Synthesis and oxidation of iron(II) ferrocenylacetylide diphosphine complexes. A novel type of mixed-valence complex

Article abstract of DOI:10.1021/om950525d

Some Fe(II) ferrocenylacetylide complexes, [(Cp or Cp*)(PP)FeC=CFc], were prepared by the photolysis of the corresponding carbonyl complexes [(Cp or Cp*)(CO)₂FeC=CFc] in the presence of diphosphines (PP = dppe, dppm, dmpe). The cyclic voltammograms showed two quasi-reversible waves at -0.47 to -0.84 and +0.08 to +0.12 V. The one-electron-oxidized species were isolated as relatively stable solids from the reaction of the neutral Fe(II) complexes with DDQ or FcHPF₆. The oxidized complexes exhibited an intervalence transfer band at 1295-1595 nm, and the interaction parameters were calculated from the position (α² = (0.98-2.44) ×10^-2). This suggests that these are highly electron delocalized mixed-valence complexes. The IR spectra (v_cc = 1956-1976 cm^-1), the ESR spectra (appearance of one broad signal), and the Mo?ssbauer spectra (QS = 2.00-2.26 mm s^-1) support the above suggestion. The structure of [Cp(dppe)FeC≡CFC] was determined by single-crystal X-ray diffraction.

Full text of DOI:10.1021/om950525d

Organometallics 1996, 15, 721-728
721
Syn th esis a n d Oxid a tion of Ir on (II) F er r ocen yla cetylid e
Dip h osp h in e Com p lexes. A Novel Typ e of Mixed -Va len ce
Com p lex
Masaru Sato* and Yukiko Hayashi
Chemical Analysis Center, Saitama University, Urawa, Saitama 338, J apan
Shigekazu Kumakura and Natsuko Shimizu
Department of Chemistry, Faculty of Science, Saitama University, Urawa 338, J apan
Motomi Katada and Satoshi Kawata
Department of Chemistry, Faulty of Science, Tokyo Metropolitan University,
Hachioji-shi, Tokyo, J apan
Received J uly 10, 1995X
Some Fe(II) ferrocenylacetylide complexes, [(Cp or Cp*)(PP)FeCtCFc], were prepared by
the photolysis of the corresponding carbonyl complexes [(Cp or Cp*)(CO)2FeCtCFc] in the
presence of diphosphines (PP ) dppe, dppm, dmpe). The cyclic voltammograms showed
two quasi-reversible waves at -0.47 to -0.84 and +0.08 to +0.12 V. The one-electron-
oxidized species were isolated as relatively stable solids from the reaction of the neutral
Fe(II) complexes with DDQ or FcHPF6. The oxidized complexes exhibited an intervalence
transfer band at 1295-1595 nm, and the interaction parameters were calculated from the
position (R2 ) (0.98-2.44) × 10-2). This suggests that these are highly electron delocalized
mixed-valence complexes. The IR spectra (νCC ) 1956-1976 cm-1), the ESR spectra
(appearance of one broad signal), and the Mo¨ssbauer spectra (QS ) 2.00-2.26 mm s-1
)
support the above suggestion. The structure of [Cp(dppe)FeCtCFC] was determined by
single-crystal X-ray diffraction.
In tr od u ction
gain more insight into the factors which affect the extent
of electron delocalization in mixed-valence complexes:
the mode of coordination to a metal, the kind of ligands,
and so on. In our latest report, we described the
synthesis and properties of some Fe(II) ferrocenylacetyl-
ide complexes and the corresponding oxidized species.7
In recent years, some transition-metal ferrocenylacetyl-
ide complexes also were investigated from the same8 or
other viewpoints (e.g., nonlinear optics).9,10 Herein, we
extend our system to include the synthesis of a complex
with a phosphine ligand, [(Cp or Cp*)Fe(PP)(CtCFc)],
and their one-electron-oxidized species.
Mixed-valence complexes are of interest for the in-
vestigation of electron-transfer processes, for their
enormous potential in the production of new materials
with super- and semiconductivity, and for their rel-
evance to biologically important systems.1 In organo-
metallic chemistry, since Cowan and his co-workers
reported the monocation of biferrocene,2 a great number
of binuclear ferrocene derivatives have been prepared
and the oxidized species have been investigated exten-
sively.3 Recently, mixed-valence systems of (η-C5R5)L2-
Fe-4 and other organoiron derivatives5 also have been
reported. However, few binuclear complexes containing
two iron atoms with each in a different coordination
mode have been prepared.6 In such complexes we can
(5) (a) Delville, M.-H.; Rittinger, S.; Astruc, D. J . Chem. Soc., Chem.
Commun. 1992, 519. (b) Stephan, M.; Davis, J . H.; Meng, X.; Chase,
K. J .; Hauss, J .; Zenneck, U.; Pritzkow, H.; Siebert, W.; Grimes, R. N.
J . Am. Chem. Soc. 1992, 114, 5214.
(6) (a) Guerchais, V. J . Chem. Soc., Chem. Commun. 1990, 534. (b)
Liu, L.-K.; Luh, L.-S. Organometallics 1994, 13, 2816. (c) Osborne, A.
G.; Whiteley, R. H. J . Organomet. Chem. 1979, 181, 425. (d) Pannell,
K. H.; Cassias, J . B.; Crawford, G. M.; Flores, A. Inorg. Chem. 1976,
15, 2671.
(7) Sato, M.; Hayashi, Y.; Katada, M.; Kawata, S. J . Organomet.
Chem. 1994, 471, 179.
(8) (a) Sato, M.; Shintate, H.; Kawata, Y.; Sekino, M.; Katada, M.;
Kawata, S. Organometallics 1994, 13, 1956. (b) Sato, M.; Mogi, E.;
Kumakura, S. Organometallics 1995, 14, 3157. (c) Sato, M.; Mogi, E.;
Katada, M. Organometallics 1995, 14, 4837.
(9) (a) Colbert, M. C. B.; Ingham, S. L.; Lewis, J .; Long, N. J .;
Raithby, P. R. J . Chem. Soc., Dalton Trans. 1994, 2215. (b) Colbert,
M. C. B.; Edwards, A. J .; Lewis, J .; Long, N. J .; Page, N. A.; Parker,
D. G.; Raithby, P. R. J . Chem. Soc., Dalton Trans. 1994, 2589.
(10) (a) Bunz, U. H. F.; Enkelmann, V. Organometallics 1994, 13,
3823. (b) Koridze, A. A.; Yanovsky, A. I.; Struchkov, Yu. T. J .
Organomet. Chem. 1992, 441, 277. (c) Russo, M. V.; Furlani, A.;
Licoccia, S.; Paolesse, R.; Villa, A. C.; Guastini, C. J . Organomet. Chem.
