; Takagi, Y.; Tsure, K.; Nitabaru, M.; Nakano, T.; Tanaka, H.;
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625, 1777.

4228 Organometallics, Vol. 21, No. 20, 2002
Emslie et al.
Sch em e 1
F igu r e 1. Molecular structure of 1-ScP h (hydrogen atoms
omitted for clarity; thermal ellipsoids drawn to 50% prob-
ability level). Selected bond distances (Å) and angles
(deg): Sc-C(1) ) 2.248(2), Sc-C(10) ) 2.254(2), Sc-C(19)
) 2.2498(19), Sc-O(1) ) 2.1966(14), Sc-O(2) ) 2.2252-
(14); O(1)-Sc-O(2) ) 175.43(5), C(1)-Sc-C(10) ) 119.23-
(8) C(10)-Sc-C(19) ) 119.91(7), C(19)-Sc-C(1) ) 120.86-
(8), O(1)-Sc-C(1) ) 90.38(7), O(1)-Sc-C(10) ) 90.68(7),
O(1)-Sc-C(19) ) 88.25(7), O(2)-Sc-C(1) ) 90.80(7),
O(2)-Sc-C(10) ) 91.76(7), O(2)-Sc-C(19) ) 87.19(6).
(4-YP h ; see below), and Me3SiPh (resulting from thermal
F igu r e 2. Selected regions of the 100 MHz 13C NMR
spectra of 2-YP h at 0 and -70 °C.
decomposition of [Y(CH2SiMe2Ph)3(THF)2]), which were
1
identified by H NMR spectroscopy. The sterically less
protected CH2SiMe3 complex 2-YMe is not as stable and
undergoes redistribution at room temperature.
are different (∆ ) 0.0244(14) Å) but fall within the range
of reported Sc-OTHF bond distances, 2.181(2)-2.228(5)
Å.4a,16,17
Attempts to form related mono(ligand) compounds of
scandium by similar procedures gave mixtures contain-
ing mainly unreacted tris(alkyl) complex and bis(ligand)
derivatives [L2Sc(CH2SiMe2R)], along with small amounts
of [LSc(CH2SiMe2R)2(THF)x]. The inaccessibility of bis-
(alkyl) complexes of scandium with this donor is due
either to rapid ligand redistribution or to competitive
reaction of the mono(ligand) complex with a second
equivalent of protio ligand I. This situation prevented
isolation of the scandium dialkyls analogous to 3-YR.
Mon o(liga n d ) Bis(a lk yl) Com p lexes. Alkane elimi-
nation from the reactions of [Y(CH2SiMe2R)3(THF)2] (1-
YR) with 1 equiv of the protio salicylaldimine ligand I
proceeds in hexane at temperatures below 0 °C and
results in precipitation of a pale yellow solid identified
as the mono(ligand) bis(THF) stabilized dialkyl deriva-
tives [LY(CH2SiMe2R)2(THF)2] (2-YR) (Scheme 1). The
THF ligands in complex 2-YP h are more labile, and
under slightly different reaction conditions the five-
coordinate mono(THF) adduct [LY(CH2SiMe2Ph)2(THF)]-
(3-YP h ) was obtained. The complex 3-YP h was also
formed by dissolution of 2-YP h in toluene, followed by
evaporation to dryness; heating solid 2-YP h for 3 days
at 40 °C under vacuum resulted in incomplete removal
of THF (∼1.2 equiv remained) and some accompanying
decomposition. The complexes 2-YP h and 3-YP h are
thermally stable in solution at room temperature but
undergo clean ligand redistribution upon heating to 60
°C to give the bis(ligand) complex [L2Y(CH2SiMe2Ph)]
Due to the lability of the THF ligands, the six-
coordinate organoyttrium complex 2-YP h shows time-
averaged 1H NMR spectra at 25-40 °C, but at lower
temperatures the spectra resolve into a pattern consis-
tent with the presence of two isomers in a 1:1 ratio. The
low-temperature 13C spectrum (Figure 2) clearly shows
that, in one isomer, the two THF molecules are equiva-
lent and the CH2SiMe2R groups are inequivalent (iso-
mer A), while in the second isomer B, the situation is
reversed. This is only consistent with the trans,cis
isomers shown in Scheme 1, since any of the less

Organometallic Complexes of Scandium and Yttrium
Organometallics, Vol. 21, No. 20, 2002 4229
F igu r e 4. Selected regions of the 100 MHz 13C NMR
spectra of 3-YP h at 25 and -60 °C.
F igu r e 3. Molecular structure of 2-YP h (hydrogen atoms
omitted for clarity; thermal ellipsoids drawn to 50% prob-
ability level). Selected bond distances (Å) and angles
(deg): Y-C(24) ) 2.430(6), Y-C(33) ) 2.440(5), Y-O(1) )
2.166(3), Y-O(2) ) 2.358(4), Y-O(3) ) 2.363(4), Y-N(1)
) 2.661(4); O(3)-Y-O(2) ) 168.32(13), O(1)-Y-C(33) )
151.83(16), N(1)-Y-C(24) ) 175.28(18), O(3)-Y-C(24) )
94.25(18), O(3)-Y-C(33) ) 96.70(17), O(3)-Y-N(1) )
90.14(13), O(3)-Y-O(1) ) 84.04(13), O(2)-Y-C(24) )
89.70(18), O(2)-Y-C(33) ) 93.64(17), O(2)-Y-N(1) )
86.32(13), O(2)-Y-O(1) ) 84.29(13), C(24)-Y-C(23) )
97.79(19), C(33)-Y-N(1) ) 79.95(16), N(1)-Y-O(1) )
71.88(13), O(1)-Y-C(24) ) 110.27(17).
symmetric cis,cis isomers would result in more complex
spectra. Since both isomers are Cs symmetric, in the low-
1
temperature H NMR spectrum, each isomer gives rise
F igu r e 5. Molecular structure of 3-YP h (hydrogen atoms
omitted for clarity; thermal ellipsoids drawn to 50% prob-
ability level). Selected bond distances (Å) and angles
(deg): Y-C(24) ) 2.404(2), Y-C(33) ) 2.398(2), Y-O(1) )
2.1212(14), Y-O(2) ) 2.3761(14), Y-N(1) ) 2.4655(16);
O(1)-Y-O(2) ) 160.37(5), O(1)-Y-N(1) ) 73.89(5), O(1)-
Y-C(24) ) 97.67(7), O(1)-Y-C(33) ) 95.75(7), O(2)-Y-
N(1) ) 86.86(5), O(2)-Y-C(24) ) 90.43(6), O(2)-Y-C(33)
) 98.00(7), N(1)-Y-C(24) ) 125.92(6), C(24)-Y-C(33) )
110.96(7), C(33)-Y-N(1) ) 122.91(6).
to one CHMe2 and two CHMe2 signals. The solid-state
structure of the cis-alkyl isomer of 2-YP h (isomer A,
Figure 3) further supports this assignment. On the basis
of the behavior of the mono(THF) compound 3-YP h , the
interconversion of the isomers of six-coordinate 2-YP h
most likely involves THF dissociation to transiently
yield the fluxional five-coordinate compound.
Trigonal-bipyramidal 3-YP h also exists as a mixture
of two isomers in solution, which are in rapid equilib-
rium at 0 °C but are in slow exchange at low temper-
ature (Figure 4). Again, the CH2SiMe2Ph groups are
inequivalent in one isomer and equivalent in the other.
Of the possible trigonal-bipyramidal isomers, only A and
B (Scheme 1) are likely, considering the preference of
the salicylaldimine ligand to adopt bite angles of 70-
80° and the preference for more electronegative donors
to occupy axial sites of a trigonal bipyramid. Indeed,
this assignment is supported by the solid-state structure
of 3-YP h , isomer A (Figure 5).
Bis(liga n d ) Mon o(a lk yl) Com p lexes: Syn th esis
a n d Th er m a l Decom p osition . Elimination of 2 equiv
of Me3SiR (R ) Me, Ph) from 1-MR and I at room
temperature gave the bright yellow, THF-free complexes
[L2M(CH2SiMe2R)] (M ) Sc, R ) Me, 4-ScMe; M ) Sc,
R ) Ph, 4-ScP h ; M ) Y, R ) Ph, 4-YP h ) in good yields
(Scheme 2). The least sterically congested derivative
combining CH2SiMe3 with yttrium could not be pre-
pared in suitable purity due to competitive formation
of the tris(ligand) complex [L3Y], (8-Y, see below), even
at low temperature. In contrast to the bis(alkyl) com-
plexes 2-MR and 3-MR, there is no evidence for ligand
In the structures of both 2-YP h and 3-YP h , the ligand
bite angle is considerably less than 90° (71.88(13) and
73.89(5)°, respectively), resulting in distortion from ideal
octahedral or trigonal-bipyramidal geometries. The Y-C
bond lengths (2.440(5) and 2.30(6) Å for 2-YP h and
2.398(2) and 2.404(2) Å for 3-YP h ) are similar to those
of the previously reported dialkyl yttrium complexes.18
(18) (a) Evans, W. J .; Broomhall-Dillard, R. N. R.; Ziller, J . W.
Organometallics 1996, 15, 1351. (b) Lee, L.; Berg, D. J .; Einstein, F.
W.; Batchelor, R. J . Organometallics 1997, 16, 1819. (c) Bambirra, S.;
van Leusen, D.; Meetsma, A.; Hessen, B.; Teuben, J . H. Chem.
Commun. 2001, 637.

4230 Organometallics, Vol. 21, No. 20, 2002
Emslie et al.
Sch em e 2
redistribution processes stemming from the mono(alkyl)
complexes 4-MR.
In solution, all three isolated [L2M(CH2SiMe2R)]
complexes exist as a single isomer (60 to -80 °C) in
which both salicylaldimine ligands are equivalent. The
F igu r e 6. Molecular structure of 4-ScMe (hydrogen atoms
omitted for clarity; thermal ellipsoids drawn to 50% prob-
ability level). See Table 1 for selected bond distances and
angles.
geometry was established by the solid-state structures
11
of both 4-ScMe (Figure 6) and 4-YP h
,
which are
isostructural, although the yttrium complex is more
distorted from ideal trigonal-bipyramidal geometry due
to the decreased bite angle of the salicylaldimine ligand
around the larger metal. Metrical data for the two
complexes are given in Table 1. The M-N and M-O
bond lengths are comparable to those of the related
complexes, but the M-C bond lengths are at the shorter
end of the scale for neutral group 3 mono(alkyl) com-
plexes (Sc-C ) 2.243(8)-2.271(7) Å14-16,19 and Y-C )
2.35(1)-2.45(2) Å18,20), perhaps because of the relatively
low coordination number in these compounds.
reaction has precedence in organometallic complexes of
aldimine based ligands.21 Likely the two aryl isopropyl
groups block the path of 1,2-migration insertion by
protecting both faces of the imine CdN moiety (Figure
6).
Red crystals of 5-Sc were characterized by X-ray
crystallography (Figure 7). The structure exhibits dis-
torted-tetrahedral geometry at scandium with one intact
salicylaldimine ligand as well as the phenoxyamido
ligand containing the newly formed C(40)-C(41) bond.
The polycyclic nature of this ligand results in twisting
of the isopropyl-substituted aryl group on N(2) directly
toward O(1), distorting the O(1)-Sc-N(2) angle to
148.17(12)°. The relative stereochemistry in 5-Sc, at Sc,
C(40)),and C(42) is RSR/SRS.
Complexes 4-MR are remarkably thermally stable in
solution, decomposing slowly at 140 °C (total decompo-
sition after 3 days). For scandium, this process occurs
cleanly with loss of Me3SiR to give the unusual brick
red product 5-Sc (Scheme 2), but for yttrium an
analogous product, though detected in the 1H NMR
spectrum, undergoes further undefined chemistry. The
1H NMR spectrum of 5-Sc is consistent with a structure
resulting from metalation of a ligand isopropyl methyl
group to give the undetected intermediate shown in
Scheme 2, followed by a 1,2-migration insertion of this
newly formed alkyl group to the aldimine carbon.
Connectivities were established using homodecoupling,
2D-COSY, and HMQC NMR experiments, and within
Rea ction s of Com p ou n d s 4-MR w ith Hyd r ogen .
