Synthesis, structure and catalytic activity of new iminophenolato complexes of scandium and yttrium

Article abstract of DOI:10.1016/S0022-328X(02)01657-1

The reaction of equimolar amounts of (HL¹) with M(CH₂SiMe₃)₃(THF) ₃ (M=Sc or Y) under mild conditions gives M(CH₂SiMe₃)₂(THF) (L¹). The trigonal-bipyramidal

Full text of DOI:10.1016/S0022-328X(02)01657-1

Journal of Organometallic Chemistry 663 (2002) 63ꢂ69
/
www.elsevier.com/locate/jorganchem
Synthesis, structure and catalytic activity of new iminophenolato
complexes of scandium and yttrium
Agust´ın Lara-Sanchez, Antonio Rodriguez, David L. Hughes, Mark Schormann,
Manfred Bochmann ꢀ
Wolfson Materials and Catalysis Centre, School of Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, UK
Received 9 May 2002; accepted 26 June 2002
Dedicated to Professor Pascual Royo on the occasion of his 65th birthday
Abstract
The reaction of equimolar amounts of 2-(2,4,6-Me3C6H2NÄ
Y) under mild conditions gives M(CH2SiMe3)2(THF)(L1). The trigonal-bipyramidal structure of these dialkyls was confirmed
crystallographically for MꢁSc. Whereas the scandium complex is stable in solution at room temperature, the yttrium derivative
slowly disproportionates to give Y(L1)3 which is also accessible from Y(CH2SiMe3)3(THF)3 and three HL1. The X-ray structure of
/
CH)(6-But)C6H3OH (HL1) with M(CH2SiMe3)3(THF)3 (Mꢁ
/Sc or
/
Y(L1)3 indicates a chiral tris-chelate complex. While the reaction of the related ligand (2-CyNÄ
/
CH)(6-But)C6H3OH (HL2, Cyꢁ
/
cyclohexyl) with Sc(CH2SiMe3)3(THF)3 gives the expected dialkyl Sc(CH2SiMe3)2(THF)(L2), the reaction with the yttrium analogue
affords the six-coordinate monoalkyl product Y(CH2SiMe3)(THF)(L2)2. This product is stable in solution towards disproportiona-
tion. The reaction of Y[N(SiMe3)2]3 with (2-C6F5NÄ
/
CH)(6-But)C6H3OH (HL3) affords Y{N(SiMe3)2}(L3)2 and Y(L3)3. Both
complexes are seven-coordinate in the solid state due to Yꢀ ꢀ ꢀF co-ordination to the C6F5 substituents. The scandium alkyl
complexes are efficient catalysts for the ring-opening polymerisation of o-caprolactone.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Scandium; Yttrium; Chelate complexes; Ring-opening polymerisation
1. Introduction
provide excellent catalysts for the ring-opening poly-
merisation of o-caprolactone.
Following the success of lanthanide metallocene
complexes as high-activity ethene polymerisation cata-
lysts [1ꢂ3], Group 3 metal complexes with new ligand
structures continue to attract considerable attention,
because of their catalytic potential. Recent examples
/
2. Results and discussion
The 2-iminophenol ligands HL1 and HL2 were pre-
pared by condensation of t-butylsalicylaldehyde with
2,4,6-trimethylaniline and cyclohexylamine, respec-
tively. The reactions of the lithium or sodium salts of
these ligands with MCl3(THF)3 (Mꢁ
to clean products. However, protolysis of the trialkyls
M(CH2SiMe3)3(THF)3 (MꢁSc or Y) with equimolar
amounts of HL1 in light petroleum at ꢃ
20 8C resulted
in tetramethylsilane elimination and the formation of
scandium and yttrium NÃ chelate complexes
M(CH2SiMe3)2(THF)(L1) as pale yellow (1, Mꢁ
Sc)
or light orange (2, MꢁY) crystalline solids in high
purity and essentially quantitative yields (Scheme 1).
include benzamidinato [4ꢂ/6], guanidinato [7], diketimi-
nato [8ꢂ10], aminotroponiminato [11], diamido [12],
/
bis(phenolato) [13] and iminopyrrolato complexes [14].
The combination of sterically demanding ligands and
Lewis acidic lanthanide metal centres has given rise to a
series of often highly active catalysts for the polymerisa-
tion of cyclic esters [15]. We report here the synthesis of
scandium and yttrium complexes bearing moderately
bulky 2-iminophenolato ligands. The new complexes
/
Sc, Y) did not lead
/
/
/O
/
/
ꢀ Corresponding author. Fax: ꢄ
/
44-1603-592044
E-mail address: m.bochmann@uea.ac.uk (M. Bochmann).
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 6 5 7 - 1

64
A. Lara-Sanchez et al. / Journal of Organometallic Chemistry 663 (2002) 63ꢂ69
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Table 1
˚
Selected bond lengths (A) and angles (8)
Sc(CH2SiMe3)2(THF)(L1) (1)
ScÃO(1)
ScÃC(30)
ScÃN(1)
N(1)ÃC(60)
C(1)ÃO(1)
1.993(2)
2.236(2)
2.323(2)
1.305(3)
1.318(3)
ScÃO(5)
ScÃC(40)
Si(3)ÃC(30)
N(1)ÃC(11)
C(51)ÃO(5)
2.217(2)
2.246(2)
1.844(2)
1.455(2)
1.460(3)
O(1)ÃScÃO(5)
O(5)ÃScÃC(30)
O(5)ÃScÃC(40)
O(1)ÃScÃN(1)
C(30)ÃScÃN(1)
161.55(6)
90.90(8)
93.36(8)
79.61(6)
134.92(7)
O(1)ÃScÃC(30)
O(1)ÃScÃC(40)
C(40)ÃScÃC(30)
O(5)ÃScÃN(1)
C(40)ÃScÃN(1)
95.31(8)
100.93(8)
109.17(8)
83.70(6)
115.80(7)
Y(L1)3 (3)
YÃO(1)
2.177(3)
2.157(3)
2.489(3)
1.331(4)
1.462(5)
YÃO(2)
2.177(2)
2.541(3)
2.525(3)
1.309(5)
YÃO(3)
YÃN(1)
YÃN(2)
O(1)ÃC(1)
N(1)ÃC(12)
YÃN(3)
C(11)ÃN(1)
Scheme 1.
