Preparation of scandium complexes with benzamidinate ligands: Synthesis and reactivity of alkyl and hydrido derivatives

Article abstract of DOI:10.1021/om950750v

A range of new scandium complexes incorporating N,N′-bis(trimethylsilyl)benzamidinato ligands has been prepared. Addition of [PhC(NSiMe₃)₂]Li(TMEDA) to ScCl₃(THF)₃ in THF gives [PhC(NSiMe₃)₂]₂Sc(μ-Cl)₂Li(TMEDA) in moderate yield. Alternatively, the use of [RC-(NSiMe₃)₂]Na(Et₂O)_n, (R = Ph, Tol) gives good yields of the lithium-free halide [RC(NSiMc₃)₂]₂-ScCl(THF). The latter is a useful starting material for the preparation of a number of derivatives, including [PhC(NSiMe₃)₂]₂ScR′ (R′ = CH₂SiMe₃, Mes), [PhC(NSiMe₃)₂]₂ScMe-(THF), [TolC(NSiMe₃)₂]₂Sc(BH₄)(THF), and [PhC(NSiMe₃)₂]₂ScNHC₆H ₃-2,6-Prⁱ2, which were obtained by salt metathesis reactions from the corresponding alkali-metal reagents. Reaction of [PhC(NSiMe₃)₂]₂ScCH₂SiMe₃ with Me₃SiCCH gives the σ-alkyne [PhC(NSiMe₃)₂]₂ScCC-SiMe₃ and Me₄Si. [PhC(NSiMe₃)₂]₂ScCH₂SiMe₃ reacts readily with H₂ to form {[PhC-(NSiMe₃)₂]₂ScH}₂. The hydride reacts with Ph₂C₂ in refluxing benzene to give the monoinsertion product [PhC(NSiMe₃)₂]₂ScC(Ph)=C(Ph)H. Two derivatives have been crystallographically characterized: [PhC(NSiMe₃)₂]₂Sc(μ-Cl)₂Li(TMEDA) and {[PhC(NSiMe₃)₂]₂ScH}₂.

Full text of DOI:10.1021/om950750v

984
Organometallics 1996, 15, 984-991
P r ep a r a tion of Sca n d iu m Com p lexes w ith
Ben za m id in a te Liga n d s: Syn th esis a n d Rea ctivity of
Alk yl a n d Hyd r id o Der iva tives
J ohn R. Hagadorn and J ohn Arnold*
Department of Chemistry, University of California, Berkeley, California 94720-1460
Received September 21, 1995X
A range of new scandium complexes incorporating N,N′-bis(trimethylsilyl)benzamidinato
ligands has been prepared. Addition of [PhC(NSiMe3)2]Li(TMEDA) to ScCl3(THF)3 in THF
gives [PhC(NSiMe3)2]2Sc(µ-Cl)2Li(TMEDA) in moderate yield. Alternatively, the use of [RC-
(NSiMe3)2]Na(Et2O)n (R ) Ph, Tol) gives good yields of the lithium-free halide [RC(NSiMe3)2]2-
ScCl(THF). The latter is a useful starting material for the preparation of a number of
derivatives, including [PhC(NSiMe3)2]2ScR′ (R′ ) CH2SiMe3, Mes), [PhC(NSiMe3)2]2ScMe-
(THF), [TolC(NSiMe3)2]2Sc(BH4)(THF), and [PhC(NSiMe3)2]2ScNHC6H3-2,6-Pri , which were
2
obtained by salt metathesis reactions from the corresponding alkali-metal reagents. Reaction
of [PhC(NSiMe3)2]2ScCH2SiMe3 with Me3SiCCH gives the σ-alkyne [PhC(NSiMe3)2]2ScCC-
SiMe3 and Me4Si. [PhC(NSiMe3)2]2ScCH2SiMe3 reacts readily with H2 to form {[PhC-
(NSiMe3)2]2ScH}2. The hydride reacts with Ph2C2 in refluxing benzene to give the mono-
insertion product [PhC(NSiMe3)2]2ScC(Ph)dC(Ph)H. Two derivatives have been crystallo-
graphically characterized: [PhC(NSiMe3)2]2Sc(µ-Cl)2Li(TMEDA) and {[PhC(NSiMe3)2]2ScH}2.
In tr od u ction
Here we report18 the synthesis and characterization
of a number of scandium benzamidinates. The major
starting material for our investigations has been [PhC-
(NSiMe3)2]2ScCl(THF),16 which was recently mentioned
in a review, and from this a range of derivatives has
been prepared.
The use of nitrogen-based donors as supporting
ligands in transition-metal chemistry has received
considerable attention.1 For the early transition metals,
the focus has been largely on the preparation and
reactivity of electrophilic species, some of which function
as olefin polymerization catalysts.2-5 Following our
studies6-8 of N4-donor sets involving porphyrin ligands,
we recently turned our attention to bis(amidinate)
ligation for the preparation of early transition metal
derivatives.9 We were attracted to N,N′-bis(trimethyl-
silyl)benzamidinate due to its ease of preparation and
derivatization, solubility properties, and steric bulk. A
number of workers have demonstrated the synthetic
utility of this ligand for the preparation of inorganic
compounds across the periodic table,10-12 but only
recently have detailed investigations into their reactiv-
ity been described.4,9,13-17
Resu lts a n d Discu ssion
Multigram quantities of [RC(NSiMe3)2]2ScCl(THF) (R
) Ph, Tol) were easily obtained by the reaction of Na-
[RC(NSiMe3)2](Et2O)n with ScCl3(THF)3 in THF. Crys-
tallization from Et2O afforded the product as colorless
crystals in reasonable yields (ca. 70%). The related
reaction using [PhC(NSiMe3)2]Li(TMEDA) (TMEDA )
N,N,N′,N′-tetramethylethylenediamine) gave [PhC-
(NSiMe3)2]2Sc(µ-Cl)2Li(TMEDA) as colorless crystals in
moderate yield. Crystals of the dichloride-lithium
adduct suitable for X-ray diffraction studies were grown
from hexanes at -10 °C. An ORTEP view of one of the
two crystallographically independent molecules is shown
in Figure 1. The two independent molecules are virtu-
ally identical with a pseudoinversion center between the
two. The compound features a planar Sc(µ-Cl)2Li core
with the lithium further coordinated to the chelating
TMEDA ligand. The amidinate ligands adopt a typical
planar coordination geometry to the metal center, with
Sc-N bond lengths varying from 2.168(5) to 2.230(5)
Å. The Sc-Cl bonds range in length from 2.529(3) to
2.560(3) Å and are similar to the values reported for
(Cp2ScCl)2 (average 2.575 Å).19 The Cl-Sc-Cl bond
angles of 83.37(9) and 84.03(9)° are identical within
X Abstract published in Advance ACS Abstracts, J anuary 1, 1996.
(1) Togni, A.; Venanzi, L. M. Angew. Chem., Int. Ed. Engl. 1994,
33, 497.
(2) Uhrhammer, R.; Black, D. G.; Gardner, T. G.; Olsen, J . D.;
J ordan, R. F. J . Am. Chem. Soc. 1993, 115, 8493.
(3) Tjaden, E. B.; Swenson, D. C.; J ordan, R. F.; Petersen, J . L.
Organometallics 1995, 14, 371.
(4) Gomez, R.; Duchateau, R.; Chernega, A. N.; Teuben, J . H.;
Edelmann, F. T.; Green, M. L. H. J . Organometallic Chem. 1995, 491,
153.
(5) Shapiro, P. J .; Bunel, E.; Schaefer, W. P.; Bercaw, J . E.
Organometallics 1990, 9, 867.
(6) Brand, H.; Arnold, J . Coord. Chem. Rev. 1995, 140, 137.
(7) Brand, H.; Capriotti, J . A.; Arnold, J . Organometallics 1994, 13,
4469.
(8) Brand, H.; Arnold, J . Angew. Chem., Int. Ed. Engl. 1994, 33,
95.
(9) Hagadorn, J . R.; Arnold, J . Organometallics 1994, 13, 4670.
(10) Edelmann, F. T. Coord. Chem. Rev. 1994, 137, 403.
(11) Dehnicke, K. Chem.-Ztg. 1990, 114, 295.
(12) Barker, J .; Kilner, M. Coord. Chem. Rev. 1994, 133, 219.
(13) Duchateau, R.; van Wee, C. T.; Meetsma, A.; Teuben, J . H. J .
