Selective σ-bond metathesis in alkyl - aryl and alkyl - benzyl yttrium complexes. new aryl - and benzyl - hydrido yttrium derivatives supported by amidopyridinate ligands

Article abstract of DOI:10.1021/om801044h

Yttrium dialkyl complexes coordinated by 6-aryl-substituted amidopyridinate ligands undergo selective intramolecular sp² or sp³ C - H bond activation. Upon treatment with PhSiH₃ of the resulting Y- C(alkyl, aryl) or Y - C(

Full text of DOI:10.1021/om801044h

Organometallics 2009, 28, 1227–1232
1227
Selective σ-Bond Metathesis in Alkyl-Aryl and Alkyl-Benzyl
Yttrium Complexes. New Aryl- and Benzyl-Hydrido Yttrium
Derivatives Supported by Amidopyridinate Ligands
D. M. Lyubov,† G. K. Fukin,† A. V. Cherkasov,† Andrei S. Shavyrin,† A. A. Trifonov,*,†
L. Luconi,‡ C. Bianchini,‡ A. Meli,‡ and G. Giambastiani*,‡
G. A. RazuVaeV Institute of Organometallic Chemistry of Russian Academy of Sciences, Tropinina 49,
GSP-445, 603950 Nizhny NoVgorod, Russia, and Istituto di Chimica dei Composti Organometallici
(ICCOM - CNR), Via Madonna del Piano 10, 50019, Sesto Fiorentino, Italy
ReceiVed October 30, 2008
Yttrium dialkyl complexes coordinated by 6-aryl-substituted amidopyridinate ligands undergo selective
intramolecular sp2 or sp3 C-H bond activation. Upon treatment with PhSiH3 of the resulting Y-C(alkyl,
aryl) or Y-C(alkyl,benzyl) systems, a σ-bond metathesis reaction takes place selectively at the Y-C(alkyl)
bond, generating rare dimeric aryl-hydrido or benzyl-hydrido yttrium complexes, respectively.
Rare-earth-metal hydrides currently attract a great deal of
attention due to the variety of their unique structural and
chemical properties.1 These compounds have proved to be
promising catalysts in several olefin transformations2 and have
demonstrated extremely high reactivity in stoichiometric reac-
tions, including C-F bond activation.3 Rare-earth-metal hy-
drides are generally constituted by sandwich-1 and half-
sandwich-type (“constrained geometry”)4 complexes, and very
few classes of cyclopentadienyl-free analogues have been
systematically explored up to now.5
modulated by tuning the electronic and steric properties of the
ligand framework. This issue makes the design of new
coordination environments crucial for generating a rational
balance between the kinetic stability and the high reactivity of
the resulting complexes. Recently the use of bulky amidopy-
ridinate ligands has allowed us to synthesize and characterized
a novel class of rare-earth alkyl-hydrido clusters containing
highly reactive Ln-C and Ln-H bonds, that demonstrate an
intriguing reactivity.6
In order to explore the potential of such a class of nitrogen-
containing ligands for the synthesis of new alkyl and/or hydrido
rare-earth complexes, we focused our attention on 6-aryl-
substituted aminopyridinate systems which were straightfor-
wardly prepared by reductive alkylation7 of related iminopy-
ridines (Schemes 1 and 2). The iminopyridine 1 was prepared
according to a procedure reported in the literature,8 while the
new xylyl -substituted iminopyridyl ligand 2 was synthesized
on a multigram scale through the five-step synthesis shown in
Scheme 1.
The reactivity of rare-earth-metal compounds is known to
be defined by both the metal electrophilicity and the free
coordination sites at the metal center and can be substantially
* To whom correspondence should be addressed. Fax: (+7)8314621497
(A.A.T.). E-mail: trif@iomc.ras.ru (A.A.T.); giuliano.giambastiani@
iccom.cnr.it (G.G.).
† G. A. Razuvaev Institute of Organometallic Chemistry of Russian
Academy of Sciences.
‡ Istituto di Chimica dei Composti Organometallici (ICCOM - CNR).
(1) (a) Ephritikhine, M. Chem. ReV. 1997, 97, 2193–2242. (b) Hou, Z.;
Nishiura, M.; Shima, T. Eur. J. Inorg. Chem. 2007, 2535–2545, and
references therein.
All our attempts to synthesize yttrium bis(alkyl) species via
monoalkane elimination by reacting Y(CH2SiMe3)3(THF)29 with
the aminopyridine N2HPh (3) in n-hexane at 0 °C resulted in
(2) (a) Edelmann, F. T. Top. Curr. Chem. 1996, 179, 247–262. (b)
Anwander, R. In Applied Homogeneous Catalysis with Organometallic
Compounds; Cornils, B., Hermann, W. A., Eds.; Wiley-VCH: Weinheim,
Germany, 2002; p 974. (c) Jeske, G.; Lauke, H.; Mauermann, H.; Swepston,
P. N.; Schumann, H.; Marks, T. J. J. Am. Chem. Soc. 1985, 107, 8091–
8103. (d) Jeske, G.; Schock, L. E.; Swepston, P. N.; Schumann, H.; Marks,
T. J. J. Am. Chem. Soc. 1985, 107, 8103–8110. (e) Desurmont, G.; Li, Y.;
Yasuda, H.; Maruo, T.; Kanehisa, N.; Kai, Y. Organometallics 2000, 19,
1811–1813. (f) Desurmont, G.; Tokomitsu, T.; Yasuda, H. Macromolecules
2000, 33, 7679–7681. (g) Giardello, M. A.; Conticello, V. P.; Brard, L.;
Gagne, M. R.; Marks, T. J. J. Am. Chem. Soc. 1994, 116, 10241–10254.
(h) Fu, P.-F.; Brard, L.; Marks, T. J. J. Am. Chem. Soc. 1995, 117, 7157–
7168.
(3) (a) Werkema, E. L.; Messines, E.; Perrin, L.; Maron, L.; Eisenstein,
O.; Andersen, R. A. J. Am. Chem. Soc. 2005, 127, 7781–7795. (b) Maron,
L.; Werkema, E. L.; Perrin, L.; Eisenstein, O.; Andersen, R. A. J. Am. Chem.
Soc. 2005, 127, 279–292.
(4) (a) Arndt, S.; Okuda, J. Chem. ReV. 2002, 102, 1593–1976. (b)
Okuda, J. Dalton Trans. 2003, 2367–2378.
(6) Lyubov, D. M.; Do¨ring, C.; Fukin, G. K.; Cherkasov, A. V.;
Shavyrin, A. S.; Kempe, R.; Trifonov, A. A. Organometallics 2008, 27,
2905–2907.
(7) (a) Gibson, V. C.; Redshaw, C.; White, A. J. P.; Williams, D. J. J.
Organomet. Chem. 1998, 550, 453–456. (b) Bruce, M.; Gibson, V. C.;
Redshaw, C.; Solan, G. A.; White, A. J. P.; Williams, D. J. Chem. Commun.
