Synthesis of carbodiimidotitanium complexes by the reaction of (trimethylstannyl)carbodiimides with titanium chlorides

Article abstract of DOI:10.1021/om971129t

Me₃Sn-N=C=N-R¹ (R¹ = SiⁱPr₃, SiPh₂^tBu, Ph) reacts with Cp₂TiCl₂ (Cp = η⁵-C₅H₅) or Cp*₂TiCl₂ (Cp* = η<

Full text of DOI:10.1021/om971129t

2926
Organometallics 1998, 17, 2926-2929
Syn th esis of Ca r bod iim id otita n iu m Com p lexes by th e
Rea ction of (Tr im eth ylsta n n yl)ca r bod iim id es w ith
Tita n iu m Ch lor id es
Guilaine Veneziani, Shigeru Shimada, and Masato Tanaka*
National Institute of Materials and Chemical Research, Tsukuba, Ibaraki 305-8565, J apan
Received December 29, 1997
t
Summary: Me3Sn-NdCdN-R1 (R1 ) SiiPr3, SiPh2 Bu,
Ph) reacts with Cp2TiCl2 (Cp ) η5-C5H5) or Cp*2TiCl2
(Cp* ) η5-C5Me5) selectively at the Sn-N bond to give
the corresponding bis(carbodiimido)titanium complexes
(Cp2Ti(NdCdN-SiR3)2, Cp*2Ti(NdCdN-SiR3)2, and
Cp2Ti(NdCdN-Ph)2) in moderate to high yields. The
structure of Cp2Ti(NdCdN-Ph)2 was determined by
X-ray crystallography. Oligomeric complexes were formed
by the reaction of Me3Sn-NdCdN-X-NdCdN-SnMe3
(X ) -C6H3Cl-CH2-C6H3Cl-) with Cp*2TiCl2.
Sch em e 1
the reaction of Cp2Ti(NdCdO)2 with LiN(SiMe3)2,4 but
the product yields were low (<15%). Here, we report a
general and high-yield synthesis of carbodiimidotita-
nium complexes and the X-ray crystal structure deter-
mination of Cp2Ti(NdCdN-Ph)2.
In tr od u ction
Titanium complexes having amido-type nitrogen
ligands are attracting much interest because of their
potential use as new catalysts for polymerization and
organic reactions1 and as pyrolytic precursors for tita-
nium nitride and titanium carbonitride.2 Accordingly,
a number of amidotitanium complexes have been
synthesized.1-3 Among amido-type nitrogen ligands,
carbodiimido ligands with their linear NdCdN moiety
are sterically less demanding and can retain larger
space around the metal center than the usual amido
ligands and a variety of substituents can be introduced
onto the terminal nitrogen. However, no useful method
for the preparation of carbodiimidotitanium complexes
has been reported. A paper by Plenio and Roesky
disclosed the synthesis of Cp2Ti(NdCdO)(NdCdN-
SiMe3) (Cp ) η5-C5H5) and Cp2Ti(NdCdN-SiMe3)2 by
Resu lts a n d Discu ssion
Transmetalation reactions between R3Si-NdCdN-X
and LnM-Cl (M ) B, Sb, Ta, Mo, W) have been used to
synthesize (carbodiimido)metal species LnM-NdCdN-X
with elimination of R3SiCl.5 The use of trialkylstan-
nylcarbodiimides seems more attractive because they
have higher reactivities toward transmetalation reac-
tions.6 For example, selective monosubstitution pro-
ceeds at the Sn-N bond in the reaction of R3Sn-
NdCdN-SiR′3 with (iPr2N)2PCl.7 This procedure proved
to work nicely for the synthesis of carbodiimidotitanium
complexes. Thus, (silyl)(stannyl)carbodiimides 1a ,b
reacted selectively at the Sn-N bond with R2 TiCl2 (R2
2
) Cp or Cp* () η5-C5Me5)) in THF at room temperature
to form bis[(trialkylsilyl)carbodiimido]titanium com-
plexes 2-4 nearly quantitatively (by 13C NMR spec-
troscopy). These complexes were readily purified by
recrystallization to give thin orange or red plates (2,
85%; 3, 94%; 4, 45%), Scheme 1.8 Phenyl(stannyl)car-
bodiimide 1c reacted similarly with Cp2TiCl2 to give 5
nearly quantitatively. The color of the resulting THF
solution of 5 was very strongly purple-violet, but 5
crystallized to form shiny metallic thin green plates.
