[Rh(trop2N)(eq-PPh3)(ax-PhNvN(O)Ph)]. To a solution of
[RhCl(PPh3)(trop2NH)] (100 mg, 0.125 mmol, 1 equiv.) in THF
(2 mL) and toluene (1 mL) was added t-BuOK (14 mg,
0.125 mmol, 1 equiv.). The reaction mixture was stirred for
30 min then all volatiles were removed under reduced pressure.
Toluene (1 mL) was added to the residue and removed again
under reduced pressure. The residue was dissolved in THF and
filtrated, then azoxybenzene (26 mg, 0.132 mmol, 1.05 equiv.)
was added. The resulting solution was stirred overnight then the
solvent was removed under reduced pressure. Yield: 101 mg,
(250.13 MHz, CDCl3, 25 °C): δ = 1H, 3.97 (s, 3H, CH3), 3.99
(s, 3H, CH3), 8.18–8.19 (m, 4H, CHar), 8.21–8.23 (m, 2H,
CHar), 8.39–8.42 (m, 2H, CHar); 13C{1H}-NMR (62.90 MHz,
CDCl3, 25 °C): δ = 52.3 (s, 1C, CH3), 52.6 (s, 1C, CH3), 122.6
(s, 2C, CHar), 125.3 (s, 2C, CHar), 130.2 (s, 2C, CHar), 130.4
(s, 2C, CHar), 130.7 (s, 1C, Cquat), 133.3 (s, 1C, Cquat), 147.0
(s, 1C, Cquat), 150.9 (s, 1C, Cquat), 165.7 (s, 1C, CO2Me), 166.2
(s, 1C, CO2Me).
1
84%. M.p.: 74–76 °C (decomposition); H-NMR (400.13 MHz,
[D8]THF, 273 K): δ = 0.86 (s, 1H, NH), 4.06 (s, 2H, CHbenzyl),
4.80 (dd, J = 9.2 Hz, J = 5.0 Hz, 2H, CHolefin), 4.92 (t, J =
7.4 Hz, 2H, CHolefin), 5.49 (t, J = 7.60 Hz, 2H, CHar), 6.42 (d, J
= 7.5 Hz, 2H, CHar), 6.56 (d, J = 7.3 Hz, 2H, CHar), 6.67–6.73
(m, 4H, CHar), 6.75–6.81 (m, 4H, CHar), 6.86 (t, J = 7.4 Hz, 2H,
CHar), 6.94 (t, J = 7.3 Hz, 2H, CHar), 7.05 (d, J = 7.6 Hz, 2H,
CHar), 7.15 (t, J = 7.3 Hz, 1H, CHar), 7.30–7.37 (m, 6H, CHar),
7.45 (t, J = 7.4 Hz, 1H, CHar), 7.53 (t, J = 7.7 Hz, 3H, CHar),
7.59–7.65 (m, 2H, CHar), 8.28 (d, J = 7.9 Hz, 2H, CHar),
8.33–8.39 (m, 6H, CHar); 13C{1H}-NMR (100.61 MHz,
[D8]THF, 273 K): δ = 67.6–67.7 (m, 1C, CHolefin), 70.0 (dd, J = 17.6
Hz, J = 10.3 Hz, 2C, CHolefin), 71.0 (s, 2C, CHbenzyl), 122.4 (s,
2C, CHar), 123.7 (d, J = 1.6 Hz, 2C, CHar), 124.1 (s, 2C, CHar),
125.9 (s, 2C, CHar), 126.6 (s, 2C, CHar), 127.7 (d, J = 4.3 Hz,
2C, CHar), 127.9–128.0 (m, 8C, CHar), 128.5 (s, 2C, CHar),
128.5–128.7 (m, 3C, CHar), 128.9 (s, 2C, CHar), 129.1–129.2
(m, 4C, CHar), 129.2 (s, 2C, CHar), 130.0 (s, 1C, CHar), 131.4
(d, J = 8.7 Hz, 2C, CHar), 131.8 (d, J = 2.5 Hz, 1C, Cquat, azoxybenzene),
132.0 (s, 1C, CHar), 132.2 (d, 1JPC = 9.4 Hz, 1C, Cquat, phosphane),
133.6 (d, J = 10.5 Hz, 4C, CHar), 133.9 (d, J = 2.1 Hz, 2C,
Cquat, trop), 136.2 (s, 2C, Cquat, trop), 137.5 (d, J = 4.6 Hz, 2C,
Complex synthesis
[Rh(trop2NH)(PPh3)(PhNHO)] (4). To
a solution of
[Rh(trop2N)(PPh3)] (1) (42 mg, 55 μmol, 1 equiv.) in THF
(1 mL) was added N-phenyl hydroxylamine (6.3 mg, 58 μmol,
1.05 equiv.). After 15 min the orange precipitate was filtered off,
washed with a small portion of Et2O (2 mL) and dried under
high vacuum. Yield: 38 mg, 79%.
