N,N′-Diferrocenyl-N-heterocyclic Carbenes
Organometallics, Vol. 18, No. 21, 1999 4335
ether precipitated the product, which was filtered off and
washed with small portions of ether and dichloromethane,
yielding 560 mg (0.96 mmol, 78.1%) of 4b. Conversion of
tetrafluoroborate 4a to tetraphenylborate 4c: A solution of 450
mg (1.9 mmol) of 4a in 700 mL of methanol was combined with
a solution of 684 mg (2 mmol) of sodium tetraphenylborate in
m, 1150 m, 1105 w, 1095 w, 1086 w, 1034 s, 1003 w, 872 w,
843 w, 816 m, 756 w, 650 s, 634 w, 519 m, 505 m, 486 w. MS
+
1
(FAB): m/z(%) 437(100) (M of cation). H NMR (CD CN): δ
3
4.32 (s, 10H, Cpunsubst), 4.40 (m, 4H, Cpsubst), 4.91 (m, 4H,
Cpsubst), 7.80 (s, 2H, -CHdCH-), 9.05 (s, 1H, -N-CHdN-).
1
3
C NMR (CD CN): δ 63.3 (Cpsubst), 68.4 (Cpsubst), 71.4
3
5
mL of methanol. The precipitated product was filtered off
(Cpunsubst), 92.1 (C(1) of Cpsubst), 123.8 (-CHdCH-), 134.4 (N-
CHdN-).
and washed with three portions of methanol and with two
portions of ether, yielding 716 mg (0.95 mmol, 50.0%) of 4c.
Da ta for 4a : Yellow crystals, mp 260 °C (dec). IR (KBr):
cm- 3110 w, 1647 s, 1479 m, 1410 w, 1377 w, 1290 s, 1124
m, 1105 s, 1084 s, 1063 s, 1036 s, 1016 m, 999 m, 850 w, 841
w, 814 m, 802 w, 515 w. MS (FAB): m/z(%) 439(100) (M+ of
cation).
1,3-Difer r ocen ylim id a zoliu m Tetr a p h en ylbor a te (7).
A solution of 15 mg (0.025 mmol) of 6 in 2 mL of methanol
was combined with a solution of 30 mg (0.067 mmol) of sodium
tetraphenylborate in 1 mL of methanol. The precipitated
product was filtered off and washed with three portions of
methanol, yielding 10 mg (0.013 mmol, 52%) of 7: yellow
1
Da ta for 4b: Yellow crystals, mp 200 °C (dec). IR (KBr):
cm- 3121 w, 1642 s, 1559 w, 1485 w, 1476 m, 1454 w, 1412
w, 1379 w, 1304 w, 1277 s, 1219 w, 1007 m, 1032 w, 1003 w,
crystals, mp 230 °C (dec). Anal. Found: C, 74.60; H, 5.47.
C H41BFe N calcd: C, 74.64; H, 5.46. IR (KBr): cm 3056
47 2 2
w, 3002 w, 1557 s, 1478 m, 1263 m, 1105 s, 1092 s, 1078 s,
1030 s, 1001 s, 868 s, 858 s, 841 s, 829 s, 748 s, 733 s, 712 s,
1
-1
8
56 s, 833 s, 821 s, 557 s, 511 m, 499 m, 490 s, 461 w. MS
+
(FAB): m/z(%) 439(100) (M of cation). Single-crystal structure
700 s, 640 s, 613 s, 511 s, 493 s, 465 s. MS (FAB): m/z(%)
437(100) (M of cation). 1H NMR (CD
+
CN): δ 4.32 (s, 10H,
analysis: Figure 2, Table 2, Supporting Information.
3
Da ta for 4c: Yellow crystals, mp 228 °C (dec). Anal.
