Unusual reactions of cationic bridging carbyne complexes of bis(η5-cyclopentadienyl)diiron tricarbonyl with carbonylmetal anions. A route to diiron bridging carbyne complexes

Article abstract of DOI:10.1021/om0002529

The reactions of cationic carbyne complexes of diiron, [Fe₂(μ-CO)(μ-CPh)(CO)₂ (η⁵-C₅H₅)₂]-BBr₄ (1), with the anionic carbonylmetal compounds Na[M (CO)₅CN] (3, M = Cr; 4, M = Mo; 5, M = W) in THF at low temperature afford the novel bridging carbyne complexes [Fe₂(μ-CO)(μ-CPh)(CO)₂ (η⁵-C₅H₅)₂NCM(CO)₅] (6, M = Cr; 7, M = Mo; 8, M = W). In contrast to the reaction of 1, the cationic carbyne complex [Fe₂(μ-CO)(μ-CC₆H₄Me-p)(CO)₂(η⁵-C₅ H₅)₂]BBr₄ (2) reacts with carbonylmetal anions 3-5 under the same conditions to produce the novel bridging p-tolyl(pentacarbonylcyanotungsten)carbene complexes [Fe₂(μ-CO) {μ-C(C₆H₄Me-p)(CO)₂(η⁵-C₅H₅)₂ NCM(CO)₅}] (9, M = Cr; 10, M = Mo; 11, M = W). However, the analogous reaction of Na[Fe(CO)₄CN] with 1 yields the diiron bridging phenylcarbene complex [Fe₂(μ-CO){μ- C(H)Ph}(CO)₂(η⁵-C₅H₅)₂] (12). The structures of 7, 8, and 11 have been established by X-ray crystallography.

Full text of DOI:10.1021/om0002529

3784
Organometallics 2000, 19, 3784-3790
Un u su a l Rea ction s of Ca tion ic Br id gin g Ca r byn e
Com p lexes of Bis(η5-cyclop en ta d ien yl)d iir on Tr ica r bon yl
w ith Ca r bon ylm eta l An ion s. A Rou te to Diir on Br id gin g
Ca r byn e Com p lexes
Yajun Liu, Ruitao Wang, J ie Sun, and J iabi Chen*
Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese
Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China
Received May 22, 2000
The reactions of cationic carbyne complexes of diiron, [Fe2(µ-CO)(µ-CPh)(CO)2(η5-C5H5)2]-
BBr4 (1), with the anionic carbonylmetal compounds Na[M(CO)5CN] (3, M ) Cr; 4, M ) Mo;
5, M ) W) in THF at low temperature afford the novel bridging carbyne complexes [Fe2(µ-
CO)(µ-CPh)(CO)2(η5-C5H5)2NCM(CO)5] (6, M ) Cr; 7, M ) Mo; 8, M ) W). In contrast to the
reaction of 1, the cationic carbyne complex [Fe2(µ-CO)(µ-CC6H4Me-p)(CO)2(η5-C5H5)2]BBr4
(2) reacts with carbonylmetal anions 3-5 under the same conditions to produce the novel
bridging p-tolyl(pentacarbonylcyanotungsten)carbene complexes [Fe2(µ-CO){µ-C(C6H4Me-
p)(CO)2(η5-C5H5)2NCM(CO)5}] (9, M ) Cr; 10, M ) Mo; 11, M ) W). However, the analogous
reaction of Na[Fe(CO)4CN] with 1 yields the diiron bridging phenylcarbene complex [Fe2-
(µ-CO){µ-C(H)Ph}(CO)2(η5-C5H5)2] (12). The structures of 7, 8, and 11 have been established
by X-ray crystallography.
In tr od u ction
drides or cationic metal compounds. Recently, we have
shown a convenient and useful method for the prepara-
tion of the bridging carbene and carbyne complexes: the
reactions of highly electrophilic cationic carbyne com-
plexes of manganese and rhenium, [(η5-C5H5)(CO)2-
MtCPh]BBr4 (M ) Mn, Re), with dianionic carbonyl-
metal compounds such as Na2[Fe(CO)4], (Et4N)2[Fe2-
(CO)8], and Na2[W(CO)5], monoanionic carbonylmetal
compounds such as (Me4N)[HFe(CO)4], Na[(η5-C5H5)M-
(CO)x] (M ) Mo, W, x ) 3; M ) Fe, x ) 2), and Na[Co-
(CO)3PPh3], or anionic mixed-dimetal carbonyl com-
pounds such as (Ph3P)2N[MCo(CO)n] (M ) Fe, W; n )
8, 9).7,8 However, the reaction of carbonylmetal anionic
compounds containing a CN group such as Na[Fe-
(CO)4CN] and Na[W(CO)5CN] with cationic carbyne
complexes [(η5-C5H5)(CO)2MtCPh]BBr4 (M ) Mn, Re)
did not give dimetal bridging carbene or bridging
carbyne complexes but produced instead phenyl(carbo-
nylcyanometal)carbene complexes, [(η5-C5H5)(CO)2-
MdC(Ph)NCM′(CO)n] (M ) Mn, Re; M′ ) Fe, W; n ) 4,
5) (eq 1).8a,f
Metal-metal-bonded cluster complexes are well-
known to have important roles in many catalytic reac-
tions.1,2 The current interest in the synthesis, structure,
and chemistry of transition-metal bridging carbene and
carbyne complexes stems from the fact that many such
complexes are themselves metal clusters or are the
precursors of metal cluster complexes. In recent years,
we have been interested in developing the methodolo-
gies of the synthesis of transition-metal bridging car-
bene and carbyne complexes. A considerable number of
dimetal complexes containing bridging carbene and
carbyne ligands have been synthesized by Stone and co-
workers by reactions3-6 of carbene or carbyne complexes
with low-valent metal species or by reactions5,6 of
neutral or anionic carbyne complexes with metal hy-
(1) Suess-Fink, G.; Meister, G. Adv. Organomet. Chem. 1993, 35,
41.
(2) (a) Gladfelter, W. L.; Roesselet, K. J . In The Chemistry of Metal
Cluster Complexes; Shriver, D. F., Kaesz, H. D., Adams, R. D., Eds.;
VCH: Weinheim, Germany, 1990; p 392. (b) Maire, G. In Metal
Clusters in Catalysis; Gates, B. C., Guczi, L., Knoezinger, H., Eds.;
Elsevier: Amsterdam, The Netherlands, 1986; p 509. (c) Dickson, R.
S.; Greaves, B. C. Organometallics 1993, 12, 3249.
