Organometallics
Article
chlorobenzonitrile, Ni(SIMes)[P(OPh) ](C H CN)Cl (9),
(ca. 1.5 mL) and layered with pentane (10 mL) and allowed to
recrystallize at −28 °C. A mixture of white powder and red crystals
are obtained, the supernatant solution was decanted, and 3 mL of
pentane was added and swirled to suspend the white precipitate and
then decanted. This process was repeated until the white precipitate
was removed. Complex 2 was obtained as bright red crystals (100 mg,
3
6
4
was also isolated and characterized. Currently we are
investigating further ligand modifications of this family of
mixed nickel NHC phosphite complexes. Additional studies
are being conducted on the reactivity of Ni(II) complex 9.
0
.1 mmol, 54%). Crystals suitable for X-ray diffraction were obtained
EXPERIMENTAL SECTION
by slow diffusion of pentane into a concentrated solution of 2 in
■
1
benzene at −28 °C. H NMR (600 MHz, C D ) δ 6.97−6.88 (m,
2
2
General Information. All reactions were performed with standard
Schlenk (nitrogen) or glovebox (Innovative Technology, argon)
techniques unless otherwise specified. THF, diethyl ether, pentane,
toluene, DCM, and hexane were purged with argon and passed
through active alumina columns (Innovative Technology, Inert) and
stored over activated molecular sieves in argon filled glove boxes. All
other reagents were used as received unless otherwise noted.
Deuterated solvents for NMR analysis were degassed with nitrogen
and stored in the glovebox over activated molecular sieves. The N-
heterocyclic carbenes IMes and SIMes were prepared from the
6
6
4H), 6.85−6.77 (m, 6H), 6.73 (s, 4H), 6.33 (s, 2H), 2.30 (s, 12H),
13
.15 (s, 6H) ppm. C NMR (151 MHz, C D ) δ 198.4 (t, J = 32.0
6
6
CP
Hz), 153.0, 137.6, 137.3, 136.1, 129.2, 128.7, 128.0, 122.2, 121.3,
3
1
1
20.9, 20.9, 17.8 ppm. P NMR (243 MHz, C D ) δ 120.9 ppm.
6 6
Anal. Calcd for C H N O P Ni: C, 69.60; H, 5.53; N, 2.85. Found:
57 54
2
6 2
C, 69.42; H, 5.42; N, 2.79.
Ni(SIMes)[P(O-o-tol)3]2 (3). In a glovebox, nickel tris(tri-o-
tolylphosphite) (200 mg, 0.18 mmol) and SIMes (110 mg, 0.36
mmol) were placed into a Schlenk flask. Toluene (15 mL) was added
and the vessel sealed and removed from the glovebox and heated at
65
corresponding NHC·HBF4 salts following literature procedures.
1
00 °C for 15 min. The mixture was cooled to room temperature and
Ni[P(OPh)3]4 and Ni[P(O-o-tol) ] were prepared according
3
3
38
the solvent was completely removed under a high vacuum (cold trap).
The flask was then returned to the glovebox, and the red oil was
dissolved in THF (ca. 2 mL) and filtered through a short plug of
Celite; the residue was further washed with THF (2 × 2 mL). The
solution was concentrated to a minimal volume of THF (ca. 1.5 mL)
and layered with pentane (10 mL) and allowed to recrystallize at −28
reported procedures.
NMR spectra were recorded with Bruker Avance IIIHD600 or
Bruker Avance IIIHD500 instruments. Chemical shifts are displayed
1
13
in ppm. H and C NMR were referenced to the residual protiated
solvent, 31P NMR were referenced to external H PO4 standard.
3
Multiplicities are abbreviated as the following: singlet (s), doublet (d),
triplet (t), quartet (q), multiplet (m), and broad (b). High resolution
accurate mass data mass spectra were recorded on a Waters LCT
Premier XE instrument. Elemental analysis was performed at London
Metropolitan University (UK) by Dr. Stephen Boyer. Flash column
chromatography was performed on silica gel (Davisil, particle size
°
C. Complex 3 was obtained as bright red crystals (130 mg, 0.12
mmol, 67%). Crystals suitable for X-ray diffraction were obtained by
slow diffusion of pentane into a concentrated solution of 3 in benzene
at −28 °C. H NMR (600 MHz, C D ) δ 7.13 (d, J = 7.6 Hz, 6H),
1
6
6
6
6
1
.90−6.84 (m, 6H), 6.78 (d, J = 0.4 Hz, 4H), 6.74 (td, J = 7.3, 1.5 Hz,
H), 6.72−6.68 (m, 6H), 3.33 (s, 4H), 2.53 (s, 12H), 2.17 (s, 6H),
4
0−63 μm, Merck) and eluted with petroleum ether/ethyl acetate.
1
3
.96 (s, 18H) ppm. C NMR (126 MHz, C D ) δ 222.4 (t, J = 32.9
Preparative thin layer chromatography (PTLC) was performed with
in-house prepared plates (20 × 20 × 0.1 cm) using silica gel 60 PF254
containing gypsum (Merck).
