(CH3)3]: C, 66.0; H, 6.5; N, 12.8. Found: C, 65.7; H, 6.4; N,
12.1%). 1H NMR (CDCl3): δ 2.08 [s, 2 ortho-CH3], 2.33 [s, para-
CH3], 6.63 [d, 3JH–H = 2, 1 H of C3H3N2S], 6.84 [d, 3JH–H = 2, 1 H
of C3H3N2S], 6.99 [s, C6H2Me3], 11–12 [br, 1 H of C3H3N2S].
Synthesis of {[BmMe]Li}2
A mixture of 2-mercapto-1-methylimidazole (10.0 g, 87.6
mmol) and LiBH4 (0.795 g, 36.5 mmol) in toluene (50 mL) was
heated overnight at 50 ЊC. After this period, the volatile com-
ponents were removed in vacuo giving a white solid which
was washed with Et2O (2 × 50 mL) and with CHCl3 (30 mL)
to remove excess 2-mercapto-1-methylimidazole. Yield of
{[BmMe]Li}2ؒCHCl3: 6.0 g, 54% (Calc. for {[BmMe]Li}2ؒCHCl3:
C, 33.4; H, 4.1; N, 18.3. Found: C, 33.6; H, 4.5; N, 18.4%). IR
(KBr disk, cmϪ1): 3121 (s), 2945 (m), 2399 (m), 2379 (m), 2276
(w), 1654 (w), 1628 (w), 1560 (m), 1525 (vw), 1510 (vw), 1458
(s), 1412 (s), 1380 (vs), 1303 (m), 1193 (s), 1119 (vs), 1086 (m),
1040 (w), 1015 (vw), 959 (vw), 884 (vw), 755 (m), 727 (s), 699
(m), 678 (m), 615 (w), 512 (m), 460 (w). NMR spectroscopic
data are listed in Table 3. Crystals for X-ray diffraction were
obtained from chloroform.
Fig. 7 Selected bond lengths (Å) and angles (Њ) for [BmMe]2Zn: Zn–
S(1) 2.336(1), Zn–S(2) 2.344(1), Zn–S(3) 2.330(1), Zn–S(4) 2.338(1),
S(1)–C(11) 1.732(3), S(2)–C(21) 1.724(3), S(3)–C(31) 1.717(3), S(4)–
C(41) 1.726(4); S(1)–Zn–S(2) 115.75(4), S(1)–Zn–S(3) 114.13(4), S(1)–
Zn–S(4) 102.74(3), S(2)–Zn–S(3) 100.59(3), S(2)–Zn–S(4) 108.91(3),
S(3)–Zn–S(4) 115.16(4).
Synthesis of {[BmMe]Tl}x
Table 2 Comparison of Zn–S bond lengths in zinc complexes with
bidentate [S2] ligands
A suspension of {[BmMe]Li}2ؒCHCl3 (7.0 g, 28.4 mmol) and
Tl(O2CMe) (12.4 g, 47.1 mmol) in MeOH (85 mL) was stirred
at room temperature for 1 hour. After this period, the volatile
components were removed in vacuo giving a sticky white solid
which was washed with water (2 × 100 mL) and dried in vacuo.
Yield of {[BmMe]Tl}x: 7.23 g, 71% (Calc. for {[BmMe]Tl}x: C,
21.7; H, 2.7; N, 12.6. Found: C, 21.6; H, 2.5; N, 12.0%). IR
(KBr disk, cmϪ1): 3144 (w), 3116 (m), 3077 (w), 2934 (w), 2665
(vw), 2371 (s), 2078 (vw), 1547 (m), 1453 (s), 1402 (s), 1373 (vs),
1297 (s), 1203 (s), 1181 (s), 1165 (s), 1109 (vs), 1082 (s), 983 (m),
888 (m), 848 (vw), 828 (vw), 749 (s), 728 (s), 701 (m), 678 (m),
651 (w), 606 (vw), 518 (w), 502 (w), 458 (w). NMR spectro-
scopic data are listed in Table 3. Crystals for X-ray diffraction
were obtained from chloroform.
d(Zn–Sav)/Å
Ref.
