Remarkable reactions of (η4-1-azadiene)Fe(CO)3 complexes with aryllithium reagents. Syntheses and structures of novel chelated furanyl-coordinated alkoxy(amino)carbeneiron, η4-azadiene-coordinated 17e acyliron, and iron inner salt complexes

Article abstract of DOI:10.1021/om010034v

The reactions of a (η⁴-1-azadiene)Fe(CO)₃ complex [(η⁴-C₄H₃OCH=CHCH=NC₆ H₁₁)Fe(CO)₃] (1), with aryllithium reagents, ArLi (Ar =C₆H₅, p-CH₃C₆H₄, o-CH₃OC₆H₄, p-CH₃OC₆H₄, p-CF₃C₆H₄), in ether at low temperature followed by alkylation with Et₃OBF₄ in aqueous solution at 0°C or in CH₂Cl₂ at -60°C gave novel chelated furanyl-coordinated alkoxy(amino)carbeneiron complexes [{η⁴-C₄H₃OCH=CHCH(Ar)N(C₆H₅ )C(OC₂H₅)=}Fe(CO)₂] (4, Ar = C₆H₅; 5, Ar = p-CH₃C₆H₄; 6, Ar = o-CH₃OC₆H₄; 7, A p-CH₃OC₆H₄; 8, Ar = p-CF₃C₆H₄). The analogous reactions of compounds [(η⁴-C₄H₃OCH=CHCH=NC₆ H₁₁)Fe(CO)₃] (2) and [(η⁴-C₆ H₅CH=CHCH=NC₆H₁₁)Fe(CO)₃] (3) with ArLi (Ar = C₆H₅, o-, m-, p-CH₃C₆ H₄) afforded novel η⁴-azadiene-coordinated 17e acyliron complexes [{η⁴-C₄H₃ OCH=CHCH=NC₆H₁₁}Fe(CO)₂(COAr)] (9, Ar = C₆H₅; 10, Ar =o-CH₃C₆H₄; 11, Ar =m-CH₃C₆H₄; 12, Ar = p-CH₃C₆H₄) and [(η⁴-C₆H₅CH=CHCH=NC₆ H₁₁)Fe(CO)₂(COAr)] (15, Ar = C₆H₅; 16, Ar = m-CH₃C₆H₄; 17, Ar = p-CH₃C₆H₄), respectively. Unexpectedly, 2 reacts similarly with p-CH₃OC₆H₄Li and p-CF₃C₆H₄Li to yield novel η²-azadiene-coordinated acyliron inner salt complexes [{η²-C₄H₃O-CH=CHCH=N(C₂ H₅)C₆H₁₁}Fe(CO)₃ (COAr)] (13, Ar = p-CH₃OC₆H₄; 14, Ar = p-CF₃C₆H₄). Analogous acyliron inner salt complex [{η²-C₆H₅CH=CHCH=N(C₂ H₅)C₆H₁₁}Fe(CO)₃ (COC₆H₄CH₃-p)] (18) was also obtained from the reaction of 3 with p-CH₃OC₆H₄Li. However, similar reactions of 3 with ArLi (Ar = o-CH₃C₆H₄, o-CH₃OC₆H₄, p-CF₃C₆H₄) produced η²-azadiene-coordinated aryliron inner salt complexes [{η²-C₆H₅CH=CHCH=N(C₂ H₅)C₆H₁₁}Fe(CO)₃Ar] (19, Ar = o-CH₃C₆H₄; 20, Ar = o-CH₃OC₆H₄; 21, Ar = p-CF₃C₆H₄). The structures of 6, 10, 13, and 18 have been established by X-ray diffraction studies.

Full text of DOI:10.1021/om010034v

Organometallics 2001, 20, 2387-2399
2387
Rem a r k a ble Rea ction s of (η4-1-a za d ien e)F e(CO)3
Com p lexes w ith Ar yllith iu m Rea gen ts. Syn th eses a n d
Str u ctu r es of Novel Ch ela ted F u r a n yl-Coor d in a ted
Alk oxy(a m in o)ca r ben eir on , η4-Aza d ien e-Coor d in a ted 17e
Acylir on , a n d Ir on In n er Sa lt Com p lexes
Shu Zhang,† Qiang Xu,*,‡ J ie Sun,† and J iabi Chen*,†
Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry,
Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China, and
National Institute of Advanced Industrial Science and Technology,
1-8-31 Midorigaoka, Ikeda 563-8577, J apan
Received J anuary 16, 2001
The reactions of a (η4-1-azadiene)Fe(CO)3 complex, [(η4-C4H3OCHdCHCHdNC6H11)Fe-
(CO)3] (1), with aryllithium reagents, ArLi (Ar ) C6H5, p-CH3C6H4, o-CH3OC6H4, p-CH3-
OC6H4, p-CF3C6H4), in ether at low temperature followed by alkylation with Et3OBF4 in
aqueous solution at 0 °C or in CH2Cl2 at -60 °C gave novel chelated furanyl-coordinated
alkoxy(amino)carbeneiron complexes [{η4-C4H3OCHdCHCH(Ar)N(C6H5)C(OC2H5)d}Fe(CO)2]
(4, Ar ) C6H5; 5, Ar ) p-CH3C6H4; 6, Ar ) o-CH3OC6H4; 7, Ar ) p-CH3OC6H4; 8, Ar )
p-CF3C6H4). The analogous reactions of compounds [(η4-C4H3OCHdCHCHdNC6H11)Fe(CO)3]
(2) and [(η4-C6H5CHdCHCHdNC6H11)Fe(CO)3] (3) with ArLi (Ar ) C6H5, o-, m-, p-CH3C6H4)
afforded novel η4-azadiene-coordinated 17e acyliron complexes [{η4-C4H3OCHdCHCHd
NC6H11}Fe(CO)2(COAr)] (9, Ar ) C6H5; 10, Ar ) o-CH3C6H4; 11, Ar ) m-CH3C6H4; 12, Ar )
p-CH3C6H4) and [(η4-C6H5CHdCHCHdNC6H11)Fe(CO)2(COAr)] (15, Ar ) C6H5; 16, Ar )
m-CH3C6H4; 17, Ar ) p-CH3C6H4), respectively. Unexpectedly, 2 reacts similarly with p-CH3-
OC6H4Li and p-CF3C6H4Li to yield novel η2-azadiene-coordinated acyliron inner salt
complexes [{η2-C4H3O-CHdCHCHdN(C2H5)C6H11}Fe(CO)3(COAr)] (13, Ar ) p-CH3OC6H4;
14, Ar ) p-CF3C6H4). Analogous acyliron inner salt complex [{η2-C6H5CHdCHCHdN(C2H5)-
C6H11}Fe(CO)3(COC6H4CH3-p)] (18) was also obtained from the reaction of 3 with p-CH3-
OC6H4Li. However, similar reactions of 3 with ArLi (Ar ) o-CH3C6H4, o-CH3OC6H4,
p-CF3C6H4) produced η2-azadiene-coordinated aryliron inner salt complexes [{η2-C6H5CHd
CHCHdN(C2H5)C6H11}Fe(CO)3Ar] (19, Ar ) o-CH3C6H4; 20, Ar ) o-CH3OC6H4; 21, Ar )
p-CF3C6H4). The structures of 6, 10, 13, and 18 have been established by X-ray diffraction
studies.
In tr od u ction
In previous studies, we have shown that a considerable
number of the novel olefin-coordinated transition-metal
carbene complexes and/or their isomerized products
were isolated, and a number of novel isomerizations of
olefin ligands have been observed in the reactions of
olefin-ligated metal carbonyls with aryllithium reagents
followed by alkylation with alkylating reagents. We
have also shown that the isomerization of the olefin
ligands and resulting products depend not only on the
olefin ligands but also on the nucleophiles used and
alkylation conditions.3-5 For instance, the reaction of
butadiene(tricarbonyl)iron with aryllithium reagents
and subsequent alkylation with Et3OBF4 result in the
formation of novel isomerized carbeneiron complexes
with two types of structures, A and B, depending on the
The synthesis, structure, and chemistry of alkene-
metal carbene complexes are one area of current inter-
est, stemming from the possible involvement of these
species in some reactions catalyzed by organometallic
compounds.1,2 In recent years, olefin-coordinated transi-
tion-metal carbene and carbyne complexes and/or their
isomerized products, as a part of a broader investigation
of transition-metal carbene and carbyne complexes,
have been examined extensively in our laboratory.3-10
† Shanghai Institute of Organic Chemistry.
‡ National Institute of Advanced Industrial Science and Technology.
(1) Rofer Depooeter, C. K. Chem. Rev. 1981, 81, 447.
(2) Wilkinson, S. G.; Stone, F. G. A.; Abel. E. W. Comprehensive
Organometallic Chemistry; Pergamon Press: Oxford, U.K., 1982; Vol.
8, p 40.
(3) Chen, J .-B.; Lei, G.-X.; Xu, W.-H.; J in, X.-L.; Shao, M.-C.; Tang,
Y.-Q. J . Organomet. Chem. 1985, 286, 55.
(4) Chen, J .-B.; Lei, G.-X.; Xu, W.-H.; Pan, Zhang, S.-W.; Zhang, Z.-
Y.; J in, X.-L.; Shao, M.-C.; Tang, Y.-Q. Organometallics 1987, 6, 2461.
(5) Chen, J .-B.; Lei, G.-X.; Pan, Z.-H.; Zhang, Z.-Y.; Tang, Y.-Q. J .
Chem. Soc., Chem. Commun. 1987, 1273.
(7) Chen, J .-B.; Lei, G.-X.; J in, Z.-S.; Hu, L.-H.; Wei, G.-C. Organo-
metallics 1988, 7, 1652.
(8) Yu, Y.; Chen, J .-B.; Chen, J .; Zheng P.-J . J . Chem. Soc., Chem.
Commun. 1995, 2089.
(9) Zhu, B.; Wang, R.-T.; Sun, J .; Chen, J .-B. J . Chem. Soc., Dalton
Trans. 1999, 4277.
(6) Chen, J .-B.; Li, D.-S.; Yu, Y.; J in, Z.-S.; Zhou, Q.-L.; Wei, G.-C.
Organometallics 1993, 12, 3885.
(10) Yu, Y.; Chen, J .-B.; Chen, J .; Zheng, P.-J . J . Chem. Soc., Chem.
Commun. 1995, 2089.
10.1021/om010034v CCC: $20.00 © 2001 American Chemical Society
Publication on Web 05/04/2001