The NMR spectra in C6D6 at room temperature indicate
Cs symmetry of the complexes. While this work was in
progress, Piers et al. reported the synthesis of sterically
O(1)ÃYÃO(3)
O(1)ÃYÃO(2)
O(2)ÃYÃN(2)
O(1)ÃYÃN(3)
N(2)ÃYÃN(3)
O(1)ÃYÃN(1)
N(2)ÃYÃN(1)
C(1)ÃO(1)ÃY
C(31)ÃN(2)ÃY
163.49(9)
90.31(9)
O(2)ÃYÃO(3)
O(1)ÃYÃN(2)
O(3)ÃYÃN(3)
O(2)ÃYÃN(3)
O(3)ÃYÃN(1)
O(2)ÃYÃN(1)
N(1)ÃYÃN(3)
C(21)ÃO(2)ÃY
C(51)ÃN(3)ÃY
96.33(9)
97.43(10)
75.02(9)
75.93(10)
101.11(9)
93.90(10)
74.23(10)
170.95(10)
142.8(2)
165.69(10)
89.69(10)
100.27(10)
91.19(10)
136.9(2)
more hindered complexes M(CH2SiMe2Ph)(NÃ
(MꢁSc, Y) bearing NÃ
C6H3Pri2 substituents which
undergo cyclometallation reactions [16].
/O)2
/
/
The crystal structure of 1 (Fig. 1) confirms a trigonal-
bipyramidal structure. Selected bond lengths and angles
are collected in Table 1. N(1), C(30) and C(40) form the
equatorial ligands, in a rather distorted arrangement,
with one wide (134.92(7)8) and one more acute
122.2(2)
122.1(2)
Y{N(SiMe3)2}(L3)2 (7)
YÃO(1)
YÃN(3)
YÃN(2)
YÃF(37)
C(11)ÃN(1)
2.141(3)
YÃO(2)
YÃN(1)
YÃF(17)
O(1)ÃC(1)
N(1)ÃC(12)
2.156(3)
2.487(3)
2.831(2)
1.324(5)
1.423(4)
2.252(3)
2.495(3)
2.858(2)
1.316(5)
(115.80(7)8) NÃ
/
ScÃ/C angle. The N(1)ScC(30)C(40)
core is planar, with an angle sum around Sc of
359.898. The axial positions are occupied by the
O(1)ÃYÃO(2)
O(2)ÃYÃN(3)
O(2)ÃYÃN(1)
O(1)ÃYÃN(2)
N(2)ÃYÃN(3)
O(1)ÃYÃF(17)
N(1)ÃYÃF(17)
YÃO(1)ÃC(1)
F(17)ÃYÃF(37)
99.95(10)
132.52(11)
93.50(11)
90.82(10)
104.80(11)
131.37(8)
60.47(9)
O(1)ÃYÃN(3)
O(1)ÃYÃN(1)
N(3)ÃYÃN(1)
O(2)ÃYÃN(2)
N(1)ÃYÃN(2)
O(2)ÃYÃF(17)
N(3)ÃYÃF(17)
YÃF(17)ÃC(17)
YÃN(3)ÃSi(2)
127.41(11)
74.78(10)
95.69(11)
74.25(10)
159.40(10)
66.93(8)
phenolate-oxygen and THF ligands (angle O(1)Ã
O(5) 161.55(6)8). The ScÃO(1) distance to the phenolate
oxygen of 1.993(2) A is much shorter than the ScÃ
distances, while the ScÃN donor bond formed by the
imino-nitrogen is significantly longer than the ScÃO(5)
interaction with the THF ligand.
/
ScÃ
/
/
˚
/C
/
77.74(9)
109.5(2)
116.4(2)
/
141.8(2)
151.83(7)
The yttrium complex 2 proved not to be stable in
solution at room temperature. After about 1 day,
Y(L3)3 (8)
YÃO(1)
YÃO(3)
YÃN(2)
YÃF(17)
C(11)ÃN(1)
O(2)ÃC(21)
2.161(2)
2.165(2)
2.541(3)
2.806(2)
1.309(4)
1.317(4)
YÃO(2)
YÃN(1)
YÃN(3)
O(1)ÃC(1)
N(1)ÃC(12)
O(3)ÃC(41)
2.153(3)
2.495(3)
2.504(3)
1.323(4)
1.418(4)
1.319(4)
O(1)ÃYÃO(2)
O(2)ÃYÃO(3)
O(2)ÃYÃN(3)
O(2)ÃYÃN(1)
O(1)ÃYÃN(2)
N(2)ÃYÃN(3)
O(1)ÃYÃF(17)
O(3)ÃYÃF(17)
N(1)ÃYÃF(17)
YÃO(1)ÃC(1)
YÃN(1)ÃC(11)
YÃN(2)ÃC(31)
94.69(9)
155.44(9)
113.86(10)
93.76(10)
156.04(10)
79.94(10)
130.84(8)
89.45(8)
O(1)ÃYÃO(3)
O(3)ÃYÃN(1)
O(1)ÃYÃN(1)
N(3)ÃYÃN(1)
O(2)ÃYÃN(2)
N(1)ÃYÃN(2)
O(2)ÃYÃF(17)
N(2)ÃYÃF(17)
N(3)ÃYÃF(17)
YÃF(17)ÃC(17)
YÃN(1)ÃC(12)
YÃN(2)ÃC(32)
108.96(9)
86.32(10)
75.00(10)
148.20(10)
73.02(9)
125.22(10)
69.50(8)
64.89(8)
142.36(8)
111.4(2)
119.2(2)
118.9(2)
60.76(9)
144.6(2)
124.8(3)
126.9(2)
Fig. 1. Molecular structure of Sc(CH2SiMe3)2(THF)(L1) (1), showing
the atomic numbering scheme. Ellipsoids are drawn at 50% prob-
ability.

