Unsymmetrically substituted butenynyl-iron(ii) complexes

Article abstract of DOI:10.1002/ejic.201000281

The preparation and characterisation of iron(II) complexes bearing unsymmetrically 1,4-disubstituted nη³-butenynyl ligands, cis-[Fe(C(C=CR)=C(H)R')(dmpe)₂][PF₆] (e.g. R = tBu, R' = Ph 2e; R = Ph, R' = tBu 2e') are reported. The complexes were obtained as a mixture by protonation and rearrangement of the bis(acetylido)iron(II) complex trans-Fe(CCPh)(CCtBu)(dmpe)₂. The complexes 2e and 2e' were separated by crystallisation and were both characterised, crystallographically. In addition, a number of complexes with symmetrically 1,4-disubstituted butenynyl ligands cis[Fe(C(C≡CR)=C(H)R)(dmpe)₂][PF₆] (R = p-C₆H₄-OMe 2a; pC₆H₄-Me 2b, C ₆H₃-3,5-(CF₃)₂ 2c; 1-adamantyl 2d) were synthesized by protonation and rearrangement of the corresponding bis(acetylido)iron(II) complexes.

Full text of DOI:10.1002/ejic.201000281

FULL PAPER
DOI: 10.1002/ejic.201000281
Unsymmetrically Substituted Butenynyl-Iron(II) Complexes
Leslie D. Field,*[a] Alison M. Magill,[a] Stuart R. Pike,[b] Anthony J. Turnbull,[b]
Scott J. Dalgarno,[c] Peter Turner,[b] and Anthony C. Willis[d]
Keywords: Iron / Phosphane ligands / Enynes / Rearrangement
The preparation and characterisation of iron(II) complexes
bearing unsymmetrically 1,4-disubstituted η3-butenynyl li-
gands, cis-[Fe(C(CϵCR)=C(H)RЈ)(dmpe)2][PF6] (e.g. R = tBu,
RЈ = Ph 2e; R = Ph, RЈ = tBu 2eЈ) are reported. The complexes
were obtained as a mixture by protonation and rearrange-
ment of the bis(acetylido)iron(II) complex trans-Fe(CCPh)-
(CCtBu)(dmpe)2. The complexes 2e and 2eЈ were separated
by crystallisation and were both characterised crystallo-
graphically. In addition, a number of complexes with sym-
metrically
1,4-disubstituted
butenynyl
ligands
cis-
[Fe(C(CϵCR)=C(H)R)(dmpe)2][PF6] (R = p-C6H4-OMe 2a; p-
C6H4-Me 2b. C6H3-3,5-(CF3)2 2c; 1-adamantyl 2d) were syn-
thesised by protonation and rearrangement of the corre-
sponding bis(acetylido)iron(II) complexes.
When used as a ligand, the but-1-en-3-yn-2-yl moiety can
coordinate in either an η3- or η1-mode, depending on the
co-ligands and metal centre, and the η1-coordination mode
of butenynyl ligands has been implicated as an important
intermediate preceding σ-bond metathesis with alkynes
during the metal mediated coupling of alkynes.[10] Buteny-
nyl complexes have been studied for a range of transition
metals including iron,[11–14] ruthenium,[2,5,10,15–18] os-
mium,[19] and platinum.[20] Various methods have been es-
tablished for the synthesis of butenynyl complexes, includ-
ing the addition of 1,4-disubstituted-1,3-diynes to metal hy-
dride complexes,[2,15,21] and the addition of terminal acetyl-
enes to either metal hydrides,[2,13,22,23] metal acet-
ylides,[1,17,24] or metal alkenyl complexes.[22] Other methods
of synthesis include the insertion of a coordinated acetylide
into a metal–vinylidene bond.[2,6,12,24,25]
Introduction
Transition-metal butenynyl complexes have been iden-
tified as key intermediates in the metal-catalysed head-to-
head couplings of alkynes leading to E/Z-1,4-disubstituted