1994, 469, 245. (d) Onitsuka, K.; Tao, X.-Q.; Sonogashira, K. Bull.
Chem. Soc. J pn. 1994, 67, 2611. (e) Weigand, W.; Robl. C. Chem. Ber.
1993, 126, 1807.
X Abstract published in Advance ACS Abstracts, December 15, 1995.
(1) (a) Mixed-Valence Compounds; Brown, D. B., Ed.; D. Reidel:
Boston, MA, 1980. (b) Astruc, D. Electron-Transfer and Radical
Processes in Transition Metal Chemistry; VCH: New York, 1995;
Chapter 1.
(2) Cowan, D. O.; Kaufman, F. J . Am. Chem. Soc. 1970, 92, 219.
Kaufman, F.; Cowan, D. O. J . Am. Chem. Soc. 1970, 92, 6198.
(3) (a) Zhang, W.; Wilson, S. R.; Hendrickson, D. N. Inorg. Chem.
1989, 28, 4160 and references therein. (b) Dong, T.-Y.; Ke, T.-J .; Peng,
S.-M.; Yeh, S.-K. Inorg. Chem. 1989, 28, 2103. (c) Talham, D. R.;
Cowan, D. O. Organometallics 1987, 6, 932. (d) Amer, S. I.; Sadler,
G.; Henry, R. M.; Ferguson, G.; Ruhl, B. L. Inorg. Chem. 1985, 24,
1517. (e) Lee, M.-T.; Foxman, B. M.; Rosenblum, M. Organometallics
1985, 4, 539.
(4) (a) Delville, M.-H.; Lacoste, M.; Astruc, D. J . Am. Chem. Soc.
1992, 114, 8310. (b) Chukwu, R.; Hunter, A. D.; Santarsiero, B. D.
Organometallics 1992, 11, 589. (c) Le Narvor, N.; Lapinte, C. Orga-
nometallics 1993, 12, 357. (d) Etzenhouser, B. A.; Cavanaugh, M. D.;
Spurgeon, H. N.; Sponsler, M. B. J . Am. Chem. Soc. 1994, 116, 2221.
(e) Etzenhouser, B. A.; Chen, Q.; Sponsler, M. B. Organometallics 1994,
13, 4176.
0276-7333/96/2315-0721$12.00/0 © 1996 American Chemical Society

722 Organometallics, Vol. 15, No. 2, 1996
Sato et al.
Sch em e 1
F igu r e 1. ORTEP view for one of the molecules of complex
3.
Ta ble 1. Selected Bon d Dista n ces a n d Bon d
An gles for Com p lex 3
Bond Distances (Å)
Fe(1)-P(1)
Fe(1)-C(1)
Fe(1)-C(14)
Fe(1)-C(16)
C(1)-C(2)
2.159(3)
Fe(1)-P(2)
Fe(1)-C(13)
Fe(1)-C(15)
Fe(1)-C(17)
C(2)-C(3)
2.155(3)
1.190(11)
2.111(12)
2.122(12)
1.196(16)
2.094(12)
2.119(10)
2.110(13)
1.455(17)
Bond Angles (deg)
P(1)-Fe(1)-P(2)
P(2)-Fe(1)-C(1)
C(1)-C(2)-C(3)
86.7(2)
83.1(4)
176.4(12)
P(1)-Fe(1)-C(1)
Fe(1)-C(1)-C(2)
Fe(2)-C(3)-C(2)
89.9(4)
177.0(9)
126.2(8)
and 4.26 (5H), the methyl protons of the Cp* ring at δ
1.75 (15H), those of dmpe at δ 0.95 (6H) and 1.49 (6H),
and the methylene protons of dmpe at δ 1.03 (2H) and
1.90 (2H). In the 13C NMR spectrum (C6D6) of 7, signals
due to the ferrocenyl ring carbons appeared at δ 66.33,
69.37, 69.91, and 70.51, the ring carbons of Cp* at δ
86.40, the methyl carbons of Cp* at 11.10, those of dmpe
at δ 16.84 and 18.42, the methylene carbons of dmpe at
δ 30.02, and the aceylene carbons at δ 77.50 and 108.10.
Str u ctu r e. For complex 3, a single-crystal X-ray
diffraction study was carried out to confirm the struc-
ture. The crystal, which was obtained by recrystalli-
zation from CH2Cl2/hexane, contained two independent
molecules in its unit cell. Because of the large disorder
in the cyclopentadienyl rings of the ferrocene moiety in
one of the molecules, the ORTEP view and the selected
structural data of only one molecule are offered in
Figure 1 and Table 1, respectively. Ferrocenylacetylene
is bonded at the terminal carbon to the iron atom in
the Cp(dppe)Fe- part. The Fe-C(1) distance is 1.910
Å, which is similar to that in other Fe acetylides (e.g.
1.900(7) Å in Cp(dppm)FeCtCPh,12 1.920(6) Å in Cp-
(CO)2FeCtCPh13). The ferrocenylacetylide ligand is
bonded almost linearly to the metal (Fe-C(1)-C(2),
177.0(9)°; C(1)-C(2)-C(3), 176.4(12)°). The C(1)-C(2)
distance (1.196(16) Å) remains in the range for CtC
bond lengths in metal acetylide complexes (1.18-1.24
Å).14 The coordination around the Fe atom of the Cp
ligand, the two P atoms of the chelating dppe molecule,
and the terminal carbon C(1) of the ferrocenylacetylide
ligand can be described as a three-legged piano stool.
The angle involving the two phosphine-containing legs,
P(1)-Fe(1)-P(2) (86.7(2)°), is significantly larger than
Resu lts a n d Discu ssion
Syn th eses a n d Ch a r a cter iza tion . The key start-
ing materials are Cp(CO)2FeCtCFc (1) and Cp*-
(CO)2FeCtCFc (2) (Cp ) η-C5H5 and Cp* ) η-C5Me5),
which were reported in a previous paper.7 A yellow
solution of 1 in acetonitrile was irradiated with a 100
W high-pressure Hg lamp to give the thermally stable
complex Cp(dppe)FeCtCFc (3), in 71% yield (dppe )
bis(diphenylphosphino)ethane). Cp(dppm)FeCtCFc (5)
and Cp(dmpe)FeCtCFc (6) were prepared similarly
(dppm ) bis(diphenylphosphino)methane and dmpe )
bis(dimethylphosphino)ethane). Cp*(dppe)FeCtCFc (4)
and Cp*(dmpe)FeCtCFc (7) were obtained in moderate
yield from the photolysis of 2 with dppe and dmpe,
respectively, in the same manner as for the Cp series.