A. Lara-Sanchez et al. / Journal of Organometallic Chemistry 663 (2002) 63ꢂ
/69
65
toluene solutions of 2 gave rise to a new product, the
tris(chelate) complex Y(L1)3 (3), isolated as orange
crystals. The same compound 3 was prepared by
reacting Y(CH2SiMe3)3(THF)3 with three molar equiva-
lents of HL1 in toluene at room temperature. By
contrast, the scandium analogue 1 is thermally stable
and persists in solution at room temperature for several
days.
Crystals of 3 suitable for X-ray crystallography were
grown from toluene (Fig. 2 and Table 1). The structure
shows a racemic tris-chelate complex with two nitrogen
and two oxygen atoms mutually in trans positions. The
nitrogen atoms are trigonal-planar, and the mesityl
substituents adopt a conformation approximately per-
pendicular to the YONC3 rings.
Scheme 2.
The reaction of Group 3 metal alkyls with the
cyclohexyl substituted ligand HL2 proceeds slightly
differently. The reaction of HL2 with the scandium
trialkyl at ꢃ
20 8C gives Sc(CH2SiMe3)2(THF)(L2) (4)
/
as a pale-yellow solid. By contrast, protolysis of the
yttrium trialkyl with either 1 or 2 molar equivalents of
HL2 gives the monoalkyl product, Y(CH2Si-
Me3)(THF)(L2)2 (5). In contrast to the related but
bulkier (NÃ
product 5 retains one THF ligand. The NMR spectrum
shows two identical NÃO chelates (Scheme 2). Unlike 2,
/
O)2MR complexes reported by Piers [16],
/
complex 5 is thermally stable and exists in solution
unchanged for several days even on heating to 60 8C.
The reaction of the pentafluorophenyl substituted
ligand HL3 with Y[N(SiMe3)2]3 in benzene or toluene at
Scheme 3.
Compounds 7 and 8 were characterised by X-ray
crystallography. Both complexes differ from the pre-
viously discussed examples by showing an increased
coordination number of seven. In 7, the two phenolate-
oxygen atoms are ca. trans to the amido ligand (Fig. 3).
25ꢂ60 8C gave a variety of products (Scheme 3).
/
Monitoring an equimolar mixture by 1H-NMR indi-
cated the formation of Y{N(SiMe3)2(L3) (6) alongside
Y{N(SiMe3)(L3)2 (7), in a ratio of 1:2.3. By contrast, a
repeat of this reaction on a preparative scale gave a
mixture of 7 (yellow needles) and Y(L3)3 8 (yellow
cubes). Compound 8 is also prepared in 60% yield as the
only isolable product by reacting HL3 with
Y[N(SiMe3)2]3 in a molar ratio of 2:1. The bis-amido
complex 6 could not be isolated.
As expected, the YÃ
/
N(3) bond to the amido ligand
˚
(2.252(3) A)is shorter than the donor interactions to the
˚
imino-nitrogen atoms (average 2.491(3) A). The YÃ
/O
distances and YÃ
/
OÃ
/
C angles correspond closely to the
values of complex 3. Two bonds to two of the ortho-
Fig. 2. Molecular structure of Y(L1)3 (3), showing the atomic
numbering scheme. Ellipsoids are drawn at 50% probability.
Fig. 3. Molecular structure of Y{N(SiMe3)2}(L3)2 (7), showing the
atomic numbering scheme. Ellipsoids are drawn at 50% probability.

66
A. Lara-Sanchez et al. / Journal of Organometallic Chemistry 663 (2002) 63ꢂ69
/
fluorine atoms complete the coordination geometry,
techniques. After drying over KOH, THF was distilled
from sodium benzophenone. Light petroleum (boiling
˚
average 2.845(2) A, with a rather wide FÃ
of 151.83(7)8. These Yꢀ ꢀ ꢀF interactions are significantly
longer than the YÃF distance in (C5H4SiMe3)2Y(m-
/
YÃ
/
F angle
point (b.p.) 40ꢂ60 8C) and toluene were purified by
/
/
distillation from sodium. Anhydrous yttrium trichloride
(ALFA) was used as received. ScCl3(THF)3 was pre-
pared from Sc2O3 (Aldrich) [18,19], the compounds
M(CH2SiMe3)3(THF)3 from MCl3(THF)3 according to
published procedures [20,21]. All other chemicals were
commercially available and used as received unless
otherwise stated. 1H- and 13C-NMR spectra were
recorded on a Bruker DPX300 spectrometer (1H, 300
MHz, 13C, 75.47 MHz) in C6D6 at room temperature
(r.t.). The assignment of all proton and carbon reso-
nance in the spectra was carried out by means of the
˚
Me)B(C6F5)3 (2.366(3) A) [17]. Complex 8 (Fig. 4)
shows only one Yꢀ ꢀ ꢀF bond to one of the three C6F5
substituents in the solid state, with a bond distance of
˚
2.806(2) A. In agreement with the long Yꢀ ꢀ ꢀF distances,
these yttriumꢂ
fluorine interactions are weak: the 19F-
/
NMR chemical shifts of 7 and 8 in CDCl3 or C6D6 are
essentially identical to the spectrum of the free ligand
and give no indication for persistent Yꢀ ꢀ ꢀF coordination
in solution.
