Ring closure of alkoxycarbonyl(tetracarbonyl)pyruvoyliron complexes into metallalactones induced by nucleophilic attack of carbanions

Article abstract of DOI:10.1002/ejic.200500997

The reaction of carbanions with the pyruvoyl-substituted iron complex [(CO)₄Fe(CO₂CH₃){C(O)C(O)CH₃}] (1) affords the anionic trifunctionalized metallalactones [(CO)₃Fe{C(O) C(CH₃)(CRR′R″)OC⁴(O)(Fe-C⁴)} (CO₂CH₃)]^- (3), whose formation results from the addition of the nucleophile to the β carbonyl of the pyruvoyl moiety, followed by attack of the oxygen of this β carbonyl on a terminal carbonyl ligand. These anionic lactones react, at low temperature, with HCl to give rise to the neutral lactones [(CO)₄Fe{C(O)C(CH₃) (CRR′R″)OC⁴(O)(Fe-C⁴)}] (2), which were previously obtained by addition of NuH nucleophiles to 1. Complex 3(3), whose lactonic ring formation has been performed using the diethyl malonate anion (R = R′ = CO₂C₂H₅; R″ = H), and the dimethyl-substituted neutral lactone 2(1) (R = R′ = R″ = H) have been characterized by X-ray diffraction studies. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Full text of DOI:10.1002/ejic.200500997

FULL PAPER
DOI: 10.1002/ejic.200500997
Ring Closure of Alkoxycarbonyl(tetracarbonyl)pyruvoyliron Complexes into
Metallalactones Induced by Nucleophilic Attack of Carbanions
Patrice Cabon,[a] René Rumin,[a] Jean-Yves Salaün,*[a] Hervé des Abbayes,[a] and
Smail Triki[a]
Keywords: Carbanions / Carbonyl ligands / Iron / Metallacycles / Nucleophilic addition
The reaction of carbanions with the pyruvoyl-substituted iron
complex [(CO)4Fe(CO2CH3){C(O)C(O)CH3}] (1) affords the
anionic trifunctionalized metallalactones [(CO)3Fe{C(O)-
C(CH3)(CRRЈRЈЈ)OC4(O)(Fe–C4)}(CO2CH3)]– (3), whose for-
mation results from the addition of the nucleophile to the β
carbonyl of the pyruvoyl moiety, followed by attack of the
oxygen of this β carbonyl on a terminal carbonyl ligand.
These anionic lactones react, at low temperature, with HCl
to give rise to the neutral lactones [(CO)4Fe{C(O)C(CH3)-
(CRRЈRЈЈ)OC4(O)(Fe–C4)}] (2), which were previously ob-
tained by addition of NuH nucleophiles to 1. Complex 3(3),
whose lactonic ring formation has been performed using the
diethyl malonate anion (R = RЈ = CO2C2H5; RЈЈ = H), and the
dimethyl-substituted neutral lactone 2(1) (R = RЈ = RЈЈ = H)
have been characterized by X-ray diffraction studies.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
gand of the molecule. We recently observed the original be-
havior of the complex cis-[(CO)4Fe{C(O)C(O)CH3}-
(CO2CH3)] (1), which afforded its cyclic isomer 2 quantita-
tively, at 15 °C, in a reaction involving the formation of a
metallalactone ring by addition of the oxygen of the β car-
bonyl of the pyruvoyl to the alkoxycarbonyl ligand and a
migration of the methoxy group of this latter ligand to the
β carbon of the pyruvoyl (Scheme 1, a).[10]
Introduction
Nucleophilic attacks upon organic ligands coordinated
to transition metals are important processes in the forma-
tion of new reactive organometallic intermediates that are
useful in organic synthesis. Although it is possible to assess
the reactivity of various ligands toward nucleophiles, it is
more difficult to predict the site of nucleophilic attack on
polyfunctional complexes. Thus, while nucleophiles react
very easily with terminal carbonyls of metal–carbonyl com-
pounds to afford acyl, aroyl, alkoxycarbonyl, or carbamoyl
ligands, the same reaction occurs regiospecifically at the α-
carbon of a carbene ligand,[1] at the α- and γ-carbons of an
allenylidene,[2,3] and at the β-carbon of an allenyl ligand[4]
of analogous complexes. It has also been shown that acyl
ligands are less electrophilic than terminal carbonyl li-
gands.[5] In the course of a study of complexes considered
as possible models for double or polycarbonylation reac-
tions, we investigated the reactivity of compounds dis-
playing a ligand with a C(O)C(O)R chain toward nucleo-
philic reagents. Indeed, addition of nucleophiles at Cα of
this type of ligand has been proposed to account for the
formation of phenylpyruvic esters by dicarbonylation of or-
ganic halides catalyzed by [Co(CO)4]–.[6] The very few nu-
cleophilic additions performed on cationic (Fe[7] Pt[8]) or
neutral complexes (Fe[9]) displaying an M–C(O)–C(O)–R
chain have been shown to occur at a terminal carbonyl li-
Scheme 1.
This reaction appeared very similar to the ring-chain
isomerism observed for organic γ-keto esters.[11] Indeed, as
the alkoxycarbonylpyruvoyliron complex 1 can be consid-
ered as a γ-keto ester with a metal inserted into the chain
linking its two organic functions, a parallel between the or-
ganic reaction and the organometallic process can be
drawn. When performed in the presence of an excess of pro-
nucleophilic reagents (Nu–H), the reaction affords Nu-sub-
[a] Laboratoire de Chimie, Electrochimie Moléculaires et Chimie
Analytique, UMR CNRS-Université de Bretagne Occidentale
6521, UFR Sciences et Techniques,
6 Avenue le Gorgeu, CS 93837, 29238 Brest Cédex, France
E-mail: jean-yves.salaun@univ-brest.fr
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P. Cabon, R. Rumin, J.-Y. Salaün, H. des Abbayes, S. Triki
FULL PAPER
stituted metallalactones (Scheme 1, b) which are formed, in the complex. These results suggest the fac trifunctional-
under these conditions, by an addition of the nucleophile ized metallalactone structure 3 for the products of these
to the β carbonyl of the pyruvoyl followed by metallalac- reactions (see Scheme 2).
tone ring formation due to attack of the oxygen of this β
carbonyl on the alkoxycarbonyl ligand and elimination of
the methoxy group of this latter ligand.[7] To the best of our
knowledge, prior to our study, only one example of nucleo-
philic addition at a carbonyl carbon of a ligand displaying
a double C(O) chain had been described in the literature.
In this paper, hydride was reported to attack the β carbonyl
of a ligand of [(CO)5Mn{C(O)C(O)C6H5)}] to afford an an-
ionic metallalactone by cyclization of the phenylglyoxyl
with a terminal carbonyl.[12] These results prompted us to
perform the cyclization of 1 with anionic nucleophiles (RO–,
RS–, or R2P–).[13] These reactions, as they only afford two
isomers of the anionic trifunctionalized metallalactone 3
(Scheme 1, c), also suggested that the formation of the
metallalactonic ring could indeed proceed by addition to a
terminal carbonyl rather than to the alkoxycarbonyl ligand.
However, as the structure of these trifunctionalized anions
3 was not firmly established, we tried to perform analogous
reactions using C–H nucleophiles and carbanions of vari-
ous nucleophilicity and of different steric effects. The results
of this study will be the topic of this paper.
Results and Discussion
Scheme 2.
Reaction of 1 with Activated C–H Bonds or Carbanions as
This assumption was confirmed by the 13C NMR spec-
Nucleophiles
troscopic data of these compounds. Although most of these
Although often used as nucleophiles,[14] pronucleophiles complexes were found to be sparingly soluble in organic
displaying activated methylenes, such as diethyl malonate solvents, the 13C NMR spectra of these compounds could
(1 equiv.) or malononitrile (20 equiv.), were found to be un- be obtained in [D8]THF (see Exp. Sect.). The anionic
reactive towards 1 at –10 °C. This lack of reactivity is not structure of complexes 3 was indicated by a shift of the
too surprising as 1 only reacts slowly with CH3OH, signals of the carbonyls linked to the metal toward lower
C2H5SH, HP(C6H5)2, or HP(C6H11)2.[7] On the other hand, fields relative to their homologues 1 (∆δ = 10 ppm for the
as shown by IR monitoring, 1 reacts very rapidly with carb- terminal carbonyls and 15 ppm for the carbon of the al-
anionic reagents such as MeLi, nBuLi, NaCH(CO2C2H5)2, koxycarbonyl).[13] However, the negative charge is very
NaCH(CϵN)2, NaCH[C(O)CH3]2, NaCH[C(O)CH3]- probably delocalized over the three carbonylated substitu-
(CO2CH3), NaCH(CO2C2H5)(CϵN), NaC(CH3)(CO2- ents of the complex as the chemical shifts of the terminal
C2H5)2, or NaC(CH2CH=CH2)(CO2C2H5)2 to afford in- carbonyls of 3 (from δ = 205 to 212 ppm) fall between those
stantaneously, even at –70 °C, new complexes displaying a observed for 1 (δ = 200 ppm)[13] and those of [(CO)4Fe-
set of three ν(CϵO) bands between 2084 and 1970 cm–1. (CO2R)]– (δ = 220 ppm).[15] The electron density of the me-
These frequencies are similar to those observed for the tal center of 3 is therefore intermediate between that ob-
product of the reaction between 1 and RO–, RS–, or R2P– served for neutral complexes and for the monofunction-
anions,[13] and are intermediate between the ν(CϵO) of the alized anion. The formation of a metallacycle in complexes
monofunctionalized anion [Fe(CO)4(CO2R)]– (three bands 3 is shown by the signal of their disubstituted cyclic quater-
around 1910 cm–1)[15] and those of their homologues of the nary carbon atom between δ = 86.5 and 96.9 ppm. This
neutral complex cis-[Fe(CO)4(CO2R)2] (four bands between value is not very different from those observed for similar
2130 and 2050 cm–1).[16] They fall within the range of those carbons substituted by OR (δ = 111 ppm), SR (δ =
of trifunctionalized mono anions such as fac-[(CO)3Fe- 95.5 ppm), or PR2 (δ = 90 ppm) groups.[13] As 3(1) displays
(CO2R)3]– (two bands at 2080 and 2015 cm–1), which are two methyl substituents on this cyclic quaternary carbon, it
themselves obtained by addition of RO– to a terminal car- only exists as one isomer. The formation of this single iso-
bonyl of [(CO)4Fe(CO2R)2].[9] These values measured for mer is shown in the 13C NMR spectrum by the observation
ν(CϵO) are therefore consistent with a moderate increase of one signal for each carbon of this complex. The non-
of the electron density on the metal. The observation of equivalency of these two methyls, shown by two signals at
three ν(CϵO) bands instead of the two required by C3v δ = 15.8 and 8.4 ppm, results from the fac position of the
symmetry could result from the presence of a metallacycle alkoxycarbonyl ligand. Reaction of 1 with nBuLi afforded
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a similar complex. This compound, which has both n-butyl and four signals for the central carbon of the nucleophile
and methyl substituents on the quaternary carbon of its at δ = 44.5, 43.5, 42.5, and 42.0 ppm.