(3) Stone, F. G. A. In Advances in Metal Carbene Chemistry;
Schubert, U., Ed.; Kluwer Academic: Dordrecht, The Netherlands,
1989; p 11.
(4) (a) Ashworth, T. V.; Howard, J . A. K.; Laguna, M.; Stone, F. G.
A. J . Chem. Soc., Dalton Trans. 1980, 1593. (b) Carriedo, G. A.;
Howard, J . A. K.; Stone, F. G. A. J . Chem. Soc., Dalton Trans. 1984,
1555. (c) Garcia, M. E.; J effery, J . C.; Sherwood, P.; Stone, F. G. A. J .
Chem. Soc., Dalton Trans. 1987, 1209. (d) Busetto, L.; J effery, J . C.;
Mills, R. M.; Stone, F. G. A.; Went, M. J .; Woodward, P. J . Chem. Soc.,
Dalton Trans. 1983, 101.
(5) (a) Howard, J . A. K.; Mead, K. A.; Moss, J . R.; Navarro, R.; Stone,
F. G. A.; Woodward, P. J . Chem. Soc., Dalton Trans. 1981, 743. (b)
Hodgson, D.; Howard, J . A. K.; Stone, F. G. A.; Went, M. J . J . Chem.
Soc., Dalton Trans. 1985, 331.
Most recently, we found a new method for the prepa-
ration of dimetal bridging carbene complexes: the
reactions of diiron cationic carbyne complexes, [Fe2(µ-
CO)(µ-CAr)(CO)2(η5-C5H5)2]BBr4 (1, Ar ) Ph; 2, Ar )
p-MeC6H4), with anionic carbonylmetal nucleophiles.
For instance, the cationic carbyne complexes 1 and 2
(7) (a) Chen, J .-B.; Yu, Y.; Liu, K.; Wu, G.; Zheng, P.-J . Organome-
tallics 1993, 12, 1213. (b) Yu, Y.; Chen, J .-B.; Chen, J .; Zheng, P.-J .;
J . Chem. Soc., Dalton Trans. 1996, 1443.
(8) (a) Tang, Y.-J .; Sun, J .; Chen, J .-B. Organometallics 1999, 18,
4337. (b) Tang, Y.-J .; Sun, J .; Chen, J .-B. J . Chem. Soc., Dalton Trans.
1998, 931. (c) Tang, Y.- J .; Sun, J .; Chen, J .-B. J . Chem. Soc., Dalton
Trans. 1998, 4003.(d) Tang, Y.-J .; Sun, J .; Chen, J .-B. Organometallics
1998, 17, 2945. (e) Tang, Y.-J .; Sun, J .; Chen, J .-B. Organometallics
2000, 19, 72. (f) Tang, Y.-J .; Sun, J .; Chen, J .-B. Organometallics 1999,
18, 2459.
(6) Pilotti, M. U.; Stone, F. G. A.; Topaloglu, L. J . Chem. Soc., Dalton
Trans. 1991, 1621.
10.1021/om0002529 CCC: $19.00 © 2000 American Chemical Society
Publication on Web 08/22/2000

A Route to Diiron Bridging Carbyne Complexes
Organometallics, Vol. 19, No. 19, 2000 3785
(η5-C5H5)2]BBr4 (1)9 and [Fe2(µ-CO)(µ-CC6H4Me-p)(CO)2(η5-
C5H5)2]BBr4 (2)9 were prepared as previously described. The
compounds Na[Cr(CO)5CN] (3),10 Na[Mo(CO)5CN] (4),10 Na-
[W(CO)5CN] (5),10 and Na[Fe(CO)4CN]11 were prepared by
literature methods.
IR spectra were measured on a Perkin-Elmer 983G spec-
trophotometer. All 1H NMR spectra were recorded at ambient
temperature in acetone-d6 solution with TMS as the internal
reference using a Bruker AM-300 spectrometer. Electron
ionization mass spectra (EIMS) were run on a Hewlett-
Packard 5989A spectrometer. Melting points obtained on
samples in sealed, nitrogen-filled capillaries are uncorrected.
Rea ction of [F e2(µ-CO)(µ-CP h )(CO)2(η5-C5H5)2]BBr 4 (1)
w ith Na [Cr (CO)5CN] (3) To Give [F e2(µ-CO)(µ-CP h )(CO)2-
(η5-C5H5)2NCCr (CO)5] (6). To 0.270 g (0.362 mmol) of freshly
prepared (in situ) 1 dissolved in 50 mL of THF at -90 °C was
added 0.100 g (0.415 mmol) of Na[Cr(CO)5CN] (3). The reaction
mixture was warmed slowly to -75 °C within 1 h, during
which time the turbid red solution gradually turned brown-
red. After it was stirred at -75 to -30 °C for an additional 3
h, the resulting solution was evaporated in vacuo at -30 °C
to dryness, and the deep red residue was chromatographed
on Al2O3 at -25 °C with petroleum ether/CH2Cl2 (10:1) as the
eluant. After elution of a small light yellow band which
contained Cr(CO)6, a red band was collected. The solvent was
removed under vacuum, and the residue was recrystallized
from petroleum ether/CH2Cl2 (10:1) at -80 °C to give 0.140 g
(64%, based on 1) of purple-red crystals of 6: mp 82-84 °C
dec; IR (CH2Cl2) ν(CO) 2056 (s), 2016 (w),1987 (s), 1933 (vs),-
reacted with nucleophiles NaER (ER ) SMe, SEt, SPh,
SC6H4Me-p, SC6H4NO2-p, OPh, N(SiMe3)2) to give the
series of diiron bridging carbene complexes [Fe2(µ-CO)-
{µ-C(ER)Ar}(CO)2(η5-C5H5)2] (eq 2).9 This offers a new
1
1772 (m) cm-1; ν(CN) 2059 (w) cm-1; H NMR (CD3COCD3) δ
8.36 (m, 2 H, C6H5), 7.74 (m, 2 H, C6H5), 7.36 (m, 1 H, C6H5),
5.84 (d, 2 H, C5H5), 5.62 (s, 1 H, C5H5), 5.48 (s, 1 H, C5H5),
5.34 (t, 3 H, C5H5), 4.90 (t, 3 H, C5H5); MS m/e 359 (M+ - CO
- Cr(CO)5CN), 254 [Fe2(η5-C5H5)2C+], 238 [Fe(CO)(η5-C5H5)-
CPh+], 218 [Cr(CO)5CN+], 192 [Cr(CO)5+]. Anal. Calcd for
C
25H15O7NCrFe2: C, 49.62; H, 2.50; N, 2.31. Found: C, 49.40;
H, 2.56; N, 2.60.