1998, 2523–2524. (c) Britovsek, G. J. P.; Gibson, V. C.; Mastroianni, S.;
Oakes, D. C. H.; Redshaw, C.; Solan, G. A.; White, A. J. P.; Williams,
D. J. Eur. J. Inorg. Chem. 2001, 431–437.
(8) (a) Bianchini, C.; Sommazzi, A.; Mantovani, G.; Santi, R.; Masi, F.
U.S. Patent 6,916,931 B2. (b) Bianchini, C.; Giambastiani, G.; Mantovani,
G.; Meli, A.; Mimeau, D. J. Organomet. Chem. 2004, 689, 1356. (c)
Bianchini, C.; Giambastiani, G.; Guerrero Rios, I.; Mantovani, G.; Meli,
A.; Segarra, A. M. Coord. Chem. ReV. 2006, 250, 1391–1418, and references
cited therein. (d) Bianchini, C.; Gatteschi, D.; Giambastiani, G.; Guerrero
Rios, I.; Ienco, A.; Laschi, F.; Mealli, C.; Meli, A.; Sorace, L.; Toti, A.;
Vizza, F. Organometallics 2007, 26, 726. (e) Barbaro, P.; Bianchini, C.;
Giambastiani, G.; Guerrero, I. R.; Meli, A.; Oberhauser, W.; Segarra, A. M.;
Sorace, L.; Toti, A. Organometallics 2007, 26, 4639–4651. (f) Bianchini,
C.; Giambastiani, G.; Guerrero, I. R.; Meli, A.; Oberhauser, W.; Sorace,
L.; Toti, A. Organometallics 2007, 26, 5066–5078.
(5) (a) Trifonov, A. A. Russ. Chem. ReV. 2007, 76, 1051–1072. (b)
Trifonov, A. A.; Skvortsov, G. G.; Lyubov, D. M.; Skorodumova, N. A.;
Fukin, G. K.; Baranov, E. V.; Glushakova, V. N. Chem. Eur. J. 2006, 12,
5320–5327, and references cited therein. (c) Ruspiv, C.; Spielman, J.;
Harder, S. Inorg. Chem. 2007, 46, 5320–5326. (d) Concol, M.; Spaniol,
T. P.; Okuda, J. Dalton. Trans. 2007, 4095–4102. (e) Konkol, M.; Okuda,
J. Coord. Chem. ReV. 2008, 252, 1577–1591.
(9) Lappert, M. F.; Pearce, R. J. J. Chem. Soc., Chem. Commun. 1973,
126–127.
10.1021/om801044h CCC: $40.75
2009 American Chemical Society
Publication on Web 01/21/2009

1228 Organometallics, Vol. 28, No. 4, 2009
LyuboV et al.
Scheme 1a
the methyl groups and for the methyne protons, the latter
providing two well-separated septets at 3.18 and 4.50 ppm,
respectively. Such a situation reflects the existence of two
possible conformations for 6 differing from each other in the
location of the benzylic CH2 group: above or below the
amidopyridinate ligand plane, respectively.
Although inter- and intramolecular metalations of sp2- and
sp3-hybridized C-H bonds have been previously documented
for cyclopentadienyl10 and cyclopentadienyl-free11 lanthanide
alkyl and hydride complexes, they still attract considerable
interest for their ability to activate inert chemical bonds.
Crystallization by slow cooling of a concentrated n-hexane
solution of 6 to -20 °C resulted in the formation of single
crystals suitable for X-ray diffraction analysis. The molecular
structure of the monomeric complex 6 is shown in Figure 1.
The coordination environment of the yttrium atom is set up by
two nitrogen atoms of the chelating aminopyridinate ligand, one
sp3 carbon atom from the residual alkyl group, one further sp3
carbon atom from the “benzylic” group, and one oxygen atom
from a THF molecule. Moreover, a close contact (2.9421(17)
Å) between the yttrium and the ipso carbon on the “benzylic”
group is finally observed, which increases the coordination
number to 6. The Y-CAlkyl bond length (2.4139(17) Å) is
comparable to the values reported for related yttrium systems
(2.410(8)-2.439(3) Å),12 while the Y-CBn distance (2.4520(18)
Å) is slightly longer than that measured for analogous C-H
activation products (Ap′(Ap-H′)Y(thf)] (2.420(11) Å).13 It is
worth noting that the covalent Y-N bond (2.2015(14) Å) is
evidently shorter than that measured in analogous six-
coordinated yttrium complexes containing amidopyridinate
ligands with a shorter backbone (2.273(3) Å).14
a
Legend: (i) t-BuLi, N,N-dimethylacetamide, Et2O, -78 °C; (ii)
ethylene glycol, p-toluenesulfonic acid, benzene, reflux 12 h, Dean-Stark
apparatus; (iii) Kumada coupling conditions, Me2(C6H3)MgBr,
NiCl2(PCy3)2 cat., THF, 50 °C, 72 h and then HCl 2 M, 85 °C, 2 h;
(iv) iPr2(C6H3)NH2, HCOOH cat., MeOH, reflux 62 h.
Scheme 2
the quantitative generation of the metallacyclic compound 5 as
a result of an intramolecular sp2-CH bond activation at one of
the ortho positions of the phenyl substituent (Scheme 3). The
1H and 13C{1H} NMR spectra for complex 5 were consistent
The most common synthetic route to rare-earth hydrido
complexes is the reaction of alkyl derivatives with either
dihydrogen15 or phenylsilane.16 We have found that, by treat-
1
with the expected yttrium coordination sphere. The H NMR
spectrum of 5, which contains both Y-C(alkyl) and Y-C(aryl)
bonds, shows one clear doublet centered at -0.54 ppm (2JYH
)
(10) (a) Okuda, J. Dalton Trans. 2003, 2367–2378. (b) Watson, P. L.
J. Chem. Soc., Chem. Commun. 1983, 276–277. (c) Watson, P. L.; Parshall,
G. B. Acc. Chem. Res. 1985, 18, 51–56. (d) 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, 203–219. (e) den Haan,
K. H.; Wiestra, Y.; Teuben, J. H. Organometallics 1987, 6, 2053–2060. (f)
Watson, P. L. J. Am. Chem. Soc. 1983, 105, 6491–6493. (g) Duchateau,
R.; van Wee, C. T.; Teuben, J. H. Organometallics 1996, 15, 2291–2302.
(h) Mu, Y.; Piers, W. E.; MacQuarrie, D. C.; Zaworotko, M. J.; Young,
V. G. Organometallcs 1996, 15, 2720–2726. (i) Evans, W. J.; Champagne,
T. M.; Ziller, J. W. J. Am. Chem. Soc. 2006, 128, 14270–14271. (j) Evans,
W. J.; Perotti, J. M.; Ziller, J. W. J. Am. Chem. Soc. 2005, 127, 1068–
1069. (k) Booij, M.; Kiers, N. H.; Meetsma, A.; Teuben, J. H.; Smeets,
W. J. J.; Spek, A. L. Organometallics 1989, 8, 2454–2461.
(11) (a) Duchateau, R.; Van Wee, C. T.; Meetsma, A.; Teuben, J. H.
