Thermal properties and reactions towards nucleophiles of an iron complex displaying an acetyl and a pyruvoyl ligands

Journal of Organometallic Chemistry 691 (2006) 3667–3678

www.elsevier.com/locate/jorganchem

Thermal properties and reactions towards nucleophiles of an

iron complex displaying an acetyl and a pyruvoyl ligands

*

´

Jean-Yves Salaun , Rene Rumin, Herve des Abbayes, Smail Triki

¨

Laboratoire de Chimie, Electrochimie Mole´culaire et Chimie Analytique, UMR CNRS-Universite´ de Bretagne Occidentale 6521 UFR Sciences

et Techniques, 6 Avenue le Gorgeu, CS 93837, 29238 Brest Ce´dex, France

Received 7 April 2006; received in revised form 11 May 2006; accepted 11 May 2006

Available online 20 May 2006

Abstract

Thermal evolution at 4 ꢀC of the structurally characterized cis(CO)₄Fe[C(O)C(O)CH₃][C(O)CH₃] (1(2)) gives rise to the cis(CO)₄Fe-

[C(O)CH₃]₂(1(3)) which, probably owing to synthetic problems, has never been described in the literature. By reaction with anionic

nucleophiles (Nu^ꢀ), 1(2) aﬀords anionic trifunctionalized metallalactones {(CO)₃Fe[C(O)CH₃][C(O)C(CH₃)(Nu)OC⁷(O);(Fe–C⁷)]}^ꢀ

(3) formed by addition of the nucleophile reagent on the b carbon of the pyruvoyl moiety followed by the cyclization of this ligand

1

on a terminal carbonyl of the complex. Anions 3 are characterized by H and ¹³C NMR and by X-ray diﬀraction for the complex with

Nu = C(H)(CO₂C₂H₅)₂. Complexes 3 are also prepared by reaction of CH₃Li with the neutral metallalactones (CO)₄Fe[C(O)C(CH₃)-

(Nu)OC⁷(O);Fe–⁷C] (2). The results of this study shed light on the reaction of cyclization of a pyruvoyl ligand as they clearly show that

the presence of a second ligand (for example CO₂R) with a labile OR group is not required to perform the formation of the metallalac-

tone ring and then that the observed reaction has no connection with organic chain-ring transformations.

Keywords: Iron complexes; Pyruvoyl ligand; Metallalactone; Nucleophilic addition

1. Introduction

bon–carbon coupling process. At 15 ꢀC this compound dis-

played a spontaneous isomerisation into the metallalactone

2(1) (Scheme 1a) [4].

The carbonylated organic ligands of transition metal

complexes have been long known to play an important role

in many catalytic carbonylation reactions [1]. However,

their complexation to metals atoms eﬃcient in catalytic

carbonylation processes, gives rise to unstable species mak-

ing the properties of these compounds diﬃcult to evaluate.

To appraise the possible intervention of complexes substi-

tuted by one or two of these organic carbonylated ligands

in mono or poly carbonylation processes, the study of sim-

ilar more stable complexes of Pt, Mn, Co, Fe have been

performed [2,3]. In the course of our study of tricarbonyla-

tion reactions induced by iron models of the type

cis(CO)₄Fe[C(O)C(O)R][C(O)R⁰], we did not observed,

for R = CH₃and R⁰= OCH₃(1(1)), the expected car-

This process looks very similar to the well known ring-

chain isomerism observed for organic c-keto-esters [5]

and, as complex 1(1) can be considered as a c-keto-ester

with a metal inserted into its organic chain, it was attractive

to establish a parallel between organic and organometallic

reactions. However, unlike the organic isomerism, the met-

allalactone formation does not require acid or base cataly-

sis and is not reversible. The cyclisation of 1(1) performed

in the presence of pronucleophile reagents (NuH) such as

C₂H₅OH, CH₃SH, HP(C₆H₅)₂, or HP(C₆H₁₁)₂gave rise

to Nu substituted metallalactones 2 (Scheme 1b) [6]. The

observed reactions are indicative of regioselective additions

of the nucleophile reagents at the b-carbonyl of the

pyruvoyl ligand of 1(1). We recently performed the same

reaction with anionic nucleophiles (C₂H₅O^ꢀ, CH₃S^ꢀ,

(C₆H₅)₂P^ꢀ, (C₆H₁₁)P^ꢀor carbanions: CH^ꢀ½C₂H₅OCðOÞꢁ -

*

Corresponding author. Tel.: +33 298016286; fax: +33 298017001.

E-mail address: jean-yves.salaun@univ-brest.fr (J.-Y. Salaun).

¨

3

2

doi:10.1016/j.jorganchem.2006.05.019

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J.-Y. Salau¨ n et al. / Journal of Organometallic Chemistry 691 (2006) 3667–3678

CH^ꢀ, [CH₃C(O)]₂CH^ꢀ, (CN)₂CH^ꢀetc) and observed the

formation of anionic trifunctionalised metallalactones 3

(Scheme 1c) [7,8]. As shown in Scheme 2, two reaction

paths can explain the formation of 3. After addition of

the nucleophile on the b-carbonyl of the pyruvoyl moiety,

the ﬁrst path (a) considers the formation of the metallalac-

tone ring by addition of the oxygen of this carbonyl on the

alkoxycarbonyl ligand with release of CH₃O^ꢀwhich, by a

further addition on a terminal carbonyl, would aﬀord 3. In

the second path (b) the cyclization of the pyruvoyl moiety

occurs on a terminal carbonyl ligand giving directly 3.

The formation of 3 in very low yield by reaction of the

neutral lactones 2 with CH₃O^ꢀsuggested the mechanism

2b as the most probable pathway of the reaction. This

assumption was reinforced by the description, in the litera-

ture, of an hydride induced cyclisation of a phenylglyoxyl

ligand on a terminal carbonyl of a manganese complex

[9]. To conﬁrm the possible formation of a metallalactone

ring by addition of the pyruvoyl ligand on a terminal car-

bonyl, it seemed appropriate to perform the reaction on

(pyruvoyl)(carbonyl)iron complexes which did not display

ligands with labile groups. The present paper describes

the synthesis, the properties and the reactions with nucleo-

philes of such compound: the cis(CO)₄Fe[C(O)-

C(O)CH₃][C(O)CH₃] (1(2)) a complex closely related to

1(1).

a

2. Results and discussion

2.1. Preparation and properties of complex 1(2)

1(2) is obtained as a pale yellow powder (45% yield) by

reaction at ꢀ70 ꢀC of one equivalent of pyruvoyl chloride

[10] with the anionic complex {Fe(CO)₄[C(O)CH₃]}^ꢀitself

prepared in situ by addition at 0 ꢀC of CH₃Li on Fe(CO)₅

[11]. Its IR spectrum displays four m(C„O) bands between

2115 and 2040 cm^ꢀ1while its ¹³C NMR spectrum exhibits

three signals at 201.8 (2 C), 201.1 and 198.9 ppm for the

terminal C„O, two singlets at 245.2 and 198.6 ppm for

the C@O of the pyruvoyl moiety and one peak at

246.7 ppm for the carbonyl of the acetyl ligand. These spec-

tra are indicative of the presence of an acetyl and of a pyru-

voyl ligands in cis position on the carbonylated complex.

Crystals suitable for an X-ray diﬀraction study are

obtained from an hexane solution at ꢀ30 ꢀC. This study

conﬁrms the structure attributed to complex 1(2). The

ORTEP drawing of the molecule is displayed on Fig. 1;

selected bond lengths and bond angles are listed in Table

1 and crystallographic data are mentioned in Table 4.

The ligands around the Fe (II) metal are disposed in a

slightly distorted octahedron geometry.

O

C

CH₃

CO

OC

C

15˚C

a)

Fe

OCH₃

O

CO

O

2(1)

CO

Fe

O

C

O

CH₃

Nu

CO

The angle between the acetyl and the pyruvoyl ligands

C(O)C(O)CH₃

CO₂CH₃

OC

C

NuH

b)

Fe

(C(5)–Fe–C(7) = 85.7 (1)ꢀ) has

a value intermediate

O

between those generally observed for complexes displaying

two organic carbonylated ligands in cis position on the

metal (88.93 (8)ꢀ for a pyruvoyl-alkoxycarbonyl [7] or

88.5 (2)ꢀ for a bis alkoxycarbonyl [12]) and those, smaller,

measured for ﬁve membered iron metallacycle (from 79.3

to 82.6ꢀ) [4,6–8,13]. As usually observed for cis disubsti-

tuted iron complexes, the two axial terminal carbonyls

are bent towards the plane which contains the two car-

bonylated organic ligands (C(5)–Fe–C(7) plane). This is

CO

2

CO

1(1)

–

CH₃

Nu

CO O

C

Nu^–

c)

OC

C

Fe

C

O

H₃C

3

Scheme 1.

