Inorganic Chemistry
Article
yellow semisolid turned to a crystalline solid after days in a capped vial
at room temperature. Yield: 0.5170 g, 95%. 1H NMR (400 MHz,
benzene-d6) δ = 6.91 (dd, J = 7.3, 8.3 Hz, 2 H), 6.26 (d, J = 8.3 Hz, 2
H), 6.01 (d, J = 7.3 Hz, 2 H), 2.11 (s, 6 H), 1.48 (s, 18 H); 13C NMR
(75 MHz, benzene-d6) δ = 172.1, 153.3, 140.7, 113.2, 107.3, 67.0, 33.2,
21.8; MS(EI) m/z 542 ([M]+), m/z 527 ([M − Me]+), m/z 471 ([M
− NtBu]+), m/z 414 ([M − NtBu − tBu ]+). Anal. Calcd for
WO2N4C20H30: N, 10.33; C, 44.29; H, 5.58. Found: N, 9.97; C, 44.53;
H, 5.66.
= 6.9, 9.1 Hz, 1 H), 6.38 (d, J = 9.1 Hz, 1 H), 6.28 (d, J = 8.2 Hz, 2 H),
6.03 (d, J = 7.4 Hz, 2 H), 5.47 (d, J = 6.9 Hz, 1 H), 2.14 (s, 6 H), 2.00
(s, 3 H), 1.47 (s, 18 H); 13C NMR (75 MHz, benzene-d6): δ = 172.0,
167.2, 153.5, 147.5, 141.5, 140.6, 116.6, 113.3, 107.5, 106.3, 66.7, 33.1,
22.0, 19.5; MS(EI) m/z 579 [M − HNtBu]+, m/z 523 [M − HNtBu,
−C3H8]+. Anal. Calcd for WO3N5C26H37: N, 10.75; C, 47.94; H, 5.72.
Found: N, 10.64; C, 48.03; H, 5.69.
(tert-Butylamido)(tert-butylimido)tris(3-methyl-2-pyridonate)-
tungsten(VI) (8). Precipitation of white and yellow solids from an
equilibrium mixture of pyridonate complex 4 and proligand 4L does
not produce a single isolable product. EIMS conducted on the
precipitated solids showed fragments corresponding to complex 4 and
a (tert-butylimido)tris(3-methyl-2-pyridonate)tungsten(VI) fragment.
Bis(tert-butylimido)bis((κ2-N,O)3-methyl-2-pyridonate)tungsten-
(VI) (4). Complex 1 (0.2357 g, 0.5011 mmol) was dissolved in 3 mL of
toluene and then added to a vial charged with 3-methyl-2-pyridone
(0.1110 g, 1.017 mmol) and a stir bar. The mixture was capped and
stirred for 2 h, resulting in a translucent yellow solution. The volatiles
were then removed under vacuum, and the resulting yellow semisolid
was dissolved in 4 mL of hexanes and filtered through a bed of Celite.
The volatiles were again removed under vacuum to yield a yellow
semisolid, which was recrystallized from minimal warm hexanes at −35
°C overnight and afforded a bright yellow powder. The mother liquor
was decanted, and the solids were dried under vacuum. Yield: 0.2065
1
The H NMR solution-phase spectrum suggested fluxional species,
1
which was confirmed by variable-temperature H NMR spectroscopy
1
experiments. H NMR 25 °C (400 MHz, toluene-d8) δ = 8.43 (br s),
8.06 (br s), 7.79 (d, J = 4.9 Hz), 7.76 (d, J = 4.9 Hz), 7.40 (d, J = 4.4
Hz), 6.87 (d, J = 7.3 Hz), 6.33−6.25 (m), 6.15 (dd, J = 5.4, 6.8 Hz),
6.02 (t, J = 6.1 Hz), 2.56 (br s), 1.99 (br s), 1.97 (s), 1.93 (s), 1.41 (s),
1.02 (s), 0.99 (s); MS(EI) m/z 579 [M − HNtBu]+, m/z 523 [M −
HNtBu, −C3H8]+
1
g, 76%. H NMR (300 MHz, benzene-d6) δ = 7.62 (d, J = 5.6 Hz, 2
Bis(tert-butylimido)chloro((κ2-N,O)N-(phenyl)pivalamidate)-
tungsten(VI) (9) and (tert-butylamido)(tert-butylimido)dichloro(N-
phenylpivalamidate)tungsten(VI) (10). Complex 5 (0.0509 g, 0.0750
mmol) was dissolved in 2 mL of toluene and added to a vial containing
a suspension of lutidinium hydrochloride (0.0114 g, 0.0794 mmol) in
2 mL of toluene in a glovebox. The yellow mixture was then stirred at
ambient temperature for 4 h. The volatiles were removed to yield pale
