10
M. Hirano et al. / Journal of Organometallic Chemistry 569 (1998) 3–14
packed Porapack-Q and Unicarbon A-400, stainless
packed molecular sieves, active carbon, and capillary
TC-wax and HR-1 columns. The volume of generated
gases was measured by Toepler pump. Melting points
were measured under nitrogen with Yazawa capillary
melting apparatus and the values were uncorrected.
Elemental analyses were performed with Yanaco MT-2
CHN auto corder or Perkin Elmer 2400 series II CHN
analyzer.
Hz, 2H, –OCH2–CH3 of the enolate), 6.9–7.6 (m, 20H,
P–Ph). 31P{1H}-NMR (121.6 MHz, C6D5CD3, 27°C): l
−26.9 (br, 1P), −22.6 (br, 3P); (0°C): l −26.6 (br. s,
1P), −22.4 (br. s, 2P), −20.6 (br. s, 1P); (−10°C): l
−26.6 (br. s, 1P), −22.3 (br. s, 2P), −20.6 (br. s, 1P);
(−20°C): l −26.4 (br. s, 1P), −22.2 (br. s, 2P),
−20.3 (br. s, 1P); (−30°C): l −26.3 (br. s, 1P),
−22.2 (br. s, 2P), −19.2 (br. s, 1P); (−40°C): l
−26.2 (br. s, 1P), −22.0 (br. s, 2P), −20.1 (br. s, 1P).
Minor isomer: Overlapping of signals due to the minor
isomer with the major ones prevented complete charac-
terization and only several peaks are assigned. 1H-
NMR (C6D5CD3, 27°C): l 4.49 (q, J=7 Hz, 2H,
–OCH2–CH3 of the enolate); (10°C): l 3.74 (q, J=7
Hz, 2H, –OCH2–CH3 of the ester), 4.48 (q, J=7 Hz,
2H, –OCH2–CH3 of the enolate); (0°C): l 0.95 (t, J=7
Hz, 3H, –OCH2–CH3 of the ester), 3.74 (q, J=7 Hz,
2H, –OCH2–CH3 of the ester), 4.49 (q, J=7 Hz, 2H,
–OCH2–CH3 of the enolate); (−10°C): l 0.93 (t, J=7
Hz, 3H, –OCH2–CH3 of the ester), 3.73 (q, J=7Hz,
2H, –OCH2–CH3 of the ester), 4.52 (q, J=7 Hz, 2H,
–OCH2–CH3 of the enolate); (−20°C): l 0.89 (t, J=7
Hz, 3H, –OCH2–CH3 of the ester), 3.70 (q, J=7 Hz,
–OCH2–CH3 of the ester), 4.53 (q, J=7Hz, –OCH2–
CH3 of the enolate); (–30°C): l 0.90 (t, J=7 Hz, 3H,
–OCH2–CH3 of the ester), 3.63 (br., 1H, NCCH–),
3.68 (q, J=7 Hz, –OCH2–CH3 of the ester), 4.51 (q,
J=7Hz, –OCH2–CH3 of the enolate); (−40°C): l
0.90 (t, J=7 Hz, 3H, –OCH2–CH3 of the ester), 2.91
(br. s., 2H, NCCH2–), 3.63 (q, J=7 Hz, 2H, –OCH2–
CH3 of the ester), 3.67 (s, 1H, NCCH–), 4.52 (q, J=7
Hz, 2H, –OCH2–CH3 of the enolate). 31P{1H}-NMR
(121.6 MHz, C6D5CD3, 0°C): l −26.6 (br. s, over-
lapped with a peak of the major species), −21.6 (br. s,
2P), −20.0 (br. s, 1P); (−10°C): l −26.6 (br. s,
overlapped with a peak of the major species), –21.5 (br.
s, 2P), –19.4 (br. s, 1P); (−20°C): l −26.4 (br. s,
overlapped with a peak of the major species), −21.4
(br. s, 2P), −19.3 (br. s, 1P); (−30°C): l −26.3 (br.
s, 1P overlapped with a peak of the major species),
−21.3 (br. s, 2P), −19.2 (br. s, 1P); (−40°C): l
−26.2 (br. s, 1P, overlapped with a peak of the major
species), −21.2 (br. s, 2P), −19.0 (br. s, 1P). IR (KBr,
cm−1): 2236 (s, wCN), 2169 (s, wCN), 1745 (s, wCO), 1629
(s, wCO). UV-Vis (C6H6, r.t.): umax=610 nm, m=3500
M−1 cm−1. Molar electric conductivity: 0.035 S cm2
mol−1 (THF, 25°C). M.p.(dec.): 94–95°C. Anal.
