Dalton Transactions
Paper
1
E/Z-[Rh{κ -O-N(Dipp)C(O)C
6
F
5
}(NBD)(PCy
3
)] (E/Z-3). In the
Experimental
General considerations
glovebox, 2 (20 mg, 0.018 mmol, 1 equiv.) and PCy (10 mg,
3
0.036 mmol, 2 equiv.) were weighed into a 20 mL scintillation
All experiments were carried out employing standard vial equipped with a stir bar. Subsequent addition of 5 mL
Schlenk techniques under an atmosphere of dry nitrogen benzene or toluene provided a clear yellow solution, which was
employing degassed, dried solvents. [Rh(NBD)Cl]
RhCl(PPh , NaHMDS, PPh , PCy , and CNXyl were pur- removed in vacuo and the resulting yellow solid was washed
chased and used as received. [Rh(PCy )(NBD)(Cl)]
2
,
allowed to stir for 12 h at 298 K. Next, all volatiles were
3
)
3
3
3
1
8
and with hexanes (3 × 5 mL) to give a mixture of E/Z-3 (24 mg,
3
1
9
1
Rh(CNXyl)
-benzene and d
degassed by three freeze–pump–thaw cycles. The proligand 3.17 (br), 2.92 (br), 2.00–0.84 (br). P{ H} NMR (C D , 298 K,
3
Cl were prepared using a literature procedure. 80%). H NMR (C
6 6
D , 298 K, 300 MHz, mixture of E/Z
d
6
8
-toluene were dried over sodium and isomers): δ = 7.34–6.86 (br, Ar), 4.44 (br), 3.65 (br), 3.49 (br),
3
1
1
6
6
2
0
1
1
Rh,P
-H was prepared according to literature procedures. NMR 162 MHz, mixture of E/Z isomers): δ = 31.38 (br d, J =
spectra were recorded on a Bruker Avance 300, 400, or 165.8 Hz), 27.11 (br d,
00 MHz spectrometer. C D8 refers to toluene-d8. H NMR
spectra are reported in parts per million (ppm) and were δ = 30.18 (br d, JRh,P = 171.2 Hz). F{ H} NMR (C
referenced to residual solvent: H(C
δ 128.06; H(C D ) δ 2.08;
constants are reported in Hz. C and P NMR spectra
were performed as proton-decoupled experiments and are 2F, F
1
JRh,P = 176.2 Hz) in ∼1 : 0.9 ratio.
1
31
1
6
P{ H} NMR (C D , 368 K, 162 MHz, mixture of E/Z isomers):
6 6
7
1
19
1
6
D
6
, 298 K,
1
13
6
D
6
): δ 7.16; C(C
6
D
6
): 282 MHz, mixture of E/Z isomers): δ = −139.4 (br s, 2F, F
o
,
1
13
C(C D ) δ 20.43; coupling isomer #1), −140.6 (br s, 2F, F , isomer #2), −158.0 (br s, 1F,
7
8
7
8
o
1
3
31
F
p
, isomer #1), −158.9 (br s, 1F, F
p
, isomer #2), −163.3 (br s,
, isomer #1) in ∼1 : 0.9
m
, isomer #2), −163.7 (br s, 2F, F
m
1
9
1
reported in ppm. The multiplicities are abbreviated as (isomer #1 : isomer #2). F{ H} NMR (C D , 368 K, 368 MHz):
6
6
3
3
follows: s = singlet, d = doublet, dd = doublet of doublets, δ = −139. 6 (app. d, JF,F = 19.2 Hz, 2F, F
h = heptet (septet). NMR spectra are shown using Topspin 20.4 Hz, 1F, F ), −164.2 (m, 2F, F
.2 NMR processing software. EI-MS data were obtained cm , mixture of E/Z isomers): 1605 (νCvN), 1583 (νCvN).
using a Kratos MS-50 spectrometer (70 eV source). Elemental Anal. Calcd for C48 NOPRh (893). C, 62.48%; H, 6.91%;
o
), −159.2 (t, JF,F
=
p
m
). FT-IR (ATR, solid-state,
−
1
3
58 5
H F
analyses were recorded on a Carlo Erba EA 1108 elemental N, 1.66%. Found: C, 62.70%; H, 7.19%; N, 1.51%.
1
3
1
4
analyser. N.B. Some signals in the C{ H} NMR spectra for
Rh(C F )(PCy )(η -NBD) (5). Route (a): in the glovebox,
6
5
3
the carbons of the aromatic ring bearing the fluorine atoms complex E/Z-3 (10 mg) was dissolved in 500 μL tol-d
were obscured due to extensive coupling to fluorine.
