3994 Organometallics, Vol. 25, No. 16, 2006
Szesni et al.
silica gel used for chromatography (Baker, silica for flash chro-
matography) was nitrogen-saturated. The reported yields refer to
analytically pure compounds and are not optimized. Instrumenta-
tion: 1H and 13C spectra were recorded at 400 MHz (1H) and 100.5
MHz (13C) at ambient temperature. Chemical shifts are relative to
the residual solvent peaks. 2-Ethynyl pyrimidine,31 methyl(1-
phenylpro-2-ynylidene)amine,32 and the complexes 3a,b,33 4a,b,
5a,b, 6a,b, 8a,b,23 9a,b,34 and [M(CO)6]34 were prepared according
to literature procedures.
Preparation of Complexes 1 and 2. A solution of 3.1 mL of
n-BuLi (5 mmol, 1.6 M in n-hexane) was added at -80 °C dropwise
to a solution of 0.52 g (5 mmol) of 2-ethynylpyrimidine in 50 mL
of dry THF. The solution was stirred for 20 min at this temperature.
Then 50 mL of a 0.1 M solution of [(CO)5M(THF)] (M ) Cr, W)
in THF was added. The cooling bath was removed, and the brown
solution was stirred for 30 min at ambient temperature. The solvent
was removed in vacuo. The remaining oily residue was dissolved
in 50 mL of CH2Cl2, treated at 0 °C with 0.95 g (5 mmol) of [Et3O]-
BF4, and stirred for a further 60 min at this temperature. The
resulting deeply colored solution was filtered at -20 °C through a
5 cm layer of silica gel using CH2Cl2 as the eluant. The solvent
was removed in vacuo, and the residue was chromatographed at
-20 °C on silica gel using mixtures of pentane/CH2Cl2 as eluant.
The first violet fraction contained the binuclear complex 2a or 2b,
the following red one the mononuclear complex 1a or 1b.
ꢀ) 525 (4.001) [CH2Cl2]. Anal. Calcd for C18H8N2O10Cr2 (516.26):
C, 41.88; H, 1.56; N, 5.43. Found: C, 41.94; H, 1.62; N, 5.56.
Pentacarbonyl(N-ethyl-N′-pentacarbonyltungsten-3-hydropy-
rimidine-1,2-propadienylidene)tungsten (2b): 0.66 g (17%, based
on W(CO)6), violet oil. IR (THF): ν(CO) 2086 vw, 2072 w, 1940
1
s, 1922 vs, 1904 sh, 1898 sh; ν(CCC) 1986 m cm-1. H NMR
(400 MHz, [d6]-acetone): δ 1.65 (t, 3JHH ) 7.1 Hz, 3H, CH3), 4.76
(q, 3JHH ) 7.2 Hz, 2H, NCH2), 7.54 (t, 3JHH ) 5.8 Hz, 1H, PyrH),
9.18 (dd, 3JHH ) 5.9 Hz, 4JHH ) 2.4 Hz, 1H, PyrH), 9.77 (dd, 3JHH
4
) 5.8 Hz, JHH ) 2.2 Hz, 1H, PyrH). 13C NMR (100 MHz, [d6]-
acetone): δ 13.9 (CH3), 57.5 (NCH2), 117.5 (Câ), 116.0, 154.1,
170.5 (3 PyrC), 142.1 (Cγ), 197.4 (cis-CO), 198.8 (cis-CO), 200.1
(CR), 203.2 (trans-CO), 203.9 (trans-CO). MS (FAB): m/z (%)
780 (7) [M+], 724 (63) [(M - 2CO)+], 396 (39) [(M - 3CO)+],
668 (41) [(M - 4CO)+], 640 (42) [(M - 5CO)+], 456 (51) [(M -
W(CO)5+], 428 (100) [(M - W(CO)5 - CO+], 316 (40) [(M -
W(CO)5 -5CO)+]. UV/vis: λmax (log ꢀ) 522 (3.971) [CH2Cl2].
