4704 Organometallics, Vol. 18, No. 23, 1999
Foley et al.
eter with deuterated benzene as a solvent and internal
standard. All elemental analyses were run on a Perkin-Elmer
PE CHN 4000 elemental analysis system.
[C6H11NC(Me)NC6H11]Sn [N(SiMe3)2] (1). To a solution of
dicyclohexylcarbodiimide (0.653 g, 3.16 mmol) in diethyl ether
(60 mL) was added MeLi (2.26 mL, 1.4 M, 3.16 mmol). After
30 min, 1 equiv of SnCl2 (0.600 g, 3.15 mmol) was added to
this mixture, which was stirred for 1.5 h. Lithium bis-
(trimethylsilylamide) (0.530 g, 3.16 mmol) was then added to
the reaction mixture. The solution was stirred for another 12
h and filtered to remove the white LiCl precipitate. The solvent
was removed under vacuum, at which point a yellow oil was
observed as the sole product (1.49 g, 94% yield). 1H NMR (C6D6,
ppm): 3.09 (br, C6H11, 2H); 1.97-1.02 (m, C6H11, 20H); 1.35
(s, Me, 3H); 0.47 (s, SiMe3, 18H). 119Sn NMR (C6D6, ppm vs
SnMe4): 17.6.
[C6H11NC(tBu )NC6H11]Sn [N(SiMe3)2] (2). To a solution of
dicyclohexylcarbodiimide (0.816 g, 3.97 mmol) in diethyl ether
t
(60 mL) was added BuLi (2.33 mL, 1.7 M, 3.96 mmol). After
15 min, 1 equiv of SnCl2 (0.750 g, 3.96 mmol) was added to
this mixture, which was stirred for 2 h. Lithium bis(trimeth-
ylsilylamide) (0.663 g, 3.96 mmol) was then added to the
reaction mixture. The solution was stirred for another 14 h,
filtered to remove the white LiCl precipitate, and evaporated
to dryness. White crystals were obtained from diethyl ether
at -34 °C (2.010 g, 94% yield). Mp: 82-84 °C. 1H NMR (C6D6,
ppm): 3.87 (br, C6H11, 2H); 2.16-0.92 (m, C6H11, 20H); 1.16
(s, tBu, 9H); 0.48 (s, SiMe3, 18H). 13C NMR (C6D6, ppm): 173.5
(s, NCtBuN); 55.6, 41.0, 35.7, 25.9 (4s, C6H11); 41.8 (s, C(CH3)3);
29.5 (s, C(CH3)3); 5.3 (s, SiMe3). 119Sn NMR (C6D6, ppm vs
SnMe4): 10.3. Anal. Calcd for C23H49N3Si2Sn: C 50.92; H 9.10;
N 7.75. Found: C 50.73; H 8.88; N 7.41.
Figu r e 4. Molecular structure and atom-numbering scheme
for (PhNCO)3 (7). Selected bond distances (Å) and angles
(deg): O(1)-C(5) 1.211(3), O(2)-C(6) 1.203(4), N(1)-C(5)
1.395(3), N(1)-C(4) 1.458(4), N(2)-C(5) 1.387(3), N(2)-C(6)
1.391(3), N(2)-C(12) 1.455(3), C(5)-N(1)-C(5)a 123.6(3),
C(5)-N(1)-C(4) 118.22(13), C(5)-N(2)-C(6) 124.7(2), C(5)-
N(2)-C(12) 118.15(19), C(6)-N(2)-C(12) 117.18(19), C(3)-
C(4)-N(1) 119.30(15), O(1)-C(5)-N(2) 121.9(2), O(1)-
C(5)-N(1) 122.3(2), N(2)-C(5)-N(1) 115.8(2), O(2)-C(6)-
N(2) 122.46(14), N(2)A-C(6)-N(2) 115.1(3).
[C6H11NC(Me)NC6H11]Sn [N(SiMe3)2]S4 (3). To a solution
of 1 (0.230 g, 0.460 mmol) in diethyl ether (5 mL) was added
0.5 equiv of S8 (0.060 g, 0.234 mmol). The solution was allowed
to react for 3 h. A small amount of insoluble white precipitate
formed, which was filtered off. Yellow crystals were obtained
from diethyl ether at -34 °C (0.19 g, 66% yield). Mp: 133 °C
(dec). 1H NMR (C6D6, ppm): 3.30 (br, C6H11, 2H); 1.87-0.96
(m, C6H11, 20H); 1.23 (s, Me, 3H); 0.40 (s, SiMe3, 18H). 13C
NMR (C6D6, ppm): 168.3 (s, NCMeN); 56.2, 35.4, 25.7, 12.3
(4s, C6H11); 26.0 (s, CCH3); 5.3 (s, SiMe3). 119Sn NMR (C6D6,
ppm vs SnMe4): 156.5. Anal. Calcd for C20H43N3Si2S4Sn: C
38.21; H 6.89; N 6.68. Found: C 37.12; H 6.63; N 6.09.
