Rhodium(I) N-Heterocyclic Carbene Complexes
FULL PAPER
1,3-Dimethylperimidinium iodide (2a): Yield: 0.622 g (1.9 mmol, 32%)
(1,3-Dibenzylbenzimidazol-2-ylidene)chlorido(h2,h2-cycloocta-1,5-diene)-
light-brown powder. 1H NMR ([D6]DMSO): d=3.52 (s, 6H -NCH3), 7.04
ACHTUNGTRENrNUNG hodium(I) (3d): Yield: 0.070 g (0.12 mmol, 35%) yellow powder.
3
(d, 2H, ArH, 3JHH =7.6 Hz), 7.54 (dd, 2H, ArH, 3JHH =7.6 Hz, JHH
=
1H NMR (CDCl3): d=1.76–1.87 (m, 2H, CH2 COD), 1.87–1.98 (m, 2H,
CH2 COD), 2.06–2.24 (m, 2H, CH2 COD), 2.26–2.41 (m, 2H, CH2
8.4 Hz), 7.65 (d, 2H, ArH, 3JHH =8.4 Hz), 9.01 ppm (s, 1H, ArH2);
13C NMR ([D6]DMSO): d=38.67 (-NCH3), 107.64 (ArC), 120.35 (quater-
nary ArC), 123.53 and 128.36 (ArC), 132.84 and 133.84 (quaternary
ArC), 153.32 ppm (ArC2); elemental analysis calcd (%) for C13H13N2I: C
48.17, H 4.04, N 8.64; found: C 47.98, H 4.31, N 8.50.
COD), 3.25–3.43 (m, 2H, CH COD), 5.10–5.26 (m, 2H, CH COD), 6.20
2
(d, 2H, -NCH2Ar, 2JHH =15.8 Hz), 6.31 (d, 2H, -NCH2Ar, JHH
=
4
3
15.8 Hz), 6.98 (m, 2H, ArH4/7, JHH =3.0 Hz, JHH =6.3 Hz), 7.02 (dd, 2H,
ArH5/6
,
4JHH =3.3 Hz, 3JHH =5.9 Hz), 7.29–7.33 (m, 2H, -NCH2ArH),
7.34–7.38 (m, 4H, -NCH2ArH), 7.38–7.42 ppm (m, 4H, -NCH2ArH);
13C NMR (CDCl3): d=28.65 (CH2 COD), 32.74 (CH2 COD), 52.96
(-NCH2Ar), 69.19 (d, cis-CH COD, 1JRhC =14.3 Hz), 100.53 (d, trans-CH
1,3-Diethylperimidinium iodide (2b): Yield: 0.622 g (1.9 mmol, 32%)
light-brown powder. 1H NMR ([D6]DMSO): d=1.41 (t, 6H, -NCH2CH3,
3JHH =7.1 Hz), 4.03 (q, 4H, -NCH2CH3, 3JHH =7.1 Hz), 7.12 (d, 2H, ArH,
3JHH =7.7 Hz), 7.52 (dd, 2H, ArH, 3JHH =7.7 Hz, 3JHH =8.3 Hz), 7.62 (d,
2H, ArH, 3JHH =8.3 Hz), 8.95 ppm (s, 1H, ArH2); 13C NMR
([D6]DMSO): d=11.82 (-NCH2CH3), 46.72 (-NCH2CH3), 107.65 (ArC),
121.13 (quaternary ArC), 123.39 and 128.31 (ArC), 131.43 and 134.43
(quaternary ArC), 152.36 ppm (s, ArC2); elemental analysis calcd (%)
for C15H17N2I: C 51.15, H 4.86, N 7.95; found: C 51.08, H 4.49, N 7.55.
1
COD, JRhC =6.6 Hz), 110.93, 122.48, 127.08, 127.82, 128.90, 135.01, 136.15
1
(18C, ArC), 197.83 ppm (d, ArC2, JRhC =51.0 Hz); MS(EI): 544 [M+]; el-
emental analysis calcd (%) for C29H30N2ClRh: C 63.92, H 5.55, N 5.14;
found: C 64.14, H 5.78, N 5.26.