J. Am. Chem. Soc. 1993, 115, 4931–4932. (b) Emslie, D. J. H.; Piers, W. E.;
Parvez, M.; McDonald, R. Organometallics 2002, 21, 4226–4240. (c)
Sigiyama, H.; Gambarotta, S.; Yap, G. P. A.; Wilson, D. R.; Thiele,
S. K.-H. Organometallics 2004, 23, 5054–5061. (d) Duchateau, R.;
Tuinstra, T.; Brussee, E. A. C.; Meetsma, A.; Van Duijnen, P. T.; Teuben,
J. H. Organometallics 1997, 16, 3511–3522. (e) Fryzuk, M. D.; Haddad,
T. S.; Rettig, S. J. Organometallics 1991, 10, 2026–2036. (f) Emslie,
D. J. H.; Piers, W. E.; Parvez, M. Dalton Trans. 2003, 2615–2620.
(12) (a) Wang, D.; Cui, D.; Miao, M.; Huang, B. Dalton Trans. 2007,
4576–4581. (b) Liu, X.; Shang, X.; Tang, T.; Hu, N.; Pei, F.; Cui, D.; Chen,
X.; Jing, X. Organometallics 2007, 26, 2747–2757. (c) Cai, C.-X.; Toupet,
L.; Lehmann, C. W.; Carpentier, J.-F. J. Organomet. Chem. 2003, 683,
131–136. (d) Bambirra, S.; Meetsma, A.; Hessen, B.; Teuben, J. H.
Organometallics 2001, 20, 782–785.
3.0 Hz), attributed to the hydrogen atoms of the methylene group
attached to the yttrium. The 13C{1H} NMR spectrum contains
a doublet for the sp3 carbon atom centered at 30.3 ppm (1JYC
)
39.5 Hz), while a further doublet at 190.6 ppm (1JYC ) 41.2
Hz) is readily assigned to the sp2 carbon of the phenyl ring
σ-bonded to the metal center.
Unexpectedly, the xylyl-substituted aminopyridine system
N2HXyl (4) did not allow us to generate dialkyl species due to
an intramolecular activation of the sp3-hybridized C-H bond
of one methyl group (Scheme 3). The reaction actually gave
the mononuclear metallacyclic monoalkyl complex 6, where
the yttrium atom turned out to be five-coordinated by a tridentate
aminopyridinate ligand, a residual (trimethylsilyl)methyl-
ene fragment, and a THF molecule.
Unlike the case for 5, the 1H NMR spectrum of 6 shows two
sets of diastereotopic protons, one for the methylene group of
the residual alkyl fragment attached to the yttrium atom (doublet
of doublets at -0.92 and -0.76 ppm (2JHH ) 10.8 Hz, 2JYH
)
3.0 Hz, respectively)) and one for the “benzylic” methylene
Me(C6H3)CH2Y group (doublet of doublets at 1.81 and 2.00
2
ppm (2JHH ) 5.5 Hz, JYH ) 2.0 Hz, respectively)). The
corresponding 13C{1H} NMR spectrum contains a broad doublet
centered at 27.3 ppm (1JYC ) 43.3 Hz) attributable to the
Me3SiCH2Y group, while a doublet at 49.2 ppm (1JYC ) 22.8
Hz) is assigned to the “benzylic” sp3 carbon. The two isopropyl
fragments as well as the two methyl groups at the sp3 carbon
are not magnetically equivalent and show 1H NMR and 13C{1H}
NMR spectra distinguished by a set of eight distinct signals for
(13) Skvortsov, G. G.; Fukin, G. K.; Trifonov, A. A.; Noor, A.; Do¨ring,
C.; Kempe, R. Organometallics 2007, 26, 5770–5773.
(14) Kretschmer, W. P.; Meetsma, A.; Hessen, B.; Schmalz, T.; Qayyum,
S.; Kempe, R. Chem. Eur. J. 2006, 12, 8969–8978.
(15) (a) Jeske, G.; Lauke, H.; Mauermann, H.; Swepston, P. N.;
Schumann, H.; Marks, T. J. J. Am. Chem. Soc. 1985, 107, 8091–8103. (b)
Jeske, G.; Schock, L. E.; Swepston, P. N.; Schumann, H.; Marks, T. J.
J. Am. Chem. Soc. 1985, 107, 8103–8110.

σ-Bond Metathesis in Yttrium Complexes
Organometallics, Vol. 28, No. 4, 2009 1229
Scheme 3
Scheme 4
ment with an equimolar amount of PhSiH3 in n-hexane at 0
°C, 5 and 6 undergo rapid σ-bond metathesis of the residual
Y-CH2SiMe3 bonds to give selectively the novel aryl-hydrido
and benzyl-hydrido complexes 7 and 8 (Scheme 4). Surpris-
ingly, the Y-C(Aryl) and Y-C(Bn) bonds in 5 and 6 did not
react with PhSiH3, even after 24 h at room temperature and in
the presence of a 2-fold excess of silane. In fact, complexes 7
and 8 were recovered in the same yield with no appreciable
decomposition. Complexes 5 and 6 were finally reacted with
H2 (1 bar) in toluene with the aim of exploring whether 7 and
8 were obtainable through this alternative way. All our attempts
to react 5 and 6 with H2 resulted in their decomposition with
formation of an off-white material that does not contain any
amidopyridinate ligand and is insoluble in common organic
solvents. This result proves the effectiveness of phenylsilane
as a highly selective reagent for the synthesis of hydride species
7 and 8.
The 1H and 13C{1H} NMR spectra of 7 and 8 (20 °C, C6D6)
are consistent with binuclear species distinguised by an internal
1
mirror plane. The hydride signals in 7 and 8 appear, in the H
NMR spectrum, as sharp, well-resolved triplets at 7.76 ppm
(1JYH ) 27.4 Hz) and at 7.37 ppm (1JYH ) 26.5 Hz),
respectively, thus indicating the coupling of each hydride with
two equivalent 89Y nuclei. The 13C{1H} NMR signals of the
carbon atoms bonded to yttrium appear as two doublets centered
at 193.1 ppm (1JYC ) 46.2 Hz) and 51.3 ppm (1JYC ) 24.9 Hz)
for complexes 7 and 8, respectively.
Yellow single crystals of 7, suitable for X-ray analysis, were
prepared by slow cooling of an n-hexane solution of 7 down to
-20 °C. The molecular structure of 7is illustrated in Figure 2.
The complex adopts a binuclear structure with two six-
coordinate yttrium atoms. The metal coordination sphere is
determined by the two nitrogen and one carbon atoms from the
tridentate amidopyridinate ligand, two bridging hydrido ligands,
and one oxygen atom from a residual THF molecule. The
tetranuclear Y2H2 core is not planar; the dihedral angle between
the Y(1)H(1)H(1A) and Y(1A)H(1)H(1A) planes is 20.1°. The
Y-H bond lengths are 2.15(2) Å. It should be noted that N(1),
N(2), and C(26) atoms lie in the same plane, though the entire
chelating ligand is not planar.