Alternative procedure. Hydrogen gas was bubbled through a
solution of [Rh(trop2N)(PPh3)] (1) (84 mg, 0.11 mmol, 1 equiv.)
in THF (1 mL) until the colour of the solution changed from
deep green to yellow and the 31P-NMR confirmed complete reac-
tion to the hydride complex [RhH(trop2NH)(PPh3)] (3). To this
solution nitrosobenzene (11.8 mg, 0.11 μmol, 1 equiv.) was
added and after 15 min the precipitate was filtered off, washed
with a small portion of Et2O (2 mL) and dried under high
vacuum. Yield: 59 mg, 61%. M.p.: 170–175 °C (decompo-
sition); 1H-NMR (500.23 MHz, CDCl3, 298 K): δ = 4.59 (d, J =
6.4 Hz, 1H, NHtrop), 4.67 (d, J = 8.7 Hz, 2H, CHbenzyl), 4.80 (d,
J = 9.2 Hz, 2H, CHolef), 4.87 (d, J = 9.4 Hz, 2H, CHolef), 6.64
(d, J = 7.3 Hz, 2H, CHar, trop), 6.75 (t, J = 7.33 Hz, 2H, CHar, trop),
6.77 (d, J = 8.3 Hz, 2H, CHar, trop), 6.83 (t, J = 7.1 Hz, 2H,
CHar, trop), 7.07–7.10 (m, 2H, CHar, trop), 7.16 (d, J = 7.3 Hz,
2H, CHar, trop), 7.19–7.21 (m, 4H, CHar, trop), 7.56 (m, 13H,
CHar, phosphane, CHar, PhNHO, NHPhNHO), 8.02 (br, 6H, CHar, phosphane),
8.20 (d, J = 7.6 Hz, 1H, CHar, PhNHO), 8.35 (d, J = 8.0 Hz,
1H, CHar, PhNHO); 13C{1H}-NMR (125.78 MHz, CDCl3,
298 K): δ = 67.4 (d, J = 12.0 Hz, 2C, CHolef), 69.7 (d, J = 7.4 Hz,
2C, CHolef), 73.0 (s, 2C, CHbenzyl), 122.8 (s, 1C, CHar, PhNHO),
125.5 (s, 2C, CHar, trop), 125.9 (m, 3C, CHar, trop, CHar, PhNHO),
125.9 (s, 2C, CHar, trop), 127.4 (s, 2C, CHar, trop), 127.7 (s, 2C,
CHar, trop), 128.5 (s, 2C, CHar, trop), 128.6 (s, 2C, CHar, trop),
128.7 (d, J = 9.6 Hz, 6C, CHar, phosphane), 129.1 (s, 1C, CHar, PhNHO),
129.2 (s, 1C, CHar, PhNHO), 129.5 (s, 2C, CHar, trop), 129.6
(s, 2C, CHar, trop), 130.0 (s, 1C, CHar, PhNHO), 130.9 (s, 3C,
1
Cquat, trop), 138.0 (d, JPC = 24.7 Hz, Cquat, phosphine), 142.0
(d, J = 4.1 Hz, 2C, Cquat, trop), 144.5 (s, 1C, Cquat, azoxybenzene);
31P{1H}-NMR (161.98 MHz, [D8]THF, 273 K) δ = 7.9 (d, 1JRhP
1
= 118.8 Hz); H, 103Rh-NMR (15.81 MHz, [D8]THF, 273 K):