Rea ction of 1 w ith Na [Mo(CO)5CN] (4) To Give [F e2-
(µ-CO)(µ-CP h )(CO)2(η5-C5H5)2NCMo(CO)5] (7). Similar to
the case for the reaction of 1 with 3, compound 1 (0.270 g,
0.362 mmol) was treated with 0.124 g (0.430 mmol) of Na[Mo-
(CO)5CN] (4) at -90 to -30 °C for 4-5 h. Further treatment
of the resulting mixture as described above for the preparation
of 6 yielded 0.176 g (75%, based on 1) of purple-red crystalline
7: mp 96-97 °C dec; IR (CH2Cl2) ν(CO) 2053 (m), 2013 (w),
and useful method for the preparation and structural
modification of dimetal bridging carbene complexes.
To explore the reactivity of the cationic carbyne
complexes of diiron and to further examine the scope of
this preparation of dimetal bridging carbene and bridg-
ing carbyne complexes, we have studied the reactions
of the cationic diiron bridging carbyne complexes 1 and
2 with anionic carbonylmetal compounds of the type Na-
[M(CO)5CN] (M ) Cr, Mo, W). These reactions produced
a series of novel trimetal bridging carbene and bridging
carbyne complexes. Herein we report these unusual
reactions and the structural characterizations of the
resulting products.
1998 (s), 1937 (vs), 1795 (s) cm-1, ν(CN) 2060 (w) cm-1 1H
;
NMR (CD3COCD3) δ 8.34-7.26 (m, 5 H, C6H5), 5.85 (t, 3 H,
C5H5), 5.63 (s, 1 H, C5H5), 5.50 (s, 1 H, C5H5), 5.24 (d, 2 H,
C5H5), 5.22 (s, 1 H, C5H5), 5.14 (s, 1 H, C5H5), 5.07 (s, 1 H,
C5H5), 4.91 (s, 1 H, C5H5); MS m/e 359 (M+ - CO - Mo(CO)5-
CN), 254 [Fe2(η5-C5H5)2C+], 238 [Fe(CO)(η5-C5H5)CPh+], 262
[Mo(CO)5CN+], 236 [Mo(CO)5+]. Anal. Calcd for C25H15O7-
NMoFe2: C, 46.27; H, 2.33; N, 2.16. Found: C, 46.22; H, 2.55;
N, 2.56.
Rea ction of 1 w ith Na [W(CO)5CN] (5) To Give [F e2(µ-
CO)(µ-CP h )(CO)2(η5-C5H5)2NCW(CO)5] (8). The procedure
used in the reaction of 1 (0.270 g, 0.362 mmol) with Na-
[W(CO)5CN] (5) (0.162 g, 0.430 mmol) was the same as that
described for the reaction of 1 with 3 at -90 to -30 °C for
4-5 h. Further treatment as described for the preparation of
6 gave 0.213 g (80%, based on 1) of blackish red crystals of 8:
mp 90-92 °C dec; IR (CH2Cl2) ν(CO) 2045 (s), 2022 (m), 1998
Exp er im en ta l Section
All procedures were performed under a dry, oxygen-free N2
atmosphere using standard Schlenk techniques. All solvents
employed were reagent grade and were dried by refluxing over
appropriate drying agents and stored over 4 Å molecular sieves
under a N2 atmosphere. Tetrahydrofuran (THF) and diethyl
ether (Et2O) were distilled from sodium benzophenone ketyl,
while petroleum ether (30-60 °C) and CH2Cl2 were distilled
from CaH2. The neutral alumina (Al2O3) used for chromatog-
raphy was deoxygenated at room temperature under high
vacuum for 16 h, deactivated with 5% w/w N2-saturated water,
and stored under N2. The complexes [Fe2(µ-CO)(µ-CPh)(CO)2-
(s), 1926 (vs), 1771 (s) cm-1; ν(CN) 2051 (w) cm-1 1H NMR
;
(CD3COCD3) δ 8.47 (m, 2 H, C6H5), 7.73 (m, 2 H, C6H5), 7.34
(m, 1 H, C6H5), 5.90 (d, 2 H, C5H5), 5.78 (d, 2 H, C5H5), 5.49 (s,
1 H, C5H5), 5.34 (s, 1 H, C5H5), 5.30 (m, 2 H, CH2Cl2), 5.24 (s,
1 H, C5H5), 5.14 (s, 1 H, C5H5), 5.05 (s, 1 H, C5H5), 4.90 (s, 1
H, C5H5); MS m/e 359 [M+ - CO - W(CO)5CN], 254 [Fe2(η5-
(9) Liu, Y.-J .; Wang, R.-T.; Sun, J .; Chen, J .-B. Organometallics, in
press.
(10) King, R. B. Inorg. Chem. 1967, 6, 25.
(11) Wannaga, U.; Seyffert, H. Angew. Chem. 1965, 77, 457.

3786 Organometallics, Vol. 19, No. 19, 2000
Liu et al.
C5H5)2C+], 238 [Fe(CO)(η5-C5H5)CPh+], 350 [W(CO)5CN+], 84
(CH2Cl2+). Anal. Calcd for C25H15O7NWFe2‚CH2Cl2: C, 38.00;
H, 2.09; N, 1.70. Found: C, 38.61; H, 2.44; N, 2.01.
254 (M+ - 3CO - Ph - H). Anal. Calcd for C20H16O3Fe2: C,
57.74; H, 3.88. Found: C, 57.57; H, 3.73.
X-r a y Cr ysta l Str u ctu r e Deter m in a tion s of Com p lexes
7, 8, a n d 11. The single crystals of 7, 8, and 11 suitable for
X-ray diffraction study were obtained by recrystallization from
petroleum ether/CH2Cl2 solution at -80 °C. Single crystals
were mounted on a glass fiber and sealed with epoxy glue. The
X-ray diffraction intensity data for 3557, 3343, and 3281
independent reflections, of which 2071 and 2276 with I >
2.00σ(I) for 7 and 11 and 2554 with I > 3.00σ(I) for 8 were
observable, were collected with a Rigaku AFC7R diffractome-
ter at 20 °C using Mo KR radiation with an ω-2θ scan mode
within the ranges 5° e 2θ e 50° for 7 and 5°e 2θ e 45° for 8
and 11, respectively.
