Preparation of acetylide and propadienylidene complexes of iron(II)

Article abstract of DOI:10.1016/S0277-5387(02)01063-X

Depending on the nature of the phosphine ligands, the reaction of phosphite-containing FeCl₂ solutions with propargylic alcohols HC≡CCRR′(OH) affords propadienylidene [Fe(=C=C=CPh₂){P(OEt)₃}₅] (BPh₄)₂ and [FeCl(=C=C=CPh₂){PPh(OEt)₂}4]BPh₄ complexes and acetylide [Fe{C≡CCRR′(OH)}{P(OEt)₃}₅]BPh₄ derivatives (R=R′ =Ph; R=Me, R′=Ph). In contrast, the reaction of phosphite-containing FeCl₂ solutions with terminal alkynes RC≡CH affords mononuclear [Fe(C≡CPh){P(OEt)₃}₅]BPh₄ and binuclear [{Fe[P(OEt)₃]₅}₂(μ-1,4-C≡ CC₆H₄C≡C)](BPh₄)₂ acetylide derivatives. All the new complexes were characterised by IR and ¹H, ³¹P and ¹³C NMR data, and a geometry in solution was also established.

Full text of DOI:10.1016/S0277-5387(02)01063-X

Polyhedron 21 (2002) 1755Á1760
/
www.elsevier.com/locate/poly
Preparation of acetylide and propadienylidene complexes of iron(II)
Gabriele Albertin, Pierluigi Agnoletto, Stefano Antoniutti
Dipartimento di Chimica, Universita` Ca’ Foscari di Venezia, Dorsoduro 2137, I-30123 Venice, Italy
Received 21 March 2002; accepted 15 May 2002
Abstract
Depending on the nature of the phosphine ligands, the reaction of phosphite-containing FeCl2 solutions with propargylic alcohols
HCÅ
complexes and acetylide [Fe{CÅ
reaction of phosphite-containing FeCl2 solutions with terminal alkynes RCÅ
/
CCRR?(OH) affords propadienylidene [Fe(Ä
CCRR?(OH)}{P(OEt)3}5]BPh4 derivatives (Rꢀ
CH affords mononuclear [Fe(CÅ
C)](BPh4)2 acetylide derivatives. All the new complexes were characterised by IR
/
CÄ
/
CÄ
/
CPh2){P(OEt)3}5](BPh4)2 and [FeCl(Ä
/
CÄ
/
CÄ
/
CPh2){PPh(OEt)2}4]BPh4
Ph). In contrast, the
CPh){P(OEt)3}5]BPh4
/
/
R?ꢀPh; RꢀMe, R?ꢀ
/
/
/
/
/
and binuclear [{Fe[P(OEt)3]5}2(m-1,4-CÅ
/
CC6H4CÅ
/
and 1H, 31P and 13C NMR data, and a geometry in solution was also established. # 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Iron; Acetylide; Vinylidene; Propadienylidene
1. Introduction
2. Experimental
The chemistry of transition-metal allenylidene com-
2.1. General considerations and physical measurements
plexes [1] [M]Ä
/
CÄ
/
CÄ/CR2 continues to attract interest,
both due to their potential usefulness in organic synth-
esis [2] and their interesting reactivity [3]. A number of
complexes have been synthesised in recent years [1],
generally by reacting propargylic alcohols with appro-
priate transition metal derivatives, and involving, as
metal centres, the Cr and Fe triads, Mn, Re, Rh and Ir.
