Unusual reactions of cationic bridging carbyne complexes of dimethylsilane-bridged bis(η5-cyclopentadienyl)diiron tricarbonyl with carbonylmetal anions

Article abstract of DOI:10.1016/S0022-328X(02)01661-3

The reactions of the dimethylsilane-bridged cationic carbyne complexes of diiron, [Fe₂(μ-CO)(μ-CAr)(CO)₂{(η⁵- Na[M(CO)₅CN] (4, M = Cr; 5, M = Mo; 6, M = W) in THF at low temperature afford diiron bridging carben

Full text of DOI:10.1016/S0022-328X(02)01661-3

Journal of Organometallic Chemistry 658 (2002) 214Á227
/
www.elsevier.com/locate/jorganchem
Unusual reactions of cationic bridging carbyne complexes of
dimethylsilane-bridged bis(h5-cyclopentadienyl)diiron tricarbonyl
with carbonylmetal anions
Ruitao Wang a, Jie Sun a, Jiabi Chen a,*, Qiang Xu b,*, Yoshie Souma b
a State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai
200032, People’s Republic of China
b National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31, Midorigaoka, Ikeda, Osaka 563-8577, Japan
Received 13 May 2002; accepted 11 June 2002
Abstract
The reactions of the dimethylsilane-bridged cationic carbyne complexes of diiron, [Fe2(m-CO)(m-CAr)(CO)2{(h5-
C5H4)2Si(CH3)2}]BBr4 (1, Arꢀ
5, MꢀMo; 6, Mꢀ
C(Ar)NCM(CO)5}(CO)2{(h5-C5H4)2Si(CH3)2}] (9, Mꢀ
MꢀCr, Arꢀp-CF3C6H4; 13, MꢀMo, Arꢀp-CF3C6H4; 14, Mꢀ
cationic carbyne complex [Fe2(m-CO)(m-CC6H4CH3-p)(CO)2{(h5-C5H4)2Si(CH3)2}]BBr4 (3) reacts with 4Á
conditions to produce novel cationic bridging carbyne complexes
[Fe2(m-CO)(m-CC6H4CH3-p)(CO)2{(h5-
C5H4)2Si(CH3)2}]ꢁ[M(CO)5CN]ꢂ (15, Mꢀ
Cr; 16, MꢀMo; 17, MꢀW). Analogous cationic bridging carbyne complex [Fe2(m-
CO)(m-CC6H4CH3-p)(CO)2{(h5-C5H4)2Si(CH3)2}]ꢁ[Fe(CO)4CN]ꢂ (18) can also be obtained from the reaction of 3 with
Na[Fe(CO)4CN] (7). Complex 15 or 16 reacts with NaSR (RꢀCH3, C6H5, p-CH3C6H4) to give bridging mercaptocarbene
complexes [Fe2(m-CO){m-C(SR)C6H4CH3-p}(CO)2{(h5-C5H4)2Si(CH3)2}] (19, Rꢀ
CH3; 20, RꢀC6H5; 21, Rꢀp-CH3C6H4) in
/
C6H5; 2, Arꢀ
W) in THF at low temperature afford diiron bridging carbene complexes [Fe2(m-CO){m-
Cr, ArꢀC6H5; 10, MꢀMo, ArꢀC6H5; 11, MꢀW, ArꢀC6H5; 12,
W, Arꢀp-CF3C6H4). In contrast to the reaction of 1 and 2,
6 under the same
/
p-CF3C6H4), with carbonylmetal anionic compounds Na[M(CO)5CN] (4, Mꢀ
/
Cr;
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
high yields. The related reaction of 1 with NaN(SiMe3)2 affords a novel benzonitrile-coordinated diiron complex [Fe2(m-
CO)2(CO)NCC6H5{(h5-C5H4)2Si(CH3)2}] (22). Unexpectedly, the reactions of 1 and 2 with 7 yield diiron bridging arylcarbene
complexes [Fe2(m-CO){m-C(H)Ar}(CO)2{(h5-C5H4)2Si(CH3)2}] (23, Arꢀ
/
C6H5; 24, Arꢀ
bridging p-tolyl-carbene complex [Fe2(m-CO){m-C(H)C6H4CH3-p}(CO)2{(h5-C5H4)2Si(CH3)2}] (25) were also obtained from the
reactions of 1Á3 with [(PPh3)2N][Cr(CO)4NO] (8). The structures of 14, 15, 22, and 23 have been established by X-ray
/
p-CF3C6H4). The products 23 and 24 and
/
crystallography. # 2002 Elsevier Science B.V. All rights reserved.
Keywords: Reaction; Diiron; Carbonylmetal anions; Bridging carbyne complexes
1. Introduction
co-workers by reactions [1Á4] of carbene or carbyne
/
complexes with low-valent metal species or by reactions
[3,4] of neutral or anionic carbyne complexes with metal
hydrides or cationic metal compounds. In continuation
of our interest in developing the methodologies of the
synthesis of transition metal bridging carbene and
carbyne complexes, we have studied the reactions of
the cationic carbyne complexes of transition metal with
carbonylmetal anions. Recently, we have shown a
convenient method for the preparation of dimetal
bridging carbene and/or carbyne complexes: the reac-
tions [5,6] of highly electrophilic cationic carbyne
complexes of manganese and rhenium, [h5-
Our interest in the chemistry of di- and polynuclear
metal complexes with bridging carbene and bridging
carbyne ligands stems from that many such complexes
are themselves metal clusters or are the precursors of
metal cluster complexes. A considerable number of
dimetal complexes containing bridging carbene and
carbyne ligands have been synthesized by Stone and
* Corresponding authors. Fax: ꢁ
E-mail addresses: chenjb@pub.sioc.ac.cn (J. Chen), q.xu@aist.go.jp
(Q. Xu).
/86-21-64166128
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 6 6 1 - 3

R. Wang et al. / Journal of Organometallic Chemistry 658 (2002) 214Á
/227
215
C5H5(CO)2MÅ
/
CC6H5]BBr4 (Mꢀ
/
Mn, Re), with carbo-
chased from Fluka Chemcal Co. and Aldrich Chemical
Co., respectively. Compounds Na[Cr(CO)5CN] (4) [9],
Na[Mo(CO)5CN] (5) [9], Na[W(CO)5CN] (6) [9],
Na[Fe(CO)4CN] (7) [10], and [(PPh3)2N] [Cr(CO)4NO]
(8) [11] were prepared by literature methods.
nylmetal anionic compounds. Most recently, we found a
new method for the preparation of dimetal bridging
carbene complexes that is the reactions of diiron cationic
bridging
CAr)(CO)2(h5-C5H5)2]BBr4 (Arꢀ
and
BBr4 (Arꢀ
cleophiles. For instance, both diiron cationic carbyne
complexes react with NaSR (Rꢀalkyl or aryl) or
Na[M(CO)5CN] (MꢀCr, Mo, W) to give a series of
diiron bridging carbene complexes [Fe2(m-CO){m-
or
carbyne
complexes,
[Fe2(m-CO)(m-
Ph, p-CH3C6H4)
/
IR spectra were measured on a PerkinÁElmer 983G
/
[Fe2(m-CO)(m-CAr)(CO)2{(h5-C5H4)2Si(CH3)2}]-
spectrophotometer. All H-NMR spectra were recorded
at ambient temperature in acetone-d6 solution with
Me4Si as the internal reference using a Bruker AM-
300 spectrometer. Electron ionization mass spectra
1
/C6H5, p-CH3C6H4, p-CF3C6H4), with nu-
/
/
(EIMS) were run on a HewlettÁPackard 5989A spectro-
/
meter. Melting points obtained on samples in sealed
nitrogen-filled capillaries are uncorrected.
C(SR)Ar}(CO)2(h5-C5H5)2]
[Fe2(m-CO){m-
C(C6H4CH3-p)NCM(CO)5}(CO)2(h5-C5H5)2] [7] and
[Fe2(m-CO){m-C(SR)Ar}(CO)2{(h5-C5H4)2Si(CH3)2}]
[8], respectively. This offers useful method for the
preparation and structural modification of dimetal
bridging carbene complexes.
2.1. Reaction of [Fe2(m-CO)(m-CC6H5)(CO)2{(h5-
C5H4)2Si(CH3)2}]BBr4 (1) with Na[Cr(CO)5CN] (4)
to give [Fe2(m-CO){m-C(C6H5)NCCr(CO)5}(CO)2-
{(h5-C5H4)2Si(CH3)2}] (9)
In order to explore the reactivity of different diiron
cationic bridging carbyne complexes and the effect of
different carbonylmetal anions on the reactivity of the
diiron cationic carbyne complexes, and to further
examine the scope of this preparation of dimetal
bridging carbene and bridging carbyne complexes, we
carried out the study of the reactivity of the dimethylsi-
lane-bridged diiron cationic bridging carbyne complexes
[Fe2(m-CO)(m-CAr)(CO)2{(h5-C5H4)2Si(CH3)2}]BBr4 (1,
To 0.400 g (0.494 mmol) of freshly prepared (in situ)
compound 1 dissolved in 60 ml of THF at ꢂ
added 0.140 g (0.581 mmol) of Na[Cr(CO)5CN] (4). The
reaction mixture was stirred at ꢂ100 to ꢂ80 8C for 1 h,
during which time the turbid solution gradually turned
purple red. After stirring at ꢂ80 to ꢂ50 8C for an
additional 4 h, the resulting solution was evaporated
under high vacuum at ꢂ45 8C to dryness and the dark
red residue was chromatographed on an alumina
column (1.6ꢃ15Á20 cm) at ꢂ25 8C with petroleum
etherÁCH2Cl2 (10:1) as the eluant. The red band was
/
100 8C was
/
/
/
/
/
Arꢀ
with carbonylmetal anionic compounds containing a
CN group, Na[M(CO)nCN] (MꢀCr, Mo, W, nꢀ5;
MꢀFe, nꢀ4), or a three-electron ligand of NO,
/
C6H5; 2, Arꢀ
/
p-CF3C6H4; 3, Arꢀp-CH3C6H4)
/
/
/
/
/
/
/
/
/
eluted and collected. After vacuum removal of the
[(PPh3)2N][Cr(CO)4NO]. These reactions produce a
series of novel di- or trimetal bridging carbene and
cationic bridging carbyne complexes. Herein we report
these unusual reactions and the structural characteriza-
tions of the resulting products.
solvent, the residue was recrystallized from petroleum
etherÁ
(84%, based on 1) of purpleÁ
point (decomposition) m.p. (dec.) 89Á
(CH2Cl2)?(CO) 2047 (m), 1998 (s), 1936 (vs) 1811 (m),
1710 (m) cmꢂ1; n(CN) 2057 (w) cmꢂ1 1H-NMR
(CD3COCD3) d 8.51Á7.36 (m, 5H, C6H5), 6.84 (s, 2H,
/
CH2Cl2 (15:1) solution at ꢂ
red crystals of 9: melting
91 8C; IR
/
80 8C to give 0.286 g
/
/
;
/
2. Experimental
C5H4), 6.76 (s, 2H, C5H4), 6.08 (s, 2H, C5H4), 5.44 (s,
2H, C5H4), 0.64 (s, 3H, SiCH3), 0.29 (s, 3H, SiCH3); MS
All procedures were performed under a dry, oxygen-
free N2 atmosphere using standard Schlenk techniques.
All solvents employed were reagent grade and dried by
refluxing over appropriate drying agents and stored over
˚
4 A molecular sieves under a N2 atmosphere. The
tetrahydrofuran and diethyl ether were distilled from
m/e 443 [Mꢁꢂ
Cr(CO)5CNꢂ
/
Cr(CO)5CNꢂ
/
CO], 415 [Mꢁꢂ
Cr(CO)5CNꢂ3CO],
/
/
2CO], 387 [Mꢁꢂ
/
/
218 [Cr(CO)5CNꢁ], 192 [Cr(CO)5ꢁ]. Anal. Calc. for
C28H19O8NSiCrFe2: C, 48.80; H, 2.78; N, 2.03. Found:
C, 48.72; H, 3.05; N, 2.18%.
The following complexes were prepared by similar
reactions.
sodium benzophenone ketyl, while petroleum ether (30Á
/
60 8C) and CH2Cl2 were distilled from CaH2. The
neutral alumina used for chromatography was deox-
ygenated at room temperature (r.t.) under high vacuum
for 16 h, deactivated with 5% w/w N2-saturated water,
and stored under N2. Complexes [Fe2(m-CO){m-
2.2. [Fe2(m-CO){m-C(C6H5)NCMo(CO)5}(CO)2-
{(h5-C5H4)2Si(CH3)2}] (10)
PurpleÁ
/
red crystals (82% yield); m.p. (dec.) 75Á
/
CAr}(CO)2{(h5-C5H4)2Si(CH3)2}]BBr4 (1, Arꢀ
/
C6H5;
76 8C; IR (CH2Cl2) n(CO) 2014 (m), 1993 (w), 1929
2, Arꢀ
/
p-CF3C6H4; 3, Arꢀ/p-CH3C6H4) were prepared
(vs, br), 1854 (m), 1784 (w) cmꢂ1; n(CN) 2043 (m)
as previously described [8]. NaSCH3, NaSC6H5,
NaSC6H4CH3-p, and NaN(SiMe3)2 (95%) were pur-
cmꢂ1
C6H5), 6.82 (s, 2H, C5H4), 6.76 (s, 2H, C5H4), 6.08 (s,
;
1H-NMR (CD3COCD3) d 8.37Á
/7.36 (m, 5H,