The structures of 7 and 11 were solved by direct methods
and expanded using Fourier techniques. The non-hydrogen
atoms were refined anisotropically. The hydrogen atoms were
included but not refined. The final cycle of full-matrix least-
squares refinement was respectively based on 2071 and 2276
observed reflections and 325 and 361 variable parameters and
converged with unweighted and weighted agreement factors
Rea ction of [F e2(µ-CO)(µ-CC6H4Me-p)(CO)2(η5-C5H5)2]-
BBr 4 (2) w ith 3 To Give [F e2(µ-CO){µ-CC6H4Me-p)NCCr -
(CO)5}(CO)2(η5-C5H5)2] (9). To 0.240 g (0.316 mmol) of freshly
prepared (in situ) 2 dissolved in 50 mL of THF at -90 °C was
added 0.081 g (0.336 mmol) of 3. The reaction mixture was
slowly warmed to -65 °C within 1 h, during which time the
turbid red solution gradually turned brown-red. After it was
stirred at -65 to -30 °C for an additional 3 h, the resulting
clear deep red solution was evaporated in vacuo at -30 °C to
dryness, and the brown-red residue was chromatographed on
Al2O3 at -25 °C with petroleum ether/CH2Cl2 (15:1) as the
eluant. A purple-red band was eluted and collected. After
vacuum removal of the solvent, the crude product was recrys-
tallized from petroleum ether/CH2Cl2 (10:1) solution at -80
°C to give 0.116 g (57%, based on 2) of purple-red crystals of
9: mp 157-158 °C dec; IR (CH2Cl2) ν(CO) 2057 (m), 2015 (s),
1993 (s), 1933 (vs), 1927 (s), 1772 (w) cm-1, ν(CN) 2127 (w)
1
cm-1; H NMR (CD3COCD3) δ 8.29-7.36 (m, 4 H, C6H4CH3),
5.80 (s, 10 H, C5H5), 2.54 (s, 3 H, C6H4CH3); MS m/e 373 (M+
- CO - Cr(CO)5CN), 254 [Fe2(η5-C5H5)2C+], 252 [Fe(CO)(η5-
C5H5)(C6H4Me-p)+], 218 [Cr(CO)5CN+], 192 [Cr(CO)5+]. Anal.
Calcd for C27H17O8NCrFe2: C, 50.11; H, 2.65; N, 2.16. Found:
C, 50.18; H, 2.58; N, 2.24.
of R ) 0.049 and Rw ) 0.050 for 7 and R ) 0.056 and Rw
)
0.071 for 11, respectively. The structure of 8 was solved by
heavy-atom Patterson methods and expanded using Fourier
techniques. Some non-hydrogen atoms were refined anisotro-
pically, while the rest were refined isotropically. The hydrogen
atoms were included but not refined. The final cycle of full-
matrix least-squares refinement was based on 2554 observed
reflections and 337 variable parameters and converged with
unweighted and weighted agreement factors of R ) 0.056 and
Rw ) 0.067. All of the calculations were performed using the
teXsan crystallographic software package of Molecular Struc-
ture Corp.
Rea ction of 2 w ith 4 To Give [F e2(µ-CO){µ-CC6H4Me-
p)NCMo(CO)5}(CO)2(η5-C5H5)2] (10). Similar to the reaction
of 2 with 3, 0.230 g (0.302 mmol) of 2 reacted with 0.091 g
(0.320 mmol) of 4 at -90 to -30 °C for 4-5 h. Further
treatment of the resulting mixture as described for the
preparation of 9 yielded 0.150 g (70%, based on 2) of 10 as
purple-red crystals: mp 65-66 °C dec; IR (CH2Cl2) ν(CO) 2054
(s), 2015 (s), 1998 (s), 1935 (vs, br), 1792 (w) cm-1, ν(CN) 2125
The details of the crystallographic data and the procedures
used for data collection and reduction information for 7, 8, and
11 are given in Table 1. Selected bond lengths and angles are
listed in Table 2. The atomic coordinates and Biso/Beq values,
anisotropic displacement parameters, all bond lengths and
angles, and least-squares planes for 7, 8, and 11 are given in
the Supporting Information. The molecular structures of 7, 8,
and 11 are given in Figures 1-3, respectively.
1
(w) cm-1; H NMR (CD3COCD3) δ 8.30-7.36 (m, 4 H, C6H4-
CH3), 5.81 (s, 10 H, C5H5), 3.29 (s, 2 H, H2O), 2.54 (s, 3 H,
C6H4CH3); MS m/e 373 (M+ - CO - Mo(CO)5CN), 254 [Fe2-
(η5-C5H5)2C+], 252 [Fe(CO)(η5-C5H5)(C6H4Me-p)+], 262 [Mo-
(CO)5CN+]. Anal. Calcd for C27H17O8NMoFe2‚H2O: C, 45.73;
H, 2.70; N, 1.97. Found: C, 45.45; H, 2.52; N, 2.07.
Rea ction of 2 w ith 5 To Give [F e2(µ-CO){µ-CC6H4Me-
p)NCW(CO)5}(CO)2(η5-C5H5)2] (11). As described for the
reaction of 2 with 3, compound 2 (0.240 g, 0.316 mmol) was
treated with 5 (0.125 g, 0.335 mmol) at -90 to -30 °C for 4-5
h. Further treatment of the resulting mixture similar to that
used in the reaction of 2 with 3 gave 0.191 g (76%, based on
2) of purple-red crystalline 11: mp 64-65 °C dec; IR (CH2Cl2)
ν(CO) 2051 (m), 2015 (s), 1995 (s), 1933 (vs), 1926 (vs), 1791
(w) cm-1, ν(CN) 2125 (w) cm-1; 1H NMR (CD3COCD3) δ 8.37-
7.37 (m, 4 H, C6H4CH3), 5.81 (s, 10 H, C5H5), 3.32 (s, 2 H, H2O),
2.59 (s, 3 H, C6H4CH3); MS m/e 373 (M+ - CO - W(CO)5CN),
254 [Fe2(η5-C5H5)2C+], 252 [Fe(CO)(η5-C5H5)(C6H4Me-p)+], 350
[W(CO)5CN+]. Anal. Calcd for C27H17O8NWFe2‚H2O: C, 40.69;
H, 2.40; N, 1.76. Found: C, 40.45; H, 2.31; N, 1.75.