Complexes 2-4 are air- and light-stable in the
crystalline state, while in solution they gradually de-
(1) (a) Patten, T. E.; Novak, B. M. J . Am. Chem. Soc. 1996, 118,
1906. (b) Scollard, J .; McConville, D. H. J . Am. Chem. Soc. 1996, 118,
10008. (c) Scollard, J .; McConville, D. H.; Payne, N. C.; Vittal, J . J .
Macromolecules 1996, 29, 5241. (d) Fuhrmann, H.; Brenner, S.; Arndt,
P.; Kempe, R. Inorg. Chem. 1996, 35, 6742.
(2) For recent examples, see: (a) Seyferth, D.; Mignani, G. J . Mater.
Sci. Lett. 1988, 7, 487. (b) Brown, G. M. Inorg. Chem. 1989, 28, 3028.
(c) Gross, M. E.; Siegrist, T. Inorg. Chem. 1992, 31, 4898. (d) Laurent,
F.; Zhao, J . S.; Valade, L.; Choukroun, R.; Cassoux, P. J . Anal. Appl.
Pyrolysis 1992, 24, 39. (e) Laurent, F.; Cyr-Athis, O.; Legros, J . P.;
Choukroun, R.; Valade, L. New J . Chem. 1994, 18, 575. (f) Narula, C.
K.; Demczyk, B. G.; Czubarow, P.; Seyferth, D. J . Am. Ceram. Soc.
1995, 78, 1247. (g) Weiller, B. H. J . Am. Chem. Soc. 1996, 118, 4975.
(3) For recent examples, see: (a) Visciglio, V. M.; Fanwick, P. E.;
Rothwell, I. P. Acta Crystallogr. 1994, C50, 896. (b) Irigoyen, A. M.;
Mart´ın, A.; Mena, M.; Palacios, F.; Ye´lamos, C. J . Organomet. Chem.
1995, 494, 255. (c) Bowen, D. E.; J ordan, R. F. Organometallics 1995,
14, 3630. (d) Warren, T. H.; Schrock, R. R.; Davis, W. M. Organome-
tallics 1996, 15, 562. (e) Minhas, R. K.; Scoles, L.; Wong, S.; Gam-
barotta, S. Organometallics 1996, 15, 1113. (f) J ohnson, A. R.; Davis,
W. M.; Cummins, C. C. Organometallics 1996, 15, 3825. (g) Friedrich,
S.; Memmler, H.; Gade, L. H.; Li, W.-S.; Scowen, I. J .; McPartlin, M.;
Housecroft, C. E. Inorg. Chem. 1996, 35, 2433. (h) Kempe, R.; Arndt,
P. Inorg. Chem. 1996, 35, 2644. (i) Gue´rin, F.; McConville, D. H.; Payne,
N. C. Organometallics 1996, 15, 5085. (j) Tsuie, B.; Swenson, D. C.;
J ordan, R. F. Organometallics 1997, 16, 1392. (k) Gue´rin, F.; McCo-
nville, D. H.; Vittal, J . J . Organometallics 1997, 16, 1491. (l) Guzei, I.
A.; Baboul, A. G.; Yap, G. P. A.; Rheingold, A. L.; Schlegel H. B.; Winter,
C. H. J . Am. Chem. Soc. 1997, 119, 3387.
(4) Plenio, H.; Roesky, H. W. Z. Naturforsch. 1989, 44b, 94.
(5) (a) Rajca, G.; Schwarz, W.; Weidlein, J . Z. Naturforsch. 1984,
39b, 1219. (b) Rajca, G.; Weidlein, J . Z. Anorg. Allg. Chem. 1986, 538,
36. (c) Einholz, W.; Haubold, W. Z. Naturforsch. 1986, 41b, 1367.
(6) Re´au, R.; Bertrand, G. Rev. Heteroat. Chem. 1996, 14, 137.
(7) Veneziani, G.; Re´au, R.; Bertrand, G. Organometallics 1993, 12,
4289.
