Regioselective ortho-Metallation of 2-Diphenylphosphanylpyridine
IR (Nujol): ν˜ ϭ 3060 w, 3029 w, (C-H); 1581 w (CϭC); 1538 m (CoCϭC)
cmϪ1. Ϫ 1H NMR (500 MHz, [D8]THF, 296 K): δ ϭ 0.88 (d, 2JP,H ϭ 6.2 Hz,
9 H, PCH3), 1.20 (tЈ, Η2JP,H
ϩ
4JP,HΗ ϭ 4.4 Hz, 18 H, PCH3), 3.20 (m, 2 H,
OCH2), 3.49 (m, 2 H, OCH2), 5.72 (s, 1 H, CHO2), 7.07 (d, 3JH,H ϭ 7.4 Hz,
3
2 H, CH), 7.09Ϫ7.15 (m, 6 H, CH), 7.24 (t, JH,H ϭ 7.0 Hz, 1 H, CH), 8.03
(t, 3JH,H ϭ 7.5 Hz, 4 H, CH) ppm. Ϫ 13C{1H} NMR (125.7 MHz, [D8]THF,
296 K): δ ϭ 23.5 Ϫ 23.8 (m, PCH3(eq)), 23.9 Ϫ 24.1 (m, PCH3(ax)), 64.9 (s,
4
3
C-O), 101.1 (d, JP,C ϭ 6.2 Hz, OCO), 118.6 (m, CH), 128.3 (d, JP,C
ϭ
7.8 Hz, CH), 128.8 (s, CH), 129.6 (d, 2JP,C ϭ 12.9 Hz, CH), 130.8 (d, 4JP,C ϭ
2
4.5 Hz, CH), 133.2 (d, JP,C ϭ 13.5 Hz, CH), 139.2 (m, C), 139.8 (m, C),
1
153.7 (d, JP,C ϭ 18.7 Hz, C), 171.1 (m, CoC) ppm. Ϫ 31P{1H} NMR
2
(202 MHz, [D8]THF, 233 K): δ ϭ Ϫ19.5 (dt, JP,P ϭ 86 and 71 Hz, 1 P,
2
2
PPh2), 2.4 (dd, JP,P ϭ 86 and 44 Hz, 2 P, PCH3), 27.7 (dt, JP,P ϭ 71 and
Scheme 3. Sterically hindered rotation in regioselective ortho-
metallation
44 Hz, 1 P, PCH3) ppm.
Iodo-methyl-(2-diphenylphosphanyl)-3-phenyl-(1,3-
dioxalane-2-yl)-C,P)bis(trimethylphosphane)cobalt (2)
donating or withdrawing substituents show the same re-
gioselectivity).
A solution of 1 (810 mg, 1.30 mmol) in 30 ml THF was combined
We propose for every monosubstituted 2-diphenylphos-
with excess iodomethane (0.16 mL, 425 mg, 3.00 mmol) in THF
phanylaryl-ligand a high regioselectivity, as long as a sub- (50 mL) at Ϫ70 °C. The solution was allowed to warm to ambient
temperature and within 4 h the mixture took on a light-brown color
and became turbid. After 15 h at 20 °C, the volatiles were removed
in vacuo and the brown solid was extracted with a mixture of
80 mL diethyl ether / pentane (1:1). On storage of the extract at
4 °C, orange-brown crystals were obtained. Yield 340 mg (38 %);
m.p. 123Ϫ125 °C. Ϫ (dec.). Ϫ Anal calc. for C28H39CoIO2P3
(686.38): calcd. C 49.00, H 5.73, P 13.54; found C 49.37, H 6.12,
P 14.01 %.
stituent is not incorporated in the coordination of the co-
balt center. We suggest that these conclusions will prove
general at least for Co(CH3)(PMe3)4. Computational work
is in progress to test this proposal.