metallalactone [R = RЈ = H; RЈЈ = C3H7; 3(2)], was formed
As shown by IR monitoring, the reaction of 1 with the
as a 50:50 mixture of two isomers. The presence of these bulky nucleophiles NaC(CH3)(CO2C2H5)2 or NaC(CH2-
two isomers is shown by the observation of two signals of CH=CH2)(CO2C2H5)2 also affords trifunctionalized an-
equal intensities at δ = 274.1 and 271.5 ppm for the C=O ionic metallalactones. However, the 13C NMR spectra of
acyl, at δ = 96.9 and 96.7 ppm for the cyclic sp3 carbon, the thus formed compounds 3(8) (R = RЈ = CO2C2H5, RЈЈ
and at δ = 60.5 and 59.9 ppm for the OCH3 group of the = CH3) and 3(9) (R = RЈ = CO2C2H5, RЈЈ = CH2CH=CH2)
alkoxycarbonyl ligand. Surprisingly, the same reaction per- are found to display broad signals whose chemical shifts are
formed with NaCH(CO2C2H5)2 afforded only one isomer in good agreement with those expected for anionic metallal-
of the anion 3(3) (R = RЈ = CO2C2H5; RЈЈ = H). Indeed, actones (see Exp. Sect.). The detection of at least three sig-
the 13C NMR spectrum of this compound only displays one nals for the resonances of the acyl CO or for their cyclic
signal at δ = 269.3 ppm for the acyl C=O, at δ = 94.3 ppm quaternary carbon suggests the presence of at least three
for the cyclic sp3 carbon, at δ = 50.9 ppm for the methoxy isomers for these two complexes. The broadness of the ob-
of the methoxycarbonyl ligand, and at δ = 21.7 ppm for the served signals probably results from slow interconversion
methyl located on the cyclic sp3 carbon. On the other hand, between the observed species. However, no change was ob-
due to the asymmetry of the metallalactone ring, the two served in the spectra of these compounds when they were
ethoxycarbonyls of the malonyl group are not equivalent recorded at different temperatures (from 20 °C to –50 °C).
and appear as two signals at δ = 168.7 and 167.3 ppm, 62.65 The only isomer of 3(3) was obtained as single crystals suit-
and 62.55 ppm, and 13.6 and 13.7 ppm for the carbonyl, able for an X-ray diffraction study.
the CH2, and the CH3 carbon atoms, respectively, while the
central carbon of this malonyl group only displays a single
resonance at δ = 55.25 ppm. The solubility of 3(3) is signifi-
cantly better than 3(1) and 3(2).
Structural Study of Complex 3(3)
When 1 was treated with the anions obtained from 2,4-
Single crystals of 3(3), with K+ as counterion, were
pentanedione or malononitrile, 3(4) [R = RЈ = C(O)CH3, grown from a hexanes/dichloromethane mixture (90:10) at
RЈЈ = H] and 3(5) (R = RЈ = CN, RЈЈ = H) were formed, –30 °C. An ORTEP diagram of the anion is displayed in
respectively. As shown by their 13C NMR spectra (see Exp. Figure 1, crystallographic data are given in the Exp. Sect.,
Sect.), they are obtained as mixtures of two isomers (70:30 and selected bond lengths and angles are gathered in
and 60:40, respectively). As observed for 3(3), the CH3C(O) Table 1 and Table 2, respectively.
and CN groups of each isomer of these complexes are not
The crystal structure confirms the proposed anionic,
equivalent. Thus, 3(4) displays four CH3 resonances at δ = metallacyclic, trifunctionalized geometry for 3(3). The
32.9, 32.7, 32.3, and 32.1 ppm (the signals for the C=O structure can be described as being composed of four crys-
groups of the terminal carbonyls are not detectable) and tallographically different (Figure 1, a) trifunctionalized
3(5) four CN resonances at δ = 113.7, 113.45, 112.6, and entities linked to four potassium ions (Figure 1, b). As these
112.5 ppm while two peaks are observed for the central car- anions exhibit slight differences in their bond lengths and
bon of the malononitrile group of 3(5) at δ = 31.1 and angles, the values measured for each of these entities (a, b,
30.8 ppm [the resonance of the homologue carbon atom of c, and d) will be mentioned in the following discussion. The
3(4) is probably hidden by the signal of the THF]. Asym- crystal structure study establishes that the only formed
metric nucleophiles such as NaCH[C(O)CH3](CO2CH3) or complex is the isomer with the alkoxycarbonyl ligand and
NaCH(CO2C2H5)(CN) also afforded anions of type 3. The the malonyl group trans to each other on the metallacycle
formed complexes 3(6) (R = CO2CH3, RЈ = C(O)CH3, (Figure 1, a). This complex, which is sterically less hindered
RЈЈ = H) or 3(7) (R = CO2CH3, RЈ = CN, RЈЈ = H) were than the corresponding cis isomer, is probably the species
again obtained as two cis/trans isomers (50:50) but, due to observed in solution. The coordination polyhedron at the
the asymmetry of their metallacycle and of the central car- metal center is a distorted octahedron built of three ter-
bon of their nucleophile group, each of these isomers is ob- minal carbonyl ligands, an alkoxycarbonyl, and the chelat-
served as two diastereoisomers. For this reason, the 13C ing carbonylated ligand. As observed for neutral metallalac-
NMR spectra of 3(6) and 3(7) exhibit four signals for each tones[7,10,12,13] and for five-membered iron metallacycles,[17]
of their carbon atoms. For example, 3(6) displays four acyl the bite angle of the chelate C(7)–Fe–C(6) [82.3(5)–83.4(5)°]
CO signals at δ = 268.5, 267.4, 267.0, and 266.8 ppm, four is smaller than the angle measured between the two organic
peaks for the cyclic quaternary carbon at δ = 94.2, 93.1, carbonylated ligands of the noncyclic cis-bis(alkoxycar-
92.6, and 92.1 ppm, and four signals for the resonance of bonyl)iron complex [(CO)4Fe(CO2tBu)2] [88.5(2)°].[18]
the central carbon atom of the nucleophilic group at δ = Therefore, its opposite angle on the metal [C(1)–Fe–C(2)]
62.5, 62.2, 61.9, and 61.2 ppm. In the same way, the 13C displays a larger value than that expected for an octahedral
NMR spectrum of 3(7) shows four CO signals at δ = 267.5, geometry [96.0(6)–100.2(5)°]. The axial alkoxycarbonyl li-
266.8, 266.5, and 266.2 ppm, four CN signals at δ = 118.0, gand is bent toward the metallacycle [C(4)–Fe–C(6) from
117.5, 117.3, and 116.8 ppm, four resonances for the cyclic 81.3(5)° to 84.6 (5)° and C(4)–Fe–C(7) from 84.8(5)° to
quaternary carbon at δ = 93.0, 92.5, 91.5, and 91.0 ppm, 89.0(5)°]. The other angles around the metal are normal,
Eur. J. Inorg. Chem. 2006, 1515–1524
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Table 1. Bond lengths [Å] and angles [°] measured for the four (a,
b, c, and d) anionic forms of 3(3).
