Syntheses, structures and reactivities of diindenyl-coordinated diiron bridging carbene complexes

Article abstract of DOI:10.1016/j.jorganchem.2006.07.012

Compound [Fe₂(μ-CO)₂(CO)₂(η⁵-C₉H₇)₂] (1) reacts with aryllithium reagents, ArLi (Ar = C₆H₅, p-CH₃C₆H₄, p-CF₃C

Full text of DOI:10.1016/j.jorganchem.2006.07.012

Journal of Organometallic Chemistry 691 (2006) 4641–4651
www.elsevier.com/locate/jorganchem
Syntheses, structures and reactivities of diindenyl-coordinated
diiron bridging carbene complexes
a
a
a
b,
c,
a,
*
Lei Zhang , Jie Sun , Huping Zhu , Qiang Xu *, Nobuko Tsumori *, Jiabi Chen
a
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Lu, Shanghai 200032, China
b
National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
c
Toyama National College of Technology, 13 Hongo-machi, Toyama-shi 939-8630, Japan
Received 9 May 2006; received in revised form 26 June 2006; accepted 6 July 2006
Available online 25 July 2006
Abstract
Compound [Fe2(l-CO)2(CO)2(g5-C9H7)2] (1) reacts with aryllithium reagents, ArLi (Ar = C6H5, p-CH3C6H4, p-CF3C6H4) followed
by alkylation with Et3OBF4 to give the diindenyl-coordinated diiron bridging alkoxycarbene complexes [Fe2{l-C(OC2H5)Ar}(l-
CO)(CO)2(g5-C9H7)2] (2, Ar = C6H5; 3, Ar = p-CH3C6H4, 4, Ar = p-CF3C6H4). Complex 4 reacts with HBF4 Æ Et2O at low temperature
to yield cationic bridging carbyne complex [Fe2(l-CC6H4CF3-p)(l-CO)(CO)2(g5-C9H7)2]BF4 (5). Cationic 5 reacts with NaBH4 in THF
at low temperature to afford diiron bridging arylcarbene complex [Fe2{l-C(H)C6H4CF3-p}(l-CO)(CO)2(g5-C9H7)2] (6). The reaction of
5 with NaSC6H4CH3-p under the similar conditions gave the bridging arylthiocarbene complex [Fe2{l-C(C6H4CF3-p)SC6H4CH3-p}(l-
CO)(CO)2(g5-C9H7)2] (7). Complex 5 can also react with carbonylmetal anionic compounds Na[M(CO)5(CN)] (M = Cr, Mo, W) to pro-
duce the diiron bridging aryl(penta-carbonylcyanometal)carbene complexes [Fe2{l-C(C6H4CF3-p)NCM(CO)5}(l-CO)(CO)2(g5-C9H7)2]
(8, M = Cr; 9, M = Mo; 10, M = W). The structures of complexes 4, 6, 7, and 10 have been established by X-ray diffraction studies.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Diindenyl; Bridging carbene complexes; Syntheses; Structures; Reactivities
1. Introduction
bridging carbene and bridging carbyne complexes is to con-
duct the reactions of the highly electrophilic cationic carbyne
complexes of manganese and rhenium, [g5-C5H5-
(CO)2M„CPh]BBr4 (M = Mn, Re), with carbonylmetal
anions [5]. In light of the common method to synthesize
the mononuclear metal Fischer-type carbene complexes,
we have previously developed a facile way to prepare diiron
bridging alkoxocarbene complexes: carbonyl-bridged diiron
complexes, such as [Fe2(l-CO)(CO)4(g8-C8H8)], [Fe2(l-
CO)2(CO)2(g5-C5H5)2] and [Fe2(l-CO)2(CO)2{SiMe2(g5-
C5H5)2}], reacted with aryllithium reagents followed by
alkylation with alkylating agent Et3OBF4 in aqueous solu-
tion at 0 ꢁC to give diiron bridging alkoxycarbene complexes
[Fe2{l-C(OEt)Ar}(CO)4(C8H8)] [6], [Fe2(l-CO){l-C(OEt)-
Ar}(CO)2(g5-C5H5)2] [7], and [Fe2(l-CO){l-C(OC2H5)-
Ar}(CO)2{(g5-C5H4)2Si(CH3)2}] [8], respectively. Recently,
we have shown a new and convenient method for the
preparation of dimetal bridging carbene and/or carbyne
The chemistry of di- and polynuclear metal bridging car-
bene and bridging carbyne complexes has been receiving
considerable current attention in our laboratory, largely
because of the interesting chemical properties exhibited by
such complexes. A number of dimetal complexes containing
bridging carbene and carbyne ligands have been synthesized
by Stone and co-workers [1–4] by reactions of carbene or
carbyne complexes with low-valent metal species or by reac-
tions of neutral or anionic carbyne complexes with metal
hydrides or cationic metal compounds. In our laboratory,
one method for preparation of the di- and polymetallic
*
Corresponding authors. Fax: +86 21 64166128 (J. Chen); fax: +81 72
751 9629 (Q. Xu).
E-mail addresses: q.xu@aist.go.jp (Q. Xu), chenjb@mail.sioc.ac.cn (J.
Chen).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.07.012

4642
L. Zhang et al. / Journal of Organometallic Chemistry 691 (2006) 4641–4651
complexes that is the reactions of diiron cationic bridging
carbyne complexes, [Fe2(l-CO)(l-CAr)-(CO)2(g5-C5H5)2]-
BBr4 [9], [Fe2(l-CO)(l-CAr)(CO)2{(g5-C5H4)2Si(CH3)2}]-
BBr4 [10], and [Fe2(l-CAr)(CO)4(g8-C8H8)][BF4] [11]
obtained by treating above corresponding bridging alkoxy-
carbene complexes with Lewis acid BBr3 or HBF4, with
nucleophiles. This offers a useful method for the preparation
and structural modification of dimetal bridging carbene
complexes.
ketyl, while petroleum ether (30–60 ꢁC) and CH2Cl2 were
distilled from CaH2. The neutral alumina (Al2O3, 100–200
mesh) used for chromatography was deoxygenated at room
temperature under high vacuum for 16 h, deactivated with
5% w/w N2-saturated water, and stored under N2
atmosphere. Compounds HBF4 Æ Et2O and NaBH4, and
n-C4H9Li were purchased from Aldrich Chemical Co. Com-
pound [Fe2(l-CO)2(CO)2(g5-C9H7)2] (1) [13], NaSC6H4-
CH3-p [14], Na[Cr(CO)5(CN)] [15], Na[Mo(CO)5(CN)]
[15], and Na[W(CO)5(CN)] [15], aryllithium reagents [16–
18], and Et3OBF4 [19] were prepared by the literature
methods.
The IR spectra were measured on a Nicolet AV-360
spectrophotometer using NaCl cells with 0.1 mm spacers.