yellow solids. Hexanes (1.5 mL) was used to form a suspension of the
crude solids, which was filtered through a 2 cm plug of Celite, and the
volatiles were removed under vacuum. The filtration was conducted
again using 1.5 mL of hexanes and again filtering through a 2 cm plug
of Celite, and the volatiles were removed under vacuum. The solids
were dissolved in warm hexanes and recrystallized at room
temperature, colorless crystals formed overnight, the mother liquor
was decanted, and the crystals were dried under vacuum. This first
batch of crystalline material yielded small amounts (less than 0.01 g)
of predominately complex 10, contaminated with complex 9 and
proligand 5L. The mother liquor was decanted, concentrated, and then
left to recrystallize again for 2 days, yielding colorless crystalline rods
which were found to be complex 9 (0.0096 g) contaminated with
proligand 5L and small amounts of complex 10. The mother liquor
was decanted, and the crystals were dried in vacuum. Analytically pure
H), 6.82 (d, J = 7.0 Hz, 2 H), 6.06 (dd, J = 5.6, 7.0 Hz, 2 H), 1.94 (s, 6
H), 1.44 (s, 18 H); 13C NMR (75 MHz, benzene-d6) δ = 172.9, 141.6,
140.0, 123.0, 112.0, 67.2, 33.2, 15.1; MS(EI) m/z 542 ([M]+), m/z
527 ([M − Me]+), m/z 471 ([M − NtBu]+), m/z 414 ([M − NtBu −
tBu ]+). Anal. Calcd for WO2N4C20H30: N, 10.33; C, 44.29; H, 5.58.
Found: N, 10.31; C, 44.60; H, 5.43.
Bis(tert-butylimido)bis((κ2-N,O)N-phenylpivalamidate)tungsten-
(VI) (5). Complex 1 (0.2014 g, 0.4282 mmol) was dissolved in 4 mL of
toluene and then added to a vial charged with N-phenylpivalamide
(0.1473 g, 0.8310 mmol) and a stir bar. The resulting mixture was
capped and stirred for 2 h, resulting in a translucent yellow solution.
The volatiles were then removed under vacuum to give a pale yellow
crystalline solid. The solids were recrystallized from minimal warm
hexanes at ambient temperature overnight. Large yellow prisms
formed, the mother liquor was decanted, and a second batch of crystals
formed after the mother liquor was stored in a −35 °C freezer
overnight to yield smaller yellow prisms. The yellow crystals were
dried under vacuum. Yield: 0.2257 g, 80%. 1H NMR (400 MHz,
benzene-d6): δ = 7.26 (d, J = 6.1 Hz, 4 H), 7.05 (apparent t, J = 7.5
Hz, 4 H), 6.88 (t, J = 7.5 Hz, 2 H), 1.16 (br. s, 18 H), 1.15 ppm (br. s,
18 H); 13C NMR (101 MHz, benzene-d6) δ = 188.6, 149.4, 128.8,
127.9, 125.8, 66.5, 42.5, 32.7, 28.6; MS(EI) m/z 678 ([M − Me]+), m/
z 663 ([M − Me]+). Anal. Calcd for WO2N4C30H36: N, 8.25; C, 53.10;
H, 6.83. Found: N, 7.97; C, 53.27; H, 6.69.
1
material of complex 9 or 10 could not be obtained. H NMR spectra
of the recrystallized complexes 9 and 10 are shown in the Supporting
Bis(tert-butylimido)bis((κ2-N,O)N-(2,6-diisopropylphenyl)-
benzamidate)tungsten(VI) (6). Complex 1 (0.2348 g, 0.4992 mmol)
was dissolved in 4.5 mL of toluene and then added to a vial charged
with N-(2,6-diisopropylphenyl)benzamide (0.2846 g, 1.011 mmol)
and a stir bar. The mixture was capped and stirred for 2 h, resulting in
a translucent yellow solution. The volatiles were then removed under
vacuum, producing a yellow crystalline solid. The crystalline solids
were dissolved in 10 mL hexanes and filtered through a plug of Celite.