Cpunsubst), 4.40 (m, 4H, Cpsubst), 4.86 (m, 4H, Cpsubst), 6.70-7.26
Found: C, 74.39; H, 5.75. C47
H
43BFe
2
N
2
calcd: C, 74.44; H,
(m, 20H, phenyl), 7.76 (s, 2H, -CHdCH-), 8.93 (s, 1H, -N-
13
5
1
7
.72. IR (KBr): cm-1 3056 w, 1626 s, 1580 m, 1476 s, 1425 m,
CHdN-). C NMR (CD CN): δ 63.2 (Cpsubst), 68.3 (Cpsubst),
3
302 m, 1267 s, 1105 m, 1032 m, 1001 m, 843 m, 827 s, 814 s,
48 s, 733 s, 710 s, 511 s, 492 s, 465 m, 424 w. MS (FAB):
71.2 (Cpunsubst), 93.1 (C(1) of Cpsubst), 122.6 (phenyl), 123.9
(-CHdCH-), 126.4 (phenyl), 126.5 (phenyl), 126.6 (phenyl),
134.5 (N-CHdN-), 136.7 (phenyl), 156.6 (phenyl). Single-
crystal structure analysis: Figure 4, Table 3, Supporting
+
1
m/z(%) 439(100) (M of cation). H NMR (CD
H, Cpsubst), 4.32 (s, 4H, CH CH ), 4.33 (s, 10H, Cpunsubst), 4.55
m, 4H, Cpsubst), 6.81-7.27 (m, 20H, tetraphenylborate), 8.31
3
CN): δ 4.26 (m,
4
2
2
1
2
(
(
(
1
(
Information. CV (CH
+0.75 (Table 5).
2
Cl
2
, V vs SCE): E1/2 ) +0.75, E1/2
)
1
3
s, 1H, NdCH-N). C NMR (CD
3
CN): δ 50.4 (CH
2
CH
2
), 60.6
Cpsubst), 67.6 (Cpsubst), 70.7 (Cpunsubst), 95.1 (C(1) of Cpsubst);
1,3-Difer r ocen ylim id a zole-2-th ion e (8). A solution of 117
mg (0.15 mmol) of 7 in 20 mL of THF was cooled to -80 °C,
and 0.1 mL (0.15 mmol) of a 1.5 M hexane solution of
methyllithium and, after the mixture had warmed to room
temperature, 5 mg (0.020 mmol) of sulfur were added. The
mixture was allowed to stir for 2 h. Aqueous workup yielded
32 mg (0.068 mmol, 44.2%) of 8: orange crystals, mp 251 °C.
22.7, 126.4, 136.6 (tetraphenylborate); 151.3 (NdCH-N). CV
1
2
CH
2 2
Cl , V vs SCE): E1/2 ) +0.53, E1/2 ) +0.65 (Table 5).
1
,3-Difer r ocen ylim id a zolin e-2-th ion e (5). Method A: To
a solution of 0.8 g (1.87 mmol) of 2 in 30 mL of toluene was
added 0.52 mL (3.73 mmol) of triethylamine and 0.142 mL
(
1.87 mmol) of thiophosgene, and the mixture was stirred at
ambient temperature for 3 days. Aqueous workup and chro-
matography (Al /CH Cl /ethyl acetate) yielded 415 mg (0.9
2 2
Anal. Found: C, 58.88; H, 4.30. C23H20Fe N S calcd: C, 59.00;
-
1
2
O
3
2
2
H, 4.31%. IR (KBr): cm 2967 w, 1674 w, 1647 m, 1497 s,
1408 m, 1369 m, 1346 m, 1327 s, 1269 w, 1207 w, 1150 w,
1119 m, 1026 w, 999 m, 868 s, 841 m, 806 s, 713 m, 659 w,
mmol, 47.3%) of 5. Method B: A solution of 60 mg (0.11 mmol)
of 4a in 100 mL of THF was cooled to -80 °C, 0.057 mL (0.11
mmol) of LDA and 0.15 g (0.6 mmol) of sulfur were added,
and the mixture was allowed to stir for 2 h. Aqueous workup
+
+
486 s. MS (EI, 70 eV): m/z(%) 468(100) (M ), 403(100) (M
-
+
+
+
Cp), 347(11) (M - FeCp), 338(38) (M - 2 Cp), 282(18) (M
1
and chromatography (Al
mmol, 56%) of 5: orange crystals, mp 296 °C. Anal. Found:
C, 58.71; H, 4.71. C23 S calcd: C, 58.75; H, 4.72. IR
KBr): cm 3100 w, 3085 w, 1489 s, 1431 m, 1418 m, 1408 w,
2
O
3
/ ether/hexane) yielded 30 mg (0.06
- FeCp, Cp). H NMR (CD
(s, 10H, Cpunsubst), 4.87 (m, 4H, Cpsubst), 7.14 (s, 2H, -CHd
): δ 65.9 (Cpsubst), 68.2 (Cpsubst), 69.9
2 2
Cl ): δ 4.24 (m, 4H, Cpsubst), 4.28
CH-). 13C NMR (CDCl
H
22Fe
2
N
2
3
-
1
(
(Cpunsubst), 95.4 (C(1) of Cpsubst), 119.2 (CHdCH). Single-crystal
1
1
389 w, 1377 w, 1308 m, 1296 s, 1202 m, 1105 m, 1095 w,
030 m, 999 w, 862 w, 833 w, 825 w, 806 m, 499 s, 484 s. MS
structure analysis: Figure 5, Table 4, Supporting Information.
