Novel thermolytic products and their structures derived from thermolysis of isomerized products of spiro[4.4]nona-1,3-diene(dicarbonyl)[ethoxy(aryl)carbene]iron phosphine adducts [(η3-C9H12)Fe{C(OC2H5)Ar}(CO)2PPh3]

Article abstract of DOI:10.1016/j.ica.2007.11.029

Heating a benzene solution of the isomerized product of spiro[4.4]nona-1,3-diene(dicarbonyl)[ethoxy(aryl)carbene]iron phosphine adduct [(η³-C₉H₁₂)Fe{C(OC₂H₅)(C₆H₄CH₃-o)}(CO)₂PPh₃] (1) in a sealed quartz tube at 85-90 °C for 72 h gave the ring-opened η⁴ olefin-coordinated dicarbonyliron phosphine complex [Fe{η⁴-C₅H₇CH{double bond, long}CHCH₂CH{double bond, long}C(OC₂H₅)C₆H₄CH₃-o}(CO)₂PPh₃] (3) and cyclobutane derivative [C₂₄H₂₂O₇] (4). The thermal decomposition of analogous isomerized product [(η³-C₉H₁₂)Fe{C(OC₂H₅)(C₆H₄CH₃-p)}-(CO)₂PPh₃] (2) afforded the corresponding η⁴ olefin-coordinated dicarbonyliron phosphine complex [Fe{η⁴-C₅H₇CH{double bond, long}CHCH₂CH{double bond, long}C(OC₂H₅)C₆H₄CH₃-p}(CO)₂PPh₃] (6) and compound 4. The structures of products 3 and 4 have been established by X-ray diffraction studies.

Full text of DOI:10.1016/j.ica.2007.11.029

Available online at www.sciencedirect.com
Inorganica Chimica Acta 361 (2008) 3171–3176
www.elsevier.com/locate/ica
Novel thermolytic products and their structures derived
from thermolysis of isomerized products
of spiro[4.4]nona-1,3-diene(dicarbonyl)[ethoxy(aryl)carbene]iron
phosphine adducts [(g3-C9H12)Fe{C(OC2H5)Ar}(CO)2PPh3]
Nu Xiao a, Jie Sun a, Huping Zhu a, Nobuko Tsumori b,*, Jiabi Chen a,*
a State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Lu, Shanghai 200032, China
b Toyama National College of Technology, 13 Hongo-machi, Toyama-shi 939-8630, Japan
Received 29 August 2007; received in revised form 16 November 2007; accepted 20 November 2007
Available online 4 March 2008
This paper is dedicated to Professor Robert J. Angelici, Department of Chemistry, Iowa State University, on the occasion of his retirement and 70th
birthday and recognition of his brilliant contribution to organometallic chemistry.
Abstract
Heating a benzene solution of the isomerized product of spiro[4.4]nona-1,3-diene(dicarbonyl)[ethoxy(aryl)carbene]iron phosphine
adduct [(g3-C9H12)Fe{C(OC2H5)(C6H4CH3-o)}(CO)2PPh3] (1) in a sealed quartz tube at 85–90 °C for 72 h gave the ring-opened g4
olefin-coordinated dicarbonyliron phosphine complex [Fe{g4-C5H7CH@CHCH2CH@C(OC2H5)C6H4CH3-o}(CO)2PPh3] (3) and cyclo-
butane derivative [C24H22O7] (4). The thermal decomposition of analogous isomerized product [(g3-C9H12)Fe{C(OC2H5)(C6H4CH3-p)}-
(CO)2PPh3] (2) afforded the corresponding g4 olefin-coordinated dicarbonyliron phosphine complex [Fe{g4-C5H7CH@CHCH2CH@
C(OC2H5)C6H4CH3-p}(CO)2PPh3] (6) and compound 4. The structures of products 3 and 4 have been established by X-ray diffraction
studies.
Ó 2007 Elsevier B.V. All rights reserved.
Keywords: Thermolytic product; Crystal structure; Isomerized product; Thermolysis
1. Introduction
ined widely; a great number of olefin-coordinated metal
carbene complexes and/or isomerized products were syn-
thesized, and a series of novel isomerizations of olefin
ligands have been observed by the reactions of olefin-
ligated metal carbonyls with aryllithium reagents followed
by alkylation with alkylating agents in our laboratory
[6–12]. However, only very little is known [6a,13] about
the reactivity of these olefin-coordinated metal carbene
complexes and their isomerized products.