8
and
placed into a J-Young NMR tube. Subsequent heating for 1 h at
Rh {μ -N,O-N(Dipp)C(O)C F } (NBD) ] (2). In the glovebox, 100 °C provided complex 5 (90% conversion). Route (b): in the
2
0
[
2
2
6
5 2
2
4
[
2 3
Rh(NBD)Cl] (12 mg, 0.026 mmol) and 1 (20 mg, 0.051 mmol) glovebox, Rh(PCy )(η -NBD)(Cl) (150 mg, 0.29 mmol, 1 equiv.)
were weighed into a 20 mL scintillation vial equipped with a was weighed into an oven-dried Schlenk and 15 mL THF was
stir bar. Subsequent addition of 5 mL benzene or toluene pro- added to give a clear orange solution. The solution was
vided a clear dark red solution, which was allowed to stir for removed from the glovebox and cooled to 0 °C. Next, a 0.5 M
3
6 5 2
0 min at 298 K. Next, the solution was filtered through solution of C F MgBr (in Et O) was slowly added (0.6 mL,
Celite® and all volatiles were removed in vacuo. The resulting 0.29 mmol, 1 equiv.) and the solution was warmed to room
orange solid was washed with hexanes (3 × 5 mL). X-ray quality temperature and allowed to stir for 12 h. All volatiles were
crystals of 2 were obtained from a 1 : 1 hexanes-layered toluene removed in vacuo and the waxy yellow solid was extracted into
1
solution at −35 °C (26 mg, 89%). H NMR (C D , 298 K, hexanes (20 mL) and recrystallized at −35 °C to give orange
6
6
3
4
1
6
6
1
00 MHz): δ = 7.26 (dd, JH,H = 7.7 Hz, JH,H = 1.3 Hz, 2H, Ar), crystals of 5 (102 mg, 54%). H NMR (C
.98 (t, JH,H = 7.7 Hz, 2H, Ar), 6.78 (dd, JH,H = 7.7 Hz, JH,H
.3 Hz, 2H, Ar), 4.48 (br s, 2H, NBD), 4.45 (br s, 2H, NBD), 4.18 NBD), 2.00–0.90 (m, 33H, PCy ), 1.26 (br s, 2H, NBD by H– H
h, JH,H = 6.8 Hz, 2H, iPr), 4.15 (br s, 2H, NBD), 3.94 (br s, 2H, COSY). C{ H} NMR (C
6
D
6
, 298 K, 400 MHz):
3
3
4
=
δ = 4.76 (br s, 2H, NBD), 4.23 (br s, 2H, NBD), 3.55 (br s, 2H,
1
1
3
3
13
1
(
6 6
D , 298 K, 100 MHz): δ = 75.23 (dt, J =
NBD), 3.48 (br s, 2H, NBD) 2.89 (br s, 2H, NBD), 2.70 (h, 9.0 Hz, J = 3.5 Hz), 66.35 (t, J = 3.8 Hz), 65.90 (d, J = 7.8 Hz),
3
3
J
= 6.9 Hz, 2H, iPr), 2.40 (d, J
= 6.6 Hz, 6H, iPr), 1.37 52.84, 35.45 (d, J = 16.1 Hz), 30.06, 27.96 (d, J = 10.0 Hz), 26.69.
H,H
3
H,H
1
1
31
1
1
(d, JH,H = 6.7 Hz, 6H, iPr), 1.25 (2H, NBD; by H– H COSY),
P{ H} NMR (C
6
D
6
, 298 K, 162 MHz): δ = 164.79 ( JRh,P = 164.8
D
6 6
1
1
3
19
1
1
.07 (2H, NBD; by H– H COSY), 1.00 (d, JH,H = 6.7 Hz, 6H, Hz). F{ H} NMR (C , 298 K, 282 MHz): δ = −111.3 (m, 2F,
3
13
1
3
iPr), 0.86 (d, JH,H = 6.7 Hz, 6H, iPr). C{ H} NMR (C D , F ), −162.5 (t, J = 20.3 Hz, 1F, F ), −164.9 (m, 2F, F ). EI-MS
2
6
6
o
F,F
p
m
+
98 K, 150 MHz): δ = 162.7, 146.6, 143.4, 141.4, 128.6, 126.1, (m/z): 642 [M] . Anal. Calcd for C31
H
41
F
5
PRh (642). C, 57.95%;
1
24.9, 123.4, 60.40 (m), 52.79 (d, JRh,C = 11.1 Hz), 52.07 (d, H, 6.43%. Found: C, 57.98%; H, 6.39%.
1
JRh,C = 11.1 Hz), 51.21, 50.87, 47.70 (d, J
2
= 11.5 Hz), 28.90,
[Rh{κ -O-N(Dipp)C(O)C F }(CNXyl) ] (6). Route (a): in the
Rh,C
6
5
3
1
9
1
8.51, 26.82, 26.60, 24.15, 23.92. F{ H} NMR (C
6
D
6
, 298 K, glovebox, [Rh(NBD)Cl]
2
(12 mg, 0.026 mmol) and 1 (20 mg,
3
76 MHz): δ = −135.9 (br s, 2F, F ), −140.5 (br s, 2F, F
o
o
), −154.3 0.051 mmol) were weighed into a 20 mL scintillation vial
3
(t, J = 21.4 Hz, 2F, F ), −161.8 (br s, 2F, F ), −163.2 (br s, equipped with a stir bar. Subsequent addition of 5 mL
F,F
p
m
+
+
2
F, F
m
). EI-MS (m/z): 1130 [M] , 565 [M/2] . Anal. Calcd for benzene or toluene provided a clear dark red solution, which
C
52
H
50
F
10
N
2
O
2
Rh (1130). C, 55.23%; H, 4.46%; N, 2.48%. was allowed to stir for 10 min at 298 K. Next, CNXyl (20 mg,
2
Found: C, 55.21%; H, 4.52%; N, 2.28%.
0.15 mmol) was added giving an orange solution, which was
This journal is © The Royal Society of Chemistry 2015
Dalton Trans., 2015, 44, 19487–19493 | 19491