[PPN][Fe3(CO)9(C≡CH)] and [Fe3(CO)9(C≡COTi(THF)4Cl)] from the reaction of low-valent titanium with [Fe3(CO)9(CCO)]2-

Article abstract of DOI:10.1021/om9806085

TiCl₃(DME)_1.5 (DME = 1,2-dimethoxyethane) and a Zn-Cu couple react with [PPN]₂[Fe₃-(CO)₉(CCO)] to give the new compound [PPN][Fe₃(CO)₉(C≡CH)] (I) (70% yield), a known compound [Fe₃(CO)₁₀(CCH₂)] (II) (9% yield), and another new compound [Fe₃(CO)₉(CCOTi-(THF)₄Cl)] (III). Compound I was characterized by ¹H and ¹³C NMR, IR, mass spectrometry, and X-ray crystallography. Compound III was characterized by IR, mass spectrometry, ¹³C NMR, and X-ray crystallography.

Full text of DOI:10.1021/om9806085

534
Organometallics 1999, 18, 534-539
[P P N][F e3(CO)9(CtCH)] a n d [F e3(CO)9(CtCOTi(THF )4Cl)]
fr om th e Rea ction of Low -Va len t Tita n iu m w ith
[F e3(CO)9(CCO)]2-
Randal W. Eveland, Casey C. Raymond,† and Duward F. Shriver*
Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113
Received J uly 17, 1998
TiCl3(DME)1.5 (DME ) 1,2-dimethoxyethane) and a Zn-Cu couple react with [PPN]2[Fe3-
(CO)9(CCO)] to give the new compound [PPN][Fe3(CO)9(CtCH)] (I) (70% yield), a known
compound [Fe3(CO)10(CCH2)] (II) (9% yield), and another new compound [Fe3(CO)9(CCOTi-
(THF)4Cl)] (III). Compound I was characterized by 1H and 13C NMR, IR, mass spectrometry,
and X-ray crystallography. Compound III was characterized by IR, mass spectrometry, 13C
NMR, and X-ray crystallography.
In earlier research we found that reaction at the
The present research was designed to explore the
reactions of metal cluster carbonyls with the McMurry
reagent, a low oxidation state titanium species.7,8 The
active titanium species in the McMurry reagent is
thought to be Ti(0) or Ti(II), which serves to abstract
oxygen atoms and form a carbon-carbon bond from an
aldehyde and starting material.9-11 In our research, we
explored the possibility that the McMurry reagent might
reduce CO and CCO concomitant with oxygen abstrac-
tion to produce cluster polycarbon compounds.
oxygen of a carbonyl with an electrophile followed by
chemical reduction leads to carbon-carbon bond forma-
tion, as in the formation of [Fe3(CO)9(CCO)]2- from [Fe3-
(CO)11]2-.1 Further reaction of [Fe3(CO)9(CCO)]2- with
a strong electrophile, triflic anhydride (O(SO2CF3)2),
resultsinformationoftheC4-containingcluster[Fe6(CO)18C4]2-,
where the C4 unit arises from two ketenylidene ligands
(CCO) as shown in eq 1.2
Exp er im en ta l Section
Gen er a l P r oced u r es a n d Ma ter ia ls. Manipulation of air-
sensitive solutions and volatile materials was carried out with
standard Schlenk techniques under a prepurified N2 atmo-
sphere. Solids were handled in a drybox with a N2 atmosphere.
Solvents were distilled under nitrogen from appropriate drying
agents. Infrared spectra were recorded on a Bomem MB-Series
FTIR spectrometer at 2 cm-1 resolution. Solution IR spectra
were obtained in matched air-free cells with CaF2 windows,
and solid samples were prepared as Nujol mulls between KBr
plates. The 1H and 13C NMR spectra were acquired on a Varian
Unity 400+ spectrometer operating at 400 MHz for 1H and
100 MHz for 13C. CD2Cl2 was used as an internal standard
and before use was vacuum distilled from P4O10. Magnetic
measurements were determined with a Quantum Design
MPMS SQUID operating at either 500 or 1000 G. Mass spectra
were determined on a VG 70-SE unit. Elemental analyses were
determined by Elbach Analytical Laboratories, Engelskirchen,
Germany. Published procedures were employed for the syn-
thesis of [PPN]2[Fe3(CO)9(CCO)],12 Ru3(CO)12,13 [PPN]2[Ru3-
(CO)9(CCO)],14 [PPN]2[Os3(CO)9(CCO)],15 [PPN]2[Ru6(CO)16C],16
(1)
In the present research we explored the possibility
that a single reagent, an oxophilic reducing agent, might
effect concerted CCO formation followed by C-O cleav-
age and reduction to yield a polycarbon metal cluster
compound. Electrophiles interact with carbonyl ligands
and ketenylidene ligands in several ways. In the reac-
tion of [Fe3(CO)9(CCO)]2- with the labile organometallic
species M(CO)3(NCCH3)3 (M ) W, Cr), tetrahedral
metal carbide clusters are formed: [MFe3(CO)12C]2- 3,4
.
Similarly, the reaction of [Fe3(CO)9(CCO)]2- with
[Re(CO)5]- and [CpFe(CO)2]- produces [Fe3(CO)9CCRe-
(CO)5]- and [Fe3(CO)9CCFeCp(CO)2]-, respectively.5,6
(6) J ensen, M. P.; Sabat, M.; Shriver, D. F. J . Cluster Sci. 1990, 1,
75.