-

OCH₃

Nu^-

CH₃

OCH₃

-

O

C C

CO

CH₃

Nu

C

CH₃

Nu

O

CO

Fe

O

C

OC

C

OC

C

Fe

O

C

O

C

O

C

O

OCH₃

O

CO

1(1)

Path a

CO

2

3

CO

Fe

C(O)C(O)CH₃

CO₂CH₃

OC

CO

1(1)

-

O

C

CH₃

Nu

CH₃

Nu^-

C

O

C

CO

C

OC

Path b

O

C

O

Fe

C

O

OCH₃

CO

1(1)

3

Scheme 2.

J.-Y. Salau¨ n et al. / Journal of Organometallic Chemistry 691 (2006) 3667–3678

3669

distances of the pyruvoyl and of the acetyl ligands are nor-

mal. The relatively long Fe-terminal carbonyls bonds

˚

(1.84 A) probably result from a reduced back donation

towards these ligands induced by the electron-withdrawing

eﬀects of the two organic ligands. However, it is worth not-

ing that the distance between the metal and one axial termi-

nal carbonyl (Fe–C(1) = 1.802(3)) is shorter than the

others and falls within the normal values found for this

type of bonds.

2.2. Thermolysis of 1(2)

Fig. 1. ORTEP perspective view of the molecular structure of 1(2) (50%

ellipsoids).

Complex 1(2), in solution in hexanes or CH₂Cl₂, is

found to evolve at 4 ꢀC into Fe(CO)₅, acetone (70%) and

butanedione (30%) with no trace of metallalactone com-

plex formation. A ¹³C monitoring of the reaction shows,

at the ﬁrst stage of the process, together with the formation

of butanedione and Fe(CO)₅(30% of conversion) the

appearance of a new organometallic compound (70%).

As this complex displays only one resonance at

243.4 ppm for the C@O linked to the metal, two signals

of equal intensities at 202.5 and 200.3 ppm for the terminal

carbonyls and one peak at 49.2 ppm corresponding to a

CH₃acetyl, it very probably displays two similar ligands

(acetyls) in cis position on the metal and is very likely the

cis(CO)₄Fe[C(O)CH₃]₂(1(3)) formed by a selective decarb-

onylation of the pyruvoyl ligand of 1(2). Such a decarbony-

lation of a ligand displaying a double C@O chain has

already been observed for the ethyloxalyl ligand of the

close complex: cis(CO)₄Fe[C(O)CO₂C₂H₅](CO₂C₂H₅) [17].

We were unable to isolate and to get a better characteriza-

tion of 1(3) as it very rapidly evolves thermally at 4 ꢀC to

aﬀord Fe(CO)₅and acetone. No additional formation of

butanedione was observed at this stage of the reaction.

The thermal evolution of 1(2) can be described as two con-

current reactions: (i) a decarbonylation of the pyruvoyl

ligand aﬀording 1(3) (70%) and (ii) a decarbonylating car-

bon–carbon coupling process giving rise to butanedione

and Fe(CO)₅(Scheme 3). The evolution of 1(3) into ace-

tone and Fe(CO)₅can occur either by a second decarbony-

lating carbon–carbon coupling or by a decarbonylation

Table 1

˚

Bond lengths (A) and bond angles (ꢀ) for compound 1(2)

Fe–C(1)

Fe–C(2)

Fe–C(3)

Fe–C(4)

Fe–C(5)

Fe–C(7)

C(1)–O(1)

C(2)–O(2)

C(1)–Fe–C(2)

C(1)–Fe–C(3)

C(1)–Fe–C(4)

C(1)–Fe–C(5)

C(1)–Fe–C(7)

C(2)–Fe–C(3)

C(2)–Fe–C(4)

C(2)–Fe–C(5)

C(2)–Fe–C(7)

C(3)–Fe–C(4)

C(3)–Fe–C(5)

C(3)–Fe–C(7)

C(4)–Fe–C(5)

C(4)–Fe–C(7)

1.802(3)

1.848(4)

1.840(4)

1.840(3)

2.038(4)

2.055(4)

1.142(4)

1.138(4)

96.6(2)

94.0(2)

167.8(2)

83.1(1)

83.8(1)

93.3(2)

94.6(1)

87.2(1)

172.8(1)

90.2(1)

177.1(1)

93.8(1)

C(3)–O(3)

C(4)–O(4)

C(5)–O(5)

C(5)–C(6)

C(6)–O(6)

C(6)–C(8)

C(7)–O(7)

C(7)–C(9)

C(5)–Fe–C(7)

Fe–C(1)–O(1)

Fe–C(2)–O(2)

Fe–C(3)–O(3)

Fe–C(4)–O(4)

Fe–C(5)–O(5)

Fe–C(5)–C(6)

O(5)–C(5)–C(6)

C(5)–C(6)–O(6)

C(5)–C(6)–C(8)

O(6)–C(6)–C(8)

Fe–C(7)–O(7)

Fe–C(7)–C(9)

O(7)–C(7)–C(9)

1.142(4)

1.135(4)

1.205(4)

1.547(5)

1.208(4)

1.483(5)

1.205(4)

1.491(5)

85.7(1)

177.9(3)

178.3(3)

177.2(3)

172.4(3)

124.2(3)

120.5(2)

115.3(3)

119.6(3)

116.6(3)

123.5(3)

121.0(3)

119.0(3)

119.9(3)

92.6(1)

84.5(1)

well shown by the value of the C(1)–Fe–C(4) angle: 167.8

(2)ꢀ. The two carbonyls of the pyruvoyl ligand adopt an

almost s-trans geometry with a torsion angle of 138.6 (3)ꢀ

between these two groups. This value is similar to that mea-

sured for the pyruvoyl moiety of the close complex 1(1):

141.7 (2)ꢀ [7] but is smaller than those usually observed

for a-keto acyl complexes (from 157ꢀ to 177ꢀ) [14]. It is also

worth noting that smaller values have been observed for

the homologues angles of a-keto acyl ligands of manganese

(112ꢀ [15]) or platinum (127ꢀ [16]) complexes. To minimize

the repulsions between the acetyl and the pyruvoyl moie-

ties, these two ligands adopt staggered positions; the acetyl

plane (Fe–C(7)–O(7)) is very close to the median plane of

the complex (C(5)–Fe–C(7)) as these two planes exhibit a

dihedral angle of 10ꢀ82 whereas the plane containing the

metal and the a-acetyl of the pyruvoyl ligand (Fe–C(5)–

O(5)) displays a dihedral angle of 56.91ꢀ with the C(5)–

Fe–C(7) median plane. The two oxygen atoms of the

a–C@O groups O(5) and O(7) are located from both sides

of this plane. The carbon–carbon and the carbon–oxygen

Fe(CO)₅+ CH₃C(O)C(O)CH₃

30%

CO

Fe

(ii)

(i)

C(O)C(O)CH₃

C(O)CH₃

OC

4˚C

70%

-CO

CO

1(2)

CO

Fe

C(O)CH₃

OC

CO

1(3)

4˚C

-CO

CO

Fe

C(O)CH₃

CH₃

+CO OC

OC

Fe(CO)₅+ CH₃C(O)CH₃

CO

Scheme 3.

3670

J.-Y. Salau¨ n et al. / Journal of Organometallic Chemistry 691 (2006) 3667–3678

giving rise to the intermediate (CO)₄Fe(CH₃)[C(O)CH₃]

which is supposed to evolve rapidly, even at low tempera-

ture, to give acetone by an easy sp₂–sp₃carbon–carbon

coupling.