It is well known that the thermal decomposition of car-
bene complexes usually results in dimerization of the car-
bene ligand to produce alkene derivatives [14] and that
heating a Fischer-type carbene complex with an olefin gen-
erally results in addition of the double bond of the olefin to
The considerable interest in the synthesis, structure, and
chemistry of alkene-coordinated transition-metal carbene
complexes stems largely from the possible involvement of
these species in many reactions catalyzed by organometallic
compounds [1,2]. Especially, the alkene–metal carbene
complexes are important intermediates in various reactions
of metal carbene complexes with alkenes [3–5]. In recent
years, olefin-coordinated transition-metal carbene com-
plexes and/or their isomerized products have been exam-
*
Corresponding authors. Tel.: +86 21 54925355; fax: +86 21 64166128.
E-mail address: chenjb@mail.sioc.ac.cn (J. Chen).
0020-1693/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2007.11.029

3172
N. Xiao et al. / Inorganica Chimica Acta 361 (2008) 3171–3176
the carbene ligand to form cyclopropane products [15,16].
Recently, we have shown a number of thermolysis reac-
tions of the olefin-coordinated monoiron alkoxycarbene
complexes or their isomerized products and the COT-coor-
dinated diiron Fischer-type carbene complexes which pro-
duced a series of novel thermolytic products [13b,17,18].
For example, the thermolysis of ring-opened norbornadi-
ene alkoxycarbene complexes [g3-C7H8(CO)2FeC(OC2H5)-
Ar] (Ar = C6H5, p-CH3C6H4) afforded novel diiron dimers
[{Fe2(l-CO)(CO){g5-C5H4CH2CH2COAr}2] (Eq. (1)) [17],
and the thermolysis of isomerized (limonene)(alkoxycar-
bene)iron complex [(g3-C10H16)(CO)2FeC(OC2H5)Ar]
(Ar = o-CH3C6H4, p-CF3C6H4) produced the g4 cycloole-
fin-coordinated tricarbonyl iron complexes [{g4-C10H15-
CH(OC2H5)C6H5}Fe(CO)3] (Eq. (1)) [17]. While the
thermal
alkylation with Et3OBF4 and subsequent transformation
with PPh3 yielded the g3 cycloolefin-coordinated dicarbon-
yliron phosphine adducts [(g3-C9H12)Fe{C(OC2H5)Ar}-
(CO)2PPh3] (Ar = o-CH3C6H4, p-CH3C6H4) (Eq. (4))
[19], which we call the isomerized products of spiro[4.4]-
nona-1,3-diene(dicarbonyl)[ethoxy(aryl)carbene]iron phos-
phine adducts or the isomerized spiro[4.4]nona-1,
3-diene(dicarbonyl)[ethoxy(aryl)carbene]iron
phosphine
adducts. The structures of these phosphine adducts have
been confirmed by the X-ray crystallographic studies.
Ar
PPh
OC H
2
1) ArLi / Et
O
3
5
2
c
C
2) Et OBF
3
4
Ar
Fe
Fe
OC H
Fe
2
5
CO
CO
OC
Ph P
3
OC
CO
CO
CO
CO
R
Ar = o-CH C H (1)
3
6 4
p-CH C H (2)
4
6
3
O
OC
O
ð4Þ
C
Fe
Fe
3
O
CO
C
O
To further explore the thermolysis reactivity of the
benzene
Fe
CO
isomerized products of the cycloolefin-coordinated alkoxy-
carbene iron complexes and their application in organome-
tallic and organic synthesis, we investigated the thermolysis
reactions of isomerized products of spiro[4.4]nona-1,
CO
sealed tube
R = H, p-CH
80 — 90 ºC
R
OC2H5
70 — 72 h
c
OC2H5
R
R
Fe
3-diene(dicarbonyl)[ethoxy(aryl)carbene]iron
phosphine
OC
CO
R = H, o-, p-CH , p-CF
adducts [(g3-C9H12)Fe{C(OC2H5)Ar}(CO)2PPh3] (1, Ar =
o-CH3C6H4; 2, Ar = p-CH3C6H4), which produced the
novel thermal decomposition products. Herein we report
these unusual thermolysis reactions and the structures of
the novel thermolytic products.