Rea ction of 1 w ith Na [F e(CO)5CN] To Give [F e2(µ-CO)-
{µ-C(H)P h }(CO)2(η5-C5H5)2] (12). Freshly prepared com-
pound 1 (0.260 g, 0.348 mmol) was treated, in a manner
similar to that for the reaction of 1 with 3, with Na[Fe-
(CO)5CN] (0.089 g, 0.410 mmol) at -90 to -30 °C for 4 h,
during which time the turbid red solution gradually turned
clear brown-red. After removal of the solvent at -40 °C in
vacuo, the dark red residue was chromatographed on Al2O3
at -25 °C with petroleum ether/CH2Cl2 (15:1) as the eluant.
A purple-red band was eluted and collected. The solvent was
removed, and the residue was recrystallized from petroleum
ether/CH2Cl2 (15:1) solution at -80 °C to give 0.078 g (54%,
based on 1) of 129 as purple-red crystals: mp 78-79 °C dec;
IR (CH2Cl2) ν(CO) 1973 (vs), 1934 (m), 1773 (s) cm-1; 1H NMR
(CD3COCD3) δ 12.39 (s, 1 H, µ-CH), 7.56 (m, 2 H, C6H5), 7.36
(m, 1 H, C6H5), 7.21-7.06 (m, 2 H, C6H5), 4.95 (s, 10 H, C5H5);
MS m/e 388 (M+ - CO), 360 (M+ - 2CO), 332 (M+ - 3CO),
Resu lts a n d Discu ssion
In principle, the highly electrophilic cationic carbyne
complexes of diiron [Fe2(µ-CO)(µ-CAr)(CO)2(η5-C5H5)2]+
should be highly reactive toward nucleophiles, which
is indeed the case. The freshly prepared (in situ)
complex [Fe2(µ-CO)(µ-CPh)(CO)2(η5-C5H5)2] (1) was
treated with about 10-15% molar excess of the anionic
carbonylmetal compounds Na[M(CO)5CN] (3, M ) Cr;
4, M ) Mo; 5, M ) W) in THF at low temperature (-90
to -30 °C) for 4-5 h. After workup as described in the
Experimental Section, novel bridging carbyne complexes
[Fe2(µ-CO)(µ-CPh)(CO)2(η5-C5H5)2NCM(CO)5] (6-8) (eq
3) were obtained in 64-80% yields.
On the basis of elemental analyses and spectroscopic
evidence, as well as X-ray crystallography, products 6-8
are formulated as novel diiron bridging carbyne com-
plexes with an M(CO)5CN (M ) Cr, Mo, W) moiety
bonded to an Fe atom through the N atom of the CN
group.
Complexes 6-8 are readily soluble in polar organic
solvents but only slightly soluble in nonpolar solvents.
They are sensitive to air and temperature in solution
1
but relatively stable in the solid state. The IR and H
NMR spectra of complexes 6-8 are consistent with the
structures shown in eq 3. The IR spectra of complexes

A Route to Diiron Bridging Carbyne Complexes
Organometallics, Vol. 19, No. 19, 2000 3787
Ta ble 1. Cr ysta l Da ta a n d Exp er im en ta l Deta ils for Com p lexes 7, 8, a n d 11
7
8‚CH2Cl2
11‚H2O
formula
fw
C
25H15O7NFe2Mo
C26H17O7NCl2Fe2W
821.87
C27H19O9NFe2W
796.99
649.03
space group
a (Å)
b (Å)
P1h (No. 2)
11.754(2)
11.988(3)
9.399(2)
98.13(2)
107.39(2)
80.20(2)
1239.7(5)
2
1.739
644.00
16.96
MoKR (λ ) 0.71069 Å)
Rigaku AFC7R
20
P1h (No. 2)
11.045(3)
13.839(4)
10.351(4)
111.42(2)
104.13(1)
93.14(3)
1410.1(8)
2
1.936
792.00
53.21
MoKR (λ ) 0.71069 Å)
Rigaku AFC7R
20
C2/c (No. 15)
32.840(9)
10.907(2)
c (Å)
22.494(6)
R (deg)
â (deg)
γ (deg)
V (Å3)
125.82(2)
6532(2)
8
1.621
3088.00
Z
Dcalcd (g/cm3)
F(000)
µ(Mo KR) (cm-1
)
44.38
radiation (monochromated in incident beam)
diffractometer
temp (°C)
MoKR (λ ) 0.71069 Å)
Rigaku AFC7R
20
orientation rflns: no.; range (2θ) (deg)
16; 13.3-24.5
20; 14.0-21.6
15; 12.5-21.4
scan method
ω-2θ
ω-2θ
ω-2θ
data collecn range, 2θ (deg)
unique data: total, no. with I > 2.00σ(I)
no. of params refined
cor factors: max-min
Ra
5-50
3557, 2071
325
0.8673-1.0000
0.049
0.050
1.28
0.00
0.58
5-45
5-45
3281, 2276
361
0.8477-1.0000
0.056
0.071
2.26
0.02
1.64
3343, 2554 (I > 3.00σ(I))
337
0.6668-1.0934
0.056
0.067
2.44
0.00
2.13
-1.02
b
Rw
quality-of-fit indicatorc
max shift/esd final cycle
largest peak, (e/Å3)
min peak (e/Å3)
-0.47
-0.79
a
b
2
R ) ∑||Fo| - |Fc||/∑|Fo|. Rw ) [∑w(|Fo| - |Fc|)2/∑w|Fo| ]1/2; w ) 1/σ2(|Fo|). c Quality of fit ) [∑w(|Fo| - |Fc|)2/(Nobservns - Nparams)]1/2
.
