Redox-ActiVe Complexes Containing Group 8 Metal Centers
Organometallics, Vol. 26, No. 15, 2007 3743
containing 0.1 M [NBu4]PF6 as supporting electrolyte using a PAR
model 263 apparatus, with ferrocene as internal calibrant (FeCp2/
[FeCp2]+ ) 0.46 V). The OTTLE cell has been described
elsewhere44 and featured a 1 mm path-length cell with a Pt-mesh
working electrode and Pt wire counter and pseudo-reference
electrodes. Samples (1 mM) were dissolved in CH2Cl2 containing
0.5 M [NBu4]BF4 as the supporting electrolyte for the spectro-
electrochemical experiments. Elemental analyses were performed
by CMAS, Belmont, Vic., Australia. The magnetic susceptibilities
were measured using a Quantum Design MPMS5 Squid magne-
tometer, in an applied field of 1 T, with the sample contained in a
quartz tube carefully sealed to prevent any sample decomposition.
Freshly prepared samples gave reproducible data.
[Os(dCdCH2)(dppe)Cp*](PF6) (4) (160 mg, 85%). IR (Nujol,
1
cm-1): ν(CC) 1633w, ν(PF) 836s. H NMR (d6-acetone): δ 0.60
(s, 2H, CCH2), 1.74 (s, 15H, Cp*), 2.86-3.06 (m, 4H, CH2CH2),
7.24-7.63 (m, 20H, Ph). 31P NMR (d6-acetone): δ 40.8 (s, dppe);
1
-142.5 [septet, J(PF) 703 Hz, PF6].
[{Ru(dppe)Cp}2(µ-CCH)]PF6 (5). Solution A: AgOTf (144 mg,
0.56 mmol) was added to a solution of RuCl(dppe)Cp (350 mg,
0.58 mmol) in thf (20 mL), and the suspension was stirred in the
dark for 30 min.
Solution B: In a separate flask, [Ru(dCdCH2)(dppe)Cp]PF6
(429 mg, 0.583 mmol) was treated with LiBu (0.48 mL of a 2.5 M
solution in hexanes, 1.22 mmol), and the resulting solution was
stirred at rt for 30 min.
Reagents. The complexes MCl(dppe)Cp′ (Cp′ ) Cp, M ) Fe,45
Ru,46 Os;47 Cp′ ) Cp*, M ) Ru,27b Os47), HCtCSiMe3,48 and [Ru-
(dCdCH2)(dppe)Cp*]PF627b were prepared by the cited methods.
(a) [Fe(dCdCH2)(dppe)Cp]PF6 (1). A solution of FeCl(dppe)-
Cp (500 mg, 0.90 mmol), [NH4]PF6 (294 mg, 1.80 mmol), and
HCtCSiMe3 (0.64 mL, 4.50 mmol) in t-BuOH (10 mL) was heated
at reflux point for 2 h. The resulting precipitate was collected by
filtration and washed with Et2O to yield [Fe(dCdCH2)(dppe)Cp]-
PF6 (1) (559 mg, 90%). IR (Nujol, cm-1): ν(CC) 1626w, ν(PF)
842s. 1H NMR (d6-acetone): δ 3.06-3.37 (m, 4H, CH2CH2), 3.99
(s, 2H, CCH2), 5.25 (s, 5H, Cp), 7.42-7.73 (m, 20H, Ph). 13C NMR
(d6-acetone): δ 90.15 (s, Cp), 106.93 (s, Câ), 129.42-137.47 (m,
Solution A was filtered through a pad of Celite into solution B.
Stirring was continued at rt for 12 h. The orange solution was then
passed through a short silica column, completing the elution with
acetone to give a green product. After removal of solvent, the
residue was extracted into a minimum amount of CH2Cl2 and
filtered into rapidly stirred Et2O (300 mL) to give [{Ru(dppe)Cp}2-
(µ-CCH)]PF6 (5) (508 mg, 70%) as a forest-green powder. An
analytical sample was recrystallized from CH2Cl2/hexane. Anal.
Calcd (C64H59F6P5Ru2): C, 59.17; H, 4.57; M (cation), 1154.