216
R. Wang et al. / Journal of Organometallic Chemistry 658 (2002) 214Á227
/
2H, C5H4), 5.45 (s, 2H, C5H4), 0.64 (s, 3H, SiCH3), 0.29
(s, 3H, SiCH3); MS m/e 443 [Mꢁꢂ
Mo(CO)5CNꢂCO],
415 Mo(CO)5CNꢂ2CO], 387
[Mꢁꢂ
Mo(CO)5CNꢂ3CO], 262
[Mo(CO)5CNꢁ],
(vs, br), 1800 (m), 1706 (m) cmꢂ1; n(CN) 2055 (w)
cmꢂ1 1H-NMR (CD3COCD3) d 8.74Á
8.18 (m, 4H,
/
/
;
/
/
/
[Mꢁꢂ
/
C6H4CF3), 6.91 (s, 2H, C5H4), 6.79 (s, 2H, C5H4), 6.16
(s, 2H, C5H4), 5.53 (s, 2H, C5H4), 0.67 (s, 3H, SiCH3),
/
236
[Mo(CO)5ꢁ]. Anal. Calc. for C28H19O8Fe2NSiMo: C,
45.87; H, 2.61; N, 1.75. Found: C, 45.58; H, 2.82; N,
1.94%.
0.31 (s, 3H, SiCH3); MS m/e 539 [Mꢁꢂ
/
W(CO)5CN],
W(CO)5CNꢂ
2CO], 350 [W(CO)5CNꢁ]. Anal. Calc. for
CH2Cl2: C, 39.18; H, 2.04; N,
511 [Mꢁꢂ
/
W(CO)5CNꢂ
/
CO], 483 [Mꢁꢂ
/
/
C29H18O8F3NsiÃ
/
WFe2×
/
2.3. [Fe2(m-CO){m-C(C6H5)NCW(CO)5}(CO)2{(h5-
C5H4)2Si(CH3)2}] (11)
1.58. Found: C, 38.98; H, 2.20; N, 1.74%.
2.7. Reaction of [Fe2(m-CO)(m-CC6H4CH3-
p)(CO)2{(h5-C5H4)2Si(CH3)2}]BBr4 (3) with 4 to
give [Fe2(m-CO)(m-CC6H4CH3-p)(CO)2{(h5-
C5H4)2Si(CH3)2}]ꢁ[Cr(CO)5CN]ꢂ (15)
PurpleÁ
/
red crystals (79% yield); m.p. (dec.) 90Á
/
92 8C; IR (CH2Cl2) n(CO) 2012 (w), 1972 (m), 1920
(vs, br), 1792 (w) cmꢂ1; n(CN) 2046 (m) cmꢂ1; H-
1
NMR (CD3COCD3) d 8.22Á7.64 (m, 5H, C6H5), 6.82
/
(s, 2H, C5H4), 6.75 (s, 2H, C5H4), 6.08 (s, 2H, C5H4),
5.44 (s, 2H, C5H4), 0.63 (s, 3H, SiCH3), 0.29 (s, 3H,
To a stirred, turbid solution of freshly prepared (in
situ) 3 (0.391 g, 0.475 mmol) dissolved in 50 ml of THF
SiCH3); MS m/e 443 [Mꢁꢂ
/
W(CO)5CNꢂ
/
CO], 415
at ꢂ
reaction mixture was slowly warmed to ꢂ
1 h, during which time the turbid red solution gradually
turned brownÁred. After being stirred at ꢂ80 to
50 8C for an additional 4 h, the resulting red solution
was evaporated in vacuo at ꢂ45 8C to dryness, and the
brownÁred residue was chromatographed on Al2O3 at
25 8C with petroleum etherÁCH2Cl2 (1:1) as the
eluant. A purpleÁred band was eluted and collected.
After vacuum removal of the solvent, the crude product
was recrystallized from petroleum etherÁCH2Cl2 (2:1)
solution at ꢂ80 8C to yield 0.264 g (79%, based on 3) of
15 as deep red crystals: m.p. (dec.) 122Á124 8C; IR
/
100 8C was added 0.136 g (0.565 mmol) of 4. The
[Mꢁꢂ
/
W(CO)5CNꢂ
/
2CO], 387 [Mꢁꢂ
/
W(CO)5CNꢂ
/
/
80 8C within
3CO], 350 [W(CO)5CNꢁ]. Anal. Calc. for C28H19O8N-
SiWFe2: C, 40.96; H, 2.33; N, 1.70. Found: C, 40.67; H,
2.61; N, 1.85%.
/
/
ꢂ
/
/
2.4. [Fe2(m-CO){m-C(C6H4CF3-
p)NCCr(CO)5}(CO)2{(h5-C5H4)2Si(CH3)2}] (12)
/
ꢂ
/
/
/
PurpleÁ
/
red crystals (80% yield); m.p. (dec.) 98Á
/
102 8C; IR (CH2Cl2) n(CO) 2039 (m), 1997 (s), 1951
/
1
(vs) 1798 (m) cmꢂ1; n(CN) 2050 (w) cmꢂ1; H-NMR
/
(CD3COCD3) d 7.56Á/7.16 (m, 4H, C6H4CF3), 6.52 (s,
/
4H, C5H4), 6.16 (s, 2H, C5H4), 5.60 (s, 2H, C5H4), 0.62
(s, 3H, SiCH3), 0.28 (s, 3H, SiCH3); MS m/e 757 [Mꢁ],
(CH2Cl2) n(CO) 2040 (vs), 2012 (m), 1966 (m), 1922 (vs),
1890 (m), 1849 (m) cmꢂ1; n(CN) 2090 (w) cmꢂ1; H-
1
511
[Mꢁꢂ
/
Cr(CO)5CNꢂ
/
2CO],
483
[Mꢁꢂ
/
NMR (CD3COCD3) d 8.37Á7.70 (m, 4H, C6H4CH3),
/
Cr(CO)5CNꢂ
/
3CO], 218 [Cr(CO)5CNꢁ]. Anal. Calc.
6.73 (s, 2H, C5H4), 6.70 (s, 2H, C5H4), 6.01 (s, 2H,
C5H4), 5.38 (s, 2H, C5H4), 2.56 (s, 3H, C6H4CH3), 0.59
for C29H18O8F3NSiCrFe2: C, 46.00; H, 2.40; N, 1.85.
Found: C, 45.75; H, 2.59; N, 1.99%.
(s, 3H, SiCH3), 0.25 (s, 3H, SiCH3); MS m/e 485 [Mꢁꢂ
/
Cr(CO)5CN], 457 [Mꢁꢂ
Cr(CO)5CNꢂ3CO], 218
/
Cr(CO)5CNꢂ
/
CO], 401 [Mꢁꢂ
/
2.5. [Fe2(m-CO){m-C(C6H4CF3-
p)NCMo(CO)5}(CO)2{(h5-C5H4)2Si(CH3)2}] (13)
/
[Cr(CO)5CNꢁ],
192
[Cr(CO)5ꢁ]. Anal. Calc. for C29H21O8NSiCrFe2: C,
49.53; H, 3.01; N, 1.99. Found: C, 49.54; H, 3.18; N,
2.16%.
PurpleÁ
/
red crystals (78% yield); m.p. (dec.) 92Á
/
94 8C; IR (CH2Cl2) n(CO) 2045 (m), 1998 (s), 1953
The following complexes were prepared by similar
reactions.
1
(vs, br), 1799 (m) cmꢂ1; n(CN) 2058 (w) cmꢂ1; H-
NMR (CD3COCD3) d 7.74Á
6.74 (s, 4H, C5H4), 5.59 (s, 4H, C5H4), 0.57 (s, 3H,
SiCH3), 0.30 (s, 3H, SiCH3); MS m/e 539 [Mꢁꢂ
Mo(CO)5CN], 511 [Mꢁꢂ
Mo(CO)5CNꢂCO], 482
[Mꢁꢂ [Mo(CO)5CNꢁ].
Mo(CO)5CNꢂ2CO], 262
/
7.54 (m, 4H, C6H4CF3),
2.8. [Fe2(m-CO)(m-CC6H4CH3-p)(CO)2{(h5-
C5H4)2Si(CH3)2}]ꢁ[Mo(CO)5CN]ꢂ (16)
/
/
/
/
/
Deep red crystals (78% yield); m.p. (dec.) 103Á
/
Anal. Calc. for C29H18O8F3NSiMoFe2: C, 43.48; H,
2.26; N, 1.75. Found: C, 43.19; H, 2.38; N, 1.99%.
105 8C; IR (CH2Cl2) n(CO) 2061 (s), 2043 (s), 2014
(s), 1930 (vs, br), 1852 (m), 1810 (m) cmꢂ1; n(CN) 2100
(w) cmꢂ1; 1H-NMR (CD3COCD3) d 8.37Á
7.70 (m, 4H,
/
2.6. [Fe2(m-CO){m-C(C6H5CF3-
p)NCW(CO)5}(CO)2{(h5-C5H4)2Si(CH3)2}] (14)
C6H4CH3), 6.71 (s, 4H, C5H4), 6.01 (s, 2H, C5H4), 5.38
(s, 2H, C5H4), 2.56 (s, 3H, C6H4CH3), 0.59 (s, 3H,
SiCH3), 0.26 (s, 3H, SiCH3); MS m/e 747 [Mꢁ], 485
PurpleÁ
/
red crystals (83% yield); m.p. (dec.) 90Á
/
[Mꢁꢂ
/
Mo(CO)5CN], 457 [Mꢁꢂ
/
Mo(CO)5CNꢂ
/
CO],
262 [Mo(CO)5CNꢁ]. Anal. Calc. for C29H21O8NSi-
92 8C; IR (CH2Cl2) n(CO) 2041 (m), 1996 (s), 1943