All 1H NMR and 13C NMR spectra were recorded at ambi-
ent temperature in acetone-d6 solution with TMS or deu-
terated solvents as the internal reference using a Varian
Mercury 300 spectrometer. The 13C NMR data for com-
plexes 5 and 7–10 were not obtained due to their lability
in the solution. Electron ionization mass spectra (EIMS)
were run on a Hewlett–Packard 5989A spectrometer. Melt-
ing points obtained on samples in sealed nitrogen-filled
capillaries are uncorrected.
On the other hand, it was found that the different olefin
ligand involving the different cyclopentadienyl ligand in the
dimetal cationic bridging carbyne complexes exhibit a great
influence on the reactivity of the cationic bridging carbyne
complexes toward nucleophiles and the resulting
products. For instance, dicyclopentadienyl-coordinated
diiron cationic carbyne complexes [Fe2(l-CO)(l-CC6H5)-
(CO)2(g5-C5H5)2]BBr4 reacts with NaN(SiMe3)2 and
Na[M(CO)5CN] (M = Cr, Mo, W) to give bridging carbene
complex
[Fe2(l-CO){(l-C(N(SiMe3)2)C6H5)(CO)2(g5-
C5H5)2}] [12] and bridging carbyne complexes [Fe2(l-CO)-
(l-CC6H5)(CO)2(g5-C5H5)2NCM(CO)5] [9], respectively,
while the analogous reactions of dimethylsilane-bridged
biscyclo-pentadienyl diiron cationic carbyne complexes
[Fe2(l-CO)(l-CAr)(CO)2{(g5-C5H4)2-Si(CH3)2}]BBr4 give
benzonitrile-coordinated diiron complex [Fe2(l-CO)2(CO)-
NC-C6H5{(g5-C5H4)2Si(CH3)2}] and bridging phenyl
(pentacarbonylcyanometal)carbene complexes [Fe2(l-CO)-
{l-C(C6H5)NCM(CO)5}(CO)2{(g5-C5H4)2Si(CH3)2}] [10],
respectively.
2.1. Reaction of [Fe2(l-CO)2(CO)2(g5-C9H7)2] (1)
with C6H5Li to give [Fe2{l-C(OC2H5)C6H5}(l-CO)-
(CO)2(g5-C9H7)2] (2)
To a suspension of 0.250 g (0.55 mmol) of 1 in 50 mL of
ether at ꢀ40 ꢁC was added 0.66 mmol of the freshly pre-
pared C6H5Li [16] ether solution with stirring. The reaction
mixture was stirred at ꢀ40 to ꢀ20 ꢁC for 3 h, during which
time the green suspension gradually turned blackish solu-
tion. The resulting solution then evaporated under high vac-
uum at ꢀ20 ꢁC to dryness. To the blackish solid residue
obtained was added Et3OBF4 [19] (ca. 5 g). This solid mix-
ture was dissolved in 50 mL of N2-saturated water at 0 ꢁC
with vigorous stirring and the mixture covered with petro-
leum ether (30–60 ꢁC). Immediately afterwards, Et3OBF4
(ca. 15 g) was added portion wise to the aqueous solution,
with strong stirring, until it became acidic. The aqueous
solution was extracted with petroleum ether/CH2Cl2 (5:1).
After removal of the solvent under vacuum, the dark brown
residue was chromatographed on an alumina (neutral) col-
umn (1.6 · 15–20 cm) at ꢀ25 ꢁC with petroleum ether/
CH2Cl2 (3:1) as the eluant. The solvent was removed in
vacuo and the residue was recrystallized from petroleum
ether/CH2Cl2 (10:1) at ꢀ80 ꢁC to give 0.236 g (76%, based
on 1) of blackish crystals of 2; m.p. 94–96 ꢁC (dec.); IR
In order to further explore the reactivity of substituted
cyclopentadienyl-coordinated diiron cationic bridging car-
byne complexes toward nucleophiles and to further examine
the scope of the preparation of dimetal bridging carbene and
bridging carbyne complexes, we synthesized diindenyl-
coordinated diiron bridging alkoxycarbene complexes
[Fe2{l-C(OC2H5)Ar}(l-CO)(CO)2(g5-C9H7)2] (Ar = C6H5,
p-CH3C6H4, p-CF3C6H4) by the reactions of diindenyl-coor-
dinated diiron carbonyl compound, [Fe2(l-CO)2(CO)2(g5-
C9H7)2] (1), where the indenyl can be formally regarded as
a cyclodiene-substituted cyclopentadienyl, with aryllithium
reagents followed by alkylation with Et3OBF4, and carried
out the study of the reactivity of the cationic bridging
carbyne complex [Fe2(l-CC6H4CF3-p)(l-CO)(CO)2(g5-
C9H7)2]BF4 with nucleophiles involving carbonylmetal
anions. These reactions produce a series of novel diinde-
nyl-coordinated dimetal bridging carbene complexes. In this
paper, we report these unusual reactions and the structural
characterization of the resulting products.
1
2. Experimental
(CH2Cl2): m(CO) 1970 (vs), 1932 (m), 1783 (m) cmꢀ1; H
NMR (CD3COCD3): d 7.69–7.45 (m, 5H, C6H5), 7.43–
7.26 (m, 8H, 2C9H7), 6.18–6.17 (dd, 2H, 2C9H7), 5.63 (m,
1H, CH2Cl2), 5.27 (t, 2H, 2C9H7), 4.90 (m, 2H,
2C9H7).3.61 (q, 2H, OCH2CH3), 1.41 (t, 3H, OCH2CH3);
13C NMR (CD3COCD3): d 267.2 (l-C), 244.5, 213.2 (CO),
158.5, 130.5, 128.7, 127.0, 126.4, 114.0 (C6H5), 101.6, 99.8,
79.8, 79.4, 67.0 (OCH2CH3), 15.1 (OCH2CH3); MS m/e
All procedures were performed under a dry, oxygen-free
N2 atmosphere by using standard Schlenk techniques. All
solvents employed were reagent grade and dried by refluxing
over appropriate drying agents and stored over 4 A molecu-
lar sieves under N2 atmosphere. Tetrahydrofuran and
diethyl ether were distilled from sodium benzophenone
˚

L. Zhang et al. / Journal of Organometallic Chemistry 691 (2006) 4641–4651
4643
447 (M+ꢀ3COꢀC2H5), 342 [M+ꢀ3COꢀC(C2H5)C6H5],
115 ðC9HþÞ, 84 ðCH2ClþÞ. Anal. Calc. for C30H24O4Fe2 Æ
0.100 mL (0.67 mmol) of HBF4 Æ Et2O. Immediately, a
blackish red precipitate was formed. After stirring at ꢀ60
to ꢀ30 ꢁC for 1 h, the resulting mixture was filtered, and
the solid was washed with ether (2 · 20 mL) at ꢀ60 ꢁC
and then dried under high vacuum at ꢀ30 ꢁC to give
0.226 g (85%, based on 4) of 5 as a blackish red solid: IR
7
2
0.5CH2Cl2: C, 60.80; H, 4.18. Found: C, 60.95; H, 4.15%.
