Organometallics
Article
The mixture was maintained under mild reflux (oil bath ∼65 °C)
for 1.5 h. By that time, the brown solution had turned amber. The
mixture was filtered and the solvent was removed under vacuum. The
remaining oily amber residue of 2 was dissolved in toluene (50 mL)
and PHPh2 in hexane (10%) (1.2 mL, 1.24 g, 0.66 mmol). The
reaction mixture was heated in an oil bath to ∼60 °C for 15 min, and
evaporation of the toluene under vacuum afforded an oily, amber
residue, which was chromatographed on deactivated alumina51 via
elution with hexane, followed by diethyl ether, to afford compound 4
along with PPh3 and 6 along with OPPh3, respectively. The solvent
was removed under reduced pressure; this gave compound 7 as an
orange-yellow powder in 10.6% yield (75.0 mg, 0.11 mmol).
Decomposition occurred at 160 °C without melting. Recrystallization
in CH2Cl2/pentane (1:3) at −5 °C afforded single crystals. IR (KBr,
cm−1): 3053 (s), 3002 (w), 2910 (m), 2853 (w), 2346 (w), 1964 (w,
br), 1899 (w, br), 1816 (w, br), 1664 (vw), 1620 (w), 1586 (m), 1483
(s), 1435 (vs), 1370 (m), 1313 (m), 1281 (m), 1186 (m), 1091 (s),
1027 (s), 1000 (m), 904 (s), 866 (s), 742 (vs), 696 (vs), 527 (vs), 508
(vs), 479 (w), 461 (w), 422 (m). MS: 680 (31.3) [M+], 645 (34.4),
585 (3.7), 548 (14.0), 495 (23.4), 460 (20.2), 418 (11.0), 391 (7.0),
380 (12.4), 363 (14.1), 307 (22.0), 289 (14.6), 262 (13.3), 183 (15.2),
154 (100.0), 136 (71.2). Anal. Calcd for C37H37ClP2Ru: C, 65.34, H,
5.48. Found: C, 65.47, H, 5.71.
Synthesis of [1-3,5-η-CH2CHCHCHN(Cy)]RuCl(PPh3)2 (7). A
THF solution (20 mL) of RuCl2(PPh3)3 (631.0 mg, 0.59 mmol) was
filtered, and Me3SnCH2CHCHCHN(Cy) (206.7 mg, 0.66 mmol),
previously dissolved in THF (1 mL), was added. The mixture was
stirred at room temperature for 6 h. The red-brown coloration of the
solution remained after all this time. The mixture was filtered, and the
solvent was removed under vacuum. The foamy red-brown residue was
washed with hexane (300 mL), giving an orange solution. The volume
was reduced to ∼150 mL and cooled overnight at −4 °C, to afford a
microcrystalline brick-red precipitate, which after filtration and drying
under vacuum gave 181.2 mg (0.22 mmol) (37% yield). Single crystals
were obtained from recrystallization with diethyl ether at −5 °C. Mp:
157−158 °C. IR (KBr, cm−1): 2672 (w, br), 2352 (m, br), 2270 (w,
br), 2160 (w, br), 1969 (m, br), 1896 (w, br), 1818 (m, br), 1734 (w),
1679 (w), 1589 (m), 1571 (w), 1481 (vs), 1433 (vs), 1393 (m), 1362
(w), 1336 (w), 1301 (m), 1260 (m), 1185 (s), 1153 (m), 1121 (m),
1089 (vs), 1029 (s), 988 (s, br), 929 (m), 905 (w), 845 (m), 744 (vs),
697 (vs). ESI + TOF: m/z 817.2411 error 0.064 ppm; DBE 25.5. Anal.
Calcd for C46H46NClP2Ru: C, 68.09; H, 5.71. Found: C, 67.94;
H, 5.90.