1
2
CV (CH
5).
2 2
Cl , V vs SCE): E1/2 ) +0.46, E1/2 ) +0.55 (Table
+
+
(EI, 70 eV): m/z(%) 470(100) (M ), 405(90) (M - Cp), 121-
1
+
(33) (FeCp ). H NMR (CDCl
3
): δ 4.01 (s, 4H, CH
2
CH
2
), 4.09
Bis[1,3-d ifer r ocen ylim id a zol-2-ylid en e]silver (I) Tet -
(
m, 4H, Cpsubst), 4.21 (s, 10H, Cpunsubst), 4.86 (m, 4H, Cpsubst).
r a p h en ylbor a te (9). A mixture of 123 mg (0.16 mmol) of 7
1
3
C NMR (CDCl
3
): δ 48.8 (CH
2
), 62.5 (Cpsubst), 64.9 (Cpsubst),
in 30 mL of dichloromethane, 19 mg (0.08 mmol) of Ag O, 100
2
6
8.9 (Cpunsubst). Single-crystal structure analysis: Figure 3,
mg (2.5 mmol) of NaOH in 3 mL of H O, and 15 mg (0.027
2
Table 3, Supporting Information. CV (CH
2
Cl
2
, V vs SCE): E1/21
mmol) of tetrabutylammonium tetraphenylborate was stirred
for 48 h. The organic layer was separated from the aqueous
layer and filtered to remove solid byproducts. Addition of
hexane precipitated the crude product, which was repeatedly
dissolved in dichloromethane and precipitated with hexane to
afford 133 mg (0.1 mmol, 62.9%) of 9: yellow crystals, mp >
2
)
+0.31, E1/2 ) +0.43 (Table 5).
,3-Difer r ocen ylim idazoliu m Tr iflu or om eth an su lfon ate
6). A Schlenk vessel was charged with 40 mL of acetonitrile
and 2.4 mL (2.4 mmol) of ZnEt (1.0 M solution in hexane).
1
(
2
After cooling to -80 °C, 0.42 mL (4.74 mmol) of triflic acid
was added dropwise, and the flask was allowed to warm to
room temperature under efficient stirring. Addition of 1.0 g
4 4
200 °C (dec). Anal. Found: C, 64.45; H, 4.67. C70H60AgBFe N
-
1
calcd: C, 64.71; H, 4.65%. IR (KBr): cm 3093 w, 2983 w,
1582 m, 1497 s, 1479 s, 1458 m, 1427 w, 1381 w, 1107 m, 1032
m, 1001 w, 872 m, 843 m, 821 m, 767 s, 733 s, 609 m, 511 w,
(2.36 mmol) of 1 caused an immediate color change from dark
purple to green. Stirring was continued for 15 min, and 70
mg (2.34 mmol) of paraformaldehyde was added. The mixture
was stirred for 3 days and worked up. All volatile materials
were removed on a rotary evaporator, and the residue was
-
1
490 m, 470 w. Raman (single crystal, 785 nm): cm 1100,
992, 427, 366, 351, 324, 296, 265, 190, 157, 70. HRMS (ESI):
+
1
m/z ) 978.9713 (calc: 978.9700) (M of cation). H NMR (CD
Cl ): δ 4.25 (m, 8H, Cpsubst), 4.30 (s, 20H, Cpunsubst), 4.63 (m,
8H, Cpsubst), 6.9-7.4 (m, 20H, phenyl); 7.43 (d, 4H,
2
-
dissolved in dichloromethane and chromatographed (Al
CH Cl /CH CN; 4:1), yielding 372 mg (0.63 mmol, 26.9%) of
: yellow crystals, mp 229 °C (dec). Anal. Found: C, 49.21;
H, 3.63. C24 Fe S calcd: C, 49.17; H, 3.61. IR (KBr):
cm 3062 m, 2927 w, 1566 m, 1283 s, 1265 s, 1231 w, 1165
2
O
3
,
2
2
2
3
4
1
107/109
13
6
J ( H-
Ag) ) 1.4 Hz, -CHdCH-). C NMR (CD
64.3 (Cpsubst), 67.2 (Cpsubst), 70.4 (Cpunsubst), 97.9 (d,
2 2
Cl ): δ
H
21
F
3
2 3 2
O N
-
1
3
13
107/109
J ( C-
Ag ) 1.0 Hz, C(1) of Cpsubst); 122.1 (C(4) of phenyl);