a
b
c
d
Fe–C1
Fe–C2
Fe–C3
Fe–C4
Fe–C6
Fe–C7
O4–C4
O6–C6
O7–C7
O8–C6
O8–C8
O9–C11
O11–C14
C7–C8
C1–Fe–C2 99.3(5)
C1–Fe–C3 97.1(6)
C1–Fe–C4 85.1(6)
C1–Fe–C6 88.4(5)
C1–Fe–C7 89.2(5)
C3–Fe–C6 93.0(5)
C3–Fe–C7 88.3(5)
C4–Fe–C6 83.3(5)
C4–Fe–C7 89.0(5)
C6–Fe–C7 82.3(5)
C6–O8–C8 117.8(9)
Fe–C6–O6 130.1(8)
Fe–C6–O8 117.6(8)
O6–C6–O8 112.3(9)
Fe–C7–O7 131.1(8)
Fe–C7–C8 113.9(8)
O7–C7–C8 115.0(9)
O8–C8–C7 107.6(8)
1.83(1)
1.78(1)
1.79(1)
1.99(1)
1.93(1)
1.94(1)
1.24(1)
1.23(1)
1.21(1)
1.38(1)
1.40(1)
1.17(1)
1.20(2)
1.60(1)
1.86(1)
1.81(1)
1.79(1)
2.00(1)
1.94(1)
1.96(1)
1.22(2)
1.22(2)
1.22(2)
1.38(1)
1.42(2)
1.20(2)
1.19(2)
1.56(2)
98.5(6)
94.8(6)
87.6(5)
88.9(6)
89.4(6)
91.1(5)
89.7(5)
83.4(5)
87.2(5)
82.6(5)
117.7(9)
129.8(8)
116.6(9)
113(1)
1.79(1)
1.90(1)
1.82(1)
2.05(1)
1.97(1)
1.97(1)
1.14(2)
1.21(2)
1.20(2)
1.36(1)
1.43(2)
1.18(2)
1.22(2)
1.58(1)
100.2(5)
94.7(6)
87.1(5)
87.8(5)
88.7(5)
93.5(5)
88.6(6)
81.3(5)
88.9(5)
82.9(5)
117.2(8)
129.4(9)
116.8(9)
113.8(9)
129.8(8)
112.1(9)
118(1)
1.87(1)
1.85(1)
1.84(1)
2.01(1)
1.94(1)
1.98(1)
1.22(1)
1.22(1)
1.21(1)
1.41(2)
1.44(1)
1.23(1)
1.21(2)
1.55(2)
96.0(6)
95.4(6)
85.8(6)
88.7(5)
91.2(6)
89.9(5)
93.3(6)
84.6(5)
84.8(5)
83.4(5)
116.0(8)
130(1)
116.7(9)
112(1)
130.5(9)
112.5(8)
117(1)
128.5(8)
114.0(9)
117(1)
108.6(9)
110(1)
110(1)
CϵO distance observed in a monofunctionalized iron
anion.[19] These data confirm a reduced electron density on
the metal due to the delocalization of the negative charge
of the complex on the carbonylated organic ligands. The
short Fe–cyclic(C=O)O distances [Fe–C(6) from 1.93(1) to
1.97(1) Å] associated with long C(6)–O(6) bonds [from
1.21(1) to 1.23(1) Å] show the enolate character of this
group whose C=O oxygen is bound to three potassium ions
(see below). Such a lengthening of the C=O double bond is
Figure 1. Structure of 3(3). Part a: ORTEP view of the anionic
complex a (50% probability ellipsoids); anions b, c, and d are sim-
ilar. Part b: Perspective view showing the potassium ions’ environ-
ment.
with values close to 90°. The Fe–terminal carbonyl dis- not observed for C(4)=O(4), C(11)=O(9), or C(14)=O(11),
tances [1.79(1)–1.90(1) Å] are similar to those in the homol- whose oxygens are only bound to one potassium, or for
ogous trifunctionalized iron monoanion[9] or to the neutral C(7)=O(7), which does not interact with this metal. The
complex [(CO)4Fe(CO2tBu)2][18] but are longer than the Fe– other bond lengths or angles of the complex are analogous
Table 2. Interionic K–O distances [Å] and angles [°] in the cubane-like structure of 3(3) (see Figure 1, part b).
K1–O4d
K1–O6b
K1–O6d
K1–O6a
K1–O8b
K1–O9b
K1–O11b
O6b–K1–O6d
O6b–K1–O6a
O6d–K1–O6a
K1–O6b–K2
K2–O6b–K4
K2–O6c–K4
2.688(8)
2.886(7)
2.859(9)
2.721(8)
2.758(8)
2.741(9)
2.81(1)
75.3(2)
75.1(2)
79.0(2)
104.1(3)
92.0(3)
92.4(3)
K2–O4b
K2–O6b
K2–O6c
K2–O6a
K2–O8a
K2–O9a
K2–O11a
O6b–K2–O6c
O6b–K2–O6a
O6c–K2–O6a
K1–O6d–K3
K3–O6d–K4
K1–O6a–K3
2.650(9)
2.787(8)
2.709(9)
2.873(7)
2.760(8)
2.697(8)
2.744(8)
83.5(2)
74.3(2)
77.2(2)
96.8(2)
108.3(3)
96.1(2)
K3–O4a
K3–O6c
K3–O6d
K3–O6a
K3–O8c
K3–O9c
K3–O11
O6c–K3–O6d
O6c–K3–O6a
O6d–K3–O6a
K1–O6b–K4
K2–O6c–K3
K3–O6c–K4
2.611(8)
2.839(7)
2.709(9)
2.876(9)
2.708(7)
2.79(1)
2.804(9)
73.3(2)
75.2(2)
K4–O4c
K4–O6b
K4–O6c
K4–O6d
K4–O8d
K4–O9d
K4–O11d
O6b–K4–O6c
O6b–K4–O6d
O6c–K4–O6d
K1–O6d–K4
K1–O6a–K2
K2–O6a–K3
2.675(9)
2.742(9)
2.799(8)
2.868(7)
2.827(7)
2.726(9)
2.824(9)
82.6(3)
77.4(2)
71.5(2)
101.6(3)
106.2(3)
100.5(2)
78.9(2)
104.1(3)
105.6(2)
106.6(2)
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FULL PAPER
to those measured for neutral metallalactones.[7,10,13] As one equivalent of anhydrous HCl at –80 °C instantaneously
shown by the deviations of O(8) (+0.13 and +0.18 Å) and affords new compounds displaying four ν(CϵO) bands be-
C(8) (+0.11 and +0.20 Å) from the plane defined by C(6)– tween 2131 and 2041 cm–1. The presence of these four IR
Fe–C(7), the metallalactone ring of 3(3) is not rigorously bands and their frequencies suggested the formation of neu-
planar. It is worth noting that C(8) and O(8) are located on tral cis disubstituted complexes. Under the same reaction
the same side of this plane. The steric effect of the malonyl conditions an analogous process was observed for 3(5) and
group induces a pseudo axial position of the methyl substit- 3(7), although the formed complexes rapidly evolved into
uent of the metallacycle, as shown by deviations of C(9) Fe(CO)5 and organic compounds. Complexes 2(1), 2(2),
from the C(6)–Fe–C(7) plane of between 1.42 and 1.53 Å; 2(3), 2(4), 2(6), 2(8), and 2(9), formed by reaction of 3(1),
deviations of between 0.91 and 1.09 Å are observed for 3(2), 3(3), 3(4), 3(6), 3(8), and 3(9) with HCl, respectively,
C(10), which is the central atom of the malonyl group. As were obtained as pale-yellow crystals from a hexanes/
mentioned above, 3(3) is composed of four slightly different CH2Cl2 (95:5) mixture at –30 °C. Their 13C NMR spectra
entities in the solid state that display their four potassium confirm their neutral character as they display terminal
ions and four cyclic ester carbonyl oxygens [O(6)] alter- CϵO resonances between δ = 202.75 and 196.2 ppm (vs. δ
nately at the corners of a distorted cube (see Figure 1, b). = 212.5–201.0 ppm for the starting complexes). Their other
This cube displays small O–K–O angles (71.5–83.5°) and resonances are very close to those exhibited by neutral
larger K–O–K angles (92.0–108.3°). Each potassium is metallalactones: a C=O cyclic acyl between δ = 249.9 and
linked to seven oxygen atoms; for example, K(4) interacts 254.1 ppm (vs. δ = 274.1 and 262.3 ppm for the anionic lac-
with O(6d) and O(8d), which are the two oxygen atoms of tones) and a cyclic C=O ester indiscernible from the ter-
the cyclic ester group of d, with the oxygen atoms [O(9d) minal CϵO. The presence of a metallacycle in these com-
and O(11d)] of the two carbonyl oxygens of the malonyl plexes is shown by the observation of signals corresponding
group of d, with the oxygen atoms of the carbonyl of the to cyclic quaternary carbons between δ = 92.3 and
cyclic esters of molecules b and c [O(6b) and O(6c)], and 98.4 ppm. All these characteristics are in good agreement
with the carbonyl oxygen of the alkoxycarbonyl ligand of with the formation of neutral metallalactones of type 2
complex c [O(4c)]. Short K–O(4) distances (2.61–2.68 Å) (Scheme 2). Complex 2(1), whose quaternary cyclic carbon
are observed between the potassium and the oxygen of this is substituted by two methyl groups, displays a single signal
latter ligand. Recall that O(6) − the carbonyl oxygen of the for its two axial terminal carbonyl ligands at δ = 200.2 ppm.
cyclic ester group of each anion − interacts with three po- This equivalence may result either from the quasi planarity
tassium ions, which induces a lengthening of the C(6)–O(6) of the metallacycle or from rapid interconversion between
bond (1.23 vs. 1.19 Å observed for neutral lactones[7,10,13]
)
different conformations of the metallacycle. Other com-
and a shortening of the Fe–C(6) distance (1.93 vs. 1.99 Å). plexes 2 whose cyclic quaternary carbons are substituted
The complexation of O(6) with a potassium ion [K(4)] that by two different groups exhibit two signals for their axial
is itself bound to O(8), O(9), and O(11) of the same mole- carbonyl ligands. For example, five peaks are observed for
cule brings about a reduction of the O(6)–C(6)–O(8) sp2 the four terminal CϵO groups and the C=O of the cyclic
angle from 112(1)° to 113.8 (9)°. The absence of complex- ester of 2(2) between δ = 200.5 and 196.5 ppm. Due to the
ation of the cyclic acyl oxygen O(7) must also be noted.