Ta ble 2. Selected Bon d Len gth s (Å)a a n d An gles
(d eg)a for Com p lexes 7, 8, a n d 11
7 (M ) Mo)
8 (M ) W)
11 (M ) W)
Fe(1)-Fe(2)
Fe(1)-C(1)
Fe(2)-C(1)
Fe(1)-C(10)
Fe(2)-C(10)
C(1)-C(2)
2.501(2)
1.755(10)
1.854(9)
1.94(1)
1.95(1)
1.46(1)
2.495(3)
1.81(8)
1.84(2)
1.95(2)
1.99(2)
1.44(2)
1.95(1)
2.507(4)
1.98(2)
1.99(2)
1.89(2)
1.89(2)
1.53(2)
Fe(1)-N
1.941(9)
C(1)-N
1.47(2)
1.15(2)
2.13(2)
1.20(2)
2.12
N-C(23)
1.15(1)
2.18(1)
1.16(1)
2.12
1.11(2)
2.20(2)
1.17(2)
2.10
M-C(23)
C(10)-O(2)
Fe(1)-C(Cp) (av)
Fe(2)-C(Cp) (av)
2.10
2.09
2.12
Fe(1)-C(1)-Fe(2)
C(1)-Fe(1)-Fe(2)
C(1)-Fe(2)-Fe(1)
C(1)-Fe(1)-C(10)
C(1)-Fe(2)-C(10)
Fe(1)-C(10)-Fe(2)
C(10)-Fe(1)-Fe(2)
C(10)-Fe(2)-Fe(1)
Fe(1)-C(10)-O(2)
Fe(2)-C(10)-O(2)
Fe(1)-N-C(23)
Fe(1)-C(1)-N
87.7(4)
47.8(3)
44.5(3)
98.0(4)
94.2(4)
80.1(4)
50.2(3)
49.7(3)
140.7(9)
139.1(9)
175.3(9)
86.4(7)
47.3(5)
46.4(5)
97.2(8)
94.9(8)
78.6(10)
51.5(6)
49.9(6)
142(1)
139(1)
167(1)
78.3(7)
50.9(5)
50.8(6)
97.6(8)
97.7(8)
83.0(9)
48.4(7)
48.6(6)
138(1)
138(1)
6-8 in the ν(CO) region showed an absorption band at
1771-1795 cm-1 attributed to the bridging CO ligand,
in addition to four terminal CO absorption bands at
2056-1926 cm-1, which signified an Fe2(µ-CO)2(CO)6
and an M(CO)5 (M ) Cr, Mo, W) moiety in these
complexes. It is interesting to note that the 1H NMR
spectra of 6-8 showed a multiplet resonance attributed
to the cyclopentadienyl protons at about 5.90-4.90 ppm,
instead of the normal singlet signal. The explanation
for this might be that the C5v symmetry of the Cp ring
is destroyed when there exist different substituents on
the Cp rings or that the cyclopentadienyl-coordinated
metals are bonded to different ligands, which could lead
to partial localization of electrons on the Cp ring.12 In
6-8, the C5v symmetry of the Cp rings was destroyed
by bonding of the M(CO)5CN ligand to the Fe(1) atom.
This increased π-localization of electrons on the two Cp
114(1)
111(1)
178(1)
176(1)
Fe(2)-C(1)-N
C(1)-N-C(23)
M-C(23)-N
Fe(2)-Fe(1)-N
C(1)-Fe(1)-N
C(10)-Fe(1)-N
C(10)-Fe(1)-C(1)
C(10)-Fe(2)-C(1)
Fe(1)-C(1)-C(2)
Fe(2)-C(1)-C(2)
C(2)-C(1)-N
177.5(9)
95.3(2)
95.7(4)
92.9(4)
98.0(4)
94.2(4)
138.8(7)
133.4(7)
169(1)
99.6(4)
89.8(6)
89.9(6)
97.2(8)
94.9(8)
134(1)
138(1)
97.6(8)
97.7(8)
123(1)
124(1)
103(1)
a
Estimated standard deviations in the least significant figure
are given in parentheses.
(12) Fitzpatrick, P. J .; Le Page, Y.; Sedman, J .; Butler, L. S. Inorg.
Chem. 1981, 20, 2852.

3788 Organometallics, Vol. 19, No. 19, 2000
Liu et al.
the bridging carbene complexes [Fe2(µ-CO){µ-C(OEt)-
Ph}(CO)2(η5-C5H5)2] (2.512(1) Å)13 and [Fe2(µ-CO){µ-
C(OEt)C6H4Me-p}(CO)2(η5-C5H5)2] (2.519(2) Å)13 but
significantly shorter than that found in the cyclohep-
tatriene-coordinated bridging carbyne complex [Fe2{µ-
C(OEt)}{µ-η4:η3-C7H7C(OEt)(C6H4CF3-p)}(CO)4] (2.6706-
(7) Å).14 The alkylidyne carbon asymmetrically bridges
the Fe-Fe bond with C(1)-Fe(1) ) 1.755(10) Å and
C(1)-Fe(2) ) 1.854(9) Å in 7. This asymmetry is more
marked than that in 8 (C(1)-Fe(1) ) 1.81(8) Å, C(1)-
Fe(2) ) 1.84(2) Å) and in the analogous bridging carbyne
complex [Fe2{µ-C(OEt)}{µ-η4:η3-C7H7C(OEt)C6H4CF3-
p}(CO)4] (Fe(1)-C(10) ) 1.857(4) Å, Fe(2)-C(10) )
1.804(4) Å).14 The Fe(1)-µ-C(1) distances in 7 and 8 not
only are much shorter than the corresponding bonds in
[Fe2(µ-CO){µ-C(OEt)Ph}(CO)2-(η5-C5H5)2] (2.032(7) and
2.019(6) Å)13 and [Fe2(µ-CO){µ-C(SEt)Ph}(CO)2(η5-
C5H5)2] (2.03(1) and 2.00(1) Å)9 but also significantly
shorter than the FedCcarbene bond in carbene complexes
[Fe{C(OEt)C6H4Me-o}(C10H16)(CO)2] (1.915(15) Å)15 and
[Fe{C(OEt)C6H4Me-o}(C6H8)(CO)2] (1.89(2) Å).16 In the
di- and trimetal bridging carbyne complexes [MoFe(µ-
CC6H4Me-4)(CO)2(η5-C5H5)]17a and [CrReFe(µ-CC6H4-
Me-4)(CO)12],17b the Fe-µ-C distances, 2.008(5) and
1.872(8) Å, respectively, are longer than those in 7 and
8. These data strongly suggest that the Fe(1)-µ-C(1)
linkage in 7 and 8 is a double bond, thus giving the Fe-
(1) atom an 18-electron configuration.
F igu r e 1. Molecular structure of 7, showing the atom-
numbering scheme. Thermal ellipsoids are shown at 40%
probability.
The M(CO)5CN (M ) Mo, W) moiety in 7 and 8 is
bonded to the Fe(1) atom through the N atom. The Fe-
(1)-N bond lengths in 7 and 8 are 1.941(9) and 1.95(1)
Å, respectively, which are much shorter than that in
the complex [Fe{Me2NCH2C6H4C(OEt)CH2C6H4CH2}-
(CO)3] (2.158(3) Å)18 but are the same within experi-
mental error as in [Fe2(CO)6(NdCHCH3)2] (1.942(7)
Å),19 in which the closing of the Fe2N2 core with the
shorter Fe-N bond distance results in partial double-
bond character in the Fe-N bonds. The shorter Fe(1)-N
distance suggests that there exists some double-bond
character in the Fe(1)-N bond in both complexes.