2.2. Reaction of 1 with p-CH3C6H4Li to give [Fe2{l-
C(OC2H5)C6H4CH3-p}-(l-CO)(CO)2(g5-C9H7)2] (3)
(CH2Cl2): m(CO) 1992 (vs), 1950 (s), 1782 (s) cmꢀ1 1H
;
Similar to the procedures described above for the reaction
of 1 with C6H5Li, compound 1 (0.200 g, 0.44 mmol) was
reacted with 0.66 mmol of p-CH3C6H4Li [17] at ꢀ40 to
ꢀ20 ꢁC for 3 h. The subsequent alkylation and further treat-
ment in a similar manner as described for the preparation of
2 afforded 0.176 g (70%, based on 1) of 3 as blackish crystals;
m.p. 108–110 ꢁC (dec.); IR (CH2Cl2): m(CO) 1970 (vs), 1952
(w), 1782 (s) cmꢀ1; 1H NMR (CD3COCD3): d 7.51–7.38 (m,
4H, p-CH3C6H4), 7.46–7.23 (m, 8H, 2C9H7), 6.15 (dd, 2H,
2C9H7), 5.62 (m, 2H, CH2Cl2), 5.25 (t, 2H, 2C9H7), 4.89 (s,
2H, 2C9H7), 3.60 (q, 2H, OCH2CH3), 2.23 (s, 3H, p-
CH3C6H4), 1.40 (t, 3H, OCH2CH3); 13C NMR
(CD3COCD3): d 257.0 (l-C), 239.8, 218.7 (CO), 161.1,
131.2, 130.0, 128.2, 126.6, 126.5, 125.7, 122.3, 99.56, 79.4,
66.0 (OCH2CH3), 18.4 (OCH2CH3), MS m/e 454
[M+ꢀC2H5ꢀC6H4CH3-p], 370 [M+ꢀ2COꢀC(OC2H5)-
C6H4CH3-p], 342 [M+ꢀ3COꢀC(OC2H5)C6H4CH3-p], 286
NMR (CD3COCD3): d 8.49–8.01 (m, 4H, p-CF3C6H4),
7.87–7.75 (m, 8H, 2C9H7), 7.40 (m, 2H, 2C9H7), 5.81 (s,
2H, 2C9H7), 5.48 (m, 2H, 2C9H7).
2.5. Reaction of 5 with NaBH4 to give [Fe2{l-
C(H)C6H4CF3-p}(l-CO)(CO)2-(g5-C9H7)2] (6)
To a solution of 5, freshly prepared (in situ) by the reac-
tion of 4 (0.200 g, 0.32 mmol) with HBF4 Æ Et2O (0.080
mL, 0.53 mmol), in 50 mL of THF at ꢀ80 ꢁC was added
0.020 g (0.53 mmol) of NaBH4. The reaction mixture was
stirred at ꢀ80 to ꢀ40 ꢁC for 3 h, during which time the black-
ish solution gradually turned brown-red. The resulting solu-
tion was evaporated under high vacuum at ꢀ40 ꢁC to
dryness and the brown-red residue was chromatographed
on an Al2O3 column at ꢀ20 ꢁC with petroleum ether/CH2Cl2
(2:1) as the eluant. A brown-red band was eluted and col-
lected. After vacuum removal of the solvent, the residue
was recrystallized from petroleum ether/CH2Cl2 solution
at ꢀ80 ꢁC to give 0.148 g (80%, based on 4) of red crystals
of 6: m.p. 140–142 ꢁC (dec.); IR (CH2Cl2): m(CO) 1991 (vs),
[M+ꢀ3COꢀC(OC2H5)C6H4CF3-pꢀFe], 115 ðC9HþÞ, 84
7
ðCH2ClþÞ. Anal. Calc. for C31H26O4Fe2 Æ CH2Cl2: C,
2
58.31; H, 4.28. Found: C, 59.09; H, 4.00%.
2.3. Reaction of 1 with p-CF3C6H4Li to give [Fe2{l-
C(OC2H5)C6H4CF3-p}(l-CO)(CO)2(g5-C9H7)2] (4)
1
1951 (m), 1782 (s) cmꢀ1; H NMR (CD3COCD3): d 10.36
(s, 1H, l-CH), 7.44–7.29 (m, 4H, C6H4CF3), 7.24–7.19 (m,
8H, 2C9H7), 7.03 (dd, 2H, 2C9H7), 5.64 (s, 2H, 2C9H7),
5.35 (s, 2H, 2C9H7); 13C NMR (CD3COCD3): d 256.7 (l-
C), 226.0, 215.6 (CO), 187.7, 128.7, 128.5, 128.2, 125.0,
123.9 (C6H5), 106.8, 95.1, 81.8, 79.7; MS m/e 444
(M+ꢀ3COꢀFe), 354 (M+ꢀ3COꢀHꢀp-CF3C6H4), 342
A solution of 0.124 g (0.55 mmol) of p-CF3C6H4Br in
20 mL of ether was mixed with 0.55 mmol of n-C4H9Li.
After 40 min stirring at room temperature, the resulting
ether solution of p-CF3C6H4Li [18] was reacted, as
described in the reaction of 1 with C6H5Li, with 0.200 g
(0.44 mmol) of 1 at ꢀ40 to ꢀ20 ꢁC for 3 h, followed by
alkylation; further treatment as described that in the prepa-
ration gave 0.226 g (81%, based on 1) of blackish crystals of
4, m.p. 116–118 ꢁC (dec.). IR (CH2Cl2): m(CO) 1973 (vs),
1935 (w), 1784 (m) cmꢀ1; 1H NMR (CD3COCD3): d 7.65–
7.42 (m, 4H, p-CF3C6H4), 7.32–7.26 (m, 8H, 2C9H7),
6.19–6.18 (dd, 2H, 2C9H7), 5.30 (t, 2H, 2C9H7), 4.98 (m,
2H, 2C9H7), 3.62 (q, 2H, OCH2CH3), 1.43 (t, 3H,
OCH2CH3); 13C NMR (CD3COCD3): d 266.0 (l-C),
241.0, 213.4 (CO), 161.8, 131.2, 129.2, 127.5, 126.4, 123.6,
123.0, 114.2, 102.2, 100.0, 80.2, 79.8, 67.8 (OCH2CH3),
15.4 (OCH2CH3); MS m/e 342 [M+ꢀ3COꢀC(OC2H5)-
C6H4CF3-p], 286 [M+ꢀ3COꢀC(OC2H5)C6H4CF3-pꢀFe],
115 ðC9Hþ7 Þ. Anal. Calc. for C31H23O4F3Fe2: C, 59.27; H,
3.69. Found: C, 59.48; H, 3.70%.
[M+ꢀ3COꢀC(H)C6H4CF3-p], 115 ðC9HþÞ. Anal. Calc. for
7
C29H19O3F3Fe2: C, 59.63; H, 3.28. Found: C, 58.09; H,
3.42%.