asymmetry of the lactone ring, the two ethoxycarbonyl
This crystallographic work confirms without any doubt groups of the malonyl substituent of 2(3) are not equivalent
the structure attributed to this series of anionic trifunction- (two peaks are observed for the C=O at δ = 168.74 and
alized metallalactones 3. However, a clear relation between 168.70 ppm, for the CH2 at δ = 62.2 and 62.15 ppm, and
the nature of the nucleophile and the trans/cis ratio ob- for the CH3 at δ = 13.9 and 13.75 ppm, whereas a single
served for the different complexes 3 (from 100% to 50% of signal at δ = 58.6 ppm corresponds to the CH). A similar
the trans isomer) has not been established. For example, spectrum should be obtained for 2(4). However, as its acetyl
the steric hindrance of KCH(CO2C2H5)2 cannot justify the C=O signals are hidden by those of the terminal CϵO, the
specific formation of the trans isomer of 3(3) except if the presence of two different acetyl groups is only shown by the
possible formation of aggregates of the anionic nucleophile two peaks of their methyl groups at δ = 31.05 and 30.2 ppm.
is considered. Such a hypothesis has already been taken into Complex 3(6), which displays an acetomethyl acetate and a
account to explain the stereospecific nucleophilic additions methyl group on its cyclic quaternary carbon, affords, upon
on organic ketones. The formation of anionic compounds reaction with HCl, the neutral complex 2(6). Owing to the
3 when the transformation of 1 is induced by anionic nu- presence of the asymmetric central carbon of the acetoace-
cleophiles raises the question of the specific formation of tate group and to the asymmetry of the metallacycle itself,
neutral lactones 2 by reaction of 1 with pronucleophiles 2(6) is obtained as an equimolecular mixture of two dia-
Nu–H. An answer to this question is given by the reaction stereoisomers. The presence of these two isomers is shown
of complexes 3 with anhydrous HCl.
in the 13C NMR spectrum by two C=O acyl resonances at
δ = 251.32 and 251.22 ppm, by numerous signals between δ
= 202.06 and 196.29 ppm [terminal carbonyls, cyclic ester
group and organic C(O) acetyl], and by the splitting in two
Reaction of Anionic Lactones 3 with HCl
As shown by IR monitoring of the process, the reaction of the other signals: the organic C=O ester at δ = 169.9
of complexes 3(1), 3(2), 3(3), 3(4), 3(6), 3(8), and 3(9) with and 169.4, the cyclic quaternary carbon at δ = 92.78 and
Eur. J. Inorg. Chem. 2006, 1515–1524
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FULL PAPER
92.32 ppm, the CH at δ = 65.86 and 65.35 ppm, the OCH3 Table 3. Bond lengths [Å] and angles [°]for compound 2(1).
at δ = 53.30 and 53.08 ppm, the acetyl CH3 at δ = 30.11
Fe–C4
Fe–C1
Fe–C2
Fe–C3
Fe–C6
Fe–C5
O6–C6
O7–C5
1.796(7)
1.811(7)
1.849(8)
1.856(6)
1.975(6)
1.991(5)
1.205(6)
1.371(6)
1.451(6)
167.7(2)
93.6(2)
92.8(2)
95.1(2)
94.6(2)
96.8(2)
88.1(2)
84.2(2)
172.6(3)
90.3(2)
83.8(2)
85.7(2)
90.4(3)
172.8(3)
82.6(3)
117.8(5)
O1–C1
O3–C3
O5–C5
O2–C2
O4–C4
C9–C7
C7–C8
C7–C6
1.143(6)
1.130(6)
1.199(6)
1.146(7)
1.137(5)
1.524(9)
1.508(8)
1.539(7)
and 29.42 ppm, and the other CH3 at δ = 22.19 and
22.15 ppm. Recall that anions 3(8) and 3(9), whose metall-
acycle is substituted by the crowded diethyl methyl- or allyl-
malonate groups, exhibit broad signals in their 13C NMR
spectra. Their reaction with HCl also affords complexes of
type 2, whose formation confirms the structure attributed
to these anions. Contrary to their precursors, 2(8) and 2(9)
give very well resolved 13C NMR spectra. The characteris-
tics of these spectra are very close to those of 2(3), which
bears an unsubstituted malonyl, as they display two non-
equivalent ethoxycarbonyls on their substituted malonyl
group. This is shown by a splitting in two of the signals of
the carbons of these ethoxycarbonyl groups, whereas the
resonances of the third substituent and of the central qua-
ternary carbon of the malonyl are found as singlets (see
Exp. Sect.). Among this series of neutral complexes 2, crys-
tals suitable for a structural study were obtained for 2(1).
O7–C7
C4–Fe–C1
C4–Fe–C2
C1–Fe–C2
C4–Fe–C3
C1–Fe–C3
C2–Fe–C3
C4–Fe–C6
C1–Fe–C6
C2–Fe–C6
C3–Fe–C6
C4–Fe–C5
C1–Fe–C5
C2–Fe–C5
C3–Fe–C5
C6–Fe–C5
C5–O7–C7
O1–C1–Fe
O3–C3–Fe
O5–C5–O7
O5–C5–Fe
O7–C5–Fe
O7–C7–C8
O7–C7–C9
C8–C7–C9
O7–C7–C6
C8–C7–C6
C9–C7–C6
O2–C2–Fe
O4–C4–Fe
O6–C6–C7
O6–C6–Fe
C7–C6–Fe
177.3(5)
176.1(5)
117.4(5)
127.1(5)
115.4(5)
107.2(5)
105.7(5)
112.8(6)
109.5(4)
112.0(5)
109.3(5)
177.6(6)
176.4(5)
117.8(5)
128.2(4)
114.0(4)
Crystallographic Study of Complex 2(1)
Single crystals of 2(1) suitable for an X-ray diffraction
study were obtained from a hexanes/dichloromethane mix-
ture (95:5) at –30 °C. Figure 2 displays an ORTEP drawing
of the molecule; selected bond lengths and angles are listed
in Table 3, and further crystallographic data can be found
in the Exp. Sect.
function, whose oxygens are linked to the counterion in 3(3).
The metallacycle is quasi planar, as shown by the torsion
angles C(5)–Fe–C(6)–C(7) [–4.6(4)°] and C(6)–Fe–C(5)–
O(7) [+6.2(4)°]. However, contrary to 3(3), O(7) and C(7)
are no longer located on the same side of the C(6)–Fe–C(5)
plane. The rapid evolution of complexes 3 into neutral
metallalactones 2 when treated with HCl sheds new light
on the direct formation of 2 by reaction of 1 with Nu–H
nucleophiles. These observations suggest that the formation
of 2 could result from a cyclization of the pyruvoyl and a
terminal carbonyl ligand (and not, as considered earlier, the
alkoxycarbonyl ligand) that affords an anionic, trifunction-
alized metallalactone 3. This intermediate, which would
have H+ as counterion, would then instantaneously evolve
into 2. The formation of complexes 2 by cyclization of the
pyruvoyl and the alkoxycarbonyl ligand is therefore not
necessarily involved in the process of anionic lactone forma-
tion. The reaction of 2 with NaOMe will confirm that this
compound is not an intermediate of the reaction of forma-
tion of 3 by cyclization of 1 by anionic reagents.
Figure 2. ORTEP view of 2(1) (50% probability ellipsoids).
As observed for 3(3), the coordination around the iron
atom in this complex can be described as a distorted octa-
hedron with a reduced metallacyclic angle [C(6)–Fe–C(5) =
82.6(3)°, vs. an average of 82.8° for 3c] and a larger value
for its opposite angle C(3)–Fe–C(2) of 96.8(2)° due to the
presence of the metallacycle. As already described by us for
other neutral metallalactones,[7,10,13] the two axial terminal
Reactions of Neutral Lactones 2 with NaOMe
The formation of anionic trifunctionalized metallalac-
carbonyls of 2(1) are bent toward the metallacycle [C(1)– tones 3 by nucleophilic addition of CH3O– to a terminal
Fe–C(4) = 167.7(2)°; C(4)–Fe–C(6) = 88.1(2)°; C(4)–Fe– carbonyl of complexes 2 was performed with 2(1) (R = RЈ
C(5) = 83.8(2)°; C(1)–Fe–C(6) = 84.2(2)°; C(1)–Fe–C(5) = = CH3; RЈЈ = H), 2(3) (R = RЈ = CO2C2H5; RЈЈ = H), and
85.7(2)]°. The Fe–cyclic ester bond [Fe–C(5)] of 1.991(5) Å 2(8) (R = RЈ = CO2C2H5; RЈЈ = CH3). As shown by the
and the C=O bond of this organic function [C(5)–O(5) = IR, H, and 13C NMR spectra of the formed complexes,
1
1.199 (6) Å] are respectively longer and shorter than their 2(1) affords 3(1) while 2(3) gives rise to 3(3), again as a
homologues in 3(3) (average of 1.95 Å for the first and single isomer. The product formed by reaction of 2(8) with
1.22 Å for the second). These bond lengths, which are sim- NaOMe also displays the IR spectrum of a trifunctional-
ilar to those measured for neutral metallalactones,[7,10,13] ized anionic lactone. Its 13C NMR spectrum is similar to
are indicative of an absence of enolate character of this that of 3(8) obtained by cyclization of 1 performed with
1520
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Eur. J. Inorg. Chem. 2006, 1515–1524

Ring Closure of Iron Complexes Induced by Nucleophilic Attack of Carbanions
FULL PAPER
Service Central dЈAnalyses du CNRS. Fe(CO)5, NaOMe, CH3Li
(1.6  in diethyl ether), nBuLi (1.6  in hexanes), CH2(CO2C2H5)2,
CH2[C(O)CH3]2, CH2(CN)2, CH(CH3)(CO2C2H5)2, CH2(CO2C2H5)-
[C(O)CH3], and CH2(CO2C2H5)(CN) were purchased from
commercial sources and used as received. CH(CH2CH=CH2)-
(CO2C2H5)2 was prepared as described in the literature[21] by reac-
tion of ClCH2CH=CH2 with NaCH(CO2C2H5)2[21–23] and purified
CH(CH3)(CO2C2H5)2 and exhibits broad signals that again
reveal the formation of at least three isomers of this com-
pound. Upon reaction with HCl at low temperature this
latter compound, which is very probably 3(8), was again
found to evolve into 2(8). The yield of complexes 3(1), 3(3)
and 3(8), upon addition of NaOMe to a terminal carbonyl
of neutral lactones, remains low (from 30 to 35%), and
careful IR monitoring of the process showed that their for-
mation is always concomitant with the detection of another
product displaying the IR spectrum of a monofunction-
alized anion (three bands around 1900 cm–1). Unfortu-
nately, the low stability of this complex did not allow its
characterization.