Of these, ruthenium allenylidene constitutes the largest
group; relatively few examples are reported for iron. In
All synthetic work was carried out under an inert
atmosphere (Ar or N2) using standard Schlenk techni-
ques or a Vacuum Atmosphere dry-box. Once isolated,
the complexes turned out to be quite air-stable and were
stored at ꢁ25 8C. All solvents used were dried over
/
appropriate drying agents, degassed on a vacuum line,
and distilled into vacuum-tight storage flasks. Anhy-
drous FeCl2 was purchased from Chempur and used as
received. Phenyldiethoxyphosphine (PPh(OEt)2) was
prepared by the method of Rabinowitz and Pellon [7];
triethylphosphite was an Aldrich product, purified by
fact, apart from the cyclopentadienyl [CpFe(Ä
CPh2)(dppe)]BF4 and [Cp*Fe{ÄCÄCÄC(OMe)Me}(dp-
pe)]BPh4 (dppeÄPh2PCH2CH2PPh2) species [4], only
carbonyl complexes [5] of the type [Fe(ÄCÄCÄ
CRR?)(CO)2P2][PꢀP(OMe)3, PEt3] and [Fe(ÄCÄCÄ
CRR?)(CO)4 are described.
/
CÄ
/
CÄ
/
/
/
/
/
/
/
/
distillation under nitrogen. Alkynes PhCÅ
/
CH and HCÅ
/
/
/
/
/
CCPh2(OH), HCÅCCHPh(OH), HCÅCCH2(OH), HCÅ
/
/
/
CCMePh(OH) were Aldrich products, used without
further purification. 1,4-Diethynylbenzene was prepared
following the method previously reported [8]. Other
reagents were purchased from commercial sources in the
highest available purity and used as received. IR spectra
were recorded on Digilab Bio-Rad FTS-40 or Nicolet
Magna 750 FT-IR spectrophotometers. NMR spectra
(1H, 13C, 31P) were obtained on a Bruker AC200
We previously reported [6] the reactions of terminal
alkynes with phosphite-containing iron(II) complexes
which led to enynyl, acetylide and vinylidene complexes.
We have now extended these studies to include pro-
pargylic alcohols. Both new propadienylidene and
acetylide iron(II) complexes can be prepared, and the
results of these investigations are reported here.
spectrometer at temperatures between ꢁ
/
90 and ꢂ
/
30 8C, unless otherwise stated. H and 13C{1H} spectra
1
* Corresponding author. Fax: ꢂ
/
39-041-257-8517
E-mail address: albertin@unive.it (G. Albertin).
are referred to internal tetramethylsilane; 31P{1H}
0277-5387/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
PII: S 0 2 7 7 - 5 3 8 7 ( 0 2 ) 0 1 0 6 3 - X

1756
G. Albertin et al. / Polyhedron 21 (2002) 1755Á1760
/
chemical shifts are reported with respect to 85% H3PO4,
with downfield shifts considered positive. The SwaN-
MR software package [9] was used to treat NMR data.
The conductivity of 10ꢁ3 mol dmꢁ3 solutions of the
complexes in MeNO2 at 25 8C was measured with a
CDM 83 Radiometer.
mmol) were added. The reaction mixture was stirred for
2 h and an excess of NEt3 (1.4 cm3, 10 mmol) was added.
After 2 h of stirring at r.t., the solvent was removed
under reduced pressure, giving a brown oil which was
treated with EtOH containing an excess of NaBPh4
(0.68 g, 2 mmol). A brown solid slowly separated out
from the resulting solution, which was filtered and
crystallised from CH2Cl2 (2 cm3) and EtOH (5 cm3);
2.2. Synthesis of complexes
yield: ]
Anal. Calc. for C64H104BFeO16P5: C, 56.9; H, 7.8.
Found: C, 57.2; H, 8.0%. LMꢀ
50.4 S cm2 molꢁ1
/
30%.
2.2.1. [Fe(Ä
/
CÄ
/
CÄ
/
CPh2){P(OEt)3}5](BPh4)2 (1) and
[Fe{CÅCCPh2(OH)}{P(OEt)3}5]BPh4 (3a)
/
/
.