Contrary to (CO)₄Fe[C(O)C(O)CH₃](CO₂CH₃) (1(1))

which, in the presence of pronucleophiles such as CH₃OH,

C₂H₅OH, CH₃SH, HP(C₆H₅)₃or HP(C₆H₁₁)₃at ꢀ70 ꢀC,

aﬀords very rapidly Nu substituted neutral metallalactones,

thermolysis of 1(2) at 4 ꢀC in the presence of these reagents,

only gives rise to the same products than those already

obtained when the thermolysis was performed without

nucleophile. 1(2) is also found unreactive towards anionic

nucleophiles such as CH₃O^ꢀor [CH₃C(O)]₂CH^ꢀ. On the

other hand, IR monitorings of its reaction at ꢀ70 ꢀC with

CH₃SNa, (C₆H₅)₂PLi, (C₆H₁₁)₂PLi, CH₃Li, [C₂H₅OC-

(O)]₂CHNa, (CN)₂CHNa, [CH₃C(O)][CH₃OC(O)]CHNa

or [C₂H₅OC(O)]₂(CH₃)CNa show rapid formation of new

complexes displaying mC„O bands between 2070 and

1983 cm^ꢀ1. The values of these frequencies which fall

between those observed for monofunctionalized anionic

compounds (1910 cm^ꢀ1[24]) and those displayed by neu-

tral difunctionalized iron complexes (from 2115 to

2040 cm^ꢀ1for complexes 1(1) or 1(2)) suggested, as

observed for analogous reactions performed with 1(1)

[7,8], the possible formation of anionic fac trifunctionalized

complexes 3 (Scheme 5).

The observation of three mC„O bands instead of the

two bands formally required by a fac L₃Fe(CO)₃geometry

could result as previously mentioned [7,8], from the pres-

ence of a metallacycle on these complexes. These products

are obtained as gray powders which are, for most of them,

poorly soluble in organic solvents. Their NMR spectra are

in good agreement with the proposed metallalactone tri-

functionalized anionic structure. The anionic character of

these complexes is shown in ¹³C NMR by a shift of ꢂ10

ppm toward the lower ﬁelds of the resonances of the carbo-

nyls linked to the metal. Thus, the signals of the carbonyl

of the acetyl groups linked to the metal are found between

256.2 and 285.4 ppm those of the cyclic C(O)O between

219.2 and 237.9 ppm while the resonances of the terminal

carbonyl ligands are located between 200.5 and

213.1 ppm. The formation of a metallalactone ring is

shown by the presence of a resonance between 92.9 and

97.7 ppm corresponding to that of a cyclic quaternary car-

bon. The presence of two diﬀerent substituents on the qua-

ternary carbon of 3(1) (Nu = SCH₃) together with the fac

trisubstitution of the metal, explain the observation of

two isomers for this complex. They are obtained as a 55/

45% mixture. The formation of these two isomers is shown

by the splitting in two of most of the ¹³C NMR resonances

The formation of 1(3) is of importance as bis-acyl iron

monomer complexes described in the literature are scarce.

They either present a cyclic structure [13,18] or display elec-

tron-withdrawing perﬂuorinated carbonylated ligands [19].

The observation of the bis-acyl complex 1(3) by decarbony-

lation of 1(2) suggests that a synthetic problem could

explain the lack of achievement of such complexes. Indeed

our attempts to prepare 1(3) by reaction of CH₃C(O)Cl

with [(CO)₄Fe{C(O)CH₃}]^ꢀfailed as the only product of

this reaction, even performed at ꢀ70 ꢀC, was a bimetallic

complex displaying two acetyl ligands in bridging position

(Scheme 4). This complex is identiﬁed by comparison with

an authentic sample as we already obtained it by reaction

of [(CO)₄Fe{C(O)CH₃}]^ꢀwith oxalyl chloride [20].

Though known for over than 30 years, the number of this

type of iron dimers is very limited. Most of them are pre-

pared by oxidation of anions [(CO)₄Fe{C(O)R}]^ꢀwith

one electron oxidants (R = CH₃, C₆H₅[11a,20,21]; C₉H₁₉

[21c,21d]; N(C₂H₅)₂[22] N^iꢀPr₂[20,23]. In the present pro-

cess, as observed for the reaction of [(CO)₄Fe{C(O)CH₃}]^ꢀ

with oxalyl chloride [20], or when [(CO)₄Fe{C(O)N^iꢀPr₂}]^ꢀ

is allowed to react with ClC(O)N^iꢀPr₂[20] or HgCl₂[23] the

organic chloride can play the part of the oxidant.

2.3. Reaction of 1(2) with nucleophiles

As its thermolysis did not give rise to a metallalactone

complex we tried to induce this metallalactone formation

by reacting 1(2) with various nucleophiles.

CO

C(O)CH₃

OC

Fe

_

CO

Fe

C

1(3)

CO

CH₃C(O)Cl

OC

+

C(O)CH₃

H₃C

CO

-70˚C

C

O

OC

CO

Fe CO

OC Fe

OC

CO

Scheme 4.

Nu = SCH₃: 3(1)

Nu = P(C₆H₅)₂: 3(2)

–

O

H₃C

Nu = P(C₆H₁₁)₂: 3(3)

CH₃

C

O

CO

Nu = CH₃: 3(4)

C(O)C(O)CH

C(O)CH₃

³Nu^–

OC

C

Nu = CH(CO₂C₂H₂)₂: 3(5)

Nu = CH(CN)₂: 3(6)

Nu = CH(CO₂CH₃)[C(O)CH₃]: 3(7)

Nu = C(CH₃)(CO₂C₂H₂)₂: 3(8)

Nu = OCH₃: 3(9)

Fe

Nu

C

O

CO

O

1(2)

3

Scheme 5.

J.-Y. Salau¨ n et al. / Journal of Organometallic Chemistry 691 (2006) 3667–3678

3671

of 3(1). Thus four resonances are observed at 285.4, 265.7,

262.7 and 259.9 ppm for the two acetyl groups linked to the

metal and two signals for the cyclic C(O)O at 226.2 and

221.1 ppm; for the cyclic quaternary carbon at 96.2 and

94.6 ppm; for the acetyl CH₃at 54.4 and 47.6 ppm; for

the CH₃of the cycle at 23.6 and 22.6 ppm and for the

SCH₃at 12.4 and 11.6 ppm. Probably due to the overlap

of two signals, the three terminal carbonyls are observed

as ﬁve resonances at 211.7, 210.6, 209.7(2), 209.2, and

208.6 ppm. In the same way, 3(2) (Nu = P(C₆H₅)₂) is also

obtained as a mixture of two isomers (70/30%). Its ¹³C

NMR spectrum is not very diﬀerent from that observed

for 3(1) (see experimental section). It is worth noting that,

probably due to a poor resolution of this ¹³C NMR spec-

trum the coupling between the phosphor atom and the cyc-

lic quaternary carbon cannot be observed. The formation

of two isomers is conﬁrmed by the presence of two reso-

nances at 10.38 and 9.16 ppm in the ³¹P NMR spectrum

of 3(2). Complex 3(3) which displays a bulky Nu group

(P(C₆H₁₁)₂) is formed as a single isomer shown by a lack

of splitting of its ¹³C NMR signals and by the presence

of a single signal at 13.45 ppm in its ³¹P NMR spectrum.

Again no interaction is observed between the cyclic quater-

nary carbon and the phosphorus of this complex. The bulk-

iness of P(C₆H₁₁)₂suggests the formation of the isomer

displaying its acetyl ligand and the P(C₆H₁₁)₂group on

both side of the metallacycle plane. Complex 3(4)