The Y-C bond length in 7 (2.469(2) Å) is in good agreement
with previously reported distances for similar six-coordinate
yttrium aryl species,17 while the Y-Y distance (3.5787(4) Å)
Figure 1. ORTEP diagram (30% probability thermal ellipsoids) of
complex 6 showing the numbering scheme. Hydrogen atoms are
omitted for clarity. Selected bond distances (Å) and angles (deg):
Y(1)-N(1) ) 2.2015(14), Y(1)-O(1) ) 2.3422(13), Y(1)-C(29)
) 2.4139(17), Y(1)-N(2) ) 2.4200(14), Y(1)-C(28) ) 2.4520(18),
Y(1)-C(26) ) 2.9421(17); C(29)-Y(1)-C(28) ) 117.20(6),
N(1)-Y(1)-N(2) ) 70.00(5), C(28)-Y(1)-C(26) ) 29.47(5).
(16) Voskoboinikov, 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, 4041–4055.
(17) (a) Rabe, G. W.; Zhang-Presse, M.; Riederer, F. A.; Yap, G. P. A.
Inorg. Chem. 2003, 42, 3527–3533. (b) Rabe, G. W.; Be´rube´, C. D.; Yap,
G. P. A.; Lam, K.-C.; Concolino, T. E.; Rheingold, A. L. Inorg. Chem.
2002, 41, 1446–1453. (c) Fryzuk, M. D.; Jafarpour, L.; Kerton, F. M.; Love,
J. B.; Patrick, B. O.; Rettig, S. J. Organometallics 2001, 20, 1387–1396.

1230 Organometallics, Vol. 28, No. 4, 2009
LyuboV et al.
using standard Schlenk-type techniques. THF was purified by
distillation from sodium/benzophenone ketyl, after drying over
KOH. Et2O, benzene, n-hexane, and toluene were purified by
distillation from sodium/triglyme benzophenone ketyl or were
obtained by means of a MBraun solvent purification system, while
MeOH was distilled over Mg prior to use. C6D6 was dried over
sodium/benzophenone ketyl and condensed in vacuo prior to use,
while CD2Cl2 and CDCl3 were dried over activated 4 Å molecular
sieves. Literature methods were used to synthesize the iminopyridine
ligand N2Ph (1).8 Y(CH2SiMe3)3(THF)2 was prepared according to
literature procedures.2 All the other reagents and solvents were used
1
as purchased from commercial suppliers. H and 13C{1H} NMR
spectra were obtained on either a Bruker ACP 200 (200.13 and
50.32 MHz, respectively) or a Bruker Avance DRX-400 (400.13
and 100.62 MHz, respectively). Chemical shifts are reported in ppm
(δ) relative to TMS, referenced to the chemical shifts of residual
solvent resonances (1H and 13C), and coupling constants are given
in Hz. IR spectra were recorded as Nujol mulls or KBr plates on
FSM 1201 and Bruker-Vertex 70 instruments. Lanthanide metal
analyses were carried out by complexometric titration. The C, H
elemental analyses were carried out in the microanalytical laboratory
of the IOMC or at the ICCOM by means of a a Carlo Erba Model
1106 elemental analyzer with an accepted tolerance of (0.4 unit
on carbon (C), hydrogen (H), and nitrogen (N). Melting points were
determined by using a Stuart Scientific SMP3 melting point
apparatus.
Figure 2. ORTEP diagram (30% probability thermal ellipsoids) of
complex 7 showing the numbering scheme. Hydrogen atoms, 2,6-
diisopropylphenyl fragments, and methylene groups of the THF
molecules are omitted for clarity. Selected bond distances (Å) and
angles (deg): Y-H ) 2.15(2), Y(1)-N(1) ) 2.2205(18), Y(1)-O(1)
) 2.3609(15), Y(1)-N(2) ) 2.4252(17), Y(1)-C(26) ) 2.469(2),
Y(1)-Y(1A) ) 3.5780(4); N(1)-Y(1)-N(2) ) 68.24(6), N(1)-
Y(1)-C(26) ) 130.34(7), N(2)-Y(1)-C(26) ) 68.43(7).
Synthesis of 1-(6-Bromopyridin-2-yl)ethanone.20 To a stirred
solution of 2,6-dibromopyridine (7.11 g, 30.0 mmol) in Et2O (130
mL) at -78 °C was added dropwise a 1.7 M solution of tBuLi
(18.8 mL, 30.0 mmol) in n-pentane over 10 min. After 30 min of
stirring at -78 °C, N,N-dimethylacetamide (3.1 mL, 33.0 mmol)
was added and stirring maintained for 1.5 h. The resulting mixture
was warmed to room temperature and treated with water (30 mL).
The formed layers were separated, and the organic phase was
washed with water (2 × 30 mL). The aqueous layer was extracted
with Et2O (3 × 30 mL). The combined organic layers were dried
over Na2SO4. Removal of the solvent under reduced pressure gave
a yellow oil that was dissolved in petroleum ether and cooled to
-20 °C. After 6 h, small yellow pale crystals were separated by
filtration (yield 90%). Mp: 44 °C. IR (KBr): ν 1695 cm-1 (CdO).
1H NMR (200 MHz, CDCl3, 293 K): δ 2.70 (s, 3H, C(O)Me), 7.68
(m, 2H, CH), 7.98 (dd, J ) 6.5, 2.1, 1H, CH). 13C{1H} NMR (50
MHz, CDCl3, 293 K): δ 26.4 (1C, C(O)Me), 121.1 (1C, CH), 132.4
(1C, CH), 139.8 (1C, CH), 142.0 (1C, C), 154.9 (1C, C), 198.5
(1C, C(O)Me). Anal. Calcd for C7H6BrNO (200.03): C, 42.03; H,
3.02; N, 7.00. Found: C, 42.09; H, 2.90; N, 7.02.
is significantly shorter than those measured in related binuclear
yttrium hydrides.5a,18
In conclusion, we have reported the synthesis of new yttrium
dialkyl complexes stabilized by amidopyridinate ligands which
rapidly undergo intramolecular sp2 or sp3 C-H bond activation
with the formation of alkyl-aryl or alkyl-benzyl complexes.