2388 Organometallics, Vol. 20, No. 11, 2001
Zhang et al.
aryllithium reagents used (eq 1),3 while o-chinodimetha-
neiron tricarbonyl, [Fe{o-(CH2)2C6H4}(CO)3], where the
Fe(CO)3 moiety is bonded to the butadiene-like residue
of the o-chinomethane ligand, reacted with (o-lithiobenz-
yl)dimethylamine to give a novel coupling product of the
o-chinomethane ligand with CO and benzyldimethyl-
amino groups (eq 2).10
plexes,14 only very little is known about the reactivity
of (1-azadiene)Fe(CO)3 complexes so far. Up to now, only
the reactions of (1-azadiene)Fe(CO)3 with organo lithium
compounds have been reported by us11,12 and Thomas
et al.15 To explore the reactivity of (1-azadiene)Fe(CO)3
compounds and to further investigate the effect of
different azadiene ligands and different substituents at
the N atom of the azadiene ligands on the isomerization
of the olefin ligands and reaction products, we chose (η4-
1-azadiene)Fe(CO)3 complexes [(η4-C4H3OCHdCHCHd
NR)Fe(CO)3] (1, R ) C6H5; 2, R ) C6H11), where C4H3O
is a 2-furanyl group, and [(η4-C6H5CHdCHCHdNC6H11)-
Fe(CO)3] (3), synthesized recently by Imhof et al.,16 as
the starting materials for the reaction with aryllithium
reagents. These reactions lead to nucleophilic addition
to an Fe-bound CO group or the azadiene ligand to
afford the novel chelated furanyl-coordinated alkoxy-
(amino)carbeneiron complexes or η4-azadiene-coordi-
nated 17e acyliron complexes, or iron inner salt com-
plexes. We report herein these novel reactions and the
structures of the resulting products.
However, the isolobal (1-azadiene)Fe(CO)3 complexes
such as (cinnamaldehyde anil)iron tricarbonyl reacted
with aryllithium reagents under similar conditions to
give the chelated (η4-styrene)dicarbonyl[ethoxy(amino)-
carbene]iron complexes (eq 3)11 or aryliron inner salt
complexes (eq 4)12 depending on the substituent at the
N atom of the azadiene ligand and aryllithium reagents
used as well as alkylation conditions. In these reactions
the initial step is the attack of the aryllithium reagent
toward the iron-coordinated CdN double bond or an
iron-bound CO ligand, which is, in the subsequent
reaction steps, incorporated into the azadiene ligand
together with the organic group attached to lithium.
Although (1,3-butadiene)Fe(CO)3 complexes are widely
used as starting materials in the synthesis of organic
compounds and their reactions have been extensively
examined13 and there is also a number of reactions
starting from the isolobal (1,4-diazadiene)Fe(CO)3 com-
Exp er im en ta l Section
All procedures were performed under a dry, oxygen-free N2
atmosphere using standard Schlenk techniques. All solvents
employed were of reagent grade and dried by refluxing over
appropriate drying reagents and stored over 4 Å molecular
sieves under N2 atmosphere. Diethyl ether (Et2O) was distilled
from sodium/benzophenone ketyl, while petroleum ether (30-
60 °C) and CH2Cl2 were distilled from CaH2. The neutral
alumina (Al2O3, 100-200 mesh) used for chromatography was
(11) Yin, J .-G.; Chen, J .-B.; Xu, W.-H.; Zhang, Z.-Y.; Tang, Y.-Q.
Organometallics 1988, 7, 21.
(12) Yin, J .-G.; Chen, J .-B.; Xu, W.-H. Acta Chim. Sin. 1988, 46,
875.
(13) (a) Pearson, A. J . Acc. Chem. Res. 1980, 13, 463. (b) Gree, R.
Synthesis 1989, 341. (c) Knoelker, H.-J . Synlett 1992, 371. Chem. Rev.
2000, 100, 2941. (d) Roush, W. R.; Wada, C. K. J . Am. Chem. Soc. 1994,
116, 2151.
(14) Feiken, N.; Fruehauf, H.-W.; Vrieze, K. Organometallics 1994,
13, 2825.
(15) Danks, T. N.; Thomas, S. E. J . Chem. Soc., Perkin Trans. 1990,
761.
(16) Imhof, W.; Goebel, A. Organometallics 1999, 18, 736.

