M.I. Bruce et al. / Journal of Organometallic Chemistry 670 (2003) 170ꢁ
/177
175
Preparative TLC was carried out on glass plates (20ꢄ
20 cm) coated with silica gel (Merck 60 GF254, 0.5 mm
thickness).
/
(positive ion, with NaOMe, m/z): 1609, [Mꢂ
1586, [M]ꢂ; 1581ꢁ
1385, [MꢂNaꢃ
(negative ion, MeOH, m/z): 1585, [Mꢃ
/
Na]ꢂ;
/
/
/
nCO]ꢂ (nꢀ
/
1ꢁ8);
/
/
H]ꢃ.
5.1.1. Instrumentation
5.2.2. (b) nꢀ
A similar reaction to (a) above used {Au[P(tol)3]}2{m-
(CÅC)3} (50 mg, 0.05 mmol), Co3(m3-CBr)(m-
dppm)(CO)7 (89.6 mg, 0.1 mmol), Pd(PPh3)4 (5 mg,
0.004 mmol) and CuI (1 mg, 0.005 mmol) in THF (25
ml). After stirring at r.t. for 2 h, a new brown band (Rf
0.38) was present. Purification by running the solution
/
3 (2)
IR: PerkinꢁElmer 1720X FTIR. Spectra of solutions
/
in CH2Cl2 held in a 0.05 mm path-length NaCl cell were
recorded. NMR: Bruker CXP300 or ACP300 (1H- at
300.13 MHz, 13C- at 75.47 MHz) or Varian Gemini 200
(1H- at 199.8 MHz, 13C- at 50.29 MHz) spectrometers.
Unless otherwise stated, spectra were recorded using
solutions in CDCl3 in 5 mm sample tubes. ES mass
spectra: Finnegan LCQ. Solutions were directly infused
into the instrument. Chemical aids to ionisation were
used as required [17]. Cyclic voltammograms were
recorded for 1.0 mM solution in CH2Cl2, with 0.1 M
[NBu4][BF4] as supporting electrolyte, using a Maclab
400 instrument. A three-electrode system was used,
consisting of a Pt-dot working electrode and Pt counter
and reference electrodes. Potentials are given in V versus
/
through
dppm)(CO)7}2{m3:m3-C(CÅ
a
short silica column gave {Co3(m-
C)3C} (2) (61.5 mg, 77%) as
/
a dark brown solid, only moderately soluble in THF and
other organic solvents. Anal. Found: C, 51.25; H, 2.49
(consistent analyses could not be obtained as a result of
the insolubility of this complex). Calc. for
C72H44Co6O4P4: C, 53.69; H, 2.75%; M, 1610. IR
(cmꢃ1) (Nujol): n(CÅ
2064 (sh), 2045s, 2014vs, 1991 (sh), 1974w. ESꢁ
(negative ion, with NaOMeꢁMeOH, m/z): 1737, [Mꢂ
I]ꢃ (I from CsI calibrant); 1609, [MꢃH]ꢃ; (positive
ion, NaOMeꢁMeOH, m/z): 1633, [Mꢂ
Na]ꢂ; 805,
[Co3C4(CO)7(dppm)]ꢂ.
/C) 2089vw; (CH2Cl2) n(CO)
/MS
SCE, the ferroceneꢁ
internal calibrant for the measured potentials (E0ꢀ
/
ferricinium couple being used as
0.46
/
/
/
/
V vs. SCE) [18].
/
/
5.1.2. Reagents
Co3(m3-CBr)(CO)9 was made from Co2(CO)8 and
CBr4 via a modified literature procedure [19]. Addition
of dppm (one equivalent) in the presence of tmno
5.2.3. (c) nꢀ
A mixture of {Au[P(tol)3]}2{m-(CÅ
mmol), Co3(m3-CBr)(m-dppm)(CO)7 (100 mg, 0.12
mmol), Pd(PPh3)4 (7 mg, 0.006 mmol) and CuI (1 mg,
0.005 mmol) in THF (25 ml) was stirred at r.t. for 1 h.
/
4 (3)
/
C)4} (65 mg, 0.06
afforded Co3(m3-CBr)(m-dppm)(CO)7 (70ꢁ
Au(I)ꢁphosphine complexes {Au[P(tol)3]}2{m-(CÅ
were obtained from reactions between AuCl{P(tol)3}
and SiMe3(CÅC)nSiMe3 (nꢀ2ꢁ4) carried out in MeOH
in the presence of NaOH [12].