(Nu = CH₃) which presents two methyl substituents on

its cyclic quaternary carbon is formed as one isomer. Its

¹³C NMR spectrum (see experimental section) then dis-

plays one resonance for each carbon of the molecule. The

fac geometry around the metal center induces the inequiv-

alency of the two methyl groups on the cyclic quaternary

carbon shown by the presence of two signals at 24.5 and

15.75 ppm in ¹³C NMR. The bulky ^ꢀC(H)(CO₂C₂H₅)₂

used as nucleophile induces the formation of only one iso-

mer of the corresponding metallalactone (3(5)). The pres-

ence of a single isomer in the reaction mixture is shown,

in ¹³C NMR, by the observance of one signal for each car-

bon of the molecule. The resonances of the two acetyl

linked to the metal are observed at 269.8 and 265.3 ppm,

those of the cyclic C(O)O group at 230.65, of the cyclic

quaternary carbon at 92.1 ppm and of the two methyl

groups at 22.05 and 46.15 (acetyl) ppm. The asymmetry

of the metallalactone ring induces a diastereotopy of the

central carbon of the malonyl group shown by the presence

of a single signal at 55.1 ppm for this carbon whereas the

two CO₂C₂H₅substituents are non equivalent (signals of

equal intensities at 169.0 and 167.5; at 62.8 and 62.4 and

at 13.75 and 13.55 ppm). The same diastereotopy is

observed for 3(6) the anionic metallalactone obtained by

reaction of 1(2) with ^ꢀC(H)(C„N)₂. However, this com-

plex (see experimental part) is obtained as a 70/30% mix-

ture of two isomers. Four resonances at 113.4, 113.05,

112.6 and 112.0 ppm are therefore observed for the C„N

of the malonyl group whereas two signals corresponding

to the central atom of this substituent are found at 30.8

and 30.6 ppm. Complex 3(7) (Nu = C(H)[C(O)CH₃]-

(CO₂CH₃)) is also obtained as two isomers (80/20%) and

moreover displays a non symmetric aceto-acetyl substitu-

ent on the quaternary carbon of its non symmetrical metal-

lacycle. For this reason, two diastereoisomers of the above

mentioned isomers are formed and the ¹³C NMR spectrum

of 3(7) displays, for each of its carbon, two major signals

and two minor resonances (see experimental section). Com-

plex 3(8) (Nu = (CH₃)C(CO₂C₂H₅)₂), substituted by a

bulky group, is obtained as one isomer. However, as

observed for 3(5) and 3(6), the two CO₂C₂H₅groups of

(CH₃)C(CO₂C₂H₅)₂are not equivalent. Two signals are

then observed for their carbon atoms whereas one reso-

nance is observed for the central carbon of this malonyl

group and for its methyl substituent (see Section 4).

2.4. Crystallographic study of complex 3(5)

(Nu = C(H)(CO₂C₂H₅)₂)

Single crystals of 3(5) are obtained from an hexanes/

dicloromethane (80:20) mixture at ꢀ40 ꢀC. The ORTEP

diagram of the structure is displayed in Fig. 2, selected

bond lengths and angles are mentioned in Tables 2 and

3, and crystallographic data can be found in Table 4.

The crystallographic study conﬁrms for 3(5) the already

proposed anionic fac trisubstituted {(CO)₃Fe[C(O)CH₃]-

{C(O)C(CH₃)[C(H)(CO₂C₂H₅)₂]OC7(O);Fe–C7}}^ꢀstruct-

ure. In the solid state, the study shows the presence of four

essentially equivalent entities named a, b, c and d which

only exhibit slight variations in their bond lengths and

angle values probably due to the relatively low precision

of the crystallographic data. The coordination about the

central Fe atom of these entities can be described as a dis-

torted octahedron. Each metal center is substituted by

three terminal carbonyl ligands (in fac positions), by an

acetyl moiety and by a metallalactone ring with a diethylm-

alonyl substituent on the quaternary carbon (C(6)) of this

ligand. The malonyl group and the acetyl ligand are located

on each side of the lactone plane. The crystallized isomer is

very probably the same compound than that already

observed in solution by NMR spectroscopy. Recall that a

close geometry has already been observed by us for the alk-

oxycarbonyl homologue of 3(5) [8]. The presence on the

metal of a ﬁve membered ring induces, as generally

observed for such metallacycles [4,6–8,13], a value of the

bite angle smaller than that required by a regular octahe-

dron: C(7)–Fe–C(5) from 83.1(6) to 84.0(6)ꢀ. Its opposite

angle on the metal center: C(2)–Fe–C(3) then displays a

higher value: from 97.1(9) to 100.7(8)ꢀ. As Shown by the

angles C(4)–Fe–C(5) (from 80.8(6) to 82.3(7)ꢀ) and C(4)–

Fe–C(7) (from 83.1(6) to 84.0(6)ꢀ the acetyl ligand is bent

toward the metallacycle. The reduced dihedral angles

observed between the median plane C(5)–Fe–C(7) and

Fe–C(7)–O(6) (4.29ꢀ) or between C(5)–Fe–C(7) and Fe–

C(5)–C(6) (3.22ꢀ) show the quasi planeness of the lactone

ring of the molecule. O(6) and C(6) only deviate from this

˚

median plane by ꢀ0.0930 A and ꢀ0.0829 A respectively

3672

J.-Y. Salau¨ n et al. / Journal of Organometallic Chemistry 691 (2006) 3667–3678

Fig. 2. Structure of 3(5)d. (a) ORTEP view of one anionic entity (50% ellipsoids), the similar views of a, b and c anions are not shown. (b) Perspective view

showing the K3 and K4 ions surrounded by two c and two d forms of 3(5), the similar view involving K1, K2, Fea and Feb is not shown. (i): (ꢀx + 1, y,

ꢀz + 3/2).

Table 2

˚

Bond lengths (A) and bond angles (ꢀ) observed for the four anionic forms (a, b, c, and d) of 3(5)

a

b

c

d

Fe–C(1)

Fe–C(2)

Fe–C(3)

Fe–C(4)

Fe–C(5)

Fe–C(7)

O(4)–C(4)

O(5)–C(5)

O(7)–C(7)

O(6)–C(6)

O(6)–C(7)

O(8)–C(9)

O(11)–C(10)

C(5)–C(6)

1.786(19)

1.86(2)

1.81(2)

2.056(16)

1.84(2)

1.985(15)

1.188(19)

1.249(19)

1.187(15)

1.417(18)

1.362(16)

1.206(19)

1.174(17)

1.67(3)

1.76(2)

1.80(2)

1.798(17)

1.786(17)

1.830(18)

2.042(14)

1.966(16)

1.934(14)

1.214(16)

1.210(17)

1.208(15)

1.436(15)

1.402(16)

1.197(17)

1.246(16)

1.55(2)

1.788(16)

1.80(2)

1.827(19)

2.017(16)

1.974(1)

1.943(14)

1.244(18)

1.194(17)

1.209(16)

1.459(15)

1.389(17)

1.195(18)

1.222(18)

1.589(19)

1.808(16)

2.016(14)

1.958(15)

1.962(15)

1.223(17)

1.192(16)

1.193(15)

1.403(15)

1.382(16)

1.142(18)

1.186(16)

1.61(2)

C(2)–Fe–C(3)

C(2)–Fe–C(1)

C(2)–Fe–C(4)

C(2)–Fe–C(7)

C(2)–Fe–C(5)

C(1)–Fe–C(5)

C(1)–Fe–C(7)

C(4)–Fe–C(5)

C(4)–Fe–C(7)

C(4)–Fe–C(1)

C(5)–Fe–C(7)

C(7)–O(6)–C(6)

Fe–C(7)–O(7)

Fe–C(7)–O(6)

O(7)–C(7)–O(6)

Fe–C(5)–O(5)

Fe–C(5)–C(6)

O(5)–C(5)–C(6)

O(6)–C(6)–C(5)

97.1(9)

95.1(8)

86.5(7)

89.7(6)

166.4(7)

96.5(8)

89.9(6)

81.4(7)

85.5(6)

100.7(8)

95.6(8)

85.6(7)

86.1(7)

164.6(7)

96.3(7)

90.9(6)

82.3(7)

87.6(6)

178.1(7)

84.0(6)

116.8(10)

132.4(11)

117.3(10)

1103.0(12)

130.2(11)

112.5(10)

117.3(13)

109.2(11)

98.9(7)

95.3(7)

85.3(7)

87.9(6)

163.9(7)

97.7(7)

88.3(6)

80.8(6)

86.2(6)

98.1(7)

97.1(8)

85.7(8)

86.6(6)

163.9(7)

95.1(6)

89.1(6)

81.5(6)

87.8(5)

175.1(8)

83.4(7)

174.1(7)

83.1(6)

175.6(6)

83.2(6)

118.1(12)

128.7(11)

116.7(9)

114.6(13)

135.0(17)

115.9(9)

109.1(19)

105.8(13)

115.3(10)

131.2(11)

117.6(9)

111.2(11)

129.5(11)

113.3(10)

117.3(13)

110.7(11)

119.8(10)

130.3(11)

115.8(9)

113.9(13)

130.9(11)

113.3(9)

115.7(12)

107.8(10)

J.-Y. Salau¨ n et al. / Journal of Organometallic Chemistry 691 (2006) 3667–3678

3673

Table 3

K–O distances (A) and angles between K1-4 and O7a–c (ꢀ) observed for 3(5)

˚

K(1)–O(4b)

K(1)–O(6a)

K(1)–O(7a)

K(1)ⁱⁱ-O(7b)