Generally, the photolysis of carbonyl complexes with a
Cp ligand has been used extensively as an efficient
method to obtain other carbonyl-free species, but there
are only a few successful examples in which an Fp*
diphos compound has thus been prepared.11 Accord-
ingly, it is worth noting that complexes 3-7 are readily
prepared by photoirradiation. In addition, complex 3
could be prepared by the reaction of FcCtCLi with Cp-
(dppe)FeI in 64% yield, but complex 4 could not be
isolated in a similar reaction. The composition and
structures of these complexes were determined by
elemental analyses and IR and 1H and 13C NMR
spectra. For example, in the IR spectrum of 7, the CtC
stretching vibration was observed at 2044 cm-1. The
1H NMR spectrum (C6D6) of 7 exhibited signals assigned
to the ferrocenyl ring protons at δ 3.98 (2H), 4.29 (2H),
(12) Camesa, M. P.; Gimeno, J .; Lastra, E.; Lanfranchi, M.; Tirip-
icchio, A. J . Organomet. Chem. 1991, 405, 333.
(13) Goddard, R.; Howard, J .; Woodward, P. J . J . Chem. Soc., Dalton
Trans. 1974, 2025.
(11) (a) Ruiz, J .; Roma´n, E.; Astruc, D. J . Organomet. Chem. 1987,
322, C13. (b) Roger, C.; Hamon, P.; Toupet, L.; Rabaa, H.; Saillard,
J .-Y.; Hamon, J .-R.; Lapinte, C. Organometallics 1991, 10, 1045.
(14) Nast, R. Coord. Chem. Rev. 1982, 47, 89.

Fe(II) Ferrocenylacetylide Diphosphine Complexes
Organometallics, Vol. 15, No. 2, 1996 723
Ta ble 2. Red ox P oten tia ls (V) of Com p lexes 3-7
in 0.1 M (n -Bu )4NClO4/CH2Cl2 a t 0.1 V s-1 (vs
F cH/F cH+)a
Sch em e 2
compd
E1/2(1)
E1/2(2)
3
4
5
6
7
-0.47
-0.61
-0.50
-0.70
-0.84
+0.12
+0.11
+0.12
+0.10
+0.08
+0.13
FcCtCPh
Cp(dppe)FeCtCPh
-0.36
a
FcH/FcH+ couple: +0.18 V vs Ag/Ag+.
that in Cp(dppm)FeCtCPh (74.8(2)°),12 reflecting that
the former contains a five-membered chelate ring but
the latter a four-membered chelate ring. The Fe(1)-
Fe(2) distance is 6.065 Å, which is similar to that in
the Ru analog [Cp(Ph3P)2RuCtCFc]PF6.8a
Red ox Beh a vior . The redox behavior of 3-7 and
the reference compounds was examined using cyclic
voltammetry. All measurements were carried out at a
scan rate of 100 mV s-1 in a solution of 0.1 M (n-Bu)4-
NClO4 in acetonitrile, and the results are summarized
in Table 2. For example, the cyclic voltammogram of 3
showed two quasi-reversible waves at E1/2 ) -0.47 and
+0.12 V (vs FcH/FcH+). The lower potential wave is
assigned to the redox wave of the Cp(dppe)Fe- moiety
and the other to the ferrocenyl moiety. These assign-
ments are based on the reference compounds Cp(dppe)-
FeCtCPh and ferrocenylphenylacetylene which gave
reversible waves at E1/2 ) -0.36 and +0.13 V, respec-
tively. Complexes 4-7 also showed behavior similar to
that of 3. The redox potentials in these complexes are
strongly influenced by the type of ligands around the
Fe(II) atom. In a comparison of complexes 4 and 7 with
3 and 6, respectively, the replacement of the Cp ligand
by the Cp* ligand results in the shift of the first redox
potential to lower potential by 0.14 V. Furthermore,
the first redox potential of the dmpe series (6 and 7) is
lower by 0.23 V compared with that of the dppe series
(3 and 4). This is probably due to the greater electron-
donating capability of Cp* and dmpe ligands, compared
with that of Cp and dppe ligands, respectively. In these
complexes, a large difference was observed between the
first and second redox potentials. Usually, ∆E can be
used to calculate the comproportionation constant (Kc)
according to eq 1,where ∆E ) E1/2(2) - E1/2(1) (mV).15
such a treatment. However, the Kc value calculated for
3 by the above treatment is only 49, much smaller than
that expected from other data (vide infra), indicating
that the treatment described above is not appropriate
for such a dissymmetric system or that an unknown
factor lowers the E1/2(2) value for 3, resulting in the
small Kc value.
Oxid a tive Beh a vior . The complexes 3 and 5 were
oxidized with 1 equiv of DDQ (2,3-dichloro-5,6-dicy-
anobenzoquinone) (E1/2 ) +0.14 V) in CH2Cl2/benzene
to respectively give the one-electron-oxidized species 8a
and 10a as stable compounds, at least in the solid state,
-
in good yield. Similarly, oxidation of 3-6 with FcH+PF6
(E1/2 ) 0.0 V) in CH2Cl2 gave the corresponding one-
electron-oxidized products 8b-11b in good yield, which
were characterized by IR spectroscopy and elemental
analysis. For example, the IR spectrum of 8a showed
the CtN, CtC, and CdO stretching frequencies at
2204, 1956, and 1580 cm-1, respectively.
Kc ) exp((∆E)F/RT) ) exp(∆E/25.69)
(1)
Kc calculated for complexes 3-7 is typically g1010, this
result being mainly due to substantial redox dissym-
metry rather than to delocalization. If the difference
between the half-wave potentials of the reference com-
pounds (e.g., Cp(CO)2FeCtCPh and FcCtCPh) is sub-
tracted from ∆E of complex 3 in order to compensate
for the dissymmetry, the ∆∆E value obtained may be
used to calculate the constant Kc. The application of
such a treatment to complex 2 afforded a Kc value of
3.9 × 106 for 2. This Kc value is near that calculated
using the ∆E value reported for biferrocene (Fc-Fc), 9.3
× 105, and is much larger than that for diferrocenyl-
acetylene (FcCtCFc), 1.6 × 102, whose one-electron-
oxidized species is classified as a class II type of mixed-
valence complex.16 This fact suggests the validity of
Nea r -In fr a r ed Sp ectr a . All oxidized complexes
described above showed a broad absorption in the near-
IR region. The near-IR spectra of 8a and 10a , along
with those of 1a and 2a , are shown in Figure 2, and
the near-IR spectral data are summarized in Table 3.
Meyer et al.17 reported that in the case of the near-IR
bands observed for the mixed-valence complexes [FcsFc]+
and [FcCtCFc]+ their transition energy (νmax) was
2
proportional to the solvent dielectric function, 1/Dop
-
1/Ds, where Dop and Ds are optical and statistical
dielectric constants of the solvent involved, respectively.