CO
R = o-CH , p-CF
3
3
3
3
ð1Þ
decomposition of isomerized products of the (cycloocta-
tetraene)(ethoxycarbene)iron complexes [g3-C8H8(CO)2Fe-
C(OC2H5)C6H4CH3-o] and [g4-C8H8(CO)2FeC(OC2H5)-
C6H4CH3-p] produced the head-bridged cyclooctatriene
derivatives [C8H8C(OC2H5)C6H4CH3-o] (Eq. (2)) and
[C8H7(OC2H5)C(H)C6H4CH3-p] (Eq. (3)), respectively,
via C–C bond formation or ethoxy migration [17]. We
are now interested in further examining the thermolysis
reactivity of such isomerized products of the cycloolefin-
coordinated metal alkoxycarbene complexes.
2. Experimental
2.1. General procedure and materials
All procedures were performed under a dry, oxygen-free
N2 atmosphere by using standard Schlenk techniques. All
solvents employed were reagent grade and dried by reflux-
˚
ing over appropriate drying agents and stored over 4 A
molecular sieves under N2 atmosphere. Benzene was dis-
tilled from sodium, while petroleum ether (30–60 °C) and
CH2Cl2 were distilled from CaH2. The neutral alumina
(Al2O3, 100–200 mesh) used for chromatography was deox-
ygenated at room temperature under high vacuum for 16 h,
deactivated with 5% w/w N2-saturated water, and stored
under N2 atmosphere. Compounds 1 and 2 were prepared
as previously described [19].
The IR spectra were measured on a Nicolet AV-360
spectrophotometer using NaCl cells with 0.1 mm spacers.
The 1H NMR and 13C NMR spectra were recorded at
ambient temperature in acetone-d6 solution with TMS as
the internal reference using a Varian Mercury 300 spec-
trometer running at 300 MHz. Electron ionization mass
spectra (EIMS) were run on a Hewlett–Packard 5989A
spectrometer. HRMS spectrum was measured on Finnigan
C2H5O
benzene
CH3
C
OC2H5
CH3
ð2Þ
ð3Þ
sealed tube
90 ºC, 72 h
Fe
OC
CO
CH
3
H
benzene
C
OC H
2 5
Fe
sealed tube
90 ºC, 72 h
OC
CO
OC H
2
5
CH
3
We previously reported that the reactions of spiro[4.4]-
nona-1,3-diene(tricarbonyl)iron with aryllithium reagents
ArLi (Ar = o-CH3C6H4, p-CH3C6H4) followed by the

N. Xiao et al. / Inorganica Chimica Acta 361 (2008) 3171–3176
3173
MAT 8430 spectrometer. Melting points obtained on sam-
ples in sealed nitrogen-filled capillaries are uncorrected.
72 h. Further treatment as described for the thermolysis
of 1 in benzene gave 0.049 g (39%) of 3, 0.011 g (12%) of
4, and 0.038 g (29%) of 5, which were identified by their
2.2. Thermolysis of [(g3-C9H12)Fe{C(OC2H5)(C6H4CH3-
o)}(CO)2PPh3] (1) in benzene to give [Fe{g4-C5H7CH@
CHCH2CH@C(OC2H5)C6H4CH3-o}(CO)2PPh3] (3),
[C24H22O7] (4), and [Fe(CO)3(PPh3)2] (5)
IR and H NMR spectra.
1
2.4. Thermolysis of [(g3-C9H12)Fe{C(OC2H5)(C6H4CH3-
p)}(CO)2PPh3] (2) to give [Fe{g4-C5H7CH@CHCH2-
CH@C(OC2H5)C6H4CH3-p}(CO)2PPh3] (6),
[C24H22O7] (4), and [Fe(CO)3(PPh3)2] (5)
Compound 1 (0.130 g, 0.20 mmol) was dissolved in ben-
zene (30 mL) in a quartz tube. The tube was cooled at
ꢀ80 °C to freeze the benzene solution and sealed under high
vacuum. The sealed tube was heated to 90–95 °C for 72 h,
during which time the red solution turned dark turbid.