IR (KBr, cm−1): 2387 (w), 1923 (w, br), 1564 (w, br), 1502 (vw),
1482 (vs), 1434 (vs), 1385 (vw), 1308 (m), 1264 (vw), 1231 (vw),
1189 (m), 1152 (w), 1119 (w), 1090 (vs), 1066 (w), 1028 (w), 999
(w), 919 (m, br), 847 (vw), 806 (m, br), 745 (vs), 696 (vs), 521 (vs),
459 (m). ESI + TOF: m/z 695.1190 (-HCl); error ppm −1.60; RDB
24.5.
Synthesis of [1-3,5-η-CH2CHCHCHN(Cy)]RuCl(PPh3)(PHPh2)
(10). Compound 7 (90.0 mg, 0.11 mmol) was dissolved in THF
(15 mL), and PHPh2 (20.5 mg, 171.0 μL, 0.11 mmol) was added. The
reaction mixture was stirred for 45 min at room temperature. Filtration
of the yellow-orange solution and evaporation of the solvent under
vacuum afforded an ochre-yellow powder. This powder was treated
with pentane (2 × 10 mL) and then evaporated until dry, giving a
yellow-brown solid in 62% yield (50.0 mg, 0.07 mmol). Mp: 177−179 °C.
IR (KBr, cm−1): 3049 (s), 2925 (vs), 2853 (m), 2610 (m, br), 2367
(m, br), 2258 (w, br), 2155 (w, br), 1956 (m, br), 1814 (w, br), 1744
(w, br), 1597 (s, br), 1434 (vs), 1370 (w, br), 1308 (w, br), 1256 (w),
1186 (m), 1155 (w), 1119 (w), 1110 (s), 1070 (w), 1026 (m), 930
(w), 897 (m, br), 882 (w, br), 822 (vw), 801 (w), 698 (vs), 623 (vw).
ESI + TOF: m/z 700.1829; error ppm 0.0693; DBE 21.5. Anal.
Calcd for C40H42NClP2Ru: C, 65.34; H, 5.76. Found: C, 65.00;
H, 5.84.
Identification of Isomers [1-3,5-η-CH2CHCHCHN(t-Bu)]RuCl-
(PPh3)(PHPh2) (11a and 11b) and Compound [η3-CH2CHC-
HCHN(t-Bu)]RuCl(PHPh2)3 (11c). An NMR tube containing
compound 8 (40.0 mg, 0.05 mmol) and 0.6 mL of C6D6 was
prepared. One equivalent of PHPh2 (11.4 μL, 0.05 mmol) was added
into the NMR tube, followed by heating for 2.5 h in an oil bath
(70 °C), affording a mixture of isomers 11a and 11b. Addition of
2 equiv of PHPh2 (3.0 μL, 0.016 mmol) to an NMR tube with 8
(6.3 mg, 0.008 mmol) in C6D6, followed by heating for 10 h in an oil
bath (70 °C), led to the formation of the tentatively assigned
compound [η3-CH2CHCHCHN(t-Bu)]RuCl(PHPh2)3 (11c), along
with trans-RuCl2(PHPh2)4, OPPh3, OPHPh2, and unknown species
having chemical shifts at 27.04 (br) and 47.80 (s). Characterization of
1
11a, 11b, and 11c was carried out exclusively through H and 31P
NMR spectroscopy.
Synthesis of [η5-CH2C(Me)CHC(Me)O]RuCl(PPh3)2 (12) and
[η5-CH2C(Me)CHC(Me)O]RuH(PPh3)2 (13). The freshly prepared in
situ lemon-yellow solution of the lithium oxopentadienide salt (0.34
mmol) was slowly added dropwise to a cold (−110 °C), previously
filtered, THF solution (20 mL) of RuCl2(PPh3)3 (300.0 mg, 0.31
mmol). After the solution was warmed to room temperature and
stirred for 2 h, the volatiles were removed under vacuum. The oily
residue was extracted with hexane and filtered, and the solution was
evaporated. After chromatography (5 cm × 15 cm) using deactivated
alumina (5%)51 and elution with hexane/toluene (9:1), toluene/
CH2Cl2 (7:3), and CH2Cl2, free PPh3 and compounds 13 and 12 were
obtained, respectively. The orange solid 12 was obtained in 14% yield
(31.7 mg, 0.042 mmol), and the yellow solid 13 in 15% yield (35.5 mg,
0.049 mmol). Single crystals of 12 were obtained by recrystallization
through diffusion in THF/hexane at −5 °C (mp: 190−195 °C with
decomposition). IR (KBr, cm−1): 3053 (s), 2904 (w), 2863 (w), 2582
(w), 2347 (w, br), 1967 (w, br), 1905 (w, br), 1827 (w, br), 1583 (w,
sh), 1572 (w), 1482 (s), 1434 (vs), 1384 (m), 1350 (w), 1313 (w),
1277 (s), 1188 (s), 1155 (w), 1117 (s), 1088 (vs), 1029 (s), 1002 (w),
925 (s), 866 (s), 795 (w), 744 (vs), 696 (vs), 620 (s), 583 (m), 520
(vs, br), 466 (m), 424 (s). Anal. Calcd for C42H39OP2ClRu: C, 66.53;
H, 5.18. Found: C, 66.67; H, 5.39.