(8) The lower isolated yield of 4 was due to its high solubility in the
recrystallization solvents. Most of the products described in this paper
were reluctant to burn in combustion analysis. Use of a larger quantity
of combustion promoter (V2O5) proved to improve elemental analyses
but was not sufficiently helpful to obtain satisfactory data.
S0276-7333(97)01129-1 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 06/05/1998

Notes
Organometallics, Vol. 17, No. 13, 1998 2927
Sch em e 2
orange powder. The IR spectrum of the latter showed
several new bands assignable to CdO stretching vibra-
tions, formed at the expense of the NdCdN bands. This
suggests the formation of urea-type products, as in the
case of the usual organic carbodiimides. Such hydrolytic
degradation has never been observed for complexes 2-4.
The molecular structure of complex 5 was determined
by X-ray diffraction, and the ORTEP drawing10 is shown
in Figure 1. Crystallographic data and selected bond
lengths and angles for 5 are given in Tables 1 and 2,
respectively. The structure of M-NdCdN-M′ is known
to be highly dependent on the nature of M and M′. For
example, even in the case of symmetric R3Si-NdCdN-
SiR3, the Si-N-C angle can vary between 180° (R )
Ph) and 142.0(11)° (R ) Me).11 Complex 5 has asym-
metric NdCdN linkages; the N1-C1 and N3-C2 bond
lengths are 1.187(7) and 1.177(6) Å, respectively, which
are close to the N-C triple bond length. On the other
hand, the N2-C1 and N4-C2 bond lengths are 1.260-
(7) and 1.247(7) Å, respectively, suggesting a double-
bond character of these bonds. The bond angles dis-
tinctly reflect the difference in these N-C bond lengths;
Ti-N1-C1 (168.1(4)°) and Ti-N3-C2 (174.5(4)°) are
almost linear, while C1-N2-C3 (123.3(5)°) and C2-
N4-C4 (125.4(5)°) are those of usual trigonal nitrogens.
The present method should be applicable to the
synthesis of polymeric complexes. The reaction of Me3-
Sn-NdCdN-SnMe3 with Cp*2TiCl2, Cp*2TiCl2, and
TiCl4 gave red or reddish-brown materials. However,
high air and/or light sensitivity and insolubility pre-
vented characterization of the products. To ensure the
characterization of possible polymeric complexes by
improving the air- and light-stability and solubility, bis-
(stannylcarbodiimido) compound 6, having an organic
spacer, was synthesized by the procedure of Ha¨nssgen
and Hajduga.12 The reaction of 6 with Cp*2TiCl2 gave
a deep violet solid 7, which indeed was more stable to
air and light than the products derived from Me3Sn-
NdCdN-SnMe3, Scheme 2. Product 7 was soluble in
CHCl3 and THF. Its IR spectrum showed a typical
F igu r e 1. A view of the molecular structure of 5.
Ta ble 1. Cr ysta llogr a p h ic Da ta for 5
formula
fw
C24H20N4Ti
412.35
cryst size, mm
a, Å
b, Å
0.40 × 0.20 × 0.03
11.674(2)
21.154(2)
9.226(2)
112.82(1)
2100.0(1)
monoclinic
P21/c (No. 14)
4
1.304
35.75
1.541 78
120.1
3454
c, Å
â, deg
V, Å3
cryst syst
space group
Z
D
calc, g cm-3
µ (Cu KR), cm-1
λ, Å
2θmax, deg
no. of rflns measd
no. of unique rflns
no. of rflns Io > 3.0σ(Io)
R, Rw
3234
1876
0.047, 0.062
1.53
GoF
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 5
Ti-N1
Ti-N3
N1-C1
N2-C1
2.002(4)
1.985(5)
1.187(7)
1.260(7)
N2-C3
N3-C2
N4-C2
N4-C4
1.404(6)
1.177(6)
1.247(7)
1.399(6)
N1-Ti1-N3
Ti1-N1-C1
Ti1-N3-C2
C1-N2-C3
95.4(2)
168.1(4)
174.5(4)
123.3(5)
C2-N4-C4
N1-C1-N2
N3-C2-N4
125.4(5)
173.8(6)
171.3(5)
compose under sunlight, even under a nitrogen atmo-
sphere to give insoluble materials. In the decomposition
of 2 and 4, the major soluble product was iPr3Si-
NdCdN-SiiPr3, as characterized by comparison of its
spectral data with those of an authentic sample. On
the other hand, the insoluble products did not show
NdCdN nor CdO absorptions in the IR spectra. In a
patent it was reported that a polymer containing
-SiPh2-NdCdN- repeat units underwent cross-link-
ing upon exposure to an electron beam.9 In our photo-
degradation process, not only the metathesis reaction
leading to the formation of iPr3Si-NdCdN-SiiPr3 but
also a cross-linking process may have been involved.