We have also found that the residual Y-C(alkyl) bonds undergo
selective σ-bond metathesis upon treatment with PhSiH3, while
the Y-C(aryl) and Y-C(benzyl) bonds do not react with the
silane under analogous conditions. As a result, rare19 binuclear
aryl-hydrido and benzyl-hydrido yttrium complexes have been
synthesized and characterized. Polymerization tests with both
Y-alkyl and Y-hydrido complexes using ethylene and propene
as monomer feeds are currently under investigation in our
laboratories. Preliminary results for ethylene polymerization
under standard conditions (10 bar of C2H4, 25 mL of toluene,
30 °C) indicate that both precursors do not generate very active
catalytic systems, as the highest turnover frequency observed
Synthesis of 6-Bromo-2-(2′-methyl-1′,3′-dioxolan-2′-yl)pyri-
dine.21 A solution of 1-(6-bromopyridin-2-yl)ethanone (1.0 g, 5
mmol), 1,2-ethanediol (0.34 mL, 6 mmol), and p-toluenesulfonic
acid hydrate (PTSA, 0.1 g, 0.5 mmol) in 15 mL of distilled benzene
was heated for 24 h under reflux in a Dean-Stark apparatus. The
mixture was cooled to room temperature and then treated with 5
mL of 0.5 M aqueous NaOH solution. The layers that formed were
separated. The aqueous phase was washed with Et2O (2 × 5 mL),
and the combined organic extracts were dried over NaSO4. After
removal of the solvent under reduced pressure a white solid was
was 870 mol of C2H4 converted (mol of metal)-1 h-1
.
Experimental Section
General Considerations. All air- and/or water-sensitive reactions
were performed under either nitrogen or argon in flame-dried flasks
1
obtained in pure form (yield >99%). Mp: 40-42 °C. H NMR
(18) (a) Emslie, D. J. H.; Piers, W. E.; Parvez, M.; McDonald, R.
Organometallics 2002, 21, 4226–4240. (b) Harder, S. Organometallics 2005,
24, 373–379. (c) Lyubov, D. M.; Bubnov, A. M.; Fukin, G. K.; Dolgushin,
F. M.; Antipin, M. Yu.; Pelce´, O.; Schappacher, M.; Guillaume, S. M.;
Trifonov, A. A. Eur. J. Inorg. Chem. 2008, 2090–2098.
(19) For examples of alkyl-hydrido complexes see: (a) Tardif, O.;
Nishiura, M.; Hou, Z. Organometallics 2003, 22, 1171–1173. (b) Vosk-
oboinikov, 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, 4690–4700. (c) Voskoboinikov, A. Z.; Shestakova, A. K.; Beletskaya,
I. P. Organometallics 2001, 20, 2794–2801. (d) Stern, D.; Sabat, M.; Marks,
T. J. J. Am. Chem. Soc. 1990, 112, 9558–9575. (e) Evans, W. J.; Perotti,
J. M.; Ziller, J. W. Inorg. Chem. 2005, 44, 5820–5825. (f) Evans, W. J.;
Ulibarri, T. A.; Ziller, J. W. Organometallics 1991, 10, 134–142.
(200 MHz, CDCl3, 293 K): δ 1.80 (s, 3H, Me), 3.95-4.20 (m, 4H,
CH2), 7.49 (dd, J ) 7.7, 1.3, 1H, CH Ar), 7.58-7.65 (2H, m, CH
Ar). 13C{1H} NMR (50 MHz, CDCl3, 298 K): δ 25.6 (1C, Me);
65.6 (2C, CH2); 108.5 (1C, C Ar); 118.9 (1C, CH Ar); 128.1 (1C,
CH Ar); 139.6 (1C, CH Ar); 142.5 (1C, CH Ar); 163.0 (1C, CH
Ar). Anal. Calcd for C9H10BrNO2 (244.09): C, 44.29; H, 4.13; N,
5.74. Found: C, 44.09; H, 4.22; N, 5.69.
(20) Bolm, C.; Ewald, M.; Schilingloff, G. Chem. Ber. 1992, 125, 1169.
(21) Constable, E. C.; Heirtzler, F.; Neuburger, N.; Zehnder, M. J. Am.
Chem. Soc. 1997, 119, 5606.

σ-Bond Metathesis in Yttrium Complexes
Organometallics, Vol. 28, No. 4, 2009 1231
Synthesis of 1-(6-(2,6-Dimethylphenyl)pyridin-2-yl)ethan-
one.22 To a solution of 6-bromo-2-(2′-methyl-1′,3′-dioxolan-2′-
yl)pyridine (1.5 g, 6.14 mmol) in dry and degassed THF (40 mL)
was added NiCl2(PCy3)2 (0.29 g, 0.43 mmol) in one portion. A 1
M THF solution of (2,6-Me2C6H3)MgBr (7.4 mL, 7.4 mmol) was
then added dropwise, and the resulting red solution was stirred at
50 °C for 72 h. Afterward, the mixture was cooled to room
temperature and then treated with 30 mL of a saturated aqueous
NH4Cl solution. The layers that formed were separated, the aqueous
phase was washed with Et2O (3 × 25 mL), and the combined
organic extracts were dried over NaSO4. After removal of the
solvent under reduced pressure a brown oil was obtained, and it
was used in the next step without any further purification. The oil
was then suspended in HCl 2 M (15 mL) and stirred at 80-85 °C
for 2 h. The resulting mixture was then cooled in an ice bath, diluted
with iced water (15 mL), and neutralized portionwise with solid
NaHCO3. A standard extractive workup with AcOEt (3 × 30 mL)
gave, after removal of solvent, a crude slightly brown solid which
was purified by filtration over a silica gel pad (AcOEt-petroleum
ether, 10:90) to afford the expected compound as a pale yellow oil
dried over Na2SO4. Removal of the solvent under reduced pressure
gave the amidopyridinate ligand as a crude dark white solid. The
ligand was purified by crystallization from hot MeOH, by cooling
the resulting solution to 4 °C overnight to afford white crystals in
1
93% yield (1.18 g). H NMR (400 MHz, CD2Cl2, 293 K): δ 1.10
(d, 3JHH ) 6.8 Hz, 12H, CH(CH3), H23,24,25,26), 1.53 (s, 6H, C(CH3)2,
3
H13,14), 3.38 (sept, JHH ) 6.8 Hz, 2H, CH(CH3), H21,22), 4.56 (bs,
1H, NH), 7,10 (bs, 3H, CH Ar, H17,18,19), 7.45-7.54 (m, 4H, CH
Ar, H2,8,9,10), 7.71 (d, 1H, 3JHH ) 7.5 Hz, CH Ar, H4), 7.81 (t, 1H,
3JHH ) 7.5 Hz, CH Ar, H3), 8.14-8.16 (m, 2H, CH Ar, H7,11).
13C{1H} NMR (100 MHz, C6D6, 293 K): δ 23.7 (CH(CH3)2,
C23,24,25,26), 28.2 (CH(CH3)2, C21,22), 28.9 (C(CH3)2, C13,14), 59.4
(C(CH3)2; C12), 117.7 (C2,4), 122.9 (C17,19), 124.4 (C18), 126.8 (C7,11),
128.6 (C8,10), 128.8 (C9), 137.2 (C3), 139.5 (C6), 140.5 (C16,20), 146.8
(C15), 155.4 (C5), 167.8 (C1). Mp: 107.8 °C. Anal. Calcd for
C26H32N2 (372.55): C, 83.82; H, 8.66; N, 7.52. Found: C, 83.91;
H, 8.62; N, 7.37.