The yttrium bis(ligand) complex 4-YP h reacts cleanly
with H2 (4 atm, 24 h, 25 °C) to give a 90% isolated yield
of the bridging hydride dimer [L2Y(µ-H)2YL2] (6-Y;
Scheme 3), which was characterized by both spectros-
copy and X-ray crystallography. Complex 6-Y is also
formed, albeit less cleanly, from 4-YP h and H3SiPh.22
In d8-toluene solution, the dimeric nature of the
hydride is demonstrated by the observation of a triplet
1
the detection limits of H NMR spectroscopy, the reac-
1
at δ 7.54 ppm in the H NMR spectrum (1J H,Y ) 32 Hz)
tion is >97% diastereoselective, which is remarkable,
as the product contains three stereocenters. An alterna-
tive decomposition pathway involving migration of the
CH2SiMe2R group to the aldimine carbon was not
observed for compounds 4-MR, even though this type of
for the bridging hydrides. The pattern of resonances for
the ligands indicate that they are equivalent and the
spectrum is invariant between +25 and -80 °C. Thus,
complex 6-Y exists as a single diastereomer, and al-
though the NMR data are not able to distinguish
(19) (a) Thompson, M. E.; Baxter, S. M.; Bulls, A. R.; Burger, B. J .;
Nolan, M. C.; Santarsiero, B. D.; Schaefer, W. P.; Bercaw, J . E. J . Am.
Chem. Soc. 1987, 109, 203. (b) Arnold, J .; Hoffman, C. G.; Dawson, D.
Y.; Hollander, F. J . Organometallics 1993, 12, 3645. (c) Schaefer, W.
P.; Kohn, R. D.; Bercaw, J . E. Acta Crystallogr., Sect. C 1992, 48, 251.
(d) Schumann, H.; Erbstein, F.; Herrmann, K.; Demtschuk, J .;
Weimann, R. J . Organomet. Chem. 1998, 562, 255.
(20) (a) Hultzsch, K. C.; Voth, P.; Beckerle, K.; Spaniol, T. P.; Okuda,
J . Organometallics 2000, 19, 228. (b) Qian, C.; Zou, G.; Sun, J . J . Chem.
Soc., Dalton Trans. 1999, 519.
(21) Woodman, P. R.; Alcock, N. W.; Munsow, I. J .; Sanders, C. J .;
Scott, P. J . Chem. Soc., Dalton Trans. 2000, 3340.
(22) (a) Gountchev, T. I.; Tilley, T. D. Organometallics 1999, 18,
2896. (b) Gountchev, T. I.; Tilley, T. D. Organometallics 1999, 18, 5661.
(c) Voskoboynikov, A. Z.; Parshina, I. N.; Shestakova, A. K.; Butin, K.
P.; Beletskaya, I. P.; Kuz’mina, L. G.; Howard, J . A. K. Organometallics
1997, 16, 4041. (d) Molander, G. A.; Dowdy, E. D.; Noll, B. C.
Organometallics 1998, 17, 3754. (e) Koo, K.; Fu, P. F.; Marks, T. J .
Macromolecules 1999, 32, 981.

Organometallic Complexes of Scandium and Yttrium
Organometallics, Vol. 21, No. 20, 2002 4231
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles (d eg) for 4-ScMe a n d 4-YP h
param
4-ScMe
4-YP h
param
4-ScMe
4-YP h
M-C(1)
2.196(2)
2.384(2)
O(1)-M-C(1)
O(1)-M-N(1)
O(1)-M-N(2)
O(2)-M-C(1)
O(2)-M-N(1)
O(2)-M-N(2)
M-C(1)-Si
97.34(7)
82.00(5)
88.47(5)
96.65(7)
96.11(6)
79.96(5)
132.94(12)
166.99(15)
-13.5(2)
100.05(9)
77.30(5)
90.62(5)
99.23(7)
97.03(5)
M-O(1)
2.0013(13)
2.0009(13)
2.2450(15)
2.3056(15)
165.90(5)
105.01(5)
137.60(7)
117.39(5)
2.1473(13)
2.1342(13)
2.4238(16)
2.4420(15)
159.93(5)
122.07(6)
116.28(6)
121.58(5)
M-O(2)
M-N(1)
M-N(2)
O(1)-M-O(2)
C(1)-M-N(1)
C(1)-M-N(2)
N(1)-M-N(2)
75.83(5)
131.36(11)
17.54(18)
-165.51(12)
N(1)-M-C(1)-Si
N(2)-M-C(1)-Si
Sch em e 3
approximately 30-40° (O(3)-Y(2)-Y(1)-O(2) ) 40.48-
(8)°; O(4)-Y(2)-Y(1)-O(1) ) 29.95(8)°) in order to
minimize unfavorable steric interactions between the
i
t
opposing ligand Pr and Bu groups, which extend into
the shared space above and below the bridging hydrides.
The bridging hydrides were located from the differ-
ence map and were refined with isotropic thermal
parameters. The Y-H distances of 2.11(3), 2.16(2), 2.25-
(3), and 2.17(3) Å are similar to those of other structur-
ally characterized yttrium hydride complexes, the data
for which are collected in Table 2. While all the yttrium
hydrides listed in Table 2 are dimeric in the solid state,
in solution, monomeric hydrides are accessible via
dissociative cleavage of the dimer in some instances. For
example, a monomer/dimer equilibrium has recently
been investigated by Casey et al. using NMR line-
broadening techniques and by mixing solutions of
[Cp*2Y(µ-H)]2 and [Cp*2Y(µ-D)]2 at low temperature to
observe the formation of [Cp*2Y]2(µ-H)(µ-D).25 While this
is the only hydride dimer for which quantitative infor-
mation concerning dissociation is available, qualitative
evidence for dissociation equilibria in other systems is
apparent in H/D exchange phenomena (Table 2). Most
Cp-donor-containing hydrides appear to undergo dis-
sociation to some extent. In contrast, complex 6-Y
exhibits no evidence for dissociation under any condi-
tions studied. In the 1H NMR spectrum, a triplet is
observed for the µ-H groups from 25 to -80 °C.
Furthermore, when the bridging deuteride [L2Y(µ-D)]2
(d2-6-Y) was synthesized and mixed with protio 6-Y (1:
1, C6D6 or C7D8), no formation of the [L2Y]2(µ-H)(µ-D)
isotopomer (d-6-Y) was observed even after 2 days at
room temperature. The absence of any d-6-Y implies
that dissociation into monomer is not kinetically sig-
nificant in this system and that any reactivity of 6-Y
must occur through the dimer. In keeping with these
F igu r e 7. Molecular structure of 5-Sc (hydrogen atoms
omitted for clarity; thermal ellipsoids drawn to 50% prob-
ability level). Selected bond distances (Å) and angles
(deg): Sc-O(1) ) 1.985(3), Sc-O(2) ) 1.920(3), Sc-N(1)
) 2.204(3), Sc-N(2) ) 2.0303(3), C(10)-N(1) ) 1.293(5),
C(40)-N(2) ) 1.506(5), C(54)-N(2) ) 1.391(5); O(1)-Sc-
N(1) ) 83.11(11), O(2)-Sc-N(2) ) 92.48(12), O(1)-Sc-
O(2) ) 112.98(12), N(1)-Sc-N(2) ) 105.50(13), O(1)-Sc-
N(2) ) 148.17(12), O(2)-Sc-N(1) ) 112.05(12), N(1)-Sc-
O(1)-C(11) ) 20.2(4), Sc-O(1)-C(11)-C(12) ) -22.1(5),
O(1)-C(11)-C(12)-C(10) ) 4.3(5), C(11)-C(12)-C(10)-
N(1) ) 7.2(9), C(12)-C(10)-N(1)-Sc ) -3.8(6), C(10)-
N(1)-Sc-O(1) ) -5.9(3), N(2)-Sc-O(2)-C(44) ) 1.5(3),
Sc-O(2)-C(44)-C(45) ) -22.0(5), O(2)-C(44)-C(45)-
C(40) ) -4.7(5), C(44)-C(45)-C(40)-N(2) ) 60.6(5), C(45)-
C(40)-N(2)-Sc ) -76.5(3), C(40)-N(2)-Sc-O(2) ) 41.7-
(2), C(54)-N(2)-C(40)-C(41) ) -26.0(5), N(2)-C(40)-
C(41)-C(42) ) 53.6(4), C(40)-C(41)-C(42)-C(55) ) -53.(4),
C(41)-C(42)-C(55)-C(54) ) 27.9(5), C(42)-C(55)-C(54)-
N(2) ) -1.6(6), C(55)-C(54)-N(2)-C(40) ) 0.3(5).
between the D2-symmetric rac and the C2h meso isomer,
the rac isomer is most likely favored on steric grounds.
Exclusive dimerization of monomers with the same
stereochemistry has been reported previously.23 This
assignment is supported by the X-ray crystal structure
(Figure 8), which is a rare example of a structurally
characterized non-cyclopentadienyl yttrium hydride.22a,24
As shown in the view given in Figure 8b, the two
O-Y-O vectors are rotated relative to each other by
(23) (a) Mitchell, J . P.; Hajela, S.; Brookhart, S. K.; Hardcastle, K.
I.; Henling, L. M.; Bercaw, J . E. J . Am. Chem. Soc. 1996, 118, 1045.
(b) Yoder, J . C.; Day, M. W.; Bercaw, J . E. Organometallics 1998, 17,
4946.
(24) Duchateau, R.; van Wee, C. T.; Meetsma, A.; vanDuijnen, P.
T.; Teuben, J . H. Organometallics 1996, 15, 2279 and references
therein.
(25) Casey, C. P.; Tunge, J . A.; Lee, T.; Carpenetti, D. W., II.
Organometallics 2002, 21, 389.

4232 Organometallics, Vol. 21, No. 20, 2002
Emslie et al.
suggested that the reactivity patterns of these benz-
amidinato complexes is a result of more ionic metal-
ligand bonding, which contracts the orbitals at the
electropositive metal centers. More polarized M-H
bonds result in robust dimers for these compounds. This
is reflected in the much lower field chemical shifts seen
for the benzamidinato and the salicylaldiminato hy-
drides in comparison to those hydrides more susceptible
to dissociation (Table 2). Likely, in the present salicyl-
aldiminato complexes, the metal-ligand bonding also
has a strong ionic component. The apparently high
steric price paid by dimerization in this bis(salicylald-
iminato) ligand environment and the observed lack of
dissociation into monomeric hydrides in solution is
difficult to reconcile but speaks to the high tendency of
the polarized Y-H moiety to stabilize itself through
dimerization.
Unlike the yttrium alkyls, the reactions of compounds
4-ScR with H2 (4 atm, 24 h, 25 °C) do not yield an
isolable scandium hydride; rather, a product derived
from a 1,3-migration of an incipient hydride to the
aldimine carbon of the ligand is observed (Scheme 3).
Evidently, for scandium, the smaller ionic radius pre-
cludes dimerization. However, the N-aryl isopropyl
groups, while sufficient to block migration of a bulky
alkyl group (vide supra), are not capable of preventing
1,3-hydride migration. In the solid state, 7-Sc adopts a
tetrahedral geometry (Figure 9) with similar Sc-O bond
lengths of 1.9683(11) Å for the monoanionic ligand and
1.9475(11) Å for the dianionic ligand, while the Sc-
Nimine and Sc-Namido bond lengths of 2.1990(13) and
2.0108(13) Å, respectively, are quite different. This
latter bond length is similar to those in other scandium
amido complexes such as [ScCl2(THF)2{N(SiMe3)2}],
which has an Sc-Namido distance of 2.039(2) Å.27
Rea ctivity Su r vey of 6-Y. There are variations in
the reactivity of group 3 and lanthanide µ-hydride
complexes, which depend on the availability of mono-
meric hydride species, the presence or absence of
coordinated solvent, and the steric bulk at the metal
center. For example, [Cp*2Y(µ-H)]2,22e [rac-(C5H2-2-
SiMe3-4-CMe3)2SiMe2)Y(µ-H)]2,28 and [rac-(BnBp)Y(µ-
H)]2 (BnBp ) (C5H2-2-SiMe3-4-CMe3)2Si(OC10H6)2)23a
are active toward olefin polymerization, while [(PhC-
(NSiMe3)2)2Y(µ-H)]224,29 and [(Me2Si(NtBu)(OtBu))2Y(µ-
F igu r e 8. Two views of the molecular structure of 6-Y‚
2(toluene) (toluene and hydrogen atoms other than H(1)
and H(2) omitted for clarity; thermal ellipsoids drawn to
50% probability level). Selected bond distances (Å) and
angles (deg): Y(1)-H(1) ) 2.108(28), Y(1)-H(2) ) 2.162-
(23), Y(2)-H(1) ) 2.245(33), Y(2)-H(2) ) 2.165(28), Y(1)‚
‚‚Y(2) ) 3.634(1), H(1)‚‚‚H(2) ) 2.372(48), Y(1)-O(1) )
2.1511(19), Y(1)-O(2) ) 2.1333(19), Y(2)-O(3) ) 2.1468-
(19), Y(2)-O(4) ) 2.1530(19), Y(1)-N(1) ) 2.508(2), Y(1)-
N(2) ) 2.543(3), Y(2)-N(3) ) 2.556(3), Y(2)-N(4) ) 2.501-
(2); H(1)-Y(1)-H(2) ) 67.49(118), H(1)-Y(2)-H(2) )
65.06(115), O(1)-Y(1)-O(2) ) 162.75(8), N(1)-Y(1)-H(2)
) 155.09(80), N(2)-Y(1)-H(1) ) 151.16(84), O(3)-Y(2)-
O(4) ) 156.68(8), N(3)-Y(2)-H(2) ) 152.72(82), N(4)-
Y(2)-H(1) ) 142.72(75), O(1)-Y(1)-Y(2)-O(4) ) 29.95(8),
O(2)-Y(1)-Y(2)-O(3) ) 40.48(8), N(1)-Y(1)-Y(2)-N(3) )
55.8(1), N(2)-Y(1)-Y(2)-N(4) ) 65.66(10).