Remarkable Reactions of (η4-1-azadiene)Fe(CO)3
Organometallics, Vol. 20, No. 11, 2001 2389
deoxygenated at room temperature under high vacuum for 16
h, deactivated with 5% w/w N2-saturated water and stored
H, C6H5 + C4H3O), 6.29 (d, 1H, C4H3O), 5.65 (d, 1H, C4H3-
OCHdCHCHN-), 5.28 (s, 1H, C4H3OCHdCHCHN-), 4.40-
4.18 (m, 2H, OCH2CH3), 3.51 (d, 1H, C4H3O), 1.15 (t, 3H,
OCH2CH3), 0.36 (d, 1H, C4H3O-CHdCHCH-); MS m/e 415
17
under N2. The ligand C4H3OCHdCHCHdNC6H5 and com-
pounds [(η4-C4H3OCHdCHCHdNC6H11)Fe(CO)3] (2)16 and [(η4-
C6H5CHdCH-CHdNC6H11)Fe(CO)3] (3),16 Et3OBF4,18 and
aryllithium reagents19-24 used were prepared by literature
methods.
(M+ - CO), 387 (M+ - 2CO), 331 (M+ - Fe(CO)2), 302 (M+
-
Fe(CO)2 - C2H5), 274 (M+ - Fe(CO)2COC2H5). Anal. Calcd for
24H21O4NFe: C, 65.03; H, 4.77; N, 3.16. Found: C, 64.86; H,
C
The IR spectra were measured on a Shimadzu-IR-440
spectrophotometer. All 1H NMR spectra were recorded at
ambient temperature in acetone-d6 solution with TMS as the
internal reference using a Bruker AM-300 spectrometer.
4.62; N, 3.22.
Reaction of 1 with p-CH3C6H4Li to Give [{η4-C4H3OCHd
CHCH(C6H4CH3-p)N(C6H5)C(OC2H5)d}F e(CO)2] (5). Simi-
lar to the reaction of 1 with C6H5Li, the reaction of 0.50 g (1.48
mmol) of 1 with 1.71 mmol of p-CH3C6H4Li20 at -75 to -35
°C for 5 h, followed by alkylation and further treatment,
afforded 0.44 g (65%, based on 1) of orange-yellow crystalline
5: mp 58-60 °C dec; IR (CH2Cl2) ν(CO) 2044 (vs), 1977 (vs,
Electron ionization mass spectra (EIMS) were run on
a
Hewlett-Packard 5989A spectrometer. Melting points obtained
on samples in sealed capillaries are uncorrected.
P r ep a r a tion of [(η4-C4H3OCHdCHCHdNC6H5)F e(CO)3]
(1). This compound was synthesized according to ref 16. Fe2-
(CO)9 (1.0 g, 2.75 mmol) was stirred together with an equi-
molar amount of ligand [C4H3OCHdCHCHdNC6H5]17 (0.547
g, 2.75 mmol) in 60 mL of n-heptane at 50 °C for 20 h, during
which time the color of the solution darkened from orange to
deep red and the undissolved Fe2(CO)9 slowly disappeared.
After cooling to room temperature, the solvent was evaporated
in vacuo and the residue was chromatographed on an alumina
column with petroleum ether as the eluant. The orange band
was eluted and collected. The solvent was removed under
vacuum, and the crude product was recrystallized from
petroleum ether at -60 °C to give 0.52 g (56%) of orange-red
crystals of 1: mp 107-110 °C dec; IR (CH2Cl2) ν(CO) 2058 (vs),
1996 (vs), 1985 (sh) cm-1; ν (CdN) 1558 cm-1; 1H NMR (CD3-
COCD3) δ 7.49-6.42 (m, 9H, C6H5 + C4H3OCHdCHCHdN-
), 5.92 (dd, 1H, C4H3OCHdCHCHdN-), 3.39 (d, 1H, C4H3-
OCHdCHCHdN-); MS m/e 337 (M+), 309 (M+ - CO), 281
(M+ - 2CO), 253 (M+ - 3CO), 197 (M+ - Fe(CO)3). Anal. Calcd
for C16H11O4NFe: C, 57.01; H, 3.29; N, 4.15. Found: C, 57.17;
H, 3.18; N, 4.20.
br) cm-1; ν(CdN) 1599 cm-1; H NMR (CD3COCD3) δ 7.47-
1
7.00 (m, 10H, C6H5 + C6H4CH3 + C4H3O), 6.07 (d, 1H, C4H3O),
5.62 (d, 1H, C4H3OCHdCHCHN-), 5.23 (s, 1H, C4H3OCHd
CHCHN-), 4.43-4.15 (m, 2H, OCH2CH3), 3.43 (d, 1H, C4H3O),
2.27 (s, 3H, C6H4CH3), 1.15 (t, 3H, OCH2CH3), 0.35 (d, 1H,
C4H3OCHdCHCHN-); MS m/e 457 (M+), 429 (M+ - CO), 401
(M+ - 2CO), 345 (M+ - Fe(CO)2), 288 (M+ - Fe(CO)2COC2H5).
Anal. Calcd for C25H23O4NFe: C, 65.66; H, 5.07; N, 3.06.
Found: C, 65.90; H, 4.99; N, 3.36.
Rea ction of 1 w ith o-CH3OC6H4Li to Give [{η4-C4H3O-
CHdCHCH(C6H4OCH3-o)N(C6H5)C(OC2H5)d}Fe(CO)2] (6).
n-C4H9Li21 (1.19 mmol) was mixed with a solution of o-CH3-
OC6H4Br (0.21 g, 1.12 mmol) in 20 mL of ether at 0 °C. The
mixture was stirred at room temperature for 1.5 h. The
resulting ether solution of o-CH3OC6H4Li22 reacted, similar to
that for the reaction of 1 with C6H5Li, with 0.25 g (0.74 mmol)
of 1 in 50 mL of ether at -75 to -35 °C for 4.5 h, during which
time the orange-red solution gradually turned deep red. After
removal of the solvent under vacuum at -40 °C, the residue
was dissolved in 30 mL of CH2Cl2 at -65 °C. To this solution
was added dropwise 0.21 g (1.11 mmol) of Et3OBF4 dissolved
in 10 mL of CH2Cl2 with stirring within 15 min. The reaction
mixture turned from brown-red to orange-red. After being
stirred at -65 to -30 °C for 2 h, the solvent was removed in
vacuo at -30 °C. Further treatment of the resulting mixture
as described for the preparation of 4 gave 0.25 g (71%, based
on 1) of orange-yellow crystals of 6: mp 144-146 °C dec; IR
Rea ction of [(η4-C4H3OCHdCHCHdNC6H5)F e(CO)3] (1)
w it h C6H 5Li t o Give [{η4-C4H 3OCHdCH CH (C6H 5)N(C6-
H5)C(OC2H5)d}F e(CO)2] (4). To a solution of 0.40 g (1.19
mmol) of 1 dissolved in 60 mL of ether at -75 °C was added
1.54 mmol of C6H5Li19 with stirring. The reaction mixture was
stirred at -75 to -35 °C for 5 h, during which time the orange-
red solution gradually turned deep red. The resulting solution
was evaporated under high vacuum at -35 to -40 °C to
(CH2Cl2) ν(CO) 1970 (s), 1902 (vs) cm-1; ν(CdN) 1602 cm-1
;
18
1H NMR (CD3COCD3) δ 7.56-6.85 (m, 10H, C6H5 + C6H4CH3
+ C4H3O), 6.06 (d, 1H, C4H3O), 5.78 (d, 1H, C4H3OCHd
CHCHN-), 5.65 (s, 1H, C4H3OCHdCHCHN-), 4.44-4.17 (m,
2H, OCH2CH3), 3.66 (s, 3H, C6H4OCH3), 3.39 (d, 1H, C4H3O),
1.16 (t, 3H, OCH2CH3), 0.31 (d, 1H, C4H3OCHdCHCHN-);
MS m/e 473 (M+), 445 (M+ - CO), 417 (M+ - 2CO), 361 (M+
- Fe(CO)2), 304 (M+ - Fe(CO)2COC2H5). Anal. Calcd for
dryness. To the red residue was added Et3OBF4 (ca. 2-3 g).
This solid mixture was dissolved in 50 mL of N2-saturated
water at 0 °C with vigorous stirring and the mixture covered
with petroleum ether (30-60 °C). Immediately afterward, Et3-
OBF4 was added to the aqueous solution portionwise, with
strong stirring, until it became acidic. The aqueous solution
was extracted with petroleum ether/CH2Cl2. The combined
extract was evaporated to remove most of the solvent under
vacuum and then chromatographed on an alumina column (1.6
× 15-25 cm) at -20 to -30 °C with petroleum ether followed
by petroleum ether/CH2Cl2/Et2O (10:3:3) as the eluant. The
orange-yellow band was eluted and collected. The solvent was
removed under vacuum, and the residue was recrystallized
from petroleum ether/CH2Cl2 (5:1) solution at -80 °C to give
0.33 g (63%, based on 1) of orange-yellow crystals of 4: mp
C
25H23O5NFe: C, 63.44; H, 4.90; N, 2.96. Found: C, 63.19; H,
4.89; N, 3.11.
Rea ction of 1 w ith p-CH3OC6H4Li to Give [{η4-C4H3O-
CHdCHCH(C6H4OCH3-p)N(C6H5)C(OC2H5)d}Fe(CO)2] (7).
A solution of 0.20 g (1.07 mmol) of p-CH3OC6H4Br in 20 mL
of ether was mixed with 1.07 mmol of n-C4H9Li. After 40 min
stirring at room temperature, the resulting ether solution of
p-CH3O-C6H4Li23 was reacted, as in the reaction of 1 with
C6H5Li, with 0.30 g (0.89 mmol) of 1 at -75 to -35 °C for 4 h.
Further treatment of the resulting brown-red mixture as in
the preparation of 6 yielded 0.28 g (67%, based on 1) of 7 as
orange crystals: mp 88-90 °C dec; IR (CH2Cl2) ν(CO) 1971
(vs), 1903 (s) cm-1; ν(CdN) 1600 cm-1; 1H NMR (CD3COCD3)
δ 7.57-6.82 (m, 10H, C6H5 + C6H4CH3 + C4H3O), 6.08 (d, 1H,
C4H3O), 5.62 (d, 1H, C4H3OCHdCHCHN-), 5.21 (s, 1H, C4H3-
OCHdCHCHN-), 4.42-4.15 (m, 2H, OCH2CH3), 3.75 (s, 3H,
C6H4OCH3), 3.44 (d, 1H, C4H3O), 1.14 (t, 3H, OCH2CH3), 0.37
(d, 1H, C4H3OCHdCHCH-); MS m/e 473 (M+), 445 (M+ - CO),
417 (M+ - 2CO), 361 (M+ - Fe(CO)2), 304 (M+ - Fe(CO)2 -
COC2H5). Anal. Calcd for C25H23O5NFe: C, 63.44; H, 4.90; N,
2.96. Found: C, 64.05; H, 5.11; N, 2.76.
120-122 °C dec; IR (CH2Cl2) ν(CO) 1970 (s), 1903 (s) cm-1
;
ν(CdN) 1598 cm-1; 1H NMR (CD3COCD3) δ 7.57-7.29 (m, 11
(17) Rudtschenko, Z. Obsc. Chim. 1940, 10, 1953
(18) Meerwein, H.; Hinze, G.; Hofmann, P.; Kroniny, E.; Pfeil, E. J .
Prakt. Chem. 1937, 147, 257.
(19) Wittig, G. Angew. Chem. 1940, 53, 243.
(20) Gilman, H.; Zoellner, E. A.; Selby, W. M. J . Am. Chem. Soc.
1933, 55, 1252.
(21) J ones, R. G.; Gilman, H. Org. React. (N. Y.) 1951, 6, 352.
(22) Gilman, H.; Langham, W.; Moore, F. W. J . Am. Chem. Soc.
1940, 62, 2327.
(23) Fischer, E. O.; Kreiter, C. G.; Kollmeier, H. J .; Muller, J .;
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(24) Fischer, E. O.; Chen, J .-B.; Schubert, U. Z. Naturforsch., B 1982,
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2390 Organometallics, Vol. 20, No. 11, 2001
Zhang et al.
Reaction of 1 with p-CF3C6H4Li to Give [{η4-C4H3OCHd
CHCH(C6H4CF 3-p)N(C6H5)C(OC2H5)d}F e(CO)2] (8). A so-
lution of 0.24 g (1.07 mmol) of p-CF3C6H4Br in 20 mL of ether
was mixed with 1.07 mmol of n-C4H9Li. After 40 min stirring
2CO - C6H4CH3), 259 (M+ - 2CO - COC6H4CH3), 203 (C4H3-
OCHdCHCHdNC6H11+), 119 (COC6H4CH3+). Anal. Calcd for
C
23H24O4NFe: C, 63.61; H, 5.57; N, 3.23. Found: C, 63.28; H,
6.05; N, 2.90.
Reaction of 2 with p-CH3C6H4Li to Give [(η4-C4H3OCHd
CHCHdNC6H11)F e(CO)2(COC6H4CH3-p)] (12). As used in
the reaction of 2 with C6H5Li, 0.40 g (1.17 mmol) of 2 was
treated with 1.32 mmol of p-CH3C6H4Li at -75 to -35 °C for
4 h. Further treatment of the resulting mixture as in the
preparation of 9 afforded 0.31 g (82%, based on 2) of yellow
powder of 12: mp 112-113 °C dec; IR (CH2Cl2) ν(CO) 1996
at room temperature, the resulting ether solution of p-CF3C6H4-
24
Li
was reacted, as in the reaction of 1 with C6H5Li, with
0.30 g (0.89 mmol) of 1 at -75 to -35 °C for 4 h, followed by
alkylation; further treatment as described for the reaction of
1 with o-CH3OC6H4Li gave 0.28 g (62%, based on 1) of orange-
red crystals of 8: mp 45-47 °C dec; IR (CH2Cl2) ν(CO) 2019
(s), 1933 (vs, br) cm-1; ν(CdN) 1605 cm-1 1H NMR (CD3-
;
1
(vs), 1933 (vs), 1607 (m) cm-1; ν(CdN) 1585 (m, br) cm-1; H
COCD3) δ 7.81-7.07 (m, 10H, C6H5 + C6H4CH3 + C4H3O), 5.90
(d, 1H, C4H3O), 5.67 (d, 1H, C4H3OCHdCHCHN-), 5.44 (s,
1H, C4H3OCHdCH-CHN-), 4.44-4.20 (m, 2H, OCH2CH3),
3.50 (d, 1H, C4H3O), 1.13 (t, 3H, OCH2CH3), 0.32 (d, 1H, C4H3-
OCHdCHCHN-); MS m/e 511 (M+), 483 (M+ - CO), 455 (M+
- 2CO), 399 (M+ - Fe(CO)2), 342 (M+ - Fe(CO)2COC2H5).
Anal. Calcd for C25H20O4F3NFe: C, 58.73; H, 3.94; N, 2.74.
Found: C, 58.90; H, 4.06; N, 3.02.
NMR (CD3CO-CD3) δ 7.28-7.02 (m, 5H, CH3C6H4 + C4H3O),
6.78 (d, 1H, C4H3OCHdCHCHdN-), 6.25-5.96 (m, 2H,
C4H3O), 5.01 (dd, 1H, C4H3OCHdCH-CHdN-), 3.30 (d, 1H,
C4H3OCHdCHCHdN-), 2.27 (s, 3H, CH3C6H4), 2.33-1.12 (m,
11H, C6H11); MS m/e 406 (M+ - CO), 378 (M+ - 2CO), 287
(M+ - 2CO - C6H4CH3), 259 (M+ - 2CO - COC6H4CH3), 203
(C4H3OCHdCHCHdNC6H11+), 119 (COC6H4CH3+). Anal. Cal-
cd for C23H24O4NFe: C, 63.61; H, 5.57; N, 3.23. Found: C,
63.48; H, 6.02; N, 3.14.
Rea ction of [(η4-C4H3OCHdCHCHdNC6H11)F e(CO)3]
(2) w ith C6H5Li to Give [(η4-C4H3OCHdCHCHdNC6H11)-
F e(CO)2(COC6H5)] (9). To a solution of 0.30 g (0.87 mmol) of
2 dissolved in 60 mL of ether at -75 °C was added 1.05 mmol
of C6H5Li with stirring. The reaction mixture was stirred at
-75 to -35 °C for 4-5 h, during which time the orange
solution gradually turned red. The resulting solution was
evaporated under high vacuum at -40 °C to dryness. Subse-
quent alkylation and further treatment of the residue as in
the reaction of 1 with o-CH3OC6H4Li gave 0.28 g (76%, based
on 2) of yellow crystals of 9: mp 119-120 °C dec; IR (CH2Cl2)
Rea ction of 2 w ith p-CH3OC6H4Li to Give [{η2-C4H3O-
CHdCHCHdN(C2H5)C6H11}Fe(CO)3(COC6H4OCH3-p)] (13).
Compound 2 (0.40 g, 1.17 mmol) was treated, in a manner
similar to that for the reaction of 2 with C6H5Li, with a fresh
p-CH3OC6H4Li ether solution prepared by the reaction of
p-CH3OC6H4Br (0.17 mL, 1.35 mmol) with n-C4H9Li (1.35
mmol) in ether at -75 to -35 °C for 4 h, during which time
the orange solution turned dark red. Subsequent alkylation
and further treatment of the resulting mixture as described
in the reaction of 2 with C6H5Li produced 0.43 g (73%, based
on 2) of orange crystals of 13: mp 92-94 °C dec; IR (CH2Cl2)
ν(CO) 2019 (vs), 1957 (w), 1936 (vs), 1603 (m) cm-1; ν(CdN)
1588 (m, br) cm-1; 1H NMR (CD3COCD3) δ 7.94-6.96 (m, 5H,
C6H4OCH3 + C4H3O), 6.63 (d, 1H, C4H3OCHdCHCHdN-),
6.35-6.25 (m, 2H, C4H3O), 4.39 (t, 1H, C4H3O-CHdCHCHd
N-), 4.20 (d, 1H, C4H3OCHdCHCHdN-), 3.87 (s, 3H, CH3-
OC6H4), 3.67-3.38 (m, 2H, CH2CH3), 3.21 (m, 1H, C6H11),
ν(CO) 1990 (vs), 1933 (vs), 1603 (m) cm-1; ν(CdN) 1550 cm-1
;
1H NMR (CD3COCD3) δ 7.29-7.07 (m, 6H, C6H5 + C4H3O),
6.79 (d, 1H, C4H3OCHdCHCHdN-), 6.26-5.99 (m, 2H,
C4H3O), 5.63 (m, 0.5H, CH2Cl2), 5.03 (dd, 1H, C4H3OCHd
CHCHdN-), 3.31 (d, 1H, C4H3OCHdCHCHdN-), 2.37-1.00
(m, 11H, C6H11); MS m/e 392 (M+ - CO), 364 (M+ - 2CO),
259 (M+ - 2CO - COC6H5), 203 (C4H3OCHdCHCHdNC6H11+),
105 (COC6H5+), 84 (CH2Cl2+). Anal. Calcd for C22H22O4NFe‚
0.25CH2Cl2: C, 60.53; H, 5.24; N, 3.17. Found: C, 60.59; H,
5.58; N, 2.91.
1.91-1.06 (m, 13H, C6H11 + CH2CH3); MS m/e 451 (M+
-
2CO), 423 (M+ - 3CO), 288 (M+ - 3CO - COC6H4OCH3), 232
(C4H3OCHdCHCHdN(C2H5)C6H11+), 135 (COC6H4OCH3+).
Anal. Calcd for C26H29O6NFe: C, 61.55; H, 5.76; N, 2.76.
Found: C, 61.26; H, 5.74; N, 2.62.
Reaction of 2 with o-CH3C6H4Li to Give [(η4-C4H3OCHd
CHCHdNC6H11)F e(CO)2(COC6H4CH3-o)] (10). The proce-
dure used in the reaction of 2 (0.30 g, 0.87 mmol) with
o-CH3C6H4Li (1.10 mmol) was the same as that for the reaction
of 2 with C6H5Li at -75 to -35 °C for 5 h, during which time
the orange solution turned red. Further treatment as in the
preparation of 9 yielded 0.28 g (73%, based on 2) of orange-
yellow crystalline 10: mp 102-103 °C dec; IR (CH2Cl2) ν(CO)
Reaction of 2 with p-CF3C6H4Li to Give [{η2-C4H3OCHd
CHCHdN(C2H5)C6H11}Fe(CO)3(COC6H4CF3-p)] (14). A 0.40
g (1.17 mmol) sample of 2 was treated, as used in the reaction
of 2 with C6H5Li, with a fresh p-CF3C6H4Li ether solution
prepared by the reaction of p-CF3C6H4Br (0.30 g, 1.32 mmol)
with n-C4H9Li (1.32 mmol) in ether at -75 to -35 °C for 4 h.
Further treatment of the resulting mixture as described for
the reaction of 2 with C6H5Li gave 0.45 g (71%,based on 2) of
crystals of 14: 89-90 °C dec; IR (CH2Cl2) ν(CO) 2055 (w), 2028
1996 (vs), 1934 (vs), 1600 (m, br) cm-1; ν(CdN) 1580 (m, br)
1
cm-1; H NMR (CD3COCD3) δ 7.40-6.89 (m, 5H, CH3C6H4
+
C4H3O), 6.73 (d, 1H, C4H3OCHdCHCHdN-), 6.57-6.13 (m,
2H, C4H3O), 5.15 (dd, 1H, C4H3OCHdCHCHdN-), 3.37 (d,
1H, C4H3O-CHdCHCHdN-), 2.26-1.04 (m, 11H, C6H11),
(vs), 1960 (vs, br), 1586 (m, br) cm-1; ν(CdN) 1570 (m, br) cm-1
1H NMR (CD3COCD3) δ 7.95-6.30 (m, 5H, CH3OC6H4
;
+
1.87 (s, 3H, CH3C6H4); MS m/e 406 (M+ - CO), 378 (M+
-
2CO), 287 (M+ - 2CO - C6H4CH3), 259 (M+ - 2CO - COC6H4-
CH3), 203 (C4H3OCHdCHCHdNC6H11+), 119 (COC6H4CH3+).
Anal. Calcd for C23H24O4-NFe‚0.5C4H8O: C, 63.84; H, 6.00;
N, 2.98. Found: C, 63.83; H, 6.16; N, 2.90.
C4H3O), 6.65 (d, 1H, C4H3OCHdCHCHdN-), 6.35-6.32 (m,
2H, C4H3O), 4.10 (m, 1H, C4H3OCHdCHCHdN-), 3.80 (d, 1H,
C4H3OCHdCHCHdN-), 3.45 (m, 2H, CH2CH3), 3.41 (m, 1H,
C6H11), 2.01-1.12 (m, 13H, C6H11 + CH2CH3); MS m/e 545
(M+), 517 (M+ - CO), 489 (M+ - 2CO), 461 (M+ - 3CO), 288
(M+ - 3CO - COC6H4CF3), 232 (C4H3OCHdCHCHdN(C2H5)-
C6H11+), 173 (COC6H4CF3+). Anal. Calcd for C26H26O5F3NFe:
C, 57.26; H, 4.81; N, 2.67. Found: C, 56.88; H, 4.86; N, 2.80.
Rea ction of [(η4-C6H5CHdCHCHdNC6H11)F e(CO)3] (3)
w ith C6H5Li to Give [(η4-C6H5CHdCHCHdNC6H11)F e-
(CO)2(COC6H5)] (15). To 0.60 g (1.70 mmol) of 3 dissolved in
60 mL of ether at -75 °C was added 1.87 mmol of C6H5Li.
The mixture was stirred at -75 to -35 °C for 4.5 h, during
which time the orange solution turned deep red. After vacuum
removal of the solvent at -35 °C, subsequent alkylation and
further treatment of the residue as that described in the
reaction of 1 with C6H5Li (alkylation in H2O) or in the reaction
Reaction of 2 with m-CH3C6H4Li to Give [(η4-C4H3OCHd
CHCHdNC6H11)F e(CO)2(COC6H4CH3-m )] (11). As in the
reaction of 2 with C6H5Li, compound 2 (0.30 g, 0.87 mmol) was
treated with m-CH3C6H4Li (1.06 mmol) at -75 to -35 °C for
4 h. Further treatment similar to that used in the reaction of
2 with C6H5Li gave 0.31 g (80%, based on 2) of 11 as yellow
powder: mp 113-114 °C dec; IR (CH2Cl2) ν(CO) 1996 (vs),
1932 (vs), 1605 (m) cm-1; ν(CdN) 1582 (m, br) cm-1; 1H NMR
(CD3CO-CD3) δ 7.29-6.90 (m, 5H, CH3C6H4 + C4H3O), 6.76
(d, 1H, C4H3OCHdCHCHdN-), 6.26-6.00 (m, 2H, C4H3O),
5.03 (dd, 1H, C4H3OCHdCHCHdN-), 3.30 (d, 1H, C4H3OCHd
CHCHdN-), 2.27 (s, 3H, CH3C6H4), 2.35-1.06 (m, 11H,
C6H11); MS m/e 406 (M+ - CO), 378 (M+ - 2CO), 287 (M+
-