(16) Le Vanda, C.; Bechgaad, K.; Cowan, D. C. J . Organomet. Chem.
1976, 41, 2700.
(15) Richardson, D. E.; Taube, H. Inorg. Chem. 1981, 20, 1278.
(17) Powers, M. J .; Meyer, T. J . J . Am. Chem. Soc. 1978, 100, 4393.

724 Organometallics, Vol. 15, No. 2, 1996
Sato et al.
F igu r e 2. Near-IR spectra of 1a (- - -), 2a (‚‚‚), 8a (s), and
10a (- - -) in CH2Cl2.
Ta ble 3. Nea r -IR Sp ectr a l Da ta for Com p lexes
8-11
1/Dop
1/Ds
-
λmax
νmax
R2
2
compd
solvent
CH2Cl2
(nm) (103 cm-1
)
ꢀmax (×10-2
)
a
8a
0.380
0.382
0.489
0.496
0.526
1590
1590
1510
1470
1470
1590
1595
1595
1295
6.29
6.29
6.62
6.80
6.80
6.29
6.27
6.27
7.72
3060
2240
2690
2370
2150
3400
2260
2700
1630
2.31
1.96
2.25
1.85
1.80
2.44
1.98
2.26
0.98
CD2Cl2
CH3NO2
CH3COCH3
CH3CN
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
8b
10a
10b
11b
a
Reference 14.
According to the Hush theory, the mixed-valence com-
plexes display low-energy (near-IR) absorption bands
which are assigned to intervalence transfer (IT) transi-
tion and exhibit the solvent effect described above. As
shown in Table 3 and Figure 3, a linear correlation is
F igu r e 3. Plots of νmax for 8a (upper) and 1a (bottom) vs
2
1/Dop - 1/Ds for the solvent used.
2
observed between νmax of complex 8a and 1/Dop - 1/Ds
of the solvent used, reasonably meaning that the near-
IR bands of the one-electron-oxidized complexes 8-11
can be assigned as the IT band of mixed-valence
complexes. The linear slope (3.7 × 103 cm-1) for 8a in
Figure 3 is smaller than that (4.4 × 103 cm-1) found for
the one-electron-oxidized species (1a ) of 1.7 It has been
reported that the stabilization of a mixed-valence
complex by solvation is strongly dependent on the extent
of electron delocalization in the system. The larger the
interaction between the metals in the mixed-valence
complex was, the smaller the influence of solvent on the
IT band became.3d,17 Thus, complexes 8-11, with a
phosphine ligand, seem to have a greater interaction
between the two iron atoms than the carbonyl analog
1a . Then, the interaction parameter R2, which gives an
approximate measure for the degree of ground-state
delocalization in a mixed-valence complex, was calcu-
lated for complexes 8-11 using eq 2, where ∆ν1/2 is the
analogous carbonyl complexes (e.g. R2 < 6.4 × 10-3).7
This suggests that there is greater electron delocaliza-
tion between two Fe centers in the phosphine complexes
8-11 than in the carbonyl complexes, which is consis-
tent with the consideration from the solvent effect
described above. The large electron delocalization in the
oxidized species (8-11) of the phosphine complexes 3-6
compared with that of the carbonyl complex 1 may be
explained as follows. The MO calculation19 and the PE
spectrum of Cp(CO)2FeCtCR20 indicate that the HOMO
is an essentially metal-based orbital mixed with the
acetylenic π bond. In other words, the d orbital on the
Fe atom in the Cp(CO)2Fe part can easily interact with
the acetylenic π orbital. This seems to be the case in
the complex Cp(Ph3P)2FeCtCR. In ferrocene, the e1g
(or e1u) orbital of the Cp ligand which can interact with
the acetylenic π orbital forms the molecular orbital by
coupling with the dxz or dyz orbital of the iron atom, but
this orbital is not the HOMO.21 As shown by the CV
measurement, the first oxidized site of 3 is the Cp-
(dppe)2Fe part (vide supra). Therefore, it is suggested
that in the oxidized species of 3 the unpaired electron
is easily delocalized into the acetylenic π bond, because
R2 ) [(4.2 × 10-4)ꢀmax∆ν1/2]/νmaxd2
(2)
half-width of the IT absorption band and d is the
intermetallic distance.18 In this case, the internuclear
distance (6.065(3) Å) observed for complex 3 was used
as the value of d. The results are summarized in Table
3, along with the values of λmax, νmax, and ꢀmax. The
values of R2 for 8-11 are much larger than those of the
(19) Kostic, N. M.; Fenske, R. F. Organometallics 1982, 1, 974.
(20) Lichtenberger, D. L.; Renshaw, S. K.; Bullock, R. M. J . Am.
Chem. Soc. 1993, 115, 3276.
(21) (a) Lauher, J . W.; Hoffmann, R. J . Am. Chem. Soc. 1976, 98,
1729. (b) Evans, E.; Green, M. L. H.; J ewitt, B.; Orchard, A. F.; Pygall,
C. F. J . Chem. Soc., Faraday Trans. 2 1972, 68, 1847.
(18) (a) Hush, N. S. Prog. Inorg. Chem. 1967, 8, 391. (b) Creutz, C.
Prog. Inorg. Chem. 1983, 28, 1.

Fe(II) Ferrocenylacetylide Diphosphine Complexes
Organometallics, Vol. 15, No. 2, 1996 725
Ta ble 4. IR Sp ectr a l Da ta for Com p lexes 8-11
the HOMO is the mixed orbital between the metal d
orbital and the acetylenic π orbital, and then into the
compd
νCC (cm-1
)
∆νa
compd
νCC (cm-1
)
∆νa
Fe atom of the ferrocene moiety through the e1g (or e1u
)
8a
8b
9b
1956
1960
1964
116
112
96
10a
10b
11b
1966
1970
1976
98
94
76
MO. In agreement with this idea, the STO-3G calcula-
tion using the Gaussian software package22 for Cp(PH3)2-
FeCtCFc (3′) in which the atomic coordinates in the
molecule are based on those of the X-ray analysis of the
complex 3 showed a remarkable contribution of the
metal d orbital of the Cp(PH3)2Fe- part to the HOMO
in molecule 3′. The NBO charges23 of +1.53 and +1.39
on the Fe atoms in the Fc and Cp(PH3)2Fe parts in the
molecule 3′, respectively, suggest that the electron is
removed from the Cp(PH3)2Fe- site and can be delo-
calized to the Fc part. On the other hand, according to
the CV measurement, the first oxidized site of carbonyl
complex 1 is the Fc part. That is, the electron is
a
The difference between the neutral and the oxidized species.