Chlorido(h2,h2-cycloocta-1,5-diene)(1,3-dimethylperimidin-2-ylidene)-
AHCTUNGTREGrNNUN hodium(I) (4a): Yield: 0.084 g (0.19 mmol, 61%) yellow powder.
1H NMR (CDCl3): d=1.94–2.04 (m, 4H, CH2 COD), 2.44–2.48 (m, 4H,
CH2 COD), 3.40 (m, 2H, CH COD), 4.54 (s, 6H, -NCH3), 5.08 (m, 2H,
CH COD), 6.67 (m, 2H, ArH), 7.30–7.40 ppm (m, 4H, ArH); 13C NMR
General procedure for synthesis of the [RhACTHNUTRGENN(UG cod)ACHUTNGTRENN(NGU NHC)] derivatives: The
respective benzimidazolium- or perimidinium halide (0.32 mmol) and
Ag2O (0.0371 g, 0.16 mmol) were added to a dried Schlenk tube. The
mixture was backflashed three times with N2 and then dry CH2Cl2 was
added (15 mL). The flask was closed and stirred for 4 h in the dark. A so-
(CDCl3): d=28.86 (CH2 COD), 32.52 (CH2 COD), 43.16 (-NCH3), 70.06
1
(d, cis-CH COD, 1JRhC =14.6 Hz), 98.22 (d, trans-CH COD, JRhC
=
lution of bisACHTUNGTRENNUNG
[chlorido(h2,h2-cycloocta-1,5-diene)rhodium(I)] (0.078 g,
6.8 Hz), 104.35 (ArC), 119.71 (quaternary ArC), 121.04 and 127.76
1
(ArC), 134.17 and 134.96 (quaternary ArC), 211.63 ppm (d, ArC2, JRhC
=
0.16 mmol) in CH2Cl2 was added (10 mL) and the solution was stirred for
2–12 h in the dark. The obtained suspension was filtered over Celite
(281 nm) and concentrated in a vacuum. The yellow residue was recrys-
tallized from CH2Cl2/n-hexane (10/40 mL) at 48C.
48.6 Hz); MS(EI): m/z: 442 [M+]; elemental analysis calcd (%) for
C21H24N2ClRh: C 51.99, H 5.65, N 7.13; found: C 51.68, H 5.59, N 6.97.
Chlorido(h2,h2-cycloocta-1,5-diene)(1,3-diethylperimidin-2-ylidene)-
Chlorido(h2,h2-cycloocta-1,5-diene)(1,3-dimethylbenzimidazol-2-ylidene)-
AHCTUNGTREGrNNUN hodium(I) (4b): Yield: 0.072 g (0.15 mmol, 48%) brown powder.
1H NMR (CDCl3): d=1.59 (t, 6H, -NCH2CH3, 3JHH =7.0 Hz), 1.86–2.10
(m, 4H, CH2 COD), 2.33–2.57 (m, 4H, CH2 COD), 3.32 (m, 2H, CH
COD), 4.68 (m, 2H, -NCH2CH3), 5.06 (m, 2H, CH COD), 6.29 (m, 2H,
-NCH2CH3), 6.67 (dd, 2H, ArH, 4JHH =1.2 Hz, 3JHH =7.3 Hz), 7.27–
7.35 ppm (m, 4H, ArH); 13C NMR (CDCl3): d=11.59 (-NCH2CH3), 28.85
(CH2 COD), 32.51 (CH2 COD), 49.96 (-NCH2CH3), 70.47 (d, cis-CH
COD, 1JRhC =14.6 Hz), 97.73 (d, trans-CH COD, 1JRhC =6.8 Hz), 105.11
(ArC), 120.75 (quaternary ArC), 120.94 and 127.63 (ArC), 133.25 and
134.85 (quaternary ArC), 211.65 ppm (d, ArC2, 1JRhC =48.5 Hz); MS(EI):
m/z: 470 [M+]; elemental analysis calcd (%) for C23H28N2ClRh: C 58.67
H 5.99, N 5.95; found: C 58.41, H 5.69, N 5.70.