(7) McMurry, J . E. Chem. Rev. 1989, 89, 1513-24.
(8) McMurry, J . E. Acc. Chem. Res. 1983, 16, 405-11.
(9) Villiers, C.; Ephritikhine, M. Angew. Chem., Int. Ed. Engl. 1997,
36, 2380.
† Current address: Kent State University, Department of Chemis-
try, Kent, OH 44242.
(1) Kolis, J . W.; Holt, E. M.; Drezdzon, M.; Whitmire, K. H.; Shriver,
D. F. J . Am. Chem. Soc. 1982, 104, 6134-35.
(2) Norton, D. M.; Stern, C. L.; Shriver, D. F. Inorg. Chem. 1984,
33, 2701-2.
(3) Hriljac, J . A.; Holt, E. M.; Shriver, D. F. Inorg. Chem. 1987, 26,
2943-9.
(4) J ensen, M. P.; Phillips, D. A.; Sabat, M.; Shriver, D. F. Orga-
nometallics 1992, 11, 1859.
(5) Norton, D. M.; Eveland, R. W.; Hutchison, J . C.; Stern, C.;
Shriver, D. F. Organometallics 1996, 15, 3916-9.
(10) Stahl, M.; Pidun, U.; Frenking, G. Angew. Chem., Int. Ed. Engl.
1997, 36, 2234-7.
(11) Dams, R.; Malinowski, M.; Westdorp, I.; Geise, H. Y. J . Org.
Chem. 1982, 47, 248-59.
(12) Kolis, J . W.; Holt, E. M.; Shriver, D. F. J . Am. Chem. Soc. 1983,
105, 7307-13.
(13) Bruce, M. I.; J ensen, C. M.; J ones, N. L. Inorg. Synth. 1989,
26, 259-61.
(14) Sailor, M. J .; Shriver, D. F. Organometallics 1985, 4, 1476-8.
10.1021/om9806085 CCC: $18.00 © 1999 American Chemical Society
Publication on Web 01/21/1999

Reaction of Ti with [Fe3(CO)9(CCO)]2-
Organometallics, Vol. 18, No. 4, 1999 535
and TiCl3(DME)1.5 (DME ) 1,2-dimethoxyethane), where
1914(m), 1779(w) cm-1. The electrospray mass spectrum of the
compound in methanol contains the parent peak for III at 836
m/z, calculated 836 m/z.
17
[PPN]+ ) [(PPh3)2N]+.
Rea ction of [P P N]2[F e3(CO)9(CCO)] w ith a Ti(0)/Ti(II)
Red u cin g Solu tion . A reducing solution was prepared by
refluxing 0.822 g (2.84 mmol) of TiCl3(DME)1.5 and 0.738 g
(11.36 mmol) Zn-Cu couple in 20 mL of DME at 90 °C for 3
h.8 The solution was cooled to room temperature, and 40 mL
of THF was added followed by 1.454 g (0.946 mmol) of solid
[PPN]2[Fe3(CO)9(CCO)]. [PPN]2[Fe3(CO)9(CCO)] is only slightly
soluble in THF, so the mixture was stirred overnight, followed
by filtration through Celite, and solvent was then removed
under vacuum. A 50 mL aliquot of CH2Cl2 was added to the
solids, and after 2 h the solution was filtered to remove white
solids. Solvent was removed from the filtrate under vacuum,
and the resulting dark solids were redissolved in 10 mL of
THF. Pentane (50 mL) was added to this solution, and vigorous
shaking gave a red-black oil of [PPN][Fe3(CO)9(CCH)] (I) and
a brown-red solution of [Fe3(CO)10(CCH2)] (II), which were
separated by filtration. This separation process was repeated
three times. The oil was dissolved in 10 mL of THF and layered
with 50 mL of pentane to give light red crystals and a color-
less solution. The crystals were isolated by filtration, washed
twice with 5 mL of pentane, and dried to yield 0.652 g of [PPN]-
[Fe3(CO)9(CCH)](I) (70% yield based on iron). The filtrates
were combined, and solvent was removed under vacuum. The
resulting solid was dissolved in pentane and filtered, and
the solvent was removed under vacuum, leaving 0.0410 g of
[Fe3(CO)10(CCH2)] (II) (9% yield based on iron).
Rea ction of [P P N][F e3(CO)9(CCH)] w ith Tr iflic Acid .
A 2.9 µL (0.0327 mmol) aliquot of HSO3CF3 was added to
0.0316 g (0.0321 mmol) of [PPN][Fe3(CO)9(CCH)] in 5 mL of
THF and stirred for 5 min. The mixture was filtered to remove
white, insoluble [PPN](OTf) and dried under vacuum to give
[HFe3(CO)9(CCH)]: IR νCO (THF) 2062(sh), 2042(s), 2025(vs),
2005(s), 1997(s) cm-1; 1H NMR 1.266 and -20.0 ppm. 13C NMR
at -30 °C shows terminal carbonyls in a 2:2:1:2:1:2 ratio at
212.8, 212.2, 211.1, 210.6, 206.9, and 205.9 ppm and peaks
for CCH at 182.3 and CCH at 39.2 ppm. Electrospray mass
spectra of a methanol solution of the compound show a parent
peak at 446 m/z (calcd ) 446 m/z).
