A. C. Filippou et al.
6.8 Hz, 12H; 2ꢄC2,6-CHMeAMeB, dipp), 3.29 (sept, 3J
4H; 2ꢄC2,6-CHMeAMeB, dipp), 3.47 (s, 4H; 2ꢄNCH2), 7.03 (d, 3J-
(H,H)=6.8 Hz,
3-Cl as
a
brown, crystalline solid in around 45% yield. 1H NMR
(300.1 MHz, C6D6, 298 K): d=1.13 (d, 3J(H,H)=6.7 Hz, 12H; 2ꢄC2,6
ACHTUNGTERNUNNG -
A
(H,H)=7.7 Hz, 2H;
CHMeAMeB, dipp), 1.58 (d, 3J
(H,H)=6.8 Hz, 12H; 2ꢄC2,6-CHMeAMeB,
ACHTUNGTRENNUNG
2ꢄC4-H, dipp); 13C{1H} NMR (75.47 MHz, C6D6, 298 K): d=23.8 (s, 4C;
2ꢄC2,6-CHMeAMeB, dipp), 26.1 (s, 4C; 2ꢄC2,6-CHMeAMeB, dipp), 29.4 (s,
4C; 2ꢄC2,6-CHMeAMeB, dipp), 54.1 (s, 2C; 2ꢄNCH2), 124.9 (s, 4C; 2ꢄ
C3,5-H, dipp), 130.5 (s, 2C; 2ꢄC4-H, dipp), 133.7 (s, 2C; 2ꢄC1, dipp),
dipp), 3.50 (sept, 3J(H,H)=6.8 Hz, 4H; 2ꢄC2,6-CHMeAMeB, dipp), 3.52
ACTHNUTRGNEUNG
(s, 4H; 2ꢄNCH2), 4.59 (s, 5H; C5H5), 7.10–7.13 (m, 4H; 2ꢄC3,5-H, dipp),
7.17–7.22 ppm (m, 2H; 2ꢄC4-H, dipp); 13C{1H} NMR (75.47 MHz, C6D6,
298 K): d=23.7 (s, 4C; 2ꢄC2,6-CHMeAMeB, dipp), 26.9 (s, 4C; 2ꢄC2,6
-
146.6 (s, 4C; 2ꢄC2,6
CHMeAMeB, dipp), 29.1 (s, 4C; 2ꢄC2,6-CHMeAMeB, dipp), 53.9 (s, 2C;
2ꢄNCH2), 85.0 (s, 5C; C5H5), 125.5 (s, 4C; 2ꢄC3,5-H, dipp), 130.7 (s, 2C;
(59.63 MHz, C6D6, 298 K): d=10.8 ppm (s); IR (solid): n˜ =3065 (vw),
2961 (s), 2926 (m), 2867 (m), 1589 (w), 1488 (s), 1476 (s), 1453 (s), 1446
(s), 1419 (m), 1384 (m), 1363 (m), 1344 (vw), 1321 (m), 1302 (w), 1269
(s), 1245 (m), 1182 (m), 1163 (vw), 1150 (vw), 1102 (m), 1056 (m), 1047
(m), 1018 (w), 987 (vw), 956 (vw), 933 (w), 916 (m), 801 (s), 754 (s), 709
(vw), 677 (vw), 633 (vw), 619 (m), 611 (w, sh), 581 (vw), 572 (vw), 546
(w), 530 (vw), 457 (m), 423 cmꢀ1 (m); elemental analysis calcd (%) for
C27H38Br2N2Si (578.50): C 56.06, H 6.62, N 4.84; found: C 56.27, H 6.47,
N 4.78.
2ꢄC4-H, dipp), 133.3 (s, 2C; 2ꢄC1 dipp), 146.6 (s, 4C; 2ꢄC2,6
-
,
CHMeAMeB, dipp), 178.7 (s, 1C; NCN), 251.3 ppm (s, 2C; 2ꢄCO);
29Si NMR (59.63 MHz, C6D6, 298 K): d=113.6 ppm (s); IR (toluene): n˜ =
1894 (vs), 1806 cmꢀ1 (vs) (n(CO)); IR (fluorobenzene): n˜ =1890 (vs),
1806 cmꢀ1 (vs) (n(CO)); IR (THF, cmꢀ1): n˜ =1894 (vs), 1809 cmꢀ1 (vs)
(n(CO)).