After cooling, the dark yellow solution was evaporated in
vacuo to dryness. The residue was chromatographed on
Al2O3 with petroleum ether as the eluant. The orange–
yellow band which was eluted first and collected. Then a
yellow band was eluted with petroleum ether/CH2Cl2
(10:1) and a third light yellow band was eluted with petro-
leum ether/CH2Cl2/Et2O (10:1:1). After vacuum removal of
the solvent from the above three eluates, the residues were
recrystallized from petroleum ether/CH2Cl2 or petroleum
ether/Et2O at ꢀ80 °C. From the first orange fraction,
0.036 g (27%) of golden yellow crystals of 5 [20] was
obtained: m.p. 262–266 °C dec (lit. [20a] 264–270 °C); IR
Using the same procedures described above, compound
2 (0.150 g, 0.23 mmol) in benzene (30 mL) in a quartz tube
was heated at 90–95 °C for 72 h. Subsequent treatment of
the black resulting solution as described for the thermolysis
of 1 afforded 0.058 g (40%) of yellow crystalline 6, 0.015 g
(16%) of 4 and 0.038 g (28%) of 5. Products 4 and 5 were
1
identified by their IR and H NMR spectra. Product 6:
m.p. 118–120 °C dec.; IR (CH2Cl2) m(CO) 1960 (vs),
1894(s) cmꢀ1 1H NMR (CD3COCD3) d 7.41–7.33 (m,
;
15H, PPh3), 7.21–7.15 (m, 4H, p-CH3C6H4), 5.03 (dd,
1H, J = 8.6 Hz, H4), 4.56 (t, 1H, J = 7.6 Hz, H11), 3.62
(q, 2H, J = 7.7 Hz, OCH2CH3), 2.81 (m, 1H, H9), 2.52
(m, 1H, H9), 2.13 (s, 3H, p-CH3C6H4), 1.75 (m, 6H,
H
10,7,8), 1.18 (t, 3H, J = 7.8 Hz, OCH2CH3), 0.23 (d, 1H,
J = 13.5 Hz, H6), ꢀ0.94 (m, 1H, H3); 13C NMR
(CD3COCD3) d 215.6 (CO), 154.1, 137.0, 136.6, 136.2,
132.8, 132.7, 133.1, 130.3, 129.6, 129.4, 129.1, 128.1,
128.3, 128.2, 125.6, 112.7, 101.9, 79.6, 68.7, 63.5, 60.4,
41.3, 32.6, 31.5, 31.2, 22.5, 18.8, 14.2; MS m/e 586
(M+ꢀ2CO), 324 (M+ꢀ2COꢀPPh3), 268 [M+ꢀPPh3ꢀ
Fe(CO)2], 262 ðPPh3þÞ. Anal. Calc. for C39H39O3PFe: C,
72.90; H, 6.12. Found: C, 72.52; H, 6.48%.
1
(CH2Cl2) m(CO) 1982 (vs) cmꢀ1 (lit. [20a] 1883 cmꢀ1); H
NMR (CDCl3) d 7.26 (s, br); MS m/e 636 (M+ꢀCO), 608
(M+ꢀ2CO), 580 (M+ꢀ3CO), 262 ðPPh3þÞ. From the sec-
ond yellow fraction, 0.052 g (41%) of yellow crystalline 3
was obtained: m.p. 109–111 °C dec.; IR (CH2Cl2) m(CO)
1
1962 (vs), 1897(s) cmꢀ1; H NMR (CD3COCD3) d 7.43–
7.31 (m, 15H, PPh3), 7.18–7.10 (m, 4H, o-CH3C6H4), 5.02
(dd, 1H, J = 8.7 Hz, H4), 4.55 (t, 1H, J = 7.8 Hz, H11),
3.64 (q, 2H, J = 7.8 Hz, OCH2CH3), 2.82 (m, 1H, H9),
2.54 (m, 1H, H9), 2.15 (s, 3H,CH3C6H4), 1.77 (m, 6H,
2.5. X-ray crystal structure determinations of complexes 3
and 4
H
10,7,8), 1.19 (t, 3H, J = 7.8 Hz, OCH2CH3), 0.24 (d, 1H,
J = 13.5 Hz, H6), ꢀ0.95 (m, 1H, H3); 13C NMR
(CD3COCD3) d 215.8 (CO), 154.4, 137.3, 136.8, 136.4,
133.0, 132.9, 132.8, 130.1, 129.8, 129.6, 129.5, 128.5,
128.4, 128.3, 125.4, 112.5, 102.1, 79.6, 68.8, 63.6, 60.4,
41.4, 32.6, 31.6, 31.3, 22.6, 18.9, 14.3; MS m/e 586
(M+ꢀ2CO), 324 (M+ꢀ2COꢀPPh3), 268 [M+ꢀPPh3ꢀ
Fe(CO)2], 262 ðPPh3þÞ. Anal. Calc. for C39H39O3P-
Fe ꢁ (C2H5)2O (ether): C, 72.09; H, 6.89. Found: C,72.61;
H, 6.63%. From the third fraction, a cyclobutane derivative
of 4 (0.012 g, 13%) as light yellow crystals was obtained:
m.p. 131 °C; 1H NMR (CDCl3) d 7.77–7.28 (m, 10H,
2C6H5), 3.91 (s, 3H, OCH3), 3.27 (m, 1H), 2.25 (m, 1H),
1.81 (m, 1H), 1.29 (s, 6H, 2CH3); MS m/z 422 (M+); HRMS
calcd for C24H22O7 [M+]: 422.1366. Found: 422.1368.