However, further characterization of the insoluble prod-
ucts was not undertaken. On the other hand, complex
5 is air stable in the solid state and insensitive to the
light. When a THF solution of 5 was exposed to air,
slow decomposition occurred to precipitate a light
NdCdN absorption band at 2130 cm-1
. GPC (gel
permeation chromatography; THF, polystyrene stan-
dards) analysis of the crude mixture revealed that the
molecular weight of the product ranged from 300 to
3000, indicative of the formation of low molecular weight
(10) J ohnson, C. K. Ortep, a FORTRAN Thermal-Ellipsoid Plot
Program for Crystal Structure Illustrations; Report ORNL-3794; Oak
Ridge National Laboratory: Oak Ridge, TN, 1970.
(11) Sheldrick, G. M.; Taylor, R. J . Organomet. Chem. 1975, 101,
19. Hammel, A.; Volden, H. V.; Haaland, A.; Weidlein, J .; Reischmann,
R. J . Organomet. Chem. 1991, 408, 35. Obermeyer, A.; Kienzle, A.;
Weidlein, J .; Riedel, R.; Simon, A. Z. Anorg. Allg. Chem. 1994, 620,
1357.
(9) Klebe, J . F.; Murray, J . G. U.S. Patent 3352799 (to General
Electric Co.), 1967; Chem. Abstr. 1968, 68, 14164x.
(12) Ha¨nssgen, D.; Hajduga, D. Chem. Ber. 1977, 110, 3961.

2928 Organometallics, Vol. 17, No. 13, 1998
Notes
Exp er im en ta l Section
Gen er a l P r oced u r es. All manipulations of air-sensitive
materials were carried out under a nitrogen atmosphere using
standard Schlenk tube techniques. Me3Sn-NdCdN-SnMe3,15
Me3Sn-NdCdN-SiiPr3,7 and Me3Sn-NdCdN-Ph12 were
prepared according to the literature procedures. 1H, 13C, and
29Si NMR spectra were recorded on Bruker AC200 and
ARX300 spectrometers.
P r ep a r a tion of Me3Sn -NdCdN-SiP h 2tBu (1b). To a
THF solution (10 mL) of Me3SnNCNSnMe3 (0.55 g, 1.5 mmol)
t
was added dropwise BuPh2SiCl (0.41 g, 1.5 mmol) at room
temperature. After 2 h, the solvent and Me3SnCl were
removed under vacuum to give 1b as a colorless oil, which was
used in the following reaction without further purification. 1H
119
117
NMR (CDCl3): δ 0.47 (s, 9H, J H
) 58.7 Hz, J H
) 56.6
Sn
Sn
t
Hz, SnCH3), 1.06 (s, 9H, Bu), 7.33-7.39 (m, 6H), 7.72-7.76
(m, 4H). 13C NMR (CDCl3): δ - 4.14 (J C
) 401 Hz, J C
119
117
Sn
Sn
) 381 Hz, SnMe3), 19.55 (CMe3), 26.27 (CMe3), 127.10, 128.84,
130.41 (NCN), 134.51, 134.76 (ipso). 29Si NMR (CDCl3): δ -
15.96. IR (neat, cm-1): 2148 (NCN). HRMS calcd for C16H19N2-
t
SiSn (M+ - Bu): 386.0328. Found: 386.0323.