Found: C, 52.21; H, 6.05; N, 2.85%. Calc. for
C42H57N2O4P4Re: C, 52.33; H, 5.96; N, 2.91%.
3.2. Preparation of Re(NCCHCO2R)(NCCH2CO2R)
(PMe2Ph)4 (2)
Methyl cyanoacetate (50.0 ml, 0.570 mmol) was
added to
a
Et2O (5 ml) solution of cis-
ReH(N2)(PMe2Ph)4 (1) (145.1 mg, 0.189 mmol) and the
solution was stirred for 6 h at room temperature. The
solution color slowly changed from yellow to greenish
yellow. During the reaction, nitrogen and hydrogen
gases were generated in 68 and 55%, respectively. Evap-
oration of the solvent followed by recrystallization
from Et2O/hexane gave air sensitive yellow crystals of
Re(NCCHCO2Me)(NCCH2CO2Me)(PMe2Ph)4
(2a)
(123.0 mg, 0.131 mmol, 69%). 1H-NMR (200 MHz,
C6D6, r.t.): l 0.92 (br. s, 6H, P–CH3), 1.69 (br. s, 6H,
P–CH3), 1.69 (d, J=7 Hz, 12H, P–CH3), 2.65 (s, 2H,
NCCH2–), 3.17 (s, 3H, –OCH3), 3.89 (s, 3H, –OCH3),
3.93 (s, 1H, NCCH–), 6.9–7.6 (m, 20H, P–Ph). IR
(KBr, cm−1): 2236 (s, wCN), 2166 (s, wCN), 1751 (s, wCO),
1627 (s, wCO). M.p.(dec.): 150–152°C. Anal. Found: C,
50.57; H, 6.33; N, 3.22%. Calc. for C40H53N2O4P4Re:
C, 51.33; H, 5.71; N, 2.99%.
Re(NCCHCO2Et)(NCCH2CO2Et)(PMe2Ph)4
(2b),
Re(NCCHCO2Bu)(NCCH2CO2Bu)(PMe2Ph)4 (2c) and
Re(NCCMeCO2Et)(NCCHMeCO2Et)(PMe2Ph)4 (2d)
were prepared analogously and their yields, m.p., ana-
lytical and spectroscopic data are listed below.
2b: From 1 (269.7 mg, 0.351 mmol) and ethyl
cyanoacetate (120 ml, 1.12 mmol), hydrogen and nitro-
gen gases were evolved in 98% and 96%, respectively.
Yield, 203.6 mg, 74%. Complex 2b is found to have two
isomers, which are likely to be due to (E)- and (Z)-iso-
mers of the enolato ligand. The population of these
isomers is approximately 85/15. No significant change
of the population was observed within VT NMR tem-
1
perature range (27– −40°C). Major isomer: H-NMR
(300 MHz, C6D5CD3, 27°C): l 0.91 (t, J=7 Hz, 3H,
–OCH2–CH3 of the ester), 0.93 (virtual triplet, J=4
Hz, 6H, mutually trans-P–CH3), 1.33 (t, J=7 Hz, 3H,
–OCH2–CH3 of the enolate), 1.64 (virtual triplet, J=3
Hz, 6H, mutually trans-P–CH3), 1.68 (d, J=5 Hz, 6H,
P–CH3 trans to the enolate or the ester), 1.72 (d, J=5
Hz, 6H, P–CH3 trans to the ester or the enolate), 2.69
(br, 2H, NCCH2–), 3.71 (q, J=7 Hz, 2H, –OCH2–
CH3 of the ester), 3.75 (s, 1H, NCCH–), 4.39 (q, J=7
2c: From 1 (92.6 mg, 0.121 mmol) and n-butyl
cyanoacetate (36.0 ml, 0.253 mmol). Yield, 64.3 mg,
1
52%. H-NMR (200 MHz, C6D6, r.t.): l 0.79 (br, 3H,
–OC3H6–CH3), 0.91 (br. s, 6H, P–CH3), 1.07 (br, 3H,
–OC3H6–CH3), 1.0–1.6 (br, 8H, –OCH2–C2H4–), 1.69
(br. s, 6H, P–CH3), 1.69 (br, 12H, P–CH3), 2.74 (s, 2H,