X-r a y Cr ysta l Str u ctu r e Deter m in a tion of [P P N][F e3-
(CO)9(CCH)] (I). A THF solution of I was layered with
pentane, and one of the resulting crystals was mounted on a
glass fiber with silicon grease. A complete hemisphere of data
was collected at 163 K on a Siemens SMART-CCD. The
intensity data were collected with 30 s frame times and
interpreted with SAINT.19 The initial unit cell parameters
were determined from several frames of data, but were
redetermined using all of the data. The structure was solved
and refined using SHELXTL on 28 216 reflections and cor-
rected for absorption using SADABS.20,21 Hydrogen atoms were
placed in idealized positions and refined with a riding model.
Because of the method used by SADABS, no transmission
factors are reported for the corrected data.
X-r a y Cr ysta l Str u ctu r e Deter m in a tion of [F e3(CO)9-
(CCOTi(THF )4Cl)] (III). A crystal of III was mounted on a
glass fiber with paratone oil, and a complete hemisphere of
data was collected at 153 K on a Bruker SMART 1000-CCD.
The intensity data were collected as described above. Cell
parameters were determined using all of the unique data, and
the structure was solved and refined using SHELXTL and
corrected for absorption using SADABS.20,21 Hydrogen atoms
were placed in idealized positions and refined with a riding
model. Because of the method used by SADABS, no transmis-
sion factors are reported for the corrected data.
The infrared spectrum of [PPN][Fe3(CO)9(CCH)] (I) in THF
displayed νCO at 2044(w), 1986(vs), 1978(vs), 1959(s), 1933-
(m) cm-1; (Nujol) 2044, 2016, 1977, 1951, 1928 cm-1. Anal.
Calcd. for Fe3C47O9P2NH31 (Found) C, 57.41 (57.06); H, 3.18
1
(3.35); N, 1.42 (1.55). H NMR (CD2Cl2, 25 °C): 7.64 (PPN+),
7.46 (PPN+), 1.15 (CCH) ppm. 13C NMR (CD2Cl2, -30 °C): δ
226.32, 222.44, 216.73, 215.81, 215.47, 211.29, 209.78 (terminal
carbonyls), 154.46 (CCH), 81.02 (CCH) ppm. Electrospray mass
spectra contain a parent peak at 446 m/z corresponding to I
+ H, plus peaks for the sequential loss of two CO ligands.
The CO stretching frequencies for [Fe3(CO)10(CCH2)] (II) in
pentane matched known values, at 2094(w), 2053(vs), 2035-
(vs), 2028(s), 2010(w), 1984(m), 1877(m, br) cm-1. The 1H NMR
spectrum of II in CD2Cl2 displayed a feature at 5.30 ppm.18
The X-ray powder diffraction pattern of this compound matches
the d-values calculated from X-ray single-crystal data previ-
ously reported for II.18
Resu lts a n d Discu ssion
R ea ct ion of Ir on Ket en ylid en e w it h McMu r r y
Rea gen t. [Fe3(CO)9(CCH)]- (I) is produced in good yield
from the reaction of [Fe3(CO)9(CCO)]2- with a low-valent
titanium solution. This ethynyl cluster was previously
synthesized by Mathieu et al. from the reaction of
Reaction of [PPN]2[Fe3(CO)9(CCO)] with TiCl3(DME)1.5. A
15 mL aliquot of THF was added to a Schlenk flask containing
0.0463 g (0.160 mmol) of TiCl3(DME)1.5 and 0.2004 g (0.130
mmol) of [PPN]2[Fe3(CO)9(CCO)]. After the mixture was stirred
under N2 for 30 min, solvent was removed under vacuum. A
20 mL portion of Et2O was added to the solids, and white
[PPN]Cl solid was removed by filtration. Diethyl ether was
removed under vacuum to yield 0.0571 g (0.0687 mmol) of red,
microcrystalline [Fe3(CO)9(CCOTi(THF)4Cl)] (III) (53% yield
based on iron).
A similar procedure was used with 0.0764 g (0.264 mmol)
of TiCl3(DME)1.5 and 0.2019 g (0.131 mmol) of [PPN]2[Fe3(CO)9-
(CCO)]. The initial THF solution was filtered, reduced under
vacuum to 5 mL, and layered with 20 mL of pentane. The
resulting red solid III (0.0286 g, 26% yield based on iron) was
collected by filtration. A green solution of Fe3(CO)10(CCH2) (II)
was collected, and solvent was removed (0.0854 g, 68% yield
based on iron).
ethoxyacetylene with [Fe3(CO)11]2- 18
but it was not
,
completely characterized, and an X-ray structure was
not reported. In the present research the CCH moiety
is generated by reduction of metal carbonyl ligands
(Scheme 1).
Another C2-containing cluster, [Fe3(CO)10(CCH2)] (II),
is formed in 9% yield. This compound was previously
synthesized in 2% yield23 from the reaction of Fe3(CO)12
with BuLi, Me3OBF4, and H2O, respectively. In our
research, it may result from CO bond scission of the
ketenylidene ligand followed by proton attack. This is
consistent with the change from nine CO ligands in
starting material and in I to 10 CO ligands in III.
An infrared spectrum of [Fe3(CO)9(CCOTi(THF)4Cl)] (III)
in THF shows νCO at 2048(w), 1993(vs), 1960(s), 1930(sh),
(19) Siemens SAINT-PC; Siemens, Ed.: Madison, WI, 1996.