et al. of the nucleophilic behavior for the â-S in the Ar2-
SnS4 and Ar2GeS4 complexes that they reported.8c,27
Con clu sion
In summary, these results add significantly to the
limited number of structurally characterized main group
cyclopolychalcogenido complexes and will help to delin-
eate the steric and electronic features that stabilize and
influence the reactivity of such species. The reactivity
of 1 and 2 contrasts with the reported Ge(II/IV) ana-
logues yielding cyclic tetrasulfido species (3 and 4) and
µ-sulfido complexes (5 and 6) rather than terminal
species. The cyclo-SnS4 complexes are interesting and
very effective catalysts for isocyanate trimerization. We
are currently attempting to clarify the details regarding
the catalyst lifetime and activity as well as illustrate
the selectivity of this system. Furthermore, we hope to
extend these efforts to include identification of the
features that favor isocyanate dimer, trimer, and poly-
mer formation.
[C6H11NC(tBu )NC6H11]Sn [N(SiMe3)2]S4 (4). To a solution
of 2 (0.450 g, 0.829 mmol) in diethyl ether (20 mL) was added
0.5 equiv of S8 (0.106 g, 0.415 mmol). The solution was allowed
to react for 18 h. A small amount of insoluble white precipitate
formed, which was filtered off. Yellow crystals were obtained
from diethyl ether at -34 °C (0.38 g, 68% yield). Mp: 79-81
1
°C. H NMR (C6D6, ppm): 3.72 (br, C6H11, 2H); 2.15-0.83 (m,
C6H11, 20H); 1.08 (s, tBu, 9H); 0.43 (s, SiMe3, 18H). 119Sn NMR
(C6D6, ppm vs SnMe4): 154.8. Anal. Calcd for C23H49N3Si2S4-
Sn: C 41.18; H 7.36; N 6.26. Found: C 40.31; H 7.06; N 5.53.
{[C6H11NC(Me)NC6H11]Sn [N(SiMe3)2]S}2 (5). To a solu-
tion of 1 (0.300 g, 0.600 mmol) in toluene (5 mL) was added
excess propylene sulfide (0.180 g). The homogeneous solution
was allowed to react for 5 days, after which sparingly soluble
white crystals were obtained at room temperature (0.285 g,
89% yield). Mp: 172-173 °C. 1H NMR (CDCl3, ppm): 3.30 (br,
C6H11, 2H); 1.97-1.05 (m, C6H11, 20H); 1.52 (s, Me, 3H); 0.43
(s, SiMe3, 18H). Anal. Calcd for C20H43N3Si2SnS: C 45.11; H
8.14; N 7.89. Found: C 45.46; H 7.95; N 7.60.
{[C6H11NC(tBu )NC6H11]Sn [N(SiMe3)2]S}2 (6). To a solu-
tion of 2 (0.288 g, 0.531 mmol) in diethyl ether (4 mL) was
added excess styrene sulfide (0.144 g). The homogeneous
solution was allowed to react for 2 days, after which sparingly
soluble white crystals were obtained at room temperature
(0.276 g, 90% yield). Mp: 168-170 °C. 1H NMR (CDCl3, ppm):
3.65 (br, C6H11, 2H); 2.10-0.90 (m, C6H11, 20H); 1.39 (s, Me,
Exp er im en ta l Deta ils
Gen er a l P r oced u r e. All manipulations were carried out
either in a Vacuum Atmospheres drybox or under nitrogen
using standard Schlenk-line techniques. Diethyl ether, hexane,
toluene, benzene, and deuterated benzene were distilled under
nitrogen from Na/K alloy. MeLi (1.4 M in diethyl ether), tBuLi
(1.7 M in pentane), SnCl2, dicyclohexylcarbodiimide, LiN-
(SiMe3)2, phenyl isocyanate, p-methoxyphenyl isocyanate, and
propylene sulfide were purchased from Aldrich and used
without further purification. S8 was recrystallized from tolu-
ene. NMR spectra were run on a GEMINI 200 MHz spectrom-
(27) Matsuhashi, Y.; Tokitoh, N.; Okazaki, R. Organometallics 1994,
13, 4387.