Triple-decker complexes. 13.1 synthesis of the first triple-decker complexes with a bridging phospholyl ligand. structures of the triple-decker complex [(μ-C4Me4P){Fe(C5Me4CH 2C6H11)}(RuCp*)]CF3so 3 and the related sandwich complex

Article abstract of DOI:10.1021/om960985m

The stacking reaction of the phosphaferrocene Cp*Fe(C₄Me₄P) (1) with the metallo-electrophiles [Cp*Ru-(solv)_x]⁺ (solv = acetone, CH₂Cl₂) gives the 30e triple-decker complex [(μ-C₄Me₄P)(FeCp*)(RuCp*)]CF ₃SO₃ (3), the first compound with a central phospholyl ligand. The cyclohexylmethyl derivative [(μ-C₄Me₄P){Fe(C₅Me₄-CH ₂C₆H₁₁)}(RuCp*)]CF₃SO ₃ (10) shows metal-to-phospholyl distances of 164.4(1) pm for Fe and 180.4(1) pm for Ru.

Full text of DOI:10.1021/om960985m

522
Organometallics 1997, 16, 522-524
Tr ip le-Deck er Com p lexes. 13.1 Syn th esis of th e F ir st
Tr ip le-Deck er Com p lexes w ith a Br id gin g P h osp h olyl
Liga n d . Str u ctu r es of th e Tr ip le-Deck er Com p lex
[(µ-C4Me4P ){F e(C5Me4CH2C6H11)}(Ru Cp *)]CF 3SO3 a n d th e
Rela ted Sa n d w ich Com p lex F e(C4Me4P )(C5Me4CH2C6H11)
Gerhard E. Herberich* and Beate Ganter
Institut fu¨r Anorganische Chemie, Technische Hochschule Aachen, D-52056 Aachen, Germany
Received November 21, 1996X
Sch em e 1a
Summary: The stacking reaction of the phosphaferrocene
Cp*Fe(C4Me4P) (1) with the metallo-electrophiles [Cp*Ru-
(solv)x]+ (solv ) acetone, CH2Cl2) gives the 30e triple-
decker complex [(µ-C4Me4P)(FeCp*)(RuCp*)]CF3SO3 (3),
the first compound with a central phospholyl ligand. The
cyclohexylmethyl derivative [(µ-C4Me4P){Fe(C5Me4-
CH2C6H11)}(RuCp*)]CF3SO3 (10) shows metal-to-phos-
pholyl distances of 164.4(1) pm for Fe and 180.4(1) pm
for Ru.
Phospholyl ligands display a rich coordination chem-
istry,2 but triple-decker complexes with bridging phos-
pholyl ligands are as yet unknown. This seems aston-
ishing, since the pentaphospholyl (P5)3 and 1,2,4-
triphospholyl rings (P2(CR)2P with R ) But)4 are known
to act as bridging ligands in triple-decker structures.
In this communication we describe the first synthesis
of a triple-decker complex with a bridging 2,3,4,5-
tetramethylphospholyl ligand.
a
Legend: (a) 4 Li in THF; (b) [Cp*Fe(NCMe)3]PF6 in THF;
(c) [Cp*Ru(solv)3]+ in acetone or CH2Cl2.
We selected the phosphaferrocene Cp*Fe(C4Me4P) (1)
as the starting compound and studied stacking reactions
of 1 with metallo-electrophiles.5 Complex 16 was readily
1 h and could be isolated as the salt (2)CF3SO3 (≡3)9
(Scheme 1).