(20) Sheldrick, G. M. J . Appl. Crystallogr. in preparation.
(21) Sheldrick, G. M. SADABS, Program for Absorption Correction
of Area Detector Data; Sheldrick, G. M., Ed.: Gottingen, Germany,
1996.
(22) Sappa, E.; Tiripicchio, A.; Braunstein, P. Chem. Rev. 1983, 83,
203-39.
(23) Aradi, A. A.; Grevels, F.; Kruger, C.; Raabe, E. Organometallics
1988, 7, 812-8.
(15) Kolis, J . W. Thesis, Northwestern University, 1984.
(16) Bradley, J . S.; Ansell, G. B.; Hill, E. W. J . Organomet. Chem.
1980, 184, C33-C35.
(17) McMurry, J . E.; Lectka, T.; Rico, J . G. J . Org. Chem. 1989, 54,
3748-3749.
(18) Suades, J .; Dahan, F.; Mathieu, R. Organometallics 1988, 7,
47-51.

536 Organometallics, Vol. 18, No. 4, 1999
Eveland et al.
Ta ble 1. Su m m a r y of Cr ysta l Da ta a n d In ten sity
Collection
Sch em e 1. Rea ction of [P P N]2[F e3(CO)9(CCO)]
w ith Low -Va len t Tita n iu m
I
III
formula
fw
a (Å)
b (Å)
c (Å)
C
47H31NO9P2Fe3
C27H32O14ClTiFe3
831.4
10.517(1)
17.903(2)
18.463(2)
90
983.22
9.2601(1)
29.7878(1)
15.7931(2)
90
R (deg)
â (deg)
γ (deg)
V (Å3)
space group, Z
T (°C)
λ (Å)
101.313(1)
90
102.915(2)
90
4271.69(7)
P21/c, 4
-110
0.710 73
1.529
1.139
0.0466
0.0756
3388.7(6)
P21/n, 4
-120
0.710 73
1.630
1.628
0.0447
0.0837
F
calc (g cm-3
)
µ (mm-1
R1a
)
wR2b
In typical McMurry reactions, the active species is
considered to be Ti(0) particles in a heterogeneous
reaction media, and it is believed that C-C coupling
occurs on the metal surface via ketyl radical intermedi-
ates.8,9,11 Recent results indicate that TiCl2 in DME may
serve as a nucleophile toward the carbonyl oxygen,
rather than a radical to effect the coupling reaction.10,24-26
By analogy with the proposed route for the conversion
of CCO to polycarbon ligands, the Ti(II) species may
attack the terminal oxygen of the ketenylidene ligand
of [Fe3(CO)9(CCO)]2- followed by reductive cleavage of
the C-O bond. The source of the proton in I and II may
be residual water, even though water was not observed
spectroscopically in any of the starting materials.
Str u ctu r e a n d Ch a r a cter iza tion of [P P N][F e3-
(CO)9(CCH)] (I). The compound was characterized in
the solid state as a well separated bis(triphenylphos-
phonium)iminium, PPN, cation and metal cluster anion.
The cation is well ordered, and all bonds and angles are
reasonable. Crystal data are shown in Tables 1, 2, and
3. The Fe-Fe distances for I are Fe1-Fe2, 2.6569(4)
Å, and Fe1-Fe3, 2.6769(4) Å. The iron edge which is
bridged by the ethynyl ligand is shorter, Fe2-Fe3
(2.4958(4) Å). The CCH moiety bonds to the trimetallic
core through one σ and two π bonds (σ + 2π, µ3-(η2- )
and is nearly perpendicular to one edge of the metal
cluster. All three metal atoms are bound to C10, with
bond lengths of 1.814(2), 2.049(2), and 2.055(2) Å for
C10-Fe1, C10-Fe2, and C10-Fe3, respectively. Longer
Fe-C bonds were found for C11 interactions with Fe2
(2.079(2) Å) and Fe3 (2.099(2) Å). The C10-C11 bond
length is 1.293(2) Å, slightly longer than expected for a
triple bond, but well within the range for similar alkyne
clusters, as reviewed by Sappa.22 The comparisons in
Table 6 show that the bond lengths quoted above are
typical of ethynyl clusters. A Fourier difference map
indicates electron density assignable to the ethynyl
proton; however, the structure was refined with the
proton in an idealized position.
a
b
2
R1 ) (∑||Fo| - |Fc||)/∑|Fo|. wR2 ) [(∑w(Fo - Fc2)2)/
∑w(Fo2)2]1/2; w ) 1/[σ2(Fo2) + (z1,P)2+z2P] where P ) (Fo + 2Fc2)/
3, z1, z2 ) weighting and extra extinction.