2.6. Reaction of 5 with NaSC6H4CH3-p to give [Fe2{l-
C(C6H4CF3-p)SC6H4CH3-p}(l-CO)(CO)2-
(g5-C9H7)2] (7)
To a solution of 5, freshly prepared (in situ) from the reac-
tion of 4 (0.120 g, 0.19 mmol) with HBF4 Æ Et2O (0.050 mL,
0.33 mmol), dissolved in 50 mL ofTHF at ꢀ80 ꢁC was added
0.030 g (0.21 mmol) of NaSC6H4CH3-p. The reaction mix-
ture was stirred at ꢀ80 to ꢀ40 ꢁC for 3 h, during this time
the reaction solution turned from blackish to dark red grad-
ually. The solvent was removed under vacuum at ꢀ40 ꢁC,
and the dark red residue was chromatographed on an
Al2O3 column at ꢀ25 ꢁC with petroleum ether/CH2Cl2
(2:1) as the eluant. A brown-red band was eluted and col-
lected. After vacuum removal of the solvent, the residue
was recrystallized from petroleum ether/CH2Cl2 solution
at ꢀ80 ꢁC to afford 0.080 g (59%, based on 4) of brown-red
crystalline 7: m.p. 120–122 ꢁC (dec.); IR (CH2Cl2): m(CO)
2.4. Reaction of [Fe2{l-C(OC2H5)C6H4CF3-p}
(l-CO)(CO)2(g5-C9H7)2] (4) with HBF4 Æ Et2O to give
[Fe2(l-CC6H4CF3-p)(l-CO)(CO)2(g5-C9H7)2]BF4 (5)
To a stirred, blackish red solution of 4 (0.250 g,
0.40 mmol) in 40 mL of ether at ꢀ60 ꢁC was added

4644
L. Zhang et al. / Journal of Organometallic Chemistry 691 (2006) 4641–4651
1980 (vs), 1943 (m), 1793 (s, br) cmꢀ1
;
1H NMR
CNꢀC9H7], 239 [M+ꢀ3COꢀC9H7ꢀMo(CO)5CNꢀCF3C6H4],
227 [M+ꢀ3COꢀC9H7ꢀC(CF3C6H4)NCMo(CO)5], 115
ðC9HþÞ, 84 ðCH2ClþÞ. Anal. Calc. for C35H18O8F3NFe2-
(CD3COCD3): d 7.63–7.33 (m, 8H, p-CF3C6H4 + p-
CH3C6H4), 7.13–6.93 (m, 8H, 2C9H7), 6.49 (s, 2H, 2C9H7),
5.62 (m, 2H, CH2Cl2), 5.46 (s, 2H, 2C9H7), 5.30 (s, 2H,
2C9H7), 2.23 (s, 3H, p-CH3C6H4); MS m/e 566 (M+ꢀ
3COꢀFe), 342 [M+ꢀ3COꢀC(C6H4CH3-p)C6H4CF3-p],
115 ðC9HþÞ, 84 ðCH2ClþÞ. Anal. Calc. for C36H25O3F3S-
7
2
Mo Æ CH2Cl2: C, 46.48; H, 2.16; N, 1.51. Found: C,
46.22; H, 2.28, N, 1.49%.
2.9. Reaction of 5 with Na[W(CO)5(CN)] to give [Fe2-
{l-C(C6H4CF3-p)NCW-(CO)5}(l-CO)(CO)2(g5-
C9H7)2] (10)
7
2
Fe2 Æ CH2Cl2: C, 56.16; H, 3.44. Found: C, 56.92; H, 3.49%.
2.7. Reaction of 5 with Na[Cr(CO)5(CN)] to give [Fe2-
{l-C(C6H4CF3-p)NCCr-(CO)5}(l-CO)(CO)2-
(g5-C9H7)2] (8)
As described for the reaction of 5 with [NaCr-
(CO)5(CN)], freshly prepared (in situ) 5 by the reaction
of 4 (0.150 g, 0.24 mmol) with HBF4 Æ Et2O (0.060 mL,
0.40 mmol), suspended in 50 mL of THF at ꢀ80 ꢁC was
reacted with [NaW(CO)5(CN)] (0.100 g, 0.29 mmol) at
ꢀ80 to ꢀ40 ꢁC for 3 h. The resulting mixture was worked
up as described for the preparation of 8 to give 0.160 g
(72%, based on 5) of brown-red crystalline 10: m.p. 84–
86 ꢁC (dec.); IR (CH2Cl2): m(CO) 2045 (m), 1993 (s), 1944
To a suspension of 5, freshly prepared (in situ) by the
reaction of 4 (0.250 g, 0.40 mmol) with HBF4 Æ Et2O
(0.100 mL, 0.67 mmol), in 50 mL of THF at ꢀ80 ꢁC was
added 0.100 g (0.41 mmol) of [NaCr(CO)5(CN)]. The reac-
tion mixture was stirred at ꢀ80 to ꢀ40 ꢁC for 3 h, during
which time the blackish suspension turned dark red solu-
tion. The resulting solution was evaporated under high vac-
uum at ꢀ40 ꢁC to dryness and the blackish residue was
chromato-graphed on an alumina column at ꢀ25 ꢁC with
petroleum ether/CH2Cl2 (3:1) as the eluant. The brown
band was eluted and collected. After vacuum removal of
the solvent, the residue was recrystallized from petroleum
ether/CH2Cl2 solution at ꢀ80 ꢁC to give 0.138 g (58%, based
on 1) of brown-red crystals of 8: m.p. 94–96 ꢁC (dec.); IR
(CH2Cl2): m(CO) 2045 (m), 1993 (s), 1949 (vs), 1818 (w)
(vs), 1810 (w) cmꢀ1; m(CN) 2112 (w) cmꢀ1 1H NMR
;
(CD3COCD3): d 8.02–7.60 (m, 4H, p-CF3C6H4), 7.58–
7.30 (m, 8H, 2C9H7), 6.56 (dd, 2H, 2C9H7), 5.43 (t, 2H,
2C9H7), 5.03 (m, 2H, 2C9H7); MS m/e 412 [M+ꢀ2COꢀ
W(CO)5CNꢀC9H7], 356 [M+ꢀ2COꢀW(CO)5CNꢀFeꢀ
C9H7], 267 [M+ꢀ2COꢀW(CO)5CNꢀC9H7-CF3C6H4],
115 ðC9Hþ7 Þ. Anal. Calc. for C35H18O8F3NFe2W: C,
45.50; H, 1.95; N, 1.50. Found: C, 45.87; H, 2.04; N, 1.98%.
1
cmꢀ1; m(CN) 2109 (w) cmꢀ1; H NMR (CD3COCD3): d
2.10. X-ray crystal structure determinations of complexes
4, 6, 7, and 10
7.79–7.53 (m, 4H, p-CF3C6H4), 7.50–7.44 (m, 8H, 2C9H7),
6.56 (m, 2H, 2C9H7), 5.41 (t, 2H, 2C9H7), 5.00 (m, 2H,
2C9H7); MS m/e 386 [M+ꢀ2COꢀCr(CO)5CNꢀCF3C6H4],
318 [M+ꢀ2COꢀCr(CO)5CNꢀFeꢀC6H4CF3-p], 290 [M+ꢀ
3COꢀCr(CO)5CNꢀFeꢀC6H4CF3-p], 278 [M+ꢀ3COꢀCr-
(CO)5CNꢀFeꢀCC6H4CF3-p], 115 ðC9Hþ7 Þ. Anal. Calc. for
C35H18O8F3NFe2Cr Æ CH2Cl2: C, 48.79; H, 2.28; N, 1.58.