1-buten-3-ynes[1–5] and E/Z-1,4-disubstituted butatrienes.[6]
Such compounds are of interest as building blocks in or-
ganic synthesis and as components of biologically active
molecules.[7] The majority of alkyne dimerisation studies
have focused on the homo-dimerisation of terminal alkynes;
there has been relatively little attention to the cross-cou-
pling of two different terminal alkynes.[8] The regioselective
and stereoselective catalytic synthesis of unsymmetrically
1,4-disubstituted butenynes from alkyne mixtures could be
utilised for the synthesis of more complex organic mole-
cules.[3,9] In a manner similar to the homodimerisation of
alkynes, metal-catalysed cross-coupling reactions could in-
volve the intermediacy of unsymmetrically 1,4-disubstituted
butenyne metal complexes
We have previously reported[12,18] the synthesis of sym-
metrical butenynyl-iron(II) and -ruthenium complexes,
[M(C(CϵCR)=C(H)R)(P4)]+ {M = Fe, P4 = 2 ϫ dmpe [1,2-
bis(dimethylphosphanyl)ethane]; M = Ru, P4 = 4 ϫ PMe3}
by the acidification of the corresponding bis(acetylido)-
iron(II) and -ruthenium(II) complexes. The bis(acetylido)
complexes were protonated at an acetylenic β-carbon to
form vinylideneacetylido complexes, which rearrange with
coupling of the acetylide and vinylidene ligands to form the
butenynyl complexes.
As an extension of this work, we report the synthesis and
characterisation of a number of iron(II) complexes bearing
both symmetrically and unsymmetrically substituted but-
enynyl ligands.
[a] School of Chemistry, University of New South Wales,
Sydney, Australia, 2052
Fax: +61-2-9385-8008
E-mail: L.Field@unsw.edu.au
[b] School of Chemistry, University of Sydney,
Sydney, Australia, 2006
Results and Discussion
Synthesis of Bis(acetylido) Complexes
[c] School of Engineering and Physical Sciences – Chemistry,
Heriot-Watt University,
Riccarton, Edinburgh EH14 4AS, U.K.
[d] Research School of Chemistry, Australian National University,
Canberra, Australia, 0200
The reaction of terminal acetylenes with cis-FeH2(dmpe)2
in MeOH is known[12] to yield bis(acetylido)iron(II) com-
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Unsymmetrically Substituted Butenynyl Iron(II) Complexes
plexes (Scheme 1). This method has been used to prepare a Table 1. Selected bond lengths [Å] and angles [°] for trans-
[Fe(CϵC–C6H4-4-OMe)]2(dmpe)2] (1a), trans-[Fe(CϵC–C6H4-4-
Me)2(dmpe)2] (1b), and trans-[Fe(CϵC–C6H3-3,5-(CF3)2)2(dmpe)2]
(1c).
number of iron(II) complexes 1a–d of the form trans-
Fe(CϵCR)2(dmpe)2 incorporating a variety of aryl- and
alkyl-substituted acetylenes.
1a
1b
1c
Fe(1)–C(1)
C(1)–C(2)
C(2)–C(3)
Fe(1)–P(1)
Fe(1)–P(2)
Fe(1)–C(1)–C(2)
C(1)–C(2)–C(3)
1.935(4)
1.197(5)
1.432(5)
2.204(1)
2.201(1)
178.6(4)
175.8(4)
1.937(2)
1.205 (3)
1.437(3)
2.206(1)
2.2082(9)
177.4(2)
177.3(2)
1.917(6)
1.219(8)
1.422(8)
2.207(2)
2.209(2)
178.2(5)
176.3(7)
known bis(acetylido)iron(II) complex trans-[Fe(CϵCPh)2-
(dmpe)2][26] shows that there is very little variation between
the structures, with the Fe–C, CϵC and C–C bonds being
essentially indistinguishable between complexes.
Scheme 1.