2
Ta ble 2. Selected Atom ic Coor d in a tes (Å × 104)
a n d Equ iva len t Isotr op ic Disp la cem en t
P a r a m eter s (Å2 × 103) for [P P N][F e3(CO)9(CCH)], I
a
atom
x
y
z
Ueq
Fe(1)
Fe(2)
Fe(3)
C(1)
O(1)
C(2)
O(2)
C(3)
O(3)
O(4)
C(4)
C(5)
O(5)
O(6)
C(6)
C(7)
O(7)
O(8)
C(8)
C(9)
O(9)
C(10)
C(11)
4209(1)
5076(1)
7015(1)
4094(2)
3999(2)
4316(3)
4359(3)
2282(2)
1039(2)
5074(2)
5060(2)
3261(2)
2095(2)
6835(2)
6136(2)
7266(2)
7502(2)
9535(2)
8560(2)
7851(2)
8430(2)
5095(2)
5984(2)
1463(1)
620(1)
2145(1)
2469(1)
2686(1)
993(1)
25(1)
23(1)
24(1)
30(1)
41(1)
40(1)
68(1)
39(1)
67(1)
35(1)
26(1)
30(1)
42(1)
43(1)
30(1)
30(1)
43(1)
50(1)
32(1)
33(1)
50(1)
27(1)
30(1)
1213(1)
1489(1)
1510(1)
2047(1)
2426(1)
1396(1)
1358(1)
486(1)
548(1)
403(1)
259(1)
-165(1)
139(1)
1253(1)
1271(1)
627(1)
260(1)
2347(2)
2500(1)
2092(2)
2067(1)
625(1)
1341(1)
2464(1)
2409(1)
3153(1)
2869(1)
1597(1)
907(1)
3295(1)
3051(1)
3058(1)
3257(1)
3154(1)
3631(1)
860(1)
1740(1)
2076(1)
1205(1)
930(1)
a
Ueq is defined as 1/3 the trace of the Uij tensor.
the ethynyl ligand are located at δ 81 and 154 ppm in
the H decoupled NMR spectrum. The â carbon is not
1
observed above -30 °C. For comparison, positions of R
and â carbons for other ethynyl clusters are provided
in Table 7. In the 1H coupled 13C NMR spectrum
collected at -80 °C, the peaks for the R and â carbons
are split with J C-H ) 188 Hz and J C-H ) 22.9 Hz. The
1H NMR of I has a peak of 1.15 ppm for the acetylide
proton. This value is lower than reported by Mathieu,18
but it is in the range expected for a metal-bound
acetylide.27
Str u ctu r e a n d Ch a r a cter iza tion of [P P N][F e3-
(CO)9(CCOTi(THF )4Cl)] (III). The structure of III is
shown in Figure 2, and crystal data are shown in Tables
1, 4, and 5. The Fe1-Fe2 (2.6490(7) Å) and Fe1-Fe3
(2.6360(7) Å) bond lengths are longer than the Fe2-
Fe3 (2.4963(7) Å) which is bridged by the C-C moiety.
1
2
The infrared spectrum of compound I contains five
bands in the νCO region. The ethynyl C-H stretch is
not observed. The 13C NMR of I indicates fluctional
behavior of the carbonyl ligands from -80 to 60 °C in
CD2Cl2 solution. The terminal carbonyl resonances
range from δ 200 to 230 ppm, and the R and â carbon of
(24) Bogdanovic, B.; Bolte, A. J . Organomet. Chem. 1995, 502, 109.
(25) Furstner, A.; J umbam, D. N. Tetrahedron 1992, 48, 5991.
(26) Furstner, A.; Hupperts, A.; Ptock, A.; J anssen, E. J . Org. Chem.
1994, 59, 5215.
(27) Parish, R. V. NMR, NQR, EPR and Mo¨ssbauer Spectroscopy
in Inorganic Chemistry, Ellis Horwood: London, 1990.

Reaction of Ti with [Fe3(CO)9(CCO)]2-
Organometallics, Vol. 18, No. 4, 1999 537
Ta ble 3. Bon d Len gth s (Å) a n d An gles (d eg) for
th e An ion in [P P N][F e3(CO)9(CCH)], I
Ta ble 5. Bon d Len gth s (Å) a n d An gles (d eg) for
[F e3(CO)9(CCOTi(THF )4Cl] (III)
C(10)-C(11)
Fe(1)-C(10)
Fe(2)-C(11)
Fe(1)-Fe(2)
Fe(2)-Fe(3)
Fe(1)-C(1)
Fe(1)-C(2)
Fe(1)-C(3)
Fe(2)-C(4)
Fe(2)-C(5)
Fe(2)-C(6)
Fe(3)-C(7)
Fe(3)-C(8)
Fe(3)-C(9)
1.293(3)
1.814(2)
2.079(2)
2.6569(4)
2.4958(4)
1.803(2)
1.769(2)
1.781(2)
1.791(2)
1.799(2)
1.781(2)
1.784(2)
1.778(2)