that a facile electron transfer takes place between the
two metal sites in complexes 8-11, as well as in the
analogous complex [FcCtCRu(PPh3)2(η-C5H5)]BF4 (R2
) 1.3 × 10-2).8a
Hush has shown that the half-width (∆ν1/2) and the
peak position (νmax) of the IT absorption can be used to
evaluate the zero-point energy difference (ν0) and the
thermal energy barrier (Eth) between metal sites in a
mixed-valence complex (ν in 103 cm-1 and T ) 300 K):
2
2
removed from the HOMO of ferrocene (a dx -y orbital
of e2g symmetry).24 In the oxidized species of 1 the
unpaired electron generated in the ferrocene moiety is
considered to be difficult to delocalize to the acetylenic
ν0 ) νmax - [(∆ν1/2)2/16kT ln2]
) νmax - [(∆ν1/2)2/2.13]
(3)
(4)
2
2
π bond because the HOMO is a dx -y orbital which
interacts very little with a dxz or dyz orbital of e1g
symmetry. Therefore, the unpaired electron on the Fe
atom in the Fc part can scarcely be delocalized to the
Fe atom in the Cp(CO)2Fe part in 1. Thus, the electron
delocalization in the oxidized species of 3 seems to be
due to electron removal from the metal d orbital in the
Cp(Ph3)2Fe part coupled with the acetylenic π orbital
and effective conjugation with the e1g orbital of the Cp
ligand coupled with the dxy or dxz orbital of the Fe atom
in the ferrocene moiety. A comparable electron delo-
calization observed in Cp(Ph3P)2RuCtCFc seems to be
explicable similarly.8a Also, an increase of the electron
density in the whole system through the displacement
of CO by the phosphine ligand may contribute to the
electron delocalization by the stabilization of the radical
cation formed. As a supporting fact, the electron
delocalization increased linearly with the electron do-
nating ability of the substituents in the Pt(II) analogs
FcCtCPt(PPh3)2(C6H4-X-p).8c Complex 11 with the
dmpe ligand, which has the strongest s-donating ability
of the diphosphine ligands used, shows a value of R2
rather smaller than the others. This phenomenon
cannot be elucidated clearly at present but seems to
suggest the importance of factors other than the elec-
tronic effect (e.g., the remarkable dissymmetry in the
electronic structure (∆E ) 0.8 V) may be concerned with
the IT transition between the metals in this kind of
oxidized complex). The R2 values observed in 8-11 are
also considerably larger than those for the oxidized
species of other binuclear complexes which have a
similar internuclear distance and are classified as class
II mixed-valence complexes: 2.4 × 10-3 in [FcCtCFc]-
PF6,17 2.3 × 10-3 in [FcCtNRu(NH3)5](PF6)3,25 and 2.7
× 10-3 in [FcCtCCCo3(CO)6L3]BF4.26 This suggests
Eth ) [(νmax)2/4(νmax - ν0)]
Furthermore, according to Brown’s proposal,27 the ther-
mal rate constant (kth) for thermal electron transfer
between the metal sites separated by a thermal energy
barrier (Eth) is approximated as follows:
kth ) (kT/h) exp(-Eth/RT)
(5)
The values of kth for the electron transfer in the oxidized
complexes 8-11 were calculated using the eqs 3-5 in
turn. These values in CH2Cl2 were given as follows: 8a ,
9.1 × 109 s-1; 8b, 4.4 × 109 s-1; 10a , 5.0 × 1010 s-1
;
10b, 3.1 × 1010 s-1; 11b, 4.2 × 108 s-1. However, the
value of Eth obtained by eq 3 actually can become
smaller because the coupling energy Hab is neglected
in Hush’s model and, therefore, electron-transfer of
8-11 in CH2Cl2 probably occurs at a faster rate than
the kth stated above (e.g. 8 and 10, g1011 s-1; 11, g109
s-1). In any case, this suggests that the electron is
transferred at a very fast rate between the metal nuclei
in these complexes, although the rate for thermal
electron transfer is somewhat smaller than that for
nuclear frequency (1012 s-1). That is, the electron is
delocalized, in an unequal but certain ratio, between two
iron atoms. Thus, complexes 8-11 can be considered
to be mixed-valence complexes close to a type of class
III.
In fr a r ed Sp ectr a . The IR spectral data are sum-
marized in Table 4. The absorptions assigned to the
CtC stretching vibration in the one-electron-oxidized
complexes 8-11 were observed near 1960 cm-1 as a
strong and broad band. This is in striking contrast to
the weak and sharp absorption observed at 2050-2070
cm-1 for the neutral complexes 3-7, and the position
is about intermediate between that of the neutral
species and the allenylidene complex, [Ru(CdCdC-
Ph2)(PMe3)2Cp]PF6 (12; 1926 cm-1).28 If electron trans-
fer between two metal sites takes place faster than on
the IR time scale (1012 s-1), only one absorption band
averaged between the two limiting species A and B
should be observed for the CtC stretching vibration.
(22) Frish, M. J .; Trucks, G. M.; Head-Gordon, M.; Gill, P. M.; Gill,
P. M. W.; Wong, M. W. Foresman, J . B.; J ohnson, B. G.; Schlegel, H.
B.; Robb, M. A.; Replogle, E. S.; Gompertes, R.; Andres, J . L.;
Raghavachari, K.; Binkley, J . S.; Gonzalez, C.; Martin, R. L.; Fox, D.
J .; Defrees, D. J .; Baker, J .; Stewart, J . J . P.; Pople, J . A. Gaussian
92, Revision D.3; Gaussian Inc.: Pittsburgh, PA, 1992.
(23) Read, A. E.; Weinstock, R. B.; Weinhold, F. J . Chem. Phys. 1985,
83, 735.
(24) Prins, R. Mol. Phys. 1970, 19, 603.
(25) Dowling, N.; Henry, P. M.; Lewis, N. A.; Taube, H. Inorg. Chem.
1981, 20, 2345.
(26) Kotz, J .; Neyhart, G.; Vining, W. J .; Rausch, M. D. Organome-
tallics 1983, 2, 79.
(27) Brown, G. M.; Sutin, N. J . Am. Chem. Soc. 1979, 101, 883.
(28) Selegue, J . P. Organometallics 1982, 1, 217.

726 Organometallics, Vol. 15, No. 2, 1996
Sato et al.
F igu r e 4. ESR spectrum of 8a in CH2Cl2 at 5.5 K.
Sch em e 3
Recently, it was reported that the value of νCC, ac-
companying the conversion of the MCtCCtCM com-
plex to its one-electron-oxidized species, was shifted to
an averaged frequency between the neutral and the
dioxidized species because of the rapid electron transfer
(>1012 s-1) in the system.4c,29 Complexes 8-11 exhib-
ited a similar shift of νCC to lower wavenumber by ca.