Anal. Calcd for C18H8N2O10W2 (779.97): C, 27.72; H, 1.03; N,
3.59. Found: C, 27.78; H, 1.19; N, 3.62.
Reaction of 1a with [(CO)5Cr(THF)] or 2b with [(CO)5W-
(THF)]. [(CO)5Cr(THF)] (10 mL of a 0.1 M solution in THF) {[of
[(CO)5W(THF)]: 25 mL of a 0.1 M solution in THF} was added
to a solution of 65 mg (0.2 mmol) of 1a [103 mg (0.2 mmol) of
2a] in 2 mL of THF. The solution was stirred for 6 h at ambient
temperature. The solvent was removed in vacuo and the residue
filtered over a short layer of silica using CH2Cl2 as the eluant. The
violet band, containing the binuclear complexes 2a (42 mg; 0.08
mmol; 41%) and 2b (150 mg; 0.19 mmol; 96%), was collected.
Reactions of 2a or 2b with Et3N, PPh3, or air. A solution of
100 mg (0.2 mmol) of 2a [1.56 g (0.2 mmol) of 2b] in 10 mL of
CH2Cl2 was treated with 2 mmol of Et3N or PPh3 and stirred for
120 min at ambient temperature. Alternatively, the solutions of the
binuclear complexes 2a and 2b were exposed to air for the same
period of time. The solvent was removed in vacuo and the residue
filtered over a short layer of silica using CH2Cl2 as the eluant. The
first yellow fraction contained the chromium complexes [(CO)5Cr-
L] (L ) NEt3,35 PPh3,36 CO; characterized by their IR spectra).
The following red band contained the mononuclear allenylidene
complex 1a (63 mg; 0.19 mmol; 97%) or 1b (88 mg; 0.19 mmol;
96%) in almost quantitative yield. When only a small excess of
Et3N or PPh3 (1.1 equiv) is used, the reaction proceeds slower and
the yields slightly decrease.
Reaction of 1a with [(CO)5W(THF)]. A solution of [(CO)5W-
(THF)] (30 mL, 0.1 M in THF) was added to 0.32 g (1 mmol) of
1a in 2 mL of THF. The solution was stirred for 3 h at ambient
temperature. The solvent was removed in vacuo and the residue
filtered over a short layer of silica using CH2Cl2 as the eluant. The
violet band was collected. Removal of the solvent in vacuo yielded
0.61 g (0.78 mmol; 78%) of the dinuclear complex 2b.
Pentacarbonyl[3-butyl(methyl)amino-3-phenyl-1,2-propadi-
enylidene]chromium (7a). A solution of n-BuLi (3.1 mL, 5 mmol,
1.6 M in n-nexane) was added at -80 °C dropwise to a solution of
0.52 g (5 mmol) of methyl(1-phenylpro-2-ynylidene)amine in 50
mL of dry THF. The solution was stirred for 20 min at -80 °C.
Then 50 mL of a solution of [(CO)5Cr(THF)] (0.1 M in THF) was
added. The cooling bath was removed, and the brown solution was
stirred for 30 min at ambient temperature. The solvent was removed
in vacuo. The remaining oily residue was dissolved in 50 mL of
CH2Cl2, treated at 0 °C with 2.22 g (10 mmol) of n-BuOTos, and
stirred for 16 h at ambient temperature. The resulting deep red
solution was filtered through a 5 cm layer of silica gel at -20 °C
using CH2Cl2 as the eluant. The solvent was removed in vacuo,
and the residue was chromatographed on silica gel at -20 °C using
Pentacarbonyl(N-ethyl-3-hydropyrimidine-1,2-propadien-
ylidene)chromium (1a): 0.70 g (43%, based on Cr(CO)6), red oil.
IR (THF): ν(CO) 2080 vw, 1931 vs, 1905 m; ν(CCC) 2008 m
1
3
cm-1. H NMR (400 MHz, [d6]-acetone): δ 1.54 (t, JHH ) 7.0
3
Hz, 3H, CH3), 4.62 (q, JHH ) 7.0 Hz, 2H, NCH2), 7.49 (m, 1H,
PyrH), 8.85 (m, 1H, PyrH), 8.92 (m, 1H, PyrH). 13C NMR (100
MHz, [d6]-acetone): δ 14.4 (CH3), 54.9 (NCH2), 113.4 (Câ), 117.1,
151.6, 164.8 (3 PyrC), 137.8 (Cγ), 188.7 (CR), 219.1 (cis-CO), 223.4
(trans-CO). MS (FAB): m/z (%) 324 (38) [M+], 296 (28) [(M -
CO)+], 268 (51) [(M - 2CO)+], 240 (33) [(M - 3CO)+], 212 (68)
[(M - 4CO)+], 184 (100) [(M - 5CO)+]. UV/vis: λmax (log ꢀ)
482 (4.124) [CH2Cl2]. C13H8N2O5Cr (324.26).