by distillation (b.p. 105 °C, 15 Torr). Complex 1 was obtained as
[24]
described elsewhere[13] by reaction of ClC(O)C(O)CH3
[(CO)4Fe(CO2CH3)]–.[15]
with
General Procedure for the Preparation of Stabilized Carbanions:
These anions were prepared as described in the literature.[21,23] The
substrate (1.5 mmol) in solution in THF (5 mL) was added drop-
wise, over a period of 10 min, to a suspension of NaH (36 mg,
1.5 mmol obtained from a 40% dispersion in mineral oil washed
with 5×5 mL of hexanes before use) in THF (10 mL) at room tem-
perature. H2 gas evolution was observed. The solution obtained
was stirred for 10 min and used without further purification.
Conclusion
This work has allowed us to show that in complex 1,
which displays an alkoxycarbonyl, a pyruvoyl, and terminal
carbonyl ligands, the β carbonyl of the pyruvoyl is the most
electrophilic site of the molecule. Addition of various nu-
cleophiles to this site affords anionic trifunctionalized
metallalactones 3 whose metallalactone ring is formed by
addition of the oxygen of this β carbonyl to a terminal car-
bonyl. When treated with HCl, the rapid evolution of these
complexes 3 into neutral metallalactones 2 explains the di-
rect formation of 2 when the cyclization of 1 is performed
with pronucleophiles (Nu–H). Recall that, starting from
complex 1, the formation of 3 could also be performed by
the intermediate formation of 2 obtained by cyclization of
the pyruvoyl ligand of 1 with the alkoxycarbonyl moiety of
the same complex and release of CH3O–. The rapid ad-
dition of this CH3O– to a terminal carbonyl of 2 was then
supposed to afford 3. This work allowed us to dismiss this
hypothesis as the reaction of complex 2 with CH3O– was
only found to afford 3 in very low yield. However, two as-
pects of this work remain unclear: i) the formation of a
single isomer of 3(3) from the cyclization of 1 with the
anion of diethyl malonate, and ii) the broadness of the
NMR signals of 3(8) and 3(9) associated with the high
number of isomers observed for the complexes bearing a
diethyl methylmalonate or a diethyl allylmalonate as sub-
stituent. Further experiments are under progress to find an
answer these questions.
Reaction of [(CO)4Fe{C(O)C(O)CH3}(CO2CH3)] (1) with Carban-
ions. General Procedure for the Preparation of the Trifunctionalized
Anionic Complexes 3: The carbanion (1.5 mmol; 0.94 mL of a 1.6 
solution of CH3Li in diethyl ether, 0.6 mL of a 2.5  solution of
nBuLi in hexanes, or the solution of the stabilized carbanion pre-
pared as described above) was added, with stirring, to a solution
of 1 (450 mg, 1.5 mmol) in THF (30 mL) at –70 °C. As shown by
IR monitoring, the reaction was very fast as three new bands were
rapidly observed in the ν(CO) region. The temperature was then
raised to –10 °C and the solvent evaporated to dryness. The residue
was washed with hexanes at –20 °C (3×5 mL) to afford a white
powder, which was generally found to be insoluble in most organic
solvents, with the exception of the complexes obtained with
(CO2C2H5)2C(R)– (R = H, CH3 or allyl) and (CO2C2H5)[C(O)-
CH3]C(H)–, which could be extracted with a hexanes/CH2Cl2 mix-
ture (75:25) at 0 °C (3×30 mL) and recrystallized from this mixture
at –40 °C. We were unable to obtain correct analysis of these rather
unstable anionic complexes 3.
Reaction of 1 with CH3Li: According to the general procedure for
this reaction, 1 (450 mg, 1.5 mmol) was treated with CH3Li (950 µL
of a 1.6  solution in diethyl ether) to give 3(1) (385 mg, 80%
yield). IR (THF): ν(CϵO) = 2070 (w), 1995 (s), 1970 cm–1 (s);
ν(C=O) = 1680 (br), 1635 (br), 1605 (br). 1H NMR (400 MHz,
[D8]THF, 273 K): δ = 3.3 (br. s, 3 H, OCH3), 1.1 (br. s, 6 H, CH3)
ppm. 13C{1H} NMR (400 MHz, THF, 273 K): δ = 262.3 (C=O),
225.4 [cyclic C(O)O-], 209.7, 208.3, 207.2 and 206.3 [CO and C(O)-
O-], 94.3 (cyclic quaternary carbon), 50.3 (OCH3), 15.8 (CH3),
8.4 ppm (CH3).
Reaction of 1 with nBuLi: The reaction of 1 (1.5 mmol, 450 mg)
with nBuLi (600 µL of a 2.5  solution in hexanes) was found to
afford white crystals of 3(2) (270 mg, 50% yield). IR (THF):
ν(CϵO) = 2068 (m), 2002 (s), 1982 cm–1 (s); ν(C=O) = 1660 (sh),
1636 (m), 1610 (m). 1H NMR (400 MHz, [D8]THF, 273 K): δ = 3.4
(br. s, 1.5 H, OCH3), 3.2 (br. s, 1.5 H, OCH3), 1.7–0.8 (br. m, 12
H, nBu and CH3) ppm. 13C{1H} NMR [400 MHz, THF, 273 K;
two isomers (50:50)]: δ = 274.1, 271.5 (C=O), 229.5, 228.8 [cyclic
C(O)O-], 212.5–208.0 [numerous signals for CO and C(O)O], 96.9,
96.7 (cyclic quaternary carbon), 60.5, 59.9 (OCH3), 50.3, 50.1, 38.2,
37.7, 23.1, 22.2 (CH2), 22.5, 22.1, 14.7, 14.5 ppm (CH3).
Experimental Section
General Remarks: All reactions were carried out with Schlenk tech-
niques under dry, oxygen-free argon. All solvents were purified by
preliminary distillation from an appropriate drying agent.[20]
CD2Cl2 and [D8]THF were stored over molecular sieves under inert
atmosphere until needed. Infrared spectra were recorded in the
range 2300–1600 cm–1 in solution in hexanes, CH2Cl2, or THF with
a FT-IR NEXUS NICOLET spectrometer. 1H and 13C NMR spec-
tra were recorded at 0 °C in CD2Cl2 or [D8]THF with a Bruker
AMX-3 300 or Bruker DRX 400 spectrometer. NMR HMQC,
HMBC, and COSY spectra were recorded with a Bruker DRX 500.
Reaction of 1 with NaC(H)(CO2C2H5)2: Complex 1 (450 mg,
1.5 mmol) was treated at –70 °C with a solution of NaC(H)-
(CO2C2H5)2 (1.5 mmol, prepared as described above) in THF
(10 mL). The product of the reaction, obtained as a white powder,
Chemical shifts are reported in
δ units (ppm) downfield
from tetramethylsilane. Elemental analyses were performed by the was extracted at –10 °C with a hexanes/CH2Cl2 (60:40) mixture
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P. Cabon, R. Rumin, J.-Y. Salaün, H. des Abbayes, S. Triki
FULL PAPER
(3×30 mL) and recrystallized at –40 °C from this solution to give
white crystals of 3(3) (650 mg, 90% yield). IR (CH2Cl2): ν(CϵO)
Reaction of 1 with NaC(H)(CO2C2H5)(CϵN): Complex 1 (450 mg,
1.5 mmol) was treated with
a
solution of NaC(H)-
= 2082 (s), 2022 (s), 2000 cm–1 (s); ν(C=O) = 1747 (s), 1624 (s). 1H (CO2C2H5)(CϵN) (1.5 mmol) in THF (10 mL) at –70 °C. After
NMR (400 MHz, CD2Cl2, 273 K): δ = 4.26 (dq, J = 7, JЈ = 3 Hz,
evaporation of the solvent, the yellow oily residue was washed with
1 H, OCH2), 4.09 (dq, J = 7, JЈ = 3 Hz, 1 H, OCH2), 3.88 (dq, J
hexanes (3×15 mL) at 0 °C to afford 3(7) as a brown powder
= 7, JЈ = 3 Hz, 1 H, OCH2), 3.74 (dq, J = 7, JЈ = 3 Hz, 1 H, (350 mg; 59% yield). IR (THF): ν(CϵN) = 2246 cm–1 (w); ν(CϵO)
OCH2), 3.74 (s, 1 H, CH), 3.24 (s, 3 H, OCH3), 1.21 (t, J = 7 Hz, = 2073 (s), 2012 (s), 1987 (s), ν(C=O) = 1749 (m), 1652 (s). 1H
3 H, CH3CH2), 1.09 (t, J = 7 Hz, 3 H, CH3CH2), 1.06 (s, 3 H,
CH3C) ppm. 13C{1H} NMR (400 MHz, CD2Cl2, 273 K): δ = 269.3
(C=O), 229.5 [cyclic C(O)O-], 207.1, 206.9, 206.4 and 204.4 [CO
and C(O)O], 168.7 (C=O ester),; 167.3 (C=O ester), 92.0 (cyclic
NMR (400 MHz, [D8]THF, 273 K): δ = 4.45 (s, 1 H, CH), 4.10 (m,
2 H, OCH2), 3.30 (s, 3 H, OCH3), 1.10 (m, 3 H, CH2CH3), 1.05 (s,
3 H, CCH3) ppm.13C{1H} NMR (400 MHz, [D8]THF, 273 K; four
isomers): δ = 267.5, 266.8, 266.5, 266.2 (C=O), 222.5–202.0 [numer-
quaternary carbon), 62.65 (OCH2), 62.55 (OCH2), 55.25 (CH), 50.9 ous peaks for CO, C(O)OCH3, and cyclic C(O)O], 167.0, 166.2,
(OCH3), 21.7 (CCH3), 13.7 (CH2CH3), 13.6 (CH2CH3) ppm. The
different signals were allocated to each carbon by HMBC and
HMQC sequences.