The bis(acetylido) complexes trans-[Fe(CϵCPh)-
(CϵCtBu)(dmpe)2] (1e), trans-[Fe(CϵCC6H4-4-CH3)-
(CϵCtBu)(dmpe)2] (1f) and trans-[Fe(CϵCPh)(CϵCSi-
(CH3)3)(dmpe)2] (1g) were synthesised as described pre-
viously from trans-Fe(CH3)Cl(dmpe)2 in a two-step se-
quence (Scheme 2).[27]
The NMR spectra of the resultant complexes are unre-
markable, with the trans configuration of the ligands con-
firmed by the presence of a single resonance in the 31P{1H}
NMR spectrum. Crystals suitable for X-ray structure deter-
mination were grown by recrystallisation from benzene (1a)
or toluene (1b, 1c) (Figure 1); selected bond lengths [Å] and
angles [°] are shown in Table 1.
Scheme 2.
Rearrangement to Butenynes
The addition of trifluoroacetic acid to 1a–d in THF, fol-
lowed by anion exchange and recrystallisation from ethanol
led to the isolation of the complexes cis-[Fe(C-
(CϵCR)=CHR)(dmpe)2][PF6] (2a–d) in good yield. The
synthesis of complexes bearing unsymmetrically substituted
butenynyl ligands was undertaken from the known[27] bis-
(acetylido) complexes trans-[Fe(CϵCPh)(CϵCtBu)(dmpe)2]
(1e), trans-[Fe(CϵCC6H4-4-CH3)(CϵCtBu)(dmpe)2] (1f)
Figure 1. Molecular projection of the complexes trans-Fe(CϵC–
C6H4-4-OMe)2(dmpe)2 (1a, left), trans-Fe(CϵC–C6H4-4-Me)2-
(dmpe)2 (1b, centre) and trans-Fe(CϵC–C6H3-3,5-(CF3)2)2(dmpe)2
(1c, right). Thermal ellipsoids are shown at the 50% probability
levels, selected hydrogen atoms have been removed for clarity.
Crystallographically, the complexes 1a–1c are highly and trans-[Fe(CϵCPh)(CϵCSi(CH3)3)(dmpe)2] (1g). Ad-
symmetrical, with the asymmetric unit consisting of one dition of either trifluoroacetic acid or ammonium hexafluo-
half of each molecule. The structural analysis confirms the rophosphate to solutions of 1e–g gave mixtures of the two
expected octahedral geometry with the two acetylide groups possible regioisomeric complexes 2e/eЈ–2g/gЈ (Scheme 3).
being disposed in a mutually trans fashion. The seven atoms
The relative yields of the two possible regioisomers of 2e/
forming the central core of the complexes (C–CϵC–Fe– eЈ–2g/gЈ were determined by NMR spectroscopy and de-
CϵC–C) are essentially colinear with the acetylide groups pended on the nature of the acetylide ligands, and in the
orthogonal to the plane containing the iron and four phos- case of 2g/gЈ, on the temperature at which the reaction was
phorus atoms. Comparison of the bond lengths with the performed (Table 2).
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L. D. Field et al.
FULL PAPER
at the phenylacetylido ligand resulted in retention of the
trimethylsilyl group and the formation of cis-[Fe(C-
(CϵCSi(CH3)3)=C(H)C6H5)(dmpe)2][PF6] (2g) (Scheme 4).
Scheme 4.
The lability of carbon–silicon bonds is well established,
and, although the cleavage of trimethylsilyl groups from tri-
methylsilylacetylide complexes to form the parent acetylido
complexes has been reported to be particularly difficult in
some cases,[29] the use of ammonium hexafluorophosphate
appears to allow the isolation of vinylidene complexes bear-
ing the C=CH2 moiety in good yields.[30] The desilylation
of 2gЈ occurs early in the reaction to yield the deprotected
vinylidene complex, which then undergoes ligand coupling
to give the final product.