/80%). The
/
/C)n}
Purification by preparative TLC gave an orangeꢁ
band (Rf 0.50) from which dark red crystals (CH2Cl2ꢁ
C)4C} (3)
/brown
/
/
/
/
MeOH) of {Co3(m-dppm)(CO)7}2{m3:m3-C(CÅ
/
(88 mg, 91%) were obtained. Anal. Found: C, 54.42; H,
2.81. Calc. for C74H44Co6O14P4: C, 54.37; H, 2.71%; M,
5.2. Preparation of {Co3(m-dppm)(CO)7}2{m3:m3-
C(CÅC)nC}
/
1634. IR (cmꢃ1) (Nujol): 2112vw, 2104vw n(CÅ
/C);
(cyclohexane): n(CÅ
/
C) 2112vw, 2104w; n(CO) 2060s,
1
2056 (sh), 2017vs, 1990 (sh), 1981w, 1960vw (br). H-
5.2.1. (a) nꢀ
Tetrahydrofuran (10 ml) was added to a solid mixture
of {Au[P(tol)3]}2{m-(CÅC)2} (105 mg, 0.1 mmol),
/
2 (1)
NMR: d 3.45, 4.33 (2ꢄ
/
m, 2ꢄ
/
1H, CH2), 7.22ꢁ7.49 (m,
/
/
20H, Ph). 13C-NMR: d 43.95 [t, J(CP) 22 Hz, dppm],
71.63 [s, C(5)], 82.74 [s, C(4)], 97.56 [s, C(3)], 103.13 [s,
Co3(m3-CBr)(m-dppm)(CO)7 (170 mg, 0.2 mmol),
Pd(PPh3)4 (14 mg, 0.012 mmol) and CuI (2 mg, 0.01
mmol) and the whole was stirred at room temperature
(r.t.) for 3 h. The filtered solution was evaporated under
vacuum and the residue was extracted with CH2Cl2.
C(2)], 128.84ꢁ
31P-NMR: 34.75 (s, dppm). ESꢁ
NaOMeꢁMeOH, m/z): 1761, [Mꢂ
calibrant); 1633, [Mꢃ
H]ꢃ; (positive ion, NaOMeꢁ
MeOH, m/z): 1657, [Mꢂ
Na]ꢂ.
/
135.05 (m, Ph), 201.67, 209.92 (s, br, CO).
MS (negative ion,
I]ꢂ (I from CsI
/
/
/
/
/
Separation by preparative TLC (C3H6Oꢁ
gave one major brown band (Rf 0.51) which contained
C)2C} (1) (142 mg,
/
C6H12 3/7)
/
{Co3(m-dppm)(CO)7}2{m3:m3-C(CÅ
/
5.3. Reaction of {Co3(m-dppm)(CO)7}2{m3:m3-C(CÅ
C)3C} with tcne
/
89.3%), isolated as dark brown crystals. Anal. Found:
C, 52.89; H, 2.85. Calc. for C70H44Co6O14P4: C, 52.99;
H, 2.80%; M, 1586. IR (cmꢃ1) (Nujol): n(CÅ
/C) 2128vw;
Tcne (4 mg, 0.03 mmol) was added to a solution of
C)3C} (50 mg, 0.03
1
(CH2Cl2) n(CO) 2053s, 2007vs, 1967 (sh). H-NMR: d
3.41, 4.43 (2ꢄm, 2ꢄ1H, CH2), 7.20ꢁ7.46 (m, 20H,
Ph). 13C-NMR: d 44.59 (s, br, dppm), 97.56 [s, C(3)],
117.96 [s, C(2)], 128.55ꢁ135.34 (m, Ph); 202.25, 209.44
(s, br, CO). 31P-NMR: d 35.06 (s, dppm). ESꢁ
MS
{Co3(m-dppm)(CO)7}2{m3:m3-C(CÅ
/
/
/
/
mmol) in THF (40 ml). After stirring overnight, the
solution had turned black. Evaporation, extraction with
CH2Cl2 and purification by preparative TLC (C3H6Oꢁ
C6H12 3/7) afforded a black band (Rf 0.29) which
/
/
/
Bruce, Michael I.