Experimental Section
IR (Nujol): ν˜ ϭ 3051 w, (C-H); 1581 w (CϭC); 1535 m (CoCϭC) 1157 m (δ
General Procedures and Materials: Standard vacuum techniques
were used in manipulations of volatile and air-sensitive materials.
Literature methods were used in the preparation of 2-diphenyl-
phosphanylpyridine [18], and (2-(2-diphenylphosphanyl)phenyl)-
1,3-dioxalane [19] and methyltetrakis-(trimethylphosphane)co-
balt(I) [20]. The other chemicals were used as purchased. Infrared
spectra (4000Ϫ400 cmϪ1), as obtained from Nujol mulls between
KBr disks, were recorded on a Nicolet 5700. 1H, 13C, and 31P NMR
(500, 300, 75, and 121 MHz, respectively) spectra were recorded on
a Bruker DRX 500 and Avance 300 spectrometer. 13C{1H} and
31P{1H} NMR resonances were obtained with broadband proton
decoupling. Elemental analyses were carried out at Kolbe Micro-
analytical Laboratory, Mülheim/Ruhr (Germany) and on an
Elementar Vario EL III. Melting points were measured in
capillaries sealed under argon and are uncorrected. CCDC-678959
(for 1), CCDC-686612 (for 3), CCDC-678958 (for 5) and CCDC-
678957 (for 6) contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
3
CoCH3) cmϪ1. Ϫ 1H NMR (500 MHz, [D8]THF): δ ϭ 0.49 (dt, JP,H
ϭ
9.1 Hz, 3JP,H ϭ 1.7 Hz, 3 H, CoCH3), 1.05 (tЈ, Η2JP,H ϩ 4JP,HΗ ϭ 3.7 Hz, 18 H,
PCH3), 3.18 (s(br), 2 H, OCH2), 3.44 (s(br), 2 H, OCH2), 5.64 (s, 1 H,
3
CHO2), 7.01 (d, JH,H ϭ 7.5 Hz, 2 H, CH), 7.12Ϫ7.17 (m, 6 H, CH), 7.24
3
4
3
(dt, JH,H ϭ 7.0 Hz, JH,H ϭ 0.7 Hz, 1 H, CH), 8.03 (dt, JH,H ϭ 7.5 Hz,
4JH,H ϭ 0.6 Hz, 4 H, CH) ppm. Ϫ 13C{1H} NMR (125.5 MHz, [D8]THF):
δ ϭ 15.2 (tЈ, Η1JP,C ϩ 3JP,CΗ ϭ 26.5 Hz, PCH3), 63.7 (s, C-O), 98.9 (d, 4JP,C
ϭ
3
7.3 Hz, OCO), 118.4 (m, CH), 128.2 (d, JP,C ϭ 8.0 Hz, CH), 128.8 (s, CH),
2
1
129.9 (d, JP,C ϭ 11.9 Hz, CH), 130.8 (s, CH), 133.2 (d, JP,C ϭ 13.5 Hz,
CH), 138.2 (s, C), 139.8 (s, C), 151.5 (d, 1JP,C ϭ 20.1 Hz, C), 169.1 (m, CoC)
ppm. Ϫ 31P{1H} NMR (202 MHz, [D8]THF, 233 K): δ ϭ 11.6 (d, JP,P
ϭ
2
2
26.5 Hz, 2 P, PMe3), Ϫ34.4 (t, JP,P ϭ 26.5 Hz, 1 P, PPh2) ppm.
(2-Diphenylphosphanyl)-3-benzoyl-(1,3-dioxalane-2-yl)-
C,P)(carbonyl)bis(trimethylphosphane)cobalt (3)
A sample of 1 (920 mg, 1.48 mmol) in 70 mL of pentane was kept
stirring under 1 bar of carbon monoxide for 16 h during which time
the color of the mixture turned from red to orange. The volatiles
were removed in vacuo, and the solid residue was extracted with
two 50 mL portions of diethyl ether. Crystallization at 4 °C fur-
nishes orange-red rhombic crystals of 3. Yield 658 mg (74 %); m.p.