1.797(2)
Fe(2)-C(10)
Fe(3)-C(10)
Fe(3)-C(11)
Fe(1)-Fe(3)
C(1)-O(1)
C(2)-O(2)
C(3)-O(3)
O(4)-C(4)
C(5)-O(5)
O(6)-C(6)
C(7)-O(7)
O(8)-C(8)
C(9)-O(9)
2.049(2)
2.055(2)
2.099(2)
2.6769(4)
1.146(2)
1.153(3)
1.149(3)
1.149(2)
1.150(2)
1.151(3)
1.154(2)
1.145(3)
1.150(3)
C(10)-C(11)
Fe(1)-C(10)
Fe(2)-C(10)
Fe(3)-C(10)
Fe(1)-Fe(2)
Fe(1)-Fe(3)
Fe(1)-C(1)
Fe(1)-C(2)
Fe(1)-C(3)
Fe(2)-C(4)
Fe(2)-C(5)
Fe(2)-C(6)
Fe(3)-C(7)
Fe(3)-C(8)
Fe(3)-C(9)
Ti(1)-O(20)
Ti(1)-O(30)
1.304(4)
1.818(3)
2.015(3)
2.034(3)
2.6490(7)
2.6360(7)
1.800(4)
1.760(4)
1.784(4)
1.789(4)
1.785(4)
1.773(4)
1.779(4)
1.770(4)
1.777(4)
2.107(2)
2.099(2)
C(11)-O(10)
O(10)-Ti(1)
Fe(2)-C(11)
Fe(3)-C(11)
Fe(2)-Fe(3)
C(1)-O(1)
C(2)-O(2)
C(3)-O(3)
C(4)-O(4)
C(5)-O(5)
C(6)-O(6)
C(7)-O(7)
C(8)-O(8)
C(9)-O(9)
Ti(1)-Cl(1)
Ti(1)-O(40)
Ti(1)-O(50)
1.310(4)
1.875(2)
2.094(3)
2.109(3)
2.4963(7)
1.139(4)
1.152(4)
1.147(4)
1.137(4)
1.146(4)
1.150(4)
1.153(4)
1.157(4)
1.151(4)
2.344(1)
2.096(2)
2.155(2)
Fe(1)-C(10)-C(11) 155.1(2) Fe(3)-C(7)-O(7)
176.5(2)
178.4(2)
176.0(2)
55.80(1)
62.51(1)
61.70(1)
Fe(1)-C(1)-O(1)
Fe(1)-C(2)-O(2)
Fe(1)-C(3)-O(3)
Fe(2)-C(4)-O(4)
Fe(2)-C(5)-O(5)
Fe(2)-C(6)-O(6)
178.8(2) Fe(3)-C(8)-O(8)
177.8(2) Fe(3)-C(9)-O(9)
178.9(2) Fe(2)-Fe(1)-Fe(3)
177.2(2) Fe(3)-Fe(2)-Fe(1)
175.8(2) Fe(2)-Fe(3)-Fe(1)
177.8(2)
C(10)-C(11)-O(10) 145.2(3) C(11)-O(10)-Ti(1) 148.0(2)
C(11)-C(10)-Fe(1) 156.4(3) Fe(3)-C(7)-O(7)
174.3(3)
179.7(4)
178.4(3)
61.55(2)
62.08(2)
56.37(2)
Fe(1)-C(1)-O(1)
Fe(1)-C(2)-O(2)
Fe(1)-C(3)-O(3)
Fe(2)-C(4)-O(4)
Fe(2)-C(5)-O(5)
Fe(2)-C(6)-O(6)
178.7(4) Fe(3)-C(8)-O(8)
176.9(4) Fe(3)-C(9)-O(9)
177.1(4) Fe(1)-Fe(2)-Fe(3)
178.2(3) Fe(1)-Fe(3)-Fe(2)
178.9(4) Fe(2)-Fe(1)-Fe(3)
175.7(4)
Ta ble 4. Atom ic Coor d in a tes (Å × 104) a n d
Equ iva len t Isotr op ic Disp la cem en t P a r a m eter s (Å2
× 103) for [F e3(CO)9(CCOTi(THF )4Cl] (III)
a
atom
x
y
z
Ueq
Ta ble 6. Bon d Len gth s (Å) a n d An gles (d eg) in
Clu ster s Con ta in in g Eth yn es
Fe(1)
Fe(2)
Fe(3)
C(1)
O(1)
C(2)
O(2)
C(3)
O(3)
C(4)
O(4)
C(5)
O(5)
C(6)
O(6)
C(7)
O(7)
C(8)
2862(1)
4321(1)
3774(1)
3991(4)
4698(3)
1652(4)
838(3)
4266(1)
4888(1)
3534(1)
4063(2)
3920(2)
3607(2)
3180(2)
5080(2)
5596(2)
4737(2)
4648(2)
5831(2)
6441(2)
5100(2)
5246(2)
3076(2)
2736(1)
3421(2)
3343(2)
2806(2)
2328(1)
4408(2)
4432(2)
4554(1)
4612(1)
4703(1)
3768(1)
5424(1)
3783(1)
5482(1)
719(1)
1923(1)
1966(1)
142(2)
-223(2)
342(2)
124(2)
241(2)
-58(2)
1493(2)
1236(2)
1653(2)
1490(2)
2842(2)
3448(2)
1406(2)
1089(2)
2831(2)
3397(2)
1988(2)
2016(2)
1637(2)
2361(2)
2952(1)
3374(1)
3871(1)
2651(1)
4112(1)
4149(1)
2600(1)
29(1)
28(1)
26(1)
41(1)
62(1)
35(1)
53(1)
42(1)
65(1)
34(1)
48(1)
38(1)
61(1)
38(1)
62(1)
32(1)
44(1)
36(1)
54(1)
32(1)
48(1)
24(1)
25(1)
26(1)
24(1)
39(1)
33(1)
29(1)
29(1)
29(1)
C-C
Fe-C-C
ref
I
1.293(3)
1.304(4)
1.28(1)
1.288(5)
1.314(8)
155.1(2)
156.4(3)
159.9(7)
161.6(3)
150.6(4)
a
a
4
4
24
III
[PPN][Fe3(CO)9CCRe(CO)5]
[PPN][Fe3(CO)9(CCFeCp(CO)2)]
[PPN][Fe3(CO)9(CCOC(O)CH3)]
2139(4)
1625(3)
5664(4)
6539(3)
3916(4)
3669(3)
5170(3)
5646(3)
4710(3)
5342(2)
4891(4)
5618(3)
2635(4)
1916(3)
2546(3)
2821(3)
2356(2)
895(1)
a
This work.