Remarkable Reactions of (η4-1-azadiene)Fe(CO)3
Organometallics, Vol. 20, No. 11, 2001 2391
of 1 with o-CH3OC6H4Li (alkylation in CH2Cl2) yielded 0.59 g
(80%, based on 3) of yellow crystals of 15: mp 118-120 °C dec;
IR (CH2Cl2) ν(CO) 1994 (s),1932 (vs), 1597 (s) cm-1; ν(CdN)
at -75 to -35 °C for 4 h, during which time the orange solution
turned deep red. Subsequent treatment of the resulting
mixture as described for the preparation of 15 afforded 0.31 g
(78%, based on 3) of yellow powder of 19: mp 102-103 °C dec;
IR (CH2Cl2) ν(CO) 2052 (m), 1992 (s), 1931 (s) cm-1; ν(CdN)
1595 (m, br) cm-1; 1H NMR (CD3COCD3) δ 7.36-6.40 (m, 10H,
C6H5 + C6H4CH3 + C6H5CHdCHCHdN-), 5.38 (dd,1H,C6H5-
CHdCHCHdN-), 3.36 (d, 1H, C6H5CHdCHCHdN-), 1.74 (s,
3H, C6H4CH3), 2.27-1.00 (m, 11H, C6H11); 3.40-3.28 (q, 2H,
CH2CH3), 0.86 (t, 3H, CH2CH3); MS m/e 445 (M+ - CO), 417
(M+ - 2CO), 298 (M+ - 3CO - C6H4CH3), 242 (C6H5CHd
CHCHdN(C2H5)C6H11+), 91 (C6H4CH3+). Anal. Calcd for
1549 (s) cm-1 1H NMR (CD3COCD3) δ 7.19-6.80 (m, 11H,
;
2C6H5 + C6H5CHdCHCHdN-), 5.26 (dd, 1H, C6H5CHd
CHCHdN-), 3.29 (d, 1H, C6H5CHdCHCHdN-), 2.32-1.09
(m, 11H, C6H11); MS m/e 402 (M+ - CO), 374 (M+ - 2CO),
297 (M+ - 2CO - C6H5], 269 (M+ - 2CO - COC6H5), 213
(C6H5CHdCHCHdNC6H11+), 105 (COC6H5+). Anal. Calcd for
C
24H24O3NFe: C, 66.99; H, 5.62; N, 3.26. Found: C, 66.67; H,
5.77; N, 3.27.
Rea ction of 3 w ith m -CH3C6H4Li to Give [(η4-C6H5CHd
CHCHdNC6H11)F e(CO)2(COC6H4CH3-m )] (16). As used for
the reaction of 3 with C6H5Li, 0.30 g (0.85 mmol) of 3 was
treated with 1.08 mmol of m-CH3C6H4Li at -75 to -35 °C for
4.5 h. Further treatment of the resulting mixture as in the
preparation of 15 gave 0.30 g (80%, based on 3) of 16 as yellow
crystals: mp 107-108 °C dec; IR (CH2Cl2) ν(CO) 1993 (s), 1930
C
27H31O3NFe: C, 68.50; H, 6.60; N, 2.96. Found: C, 68.54; H,
7.01; N, 2.84.
Reaction of 3 with o-CH3OC6H4Li to Give [{η2-C6H5CHd
CH CH dN(C2H 5)C6H 11}F e(CO)3C6H 4OCH 3-o] (20). Com-
pound 3 (0.30 g, 0.85 mmol) was treated as in the reaction of
3 with C6H5Li with a fresh o-CH3OC6H4Li ether solution
prepared by the reaction of o-CH3OC6H4Br (0.24 g, 1.28 mmol)
with n-C4H9Li (1.28 mmol) in ether at -75 to -35 °C for 4 h.
Further treatment of the resulting solution as in the reaction
of 3 with C6H5Li yielded 0.30 g (60%, based on 3) of orange-
yellow crystalline 20: mp 84-85 °C dec; IR (CH2Cl2) ν(CO)
1
(vs), 1603 (br, m) cm-1; ν(CdN) 1584 (br, m) cm-1; H NMR
(CD3COCD3) δ 7.16-6.47 (m, 9H, C6H5 + C6H4CH3), 6.78 (dd,
1H, C6H5CHdCH-CHdN-), 5.63 (m, 0.5H, CH2Cl2), 5.25 (dd,
1H, C6H5CHdCHCHdN-), 3.30 (dd, 1H, C6H5CHdCHCHd
N-), 2.19 (s, 3H, CH3C6H4), 2.34-1.03 (m, 11H, C6H11); MS
m/e 416 (M+ - CO), 388 (M+ - 2CO), 269 (M+ - 2CO -
COC6H4CH3), 213 (C6H5CHdCH-CHdNC6H11+), 119 (COC6H4-
CH3+), 84 (CH2Cl2+). Anal. Calcd for C25H26O3NFe‚0.25CH2-
Cl2: C, 65.14; H, 5.74; N, 3.01. Found: C, 65.17; H, 6.03; N,
3.09.
1
2051 (s), 1986 (vs), 1925 (s) cm-1; ν(CdN) 1601 (m) cm-1; H
NMR (CD3COCD3) δ 7.36-7.08 (m, 9H, C6H5 + C6H4OCH3),
6.72 (d, 1H, C6H5CHdCHCHdN-), 5.36 (t, 1H, C6H5CHd
CHCHdN-), 3.82 (s, 3H, CH3OC6H4), 3.45 (d, 1H, C6H5CHd
CHCHdN-), 3.30-3.25 (m, 2H, CH2CH3), 3.21 (m, 1H, C6H11),
2.08-0.87 (m, 13H, C6H11 + CH2CH3); MS m/e 461 (M+
-
Rea ction of 3 w ith p-CH3C6H4Li to Give [(η4-C6H5CHd
CHCHdNC6H11)F e(CO)2(COC6H4CH3-p)] (17). The proce-
dure used in the reaction of 3 (0.30 g, 0.85 mmol) with
p-CH3C6H4Li (1.11 mmol) was the same as that for the reaction
of 3 with C6H5Li at -75 to -35 °C for 4 h. Further treatment
of the resulting mixture in a manner similar to that described
in the reaction of 1 with C6H5Li (alkylation in H2O) or in the
reaction of 1 with o-CH3OC6H4Li (alkylation in CH2Cl2) gave
0.32 g (79%, based on 3) of yellow crystals of 17: mp 103-104
2CO), 433 (M+ - 3CO), 354 (M+ - 2CO - C6H4OCH3), 326
(M+ - 3CO - C6H4OCH3), 242 (C6H5CHdCHCHdN(C2H5)-
C6H11+),107 (C6H4OCH3+). Anal. Calcd for C28H31O5NFe: C,
65.00; H, 6.04; N, 2.71. Found: C, 64.98; H, 6.30; N, 2.97.
Rea ction of 3 w ith p-CF 3C6H4Li to Give [{η2-C6H5CHd
CHCHdN(C2H5)C6H11}F e(CO)3C6H4CF 3-p] (21). Compound
3 (0.40 g, 1.13 mmol) was treated, in a manner similar to that
described in the reaction of 3 with C6H5Li, with a fresh
p-CF3C6H4Li ether solution prepared by the reaction of
p-CF3C6H4Br (0.31 g, 1.36 mmol) with n-C4H9Li (1.36 mmol)
in ether at -75 to -35 °C for 4 h. Further treatment of the
resulting mixture as described for the reaction of 3 with C6H5-
Li gave 0.48 g (80%, based on 3) of yellow crystals of 21: mp
118-120 °C dec; IR (CH2Cl2) ν(CO) 2025 (vs), 1951 (vs, br),
°C dec; IR (CH2Cl2) ν(CO) 1993 (s), 1930 (vs), 1598 (m, br) cm-1
;
ν(CdN) 1550 (m) cm-1; 1H NMR (CD3COCD3) δ 7.36-6.78 (m,
10H, C6H5 + C6H4CH3 + C6H5CHdCHCHdN-), 5.23 (dd, 1H,
C6H5-CHdCHCHdN-), 3.26 (d, 1H, C6H5CHdCHCHdN-),
2.31 (s, 3H, C6H4CH3), 2.40-1.14 (m, 11H, C6H11); MS m/e 416
(M+ - CO), 388 (M+ - 2CO), 269 (M+ - 2CO - COC6H4CH3),
213 (C6H5CHdCHCHdNC6H11+), 119 (COC6H4CH3+). Anal.
Calcd for C25H26O3NFe: C, 67.58; H, 5.98; N, 3.15. Found: C,
67.33; H, 6.01; N, 3.25.
1930 (w) cm-1; ν(CdN) 1586 (br, m) cm-1 1H NMR (CD3-
;
COCD3) δ 8.04-7.07 (m, 9H, C6H5 + C6H4CF3), 6.40 (d, 1H,
C6H5CHdCH-CHdN-), 4.87 (m, 1H, C6H5CHdCHCHdN-
), 4.11 (d, 1H, C6H5CHdCHCHdN-), 3.75 (m, 2H, CH2CH3),
3.12 (m, 1H, C6H11), 1.96-1.20 (m, 13H, C6H11 + CH2CH3);
MS m/e 499 (M+ - CO), 471 (M+ - 2CO), 443 (M+ - 3CO),
298 (M+ - 3CO - C6H4CF3), 242 (C6H5CHdCHCHdN(C2H5)-
C6H11+), 145 (C6H4CF3+). Anal. Calcd for C27H28O3F3NFe: C,
61.49; H, 5.35; N, 2.66. Found: C, 61.20; H, 5.39; N, 2.90.
X-r a y Cr ysta l Str u ctu r e Deter m in a tion s of Com p lexes
6, 10, 13, a n d 18. The single crystals of 6, 10, 13, and 18
suitable for X-ray diffraction study were obtained by recrys-
tallization from petroleum ether/CH2Cl2 solution or petroleum
ether/THF at -80 °C. Single crystals were mounted on a glass
fiber and sealed with epoxy glue. The X-ray diffraction
intensity data for 3870, 7214, 3725, and 4719 independent
reflections, of which 2159, 1840, and 2898 with I > 2.50σ(I)
for 6, 10, and 18 and 1307 with I > 2.00σ(I) for 13 were
observable, were collected with a Rigaku AFC7R diffractome-
ter at 20 °C using Mo KR radiation with an ω-2θ scan mode
within the ranges 5°e 2θ e 50° for 6, 10, and 13 and 5°e 2θ
e 51° for 18, respectively.
Reaction of 3 with p-CH3OC6H4Li to Give [{η2-C6H5CHd
CHCHdN(C2H5)C6H11}F e(CO)3(COC6H4OCH3-p)] (18). As
used in the reaction of 3 with C6H5Li, 3 (0.34 g, 0.963 mmol)
was treated with a fresh p-CH3OC6H4Li solution prepared by
the reaction of p-CH3OC6H4Br (0.18 mL, 1.43 mmol) with
n-C4H9Li (1.43 mmol) in ether at -75 to -35 °C for 4 h, during
which time the orange solution turned deep red. Subsequent
alkylation and further treatment of the resulting mixture as
described in the reaction of 3 with C6H5Li yielded 0.28 g (55%,
based on 3) of orange crystalline 18: mp 104-105 °C dec; IR
(CH2Cl2) ν(CO) 2052 (w), 2016 (vs), 1937 (vs, br), 1588 (m, br)
1
cm-1; ν(CdN) 1552 (m) cm-1; H NMR (CD3COCD3) δ 7.92-
6.95 (m, 9H, C6H5 + CH3OC6H4), 6.73 (d, 1H, C6H5CHd
CHCHdN-), 4.67 (t, 1H, C6H5CHdCH-CHdN-), 4.33 (d, 1H,
C6H5CHdCHCHdN-), 3.86 (s, 3H, CH3OC6H4), 3.72-3.51 (m,
2H, CH2CH3), 3.24 (m, 1H, C6H11), 2.00-0.84 (m, 13H, C6H11
+ CH2CH3); MS m/e 517 (M+), 489 (M+ - CO), 461 (M+ - 2CO),
326 (M+ - 2CO - COC6H4OCH3), 242 (C6H5CHdCHCHd
N(C2H5)C6H11+), 135 (COC6H4OCH3+). Anal. Calcd for C28H31O5-
NFe: C, 65.00; H, 6.04; N, 2.71. Found: C, 64.80; H, 5.94; N,
2.85.
Rea ction of 3 w ith o-CH3C6H4Li to Give [{η2-C6H5CHd
CHCHdN(C2H5)C6H11}F e(CO)3C6H4CH3-o] (19). Similar to
the procedures used in the reaction of 3 with C6H5Li, 0.30 g
(0.85 mmol) of 3 was treated with 1.19 mmol of o-CH3C6H4Li
The structures of 6, 10, 13, and 18 were solved by direct
methods and expanded using Fourier techniques. For 6 and
18, the non-hydrogen atoms were refined anisotropically. For
10 and 13, some non-hydrogen atoms were refined anisotro-
pically, while the rest were refined isotropically. For all four
complexes, the hydrogen atoms were included but not refined.