Synthesis of 4-Br: 1,3-Dihydro-4,5-dimethyl-1,3-bis(isopropyl)-2H-imida-
zol-2-ylidene (90 mg, 0.50 mmol, 2.64 equiv) was added in portions to a
stirred solution of 3-Br·0.5C6H6 (134 mg, 0.189 mmol) in benzene (5 mL).
The reaction mixture was stirred for 15 min, filtered from a tiny amount
of a brown insoluble material, and stored overnight at ambient tempera-
ture. The supernatant solution was removed with a syringe, and the dark
red-brown crystals of 4-Br·C6H6 were washed with benzene (2ꢄ1 mL),
then hexane (2 mL), and dried for 1 h at ambient temperature in the glo-
vebox in an open vial. Yield: 120 mg (0.167 mmol, 88%). The compound
4-Br·C6H6 desolvates upon heating and then decomposes at 166–1688C
to give a black liquid. 1H NMR (300.1 MHz, [D8]THF, 298 K): d=1.31
and 1.47 (br each, 12H each; 2ꢄN1,3-CHMeAMeB, IMe2iPr2), 2.31 (s,
12H; 2ꢄC4,5-Me, IMe2iPr2), 4.30 (s, 5H; C5H5), 6.1 (br, Dn1/2 ꢂ300 Hz,
4H; 2ꢄN1,3-CHMeAMeB, IMe2iPr2), 7.30 ppm (s, 6H; C6H6); 1H NMR
Synthesis of 3-Br: A suspension of 2-Br (517 mg, 0.894 mmol) and Li-
ACHTUNGTRENNUNG[CpCr(CO)3] (217 mg, 1.04 mmol, 1.12 equiv) in benzene (10 mL) was
immersed in an ultrasonic bath for 5 min and heated at 808C for 30 min.
Pressure release was allowed for through a mercury bubbler. Evolution
of CO was observed and the color of the reaction mixture changed from
yellow to dark red-brown. The mixture was cooled to room temperature,
filtered to a schlenk-tube that contained a new portion of LiACTHUNRGTNEUNG[CpCr(CO)3]
(50 mg, 0.24 mmol, 0.27 equiv), and heating was repeated as described
above to complete the conversion of 2-Br.[39] Then the reaction mixture
was cooled to ambient temperature, concentrated to approximately 7 mL
under vacuum, and diluted with hexane (7 mL). After storage at ambient
temperature for 10 min, the reaction mixture was filtered. The brown fil-
trate was treated with hexane (10 mL) to precipitate a brown less soluble
component, and the mixture was filtered as fast as possible before the
product started to crystallize. The filtrate was stored at ꢀ58C for 16 h to
give dark brown (almost black) crystals of 3-Br·0.5C6H6 and some
brownish powder of a contaminant. The supernatant solution was deca-
nted, and the crystals were washed with hexane (2ꢄ3 mL) and dried
under vacuum (15 min, RT, 0.05 mbar). The crystals of 3-Br·0.5C6H6
were easily separated from the contaminant upon shaking into another
Schlenk tube. Yield: 340 mg (0.478 mmol, 53%). The compound starts to