Anhydrous FeCl2 (0.126 g, 1 mmol) and an excess of
P(OEt)3 (1 cm3, 6 mmol) were placed in a three-necked
flask (25 cm3). The suspension was stirred for 1 h and
2.2.4. [Fe(CÅ
/
CPh){P(OEt)3}5]BPh4 (3c)
Anhydrous FeCl2 (0.63 g, 5 mmol) and an excess of
P(OEt)3 (5.0 cm3, 30 mmol) were placed in a three-
necked flask (50 cm3), and the resulting suspension was
stirred for about 1 h. EtOH (15 cm3) and then an excess
of the appropriate alkyne (15 mmol) were added and the
reaction mixture refluxed for 15 min. The solvent was
removed under reduced pressure, giving an oil which
was treated with EtOH (4 cm3) containing an excess of
NaBPh4 (3.42 g, 10 mmol). A yellow solid slowly
separated out, and was filtered and crystallised from
then 10 cm3 of EtOH and a solution of HCÅ
/
CCPh2(OH) (0.208 g, 1 mmol) in 2 cm3 of EtOH were
added. The reaction mixture was stirred for 2 h, treated
with an excess of NEt3 (0.28 cm3, 2 mmol), and stirred
for a further 2 h. The solvent was removed under
reduced pressure, giving an oil which was treated with
EtOH (4 cm3) containing an excess of NaBPh4 (0.68 g, 2
mmol). A dark-pink solid, containing both compounds
1 and 3a, slowly separated out, and was filtered and
crystallised fractionally. Typical separation involved the
CH2Cl2 (2 cm3) and EtOH (5 cm3); yield: ]
Anal. Calc. for C62H100BFeO15P5: C, 57.0; H, 7.7.
Found: C, 56.8; H, 7.8%. LMꢀ
58.5 S cm2 molꢁ1
/35%.
slow cooling to ꢁ25 8C of a saturated solution of the
/
mixture of compounds in EtOH (5 cm3) and enough
CH2Cl2 to dissolve the solid at room temperature (r.t.).
/
.
The first solid separated was acetylide 3a, with yield: ]
15%; propadienylidene 1 was obtained with yield: ]
40%.
Anal. Calc. for C93H125B2FeO15P5 (1): C, 65.1; H, 7.3.
Found: C, 65.2; H, 7.2%. LMꢀ
121.4 S cm2 molꢁ1
Anal. Calc. for C69H106BFeO16P5 (3a): C, 58.7; H,
7.6. Found: C, 58.9; H, 7.5%. LMꢀ
56.7 S cm2 molꢁ1
/
2.2.5. [{Fe[P(OEt)3]5}2(m-1,4-CÅ
/
CC6H4CÅ
/
/
C)](BPh4)2 (4)
An excess of P(OEt)3 (1.0 cm3, 6 mmol) was added to
0.126 g (1 mmol) of anhydrous FeCl2 in a 25-cm3 three-
necked flask and the resulting suspension stirred for 1 h.
/
.
Tetrahydrofurane (10 cm3) and a solution of 1,4-HCÅ
/
/
.
CC6H4CÅ
/
CH (63 mg, 0.5 mmol) in 3 cm3 in THF were
added and, after 2 h of stirring, an excess of NEt3 (1.4
cm3, 10 mmol) was further added. The reaction mixture
was stirred for 3 h and then the solvent evaporated to
dryness under reduced pressure, giving a brown oil
which was treated with 4 cm3 of EtOH. The addition to
the resulting solution of an excess of NaBPh4 (0.68 g, 2
mmol) in 2 cm3 of EtOH caused the separation of an
2.2.2. [FeCl(Ä
/
CÄ
/
CÄ
/
CPh2){PPh(OEt)2}4]BPh4 (2)
A suspension of anhydrous FeCl2 (0.126 g, 1 mmol) in
an excess of PPh(OEt)2 (1.2 cm3, 6 mmol) was stirred for
1 h and then a solution of HCÅ
/
CCPh2(OH) (0.208 g, 1
mmol) in 10 cm3 of EtOH was added. The reaction
mixture was stirred for 2 h and then an excess of NEt3
(0.28 cm3, 2 mmol) was added. After 2 h of stirring, the
solvent was evaporated to dryness, giving an oil which
was treated with EtOH (4 cm3) containing an excess of
NaBPh4 (0.68 g, 2 mmol). A dark-pink solid separated
out, and was filtered and crystallised from CH2Cl2 (2
orangeÁ
from CH2Cl2 (2 cm3) and EtOH (5 cm3); yield: ]
Anal. Calc. for C118H194B2Fe2O30P10: C, 55.9; H, 7.7.