The single crystals of complexes 3 and 4 suitable for
X-ray diffraction studies were obtained by recrystallization
from petroleum ether/CH2Cl2 or petroleum ether/Et2O at
ꢀ80 °C. Single crystals were mounted on a glass fibre and
sealed with epoxy glue. The X-ray diffraction intensity data
for the two complexes were collected with a Bruker Smart
diffractometer at 20 °C using Mo Ka radiation with an
x–2h scan mode.
The structures of 3 and 4 were solved by the direct meth-
ods and expanded using Fourier techniques. For both
compounds, the non-hydrogen atoms were refined aniso-
tropically and the hydrogen atoms were included but not
refined. The absorption corrections were applied using
SADABS. The final cycle of full-matrix least-squares refine-
ment was based on the observed reflections and the vari-
able parameters converged with the unweighted and
weighted agreement to give the agreement factors listed
in Table 1.
2.3. Thermolysis of 1 in benzene-d6 (C6D6) to give 3, 4, and
5
As described above for the thermolysis of 1 in benzene,
0.130 g (0.20 mmol) of compound 1 dissolved in benzene-
d6 (6 mL) in a quartz tube was heated at 85–90 °C for
The details of the crystallographic data and the proce-
dures used for data collection and reduction information
for 3 and 4 are given in Table 1. The molecular structures

3174
N. Xiao et al. / Inorganica Chimica Acta 361 (2008) 3171–3176
Table 1
Crystal data and experimental details for complexes 3 and 4
3 ꢁ Et2O
43H49O4PFe
4
Formula
C
C24H22O7
422.42
Formula weight
Space group
716.64
C2/c (no. 15)
36.861(3)
13.7572(12)
14.8558(13)
106.069(2)
7239.1(11)
8
1.315
3040
5.03
P21/n (no. 14)
9.6406(12)
13.2005(16)
16.860(2)
101.451(2)
2102.9(4)
4
1.334
888
0.98
˚
a (A)
˚
b (A)
˚
c (A)
b (°)
3
˚
V (A )
Z
Dcalcd (g/cm3)
F(000)
l (Mo Ka) (cmꢀ1
)
Orientation reflections: number;
2871;
2313;
range (2h) (°)
4.477–44.101
2.30–56.56
8469
4.930–46.173
3.94–50.00
3710
Data collection range, 2h (°)
Number of unique data,
total with I > 2.00r(I)
4493
545
2215
296
˚
Fig. 1. ORTEP diagram of 3. Selected bond lengths (A) and angles (°):
No. of parameters refined
Correction factors,
maximum–minimum
Ra
Fe–C(3) = 2.123(3), Fe–C(4) = 2.054(3), Fe–C(5) = 2.091(3), Fe–C(6) =
2.158(3), C(3)–C(4) = 1.416(4), C(4)–C(5) = 1.401(4), C(5)–C(6) = 1.408(4),
0.76577–1.00000 0.7236–1.0000
C(5)–C(9) = 1.504(5),
C(6)–C(7) = 1.515(5),
C(3)–C(10) = 1.508(5),
C(4)–C(5)–C(6) =
120.0(3), C(3)–C(4)–C(5) = 117.7(3), C(4)–C(3)–C(10) = 122.3(3), C(3)–
C(10)–C(11) = 113.3(3), C(10)–C(11)–C(12) = 127.5(4), C(3)–C(4)–C(5)–
C(6) = ꢀ3.8(4), C(10)–C(3)–C(4)–C(5) = 174.8(3).
0.0519
0.1051
0.866
0.0721
0.1657
0.855
0.001
0.319
C(10)–C(11) = 1.498(5),
C(11)–C(12) = 1.313(4);
b
Rw
Quality of fit in dicatorc
Maximum shift/estimated final cycle 3.022
ꢀ
3
˚
ꢀ
Largest peak (e /A )
0.684
ꢀ0.363
3
˚
Minimum peak (e /A )
ꢀ0.351
products
of
spiro[4.4]nona-1,3-diene(dicarbonyl)[eth-
oxy(aryl)carbene]iron phosphine adducts 1 and 2.
P
P
a
b
c
R = kFo| ꢀ |Fck/ |Fo|.
