spectrometer using CDCl3 solvent with liquid NH3 and
85% H3PO4 respectively as references. Positive and negative
ionization fast atom bombardment (FAB) mass spectra were
recorded on a Finnigan MAT 95 mass spectrometer, using
m-nitrobenzyl alcohol or α-thioglycerol as matrix solvents.
Microanalyses were performed by Butterworth Laboratories,
UK.
bands. Four consecutive bands were then eluted, namely
[Ru4(CO)9(µ-CO)2(µ4-NOMe)(µ4-η2-PhC2Ph)] 3b (Rf 0.75, 32.4
mg, 0.035 mmol, 18%), [Ru6(CO)13(µ-H)(µ5-N)(µ3-η2-PhC2Ph)2]
7b (Rf 0.7, 10.3 mg, 0.0077 mmol, 6%), [Ru4(CO)9(µ-CO)2-
{µ4-NC(O)OMe}(µ4-η2-PhC2Ph)] 4b (Rf 0.48, 18.6 mg, 0.019
mmol, 10%) and [Ru4(CO)9(µ-CO)2(µ4-NH)(µ4-η2-PhC2Ph)]
6b4 (Rf 0.45, 20.9 mg, 0.023 mmol, 12%) (Found: C, 33.5; H,
1.2; N, 1.6. Calc. for C26H13NO12Ru4 3b: C, 33.38; H, 1.40; N,
1.50. Found: C, 36.8; H, 1.7; N, 1.2. Calc. for C41H21NO13Ru6
7b: C, 36.69; H, 1.58; N, 1.04. Found: C, 33.8; H, 1.5; N, 1.3.
Calc. for C27H13NO13Ru4 4b: C, 33.65; H, 1.36; N, 1.45%).
Preparation of [Ru3(CO)9(ì3-NOMe)(ì3-ç2-HC2Ph)] 2a
A
solution of [Ru3(CO)9(µ3-CO)(µ3-NOMe)] 1 (200 mg,
0.32 mmol) in n-hexane (40 ml) was heated with 3 drops of
phenylacetylene under an argon atmosphere. The initial yellow
solution changed to brown upon refluxing. After 1 h, the
solvent was removed under reduced pressure. The residue was
redissolved in CH2Cl2 (2 ml) and separated by preparative
TLC using the eluent n-hexane–CH2Cl2 (9:1, v/v) to afford one
yellow band 2a (Rf 0.75) in 75% yield (168 mg, 0.24 mmol)
(Found: C, 30.9; H, 1.4; N, 1.8. Calc. for C18H9NO10Ru3: C,
30.78; H, 1.29; N, 1.99%).
Reaction of complex 1 with phenylacetylene in n-octane
A suspension of compound 1 (200 mg, 0.32 mmol) in n-octane
(60 ml) was refluxed with 3 drops of phenylacetylene under
an argon atmosphere. The solution gradually changed from
yellow to dark brown. Thermolysis was continued until no
starting materials remained (about 4 h, as confirmed by IR
spectroscopy). The mixture was dried in vacuo. The dark brown
residue was redissolved in CH2Cl2 (2 ml) and TLC separation
(n-hexane–dichloromethane, 3:1, v/v) afforded [Ru4(CO)12-
(µ4-η2-HC2Ph)]10 (Rf 0.85, 8.0 mg, 0.010 mmol, 4%), 3a (Rf 0.7,
51.3 mg, 0.060 mmol, 25%), 5a (Rf 0.5, 5.4 mg, 0.005 mmol,
3%), 4a (Rf 0.45, 36.0 mg, 0.041 mmol, 17%) and [Ru2(CO)6-
{µ-η3-HC2(Ph)C(O)N(OMe)}] 8a (Rf 0.2, 7.8 mg, 0.014 mmol,
3%) (Found: C, 33.1; H, 1.8; N, 2.4. Calc. for C16H9NO8Ru2
8a: C, 33.24; H, 1.66; N, 2.57%).
Preparation of [Ru3(CO)9(ì3-NOMe)(ì3-ç2-PhC2Ph)] 2b
A solution of cluster 1 (200 mg, 0.32 mmol) and diphenyl-
acetylene (62 mg, 0.35 mmol) in n-hexane was allowed to heat at
60 ЊC for 1 h, the solvent was then removed in vacuo and the
residue subjected to TLC using n-hexane–CH2Cl2 (6:1, v/v) as
eluent. An intense yellow band [Ru3(CO)9(µ3-NOMe)(µ3-η2-
PhC2Ph)] 2b was isolated in 70% yield (Rf 0.7, 173 mg, 0.22
mmol) (Found: C, 37.1; H, 1.8; N, 1.6. Calc. for C24H13NO10-
Ru3: C, 37.02; H, 1.68; N, 1.80%).
Thermolysis of complex 3a
Compound 3a (20 mg, 0.023 mmol) was dissolved in n-octane
(30 ml). The yellow solution was heated at 125 ЊC for 4 h which
resulted in the formation of a deep brown solution. The solvent
was removed under reduced pressure and the only product
isolated by TLC, using n-hexane–dichloromethane (3:1, v/v) as
eluent, was 4a (Rf 0.45, 6.2 mg, 0.007 mmol, 30%) accompanied
by a small amount of unchanged 3a (Rf 0.7, 1.6 mg, 0.0019
mmol, 8%).