Found: C, 56.1; H, 7.8%. LMꢀ
124.5 S cm2 molꢁ1
/
brown solid, which was filtered and crystallised
/25%.
/
.
cm3) and EtOH (5 cm3); yield: ]
Anal. Calc. for C79H90BFeClO8P4: C, 68.1; H, 6.5; Cl,
2.5. Found: C, 68.0; H, 6.3; Cl, 2.7%. LMꢀ
51.3 S cm2
molꢁ1
/
55%.
/
3. Results and discussion
.
Propadienylidene
{P(OEt)3}5](BPh4)2 (1) and [FeCl(Ä
complexes
[Fe(Ä
/
CÄ
/
CÄ
/
CPh2)-
2.2.3. [Fe{CÅ
/
CCMePh(OH)}{P(OEt)3}5]BPh4 (3b)
/
CÄ
/
CÄ
/CPh2)-
Anhydrous FeCl2 (0.126 g, 1 mmol) and an excess of
P(OEt)3 (1 cm3, 6 mmol) were placed in a three-necked
flask (25 cm3). The suspension was stirred for 1 h and
{PPh(OEt)2}4]BPh4 (2) were prepared by allowing
iron(II) chloride solutions containing an excess of
phosphite to react with propargylic alcohol, as shown
in Scheme 1.
then EtOH (10 cm3) and HCÅ
/CCMePh(OH) (0.15 g, 1

G. Albertin et al. / Polyhedron 21 (2002) 1755Á
/1760
1757
[FeCl{PPh(OEt)2}4{Ä
/
CÄ
/
C(H)C(OH)Ph2}]ꢂ
form, yielding chloropropadienylidene 2 by treatment
may
with NEt3. However, an acetylide complex of the type
[FeCl{CÅ
/
CCPh2(OH)}{PPh(OEt)2}4] may also form by
treatment with NEt3, but in this case probably in low
yield, and this prevents its separation as a solid.
The reactions with HCÅ/CPh2(OH) were also studied
in the presence of Brønsted acid (HBF4, CF3SO3H), but
no evidence of formatione of propadienylidene com-
plexes was detected. This result is rather surprising,
because an acid is generally used to promote the loss of
H2O in hydroxy-vinylidene species to give the Ä
/
CÄ
/
CÄ
/
CPh2 ligand while, in our case, only in the presence of
NEt3 the propadienylidene species 1, 2 were isolated.
Probably, the hydroxy-vinylidene bound to an iron
fragment containing phosphites as ancillary ligands
requires NEt3 to give propadienylidene, and the results
show as both acid and basic media can promote the loss
of H2O in the reaction of propargylic alcohol.
Scheme 1.
Propargylic alcohols different from HCÅ
of the type HCÅCCPhMe(OH), HCÅCCH2(OH), or
HCÅCCHPh(OH), also react with phosphite-containing
/
CCPh2(OH),
/
/
The reaction depends on the nature of the phosphite,
affording pentakis complex 1 with P(OEt)3, or chloro-
derivative 2 with PPh(OEt)2. Furthermore, a mixture of
propadienylidene 1 and acetylide 3a (ratio 2.7:1) forms
in the case of Eq. (1), and these were separated by
fractional crystallisation. The formation of both com-
plexes 1 and 3a is not surprising, as propargylic alcohol
probably tautomerises on the iron centre (Scheme 2),
giving a hydroxy-vinylidene [A] which, in the presence of
NEt3, can either lose H2O to give propadienylidene 1 or
undergo deprotonation, affording the new acetylide 3a
(Scheme 2).