7
made from [Cp*Fe(NCMe)3]PF6 and Li(C4Me4P).8 De-
Two regiochemistries are conceivable for the stacking
reaction of 1, one which gives 2+ and an alternative
which would give a triple-decker cation with a bridging
Cp* ligand. We note here that triple-decker complexes
with terminal phospholyl ligands10 as well as other ones
with bridging pentamethylcyclopentadienyl ligands11
are known. On the basis of the present experimental
data we cannot decide whether 2+ is the more stable
isomer. The formation of 2+ could also be the outcome
of kinetic control. Attack of the metallo-electrophile at
the open face of the phospholyl ligand of 1 could for
halogenation of [Cp*RuCl]4 with AgCF3SO3 in acetone
or CH2Cl2 produces the metallo-electrophiles [Cp*Ru-
(solv)x]+ (solv ) acetone, CH2Cl2). These undergo stack-
ing reactions with the complex 1. The 30e triple-decker
cation [(µ-C4Me4P)(FeCp*)(RuCp*)]+ (2+) is formed within
X Abstract published in Advance ACS Abstracts, February 1, 1997.
(1) Part 12: Herberich, G. E.; Englert, U.; Ganter, B.; Lamertz, C.
Organometallics 1996, 15, 5236.
(2) Mathey, F. Coord. Chem. Rev. 1994, 137, 1.
(3) (a) Scherer, O. J . Angew. Chem., Int. Ed. Engl. 1990, 29, 1104.
(b) Rink, B.; Scherer, O. J .; Heckmann, G.; Wolmersha¨user, G. Chem.
Ber. 1992, 125, 1011. (c) Scherer, O. J .; Bru¨ck, T.; Wolmersha¨user, G.
Chem. Ber. 1989, 122, 2049.
(4) Hitchcock, P. B.; J ohnson, J . A.; Nixon, J . F. Organometallics
1995, 14, 4382.
(5) Herberich, G. E.; Englert, U.; Marken, F.; Hofmann, P. Orga-
nometallics 1993, 12, 4039.
(9) Preparation of 3: A suspension of [Cp*RuCl]4 (187 mg, 0.17
mmol) in acetone (or CH2Cl2) was cooled to 0 °C; AgCF3SO3 (176 mg,
0.68 mmol) was added, and the mixture was stirred for 30 min. The
suspension was filtered through Kieselguhr into a Schlenk tube with
1 (226 mg, 0.68 mmol), and stirring was continued for 1 h. The reaction
mixture was evaporated to dryness, dissolved in acetone (10 mL), and
filtered through a layer of alumina (5% H2O, 3 cm); the product was
eluted with acetone. The solution was concentrated to a small volume
and layered with Et2O to give 3 (135 mg, 28%) as violet crystalline
powder. Anal. Calcd for C29H42F3FeO3PRuS: C, 48.68; H, 5.92.
Found: C, 48.62; H, 6.12. 1H NMR (500 MHz, d6-acetone): δ 1.67 (s,
RuCp*), 1.81 (s, FeCp*), 1.94 (d, J PH ) 8.3 Hz, 2 MeR), 2.66 (s, 2 Meâ).
13C{1H} NMR (125 MHz, d6-acetone): δ 9.21 (s, FeCp*), 9.69 (s,
RuCp*), 12.19 (s, 2 Meâ), 14.27 (d, J PC ) 15.9 Hz, 2 MeR), 75.58 (d, J PC
) 85.0 Hz, 2 CR), 76.61 (d, J PC ) 7.6 Hz, 2 Câ), 83.18 (s, FeCp*), 89.47
(s, RuCp*). 31P{1H} NMR (202 MHz, d6-acetone): δ -39.5. SIMS: m/ z
(Irel) 567.2 (100, M+) from cation spectrum, 148.9 (100, CF3SO3-) from
anion spectrum.