Am. Chem. Soc. 1993, 115, 4931.
(15) Wedler, M.; Noltemeyer, M.; Pieper, U.; Schmidt, H.; Stalke,
D.; Edelmann, F. T. Angew. Chem., Int. Ed. Engl. 1990, 29, 894.
(16) Edelmann, F. T. J . Alloys Comp. 1994, 207/ 208, 182.
(17) Wedler, M.; Noltemeyer, M.; Pieper, U.; Schmidt, H. G.; Stalke,
D.; Edelmann, F. T. J . Organomet. Chem. 1992, 426, 295.
(18) Dawson, D. Y.; Hagadorn, J . R.; Arnold, J . This work was
presented in part at the 210th ACS National Meeting in Chicago, IL
(Aug 20-24, 1995); Abstract INOR 338.
(14) Flores, J . C.; Chien, J . C. W.; Rausch, M. D. Organometallics
1995, 14, 1827.
0276-7333/96/2315-0984$12.00/0 © 1996 American Chemical Society

Sc Complexes with Benzamidinate Ligands
Organometallics, Vol. 15, No. 3, 1996 985
Sch em e 1
stretches and a broad band with multiple shoulders at
2330 cm-1 assignable to the (A1, B2) B-H(bridging)
stretches.
Reaction of [PhC(NSiMe3)2]2ScCl(THF) with lithium
reagents was successful for the preparation of five-
coordinate [PhC(NSiMe3)2]2ScCH2SiMe3, [PhC(NSi-
Me3)2]2ScCH2SiMe2Ph, and [PhC(NSiMe3)2]2ScMes (Mes
) 2,4,6-trimethylphenyl). The proton NMR spectrum
of [PhC(NSiMe3)2]2ScMes, which was easily isolated as
colorless crystals from hexanes, shows a broadened
signal for the -SiMe3 groups of the amidinate ligands
indicative of slow rotation of the amidinate ligands on
the NMR time scale. Both [PhC(NSiMe3)2]2ScCH2SiMe3
and [PhC(NSiMe3)2]2ScCH2SiMe2Ph were isolated as
colorless crystals from hexamethyldisiloxane (HMDSO)
and are exceedingly soluble in hydrocarbon solvents. In
contrast to Cp*2ScR compounds,22 heating to 60 °C in
C6D6 led to no reaction. Proton NMR spectroscopy
shows signals at δ 0.41 and 0.58 for the R-CH2 protons
of [PhC(NSiMe3)2]2ScCH2SiMe3 and [PhC(NSiMe3)2]2-
ScCH2SiMe2Ph, respectively. These are upfield of re-
lated absorptions in other d0-amidinates such as
[PhC(NSiMe3)2]2TiMe2 and [PhC(NSiMe3)2]2TiCH2SiMe3-
(Cl)9 (δ 1.96 and 3.06, respectively) due to the effect of
the highly electropositive scandium. Relative to the
analogous Cp*2Sc compounds, however, the signals are
shifted slightly downfield, possibly indicative of a more
electron-deficient metal in [PhC(NSiMe3)2]2Sc than that
of the Cp*2Sc fragment.22 Qualitatively, the steric
demands of the PhC(NSiMe3)2 ligand appears to be
intermediate to Cp and Cp* ligands.9,23 Attempts to
prepare the corresponding methyl derivative using MeLi
gave instead the six-coordinate [PhC(NSiMe3)2]2ScMe-
(THF) in good yield.
F igu r e 1. ORTEP view of [PhC(NSiMe3)2]2Sc(µ-Cl)2Li-
(TMEDA) drawn with 50% thermal ellipsoids. Hydrogens
were omitted for clarity.
experimental error and are only slightly more acute
than that reported20 for Cp*2Y(µ-Cl)2Li(THF)2 (84.8(1)°).
Coordination about the lithium atoms is roughly tetra-
hedral with average bond lengths of 2.38 and 2.07 Å
for Li-Cl and Li-N bonds, respectively. Bond angles
about the lithium atoms are typical with average values
of 91.2 and 88.5° for Cl-Li-Cl and N-Li-N angles,
respectively.
As shown in Scheme 1, [RC(NSiMe3)2]2ScCl(THF)
compounds (R ) Ph, Tol) are good starting materials
for the preparation of a wide range of new derivatives.
Reaction of [TolC(NSiMe3)2]2ScCl(THF) with NaBH4 in
THF, followed by extraction with hexanes, yielded
colorless crystals of [TolC(NSiMe3)2]2Sc(BH4)(THF). IR
data are consistent21 with bidentate coordination of the
borohydride ligand, showing absorptions at 2463 and
2388 cm-1 assignable to the (A1, B1) B-H(terminal)
[PhC(NSiMe3)2]2ScCH2SiMe3 reacted with H2 (1 atm)
at room temperature in hexanes or benzene to give 1
equiv of Me4Si and the hydride {[PhC(NSiMe3)2]2ScH}2.
This may also be prepared from either [PhC(NSiMe3)2]2-
ScMe(THF) or [PhC(NSiMe3)2]2ScMes, but these reac-
(19) Atwood, J . L.; Smith, K. D. J . Chem. Soc., Dalton Trans. 1973,
2487.
(20) Marsh, R. E.; Schaefer, W. P.; Coughlin, E. B.; Bercaw, J . E.
Acta. Crystallogr. 1992, C48, 1773.
(22) 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.
(23) Wedler, M.; Knosel, F.; Noltemeyer, M.; Edelmann, F. T.;
Behrens, U. J . Organometallic Chem. 1990, 388, 21.
(21) Marks, T. J .; Kolb, J . R. Chem. Rev. 1977, 77, 263.

986 Organometallics, Vol. 15, No. 3, 1996
Hagadorn and Arnold
tance of 3.30 Å. Each of the amidinate ligands is
coordinated with the Sc atom in the N-C-N plane.
The hydride is quite thermally robust in C6D6 solution
showing only trace decomposition after heating to 60
°C for 24 h, and no exchange was observed with D2 (15
psig) under the same conditions. Additionally, the
dimeric structure remained intact even after heating in
the presence of THF. Ethylene and propylene failed to
react at room temperature; however, at 60 °C ethylene
is sluggishly polymerized and propene appears to un-
dergo multiple insertions. Heating was also required
to initiate the reaction of Me3SiCCH, where, at 60 °C,
multiple products were formed. The absence of H2 and
the presence of several vinylic peaks in the 1H NMR
spectrum are consistent with initial insertion of alkyne
into the Sc-H bond; however, no pure product could be
isolated. [PhC(NSiMe3)2]2ScCCSiMe3 was also detected
by 1H NMR spectroscopy indicative of competing σ-bond
metathesis and insertion pathways.
Reaction of {[PhC(NSiMe3)2]2ScH}2 with the internal
alkyne Ph2C2 in refluxing benzene cleanly gives yellow
crystals of the single insertion product, [PhC(NSiMe3)2]2-
ScC(Ph)dC(Ph)H, in 40% isolated yield. In contrast,
reaction of [PhC(NSiMe3)2]2ScCH2SiMe3 with Me3-
SiCCH in C6D6 was found to give exclusively the σ-bond
metathesis product [PhC(NSiMe3)2]2ScCCSiMe3, which
we formulate as a monomeric species in solution on the
basis of a single sharp -SiMe3 signal for the amidinate
ligands in the 1H NMR. This is in contrast to the
dimeric {[PhC(NSiMe3)2]2Y(µ-CCH)}2, which was re-
cently reported13 by Teuben. Further equivalents of the
alkyne reacted with the acetylide at 60 °C, yielding an
uncharacterized mixture of products. Details of the
reactions of the hydride and alkyl derivatives with
ethylene and higher olefins will be presented sepa-
rately.30
In summary, the scandium chloride [PhC(NSiMe3)2]2-
ScCl(THF) has been shown to be a good starting
material for the preparation of a wide range of new
alkyl, amido, and borohydride derivatives. The alkyl
derivatives react with dihydrogen under mild conditions
to yield the dimeric hydride with the liberation of RH.
Reaction of alkyl and hydride derivatives with terminal
and internal alkynes reveals competing insertion and
σ-bond metathesis pathways.