As has previously been noted for iron butenyne com-
plexes of this type,[12,14] the butenynyliron(II) complexes
generally exhibit four sharp eight-line multiplets in the
31P{1H} NMR spectrum ranging from δ = 49 ppm to
65 ppm, with the observed splittings due to either cis (–19
to –50 Hz) or trans (150 Hz to 170 Hz) phosphorus–phos-
phorus coupling. Second-order coupling effects arise in the
31P{1H} NMR spectrum of 2e and 2eЈ due to the close
proximity of the chemical shifts. Assignment of the 31P{1H}
NMR spectra of these complexes was achieved by crude
extraction of coupling constants from each species by the
use of 31P-COSY NMR spectroscopy. The coupling con-
stants and chemical shifts were then refined by the use of an
iterative 31P{1H}-NMR simulation program. The simulated
Scheme 3. Preparation of butenynyl-iron(II) complexes 2a–g. Rea-
gents: i) CF3COOH, KPF6 (2a–2d, 2f/fЈ). ii) NH4PF6 (2e/eЈ, 2g/gЈ).
Table 2. Yields of non-symmetric butenynyl-iron(II) complexes
from bis(acetylido)iron(II) complexes.
Acetylide
complex
Butenynyl
complex
Relative yield
[%][a]
Temp. [°C]
1e
1e
1f
1g
1g
2e/2eЈ
2e/2eЈ
2f/2fЈ
2g/2gЈ
2g/2gЈ
45:55
45:55
24
65
24
10
65
Ͼ98/Ͻ2[b]
10:90
23:77
[a] Average of two preparations. [b] At the limit of detection.
Attempts to prepare complexes incorporating a trimeth- spectra for each complex were obtained separately (see
ylsilyl group met with limited success. The first step in but- parts a and b in Figure 2), combined (Figure 2, c), and
enyne formation is generally taken to be protonation at one compared with the experimental data (Figure 2, d). The ap-
of the acetylide β-carbon atoms to yield a mixed vinylidene/ pearance of unique phosphorus resonances is entirely con-
acetylide complex,[12,28] and this is followed by coupling of sistent with the structures revealed by the X-ray crystal
the two carbon-based ligands. Protonation of the β-carbon structure analysis (vide infra).
of the trimethylsilylacetylido ligand in trans-[Fe-
The reaction of trans-[Fe(CϵCC6H5)(CϵCtBu)(dmpe)2]
(CϵCC6H5)(CϵCSi(CH3)3)(dmpe)2] (1h) resulted in the (1e) with NH4PF6 at –10 °C occurred at such a rate that it
1
cleavage of the trimethylsilyl group to give cis-[Fe(C- could be followed by 31P{1H} and H NMR spectroscopy.
(CϵCC6H5)=CH2)(dmpe)2][PF6] (2gЈ), while protonation During the course of the reaction, two intermediates were
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Unsymmetrically Substituted Butenynyl Iron(II) Complexes
Figure 2. (a) Simulated 31P{1H} NMR spectrum of 2f. (b) Simu-
lated spectrum of 2fЈ. (c) Combined simulated spectra. (d) Experi-
mental spectrum [162 MHz, (CD3)2CO].
Scheme 5.
observed in the 31P{1H} NMR spectrum, with broad singlet
resonances appearing at δ = 56.8 ppm and 56.7 ppm (in the
ratio 45:55 respectively). Evidence allowing assignment of
these intermediates as vinylidene species was provided by
1
the H NMR spectrum, with the appearance of resonances
corresponding to vinyl protons at δ = 4.91 and 5.79 ppm.
Both (acetylido)vinylidene-iron(II) complexes then slowly
rearranged at room temperature to the two butenynyl-
iron(II) complexes 2e and 2eЈ. The proportions of the (ace-
tylido)vinylidene-iron(II) intermediates mirrored the final
distribution of butenynyl regioisomers. Clearly then, 1e can
be protonated at the β-carbon of both acetylide ligands,
with little preference for the site of protonation in this case.