100 cm-1. This may suggest that the electron transfer
between the two Fe atoms is very rapid, on the IR time
scale. However, we could not confirm this possibility,
since the dioxidized species of complexes 3-7 were not
available because of their instability. The shift to lower
wavenumber from the corresponding neutral complex
decreased in the following order: 8 > 9 > 10 > 11. This
order is parallel to that of the rate of thermal electron
transfer calculated from the near-IR spectral data.
Therefore, the IR spectral data also seem to support the
suggestion from the near-IR spectra that complexes
8-11 may be classified as the mixed-valence type close
to a type of class III.
ESR Sp ectr a . The ESR spectra of 8a were measured
in both the solid state and CH2Cl2 solution at 5.5 K and
room temperature. However, in either case only one
signal with a width of ca. 1000 G was observed, as
shown in Figure 4. This is in great contrast to the case
of the carbonyl complex 1a , which showed two signals
at g| ) 3.81 and g ) 1.68, suggesting localization of
the radical cation on its ferrocenyl part.7 According to
the result obtained in cyclic voltammetry, the first
oxidation site in complex 3 is the CpFeP2 part. If the
radical cation is localized there on the ESR time scale
(10-9 s), anisotropy of the g value (two g values, as for
FeCp*(dppe)Me+) ought to be observed in complex 8,
because an Fe(III) half-sandwich complex has axis
symmetry.30 As seen clearly in Figure 4, only one signal
with g ) 2.09 appeared in the ESR spectrum of complex
F igu r e 5. Mo¨ssbauer spectra of 3 (upper) and 8b (bottom).
Ta ble 5. Mo1ssba u er P a r a m eter s for Com p lexes 3,
6, a n d 8-11
IS
QS
IS
QS
compd (mm s-1
)
(mm s-1
)
compd (mm s-1
)
(mm s-1
)
3
0.28
0.49
0.23
0.54
0.19
0.55
1.77
2.41
1.77
2.40
0.86
2.00
9b
10b
11b
0.25
0.53
0.15
0.53
0.15
0.53
0.96
2.19
0.91
2.22
1.00
2.26
6
8b
8. We also observed no temperature dependence in the
ESR spectra of 8. Therefore, it is considered that the
rate of the electron transfer in 8 is faster than 10-9
s
even at 5.5 K. This result seems to be consistent with
the IR and near-IR spectral data. The small signal near
3250 G is probably due to the DDQ radical anion.
Mo1ssba u er Sp ectr a . The Mo¨ssbauer spectra of 3,
6, and 8-11 were measured at 77 K, and the results
are summarized in Table 5. The spectra of the neutral
complex 3 and the oxidized complex 8b are shown in
Figure 5. In the spectra of 3 and 6 two doublets were
observed, whose QS values are consistent with those of
ferrocene derivatives (ca. 2.42 mm s-1) and a half-
sandwich complex, Cp*(dppe)FeMe (1.82 mm s-1).30
These indicate that two Fe(II) atoms exist in complexes
3 and 6. On the other hand, in the one-electron-oxidized
complex 8b, two doublets with QS ) 0.86 and 2.00 mm
s-1 were observed, as seen in Figure 5. In comparison
with the reference complex, [Cp*(dppe)FeMe]PF6 (0.76
mm s-1),30 the doublet of QS ) 0.86 mm s-1 is assigned
to the half-sandwich unit in 8b. This confirms that the
oxidized site in 8 is the iron atom in the half-sandwich
unit, not the one in the ferrocenyl part, as well as the
above-mentioned discussions. The QS value (2.00 mm
s-1) of the doublet due to the ferrocenyl moiety is smaller
than that (2.41 mm s-1) of the neutral complex 3. Such
(29) Seyler, J . W.; Weng, W.; Zhou, Y.; Gladysz, J . A. Organome-
tallics 1993, 12, 3802.
(30) Roger, C.; Hamon, P.; Toupet, L.; Rabaa, H.; Saillard, J .-Y.;
Hamon, J .-R.; Lapinte, C. Organometallics 1991, 10, 1045.

Fe(II) Ferrocenylacetylide Diphosphine Complexes
Organometallics, Vol. 15, No. 2, 1996 727
(2)7 were prepared according to the methods described in the
literature. All experiments were performed in a nitrogen-
saturated solvent under nitrogen.
a low value for a neutral ferrocene derivative is unprec-
edented. This may be explained as follows: the fast
electron transfer between two iron atoms occurs over
the time scale of the Mo¨ssbauer measurement (10-7 s)
in complex 8b, so that the QS value of the iron atom in
both sites approaches the averaged value. That is, the
QS value of the neutral site decreases and that of the
radical cation site increases. In fact, such a tendency
was observed in the monocations of [0.0]ferrocenophane
(QS ) 1.78 mm s-1),31 [2.2]ferrocenophane-1,13-diyne
(QS ) 1.61 mm s-1),31 and [Cp*(dppe)Fe]2C4 (QS ) 1.32
mm s-1),4c which were classified as class III mixed-
valence complexes. However, this explanation is some-
what uncertain, because the QS value (0.86 mm s-1) of
the Cp(dppe)Fe site in complex 3 is rather close to that
(0.76 mm s-1) of the reference complex [Cp*(dppe)FeMe]-
PF6.30 Complete averaging of the QS values of two iron
sites may not appear in a dissymmetric molecule even
if a fast electron transfer exists between the metal sites.
While the near-IR data of complex 10 are indicative of
the existence of fast electron transfer as in complex 8,
the QS value (2.22) of 10b is relatively larger than that
of 8b. For the present, we suppose that it is due to the
structural strain at the methylene moiety of dppm in
the solid state.
(η-C5H5)(d p p e)F eCtCF c (3). (a) A solution of complex 1
(50 mg, 0.13 mmol) and dppe (55 mg, 0.14 mmol) in acetonitrile
(40 mL) was irradiated with a 100 W high-pressure Hg lamp
for 30 min at 0 °C under bubbling of nitrogen. After the
solution had been concentrated to a small volume, it was
filtered. The filtrate was evaporated, and the residue was
recrystallized from CH2Cl2/hexane: red crystals (67 mg, 71%);
mp 207 °C. Anal. Calcd for C43H38P2Fe2: C, 70.90; H, 5.25.
Found: C, 70.67; H, 5.33. IR (KBr): 2072 cm-1
.
1H NMR
(CDCl3): δ 2.31 (m, 2H, CH2), 2.76 (m, 2H, CH2), 3.76 (s, 2H,
Fc), 3.67 (s, 5H, Fc unsub), 3.62 (s, 2H, Fc), 7.24-8.0 (m, 20H,
Ph). 13C NMR (CDCl3): δ 28.57 (t, J ) 24.1 Hz, CH2), 65.63
(Fc), 66.51 (Fc unsub), 69.24 (Fc), 70.02 (Fc ipso), 79.00 (η-
C5H5), 127.48, 127.66 (Ph p), 128.62, 129.13 (Ph m), 131.70,
134.08 (Ph o), 138.02 (t, J ) 23 Hz, Ph ipso), 142.44 (m, Ph
ipso).