F igu r e 2. ORTEP view of {[PhC(NSiMe3)2]2ScH}2 drawn
with 50% thermal ellipsoids. Methyl groups and non-
hydridic hydrogens were omitted for clarity.
tions require elevated temperatures (ca. 70 °C) to
1
proceed at reasonable rates. The H NMR spectrum of
{[PhC(NSiMe3)2]2ScH}2 shows two broad, partially-
overlapped peaks for the -SiMe3 groups of the amidi-
nate ligands, once again indicative of a sterically
congested metal center. These signals coalesce at 37
°C corresponding to a barrier to ligand rotation of ∆Gq
) 10(1) kcal/mol. We did not detect the hydride
1
resonance in the H NMR presumably due to coupling
to the quadrupolar 45Sc (I ) 7/2). Bercaw and co-workers
have reported22 observing broadened hydride signals in
the related Cp*2Sc system. IR spectroscopy revealed a
broad band at 1283 cm-1 that is consistent with early
metal bridging hydrides.5,24 This band is absent in the
deuteride which showed a new band (partially obscured)
at 907 cm-1. Crystals of the hydride for X-ray diffrac-
tion studies were prepared by the blanketing of H2 onto
a hexanes solution of [PhC(NSiMe3)2]2ScCH2SiMe3 at
room temperature. An ORTEP view of the molecular
structure is shown in Figure 2. Each Sc is coordinated
in a distorted octahedral fashion with the bridging
hydrides, which were located and refined isotropically,
roughly equidistant to both metal centers. The Sc-H
bond distances range from 1.87(3) to 2.00(3) Å and are
typical of early metal bridging hydride ligands,25-27 but
there are almost no reliable Sc-H bond distances from
crystal structure analyses reported in the literature for
comparison.5 Borohydride and dicarbollide derivatives
display longer Sc-H bond lengths of 2.03 and 2.18 Å
for [C5H3(SiMe3)2]2ScBH428 and [Cp*(C2B9H11)ScH]2[Li-
(THF)n]2,29 respectively. The Sc2H2 core is planar with
H-Sc-H angles of 61(1) and 65(1)° and a Sc-Sc dis-
Exp er im en ta l Section
Gen er a l Con sid er a tion s. Standard Schlenk-line and
glovebox techniques were used throughout.31 Tetrahydrofuran
(THF), diethyl ether, hexamethyldisiloxane (HMDSO), and
hexanes were dried over 4-Å molecular sieves and then
distilled from sodium/benzophenone under nitrogen. Dichlo-
romethane (from sieves) was distilled from CaH2 under
nitrogen. C6D6 was predried over 4-Å molecular sieves,
degassed with three freeze-pump-thaw cycles, and vacuum
transferred from sodium/benzophenone. H2 and D2 were used
directly from cylinders without purification. The compounds
ScCl3(THF)3,32,33 Li[RC(NSiMe3)2](TMEDA),34 Na[RC(NSiMe3)2]
(24) Bercaw, J . E.; Brintzinger, H. H. J . Am. Chem. Soc. 1969, 91,
7301.
(25) Takahashi, T.; Hasegawa, M.; Suzuki, N.; Saburi, M.; Rousset,
C. J .; Fanwich, P. E.; Negishi, E. J . Am. Chem. Soc. 1991, 113, 8564.
(26) Bochmann, M.; Lancaster, S. J .; Hursthouse, M. B.; Mazid, M.
Organometallics 1993, 12, 4718.
(27) J ones, S. B.; Petersen, J . L. Inorg. Chem. 1981, 20, 2889.
(28) Lappert, M. F.; Singh, A.; Atwood, J . L.; Hunter, W. E. J . Chem.
Soc., Chem. Commun. 1983, 206.
(30) Hagadorn, J . R.; Arnold, J . Manuscript in preparation.
(31) Shriver, D. F.; Dredzon, M. A. The Manipulation of Air-Sensitive
Compounds, 2nd ed.; Wiley-Interscience: New York, 1986.
(32) Piers, W. E.; Shapiro, P. J .; Bunel, E. E.; Bercaw, J . E. Synlett
1990, 74.
(33) Manzer, L. E. Inorg. Synth. 1982, 21, 135.
(34) Dick, D. G.; Duchateau, R.; Edema, J . H.; Gambarotta, S. Inorg.
Chem. 1993, 32, 1959.
(29) Bazan, G. C.; Schaefer, W. P.; Bercaw, J . E. Organometallics
1993, 12, 2126.

Sc Complexes with Benzamidinate Ligands
Organometallics, Vol. 15, No. 3, 1996 987
(R ) Ph, Tol),23,35,36 LiCH2SiMe3,37 and LiCH2SiMe2Ph37 were
prepared according to literature procedures. (Et2O)LiMes was
prepared by the addition of n-BuLi to the aryl bromide in Et2O.
colorless solution. MeLi (2.11 mmol, 1.42 M in Et2O) was
added dropwise causing white precipitate to form. After the
mixture was stirred overnight, the volatiles were removed
under reduced pressure to give a colorless residue, which was
extracted with hexanes (50 mL) and filtered through a pad of
Celite on a fritted disk. Concentration to 10 mL and cooling
to -40 °C yielded the product as small colorless crystals (1.0
g, 65%). Recrystallization from Et2O afforded analytically pure
LiNHC6H3-2,6-Pri was prepared by addition of the amine to
2
n-butyllithium in hexanes. Melting points were determined
in sealed capillary tubes under nitrogen and are uncorrected.
1H and 13C{1H} NMR spectra were recorded at ambient
temperatures. Chemical shifts (δ) are given relative to
residual protium in the deuterated solvent at 7.15 (C6D6). IR
samples were prepared as Nujol mulls and taken between KBr
plates unless stated otherwise. Elemental analyses and mass
spectral data were determined within the College of Chemis-
try, University of California, Berkeley, CA. Single-crystal
X-ray structure determinations were performed at CHEXRAY,
University of California, Berkeley, CA.
product. Mp: 113-126 °C. 1H NMR (C6D6, 400 MHz):
δ
7.25-7.20 (m, 4H), 7.10-7.00 (m, 6H), 4.17 (m, 4H), 1.50 (m,
4H), 0.12 (s, 36H), 0.03 (s, 3H). 13C{1H} NMR (C6D6, 75.5
MHz): δ 182.4, 142.9, 128.1, 126.4, 72.0, 25.5, 2.6. IR: 1434
(s), 1403 (s), 1255 (sh), 1246 (s), 1169 (w), 1094 (w), 1073 (w),
1020 (m), 1010 (m), 1001 (m), 984 (s), 917 (m), 845 (s, br), 785
(m), 761 (s), 732 (m), 701 (m), 683 (w), 604 (w), 498 (m) cm-1
.
[TolC(NSiMe3)2]2ScCl(THF ). Tetrahydrofuran (75 mL)
was added to ScCl3(THF)3 (3.10 g, 8.43 mmol) and Na[TolC-
(NSiMe3)2](Et2O) (6.32 g, 16.9 mmol) in a 250-mL round-
bottomed flask forming an orange, slightly cloudy solution.
After the solution was stirred overnight, the volatiles were
removed under reduced pressure. The resulting orange-red
solid was extracted with Et2O (90 mL) and filtered through a
pad of Celite on a fritted disk. Concentration to 15 mL
followed by cooling to -40 °C gave the product as colorless
crystals (2.85 g, 47.8%). Mp: 160-170 °C. 1H NMR (C6D6,
300 MHz): δ 7.21 (d, J ) 8.0 Hz, 4 H), 6.89 (d, J ) 7.9 Hz, 4
H), 4.32 (m, 4 H), 2.03 (s, 6 H), 1.46 (m, 4 H), 0.18 (s, 36H).
13C{1H} NMR (C6D6, 75.5 MHz): δ 183.3, 139.7, 138.1, 128.8,
126.5, 73.1, 25.5, 21.2, 2.6. IR: 1658 (w), 1613 (w), 1444 (s,
br), 1393 (m), 1245 (m), 1166 (w), 1110 (w), 1010 (w), 986 (m),
845 (s, br), 759 (m), 644 (w), 467 (m) cm-1. Anal. Calcd for
Anal. Calcd for C31H57N4OScSi4: C, 56.49; H, 8.72; N, 8.50.
Found: C, 56.24; H, 8.79; N, 8.78.