Synthesis of N2HXyl (4). A solution of the iminopyridine ligand
Xyl
N2 (2; 0.85 g, 2.2 mmol) in 20 mL of toluene was cooled to 0
°C in an ice bath and treated dropwise with a 2.0 M toluene solution
of trimethylaluminum (TMA; 1.65 mL, 3.3 mmol). The reaction
mixture was stirred at room temperature for 12 h and then was
quenched with 20 mL of water. The aqueous phase was extracted
with 3 × 25 mL of AcOEt, and the combined organic layers were
dried over Na2SO4. Removal of the solvent under reduced pressure
gave the amidopyridinate ligand as a crude dark white solid. The
ligand was purified by crystallization from hot MeOH, by cooling
the resulting solution to -20 °C overnight to afford white crystals
1
(yield 76%). H NMR (200 MHz, CD2Cl2, 293 K): δ 1.98 (s, 6H,
(C6H3)(CH3)2), 2.60 (s, 3H, COCH3), 7.06-7.08 (2H, CH Ar), 7.16
(m, 1H, CH Ar), 7.36 (dd, 3JHH ) 7.8 Hz, 1H, CH Ar), 7.85 (t, 3JHH
3
) 7.8 Hz, 1H, CH Ar), 7.92 (dd, JHH ) 7.8 Hz, 1H, CH Ar).
Synthesis of [1-(6-(2,6-Dimethylphenyl)pyridin-2-yl)ethylidene]-
(2,6-diisopropyphenyl)amine (2). A solution of 1-(6-(2,6-dimeth-
ylphenyl)pyridin-2-yl)ethanone (0.94 g, 4.17 mmol), 2,6-diisopro-
pylaniline (2.4 mL, 12.5 mmol, 3 equiv) and a few drops of formic
acid in MeOH (30 mL) was refluxed for 62 h. The reaction mixture
was cooled to room temperature under stirring overnight and cooled
for several hours to +4 °C to afford a yellow solid, which was
filtered and washed several times with cold MeOH. Recrystallization
1
in 89% yield (0.79 g). H NMR (400 MHz, CD2Cl2, 293 K): δ
3
1.07 (d, 12H, JHH ) 6.8 Hz, CH(CH3), H23,24,25,26), 1.49 (s, 6H,
3
C(CH3)2, H13,14), 2.12 (s, 6H, C(CH3), H27,28), 3.23 (sept, JHH
)
6.8 Hz, 2H, CH(CH3), H21,22), 4.14 (bs, 1H, NH), 7,08 (bs, 3H,
CH Ar, H17,18,19), 7.14-7.17 (m, 4H, CH Ar, H2,8,9,10), 7.57 (dd,
1
from boiling MeOH gave a yellow solid in 69% yield. H NMR
3
(200 MHz, CD2Cl2, 293 K): δ 1.19 (d, JHH ) 6.9 Hz, 12H,
3
3
3
1H, JHH ) 7.9 Hz, JHH ) 0.9 Hz, CH Ar, H4), 7.80 (t, 1H, JHH
) 7.9 Hz, CH Ar, H3). 13C{1H} NMR (100 MHz, C6D6, 293 K): δ
20.1 (C(CH3)2, C13,14), 23.7 (CH(CH3)2, C23,24,25,26), 28.1 (CH(CH3)2,
C21,22), 29.1 (C(CH3), C27,28), 58.9 (C(CH3)2; C12), 116.9 (C2), 122.1
(C4), 122.9 (C17,19), 124.2 (C18), 127.4 (C8,10), 127.6 (C9), 135.9
(C6), 136.5 (C16,20), 140.8 (C3), 141.0 (C15), 146.3 (C7,11), 158.3
(C5), 168.5 (C1). Mp: 109.6 °C. Anal. Calcd for C28H36N2 (400.6):
C, 83.95; H, 9.06; N, 6.99. Found: C, 83.7; H, 8.97; N, 7.02.
Synthesis of N2PhY(CH2SiMe3)(THF)2 (5). A solution of N2PhH
(3; 0.182 g, 0.49 mmol) in n-hexane (15 mL) was added to a
solution of (Me3SiCH2)3Y(THF)2 (0.242 g, 0.49 mmol) in n-hexane
(10 mL) at 0 °C. The reaction mixture was stirred at 0 °C for 1 h.
The solution was concentrated under vacuum and was kept
overnight at -20 °C. Complex 5 was isolated as a yellow
microcrystalline solid in 87% yield (0.294 g). 1H NMR (400 MHz,
C6D6, 293 K): δ -0.54 (d, 2JYH ) 3.0 Hz, 2H, YCH2), 0.22 (s, 9H,
CH(CH3)2), 2.15 (s, 6H, (C6H3)(CH3)2), 2.19 (s, 3H, CNCH3), 2.82
(sept, 3JHH ) 6.9 Hz, 2H, CH(CH3)2), 6.09-7.14 (m, 1H, CH Ar),
7.16-7.22 (4H, CH Ar), 7.23-7.29 (m, 1H, CH Ar), 7.38 (dd,
3
3JHH ) 7.7 Hz, 1H, CH Ar), 7.93 (t, JHH ) 7.7 Hz, 1H, CH Ar),
3
8.32 (dd, JHH ) 7.7 Hz, 1H, CH Ar). 13C{1H} NMR (50 MHz,
CD2Cl2, 293 K): δ 17.1 (1C, CNCH3), 20.1 (2C, CH3 Ar), 22.5
(2C, CH(CH3)2), 23.0 (2C, CH(CH3)2), 28.1 (2C, CH(CH3)2), 119.0
(1C, CH Ar), 122.9 (2C, CH Ar), 123.4 (1C, CH Ar), 125.7 (1C,
CH Ar), 127.6 (2C, CH Ar), 127.8 (1C, CH Ar), 135.8 (1C, CH
Ar), 136.0 (2C, C Ar), 136.6 (2C, C Ar), 140.4 (1C, C Ar), 146.5
(1C, C Ar), 156.3 (1C, C Ar), 158.4 (1C, C Ar), 167.5 (1C, CN).
Anal. Calcd for C27H32N2 (384.56): C, 84.33; H, 8.39; N, 7.28.
Found: C, 84.19; H, 8.42; N, 7.39.