(b) Ferrocenylacetylene (84 mg, 0.4 mmol) and (η-C5H5)-
(dppe)FeI (150 mg, 0.23 mmol) were dissolved in dry THF (3
mL) under nitrogen, and the solution was chilled in an ice-
water bath. To the solution was slowly added methyllithium
(0.8 mL of 1.4 M solution in diethyl ether, 1.12 mmol). After
it was stirred for 15 min, the solution was evaporated. The
residue was chromatographed on deactivated alumina to give
the title complex (107 mg, 64%) as red crystals after recrys-
tallization from CH2Cl2/hexane: mp 207 °C.
Su m m a r y. Some Fe(II) ferrocenylacetylide com-
plexes with a diphosphine ligand were prepared by
photolysis of the corresponding carbonyl complexes in
the presence of the diphosphines in excellent yield.
Their one-electron oxidation provided a new type of
mixed-valence complex. The one-electron-oxidized com-
plexes 8-11 showed behavior close to class III of mixed-
valence compounds in all measurements (IR, near-IR,
ESR, and Mo¨ssbauer spectra). In dissymmetric com-
plexes, to the best of our knowledge, there are few
instances that have as large an electron delocalization
as in complexes 8-11.
(η-C5H5)(d p p m )F eCtCF c (5). This complex was prepared
in a method similar to that used for complex 3: red crystals
(64%); mp 170-180 °C dec. Anal. Calcd for C42H36P2Fe2: C,
70.61; H, 5.07. Found: C, 70.41; H, 5.09. IR (KBr): 2064 cm-1
(CtC). 1H NMR (CDCl3): δ 3.92 (m, 2H, CH2), 3.40 (bs, 2H,
Fc), 3.58 (s, 5H, Fc unsub), 3.71 (bs, 2H, Fc), 4.39 (s, 5H,
η-C5H5), 7.26-7.80 (m, 20H, Ph). 13C NMR (CDCl3): δ 44.26
(CH2), 65.85 (Fc â), 68.50 (Fc unsub), 69.94 (Fc R), 76.47 (η-
C5H5), 127.75-139.10 (Ph).
(η-C5H5)(d m p e)F eCtCF c (6). This complex was prepared
a similar manner. Crystallization from ether/hexane
in
provided complex 6 as an orange powder (80%): Mp 160-162
°C dec. Anal. Calcd for C23H30P2Fe2: C, 57.53; H, 6.29.
Found: C, 57.07; H, 6.48. IR (KBr): 2052 cm-1 (CtC). 1H
NMR (CDCl3): δ 1.45, 1.75 (bs, 12H, CH3), 1.62, 1.95 (m, 4H,
CH2), 3.91 (bs, 2H, Fc), 4.05 (bs, 2H, Fc), 4.07 (s, 5H, Fc unsub),
and 4.16 (s, 5H, η-C5H5). 13C NMR (CDCl3): δ 19.09, 20.56
(CH3), 29.42 (CH2), 66.40 (Fc â), 69.42 (Fc unsub), 69.82 (Fc
R), 77.05 (η-C5H5), 77.39, 110.42 (CtC).
(η-C5Me5)(d p p e)F eCtCF c (4). A solution of complex 2
(50 mg, 0.11 mmol) and dppe (44 mg, 0.11 mmol) in diethyl
ether (20 mL) and hexane (20 mL) was irradiated with the
same lamp used in the Cp series for 15 min at 0 °C under
bubbling of nitrogen. The solution was purified in a manner
similar to that used for complex 3: red-orange crystals (54
mg, 62%); mp 207 °C dec. Anal. Calcd for C48H48P2Fe2: C,
72.19; H, 6.05. Found: C, 71.95; H, 6.28. IR (KBr): 2060 cm-1
(CtC). 1H NMR (CDCl3): δ 1.32 (s, 15H, η-C5Me5), 1.92, 2.73
(m, 4H, CH2), 3.89 (bs, 2H, Fc), 3.91 (s, 5H, Fc unsub), 3.98
(bs, 2H, Fc), 7.24-7.96 (m, 20H, Ph). 13C NMR (CDCl3): δ
9.84 (η-C5Me5), 88.28 (η-C5Me5), 27.60 (CH2), 66.98 (Fc â), 68.74
(Fc unsub), 72.00 (Fc R), 127.09-138.69 (Ph).
(η-C5Me5)(d m p e)F eCtCF c (7). This complex was simi-
larly prepared in acetonitrile and crystallized from diethyl
ether/hexane at -78 °C: orange powder (67%); mp 146 °C.
Anal. Calcd for C28H40P2Fe2: C, 61.11; H, 7.32. Found: C,
60.81; H, 7.34. IR (KBr): 2044 cm-1 (CtC). 1H NMR (C6D6):
δ 0.95, 1.49 (bs, 12H, CH3), 1.75 (s, 15H, η-C5Me5), 1.03, 1.90
(m, 4H, CH2), 3.98 (bs, 2H, Fc), 4.26 (s, 5H, Fc unsub), 4.29
(bs, 2H, Fc). 13C NMR (C6D6): δ 11.10 (η-C5Me5), 88.28 (η-C5-
Me5), 16.84, 18.42 (CH3), 30.02 (CH2), 66.33 (Fc â), 69.37 (Fc
unsub), 69.91 (Fc R), 70.51 (Fc ipso), and 77.50, 108.10 (CtC).
[(η-C5H5)(d p p e)F eCCF c]+[C6H4Cl2(CN)2]- (8a ). To a
solution of complex 3 (60 mg, 0.082 mmol) in CH2Cl2 (1.5 mL)
Exp er im en ta l Section
Visible and near-infrared spectra were recorded on a Shi-
madzu 365 spectrometer and IR spectra on a Hitachi 270-50
spectrometer. 1H and 13C NMR spectra were measured on a
Bruker AM400 spectrometer. Electrochemical measurements
were made by cyclic voltammetry in a solution of 0.1 M (n-
Bu)4NClO4 in CH2Cl2 or acetonitrile under nitrogen at 25 °C,
using a standard three-electrode cell on a BAS CV-27 analyzer.
All potentials were measured vs a Ag/AgNO3 (0.05 M) elec-
trode, and the scan rate was 100 mV/s. ESR spectra were
measured on a J EOL J ES-PE-3X spectrometer. Mo¨ssbauer
spectra were measured with a constant-acceleration type
spectrometer, and the velocity scale was calibrated on the
spectrum of metallic iron at room temperature. Spectra were
fitted with Lorentzian line shapes by least squares. The
isomer shifts were reported with respect to R-Fe foil at room
temperature. The error of the values of isomer shift and
quadrupole splitting was estimated as within (0.02 mm s-1
.