[P h C(NSiMe3)2]2ScCH2SiMe3. Toluene (20 mL) was added
to a 100-mL round-bottomed flask containing [PhC(NSiMe3)2]2-
ScCl(THF)(Et2O)0.8 (0.750 g, 1.01 mmol) and LiCH2SiMe3 (95.0
mg, 1.01 mmol) forming a cloudy colorless solution. After the
solution was stirred overnight, the volatiles were removed
under reduced pressure. The remaining cloudy oil was
extracted with hexanes (25 mL) and filtered through a pad of
Celite on a fritted disk. The solvent was then removed under
reduced pressure and HMDSO (15 mL) was added forming a
clear colorless solution. Concentration to 0.5 mL and cooling
to -40 °C failed to induce crystallization. Crystalline product
was obtained by concentrating the HMDSO solution to a sticky
oil and leaving it at room temperature overnight (0.35 g, 53%).
Subsequent batches of product were crystallized by the addi-
tion of a seed crystal. Mp: 106-108 °C. 1H NMR (C6D6, 400
MHz): δ 7.20-7.17 (m, 4H), 7.08-6.80 (m, 6H), 0.47 (s, 9H),
0.41 (s, 2H), 0.12 (s, 36H). 13C{1H} NMR (C6D6, 75.5 MHz):
δ 184.7, 141.3, 128.8, 128.2, 126.7, 4.7, 2.7. IR: 1432 (s), 1402
(s), 1248 (m), 1168 (w), 1074 (w), 1032 (w), 1002 (w), 986 (m),
C
32H58ClN4OScSi4: C, 54.32; H, 8.26; N, 7.92. Found: C,
54.18; H, 8.25; N, 7.86.
[P h C(NSiMe3)2]2ScCl(THF )(Et2O)n . A 250-mL round-
bottomed flask was loaded with ScCl3(THF)3 (4.47 g, 12.2
mmol) and Na[PhC(NSiMe3)2](Et2O)1.25 (9.22 g, 24.3 mmol).
Tetrahydrofuran (125 mL) cooled to -50 °C was added forming
a colorless suspension. After the mixture had stirred overnight
at room temperature, the volatiles were removed under
reduced pressure and the resulting white solid was extracted
with Et2O (125 mL). Filtration through a Celite pad on a
fritted disk followed by concentration to 25 mL and cooling to
-40 °C yielded the product as colorless crystals. Et2O content
was determined by 1H NMR spectroscopy. Total yield from
two crops: 6.7 g, 74%. 1H NMR (C6D6, 300 MHz): δ 7.28-
7.22 (m, 4H), 7.08-7.00 (m, 6H), 4.28 (m, 4H), 3.27 (q, 1.9H),
1.45 (m, 4H), 1.11 (t, 2.8H), 0.14 (s, 36H).
918 (w), 945 (s, br), 761 (m), 721 (w), 701 (w), 504 (m) cm-1
.
Anal. Calcd for C30H57N4ScSi5: C, 54.66; H, 8.72; N, 8.50.
Found: C, 54.54; H, 8.78; N, 8.35.
[P h C(NSiMe3)2]2ScCH2SiMe2P h . To a 100-mL round-
bottomed flask was added [PhC(NSiMe3)2]2ScCl(THF) (0.500
g, 0.674 mmol), LiCH2SiMe2Ph (0.105 g, 0.674 mmol), and
toluene (20 mL) forming a cloudy colorless solution. After the
solution was stirred overnight, the volatiles were removed
under reduced pressure. The resulting oily solid was extracted
with hexanes (40 mL) and filtered through a pad of Celite on
a fritted disk. The volatiles were again removed under reduced
pressure, and HMDSO (15 mL) was added. Concentration to
3 mL followed by cooling to -40 °C yielded product as small
colorless crystals (0.26 g, 53%). Mp: 102-103 °C. 1H NMR
(C6D6, 400 MHz): δ 7.88 (dd, J ) 1.4, 8.0 Hz, 2H), 7.34 (t, J )
7.4 Hz, 2H), 7.23 (t, J ) 7.4 Hz, 1 H), 7.20-7.15 (m, 4H), 7.05-
6.96 (m, 6H), 0.68 (s, 6H), 0.58 (s, 2H), 0.07 (s, 36H). 13C{1H}
NMR (C6D6, 75.5 MHz): δ 184.7, 146.1, 141.2, 134.1, 128.9,
128.1, 127.2, 126.7, 3.6, 2.7.
[P h C(NSiMe3)2]2Sc(µ-Cl)2Li(TMEDA). In a 100-mL round-
bottomed flask, THF (40 mL) cooled to -40 °C was added to
[PhC(NSiMe3)2]Li(TMEDA) (2.10 g, 5.44 mmol) and ScCl3-
(THF)3 (1.00 g, 2.72 mmol) forming a white slurry. The
mixture was stirred overnight at room temperature giving a
clear, slightly yellow solution. The volatiles were removed
under reduced pressure affording a white solid. Extraction
with Et2O (70 mL) followed by filtration through a Celite pad
on a fritted disk gave a clear, pale yellow solution. Concentra-
tion of the solution to 35 mL followed by cooling to -40 °C
produced the product as small colorless crystals (1.1 g, 52%).
Mp: 210-228 °C. 1H NMR (C6D6, 300 MHz): δ 7.40-7.35 (m,
4 H), 7.08-7.00 (m, 6 H), 2.10 (s, 12 H), 1.70 (s, 4 H), 0.28 (s,
36 H). 13C{1H} NMR (CDCl3, 75.5 MHz): δ 181.7, 141.8, 127.7,
127.5, 126.5, 57.0, 46.0, 2.4. IR: 1292 (w), 1259 (w), 1242 (m),
986 (m), 844 (s, br), 785 (w), 763 (m), 731 (w), 702 (m), 604
[P h C(NSiMe3)2]2ScMes. Toluene (25 mL) was added to a
100-mL round-bottomed flask containing [PhC(NSiMe3)2]2-
ScCl(THF) (0.500 g, 0.674 mmol) and (Et2O)LiMes (0.135 g,
0.674 mmol) forming a white suspension. After the mixture
was stirred overnight, the volatiles were removed under
reduced pressure. The resulting white solid was extracted
with hexanes (40 mL) and filtered. Concentration of the clear
colorless filtrate to 8 mL followed by cooling to -40 °C yielded
the product as small colorless crystals. Two crops yielded 0.24
g (51%). Mp: 167-168 °C. 1H NMR (C6D6, 400 MHz): δ 7.25
(br, 4 H), 7.07-6.98 (m, 6H), 6.91 (s, 2H), 2.90 (s, 6H), 2.27 (s,
3H), 0.03 (br, 36H). 13C{1H} NMR (C6D6, 75.5 MHz): δ 184.1,
142.0, 141.2, 135.6, 128.8, 126.4 (br), 125.8, 25.1, 21.7, 2.6.
IR: 1592 (w), 1424 (s, br), 1247 (m), 1170 (w), 1034 (w), 1011
(w), 1002 (w), 986 (m), 914 (w), 843 (s, br), 790 (w), 761 (m),
720 (w), 704 (w), 685 (w), 604 (w), 546 (w), 506 (m) cm-1. Anal.
(w), 494 (m) cm-1
. Anal. Calcd for C32H62Cl2LiN6ScSi4: C,
50.17; H, 8.16; N, 10.97. Found: C, 50.12; H, 8.38; N, 10.96.
[P h C(NSiMe3)2]2ScMe(THF ). In a 100-mL round-bot-
tomed flask, [PhC(NSiMe3)2]2ScCl(THF)(Et2O)0.4 (1.50 g, 2.11
mmol) and Et2O (45 mL) were combined forming a clear
(35) Sanger, A. R. Inorg. Nucl. Chem. Lett. 1973, 9, 351.
(36) Hontz, A. C.; Wagner, E. C. Org. Synth. 1951, 31, 48.
(37) Tessier-Youngs, C.; Beachley, O. T. Inorg. Synth. 1984, 24, 95.