165.5, 164.0 [organic C(O)OC2H5], 118.0, 117.5, 117.3, 116.8
(CϵN), 93.0, 92.5, 91.5, 91.0 (cyclic quaternary carbon), 60–52
(numerous peaks for OCH3 and OCH2), 14–10 (numerous reso-
nances for CCH3 and CH2CH3) ppm.
Reaction of 1 with NaC(H)[C(O)CH3]2: As described in the general
procedure, 1 (450 mg 1.5 mmol) was added at –70 °C to a suspen-
sion of NaC(H)[C(O)CH3]2 (1.5 mmol) in THF (10 mL) to give
3(4) as a white powder (475 mg, 75% yield) that was found to be
insoluble in most organic solvents. IR (THF): ν(CϵO) = 2071 (s),
2011 (s), 1985 cm–1 (s); ν(C=O) = 1726 (w), 1697 (w), 1651 (s),
Reaction of 1 with Substituted Malonate Anions NaC(R)(CO2C2H5)2
(R = CH3 or allyl): Compound 1 (450 mg 1.5 mmol) was treated
at –70 °C with NaC(R)(CO2C2H5)2 [1.5 mmol in solution in THF
(10 mL) prepared as described above: 300 mg for R = CH3 or
330 mg for R = allyl]. The product of the reaction, obtained as a
white powder, was extracted at 0 °C with a hexanes/CH2Cl2 (60:30)
mixture (3×30 mL) but, despite several attempts, we were unable
to get crystals from these solutions. The solvent was removed to
give 550 mg (R = CH3; 75% yield) or 505 mg (R = allyl; 65% yield)
of a white powder which was probably composed of several isomers
of 3(8) (R = CH3) or 3(9) (R = allyl).
1
1598 (w). H NMR (400 MHz, [D8]THF, 273 K): δ = 3.54 (s, 1 H,
CH), 3.39 (s, 3 H, OCH3), 2.20 (s, 3 H, CCH3), 2.06 [s, 6 H, C(O)
CH3] ppm. 13C{1H} NMR [400 MHz, [D8]THF, 273 K; 2 isomers
(70:30)]: δ = 268.8 (C=O), 267.5 (C=O), 220.9 [cyclic C(O)O],
207.7, 207.1, 206.3, 205.1, 204.6, 203.5, 203.15, 202.6, and 201.6
[CO, C(O)O, and C(O)CH3], 94.0 (cyclic quaternary carbon), 69.2
[C{C(O)CH3}2], 51.85, 50.45 (OCH3), 34.05, 33.88, 33.05,32.05
[C(O)CH3], 21.95, 20.3 (CH3) ppm.
3(8): IR (CH2Cl2): ν(CϵO) = 2084 (s), 2023 (s), 2000 cm–1 (s);
ν(C=O) = 1721 (s), 1606 (s); (THF): ν(CϵO) = 2069 (s), 2006 (s),
1995 cm–1 (s); ν(C=O) = 1735 (s), 1637 (s). 1H NMR (400 MHz,
CD2Cl2, 273 K): δ = 4.20 (br. m, 4 H, OCH2), 3.41 (br. s, 3 H,
OCH3), 1.46 (br. s, 3 H, CH3), 1.40 (br. s, 3 H, CH3), 1.23 (br. m,
6 H, CH3) ppm. 13C{1H} NMR (400 MHz, CD2Cl2, 273 K): δ =
262.3, 266.2, 265.8 (C=O), 237.8, 236.3 [cyclic C(O)O], 210.9,
210.6, 209.4, 208.9, 206.3, 205.6, 205.2 [CO and C(O)O], 173.7,
168.2 (C=O ester), 96.3, 96.2, 95.4, 95.0 (cyclic quaternary carbon),
62.9, 62.3, 62.2, 62.1, 59.6, 59.2 (OCH2), 52.0, 51.8, 51.5 [OCH3,
C(CH3)], 22.4, 21.6, 20.2, 19.3, 18.4, 13.9, 13.8 (CH3) ppm.
Reaction of 1 with NaC(H)(CϵN)2: As described in the general
procedure, 1 (450 mg, 1.5 mmol) was added at –70 °C to a solution
of NaC(H)(CϵN)2 (1.5 mmol) in THF (10 mL). The yellow pow-
der of 3(5) which was obtained (375 mg, 65% yield) was insoluble
in most organic solvents. IR (THF): ν(CϵN) = 2253 cm–1 (w);
ν(CϵO) = 2075 (s), 2015 (s), 1987 (s); ν(C=O) = 1658 (s), 1622
(sh), 1601 (sh). 1H NMR [400 MHz, [D8]THF, 273 K; 2 isomers
(60:40)]: δ = 4.98 (s, 0.6 H, CH), 4.61 (s, 0.4 H, CH), 3.34 (s, 1.8
H, OCH3), 3.30 (s, 1.2 H, OCH3), 1.39 (s, 1.8 H, CH3), 1.15 (s, 1.2
H, CH3) ppm. 13C{1H} NMR (400 MHz, [D8]THF, 273 K): δ =
267.6 (C=O), 264.5 (C=O), 220.4, 219.25 [cyclic C(O)O], 208.7,
207.8, 207.35, 207.2, 206.9, 206.65 (CO), 206.2, 205.25 [s, C(O)
OCH3], 113.7, 113.45, 112.6, 112.5 (CϵN), 90.5, 88.5 (cyclic qua-
ternary carbon), 51.5, 50.65 (OCH3), 31.1, 30.8 [C(CϵN)2], 22.15,
21.0 (CCH3) ppm.
3(9): IR (CH2Cl2): ν(CϵO) = 2070 (s), 2010 (s), 1983 cm–1 (s);
ν(C=O) = 1749 (s), 1610 (s). 1H NMR (400 MHz, CD2Cl2, 273 K):
δ = 5.74 (br. m, 1 H, CH allyl), 5.30 (br. m, 2 H, CH2 allyl), 4.16,
4.05 (br. m, 4 H, OCH2), 3.36 (br. s, 3 H, OCH3), 2.61, 2.19 (br.
m, 2 H, CH2 allyl), 1.36 (br. s, 3 H, CH3), 1.15 (br. s, 6 H, CH3)
ppm. 13C{1H} NMR (400 MHz, CD2Cl2, 273 K): δ = 272 (br.,
C=O), 237.5 [br., cyclic C(O)O], 210.0, 206.7, 206.3 [br., CO and
C(O)O], 171.3, 167.6 (C=O ester), 134.4, 133.8, 132.4 (allylic CH),
119.3, 118.2, 117.3 (allylic CH2), 95.6, 93.9, 92.2 (cyclic quaternary
carbon), 64.5 (malonyl quaternary carbon), 62.1, 61.7 (OCH2),
51.6, 51.3 (OCH3), 36.5, 35.3, 34.5 (allylic CH2), 25.5, 22.8 (CCH3),
13.6 (CH3) ppm.
Reaction of 1 with NaC(H)(CO2CH3)[C(O)CH3]: Following the ge-
neral procedure, 1 (450 mg, 1.5 mmol) was allowed to react with a
solution of NaC(H)(CO2CH3)[C(O)CH3] (1.5 mmol) in THF
(10 mL) at –70 °C to give 3(6) as a yellow powder (490 mg, 75%
yield) after extraction with a 60:40 hexanes/CH2Cl2 mixture
(3×15 mL) at 0 °C and crystallization from this mixture at –40 °C.
IR (CH2Cl2): ν(CϵO) = 2071 (s), 2011 (s), 1984 cm–1 (s); ν(C=O) =
1744 (s), 1655 (sh), 1621 (s). 1H NMR (400 MHz, CD2Cl2, 273 K; 4
isomers): δ = 4.2 (s, 1 H, CH), 3.65 (s, 3 H, OCH3), 3.4 (s, 1.5 H,
OCH3), 3.25 (s, 1.5 H, OCH3), 2.3 [s, 1.5 H, C(O)CH3], 2.1 (s, 1.5
H, C(O)CH3], 1.2 (s, 1.5 H, CCH3), 1.1 (s, 1.5 H, CCH3) ppm.