30
H)]2 show little or no activity. This qualitatively
correlates with the H/D exchange reactivity discussed
above, suggesting that for ethylene polymerization
efficacy, dissociation into monomer is required. How-
ever, irrespective of olefin polymerization activity, most
yttrium hydride complexes undergo hydroyttration chem-
istry with small molecules such as alkynes, carbonyl
functions, and pyridines. The reactivity in this connec-
tion for 6-Y is summarized in Scheme 4, and these
observations are qualitatively consistent with the notion
that the compound reacts as a dimer, rather than by
observations, 6-Y does not undergo H/D exchange via σ
bond metathesis with deuterated NMR solvents either,
as is often observed in the metallocene systems which
dissociate readily into monomers.24,25 In this regard, 6-Y
exhibits behavior similar to that of the related benz-
amidinato group 3 hydrides [{(PhC(NSiMe3)2)2M(µ-H)}2]
(M ) Sc,26 Y24), which also do not undergo the H/D
scrambling reactions in deuterated solvents. It has been
(26) Hagadorn, J . R.; Arnold, J . Organometallics 1996, 15, 984.
(27) Karl, M.; Seybert, G.; Massa, W.; Dehnicke, K. Z. Anorg. Allg.
Chem. 1999, 625, 375.
(28) CougIin, E. B.; Bercaw, J . E. J . Am. Chem. Soc. 1992, 114, 7606.
(29) Duchateau, R.; van Wee, C. T.; Teuben, J . H. Organometallics
1996, 15, 2291.
(30) (a) Duchateau, R.; Brussee, E. A. C.; Meetsma, A.; Teuben, J .
H. Organometallics 1997, 16, 5506. (b) Duchateau, R.; Tuinstra, T.;
Brussee, E. A. C.; Meetsma, A.; van Duijnen, P. T.; Teuben, J . H.
Organometallics 1997, 16, 3511.

Organometallic Complexes of Scandium and Yttrium
Organometallics, Vol. 21, No. 20, 2002 4233
Ta ble 2. Com p a r ison of Str u ctu r a lly Ch a r a cter ized Dim er ic Yttr iu m Hyd r id e Com p lexes
complex
Y-H bond lengths (Å)
δ(Y-H)a
dissoc
ref
6-Y
2.11(3), 2.16(2), 2.25(3), 2.17(3)
2.19(3), 2.17(3), 2.11(3), 2.16(3)
2.22(4), 2.27(4)
2.235(2), 2.097(2), 2.4(1), 2.0(1)
2.17(8), 2.19(8)
2.48(4), 1.98(6), 2.39(4), 2.31(6)
2.12(6), 2.09(4), 2.12(4), 2.14(7)
2.27(6), 2.03(7)
2.02(6), 2.07(6) & 2.04(6), 2.15(6)
2.10(7), 2.14(7)
7.54
8.28
5.88
5.97
2.02
5.50
2.69
2.82
1.86
5.35e
no
no
yes
yes
[{PhC(NSiMe3)2}Y(µ-H)}2]
23
22a
24a
43b
20a, 43c
43d
43e
43f
43g
[{(NN)Y(thf)(µ-H)}2]b
[{(BnBp)2Y(µ-H)}2]c
[{(C5H4Me)2Y(thf)(µ-H)}2]
[{(Me4C5SiMe2NtBu)Y(thf)(µ-H)}2]
[{(2,4,7-Me3C9H4)2Y(µ-H)}2]
[{(C5H3Me2)2Y(thf)(µ-H)}2]
[{(C5H4CH2CH2OMe)2Y(µ-H)}2]d
[Cp*2Y(µ-H)(µ-CH2C5Me4)YCp*]
yes
yes
yes
a
b
d
In ppm. NN ) bis(silylamido)biphenyl. c BnBp ) (C5H2-2-SiMe3-4-CMe3)2Si(OC10H6)2. Two crystallographically independent
molecules in the unit cell. e Data given is for [Cp*2Y(µ-H)]2, taken from ref 25.
firmed by spectroscopy and via elemental analysis. The
very slow reactions with ethylene and HB(C6F5)2 are
indicative of slow or nonexistent dissociation of 6-Y into
a reactive monomer.
Typically, organoyttrium hydrides catalyze the oligo-
merization of alkynes to give dimers (e.g. HRCdCH-
CtCR), trimers, or higher oligomers.29,32a,33,34 Reaction
of 6-Y with excess HCtCSiMe3 at room temperature
for 3 days gave the monomeric acetylide complex [L2Y-
(CtCSiMe3)]. The monomeric structure of the acetylide
product is indicated by the observation of two doublets
due to the alkynyl carbons in the 13C NMR spectrum (δ
1
163.12 (d, J C,Y ) 72 Hz, R-YCtCR) and δ 108.91 (d,
2J C,Y ) 12.5 Hz, â-YCtCR)). The 1H NMR spectra
indicate the presence (∼10%) of a second species, which
may be a µ-acetylide dimer, since the majority of yttrium
alkynyl complexes are dimeric in solution29,35 unless
stabilized by a coordinating base.29,33,36,37 For the major
1
monomeric acetylide species, H NMR spectra indicate
a trigonal-bipyramidal structure analogous to the struc-
tures of compounds 4-MR. The preference for a mono-
meric structure is a testament to the steric congestion
at the metal center in the bis(salicylaldiminato) ligand
environment. The concurrent production of vinyltri-
methylsilane and the apparent absence of H2 in sealed-
NMR-tube experiments suggest that the first step in
this process is alkyne insertion into Y-H rather than
F igu r e 9. Molecular structure of 7-Sc‚0.5(hexane) (hy-
drogen atoms omitted for clarity; thermal ellipsoids drawn
to 50% probability level). Selected bond distances (Å) and
angles (deg): Sc-O(1) ) 1.9683(11), Sc-O(2) ) 1.9475(11),
Sc-N(1) ) 2.1990(13), Sc-N(2) ) 2.0108(13), Sc-C(24) )
2.6421(17), C(1)-N(1) ) 1.294(2), C(24)-N(2) ) 1.497(2);
O(1)-Sc-N(1) ) 84.58(7), O(2)-Sc-N(2) ) 97.94(5), O(1)-
Sc-O(2) ) 112.20(5), N(1)-Sc-N(2) ) 117.11(5), O(1)-Sc-
N(2) ) 134.64(5), O(2)-Sc-N(1) ) 109.50(5), N(1)-Sc-
O(1)-C(2) ) 24.39(15), Sc-O(1)-C(2)-C(3) ) -22.8(2),
O(1)-C(2)-C(3)-C(1) ) 1.9(3), C(2)-C(3)-C(1)-N(1) )
6.4(3), C(3)-C(1)-N(1)-Sc ) 2.7(2), C(1)-N(1)-Sc-O(1)
) -12.72(13), N(2)-Sc-O(2)-C(25) ) 2.79(12), Sc-O(2)-
C(25)-C(26) ) -23.67(19), O(2)-C(25)-C(26)-C(24) )
-3.8(2), C(25)-C(26)-C(24)-N(2) ) 66.90(18), C(26)-
C(24)-N(2)-Sc ) -78.85(13), C(24)-N(2)-Sc-O(2) )
40.85(10).
2
direct σ-bond metathesis between the Csp -H bond of
the alkyne and Y-H. The alkyne insertion could con-
ceivably involve the dimer, producing an yttrium vinyl
species that then undergoes σ-bond metathesis with
another equivalent of alkyne.
The reactions of 6-Y with a selection of Lewis bases
also imply direct, slow reaction with the dimer to give
(32) (a) Spence, R. E. v H.; Piers, W. E.; Sun, Y.; Parvez, M.;
MacGillivray, L. R.; Zaworotko, M. J . Organometallics 1998, 17, 2459.
(b) Chase, P. A.; Piers, W. E.; Parvez, M. Organometallics 2000, 19,
2040. (c) Iverson, C. N.; Smith, M. R. J . Am. Chem. Soc. 1999, 121,
7696.
(33) Den Haan, K. H.; Wielstra, Y.; Teuben, J . H. Organometallics
1987, 6, 2053.
(34) (a) Haskel, A.; Straub, T.; Dash, A. K.; Eisen, M. J . Am. Chem.
Soc. 1999, 121, 3014. (b) Straub, T.; Haskel, A.; Eisen, M. J . Am. Chem.
Soc. 1995, 1995, 6364. (c) Evans, W. J .; Keyer, R. A.; Ziller, J . W.
Organometallics 1993, 12, 2618. (d) St. Clair, M.; Schaefer, W. P.;
Bercaw, J . E. Organometallics 1991, 10, 525.
(35) (a) Duchateau, R.; van Wee, C. T.; Meetsma, A.; Teuben, J . H.
J . Am. Chem. Soc. 1993, 115, 4931. (b) Lee, L.; Berg, D. J .; Einstein,
F. W.; Batchelor, R. J . Organometallics 1997, 16, 1819. (c) Evans, W.
J .; Meadows, J . H.; Hunter, W. E.; Atwood, J . L. J . Am. Chem. Soc.
1984, 106, 1291. (d) Heeres, H. J .; Teuben, J . H. Organometallics 1991,
10, 1980.
an initial dissociative step to provide reactive monomer.
For example, 6-Y shows no polymerization activity
under 1 atm of ethylene at room temperature and very
low activity under 4 atm. Another reagent which would
be expected to react rapidly with terminal M-H bonds
but slowly with the dimeric structure of 6-Y is the highly
electrophilic borane [HB(C6F5)2]2. This borane itself
readily dissociates into a monomer in aromatic hydro-
carbon solution,31 which rapidly complexes transition-
metal hydrides to give robust hydridoborate M[(µ-
H)2B(C6F5)2] complexes.32 6-Y reacts extremely slowly
(8 days at room temperature) with HB(C6F5)2 to form
[L2Y(µ-H)2B(C6F5)2], the structure of which was con-
(36) Deelman, B. J .; Stevels, W. M.; Teuben, J . H.; Lakin, M. T.;
Spek, A. L. Organometallics 1994, 13, 3881.
(31) Parks, D. J .; Piers, W. E., Yap, G. P. A. Organometallics 1998,
17, 5492.
(37) (a) Schaverien, C. J . Organometallics 1994, 13, 69. (b) Scha-
verien, C. J . J . Chem. Soc., Chem. Commun. 1992, 11.

4234 Organometallics, Vol. 21, No. 20, 2002
Emslie et al.
Sch em e 4
a more reactive monomeric hydride species, which
undergoes insertion or migration to the ligand aldimine
carbon. In an example of the former pathway, reaction
of 6-Y with excess benzophenone gave a bright yellow
solid which was identified as the bis(ligand) alkoxy
ketone compound [trans-L2Y(OCHPh2)(OCPh2)] by ele-
mental analysis, NMR spectroscopy, and X-ray crystal-
lography. The structure is shown in Figure 10, depicting
the trans arrangement of both the alkoxide/ketone
ligands and the salicylaldimine ancillaries. The Y-O(4)
bond to the ketone is longer than the others in the
molecule at 2.444(2) Å, in line with the dative nature
of this bond. A comparison with the related complexes
Cp*2YCl(OdCPh2),38 [Tb{N(SiMe3)2}3(OdCPh2)],39 and
[DyCp3(OdCPh2)],40 which are suitable for comparison
due to the similar ionic radii of Y, Dy, and Tb (0.893,
0.908, and 0.923 Å, respectively41), reveals that the
M-Oketone bond distances for these complexes are
shorter (Y, 2.312(2) Å; Tb, 2.305(9) Å; Dy, 2.384(3) Å)
than Y-Oketone in [L2Y(OCHPh2)(OCPh2)]. This is reflec-
tive of the more severe steric environment in [L2Y-
(OCHPh2)(OCPh2)]. For all four complexes, the M-Od
C angle is approximately linear, ranging from 165.2 to
170.7°, as is common for ligation of carbonyl functions
to d0 metals.42
where 1,3-hydride migration to the ancillary ligand is
more facile. Solution NMR data for these two com-
pounds are consistent with the geometry shown in
Scheme 4, although for the THF adduct, the lability of
the Lewis base indicates somewhat more complicated
behavior due to the accessibility of a fluxional five-
coordinate species.