δ = −6508 (d, 1JPRh = 118.8 Hz); ATR IR (ν in cm−1): 3199 (w),
3039 (w), 2953 (w), 1598 (w), 1569 (w), 1472 (m), 1435 (m),
1413 (w), 1396 (w), 1324 (w), 1300 (w), 1258 (w), 1216 (w),
1188 (w), 1159 (w), 1119 (w), 1088 (w), 1069 (m), 1025 (m),
999 (w), 971 (w), 925 (w), 906 (w), 859 (w), 810 (m), 763 (m),
745 (s), 698 (s), 684 (s), 618 (w).
Miscellaneous reactions
To a solution of [Rh(trop2N)(PPh3)] (1) (10 mg, 13 μmol,
1 equiv.) in THF (0.5 mL) was added nitrosobenzene (14 mg,
0.13 mmol, 10 equiv.). The solution turned dark red. 31P{1H}-
NMR (202.50 MHz, [H8]THF, 298 K) δ = 25.7 (s, OPPh3).
[RhH(trop2NH)(PPh3)] (3) was generated in situ by reacting a
solution of [Rh(trop2N)(PPh3)] (1) (10 mg, 13 μmol, 1 equiv.) in
THF (0.5 mL) with hydrogen gas. To this solution nitrosoben-
zene (2.1 mg, 20 μmol, 1.5 equiv.) was added. After a short reac-
tion time (less than 10 s) the solution turned dark yellow and a
precipitate formed. 31P{1H}-NMR (101.25 MHz, [H8]THF,
298 K) δ = 24.6 (s, OPPh3), 39.9 (d, 1JRhP = 134.9, 4).
1
CHar, phosphane), 131.1 (d, JPC = 45.6 Hz, 3C, Cquat, phosphane),
132.0 (s, 1C, Cquat, PhNHO), 134.6 (s, 2C, Cquat, trop), 134.7 (s, 2C,
Cquat, trop), 135.1 (d, J = 8.9 Hz, 6C, CHar, phosphane) 136.4
(s, 2C, Cquat, trop), 139.8 (s, 2C, Cquat, trop); 31P{1H}-NMR
1
(202.50 MHz, CDCl3, 298 K) δ = 43.1 (d, JRhP = 135.0 Hz);
1H, 103Rh-NMR (15.81 MHz, CDCl3, 298 K): δ = −7147 (d,
1JPRh = 135.0 Hz); ATR IR (ν in cm−1): 3147 (w), 3044 (w),
2848 (w), 1719 (w), 1636 (w), 159 (w), 1474 (m), 1435 (m),
1403 (w), 1341 (w), 1297 (w), 1258 (w), 1223 (w), 1186 (w),
1157 (w), 1114 (w), 1092 (m), 1064 (w), 1042 (w), 1024 (w),
998 (w), 984 (m), 936 (w), 887 (w), 879 (w), 856 (w), 840 (w),
825 (w), 801 (w), 742 (s), 714 (w), 699 (s) 683 (s), 618 (m).
A suspension of [Rh(trop2NH)(PPh3)(PhNHO)] (4) (5.0 mg,
5.7 μmol) in THF (0.5 mL) was treated overnight with hydrogen
14144 | Dalton Trans., 2012, 41, 14137–14145
This journal is © The Royal Society of Chemistry 2012