1
Found: C, 59.30; H, 4.53. IR (Nujol, cm-1): 1651m, 837s. H
NMR (CD2Cl2): δ 1.91, 2.08 (2 × m, 2 × 4H, CH2), 2.51 [qu,
J(HP) ) 6 Hz, CdCH], 4.75 (s, 10H, Cp), 6.52-8.02 (m, 40H,
Ph). 31P (CD2Cl2): δ 81.7 (s, dppe), -142.4 (septet, PF6). ES-MS
2
Ph), 354.71 [t, J(CP) ) 33 Hz, CR]. 31P NMR (d6-acetone): δ
1
98.0 (s, dppe); -142.5 [septet, J(PF) ) 703 Hz, PF6]. ES-MS
(MeOH, m/z): 1154, M+; 577, M2+
.
(positive ion mode, MeOH, m/z): 545, [Fe(CCH2)(dppe)Cp]+; 519,
[Fe(dppe)Cp]+.
(e) [{Cp(dppe)Ru}2(µ-C2)]PF6 ([7]PF6). [FeCp2]PF6 (38 mg,
0.115 mmol) was added to a solution of [{Cp(dppe)Ru}2(µ-CCH)]-
PF6 (150 mg, 0.115 mmol) in CH2Cl2 (15 mL), and the mixture
was stirred for 30 min. Solvent was then removed under vacuum,
and the residue was dissolved in a minium amount of benzene and
chromatographed (silica gel), eluting with acetone/hexane (1:9) to
remove FeCp2 and then acetone/hexane (3:7) to yield [{Cp(dppe)-
Ru}2(µ-C2)]PF6 ([7]PF6) (137 mg, 92%). Anal. Calcd (C64H58F6P5-
Ru2): C, 59.21; H, 4.50; M (cation), 1154. Found: C, 59.30; H,
4.53. IR (Nujol, cm-1): ν(CC) 1713w, ν(PF) 839s. ES-MS (positive
ion mode, MeOH, m/z): 1154, M+.
(b) [Ru(dCdCH2)(dppe)Cp]PF6 (2). Similarly, RuCl(dppe)-
Cp (500 mg, 0.83 mmol), [NH4]PF6 (272 mg, 1.67 mmol), and
HCtCSiMe3 (0.59 mL, 4.15 mmol) in t-BuOH (10 mL) gave [Ru-
(dCdCH2)(dppe)Cp]PF6 (2) (554 mg, 91%). IR (Nujol): ν(CC)
1
1640w, ν(PF) 839s. H NMR (d6-acetone): δ 3.08-3.24 (m, 4H,
CH2CH2), 3.20 [t, 4J(HP) ) 1.5 Hz, 2H, CCH2)], 5.65 (s, 5H, Cp),
7.34-7.83 (m, 20H, Ph). 31P NMR (d6-acetone): δ 80.8 (s, dppe);
1
-142.4 [septet, J(PF) ) 703 Hz, PF6]. Lit. values:25 IR (Nujol):
1
ν(CC) 1641w, ν(PF) 841 s (PF6). H NMR (CD2Cl2): δ 2.95 (m,
4
4H, CH2CH2), 3.19 [t, J(HP) 1.5 Hz, 2H, CCH2], 5.37 (s, 5H,
(f) [{Cp(dppe)Ru}2(µ-C2)](PF6)2 ([7](PF6)2). [FeCp2]PF6 (76
mg, 0.23 mmol) was added to a solution of [{Cp(dppe)Ru}2(µ-
CCH)]PF6 (150 mg, 0.115 mmol) in CH2Cl2 (15 mL) and stirred
for 30 min. The solvent was then removed under vacuum, and the
residue dissolved in a minium amount of benzene and chromato-
graphed (silica gel), eluting with acetone/hexane (1:9) to remove
FeCp2 and then acetone/hexane (1:1) to yield [{Cp(dppe)Ru}2(µ-
C2)](PF6)2 ([7](PF6)2) (166 mg, 89%). Anal. Calcd (C64H58F12P6-
Ru2): C, 53.18; H, 4.05; M (dication), 577. Found: C, 53.09; H,
4.07. IR (Nujol, cm-1): ν(CC) 1651w, ν(PF) 840s. ES-MS (positive
Cp), 7.57-7.16 (m, 20H, Ph).