2392 Organometallics, Vol. 20, No. 11, 2001
Ta ble 1. Cr ysta l Da ta a n d Exp er im en ta l Deta ils for Com p lexes 6, 10, 13, a n d 18
Zhang et al.
6
10‚1/2C4H8O
13
18
formula
fw
C
25H23O5NFe
C25H28O4.5NFe
470.35
C26H28O6NFe
506.36
C28H31O5NFe
517.40
473.31
space group
a (Å)
b (Å)
P-1 (No. 2)
9.984(5)
12.889(4)
9.898(5)
103.66(3)
113.64(4)
82.28(4)
1132.7(10)
2
P21/c (No. 14)
10.524(7)
12.313(10)
37.64(1)
P21/n (No. 14)
10.822(3)
20.028(6)
P21/c (No. 14)
12.799(2)
10.276(2)
20.649(4)
c (Å)
11.924(4)
R (deg)
â (deg)
γ (deg)
V (Å3 )
96.31(7)
97.38(2)
105.64(1)
4847(5)
8
1.289
1976.00
2563(1)
4
1.312
1060.00
2615.3(9)
4
1.314
1088.00
Z
Dcalcd (g/cm3)
F(000)
µ(Mo KR) (cm-1
1.388
492.00
7.01
)
6.53
6.27
6.13
radiation (monochromated
in incident beam)
diffractometer
Mo KR (λ ) 0.71069 Å)
Mo KR (λ ) 0.71069 Å)
Mo KR (λ ) 0.71069 Å)
Mo KR (λ ) 0.71069 Å)
Rigaku AFC7R
20
24; 13.8-24.5
Rigaku AFC7R
20
10; 9.6-15.6
Rigaku AFC7R
20
18; 14.0-21.0
Rigaku AFC7R
20
19; 14.3-20.8
temperature (°C)
orientation reflns: no.;
range (2θ) (deg)
scan method
ω-2θ
5-50
3870
2159
289
0.9098-1.0000
0.048
0.050
1.24
0.00
0.32
ω-2θ
5-50
7214
1840
492
0.6173-1.0000
0.077
0.070
1.65
0.00
0.42
ω-2θ
ω-2θ
5-51
4719
2898
316
0.9360-1.0000
0.039
0.046
1.41
0.00
0.24
data coll. range, 2θ (deg)
no. of unique data, total
with I > 2.50σ(I)
5-50
3725
1307 (I >2.00σ(I))
277
0.7659-1.0816
0.073
0.067
1.68
0.00
0.38
no. of params refined
correct. factors, max. min.
Ra
b
Rw
quality of fit indicatorc
max. shift/esd. final cycle
largest peak, e-/Å3
min. peak, e-/Å3
-0.26
-0.48
-0.35
-0.22
a
b
2
R ) ∑||Fo| - |Fc||/∑|Fo|. Rw ) [∑w(|Fo| - |Fc|)2/∑w|Fo| ]1/2; w ) 1/σ2(|Fo|). c Quality-of-fit ) [∑w(|Fo| - |Fc|)2/(Nobs - Nparams)]1/2
.
Ta ble 2. Selected Bon d Len gth s (Å)a a n d An gles (d eg)a for Com p lexes 6 a n d 10
Complex 6
Fe-C(3)
1.916(5)
2.021(5)
2.018(5)
2.112(5)
2.261(5)
1.439(7)
134.2(4)
117.7(3)
108.1(4)
113.3(3)
65.6(3)
C(13)-C(14)
1.393(7)
1.404(8)
1.450(8)
1.286(9)
1.393(6)
1.398(8)
119.9(4)
111.7(5)
126.5(5)
104.3(6)
107.1(4)
117.9(4)
N-C(3)
1.358(6)
Fe-C(12)
C(14)-C(15)
O(3)-C(3)
1.331(5)
1.472(6)
1.448(6)
1.509(7)
1.513(5)
124.0(4)
118.0(4)
112.5(4)
111.3(4)
121.1(4)
Fe-C(13)
C(15)-C(16)
N-C(4)
Fe-C(14)
C(16)-C(17)
N-C(20)
Fe-C(15)
O(5)-C(14)
C(4)-C(5)
C(12)-C(13)
Fe-C(3)-O(3)
Fe-C(3)-N
N-C(3)-O(3)
Fe-C(12)-C(4)
Fe-C(15)-C(14)
Fe-C(15)-C(16)
O(5)-C(17)
C(4)-C(12)
C(3)-N-C(20)
C(4)-N-C(20)
N-C(4)-C(5)
C(5)-C(4)-C(12)
C(3)-O(3)-C(18)
C(4)-C(12)-C(13)
C(12)-C(13)-C(14)
C(13)-C(14)-C(15)
C(14)-C(15)-C(16)
C(12)-C(4)-N
C(3)-N-C(4)
124.0(4)
Complex 10
Fe(1)-N(1)
2.11(2)
2.05(2)
2.16(2)
2.00(2)
118(1)
Fe(1)-C(12)
2.08(4)
1.22(2)
1.46(2)
1.41(3)
126(1)
110(1)
109(2)
C(13)-C(14)
1.45(3)
1.45(2)
1.45(3)
1.40(3)
123(2)
Fe(1)-C(13)
O(4)-C(4)
C(14)-C(15)
Fe(1)-C(14)
Fe(1)-C(4)
Fe(1)-C(4)-O(4)
Fe(1)-C(4)-C(5)
Fe(1)-N(1)-C(23)
C(4)-C(5)
N(1)-C(12)
Fe(1)-C(14)-C(15)
C(23)-N(1)-C(12)
N(1)-C(12)-C(13)
N(1)-C(23)
C(12)-C(13)
C(12)-C(13)-C(14)
C(13)-C(14)-C(15)
120(1)
123(1)
124(2)
a
Estimated standard deviations in the least significant figure are given in parentheses.
The final cycle of full-matrix least-squares refinement was
respectively based on 2159, 1840, 1307, and 2898 observed
reflections and 289, 492, 277, and 316 variable parameters and
converged with unweighted and weighted agreement factors
of R ) 0.048 and Rw ) 0.050 for 6, R ) 0.077 and Rw ) 0.070
for 10, R ) 0.073 and Rw ) 0.067 for 13, and R ) 0.039 and
Rw ) 0.046 for 18, respectively. All the calculations were
performed using the teXsan crystallographic software package
of Molecular Structure Corporation.
The details of the crystallographic data and the procedures
used for data collection and reduction information for 6, 10,
13, and 18 are given in Table 1. The 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, and least-squares planes for 6, 10,
13, and 18 are given in the Supporting Information. The
molecular structures of 6, 10, 13, and 18 are given in Figures
1-4, respectively.
Resu lts a n d Discu ssion
Compound [(η4-C4H3OCHdCHCHdNC6H5)Fe(CO)3]
(1), which was synthesized by the reaction of C4H3-
OCHdCHCHdNC6H5 with an equimolar amount of Fe2-
(CO)9 according to the literature method,16 reacted with
about 20-30% molar excess of an aryllithium reagent,
ArLi(Ar )C6H5,p-CH3C6H4,o-,p-CH3OC6H4,p-CF3C6H4),