(6) Preparation of 1: To a solution of C4Me4PCl (1.56 g, 8.9 mmol)
in THF was added freshly cut lithium metal (250 mg). After the
reaction mixture was stirred for 4 h, unreacted lithium was removed
7
from the solution. [Cp*Fe(NCMe)3]PF6 (4.12 g, 8.9 mmol) was added,
and the dark red mixture was stirred for 1 h. After removal of all
volatiles under vacuum, the residue was dissolved in CH2Cl2, and the
solution was filtered through silica (5 cm) using hexane (300 mL) as
eluent. The orange solution was evaporated to dryness to give 1 (2.42
g, 82%) as orange crystals. Anal. Calcd for C18H27FeP: C, 65.47; H,
8.24. Found: C, 65.08; H, 8.17. 1H NMR (500 MHz, CDCl3): δ 1.64 (d,
J PH ) 9.8 Hz, 2 MeR), 1.74 (s, Cp*), 1.88 (s, 2 Meâ). 13C{1H} NMR (63
MHz, CDCl3): δ 10.03 (s, Cp*), 11.36 (s, 2 Meâ), 13.07 (d, J PC ) 23.8
Hz, 2 MeR), 81.48 (s, Cp*), 91.61 (d, J PC ) 3.8 Hz, 2 Câ), 91.77 (d, 2C,
J PC ) 53.6 Hz, 2 CR). 31P{1H} NMR (202 MHz, CDCl3): δ -61.2. MS
(EI): m/ z (Irel) 330.2 (100, M+), 315.0 (15, M+ - Me).
(7) Catheline, D.; Astruc, D. Organometallics 1984, 3, 1094.
(8) Douglas, T.; Theopold, K. H. Angew. Chem., Int. Ed. Engl. 1989,
28, 1367. See also: Nief, F.; Mathey, F.; Ricard, L.; Robert, F.
Organometallics 1988, 7, 921.
(10) Chase, K. J .; Bryan, R. F.; Woode, M. K.; Grimes, R. N.
Organometallics 1991, 10, 2631.
(11) Kudinov, A. R.; Rybinskaya, M. I.; Struchkov, Yu. T.; Yanovskii,
A. I.; Petrovskii, P. V. J . Organomet. Chem. 1987, 336, 187.
S0276-7333(96)00985-5 CCC: $14.00 © 1997 American Chemical Society

Communications
Organometallics, Vol. 16, No. 4, 1997 523
Sch em e 2a
Sch em e 3a
a
Legend: (a) Fe(CO)5 in refluxing octane; (b) [FeCp2]PF6
in CH2Cl2/MeCN; (c) hν, MeCN; (d) Li(C4Me4P) in THF; (e)
[Cp*Ru(solv)x]+ in acetone or CH2Cl2.
a
Legend: (a) 0.5 [Cp*Ru(NCMe)3]+; (b) 2 [Cp*Ru(NCMe)3]+;
(c) MeCN, slow.
When 3 was recrystallized from acetone/ether/tet-
rahydropyran (THP), cocrystals with THP, 618 (6 ≡ 3‚
THP), were obtained. The crystal structure of 6 showed
an orientational disorder for the cations; therefore, the
Fe and Ru positions were not distinguishable. In order
to overcome this problem, we replaced the FeCp*
fragment in 2+ with a Fe(C5Me4CH2C6H11) fragment.
The required 1-(cyclohexylmethyl)-2,3,4,5-tetramethyl-
cyclopentadiene (7) was prepared from C6H11CH2Br, Li,
and 2,3,4,5-tetramethylcyclopentenone (cf. the synthesis
of Cp*H19). The subsequent synthetic steps, via the
phosphaferrocene 820 to the triple-decker complex (9)CF3-
SO3 (≡10),21 closely follow the synthesis of 3 and are
summarized in Scheme 3.
Compound 8 crystallizes in the monoclinic space
group P21/n with two independent molecules in the
asymmetric unit;22 the two molecules differ in the
orientation of the cyclohexyl groups. The X-ray crystal-
lographic study of compound 10 reveals a typical triple-
decker structure (Figure 1).23 The distances to the best
phospholyl plane amount to 164.4(1) pm for Fe and
180.4(1) pm for Ru. These distances are almost equal
instance be favored by an intermediate σ-coordination
of the ruthenium to the phosphorus atom.