Found: C, 48.45; H, 2.50; N, 1.48%.
The single crystals of 4, 6, 7, and 10 suitable for X-ray
diffraction studies were obtained by recrystallization from
petroleum ether/CH2Cl2 solution at ꢀ80 ꢁC. Single crystals
were mounted on a glass fibre and sealed with epoxy glue.
The X-ray diffraction intensity data for 4, 7, 8, and 10 were
collected with a Bruker Smart diffractometer at 20 ꢁC using
˚
Mo Ka radiation (k = 0.71073 A) with a 2h scan mode.
2.8. Reaction of 5 with Na[Mo(CO)5(CN)] to give [Fe2-
{l-C(C6H4CF3-p)NCMo-(CO)5}(l-CO)(CO)2(g5-
C9H7)2] (9)
The structures of 4, 6, 7, and 10 were solved by the direct
methods and expanded using Fourier techniques. For com-
plexes 2, 6, and 10, the some non-hydrogen atoms were
refined anisotropically, while the rest were refined isotropi-
cally, and the hydrogen atoms were included but not refined.
For complex 7, the non-hydrogen atoms were refined aniso-
tropically and the hydrogen atoms were included but not
refined. For the four complexes, the absorption corrections
were applied using SADABS. The final cycle of full-matrix
least-squares refinement was based on the observed reflec-
tions and the variable parameters and converged with
unweighted and weighted agreement to give the agreement
factors of R and Rw which are listed in Table 1.
The details of the crystallographic data and the proce-
dures used for data collection and reduction information
for 4, 6, 7, and 10 are given in Table 1. The selected bond
lengths and angles are listed in Table 2. The atomic coordi-
nates and Biso/Beq, anisotropic displacement parameters,
complete bond lengths and angles, least-squares planes
Using the same procedure above, freshly prepared
(in situ) 5 by the reaction of 4 (0.150 g, 0.24 mmol) with
HBF4 Æ Et2O (0.060 mL, 0.40 mmol), suspended in 50 mL
of THF at ꢀ80 ꢁC was reacted with 0.080 g (0.28 mmol)
of [NaMo(CO)5(CN)]. The reaction mixture was stirred
at ꢀ80 to ꢀ40 ꢁC for 3 h, during which time the blackish
suspension turned dark red solution. Further treatment
of the resulting solution as described in the preparation
of 8 gave 0.125 g (62%, based on 5) of brown-red crystal-
line 9: m.p. 82–84 ꢁC (dec.); IR (CH2Cl2): m(CO) 2048
(m), 1994 (s), 1950 (vs), 1810 (m) cmꢀ1; m(CN) 2108 (w)
cmꢀ1 1H NMR (CD3COCD3): d 7.78–7.57 (m, 4H, p-
;
CF3C6H4), 7.53–7.44 (m, 8H, 2C9H7), 6.56 (dd, 2H,
2C9H7), 5.63 (m, 2H, CH2Cl2), 5.41 (t, 2H, 2C9H7), 5.00
(m, 2H, 2C9H7); MS m/e 384 [M+ꢀ3COꢀMo(CO)5-

L. Zhang et al. / Journal of Organometallic Chemistry 691 (2006) 4641–4651
4645
Table 1
Crystal data and experimental details for complexes 4, 7, 8, and 10
Compound
4
6
7 Æ CH2Cl2
10 Æ CH2Cl2
Formula
C31H23O4F3Fe2
628.19
P21/c (No. 14)
16.7771(13)
9.6117(7)
C29H19O3F3Fe2
584.14
C37H27O3Cl2F3SFe2 C36H20O8Cl2F3NFe2W
Formula weight
Space group
791.25
1017.98
Pnma (No.53)
11.3883(9)
14.6661(11)
14.5225(10)
90
90
90
2425.6(3)
4
1.660
P21/n (No. 14)
15.054(5)
12.185(4)
19.219(7)
P21/c (No. 14)
13.0139(8)
9.6277(6)
˚
a (A)
˚
b (A)
˚
c (A)
17.8962(14)
29.7705(19)
a (ꢁ)
b (ꢁ)
c (ꢁ)
111.526(2)
107.131(6)
99.0320(10)
3
˚
V (A )
2684.6(4)
4
1.554
1280
3369.2(19)
4
3683.8(4)
4
Z
Dcalc (g/cm3)
F(000)
1.560
1608
1.835
463
1184
Crystal size (mm)
l (Mo Ka) (cmꢀ1
0.198 · 0.167 · 0.097 0.175 · 0.157 · 0.078 0.375 · 0.309 · 0.021 0.168 · 0.127 · 0.062
)
11.38
12.50
11.35
41.04
Orientation reflections: number; range (2h) (ꢁ)
Collected data range, 2h (ꢁ)
2510; 4.894–43.444
4.62–54.00
5848, 2825
416
0.8622–1.0000
0.0534
1098; 5.326–47.100
3.94–56.52
3019, 1479
180
0.83023–1.00000
0.0697
1553; 4.518–39.440
3.04–52.00
6582, 2853
434
0.75514–1.00000
0.0721
2921; 4.525–39.418
3.16–52.00
7190, 4478
463
0.84931–1.00000
0.0595
Number of unique data, total with [I > 2.00r(I)]
Number of parameters refined
Correction factors, maximum–minimum
Ra
b
Rw
Quality of fit in dicatorc
0.1089
1.079
0.1376
0.946
0.1314
0.889
0.1283
0.944
Maximum shift/estimated standard deviations final cycle 0.094
0.001
0.430
ꢀ0.516
0.001
0.442
ꢀ0.430
0.098
2.223
ꢀ1.087
3
˚
Largest peak (e/A )
Minimum peak (e/A )
1.228
ꢀ0.740
3
˚
P
P
a
b
c
R = iFoj ꢀ jFci/ jFoj.
P
P
P
Rw = [ w(jFoj ꢀ jFcj)2/ wjFoj2]1/2; w = 1/ 2(jFoj).
P
2
1=2
Quality-of-fit ¼ ½ wðjF 2oj ꢀ jF 2cjÞ =ðNobserved ꢀ NparametersÞꢁ
.
for 4, 6, 7, and 10 are deposited in the Cambrige Crystallo-
graphic Data Center, CCDC. The molecular structures of
4, 6, 7, and 10 are given in Figs. 1–4, respectively.
perature (ꢀ40 to ꢀ20 ꢁC) for 3–4 h, followed by alkylation
with Et3OBF4. After removal of the solvent under high vac-
uum at low temperature, the residue was chromatographed
on an alumina column at low temperature, and the crude
product was recrystallized from petroleum ether/CH2Cl2
solution at ꢀ80 ꢁC to afford the diindenyl-coordinated
diiron bridging alkoxycarbene complexes [Fe2{l-C(OC2H5)-
Ar}(l-CO)(CO)2(g5-C9H7)2] (2, Ar = C6H5; 3, Ar = p-
CH3C6H4; 4, Ar = p-CF3C6H4) (Eq. (1)) in 70–81% yields.