In the case of 2f/fЈ, there is a clear preference for proton-
ation at the β-carbon of the 4-methoxyphenylacetylide li-
gand. As there are essentially no steric differences between
1e and 1f, this stark difference in reactivity is likely the re-
sult of the high electron-donating ability of the methoxy
substituent on the aryl ring in 1f increasing the suscep-
tibility of the acetylenic β-carbon to electrophilic attack
(Scheme 5) and stabilising the resulting cation.
Figure 3. Molecular projection of the complex cations of 2a (top
left), 2b (top right), 2e (bottom left) and 2eЈ (bottom right). Only
one component of each of the disordered sites of 2b and 2e is
shown.
Suitable crystals of 2a, 2b, 2e and 2eЈ were subjected to
X-ray crystallographic analysis. ORTEP[31] diagrams of the
crystal structures are shown in Figure 3, while selected
bond lengths and bond angles are shown in Table 3.
Table 3. Selected bond lengths [Å] and angles [°] for complexes 2a,
2b, 2e and 2eЈ.
2a
2b
2e
2eЈ
Fe(1)–C(3)
Fe(1)–C(2)
Fe(1)–C(1)
C(3)–C(4)
C(2)–C(3)
C(1)–C(2)
C(1)–Fe–C(3)
C(2)–C(3)–C(4) 133.3(1)
C(1)–C(2)–C(3) 148.8(2)
C(2)–C(1)–R
C(1)–Fe–P(2)
P(3)–Fe–C(3)
2.018(2)
2.089(1)
2.269(2)
1.347(2)
1.383(2)
1.253(2)
72.35(6)
2.005(3)
2.081(3)
2.300(4)
1.338(5)
1.388(5)
1.237(5)
72.0(1)
133.3(1)
148.7(2)
150.2(4)
93.7(1)
2.017(7)
2.098(7)
2.344(8)
1.342(10) 1.334(9)
1.397(10) 1.381(8)
1.212(10) 1.234(8)
70.7(3)
132.0(7)
152.9(8)
143.4(8)
97.4(2)
94.5(2)
2.026(7)
2.084(6)
2.260(7)
The Me2PCH2CH2PMe2 ligands in 2b show considerable
disorder, which required the use of two sites for each of
these atoms. The iron atom and the atoms of the C18H15
ligand have full occupancy. The major isomer has P1 linked
to P2 and P3 to P4; whereas the minor isomer has P91 (near
P1) linked to P92 (near P4) and P93 (near P3) linked to P94
(near P2). As the various sites frequently overlap, restraints
were imposed on P–C and C–C bonded distances and on
C–P–C and P–C–C angles for the minor isomer. Isotropic
displacement parameters were used for the minor sites. The
71.9(3)
134.0(6)
149.6(7)
151.4(7)
95.1(2)
90.6(2)
146.3(2)
92.12(4)
97.56(5)
93.0(1)
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L. D. Field et al.
FULL PAPER
Phenylacetylene, (trimethylsilyl)acetylene, 4-ethynyltoluene and
(tert-butyl)acetylene were obtained from Aldrich and degassed
prior to use. 1,2-Bis(dimethylphosphanyl)ethane (dmpe) was ob-
relative occupancies of the two isomers were refined. Simi-
larly, 2e is disordered, with two sites associated with two
ligand orientations resolved for atom C18 and C20, with
occupancies of the components refining to 0.4 and 0.6. The
model C17 and C19 ellipsoids are large; however the atoms
could not be successfully modelled with multiple sites.