3
Si(CH3)), 1.07 (m, 8H, ꢀ-CH2 THF), 1.21 (d, JHH ) 6.8 Hz, 6H,
3
CH(CH3); H23,24,25,26), 1.31 (d, JHH ) 6.8 Hz, 6H, CH(CH3),
H23,24,25,26), 1.44 (s, 6H, C(CH3)2, H13,14), 3.55 (m, 8H, R-CH2 THF),
3
3
3.80 (sept, JHH ) 6.8 Hz, 2H, CH(CH3), H21,22), 6.76 (d, JHH
)
7.9 Hz, 1H, CH Ar, H2), 7.19 (m, together 2H, CH Ar, H3,18), 7.27
(m, together 3H, CH Ar, H10,17,19), 7.39 (t, 3JHH ) 7.3 Hz, 1H, CH
Ar, H9), 7.45 (d, JHH ) 7.5 Hz, 1H, CH Ar, H4), 7.79 (d, JHH
)
3
3
8.0 Hz, 1H, CH Ar, H11), 8.15 (d, 3JHH ) 6.8 Hz, 1H, CH Ar, H8).
13C{1H} NMR (100 MHz, C6D6, 293 K): δ 4.6 (s, Si(CH3)3), 23.8
(s, CH(CH3)2, C23,24,25,26), 24.7 (s, ꢀ-CH2, THF), 27.5 (s, CH(CH3)2,
Synthesis of N2HPh (3). A solution of the iminopyridine ligand
N2Ph (1; 1.21 g, 3.4 mmol) in 35 mL of toluene was cooled to 0 °C
in an ice bath and treated dropwise with a 2.0 M toluene solution
of trimethylaluminum (TMA; 2.54 mL, 5.1 mmol). The reaction
mixture was stirred at room temperature for 12 h and then was
quenched with 30 mL of water. The aqueous phase was extracted
with 3 × 25 mL of AcOEt, and the combined organic layers were
C3,24,25,26), 27.6 (s, CH(CH3)2, C21,22), 30.3 (d, JYC ) 39.5 Hz,
1
YCH2), 32.1 (s, C(CH3)2, C13,14), 68.5 (s, C(CH3)2; C12), 69.6 (s,
R-CH2 THF), 115.2 (s, C4), 117.7 (s, C2), 122.9 (s, C11), 123.6 (s,
C17,19), 123.7 (s, C18), 125.3 (s, C10), 127.9 (s, C9), 138.0 (s, C8),
138.6 (s, C3), 145.3 (s, C6), 147.6 (s, C15), 150.2 (s, C16,20), 164.6
(s, C5), 175.8 (s, C1), 190.6 (d, JYC ) 41.2 Hz, YC, C7). Anal.
1
(22) (a) Scott, N. M.; Schareina, T.; Tock, O.; Kempe, R. Eur. J. Inorg.
Chem. 2004, 3297–3304. (b) Labonne, A.; Kribber, T.; Hintermann, L. Org.
Lett. 2006, 8, 5853–5856.
Calcd for C38H57N2O2SiY (690.86): C, 66.06; H, 8.32; N, 4.05; Y,
12.87. Found: C, 66.38; H, 8.52; N, 4.09; Y, 12.64.

1232 Organometallics, Vol. 28, No. 4, 2009
LyuboV et al.
Synthesis of N2XylY(CH2SiMe3)(THF) (6). A solution of N2XyH
(4; 0.215 g, 0.54 mmol) in n-hexane (15 mL) was added to a
solution of (Me3SiCH2)3Y(THF)2 (0.266 g, 0.54 mmol) in n-hexane
(10 mL) at 0 °C. The reaction mixture was stirred at 0 °C for 1 h.
The solution was concentrated under vacuum and kept overnight
at -20 °C. Complex 6 was isolated as an orange crystalline solid
in 79% yield (0.274 g). 1H NMR (400 MHz, C6D6, 293 K): δ -0.92
(dd, 2JHH ) 10.8 Hz, 2JYH ) 3.0 Hz, 1H, YCH2SiMe3), -0.76 (dd,
(s, C2), 115.5 (s, C4), 122.2 (s, C18), 122.8 (s, C17,19), 123.1 (s, C11),
125.1 (s, C10), 126.9 (s, C9), 138.0 (s, C8), 138.6 (s, C3), 147.8 (s,
C6), 148.1 (s, C15), 148.9 (s, C16,20), 164.0 (s, C5), 176.0 (s, C1),
193.1 (d, JYC ) 46.2 Hz, YC). Anal. Calcd for C60H78N4O2Y2
(1065.10): C, 67.66; H, 7.38; N, 5.26; Y, 16.69. Found: C, 67.23;
H, 7.42; N, 5.15; Y, 16.43.
1
Synthesis of [N2XylY(µ-H)(THF)]2 (8). PhSiH3 (0.048 g, 0.444
mmol) was added to a solution of 6 (0.287 g, 0.444 mmol) in
n-hexane (25 mL) at 0 °C. The reaction mixture was stirred at 0
°C for 1 h and kept overnight at room temperature. The solution
was concentrated under vacuum and was kept overnight at -20
°C. Complex 8 was isolated as an orange microcrystalline solid in
2
2JHH ) 10.8 Hz, JYH ) 3.0 Hz, 1H, YCH2SiMe3), 0.23 (s, 9H,
Si(CH3)3), 0.96 (d, 3JHH ) 6.3 Hz, 3H, CH(CH3), H23,24,25,26), 1.02
(br m, ꢀ-CH2 THF), 1.15 (m, together 6H, CH(CH3)2 and C(CH3)2,
H13,14,23,24,25,26), 1.38 (d, 3JHH ) 6.8 Hz, 3H, CH(CH3)2, H23,24,25,26),
3
1.39 (d, JHH ) 6.8 Hz, 3H, CH(CH3)2, H23,24,25,26), 1.81 (dd, d,
1
63% yield (0.157 g). H NMR (400 MHz, C6D6, 293 K): δ 1.03
2
2JHH ) 5.5 Hz, JYH ) 2.0 Hz, 1H, ArCH2Y, H28), 1.89 (s, 3H,
3
3
(d, JHH ) 6.3 Hz, 6H, CH(CH3), H23,24,25,26), 1.08 (d, JHH ) 6.3
Hz, 6H, CH(CH3), H23,24,25,26), 1.13 (m, together 12H, CH(CH3)2
and C(CH3)2, H13,14,23,24,25,26), 1.27 (br m, together 14H, CH(CH3)2
and ꢀ-CH2 THF, H23,24,25,26), 1.76 (d, 2JHH ) 5.5 Hz, 2H, ArCH2Y,
2
2
ArCH3, C27), 2.00 (dd, d, JHH ) 5.5 Hz, JYH ) 2.0 Hz, 1H,
ArCH2Y, H28), 2.20 (s, 3H, C(CH3)2, C13,14), 3.00 (br m, 2H, R-CH2,
3
THF), 3.11 (br m, 2H, R-CH2 THF), 3.18 (sept, JHH ) 6.8 Hz,
1H, CH(CH3), H21,22), 4.50 (sept, JHH ) 6.3 Hz, 1H, CH(CH3),
3
H8), 1.87 (d, JHH ) 5.5 Hz, 2H, ArCH2Y, H28), 2.15 (s, 6H,