Remarkable Reactions of (η4-1-azadiene)Fe(CO)3
Organometallics, Vol. 20, No. 11, 2001 2393
elucidated by X-ray structure analysis and on the
literature reports.11,16,25 The upfield chemical shift (ca.
3.39-3.51 ppm) of the proton (3-position) of the furanyl
coordinated to the Fe atom suggests that the aromaticity
of the furan ring was considerably perturbed. This
picture was further supported by X-ray structure de-
termination of complex 6.
IR spectra of complexes 4-8 showed two CO absorp-
tion bands at 2044-1902 cm-1 in the ν(CO) region,
evidence for an Fe(CO)2 moiety in these complexes. The
molecular ion peaks and characteristic fragments pro-
duced by successive loss of CO ligands were shown in
the mass spectra of complexes 5-8; no parent ion but
feature fragments are observed for 4. To unambiguously
confirm their structures, an X-ray diffraction study for
complex 6 was carried out. The results of the X-ray
diffraction work are summarized in Table 1, and the
structure is given in Figure 1.
The molecular structure of complex 6 confirmed that
the aryl group has been added to the carbon end of the
imine unit so that C(4) atom forms three σ bonds to C(5),
C(12), and N atoms with sp3-hybridized orbitals, as
confirmed by the values of the bond angles around C(4)
(C(12)-C(4)-N 107.1(4)°, C(5)-C(4)-C(12) 111.3(4)°,
C(5)-C(4)-N 112.5(4)°). The N atom forms a new bond
with the carbene carbon atom (C(3)). The sum of the
bond angles around C(3) is exactly 360°, indicating that
the C(3) atom forms bonds to Fe, N, and O(3) atoms with
sp2-hybridized orbitals. The Fe, C(3), O(3), and N atoms
lie in a plane. The bond lengths of Fe-C(3), C(3)-N,
and C(3)-O(3) are 1.916(5), 1.358(6), and 1.331(5) Å,
respectively, which indicates that there exists a certain
extent of π bond character in the three bonds. The
coordinated carbon atoms C(12), C(13), C(14), and C(15)
are essentially coplanar to form an η4-alkadiene ligand.
The perpendicular distance from the Fe atom to this
plane is 1.617 Å, and the dihedral angle between the
C(12)C(13)C(14)C(15) plane and the furan ring plane
is 6.71°. Thus, the C(12)C(13)C(14)C(15) plane is ap-
proximately parallel to the furan ring plane. These bond
distances and angles suggest that the Fe, C(3), O(3), N,
C(12), C(13) atoms and the furan ring could form a large
conjugated system to stabilize the complex.
F igu r e 1. Molecular structure of 6, showing the atom-
numbering scheme. Thermal ellipsoids are shown at 45%
probability.
in ether at low temperature (-75 to -35 °C), followed
by alkylation with Et3OBF4 in aqueous solution at 0 °C
or in CH2Cl2 at -60 °C. After separation of the resulting
mixture by chromatography on an alumina column at
-20 to -25 °C and recrystallization from petroleum
ether/CH2Cl2 solution at -80 °C, the orange-yellow
crystalline complexes 4-8 with general composition
[{η4-C4H3OCHdCHCH-(Ar)N(C6H5)C(OC2H5)d}Fe-
(CO)2] were obtained in 62-71% yields. Scheme 1 shows
a possible mechanism for the formation of complexes
4-8. The initial attack of aryllithium reagent on the
iron-coordinated CdN double bond with the addition of
the phenyl group to the carbon atom and Li positive ion
to the N atom of the imine moiety gave rise to the
formation of the intermediate (a). Then the nucleophilic
addition of the N negative ion to a CO ligand of the Fe-
(CO)3 unit occurred, accompanied by dissociation of the
coordination of the Fe atom to the CdN double bond
and the formation of the coordination of the Fe atom to
a double bond of the furanyl group, to generate the
unstable adduct intermediate (b). Subsequent alkylation
of adduct intermediate (b) with Et3OBF4 eventually
converted into the stable chelated carbene complexes
4-8, as that of the chelated (η4-styrene)dicarbonyl-
[ethoxy(amino)carbene]iron complexes.11
The dihedral angle between the plane defined by Fe,
C(3), C(4), and C(12) and the plane comprised of C(12),
C(13), C(14), and C(15) is 77.41°. The FeC(3)C(4)C(12)
plane is, respectively, oriented at angles of 61.02° and
94.59° with respect to the benzene ring C(20)C(21)C-
(22)C(23)C(24)C(25) plane and o-methoxyphenyl ring
C(5)C(6)C(7)C(8)C(9)C(10) plane, while the angle be-
tween the benzene ring plane and the o-methoxyphenyl
ring plane is 93.76°, nearly perpendicular to each other,
to avoid steric repulsion between them.
The orange-yellow complexes 4-8 were soluble in
polar solvents but only slightly soluble in nonpolar
solvents. They are sensitive to air and temperature in
solution but relatively stable in the solid. On the basis
of elemental analyses and spectroscopic evidence, as
well as X-ray crystallography, products 4-8 are formu-
lated as novel chelated furanyl-coordinated alkoxy-
(amino)carbeneiron complexes with an η2-bonding of the
furanyl bonded to the Fe atom, similar to the chelated
(η4-styrene)dicarbonyl[ethoxy(amino)carbene]iron com-
plexes obtained by the reaction of (cinnamaldehyde
anil)iron tricarbonyl with aryllithium reagents (eq 3).11
It is noteworthy that the bond lengths of the two
double bonds of the furan ring in complex 6 are
obviously different from each other; the bond distance
of 1.404(8) Å for (C14)-C(15), which are both coordi-
nated to the Fe atom, is much longer than that of 1.286-
(9) Å for C(16)-C(17). These bond lengths indicate that
the aromaticity of the furan ring is considerably de-
stroyed owing to the coordination of the Fe atom, as
1
anticipated from the H NMR spectrum. More interest-
1
The H NMR spectral data of complexes 4-8 are given
in the Experimental Section, and the assignments of
their resonances are based on the structural information
(25) Victor, R.; Ben-Shoshan, R.; Sarel, S. J . Org. Chem. 1972, 37,
1930.