Phosphite-containing FeCl2 solutions in ethanol
probably contain a mixture of phosphite complexes of
the type [FeClP5]ꢂ, FeCl2P4 and [FeP6]2ꢂ, analogous to
those observed in THF as solvent [10], with the pentakis
species predominating in the case of P(OEt)3. Treatment
/
FeCl2 solutions, but afford mixtures of products whose
IR spectra exclude the presence of propadienylidene
ligands. However, in the case of HCÅ
pale-yellow solid was isolated, which was characterised
CCMePh(OH)}{P(OEt)3}5]BPh4
/CCMePh(OH), a
as the acetylide [Fe{CÅ
/
(3b) derivative (Scheme 3).
These results on the reactivity of propargylic alcohols
with phosphite-containing iron(II) solutions indicate
that the nature of both the phosphite ligand and the
acetylene play an important role in determining the
reaction course and the stoichiometry of the final
products. In fact, only with the diphenyl HCÅ
/
CCPh2(OH) species can propadienylidene complexes 1
and 2 be prepared, containing the pentakis(phosphite)
FeP5 fragment in the case of P(OEt)3 (1); with the
of these solutions with HCÅ/CCPh2OH may afford
bulkier PPh(OEt)2 ligand, chloro-species [FeClP4(Ä
/
CÄ
/
intermediates of type [A], whose reaction with NEt3
gives final species 1 and 3a. In contrast, in the case of
CÄ
/
CPh2)]ꢂ (2) was obtained. Acetylide species 3 can
also be prepared, but only in the case of the compound
with P(OEt)3 ligand do solid samples result.
PPh(OEt)2,
a
hydroxy-vinylidene of the type
Good analytical data were obtained for propadieny-
lidene complexes 1 and 2, which are purple solids stable
in air and in solution of polar organic solvents, where
they behave as 2:1 (1) or 1:1 (2) electrolytes [11].
Scheme 2. [Fe]ꢂ ꢀ
/
[FeClP5]ꢂ
.
Scheme 3.

1758
G. Albertin et al. / Polyhedron 21 (2002) 1755Á1760
/
Table 1
IR and NMR data for iron complexes
a
b,c
b,e
Compound
IR
1H NMR
Spin
system NMR
31P{1H}
13C{1H} NMR
b,d
/n¯
Assgnt
d
Assgnt
d (J Hz)
d (J Hz)
Assgnt
(cmꢁ1
)
1
2
[Fe(ÄCÄCÄCPh2){P(OEt)3}5]-
(BPh4)2
1950 m n(CÄCÄC) 4.04 (m)
1.40 (t)
1.24 (t)
POCH2CH3 AB4
POCH2CH3
dA 139.9
dB 138.4
320.0 (m, br) Ca
230.3 (m, br) Cb
JABꢀ119.3 148.4 (s)
63.2 (s, br)
16.1 (s, br)
Cg
POCH2CH3
POCH2CH3
Ca
[FeCl(ÄCÄCÄCPh2){PPh(OEt)2}4]- 1918 m n(CÄCÄC) 3.62 (br)
BPh4
POCH2 CH3 A4
POCH2CH3 A2B2
156 (br)
319.7 (qnt)
JCPꢀ27
239.7 (s, br)
f
1.12 (br)
dA 169.3
dB 157.6
JABꢀ73.0
Cb
152.5 (s)
Cg
POCH2CH3
64.9 (s, br)
16.1 (s, br)
120.1 (m)
103.1 (m)
POCH2CH3
Cb
Ca
3a [Fe{CÅCCPh2(OH)}{P(OEt)3}5]-
BPh4
2091 m n(CÅC)
4.20 (m)
1.40 (t)
1.37 (t)
POCH2 CH3 AB4
POCH2CH3
dA 154.8
dB 152.3
JABꢀ107.2 75.5 (s)
63.2 (s, br)
62.4 (d)
Cg
POCH2CH3
16.1 (s, br)
119.2 (m)
110.3 (m)
POCH2CH3
Cb
Ca
POCH2CH3
g
g
g
3b Fe{CÅCCMePh(OH)}{P(OEt)3}5]- 2074 m n(CÅC)
BPh4
8.65 (br)
4.26 (m)
4.14 (m)
1.34 (t)
OH
POCH2 CH3
AB4
dA 155.5
dB 152.7
JABꢀ106.5 63.0 (s, br)
POCH2CH3
62.1 (d)
46.9 (s)
16.2 (s)
8.87 (s)
1.29 (t)
Cg
POCH2CH3
C(CH3)
Cb
g
g
3c [Fe(CÅCPh){P(OEt)3}5]BPh4
2089 m n(CÅC)
4.31 (br)
4.16 (br)
1.34 (t, br) POCH2CH3
POCH2 CH3 AB4
dA 154.8
dB 151.5
119.0 (m)
108.7 (m)
Ca
JABꢀ105.8 [AB4X system:
dX 108.7
JAXꢀꢁ22.25
JBXꢀ47.3]
62.7 (s, br)
POCH2CH3
POCH2CH3
61.6 (d)
15.9 (s, br)
4
[{Fe[P(OEt)3]5}2(m-1,4-
CÅCC6H4CÅC)](BPh4)2
2085 m n(CÅC)
4.29 (m) POCH2 CH3 AB4
1.33 (t, br) POCH2CH3
dA 155.2
dB 152.3
JABꢀ106.5
a
b
c
d
e
f
In KBr pellets.