R. Wang et al. / Journal of Organometallic Chemistry 658 (2002) 214Á
/227
217
MoFe2: C, 46.62; H, 2.83; N, 1.87. Found: C, 46.30; H,
2.98; N, 1.98%.
[Mꢁꢂ
/
3CO], 485 [Mꢁꢂ
/
SCH3]. Anal. Calc. for
C24H24O3SFe2Si: C, 53.23; H, 4.54. Found: C, 53.09;
H, 4.70%.
2.9. [Fe2(m-CO)(m-CC6H4CH3-p)(CO)2{(h5-
C5H4)2Si(CH3)2}]ꢁ[W(CO)5CN]ꢂ (17)
2.12. Reaction of 15 with NaSC6H5 to give [Fe2(m-
CO){m-C(SC6H5)C6H4CH3-p}(CO)2{(h5-
C5H4)2Si(CH3)2}] (20)
Deep red crystals (76% yield); m.p. (dec.) 118Á
/
120 8C; IR (CH2Cl2) n(CO) 2056 (w), 2040 (s), 2012
(w), 1966 (m), 1917 (vs), 1853 (m) cmꢂ1; n(CN) 2096 (w)
As used for the reaction of 16 with NaSCH3, 15 (0.049
g, 0.070 mmol) was treated with 0.010 g (0.071 mmol) of
cmꢂ1
;
1H-NMR (CD3COCD3) d 8.37Á
/
7.70 (m, 4H,
C6H4CH3), 6.73 (s, 2H, C5H4), 6.71 (s, 2H, C5H4), 6.01
(s, 2H, C5H4), 5.38 (s, 2H, C5H4), 5.26 (m, 2H, CH2Cl2),
2.56 (s, 3H, C6H4CH3), 0.58 (s, 3H, SiCH3), 0.25 (s, 3H,
NaSC6H5 to yield 0.038 g (92%, based on 15) of purpleÁ
red crystalline 20 [8]: m.p. (dec.) 134Á135 8C; IR
(CH2Cl2) n(CO) 1984 (vs), 1951 (s), 1778 (s) cmꢂ1
1H-NMR (CD3COCD3) d 7.39Á
6.55 (m, 9H, C6H5ꢁ
/
/
;
SiCH3); MS m/e 835 [Mꢁ], 485 [Mꢁꢂ
/
W(CO)5CN], 457
W(CO)5CN], 350 [W(CO)5CNꢁ], 84 (CH2Cl2).
CH2Cl2: C, 39.26;
/
/
[Mꢁꢂ
/
C6H4CH3), 6.24 (s, 2H, C5H4), 5.64 (s, 2H, C5H4),
5.27 (s, 2H, C5H4), 5.21 (s, 2H, C5H4), 2.01 (s, 3H,
C6H4CH3), 0.63 (s, 3H, SiCH3), 0.52 (s, 3H, SiCH3); MS
Anal. Calc. for C29H21O8NSiWFe2×
/
H, 2.52; N, 1.52. Found: C, 39.80; H, 2.65; N, 1.85%.
m/e 594 [Mꢁ], 538 [Mꢁꢂ
/
2CO], 485 [Mꢁꢂ
SC6H5].
/
2.10. [Fe2(m-CO)(m-CC6H4CH3-p)(CO)2{(h5-
C5H4)2Si(CH3)2}]ꢁ[Fe(CO)4CN]ꢂ (18)
Anal. Calc. for C29H26O3SFe2Si: C, 58.60; H, 4.41.
Found: C, 58.36; H, 4.62%.
Deep red crystals (58% yield); m.p. (dec.) 207Á
/
2.13. Reaction of 15 with NaSC6H4CH3-p to give
[Fe2(m-CO){m-C(SC6H5CH3-p)C6H4CH3-
p}(CO)2{(h5-C5H4)2Si(CH3)2}] (21)
209 8C; IR (CH2Cl2) n(CO) 2050 (w), 2038 (vs), 2012
(m), 1929 (vs), 1849 (m) cmꢂ1; n(CN) 2098 (m) cmꢂ1
;
1H-NMR (CD3COCD3)
d
8.36Á7.64 (m, 4H,
/
C6H4CH3), 6.71 (s, 4H, C5H4), 6.01 (s, 2H, C5H4),
5.44 (s, 2H, C5H4), 2.56 (s, 3H, C6H4CH3), 0.53 (s, 3H,
Using the same procedures for the reaction of 16 with
NaSCH3, compound 15 (0.070 g, 0.100 mmol) was
treated with NaSC6H4CH3-p (0.015 g, 0.100 mmol) to
SiCH3), 0.30 (s, 3H, SiCH3); MS m/e 485 [Mꢁꢂ
/
Fe(CO)4CN], 457 [Mꢁꢂ
/
Fe(CO)4ꢂ
/
CO], 401 [Mꢁꢂ
/
give 0.054 g (90%, based on 15) of purpleÁ
21 [8]: m.p. (dec.) 109Á110 8C; IR (CH2Cl2) n(CO) 1983
(vs), 1951 (m), 1773 (s) cmꢂ1; H-NMR (CD3COCD3)
d 7.33Á6.56 (m, 8H, 2C6H4CH3), 6.22 (s, 2H, C5H4),
/red crystals of
Fe(CO)4CNꢂ
/
3CO], 194 [Fe(CO)4CNꢁ]. Anal. Calc.
/
1
for C28H21O7NSiFe3: C, 47.83; H, 3.02; N, 1.99. Found:
C, 47.62; H, 3.27; N, 2.09%.
/
5.65 (s, 2H, C5H4), 5.26 (s, 2H, C5H4), 5.23 (s, 2H,
C5H4), 2.25(s, 3H, SC6H4CH3), 2.03 (s, 3H, C6H4CH3),
0.62 (s, 3H, SiCH3), 0.50 (s, 3H, SiCH3); MS m/e 608
2.11. Reaction of 16 with NaSCH3 to give [Fe2(m-
CO){m-C(SCH3)C6H4CH3-p}(CO)2{(h5-
C5H4)2Si(CH3)2}] (19)
[Mꢁ], 580 [Mꢁꢂ
/
CO], 524 [Mꢁꢂ
/
3CO], 485 [Mꢁꢂ
/
SC6H4CH3]. Anal. Calc. for C30H28O3SFe2Si: C,
59.22; H, 4.64. Found: C, 58.87; H, 4.87%.
To a brownÁ
in 50 ml of THF at ꢂ
mmol) of NaSCH3. The reaction solution was stirred at
78 to ꢂ35 8C for 5 h, during which time the brownÁ
/
red solution of 16 (0.120 g, 0.161 mmol)
/
78 8C was added 0.012 g (0.171
2.14. Reaction of 1 with NaN(SiMe3)2 to give [Fe2(m-
CO)2(CO)NCC6H5{(h5-C5H4)2Si(CH3)2}] (22)
ꢂ
/
/
/
red solution gradually turned purple red. After evapora-
tion of the solvent under vacuum, the residue was
To 0.400 g (0.494 mmol) of freshly prepared 1
chromatographed on Al2O3 at ꢂ
/
25 8C with petroleum
dissolved in 60 ml of THF at ꢂ
0.106 g (0.581 mmol) of NaN(SiMe3)2. The reaction
mixture was stirred at ꢂ80 8C for 1 h, during which
time the turbid solution turned deep-red. After stirring
at ꢂ70 to ꢂ50 8C for additional 4 h, the resulting
solution was evaporated in vacuo at ꢂ45 8C to dryness
and the dark red residue was chromatographed on
Al2O3 at ꢂ25 8C with petroleum etherÁCH2Cl2 (10:1)
/
90 8C was added
etherÁCH2Cl2 (10:1) as the eluant. A purpleÁ
/
/red band
was eluted and collected. The solvent was removed in
vacuo, and the residue was recrystallized from petro-
/
leum etherÁ
0.077 g (91% based on 16) of 19 [8] as purpleÁ
crystals: m.p. (dec.) 128Á130 8C; IR (CH2Cl2) n(CO)
1982 (vs), 1949 (s), 1774 vs) cmꢂ1 1H-NMR
(CD3COCD3) d 7.35Á6.83 (dd, 4H, C6H4CH3), 6.13
/
CH2Cl2 (15:1) solution at ꢂ
/
80 8C to yield
/
/
/red
/
/
;
/
/
/
as the eluant. The red band was eluted and collected.
After vacuum removal of the solvent, the residue was
(s, 2H, C5H4), 5.56 (s, 2H, C5H4), 5.22 (s, 2H, C5H4),
5.05 (s, 2H, C5H4), 2.19 (s, 3H, SCH3), 2.03 (s, 3H,
C6H4CH3), 0.61 (s, 3H, SiCH3), 0.47 (s, 3H, SiCH3); MS
recrystallized from petroleum etherÁ
tion at ꢂ80 8C to yield 0.115 g (48%, based on 1) of red
crystals of 22: m.p. (dec.) 122Á123 8C; IR
/
CH2Cl2 (10:1) solu-
/
m/e 532 [Mꢁ], 504 [Mꢁꢂ
/
CO], 476 [Mꢁꢂ
/
2CO], 448
/