Gen er a l P r oced u r e for th e Syn th esis of Com p ou n d s
2-4. To a THF solution (8 mL) of R22TiCl2 (0.3 mmol) was
added dropwise a THF solution (8 mL) of R1-NdCdN-SnMe3
(0.6 mmol) at room temperature. After the mixture was stirred
overnight, the solvent and Me3SnCl were removed under
vacuum (3 h, 10-2 mmHg) to give 2-4, which were recrystal-
lized from pentane (2, 85%), hexane (3, 94%), or a THF/aceto-
nitrile mixture (3/7, 4, 45%).
F igu r e 2. GPC profiles of (a) a crude mixture of 7 and (b)
an isolated needle of 7.
Cp 2Ti(NdCdN-SiiP r 3)2 (2). Orange thin plates (85%
oligomers (Figure 2a; the formula weight of the repeat
unit of 7 is 633). The 1H NMR spectrum of crude 7
displayed signals arising from C5(CH3)5 and aromatic
hydrogens as well as a small amount of Sn(CH3)3, which
was assignable to the unreacted -NCN-SnMe3 termi-
nus. A small amount of purer 7 could be isolated by
recrystallization as fine needles13 and showed the same
retention time in the GPC analysis (Figure 2a; Mw
(polystyrene standard) ) 631, Mw/Mn ) 1.08) as that of
the major fraction of the crude material. Although
the Mw estimated by GPC corresponds to the formula
weight of one repeat unit, the absolute value is mean-
ingless since the polystyrene standards are used. In-
deed, the FAB mass spectrum of the needle showed a
signal at m/z 1267 (with the expected isotope pat-
tern), which corresponds to the molecular ion peak of a
cyclic dimer (-Cp*2Ti-NdCdN-C6H3Cl-CH2-C6H3Cl-
NdCdN-)2. This result suggests that GPC analysis
using the standards underestimates the molecular
weight of 7. Similar underestimations are reported for
dendrimers and organometallic oligomers and poly-
mers.14 The 1H and 13C NMR spectra of the needle
verified the presence of Cp* and C6H3Cl-CH2-C6H3Cl
groups and the absence of Me3Sn. These spectra also
are consistent with the cyclic structure.
i
yield), mp 112 °C. 1H NMR (CDCl3): δ 1.07 (m, 42H, Pr),
6.24 (s, 10H, C5H5). 13C NMR (CDCl3): δ 12.89 (CHMe2), 18.19
(CHMe2), 115.68 (C5H5), NCN was not observed. 29Si NMR
(CDCl3): δ 2.39. IR (KBr, cm-1): 2146, 2112 (NCN). MS (EI,
i
relative intensity): m/z 572 (M+, 8), 529 (M+ - Pr, 100), 507
(M+ - C5H5, 100), 486 (56). HRMS Calcd for C30H52N4Si2Ti:
572.3210. Found: 572.3176. Anal. Calcd for C30H52N4Si2Ti:
C, 62.90; H, 9.15; N, 9.18. Found: C, 62.34; H, 9.19; N, 9.14.
Cp 2Ti(NdCdN-SiP h 2tBu )2 (3). Orange-red thin plates
(94% yield), mp 105 °C. 1H NMR (CDCl3): δ 1.09 (s, 18H,
CMe3), 6.14 (s, 10H, C5H5), 7.38-7.78 (m, 20H, Ph). 13C NMR
(CDCl3): δ 19.84 (CMe3), 26.77 (CMe3), 116.12 (C5H5), 127.60,
129.27, 135.19, 135.88 (ipso), 138,63 (NCN). 29Si NMR
(CDCl3): δ-15.53. IR (KBr, cm-1): 2156, 2094 (NCN). MS
(EI, relative intensity): m/z 679 (M+ - tBu, 63), 223 (100), 178
(42). Anal. Calcd for C44H48N4Si2Ti: C, 71.71; H, 6.57; N, 7.60.
Found: C, 72.04; H, 6.67; N, 7.60.
Cp *2Ti(NdCdN-SiiP r 3)2 (4). Red plates (45% yield), mp
i
182 °C. 1H NMR (CDCl3): δ 1.04 (m, 42H, Pr), 1.95 (s, 30H,
C5Me5). 13C NMR (CDCl3): δ 11.99, 13.06, 18.32, 124.74 (C5-
Me5), NCN was not observed. 29Si NMR (CDCl3): δ -1.66. IR
(KBr, cm-1): 2166, 2102 (NCN). MS (EI, relative intensity):
m/z 712 (M+, 0.4), 669 (M+ - iPr, 0.59), 578 (M+ - C5Me5, 100).