3. Results and discussion
Compound [Fe2(l-CO)2(CO)2(g5-C9H7)2] (1) reacts with
about 20–30% molar excess of the aryllithium reagents, ArLi
(R = C6H5, p-CH3C6H4, p-CF3C6H4), in ether at low tem-
O
O
C
C
Et2O
_
Fe
Fe
ArLi
+
o
Fe
Fe
-40 -20 C
CO
OC
C
CO
OC
C
O
-
+
.
Ar
O Li xEt2O
1
ð1Þ
O
C
Et3OBF4
Fe
Fe
Ar
o
H O,
0 C
2
CO
OC
C
OEt
2, Ar = C6H5
3, Ar = p-CH3C6H4
4, Ar = p-CF3C6H4

4646
L. Zhang et al. / Journal of Organometallic Chemistry 691 (2006) 4641–4651
Table 2
a
Selected bond lengths (A) and angles (ꢁ)a for complexes 4, 6, 7, and 10
˚
Complex
4
6 (Fe(1) = Fe, Fe(2) = FeA)
7
10
Fe(1)–Fe(2)
Fe(1)–C(3)
Fe(2)–C(3)
Fe(1)–C(4)
Fe(2)–C(4)
Fe(1)–C(1)
Fe(2)–C(2)
C(3)–O(3)
2.5392(9)
2.007(4)
2.023(4)
1.909(5)
1.898(5)
1.731(5)
1.748(5)
1.413(4)
2.5393(15)
1.960(6)
1.960(6)
1.919(6)
1.919(6)
1.739(6)
2.5647(16)
2.025(6)
2.017(6)
1.936(7)
1.915(7)
1.728(9)
1.753(8)
2.5551(19)
1.992(9)
1.984(9)
1.952(9)
1.936(10)
1.761(12)
1.763(11)
C(3)–S(1)
1.860(7)
C(3)–N(1)
C(3)–C(5)
C(4)–O(4)
S(1)–C(31)
N(1)–C(11)
C(11)–W(1)
Fe(1)–C(Cp) (av)
Fe(2)–C(Cp) (av)
1.454(11)
1.508(12)
1.131(10)
1.503(5)
1.170(4)
1.445(10)
1.170(8)
1.486(8)
1.152(7)
1.778(7)
1.134(10)
2.135(10)
2.154
2.158
2.140
2.152
2.160
2.144
2.155
Fe(1)–Fe(2)–C(3)
Fe(1)–C(3)–Fe(2)
Fe(2)–Fe(1)–C(3)
Fe(1)–Fe(2)–C(4)
Fe(1)–C(4)–Fe(2)
Fe(2)–Fe(1)–C(4)
C(3)–Fe(1)–C(4)
C(3)–Fe(2)–C(4)
Fe(1)–C(1)–O(1)
Fe(1)–C(3)–C(5)
Fe(2)–C(3)–C(5)
Fe(1)–C(3)–S(1)
Fe(1)–C(3)–N(1)
Fe(2)–C(2)–O(2)
Fe(2)–C(3)–S(1)
Fe(2)–C(3)–N(1)
C(5)–C(3)–S(1)
C(5)–C(3)–N(1)
C(3)–S(1)–C(31)
C(3)–N(1)–C(11)
N(1)–C(11)–W(1)
a
50.68(12)
78.10(15)
51.22(11)
48.35(14)
83.7(2)
47.98(15)
98.05(19)
97.88(19)
50.76(18)
78.8(2)
50.49(19)
48.6(2)
83.5(3)
50.49(19)
97.1(3)
50.2(3)
80.0(3)
49.9(3)
49.2(3)
82.2(4)
48.7(3)
97.1(4)
97.9(4)
177.2(12)
124.5(7)
121.7(6)
80.7(3)
49.63(14)
82.9(3)
48.57(15)
97.2(2)
98.1(3)
177.6(4)
119.0(3)
120.4(3)
176.9(6)
127.9(3)
127.9(3)
174.2(7)
124.9(5)
118.4(5)
108.7(3)
112.8(6)
175.0(10)
173.4(4)
175.9(7)
117.6(3)
114.6(6)
102.9(7)
106.8(4)
113.1(3)
178.9(9)
178.9(9)
Estimated standard deviations in the least significant figure are given in parentheses.
Complexes 2–4 are soluble in polar organic solvents but
slightly soluble in nonpolar solvents. They are very sensi-
tive to air and temperature in solution but relatively stable
as the solid. The proposed structure for 2–4 was first sup-
ported by elemental analyses and spectroscopic data. The
IR spectra of complexes 2–4 showed the two CO absorp-
tion bands at 1932–1973 cmꢀ1 in the terminal m(CO) region
and one at 1782–1784 cmꢀ1 in the bridging m(CO) region,
evidence an (CO)2Fe2(l-CO) moiety in these complexes
and suggested that only one l-CO ligand was converted
into a bridging carbene ligand upon the reaction of 1 with
nucleophilic aryllithium and subsequent alkylation with
Et3OBF4 in four-carbonyl compound 1. The further char-
acterization for their structures was obtained by X-ray
analysis of 4, which firmly confirmed that products 2–4
are diindenyl-coordinated diiron complexes with a bridging
carbene ligand, in which the two indenyl ligands are coor-
dinated the two iron atoms through their cyclopentadienyl
ring moiety in g5-bonding.
There are two bridging CO ligands which have the same
chemical environment in the starting 1. It was expected that
the diiron di-bridging alkoxy(aryl)carbene complexes
should exist in the resulting products when treating 1 with
aryllithium reagents. However, no expected diiron di-
bridging alkoxy(aryl)carbene complexes or their derivatives
were obtained from the reactions even though more than
two molar equivalents of aryllithium reagent were used
for the reactions.
In addition, compound 1 has two forms of coordi-
nated carbonyl ligands, terminal and bridging CO. It
can be expected that the aryllithium reagent could attack
both terminal and bridging CO ligands to produce a
terminal alkoxy(aryl)carbene and
oxy(aryl)carbene complexes when treating 1 with arylli-
thium reagent. However, only diiron bridging
a
bridging alk-
a
alkoxycarbene complex was obtained, which could be
produced via an attack of nucleophilic aryllithium
reagent on a bridging CO of 1 although this attack is

L. Zhang et al. / Journal of Organometallic Chemistry 691 (2006) 4641–4651
4647
benzene ring C(5)C(6)C(7)C(8)C(9)C(10) plane is, respec-
tively, oriented at an angle of 52.89ꢁ, 75.48ꢁ, and 72.62ꢁ
with respect to the Fe(1)Fe(2)C(3) plane, the indene ring
C(13) through C(21) plane, and the indene ring C(22)
through C(30) plane. There should exist cis and trans iso-
mers in starting compound 1, which cannot be isolated,
and the both isomers should participate in the reaction.