Pentacarbonyl(N-ethyl-3-hydropyrimidine-1,2-propadien-
ylidene)tungsten (1b): 0.82 g (36%, based on W(CO)6), red oil.
IR (THF): ν(CO) 2083 vw, 1926 vs, 1900 m; ν(CCC) 2009 m
1
3
cm-1. H NMR (400 MHz, [d6]-acetone): δ 1.55 (t, JHH ) 7.1
Hz, 3H, CH3), 4.62 (q, 3JHH ) 7.0 Hz, 2H, NCH2), 7.57 (dd, 3JHH
) 4.7 Hz, 3JHH ) 6.3 Hz, 1H, PyrH), 8.91 (m, 3JHH ) 6.3 Hz, 4JHH
) 2.3 Hz, 1H, PyrH), 8.96 (m, 3JHH ) 4.7 Hz, 4JHH ) 2.3 Hz, 1H,
PyrH). 13C NMR (100 MHz, [d6]-acetone): δ 14.4 (CH3), 55.0
(NCH2), 111.3 (Câ), 117.6, 151.8, 164.7 (3 PyrC), 142.6 (Cγ), 170.5
1
(CR), 198.2 (cis-CO, JWC ) 125.0 Hz), 202.6 (trans-CO). MS
(FAB): m/z (%) 456 (42) [M+], 400 (13) [(M - 2CO)+], 372 (33)
[(M - 3CO)+], 344 (72) [(M - 4CO)+], 316 (100) [(M - 5CO)+].
UV/vis: λmax (log ꢀ) 477 (4.131) [CH2Cl2]. C13H8N2O5W (456.11).
Pentacarbonyl(N-ethyl-N′-pentacarbonylchromium-3-hydro-
pyrimidine-1,2-propadienylidene)chromium (2a): 0.64 g (25%,
based on Cr(CO)6), violet oil. IR (THF): ν(CO) 2081 vw, 2068 w,
1943 s, 1929 vs, 1904 sh, 1900 sh; ν(CCC) 1991 m cm-1. 1H NMR
(400 MHz, [d6]-acetone): δ 1.63 (t, 3JHH ) 7.0 Hz, 3H, CH3), 4.73
3
(q, JHH ) 7.0 Hz, 2H, NCH2), 7.47 (m, 1H, PyrH), 9.05 (m, 1H,
PyrH), 9.56 (m, 1H, PyrH). 13C NMR (100 MHz, [d6]-acetone): δ
13.9 (CH3), 57.1 (NCH2), 119.2 (Câ), 114.8, 153.6, 169.8 (3 PyrC),
139.9 (Cγ), 214.4 (cis-CO), 214.6 (CR), 218.1 (cis-CO), 220.2
(trans-CO), 222.9 (trans-CO). MS (FAB): m/z (%) 516 (6) [M+],
460 (7) [(M - 2CO)+], 432 (8) [(M - 3CO)+], 324 (100) [(M -
Cr(CO)5+], 184 (34) [(M - Cr(CO)5 - 5CO+]. UV/vis: λmax (log
(31) Lottermoser, U.; Rademacher, P.; Mazik, M.; Kowski, K. Eur. J.
Org. Chem. 2005, 522.
(32) Schlegel, J.; Maas, G. Synthesis 1999, 100.
(35) Strohmeier, W.; Guttenberger, J. F.; Blumenthal, H.; Albert, G.
Chem. Ber. 1966, 99, 3419.
(33) Roth, G.; Fischer, H. Organometallics 1996, 15, 1139.
(34) Fischer, H.; Reindl, D.; Roth, G. Z. Naturforsch. 1994, 49b, 1207.
(36) Chalmers, A. A.; Lewis, J.; Whyman, R. J. Chem. Soc., Sect. A
1967, 11, 1817.