decompose above 1408C and turns until 1608C into a brown liquid with
(300.1 MHz, [D8]THF, 213 K): d=0.76 (d, 3J
A
CHMeAMeB, (IMe2iPr2)X), 0.90 (d, J
E
3
(IMe2iPr2)Y), 1.37 (d, J
(H,H)=6.7 Hz, 3H; N1-CHMeAMeB, (IMe2iPr2)X),
3
1.42 (d, 3J
(H,H)=6.7 Hz, 3H; N1-CHMeAMeB, (IMe2iPr2)Y), 1.56 (d, 3J
6.7 Hz, 3H; N3-CHMeAMeB, (IMe2iPr2)X), 1.66 (d, 3J
(H,H)=6.7 Hz, 3H;
(H,H)=6.7 Hz, 3H; N3-
ACHTUNGTRENNUNG
T
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
N3-CHMeAMeB, (IMe2iPr2)Y), 1.68 (d, 3J
ACHTUNGTRENNUNG
CHMeAMeB, (IMe2iPr2)X), 2.26 (s, 3H; C4-Me, (IMe2iPr2)X), 2.34 (s, 3H;
C4-Me, (IMe2iPr2)Y), 2.37 (s, 3H; C5-Me, (IMe2iPr2)X), 2.38 (s, 3H; C5-Me,
(IMe2iPr2)Y), 4.27 (s, 5H; C5H5), 4.94 (sept, 3J
ACHTUNGTRENNUNG
1
3
CHMeAMeB, (IMe2iPr2)X), 5.12 (sept, 3J
CHMeAMeB, (IMe2iPr2)Y), 6.19 (sept, 3J
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
gas evolution. H NMR (300.1 MHz, C6D6, 298 K): d=1.13 (d, J
6.8 Hz, 12H; 2ꢄC2,6-CHMeAMeB, dipp), 1.59 (d, 3J
(H,H)=6.8 Hz, 12H;
(H,H)=
ACHTUNGTRNE(NUNG H,H)=
AHCTUNGTRENNUNG
2ꢄC2,6-CHMeAMeB, dipp), 3.51 (s, 4H; 2ꢄNCH2), 3.52 (sept, 3J
ACHTUNGTRENNUNG
CHMeAMeB, (IMe2iPr2)X), 7.34 (s, 6H; C6H6), 9.54 ppm (sept, 3J
ACHTUNGTRENNUNG
6.8 Hz, 4H; 2ꢄC2,6-CHMeAMeB, dipp), 4.64 (s, 5H; C5H5), 7.10–7.14 (m,
4H; 2ꢄC3,5-H, dipp), 7.17–7.22 ppm (m, 2H; 2ꢄC4-H, dipp);
6.7 Hz, 1H; N3-CHMeAMeB, (IMe2iPr2)Y); 13C{H} NMR (75.47 MHz,
[D8]THF, 298 K): d=10.6 (s, 4C; 2ꢄC4,5-Me, IMe2iPr2), 21.1 and 22.4
(brs each, 4C each; 2ꢄN1,3-CHMeAMeB, IMe2iPr2), 52.4 (brs, 4C; 2ꢄ
N1,3-CHMeAMeB, IMe2iPr2), 81.5 (s, 5C; C5H5), 127.0 (s, 4C; 2ꢄC4,5-Me,
IMe2iPr2), 129.0 (s, 6C; C6H6), 157.4 (s, 2C; 2ꢄC2, IMe2iPr2), 250.6 ppm
(s, 2C; 2ꢄCO); 13C{1H} NMR (75.47 MHz, [D8]THF, 213 K): d=10.36 (s,
1C; C4-Me, (IMe2iPr2)Y), 10.42 (s, 1C; C4-Me, (IMe2iPr2)X), 10.54 (s, 2C;
C5-Me, (IMe2Pr2)X and (IMe2iPr2)Y), 19.0 (s, 1C; N1-CHMeAMeB, (IM-
e2iPr2)Y), 19.3 (s, 1C; N1-CHMeAMeB, (IMe2iPr2)X), 20.9 (s, 1C; N3-
CHMeAMeB, (IMe2iPr2)X), 21.7 (s, 1C; N3-CHMeAMeB, (IMe2iPr2)X), 22.0
(s, 1C; N1-CHMeAMeB, (IMe2iPr2)Y), 22.37 (s, 1C; N3-CHMeAMeB, (IM-
e2iPr2)Y), 22.43 (s, 1C; N3-CHMeAMeB, (IMe2iPr2)Y), 23.9 (s, 1C; N1-
CHMeAMeB, (IMe2iPr2)X), 50.3 (s, 1C; N3-CHMeAMeB, (IMe2iPr2)Y), 52.2
(s, 1C; N3-CHMeAMeB, (IMe2iPr2)X), 53.3 (s, 1C; N1-CHMeAMeB, (IM-
e2iPr2)Y), 54.1 (s, 1C; N1-CHMeAMeB, (IMe2iPr2)X), 81.3 (s, 5C; C5H5),
126.6 (s, 1C; C5-Me, (IMe2iPr2)Y), 126.8 (s, 1C; C5-Me, (IMe2iPr2)X),
127.4 (s, 1C; C4-Me, (IMe2iPr2)X), 127.9 (s, 1C; C4-Me, (IMe2iPr2)Y),
129.1 (s, 6C; C6H6), 156.2 (s, 1C; C2, (IMe2iPr2)X or (IMe2iPr2)Y), 156.3