988 Organometallics, Vol. 15, No. 3, 1996
Ta ble 1. Cr ysta l Da ta a n d Collection P a r a m eter s
Hagadorn and Arnold
{[PhC(NSiMe3)2]2ScH}2
[PhC(NSiMe3)2]2Sc(µ-Cl)2Li(TMEDA)
formula
fw
space group
temp (°C)
a (Å)
C52H94N8Sc2Si8
1145.97
P21/n (No. 14)
-150
16.279(3)
19.852(4)
21.025(4)
6780(3)
90
C64H124Cl4Li2N12Sc2Si8
1532.06 (two indep. molecules)
P1h (No. 2)
-102
15.418(4)
16.526(4)
18.900(4)
4470(3)
102.72(2)
106.18(1)
93.75(2)
2
b (Å)
c (Å)
V (Å3)
R (deg)
â (deg)
γ (deg)
Z
93.80(1)
90
4
d
calc (g/cm3)
1.12
1.06
diffractometer
radiation
monochromator
detector
Siemens SMART
Mo KR
Siemens SMART
Mo KR
graphite
CCD area detector
ω, 0.3
graphite
CCD area detector
ω, 0.3
scan type, deg
frame collcn time (s)
reflcns measd
2θ range (deg)
30
30
hemisphere
3-46.5
0.38
0.828, 0.879
0.40 × 0.30 × 0.20
21 515
9501
7771
639
3.12
hemisphere
3.1-46.5
0.16
0.854, 0.946
0.40 × 0.15 × 0.20
17 854
12 321
9755
829
4.42
µ (mm-1
min, Tmax
)
T
cryst dimens (mm)
no. of reflcns measd
no. of unique reflcns
no. of observns (I > 3σ)
no. of parameters
Rint (%)
R (%)
4.11
9.94
Rw (%)
6.85
9.51
GOF
2.41
7.51
Ta ble 2. Selected Da ta for
Ta ble 3. Selected Da ta for {[P h C(NSiMe3)2]2ScH}2
[P h C(NSiMe3)2]2Sc(µ-Cl)2Li(TMEDA)
Bond Distances (Å)
Sc1-H1
Sc1-H2
Sc1-N1
Sc1-N2
Sc1-N3
Sc1-N4
Sc1-Sc2
1.92(3)
1.87(3)
Sc2-H1
Sc2-H2
Sc2-N5
Sc2-N6
Sc2-N7
Sc2-N8
2.00(3)
1.98(3)
2.235(3)
2.225(3)
2.187(3)
2.224(3)
Bond Distances (Å)
Sc1-Cl1
Sc1-Cl2
Sc1-N1
Sc1-N2
Sc1-N3
2.557(3)
2.545(3)
2.230(5)
2.182(5)
2.199(5)
Sc1-N4
Li1-Cl1
Li1-Cl2
Li1-N9
Li1-N10
2.196(5)
2.38(1)
2.35(1)
2.13(1)
2.04(1)
2.219(3)
2.192(3)
2.205(3)
2.236(3)
3.3077(8)
Bond Angles (deg)
Bond Angles (deg)
Cl1-Sc1-Cl2
N1-Sc1-N2
N3-Sc1-N4
N1-Sc1-N3
N2-Sc1-N4
N2-Sc1-Cl1
N2-Sc1-Cl2
N4-Sc1-Cl1
N4-Sc1-Cl2
N1-Sc1-Cl1
N1-Sc1-Cl2
83.37(9)
N2-Sc1-Cl1
167.2(1)
91.6(2)
92.0(3)
92.9(3)
91.5(4)
87.7(5)
118.0(6)
127.3(5)
117.6(5)
117.5(6)
H1-Sc1-H2
H1-Sc1-N1
H1-Sc1-N2
H1-Sc1-N3
H1-Sc1-N4
N1-Sc1-N2
N1-Sc1-N3
N1-Sc1-N4
N2-Sc1-N3
65(1)
N2-Sc1-N4
H2-Sc1-N1
H2-Sc1-N2
H2-Sc1-N3
H2-Sc1-N4
H1-Sc2-H2
N5-Sc2-N8
N6-Sc2-N7
105.1(1)
110(1)
103(1)
147(1)
90(1)
61(1)
154.4(1)
103.8(1)
62.8(2)
62.2(2)
151.1(2)
97.3(2)
167.2(1)
91.6(2)
89.8(1)
167.3(2)
105.9(1)
95.7(2)
N2-Sc-Cl2
86(1)
Li1-Cl1-Sc1
Li1-Cl2-Sc1
Cl1-Li1-Cl2
N9-Li1-N10
N9-Li1-Cl1
N9-Li1-Cl2
N10-Li1-Cl1
N10-Li1-Cl2
141(1)
106(1)
112(1)
62.2(1)
100.8(1)
157.6(1)
102.1(1)
[P h C(NSiMe3)2]2ScC(P h )dC(P h )H. To a 100-mL round-
bottomed flask containing {[PhC(NSiMe3)2]2ScH}2 (0.166 g,
0.145 mmol) and Ph2C2 (51.6 mg, 0.290 mmol) was added
benzene (20 mL) forming a clear colorless solution. The
solution was heated to reflux forming a clear yellow solution.
After the solution was stirred overnight, the volatiles were
removed under reduced pressure. The resulting yellow solid
was extracted with hexanes (35 mL) and filtered. Concentra-
tion of the clear yellow filtrate to 15 mL followed by cooling to
-10 °C afforded the product as clear yellow crystals. Two
crops yielded 87 mg (40%). Mp: 214-231 °C. 1H NMR (C6D6,
400 MHz): δ 7.67-7.60 (m, 4H), 7.45-7.35 (m, 4H), 7.28 (s,
1H), 7.20-7.16 (m, 2H), 7.14-7.07 (m, 4H), 7.05-6.96 (m, 6H),
0.03 (s, 36H). 13C{1H} NMR (C6D6, 75.5 MHz): δ 184.1, 152.5,
145.2, 141.0, 138.4, 129.2, 128.7, 128.5, 128.1, 127.4, 127.1,
126.5, 126.0, 124.6, 2.3. IR: 1590 (w), 1421 (m), 1245 (m),
1168 (w), 1074 (w), 1032 (w), 1002 (w), 987 (m), 920 (w), 840
(s, br), 784 (w), 761 (m), 723 (m), 702 (m), 506 (m) cm-1. Anal.
Calcd for C40H57N4ScSi4: C, 63.95; H, 7.65; N, 7.46. Found:
C, 63.81; H, 7.71; N, 7.61.
Calcd for C35H57N4ScSi4: C, 60.82; H, 8.31; N, 8.11. Found:
C, 60.63; H, 8.41; N, 7.89.
{[P h C(NSiMe3)2]2ScH}2. In a 100-mL Schlenk tube, the
addition of hexanes (10 mL) to [PhC(NSiMe3)2]2ScCH2SiMe3
(0.50 g, 0.76 mmol) formed a clear colorless solution. The flask
was evacuated briefly and then backfilled with H2 (ca. 5 psig).
After remaining undisturbed overnight, analytically pure
product was isolated as colorless crystals (0.34 g, 79%). Mp:
199-205 °C (dec with gas evolution). 1H NMR (C6D6, 300
MHz): δ 7.60-7.40 (br, 4H), 7.18-6.90 (br), 0.32 (br, 18H),
0.15 (br, 18H). 13C{1H} NMR (C6D6, 75.5 MHz): δ 185.4, 142.3,
128.6, 126.6, 4.3, 3.0. IR: 1447 (s, br), 1434 (s, br), 1283 (m,
br), 1260 (m, sh), 1246 (m), 1168 (w), 1030 (w), 1002 (m, sh),
985 (s), 932 (w), 845 (s, br), 786 (w), 761 (m), 745 (w), 723 (w),
698 (m), 604 (w), 496 (m) cm-1
. IR (CaF2, C6D6): 3061 (w),
2954 (m), 2896 (w), 1435 (s, br), 1406 (s, br), 1290 (m, br), 1260
(m, sh), 1246 (s), 1162 (w), 1074 (w), 1030 (w), 1002 (m, sh),
985 (s), 942 (m), 933 (m) cm-1. Anal. Calcd for C52H94N8Sc2-
Si8: C, 54.50; H, 8.27; N, 9.78. Found: C, 54.13; H, 8.39; N,
9.48.