In CD2Cl2 at 25 8C.
Phenyl proton resonances are omitted.
Positive shift downfield from 85% H3PO4.
Phenyl carbon resonances are omitted.
At ꢁ70 8C.
g
In (CD3)2CO.
The IR and NMR data (Table 1) support the
1 and 319.7 ppm for 2. The spectra also reveal the
signals due to the Cb and Cg of the propadienylidene
proposed formulation and allow a geometry in solution
to be established. The IR spectra show a medium-
intensity band at 1950 cmꢁ1 for 1 and 1918 cmꢁ1 for 2,
attributed to the n(CÄCÄC) of the propadienylidene
ligand at 239.7Á
tively.
In the temperature range ꢂ
31P{1H} NMR spectrum of the [Fe(Ä
/
230.3 and 152.5Á148.4 ppm, respec-
/
/
20 to ꢁ
/
80 8C, the
/
CÄCÄ
/
/
CPh2)P5]2ꢂ
ligand. However, support for the presence of the Ä
/
CaÄ
/
cation 1 appears as an AB4 multiplet, in agreement with
CbÄCgPh2 group in the complexes comes from the
/
geometry (I). In contrast, the 31P spectrum of the related
13C{1H} NMR spectra, which show the characteristic
highly deshielded Ca carbon resonance at 320.0 ppm for
complex [FeCl(Ä
/
CÄ
/
CÄ
/
CPh2)P4]ꢂ (2) is temperature-

G. Albertin et al. / Polyhedron 21 (2002) 1755Á
/1760
1759
dependent and the sharp singlet which appears at ꢂ
20 8C changes as temperature falls and resolves into
an A2B2 multiplet at ꢁ50 8C.
/
/
These results are difficult to interpret, because octa-
hedral geometry with the halogenide and propadienyli-
dene ligands in a mutually cis position should give an
ABC2- or AB2C-type multiplet, whereas, in trans
geometry, a sharp singlet is expected. However, the
presence of inequivalent phosphorus nuclei at low
temperature for 2 may also be interpreted on the basis
of trans geometry (II), in which the four PPh(OEt)2
phosphite ligands are made inequivalent by the different
arrangement of the phenyl and ethoxy groups of one
phosphite with respect to the other.
Examples of inequivalent phosphorus nuclei in octa-
hedral complexes containing four PPh(OEt)2 ligands in
a plane have recently been reported for FeHCl[P-
Ph(OEt)2]4 [6c], MnH(CO)[PPh(OEt)2]4 [12] and [Re-
Cl(ArN2){PPh(OEt)2}4]ꢂ [13]. These precedents
support the hypothesis of the existence, for 2, of trans
Scheme 4.