The iron centre exhibits a distorted octahedral coordina-
tion sphere, in which the butenynyl fragment binds in a tri-
hapto fashion to the metal centre. A similar arrangement
has been reported previously for the related complex cis-
[FeC(CϵCC6H5)=C(H)C6H5(dmpe)2]BPh4.[14] The bond
lengths of the complexes show subtle changes in the binding
of the butenynyl fragment between the four butenynyl-
iron(II) complexes; notably the Fe(1)–C1 bond length for
2e [2.344(8) Å] is significantly longer than for 2a and 2eЈ
[2.269(2) and 2.260(7) Å, respectively]. The analogous bond
lengths in 2c and cis-[FeC(CϵCC6H5)=C(H)C6H5(dmpe)2]-
PF6 [2.300(4) and 2.309(8) Å, respectively] are midway be-
tween these two extremes. Additionally, the C(1)–C(2) bond
is shortened in 2e [1.212(10) Å] compared to 2a, 2b and 2eЈ
[1.253(2), 1.237(5) and 1.234(8) Å, respectively]. Note-
worthy changes in bond angles include an increase in the
C(1)–C(2)–C(3) angle of 2e [152.9(8)°] relative to the other
complexes [e.g., 149.6(7)° for 2eЈ] and reductions in the
C(1)–Fe–C(3) [70.7(3)° (2e) vs. 71.9(3)° (2eЈ)] and C(2)–
C(1)–R angles [143.4(8)° (2e) vs. 151.4(7)° (2eЈ)]. The crys-
tallographic results suggest that the alkyne group in cis-
[FeC(CϵCtBu)=C(H)C6H5(dmpe)2]PF6 (2e) is less strongly
bound to the metal centre than in the other complexes
studied. The interaction of the sterically demanding tert-
butyl substituent with the methyl groups of the cis phos-
phane ligand almost certainly accounts for this observation.
tained from Strem and used as supplied. (4-Methoxyphenyl)acetyl-
[34]
ene,[32] (1-adamantyl)acetylene,[33] and cis-FeH2(dmpe)2
were
prepared according to literature methods. The unsymmetrical
bis(acetylido) complexes trans-[Fe(CϵCtBu)(CϵCC6H5)(dmpe)2]
(1e), trans-[Fe(CϵCtBu)(CϵCC6H4OCH3)(dmpe)2] (1f) and trans-
[Fe(CϵCPh)(CϵCSi(CH3)3)(dmpe)2] (1g) were prepared as de-
scribed previously.[27]
NMR spectra were recorded on a Bruker AMX or DRX 400 spec-
trometer at 300 K unless otherwise stated, fitted either with a
broadband or multinuclear probe tuned to 100.61, 400.13 and
162.00 MHz for 13C, 1H and 31P nuclei, respectively. Chemical
shifts (δ) are reported in ppm. 13C and 1H NMR spectra were refer-
enced to residual solvent resonances whilst 31P NMR spectra were
referenced to external, neat, trimethyl phosphite taken to be
140.85 ppm at 300 K. Infrared spectra were recorded on a Perkin–
Elmer 1600 Series FTIR. Electrospray mass spectra were recorded
on a Finnigan LCQ mass spectrometer by direct infusion of a
methanol or THF solution of the complexes into the source. Chem-
ical ionisation (CI) mass spectra of organic compounds were re-
corded on a Hewlett–Packard 5989 A mass spectrometer “engine”
using CH4 as the ionization gas. Liquid secondary ion mass spectra
(LSIMS) were recorded at the Central Science Laboratory, Univer-
sity of Tasmania, on a Kratos Concept ISQ mass spectrometer
using a m-nitrobenzyl alcohol matrix.
Preparation of Bis(acetylido)iron(II) Complexes:[35] An excess of the
appropriate acetylene was added to a solution of FeH2(dmpe)2 in
methanol (3 mL). The mixture was stirred at room temperature for
17 h, before the resultant precipitate was isolated by filtration,
washed with methanol and dried.