In summary, the reactivity patterns observed for
yttrium hydride 6-Y indicate that it does not dissociate
into a monomeric hydride, resulting in sluggish reaction
rates in relation to other systems for which dimer
dissociation is more facile. Despite the high steric
congestion associated with the bis(salicylaldimine) ligand
environment in 6-Y, it appears to react primarily as the
dimer with typical small-molecule substrates, although
in the absence of kinetic studies, very slow, rate-limiting
dissociation into reactive monomers cannot be ruled out.
Tr is(liga n d ) Com p lexes. A final aspect of the
chemistry of the group 3 metals Sc and Y with the bulky
salicylaldimine ligand employed here is the tendency
to form nonorganometallic tris(ligand) coordination
complexes L3M. For yttrium, the third ligand is readily
instituted via alkane elimination, necessitating care in
the preparation of the derivatives 4-YR; addition of
another 1 equiv of I gives the tris(ligand) compound 8-Y
in high yield (Scheme 5). This octahedral complex exists
as a single isomer in solution with all three ligands
equivalent on the NMR time scale (25 to -80 °C),
suggesting a facial coordination arrangement of the
ligands. This has been confirmed by X-ray crystal-
lography (Figure 11). The high steric requirements of
Reaction of 6-Y with Lewis bases such as pyridine and
THF give products in which 2 equiv of Lewis base is
taken up, and the yttrium hydride is transferred to
the aldimine carbon of one of the salicylaldimine
ligands. Alternative outcomes such as simple coordina-
tion or activation of the ligated pyridine22a,29,35c,36 or
THF22a,24,33,35c,43 are not operative in the present system,
(43) (a) Deelman, B. J .; Booij, M.; Meetsma, A.; Teuben, J . H.;
Kooijman, H.; Spek, A. L. Organometallics 1995, 14, 2306. (b) Evans,
W. J .; Meadows, J . H.; Wayda, A. L.; Hunter, W. E.; Atwood, J . L. J .
Am. Chem. Soc. 1982, 104, 2008. (c) Hultzsch, K. C.; Spaniol, H. P.;
Okuda, J . Angew. Chem., Int. Ed. 1999, 38, 227. (d) Kretschmer, W.
P.; Troyanov, S. I.; Meetsma, A.; Hessen, B.; Teuben, J . H. Organo-
metallics 1998, 17, 284. (e) Evans, W. J .; Drummond, D. K.; Hanusa,
T. P.; Doedens, R. J . Organometallics 1987, 6, 2279. (f) Deng, D.; J iang,
Y.; Qian, C.; Wu, G.; Zheng, P. J . Organomet. Chem. 1994, 470, 99. (g)
Booij, M.; Deelman, B. J .; Duchateau, R.; Postma, D. S.; Meetsma, A.;
Teuben, J . H. Organometallics 1993, 12, 3531.
(38) Evans, W. J .; Fujimoto, C. H.; J ohnston, M. A.; Ziller, J . W.
Organometallics 2002, 21, 1825.
(39) Zhou, X.; Ma, H.; Wu, Z.; You, X.; Xu, Z.; Zhang, Y.; Huang, X.
Acta Crystallogr., Sect. C 1996, 52, 1875.
(40) Allen, M.; Aspinall, H. C.; Moore, S. R.; Hursthouse, M. B.;
Karvalov, A. I. Polyhedron 1992, 11, 409.
(41) CRC Handbook of Chemistry and Physics; 70th ed.; CRC
Press: Boca Raton, FL, 1989-1990.
(42) Sun, Y.; Piers, W. E.; Yap, G. P. A. Organometallics 1997, 16,
2509.

Organometallic Complexes of Scandium and Yttrium
Organometallics, Vol. 21, No. 20, 2002 4235
F igu r e 11. Molecular structure of 8-Y (hydrogen atoms
omitted for clarity; thermal ellipsoids drawn to 50% prob-
ability level). Selected bond distances (Å) and angles
(deg): Y-O(1) ) 2.133(3), Y-O(2) ) 2.107(3), Y-O(3) )
2.130(3), Y-N(1) ) 2.581(4), Y-N(2) ) 2.694(4), Y-N(3)
) 2.603(4); O(1)-Y-N(3) ) 164.97(12), O(2)-Y-N(1) )
164.22(12), O(3)-Y-N(2) ) 165.04(12), O(1)-Y-O(2) )
91.46(12), O(1)-Y-O(3) ) 91.51(11), O(1)-Y-N(1) )
73.57(11), O(1)-Y-N(2) ) 94.91(11), N(3)-Y-O(2) )
91.97(12), N(3)-Y-O(3) ) 73.71(11), N(3)-Y-N(1) )
103.78(12), N(3)-Y-N(2) ) 100.10(12), O(2)-Y-O(3) )
92.64(12), O(3)-Y-N(1) ) 92.71(12), N(1)-Y-N(2) )
102.05(11), N(2)-Y-O(2) ) 73.74(11).
F igu r e 10. Molecular structure of L2Y(OCHPh2)(OdCPh2)
(hydrogen atoms other than H(70) omitted for clarity;
thermal ellipsoids drawn to 50% probability level). Selected
bond distances (Å) and angles (deg): Y-O(1) ) 2.160(2),
Y-O(2) ) 2.166(2), Y-O(3) ) 2.067(2), Y-O(4) ) 2.444-
(2), Y-N(1) ) 2.509(3), Y-N(2) ) 2.528(3), C(11)-O(1) )
1.316(4), C(41)-O(2) ) 1.313(4), C(70)-O(3) ) 1.404(4),
C(90)-O(4) ) 1.243(4); O(1)-Y-N(1) ) 75.99(9), O(2)-Y-
N(2) ) 75.26(9), O(1)-Y-O(2) ) 167.15(9), N(1)-Y-N(2)
) 170.64(9), O(3)-Y-O(4) ) 178.07(12), Y-O(4)-C(90) )
170.7(3), O(4)-C(90)-C(91) ) 119.3(4), O(4)-C(90)-C(97)
) 119.3(4), C(91)-C(90)-C(97) ) 121.4(3), Y-O(3)-C(70)
) 169.5(2), O(3)-C(70)-C(71) ) 111.4(3), O(3)-C(70)-
C(77) ) 110.6(3), C(71)-C(70)-C(77) ) 116.0(3).
in which none of the ligands are related by symmetry.
Given the apparent tendency toward imine dissociation
in 8-Y, it seemed likely that the analogous scandium
complex 8-Sc might be a five-coordinate [(κ2-L)2(κ1-L)]-
Sc species in which the imine arm of the third ligand is
completely dissociated. This species is a bulky phenoxy
analogue of the alkyl complex 4-ScMe, which exists as
a single isomer with the alkyl group in an equatorial
position. Therefore, a similar arrangement is expected
for 8-Sc, and it is likely that the two isomers seen in
solution at low temperature result from hindered rota-
tion of the bulky κ1(O)-salicylaldimine group. 2-D COSY
Sch em e 5
1
NMR experiments allow for assignment of the H NMR
spectrum of 8-Sc at -20 °C and support this interpreta-
tion of the data. Finally, the X-ray crystal structure of
8-Sc shows that the molecule is indeed trigonal bipy-
ramidal with one ligand κ1(O)-coordinated in an equato-
rial position and the noncoordinated imine group angled
away from the metal center (Figure 12). The metrical
data for this compound are unremarkable.
the ligand are reflected in the Y-N distances, which
show that the imine moiety of one of the ligands is less
tightly coordinated than the other two (Y-N(1) ) 2.581-
(4) Å, Y-N(2) ) 2.694(4) Å, and Y-N(3) ) 2.603(4) Å).
To compensate, the Y-O bond length of this same ligand
(Y-O(2) ) 2.107(3) Å) is slightly shorter than that of
the other two ligands (Y-O(1) ) 2.133(3) Å, Y-O(3) )
2.130(3) Å).
Con clu sion s
In contrast to the facile synthesis of 8-Y, there was
no reaction observed between 4-ScMe and I at room
temperature. Under forcing conditions, (80 °C for 4 days)
The organometallic chemistry of the group 3 metals
scandium and yttrium as supported by a bulky salicyl-
aldiminato ligand has been explored. Both mono- and
bis(ligand) complexes of yttrium were prepared via
alkane elimination protocols and characterized, while
only the bis(ligand) derivatives of scandium were found
to be chemically well-behaved enough for detailed study.
1
a new product with a broad room-temperature H NMR
spectrum was formed. Investigation of this product by
variable-temperature NMR spectroscopy gave a sharp
spectrum at -20 °C, which was consistent with the
presence of an approximately 1:1 mixture of two isomers

4236 Organometallics, Vol. 21, No. 20, 2002
Emslie et al.
Fischer Scientific Ultrasonic FS-14 bath was used to sonicate
reaction mixtures where indicated. The ligand I was prepared
by a literature procedure. Complexes 1-MMe were generated
in situ from MCl3‚nTHF and LiCH2SiMe3 (Sigma-Aldrich).
LiCH2SiMe2Ph was prepared via a modification of the previ-
ously reported literature procedure.45 All other materials were
obtained from Sigma-Aldrich and purified according to stan-
dard procedures. X-ray crystallographic analyses were per-
formed on suitable crystals coated in Paratone oil and mounted
on either a Bruker P4/RA/SMART 1000 CCD diffractometer
(University of Alberta) or a Rigaku AFC6S diffractometer
(University of Calgary). Details of the crystallographic data
and data analysis are given in Table 3; full details can be found
in the Supporting Information.
Syn th esis of LiCH2SiMe2P h . Me2PhSiCH2Cl (7.8 g, 42
mmol) was added to a slurry of Li powder (0.5% Na; 880 mg,
127 mmol) in toluene (50 mL) at room temperature. The
mixture was then stirred at 75 °C for 2-3 days before being
filtered, and the residue was washed twice with toluene. The
resulting orange solution was evaporated to dryness in vacuo,
slurried in n-hexane (10 mL), sonicated, cooled to -78 °C, and
filtered to collect a yellow-white solid which was washed with
a small volume of cold n-hexane. The resulting cream white
1
solid was dried in vacuo for 1 h. Yield: 4.6 g (59%). H NMR
(C6D6): δ 7.55-7.50 (m, 2H, Ph), 7.27-7.15 (m, 3H, Ph), 0.24
(s, 6H, SiMe2), -2.42 (s, 2H, LiCH2).
F igu r e 12. Molecular structure of one of the two crystal-
lographically independent molecules of 8-Sc‚0.5(hexane)
(hydrogen atoms and hexane omitted for clarity; thermal
ellipsoids drawn to 50% probability level). Selected bond
distances (Å) and angles (deg): Sc(1)-O(1) ) 1.972(2), Sc-
(1)-O(2) ) 1.998(2), Sc(1)-O(3) ) 1.959(2), Sc(1)-N(1) )
2.257(2), Sc(1)-N(2) ) 2.2.265(3); O(1)-Sc(1)-O(2) )
161.79(9), O(1)-Sc(1)-N(1) ) 81.34(9), O(1)-Sc(1)-N(2)
) 86.74(7), O(1)-Sc(1)-O(3) ) 94.15(9), O(2)-Sc(1)-N(1)
) 92.52(9), O(2)-Sc(1)-N(2) ) 80.34(9), O(2)-Sc(1)-O(3)
) 103.75(9), O(3)-Sc(1)-N(1) ) 119.43(9), N(1)-Sc(1)-
N(2) ) 115.05(9), N(2)-Sc(1)-O(3) ) 124.99(9).