Ta ble 7. 13C NMR Da ta for Clu ster s Con ta in in g
Eth yn es
CR
Câ
ref
I
III
81.0
154.5
279
a
a
4
10
10
[PPN]2[Fe3(CO)9(CCO)]
[PPN][Fe3(CO)9(CCOEt)]
[PPN][Fe3(CO)9(CCOAc)]
90.1
160.7
172.9
182.2
148.5
132.2
O(8)
C(9)
a
O(9)
C(10)
C(11)
O(10)
Ti(1)
Cl(1)
O(20)
O(30)
O(40)
O(50)
This work.
titanium with [Fe3(CO)9(CCO)]2- from the resulting oily
mass of I when the reaction to produce I was run on
very large, 20 g scale of [PPN]2[Fe3(CO)9(CCO)] starting
-965(1)
-38(2)
1876(2)
1677(2)
90(2)
material. Spectroscopic evidence, νCO at 1779 cm-1
,
suggests its presence in earlier preparations. To deter-
mine if III is an intermediate in the formation of I, the
reaction of [Fe3(CO)9(CCO)]2- with TiCl3(DME)1.5 was
explored. This reaction formed III rapidly and in good
yield (53% yield, based on iron). The infrared spec-
trum of the neutral cluster, III, is very similar to that
of the monoanionic cluster I. The R substituents of the
CCR ligand in [Fe3(CO)9(CCR)]n (n ) 0 or -1) do not
cause large changes in the electron density as judged
by infrared stretching frequencies of the terminal car-
bonyls for similar types of clusters, whether the CC
moiety is ethynyl (R ) H, OTi(THF)4Cl, OC(O)CH3,28
or OCH2CH328) or ethenyl (CCR ) CH3CCCH3,
CH3CCH2Ph, or CH3CCCH2-t-Bu);18,29,30 compounds
a
Ueq is defined as 1/3 the trace of the Uij tensor.
The interactions of the -CCO ligand with the metal
cluster may be regarded as a σ bond to Fe1 and two π
bonds to the Fe2-Fe3 edge. The three iron atoms
interact with C10, with bond distances of 1.818(3),
2.015(3), and 2.034(3) Å for Fe1, Fe2, and Fe3. The C-C
bond length, 1.304(4) Å, is within the range for kete-
nylidene ligands. The C11-O10 bond (1.310(4) Å) is
indicative of a single bond. The Ti-O bonds for the four
Ti-THF interactions are all similar, with an average
bond length of 2.11 Å; however, the Ti-OCC bond is
much shorter, 1.875(2) Å.
(28) Hriljac, J . A.; Shriver, D. F. J . Am. Chem. Soc. 1987, 109, 6010.
(29) Lourdichi, M.; Mathieu, R. Organometallics 1986, 5, 2067-71.
(30) Nuel, D.; Mathieu, R. Organometallics 1988, 7, 16-21.
[Fe3(CO)9(CCOTi(THF)4Cl)] (III) was also isolated in
less than 1% yield from the reaction of low-valent

538 Organometallics, Vol. 18, No. 4, 1999
Eveland et al.
lengths, to determine the effective charge by the “sum
of valence bonds” method.30 This calculation gave a
value of 3.1, indicating paramagnetic Ti(III). The broad-
ening of the 13C NMR spectrum for III also provides
qualitative confirmation of a Ti(III) species. Further-
more, an EPR spectrum of III indicates a paramagnetic
species, with splitting values for gx, gy, and gz of 2.05,
2.02, and 1.96 for a solid-state sample. These values are
within the expected range for Ti(III).32,33 Magnetic
susceptibility was determined by the Evans method,34
and this measurement (2.01 µB for III) indicates the
presence of Ti(III). A variable-temperature magnetic
susceptibility (SQUID) measurement of III over the
temperature range 5 to 300 K reveals a magnetic
moment of 2.64 µB, indicating a Ti(II) species. It appears
that paramagnetic Ti species are present. A variable-
temperature magnetic susceptibility measurement, over
the same temperature range, for [PPN]2[Fe3(CO)9(CCO)]
indicated paramagnetic behavior, with a much lower
magnetic moment of 0.091 µB. The paramagnetic be-
havior for III and that for [PPN]2[Fe3(CO)9(CCO)] in the
SQUID measurements may arise from an adventitious
impurity.
F igu r e 1. Thermal ellipsoid plot of [PPN][Fe3(CO)9(Ct
CH)] (I) at 50% probability.
F u r th er Rea ction s of [P P N][F e3(CO)9(CCH)] (I).
The reaction of I with the strong proton source, triflic
acid, does not yield II; instead protonation occurs at the
metal core yielding [HFe3(CO)9(CCH)] (IV) in a quan-
titative yield. This cluster has been previously re-
ported.18 The 1H NMR of IV contains a large, sharp
upfield feature at -20.0 ppm assigned to the metal-
bridging hydride. This value is higher than the reported
value of -27.8 ppm.18 Repetition of our NMR experi-
ment gave the same result, and the previously reported
peak was not observed. The observed protonation at the
metal core is contrary to our expectation that protona-
tion should occur at the â carbon of I, by analogy with
the structure of II. Under an atmosphere of CO, a
solution of I in THF converts to II after several days.