HRMS Calcd for C40H72N4Si2Ti: 712.4775. Found: 712.4786.
Cp 2Ti(NdCdN-P h )2 (5). To a THF solution (3 mL) of Cp2-
TiCl2 (0.075 g; 0.3 mmol) was added dropwise a THF solution
(3 mL) of PhNCNSnMe3 (0.168 g; 0.6 mmol) at room temper-
ature. After the mixture was stirred overnight, the solution
was poured into pentane (20 mL). Filtration followed by
drying in vacuo gave metallic green crystals 5 (95% yield),
mp: 123 °C. 1H NMR (CDCl3): δ 6.41 (s, 10H, C5H5), 6.98-
7.24 (m, 10H, Ph). 13C NMR (CDCl3): δ 116.33 (C5H5), 122.01,
122.26, 129.37, 143.72 (NCN), 145.53 (ipso). IR (KBr, cm-1):
2132, 2092 (NCN). MS (EI, relative intensity): m/z 412 (M+,
21), 295 (M+ - PhNCN, 100), 178 (Cp2Ti, 87). HRMS Calcd
for C24H20N4Ti: 412.1167. Found: 412.1185. Anal. Calcd for
(13) We tried the reaction of 6 with Cp*2TiCl2 several times. In all
cases, GPC profiles of the resulting mixtures of oligomers were almost
the same. However, we succeeded only once to obtain a small amount
of a purer compound as needles by cooling a saturated THF solution
of a mixture of oligomers. FAB mass analyses of the crude products
also always showed the signal corresponding to the cyclic dimer (-Cp*2-
Ti-NdCdN-C6H3Cl-CH2-C6H3Cl-NdCdN-)2 at m/z 1267, 1131,
and 633.
(14) For recent examples, see: Hawker, C. J .; Frechet, J . M. J .;
Wooley, K. L. Pure Appl. Chem. 1994, A31, 1627. Foucher, D.;
Ziembinski, R.; Petersen, R.; Pudelski, J .; Edwards, M.; Ni, Y.; Massey,
J .; J aeger, C. R.; Vancso, G. J .; Manners, I. Macromolecules 1994, 27,
3992. Achar, S.; Vittal, J . J .; Puddephatt, R. J . Organometallics 1996,
15, 43. Liano, Y.-H.; Moss, J . R. Organometallics 1996, 15, 4307.
C
24H20N4Ti: C, 69.91; H, 4.89; N, 13.59. Found: C, 69.29; H,
4.90; N, 13.29.
(15) Forder, R. A.; Sheldrick, G. M. J . Chem. Soc. A 1971, 1107.

Notes
P r ep a r a tion of 6. To a hexane solution (8 mL) of (Me3-
Organometallics, Vol. 17, No. 13, 1998 2929
reflections were measured after every 150 reflections. Over
the course of data collection, the standards decreased by 28.7%.
A linear correction factor was applied to the data to account
for this phenomenon. The linear absorption coefficient, µ, for
Sn)3N (0.505 g; 1.0 mmol) stirred at room temperature was
added dropwise an EtOH solution (3 mL) of 1,1′-methylenebis-
(3-chloro-4-isothiocyanatobenzene) (0.175 g; 0.50 mmol). After
the mixture was stirred overnight, the solvent and (Me3Sn)2S
were removed by a syringe. The residue was then dissolved
in THF (5 mL) and poured into pentane (20 mL) under
vigorous stirring. The solvent was again removed by a syringe,
and the remaining product was dried under vacuum, affording
a pale yellow solid (89% yield), which was used in subsequent
reactions without further purification. 1H NMR (CDCl3): δ
Cu KR radiation was 35.8 cm-1
. An empirical absorption
correction based on azimuthal scans of several reflections was
applied, resulting in transmission factors ranging from 0.69
to 1.00. The data were corrected for Lorentz and polarization
effects. The structure was solved by direct methods16 and
expanded using Fourier techniques.17 The non-hydrogen
atoms were refined anisotropically. Hydrogen atoms were
included but not refined. The final cycle of full-matrix least-
squares refinement was based on 1876 observed reflections (I
> 3.00σ(I)) and 262 variable parameters and converged (largest
parameter was 1.31 times its esd) with unweighted and
weighted agreement factors of R ) ∑||Fo| - |Fc||/∑|Fo| ) 0.047,
119
117
0.55 (s, 18H, J H
) 58.4 Hz, J H
) 53.5 Hz, SnMe3), 3.76
Sn
Sn
(s, 2H, CH2), 6.91-7.05 (m, 6H). 13C NMR (CDCl3): δ - 1.98
119
117
(J C Sn ) 402 Hz, J C Sn ) 384 Hz, SnMe3), 40.85 (CH2), 124.59,
127.79, 128.81, 130.95, 133.14 (NCN), 136.36, 140.02. IR
(neat, cm-1): 2128 (NCN). HRMS Calcd for C20H23N4119Sn2
-
35
Cl2 (M+ - Me): 628.9342. Found: 628.9360.