13C{1H} NMR (400 MHz, [D8]THF, 273 K): δ = 268.5, 267.4,
Reaction of the Anionic Trifunctionalized Metallalactones 3 with
HCl. General Procedure for Preparation of Neutral Alkyl-Substi-
tuted Lactones 2: A 1  solution of HCl in diethyl ether (1 mL) was
added to a slurry of anionic lactones 3 (1 mmol) in THF (40 mL)
267.1, 267.0 (C=O), 221.9, 221.3, 220.6, 220.4 [cyclic C(O)O], at –70 °C. As shown by IR monitoring of the reaction, the reaction
211.7, 209.6, 208.5, 208.4, 208.3, 208.1, 207.7, 207.2, 207.1, 203.5,
203.3, 202.7, 201.0 [CO, C(O)OCH3, and C(O)CH3], 169.6, 169.2
(2), 168.7 [organic C(O)OCH3], 93.9, 93.1, 92.6, 92.3 (cyclic quater-
nary carbon), 62.5, 62.2, 61.9, 61.2 (CH), 52.7, 52.5, 52.2, 50.8 (2),
50.5, 50.3, 49.9 (OCH3), 32.9, 32.7, 32.3, 32.1 [CH3 C(O), 24.1,
23.7, 23.2, 22.9 (CCH3) ppm.
was very fast. After 15 min at this temperature the ν(CO) bands of
neutral complexes 2 at 2120, 2070, 2060, and 2040 cm–1 were found
to have totally replaced those of the starting complexes 3 at 2080,
2020, and 2000 cm–1. The temperature was then raised to –10 °C
and the solvent removed to dryness. The residue was extracted at
–10 °C with a hexanes/CH2Cl2 (95:5) mixture (5×25 mL). This
1522
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© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 1515–1524

Ring Closure of Iron Complexes Induced by Nucleophilic Attack of Carbanions
FULL PAPER
solution was reduced to 10 mL at –40 °C to afford pure crystals of
complexes 2.
of HCl was found, even at low temperature (–80 °C), to lead to
their decomposition into Fe(CO)5 and organic compounds.
Reaction of 3(1) with HCl: Preparation of 2(1): Following the gene-
ral procedure, 3(1) (385 mg, 1.20 mmol) was treated with HCl
(1.2 mL of a 1  solution in diethyl ether) to afford 2(1) (219 mg
65% yield). IR (hexanes): ν(CϵO) = 2125 (m), 2073 (sh), 2064 (m),
2042 cm–1 (s); ν(C=O) = 1780 (m), 1685 (sh). 1H NMR (400 MHz,
CD2Cl2, 273 K): δ = 1.3 (s, 6 H, CH3) ppm. 13C{1H} NMR
(400 MHz, CD2Cl2, 273 K): δ = 254.1 (C=O), 200.2 (2 C, axial
CϵO), 198.4, 196.6, 196.3 [CO and cyclic C(O)O], 96.2 (cyclic qua-
ternary carbon), 24.1 (CH3) ppm. C9H6FeO7 (281.95): calcd. C
38.33, H 2.14, Fe 19.80; found C 38.21, H 2.12, Fe 19.73.
Reaction of the Mixture of Isomers of 3(8) or 3(9) Bearing Bulky
Substituents with HCl. Preparation of 2(8) and 2(9): The reaction
of 3(8) or 3(9) [1 mmol, 500 mg for 3(8) (R = CH3) or 520 mg for
3(9) (R = allyl)] with HCl (1 mL of a 1  solution in diethyl ether)
at –50 °C afforded 2(8) (310 mg, 70% yield) or 2(9) (233 mg, 50%
yield), respectively, as white powders after crystallization from hex-
anes at –40 °C.
2(8): IR (hexanes): ν(CϵO) = 2131 (s), 2084 (m), 2052 (m),
1
2050 cm–1 (s); ν(C=O) = 1727 (m), 1695 (s). H NMR (400 MHz,
CD2Cl2, 273 K): δ = 4.11 (q, J = 7 Hz, 4 H, OCH2), 1.58 (s, 3 H,
CH3), 1.44 (s, 3 H, CH3), 1.20 (t, J = 7 Hz, 6 H, CH2CH3) ppm.
13C{1H} NMR (400 MHz, CD2Cl2, 273 K): δ = 249.9 (C=O),
202.6, 199.55 (3 C), 196.35 [CO and cyclic C(O)O], 169.9, 169.4
(CO2C2H5), 95.25 (cyclic quaternary carbon), 62.1, 61.8 [quater-
nary malonic carbon and OCH2 (2 C)]; 20.1 (CH3), 18.95 (CH3),
13.8 [CH2CH3 (2 C)] ppm. C16H16FeO11 (440.143): calcd. C 43.66,
H 3.66, Fe 12.67; found C 43.85, H 3.63, Fe 12.62.
Reaction of 3(2) with HCl. Preparation of 2(2): The reaction of 3(2)
(270 mg, 0.75 mmol) with HCl (750 µL of a 1  solution in diethyl
ether) gave rise to 2(2) (134 mg, 55% yield). IR (hexanes): ν(CϵO)
= 2124 (s), 2072 (sh), 2063 (s), 2041 cm–1 (s); ν(C=O) = 1738 (w),
1
1704 (s). H NMR (400 MHz, CD2Cl2, 273 K): δ = 1.5–1.2 (br. m,
9 H, nBu), 0.85 (br. s, 3 H, CH3) ppm. 13C{1H} NMR (400 MHz,
CD2Cl2, 273 K): δ = 254.1 (C=O), 200.5, 200.3, 198.4, 196.6, 196.5
[CO and cyclic C(O)O], 98.4 (cyclic quaternary carbon), 36.9, 26.9,
25.6, 23.0, 21.9 (CH2 and CH3) ppm. C12H12FeO7 (324.03): calcd.
C 44.48, H 3.73, Fe 17.23; found C 44.62, H 3.92, Fe 17.15.
2(9): IR (hexanes): ν(CϵO) = 2128 (s), 2083 (m), 2059 (m),
1
2041 cm–1 (s); ν(C=O) = 1750 (m). 1737 (m), H NMR (400 MHz,
CD2Cl2, 273 K): δ = 5.8 (m, 1 H, =CH), 5.1 (m, 2 H, =CH2), 4.15
(m, 4 H, OCH2), 2.8 (d, J = 5 Hz, 2 H, allylic CH2), 1.49 (s, 3
H, CH3), 1.22 (t, J = 7 Hz, 6 H, CH2CH3) ppm. 13C{1H} NMR
(400 MHz, CD2Cl2, 273 K): δ = 249.84 (C=O), 202.75, 198.48,
198.34, 197.98, 196.41 [CO and cyclic C(O)O-], 168.74, 168.70
(CO2C2H5), 133.94 (=CH), 118.16 (=CH2), 95.60 (cyclic quater-
nary carbon), 65.71 (quaternary malonic carbon), 62.19, 62.07
(OCH2), 37.59 (allylic CH2), 19.90 (CH3), 13.94, 13.80 (CH2CH3)
ppm. C18H18FeO11 (466.181): calcd. C 46.38, H 3.89, Fe 11.98;
found C 46.52, H 3.93, Fe 11.97.
Reaction of 3(3) with HCl. Preparation of 2(3): Complex 3(3)
(480 mg, 1 mmol) and HCl (1 mL of a 1  solution in diethyl ether)
were reacted to afford 2(3) (255 mg, 60% yield). IR (hexanes):
ν(CϵO) = 2131 (s), 2083 (m), 2064 (s), 2047 cm–1 (s); ν(C=O) =
1
1734 (m), 1689 (s). H NMR (400 MHz, CD2Cl2, 273 K): δ = 4.13
(m, 4 H, OCH2), 3.70 [s, 1 H, C(H)(CO2C2H5)2], 1.34 (s, 3 H,
CCH3), 1.22 (m, 6 H, CH2CH3) ppm. 13C{1H} NMR (400 MHz,
CD2Cl2, 273 K): δ = 251.8 (C=O), 202.0, 199.4, 199.05 (2 C), 196.3
[CO and cyclic C(O)O], 166.3, 166.1 (CO2C2H5), 92.6 (cyclic qua-
ternary carbon), 62.2, 62.15 (OCH2), 58.6 (CH), 22.2 (CCH3), 13.9,
13.75 ppm (CH2CH3). C15H14FeO11 (426.12): calcd. C 42.28, H
3.31, Fe 13.11; found C 42.46, H 3.35, Fe 13.05.
Reaction of 2(1) (R = RЈ = RЈЈ = H), 2(3) (R = RЈ = CO2C2H5;
RЈЈ = H), and 2(8) (R = RЈ = CO2C2H5; RЈЈ = CH3) with NaOMe.
Formation of 3(1), 3(3), and 3(8): Complex 2 [0.5 mmol; 140 mg of
2(1), 210 mg of 2(3), or 220 mg of 2(8)] in solution in THF (30 mL)
at 0 °C was added to a suspension of 28 mg of NaOMe in THF.
The reaction was monitored by IR spectroscopy. After 90 min the
solvent was removed to dryness. The residue of the reaction per-
formed with 2(1) was washed with CH2Cl2 (3×5 mL) at 0 °C. The
residues obtained from 2(3) and 2(8) were washed with hexanes
(3×5 mL) and extracted with a hexanes/CH2Cl2 (60:40, 3×10 mL)
mixture and crystallized from this solution at –40 °C. The 13C
NMR spectra of the obtained products were found to be similar
to those of 3(1), 3(3), and 3(8), respectively. These reactions were
found to afford 60 mg of 3(1) (35% yield), 70 mg of 3(3) (30%
yield), or 75 mg of 3(8) (30% yield).