Sc Complexes with Benzamidinate Ligands
Organometallics, Vol. 15, No. 3, 1996 989
Ta ble 4. P osition a l P a r a m eter s a n d Equ iva len t Isotr op ic Disp la cem en t Coefficien ts for
[P h C(NSiMe3)2]2Sc(µ-Cl)2Li(TMEDA)
atom
x
y
z
B(eq) (Å2)
atom
x
y
z
B(eq) (Å2)
Sc1
Sc2
Cl1
Cl2
Cl3
Cl4
Si1
Si2
Si3
Si4
Si5
Si6
Si7
Si8
N1
N2
N3
N4
N5
N6
N7
N8
N9
N10
N11
N12
C1
C2
C3
C4
C5
C6
C7
0.21294(8)
0.80857(8)
0.3493(2)
0.1837(2)
0.6673(2)
0.8296(2)
0.0762(1)
0.0272(1)
0.3579(1)
0.2661(1)
0.7590(1)
0.6640(1)
0.9944(1)
0.9400(1)
0.1005(3)
0.0788(3)
0.2968(3)
0.2668(3)
0.7600(3)
0.7276(3)
0.9443(4)
0.9191(3)
0.3047(4)
0.4025(5)
0.6043(4)
0.6973(4)
0.1685(6)
0.0681(6)
-0.0314(6)
-0.0928(5)
0.0923(5)
0.0330(6)
0.0439(4)
-0.0581(4)
-0.1016(5)
-0.1989(6)
-0.2419(6)
-0.1976(6)
-0.1078(5)
0.4803(6)
0.3055(6)
0.3557(6)
0.1491(6)
0.3424(7)
0.3080(6)
0.3099(4)
0.21765(8)
0.29148(7)
0.2635(2)
0.0961(2)
0.2474(2)
0.4185(2)
0.3504(1)
0.1116(1)
0.0969(1)
0.4180(1)
0.0835(1)
0.4004(1)
0.3756(1)
0.1780(1)
0.2846(3)
0.1846(3)
0.1782(3)
0.3123(3)
0.1917(3)
0.3218(3)
0.3175(3)
0.2317(3)
0.1750(5)
0.0720(4)
0.4421(4)
0.3333(4)
0.3527(6)
0.4579(6)
0.3146(7)
0.1177(6)
0.1289(5)
0.0061(5)
0.2346(5)
0.2333(5)
0.2966(5)
0.2901(7)
0.2245(8)
0.1668(6)
0.1677(5)
0.1153(5)
-0.0007(5)
0.0786(6)
0.4357(5)
0.4738(5)
0.4697(5)
0.2567(4)
0.01476(6)
0.48359(6)
0.1350(1)
0.0712(2)
0.3669(1)
0.4330(2)
0.1167(1)
-0.1560(1)
-0.0879(1)
-0.0223(1)
0.5113(1)
0.5928(1)
0.6579(1)
0.3639(1)
0.0416(3)
-0.0703(3)
-0.0604(3)
-0.0325(3)
0.5275(3)
0.5626(3)
0.5643(3)
0.4467(3)
0.2965(4)
0.2099(4)
0.2961(3)
0.2080(3)
0.2050(4)
0.1044(5)
0.1332(5)
-0.2046(4)
-0.2214(4)
-0.1382(5)
-0.0220(4)
-0.0387(4)
-0.0644(5)
-0.0784(6)
-0.0608(7)
-0.0322(7)
-0.0216(5)
-0.0256(5)
-0.0756(5)
-0.1900(5)
-0.0671(5)
-0.0646(5)
0.0812(4)
-0.0670(3)
2.23(4)
2.15(4)
5.40(8)
7.4(1)
5.71(9)
7.1(1)
3.53(7)
3.18(7)
3.27(7)
3.03(7)
2.86(6)
3.39(7)
3.01(6)
3.06(7)
2.5(2)
2.9(2)
2.7(2)
2.6(2)
2.5(2)
2.3(2)
2.4(2)
2.3(2)
4.3(3)
4.5(3)
3.2(2)
3.8(2)
4.7(3)
4.9(3)
5.9(4)
4.7(3)
4.0(3)
5.1(3)
3.0(2)
3.4(2)
4.6(3)
6.2(4)
7.2(5)
6.1(4)
4.2(3)
4.9(3)
4.3(3)
5.0(3)
4.9(3)
5.3(4)
4.1(3)
2.5(2)
C21
C22
C23
C24
C25
C26
C27
C28
C29
C30
C31
C32
C33
C34
C35
C36
C37
C38
C39
C40
C41
C42
C43
C44
C45
C46
C47
C48
C49
C50
C51
C52
C53
C54
C55
C56
C57
C58
C59
C60
C61
C62
C63
C64
Li1
0.3727(4)
0.3400(6)
0.3970(8)
0.4863(7)
0.5200(5)
0.4639(5)
0.4897(8)
0.3786(7)
0.410(1)
0.2810(4)
0.2790(6)
0.3036(6)
0.3275(7)
0.3323(6)
0.3084(5)
0.1049(7)
-0.0140(6)
0.072(1)
-0.1084(4)
-0.1857(4)
-0.2229(5)
-0.1879(7)
-0.1123(6)
-0.0730(5)
0.199(1)
2.5(2)
4.5(3)
6.1(4)
6.2(5)
5.5(4)
4.1(3)
11.5(7)
6.2(4)
13(1)
0.1634(6)
0.2867(7)
0.3239(8)
0.3418(5)
0.3040(6)
0.5158(5)
0.4144(4)
0.5795(4)
0.5701(5)
0.5409(6)
0.6979(5)
0.5624(3)
0.5961(4)
0.5512(4)
0.5825(5)
0.6589(5)
0.7052(4)
0.6741(4)
0.6602(5)
0.7189(4)
0.6946(4)
0.3812(4)
0.3167(4)
0.3012(4)
0.5142(3)
0.5291(4)
0.5631(5)
0.5751(5)
0.5517(6)
0.5150(5)
0.5054(4)
0.3080(6)
0.3427(5)
0.2185(5)
0.1724(5)
0.1713(5)
0.1954(6)
0.1818(6)
0.3226(6)
0.367(1)
0.114(1)
14(1)
0.3335(8)
0.2186(7)
0.8756(6)
0.6798(5)
0.7251(6)
0.6994(7)
0.5381(6)
0.6826(7)
0.7157(4)
0.6453(5)
0.5617(5)
0.5002(6)
0.5218(6)
0.6075(6)
0.6704(5)
0.9645(7)
0.9409(6)
1.1185(5)
1.0281(5)
0.9804(7)
0.8344(6)
0.9774(5)
1.0770(4)
1.1133(5)
1.2116(6)
1.2598(7)
1.2187(6)
1.1313(5)
0.5193(6)
0.6229(5)
0.5939(6)
0.6060(6)
0.7007(7)
0.7684(6)
0.3071(8)
0.7009(9)
0.2584(8)
0.1480(7)
0.0608(4)
0.0323(5)
0.0314(5)
0.4971(5)
0.3719(6)
0.4261(6)
0.2409(4)
0.2092(4)
0.1689(5)
0.1390(6)
0.1473(7)
0.1830(5)
0.2154(5)
0.4824(6)
0.3315(7)
0.3819(6)
0.1045(5)
0.2547(6)
0.1125(6)
0.2713(4)
0.2636(4)
0.2044(5)
0.2001(6)
0.253(1)
7.2(5)
6.6(4)
4.3(3)
3.8(3)
4.3(3)
5.1(3)
6.6(4)
5.4(4)
2.7(2)
3.2(2)
3.9(3)
5.1(3)
5.6(4)
4.8(3)
3.9(3)
6.1(4)
5.7(4)
4.9(3)
4.1(3)
5.3(4)
5.2(3)
2.5(2)
2.9(2)
4.6(3)
6.1(4)
7.9(5)
5.4(4)
4.2(3)
6.0(4)
4.3(3)
4.9(3)
5.0(3)
6.2(4)
6.1(4)
3.3(4)
3.5(4)
C8
C9
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
0.3114(7)
0.3180(5)
0.4022(6)
0.5271(5)
0.4419(6)
0.3563(6)
0.2433(6)
0.3845(7)
0.1490(8)
0.3671(7)
Li2
{[P h C(NSiMe3)2]2ScD}2. The procedure for the prepara-
tion of {[PhC(NSiMe3)2]2ScH}2 was followed except H2 was
replaced by D2. IR: 1446 (s, br), 1404 (s, br), 1260 (m, sh),
1246 (s), 1169 (w), 1074 (w), 1002 (m, sh), 984 (s), 907 (s, br),
840 (s, br), 786 (m), 761 (m), 745 (m), 723 (m), 701 (m), 664
C32H62BN4OScSi4: C, 55.95; H, 9.10; N, 8.16. Found: C, 55.83;
H, 9.05; N, 7.96.