C(23)-N has a bond length of 1.15(1) Å for 7 and 1.11-
(2) Å for 8, which indicates high triple-bond character,
and is essentially the same as that found (1.15(1) Å) in
[(η5-C5H5)(CO)2RedC(Ph)NCW(CO)5] (1.16(1) Å)8f and
is comparable with that of the corresponding C-N bond
in [Fe2(µ-CNEt)3(CNEt)6] (1.13-1.19 Å).20 The shorter
M-C(23) distance (Mo-C(23) ) 2.18(1) Å for 7, W-C(23)
) 2.20(2) Å for 8) indicates a high double-bond character
of the M-C(23) bond in both complexes. This distance
is nearly the same as that in [(η5-C5H5)(CO)2RedC(Ph)-
NCW(CO)5] (W-C(8) ) 2.13(1) Å)8f and is comparable
F igu r e 2. Molecular structure of 8, showing the atom-
numbering scheme. Thermal ellipsoids are shown at 40%
probability. CH2Cl2 has been omitted for clarity.
rings coordinated respectively to the Fe(1) and Fe(2)
atoms. This would change the chemical environment of
the cyclopentadienyl protons, resulting in the splitting
of the singlet signal into a multiplet of cyclopentadienyl
protons.
The structures of complexes 7 and 8 have been further
confirmed by X-ray diffraction studies. The results of
the X-ray diffraction work for both complexes are
summarized in Table 1, and the structures are shown
in Figures 1 and 2, respectively. Both structures are
nearly identical, as illustrated by the following param-
eters. The distances of the Fe-Fe bond bridged by the
µ-CPh ligand in 7 and 8 are 2.501(2) and 2.495(3) Å,
respectively, which are slightly shorter than those in
(13) Chen, J .-B.; Li, D.-S.; Yu, Y.; Chen, C.-G. Organometallics 1994,
13, 3581.
(14) Yu, Y.; Chen, J .-B.; Chen, J .; Zheng, P.-J . Organometallics 1993,
12, 4731.
(15) Chen, J .-B.; Lei, G.-X.; J in, Z.-S.; Hu, L.-H.; Wei, G.-C. Orga-
nometallics 1988, 7, 1652.
(16) Chen, J .-B.; Yu, Y.; Hu, L.-H.; J in, Z.-S. J . Organomet. Chem.
1993, 447, 113.
(17) (a) Carcia, M. E.; J effery, J . C.; Sherwood, P.; Stone, F. G. A.
J . Chem. Soc., Dalton Trans. 1987, 1209. (b) Evans, D. G.; Howard, J .
A. K.; J effery, J . C.; Lewis, G. E.; Grosse-Ophoff, M. J .; Parrott, M. J .;
Stone, F. G. A. J . Chem. Soc., Dalton Trans. 1986, 1723.
(18) Yu, Y.; Chen, J .-B.; Chen, J .; Zheng, P.-J . J . Chem. Soc., Chem.
Commun. 1995, 2089.
(19) Gervasio, G.; Stanghellini, P. L.; Rossetti, R. Acta Crystallogr.
1981, B37, 1198.
(20) Goldfield, S. A.; Raymond, K. N. Inorg. Chem. 1974, 13, 770.

A Route to Diiron Bridging Carbyne Complexes
Organometallics, Vol. 19, No. 19, 2000 3789
with the W-Ccarbene bond distance in the analogous
carbene
complex
[(CO)5WdC(OEt)C5H4RuC5H5]
(2.23(2) Å)21 but is markedly longer than the W-Ccarbyne
bond distance in the carbyne complex [CrPPh2(2,2′-
bipy)WCNEt2(CO)7] (1.877(8) Å).22 The Fe(1), N, C(23),
and Mo or W atoms are coplanar with an Fe(1)-N-
C(23) angle of 175.3(9)° and a N-C(23)-Mo angle of
177.5(9)° for 7 and an Fe(1)-N-C(23) angle of 167(1)°
and a N-C(23)-W angle of 169(1)° for 8, which shows
that the Fe(1)-N-C(23)-M fragment is approximately
linear; thus, the Fe(1), N, C(23), and Mo or W atoms
form a conjugate chain. Moreover, C(1)-C(2) bond
lengths in 7 and 8 are 1.46(1) and 1.44(2) Å, respec-
tively, which are intermediate between C-C single-bond
and CdC double-bond distances. The shorter C(1)-C(2)
distance suggests some π-bond character between the
C(1) atom and C(2) atom of the benzene ring in
complexes 7 and 8.
The formation of complexes 6-8 could involve initial
formation of the cationic bridging carbyne intermediate
[Fe2(µ-CO)(µ-CPh)(CO)(η5-C5H5)2]+ by loss of a CO
ligand from an Fe atom (e.g. Fe(1)) accompanied by
formation of a M(CO)6 (M ) Cr, Mo, W) compound in
the presence of the carbonylmetal anion. Then the
(CO)5MdCdN- (M ) Cr, Mo, W) anion (a representa-
tion of the same electronic structure of the -M(CO)5CN
anion) attacks the unsaturated Fe(1) center of the
carbyne intermediate to produce products 6-8. Indeed,
we have isolated small amounts of compound M(CO)6
in the course of the column chromatography.
Although a number of dimetal bridging carbyne
complexes have been prepared by Stone et al. and by
us as mentioned in the Introduction, complexes 6-8 as
dimetal bridging carbyne complexes were synthesized
first by the reaction of a cationic carbyne complex of
diiron with carbonylmetal anions.
In contrast to the reaction of complex 1, the cationic
carbyne complex [Fe2(µ-CO)(µ-CC6H4Me-p)(CO)2(η5-
C5H5)2]BBr4 (2) reacts with carbonylmetal anions 3-5
under the same conditions to give not analogous bridg-
ing carbyne complexes but rather the novel bridging
p-tolyl(pentacarbonylcyanotungsten)carbene complexes
[F e2 (µ-CO){µ-C(C6 H 4 Me-p )N CM(CO)5 }(CO)2 (η5 -
C5H5)2] (9-11) (eq 4) in 57-76% isolated yields.