Synthesis of [1-3,5-η-CH2CHCHCHN(t-Bu)]RuCl(PPh3)2 (8). A
THF solution (30 mL) of RuCl2(PPh3)3 (880.0 mg, 0.91 mmol) was
filtered, and Me3SnCH2CHCHCHN(t-Bu) (290.0 mg, 1.01 mmol)
previously dissolved in THF (1 mL) was added. The reaction mixture
was kept under reflux for 2.5 h. The red-brown solution turned wine-
red after this time. The mixture was filtered, and the solvent was
removed under vacuum. The foamy wine-red residue was dissolved in
the minimum amount of THF, and thin-layer chromatography was
carried out with alumina plates and a mixture of hexane/diethyl ether
(1:1), leading to separation of pink and pale orange bands. The latter
was extracted with THF, and a second round of thin layer chro-
matography on alumina, with elution by the same ratio of solvents, led
to two bands, pale-pink and yellow. Extraction of the yellow band with
THF and removal of the solvent afforded a bright lemon-yellow solid,
which was washed with a small amount of pentane (2 mL).
Compound 8 was obtained in 30% yield (260.0 mg, 0.33 mmol;
mp: 149−151 °C). IR (KBr, cm−1): 3048 (w), 2964 (w), 2341 (w),
1569 (vs), 1530 (w), 1429 (vs), 1371 (w), 1270 (m), 1214 (m), 1183
(m), 1155 (vw), 1091 (s), 1024 (w), 993 (vw), 912 (vw), 800 (w),
741 (s), 691 (vs), 537 (s), 515 (vs). Anal. Calcd for C44H44NClP2Ru:
C, 67.29; H, 5.64. Found: C, 66.55; H, 5.99.
Synthesis of [η5-CH2C(Me)CHC(Me)O]RuH(PPh3)2 (13). The
freshly prepared in situ lemon-yellow solution of the lithium
oxopentadienide salt (0.58 mmol) was slowly added dropwise to a
cold (−110 °C), purple suspension of RuHCl(PPh3)3 (270 mg, 0.29
mmol) in 50 mL of THF. After the solution was warmed to room
temperature and stirred for 12 h, a bright yellow solution was
observed. The volatiles were removed under vacuum and the crude,
oily, amber-colored product was washed five times with hexane (15 mL),
affording a fine yellow precipitate. The solid was recrystallized from
methylene chloride−hexane at room temperature to give 141.0 mg (0.19
mmol, 67%) of 13, which melts at 205−209 °C, with decomposition.
Synthesis of RuCl(η5-CH2CHCHCHO)(PPh3)2 (9). Compound 7
(91.0 mg, 0.11 mmol) was dissolved in the minimum amount of THF
and passed down a silica gel column (50.0 cm × 1.5 cm) by elution
with diethyl ether. A yellow fraction was collected, and the solvent
removed under reduced pressure; this gave compound 9 (40.0 mg,
0.06 mmol) as a bright yellow powder in 49% yield, mp: 119−121 °C).
7143
dx.doi.org/10.1021/om300657z | Organometallics 2012, 31, 7125−7145
Reyna-Madrigal, Amira