Reaction of 3(4) with HCl. Preparation of 2(4): Complex 3(4)
(1 mmol 420 mg) was reacted at –50 °C with HCl (1 mL of a 1 
solution in diethyl ether) to afford 2(4) (200 mg, 55% yield). IR
(hexanes): ν(CϵO) = 2131 (s), 2085 (m), 2064 (s), 2047 cm–1 (s);
ν(C=O) = 1720 (sh), 1705 (s), 1690 (sh). 1H NMR (400 MHz,
CD2Cl2, 273 K): δ = 2.15 (s, 3 H, CCH3), 2.02 [s, 6 H, C(O)CH3]
ppm. 13C{1H} NMR (400 MHz, CD2Cl2, 273 K): δ = 251.65
(C=O), 202.1, 201.8, 201.3, 199.3 (2 C), 197.85, 196.2 [CO, cyclic
C(O)O and C(O)CH3], 92.65 (cyclic quaternary carbon), 74.0 (CH),
31.05, 30.2 [CH3C(O)], 22.2 (CCH3) ppm. C13H10FeO9 (366.064):
calcd. C 42.65, H 2.75, Fe 15.26; found C 42.78, H 2.85, Fe 15.22.
Reaction of 3(6) with HCl. Preparation of 2(6): The reaction of 3(6)
(500 mg, 1.15 mmol) with HCl (1.15 mL of a 1  solution in diethyl
ether) at –50 °C was found to afford 2(6) (285 mg 65% yield). IR
(hexanes): ν(CϵO) = 2131 (m), 2085 (m), 2064 (s), 2047 cm–1 (s);
ν(C=O) = 1755 (w), 1721 (sh), 1703 (m). 1H NMR (400 MHz,
CD2Cl2, 273 K; two isomers: δ = 3.98 (s, 0.6 H, CH), 3.92 (s, 0.4
H, CH), 3.78 (s, 1.8 H, OCH3), 3.66 (s, 1.2 H, OCH3), 2.25 [s, 1.2
H, C(O)CH3], 2.12 [s, 1.8 H, C(O)CH3], 1.28 (s, 1.8 H, CCH3), 1.25
(s, 1.2 H, CCH3) ppm. 13C{1H} NMR (400 MHz, CD2Cl2, 273 K):
δ = 251.32, 251.22 (C=O), 202.06, 201.94, 200.72, 200.01, 198.41,
198.31, 198.15, 198.08, 198.02, 196.29 [CO, cyclic C(O)O and C(O)
CH3], 167.70, 167.18 (CO2CH3), 92.78, 92.32 (cyclic quaternary
carbon), 65.86, 65.35 (CH), 53.30, 53.08 (OCH3), 30.11, 29.42
[C(O)CH3], 22.19, 22.15 (CCH3) ppm. C13H10FeO10 (382.063):
calcd. C 40.87, H 2.64, Fe 14.62; found C 41.05, H 2.63, Fe 14.52.
X-ray Crystallographic Studies: Data for compounds 2(1) and 3(3)
were collected on a Xcalibur 1 diffractometer (Oxford Diffraction)
at 150 and 100 K, respectively. The very low stability of compound
3(3) made a correct X-ray data collection difficult. In this case we
had only a few seconds to select a correct single crystal which was
very quickly mounted on the goniometer head of the diffractometer
at 100 K. After several attempts we succeeded in finding a correct
single crystal of 3(3) suitable for the data collection. Both structures
were solved by direct methods and successive Fourier difference
syntheses, and were refined by weighted anisotropic full-matrix le-
ast-squares methods.[25] The hydrogen atoms of compound 2(1)
were located by difference Fourier techniques and were refined iso-
tropically; while those of compound 3(3) were calculated [d(C–H)
= 0.95 Å]; their thermal parameters were taken as Uiso = 1.3·
Uequ(C) and therefore included as isotropic fixed contributors to
Fc. Scattering factors and corrections for anomalous dispersion
Reaction of Complexes 3(5) or 3(7) with HCl: The reactions of these
complexes, which contain one or two CϵN groups, with 1 equiv.
Eur. J. Inorg. Chem. 2006, 1515–1524
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1523

P. Cabon, R. Rumin, J.-Y. Salaün, H. des Abbayes, S. Triki
FULL PAPER
[6] a) H. des Abbayes, A. Buloup, J. Chem. Soc., Chem. Commun.
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Francalanci, M. Foa, J. Organomet. Chem. 1982, 232, 59–70;
d) L. Cassar, Ann. N. Y. Acad. Sci. 1980, 333, 208–224.
[7] P. Cabon, M. Sellin, J. Y. Salaün, V. Patinec, H. des Abbayes,
M. M. Kubicki, Organometallics 2002, 21, 2196–2202.
[8] T. M. Huang, Y. J. You, C. S. Yang, W. H. Tzeng, J. T. Chen,
M. C. Cheng, Y. Wang, Organometallics 1991, 10, 1020–1026.
[9] M. Sellin, D. Luart, J. Y. Salaün, P. Laurent, L. Toupet, H.
des Abbayes, Organometallics 1996, 15, 521–526.
[10] M. Sellin, D. Luart, J. Y. Salaün, P. Laurent, L. Toupet, H.
des Abbayes, Chem. Commun. 1996, 857–858.
[11] R. E. Valters, W. Flitsch, Ring–Chain Tautomerism, Plenum,
New York 1985.
[12] J. C. Selover, G. D. Vaughn, C. E. Strouse, J. A. Gladysz, J. Am.
Chem. Soc. 1986, 108, 1455–1462.
[13] P. Cabon, R. Rumin, J. Y. Salaün, S. Triki, H. des Abbayes,
Organometallics 2005, 24, 1709–1717.
[14] See, for example: a) M. Picquet, C. Bruneau, P. H. Dixneuf,
Tetrahedron 1999, 55, 3937–3948; b) N. Tsukada, A. Shibuya,
I. Nakamura, H. Kitahara, Y. Yamamoto, Tetrahedron 1999,
55, 8833–8844; c) I. Kadota, A. Shbuya, H. C. Gyoung, Y. Ya-
mamoto, J. Am. Chem. Soc. 1998, 120, 10262–10263; d) Y. Ya-
mamoto, U. Radhakrishnan, Chem. Soc. Rev. 1999, 28, 199–
207.
[15] J. L. McLean, Ph.D. Thesis, New York University, 1974.
[16] J. Y. Salaün, G. le Gall, P. Laurent, H. des Abbayes, J. Or-
ganomet. Chem. 1992, 441, 99–108.
[17] a) R. C. Pettersen, J. L. Cihonski, F. R. Young, R. A. Leven-
son, J. Chem. Soc., Chem. Commun. 1975, 370–371; b) K.
Hoffmann, E. Weiss, J. Organomet. Chem. 1977, 128, 389–398;
c) S. Aime, L. Milone, E. Sappa, A. Tiripicchio, A. M. Man-
otti Lanfredi, J. Chem. Soc., Dalton Trans. 1979, 1664–1670; d)
K. J. Karel, T. H. Tulip, S. D. Ittel, Organometallics 1990, 9,
1276–1282.
[18] D. Luart, N. le Gall, J. Y. Salaün, L. Toupet, H. des Abbayes,
Inorg. Chim. Acta 1999, 291, 166–177.
[19] R. H. Dotz, U. Wenicker, G. Muller, H. G. Alt, D. Seyferth,
Organometallics 1986, 5, 2570–2572.
[20] D. D. Perrin, W. L. F. Armarego, D. R. Perrin, Purification of
Laboratory Chemicals, Pergamon Press, New York, 1980.
[21] L. S. Hegedus, Y. Inoue, J. Am. Chem. Soc. 1982, 104, 4917–
4921.
Table 4. Crystal data and structural refinement details for 2(1) and
3(3).
2(1)
3(3)
Empirical formula
Molecular weight
Space group
a [Å]
b [Å]
c [Å]
C9H6FeO7
281.99
P421c
17.824(2)
17.824(2)
7.1894(5)
90
90
90
2284.0(4)
8
1.64
C67H74Cl6Fe4K4O48
2239.82
P1
¯
¯
14.892(1)
17.082(1)
20.093(2)
75.553(7)
84.644(7)
77.615(6)
4830.3(9)
2
α [°]
β [°]
γ [°]
V [Å3]
Z
ρcalcd. [gcm–3]
Temperature
µ [cm–1]
1.54
100
10.16
150(2)
13.30
F(000)
Reflections measured
2θ range
Reflections unique/Rint
Reflections with I Ͼ 2σ(I) 881
1136
7474
7.22–43.70
952/0.049
2284
16359
5.0–44.10
7262/0.042
5125
Nv
178
0.0262/0.0556
1.064
837
0.065/0.082
1.619
[b]
R1,[a] wR2
GooF[c]
Flack parameter
–0.01(3)
∆ρmax.,min. [eÅ–3]
+0.209, –0.159 +0.771, –0.223
2 2
[a] R1 = ∑|Fo – Fc|/Fo. [b] wR2 = {Σ[w(Fo2 – Fc ) ]/Σ[w(Fo2)2]}1/2. [c]
GooF = S = {Σ[w(Fo – Fc ) ]/(Nobsd – Nvar)}1/2
.
2
2 2
were taken from the International Tables for X-ray Crystallogra-
phy.[26] The thermal ellipsoid drawings were made with the ORTEP
program.[27] Pertinent crystal data and selected bond lengths and
bond angles of 2(1) and 3(3) are listed in Tables 1–4.
CCDC-286043 [for 2(1)] and -270916 [for 3(3)] contain the supple-
mentary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallographic
Data Center via www.ccdc.cam.ac.uk/data_request/cif.
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Received: November 9, 2005
Published Online: February 21, 2006
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