Ferrocenylacetylene,32 (η-C5H5)(CO)2FeI,33 (η-C5Me5)(CO)2-
FeI,34 (η-C5H5)(CO)2FeCtCFc (1), and (η-C5Me5)(CO)2FeCtCFc
(31) (a) Motoyama, I.; Watanabe, M.; Sano, H. Chem. Lett. 1978,
513. (b) Kramer, J . A.; Hendrickson, D. N. Inorg. Chem. 1980, 19,
3330.
(32) (a) Schlo¨gl, K.; Steyrer, W. Monatsh. Chem. 1965, 96, 1521. (b)
Rosenblum, M.; Brawn, N.; Papenmeier, J .; Applebaum, M. J . Orga-
nomet. Chem. 1966, 6, 173.
(33) King, R. B. Organometallic Synthesis; Academic Press: New
York, 1965; Vol. 1, p 175.
(34) Akita, M.; Terada, M.; Oyama, S.; Moro-oka, Y. Organometallics
1990, 9, 816.

728 Organometallics, Vol. 15, No. 2, 1996
Sato et al.
and benzene (20 mL) was added slowly a solution of dichlo-
rodicyanobenzoquinone (DDQ; 20 mg, 0.088 mmol, freshly
recrystallized from CH2Cl2) in benzene (13 mL) on an ice-
water bath under nitrogen. After the mixture was stirred for
15 min, dry hexane (50 mL) was added slowly to the solution.
The resulting deep blue crystals were filtered quickly: yield
46 mg (59%); mp ∼150 °C dec. Anal. Calcd for C51H38Cl2N2-
O2P2F2‚1/2CH2Cl2: C, 61.98; H, 3.93; N, 2.80. Found: C, 61.80;
10b (PP ) dppm): 94% yield; mp ca. 150 °C dec. Anal.
Calcd for C42H36F6P3Fe2: C, 58.70; H, 4.22. Found: C, 58.51;
H, 4.40. IR (KBr): 1970 cm-1 (CtC). Vis-near-IR (CH2Cl2):
647 (ꢀ 6220), 1595 nm (2700).
11b (PP ) dmpe): 94% yield; mp ca. 150 °C dec. Anal.
Calcd for C23H30F6P3Fe2: C, 44.19; H, 4.84. Found: C, 44.20;
H, 4.97. IR (KBr): 1976 cm-1 (CtC). Vis-near-IR (CH2Cl2):
590 (ꢀ 3870), 1295 nm (1630).
H, 4.04; N, 2.86. IR (KBr): 1956 cm-1
. Vis-near-IR (CH2-
Str u ctu r e Deter m in a tion . Crystal data for 3: C43H38P2-
Fe2, fw 728.40, monoclinic, P21/c (No. 14); a ) 17.190(3) Å, b
) 19.756(2) Å, c ) 21.851(4) Å; â ) 107.703(2)°; V ) 7069.3
Å3; Z ) 8; Dcalc ) 1.37 g/cm3; µ(Mo KR) ) 9.444 cm-1; T ) 298
K; crystal size 0.26 × 0.20 × 0.18 mm.
Cl2): 465 (ꢀ 6710), 600 (8170), 1590 nm (2240).
[(η-C5H5)(d p p m )F eCtCF c]+DDQ- (10a ). This complex
was prepared from complex 5 by a method similar to that used
for complex 8a : 85% yield; mp ca. 150 °C dec. Anal. Calcd
for C50H36N2O2Cl2P2Fe2: C, 63.79; H, 3.85; N, 2.98. Found:
C, 63.93; H, 4.13; N, 2.92. IR (KBr): 2208 (CtN), 1966 cm-1
(CtC). Vis-near-IR (CH2Cl2): 460 (ꢀ 5380), 593 (7200), 1595
nm (2260).
Oscillation and nonscreen Weissenberg photographs were
recorded on the imaging plates on a Mac Science DIP3000
diffractometer with graphite-monochromated Mo KR radiation
and an 18-kW rotating anode generator. Data reduction and
determination of cell parameters were made by the MAC
DENZO program system. Of 16 860 reflections collected,
16 437 reflections were unique, 7207 reflections of which with
I > 3.00σ(I) were used for refinement. The structure was
solved by direct methods using SIR92 in the CRYSTAN-GM
program system (software package for structure determina-
tion) and refined by a full-matrix least-squares procedure.
Hydrogen atoms were not located. Anisotropic refinement for
non-hydrogen atoms was carried out. R ) 0.088 and Rw )
0.090.
-
[(η-C5Me5)(d p p e)F eCtCF c]+P F 6 (9b). Complex 4 (50
mg, 0.063 mmol) was dissolved in CH2Cl2 (2 mL) and cooled
to -78 °C. To this solution was slowly added a solution of
-
FcH+PF6 (21 mg, 0.063 mmol) in CH2Cl2 (6 mL) under
nitrogen. The mixture was stirred for 15 min and then
concentrated under reduced pressure. The concentrated solu-
tion was cooled to -78 °C again. After addition of hexane to
the solution, the resulting deep blue precipitate was filtered:
yield 38 mg (64%); mp ca. 150 °C dec. Anal. Calcd for C48H48
-
F6P3Fe2‚1/2CH2Cl2: C, 59.08; H, 5.00. Found: C, 59.16; H, 5.37.
IR (KBr): 1964 cm-1 (CtC). Vis-near-IR (CH2Cl2): 410 (ꢀ
1380), 610 (2320), 1250 (1490), 1700 nm (828 sh).
-
Syn th esis of [(η-C5H5)(P P )F eCtCF c]+P F 6 (8b, 10b,
Su p p or tin g In for m a tion Ava ila ble: Tables giving crys-
tal data and data collection and refinement details, atomic
coordinates, bond distances and angles, torsion angles, thermal
parameters, and least-squares planes and deviations therefrom
and figures giving additional views and atom numbering for
3 (61 pages). Ordering information is given on any current
masthead page.
a n d 11b). These oxidized complexes were similarly prepared
from the respective neutral complexes 3, 5, and 6 according
to the method described above. Complex 11b is unstable in
hexane, and so ether was used instead.
8b (PP ) dppe): 71% yield; mp ca. 150 °C dec. Anal. Calcd
for C43H48F6P3Fe2‚1/2CH2Cl2: C, 57.04; H, 4.29. Found: C,
57.38; H, 4.40. IR (KBr): 1960 cm-1 (CtC). Vis-near-IR
(CH2Cl2): 450 (ꢀ 1790), 634 (6290), 1590 nm (3400).
OM950525D