[Sc(CH2SiMe2P h )3(THF )2] (1-ScP h ). A mixture of [ScCl3-
(THF)3] (1.00 g, 2.72 mmol) and LiCH2SiMe2Ph (1.28 g, 8.16
mmol) in toluene (40 mL) was stirred for 6 h at 0 °C and then
evaporated to dryness in vacuo. After addition of n-hexane (70
mL), the mixture was sonicated to break up the solid and
filtered to give a clear solution. This was concentrated in vacuo
(ca. 5 mL) and then cooled to -78 °C to precipitate a white
solid which was collected by filtration. Yield: 1.29 g (75%).
X-ray-quality crystals were grown by cooling an n-hexane
1
solution to -40 °C. H NMR (C6D6): δ 7.74 (dd, 6H, J ) 7, 1
Hz, o-Ph), 7.27 (ddd, 6H, J ) 7, 7, 1 Hz, m-Ph), 7.18 (tt, 3H,
J ) 7, 1 Hz, p-Ph), 3.77, 1.15 (m, 2 × 8H, THF), 0.44 (s, 18H,
SiMe2Ph), -0.11 (s, 6H, Sc-CH2). 13C{1H} NMR (C6D6):
δ
Although this ancillary ligand provides an adequate
level of steric stabilization for even the larger yttrium
nucleus, these compounds show reactivity patterns with
similarities to other noncyclopentadienyl organoscan-
dium and yttrium complexes. For example, hydro-
genolysis reactions of the alkyl derivatives 4-MR proceed
slowly to give hydrides due to the electropositive nature
of the metal centers. The putative monomeric hydride
products of these reactions undergo either rapid hydride
transfer to the aldimine carbon of one of the ancillary
ligands (M ) Sc) or effectively irreversible dimerization
(M ) Y). This behavior results in sluggish reactivity
toward small molecules for 6-Y. Finally, for the larger
metal, facile formation of tris(ligand) coordination com-
plexes is possible when excess ligand is present.
146.34 (s, quaternary aromatic), 134.30, 128.47, 128.12 (s, 3
Ph), 71.75 (s, THF), 37.0 (broad s, Y-CH2), 25.35 (s, THF),
3.18 (s, SiMe2Ph). Anal. Calcd for C35H55O2Si3Sc: C, 65.99; H,
8.70. Found: C, 64.89; H, 8.80.
[Y(CH2SiMe2P h )3(THF )2] (1-YP h ). A procedure identical
with that described above using a mixture of [YCl3(THF)3.5
]
(1.00 g, 2.23 mmol) and LiCH2SiMe2Ph (1.05 g, 6.70 mmol)
1
was employed to yield 1.32 g (87%) of 1-YP h . H NMR (C6D6):
δ 7.74 (dd, 6H, J ) 8, 1 Hz, o-Ph), 7.28 (ddd, 6H, J ) 7, 7, 1
Hz, m-Ph), 7.18 (tt, 3H, J ) 8, 1 Hz, p-Ph), 3.63, 1.11 (m, 2 ×
2
8H, THF), 0.45 (s, 18H, SiMe2Ph), -0.52 (d, 6H, J H,Y ) 3 Hz,
Y-CH2). 13C{1H} NMR (C6D6): δ 146.98 (s, quaternary aro-
matic), 134.27, 128.39, 128.16 (s, 3 Ph), 71.21 (s, THF), 31.97
1
(d, J C,Y ) 35 Hz, Y-CH2), 25.27 (s, THF), 3.54 (s, SiMe2Ph).
Anal. Calcd for C35H55O2Si3Y: C, 61.73; H, 7.08. Found: C,
58.26; H, 6.83.
[LY(CH 2SiMe3)2(TH F )2] (2-YMe). A mixture of [YCl3-
(THF)3.5] (0.84 g, 1.88 mmol) and LiCH2SiMe3 (0.53 g, 5.63
mmol) in n-hexane (30 mL) was stirred for 4 h at 0 °C and
then filtered to give a colorless solution of [Y(CH2SiMe3)3-
(THF)x]. After the mixture was cooled to -78 °C, a solution of
I (0.63 g, 1.88 mmol) in cold n-hexane (20 mL) was added and
the temperature was raised to 0 °C for 30 min. The resulting
yellow solid was collected by filtration and washed with
n-hexane (×2). Yield: 0.92 g (66%). 1H NMR (d8-toluene, 25
°C): δ 7.94 (s, 1H, CH(NAr)), 7.44 (d, 1H, J ) 7 Hz, Ph), 7.12-
7.03 (m, 3H, Ph), 6.84 (d, 1H, J ) 7 Hz, Ph), 6.57 (t, 1H, J )
7 Hz, Ph), 3.69 (s, 8H, THF), 2.94 (septet., 2H, CHMe2), 1.67
(s, 9H, CMe3), 1.34 (m, 8H, THF), 1.25, 0.94 (d, 2 × 6H, J ) 6
Exp er im en ta l Section
Gen er a l P r oced u r es. All operations were performed under
a purified argon atmosphere using glovebox or vacuum line
techniques. Toluene, hexane, and THF solvents were dried and
purified by passing through activated alumina and Q5 col-
umns.44 NMR spectra were recorded in dry, oxygen-free C6D6,
1
2
unless otherwise noted. H, H, 13C{1H}, HMQC, DEPT, and
COSY NMR experiments were performed on Bruker AC-200,
AMX-300, and WH-400 or Varian 200 MHz spectrometers.
Data are given in ppm relative to solvent signals for 1H and
13C spectra. Elemental analyses were performed by Mrs.
Dorothy Fox or Ms. Roxanna Simank of this department. A
(44) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.;
Timmers, F. J . Organometallics 1996, 15, 1518.
(45) Bruno, J . W.; Smith, G. M.; Marks, T. J .; Fair, C. K.; Schultz,
A. J .; Williams, J . M. J . Am. Chem. Soc. 1986, 108, 40.

Organometallic Complexes of Scandium and Yttrium
Organometallics, Vol. 21, No. 20, 2002 4237
Ta ble 3. Su m m a r y of Da ta Collection a n d Str u ctu r e Refin em en t Deta ils
1-ScP h
2-YP h
3-YP h
4-ScMe
5-Sc
formula
fw
C
35H55O2ScSi3
C49H72NO3Si2Y
868.17
C45H64NO2Si2Y
796.06
C50H71N2O2ScSi
805.14
C46H59N2O2Sc
716.91
637.02
cryst syst
a, Å
b, Å
monoclinic
16.9753(3)
13.0885(3)
17.0669(4)
monoclinic
22.7450(3)
9.8118(1)
monoclinic
21.5355(2)
11.0719(1)
37.1685(4)
monoclinic
11.9830(7)
17.6241(10)
22.7220(13)
monoclinic
11.2423
20.2909
c, Å
23.0596(4)
18.3725
R, deg
â, deg
γ, deg
V, Å3
94.012(1)
105.621(1)
93.6312
91.0259(11)
100.568(1)
3782.65(14)
P21/c
4
1.119
0.32
0.044
0.094
0.111
1.03
4956.12(12)
P21/c
4
1.164
1.26
0.091
0.207
0.221
1.15
8844.62
C2/c
8
1.196
1.41
0.037
0.082
0.091
1.01
4797.9(5)
P21/c
4
1.115
0.216
0.0468
0.1339
0.211
1.029
4119.98(19)
P21/c
4
1.156
0.217
0.079
0.162
0.153
1.00
space group
Z
d
calcd, mg m-3
µ, mm-1
R1
wR2
wR2 (all data)
GOF
6-Y
7-Sc
L2Y(OCHPh2)(OdCPh2)
8-Y
8-Sc
formula
fw
cryst syst
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
C
106H138N4O4Y2
C49H68N2O2Sc
762.01
C72H81N2O4Y
1127.30
triclinic
11.8539(2)
11.8956(2)
13.2843(2)
105.608(1)
116.443(1)
101.171(1)
1504.82(4)
P1h
C69H90N3O3Y
1098.35
monoclinic
13.065(1)
22.8064(18)
21.3288(17)
98.106(1)
106.4928(18)
105.357(1)
6093.8(8)
P21/n
C72H97N3O3Sc
1075.94
triclinic
13.1532(2)
21.9728(3)
23.6174(3)
1710.02
triclinic
13.5187(1)
18.9396(2)
20.8165(3)
80.2648(4)
78.9598(4)
83.2781(7)
5136.08(10)
P1h
triclinic
10.8442(2)
12.4440(2)
18.4372(3)
102.259(1)
99.938(1)
103.838(1)
2294.37(7)
P1h
91.425(1)
6502.40(16)
P1h
4
1.099
0.16
0.072
0.140
space group
Z
2
2
1
4
d
calcd, mg m-3
1.106
1.17
0.053
0.138
1.103
0.20
0.053
0.130
1.244
1.020
0.055
0.119
1.197
1.005
0.0664
0.1505
µ, mm-1
R1
wR2
wR2 (all data)
GOF
0.147
1.05
0.122
1.06
0.182
0.907
1.03
0.97
Hz, CHMe2), 0.23 (s, 18H, SiMe3), -0.54 (broad s, 4 H, YCH2).
13C{1H} NMR (d8-toluene, 0 °C): δ 174.28 (s, CH(NAr)), 166.88,
150.8 (b), 140.93, 140.31 (s, four quaternary aromatic), 135.71,
133.79, 126.94, 124.34 (s, 4 Ph), 123.05 (s, quaternary aro-
matic), 116.40 (s, Ph), 70.67 (s, THF), 35.91 (s, CMe3), 32.0 (v
weak s, YCH2), 30.59 (s, CMe3), 28.92 (s, CHMe2), 26.18 (s,
CHMe2), 25.60 (s, THF), 23.19 (s, CHMe2), 5.06 (s, SiMe3). Anal.
Calcd for C39H68NO3SiY: C, 62.96; H, 9.21; N, 1.88. Found:
C, 60.32; H, 8.44; N, 2.03.
[LY(CH2SiMe2P h )2(THF )2] (2-YP h ). A mixture of [Y(CH2-
SiMe2Ph)3(THF)2] (0.2 g, 0.29 mmol) and I (0.10 g, 0.29 mmol)
in n-hexane (10 mL) was warmed from -78 to 0 °C over 1 h,
stirred at 0 °C for an additional 1 h, cooled to -78 °C, and
then filtered to collect a pale yellow solid which was washed
with cold n-hexane (×2). Yield: 205 mg (80%). X-ray-quality
crystals were grown by cooling a hexane solution to -35 °C.
1H NMR (C6D6): δ 7.98 (s, 1H, CH(NAr)), 7.77 (d, 4H, J ) 8
Hz, Ph), 7.48 (dd, 1H, J ) 8, 2 Hz, Ph), 7.29-7.01 (m, 9H,
Ph), 6.92 (dd, J ) 8, 2 Hz, 1H, Ph), 6.64 (t, 1H, J ) 8 Hz, Ph),
3.59 (broad s, 8H, THF), 2.85 (septet, 2H, J ) 7 Hz, CHMe2),
1.64 (s, 9 H, CMe3), 1.22 (s, 8H, THF), 1.14, 0.86 (d, 2 × 6H,
J ) 7 Hz, CHMe2), 0.47 (s, 12H, CH2SiMe2Ph), -0.35 (broad
s, 4H, CH2SiMe2Ph). 13C{1H} NMR (C6D6): δ 174.50 (s, CH-
(NAr)), 166.83, 150.4, 147.74, 141.18, 140.65 (s, 5 quaternary
aromatic), 135.55, 134.34, 134.04, 128.02, 127.93, 127.02,
124.45 (s, 7 Ph), 123.22 (s, quaternary aromatic), 116.73 (s,
Ph), 70.37 (s, THF), 35.88 (s, CMe3), 30.61 (s, CMe3), 30.2 (v
weak s, YCH2), 29.06 (s, CHMe2), 26.03 (s, CHMe2), 25.53
(THF), 23.09 (s, CHMe2), 3.49 (s, SiMe2Ph). Anal. Calcd for
0.44 mmol) in n-pentane (10 mL) was stirred at 0 °C for 2 h,
cooled to -78 °C, and filtered to collect a pale yellow solid
which was washed with cold n-pentane (×2). Yield: 0.24 g
(68%).
Meth od 2. Solid 2-YP h (0.38 g, 0.44 mmol) was dissolved in
toluene (10 mL) and then evaporated to dryness in vacuo (×2).
The resulting solid was slurried in n-hexane, sonicated, cooled
to -78 °C, and then filtered to collect a cream white solid which
was washed with cold n-hexane (×1). Yield: 0.21 g (60%).