As one goes from 1 to 3, the H NMR signals show a
1
downfield shift for the methyl groups of the phospholyl
ring. The same trend has also been noted for triple-
decker complexes with e.g. cyclopentadienyl ligands
C5H4Me12 and Cp*11 rings as central ligands. Quite
remarkably, the 31P NMR resonance is also shifted
downfield (δ(31P) -61.2 for 1 and δ(31P) -39.5 ppm for
3).
When 3 is dissolved in acetonitrile, nucleophilic
degradation takes place within 5-10 days at ambient
temperature to give the complex [Cp*Ru(NCMe)2(µ-C4-
Me4P)FeCp*]CF3SO3 ((4)CF3SO3)13 with a Ru-P σ-bond.
On the other hand, mixtures of [Cp*Ru(NCMe)3]+ 14 and
1 form the same species 4+ as well as the complex
[Cp*Ru(NCMe){(µ-C4Me4P)FeCp*}2]CF3SO3 ((5)CF3-
SO3).15 The σ-coordination of the phosphaferrocene 1
is indicated by a considerable downfield shift of the 31P
resonances (δ(31P) 16.2 for 4+ and δ(31P) 1.4 ppm for
5+).16 With an excess of [Cp*Ru(NCMe)3]+ only 4+ is
formed, while with an excess of 1 only 5+ is seen
(Scheme 2).17 We conclude that these reactions are
thermodynamically controlled, and the triple-decker
cation 2+ will only be formed if stabilizing ligands such
as acetonitrile are absent.
(18) A solution of 3 in a mixture of acetone (5 mL) and tetrahydro-
pyran (5 mL) was layered with Et2O (30 mL) to give 6 as violet crystals
which were suitable for X-ray structure determination; they lose THP
at room temperature.
(19) (a) King, R. B.; Bisnette, M. B. J . Organomet. Chem. 1967, 8,
287. (b) Feitler, D.; Whitesides, G. M. Inorg. Chem. 1975, 15, 466.
(20) Data for 8: Anal. Calcd for C24H37FeP: C, 69.90; H, 9.04.
Found: C, 69.46; H, 9.11. 1H NMR (500 MHz, CDCl3): δ 0.85 (m, 2H,
Cy), 1.10 (m, 3H, Cy), 1.15 (m, 1H, CH, Cy), 1.58 (m, 5H, Cy), 1.62 (d,
J PH ) 9.8 Hz, 2 MeR), 1.72 and 1.73 (s, C5Me4), 1.86 (s, 2 Meâ), 2.11 (d,
J ) 7.0 Hz, CH2). 13C{1H} NMR (125 MHz, CDCl3): δ 10.10 and 10.69
(s, C5Me4), 11.41 (s, 2 Meâ), 13.16 (d, J PC ) 23.6 Hz, 2 MeR), 26.40 (s,
2C, Cy), 26.51 (s, 1C, Cy), 33.47 (s, 2C, Cy), 33.79 (s, 1C, CH2), 39.62
(s, 1C, Cy), 81.51 and 81.67 (s, C5Me4), 84.92 (s, FeCCH2Cy), 91.48 (d,
J PC ) 53.2 Hz, 2 CR), 91.56 (d, J PC ) 4.4 Hz, 2 Câ). 31P{1H} NMR (202
MHz, CDCl3): δ -61.3. MS (EI): m/ z (Irel) 412.1 (95, M+), 58.0 (100).
(21) Data for 10: Anal. Calcd for C35H52F3FeO3PRuS: C, 52.70; H,
6.57. Found: C, 52.85; H, 6.77. 1H NMR (500 MHz, d6-acetone): δ 0.94
(m, 2H, Cy), 1.11 (m, 3H, Cy), 1.25 (m, CH, Cy), 1.53 (m, 2H, Cy), 1.61
(12) Salzer, A.; Werner, H. Angew. Chem., Int. Ed. Engl. 1972, 11,
930.