trans-Fe(CϵCC6H4OCH3)2(dmpe)2 (1a): Prepared from (4-meth-
oxyphenyl)acetylene (0.28 g, 2.1 mmol) and FeH2(dmpe)2 (0.070 g,
0.20 mmol). The product was recrystallised from benzene to afford
a yellow crystalline solid of trans-Fe(CϵCC6H4OCH3)2(dmpe)2
(1a); yield 0.076 g (63%). νCϵC (Nujol): 2043 cm–1 (w). 31P{1H}
Conclusions
1
NMR (C6D6): δ = 69.1 (s) ppm. H{31P} NMR (C6D6): δ = 1.66
(br. s, 24 H, CH3), 1.77 (br. s, 8 H, CH2), 3.57 (s, 6 H, OCH3), 7.02
(AAЈ of AAЈXXЈ, 4 H, ArH), 7.49 (XXЈ of AAЈXXЈ, 4 H, ArH)
ppm. 13C{1H} NMR (C6D6): δ = 16.6 (CH3), 31.2 (CH2), 55.2
(OCH3), 114.5 (ArCH), 114.7 (CϵCC), 125.0 (FeCϵC), 131.5
(ArCH), 133.4 (FeCϵC), 156.7 (COCH3) ppm. MS (C.I.): m/z (%)
= 619 (100) [M + 1], 487 (53). C30H46FeO2P4 (618.398): calcd. C
58.26, H 7.50; found C 58.36, H 7.50.
Butenynyl-iron(II) complexes of the general formula cis-
[FeC(CϵCR)=C(H)RЈ(dmpe)2]PF6 (R = RЈ, 2a–d; R ϶ RЈ,
2e/eЈ–g/gЈ) have been prepared by the reaction of bis(acetyl-
ido)iron(II) complexes under mildly acidic conditions.
The use of unsymmetrically substituted bis(acetylido)-
iron(II) complexes results in a mixture of products in which
both possible regioisomeric butenynyl products are formed.
In the rearrangement of arylacetylides, the major product
is that derived from the more stable vinylidene intermediate.
X-ray structure analysis of a pair of regioisomeric buten-
ynyl-iron(II) complexes show that the ligand binds in an η3-
manner, with some significant differences in the bond
lengths and angles.
trans-Fe(CϵCC6H4CH3)2(dmpe)2 (1b): Prepared from 4-ethynyltol-
uene (0.20 g, 1.7 mmol) and FeH2(dmpe)2 (0.030 g, 0.084 mmol).
trans-Fe(CϵCC6H4CH3)2(dmpe)2 (1b) was obtained as a yellow
crystalline solid that was recrystallised from toluene; yield 0.037 g
(76%). νCϵC (Nujol): 2047 cm–1. 31P{1H} NMR (C6D6): δ = 68.9
1
(s) ppm. H{31P} NMR (C6D6): δ = 1.65 (s, 24 H, CH3), 1.75 (br.
s, 8 H, CH2), 2.39 (s, 6 H, ArCH3), 7.23 (AAЈ of AAЈXXЈ, 4 H,
ArH), 7.51 (XXЈ of AAЈXXЈ, 4 H, ArCH) ppm. 13C{1H,31P} NMR
(C6D6): δ = 16.9 (CH3), 21.9 (ArCH3), 31.6 (CH2), 129.5 (CϵCC),
115.9 (FeCϵC), 129.7 (ArCH), 130.9 (ArCH), 132.5 (CCH3), 133.0
=
586 (100) [MH3+].
Experimental Section
(FeCϵC) ppm. MS (C.I.): m/z (%)
C30H46FeP4 (586.398): calcd. C 61.44, H 7.91; found C 61.18, H
7.95.
General: All syntheses and manipulations involving air-sensitive
compounds were performed under an inert atmosphere in a nitro-
gen-filled box or by using standard Schlenk techniques. All solvents
used with air-sensitive compounds were either distilled under nitro-
gen or degassed using three to five freeze-pump-thaw cycles.