ACHTUNGTRENNUNGrhodium(I) (3a): The preparation of this compound has been reported
previously.[50] Yield: 0.084 g (0.21 mmol, 69%) yellow powder. 1H NMR
(CDCl3): d=2.01–2.12 (m, 4H, CH2 COD), 2.44–2.57 (m, 4H, CH2
COD), 3.40 (m, 2H, CH COD), 4.35 (s, 6H, -NCH3), 5.20 (m, 2H, CH
COD), 7.23 (m, 2H, ArH4/7), 7.28 ppm (m, 2H, ArH5/6); 13C NMR
(CDCl3): d=28.85 (CH2 COD), 32.97 (CH2 COD), 34.64 (-NCH3), 68.35
1
(d, cis-CH COD, 1JRhC =14.9 Hz), 100.35 (d, trans-CH COD, JRhC
=
6.8 Hz), 109.25 and 122.38 ppm (ArC), 135.32 (quaternary ArC),
196.14 ppm (d, ArC2, 1JRhC =50.6 Hz); MS (EI): m/z: 392 [M+]; elemental
analysis calcd (%) for C17H22N2Cl2Rh: C 51.99, H 5.65, N 7.13; found: C
51.68, H 5.59, N 6.97.
Chlorido(h2,h2-cycloocta-1,5-diene)(1,3-diethylbenzimidazol-2-ylidene)-
ACHTUNGTRENNUNGrhodium(I) (3b): The preparation of this compound has been reported
General procedure for the synthesis of rhodium dicarbonyl derivatives:
The respective [RhACTHNUTRGNEU(GN cod)] derivative was added to a dried Schlenk tube.
previously.[16] Yield: 0.107 g (0.22 mmol, 72%) yellow powder. 1H NMR
(CDCl3): d=1.63 (t, 6H, -NCH2CH3, 3JHH =7.3 Hz), 1.96–2.06 (m, 4H,
CH2 COD), 3.41–3.51 (m, 4H, CH2 COD), 3.37 (m, 2H, CH COD), 4.81
(dq, 2H, -NCH2CH3, 3JHH =7.3 Hz, 2JHH =14.4 Hz), 5.05 (dq, 2H
-NCH2CH3, 3JHH =7.3 Hz, 2JHH =14.4 Hz), 5.14 (m, 2H, CH COD), 7.21
The complex was back flashed three times with carbon monoxide and
then dry CH2Cl2 was added (15 mL). The solution was stirred under
a constant flux of CO for 30 min. The solution was concentrated in
vacuum (ꢀ5 mL) and precipitated by addition of n-hexane (ꢀ30 mL) at
48C.
(dd, 2H, ArH4/7
,
4JHH =3.1 Hz, 3JHH =6.0 Hz), 7.32 ppm (dd, 2H, ArH5/6
,
Dicarbonylchlorido(1,3-dimethylbenzimidazol-2-ylidene)ACTHNGUTERNNUrG hodium(I) (5a):
4JHH =3.1 Hz, 3JHH =6.0 Hz); 13C NMR (CDCl3): d=14.96 (-NCH2CH3),
28.79 (CH2 COD), 32.90 (CH2 COD), 43.60 (-NCH2CH3), 68.58 (d, cis-
CH COD, 1JRhC =14.2 Hz), 99.93 (d, trans-CH COD, 1JRhC =6.7 Hz),
109.88 and 122.11 (ArC), 134.44 (quaternary ArC), 195.23 ppm (d, ArC2,
1JRhC =50.6 Hz); MS (EI): m/z: 420 [M+]; elemental analysis calcd (%)
for C19H26N2ClRh: C 52.50, H 5.87, N 5.83; found: C 52.64, H 5.72, N
5.65.