2394 Organometallics, Vol. 20, No. 11, 2001
Zhang et al.
Sch em e 1
ingly, the bond length of C(12)-C(13), 1.439(7) Å, is
obviously longer than that (1.393(7) Å) of C(13)-(14).
Kruger et al. have proposed that there exist two bonding
arrangements, A and B, in cis-1,3-diene iron com-
plexes.26 Form A emphasizes a π-donation from the
ligand to the metal. Form B emphasizes σ- and π-bond-
ing contributions from the terminal and central carbon
atoms, respectively, and supposedly indicates a stronger
interaction than does form A. In the crystalline state,
form B may be a superior configuration for 6. However,
based on the traditional presentation, complexes 4-8
show that form A rather than form B is the best
description of the diene-iron bonding.
Unexpectedly, when p-CH3OC6H4Li and p-CF3C6H4-
Li were used as nucleophiles for the reaction with
compound 2, no analogous η4-azadiene-coordinated acyl-
iron complexes but novel η2-azadiene-coordinated acyl-
iron inner salt complexes [{η2-C4H3OCHdCHCHd
N(C2H5)C6H11}Fe(CO)3(COC6H4OCH3-p)] (13) and [{(η2-
C4H3OCHdCHCHdN(C2H5)C6H11}Fe(CO)3(COC6H4CF3-
p)] (14) (Scheme 3) were obtained in >70% yields,
respectively.
The formulas of complexes 9-12 and 13, 14 shown
in Schemes 2 and 3, respectively, are supported by
microanalytical and spectroscopic data as well as X-ray
crystallography. A possible reaction pathway to com-
plexes 9-12 (Scheme 2) could involve the acylmetalate
intermediates (a) formed by initial attack of aryllithium
nucleophiles on one of the three CO ligands. The fact
that the acylmetalate intermediate (a) formed upon
subsequent alkylation with Et3OBF4 in CH2Cl2 solution
gave the acyliron complexes 9-12 having a 17-electron
configuration for the acyliron moiety suggests that an
oxidation of intermediate (a) to lose one electron oc-
curred in the alkylation step. Apparently, the triethy-
loxonium tetrafluoroborate (Et3OBF4) acts as an oxidant
of Fe(0) to Fe(I) in the reaction. Analogous transforma-
tion and oxidation of the central iron have been previ-
ously observed in the reactions of tricarbonyl(η4-
cyclopenta-1,3-diene)iron and (cyclooctatetraene)diiron
hexacarbonyl with aryllithium reagents followed by
alkylation with Et3OBF4, which gave the acyldicarbonyl-
(η5-cyclopentadienyl)iron complexes [η5-C5H5Fe(CO)2-
(COAr)]27 and the 16e (8,8-dihydro-1-4-η:5-7-η-cyclo-
octatrienyl)tricarbonylirondicarbonyl(arylformacyl)iron
complexes [(CO)3Fe(1-4-η:5-7-η-C8H9)(CO)2Fe(COAr)],28
respectively. However, it is not yet clear how the
oxidation of the central iron occurred during the reaction
and what factors promote the formation of these stable
17e complexes. The formation of complexes 13 and 14
To explore the effect of different azadiene ligands on
the reactivities of (1-azadiene)Fe(CO)3 complexes and
reaction products, an attempt was made at the reaction
of [(η4-C4H3OCHdCHCHdNC6H11)Fe(CO)3] (2) and [(η4-
C6H5CHdCH-CHdNC6H11)Fe(CO)3] (3), where the aryl
substituents on the azadiene ligand are a furanyl and
a phenyl, respectively, and the substituent at the N
atom of the azadiene ligand is a cyclohexyl group, with
aryllithium reagents under similar conditions. Thus,
compound 2 reacted with about 15-30% molar excess
of an aryllithium reagents, ArLi (Ar ) C6H5, o-, m-,
p-CH3C6H4), in ether at low temperature (-75 to -35
°C), followed by alkylation with Et3OBF4 in CH2Cl2 at
-65 to -30 °C. After workup as described in the
Experimental Section, novel η4-azadiene-coordinated
17e acyliron complexes [{η4-C4H3OCHdCHCHdNC6H11}-
Fe(CO)2(COAr)] (9-12) (Scheme 2) were obtained in
73-82% yields.
(27) Chen, J .-B.; Yin, J .-G.; Lei, G.-X. J . Chem. Soc., Dalton Trans.
1989, 635.
(28) Yu, Y.; Sun, J .; Chen, J .-B. J . Organomet. Chem. 1997, 533,
13.
(26) Kruger; C.; Barnett, B. L.; Brauer, D. In The Organic Chemistry
of Iron; Koerner, E. A., Ed.; Academic Press: New York, 1978; Vol. 1,
p 17.

Remarkable Reactions of (η4-1-azadiene)Fe(CO)3
Organometallics, Vol. 20, No. 11, 2001 2395
Sch em e 2
Sch em e 3
Ta ble 3. Selected Bon d Len gth s (Å)a a n d An gles (d eg)a for Com p lexes 13 a n d 18
13
18
13
18
Fe-C(1)
1.78(1)
1.76(2)
1.80(1)
2.10(1)
2.10(1)
2.10(1)
1.34(1)
178(1)
178(1)
175(1)
120(1)
122(1)
93.3(9)
70.2(8)
70.3(8)
1.777(4)
1.775(4)
1.807(4)
2.073(3)
2.136(3)
2.116(3)
1.329(4)
177.0(3)
176.4(3)
174.6(3)
121.5(3)
121.9(3)
94.0(2)
N-C(21)
1.58(2)
1.50(2)
1.39(2)
1.42(2)
1.46(2)
1.20(1)
1.49(2)
121.5(10)
121(1)
122(1)
125(1)
100(1)
122(1)
122(1)
117(3)
1.472(4)
1.485(4)
1.402(4)
1.421(4)
1.477(4)
1.225(4)
1.510(5)
122.7(2)
122.4(3)
120.2(3)
126.1(3)
114.2(3)
123.0(3)
123.2(3)
116.5(3)
Fe-C(2)
N-C(23)
Fe-C(3)
C(12)-C(13)
Fe-C(4)
C(13)-C(14)
Fe-C(13)
C(14)-C(15)
Fe-C(14)
O(4)-C(4)
N-C(12)
C(4)-C(5)
Fe-C(1)-O(1)
Fe-C(2)-O(2)
Fe-C(3)-O(3)
Fe-C(4)-O(4)
Fe(1)-C(4)-C(5)
Fe-C(13)-C(12)
Fe-C(13)-C(14)
Fe-C(14)-C(13)
Fe-C(14)-C(15)
C(12)-N-C(21)
C(12)-N-C(23)
N-C(12)-C(13)
N-C(21)-C(22)
C(12)-C(13)-C(14)
C(13)-C(14)-C(15)
O(4)-C(4)-C(5)
69.7(2)
71.2(2)
a
Estimated standard deviations in the least significant figure are given in parentheses.
(Scheme 3) could proceed via an analogous acylmetalate
intermediate (a), which was then converted into another
unstable intermediate (b) by abstracting one molecule
of CO generated from decomposition of unstable inter-
mediate (a) accompanied by dissociation of the coordina-
tion of the Fe to the CdN double bond. Subsequently,
such an intermediate (b) can react with alkylating
reagent Et3OBF4 to achieve electron charge equilibrium
and be converted into the stable N-alkylation products
13 and 14.
The yellow complexes 9-12 and 13, 14 are only
soluble in polar organic solvents and sensitive to air and
temperature in solution but stable for a short period on
exposure to air at room temperature in the crystalline
1
state. The IR spectra, the solution H NMR spectra, and
mass spectra are consistent with the proposed structure

2396 Organometallics, Vol. 20, No. 11, 2001
Zhang et al.
F igu r e 2. Molecular structure of 10, showing the atom-numbering scheme. Thermal ellipsoids are shown at 45% probability.
F igu r e 4. Molecular structure of 18, showing the atom-
numbering scheme with 45% thermal ellipsoids.
F igu r e 3. Molecular structure of 13, showing the atom-
numbering scheme with 40% thermal ellipsoids.
dissociation of the Fe to the CdN double bond and the
shown in Schemes 2 and 3, respectively. The IR spectra
of 9-12 and 13, 14 in CH2Cl2 solution showed an
absorption band at 1586-1607 cm-1, which is charac-
teristic of the acyl ligand, besides the two or three
terminal CO absorption bands in the ν(CO) region. In
bonding of C2H5 group to the N atom. As a result, the
structure of the azadiene ligand consists of an η2-
coordinated CdC double bond and a free CdN double
bond with an ethyl group bonded to the N atom. Thus,
the proton signals of the original azadiene ligand shifted
accordingly. In the 1H NMR spectra of 13 and 14, a
triplet (ca. 2.01-1.06 ppm), a quartet (ca. 3.67-3.38
ppm), and a set of multiplet (ca. 7.95-6.96 ppm) bands
were observed from both complexes, which showed
characteristically the presence of the ethyl and aryl
groups. The molecular ion peaks or characteristic frag-
ments produced by successive loss of CO ligands were
1
the H NMR spectra of 9-12, the chemical shifts of the
protons of the η4-azadiene ligand were similar to those
of (η4-1-azadiene)tricarbonyliron compound 2,16 indicat-
ing that the principal framework remained in these
1
complexes, while the H NMR spectra of complexes 13
and 14 showed complicated proton signals attributed
to the azadiene ligand arising from the coordinating