appropriate 13CÃ
/
1H heteronuclear correlation (HET-
ð1Þ
COR). The microanalytical laboratory of this depart-
ment performed elemental analyses.
The scandium complex 1 is a highly effective catalyst
for the ring-opening polymerisation of o-caprolactone
(Eq. (1)). Mixtures of catalyst and monomer at 0 8C in
a ratio of 1:110 led to rapid polymerisation, with
quantitative conversion after 1 min. The polymer had
a weight-average molecular weight of 71 000 and a
polydispersity of 2.9. Longer reaction times gave mainly
oils, most probably because of back-biting and forma-
tion of cyclic oligomers once the monomer was con-
sumed. The yttrium complex 2 was also active but gave
products of moderate molecular weights. NMR analysis
of the polymers gave no indication of the nature of end
3.2. N-(3-tert-Butyl-2-hydroxy)benzylidene(2,4,6-
trimethyl)aniline (HL1)
To a solution of 3-t-butylsalicylaldehyde (1.92 ml,
11.6 mmol) in toluene (40 ml) was added 2,4,6-trimethy-
laniline (2.86 ml, 11.6 mmol) at r.t. After stirring 10 min
0.22 g (1.16 mmol) of p-toluenesulphonic acid mono-
hydrate was added as catalyst. The mixture was refluxed
for 8 h, the solution concentrated under vacuum and
extracted with 50 ml of diethyl ether. The ether solution
was dried with anhydrous MgSO4, filtered and concen-
trated under vacuum. The crude product was recrystal-
groups; for example Ã
/
CH2SiMe3 groups resulting from
a possible alkyl transfer in the initiation stage could not
be detected.
lised from light petroleum at ꢃ
/
30 8C to give yellow
crystals, yield 3.22 g (94%). 1H-NMR (300 MHz, C6D6):
d 14.24 (s, 1H, OH), 7.79 (s, 1H, CHÄ
/
N), 7.37 (dd,
7.5 Hz, 1H, CH6), 6.86 (dd,
3
1.8 Hz, JHH
4JHH
4JHH
3JHH
ꢁ
/
ꢁ
/
3. Experimental
3
1.6 Hz, JHH
ꢁ
/
ꢁ
7.7 Hz, 1H, CH4), 6.78 (t,
/
3.1. General considerations
ꢁ
7.5 Hz, 1H, CH5), 6.75 (s, 2H, CH3?), 2.15 (s,
/
3H, p-Me), 1.99 (s, 6H, o-Me), 1.61 (s, 9H, But).
All operations were performed under a nitrogen
atmosphere using standard Schlenk-line or glove box
13C{1H}-NMR (75.47 MHz, C6D6): d 168.0 (CHÄ
161.5 (COH), 146.3 (C1?), 138.2 (C1), 134.4 (C4?), 131.0
/
N),
Fig. 4. Molecular structure of Y (L3)3 (8). Left: structure showing the atomic numbering scheme. Right: coordination geometry of 8, with most
ligand atoms omitted for clarity.

A. Lara-Sanchez et al. / Journal of Organometallic Chemistry 663 (2002) 63ꢂ
/69
67
4
N), 7.52 (dd, JHH
(C4), 130.7 (C6), 129.4 (C3?), 128.6 (C2?), 119.4 (C3),
118.7 (C5), 35.4 (CMe3), 29.8 (CMe3), 21.0 (p-Me), 18.6
(o-Me). Anal. Calc. for C20H25NO: C, 81.3; H, 8.5; N,
4.7. Found: C, 81.4; H, 8.5; N, 4.5%.
3JYH
3JHH
3JHH
ꢁ
/
1.3 Hz, 1H, CHÄ
/
ꢁ
/
1.7 Hz,
4
ꢁ
/
7.5 Hz, 1H, CH6), 6.85 (dd, JHH
ꢁ
/
1.7 Hz,
7.6 Hz, 1H,
3
ꢁ
/
7.5 Hz, 1H, CH4), 6.65 (t, JHH
ꢁ
/
CH5), 6.60 (s, 2H, CH3?), 3.52 (br, 4H, THF), 2.07 (s,
3H, p-Me), 1.92 (s, 6H, o-Me), 1.77 (s, 9H, But), 1.12
2
0.25 (d, JYH
3.3. N-(3-tert-butyl-2-
hydroxy)benzylidenecyclohexylamine (HL2)
(br, 4H, THF), 0.33 (s, 18H, SiMe3), ꢃ
/
ꢁ
/
2.1 Hz, 4H, YCH2). 13C{1H}-NMR (75.47 MHz, C6D6):
2
N), 166.9 (d, JYC
d 174.5 (CHÄ
/
ꢁ2.9 Hz, COY), 148.3
/
The synthetic procedure was the same as for com-
pound HL1, using 3-t-butylsalicylaldehyde (1.92 ml,
11.6 mmol) and cyclohexylamine (1.32 ml, 11.6 mmol)
(C1?), 140.5 (C1), 135.2 (C4?), 135.0 (C6), 134.1 (C4),
129.9 (C2?), 129.6 (C3?), 123.3 (C3), 116.3 (C5), 70.5
1
(THF), 35.7 (CMe3), 34.6 (d, JYC
ꢁ40.9 Hz, YCH2),
/
1
to give HL2 as yellow crystals, yield 2.86 g (95%). H-
30.3 (CMe3), 24.9 (THF), 20.8 (p-Me), 19.2 (o-Me), 4.7
(SiMe3). Anal. Calc. for C32H54NO2Si2Y: C, 61.0; H,
8.6; N, 2.2. Found: C, 61.3; H, 8.7; N, 2.0%.