(s, 1C; C2, (IMe2iPr2)X or (IMe2iPr2)Y), 248.9 (s, 1C; CO), 251.8 ppm (s,
1C; CO); 29Si NMR (59.63 MHz, [D8]THF, 298 K): d=17.3 ppm (s); IR
(THF): n˜ =1797 (vs), 1733 cmꢀ1 (vs) (n(CO)); IR (fluorobenzene): n˜ =
1794 (vs), 1726 cmꢀ1 (vs) (n(CO)); IR (solid): n˜ =3088 (vw), 3032 (vw),
2991 (vw, sh), 2975 (w), 2937 (w), 2874 (vw), 2654 (vw), 1889 (vw), 1776
(vs) (n(CO)), 1707 (vs) (n(CO)), 1632 (m), 1476 (w), 1463 (w), 1441 (m),
1402 (vw), 1384 (m), 1369 (s), 1346 (m), 1336 (w), 1313 (vw), 1209 (m),
1183 (vw), 1168 (vw), 1148 (vw), 1134 (w), 1109 (m), 1078 (w), 1058 (vw),
1033 (w), 1006 (vw), 997 (w), 932 (vw), 903 (w), 883 (vw), 837 (vw), 794
13C{1H} NMR (75.47 MHz, C6D6, 298 K): d=23.8 (s, 4C; 2ꢄC2,6
-
CHMeAMeB, dipp), 26.9 (s, 4C; 2ꢄC2,6-CHMeAMeB, dipp), 29.1 (s, 4C;
2ꢄC2,6-CHMeAMeB, dipp), 53.9 (s, 2C; 2ꢄNCH2), 85.9 (s, 5C; C5H5),
125.5 (s, 4C; 2ꢄC3,5-H, dipp), 130.7 (s, 2C; 2ꢄC4-H, dipp), 133.5 (s, 2C;
2ꢄC1 dipp), 146.6 (s, 4C; 2ꢄC2,6-CHMeAMeB, dipp), 177.4 (s, 1C;
,
NCN), 251.7 ppm (s, 2C; 2ꢄCO); 29Si NMR (59.63 MHz, C6D6, 298 K):
d=95.1 ppm (s); IR (toluene): n˜ =1898 (vs), 1809 cmꢀ1 (vs) [n(CO)]; IR
(fluorobenzene):n˜ =1894 (vs), 1809 cmꢀ1 (vs) (n(CO)); IR (solid): n˜ =
3066 (vw), 3034 (vw), 3015 (vw), 2963 (m), 2927 (w), 2868 (w), 1893 (vs)
(n(CO)), 1867 (m, sh), 1805 (vs) (n(CO)), 1776 (s, sh), 1630 (vw), 1588
(w), 1478 (s), 1465 (m), 1453 (s), 1445 (s), 1421 (m), 1386 (m), 1366 (w),
1345 (vw), 1323 (m), 1314 (w), 1302 (m), 1288 (vw), 1272 (s), 1242 (m),
1231 (w, sh), 1217 (vw, sh), 1190 (w, sh), 1180 (m), 1150 (vw), 1111 (w,
sh), 1106 (w), 1097 (w, sh), 1055 (w), 1037 (vw), 1017 (vw), 1007 (w), 990
(vw), 963 (vw), 934 (w), 924 (m), 894 (vw), 886 (vw), 840 (vw), 822 (w),
801 (s), 754 (m), 725 (vw), 702 (vw), 680 (s), 651 (s), 623 (m), 602 (s), 567
(s), 547 (m), 523 (m), 505 (s), 488 (m), 464 (m), 445 (m), 429 (m), 416
(vw), 408 (vw), 378 cmꢀ1 (s); elemental analysis calcd (%) for
C34H43BrCrN2O2Si·0.5C6H6 (710.76): C 62.52, H 6.52, N 3.94; found: C
62.34, H 6.65, N 3.75.
Synthesis of 3-Cl: Using a similar procedure to that described for 3-Br, a
suspension of LiACHTUNGTRENNUNG[CpCr(CO)3] (approx. 3 equiv) in benzene was heated at
708C with 2-Cl[40] until conversion of 2-Cl was complete. The resulting re-
action mixture was worked up as described above for the isolation of 3-
Br to afford after crystallization from a toluene/hexane mixture complex
13580
ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2011, 17, 13574 – 13583