Remarkable Reactions of (η4-1-azadiene)Fe(CO)3
Organometallics, Vol. 20, No. 11, 2001 2397
Sch em e 4
observed in the mass spectra of 9-12 and 13, 14. The
acyl ions (COAr+) are observed for all complexes of 9-12
and 13, 14.
distance of1.78 Å is somewhat shorter than that found
in [{(η2-C6H5CHdCHCHdN(C2H5)(2,4-Me2C6H3)}Fe-
(CO)3C6H5] (1.803 Å).12 The Fe-C bond lengths of the
C(4), C(13), and C(14) in 13 are the same (2.10(1) Å).
The C(12)-C(13) and C(13)-C(14) bond lengths are
1.39(2) and 1.42(2) Å, respectively, which are between
the normal C-C and CdC distances; the C(12)-N bond
length of 1.34(1) Å is also between the normal C-N and
CdN distances. The N, C(12), C(13), and C(14) atoms
are coplanar, with a N-C(12)-C(13) angle of 125(1)°,
a C(12)-C(13)-C(14) angle of 122(1)°, and a C(13)-
C(14)-C(15) angle of 122(1)°. Thus, the N, C(12), C(13),
and C(14) atoms construct a conjugate system, and the
C(12)-C(13) bond adopts steric stable s-trans configu-
ration. The dihedral angle between the plane defined
by N, C(12), C(13), and C(14) and the furan ring C(15)C-
(16)C(17)C(18)O(6) plane is only 13.52°, being ap-
proximately coplanar. Moreover, the C(14)-C(15) bond
length is 1.46(2) Å, which is intermediate between C-C
single-bond and CdC double-bond distances. The shorter
C(14)-C(15) distance suggests some π-bond character
between the C(14) atom and C(15) atom of the furan
ring in 13. Thus, the N, C(12), C(13), and C(14) atoms
and the furan ring could form a large conjugate system,
which could favorably disperse and neutralize the
positive and negative charge on the Fe and N atoms to
stabilize the complex.
The structures of complexes 9-12 and 13, 14 have
been further confirmed by X-ray crystallography of 10
and 13, respectively. In complex 10, one of the CO
groups of the Fe(CO)3 moiety has been converted into
an acyl group (Figure 2). The structure of 10 resembled
that of [(η4-C4H3OCHdCHCHdNC6H11)Fe(CO)3] (2),16
except that the substituents on the Fe atom are two CO
groups and one acyl group in 10 but three CO ligands
in the latter. It is interesting that complex 10 crystal-
lizes with two independent molecules and one THF
solvent molecule in the asymmetric unit. The two
molecules in the unit cell are nearly the same. The Fe
atom shows an approximately square pyramidal coor-
dination sphere with the azadiene ligand situated in the
square plane. The complex consists of a 1-azadiene
ligand adopting an s-cis conformation with respect to
the central C(12)-C(13) bond in the azadiene chain. By
comparison with 2, the C-N bond (1.41(3) Å) of the
azadiene is lengthened by 0.70 Å arising from the
bonding of electron-withdrawing acyl to the Fe atom,
leading to further weakness of the CdN bond of the
azadiene ligand. The C(12)-C(13) bond length of
1.40(3) Å in 10 is slightly shorter than the corresponding
distance in 2 (1.415(4) Å),16 whereas the C(13)-C(14)
distance (1.45(3) Å) is significantly longer than the
corresponding distance in 2 (1.414(4) Å).16 The Fe-C
bond lengths of the C(12) and C(13) atoms, 2.08(4) and
2.05(2) Å, respectively, are similar to those of 2.
Complex 10 is a 17-electron species for the acyliron
moiety, in which the 17 electrons participating in the
central metal valence configuration consist of the eight
electrons of the Fe atom, two pairs of electrons provided
by the two CO ligands, and the other five electrons, one
of which is a σ-electron, provided by the acyl group
ligating the Fe atom in an end-on mode, and four of
which are the π-electrons provided by an η4-bonding
orbital of the azadiene ligand bonded to the Fe atom.
The structure of 13 (Figure 3) resembled that of
analogous aryliron inner salt complex [{η2-C6H5CHd
CHCHdN(C2H5)(2,4-Me2C6H3)}Fe(CO)3C6H5]12 obtained
by the reaction of [(η4-C6H5CHdCHCHdN(2,4-Me2C6H3)-
Fe(CO)3] with C6H5Li (eq 4). The average Fe-C(CO)
The angles between the benzene ring plane comprised
of C(5) through C(10) and the NC(12)C(13)C(14) plane
and the C(5)C(6)C(7)C(8)C(9)C(10) and furan ring
C(15)C(16)C(17)C(18)O(6) planes are 99.27° and 89.49°,
respectively. Thus, the benzene ring plane of the meth-
oxyphenyl group is perpendicularly warped toward both
the NC(12)C(13)C(14) and C(15)C(16)C(17)C(18)O(6)
planes due to intramolecular steric hindrance and
intermolecular accumulation.
Analogous η4-azadiene-coordinated 17e acyliron com-
plexes [{η4-C6H5CHdCH-CHdNC6H11}Fe(CO)2(COAr)]
(15, Ar ) C6H5; 16, Ar ) m-CH3C6H4; 17, Ar )
p-CH3C6H4) (Scheme 4) and acyliron inner salt com-
plexes [{η2-C6H5CHdCHCHdN-(C2H5)C6H11}Fe(CO)3-
(COC6H4OCH3-p)] (18) (Scheme 5) were also obtained
in 79-80% and 55% yield, in the reaction of [(η4-C6H5-
CHdCHCHdNC6H11)Fe(CO)3] (3) with aryllithium re-

2398 Organometallics, Vol. 20, No. 11, 2001
Zhang et al.
Sch em e 5
agents C6H5Li, m-CH3C6H4Li, p-CH3C6H4Li, and p-CH3-
OC6H4Li, respectively.
Thus, as in 13, the conjugate system comprised of N,
C(12), C(13), and C(14) atoms can also form a large
conjugate system with the benzene ring to disperse and
neutralize the positive and negative charge on the Fe
and N atoms to stabilize the complex.
Of special interest are the reactions of 3 with aryl-
lithium reagents o-CH3C6H4Li, o-CH3OC6H4Li, and
p-CF3C6H4Li. Their reactions under the same conditions
gave no expected η4-azadiene-coordinated acyliron com-
plexes or acyliron inner salt complexes but η2-azadiene-
coordinated aryliron inner salt complexes [{η2-C6H5-
CHdCHCHdN(C2H5)C6H11}Fe(CO)3Ar] (19-21) (Scheme
6) in 60-80% yields.
The formulas for complexes 19-21 shown in Scheme
6 are based on elemental analysis and spectroscopic
evidence (Experimental Section), and their structures
are established by an X-ray diffraction study of 19,29
which gave an R value of 0.20 due to serious decay.
However, the IR, 1H NMR, and mass spectra are
consistent with this geometry. The IR spectra in the
ν(CO) region of 19-21 showed three terminal CO
absorption bands, similar to that of [{η2-C6H5CHd
CHCHdN(C2H5)(2,4-Me2C6H3)}Fe(CO)3C6H5].12 In the
1H NMR spectra of 19-21, the chemical shifts of the
two protons on the η2-coordinating CdC double bond of
the azadiene ligand (4.11-3.36 and 5.38-4.87 ppm) is
similar to those (3.97-3.89 and 6.64-6.52 ppm)12 of
[{η2-C6H5CHdCHCHdN(C2H5)(2,4-Me2C6H3)}Fe(CO)3-
Ar] (Ar ) C6H5, p-ClC6H4). In contrast to complex 18,
the IR spectra of complexes 19-21 showed no acyl
absorption band in the ν(CdO) region, and the mass
spectra of 19-21 showed no characteristic acyl (COAr+)
fragments but aryl (Ar+) fragment peaks.
A possible reaction pathway to complexes 19-21
(Scheme 6) could involve initial formation of acylmeta-
late intermediates (a), analogous to that of complexes
13 and 14 (Scheme 3) and 18 (Scheme 5). The unstable
intermediate (a) was then alkylated at the N atom
accompanied by coordinating dissociation of Fe to the
CdN double bond and aryl migration from acylcarbonyl
carbon to the Fe atom, resulting in the formation of the
stable N-alkylation products 19-21. The formation of
19-21 is not surprising since analogous η2-azadiene-
The formulas of complexes 15-17 and 18, shown in
Schemes 4 and 5, respectively, were supported by
microanalytical and spectroscopic data, among which 18
has been further confirmed by its X-ray single-crystal
structure determination. Complexes 15-17 are assigned
to the analogous 17e structure since their spectral data
are similar to those of complexes 9-12. The IR spectra
of 15-17 in CH2Cl2 solution showed an absorption band
at 1597-1603 cm-1, indicating characteristically the
presence of the acyl ligand, besides the two terminal
CO absorption bands in the ν(CO) region. In the 1H
NMR spectra of 15-17, the chemical shifts of the
protons at the coordinated CdC and CdN double bonds
of the azadiene ligand are very similar to those of
complexes 9-12. Likely, complex 18 is assigned to a
similar structure since its spectral data are similar to
those of 13 and 14. The possible reaction pathways to
complexes 15-17 (Scheme 4) and 18 (Scheme 5) would
be analogous to those of complexes 9-12 (Scheme 2) and
complexes 13 and 14 (Scheme 3), respectively.
The structure of complex 18 shown in Figure 4 is very
similar to that of 13, except that the substituent on the
azadiene ligand is a phenyl group in 18 but a furanyl
group in 13. Many structural features of 18 are es-
sentially the same as those in 13: the Fe-C bond
lengths of C(4), C(13), and C(14), the bond distances of
C(12)-C(13), C(13)-C(14), and N-C(12), the dihedral
angle between the NC(12)C(13)C(14) plane and the
benzene ring C(15)C(16)C(17)C(18)C(19)C(20) plane,
and the angles between the benzene ring plane com-
prised of C(5) through C(10) and the NC(12)C(13)-C(14)
plane and the C(5)C(6)C(7)C(8)C(9)C(10) and the ben-
zene ring C(15)C(16)C(17)C(18)C(19)C(20) planes. Ap-
parent differences in the structures of 13 and 18 are
the shorter N-C(21) (1.472(4) Å) and N-C(23)
(1.485(4) Å) bonds in 18 as compared to 13 (1.58(2) Å
for N-C(21) and 1.50(2) Å for N-C(23)) arising from
the different aryl substituent on the azadiene ligand.
The NC(12)C(13)C(14) plane is oriented at an angle of
20.42° with respect to the benzene ring C(5) though
C(10) plane, being approximately parallel to each other.
The C(14)-C(15) bond length is 1.477(4) Å, which is
shorter than the normal C-C single-bond distance.
(29) Sun, J .; Chen, J .-B. Unpublished work.

Remarkable Reactions of (η4-1-azadiene)Fe(CO)3
Organometallics, Vol. 20, No. 11, 2001 2399
Sch em e 6
coordinated aryliron inner salt complexes have been
observed in the reaction of [{η4-C6H5CHdCHCHdN(2,4-
Me2C6H3)}Fe(CO)3], where the substituent on the N
atom is an electron-pushing 2,4-dimethylphenyl group
as that of the cyclohexyl group, with aryllithium re-
agents (eq 4).12
aryllithium reagents to afford the chelated furanyl-
coordinated alkoxy(amino)carbeneiron complexes (Scheme
1), while the analogous reactions of compound 2, where
the substituent at the N atom is a cyclohexyl group, gave
novel η4-azadiene-coordinated 17e acyliron complexes
(Scheme 2). Likewise, compound 3, where the substitu-
ent at the N atom is also a cyclohexyl group, reacted
with aryllithium reagents yielding η4-azadiene-coordi-
nated 17e acyliron complexes, η2-azadiene-coordinated
acyliron inner salt complexes, or η2-azadiene-coordinat-
ed aryliron inner salt complexes (Scheme 6) based on
the aryllithium reagents used. The title reaction offers
a new and useful method for the preparation of the
chelated heteroatomic carbene complexes or their isomer-
ized products and enriches the chemistry of (1-azadi-
ene)Fe(CO)3 complexes.
The title reaction encompasses a variety of reactions
of (η4-1-azadiene)Fe(CO)3 complex with aryllithium
reagents. The formation of the various reaction products
depends not only on the azadiene ligand and the
substituents at the N atom of the azadiene ligand but
also on the different aryllithium reagents used. The
reaction results show that the azadiene ligand with
different aryl substituents exerts no great influence
upon the reation products. For example, compound 1
and (cinnamaldehyde anil)iron tricarbonyl, where the
aryl substituents on the azadiene ligand are a furanyl
and a phenyl, respectively, reacted with aryllithium
reagents to give analogous chelated alkoxy(amino)-
carbeneiron complexes (eq 3 and Scheme 1); compound
2 and 3, where the aryl substituents on the azadiene
ligand also are a furanyl and a phenyl, reacted with
aryllithium reagents to produce analogous η4-azadiene-
coordinated 17e acyliron complexes (Schemes 2 and 4)
or η2-azadiene-coordinated acyliron inner salt complexes
(Schemes 3 and 5) based on the aryllithium reagents
used. However, the substituents at the N atom of the
azadiene ligand exert a great influence on the resulting
products. For instance, compound 1, where the sub-
stituent at the N atom is a phenyl group, reacted with
Ack n ow led gm en t. Financial support from the Na-
tional Natural Science Foundation of China and the
Science Foundation of the Chinese Academy of Sciences
is gratefully acknowledged.
Su p p or tin g In for m a tion Ava ila ble: Tables of the posi-
tional parameters and Biso/Beq, H atom coordinates, anisotropic
displacement parameters, complete bond lengths and angles,
and least-squares planes for 6, 10, 13, and 18. This material
is available free of charge via the Internet at http://pubs.acs.org.
OM010034V