X-ray-quality crystals were grown by cooling a hot hexane
1
solution to -35 °C. H NMR (C6D6): δ 7.94 (s, 1H, CH(NAr)),
7.78 (dd, 4H, J ) 8, 2 Hz, Ph), 7.51 (dd, 1H, J ) 8, 2 Hz, Ph),
7.21-7.13 (m, 8H, Ph), 6.99-6.92 (m, 4H, Ph), 6.68 (t, 1H, J
) 8 Hz, Ph), 3.35 (broad s, 4H, THF), 2.78 (broad septet, 2H,
J ) 7 Hz, CHMe2), 1.66 (s, 9 H, CMe3), 1.10 (d, 6H, J ) 7 Hz,
CHMe2), 1.00 (s, 4H, THF), 0.78 (d, 6H, J ) 7 Hz, CHMe2)
0.48 (s, 12H, CH2SiMe2Ph), -0.08 (broad s, 4H, CH2SiMe2Ph).
13C{1H} NMR (C6D6): δ 174.88 (s, CH(NAr)), 167.08, 148.61,
146.97, 141.53, 140.80 (s, 5 quaternary aromatic), 135.30,
134.63, 134.25, 128.69, 128.21, 127.35, 124.50 (s, 7 Ph), 123.16
(s, quaternary aromatic), 117.05 (s, Ph), 70.92 (s, THF), 35.91
1
(s, CMe3), 32.30 (d, J C,Y ) 42 Hz, CH2SiMe2Ph), 30.44 (s,
CMe3), 29.46 (s, CHMe2), 25.94 (s, CHMe2), 25.07 (THF), 22.89
(s, CHMe2), 3.40 (s, CH2SiMe2Ph). Anal. Calcd for C45H64NO2-
Si2Y: C, 67.89; H, 8.10; N, 1.76. Found: C, 66.83; H, 8.09; N,
1.57.
[L2Sc(CH2SiMe3)] (4-ScMe). A mixture of [ScCl3(THF)3] (0.3
g, 0.82 mmol) and LiCH2SiMe3 (0.23 g, 2.45 mmol) in n-hexane
(30 mL) was stirred for 2 h at 0 °C and then filtered to give a
colorless solution of [Sc(CH2SiMe3)3(THF)2]. After the mixture
was cooled to -78 °C, a solution of I (0.55 g, 1.63 mmol) in
n-hexane (20 mL) was added and the temperature was raised
to 0 °C for 2 h and then to room temperature for 1 day. The
C
49H72NO3Si2Y: C, 67.79; H, 8.36; N, 1.61. Found: C, 64.65;
H, 8.07; N, 1.66.
[LY(CH2SiMe2P h )2(THF )] (3-YP h ). Meth od 1. A mixture
of [Y(CH2SiMe2Ph)3(THF)2] (0.30 g, 0.44 mmol) and I (0.15 g,

4238 Organometallics, Vol. 21, No. 20, 2002
Emslie et al.
bright yellow solution was evaporated to dryness in vacuo to
give a yellow oil, to which O(SiMe3)2 (5 mL) was added. After
sonication, the mixture was cooled to -45 °C and the resulting
bright yellow solid collected by filtration and washed with cold
O(SiMe3)2 (×2). Yield: 0.47 g (72%). X-ray-quality crystals
were grown by allowing a hot n-hexane solution to cool to room
mL) was heated at 140 °C for 3 days. The resulting red solution
was evaporated to dryness in vacuo to give an oil to which
n-hexane (10 mL) was added. After sonication, the mixture
was cooled to -78 °C and the resulting brick red solid collected
by filtration and washed with cold n-hexane (×2). Yield: 0.18
g (52%). X-ray-quality crystals were grown by cooling a hot
n-hexane solution of 5-Sc to room temperature. 1H NMR
(C6D6): δ 7.83 (s, 1H, CH(NAr)), 7.45 (dd, 1H, J ) 8, 2 Hz,
Ph), 7.27 (dd, 1H, J ) 8, 1 Hz, Ph), 7.20 (d, 2H, J ) 7 Hz, Ph),
7.07 (d, 1H, J ) 8 Hz, Ph), 7.00-6.95 (m, 3H, Ph), 6.82-6.95
(m, 3H, Ph), 6.61 (t, 1H, J ) 8 Hz, Ph), 4.50 (dd, 1H, J ) 4
Hz, Ha), 3.34 (quartet of dd, 1H, J ) 5.5, 6, 12 Hz, Hd), 3.29,
2.74, 2.61 (sept, 3 × 1H, J ) 7 Hz, CHMe2), 2.15 (ddd, 1H, J
) 14, 6, 1.5 Hz, Hb), 1.62, 1.59 (s, 2 × 9H, CMe3), 1.48 (d, 6H,
J ) 7 Hz, CHMe2), 1.29 (d, 3H, J ) 5 Hz, CHdMea), 0.97, 0.85,
0.83 (d, 3 × 3H, J ) 7 Hz, CHMe2), 0.80 (ddd, 1H, J ) 14, 12,
4 Hz, Hc) 0.75 (d, 3H, J ) 7 Hz, CHMe2). 13C{1H} NMR
(C6D6): δ 174.70 (s, CH(NAr)), 166.89, 164.08, 148.19, 145.83,
142.24, 141.91, 140.91, 136.14 (s, 8 quaternary aromatic),
135.60, 135.35 (s, 2 Ph), 132.89, 132.58 (s, 2 quaternary
aromatic), 128.32, 125.95, 125.47, 124.87, 124.68 (s, 5 Ph),
124.28 (s, quaternary aromatic), 123.82 (s, Ph), 123.09 (s,
quaternary aromatic), 122.61, 119.14, 118.19, 115.89 (s, 4 Ph),
53.39 (s, C1Ha), 35.94 (s, CHMe2), 35.77 (s, CMe3), 35.47 (s,
CMe3), 32.83 (s, C2H2), 30.48, 30.04 (s, 2 CMe3), 30.04, 29.68
(s, 2 CHMe2), 27.42 (s, C3HdMea), 25.81 (CHMe2), 25.81, 25.65
(s, 2 CHMe2), 22.91 (s, C3HdMea), 22.86, 22.66, 21.82, 20.02 (s,
4 CHMe2). Anal. Calcd for C46H59N2O2Sc: C, 77.06 H, 8.29; N,
3.91. Found: C, 76.55; H, 8.71; N, 3.77.
1
temperature. H NMR (C6D6): δ 7.85 (s, 2H, CH(NAr)), 7.37
(dd, 2H, J ) 8, 2 Hz, Ph), 7.14-7.01 (m, 4H, Ph), 6.91 (dd,
2H, J ) 7, 2 Hz, Ph), 6.76 (dd, 2H, J ) 8, 2 Hz, Ph), 6.53 (t,
2H, J ) 8 Hz, Ph), 3.25, 2.67 (sept, 2 × 2H, J ) 7 Hz, CHMe2),
1.47 (d, 6H, J ) 7 Hz, CHMe2), 1.19 (s, 18H, CMe3), 1.09 (d,
2
1H, J H,H ) 10 Hz, ScCH2), 0.96, 0.95, 0.69 (d, 3 × 6H, J ) 7
2
Hz, CHMe2), 0.24 (s, 9H, SiMe3), 0.23 (d, 1H, J H,H ) 10 Hz,
Sc-CH2). 13C{1H} NMR (C6D6): δ 175.79 (s, CH(NAr)), 167.63,
150.81, 142.19, 141.15, 140.53 (s, 5 quaternary aromatic),
135.07, 134.95, 127.62, 125.35, 124.61 (s, 5 Ph), 123.15 (s,
quaternary aromatic), 117.12 (s, Ph), 45.39 (weak s, Sc-CH2),
35.57 (s, CMe3), 30.57 (s, CMe3), 30.22, 29.11 (s, 2 CHMe2),
26.03, 25.66, 23.78, 22.49 (s, 4 CHMe2), 4.27 (s, SiMe3). Anal.
Calcd for C50H71N2O2SiSc: C, 74.59; H, 8.89; N, 3.46. Found:
C, 74.38; H, 9.04; N, 3.56.
[L2Sc(CH2SiMe2P h )]‚1/2(h exa n e) (4-ScP h ). A solution of
[Sc(CH2SiMe2Ph)3(THF)2] (0.3 g, 0.47 mmol) and I (0.32 g, 0.94
mmol) in n-hexane (20 mL) was stirred at 0 °C for 1 h and
then at room temperature for 6 h. The mixture was then
evaporated to lower volume in vacuo, sonicated, and cooled to
-78 °C and the resulting pale yellow solid collected by
filtration and washed with cold n-hexane (×2). Yield: 0.34 g
1
(79%). H NMR (C6D6): δ 7.86 (s, 2H, CH(NAr)), 7.76 (d, 2H,
J ) 5 Hz, Ph), 7.38 (d, 2H, J ) 7 Hz, Ph), 7.15-7.02 (m, 7H,
Ph), 6.91 (d, 2H, J ) 7 Hz, Ph), 6.78 (d, 2H, J ) 7 Hz, Ph),
6.56 (t, 2H, J ) 8 Hz, Ph), 3.16, 2.69 (sept, 2 × 2H, J ) 7 Hz,
[L2Y(µ-H)2YL2]‚(h exa n e) (6-Y). A solution of 4-YP h (1.0 g,
1.10 mmol) in toluene (30 mL) was stirred under H2 (4 atm)
for 1 day at room temperature. The pale yellow solution was
then evaporated to dryness in vacuo, n-hexane (ca.10 mL) was
added, and the mixture was sonicated, cooled to -78 °C, and
filtered to collect a pale yellow solid which was washed with
cold n-hexane (×2). Yield: 0.79 g (90%). X-ray-quality crystals
were grown by cooling a 1:1 toluene-n-heptane solution to -35
°C. 1H NMR (C6D6): δ 8.14 (s, 4H, CH(NAr)), 7.54 (t, 2H, 1J H,Y
) 32 Hz, µ-H), 7.27-7.11 (m, 8H, Ph), 7.09 (t, 4H, J ) 8 Hz,
Ph), 6.93 (d, 4H, J ) 7 Hz, Ph), 6.85 (d, 4H, J ) 7 Hz, Ph),
6.53 (t, 4H, J ) 7 Hz, Ph), 3.25, 2.85 (sept, 2 × 4H, J ) 6.5
Hz, CHMe2), 1.42 (d, 12H, J ) 7 Hz, CHMe2), 1.22 (m, 8H,
n-hexane), 1.13 (d, 12H, J ) 7 Hz, CHMe2), 1.07 (s, 36H, CMe3),
0.91 (d, 12H, J ) 7 Hz, CHMe2), 0.88 (t, 6H, n-hexane), 0.58
(d, 12H, J ) 7 Hz, CHMe2). 13C{1H} NMR (C6D6): δ 176.68 (s,
CH(NAr)), 166.98, 151.30, 142.44, 141.54, 140.58 (s, 5 qua-
ternary aromatic), 135.59, 133.48, 127.07, 125.37, 123.81 (s, 5
Ph), 123.35 (s, quaternary aromatic), 116.46 (s, Ph), 35.22 (s,
CMe3), 32.30 (s, n-hexane), 30.13 (s, CHMe2), 30.13 (s, CMe3),
28.16 (s, CHMe2), 27.61, 27.47, 25.84 (s, 3 CHMe2), 23.39 (s,
n-hexane), 21.72 (s, CHMe2), 14.69 (s, n-hexane). Anal. Calcd
for C98H136N4O4Y2: C, 73.02; H, 8.50; N, 3.47. Found: C, 73.33;
H, 8.23; N, 3.59.
2
CHMe2), 1.17 (d, 1H, J H,H ) 10 Hz, Sc-CH2), 1.36 (d, 6H, J
) 7 Hz, CHMe2), 1.23 (m, 4H, n-hexane), 1.13 (s, 18H, CMe3),
0.97 (d, 6H, J ) 7 Hz, CHMe2), 0.89 (m, 3H, n-hexane), 0.88,
0.69 (d, 2 × 6H, J ) 7 Hz, CHMe2), 0.49 (d, 1H, 2J H,H ) 10 Hz,
ScCH2), 0.43 (s, 6H, SiMe2Ph). 13C{1H} NMR (C6D6): δ 175.83
(s, CH(NAr)), 167.58, 150.83, 146.38, 142.23, 141.09, 140.55
(s, 6 quaternary aromatic), 135.25, 135.03, 134.48, 128.11,
127.78, 127.66, 125.34, 124.59 (s, 8 Ph), 123.25 (s, quaternary
aromatic), 117.25 (s, Ph), 40.97 (broad s, ScCH2) 35.56 (s,
CMe3), 32.30 (s, n-hexane), 30.58 (s, CMe3), 30.24, 29.14 (s, 2
CHMe2), 26.05, 25.69, 23.74 (s, 3 CHMe2), 23.39 (s, n-hexane),
22.48 (s, CHMe2), 14.70 (s, n-hexane), 3.81, 2.76 (s, 2 SiMe2-
Ph). Anal. Calcd for C58H80N2O2SiSc: C, 76.53; H, 8.86; N, 3.08.