The volatiles were removed, leaving analytically pure yellow crystalline
Information (Figures S29 and S30, respectively). Spectroscopic
assignments for complex 9: H NMR (300 MHz, benzene-d6): δ =
1
7.08−6.95 (m, 4 H), 6.83 (tt, J = 2.1, 7.2 Hz, 1 H), 1.27 (s, 18 H), 0.91
(s, 9 H); MS(EI) m/z 537 [M]+, m/z 522 [M − Me]+. Spectroscopic
assignments for complex 10: 1H NMR (300 MHz, benzene-d6) δ ppm
1.02 (s, 9 H) 1.09 (s, 9 H) 1.16 (s, 9 H) 6.92 (tt, J = 7.4, 1.3 Hz, 1 H)
7.06−7.13 (m, 2 H) 7.59−7.65 (m, 2 H) 9.87 (br s, 1 H)
(tert-Butylimido)(chloro)bis((κ1-O)6-methyl-2-pyridonate)((κ2-
N,O)6-methyl-2-pyridonate)tungsten (11). Complex 3 (0.0360 g,
0.06638 mmol) was dissolved in 3 mL of toluene and added to a vial
containing solid lutidinium hydrochloride (0.0093 g, 0.06476 mmol)
in a glovebox. The mixture was stirred at ambient temperature for 4 h;
then 3 mL of hexanes was added and the stirring was halted. Off-white
solids precipitated, and the mother liquor was decanted. The solids
were washed with 2 mL of hexanes twice, and then the solids were
dried under vacuum. Yield: 0.0087 g. Analytically pure material of
1
solids. Yield: 0.3799 g, 86%. H NMR (300 MHz, benzene-d6) δ =
7.76 (dd, J = 1.5, 8.3 Hz, 4 H), 7.29−7.18 (m, 6 H), 6.94−6.79 (m, 6
H), 4.19 (spt, J = 6.9 Hz, 2 H), 3.90 (spt, J = 6.9 Hz, 2 H), 1.74 (d, J =
6.9 Hz, 6 H), 1.44 (d, J = 6.9 Hz, 6 H), 1.20 (s, 18 H), 1.15 (d, J = 6.9
Hz, 6 H), 0.96 (d, J = 6.9 Hz, 6 H); 13C NMR (75 MHz, benzene-d6)
δ = 178.5, 145.0, 144.0, 143.7, 134.1, 132.1, 130.4, 127.7, 125.4, 124.0,
67.6, 32.7, 28.5, 28.4, 26.5, 25.4, 24.0, 23.3; MS(EI) m/z 886 ([M]+),
m/z 871 ([M − Me]+.Anal. Calcd for WO2N4C20H30: N, 6.32; C,
62.30; H, 7.05. Found: N, 6.72; C, 62.67; H, 7.14.
1
complex 11 could not be obtained. The H NMR spectrum of the
recrystallized complex 11 is shown in the Supporting Information
1
(tert-Butylamido)(tert-butylimido)bis((κ1-O)6-methyl-2-
pyridonate)((κ2-N,O)6-methyl-2-pyridonate)tungsten(VI) (7). Solid
complex 7 was precipitated from an equilibrium mixture of pyridonate
complex 3 (0.0500 g, 0.09713 mmol) and proligand 3L (0.0106 g,
0.09220 mmol) in hexanes at −35 °C. The mother liquor was
decanted, and the solids were dried under reduced pressure. 1H NMR
(300 MHz, benzene-d6): δ = 6.93 (dd, J = 7.4, 8.2 Hz, 2 H), 6.79 (dd, J
(Figure S31). H NMR (300 MHz, benzene-d6) δ = 6.99 (t, J = 7.9
Hz, 3 H), 6.59−6.09 (m, 6 H), 2.54 (s, 9 H), 1.09 (s, 9 H); MS(EI)
m/z 579 [M − Cl]+, m/z 506 [M − ONC6H6]+, m/z 472 [M −
ONC6H6, −Cl]H+, m/z 450 [M − ONC6H6, −C3H8]+, m/z 414 [M −
ONC6H6, −Cl, −C3H8]+.
Bis(tert-butylimido)chloro((κ2-N,O)6-methyl-2-pyridonate)tung-
sten (12). Complex 3 (0.0637 g, 0.118 mmol) was dissolved in 1.5 mL
C
Inorg. Chem. XXXX, XXX, XXX−XXX