218
R. Wang et al. / Journal of Organometallic Chemistry 658 (2002) 214Á227
/
(CH2Cl2)n(CO) 1945 (s), 1795 (vs, br) cmꢂ1; n(CN)
ꢂ
/
50 8C for 5 h, during which time the turbid red
solution gradually turned brownÁred. After vacuum
removal of the solvent, the brownÁred residue was
chromatographed on Al2O3 at ꢂ25 8C with petroleum
etherÁCH2Cl2 (5:1) as the eluant. A purpleÁred band
1
1993 cmꢂ1; H-NMR (CD3COCD3) d 7.56Á
/
7.26 (m,
/
5H, C6H5), 5.57 (s, 2H, C5H4), 5.47 (s, 2H, C5H4), 5.15
(s, 2H, C5H4), 5.02 (s, 2H, C5H4), 0.26 (s, 6H, SiCH3);
/
/
MS m/e 485 [Mꢁ], 382 [Mꢁꢂ
/
C6H5CN], 354 [Mꢁꢂ
/
/
/
C6H5CNꢂ
/
CO], 298 [Mꢁꢂ
Calc. for C22H19O3NSiFe2: C, 54.46; H, 3.95, N, 2.89.
/
C6H5CNꢂ3CO]. Anal.
/
was eluted and collected. The solvent was removed in
vacuo, and the crude product was recrystallized from
Found: C, 54.66, H, 4.02, N, 2.88%.
petroleum etherÁ
/
CH2Cl2 (5:1) solution at ꢂ
/
80 8C to
yield 0.082 g (37%, based on 1) of purpleÁ
/
red crystals of
1
23, which was identified by its m.p., and IR, H-NMR
and mass spectra.
2.15. Reaction of 1 with 7 to give [Fe2(m-CO){m-
C(H)C6H5}(CO)2{(h5-C5H4)2Si(CH3)2}] (23)
To a stirred, turbid red solution of 1 (0.400g, 0.494
2.18. Reaction of 2 with 8 to give 24
mmol) in 50 ml of THF at ꢂ
(0.581 mmol) of 7. The reaction mixture was stirred at
100 to ꢂ50 8C for 5 h, during which time the turbid
red solution gradually turned brown red. The resulting
solution was evaporated in vacuo at ꢂ40 8C to dryness,
and the dark-red residue was chromatographed on
Al2O3 at ꢂ25 8C with petroleum etherÁCH2Cl2 (5:1)
as the eluant. A purpleÁred band was eluted and
collected. The solvent was removed in vacuo, and the
residue was recrystallized from petroleum etherÁCH2Cl2
(5:1) solution at ꢂ80 8C to yield 0.120 g (51%, based on
1) of purpleÁred crystals of 23: m.p. (dec.) 228Á230 8C;
IR (CH2Cl2) n(CO) 1971 (vs), 1938 (s), 1775 (vs) cmꢂ1
1H-NMR (CD3COCD3) d 12.22 (s, 1H, m-CH), 7.37Á
/
100 8C was added 0.126 g
Compound 2 (0.389 g, 0.447 mmol) was reacted with
8 (0.340 g, 0.447 mmol) as described for the reaction of 1
with 8 to produce 0.090 g (38%, based on 2) of purpleÁ
red crystals of 24, which was identified by its m.p., IR,
1
and H-NMR and mass spectra.
ꢂ
/
/
/
/
/
/
/
2.19. Reaction of 3 with 8 to give [Fe2(m-CO){m-
C(H)C6H4CH3-p}(CO)2{(h5-C5H4)2Si(CH3)2}] (25)
/
/
/
/
As used in the reaction of 1 with 8, 0.313 g (0.380
mmol) of 3 was treated with 8 (0.289 g, 0.380 mmol) to
;
/
give 0.087 g (47%, based on 3) of 25 as purpleÁ
crystals: m.p. (dec.) 220Á222 8C; IR (CH2Cl2) n(CO)
1971 (s), 1939 (m), 1770 (m) cmꢂ1 1H-NMR
(CD3COCD3) d 12.23 (s, 1H, m-CH), 7.26Á6.93 (m,
/
red
7.01 (m, 5H, C6H5), 5.70 (s, 2H, C5H4), 5.62 (s, 2H,
C5H4), 5.35 (s, 2H, C5H4), 5.12 (s, 2H, C5H4), 0.58 (s,
3H, SiCH3), 0.35 (s, 3H, SiCH3); MS m/e 472 [Mꢁ], 444
/
;
/
[Mꢁꢂ
/
CO], 416 [Mꢁꢂ
/
2CO], 388 [Mꢁꢂ
/3CO]. Anal.
4H, C6H4CH3), 5.63 (s, 2H, C5H4), 5.57 (s, 2H, C5H4),
5.30 (s, 2H, C5H4), 5.26 (m, 3H, CH2Cl2), 5.09 (s, 2H,
C5H4), 2.23 (s, 3H, C6H4CH3), 0.59 (s, 3H, SiCH3), 0.34
Calc. for C22H20O3SiFe2: C, 55.96; H, 4.27. Found: C,
55.70; H, 4.28%.
(s, 3H, SiCH3); MS m/e 557 [Mꢁ], 529 [Mꢁꢂ
/
CO], 501
2.16. Reaction of 2 with 7 to give [Fe2(m-CO){m-
C(H)C6H4CF3-p}(CO)2{(h5-C5H4)2Si(CH3)2}] (24)
[Mꢁꢂ
/
2CO], 473 [Mꢁꢂ
/
3CO], 84 [CH2Cl2ꢁ]. Anal.
Calc. for C23H22O3SiFe2 1.5CH2Cl2: C, 47.95; H, 4.10.
Found: C, 47.77; H, 4.22%.
Similar to the reaction of 1 with 7, 2 (0.389 g, 0.447
mmol) was treated with 7 (0.112 g, 0.513 mmol) to
X-ray crystal structure determinations of complexes
14, 15, 22, and 23. The single crystals of 14, 15, 22, and
23 suitable for X-ray diffraction study were obtained by
afford 0.110 g (46%, based on 2) of purpleÁ
line 24: m.p. (dec.) 212Á214 8C; IR (CH2Cl2) n(CO)
1975 (s), 1944 (m), 1781 (m) cmꢂ1 1H-NMR
(CD3COCD3) d 12.04 (s, 1H, m-CH), 7.60Á7.36 (m,
/
red crystal-
/
recrystallization from petroleum etherÁ
/
CH2Cl2 solution
;
at ꢂ80 8C. Single crystals were mounted on a glass
/
/
fibre and sealed with epoxy glue. The X-ray diffraction
intensity data were collected with a Rigaku AFC7R or
Brock Smart diffractometer.
4H, C6H4CF3), 5.69 (s, 2H, C5H4), 5.60 (s, 2H, C5H4),
5.35 (s, 2H, C5H4), 5.25 (m, 1H, CH2Cl2), 5.12 (s, 2H,
C5H4), 0.59 (s, 3H, SiCH3), 0.36 (s, 3H, SiCH3); MS m/e
The structures of 14, 15, 22, and 23 were solved by
direct methods and expanded using Fourier techniques.
For 14, some non-hydrogen atoms were refined aniso-
tropically, while the rest were refined isotropically. For
15, 22, and 23, the non-hydrogen atoms were refined
anisotropically. For the four complexes the hydrogen
atoms were included but not refined. The final cycle of
full-matrix least-squares refinement gave agreement
512 [Mꢁꢂ
/
CO], 484 [Mꢁꢂ
/
2CO], 456 [Mꢁꢂ
3CO], 84
/
[CH2Cl2ꢁ]. Anal. Calc. for C23H19O3F3SiFe2 0.5CH2Cl2:
C, 48.47; H, 3.46. Found: C, 48.60; H, 4.00%.
2.17. Reaction of 1 with [(PPh3)2N][Cr(CO)4NO] (8)
to give 23
To a stirred solution of 1 (0.400 g, 0.494 mmol) in 50
factors of Rꢀ
and Rwꢀ0.062 for 15, Rꢀ
and Rꢀ0.0429 and Rwꢀ0.0514 for 23.
/
0.050 and Rwꢀ
/
0.062 for 14, Rꢀ
/
0.061
ml of THF at ꢂ
/
100 8C was added 0.340 g (0.494 mmol)
/
/
0.046 and Rwꢀ
/0.047 for 22,
of 8. The reaction mixture was stirred at ꢂ
/
100 to
/
/