The IR spectra of both mononuclear (3c) and bi-
nuclear (4) acetylide complexes show only one medium
intensity band, at 2089 and 2085 cmꢁ1, respectively, due
to the nCÅC of the acetylide ligand. The 13C{1H} NMR
spectra of 3c also confirm the presence of the RCÅ
group, showing the characteristic signals of the Ca and
Cb carbon atoms. Lastly, in the temperature range ꢂ30
to ꢁ
80 8C, the 31P spectra of both complexes 3c and 4
geometry in which restricted rotation around the FeÃ
/P
bond at low temperature makes the phosphite ligands
‘two-by-two’ inequivalent in the complex.
/C
The IR spectra of acetylide complexes 3a and 3b show
the n(CÅC) of the acetylide ligand as a medium-intensity
band at 2091 cmꢁ1 for 3a and 2074 cmꢁ1 for 3b. The
13C{1H} NMR spectra also confirm the presence of the
acetylide ligand in both complexes showing the char-
/
/
appear as AB4 multiplets, in agreement with the
presence of a pentakis(phosphite) fragment in these
acetylide derivatives.
acteristic Ca and Cb carbon signals at 110.3Á
/
103.1 and
120.1Á119.2 ppm, respectively (Table 1). They also show
/
the signals of the Cg carbon atoms at 46.9 (3b) and 75.5
ppm (3a), and the proton NMR spectrum of 3b displays
a broad signal at 8.65 ppm, attributed to the OH group
Acknowledgements
of the CÅ
/
CCMePh(OH) ligand. Lastly, an AB4 multi-
plet is present for both complexes in the 31P spectra, in
agreement with the proposed formulation.
The financial support of MIUR (Rome)*
di Ricerca Scientifica di Rilevante Interesse Nazionale,
Cofinanziamento 2000Á2001*is gratefully acknowl-
edged. We thank Daniela Baldan for technical assis-
tance.
/
Programmi
/
/
The results obtained with propargylic alcohols
prompted us to extend study to other terminal alkynes.
The results are summarised in Scheme 4 and show the
formation of pentakis(phosphite) acetylide complexes 3c
and 4. However, while the mononuclear complexes 3
had previously been prepared by us (except 3c) follow-
ing a different method [6], the dinuclear [{FeP5}2(m-4,4?-
References
[1] (a) M.I. Bruce, Chem. Rev. 98 (1998) 2797;
(b) V. Cadierno, M.P. Gamasa, J. Gimeno, Eur. J. Inorg. Chem.
(2001) 571.
CÅ
/
CC6H4CÅ
/
C)]2ꢂ (4) is new, and was isolated as a
pale-yellow solid and characterised.
The formation of acetylide in these reactions is not
surprising, and probably involves deprotonation of a
[2] (a) H. Werner, M. Laubender, R. Wiedemann, B. Windmuller,
¨
Angew. Chem., Int. Ed. Engl. 35 (1996) 1237;
(b) R. Wiedemann, P. Steinert, O. Gevert, H. Werner, J. Am.
Chem. Soc. 118 (1996) 2495;
vinylidene Ä
CÄ
C(H)R}P4]2ꢂ. Such a vinylidene ligand probably
formes by a 1,2-hydrogen shift of a coordinate h2-
alkyne group [14Á16]. Deprotonation by NEt3 or an
/
CÄ
/
C(H)R intermediate of the type [Fe{Ä
/
/
(c) A. Furstner, M. Picquet, C. Bruneau, P.H. Dixneuf, J. Chem.
¨
Soc., Chem. Commun. (1998) 1315;
(d) M. Picquet, D. Touchard, C. Bruneau, P.H. Dixneuf, New J.
Chem. (1999) 141;
/
excess of phosphite of the vinylidene intermediate gives
the final acetylide derivative.
(e) K.J. Harlow, A.F. Hill, J.D.E.T. Wilton-Ely, J. Chem. Soc.,
Dalton. Trans. (1999) 285;
Analytical and spectroscopic data (Table 1) support
the formulation of acetylide complexes 3c and 4.
(f) Y. Nishibayashi, I. Wakiji, Y. Ishii, S. Uemura, M. Hidai, J.
Am. Chem. Soc. 123 (2001) 3393 (and references therein).