[P h C(NSiMe3)2]2ScNHC6H3-2,6-P r i2. To a 100-mL round-
bottomed flask containing [PhC(NSiMe3)2]2ScCl(THF)(Et2O)0.8
(2.00 g, 2.70 mmol) and LiNHC6H3-2,6-Pri (0.490 g, 2.70 mmol)
was added toluene (40 mL) forming a cloudy, dirty yellow
solution. After the solution was stirred overnight, the volatiles
were removed under reduced pressure. The remaining yellow-
orange solid was extracted with hexanes (75 mL) and filtered
through a pad of Celite on a fritted disk. Concentration to 20
mL and cooling to -40 °C yielded the product as large colorless
crystals. Total yield from two crops: 1.5 g, 74% Mp: 162-
163 °C. 1H NMR (C6D6, 400 MHz): δ 7.30-7.25 (m, 4H), 7.20
(d, J ) 7.6 Hz, 2H), 7.05-7.00 (m, 6H), 6.92 (t, J ) 7.6 Hz,
1H), 5.86 (br, 1H), 3.40 (sept, J ) 6 8 Hz, 2H), 1.54 (d, J ) 6.8
Hz, 12H), 0.04 (s, 36H). 13C{1H} NMR (C6D6, 75.5 MHz): δ
184.8, 150.5, 141.5, 133.8, 128.9, 128.3, 126.6, 123.0, 117.1,
30.3, 24.0, 2.4. IR: 1736 (w), 1590 (w), 1447 (s), 1430 (s), 1334
(w), 1263 (m), 1247 (m), 1170 (w), 1008 (w), 984 (m), 916 (w),
843 (s, br), 786 (w), 761 (m), 746 (w), 701 (w), 574 (w), 505 (m)
cm-1. Anal. Calcd for C38H66N5ScSi4: C, 60.83; H, 8.87; N,
9.33. Found: C, 60.71; H, 8.81; N, 9.31.
(w), 605 (w), 515 (m), 491 (m) cm-1
. IR (CaF2, C6D6): 3061
(w), 2954 (m), 2896 (w), 1434 (s, br), 1405 (s, br), 1260 (m, sh),
1246 (s), 1162 (w), 1074 (w), 1002 (m, sh), 984 (s), 932 (m),
916 (s), 908 (s), 904 (s) cm-1
.
[TolC(NSiMe3)2]2Sc(BH4)(THF). Tetrahydrofuran (30 mL)
was added to [TolC(NSiMe3)2]2ScCl(THF) (0.50 g, 0.71 mmol)
and NaBH4 (0.080 g, 2.1 mmol) in a 100-mL round-bottomed
flask forming a cloudy colorless solution. After the solution
was stirred overnight, the volatiles were removed under
reduced pressure. The resulting white residue was extracted
with hexanes (50 mL) and filtered through a pad of Celite on
a fritted disk. Concentration to 10 mL followed by cooling to
-40 °C gave the product as large colorless crystals (0.30 g, 62
%). Mp: 160-161 °C dec. 1H NMR (C6D6, 400 MHz): δ 7.17
(d, J ) 8.0 Hz, 4 H), 6.89 (dd, J ) 0.6, 8.3 Hz, 4 H), 4.15 (m,
4 H), 2.03 (s, 6 H), 1.44 (m, 4 H), 0.15 (s, 36 H). 13C{1H} NMR
(C6D6, 75.5 MHz): δ 182.9, 139.5, 138.1, 128.7, 126.5, 72.7,
25.4, 21.2, 2.7. IR: 2463 (w), 2388 (w), 2349 (w), 2230 (w),
1612 (w), 1433 (s, br), 1400 (s, sh), 1244 (s), 1168 (w), 1110
(w), 1008 (m, sh), (987 (s), 843 (s, br), 760 (m), 733 (m), 685
(w), 644 (w), 633 (w), 603 (w), 463 (m) cm-1. Anal. Calcd for
Rea ction of [P h C(NSiMe3)2]2ScCH2SiMe3 w ith Me3Si-
CCH . To a serum-capped NMR tube containing [PhC-
(NSiMe3)2]2ScCH2SiMe3 (9.0 mg, 14 µmol) and benzene-d6 was
added Me3SiCCH (1.9 µL, 14 µmol) forming a clear colorless

990 Organometallics, Vol. 15, No. 3, 1996
Hagadorn and Arnold
Ta ble 5. P osition a l P a r a m eter s a n d Equ iva len t Isotr op ic Disp la cem en t Coefficien ts for
{[P h C(NSiMe3)2]2ScH}2
atom
x
y
z
B(eq) (Å2)
atom
x
y
z
B(eq) (Å2)
Sc1
Sc2
Si1
Si2
Si3
Si4
Si5
Si6
Si7
Si8
N1
N2
N3
N4
N5
N6
N7
N8
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
C13
C14
C15
C16
C17
C18
0.37422(4)
0.49959(3)
0.19572(6)
0.29385(6)
0.28053(6)
0.56030(6)
0.59041(6)
0.70306(6)
0.46005(6)
0.42397(6)
0.2511(2)
0.2901(2)
0.3533(2)
0.4664(2)
0.5871(2)
0.6339(2)
0.4618(2)
0.4488(2)
0.0824(2)
0.2173(2)
0.2329(2)
0.2126(3)
0.3963(3)
0.2900(3)
0.2314(2)
0.1473(2)
0.0906(2)
0.0120(3)
-0.0092(2)
0.0475(2)
0.1245(2)
0.2956(2)
0.2805(3)
0.1780(2)
0.5481(2)
0.6042(2)
0.28771(3)
0.30103(3)
0.26197(5)
0.42208(5)
0.13845(5)
0.29786(5)
0.12918(4)
0.38820(5)
0.22305(5)
0.47327(4)
0.2976(1)
0.3636(1)
0.2014(1)
0.2693(1)
0.2153(1)
0.3220(1)
0.2881(1)
0.3901(1)
0.2559(2)
0.3096(2)
0.1744(2)
0.4884(3)
0.4637(2)
0.3740(3)
0.3453(2)
0.3769(2)
0.3572(2)
0.3857(2)
0.4332(2)
0.4524(2)
0.4243(2)
0.0671(2)
0.1042(2)
0.1771(2)
0.3423(2)
0.3569(2)
0.38524(3)
0.26834(3)
0.26952(4)
0.48146(5)
0.46017(4)
0.50139(4)
0.30279(5)
0.25655(4)
0.11160(4)
0.23102(4)
0.3344(1)
0.4197(1)
0.4483(1)
0.4671(1)
0.2863(1)
0.2686(1)
0.1673(1)
0.2148(1)
0.2775(2)
0.1963(2)
0.2603(2)
0.4766(3)
0.4788(2)
0.5577(2)
0.3757(1)
0.3724(2)
0.4160(2)
0.4108(2)
0.3650(2)
0.3234(2)
0.3267(2)
0.4054(2)
0.5425(2)
0.4440(2)
0.5782(2)
0.4443(2)
1.83(3)
1.75(3)
2.43(4)
3.04(4)
2.60(4)
2.44(4)
2.52(4)
2.58(4)
2.51(4)
2.25(4)
2.3(1)
2.4(1)
2.2(1)
2.2(1)
2.1(1)
2.2(1)
2.2(1)
2.1(1)
3.6(2)
3.4(2)
3.3(2)
6.8(3)
4.3(2)
5.1(2)
2.3(1)
2.5(1)
3.7(2)
4.8(2)
4.5(2)
3.8(2)
3.0(2)
3.4(2)
4.9(2)
3.3(2)
3.3(2)
3.1(2)
C19
C20
C21
C22
C23
C24
C25
C26
C27
C28
C29
C30
C31
C32
C33
C34
C35
C36
C37
C38
C39
C40
C41
C42
C43
C44
C45
C46
C47
C48
C49
C50
C51
C52
H(1)
H(2)
0.6392(2)
0.4240(2)
0.4569(2)
0.4938(3)
0.5287(4)
0.5261(4)
0.4883(3)
0.4531(2)
0.4876(2)
0.6674(3)
0.6128(2)
0.7218(2)
0.8059(2)
0.6553(2)
0.6508(2)
0.7371(2)
0.7837(2)
0.8615(2)
0.8929(2)
0.8489(2)
0.7706(2)
0.4146(3)
0.5680(3)
0.3977(3)
0.4375(2)
0.3161(2)
0.4919(2)
0.4435(2)
0.4210(2)
0.4825(2)
0.4608(2)
0.3802(2)
0.3186(2)
0.3395(2)
0.409(2)
0.2307(2)
0.2146(2)
0.1685(2)
0.1081(2)
0.0666(2)
0.0838(3)
0.1420(2)
0.1849(2)
0.1057(2)
0.1025(2)
0.0771(2)
0.4381(2)
0.3625(2)
0.4421(2)
0.2575(2)
0.2309(2)
0.2400(2)
0.2116(2)
0.1748(2)
0.1674(2)
0.1949(2)
0.1486(2)
0.2057(2)
0.2377(2)
0.5334(2)
0.4758(2)
0.5022(2)
0.3537(2)
0.3839(2)
0.3948(2)
0.4203(2)
0.4334(2)
0.4227(2)
0.3984(2)
0.250(1)
0.5166(2)
0.4826(1)
0.5345(2)
0.5176(2)
0.5646(3)
0.6275(3)
0.6450(2)
0.5975(2)
0.3284(2)
0.3677(2)
0.2322(2)
0.3311(2)
0.2300(2)
0.1916(2)
0.2807(1)
0.2888(2)
0.3461(2)
0.3552(2)
0.3061(2)
0.2491(2)
0.2401(2)
0.1485(2)
0.944(2)
0.0351(2)
0.1634(2)
0.2542(2)
0.3008(2)
0.1616(1)
0.0973(1)
0.0554(2)
-0.0052(2)
-0.0246(2)
0.0168(2)
0.0780(1)
0.307(1)
4.2(2)
2.3(1)
2.7(1)
4.4(2)
6.8(3)
7.0(3)
5.1(2)
3.3(2)
3.4(2)
4.2(2)
3.3(2)
3.6(2)
3.9(2)
3.3(2)
2.1(1)
2.4(1)
3.3(2)
4.4(2)
4.5(2)
4.1(2)
3.2(2)
3.7(2)
3.9(2)
4.8(2)
2.7(1)
3.3(2)
3.4(2)
2.1(1)
2.1(1)
3.0(2)
3.6(2)
3.4(2)
3.0(2)
2.6(1)
1.6(6)
3.4(8)
0.452(2)
0.340(2)
0.345(2)
solution. After 30 min, NMR spectroscopic analysis showed
complete conversion to the products. 1H NMR (C6D6, 400
MHz): δ 7.08-7.03 (m, 4H), 6.99-6.94 (m, 6H), 0.30 (s, 9H),
0.18 (s, 36H), -0.01 (s, 9H).