R. Wang et al. / Journal of Organometallic Chemistry 658 (2002) 214Á
/227
219
The details of the crystallographic data and the
procedures used for data collection and reduction
information for 14, 15, 22, and 23 are given in Table
1. Selected bond lengths and angles are listed in Tables 2
and 3. The atomic coordinates and Biso/Beq, anisotropic
displacement parameters, complete bond lengths and
angles, least-squares planes for 14, 15, 22, and 23 are
given in the supporting information. The molecular
be obtained in somewhat lower yield (58%) from the
reaction (Eq. (2)) of 3 with Na[Fe(CO)4CN] (7).
structures of 14, 15, 22, and 23 are given in Figs. 1Á4,
/
respectively.
ð2Þ
3. Results and discussion
The highly electrophilic dimethylsilane-bridged catio-
nic carbyne complexes [Fe2(m-CO){m-CAr}(CO)2{(h5-
C5H4)2Si(CH3)2}]BBr4 should be highly reactive toward
nucleophilic carbonylmetal anions, which is indeed the
case. The freshly prepared (in situ) complex [Fe2(m-
On the basis of elemental analyses and spectroscopic
evidence, as well as X-ray crystallography, product 14 is
formulated as diiron bridging carbene complexes with a
CO)(m-CC6H5)(CO)2{(h5-C5H4)2Si(CH3)2}]BBr4
(1)
15% molar excess of anionic
carbonylmetal compounds Na[M(CO)5CN] (4, MꢀCr;
5, MꢀMo; 6, MꢀW) in THF at low temperature (ꢂ90
to ꢂ50 8C) for 4Á5 h. After work-up as described in the
M(CO)5CN (MꢀW) moiety bonded to bridging car-
/
was treated with about 10Á
/
bene carbon through the N atom of the CN group, while
product 15 as novel cationic bridging carbyne complexes
/
with a [M(CO)nCN]ꢂ (Mꢀ
/Cr) anion as the counter-
/
/
/
/
/
ion, respectively. Complexes 9Á13 are assigned to
/
Section 2, the novel bridging phenyl(pentacarbonylcya-
similar structures since their spectral data and polarity
are similar to those of complex 14. Likely, complexes
nometal)carbene complexes [Fe2(m-CO){m-C(C6H5)
NCM(CO)5}(CO)2{(h5-C5H4)2Si(CH3)2}] (9Á
/
11) (Eq.
84% yields. Com-
[Fe2(m-CO)(m-CC6H4CF3-p)(CO)2{(h5-C5H4)2-
Si(CH3)2}]BBr4 (2) reacts similarly with 4Á6 under the
16Á18 are assigned to a similar structure since its
/
(1)) were obtained in 79Á
/
spectral data and polarity are similar to those of
complex 15.
plex
/
Complexes 9Á
solvents but slightly soluble in non-polar solvents, while
complexes 15Á18 are only sparingly soluble in polar
solvents, such as THF and CH2Cl2. The isolation of 9Á
14 was by chromatography on an alumina column with
a 10:1 of petroleum etherÁCH2Cl2 as the eluant and the
further purification was recrystallized from a 15:1 of
petroleum etherÁCH2Cl2 solution, while for 15Á18, the
chromatography isolation was with used an 1:1 of
petroleum etherÁCH2Cl2 as the eluant and the recrys-
tallization was from a 2:1 of petroleum etherÁCH2Cl2
solution, indicating larger polarity for 15Á18 than for
9Á14. Complexes 9Á14 and 15Á18 are sensitive to air
/14 are readily soluble in polar organic
same conditions to give corresponding bridging ar-
yl(pentacarbonylcyanometal)carbene complexes [Fe2(m-
CO){m-C(C6H4CF3 -p)NCM(CO)5}(CO)2{(h5-C5H4)2-
/
/
Si(CH3)2}] (12Á
/
14) (Eq. (1)) in similar yields (78Á
/83%).
/
/
/
/
ð1Þ
/
/
/
/
/
and temperature in solution but relatively stable in the
solid states.
In contrast to the reactions of cationic 1 and 2,
cationic carbyne complex [Fe2(m-CO)(m-CC6H4CH3-
p)(CO)2{(h5-C5H4)2Si(CH3)2}]BBr4 (3), where the aryl
substituent on the m-carbyne carbon is a p-tolyl group,
The IR and 1H-NMR spectra of complexes 9Á
/
14 and
18 are consistent with their structures shown in Eqs.
(1) and (2), respectively. The IR spectra of 15Á18 in the
n(CO) region shows that the absorption band of the
bridging CO group appears at ca. 1810Á
1853 cmꢂ1 for
15Á
18, similar to complex 3 (at 1857 cmꢂ1) but very
different from complexes 9Á14 (at 1706Á
1799 cmꢂ1).
The characteristic n(CN) stretching vibration occurs at
ca. 2043Á 14 but at ca. 2090Á2100
2058 cmꢂ1 for 9Á
cmꢂ1 for 15Á
18, shifting to high vibration frequency by
about 45 cmꢂ1. The lower n(CN) vibration frequency
15Á
/
/
reacts with carbonylmetal anions 4Á6 under the
/
/
same conditions to give not analogous bridging
carbene complexes but rather novel cationic carbyne
/
complexes
C5H4)2Si(CH3)2}]ꢁ[M(CO)5CN]ꢂ (15Á
76Á79% isolated yields. Analogous cationic bridging
[Fe2(m-CO)(m-CC6H4CH3-p)(CO)2{(h5-
/
/
/
17) (Eq. (2)) in
/
/
/
/
carbyne complex [Fe2(m-CO)(m-CC6H4CH3-p)(CO)2-
/
{(h5-C5H4)2Si(CH3)2}]ꢁ[Fe(CO)4CN]ꢂ (18) can also

220
R. Wang et al. / Journal of Organometallic Chemistry 658 (2002) 214Á227
/
Table 1
Crystal data and experimental details for complexes 14, 15, 22, and 23
14
15 CH2Cl2
22
23
Formula
Formula weight
Space group
C
889.09
29H18O8NF3SiWFe2
C30H23O8NCl2SiCrFe2 C22H19O3NFe2Si
788.20
C22H20O3SiFe2
472.17
P212121
8.4357(9)
12.4388(14)
19.011(2)
90
485.18
P21/m (number 11)
11.523(3)
11.028(3)
P21/n (number 14)
9.474(3)
15.391(3)
P21/n (number 14)
10.856(5)
14.992(4)
˚
a (A)
˚
b (A)
˚
c (A)
12.228(3)
23.028(4)
13.015(4)
a (8)
b (8)
g (8)
V (A )
Z
91.37(2)
90.39(2)
93.34(3)
90
90
3
˚
1553.4(6)
2
3357(1)
4
2114(1)
4
1994.8(4)
4
1.572
Dcalc (g cmꢂ3
F(000)
)
1.901
860.00
47.24
1.559
1592.00
14.12
1.524
992.00
14.50
968
15.35
m (MoÁ
/
Ka) (cmꢂ1
)
˚
˚
Radiation (monochromated in incident
beam)
MoÁ
/
Ka (lꢀ0.71069
MoÁ
/
Ka (lꢀ0.71069 A) MoÁ
/Ka (lꢀ0.71069 A) MoÁKa (lꢀ0.71073
/
˚
A)
˚
A)
Diffractometer
Temperature (8C)
Rigaku AFC7R
20
Rigaku AFC7R
20
Rigaku AFC7R
20
Brock Smart
20
Orientation reflections: number; range (2u) 20; 14.5Á
/
21.1
19; 18.7Á/21.5
23; 14.4Á/19.3
2.95Á/28.82
(8)
Scan method
v Á
/
2u
v Á/2u
v Á/2u
v Á/2u
Data coll. range, 2u (8)
Number of unique data, total with
I ꢀ3.00s(I)
5Á55
3675, 2565
/
5Á50
6155, 406
/
5Á51
/
3.92Á
/
56.6
3948, 2163
(I ꢀ2.50s(I))
262
4643, 4643
(I ꢀ2.00s(I))
311
Number of parameters refined
215
406
Corrected factors, max/min
a
0.9512Á
/0.9999
0.7151Á
/
1.0000
0.8477Á
/1.0000
0.8928Á1.0000
0.046
/
R
0.050
0.062
1.88
0.061
0.062
1.80
0.046
0.047
1.25
b
Rw
0.0526
0.713
0.003
c
Quality of fit indicator
Max shift/estimated S.D. final cycle
0.00
2.08
0.00
1.03
0.00
0.40
ꢂ3
˚
Largest peak (e A
)
0.788
ꢂ0.320
ꢂ3
˚
Minimum peak (e A
)
ꢂ1.43
ꢂ0.47
ꢂ0.39
a
RꢀajFojꢂjFcj/ajFoj.
b
c
Rwꢀja w(jFojꢂjFcj)2/a wjFoj2]1/2; wꢀ1/s2(jFoj).
Quality-of-fitꢀ[a w(jFojꢂjFcj)2/(NobsꢂNparameters)]1/2
.
for 9Á
(MꢀCr, Mo, W) moiety to the m-carbene carbon
through the CN group leading to a weakening of the
CÃN bond to a certain extent in 9Á14, as compared with
that of complexes 15Á18. The H-NMR spectra of 15Á
18 showed that the signals attributed to the cyclopenta-
dienyl rings at 6.73Á5.38 ppm which are different from
those of 9Á14 (at 6.91Á5.44 ppm) but are similar to that
of parent cationic carbyne complex 3 (at 6.78Á5.42
ppm). These suggest that the structures of 15Á18 are
quite different from those of 9Á14 and somewhat like
parent complex 3, a fact that is further confirmed by X-
ray diffraction studies of 14 and 15. The results of the X-
ray diffraction work for both complexes are summarized
in Table 1, and their structures are shown in Figs. 1 and
2, respectively.
/
14 may be due to the bonding of the M(CO)5CN
CH3OC6H4 and an OC2H5 group in the latter. The
structural features of the principal portion of [Fe2(m-
CO){m-C(OC2H5)C6H4OCH3-p}(CO)2{(h5-C5H4)2Si-
(CH3)2}] of 14 are very similar to those of the same unit
/
/
/
1
/
/
in
complex
[Fe2(m-CO){m-C(OC2H5)C6H4OCH3-
p}(CO)2{(h5-C5H4)2Si(CH3)2}], as illustrated by the
following parameters (the value for 14 is followed by
the same parameters for [Fe2(m-CO){m-C(OC2H5)-
/
/
/
/
C6H4OCH3-p}(CO)2{(h5-C5H4)2Si(CH3)2}]):
FeÃ
/
Fe
˚
/
(2.502(3), 2.503(6) A), average FeÃ
/
C(10) (1.914, 1.885
˚
˚
/
A), average FeÃ
/
C(Cp) (2.117, 2.115 A), C(1)Ã
/
C(2)
˚
(1.51(1), 1.49(3) A), FeÃ
/
C(1)Ã
/
Fe (76.6(4)8, 75.4(9)8),
FeÃC(10)ÃFe (81.6(5)8, 82(1)8). The structure of
/
/
W(CO)5CN moiety bonded to the m-carbene carbon is
essentially the same as that in analogous complex
[Fe2(m-CO){m-C(C6H4CH3-p)NCW(CO)5}(CO)2(h5-
The structure of 14 resembles that of bridging
alkoxycarbene complex [Fe2(m-CO){m-C(OC2H5)C6
H4OCH3-p}(CO)2{(h5-C5H4)2Si(CH3)2}] [12] except
that the substituents on the m-carbene carbon are a p-
CF3C6H4 and a W(CO)5CN group in 14 but a p-
C5H5)2] [7]. The two CÃ
/
N bond lengths in 14 are very
˚
different. C(18)ÃN has a bond length of 1.15(1) A,
/
which indicates high triple-bond character and is
essentially the same as the corresponding distance found
in [Fe2(m-CO){m-C(C6H4CH3-p)NCW(CO)5}(CO)2(h5-