K(1)–O(7b)

K(1)–O(8a)

O(7b)ⁱⁱ–K(1)–O(7a)

O(7b)ⁱⁱ–K(1)–O(7b)

O(7a)–K(1)–O(7b)

2.658(11)

2.859(10)

2.863(9)

2.684(10)

2.879(9)

2.775(12)

86.6(3)

K(2)–O(4a)

2.669(12)

2.770(9)

2.646(9)

2.987(10)

2.944(10)

2.687(11)

80.7(3)

K(3)–O(4c)

K(3)–O(6d)

K(3)ⁱ-O(7c)

K(3)–O(7c)

K(3)–O(7d)

K(3)–O(8d)

O(7c)ⁱ–K(3)–O(7c)

O(7c)ⁱ–K(3)–O(7d)

O(7c)–K(3)–O(7d)

2.690(10)

2.808(9)

2.651(9)

2.862(9)

2.905(9)

2.802(11)

76.8(3)

K(4)–O(4d)

K(4)–O(6c)

K(4)–O(7c)

K(4)–O(7d)

K(4)ⁱ-O(7d)

K(4)–O(8c)

O(7d)–K(4)–O(7d)ⁱ

O(7d)–K(4)–O(7c)

O(7d)ⁱ–K(4)–O(7c)

2.626(12)

2.767(8)

2.933(9)

2.655(9)

2.884(9)

2.754(11)

75.1(3)

K(2)ⁱⁱ-O(6b)

K(2)ⁱⁱ-O(7a)

K(2)–O(7a)

K(2)ⁱⁱ-O(7b)

K(2)–O(8b)

O(7a)ⁱⁱ–K(2)–O(7b)ⁱⁱ

O(7a)ⁱⁱ–K(2)–O(7a)

O(7b)ⁱⁱ–K(2)–O(7a)

75.9(3)

78.3(3)

74.0(3)

79.9(3)

80.3(3)

77.8(3)

80.6(3)

76.2(3)

Atoms are labeled as mentioned in Fig. 2b. Symmetry transformations used to generate equivalent atoms (i) ꢀx + 1, y, ꢀz + 3/2 and (ii) ꢀx + 2, y,

ꢀz + 3/2.

Table 4

comes to light that the four K(3), K(4), K(3)ⁱand K(4)ⁱions

Crystal data for compounds 1(2) and 3(5)

and the four carbonyl oxygen atoms of the cyclic C(O)O

Compound

1(2)

3(5)

groups of the two c anions and the two d anions (O(7c),

O(7d), O(7c)ⁱand O(7d)^I) are alternately located at the cor-

ners of a distorted cube. This cubo¨ıd structure displays

small O–K–O angles (from 75.1(3)ꢀ to 80.6(3)ꢀ) and larger

K–O–K angles (from 96.2(3)ꢀ to 104.2(3)ꢀ). Edges of diﬀer-

ent lengths are also observed. Short edges are measured

between K(4) and O(7d), K(3)ⁱand O(7d) and between

Empirical formula

Molecular weight

Space group

C₉H₆O₇Fe

281.99

P2₁/c

8.960(1)

9.725(1)

13.022(1)

99.136(8)

1120.2(4)

4

C₆₆H₆₅O₄₄Fe₄K₄

2083.78

C2/c

24.262(2)

32.278(2)

27.503(2)

113.596(6)

19738(2)

8

˚

a [A]

˚

b [A]

˚

c [A]

b [ꢀ]

3

˚

V [A ]

˚

their symmetric atoms. These distances: 2.655(9) A and

Z

˚

q_calcd[g cm^ꢀ3

]

1.67

1.40

2.651(9) A respectively are by far shorter than those mea-

sured for the eight other edges of the cube (average of

2.90 A). They correspond to an interaction between the

Temperature

100(2)

13.62

568

100(2)

9.36

8488

l [cm^ꢀ1

F(000)

]

˚

oxygen of the carbonyl of a cyclic C(O)O group (O(7))

and a potassium ion which is not linked by other oxygen

atoms to the same entity. In the crystal, each potassium

is surrounded by seven oxygen atoms; four of them belong

to the same molecule: for example K(3) is linked to d by the

carbonyl oxygen of the cyclic C(O)O group (O(7d)), by the

ether oxygen of the same function (O(6d)) and by the two

carbonyl oxygen atoms of the malonyl substituent (O(8d)

and O(11d)). K3 is also linked to c via O(4c) the oxygen

of the acetyl ligand and via O(7c) the carbonyl oxygen of

the cyclic C(O)O function of this entity. At last, K(3) is

connected to cⁱ(symmetric of c) by O(7c)ⁱthe carbonyl oxy-

gen of the cyclic C(O)O of this anion. Considering a

{(CO)₃Fe[C(O)CH₃]{C(O)C(CH₃)[C(H)(CO₂C₂H₅)₂]OC-

(O)}^ꢀpattern, for example d, as mentioned above, this

anion is linked to K(3) by the two oxygen atoms of its cyc-

lic C(O)O function (O(7d) and O(6d)) and by the two car-

bonyl oxygens of its malonyl group (O(8d) and O(11d)). d

is also connected to K(4)⁽ⁱ⁾by O(7d) the carbonyl oxygen of

its C(O)O group and by O(4d) the oxygen of its acetyl

ligand and d is also linked to K(4) via the same O(7d) atom

(the oxygen carbonyl of the cyclic C(O)O). It is worth not-

ing that O(5d) the oxygen of the cyclic carbonyl does not

interact with any potassium. The interaction of O(7) the

oxygen of the cyclic C(O)O group with three potassium cat-

ions does not induce a signiﬁcant lengthening of the

Reﬂ. measured

2h range

Reﬂ. Unique/R_int

Reﬂ. with I > 2r(I)

N_v

3544

51030

5.00–44.04

1200/0.03

975

178

0.026

0.029 (Fo)

0.999

+0.291, ꢀ0.262

5.84–47.48

11059/0.0654

8605

1094

0.1284

0.3244 (Fo²)

1.030

R^a

b,c

R_w

GooF^d

3

˚

Dq_max,min/eA

1.551, ꢀ0.58

a

R = RjjF_oj ꢀ jF_cjj/RF_oj.

b

R_w(F_o) = {R[w(F_oꢀ F_c)²]/R[w(F_o)²]}^1/2

2

1=2

c

R_wðF _oÞ ¼ wR2 ¼ fR½wðF ²_oꢀ F _c²Þ ꢁ=R½wðF _o²Þ ꢁg

.

2

1=2

d

GooF ¼ S ¼ fR½wðF ²_oꢀ F _c²Þ ꢁ=N_obsꢀ N_varÞg

and are located on the same side of this plane. The methyl

substituent of C(6) is also located on the same side of the

median plane (distance between C(15) and the C(7)–Fe–C

˚

(5) plane = ꢀ1.32 A). It adopts a slightly more axial posi-

tion than that of the second substituent of C(6): the malo-

nyl group, which is found in a pseudo equatorial position

˚

shown by a distance of 1.15 A. between C(8) (the central

atom of the malonyl group) and the C(7)–Fe–C(5) plane.

We mentioned above that, in the solid state, 3(5) can be

described as four slightly diﬀerent anionic entities named

a, b, c, and d. The perspective view of the potassium cations

environments shows that two a and two b anions are linked

to four potassium ions (two equivalent K(1) and two equiv-

alent K(2)). In the same way, two c and two d anionic enti-

ties are linked to two equivalent K(3) and two equivalent

K(4) ions. Lets consider this last case drawn in Fig. 2. It

˚

C(7)@O(7) double bond (from 1.187(15) to 1.209(16) A

˚

compared to an average of 1.20 A measured for neutral lac-

tones [4,8]. On the other hand, the interaction of the two

oxygen atoms (O(7) and O(6)) of the C(O)O cyclic function

3674

J.-Y. Salau¨ n et al. / Journal of Organometallic Chemistry 691 (2006) 3667–3678

of a molecule with the same potassium ion induces the

presence of small O(7)–C(7)–O(6) angles ( from 110.3(12)

to 114.6(13)ꢀ) and of large O(7)–C(7)–Fe angles (from

128.7(11) to 132.4(11)ꢀ). The homologues angles of neutral

lactones are respectively of 118ꢀ and 127ꢀ [4,8].

the b-carbonyl followed by an addition of the oxygen of

this carbonyl on a terminal carbonyl ligand. The diﬀer-

ence of reactivity observed between 1(1) which displays

an alkoxycarbonyl co-ligand and 1(2) whose metal center

bear an acetyl, could result from the diﬀerence between

the electronic eﬀects of these two ligands. The electron-

withdrawing eﬀect of the alkoxycarbonyl ligand of 1(1)

can explain the enhanced reactivity of this complex

toward anionic nucleophiles whereas the lability of the

alkoxy group of the same ligand the formation of metall-

alactones by reaction with pronucleophiles. Further

experiments are at present under progress to extend this

reaction to all complexes bearing terminal carbonyls

and a ligand with a double C(O) chain.