(13) NMR data for 4+: 1H NMR (500 MHz, CD2Cl2) δ 1.37 (d, J PH
)
9.8 Hz, 2 MeR), 1.53 (d, J PH ) 2.7 Hz, RuCp*), 1.69 (s, FeCp*), 1.94 (s,
2 Meâ), 2.49 (d, J PH ) 1.5 Hz, 2 MeCN); 31P{1H} NMR (202 MHz, CD2-
Cl2) δ 16.2.
(14) (a) [Cp*Ru(NCMe)3]PF6: Schrenk, J . L.; McNair, A. M.; Mc-
Cormick, F. B.; Mann, K. R. Inorg. Chem. 1986, 25, 3501. (b) [Cp*Ru-
(NCMe)3]CF3SO3: Fagan, P. J .; Ward, M. D.; Calabrese, J . C. J . Am.
Chem. Soc. 1989, 111, 1698.
(15) NMR data for 5+: 1H NMR (500 MHz, CD2Cl2) δ 1.42 (d, J PH
)
11.9 Hz, 4 MeR), 1.66 (s, 2 FeCp*), 1.69 (s, RuCp*), 1.96 (s, 4 Meâ),
2.43 (s, MeCN); 31P{1H} NMR (202 MHz, CD2Cl2): δ 1.4 (br).
(16) For reference data see: (a) Deschamps, B.; Mathey, F.; Fischer,
J .; Nelson, J . H. Inorg. Chem. 1984, 23, 3455. (b) Nelson, J . H.; Mathey,
F. In Phosphorus-31 NMR spectroscopy in Stereoechemical Analysis;
Verkade, J . G., Quin, L. D., Eds.; VCH: Weinheim, Germany, 1987.
(17) There are no indications for the formation of the triply
(m, 3H, Cy), 1.66 (s, RuCp*), 1.82 and 1.84 (s, C5Me4), 1.94 (d, J PH )
7.9 Hz, 2 MeR), 2.38 (d, J ) 7.3 Hz, CH2), 2.65 (s, 2 Meâ). 13C{1H} NMR
(125 MHz, d6-acetone): δ 9.22 and 9.93 (s, C5Me4), 9.69 (s, RuCp*, 12.25
(s, 2 Meâ), 14.36 (d, J PC ) 15.9 Hz, 2 MeR), 26.84 (s, 2C, Cy), 26.93 (s,
1C, Cy), 32.84 (s, 1C, CH2), 33.82 (s, 2C, Cy), 39.56 (s, 1C, Cy), 75.52
(d, J PC ) 85.0 Hz, 2 CR), 76.64 (d, J PC ) 7.6 Hz, 2 Câ), 83.15 and 83.71
(s, C5Me4), 86.06 (s, FeCCH2Cy), 89.47 (s, RuCp*). 31P{1H} NMR (202
MHz, d6-acetone): δ -39.3. SIMS: m/ z (Irel) 649.2 (100, M+) from
cation spectrum, 148.9 (100, CF3SO3-) from anion spectrum.
substituted species [Cp*Ru(1)3]+, even with
presumably because of too much steric hindrance.
a large excess of 1,

524 Organometallics, Vol. 16, No. 4, 1997
Communications
Ack n ow led gm en t. We thank Dr. U. Englert for
advice with the structure determinations. This work
was generously supported by the Deutsche Forschungs-
gemeinschaft and the Fonds der Chemischen Industrie.
Su p p or tin g In for m a tion Ava ila ble: PLATON plots of
8 and tables of bond distances and angles, positional and
anisotropic thermal parameters, and hydrogen atom coordi-
nates for 8 and 10 (21 pages). Ordering information is given
on any current masthead page.