R. Wang et al. / Journal of Organometallic Chemistry 658 (2002) 214Á
/227
221
Table 2
Selected bond lengths (A) and angles (8) for complexes 14 and 23
a
a
˚
14
23
14
23
Bond lengths
FeÃFe
FeÃC(1)
2.502(3)
2.019(9)
2.5150(9)
C(9)ÃO(3)
C(1)ÃN
C(1)ÃC(2)
NÃC(18)
C(18)ÃW
SiÃC(17)
SiÃC(18)
SiÃC(23)
SiÃC(24)
Fe(1)ÃC(Cp) (av)
Fe(2)ÃC(Cp) (av)
1.170(4)
1.453(6)
1.43(1)
1.51(1)
1.15(1)
2.13(1)
1.877(9)
Fe(1)ÃC(1)
Fe(2)ÃC(1)
FeÃC(10)
Fe(1)ÃC(10)
Fe(2)ÃC(10)
C(10)ÃO(2)
Fe(1)ÃC(8)
C(8)ÃO(1)
Fe(2)ÃC(9)
1.996(5)
1.997(5)
1.914(9)
1.913(5)
1.906(5)
1.181(5)
1.700(5)
1.178(5)
1.689(5)
1.863(5)
1.866(5)
1.849(5)
1.852(4)
2.107
1.18(1)
1.780(9)
1.11(1)
1.87(1)
1.86(1)
2.117
2.117
2.115
Bond angles
Fe(1)ÃFe(2)ÃC(1)
FeÃC(1)ÃFe
Fe(2)ÃFe(1)ÃC(1)
Fe(1)ÃFe(2)ÃC(10)
FeÃC(10)ÃFe
50.93(15)
78.08(19)
50.98(15)
48.92(14)
82.4(2)
C(1)ÃNÃC(18)
NÃC(18)ÃW
166.0(1)
178.2(10)
122.6(5)
76.6(4)
FeÃC(1)ÃC(2)
Fe(1)ÃC(1)ÃC(2)
Fe(2)ÃC(1)ÃC(2)
FeÃC(8)ÃO(1)
Fe(1)ÃC(8)ÃO(1)
FeÃC(10)ÃO(2)
Fe(2)ÃC(9)ÃO(3)
FeÃC(17)ÃSi
130.3(4)
126.2(3)
81.6(5)
51.7(2)
49.2(2)
Fe*ÃFeÃC(1)
173.4(8)
139.2(2)
119.8(4)
Fe*ÃFeÃC(10)
Fe(2)ÃFe(1)ÃC(10)
C(1)ÃFeÃC(10)
C(1)ÃFe(1)ÃC(10)
C(1)ÃFe(2)ÃC(10)
Fe(1)ÃC(10)ÃO(2)
Fe(2)ÃC(10)ÃO(2)
FeÃC(1)ÃN
173.8(4)
175.9(4)
48.68(16)
97.6(3)
97.3(2)
97.5(2)
Fe(1)ÃC(17)ÃSi
Fe(2)ÃC(18)ÃSi
C(17)ÃSiÃC(18)
120.5(2)
119.5(2)
106.4(2)
137.9(4)
139.7(4)
116.7(5)
a
Estimated S.D. in the least significant figure are given in parentheses.
˚
˚
˚
C5H5)2] (C(23)Ã
/
N 1.15(2) A) [7]. The other is C(1)Ã
/
N
A), shorter Fe-m-C bonds (Fe(1)Ã
/
C(1)ꢀ
1.83(1) A), and shorter C(1)Ã
(1.44(1) A) but is longer FeÃC(10) bond (1.94(1) A) and
larger Fe-m-C(1)ÃFe angle (85.8(4)8) in 15, as compared
/
1.83(1) A,
˚
˚
with the bond length of 1.43 (1) A, which is between the
normal CÃN and CÄN distances and slightly shorter
than the corresponding CÃ distance in com-
Fe(2)Ã
/
C(1)ꢀ
/
/
C(2) bond
˚
˚
/
/
/
/
N
/
plexes [Fe2(m-CO){m-C(C6H4CH3-p)NCW(CO)5}(CO)2-
with 14. The Fe-m-C(1) distances in 15 not only are
5
˚
˚
much shorter than that found (2.019(9) A) in 14, but
(h -C5H5)2] (1.47(2) A) and [WÃ
/
N(ButCMe2(Me)-
˚
(NBut){N(But)CMeÄ
The shorter WÃ
its high double-bond character and is the same as the
/
CMe2}] (1.438Á
/
1.521 A) [13].
also significantly shorter than the FeÄCcarbene bond
in carbene complexes [Fe{C(OC2H5)C6H4CH3-o}-
˚
(C10H16)(CO)2] (1.915(15) A) [14] and [Fe{C(OC2H5)-
/
˚
/
C(18) distance (2.13(1) A) in 14 signifies
˚
C6H4CH3-o}(C6H8)(CO)2] (1.89(2) A) [15]. In the di-
corresponding distance in [Fe2(m-CO){m-C(C6H4CH3-
p)NCW(CO)5}(CO)2(h -C5H5)2] (2.13(2) A) [7]. The
C(1), N, C(18), and W atoms are coplanar with a
5
˚
and trimetal bridging carbyne complexes [MoFe(m-
CC6H4CH3-p)(CO)6(h5-C5H5)] [16a] and [CrReFe(m-
CC6H4CH3-p)(CO)12] [16b], the Fe-m-C distances,
C(1)Ã
angle of 178.2(10)8, indicating that the C(1)Ã
C(28)ÃW fragment is almost linear; thus C(1), N,
C(28), and W atoms form a conjugate chain.
/
NÃ
/
C(18) angle of 166(1)8 and a NÃ
/
C(18)Ã
/
W
˚
/
NÃ
/
2.008(5) and 1.872(8) A, respectively, are longer than
/
those in 15. These data strongly suggest that both Fe-m-
C(1) linkages in 15 are a double bond. Moreover, the
The X-ray study of 15 showed that its structure is
formed by complex cations [Fe2(m-CO)(m-CC6H4CH3-
p)(CO)2{(h5-C5H4)2Si(CH3)2}]ꢁ and complex anions
[Cr(CO)5CN]ꢂ; the anion being directed towards
the cation, as shown in Fig. 2. The structure of the
cationic [Fe2(m-CO)(m-CC6H4CH3-p)(CO)2{(h5-C5H4)2-
Si(CH3)2}]ꢁ fragment is very close to that of the similar
shorter C(1)Ã
/
C(2) bond length in 15, which is inter-
mediate between CÃ
/
C single and CÄC double bond
/
distances, suggests some p-bond character between the
C(1) atom and C(2) atom of the benzene ring in 15.
The molecular structure of 15 shows that in the
direction of the cationic fragment [Fe2(m-CO)(m-
CC6H4CH3-p)(CO)2{(h5-C5H4)2Si(CH3)2}]ꢁ, an anio-
nic fragment of [Cr(CO)5CN]ꢂ was located. The
[Cr(CO)5CN]ꢂ anion is a octahedral structure with
unit
Si(CH3)2}] in 14. An apparent difference in the struc-
tures of 14 and 15 is the shorter FeÃFe bond (2.495(2)
[Fe2(m-CO)(m-C(C6H4CF3-p)(CO)2{(h5-C5H4)2-
/
the CO groups almost linear (178]
/
CrÃ
/
CÃ
/
O]1768) in
/