2.5. Preparation of anionic complexes 3 by reaction of

neutral lactones 2 with CH₃Li

We brieﬂy mentioned, in the introductive part the

achievement of neutral lactones 2 by reaction of complex

1(1) with pronucleophiles. These compounds 2, by reac-

tion with CH₃Li, are supposed to aﬀord anionic metall-

alactones 3 by addition of ^ꢀCH₃on one of their

terminal carbonyl ligands. Indeed, 2(2) (Nu = CH₃), the

neutral lactone substituted by two methyl groups, aﬀords

rapidly, at ꢀ70 ꢀC a complex displaying the same IR and

¹³C NMR spectra than 3(4). However, the yield of forma-

tion of 3(4) by this method remains lower (15%) than the

yield of formation of the same product by reaction of

1(2) with CH₃Li (65%). An analogous reaction aﬀords

3(1) (Nu = SCH₃) by addition of CH₃Li with the appro-

priate neutral lactone. The process is slow (one hour at

ꢀ70 ꢀC) and the yield remains low (20%). It is notewor-

thy that 3(1) is formed in the same proportion of isomers

(55/45%) than that obtained by reaction of 1(2) with

CH₃SNa. As described above, the reaction of 1(2) with

CH₃ONa failed to aﬀord the anionic trifunctionalized lac-

tone substituted by a methyl and a methoxy groups. This

complex (3(9)) is still obtained in 20% yield by reacting

CH₃Li with the neutral metallalactone substituted by a

methyl and a methoxy groups. Recall that this lactone

was prepared by thermolysis of 1(1) in methanol. Com-

plex 3(9) is formed as a mixture of isomers (40/60%);

its ¹³C NMR spectrum is in good agreement with the

spectra of analogous compounds 3 except that, a shift

toward the lower ﬁelds of the resonances of the cyclic

quaternary carbon substituted by the methoxy group

(two peaks at 114.8 and 117.8 ppm), is observed in ¹³C

NMR.

4. Experimental

4.1. Materials

All reactions where performed under argon using stan-

dard Schlenk techniques. All solvents were puriﬁed by pre-

liminary distillation from an appropriate drying agent [25].

Deuterated dichloromethane or THF were stored under

argon over molecular sieves before use. NMR spectra were

recorded at 0 ꢀC on a Bruker AC 300, a Bruker AMX 3-

400 or a Bruker DRX 500 spectrometers with chemical

shifts reported in d values relative to residual protonated

1

solvents for H NMR spectra and to the solvent for ¹³C

NMR spectra. ³¹P NMR spectra were externally referenced

to H₃PO₄(85%). Infrared spectra were recorded in the

range 2300–1600 cm^ꢀ1in solution in hexane, dichloro-

methane or tetrahydrofuran with a FT-IR NEXUS NICO-

LET spectrometer. Gas chromatographic analyses were

performed on a Hewlett-Packard 5890 instrument using a

CP SIL 25 m column. Elemental analyses were performed

by the Service Central d’Analyses du CNRS. All reagents

were purchased from commercial sources and used as

received. {(CO)₄Fe[C(O)CH₃]}^ꢀ[11], CH₃SNa [26],

(C₆H₁₁)₂PLi and (C₆H₆)₂PLi [27] and stabilized carbanions

(NaC(H)(CO₂C₂H₅)₂, NaC(H)(C„N)₂, NaC(H)[C(O)-

CH₃](CO₂CH₃), and NaC(CH₃)(CO₂C₂H₅)₂) [8,28,29]

were prepared in situ as previously described. ClC(O)-

C(O)CH₃[10] was obtained after distillation as a mixture

with HC(O)OCH₃. The percentages of these two com-

3. Conclusion

This work shows that spontaneous metallalactones for-

mation previously observed on a complex displaying a

pyruvoyl and an alkoxycarbonyl ligands does not occur

on pyruvoyl complexes which do not present a ligand

with a labile group. A decarbonylation of the pyruvoyl

ligand together with a carbon–carbon coupling are then

observed by thermolysis. This study also conﬁrms that

on a complex bearing a pyruvoyl, an acetyl and terminal

carbonyl ligands, the pyruvoyl b-carbonyl carbon is the

most electrophilic site of the molecule. The formation

of anionic trifunctionalized metallalactones by reaction

of this complex with anionic nucleophiles conﬁrms unam-

biguously the cyclization of the pyruvoyl ligand to occur

by an attack of the nucleophile reagent on the carbon of

1

pounds were measured by H NMR.

4.2. Preparation of

Fe(CO)₄[C(O)CH₃][C(O)C(O)CH₃] (1(2))

Reaction at ꢀ10 ꢀC of 15 mmol of Fe(CO)₅(1.97 ml)

dissolved in 50 ml of THF with 10 mmol of CH₃Li

(6.25 ml of a 1.6 N solution in diethyl ether) aﬀorded,

as shown by IR monitoring, {Fe(CO)₄[C(O)C(O)CH₃]}^ꢀ

[11]. After one hour the temperature of the solution

was lowered to ꢀ30 ꢀC and 10 mmol (1.065 g) of ClC(O)-

C(O)CH₃[10], in solution in 5 ml of THF, was slowly

added under stirring. After two hours at this temperature,

J.-Y. Salau¨ n et al. / Journal of Organometallic Chemistry 691 (2006) 3667–3678

3675

the solvent was evaporated to dryness at 0 ꢀC. The yellow

4.4.2. Reaction of 1(2) with NaOCH₃or

NaC(H)[C(O)CH₃]₂

residue was washed with two portions of 5 ml of hexanes

at ꢀ70 ꢀC and extracted with three fractions of a

CH₂Cl₂/hexanes (10/90%) mixture at ꢀ10 ꢀC. These frac-

tions were joined and the volume of the resulting solution

slowly reduced under vacuum at ꢀ40 ꢀC. The pale yellow

solid which precipitated was ﬁltered oﬀ and washed with

hexanes at ꢀ70 ꢀC (2 · 3 ml) to aﬀord, after recrystalliza-

tion in an hexanes/CH₂Cl₂(95/5%) mixture at ꢀ40 ꢀC,

1.27 g; (45% yield) of complex 1(2). IR (hexanes, cm^ꢀ1):

m(C„O) 2115 (w), 2065 (w,sh), 2055 (w, sh), 2040 (s);

m(C@O) 1780 (w, br), 1740 (w, br), 1680 (w,br). ¹H

NMR (CD₂Cl₂, 273 K, d ppm): 2.7 (s, 3H, CH₃acetyl),

2.4 (s, 3H, CH₃pyruvoyl). ¹³C {¹H} NMR (CD₂Cl₂,

273K, d ppm): 246.7, 245.2 (C@O bound to the metal),

201.8 (2), 201.1, 198.9, 198.6 (terminal C„O and organic

C@O), 51.2 (CH₃acetyl), 23.2 (CH₃pyruvoyl). Anal.

Calc. for C₉FeH₆O₇: C, 38.33; Fe, 19.80; H, 2.14. Found:

C, 38.25; Fe, 19.89; H, 2.17.

As shown by IR monitoring, when 1(2) (1.5 mmol,

423 mg) was reacted, according to the general procedure

described for this process, with one of these two nucleo-

philes no reaction was observed even if the temperature

of the solution was brought up to 0 ꢀC.