NMR (300 MHz, C6D6): d 14.64 (s, 1H, OH), 7.89 (s,
4
N), 7.35 (dd, JHH
3
1.8 Hz, JHH
1H, CHÄ
/
ꢁ
/
ꢁ7.6 Hz,
/
1H, CH6), 6.93 (dd, JHH
ꢁ
/
1.8 Hz, JHH
ꢁ7.6 Hz, 1H,
/
4
3
CH4), 6.81 (t, JHH
CH1?), 1.62 (s, 9H, But), 1.59ꢂ
CH3? or CH4?). 13C{1H}-NMR (75.47 MHz, C6D6): d
N), 161.4 (COH), 137.8 (C1), 130.0 (C4),
ꢁ
/
7.4 Hz, 1H, CH5), 2.74 (m, 1H,
3.6. Y(L1)3 (3)
3
/
1.09 (m, 10H, CH2? or
A solution of complex 2 (0.30 g, 0.47 mmol) in toluene
(40 ml) was stirring at r.t. for 24 h. The solvent was
removed in vacuum, leaving an orange solid. The crude
product was washed three times with cold petroleum (10
ml) and dried in vacuum to give 3 (0.09 g, 60% based on
163.5 (CHÄ
/
129.6 (C6), 119.5 (C3), 118.2 (C5), 67.7 (C1?), 35.4
(CMe3), 34.5, 24.5 (C2? or C3?), 29.8 (CMe3), 25.91
(C4?). Anal. Calc. for C17H25NO: C, 78.7; H, 9.7; N, 5.4.
Found: C, 78.9; H, 9.8; N, 5.3%.
HL1). 1H-NMR (300 MHz, C6D6): d 7.81 (d, 3JYH
ꢁ/1.7
4
N), 7.30 (dd, JHH
3
1.7 Hz, JHH
Hz, 3H, CHÄ
/
ꢁ
/
ꢁ/7.5
3.4. Sc(CH2SiMe3)2(THF)(L1) (1)
Hz, 3H, CH6), 6.97 (s, 3H, CH3? or CH5?), 6.80 (dd,
4JHH
3JHH
ꢁ
/
ꢁ
7.5 Hz, 3H, CH4), 6.53 (t,
/
3
1.7 Hz, JHH
To a solution of Sc(CH2SiMe3)3(THF)3 (0.35 g, 0.71
mmol) in light petroleum (30 ml) was added a solution
of HL1 (0.21 g, 0.71 mmol) in petroleum (10 ml) at
ꢁ
7.5 Hz, 3H, CH5), 6.50 (s, 3H, CH3? or CH5?),
/
2.40 (s, 9H, p-Me), 2.15 (s, 9H, o-Me), 1.95 (s, 9H, o-
Me), 0.98 (s, 27H, CMe3). 13C{1H}-NMR (75.47 MHz,
ꢃ
/
20 8C. After stirring at this temperature for 2 h the
C6D6): d 176.5 (CHÄ
/
N), 165.8 (d, 2JYC
ꢁ3.0 Hz, COY),
/
solution was decanted and concentrated in vacuum. The
reaction mixture was filtered and the solid was dried in
vacuum. The crude product was recrystallised from
toluene (15 ml) to give 1 as pale yellow crystals, yield
0.33 g (80%). 1H-NMR (300 MHz, C6D6): d 7.58 (s, 1H,
148.4 (C1?), 140.6 (C1), 136.2 (C4?), 135.2 (C6), 134.8
(C4), 130.1, 129.8 (C2? or C6?), 131.2, 128.1 (C3? or C5?),
123.1 (C3), 115.3 (C5), 36.1 (CMe3), 26.1 (CMe3), 22.7
(p-Me), 20.2 (o-Me), 18.9 (o-Me). Anal. Calc. for
C60H72N3O3Y: C, 62.6; H, 6.3; N, 3.6. Found: C, 62.7;
H, 6.4; N, 3.4%.
4
3
CHÄ
/
N), 7.52 (dd, JHH
4
ꢁ
/
1.7 Hz, JHH
3
1.7 Hz, JHH
ꢁ
/
7.5 Hz, 1H,
7.5 Hz, 1H,
CH6), 6.83 (dd, JHH
CH4), 6.66 (t, JHH
CH3?), 3.68 (br, 4H, THF), 2.08 (s, 3H, p-Me), 1.92 (s,
6H, o-Me), 1.80 (s, 9H, But), 1.18 (br, 4H, THF), 0.30
(s, 4H, ScCH2), 0.28 (s, 18H, SiMe3). 13C{1H}-NMR
ꢁ
/
ꢁ
/
3
ꢁ
/
7.2 Hz, 1H, CH5), 6.61 (s, 2H,
3.7. Sc(CH2SiMe3)2(THF)(L2) (4)
Following the synthetic procedure described for 1 and
2, HL2 (0.27 g, 1.03 mmol) and Sc(CH2SiMe3)3(THF)3
(0.46 g, 1.03 mmol) gave 4 as a pale-yellow solid, yield
0.45 g (80%). 1H-NMR (300 MHz, C6D6): d 8.19 (s, 1H,
(75.47 MHz, C6D6): d 174.6 (CHÄ
/
N), 166.8 (COSc),
149.1 (C1?), 140.0 (C1), 135.3 (C4?), 134.4 (C4), 134.3
(C6), 130.1 (C2?), 129.4 (C3?), 123.1 (C3), 116.7 (C5), 70.9
(THF), 40.1 (ScCH2), 35.7 (CMe3), 31.2 (CMe3), 25.0
(THF), 20.8 (p-Me), 19.5 (o-Me), 4.6 (SiMe3). Anal.