F igu r e 3. Molecular structure of 11, showing the atom-
numbering scheme. Thermal ellipsoids are shown at 40%
probability. H2O has been omitted for clarity.
data, and the X-ray diffraction study of 11. The IR and
1H NMR spectra of complexes 9-11 are different from
those of 6-8 (see the Experimental Section). The IR
spectra of 9-11 in the ν(CO) region showed four to six
CO absorption bands at 2057-1772 cm-1, similar to
6-8, whereas the characteristic ν(CN) stretching vibra-
tion occurs at ca. 2059-2051 cm-1 for complexes 6-8
but at ca. 2127-2125 cm-1 for complexes 9-11, shifting
to high vibration frequency by about 70 cm-1. This may
be due to the coordination of the M(CO)5CN (M ) Cr,
Mo, W) moiety to the Fe(1) atom through a CN group
leading to a weakening of the C-N bond to a greater
extent in complexes 6-8, as compared to that of
complexes 9-11, in which the M(CO)5CN moiety is
bonded to the µ-carbene carbon through the CN group.
1
The H NMR spectra of 6-8 showed five to seven sets
of proton signals attributed to the cyclopentadienyl
protons at 5.90-4.90 ppm, while complexes 9-11
showed only a singlet cyclopentadienyl proton signal at
ca. 5.81 ppm, since the W(CO)5CN moiety is bonded to
the Fe(1) atom in 6-8 but to the µ-carbene carbon in
the latter. In complexes 9-11, the C5v symmetry of the
Cp rings has not been destroyed. This suggests that the
structures of complexes 9-11 are quite different from
those of complexes 6-8, a fact that is further confirmed
by an X-ray diffraction study of 11.
The structure of 11 (Figure 3) resembles that of the
bridging complexes [Fe2(µ-CO){µ-C(OEt)Ph}(CO)2(η5-
C5H5)2]13 and [Fe2(µ-CO){µ-C(SEt)Ph}(CO)2(η5-C5H5)2],9
except that the substituent on the µ-carbene carbon is
the W(CO)5CN group in 11 but an OEt or SEt group in
The composition and structure of complexes 9-11 are
supported by their elemental analyses, spectroscopic
(21) Fischer, E. O.; Gammel, F. J .; Besenhard, J . O.; Frank, A.;
Neugebauer, D. J . Organomet. Chem. 1980, 191, 261.
(22) Filippou, A. C.; Fischer, E. O. J . Organomet. Chem. 1987, 326,
59.

3790 Organometallics, Vol. 19, No. 19, 2000
Liu et al.
the latter. The structure of the principal portion of [Fe2-
(µ-CO)(µ-CAr)(CO)2(η5-C5H5)2] in 11 is very similar to
that in 7 and 8. An apparent difference in the structures
of 7 (or 8) and 11 is the longer Fe-µ-C(1) bonds (Fe-
(1)-C(1) ) 1.98(2) Å, Fe(2)-C(1) ) 1.99(2) Å) and the
longer C(1)-C(2) bond (1.53(2) Å) in 11, as compared
to 7 and 8. The two C-N bond lengths in 11 are very
different. C(23)-N has a bond length of 1.15(2) Å, which
indicates high triple-bond character and is essentially
the same as that found in 7 (1.15(1) Å) and 8 (1.11(2)
Å). The other is C(1)-N with a bond length of 1.47(2)
Å, which is between the normal C-N and CdN dis-
tances and is slightly shorter than the corresponding
C-N distance in [W-N(ButCMe2(Me)(NBut){N(But)-
CMedCMe2}] (1.438-1.521 Å).23 The shorter W-C(23)
distance (2.13(2) Å) in 11 signifies its high double-bond
character, as in 7 and 8. The C(1), N, C(23), and W
atoms are coplanar with a C(1)-N-C(23) angle of 178-
(1)° and a N-C(23)-W angle of 176(1)°, indicating that
the C(1)-N-C(23)-W fragment is almost linear; thus,
the C(1), N, C(23), and W atoms form a conjugate chain.
The reaction pathway to complexes 9-11 could pro-
ceed via attack of the (CO)5MdCdN- (M ) Cr, Mo, W)
anion (a representation of the same electronic structure
of the -M(CO)5CN anion) at the µ-carbyne carbon of 2.
In the reaction of 2, no analogous cationic bridging
carbyne intermediate [Fe2(µ-CO)(µ-CC6H4Me-p)(CO)(η5-
C5H5)2]+ would be formed as in the case of complex 1,
owing to the electron-pushing action of the p-tolyl group,
which provides the partial charge for the µ-carbyne
carbon to stabilize cationic 2. Thus, the (CO)5MdCdN-
anion directly attacks the µ-carbyne carbon to produce
complexes 9-11.
the carbonylmetal anionic compound is important; the
Cr, Mo, and W atoms probably promote the reaction by
forming a stable (CO)5MdCdNFe (M ) Cr, Mo, W) core.
Complex 12 is a known compound9 whose structure
has been established by X-ray crystallography; it has
been obtained by the reaction of 1 with the reactive salt
[Et3NH][Fe2(µ-CO)(µ-SPh)(CO)6] or the carbonylmetal
dianions Na2[W(CO)5] and Na2[Fe(CO)4]. The formation
of product 12 is unexpected, and we do not know the
chemistry involved.
The title reaction shows the novel reactions between
carbonylmetal anions and the cationic bridging carbyne
complexes of diiron. The reaction results indicate that
the different cationic bridging carbyne complexes exert
great influence on the resulting products, and the
different carbonylmetal anions exhibit great influence
on the reactivity of cationic bridging carbyne complexes
and the reaction products. The title reaction represents
a new, convenient, and useful method for the prepara-
tion and structural modification of dimetal bridging
carbene and bridging carbyne complexes.
Not all such carbonylmetal anions containing a CN
group can react with cationic carbyne complex 1 or 2 to
afford the bridging carbyne or bridging carbene com-
plexes, since the analogous anionic carbonylmetal com-
pound Na[Fe(CO)4CN] reacted with 1 under the same
conditions to give a 54% yield of diiron bridging phe-
nylcarbene complex [Fe2(µ-CO){µ-C(H)Ph}(CO)2(η5-
C5H5)2] (12) (eq 5), instead of the expected bridging
carbyne complex. This suggests that the metal atom in
Ack n ow led gm en t . Financial support from the
National Natural Science Foundation of China and
the Science Foundation of the Chinese Academy of
Sciences is gratefully acknowledged.
Su p p or tin g In for m a tion Ava ila ble: Tables of the posi-
tional parameters and Biso/Beq values, H atom coordinates,
anisotropic displacement parameters, all bond lengths and
angles, and least-squares planes for 7, 8, and 11. This material
is available free of charge via the Internet at http://pubs.acs.org.
(23) Chiu, K. W.; J ones, R. A.; Wilkinson, G. J . Chem. Soc., Dalton
Trans. 1981, 2088.
OM0002529