222
R. Wang et al. / Journal of Organometallic Chemistry 658 (2002) 214Á
/227
Table 3
a
a
˚
Selected bond lengths (A) and angles (8) for complexes 15 and 22
Complex 15
Bond lengths
Fe(1)ÃFe(2)
Fe(1)ÃC(1)
Fe(2)ÃC(1)
Fe(1)ÃC(10)
Fe(2)ÃC(10)
C(10)ÃO(2)
Fe(1)ÃC(8)
C(8)ÃO(1)
2.495(2)
1.83(1)
1.83(1)
1.94(1)
1.95(1)
1.16(1)
1.73(1)
1.18(1)
Fe(2)ÃC(9)
C(9)ÃO(3)
C(1)ÃC(2)
SiÃC(17)
SiÃC(18)
SiÃC(23)
SiÃC(24)
1.75(1)
1.15(1)
1.44(1)
1.86(1)
1.86(1)
1.85(1)
1.85(1)
2.106
Fe(2)ÃC(Cp) (av)
CrÃC(31)
C(31)ÃN
CrÃC(26)
CrÃC(27)
CrÃC(28)
CrÃC(29)
CrÃC(30)
2.110
1.92(2)
1.13(1)
1.85(1)
2.02(1)
1.92(1)
1.89(1)
1.90(2)
Fe(1)ÃC(Cp) (av)
Bond angles
Fe(1)ÃFe(2)ÃC(1)
Fe(1)ÃC(1)ÃFe(2)
Fe(2)ÃFe(1)ÃC(1)
Fe(1)ÃFe(2)ÃC(10)
Fe(1)ÃC(10)ÃFe(2)
Fe(2)ÃFe(1)ÃC(10)
C(1)ÃFe(1)ÃC(10)
C(1)ÃFe(2)ÃC(10)
47.0(3)
85.8(4)
47.2(3)
50.0(3)
79.7(4)
50.3(3)
94.1(4)
93.7(5)
Fe(1)ÃC(10)ÃO(2)
Fe(2)ÃC(10)ÃO(2)
Fe(1)ÃC(1)ÃC(2)
Fe(2)ÃC(1)ÃC(2)
Fe(1)ÃC(17)ÃSi
Fe(2)ÃC(18)ÃSi
Fe(2)ÃFe(1)ÃC(8)
C(1)ÃFe(1)ÃC(8)
141.4(9)
138.9(9)
136.1(9)
137.9(9)
121.7(5)
121.5(5)
105.0(4)
89.2(5)
Fe(1)ÃFe(2)ÃC(9)
C(1)ÃFe(2)ÃC(9)
CrÃC(31)ÃN
CrÃC(26)ÃO(4)
CrÃC(27)ÃO(5)
CrÃC(28)ÃO(6)
CrÃC(29)ÃO(7)
CrÃC(30)ÃO(8)
104.5(3)
88.3(5)
175.0(1)
178.0(1)
176.0(1)
178.0(1)
178.0(1)
177.0(1)
Complex 22
Bond lengths
Fe(1)ÃFe(2)
Fe(1)ÃC(9)
Fe(2)ÃC(9)
Fe(1)ÃC(10)
Fe(2)ÃC(10)
C(9)ÃO(2)
2.510(1)
1.933(6)
1.905(7)
1.946(6)
1.891(6)
1.173(7)
C(10)ÃO(3)
Fe(1)ÃC(8)
C(8)ÃO(1)
SiÃC(17)
1.183(7)
1.733(7)
1.155(7)
1.872(6)
1.869(6)
1.858(7)
SiÃC(24)
Fe(2)ÃN
NÃC(1)
C(1)ÃC(2)
Fe(1)ÃC(Cp) (av)
Fe(2)ÃC(Cp) (av)
1.857(7)
1.894(5)
1.134(7)
1.435(9)
2.1334
SiÃC(18)
SiÃC(23)
2.1082
Bond angles
Fe(1)ÃFe(2)ÃC(9)
Fe(1)ÃC(9)ÃFe(2)
Fe(2)ÃFe(1)ÃC(9)
Fe(1)ÃFe(2)ÃC(10)
Fe(1)ÃC(10)ÃFe(2)
Fe(2)ÃFe(1)ÃC(10)
C(9)ÃFe(1)ÃC(10)
C(9)ÃFe(2)ÃC(10)
49.6(2)
81.7(3)
48.7(2)
50.1(2)
81.7(2)
48.2(2)
95.2(3)
97.9(3)
Fe(1)ÃC(9)ÃO(2)
Fe(2)ÃC(9)ÃO(2)
Fe(1)ÃC(10)ÃO(3)
Fe(2)ÃC(10)ÃO(3)
Fe(1)ÃC(8)ÃO(1)
Fe(1)ÃC(17)ÃSi
Fe(2)ÃC(18)ÃSi
Fe(1)ÃFe(2)ÃN
138.3(5)
140.0(5)
136.6(5)
141.6(5)
178.7(6)
119.4(3)
118.9(3)
101.5(2)
Fe(2)ÃFe(1)ÃN
C(9)ÃFe(2)ÃN
C(10)ÃFe(2)ÃN
Fe(2)ÃNÃC(1)
NÃC(1)ÃC(2)
C(1)ÃC(2)ÃC(3)
C(1)ÃC(2)ÃC(7)
99.3(2)
90.1(2)
90.6(2)
179.2(5)
178.3(7)
120.0(7)
119.4(6)
a
Estimated S.D. in the least significant figure are given in parentheses.
which one corner is occupied by a CN group. The
˚
the aryl substituents on the m-carbyne carbon are an
electron-withdrawing phenyl and p-(trifluo-ro-
methyl)phenyl group, respectively, the cationic carbyne
intermediate
[Fe2(m-CO)(m-CAr)(CO)2{(h5-C5H4)2Si-
(CH3)2}]ꢁ[M(CO)nCN]ꢂ (Arꢀ
C6H5 or p-CF3C6H4)
is not stably exist, and the (CO)5MÄCÄ Cr or
Nꢂ (Mꢀ
average CrÃ
/
C(CO) bond length is 1.916 A. The CÃ
/
N
a
˚
bond has a bond length of 1.13(1) A, which is a normal
CÅN triple-bond distance and is comparable with that
of corresponding CÃ
[(PPh3)2N][Fe(CO)4CN] (1.147(7) A) [17], and [Fe2(m-
/
˚
/
N bonds in 14 (1.15(1) A),
/
˚
/
/
/
˚
CNEt)3(CNEt)6] (1.13Á
C(CN) distance (1.92(2) A) indicates a high double-
bond character of the CrÃC(23) bond. Evidently,
/
1.19 A) [17]. The shorter CrÃ
/
Mo, W) anion (a representation of the same electronic
structure of the ꢂM(CO)5CN anion) further attacks the
more positive m-carbyne carbon of 1 or 2 to give
˚
/
complex 15 is the first example of a dimetal cationic
bridging carbyne complex with a carbonylmetal anion
counterion studied by X-ray crystallography.
bridging carbene complexes 9Á14 due to the electron-
/
withdrawing action of C6H5 or p-CF3C6H4 group to
increase the electron density on the m-carbyne carbon;
while in the case of 3, where the aryl substituent on the
m-carbyne carbon is a electron-pushing p-tolyl group,
the cationic carbyne intermediate [Fe2(m-CO)(m-
CC6H4CH3-p)(CO)2{(h5 - C5H4)2Si(CH3)2}]ꢁ[M(CO)n-
CN]ꢂ formed can stably exist due to the electron-
pushing action of the p-tolyl group, which provides its
The formation of complexes 9Á
involve initial formation of a cationic bridging carbyne
intermediate [Fe2(m-CO)(m-CAr)(CO)2{(h5-C5H4)2SiÃ
(CH3)2}]ꢁ[M(CO)nCN]ꢂ (Mꢀ
Cr, Mo, W; nꢀ5;
MꢀFe, nꢀ4) by combination of 1 or 2 and 3 with
[M(CO)nCN]ꢂ. In the case of cationic 1 and 2, where
/
14 and 15Á/18 might
/
/
/
/
/

R. Wang et al. / Journal of Organometallic Chemistry 658 (2002) 214Á
/227
223
Fig. 3. Molecular structure of 22, showing the atom-numbering
scheme with 45% thermal ellipsoids.
Fig. 1. Molecular structure of 14, showing the atom-numbering
scheme. Thermal ellipsoids are shown at 45% probability.
Fig. 2. Molecular structure of 15, showing the atom-numbering
scheme with 45% thermal ellipsoid. CH2Cl2 has been omitted for
clarity.
Fig. 4. Molecular structure of 23, showing the atom-numbering
scheme with 40% thermal ellipsoids.

224
R. Wang et al. / Journal of Organometallic Chemistry 658 (2002) 214Á227
/
partial charge for the m-carbyne carbon to stabilize the
cationic moiety of 3. Thus, complexes 15Á18 can be
isolated in high yields.
Complexes 9Á14 as dimetal bridging carbene com-
C5H4)2Si(CH3)2}] (22), in 48% yield was obtained (Eq.
(4)), whose structure has been established by its single
crystal X-ray diffraction study.
/
/
plexes were conveniently synthesized by the reaction of
the dimethylsilane-bridged diiron cationic carbyne com-
plexes with CN-containing carbonylmetal anions; and
these products are related to metal cyanide complexes
which have been examined extensively and can be used
as synthetic building blocks for syntheses of heterocycles
[18]. On the other hand, the carbonylmetal anion as a
counterion is quite unusual in the cationic carbyne
complexes. Only the [BF4]ꢂ, [BCl4]ꢂ, [BBr4]ꢂ, and
[SbCl6]ꢂ salts are known in transition-metal cationic
carbyne complexes [19]. To our knowledge, products
ð4Þ
15Á18 are the first samples of transition-metal cationic
/
However, complexes
3
and 16 react with
carbyne complexes with a carbonylmetal anion as a
counterion obtained by the reactions of [BBr4]ꢂ salt of 3
Na[N(SiMe3)2] under the same conditions to give not
similar arylnitrile-coordinated diiron complexes but
rather an unidentified decomposition product. The
identical reaction patterns of cationic complexes 3 and
16 with mercaptides and NaN(SiMe3)2 exhibit that both
complexes have similar reactivity which is different from
that of 1. Moreover, in contrast to the reaction [7] of
analogous cationic carbyne complex [Fe2(m-CO)(m-
CC6H5)(CO)2(h5-C5H5)2]BBr4 with Na[N(SiMe3)2]
which afforded a bridging carbene complex [Fe2(m-
with the [M(CO)nCN]ꢂ (Mꢀ
/
Cr, Mo, W, nꢀ
/
5; Mꢀ
/
Fe, nꢀ
It is noteworthy that cationic carbyne complexes 15Á
17 are more thermally stable than the parent complexes
1Á3 and can be stored at below ꢂ20 8C for several
months, while complexes 1Á3 only can be stored at
lower temperature (below ꢂ65 8C) for a short period.
Like complexes 1Á3, cationic carbyne complexes 15Á18
/4) anions.
/
/
/
/
/
/
/
should be highly electrophilic and highly reactive toward
nucleophiles. Indeed, when complex 15 or 16 was treated
CO){m-C(C6H5)N(SiMe3)2}(CO)2(h5-C5H5)2],
where
the N(SiMe3)2 moiety is bonded to the m-carbene
carbon, the reaction of cationic carbyne complex 1
with Na[N(SiMe3)2] gives benzonitrile-coordinated com-
plex 22. These reaction results indicate that the different
aryl-substituents at the m-carbyne carbon in the cationic
carbyne complexes have a great influence on the
reactivity of the cationic bridging carbyne complexes
and the resulting products.
with an equimolar quantity of NaSR (Rꢀ
/
CH3, C6H5,
5 h, after
work up as described in the Section 2 the known
p-CH3C6H4) in THF at ꢂ70 to ꢂ35 8C for 4Á
/
/
/
bridging mercaptocarbene complexes [Fe2(m-CO){m-
C(SR)C6H4CH3-p}(CO)2{(h5-C5H4)2Si(CH3)2}] (19Á
/
21) (Eq. (3)) were obtained in ꢀ
the reaction of parent cationic carbyne complex 3 with
NaSR which afforded the same products 19Á21 in lower
yields (64Á73%), among which the structure of 20 has
been established by X-ray crystallography [8].
/90% yields, similar to
/
The molecular structure of 22 (Fig. 3) confirmed that
N moiety is bonded to an Fe atom through
/
the C6H5CÅ
/
the N atom. The principal structure of the [Fe2(m-
CO)(CO){(h5-C5H4)2Si(CH3)2}] fragment of 22 is simi-
lar to that of the same unit in 14 and 15. The FeÃ
/
Fe
˚
bond length of 2.510(1) A is the same within experi-
ð3Þ
mental error as that found in 14, but the average FeÃ
/
˚
C(Cp) distance of 2.121 A is slightly longer than those of
˚
14 and 15 (average 2.108Á
/
2.117 A). The Fe(2)Ã
/
N bond
˚
length is 1.894(5) A, which is somewhat shorter than
˚
To further compare the reactivity of complexes 15Á
/
18
that in complex [Fe2(CO)6(NÄ
[20], in which the closing of the Fe2N2 core with the
shorter FeÃN bond distance results in partial double-
bond character in the FeÃN bond. The shorter Fe(2)Ã
distance in 22 suggests that the Fe(2)ÃN bond is a more
strongly coordinating bond and that there exists certain
double-bond character in the Fe(2)ÃN bond. The C(1)Ã
N has a bond length of 1.134(7) A, which is a normal CÅ
N distance and significantly shorter than that in similar
complexes [{(h5-C5H5)(CO)2MnÄ
C(C6H5)NC}2MnÃ
/
CHCH3)2] (1.942(7) A)
with that of parent cationic carbyne complexes 1Á3, the
/
reactions of complexes 1, 3, and 16 with NaN(SiMe3)2
was also made. When Na[N(SiMe3)2] was used as a
nucleophile for the reaction with cationic carbyne
/
/
/N
/
complex 1 in THF at ꢂ
/
70 to ꢂ
/
30 8C for 5 h, no
expected bridging carbene complex with
a
m-
/
/
˚
C(C6H5)N(SiMe3)2 ligand bonded to the m-carbene
carbon but a novel transferred product of bridging
/
carbyne
ligand,
[Fe2(m-CO)2(CO)NCC6H5{(h5-
/
/