Calc. for C32H54NO2Si2Sc: C, 65.5; H, 9.3; N, 2.4.
Found: C, 65.8; H, 9.4; N, 2.2%.
4
3
CHÄ
/N), 7.43 (dd, JHH
ꢁ
/
1.4 Hz, JHH
ꢁ
/
7.6 Hz, 1H,
4
3
CH6), 7.09 (dd, JHH
ꢁ
/
1.4 Hz, JHH
ꢁ
/7.6 Hz, 1H,
CH4), 6.76 (t, 3JHH
3.3 Hz, 3JHH 11.6 Hz, 1H, CH1?), 4.06 (br, 4H, THF),
2.24ꢂ
0.98 (m, 10H, CH2? or CH3?or CH 4?), 1.50 (s, 9H,
But), 1.43 (br, 4H, THF), 0.21 (s, 9H, SiMe3), ꢃ
0.01
(br, 4H, ScCH2). 13C{1H}-NMR (75.47 MHz, C6D6): d
N), 164.2 (COSc), 138.3 (C1), 133.9 (C4),
ꢁ
/
7.6 Hz, 1H, CH5), 4.47 (tt, 4JHH
ꢁ
/
ꢁ
/
/
/
3.5. Y(CH2SiMe3)2(THF)(L1) (2)
167.5 (CHÄ
/
The synthetic procedure was the same as for complex
1, using HL1 (0.21 g, 0.71 mmol) and Y(CH2Si-
Me3)3(THF)3 (0.43 g, 0.71 mmol) in light petroleum
132.1 (C6), 124.4 (C3), 116.9 (C5), 71.4 (THF), 60.68
(C1?), 35.4 (CMe3), 35.3 (ScCH2), 33.7, 24.4 (C2? or C3?),
29.91 (CMe3), 26.2 (C4?), 25.3 (THF), 4.3 (SiMe3). Anal.
Calc. for C29H54NO2Si2Sc: C, 63.3; H, 9.9; N, 2.5.
Found: C, 63.7; H, 9.8; N, 2.3%.
(40 ml) at ꢃ20 8C to give 2 as a pale orange solid, yield
/
1
0.38 g, 85%. H-NMR (300 MHz, C6D6): d 7.60 (d,

68
A. Lara-Sanchez et al. / Journal of Organometallic Chemistry 663 (2002) 63ꢂ69
/
3.8. Y(CH2SiMe3)(THF)(L2)2 (5)
127.5 (C2?), 122.5 (C3?), 119.2 (C3), 117.1 (C5), 35.05
(CMe3), 29.26 (CMe3) 4.79 (SiMe3).
The synthetic procedure was similar to that described
for 4, except for the use of two equivalents of HL2. The
same compound is formed from one equivalent of HL2,
in reduced yield. The reaction of HL2 (0.30 g, 1.15
mmol) with Y(CH2SiMe3)3(THF)3 (0.35 g, 0.57 mmol)
3.10. Y{N(SiMe3)2}(L3)2 (7) and Y(L3)3 (8)
To a solution of Y[N(SiMe3)2]3 (384 mg, 0.674 mmol)
in toluene (2.5 ml) at r.t. was added a solution of HL3
(463 mg, 0.675 mmol) in toluene (2.5 ml). The reaction
mixture was stirred for 12 h at 60 8C. The resulting
1
gives 5 as an orange solid, yield 0.33 g (75%). H-NMR
(300 MHz, C6D6): d 8.01 (s, 2H, CHÄ
/
N), 7.52 (dd,
7.9 Hz, 2H, CH6), 7.06 (dd,
3
1.3 Hz, JHH
4JHH
4JHH
3JHH
ꢁ
ꢁ
/
ꢁ
/
3
1.3 Hz, JHH
/
ꢁ
/
7.9 Hz, 2H, CH4), 6.72 (t,
yellowꢂ
/
brown solution was evaporated, cold petrol was
added to the crude product, and the mixture was kept at
ꢁ
7.5 Hz, 2H, CH5), 3.8 (br, 4H, THF), 3.51 (br,
/
2H, CH1?), 1.75 (s, 18H, But), 1.76ꢂ
/
1.20 (m, 20H, CH2?
ꢃ26 8C. A bright yellow solid was obtained which
/
or CH3? or CH 4?), 1.43 (br, 4H, THF), 0.36 (s, 9H,
consisted of a mixture of crystalline Y(NR2)(L3)2 (7) and
Y(L3)3 (8). Concentrating and cooling the supernatant
2
0.52 (d, JYH
SiMe3), ꢃ
/
ꢁ
6 Hz, 2H, YCH2). 13C{1H}-
/
NMR (75.47 MHz, C6D6): d 168.7 (CHÄ
/
N), 166.1
(COY), 139.3 (C1), 134.6 (C4), 131.9 (C6), 123.7 (C3),
to ꢃ
/
60 8C provided another crop of 8 as yellow cubes.