2
H21,22), 6.74 (d, 3JHH ) 8.0 Hz, 1H, CH Ar, H2), 6.80 (m, 2H, CH
Ar, H4,8), 6.98 (d, 3JHH ) 7.8 Hz, 1H, CH Ar, H10), 7.05-7.22 (m,
5H, CH, H3,9,17,18,19). 13C{1H} NMR (100 MHz, C6D6, 293 K): δ
4.7 (s, Si(CH3)3), 21.5 (s, C(CH3)2, C13,14), 24.1 (s, CH(CH3)2,
C23,24,25,26), 24.8 (s, ꢀ-CH2 THF), 24.9 (s, C(CH3)2, C13,14), 25.6 (s,
CH(CH3)2, C23,24,25,26), 26.7 (s, CH(CH3)2, C23,24,25,26), 27.2 (s,
CH(CH3)2, C23,24,25,26), 27.3 (d, 1JYC ) 41.4 Hz, YCH2Si), 27.4 (s,
CH(CH3)2, C21,22), 28.1 (s, CH(CH3)2, C21,22), 40.8 (s, ArCH3, C27),
C(CH3)2, C13,14), 2.18 (s, 6H, ArCH3, H27) 2.83 (sept, JHH ) 6.5
3
Hz, 2H, CH(CH3), H21,22), 2.92 (br m, 4H, R-CH2 THF), 3.17 (br
3
m, 4H, R-CH2 THF), 4.33 (sept, JHH ) 6.5 Hz, 2H, CH(CH3),
H21,22), 6.32 (d, JHH ) 6.5 Hz, 2H, CH Ar, H2), 6.76 (d, JHH
)
3
3
8.5 Hz, 2H, CH Ar, H4), 6.81 (m, 4H, CH Ar, H9,10), 6.88 (d, 3JHH
) 7.8 Hz, 2H, CH Ar, H8), 7.06 (m, 4H, CH Ar, H17,19), 7.15 (m,
4H, CH Ar, H3,18), 7.37 (t, JYH ) 26.5 Hz, 2 H, YH). 13C{1H}
1
NMR (100 MHz, C6D6, 293 K): δ 21.3 (s, C(CH3)2, C13,14), 24.6
(s, CH(CH3)2, C23,24,25,26), 24.5 (s, CH(CH3)2, C23,24,25,26), 25.2 (s,
C(CH3)2, C13,14), 25.4 (s, CH(CH3)2, C23,24,25,26), 25.5 (s, ꢀ-CH2
THF), 26.3 (s, CH(CH3)2, C23,24,25,26), 26.9 (s, CH(CH3)2, C21,22),
1
49.2 (d, JYC ) 23.1 Hz, YCH2, C28), 65.4 (s, C(CH3)2, C12), 69.5
(s, R-CH2 THF), 115.5 (s, Ar, C4), 119.8 (s, Ar, C2), 122.8 (s, Ar,
C10), 123.5 (s, Ar, C17,19), 123.6 (s, Ar, C17,19), 123.7 (s, Ar, C18),
124.0 (s, Ar, C8), 130.5 (s, Ar, C9), 136.5 (s, Ar, C11), 139.0 (s, Ar,
C3), 145.6 (s, Ar, C6), 149.3 (s, Ar, C15), 150.0 (s, Ar, C16,20), 150.2
(s, Ar, C16,20) 150.6 (s, Ar, C7), 158.3 (s, Ar, C5), 176.0 (s, Ar, C1).
Anal. Calcd for C36H53N2OSiY (646.30): C, 66.85; H, 8.26; N, 4.33;
Y, 13.76. Found: C, 66.63; H, 8.03; N, 4.29; Y, 13.64.
27.7 (s, CH(CH3)2, C21,22), 43.3 (s, ArCH3, C27), 51.3 (d,1JYC
)
24.9 Hz, YCH2), 63.6 (s, C(CH3)2, C12), 69.3 (s, R-CH2 THF), 113.1
(s, C4), 118.0 (s, C2), 122.0 (s, C10), 122.9 (s, C17,19), 123.0 (s, C17,19),
123.2 (s, C18), 123.7 (s, C8), 128.7 (s, C9), 134.5 (s, C3), 137.8 (s,
C11), 146.7 (s, C6) 147.8 (s, C15), 148.5 (s, C16,20), 148.7 (s, C16,20),
150.8 (s, C7), 159.0 (s, C5), 176.0 (s, C1). Anal. Calcd for
C64H86N4O2Y2 (1121.20): C, 68.56; H, 7.73; N, 5.00; Y, 15.86.
Found: C, 68.41; H, 7.33; N, 4.92; Y, 15.76.
Synthesis of [N2PhY(µ-H)(THF)]2 (7). PhSiH3 (0.035 g, 0.318
mmol) was added to a solution of 5 (0.220 g, 0.318 mmol) in
n-hexane (25 mL) at 0 °C. The reaction mixture was stirred at 0
°C for 1 h and kept overnight at room temperature. The solution
was concentrated under vacuum and was kept overnight at -20
°C. Complex 7 was isolated as a yellow microcrystalline solid in
Acknowledgment. This work has been supported by the
Russian Foundation for Basic Research (Grant Nos. 08-03-
00391-a, 06-03-32728). Thanks are also due to the European
Commission (NoE IDECAT, NMP3-CT-2005-011730) and
the Ministero dell’Istruzione, dell’Universita` e della Ricerca
of Italy (NANOPACK - FIRB project no. RBNE03R78E)
for support.
1
69% yield (0.117 g). H NMR (400 MHz, C6D6, 293 K): δ 1.03
(br s, 8H, ꢀ-CH2 THF), 1.18 (br m, 12H, CH(CH3); H23,24,25,26),
1.35 (br m, 12H, CH(CH3), H23,24,25,26), 1.55 (s, 12H, C(CH3)2,
H13,14), 3.21 (br m, together 12H, R-CH2 THF and CH(CH3), H21,22),
3
3
6.84 (d, JHH ) 7.6 Hz, 2H, CH Ar, H2), 6.95 (d, JHH ) 7.5 Hz,
2H, CH Ar, H18), 7.04 (d, 3JHH ) 7.5 Hz, 4H, CH Ar, C17,19), 7.23
(m, together 4H, CH Ar, H3,10), 7.36 (t, 3JHH ) 7.0 Hz, 2H, CH Ar,
H9), 7.47 (d, 3JHH ) 8.0 Hz, 2H, CH Ar, H4), 7.76 (t, 1JYH ) 27.7
Supporting Information Available: Tables and CIF files giving
crystallographic data for the compounds N2XylY(CH2SiMe3)(THF)
(6) and [N2PhY(µ-H)(THF)]2 (7). This material is available free of
charge via the Internet at http://pubs.acs.org.
Hz, 2H, Y(µ-H)), 7.85 (d, JHH ) 7.8 Hz, 2H, CH Ar, H11), 8.07
3
(d, JHH ) 6.5 Hz, 2H, CH Ar, H8). 13C{1H} NMR (100 MHz,
3
C6D6, 293 K): δ 24.8 (s, ꢀ-CH2 THF), 25.6 (s, CH(CH3)2, C23,24,25,26),
27.5 (s, CH(CH3)2, C23,24,25,26), 28.3 (s, CH(CH3)2, C21,22), 29.2 (s,
C(CH3)2, C13,14), 66.2 (s, C(CH3)2, C12), 70.0 (s, R-CH2 THF), 115.2
OM801044H