[BmMe]ZnI
2.29
2.36
2.27
2.34
2.35
2.30
This work
This work
This work
This work
18
[BmMe]ZnMe
[BmMes]Zn(NO3)
[BmMe]2Zn
{N[PPri2(S)]2}2Zn
[MeC(S)CH2C(S)OEt]2Zn
19
Experimental
General considerations
All manipulations were performed using a combination of
glovebox, high-vacuum or Schlenk techniques.22 Solvents were
purified and degassed by standard procedures. 1H NMR
spectra were recorded on Varian VXR-400 and Bruker Avance
400 DRX spectrometers. 13C NMR spectra were recorded on
Varian VXR-300 (75.43 MHz) and Bruker Avance 300wb DRX
(75.47 MHz) spectrometers. 1H and 13C chemical shifts are
reported in ppm relative to SiMe4 (δ = 0) and were referenced
Synthesis of [BmMe]ZnI
A mixture of {[BmMe]Tl}x (660 mg, 1.48 mmol Tl) and ZnI2
(485 mg, 1.52 mmol) in CH2Cl2 was stirred at room temperature
for ca. 3 hours, resulting in the formation of a yellow precipi-
tate. After this period, the mixture was filtered. Removal of the
volatile components from the filtrate in vacuo gave [BmMe]ZnI
as a white solid. Yield of [BmMe]ZnI: 220 mg, 34% (Calc. for
[BmMe]ZnI: C, 22.3; H, 2.8; N, 13.0. Found: C, 22.3; H, 2.8; N,
12.5%). IR (KBr disk, cmϪ1): 3155 (m), 3125 (m), 3087 (w),
2948 (w), 2865 (vw), 2708 (vw), 2439 (m), 2224 (m), 2067 (w),
1559 (s), 1463 (vs), 1439 (m), 1420 (s), 1390 (vs), 1326 (m), 1299
(m), 1261 (w), 1195 ( vs), 1156 (m), 1130 (s), 1088 (s), 1049 (m),
1017 (m), 963 (m), 878 (m), 836 (w), 802 (w), 725 (s), 694 (s), 678
(w), 643 (w), 593.4 (w), 514 (m), 464 (vw). NMR spectroscopic
data are listed in Table 3. Crystals for X-ray diffraction were
obtained from chloroform.
internally with respect to the protio solvent impurity or the 13
C
resonances, respectively. All coupling constants are reported in
Hz. IR spectra were recorded as KBr pellets on Perkin-Elmer
1430 or 1600 spectrophotometers and are reported in cmϪ1
.
C, H, and N elemental analyses were measured using a
Perkin-Elmer 2400 CHN Elemental Analyzer. 2-mercapto-1-
methylimidazole was obtained from Aldrich.
Synthesis of 2-mercapto-1-mesitylimidazole
2-Mercapto-1-mesitylimidazole was prepared using a general
procedure.23 Specifically, a mixture of MesNCS24 (Mes = 2,4,6-
Me3C6H2) (15 g, 0.085 mol) and amino acetaldehyde diethyl
acetal [H2NCH2CH(OEt)2] (12.3 mL, 0.085 mol) in toluene (ca.
60 mL) was stirred at room temperature for 3 hours. After this
period, HCl(aq) (3.2 mL of 14 M, 0.045 mol) was added and
the mixture was refluxed for 7 hours. The volatile components
were removed in vacuo and water (ca. 300 mL) was added to the
residue. The pH was adjusted to 8 by the addition of NaOH
(0.1 M), resulting in the formation of a precipitate. The mixture
was filtered and the precipitate was dried, extracted into CHCl3
(ca. 500 mL), and filtered. The volatile components were
removed in vacuo, and the residue obtained was washed with
Et2O giving 2-mercapto-1-mesitylimidazole as a pale peach
colored powder (13.6 g, 74%) (Calc. for C3H3N2(S)[C6H2-
Synthesis of [BmMe]ZnMe
A suspension of {[BmMe]Tl}x (0.75 g, 1.70 mmol Tl) in benzene
(25 mL) was treated with a solution of ZnMe2 (0.29 g, 3.0
mmol) in toluene (1.5 mL), thereby resulting in the slow form-
ation of a black precipitate. The mixture was stirred for 2 hours,
filtered and the volatile components were removed in vacuo.
Yield of [BmMe]ZnMe 0.45 g (83%). IR (KBr, cmϪ1): 3122 (vs),
2938 (s), 2409 (vs), 2293 (s), 2068 (m), 1578 (w), 1561 (s), 1460
(vs), 1418 (s), 1381 (vs), 1322 (m), 1304 (m), 1227 (m), 1198 (vs),
1120 (vs), 1087 (s), 1043 (m), 1017 (m), 957 (m), 878 (w), 749 (s),
732 (vs), 697 (s), 678 (s), 663 (m), 526 (s), 502 (m), 484 (m), 455
(m). NMR spectroscopic data are listed in Table 3. Crystals for
X-ray diffraction were obtained from benzene.
894
J. Chem. Soc., Dalton Trans., 2000, 891–897