R. Wang et al. / Journal of Organometallic Chemistry 658 (2002) 214Á
/227
225
5
1
˚
(CO)3CNMn(CO)2(h -C5H5)] (1.154(10) A) [6a] but is
comparable with that of the corresponding CÃN bond
1.19 A) [17]. The Fe(2),
N, C(1), and C(2) atoms are coplanar with an Fe(2)ÃNÃ
C(1) angle of 179.2(5)8 and a NÃC(1)ÃC(2) angle of
NÃC(1)ÃC(2)
Their H-NMR spectra had a resonance at 12.22, 12.04
and 12.23 ppm, respectively, characteristic for a m-
C(H)Ar group.
/
˚
in [Fe2(m-CNEt)3(CNEt)6] (1.13Á
/
/
/
Interestingly, this resonance has undergone a remark-
able downfield, similar to that of analogous bridging
arylcarbene complexes [Fe2(m-CO){m-C(H)Ar}(CO)2-
/
/
178.3(7)8, which shows that the Fe(2)Ã
/
/
/
(h5-C5H5)2] (Arꢀ
12.40) [21].
/
C6H5, d 12.38; Arꢀp-CH3C6H4, d
/
fragment is nearly linear. Thus, the Fe(2), N, C(1), and
C(2) atoms form a conjugate chain; the molecular of 22
is a stable conjugate system. Moreover, the C(1)Ã
/
C(2)
bond length is 1.435(9) A, intermediate between CÃ
single and CÄC double bond distances, which signify
˚
/C
/
some p-bond character between the C(1) atom and C(2)
atom of the benzene ring. In addition, it is interesting
that the two bridging CO ligands in 22 are asymme-
ð5Þ
trically bridged by the two iron atoms (C(9)Ã
/
Fe(1)
Fe(1) 1.946(6)
Fe(2) 1.891(6) A). The distances of Fe(1)Ã
C(9) and Fe(1)ÃC(10) are obviously longer than those
of Fe(2)ÃC(9) and Fe(2)ÃC(10). This might be caused
by the stronger electron-withdrawing action of the
C6H5CÅN ligand, which formed a conjugated chain
with the Fe(2) atom. Complex 22 appears to be the first
example of a species with a ArCNÃFe bond studied by
X-ray crystallography.
˚
˚
1.933(6) A, C(9)Ã
/
Fe(2) 1.905(7) A; C(10)Ã
/
˚
˚
A, C(10)Ã
/
/
/
/
/
/
ð6Þ
/
The formation of product 22 is unexpected and we do
not know the chemistry involved. Presumably the
reaction pathway to complex 22 could be proceeded
via initial attack of the [N(SiMe3)2]ꢂ anion on the m-
carbyne carbon of 1 to form an unstable bridging
carbene intermediate [Fe2(m-CO){m-C(Ar)N(SiMe3)2}-
(CO)2{(h5-C5H4)2Si(CH3)2}], which then formally lost
The structures of complexes 23 (Fig. 4) are very
similar to that of 14 and [Fe2(m-CO){m-C(SCH3)-
C6H4CH3-p}(CO)2{(h5-C5H4)2Si(CH3)2}] [8], except
that the W(CO)5CN group in 14 or SCH3 group in
[Fe2(m-CO){m-C(SCH3)C6H4CH3-p}(CO)2{(h5-C5H4)2-
Si(CH3)2}] is replaced by a H atom in 23. Many
structural features of 23 are nearly the same as those
of 14 and [Fe2(m-CO){m-C(SCH3)C6H4CH3-p}(CO)2-
two SiMe3 group with the dissociation of the m-CÃ
/Fe
bonds and the coordination of the N atom to the Fe(2)
atom and the terminal CO at Fe(2) to Fe(1) to yield
product 22. Such transformation from a bridging
phenylcarbyne ligand into a benzonitrile ligand to
coordinate to a central metal is quite novel. To the
best of our knowledge, there is no precedent for such
transformation in the reaction of transition-metal car-
byne complexes.
Unlike the reaction of 3, the reactions of cationic
carbyne complexes 1 and 2 with Na[Fe(CO)4CN] under
the same conditions give neither bridging aryl(penta-
carbo-nylcyanometal)carbene complexes nor cationic
bridging carbyne complexes with the [Fe(CO)4CN]ꢂ
anion as a counterion; instead unexpected bridging
arylcarbene complexes 23 and 24 (Eq. (5)) were obtained
in 51 and 46% yield, respectively.
{(h5-C5H4)2Si(CH3)2}]: the FeÃ
C(1)ÃFe distances, and the m-C(CO)Ã
/
Fe distance, the two m-
/
/Fe distances, the
angles between the planes of the benzene ring and the
two cyclopentadienyl rings. An apparent difference in
the structures of 14 or [Fe2(m-CO){m-C(SCH3)C6H4-
CH3-p}(CO)2{(h5-C5H4)2Si(CH3)2}] and 23 is the
˚
C(2) bond in 23 (1.453(6) A), which is
shorter C(1)Ã
/
intermediate between CÃ
/
C single and CÄ
/
C double bond
˚
distances, as compared with 14 (1.51(1) A) (or
[Fe2(m-CO){m-C(SCH3)C6H4CH3-p}(CO)2{(h5-C5H4)2-
˚
Si(CH3)2}] 1.52(1) A).
It is not clear by what pathway complexes 23Á
formed in reactions 5 and 6. These reactions possibly
could involve the formation of [MH(CO)n]ꢂ (Mꢀ
Fe,
nꢀ4; MꢀCr, nꢀ5) species via dissociation of the
[Fe(CO)4CN]ꢂ or [Cr(CO)4NO]ꢂ anion and protona-
/
25
The products 23 and 24 and bridging p-tolylcarbene
[Fe2(m-CO){m-C(H)C6H4CH3-p}(CO)2(h5-
/
complex
C5H4)2] (25) were also obtained in 37Á
/
47% yields from
/
/
/
the respective reaction (Eq. (6)) of 1, 2, and 3 with
[(PPh3)2N][Cr(CO)4NO] (8), of which the structure of 23
has been established by X-ray diffraction studies.
tion of [M(CO)n]2ꢂ (Mꢀ
/
Fe, nꢀ
/
4; Mꢀ
/
Cr, nꢀ5)
/
formed. Hydride transfer from the [MH(CO)n]ꢂ anion
The formulas of complexes 23Á/25 are also supported
by microanalytical and spectroscopic data (Section 2).
to the m-carbyne carbon of the cationic bridging carbyne

226
R. Wang et al. / Journal of Organometallic Chemistry 658 (2002) 214Á227
/
complex could form the bridging arylcarbene complex.
Indeed, the attack of [MH(CO)5]ꢂ (Mꢀ
Cr, W) species
on unsaturated MÅC moiety has been documented [22].
An indirect evidence is the reaction 6b of [h5-
C5H5(CO)2MnÅCC6H5]BBr4 with [NMe4][FeH(CO)4]
Acknowledgements
/
/
Financial support from the National Natural Science
Foundation of China, the Science Foundation of the
Chinese Academy of Sciences, and the NEDO of Japan
is gratefully acknowledged.
/
to give bridging phenylcarbene complex [MnFe{m-
C(H)C6H5}(CO)6(h5-C5H5)] which was formed via a
carbene intermediate [h5-C5H5(CO)2MnÄ
/
(C6H5)FeH-
(CO)6], then a hydrogen migration from Fe to the
carbene carbon occurred to produce the phenylcarbene
complex. The origin of the hydrogen could be THF or
water, which is a trace contaminant in solvent THF or
from glassware. Analogous H-abstracting reactions
from THF solvent to form the arylcarbene complexes
have been observed in the reactions of [h5-
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