OM960985M
(22) Crystal data for 8: orange crystals, 0.60 × 0.45 × 0.25 mm,
monoclinic, a ) 1687(1) pm, b ) 1474(1) pm, c ) 1773(1) pm, â )
92.39(5)°, V ) 4.405(8) nm3, Z ) 8, space group P21/n (No. 14), Dcalcd
) 1.244 g cm-3, µ ) 7.60 cm-1, F(000) ) 1776. Data collection: ENRAF-
Nonius CAD4, Mo KR radiation, graphite monochromator, ω scan (3
< θ < 27°) at 203 K, 10 291 reflections measured, 5885 unique
reflections with I > σ(I). Solution26 and refinement:27 749 parameters,
R ) 0.067, Rw ) 0.060, w-1 ) σ2(Fo), GOF ) 1.426, non-hydrogen atoms
were refined anisotropically, most of the hydrogen atoms were refined
isotropically, the remaining hydrogen atoms were treated as riding.28
(23) Crystal data for 10: violet crystals, 0.50 × 0.25 × 0.08 mm,
monoclinic, a ) 1721(1) pm, b ) 1109.6(3) pm, c ) 1862.2(6) pm, â )
F igu r e 1. PLATON25 plot of 10 (at the 30% probability
level). Bond distances (pm): Ru-P, 241.2(2); Fe-P,
229.2(3); Ru-C2, 225.2(7); Ru-C3, 221.2(9); Ru-C4, 220.7-
(7); Ru-C5, 221.2(7); Fe-C2, 208.9(7); Fe-C3, 209.0(9);
Fe-C4, 209.1(7); Fe-C5, 210.1(7); P-C2, 180.9(8); P-C5,
185.5(8); C2-C3, 145(1); C3-C4, 147(1); C4-C5, 143(1).
Distances from ring planes (pm): Ru-(C4Me4P), 180.4;
Ru-Cp*, 180.4; Fe-(C4Me4P), 164.4; Fe-(C5Me4CH2C6H11),
166.3. Bond angles (deg): Ru-P-Fe, 94.26(9); C2-P-C5,
88.2(3).
92.81(4)°, V ) 3.553(4) nm3, Z ) 4, space group Ia (No. 9), Dcalcd
)
1.490 g cm-3, µ ) 9.73 cm-1, F(000) ) 1656. Data collection: ENRAF-
Nonius CAD4, Mo KR radiation, graphite monochromator, ω scan (3
< θ < 28°) at 203 K, 10 298 reflections measured, 6445 unique
reflections with I > σ(I). Solution26 and refinement:27 404 parameters,
R ) 0.063, Rw ) 0.054, w-1 ) σ2(Fo), GOF ) 1.137, non-hydrogen atoms
were refined anisotropically, all hydrogen atoms were treated as
riding.28
(24) Carmichael, D.; Ricard, L.; Mathey, F. J . Chem. Soc., Chem.
Commun. 1994, 1167.
(25) Spek, A. L. Acta Crystallogr. 1990, A46, C34.
(26) Sheldrick, G. M. SHELXS-86, Program for Crystal Structure
Solution; University of Go¨ttingen: Go¨ttingen, Germany, 1986.
(27) MolEN, An Interactive Structure Solution Procedure; ENRAF-
Nonius: Delft, The Netherlands, 1990.
(28) Further details of the crystal structure analyses are available
on request from the Fachinformationszentrum Karlsruhe, Gesellschaft
fu¨r wissenschaftlich-technische Information mbH, D-76344 Eggenstein-
Leopoldshafen, Germany, on quoting the depository number CSD-
406301 for 8 and CSD-406302 for 10, the names of the authors, and
this journal citation.
to those in comparable sandwich complexes (165.1(1) pm
for 8 and 181.4 pm for Cp*Ru(2,5-ButC4H2P)24).
Work is in progress in order to generalize the results
presented here. Degradation reactions of triple-decker
complexes with bridging phospholyl rings and phos-
pholyl ligand transfer reactions are also currently under
investigation.