Rw ) [Σw(|Fo| - |Fc|)2/ΣwFo
]
) 0.062. The maximum and
2
1/2
Syn th esis of 7. To a THF solution (5 mL) of Cp*2TiCl2
(0.233 g, 0.60 mmol) stirred at room temperature was added
dropwise a THF solution (4 mL) of 6 (0.386 g; 0.60 mmol). After
the mixture was refluxed for 2 h, the solution was poured into
pentane (20 mL). The precipitate was filtered, redissolved in
THF (5 mL), and poured again in pentane (15 mL). Filtration
and drying under vacuum afforded the oligomers 7 (0.285 g).
1H NMR (CDCl3): δ 1.95 (s), 2.01 (s), 3.7-3.8 (m), 6.7-7.2 (m).
IR (KBr, cm-1): 2130 (NCN).
A small amount (ca. 5 mg) of deep brown needles was
obtained from a saturated THF solution of crude 7. 1H NMR
(CDCl3): δ 2.01 (s, 30H, C5Me5), 3.73 (s, 2H, CH2), 6.83-7.13
(m, 6H, C6H3Cl). 13C NMR (CDCl3): δ 12.35 (C5Me5), 40.03
(CH2), 123.05, 125.91, 126.52, 127.63, 129.98, 134.16, 139.64
(NCN), 141.63. IR (KBr, cm-1): 2136, 2102 (NCN). MS
(FAB): m/z 1267, 1131, 633.
X-r a y Str u ctu r e Deter m in a tion of 5. A red plate crystal
was mounted on a glass fiber. All measurements were made
on a Rigaku AFC7R diffractometer with graphite-monochro-
mated Cu KR radiation and a 12 kW rotating anode generator.
Cell constants and an orientation matrix for data collection
were obtained from a least-squares refinement using the
setting angles of 22 carefully centered reflections in the range
50.04° < 2θ < 58.38°. The data were collected at 23 ( 1 °C
using the ω-2θ scan technique to a maximum 2θ value of
120.1°. Of the 3454 reflections which were collected, 3234 were
unique (Rint ) 0.025). The intensities of three representative
minimum peaks on the final difference Fourier map cor-
responded to 0.26 and - 0.26 e-/Å3, respectively. All calcula-
tions were performed using the teXsan crystallographic soft-
ware package of Molecular Structure Corp.
Ack n ow led gm en t. The authors thank Drs. M. Goto,
K. Honda, M. Shibakami, and A. Sekiya for their
assistance in X-ray structure determinations. This work
was supported in part by CREST (Core Research for
Evolutional Science and Technology) program of J apan
Science and Technology Corporation (J ST).
Su p p or tin g In for m a tion Ava ila ble: Details of X-ray
analysis and tables of crystal data and structure refinement,
atomic coordinates, anisotropic thermal parameters, and bond
lengths and angles (14 pages). Ordering information is given
on any current masthead page.
OM971129T
(16) Sheldrick, G. M. In Crystallographic Computing 3; Sheldrick,
G. M., Kruger, C., Goddard, R., Eds.; Oxford University Press: New
York, 1985; p 175.
(17) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;
Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla, C. The
DIRDIF program system; Technical Report of the Crystallography
Laboratory; University of Nijmegen: The Netherlands, 1992.