P
P
Rw = [ w(|Fo| ꢀ |Fc|)2/ w|Fo|2]1/2; w = 1/r2(|Fo|).
An orange-red benzene solution of compound 1 in a
sealed tube was heated with stirring at 90–95 °C for 72 h.
After workup as in the Section 2, the g4 olefin-coordinated
carbonyliron phosphine complex [Fe{g4-C5H7CH@
CHCH2CH@C(OC2H5)C6H4CH3-o}(CO)2PPh3] (3), cyclo-
butane derivative 4, and Fe(CO)3(PPh3)2 (5) (Eq. (5)) were
obtained in 41%, 13%, and 27% yields, respectively. The
analogous thermolyses of compound 2 gave the corre-
sponding g4 olefin-coordinated carbonyliron complex
[Fe{g4-C5H7CH@CHCH2CH@C(OC2H5)C6H4CH3-p}-
(CO)2PPh3] (6) and products 4 and 5 (Eq. (5)). The
structures of 3 and 4 have been established by their sin-
gle-crystal X-ray diffraction studies. Product 5 is a known
compound [20], which was identified by its mp, and IR,
1H NMR, and mass spectra. Product 6 was assigned the
similar structure of 3 since its spectral data are similar to
those of 3 (Section 2).
P
Quality-of-fit = [ w(|Fo| ꢀ |Fc|)2/(Nobs ꢀ Nparameters)]1/2
.
of 3 and 4 are shown in Figs. 1 and 2, respectively, and the
principal bond lengths and angles for complexes 3 and 4
are also shown in Figs. 1 and 2. The atomic coordinates
and Biso/Beq, anisotropic displacement parameters, com-
plete bond lengths and angles, least-squares planes for 3
and 4 are given in the Supporting Information.
3. Results and discussion
As mentioned in the Introduction, in order to further
examine the thermolysis behavior of isomerized cycloole-
fin-coordinated alkoxycarbene iron complexes, we carried
out the study of the thermolysis reactions of the isomerized
CH
C
3
7
8
9
CH
+
3
O
8
7
OC2H5
O
O
5
6
C6H6 or C6D6
sealed tube
4
9
11
10
12
O
C
5
C
Ar
OCH
3
4
Ar
+
6
3
C
Fe(CO) (PPh )
3 2
12
3
90-95oC
70-72 h
11
10
Fe
O
Ph3P
3
ð5Þ
5
CO
OC2H5
CO
Fe
C
O
OC
PPh3
3, Ar= o-CH C H
6, r= p-CH C H
CO
3
3
6
6
4
4
4
A
1, Ar= o-CH C H
2, r= p-CH C H
3
3
6
6
4
4
A

N. Xiao et al. / Inorganica Chimica Acta 361 (2008) 3171–3176
3175
˚
Fig. 2. ORTEP diagram of 4. Selected bond lengths (A) and angles (°): C(2)–C(5) = 1.571(3), C(5)–C(6) = 1.539(4), C(6)–C(7) = 1.581(3), C(2)–
C(7) = 1.582(4), C(2)–C(1) = 1.532(3), C(2)–C(3) = 1.500(4), C(5)–C(12) = 1.522(4), C(6)–C(19) = 1.505(4), C(7)–C(8) = 1.502(4), C(1)–O(1) = 1.331(3),
C(3)–O(3) = 1.337(3), C(4)–O(1) = 1.446(3), C(4)–O(3) = 1.452(3); C(5)–C(2)–C(7) = 87.26(18), C(2)–C(5)–C(6) = 92.64(18), C(5)–C(6)–C(7) = 88.42
(19), C(6)–C(7)–C(2) = 90.62(18), C(7)–C(2)–C(5)–C(6) = 7.84(18), C(4)–O(1)–C(1)–C(2) = 9.8(3), O(1)–C(1)–C(2)–C(3) = 13.5(3).