1
Compound 8: H-NMR (CDCl3): d: 8.22 (s, 1H, CHÄ
/
115.3 (C5), 70.6 (THF), 67.1 (C1?), 35.6 (CMe3), 33.8,
ꢁ
/
ꢁ
/
7.5 Hz, 1H, CH6),
4
N), 7.40 (dd, JHH
3
1.7 Hz, JHH
1
4
3
26.1 (C2? or C3?), 30.3 (CMe3), 27.3 (d, JYC
ꢁ
/
39.1 Hz,
7.00 (dd, JHH
ꢁ
/
1.7 Hz, JHH
ꢁ
7.5 Hz, 1H, CH4), 6.63
/
YCH2), 25.7 (C4?), 25.2 (THF), 5.0 (SiMe3). Anal. Calc.
for C42H67N2O3SiY: C, 65.9; H, 8.8; N, 3.6. Found: C,
65.8; H, 8.3; N, 3.8%.
(t, 3JHH
NMR (CDCl3): d: ꢃ
162.3 (br, m-F). 13C{1H}-NMR (75.47 MHz,
N), 143.2 (C1?), 140.6 (C1),
ꢁ
/
7.2 Hz, 1H, CH5), 1.04 (s, 9H, But). 19F{1H}-
/150.8 (o-F), -159.3 (br, p-F),
ꢃ
/
CDCl3): d 178.2 (CHÄ
/
138.6 (C4?), 136.9 (C4), 135.9 (C6), 127.5 (C2?), 122.2
(C3?), 119.2 (C3), 116.1 (C5), 34.97 (CMe3), 29.68
(CMe3) Anal. Calc. for C51H39F15 N3O3Y: C, 54.85;
H, 3.52; N, 3.76. Found: C, 54.95; H, 4.17; N, 3.58%.
3.9. Reaction of 2-C6F5NÄ
/
CH(6-But)C6H3OH (HL3)
with Y[N(SiMe3)2]3 (ratio 2:1)
Y[N(SiMe3)2]3 (30 mg, 0.058 mmol) and 2-C6F5NÄ
CH(6-But)C6H3OH (HL3) (19.9 mg, 0.058 mmol) were
dissolved in 0.50 ml of benzene-d6 at 20 8C in an NMR
tube equipped with a Young teflon cap. Spectra of the
clear yellow solution recorded at intervals from 15 h to 1
week and after heating to 60 8C show the liberation of
HN(SiMe3)2]3, as well as two new sets of signals
attributed to the complexes Y{N(SiMe3)2}2(L3) (6) and
Y{N(SiMe3)2}(L3)2 (7), at a ratio of 1:2.3.
/
3.11. Synthesis of Y(L3)3 (8)
A mixture of Y[N(SiMe3)2]3 (384 mg, 0.674 mmol)
and HL3 (463 mg, 1.35 mmol) in toluene (5 ml) was
stirred for 12 h at 60 8C. The resulting solution was
evaporated and residue recrystallised from light petro-
leum to give 8 as yellow crystals (60%).
3.9.1. Compound 6
1H-NMR (C6D6): d: 8.03 (s, 1H, CHÄ
/
N), 7.33 (dd,
7.5 Hz, 1H, CH6) 6.90 (3JHH
Hz, 1H, CH4), 6.54 (t, 3JHH 9.0 Hz, 2H, CH5), 1.34 (s,
9H, But) 0.30 (s, 36H (SiMe3). 19F{1H}-NMR: d:
150.6 (o-F), ꢃ159.6 (b, p-2F), ꢃ162.7 (t, br, m-2F).
N),
3.12. X-ray crystallography
3
4JHH
ꢁ
/
1.7 Hz, JHH
ꢁ
/
ꢁ9
/
ꢁ
/
Crystals coated with dry nujol were mounted on a
glass fibre under a cold nitrogen stream. Data were
collected at 140(1) K on a Rigaku R-Axis IIc image
ꢃ
/
/
/
13C{1H}-NMR (75.47 MHz, C6D6): d: 177.6 (CHÄ
/
plate diffractometer equipped with a rotating anode X-
˚
Ka radiation, lꢁ0.71069 A) and
143.2 (C1?), 140.7 (C1), 138.6 (C4?), 135.9 (C4), 135.5
(C6), 127.8 (C2?), 122.4 (C3?), 117.8 (C3), 116.5 (C5),
35.16 (CMe3), 29.59 (CMe3), 4.49 (SiMe3).
ray source (Moꢂ
/
/
graphite monochromator. Data were processed using
the DENZO SCALEPACK [22] programs. The structure
/
was determined by direct methods in the SHELXS
program [23] and refined by full-matrix least-squares
methods, on F2?s, in SHELXL [24]. The non-hydrogen
atoms were refined with anisotropic thermal parameters.
Hydrogen atoms were included in idealised positions
and their Uiso values were set to ride on the Ueq values of
the parent carbon atoms. Scattering factors for neutral
atoms were taken from [25]. Computer programs used
were as noted above or on Table 2 [26].