152Ϫ154 °C (dec.). Ϫ Anal calc. for C29H36CoO4P3 (600.4): calcd.
C 58.01, H 6.04, P 15.48; found C 57.88, H 5.56, P 15.71 %.
(2-Diphenylphosphanyl)-3-phenyl-(1,3-dioxalane-2-yl)-
C,P)tris(trimethylphosphane)cobalt (1)
IR (Nujol): ν˜ ϭ 1854 vs (CϵO), 1582 m (CϭC), 1538 w (CoCϭC) cmϪ1. Ϫ
1H NMR (500 MHz, [D8]THF): δ ϭ 1.15 (tЈ, Η2JP,H
ϩ
4JP,HΗ ϭ 7.2 Hz, 18 H,
3
3
2
PCH3), 3.12 (ddd, JH,H ϭ 7.5 Hz, JH,H ϭ 6.1 Hz, JH,H ϭ 3.6 Hz, 2 H,
3
3
2
2-(2-Diphenylphosphanyl)phenyl-1,3-dioxalane (576 mg, 1.72 mmol)
in 50 mL of diethyl ether was combined at Ϫ70 °C with
[CoCH3(PMe3)4] (650 mg, 1.72 mmol) in 30 mL of diethyl ether.
The reaction was accompanied by the evolution of a gas. After
keeping the red-brown mixture at 20 °C for 16 h, the volatiles were
removed in vacuo and the solid residue was extracted with two
70 mL portions of pentane. When the solution was kept at Ϫ27 °C,
dark-red crystals of 1 were obtained. Yield 852 mg (81 %); m.p.
111Ϫ113 °C (dec.). Ϫ Anal calc. for C30H45CoO2P4 (620.5): calcd.
C 58.07, H 7.31, P 19.97; found C 58.78, H 7.61, P 20.42 %.
OCH2), 3.53 (ddd, JH,H ϭ 7.5 Hz, JH,H ϭ 6.1 Hz, JH,H ϭ 3.6 Hz, 2 H,
OCH2), 5.94 (s, 1 H, CHO2), 7.12 (dd, 3JH,3H ϭ 7.2 Hz, 3JH,H ϭ 7.0 Hz, 2 H,
4
CH), 7.17Ϫ7.21 (m, 4 H, CH), 7.41 (dt, JH,H ϭ 7.5 Hz, JH,H ϭ 2.7 Hz,
3
4
1 H, CH), 7.90 Ϫ 7.96 (m, 5 H, CH), 8.17 (dd, JH,H ϭ 7.5 Hz, JH,H
ϭ
0.9 Hz, 1 H, CH) ppm. Ϫ 13C{1H} NMR (125.4 MHz, [D8]THF): δ ϭ 18.3
1
3
3
(dt, JP,C ϭ 12.8 Hz, JP,C ϭ 4.5 Hz, PCH3), 63.7 (s, C-O), 100.4 (d, JP,C
1.5 Hz, OCO), 121.1 (d, JP,C ϭ 20.3 Hz, CH), 127.06 (s, CH), 127.10 (s,
ϭ
1
4
2
CH), 128.6 (d, JP,C ϭ 3.0 Hz, CH), 130.1 (d, JP,C ϭ 12.8 Hz, CH), 130.3
(s, CH), 138.2 (td, 1JP,C ϭ 27.9 Hz, JP,C ϭ 3.7 Hz, C), 138.5 (s, C), 139.3 (s,
4
C), 158.5 (s, C), 222.1 (m, CϵO), 260.2 (m, CoCϭO) ppm. Ϫ 31P{1H} NMR
2
(202 MHz, [D8]THF, 233 K): δ ϭ 14.7 (d, JP,P ϭ 72.2 Hz, 2 P, PMe3), 90.3
2
(t, JP,P ϭ 72.2 Hz, 1 P, PPh2) ppm.
Z. Anorg. Allg. Chem. 2009, 99Ϫ105
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
103