The X-ray structure of 3 (Fig. 1) shows that a five-
membered ring of the spiro ring ligand was opened with
breaking of the C–C r-bond and formation of an g4 p-
bond coordinating to the Fe atom through the two conju-
gated double bonds, one of which is a cyclic and the other
is an acyclic. The distances from the Fe atom to the four
coordinated carbon atoms are different: the longest dis-
A possible mechanism for the formation of products 3
and 6 might be via an homolysis of the C–C r-bond in
spiro ring ligand corresponding to C(5)–C(11) with the for-
mations of the cyclic double bond C(5)–C(6) and acyclic
double bond C(4)–C(3) and with the coordination of the
Fe atom to satisfy the 18-electron configuration. While
the formation of compound 4, a minor product, is unex-
pected and surprising, and we do not know the chemistry
involved. However, it is certain that product 4 was derived
from starting 1 or 2 on thermal decomposition by losing
the Fe(CO)2PPh3 moiety, which can be converted into
Fe(CO)3(PPh3)2 (5) by abstracting a CO and a PPh3 ligands
generated from the decomposition of 1 or 2. Indeed, we
have isolated the by-product 5 by column chromatography
(Section 2 and Eq. (5)). The phenyl groups in product 4
might come from the solvent benzene or PPh3 ligand of
starting compound 1 or 2. However, the solvent benzene
can be excluded since the thermolysis of compound 1 in
deuterated benzene (C6D6) under the same conditions as
those in benzene also afforded product 4 in similar yield
(12%) but no deuterated product 4-d10 (Eq. (5)). Thus,
the most possible source of the phenyl groups in compound
4 is the PPh3. It is not excluded that the phenyl groups in
product 4 were derived from the tolyl group of starting 1
or 2, as mentioned below. As for the origin of the CH3
groups in molecule 4, we speculate that it might come from
the tolyl substituent or ethoxy group of 1 or 2. Further
cleavage could occur in the CH3C6H4 or OC2H5 group in
˚
tance is Fe–C(6) = 2.158(3) A, and the shortest distance
˚
is Fe–C(4) = 2.054(3) A; the distances of Fe–C(3) and
˚
Fe-(5) are 2.123(3) and 2.091(3) A, respectively. This dif-
ference could be caused by the steric hindrance of the
bulky PPh3 ligand. The bond lengths between the four-
coordinated carbon atoms are almost identical (C(3)–
˚
˚
C(4) = 1.416(4) A, C(4)–C(5) = 1.401(4) A, C(5)–C(6) =
˚
1.408(4) A), which are shorter than that of C–C single
bonds but longer than that of C@C double bonds. The
C(3), C(4), C(5), and C(6) atoms are nearly lie in a plane
with a torsion angle of C(3)–C(4)–C(5)–C(6) = 5.7(4)°.
The molecular structure of 4 (Fig. 2) shows that it is a
spiro organic compound consisting of a four-membered
ring and a six-membered ring. The C(2), C(5), C(6), and
C(7) atoms construct a planar square (C(7)–C(2)–C(5)–
C(6) = 7.84(18), C(2)–C(5)–C(6) = 92.64(18), C(5)–C(6)–
C(7) = 88.42(19), C(6)–C(7)–C(2) = 90.62(18)). The bond
lengths of C(2)–C(5), C(5)–C(6), C(6)–C(7), and C(2)–
˚
C(7) are 1.571(3), 1.539(4), 1.581(3), and 1.582(4) A,
respectively, which are approximately equal and obviously
longer than the normal C–C single bonds.

3176
N. Xiao et al. / Inorganica Chimica Acta 361 (2008) 3171–3176
(b) G. Maire, in: B.C. Gates, L. Guczi, H. Knoezinger (Eds.), Metal
Clusters in Catalysis, Elsevier Amsterdam Press, The Netherlands,
1986, p. 509;
(c) R.S. Dickson, B.C. Greaves, Organometallics 12 (1993)
3249.
1 or 2 aided by metal iron species under heating to lose the
CH3 group to become a C6H5 or OCH3 group by abstract-
ing a hydrogen from the solvent and provide its CH3 or
C6H5 group for the formation of 4. While the source of
the oxygen atom in product 4 is only CO ligands or ethoxy
group of starting 1 or 2 because the thermolysis reaction
was carried out in a vacuum sealed tube using water- and
oxygen-free benzene. Due to no relative reference and lack
of further experimental evidence, the mechanism proposed
above is a speculation only.
[3] C.P. Casey, N.W. Vollendorf, K.J. Haller, J. Am. Chem. Soc. 106
(1984) 3754.
[4] A. Parlier, H. Rudler, N. Platzer, M. Fontanniller, A. Soum, J.
Organomet. Chem. 287 (1985) C8.
[5] J.-L. Herrison, Y. Chauvin, Mokromol. Chem. 141 (1971) 161.
[6] (a) J.-B. Chen, G.-X. Lei, W.-H. Xu, J. Organomet. Chem. 286 (1985)
55;
(b) T.-L. Wang, J.-B. Chen, Q.-W. Wang, Acta Chim. Sin. (Chin. Ed.)
49 (1991) 265.