Found: C, 76.27; H, 8.47; N, 2.98.
[L2Y(CH2SiMe2P h )] (4-YP h ). A solution of [Y(CH2SiMe2-
Ph)3(THF)2] (0.2 g, 0.29 mmol) and I (0.2 g, 0.29 mmol) in
n-pentane (30 mL) was stirred for 4 h at room temperature.
The pale yellow solution was then concentrated in vacuo (ca.10
mL), sonicated, cooled to -78 °C, and filtered to collect a pale
yellow solid which was washed with cold n-pentane (×2).
Yield: 0.21 g (77%). X-ray-quality crystals were grown by slow
cooling of a hot n-hexane solution to room temperature. 1H
NMR (C6D6): δ 7.82-7.79 (m, 4H, CH(NAr) & Ph), 7.38 (dd,
2H, J ) 8, 2 Hz, Ph), 7.15-7.01 (m, 7H, Ph), 6.91 (dd, 2H, J
) 6, 3 Hz, Ph), 6.76 (dd, 2H, J ) 8, 2 Hz, Ph), 6.55 (t, 2H, J )
8 Hz, Ph), 3.00, 2.78 (sept, 2 × 2H, J ) 7 Hz, CHMe2), 1.33 (d,
6H, J ) 7 Hz, CHMe2), 1.17 (s, 18H, CMe3), 1.00, 0.86, 0.81
(d, 3 × 6H, J ) 7 Hz, CHMe2), 0.50, 0.43 (s, 2 × 3H, SiMe2Ph),
[L2Y(µ-D)2YL2]‚(h exa n e) (d 2-6-Y). A procedure analogous
to that described above using D2 gave 132 mg (75%) of d 2-6-Y.
2H NMR (C6H6): δ 7.59 (J YD ) 5 Hz). Anal. Calcd for
C
98H134D2N4O4Y2: C, 72.93; H/D, 8.62; N, 3.47. Found: C,
72.91; H/D, 8.75; N, 3.58.
Syn th esis of 7-Sc. A solution of [L2Sc(CH2SiMe3)] (0.30 g,
0.37 mmol) in toluene (20 mL) was stirred under H2 (4 atm)
for 1 day at room temperature. The resulting orange solution
was evaporated to dryness in vacuo, O(SiMe3)2 (ca. 5 mL) was
added, and the mixture was sonicated, cooled to -45 °C, and
filtered to collect a bright yellow solid which was washed with
cold O(SiMe3)2 (×2). Yield: 0.16 g (60%). X-ray-quality crystals
of 7-Sc‚0.5(n-hexane) were grown by cooling an n-hexane
2
2
0.39, 0.06 (dd, 2 × 1H, J H,H ) 11, J H,Y ) 3.5 Hz, YCH2). 13C-
{1H} NMR (C6D6): δ 175.86 (s, CH(NAr)), 167.69, 167.66,
149.05, 146.71, 141.86, 140.96, 140.82 (s, 7 quaternary aro-
matic), 135.51, 134.82, 127.93, 125.16, 124.86 (s, 5 Ph), 123.41
(s, quaternary aromatic), 116.77 (s, Ph), 35.54 (s, CMe3), 32.42
1
(d, J C,Y ) 49 Hz, Y-CH2), 30.32 (s, CHMe2), 30.23 (s, CMe3),
1
29.49 (s, CHMe2), 26.00, 25.37, 23.98, 22.84 (s, 4 CHMe2), 4.37,
3.05 (s, 2 SiMe2Ph). Anal. Calcd for C55H73N2O2SiY: C, 72.50;
H, 8.07; N, 3.07. Found: C, 72.12; H, 8.25; N, 3.12.
solution to -35 °C. H NMR (C6D6): δ 7.81 (s, 1H, CH(NAr)),
7.38 (dd, 1H, J ) 8, 2 Hz, Ph), 7.25 (dd, 1H, J ) 8, 2 Hz, Ph),
7.11 (d, 1H, J ) 8 Hz, Ph), 7.08-6.99 (m, 5H, Ph), 6.76 (dt,
1H, J ) 8, 2 Hz, Ph), 6.66 (t, 1H, J ) 8 Hz, Ph), 6.55 (t, 1H,
Th er m olysis of 4-ScM: P r ep a r a tion of 5-Sc. A bright
yellow solution of 4-ScMe (0.39 g, 0.48 mmol) in toluene (30
2
1
J ) 8 Hz, Ph), 4.71 (d, 1H, J H,H 15 Hz, J C,H ≈ 100 Hz, C1H),

Organometallic Complexes of Scandium and Yttrium
Organometallics, Vol. 21, No. 20, 2002 4239
1
4.46 (d, 1H, J H,H ) 15 Hz, J C,H ≈ 110 Hz, C1H), 3.43 (sept.,
(t, 3H, J ) 7 Hz, Ph), 6.31 (s, 1H, OCHPh2), 2.99, 2.90 (sept,
2 × 2H, J ) 7 Hz, CHMe2), 1.16 (broad s, 18H, CMe3), 1.09,
1.02, 0.89, 0.82 (d, 3 × 6H, J ) 6 Hz, CHMe2). 13C{1H} NMR
(d8-toluene, 40 °C): δ 175.98 (s, CH(NAr)), 135.37, 134.16,
132.66 (b), 130.91 (b), 128.67, 128.40, 127.5 (b), 127.40, 126.47,
125.11, 124.81, 116.16 (s, 12 x Ph), 82.63 (s, OCHPh2), 35.57
(s, 2 × CMe3), 30.24 (s, 2 × CMe3), 30.24, 29.50 (s, 2 × CHMe2),
26.02, 24.91, 23.68, 23.00 (s, 4 × CHMe2). Anal. Calcd for
1H, J ) 6 Hz, CHMe2), 3.31 (sept, 2H, J ) 7 Hz, CHMe2),
2.78 (sept, 1H, J ) 6 Hz, CHMe2), 1.59, 1.45 (s, 2 × 9H, CMe3),
1.28 (d, 6H, J ) 7 Hz, CHMe2), 1.24, 0.97 (d, 2 × 3H, J ) 6
Hz, CHMe2), 0.91 (d, 6H, J ) 7 Hz, CHMe2), 0.90, 0.88 (d, 2 ×
3H, J ) 6 Hz, CHMe2). 13C{1H} NMR (C6D6): δ 176.16 (s, CH-
(NAr)), 166.82, 162.74, 150.41, 145.34, 144.97, 142.05, 141.68,
141.01, 137.22 (s, 9 quaternary aromatic), 135.76, 135.35 (s, 2
Ph), 130.33 (s, quaternary aromatic), 128.54, 127.83, 126.72,
125.28, 125.07, 124.43 (s, 6 Ph), 122.94 (s, quaternary aro-
matic), 119.20, 118.51 (s, 2 Ph), 60.14 (s, C1H2), 35.83, 35.63
(s, 2 CMe3), 30.52, 29.97 (s, 2 CMe3), 29.97, 29.89, 29.42 (s, 3
CHMe2), 25.82, 25.73, 25.37, 25.12, 23.79, 23.40 (s, 6 CHMe2).
Anal. Calcd for C46H61N2O2Sc: C, 76.85; H, 8.55; N, 3.90.
Found: C, 77.30; H, 8.05; N, 3.87.
C
72H81N2O4Y: C, 76.71; H, 7.24; N, 2.48. Found: C, 76.90; H,
7.44; N, 2.55.
Rea ction of 6-Y w ith P yr id in e. A solution of 6-Y (100 mg,
6.55 × 10-5 mol) and pyridine (0.03 mL, 3.71 × 10-4 mol) in
toluene (5 mL) was stirred at room temperature for 18 h and
then evaporated to dryness in vacuo. The resulting orange solid
was washed with n-pentane (×2) and dried in vacuo; yield 85
1
Rea ction of 6-Y w ith HB(C6F 5)2. A solution of 6-Y (40 mg,
2.48 × 10-5 mol) and HB(C6F5)2 (17 mg, 4.96 × 10-5 mol) in
toluene (3 mL) was stirred at room temperature for 8 days
and then evaporated to dryness in vacuo. The resulting
mixture was slurried with n-hexane, cooled to -78 °C, and
filtered to collect a pale yellow solid which was dried in vacuo
for 20 min; yield 20 mg (35%). 1H NMR (d8-toluene, 25 °C):
7.79 (d, 2H, J ) 3 Hz, CH(NAr)), 7.17 (dd, 2H, J ) 8, 2 Hz,
Ph), 7.10-6.97 (m, 4H, Ph), 6.83, 6.63 (dd, 2 × 2H, J ) 8, 2
Hz, Ph), 6.44 (t, 2H, J ) 8 Hz, Ph), 3.36, 2.73 (sept., 2 × 2H,
mg (70%). H NMR (d8-toluene, -60 °C): δ 8.89, 8.49 (d, 2 ×
2H, J 5 Hz, o-NC5H5), 8.01 (s, 1H, CH(NAr)), 7.58, 7.46, 7.39
(d, 3 × 1H, J ) 7.5 Hz, Ph), 7.22-6.94 (m, 6H, Ph), 6.92 (dd,
1H, J ) 7.5 Hz, Ph), 6.80 (d, 1H, J 7.5 Hz, Ph), 6.61 (dd, 3H,
J ) 7.5, 7.5 Hz, Ph), 6.47 (t, 2H, J 7.5 Hz, p-NC5H5), 6.25,
6.01 (dd, 2 × 2H, J 7.5, 5 Hz, m-NC5H5), 4.79 (s, 2H, CH2),
2.75, 2.37 (sept, 2 × 2H, J ) 6 Hz, CHMe2), 1.45, 1.37 (s, 2 ×
9H, CMe3), 1.27 (m, 6H, pentane), 1.17 (d, J ) 6 Hz, CHMe2),
0.94 (t, 6H, pentane), 0.70, 0.52, 050 (d, 3 × 6H, J ) 6 Hz,
CHMe2). 13C{1H} NMR (d8-toluene, 0 °C): δ 175.41 (s, CH-
(NAr)), 139.12, 136.16, 133.25, 129.58, 129.04, 128.65, 126.42,
125.77, 125.76, 125.05, 124.53, 123.48, 122.16, 116.63, 115.93
(s, 15 × Ph), 65.74 (s, CH2), 35.43, 35.32 (s, 2 × CMe3), 31.11,
30.44 (s, 2 × CMe3), 28.69, 28.58 (s, 2 × CHMe2), 27.55, 26.21,
23.00, 21.96 (s, 4 × CHMe2). Anal. Calcd for C61H83N4O2Y: C,
73.76; H, 8.42; N, 5.64. Found: C, 74.23; H, 8.47; N, 5.60.
Rea ction of 6-Y w ith THF . A solution of 6-Y (80 mg, 4.34
× 10-5 mol) in toluene (2 mL) was layered with THF (∼0.5
mL) and allowed to stand for 3 days. The pale yellow mother
liquors were then decanted, and the remaining yellow crystals
1
J ) 7 Hz, CHMe2), 3.04 (broad quartet, J H,B ) 74 Hz, µ-H),
1.23 (broad s, 6H, hexane), 1.53, 1.12, 0.97 (d, 3 × 6H, J ) 7
Hz, CHMe2), 0.89 (t, J ) 7 Hz, 6H, hexane), 0.70 (s, 18H,
CMe3), 0.60 (d, 6H, J ) 7 Hz, CHMe2). 19F NMR (d8-toluene,
20 °C): -132.6 (m, 2F, ortho-F), -158.8 (t, 1F, J ) 20 Hz, para-
F), -163.9 (m, 2F, meta-F). 13C{1H} NMR (d8-toluene, 25 °C):
δ 176.99 (s, CH(NAr)), 135.83, 135.77, 128.25, 125.67, 124.87,
118.39 (s, 6 Ph), 35.09 (s, CMe3), 30.58, 30.05 (s, 2 × CHMe2),
29.35 (s, CMe3), 25.94, 25.54, 23.52, 22.72 (s, 4 × CHMe2). 11
B
NMR (d8-toluene, 20 °C): -17.10 (t, 1J B,H ) 74 Hz). Anal. Calcd
for C61H69F10N2O2BY: C, 63.60; H, 6.04; N, 2.43. Found: C,
63.03; H, 5.88; N, 2.54.