However, only the trans isomer of product 4, in which
the two indenyl groups adopt a trans configuration, was
obtained.
The reaction pathway to complexes 2–4 shown in Eq. (1)
is similar to that of the reactions of the cyclopentadienyl-
and COT-coordinated diiron carbonyl compounds with
aryllithium reagents [7,8]. The Arꢀ anion firstly attacks
on a bridging CO ligand of 1to form an acylmetallate inter-
mediate, which is subsequently alkylation with Et3OBF4 to
afford diiron bridging alkoxycarbene complex. To our
knowledge, complexes 2–4 are the first examples of the
indenyl-coordinated dimetal bridging carbene complexes.
The bridging alkoxycarbene complex 4 in ether was trea-
ted, similar to the procedures for the preparation of the
COT-coordinated diiron cationic bridging carbyne com-
plexes [Fe2(l-CAr)(CO)4(g8-C8H8)]BF4 [11] and pyrida-
zine-coordinated diiron cationic bridging carbyne
complex [(C4H4N2)Fe2(l-CAr)(CO)6]BF4 [20] with an
exess of HBF4ÆEt2O at low temperature (ꢀ60 to ꢀ30 ꢁC)
for 1 h to give a brown-red solid [Fe2(l-CC6H4CF3-p)(l-
CO)(CO)2(g5-C9H7)2]BF4 (5) (Eq. (2)) in 85% yield.
Fig. 1. Molecular structure of 4, showing the atom-numbering scheme
with 45% thermal ellipsoids.
unfavorable due to the higher electron density on the
bridging carbonyl.
The molecular structure of 4 confirmed by X-ray crystal-
lography is shown in Fig. 1. The two indenyl ligands lie in
the trans position, as can be visualized in the ORTEP dia-
gram of 4 in Fig. 1. There exist two different coordinated
CO ligands in molecule 4, and the bond distances of
Fe–C(CO) are also different. The Fe–CO (bridged, sp2) dis-
O
C
+
HBF4
Fe
Fe
Ar
CO
OC
C
OEt
4, Ar = p-CF3C6H4
˚
tances are 1.909(5) and 1.898(5) A, while Fe–CO (nonbrid-
˚
ð2Þ
ged, sp) are 1.731(5) and 1.748 (6) A, respectively. The
˚
distance (2.5392(9) A) of the Fe–Fe bond bridged by the
O
C
l-carbene ligand is somewhat longer in value than that
found in analogous bridging carbene complex [Fe2(l-
Et2O
BF4
Fe
Fe
_
o
˚
CO){l-C(OEt)C6H5}(CO)2(g-C5H5)2] (2.512(1) A) [7] and
- 60 -30 C
CO
OC
[Fe2(l-CO){l-C(OC2H5)C6H5}(CO)2{(g5-C5H4)2Si(CH3)2}]
C
Ar
˚
(2.513(1) A) [8]. The alkylidene carbon asymmetrically
˚
bridges the Fe–Fe bond (Fe(1)–C(3) = 2.007(4) A, Fe(2)–
5, Ar = p-CF3C6H4
˚
C(3) = 2.023(4) A). The l-C–Fe distances are somewhat
˚
longer than the l-Fe-CO bond (C(4)–Fe(1) 1.909(5) A,
The compound 5 would be a diindenyl-coordinated
diiron cationic complex with a bridging carbyne ligand as
inferred from its reactivity (below) and previously reported
˚
C(4)–Fe(2) 1.898(5) A) but approximately equal to those
in
complexes
[Fe2(l-CO){l-C(OEt)-C6H5}(CO)2(g5-
1
˚
˚
C5H5)2] (C(1)–Fe(1) 2.03(1) A and C(1)–Fe(2) 2.00(1) A)
analogous compexes [12] as well as its IR and H NMR
[7] and [Fe2(l-CO){l-C(OC2H5)C6H5}(CO)2{(g5-C5H4)2-
spectra. Complex 5 is only sparingly soluble in polar
organic solvents such as THF and CH2Cl2 and very sensi-
tive to air, moisture, and temperature and can be stored at
low temperature (below ꢀ60 ꢁC) only for a short period of
time. The carbyne structure is just a plausible proposal for
complex 5, which was prepared in situ and not fully
characterized.
˚
Si(CH3)2}] (C(1)–Fe(1) 2.023(5) A and C(1)–Fe(2)
2.021(5) A) [8]. In both indenyl ligands, the Cp ring and
˚
benzene ring moieties are coplanar. The angle between
the two indene ring planes is 84.32ꢁ, approximately perpen-
dicular to each other. The dihedral angle between the
Fe(1)Fe(2)C(3) and Fe(1)Fe(2)C(4) planes is 15.15ꢁ. The

4648
L. Zhang et al. / Journal of Organometallic Chemistry 691 (2006) 4641–4651
The freshly prepared (in situ) cationic carbyne complex
5 reacts with NaBH4 in THF at ꢀ80 to ꢀ40 ꢁC for 3 h.
After workup as described in Section 2, a brown-red bridg-
ing arylcarbene complex [Fe2{l-C(H)C6H4CF3-p}(l-
CO)(CO)2ꢀ(g5-C9H7)2] (6) was obtained in 80% yield
(Eq. (3)), supported by microanalytic and spectroscopic
data and its X-ray diffraction analysis.
O
C
+
NaBH4
BF4
Fe
Fe
CO
OC
C
Ar
5, Ar = p-CF3C6H4
ð3Þ
O
C
THF
-80 -40oC
_
Fe
Fe
Ar
CO
OC
C
H
6, Ar = p-CF3C6H4
1
The H NMR spectrum had a resonance at 10.36 ppm,
characteristic for a l-CHR group. However, this resonance
has undergone a significant upfield shift, as compared to that
of analogous cyclopentadienyl-coordinated bridging aryl-
carbene complex [Fe2(l-CO){l-C(H)C6H4CH3-p}(CO)2(g-
C5H5)2] (d 12.40) [12], which probably is arising from that
the H atom is influenced by the ring current of the dindenyl
moiety.
Fig. 2. Molecular structure of 6, showing the atom-numbering scheme
with 45% thermal ellipsoids.