[7] J.-B. Chen, G.-X. Lei, Z.-H. Pan, S.-W. Zhang, Y.-Q. Tang, J. Chem.
Soc., Chem. Commun. (1987) 1273.
[8] J.-B. Chen, G.-X. Lei, M.-C. Shao, X.-J. Xu, Z.-Y. Zhang, J. Chem.
Soc., Chem. Commun. (1988) 1296.
[9] (a) J.-B. Chen, G.-X. Lei, Z.-S. Jin, L.-H. Hu, G.-C. Wei, J. Chem.
Soc., Chem. Commun. (1988) 731;
(b) J.-B. Chen, G.-X. Lei, Z.-S. Jin, L.-H. Hu, G.-C. Wei, Organo-
metallics 7 (1988) 1652.
[10] J.-B. Chen, J.-G. Yin, Z.-H. Pan, W.-H. Xu, J. Chem. Soc., Dalton
Trans. (1988) 2803.
[11] J.-B. Chen, G.-X. Lei, W.-H. Xu, Z.-H. Pan, S.-W. Zhang, Z.-Y.
Zhang, X.-L. Jin, M.-C. Shao, Y.-Q. Tang, Organometallics 6 (1987)
2461.
[12] (a) Y. Yu, J.-B. Chen, Organometallics 12 (1993) 4731;
(b) J.-B. Chen, Y. Yu, J. Sun, Organometallics 16 (1997) 3608;
(c) B.-H. Wang, R.-H. Li, J. Sun, J.-B. Chen, Chem. Commun. (1998)
631;
In summary, we have found that the remarkable
thermolysis reactions of the isomerized spiro[4.4]nona-
1,3-diene(dicarbonyl)[ethoxy(aryl)carbene]iron phosphine
adduct, and the novel thermolytic products were obtained.
The thermolysis results further indicate that the different
cycloolefin ligands exert a great influence on the thermoly-
sis behavior of the isomerized iron alkoxycarbene com-
plexes and the resulting products. Further studies on the
scope of these thermolysis reactions and application in
organic and organometallic synthesis are being carried
out in our laboratory.
Acknowledgements
We thank the National Natural Science Foundation of
China and the JSPS of Japan for financial support of this
research.
(d) N. Xiao, S. Zhang, Z.-L. Qiu, R.-H. Li, B.-H. Wang, Q. Xu, J.
Sun, J.-B. Chen, Organometallics 21 (2002) 3709.
[13] (a) J.-B. Chen, Y. Yu, L.-H. Hu, Z.-S. Jin, J. Organomet. Chem. 447
(1993) 113;
Appendix A. Supplementary material
(b) B.-H. Wang, R.-H. Li, J. Sun, J.-B. Chen, Organometallics 17
(1998) 3723.
[14] K.H. Doetz, Angew. Chem., Int. Ed. Engl. 23 (1984) 587.
[15] U. Schubert, Advances in Metal Carbene Chemistry, Kluwer
Academic Publishers, Norwell, 1988.
[16] D.F. Harvey, K.P. Lund, J. Am. Chem. Soc. 133 (1991) 8916.
[17] N. Xiao, B.-H. Wang, J.-G. Yin, Q. Xu, N. Tsumori, J. Sun, J.-B.
Chen, Organometallics 23 (2004) 257.
[18] L. Zhang, S. Zhang, Q. Xu, J. Sun, J.-B. Chen, Organometallics 24
(2005) 933.
CCDC 657153 and 657154 contain the supplementary
crystallographic data for 3 and 4. These data can be
obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/
j.ica.2007.11.029.
[19] J.-B. Chen, J.-G. Yin, W.-H. Xu, Acta Chem. Sin. (Chin. Ed.) 50
(1992) 409.
References
[20] (a) A. Davison, W. McFarlane, L. Pratt, G. Wilkinson, J. Chem. Soc.
(1962) 3653;
[1] G. Suess-Fink, G. Meister, Adv. Organomet. Chem. 35 (1993) 41.
[2] (a) W.L. Gladfelter, K.J. Roesselet, in: D.F. Shriver, H.D. Kaesz,
R.D. Adams (Eds.), The Chemistry of Metal Cluster Complexes,
VCH Weinheim Press, Germany, 1990, p. 392;
(b) R.L. Keiter, J.W. Benson, E.A. Keiter, T.A. Harris, M.W.
Hayner, L.L. Mosimann, E.E. Karch, C.A. Boecker, D.M. Olson, J.
VanderVeen, D.E. Brandt, Organometallics 16 (1997) 2246.