(c) [Os(dCdCH2)(dppe)Cp]PF6 (3). A solution of OsCl(dppe)-
Cp (100 mg, 0.145 mmol), [NH4]PF6 (48 mg, 0.29 mmol), and
HCtCSiMe3 (0.1 mL, 0.725 mmol) in t-BuOH (2.5 mL) was heated
at reflux point for 4 h. After removal of solvent under vacuum, the
residue was dissolved in a minimum amount of CH2Cl2 and filtered
into Et2O. The resulting precipitate was collected to yield
[Os(dCdCH2)(dppe)Cp]PF6 (3) (40 mg, 56%). IR (Nujol, cm-1):
1
4
ν(CC) 1641w, ν(PF) 837s. H NMR (d6-acetone): δ 0.62 (t, JHP
) 0.23 Hz, 2H, CCH2), 3.22-2.94 (m, 4H, CH2CH2), 5.76 (s, 5H,
Cp), 7.91-7.14 (m, 20H, Ph). 13C NMR (d6-acetone): δ 90.79 (s,
Cp), 95.06 (s, Câ), 126.73-139.29 (m, Ph), 302.91 (s, CR). 31P NMR
(d6-acetone): δ 42.9 (s, dppe); -141.6 (septet, 1JPF ) 703 Hz, PF6).
ES-MS (positive ion mode, MeOH, m/z): 681, [Os(CCH2)(dppe)-
Cp]+; 655, [Os(dppe)Cp]+. The filtrate was then purified by
chromatography (silica gel), eluting with acetone/hexane (3:7) to
recover unreacted OsCl(dppe)Cp (40 mg, 40%).
ion mode, MeOH, m/z): 577, [M]2+
.
{Cp(dppe)Ru}2(µ-CtC) (7). KOBut (35 mg, 0.31 mmol) was
added to a suspension of [{Ru(dppe)Cp}2(µ-CCH)]PF6 (100 mg,
0.08 mmol) in thf (5 mL). The color changed rapidly from green
to orange, and after ca. 5 min, hexane (50 mL) was added.
Concentration to 20 mL and addition of CH2Cl2 (1 mL) gave an
orange solution, which was left to crystallize under a gentle stream
of N2. After 24 h, red crystals had separated. These were collected
and washed with acetone and dry Et2O to give {Cp(dppe)Ru}2(µ-
CtC) (7) (24 mg, 27%). Anal. Calcd (C64H58P4Ru2): C, 66.66; H,
5.07; M, 1153. Found: C, 66.70; H, 5.06. IR (Nujol, cm-1): 1951m.
1H NMR (C6D6): δ 1.92, 2.11 (2 × m, 2 × 4H, CH2), 4.59 (s,
10H, Cp), 6.85-7.93 (m, 40H, Ph). 13C NMR (C6D6): δ 29.09
(m, CH2), 82.84 (s, Cp), 129.18-145.90 (m, Ph). 31P NMR
(C6D6): δ 87.8 (br). ES-MS (positive ion, MeOH, m/z): 1154,
(d) [Os(dCdCH2)(dppe)Cp*]PF6 (4). Similarly, OsCl(dppe)-
Cp* (160 mg, 0.211 mmol), [NH4]PF6 (69 mg, 0.422 mmol), and
HCtCSiMe3 (0.14 mL, 1.054 mmol) in MeOH (15 mL) were
heated at reflux point for 3 h, subsequent workup giving
(44) Duff, C. M.; Heath, G. A. Inorg. Chem. 1991, 30, 2528.
(45) Mays, M. J.; Sears, P. L. J. Chem. Soc., Dalton Trans. 1973, 1873.
(46) Gutierrez, A. A.; Ballester Reventos, L. J. Organomet. Chem. 1998,
338, 249.
(47) Perkins, G. J.; Bruce, M. I.; Skelton, B. W.; White, A. H. Inorg.
Chim. Acta 2006, 359, 2644.
[M]+; 577, [M + H]2+
.
{Cp(dppe)Ru}CtC{Ru(dppe)Cp*} (10). To a solution of
[{Cp(dppe)Ru}CC{Ru(dppe)Cp*}](PF6)2 (100 mg, 0.066 mmol)
in THF (10 mL) was added an excess of KOBut (23 mg, 0.198
(48) Holmes, A. B.; Sporikou, C. N. Organic Syntheses; Wiley: New
York, 1993; Collect. Vol. 8, p 606.