1
were dried in vacuo for 10 min. Yield: 78 mg (72%). H NMR
(d8-toluene, 100 °C): δ 8.02 (d, 1H, J ) 2 Hz, CH(NAr)), 7.28
(dd, 1H, J ) 8, 2 Hz, Ph), 7.15-6.92 (m, 7H, Ph), 6.86 (dd,
1H, J ) 8 Hz, Ph), 6.53, 6.48 (t, 2 × 1H, J ) 8 Hz, Ph), 4.35
(broad s, 2H CH2), 3.74, 3.15 (sept, 2 × 2H, J ) 7 Hz, CHMe2),
3.61, 1.43 (m, 2 × 8H, THF), 1.32, 1.13 (d, 2 × 6H, J ) 7 Hz,
CHMe2), 1.18 (d, 12H, J ) 7 Hz, CHMe2), 1.14, 1.07 (s, 2 ×
9H, CMe3). 13C{1H} NMR (d8-toluene, 80 °C): δ 174.35 (s, CH-
(NAr)), 134.47, 133.11, 127.43, 126.50, 124.92, 123.96, 123.11,
122.71, 115.69, 115.15 (s, 10 Ph), 68.95 (broad s, THF), 63.08
(s, CH2), 25.0 (broad s, THF), 34.66, 34.61 (s, 2 × CMe3), 30.23,
29.25 (s, 2 × CMe3), 29.66, 28.42 (s, 2 × CHMe2), 25.01, 24.88,
22.84 (s, 3 CHMe2). Anal. Calcd for C68H93N2O4Y: C, 71.50;
H, 8.56; N, 3.09. Found: C, 71.58; H, 8.11; N, 2.67.
Syn th esis of L3Y (8-Y). A mixture of [YCl3(THF)3.5] (0.3 g,
0.67 mmol) and LiCH2SiMe3 (0.19 g, 2.01 mmol) in n-hexane
(30 mL) was stirred for 2 h at 0 °C and then filtered to give a
colorless solution of [Y(CH2SiMe3)3(THF)2]. After the mixture
was cooled to -78 °C, a solution of I (0.68 g, 2.01 mmol) in
n-hexane (20 mL) was added and the temperature was raised
to 0 °C for 2 h and then to room temperature for 6 days. The
mixture was then concentrated in vacuo (ca. 10 mL), sonicated,
and cooled to -78 °C and the resulting pale yellow solid
collected by filtration and washed with n-hexane (×2). Yield:
0.55 g (75%). X-ray-quality crystals were grown by allowing a
hot toluene solution to cool to room temperature. 1H NMR
(C6D6): δ 7.88 (d, 3H, J ) 1 Hz, CH(NAr)), 7.48 (dd, 3H, J )
8 Hz, J ) 2 Hz, Ph), 7.04-6.98 (m, 9H, Ph), 6.75 (dd, 3H, J )
8 Hz, J ) 2 Hz, Ph), 6.57 (t, 3H, J ) 8 Hz, Ph), 3.67, 2.13
(sept, 2 × 3H, J ) 7 Hz, CHMe2), 1.54 (s, 27H, CMe3), 0.95,
0.80, 0.66, 0.61 (d, 4 × 9H, J ) 7 Hz, CHMe2). 13C{1H} NMR
(C6D6): δ 177.97 (s, CH(NAr)), 166.91, 152.61, 143.53, 141.69,
140.27 (s, 5 quaternary aromatic), 136.35, 134.74, 127.45,
125.35, 125.19 (s, 5 Ph), 123.83 (s, quaternary aromatic),
116.44 (s, Ph), 36.15 (s, CMe3), 32.07 (s, CMe3), 29.27 (s,
CHMe2), 27.86 (s, CHMe2), 27.77 (s, CHMe2), 26.94, 23.81,
Rea ction of 6-Y w ith HCtCSiMe3. To a solution of 6-Y
(100 mg, 6.55 × 10-5 mol) in toluene (10 mL) was added HCt
CSiMe3 (0.2 mL, 1.42 mmol). After it was stirred at room
temperature for 3 days, the yellow solution was evaporated
to dryness in vacuo, and the resulting oily solid was dried in
vacuo for 12 h. The product was then slurried in n-hexane (2
mL) and cooled to -35 °C, and the mother liquors were
removed to give 43 mg of a yellow powder; yield 35 mg (33%).
1H NMR of major isomer (d8-toluene, -60 °C): δ 7.77 (d, 2H,
J ) 2 Hz, CH(NAr)), 7.33 (dd, 2H, J ) 8, 2 Hz, Ph), 7.10-7.01
(m, 4H, Ph), 6.92 (broad d, 2H, J ) 8 Hz, Ph), 6.80 (dd, 2H, J
) 8, 2 Hz, Ph), 6.51 (t, 2H, J ) 8 Hz, Ph), 3.12, 2.82 (sept, 2
× 2H, J ) 7 Hz, CHMe2), 1.54 (d, 6H, J ) 7 Hz, CHMe2), 1.14
(s, 18H, CMe3), 1.04, 0.91, 0.75 (d, 3 × 6H, J ) 7 Hz, CHMe2),
0.25 (s, 9H, SiMe3). 13C{1H} NMR of major isomer (d8-toluene,
0 °C): δ 175.21 (s, CH(NAr)), 167.33 (s, quaternary aromatic),
1
163.13 (d, J C,Y ) 72 Hz, YCCSiMe3), 148.46, 141.83, 140.66,
140.58 (s, 4 quaternary aromatic), 134.91, 134.41, 127.36,
125.02, 124.45, 123.06 (s, 5 Ph), 123.06 (s, quaternary aro-
2
matic), 116.50 (s, Ph), 108.91 (d, J C,Y ) 12 Hz, YCCSiMe3),
35.22 (s, CMe3), 29.74 (s, 2 × CMe3), 30.05, 29.24 (s, 2 ×
CHMe2), 27.47, 24.69, 24.35, 22.53 (s, 4 CHMe2), 1.40 (s,
SiMe3). Anal. Calcd for C51H69N2O2SiY: C, 71.30; H, 8.09; N,
3.26. Found: C, 70.96; H, 7.51; N, 3.31.
Rea ction of 6-Y w ith Ben zop h en on e. A solution of 6-Y
(50 mg, 3.28 × 10-5 mol) and Ph2CO (24 mg, 1.31 × 10-4 mol)
in C6H6 (2 mL) was stirred at room temperature for 6 days
and then evaporated to dryness. The resulting yellow oil was
sonicated in n-hexane to give a yellow solid from which the
near-colorless mother liquors were decanted. The solid was
then washed an additional two times with n-hexane to give
34 mg of product (51% yield). H NMR (d8-toluene, 40 °C): δ
7.84 (s, 1H, CH(NAr)), 7.66 (broad s, 4H, Ph), 7.36 (m, 6H,
Ph), 7.14-6.96 (m, 18H, Ph), 6.78 (d, 1H, J ) 7 Hz, Ph), 6.52
1

4240 Organometallics, Vol. 21, No. 20, 2002
Emslie et al.
22.74 (s, 3 CHMe2). Anal. Calcd for C69H90N3O3Y: C, 75.45;
H, 8.26; N, 3.83. Found: C, 75.12; H, 8.24; N, 3.85.
× quaternary aromatic), 136.95 (s, Ph), 136.28 (s, quaternary
aromatic), 136.20, 135.88, 135.85 (s, 3 × Ph), 135.84 (s,
quaternary aromatic), 135.66, 135.58, 135.47 (s, 3 × Ph),
133.57 (s, quaternary aromatic), 130.19, 129.62, 129.13, 128.69,
128.08, 127.94, 127.74, 126.29, 125.65, 125.46, 125.42, 125.25,
125.09, 124.90, 124.70, 124.57 (s, 16 × Ph), 123.88 (s, quater-
nary aromatic), 123.71 (s, Ph), 123.52 (s, quaternary aromatic),
123.43 (s, Ph), 123.40 (s, quaternary aromatic), 123.33, 122,
81, 118.49, 117.93, 117.59, 117.51, 117.12 (s, 7 × Ph), 36.29,
36.03, 35.69, 35.59, 35.47 (s, 6 × CMe3), 32.20, 31.94, 31.75,
31.33, 30.72, 30.67 (s, 6 × CMe3), 30.44, 30.32, 30.06, 29.41,
29.29, 28.99, 28.98, 28.74, 28.36, 27.98 (s, 10 × CHMe2), 26.46,
26.26, 26.25, 26.02, 25.85, 25.70, 25.64, 25.61, 24.90, 24.09,
23.83, 23.59, 23.51, 22.88, 22.74, 22.65, 22.52 (s, 17 × CHMe2).
Anal. Calcd for C69H90N3O3Sc: C, 78.60; H, 8.60; N, 3.99.
Found: C, 78.04; H, 8.68; N, 3.74.
Syn th esis of [(K2-L)2(K1-L)Sc] (8-Sc). A mixture of [Sc-
(CH2SiMe3)L2] (4-ScMe; 0.2 g, 0.25 mmol) and I (84 mg, 0.25
mmol) in toluene (20 mL) was stirred for 4 days at 85 °C and
then evaporated to dryness in vacuo. The resulting yellow oil
was sonicated in n-pentane, cooled to -78 °C, and then filtered
to collect a yellow solid, which was washed with cold n-pentane
(×2); yield 149 mg (56%). X-ray-quality crystals of 8-Sc‚0.5-
(n-hexane) were grown by cooling a hot hexane solution to
room temperature. 1H NMR (d8-toluene, -20 °C): δ 9.13, 8.77
(s, 2 × 1H, CH(NAr)), 8.46 (d, 1H, J ) 7 Hz, Ph), 7.99, 7.81 (s,
2 × 1H, CH(NAr)), 7.73 (s, 2H, CH(NAr)), 7.38-7.33 (m, 4H,
Ph), 7.26 (d, 1H, J ) 7 Hz, Ph), 7.16-6.76 (m, 22H, Ph), 6.57-
6.46 (m, 6H, Ph), 6.40 (t, 1H, J ) 7 Hz, Ph), 6.12 (t, 1H, J )
8 Hz, Ph), 3.66, 3.32, 3.19, 3.06 (sept, 4 × 1H, J ) 7 Hz,
CHMe2), 2.97 (m, 3H, CHMe2), 2.82, 2.78 (sept, 2 × 1H, J ) 7
Hz, CHMe2), 2.73 (m, 3H, CHMe2), 1.48 (d, 3H, J ) 7 Hz,
CHMe2), 1.37, 1.33 (s, 2 × 9H, CMe3), 1.32, 1.29, 1.23, 1.20,
1.16, 1.14, 1.10 (d, 7 × 3H, J ) 7 Hz, CHMe2), 1.10 (s, 9H,
CMe3), 1.08, 1.07 (d, 2 × 3H, J ) 7 Hz, CHMe2), 1.06 (12H,
CHMe2), 1.03 (s, 3H, J ) 7 Hz, CHMe2), 1.03 (s, 9H, CMe3),
1.02, 1.00 (d, 2 × 3H, J ) 7 Hz, CHMe2), 0.94 (s, 9H, CMe3),
0.93 (d, 3H, J ) 7 Hz, CHMe2), 0.91 (s, 9H, CMe3), 0.81, 0.79
(d, 2 × 3H, J ) 7 Hz, CHMe2), 0.75 (6H, CHMe2), 0.68, 0.51
(d, 2 × 3H, J ) 7 Hz, CHMe2). 13C NMR (d8-toluene, -20 °C):
δ 177.24, 177.18, 177.00, 176.16 (s, 4 × CH(NAr)), 167.15,
166.78, 166.67, 165.64, 165.30 (s, 5 × quaternary aromatic),
158.96, 157.56 (s, 2 × CH(NAr)), 152.26, 152.22, 151.78,
151.17, 151.04, 148.41, 142.94, 142.30, 141.58, 141.45, 141.17,
141.13, 140.01, 139.92, 139.82, 139.50, 138.72, 138.66 (s, 18
Ack n ow led gm en t. Funding for this work came
from Nova Chemicals Ltd. of Calgary, Alberta, Canada,
and the Natural Sciences and Engineering Research
Council of Canada in the form of a Collaborative
Research and Development Grant (to W.E.P.), and an
E. W. R. Steacie Fellowship (2001-2003) (to W.E.P.).
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates, anisotropic displacement parameters, and all bond
distances and angles for the structurally characterized mol-
ecules presented here. This material is available free of charge
via the Internet at http://pubs.acs.org.
OM020382C