4.4.3. Reaction of 1(2) with NaSCH₃, preparation of 3(1)

The reaction of 1(2) (1.5 mmol, 423 mg) with 1.5 mmol

of NaSCH₃(105 mg) was found to give rise to 3(1)

obtained as a white powder (400 mg, 75% yield). IR

(THF, cm^ꢀ1): m(C„O) 2056 (s), 1997 (br, s); m(C@O)

1652 (sh), 1637 (m), 1595 (w). ¹H NMR (400 MHz,

[D₈] THF, 273 K, d ppm): 2.3 [s, 3H, C(O)CH₃], 1.75

(s, 3H, SCH₃), 1.36 (s, 3H, CH₃). ¹³C {¹H} NMR

[400 MHz, [D₈] THF, 273 K, d ppm] two isomers

(55:45): 285.4, 265.7, 262.7, 259.9 [C(O)CH₃and cyclic

C(O)], 226.2, 221.1 [cyclic C(O)O], 211.7, 210.6, 209.7

(2), 209.2, 208.6 (terminal CO), 96.2, 94.6 (quaternary

carbon), 54.4, 47.6 [C(O)CH₃], 23.6, 22.6 (CH₃), 12.4,

11.6 (SCH₃).

4.3. Thermal evolution of 1(2)

A portion of 0.282 g (1 mmol) of 1(2) in 15 ml of

CH₂Cl₂was stirred at 4 ꢀC for one hour. The formation

of acetone (70%) and 2,3 butanedione (30%) was detected

by gas chromatographic analyses of the solution by com-

parison with authentic samples.

4.4.4. Reaction of 1(2) with LiP(C₆H₅)₂, preparation of

3(2)

Complex 1(2) (1.5 mmol, 423 mg) was treated with

1.5 mmol of LiP(C₆H₅)₂to give 390 mg (55% yield) of

3(2) obtained as a grey powder. IR (THF, cm^ꢀ1):

m(C„O) 2058 (s), 1995 (s) 1985 (s); m(C@O) 1646 (sh),

1618 (s), 1576 (sh). ¹H NMR (400 MHz, [D₈] THF,

273 K, d ppm) two isomers (70:30): 7.8–7.05 (m, 10H,

C₆H₅), 2.36 [s, 2.1H, C(O)CH₃], 2.06 [s, 0.9 H,

C(O)CH₃], 1.35 (s, 0.9H, CH₃), 1.18 (s, 2.1H, CH₃). ¹³C

{¹H} NMR [400 MHz, [D₈] THF, 273 K, d ppm] two iso-

mers (70:30): 270.3, 270.7, 261.5, 267.4 [C(O)CH₃and

cyclic C(O)], 227.0, 227.7 [cyclic C(O)O], 213.1, 209.7,

209.5, 206.9, 207.3 (terminal CO), from 137.7 to 128.6

numerous signals (aromatics), 97.7, 97.3 (s, quaternary

carbon), 47.5, 46.2 [C(O)CH₃], 23.6, 23.0 (CH₃). ³¹P

NMR ([D₈] THF, 273 K, d ppm) two isomers (70:30)

10.38 (70%), 9.16 (30%).

¹³C NMR monitoring of the reaction: 60 mg of 1(2) in

solution in cold CD₂Cl₂was introduced into an NMR

tube. The reaction was monitored at ꢀ3 ꢀC, each spectrum

being drawn over a period of 30 min. The thermal evolu-

tion of 1(2) was shown by the appearance of the resonances

of the butanedione at 23 and 197 ppm, of Fe(CO)₅at

211 ppm and by the presence of four signals of equal inten-

sities at 243.4, 202.5, 200.3 and 49.2 ppm corresponding to

1(3). The presence of free CO in solution was shown by a

signal at 184 ppm. The peaks of 1(3) then slowly disap-

peared and the formation of acetone was shown by the res-

onances at 206.0 and 29.8 ppm.

4.4. Reaction of 1(2) with anionic nucleophiles

4.4.1. General procedure for the preparation of anionic

trifunctionalized metallalactones 3

4.4.5. Reaction of 1(2) with LiP(C₅H₁₁)₂, preparation of

3(3)

A cold solution of 1.5 mmol of the anionic nucleophile

reagent was added under stirring to a solution of 1.5 mmol

of 1(2) (423 mg) in 30 ml of THF at ꢀ70 ꢀC. IR monitoring

showed the reaction to be generally fast. After 1 h at

ꢀ70 ꢀC, the temperature was raised to 0 ꢀC and the solvent

evaporated to dryness. The residue was washed with hex-

anes at 0 ꢀC to aﬀord a grey powder. With the exception

of 3(5) (Nu = C(H)(CO₂C₂H₅)₂) and 3(8) (Nu = C(CH₃)-

(CO₂C₂H₅)₂), these anions 3 were found only sparingly

soluble in most organic solvents. 3(5) and 3(8) were crystal-

lized from a hexanes/CH₂Cl₂(70/30%) mixture at ꢀ40 ꢀC.

It was not possible to obtain correct elemental analyses for

3 since these complexes are very unstable.

According to the general procedure, complex 1(2)

(1.5 mmol, 423 mg) was reacted with 1.5 mmol of

LiP(C₆H₁₁)₂to give 330 mg (45% yield) of 3(3) (one isomer)

obtained as a white powder. IR (THF, cm^ꢀ1): m(C„O)

2058 (s), 1991 (s); m(C@O) 1640 (sh), 1616 (m), 1560 (sh).

¹H NMR (400 MHz, [D₈] THF, 273 K, d ppm) numerous

signals between 2.1 and 1.1. ¹³C {¹H} NMR (400 MHz,

[D₈] THF, 273 K, d ppm) one isomer: 282.9, 270.7

[C(O)CH₃and cyclic C(O)], 230.5, [cyclic C(O)O], 209.9,

209.1, 208.2 (terminal CO), 97.7 (s, quaternary carbon),

46.6 [C(O)CH₃], from 32.0 to 30.1 10 peaks (cyclohexyl),

24.8 (CH₃). ³¹P NMR ([D₈] THF, 273 K, d ppm) one iso-

mer 13.45.

3676

J.-Y. Salau¨ n et al. / Journal of Organometallic Chemistry 691 (2006) 3667–3678

4.4.6. Reaction of 1(2) with LiCH₃, preparation of 3(4)

As above, 1.5 mmol of 1(2) (423 mg) was reacted with

1.5 mmol of CH₃Li (950 lL of a 1.6 M solution in diethyl

ether). After treatment of the reaction, 300 mg (65% yield)

of 3(4) was obtained as a grey powder. IR (THF, cm^ꢀ1):

m(C„O) 2069 (m), 2003 (s) 1987 (s); m(C@O) 1746 (s),

1731 (sh), 1620 (s). ¹H NMR (400 MHz, [D₈] THF, 273 K,

d ppm): 2.16 [s, 3H, C(O)CH₃], 1.40 (s, 3H, CH₃), 1.32 (s,

3H, CH₃). ¹³C {¹H} NMR (400 MHz, [D₈] THF, 273 K, d

ppm): 271.45, 261.2 [C(O)CH₃and cyclic C(O)], 226.15 [cyc-

lic C(O)O], 209.8, 209.5, 208.4 (terminal CO), 94.05 (quater-

nary carbon), 47.4 [C(O)CH₃], 24.5, 15.75 (CH₃).

of 3(7) as a grey powder. IR (THF, cm^ꢀ1): m(C„O) 2067

(s), 2004 (s), 1990 (sh); m(C@O) 1624 (s), 1599 (sh), 1575

1

(sh), 1523 (m). H NMR (400 MHz, [D₈] THF, 273 K, d

ppm) two isomers 80/20%: 3.78 (br s, 1H, CH), 3.56 (br

s, 3H, OCH₃) 2.32 [br s, 3H, CH₃C(O)], 2.11 [br s, 3H,

CH₃C(O)], 1.23 (br s, 2.4H, CH₃), 1.11 (br s, 0.6H, CH₃).

¹³C {¹H} NMR (400 MHz, [D₈] THF, 273 K, d ppm)

two ‘‘cis–trans’’ isomers 80/20% and two diastereoisomers:

269.9, 269.5, 268.6, 268.4, 261.1, 259.95, 256.3, 256.2

[C(O)CH₃and cyclic C(O)], 222.9, 222.8, 222.3, 222.1 [cyc-

lic C(O)O], 209.35, 209.3, 209.2, 209.1, 208.4, 208.15, 208.1,

203.3, 203.1 202.1, 201.9, 200.5 (terminal CO), 169.3, 169.1,

168.4, 168.15 [organic C(O)O], 93.5, 92.9, 92.8, 92.6 (qua-

ternary carbon), 62.3, (2) 62.0, 59.7(CH) 52.7, 52.5 (2),

52.2 (OCH₃), 47.6, 47.2, 46.6, 46.4 [C(O)CH₃], 33.7, 32.9,

32.6, 29.9 [C(O)CH₃], 23.0, 22.4, 21.8, 20.8 (CH₃).