Yield: 0.021 g (0.06 mmol, 48%) yellow powder. 1H NMR (CDCl3): d=
4.14 (s, 6H, -NCH3), 7.40 (m, 4H, ArH), 13C NMR (CDCl3): d=35.22
(-NCH3), 110.40 and 123.69 (ArC), 134.85 (quaternary ArC), 182.40 (d,
cis-CO, 1JRhC =74.2 Hz), 185.21, 185.30 (d, trans-CO, 1JRhC =53.6 Hz),
185.36 ppm (d, NHC, 1JRhC =43.1 Hz); FTIR: n˜ =2074 (n˜(CO)sym),
1989 cmÀ1 (v˜(CO)asym); MS (EI): m/z: 318 [M+ÀCO]; elemental analysis
calcd (%) for C11H10ClN2O2Rh: C 38.79, H 2.96, N 8.23; found: C 39.20,
H 3.10, N 7.89.
Chlorido(h2,h2-cycloocta-1,5-diene)(1,3-diisopropylbenzimidazol-2-
ylidene)
ported previously.[53] Yield: 0.087 g (0.17 mmol, 55%) yellow powder.
1H NMR (CDCl3): d=1.70 (d, 6H, -NCH(CH3)2, 3JHH =7.1 Hz), 1.79 (d,
6H, -NCH
(CH3)2, 3JHH =7.1 Hz), 1.94–2.04 (m, 4H, CH2 COD), 2.39–2.49
G
Dicarbonylchlorido(1,3-diethylbenzimidazol-2-ylidene)ACTHNGUTERNNUrG hodium(I) (5b):
The preparation of this compound has previously been reported.[52]
Yield: 0.016 g (0.04 mmol, 33%) yellow powder. 1H NMR (CDCl3): d=
3
1.58 (t, 6H, 3JK =7.3 Hz, -NCH2CH3), 4.62 (dq, 2H, -NCH2CH3, JHH
=
2
(m, 4H, CH2 COD), 3.46 (m, 2H, CH COD), 5.10 (m, 2H, CH COD),
7.3 Hz, 2JHH =14.4 Hz), 4.75 (dq, 2H, -NCH2CH3, 3JHH =7.3 Hz, JHH
=
4
3
6.49 (hept, 2H, -NCH
3.1 Hz, 3JHH =6.1 Hz), 7.50 ppm (dd, 2H, ArH5/6
6.1 Hz); 13C NMR (CDCl3): d=20.88 and 21.88 (-NCH
G
,
4JHH
=
14.4 Hz), 7.36 (dd, 2H, ArH4/7, JHH =3.1 Hz, JHH =6.1 Hz), 7.45 (dd, 2H,
ArH5/6
4JHH =3.1 Hz, 3JHH =6.1 Hz); 13C NMR (CDCl3): d=14.79
(-NCH2CH3), 43.89 (-NCH2CH3), 110.77 and 123.47 (ArC), 134.02 (qua-
3
4JHH =3.1 Hz, JHH
=
,
1
1
(CH2 COD), 32.88 (CH2 COD), 53.87 (-NCH
G
ternary ArC), 182.61 (d, cis-CO, JRhC =72.2 Hz), 184.26 (d, NHC, JRhC =
COD, 1JRhC =14.5 Hz), 99.17 (d, trans-CH COD, 1JRhC =6.7 Hz), 112.08
42.5 Hz), 185.30 ppm (d, trans-CO, 1JRhC =53.8 Hz); FTIR: 2077
(v(CO)sym), 1991 cmÀ1 (v(CO)asym); MS (EI): m/z: 340 [M+ÀCO]; ele-
mental analysis calcd (%) for C13H14ClN2O2Rh: C 42.36, H 3.83, N 7.60;
found: C 41.98, H 3.55, N 7.53.
and 121.51 (ArC). 133.64 (quaternary ArC), 194.00 ppm (d, ArC2, JRhC
50.3 Hz); MS (EI): m/z: 448 [M+]; elemental analysis calcd (%) for
C21H30N2ClRh: C 54.33, H 6.34, N 5.51; found: C 54.14, H 6.33, N 5.23.
Chem. Eur. J. 2013, 19, 17871 – 17880
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
17877