6
6
CP
Hz), 151.5, 137.9, 136.9, 136.8, 130.3, 129.6, 128.8, 128.0, 126.1,
3
1
122.0, 120.1, 50.7, 20.9, 18.3, 16.7 ppm. P NMR (243 MHz, C
δ 120.9 ppm. Anal. Calcd for C63 Ni: C, 70.73; H, 6.41; N,
2.62. Found: C, 70.84; H, 6.33; N, 2.65.
Ni(IMes)[P(O-o-tol) (4). In a glovebox, nickel tris(tri-o-
D )
6
6
Ni(SIMes)[P(OPh)3]2 (1). In a glovebox, nickel tetrakis-
triphenylphosphite) (429 mg, 0.33 mmol) and SIMes (204 mg,
.66 mmol) were placed into a Schlenk flask. Toluene (20 mL) was
H N O P
68 2 6 2
(
0
]
3 2
added and the vessel sealed and removed from the glovebox and
heated at 110 °C for 40 min. The mixture was then cooled to room
temperature, and the solvent was completely removed under a high
vacuum (cold trap). The flask was then returned to the glovebox and
the red oil was dissolved in THF (ca. 2 mL), filtered through a short
plug of Celite, and the residue was further washed with THF (2 × 2
mL). The solution was concentrated in a minimal volume of THF (ca.
tolylphosphite) (200 mg, 0.18 mmol) and IMes (109 mg, 0.36
mmol) were placed into a Schlenk flask. Toluene (15 mL) was added
and the vessel sealed and removed from the glovebox and heated at
100 °C for 30 min. The mixture was cooled to room temperature and
the solvent was completely removed under a high vacuum (cold trap).
The flask was then returned to the glovebox, and the red oil was
dissolved in THF (ca. 2 mL) and filtered through a short plug of
Celite; the residue was further washed with THF (2 × 2 mL). The
solution was concentrated to a minimal volume of THF (ca. 1.5 mL)
and layered with pentane (10 mL) and allowed to recrystallize at −28
°C. Complex 4 was obtained as bright red crystals (109 mg, 0.10
mmol, 57%). Crystals suitable for X-ray diffraction were obtained by
1
.5 mL) and layered with pentane (10 mL) and allowed to crystallize
at −28 °C. A mixture of white powder and red crystals was obtained,
the supernatant solution was decanted, and 3 mL of pentane was
added and swirled to suspend the white precipitate that was then
decanted. This process was repeated until the white precipitate was
removed. Complex 1 was obtained as bright red crystals (256 mg, 0.3
mmol, 79%). Crystals suitable for X-ray diffraction were obtained by
slow diffusion of pentane into a concentrated solution of 1 in benzene
slow diffusion of pentane into a concentrated solution of 4 in benzene
1
at −28 °C. H NMR (600 MHz, C
D
6
) δ 7.27−7.19 (m, 6H), 6.91−
6
6.84 (m, 6H), 6.78−6.67 (m, 16H), 6.33 (s, 2H), 2.33 (s, 12H), 2.15
(s, 6H), 1.94 (s, 18H). C NMR (151 MHz, C
1
13
at −28 °C. H NMR (600 MHz, C D ) δ 6.95−6.90 (m, 12H), 6.87
D ) δ 198.7 (t, JCP =
6 6
6
6
(
d, J = 7.5 Hz, 12H), 6.80 (t, J = 7.2 Hz, 6H), 6.76 (s, 4H), 3.33 (s,
H), 2.50 (s, 12H), 2.17 (s, 6H) ppm. C NMR (151 MHz, C D ) δ
22.2 (t, JCP = 32.0 Hz), 152.3, 137.0, 136.4, 136.0, 128.9, 128.1,
27.4, 121.6, 120.3, 49.9, 20.2, 17.2 ppm. P NMR (243 MHz, C D )
33.2 Hz), 151.9, 138.1, 137.9, 136.4, 130.7, 129.6, 129.2, 128.4, 126.5,
1
3
31
4
2
1
122.3, 121.9, 120.4, 21.2, 18.6, 17.0 ppm. P NMR (243 MHz, C
δ 120.2 ppm. Anal. Calcd for C63 Ni: C, 70.86; H, 6.23; N,
2.62. Found: C, 70.69; H, 6.46; N, 2.62.
Ni(IMes)[P(OPh) ](C CHO) (5). Ni(SIMes)[P(OPh)
6 6
D )
6
6
H N O P
66 2 6 2
3
1
6
6
δ 121.6 ppm. Anal. Calcd for C H N O P Ni: C, 69.45; H, 5.73; N,
3
6
H
2
F
3
] (1) (20
3 2
5
7
56
2
6 2
2
.84. Found: C, 69.30; H, 5.79; N, 2.77.
Ni(IMes)[P(OPh)3]2 (2). In a glovebox, nickel tetrakis-
triphenylphosphite) (244 mg, 0.19 mmol) and IMes (115 mg,
.38 mmol) were placed into a Schlenk flask. Toluene (15 mL) was
mg, 20 μmol) was dissolved in THF (0.5 mL) followed by addition of
3,4,5-trifluorobenzaldhyde (2.5 μL, 20 μmol). The solution turned
from bright red to yellow within 2 min and the mixture was allowed to
stir for a further 10 min. The ensuing mixture was concentrated under
reduced pressure to afford a yellow solid, which was dissolved in a
small portion of benzene (ca. 0.5 mL), layered with pentane and
cooled to −28 °C. Filtration provided title complex 5 (49.6 mg, 0.06
mmol, 72%) as yellow needles. Crystals suitable for X-ray diffraction
were obtained by slow diffusion of pentane into a concentrated
(
0
added and the vessel sealed and removed from the glovebox and
heated at 120 °C for 50 min. The mixture was then cooled to room
temperature and the solvent was completely removed under a high
vacuum (cold trap). The flask was then returned to the glovebox, and
the red oil was dissolved in THF (ca. 2 mL) and filtered through a
short plug of Celite; the residue was further washed with THF (2 × 2
mL). The solution was concentrated to a minimal volume of THF
1
solution of 5 in benzene at −28 °C. H NMR (600 MHz, C D ) δ
6
6
7.03 (br s, 2H), 6.97 (s, 2H), 6.95−6.90 (m, 6H), 6.83 (t, J = 7.4 Hz,
H
Organometallics XXXX, XXX, XXX−XXX