4.4.7. Reaction of 1(2) with NaC(H)(CO₂C₂H₅)₂,

preparation of 3(5)

Reaction of complex 1(2) (1.5 mmol, 423 mg) with

1.5 mmol of NaC(H)(CO₂C₂H₅)₂was found to aﬀord a

white residue after evaporation of the solvent. This white

powder was washed with three portions of hexanes at

ꢀ40 ꢀC and then extracted with a hexanes/CH₂Cl₂mixture

(3 · 10 ml) at ꢀ10 ꢀC. These fractions were joined and the

volume of the resulting solution was reduced under vac-

uum at ꢀ40 ꢀC to aﬀord a white precipitate of 3(5)

(520 mg, 75% yield). IR (THF, cm^ꢀ1): m(C„O) 2069 (m),

2003 (s), 1987 (s); m(C@O) 1746 (s), 1731 (sh), 1620 (s).

¹H NMR (400 MHz, CD₂Cl₂, 273 K, d ppm): 4.26 (br q

J = 7 Hz, 4H, OCH₂), 3.72 (s, 1H, CH) 2.40 [s, 3H,

C(O)CH₃], 1.21 (br t J = 7 Hz, 6H, CH₃) 1.01 (s, 3H,

CH₃). ¹³C {¹H} NMR [400 MHz, CD₂Cl₂, 273 K, d ppm]

one isomer: 269.8, 265.3 [C(O)CH₃and cyclic C(O)],

230.65 [cyclic C(O)O], 208.5, 206.8, 205.3 (terminal CO),

169.0, 167.5 [organic C(O) ester], 92.1 (quaternary carbon),

62.8, 62.4 (OCH₂), 55.1 (CH), 49.15 [C(O)CH₃], 22.05

(CH₃), 13.75, 13.55 (CH₂CH₃).

4.4.10. Reaction of 1(2) with NaC(CH₃)(CO₂C₂H₅)₂

preparation of 3(8)

Complex 1(2) (1.5 mmol, 423 mg) reacted with 1.5 mmol

of NaC(CH₃)(CO₂C₂H₅)₂. After evaporation of the solvent

a white residue was obtained. This white powder was washed

with three portions of hexanes at ꢀ40 ꢀC and extracted with

a hexanes/CH₂Cl₂mixture (3 · 10 ml) at ꢀ10 ꢀC. These

fractions were joined and the volume of the resulting solu-

tion was reduced under vacuum at ꢀ40 ꢀC to aﬀord a white

precipitate of 3(8) (320 mg, 45% yield). IR (THF, cm^ꢀ1):

m(C„O) 2071 (s), 2005 (s), 1995 (sh); m(C@O) 1733 (sh),

1721 (sh), 1652 (m), 1612 (s), 1576 (sh). ¹H NMR

(400 MHz, CD₂Cl₂, 273 K, d ppm): 4.12 (br m, 4H,

OCH₂), 2.51 [br s, 3H, C(O)CH₃], 1.20 (br m, 12H, other

CH₃). ¹³C {¹H} NMR (400 MHz, CD₂Cl₂, 273 K, d ppm),

one isomer: 269.05, 267.9 [C(O)CH₃and cyclic C(O)],

237.9, [cyclic C(O)O], 207.1, 206.2, 205.8 (terminal CO),

175.6, 168.2 [organic C(O) ester], 96.1, (quaternary carbon),

62.9, (CH), 61.5, 58.4 (OCH₂), 46.5 [C(O)CH₃], 21.6 (CH₃),

19.1 (CH₃), 13.7, 13.4 (CH₂CH₃).

4.4.8. Reaction of 1(2) with NaC(H)(CN)₂, preparation of

3(6)

The reaction of 1(2) (1.5 mmol, 423 mg) with 1.5 mmol

of NaC(H)(C„N)₂was found to give rise to 3(6) obtained

as a white powder (220 mg, 40% yield). IR (THF, cm^ꢀ1):

m(C„N) 2194 (w), 2174 (w); m(C„O) 2062 (s), 1997 (s),

1983 (sh); m(C@O) 1666 (m), 1644 (s), 1611 (m). ¹H

NMR (400 MHz, [D₈] THF, 273 K, d ppm) two isomers

70/30%: 4.81 (br s, 0.7H, CH), 4.63 (br s, 0.3H, CH),

2.40 [br s, 2.1H, CH₃C(O)], 2.19 [br s, 0.9H, CH₃C(O)],

1.25 (br s, 0.9H, CH₃), 1.02 (br s, 2.1H, CH₃). ¹³C {¹H}

NMR (400 MHz, [D₈] THF, 273 K, d ppm): 270.0, 268.7,

262.4, 259.4 [C(O)CH₃and cyclic C(O)], 219.9, 219.2 [cyclic

C(O)O], 209.3, 209.1, 208.4, 208.0, 206.5, 201.9 (terminal

CO), 113.4, 113.05, 112.6, 112.0 (C„N), 89.8, 89.6 (quater-

nary carbon), 47.3, 47.0 [C(O)CH₃], 30.8, 30.6 (CH), 21.7,

21.5 (CH₃).

4.5. Preparation of anionic complexes 3 by reaction of

neutral lactones 2 with CH₃Li

4.5.1. General procedure

One mmol of CH₃Li (0.625 lL of a 1.6 M solution in

ether) was added to a solution of one mmol of the neutral

lactone 2 in 20 ml of THF at ꢀ70 ꢀC. The reaction was

monitored by IR (substitution of the t(C„O) of 2 at

2120, 2075, 2065 and 2050 cm^ꢀ1by their homologues of

the trifunctionalized anionic complex 3 at 2060, 2000,

and 1985 cm^ꢀ1. After evaporation of the solvent, the resi-

due was washed with three portions (5 ml) of CH₂Cl₂at

ꢀ40 ꢀC to aﬀord 3 as a gray powder.

4.5.2. Preparation of 3(4)

4.4.9. Reaction of 1(2) with

Two hundred and eighty-two milligrams of 2(2)

(Nu = CH₃) were found to aﬀord 45 mg (15% yield) of

3(4) identiﬁed by comparison with the spectroscopic prop-

erties of an authentic sample.

NaC(H)[C(O)CH₃](CO₂CH₃) preparation of 3(7)

Complex 1(2) (1.5 mmol, 423 mg) reacted with 1.5 mmol

of NaC(H)[C(O)CH₃](CO₂CH₃) to give 315 mg (50% yield)

J.-Y. Salau¨ n et al. / Journal of Organometallic Chemistry 691 (2006) 3667–3678

3677

4.5.3. Preparation of 3(1)

315 mg of 2(3) (Nu = SCH₃) gave rise to 67 mg (20%

yield) of 3(1).

5. Supplementary material

Complete crystallographic details are included in the

supporting information. CCDC reference numbers

293145 and 603315 for 1(2) and 3(5) respectively contain

the supplementary crystallographic data for this paper.

These data can be obtained free of charge from the Cam-

bridge Crystallographic Data Centre via www.ccdc.cam.ac.

uk/data_request/cif.

4.5.4. Preparation of 3(9)

After reaction of 300 mg of 2(1) (Nu = OCH₃) with

CH₃Li, 64 mg of 3(9) were obtained as a white powder.

IR (THF, cm^ꢀ1): m(C„O) 2060 (s), 1998 (s); m(C@O)

1652 (m), 1625 (s), 1576 (m). ¹H NMR (400 MHz, CD₂Cl₂,

273 K, d ppm): 3.5 (br s, 3H, OCH₃), 2.3 [br s, 3H,

C(O)CH₃], 1.1 (br s, 3H, CH₃). ¹³C {¹H} NMR

(400 MHz, CD₂Cl₂, 273 K, d ppm), two isomers (60/

40%): 272.6, 269.6, 268.5, 265.7 [C(O)CH₃and cyclic

C(O)], 221.0, 219.7 [cyclic C(O)O], 210.3, 210.2, 209.2,

208.2 (terminal CO), 117.8, 114.8 (quaternary carbon),

53.40, 52.9 (OCH₃), 50.45, 49.7 [C(O)CH₃], 20.5, 19.2

(CH₃).

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Full text of DOI:10.1016/j.jorganchem.2006.05.019

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