This reaction is accompanied by some decomposition of
I. The solvent was freshly distilled and all solids were
stored in a drybox, so the hydrogen needed to form II
may originate by H abstraction from the solvent.
Rea ction of th e McMu r r y Rea gen t. Reaction of the
low-valent titanium compound with Ru3(CO)12, [PPN]2-
[Ru3(CO)9(CCO)], [PPN]2[Os3(CO)9(CCO)], and [PPN]2-
[Ru6(CO)16C] leads to the formation of the known
hydride compounds [H4Ru4(CO)12],35 [H2Ru3(CO)9-
(CCO)],36 [H2Os3(CO)9(CCO)],37 and [H2Ru6(CO)16C],38
respectively, presumably through H abstraction from
the solvent or from adventitious water. Apparently, the
basic nature of these clusters leads to the formation of
hydrides. We obtained evidence for the formation of
compounds similar to III in the reaction of the titanium
F igu r e 2. Thermal ellipsoid plot of [Fe3(CO)9(CCOTi-
(THF)4Cl)] (III) at 50% probability.
that have similar R groups will have similar ranges of
CO stretching frequencies.
At 20 °C, the spectrum for a 13C-enriched sample of
III shows a broad feature from δ 210 to 230 ppm, with
peaks at 228.3, 223.8, 220.7, 217.8, 214.0, and 210.5
ppm, and the peaks for the R and â carbon are not
observed. At -80 °C, four broad peaks (∼4 ppm) are
observed at δ 226.8, 219.2, 214.4, and 209.6 ppm, and
another broad feature (∼11 ppm) is seen at 279 ppm,
which we assign to the â carbon of the ketenylidene. A
weak peak for the R carbon is observed in similar
compounds, but is not observed in the present case. The
position of the â carbon is shifted to a higher field
relative to those observed in similar structures (Table
7).4,10 The observed NMR line widths and shifts are in
line with the paramagnetism of the sample.
reagent with [Ru3(CO)9(CCO)]2- or [Os3(CO)9(CCO)]2-
.
(31) Palenik, G. J . Inorg. Chem. 1997, 36, 3394-7.
(32) Abragam, A.; Bleaney, B. Electron Paramagnetic Resonance of
Transition Ions; Dover Publications: New York, 1988.
(33) Pilbrow, J . R. Transition Ion Electron Paramagnetic Resonance;
Clarendon Press: Oxford, 1990.
(34) Evans, D. F. J . Chem. Soc. 1959, 2003-5.
Ma gn et ic P r op er t ies. Assuming that no redox
chemistry occurs upon formation of III, electron count-
ing indicates that the titanium should be Ti(III). Several
methods were used to infer the oxidation state of
titanium in [Fe3(CO)9(CCOTi(THF)4Cl)]. One of these
involved the examination of the titanium-atom bond
(35) Bruce, M. I.; Williams, M. L. Inorg. Synth. 1989, 26, 262-263.
(36) Holmgren, J . S.; Shapley, J . R. Organometallics 1984, 3, 1322-
223.
(37) Sievert, A. C.; Strickland, D. S.; Shapley, J . R.; Steinmetz, G.
R.; Geoffroy, G. L. Organometallics 1982, 1, 214-5.
(38) J ohnson, B. F. G.; Lewis, J .; Sankey, S. W.; Wong, K.; McPartlin,
M.; Nelson, W. J . H. J . Organomet. Chem. 1980, 191, C3-C7.

Reaction of Ti with [Fe3(CO)9(CCO)]2-
Organometallics, Vol. 18, No. 4, 1999 539
Thus, for the reaction with ruthenium ketenylidene, a
peak in the infrared spectrum was observed at 1650
cm-1. This evidence for Ti coordination to the oxygen
of the CCO ligand plus a parent peak at 966.5 m/z in
the mass spectrum indicates the presence of [Ru3(CO)9-
(CCOTi(THF)4Cl)]. Similarly, reaction of the titanium
reagent with the osmium ketenylidene produces a
product with an infrared stretching frequency peak at
1728 cm-1, which is attributed to the CO stretch of CCO
in [Os3(CO)9(CCOTi(THF)4Cl)].
approach for the generation of the C2 ligand in a metal
cluster. Previously ethynyl ligands were introduced into
metal clusters by alkyne starting materials. The 13C
NMR spectra of the ethynyl cluster and a related mixed
metal iron-titanium cluster containing the ketenylidene
ligand are reported.
Ack n ow led gm en t. We thank Charlotte Stern of
Northwestern University and Susie Miller of Colorado
State University for their assistance in collecting the
crystallographic data. This research was sponsored by
the Department of Energy Grant DE-FG02-86ER13640.
Con clu sion s
Reaction of [Fe3(CO)9(CCO)]2- with a low-valent
titanium source converts the CCO to an ethynyl ligand.
Apparently, a low-oxidation-state Ti species serves as
both an oxophile and reducing agent, to afford a new
Su p p or tin g In for m a tion Ava ila ble: Crystallographic
data for Ia , Ib, and III. This material is available free of charge
via the Internet at http://pubs.acs.org.
OM9806085