O
C
The molecular structure of 6 is shown in Fig. 2. Com-
plex 6 has a mirror plane passing through C(5) and C(8)
of the benzene ring, the C(11) and F(1) atoms, the C(4)
and O(4) atoms, and the bridging carbene carbon
(C(3)). The two Fe atoms are coordinated symmetrically
(relative to the mirror) by the two indenyl groups, respec-
+
NaSC6H4CH3-p
BF4
Fe
Fe
CO
OC
C
Ar
5, Ar = p-CF3C6H4
ð4Þ
˚
tively. The Fe–Fe distance in 6 (2.5393(15) A) is essentially
the same as that in the bridging alkoxy-carbene complex
4 (2.5392(9) A) and close to that of analogous cyclopenta-
O
˚
C
THF
-80 -40oC
Fe
Fe
Ar
dienyl-coordinated complex [Fe2(l-CO){l-C(H)C6H4CH3-
_
CO
OC
˚
C
p}(CO)2-(g-C5H5)2] (2.523(2) A) [12], but is significantly
SC6H4CH3-p
shorter than that found in analogous COT-coordinated
complex [Fe2{l-C(H)C6H4CF3-p}(CO)4(g8-C8H8)] (2.7069
7, Ar = p-CF3C6H4
˚
(11) A) [11a]. In addition to the molecular configuration,
an apparent difference in the structure of 4 and 6 is the
shorter C(3)–C(5) bond in 6 (1.445(10) A), which is inter-
The elemental analysis and spectroscopic data (Section
˚
2) supported the proposed structure of complex 7 shown
1
mediate between C–C single and C@C double bond
in Eq. (4). The H and 13C NMR data indicated the pres-
˚
lengths, as compared to 4 (1.503(5) A).
ence of two indenyl groups and a bridging carbene ligand.
The further characterization for its molecular structure was
obtained by X-ray structural determination.
The molecular structure of 7 (Fig. 3) resembles that of 6,
except the substituent on the l-carbene carbon is an p-
CH3C6H4S group in 7 but a H atom in 6. The two indenyl
Cationic bridging carbyne complexes 5 also reacts with
NaSC6H4CH3-p under the similar conditions to give the
diindenyl-coordinated diiron bridging arylthiocarbene com-
plexes [Fe2{l-C(C6H4CF3-p)SC6H4CH3-p}(l-CO)(CO)2-
(g5-C9H7)2] (7) (Eq. (4)) in 59% yield.

L. Zhang et al. / Journal of Organometallic Chemistry 691 (2006) 4641–4651
4649
benzene ring composed by C(31) through C(36) plane are
at angles of 62.05ꢁ and 69.27ꢁ and of 16.56ꢁ and 86.05ꢁ,
respectively, to the planes of the two indene rings. Thus,
compound 7 exists in a cis structure to avoid steric repul-
sion between the six-membered aryl rings and the indene
rings.
The highly electrophilic complex 5 also reacts with anio-
nic carbonylmetal compound containing a CN negative
substituent, Na[M(CO)5(CN)] (M = Cr, Mo, W), in THF
at low temperature to afford diindenyl-coordinated diiron
bridging aryl(penta-carbonylcyanometal)carbene com-
plexes [Fe2{l-C(C6H4CF3-p)NCM(CO)5}(l-CO)(CO)2(g5-
C9H7)2] (8, M = Cr; 9, M = Mo; 10, M = W) (Eq. (5)) in
58–72% isolated yields, respectively.
O
C
Na[M(CO)5CN]
BF4
+
Fe
Fe
CO
OC
C
C6H4CF3-p
5
ð5Þ
O
C
THF
_
Fe
Fe
-80 -40oC
CO
OC
C
p-CF3C6H4
N C M(CO)5
8, M = Cr
9, M = Mo
10, M = W
On the basis of elemental analyses and spectroscopic evi-
dence, as well as X-ray crystallography, products 8–10 are
formulated as the diindenyl-coordinated diiron bridging
carbene complexes with a M(CO)5CN (M = Cr, Mo, W)
moiety bonded to the l-carbene carbon through the N
Fig. 3. Molecular structure of 7, showing the atom-numbering scheme
with 45% thermal ellipsoids.
groups are in a cis, almost totally eclipsed configuration.
1
The distances between the Fe atoms and the Cp ring planes
atom. The IR and H NMR spectra of 8–10 are consistent
˚
of the indenyl ligands are nearly 1.78 A. The least-squares
with their structures shown in Eq. (5). The IR spectra of 8–
10 in the m(CO) region show the four absorption bands of
the CO groups at ca. 2048–1810 cmꢀ1. The characteristic
plane calculations show that the carbon atoms in the
indene ring are coplanar and the two CO groups coordi-
nated to the same Fe atom are not coplanar arising from
the bridge. The distance of the Fe–Fe bond bridged by
m(CN) stretching vibration occurs at ca. 2108–2112 cmꢀ1
,
similar to those of analogous aryl(pentacarbonylcyano-
metal)carbene complexes [Fe2(l-CO){l-C(C6H4CF3-p)N
CM(CO)5}(CO)2(g5-C5H5)2] (M = Cr, Mo, W) (at ca.
˚
the l-carbene ligand in 7 is 2.5647(16) A, which is obvi-
ously longer than that in 4 and 6. The l-carbene carbon
almost symmetrically bridges the Fe–Fe bond with C(3)–
1
2125 cmꢀ1) [9]. The H NMR spectra of 8–10 showed the
˚
˚
Fe(1) of 2.025(6) A and C(3)–Fe(1) of 2.017(6) A. The
C(3)–S bond length of 1.860(7) indicates that it is essen-
signals for the indenyl and aryl rings at ca. 8.02–
7.30 ppm which are downfield of those in 4, 6, and 7 (at
7.63–6.93 ppm) because of the stronger electron-accepting
ability of (CO)5MCN as compared to OC2H5, H, and p-
CH3C6H4S groups. The structures of complexes 8–10 are
further confirmed by a single-crystal X-ray diffraction of
10.
The molecular structure of 10 (Fig. 4) resembles that of
7, except that the p-CH3C6H4S substituent at the l-carbene
carbon in 7 is replaced by the W(CO)5CN group in 10.
tially single bond as comparison with standard C(sp2)–S
3
˚
˚
(1.76 A) [21] single bond and C(sp )–S (1.81 A) [21] single
bond distances. In molecule 7, the two benzene rings are
on the opposite side of the two indene rings. The angles
between the two indene ring planes and the benzene ring
C(5) through C(10) and the benzene ring C(31) through
C(36) planes are 76.91ꢁ and 45.49ꢁ, respectively. The ben-
zene ring composed by C(5) through C(10) plane and the

4650
L. Zhang et al. / Journal of Organometallic Chemistry 691 (2006) 4641–4651
2–4 and discovered the reactions of the cationic bridging
carbyne complex 5 of 4 with the nucleophiles involving
carbonylmetal anions, which produced a series of novel diin-
denyl-coordinated diiron bridging carbene complexes. This
provides an useful and convenient method for the prepara-
tion and structural modification of such dimetal bridging
carbene complexes. Further studies on the scope of the
reaction and the application in organometallic and organic
synthesis are now being carried out in our laboratory.
4. Supplementary material
Crystallographic data for the structural analysis of com-
plexes 4, 6, 7, and 10 have been deposited with the Cam-
bridge Crystallographic Data Center, CCDC Nos. 602212
for 4, 602213 for 6, 602214 for 7, and 602215 for 10. Copies
of this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge CB2
1EZ, UK (fax: +44 1233 336 033; e-mail: deposit@ccdc.
cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
Acknowledgments
We thank the National Natural Science Foundation of
China, and the JSPS of Japan for financial support of this
research.
Fig. 4. Molecular structure of 10, showing the atom-numbering scheme
with 45% thermal ellipsoids.
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In summary, we have synthesized a new type of the diin-
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