3.9.2. Compound 7
1H-NMR (C6D6): d: 7.87 (s, 1H, CHÄ
/
N) 7.33 (dd,
3
4JHH
ꢁ
/
1.7 and 7.5 Hz, 1H, CH6), 6.90 (t, JHH
ꢁ9 Hz,
/
3
1H, CH4), 6.54 (t, JHH
ꢁ
9 Hz, 1H, CH5), 1.19 (s, 9H,
/
But), 0.28 (s, 18H, SiMe3). 19F{1H}-NMR: d: ꢃ
(o-F), ꢃ158.6 (br, p-F), ꢃ
161.2 (br,m-F). 13C{1H}-
NMR (75.47 MHz, C6D6): d: 176.9 (CHÄN), 143.2
(C1?), 140.8 (C1), 137.0 (C4?), 136.4 (C4), 135.9 (C6),
/
151.8
/
/
/

A. Lara-Sanchez et al. / Journal of Organometallic Chemistry 663 (2002) 63ꢂ
/69
69
Table 2
Crystallographic data of complexes 1, 3, 7 and 8
1
3
7
8
Formula
Crystal size, mm
Mr
C
32H54NO2ScSi2
C60H72N3O3Y
0.3ꢅ0.3ꢅ0.2
1015.20
C40H44F10N3O2Si2Y
0.5ꢅ0.2ꢅ0.2
933.87
C56H51F15N3O3Y
0.2ꢅ0.1ꢅ0.1
1187.91
Monoclinic
P21/n
0.4ꢅ0.3ꢅ0.3
585.9
Crystal system
Space group
Monoclinic
P21/n (no. 14)
12.404(3)
17.034(3)
16.432(3)
90
Triclinic
¯
Triclinic
¯
P/
1/(no. 2)
P/1/
˚
a (A)
10.266(2)
12.111(2)
23.973(5)
87.84(3)
77.96(3)
76.14(3)
4
11.308(2)
13.363(3)
16.698(3)
92.95(3)
106.28(3)
113.44(3)
2
13.115(3)
26.048(5)
16.320(3)
90
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
Z
90.57(3)
90
104.46(3)
90
4
4
5399(2)
3
˚
V (A )
3471.7(12)
1.121
3.1
2829.9(10)
1.191
1.076
2183.8(8)
1.420
1.470
Dcalc (g cmꢃ3
)
1.462
1.178
m(Moꢂ
/
Ka) (mmꢃ1
)
u Range (8)
2.035u 525.39
11765
6359
2.095u 525.35
14412
9052
2.085u 525.35
12458
7435
1.785u 523.50
15210
7807
Reflections measured
Independent reflections
Rint
0.025
0.1154, 0.0507
0.0816
0.1539, 0.0810
0.0762
0.1159, 0.0847
0.0687
0.0875, 0.0855
a
wR2 (all data), R1
a
wꢁ[s2(F2o)ꢄ(0.0266P)2ꢄ0.606P]ꢃ1 with Pꢁ(Fo2ꢄ2F2c)/3.
[6] S. Bambirra, M.J.R. Brandsma, E.A.C. Brussee, A. Meetsma, B.
Hessen, J.H. Teuben, Organometallics 19 (2000) 3197.
[7] G.R. Giesbrecht, G.D. Whitener, J. Arnold, J. Chem. Soc. Dalton
Trans. (2001) 923.
4. Supplementary Material
Tables with crystal and structure refinement data for
complexes 1, 3, 7 and 8. Crystallographic data for the
structural analysis have been deposited with the Cam-
bridge Crystallographic Data Centre, CCDC No.
185598 and 185599, 188005 and 188006 for compounds
1, 3 and 7 and 8, respectively. Copies of this information
may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
[8] P.B. Hitchcock, M.F. Lappert, S. Tian, J. Chem. Soc. Dalton
Trans. (1997) 1945.
[9] L.W.N. Lee, W.E. Piers, M.R.J. Elsegood, W. Clegg, M. Parvez,
Organometallics 18 (1999) 2947.
[10] P.G. Hayes, W.E. Piers, L.W.M. Lee, L.K. Knight, M. Parvez,
M.J.R. Elsegood, W. Clegg, Organometallics 20 (2001) 2533.
[11] P.W. Roesky, Eur. J. Inorg. Chem. (1998) 593.
[12] T.I. Gountchev, T.D. Tilley, Organometallics 18 (1999) 5661.
[13] C.J. Schaverien, N. Meijboom, A.G. Orpen, J. Chem. Soc. Chem.
Commun. (1992) 124.
(Fax:
ac.uk or www: http://www.ccdc.cam.ac.uk).
ꢄ44-1223-336033; e-mail: deposit@ccdc.cam.
/
[14] Y. Matsuo, K. Mashima, K. Tani, Organometallics 20 (2001)
3510.
[15] Review: S. Agarval, C. Mast, K. Dehnicke, A. Greiner, Macro-
mol. Rapid Commun. 21 (2000) 195.
Acknowledgements
[16] D.J.H. Emslie, W.E. Piers, R. MacDonald, J. Chem. Soc. Dalton
Trans. (2002) 293.
This work was supported by the European Commis-
sion, contracts no. HPRN-CT2000-00004 and HPMF-
CT-2000-00710 (M.-C. Fellowship to A.L.-S.). A.R.
thanks the University of East Anglia for a Ph.D.
studentship.
[17] X. Song, M. Thornton-Pett, M. Bochmann, Orrganometallics 17
(1998) 1004.
[18] R.W. Stotz, G.A. Melson, Inorg. Chem. 11 (1972) 1720.
[19] J.L. Atwood, K.D. Smith, J. Chem. Soc. Dalton Trans. (1974)
921.
[20] K.C. Hultzsch, P. Volh, K. Beckerle, T.P. Spaniol, J. Okuda,
Organometallics 19 (2000) 228.
[21] W.J. Ewans, J.C. Brady, J.W. Ziller, J. Am. Chem. Soc. 123
(2001) 7711.
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