X-r a y Cr ysta llogr a p h y. Table 1 lists a summary of
crystallographic data for both structurally characterized com-
pounds.
14).42 The data were corrected for Lorentz and polarization
effects, but no correction for crystal decay was applied.
The 21 515 reflections measured (θ ) 0-45°) were averaged
(Rint ) 3.12%) yielding 9501 unique reflections. The structure
was solved and refined with the teXsan43 software package
using direct methods44 and expanded using Fourier tech-
niques.45 All non-hydrogen atoms were refined anisotropically.
The hydride hydrogens were located in a difference Fourier
and were refined isotropically. All remaining hydrogens were
assigned idealized positions and included in structure factor
calculations but were not refined. The final residuals for the
{[P h C(NSiMe3)2]2ScH}2. Crystals suitable for X-ray dif-
fraction studies were prepared by the blanketing of H2 onto
an hexanes solution of [PhC(NSiMe3)2]2ScCH2SiMe3 at room
temperature. Within 2 h, colorless prisms started forming at
the interface. A large crystal was cut to appropriate size and
mounted38 on a glass capillary using Paratone-N hydrocarbon
oil. The crystal was transferred to a Siemens SMART diffrac-
tometer/CCD area detector,39 centered in the beam, and cooled
to -150 °C by a nitrogen-flow low-temperature apparatus
which had been previously calibrated by a thermocouple placed
at the same position as the crystal. Preliminary orientation
matrix and cell constants were determined by collection of 60
10-s frames, followed by spot integration and least-squares
refinement. A hemisphere of data was collected using a 30-s
scan time per frame. The raw data were integrated (XY spot
spread ) 1.60°; Z spot spread ) 0.60°) using SAINT.40 Data
analysis and absorption correction were performed using
Siemens XPREP.41 The unit cell parameters and systematic
absences indicated the primitive monoclinic cell P21/n (No.
639 variables refined against the 7771 data for which F2
>
3σ(F2) were R ) 4.11%, Rw ) 6.85%, and GOF ) 2.41.46 The
quantity minimized by the least squares program was ∑w(|Fo|
- |Fc|)2, where w is the weight of a given observation. The
p-factor,46 used to reduce the weight of intense reflections, was
set to 0.03 throughout the refinement. The analytical forms
of the scattering factor tables for the neutral atoms were
used,47 and all scattering factors were corrected for both the
real and imaginary components of anomalous dispersion.48 The
(42) International Tables for Crystallography, 2nd ed.; Kluwer
Academic Publishers: Boston, MA, 1989; Vol. A.
(43) TEXSAN: Crystal Structure Analysis Package; Molecular
Structure Corp.: The Woodlands, TX, 1992.
(44) Hai-Fu, F. SAPI91: Structure Analysis Programs with Intel-
ligent Control; Rigaku Corp.: Tokyo, 1991.
(45) Beurskens, P. T.; Admiraal, G.; Beuskens, G.; Bosman, W. P.;
Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla, C.
DIRDIF92: The DIRDIF Program System; Technical Report of the
Crystallography Laboratory, University of Nijmegen: Nijmegen, The
(38) Hope, H. In ACS Symposium Series 357; Wayda, A. L.,
Darensbourg, M. Y., Eds.; American Chemical Society: Washington,
DC, 1987; p 257.
(39) SMART Area-Detector Software Package; Siemens Industrial
Automation, Inc.: Madison, WI, 1993.
(40) SAINT: SAX Area-Detector Integration Program, v. 4.024;
Siemens Industrial Automation, Inc.: Madison, WI, 1995.
(41) XPREP: Part of the SHELXTL Crystal-Structure Determination
Package; Siemens Industrial Automation: Madison, WI, 1994.
Netherlands, 1992.
(46) R ) [∑||Fo| - |Fc||]/∑|Fo|, Rw ) {[∑w(|Fo| - |Fc|)2]/∑wFo
}
1/2, and
2
GOF ) {[∑w(|Fo| - |Fc|)2]/(no - nv)}1/2, where no is the number of
observations, nv the number of variable parameters, and the weights
w were given by w ) 1/σ2(Fo), with σ(Fo2) ) [σo2(Fo2) + (pFo2)2]1/2, where
σ2(Fo) is calculated as above from σ(Fo)2 and where p is the factor used
to lower the weight of intense reflections.

Sc Complexes with Benzamidinate Ligands
Organometallics, Vol. 15, No. 3, 1996 991
positional and thermal parameters for all non-hydrogen atoms
are given in Table 5.
yielding 12 321 unique reflections. The structure was solved
and refined with the teXsan software package using direct
methods and expanded using Fourier techniques. All non-
hydrogen atoms were refined anisotropically. All hydrogen
atoms were assigned idealized positions and included in
structure factor calculations but were not refined. The final
residuals for the 829 variables refined against the 9755 data
for which F2 > 3σ(F2) were R ) 9.94%, Rw ) 9.51%, and GOF
) 7.51.46 The positional and thermal parameters of all non-
hydrogen atoms are given in Table 4.
[P h C(NSiMe3)2]2Sc(µ-Cl)2Li(TMEDA). While attempting
to undertake X-ray structural investigations of a borohydride
derivative prepared from [PhC(NSiMe3)2]2Sc(µ-Cl)2Li(TMEDA)
and LiBH4, we determined the crystal structure of the unre-
acted dichloride. The crystal was grown from hexanes at -10
°C. A crystal was selected, mounted, centered, and cooled to
-102 °C in the manner described above. Data collection,
integration, processing, and absorption correction were carried
out as described above. The unit cell was determined to be
primitive triclinic with space group P1h (No. 2). The 17 854
reflections measured (θ ) 0-45°) were averaged (Rint ) 4.42%)
Su p p or tin g In for m a tion Ava ila ble: ORTEP diagrams
and tables of positional parameters, thermal parameters, and
bond distances and angles (51 pages). Ordering information
is given on any current masthead page.
(47) Cromer, D. T.; Waber, J . T. International Tables for X-Ray
Crystallography; The Kynoch Press: Birmingham, England, 1974; Vol.
IV, Table 2.2B.
(48) Cromer, D. T.; Waber, J . T. Ibid., Table 2.3.1.
OM950750V