1760
G. Albertin et al. / Polyhedron 21 (2002) 1755Á1760
/
[3] (a) M.A. Esteruelas, A.V. Go´mez, A.M. Lo´pez, J. Modrego, E.
(c) G. Albertin, S. Antoniutti, E. Bordignon, J. Organomet.
Chem. 513 (1996) 147.
Onate, Organometallics 17 (1998) 5434;
˜
[7] R. Rabinowitz, J. Pellon, J. Org. Chem. 26 (1961) 4623.
[8] A.S. Hay, J. Org. Chem. 25 (1960) 637.
(b) C. Bianchini, N. Mantovani, A. Marchi, L. Marvelli, D. Masi,
M. Peruzzini, R. Rossi, A. Romerosa, Organometallics 18 (1999)
4501;
[9] G. Balacco, J. Chem. Inf. Comput. Sci. 34 (1994) 1235 (Upgrades
via the Internet at: http://qobrue.usc.es/jsgroup/swan/index.html).
[10] S.D. Ittel, A.D. English, C.A. Tolman, J.P. Jesson, Inorg. Chim.
Acta 33 (1979) 101.
(c) E. Bustelo, M. Jime´nez-Tenorio, M.C. Puerta, P. Valerga,
Organometallics 18 (1999) 4563;
(d) V. Cadierno, M.P. Gamasa, J. Gimeno, E. Pe´rez-Carreno, A.
˜
[11] W.J. Geary, Coord. Chem. Rev. 7 (1971) 81.
[12] G. Albertin, S. Antoniutti, M. Bettiol, E. Bordignon, F. Busatto,
Organometallics 16 (1997) 4959.
Ienco, Organometallics 17 (1998) 5216;
(e) C. Bohanna, B. Callejas, A.J. Edwards, M.A. Esteruelas, F.J.
Lahoz, L.A. Oro, N. Ruiz, C. Valero, Organometallics 17 (1998)
373.
[13] G. Albertin, S. Antoniutti, A. Bacchi, E. Bordignon, F. Miani, G.
Pelizzi, Inorg. Chem. 39 (2000) 3283.
[4] (a) S. Nakanishi, K. Goda, S. Uchiyama, Y. Otsuji, Bull. Chem.
Soc. Jpn. 65 (1992) 2560;
[14] (a) M.I. Bruce, Chem. Rev. 91 (1991) 197;
(b) M.I. Bruce, B.C. Hall, N.N. Zaitseva, B.W. Skelton, A.H.
White, J. Chem. Soc., Dalton. Trans. (1998) 1793.
[15] (a) J. Silvestre, R. Hoffmann, Helv. Chim. Acta 68 (1985) 1461;
(b) Y. Wakatsuki, N. Koga, H. Yamazaki, K. Morokuma, J. Am.
Chem. Soc. 116 (1994) 8105.
(b) V. Guillaume, P. Thominot, F. Coat, A. Mari, C. Lapinte, J.
Organomet. Chem. 565 (1998) 75.
[5] (a) C. Gauss, D. Veghini, O. Orama, H. Berke, J. Organomet.
Chem. 541 (1997) 19;
(b) H. Berke, V. Grossmann, G. Huttner, L. Zsolnai, Chem. Ber.
¨
[16] (a) M.D. Fryzuk, L. Huang, N.T. McManus, P. Paglia, S.J.
Rettig, G.S. White, Organometallics 11 (1992) 2979;
(b) J.R. Lumphrey, J.P. Selegue, J. Am. Chem. Soc. 114 (1992)
5518;
117 (1984) 3432.
[6] (a) G. Albertin, S. Antoniutti, E. Del Ministro, E. Bordignon, J.
Chem. Soc., Dalton. Trans. (1992) 3203;
(b) G. Albertin, S. Antoniutti, E. Bordignon, E. Del Ministro, S.
Iannelli, G. Pelizzi, J. Chem. Soc., Dalton. Trans. (1995) 1783;
(c) C. Bianchini, M. Peruzzini, A. Vacca, F. Zanobini, Organo-
metallics 10 (1991) 3697.