Thermolysis of compound 2a
Compound 2a (200 mg, 0.28 mmol) was dissolved in n-octane
(40 ml). The bright yellow solution was heated at 125 ЊC for
3 h. The solvent was then removed in vacuo and the residue
chromatographed on TLC plates using n-hexane–CH2Cl2 (3:1,
v/v) as eluent. The first red band was [Ru4(CO)12(µ4-η2-
HC2Ph)]10 (Rf 0.85, 9.0 mg, 0.011 mmol, 5%). Three products
were isolated in the following order of elution [Ru4(CO)9-
(µ-CO)2(µ4-NOMe)(µ4-η2-HC2Ph)] 3a (Rf 0.7, 45.9 mg, 0.053
mmol, 25%), [Ru5(CO)13(µ-CO)(µ4-NH)(µ4-η2-HC2Ph)] 5a (Rf
0.5, 4.8 mg, 0.0047 mmol, 3%) and [Ru4(CO)9(µ-CO)2{µ4-
NC(O)OMe}(µ4-η2-HC2Ph)] 4a (Rf 0.45, 28.4 mg, 0.032 mmol,
15%) (Found: C, 27.7; H, 0.9; N, 1.6. Calc. for C20H9NO12Ru4
3a: C, 27.9; H, 1.06; N, 1.63. Found: C, 26.2; H, 0.9; N, 1.5.
Calc. for C22H7NO14Ru5 5a: C, 26.04; H, 0.70; N, 1.38. Found:
C, 28.6; H, 1.2; N, 1.4. Calc. for C21H9NO13Ru4 4a: C, 28.42;
H, 1.02; N, 1.58%).
Carbonylation of complex 3a in n-hexane or n-heptane
Compound 3a (20 mg, 0.023 mmol) was dissolved in n-hexane
or n-heptane (30 ml). The bright yellow solution was heated
while CO gas was bubbled through it. Using IR spectroscopic
monitoring, no visible change was observed after 4 h.
Carbonylation of complex 3a in n-octane
Compound 3a (20 mg, 0.023 mmol) was dissolved in n-octane
(30 ml). The yellow solution was then carbonylated under
reflux. The reaction was monitored by spot TLC until complete
consumption of 3a (about 10 h). The mixture was dried in vacuo
and the residue chromatographed on TLC plates using n-
hexane–dichloromethane (6:1, v/v) as eluent. The first band
obtained was [Ru3(CO)12] (Rf 0.9, 5.0 mg, 0.008 mmol, 25%).
Compounds 2a (Rf 0.8, 6.5 mg, 0.009 mmol) and 4a (Rf 0.65,
6.2 mg, 0.007 mmol) were eluted in sequence with 30% yield of
each.
Pyrolysis of [Ru3(CO)9(ì3-NOMe)(ì3-ç2-HC2Ph)] 2a
Compound 2a (200 mg, 0.28 mmol) was sealed in a Carius
tube under reduced pressure and placed in an oven at 140 ЊC
for half an hour. The dark brown residue was then extracted
with dichloromethane until the extract became colourless. The
solvent was removed and the residue chromatographed on silica
gel plates using n-hexane–dichloromethane (3:1, v/v) as eluent.
The first few compounds eluted were [Ru3(CO)12] (Rf 0.95, 18.2
mg, 0.028 mmol, 10%), [Ru4(CO)12(µ4-η2-HC2Ph)]10 (Rf 0.85,
14.4 mg, 0.017 mmol, 8%) and [Ru6C(CO)17] (Rf 0.8, 9.4 mg,
0.0085 mmol, 6%). The following compounds 3a, 4a and 5a
were isolated in 19 (34.9 mg, 0.041 mmol), 26 (49.3 mg, 0.055
mmol) and 4% (6.9 mg, 0.0068 mmol) yields, respectively.
Protonation of complex 3a
Compound 3a (50 mg, 0.058 mmol) was stirred in acidified
acetonitrile (50 ml) prepared by the addition of 0.4 ml of 0.18
M (in MeCN) H2SO4 solution to 50 ml of distilled acetonitrile
solvent. The reaction was monitored by spot TLC until all start-
ing material had been consumed (about 1 d). The solvent was
removed under reduced pressure and the residue chromato-
graphed on silica using n-hexane–dichloromethane (3:1, v/v) as
eluent. The first two yellow bands were found to be 2a (Rf 0.78,
2.7 mg, 0.004 mmol, 5%) and 3a (Rf 0.7, 2.5 mg, 0.003 mmol,
5%). The following product 9a was isolated in 65% yield (Rf 0.3,
Thermolysis of compound 2b
A solution of compound 2b (200 mg, 0.26 mmol) in n-octane
(40 ml) was refluxed under an argon atmosphere for 3 h. The
solution gradually turned from yellow to dark brown. The sol-
vent was removed under reduced pressure. Chromatography on
silica with n-hexane–dichloromethane (4:1, v/v) afforded four
J. Chem. Soc., Dalton Trans., 1998, 4215–4228
4225
Ho, Emmie Ngai-Man