trans-Fe[CϵCC6H3-3,5-(CF3)2]2(dmpe)2 (1c): Prepared from 3,5-
bis(trifluoromethyl)phenylacetylene (0.18 g, 0.76 mmol) and
FeH2(dmpe)2 (0.060 g, 0.17 mmol). The product was recrystallised
2410
www.eurjic.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2010, 2406–2414

Unsymmetrically Substituted Butenynyl Iron(II) Complexes
from benzene to afford a yellow crystalline solid of trans-
Fe[CϵCC6H3-3,5-(CF3)2]2(dmpe)2 (1c); yield 0.117 g (84%). νCϵC
H, 2ϫ PCH3), 1.38 (s, 3 H, PCH3), 1.42 (s, 3 H, PCH3), 1.57 (s, 3
H, PCH3), 1.57–1.70 (m, 8 H, PCH2), 1.92 (s, 3 H, PCH3), 2.14 (s,
(Nujol): 2030 cm–1. 31P{1H} NMR ([D8]THF): δ = 67.0 (s) ppm. 3 H, ArCH3), 2.23 (s, 3 H, ArCH3), 7.02 (ArH, 2 H, AAЈ of
1H{31P} NMR ([D8]THF): δ = 1.60 (br. s, 24 H, CH3), 1.88 (br. s, AAЈXXЈ), 7.17 (ArH, 2 H, AЈЈAЈЈЈ of AЈЈAЈЈЈXЈЈXЈЈЈ), 7.22 (ArH,
8 H, CH2), 7.38 (s, 2 H, ArH), 7.41 (s, 4 H, ArH) ppm. 13C{31P,1H} 2 H, XЈЈXЈЈЈ of AЈЈAЈЈЈXЈЈXЈЈЈ), 7.25 (s, 1 H, C=CH), 7.54 (ArH,
NMR ([D8]THF): δ = 16.1 (PCH3), 31.2 (PCH2), 114.8 (FeCϵC), 2 H, XXЈ of AAЈXXЈ) ppm. 13C{1H,31P} NMR ([D6]acetone): δ =
115.3 (ArCH), 124.8 (q, 1JCF = 272 Hz, CF3), 129.9 (ArCH), 132.0
8.5 (PCH3), 9.1 (PCH3), 15.2 (PCH3), 16.8 (PCH3), 18.8 (PCH3),
(q, 2JCF = 32 Hz, CCF3), 132.9 (ArC), 153.4 (FeC) ppm. MS (C.I.): 19.0 (2ϫ PCH3), 19.9 (2ϫ ArCH3), 20.3 (PCH3), 26.3 (PCH2),
m/z (%) = 831 (100) [M + 1], 537 (45). C32H38F12FeP4 (830.354):
calcd. C 46.29, H 4.61; found C 46.57, H 4.82.
27.6 (PCH2), 31.7 (PCH2), 32.6 (PCH2), 49.4 (PhCϵC), 106.0
(PhCϵC), 125.4 (ArCH), 126.1 (CCϵC), 129.0 (ArCH), 129.4
(ArCH), 129.7 (ArCH), 132.1 (=CH), 135.6 (2ϫ ArC), 138.4
(ArC), 152.5 (FeC) ppm. MS (E.S.): m/z (%) = 587 (100) [M+], 471
(37), 356 (19). C30H47F6FeP5 (732.376): calcd. C 49.20, H 6.47;
found C 49.17, H 6.42.
trans-Fe(CϵCC10H15)2(dmpe)2 (1d): Prepared from (1-adamantyl)-
acetylene (0.270 g, 1.67 mmol) and FeH2(dmpe)2 (0.060 g,
0.167 mmol). The product was recrystallised from toluene to afford
a yellow crystalline solid of trans-Fe(CϵCC10H15)2(dmpe)2 (1d);
yield 0.088 g (78%). νCϵC (Nujol): 2067 cm–1. 31P{1H} NMR
cis-[Fe{C(CϵC–C6H4-3,5-(CF3)2)=C(H)C6H3-3,5-(CF3)2}(dmpe)2]-
PF6 (2c): Prepared as described for 2a from trans-Fe(CϵCC6H3-
3,5-(CF3)2)2(dmpe)2 (1c) (200 mg, 0.241 mmol). cis-[Fe{C(ϵCC6H3-
(CF3)2)C=C(H)C6H3(CF3)2}(dmpe)2]PF6 (2c) was obtained as a
red crystalline solid; yield 0.206 g (84%). 31P{1H} NMR ([D6]ace-
1
(C6D6): δ = 68.3 (s) ppm. H{31P} NMR ([D8]THF): δ = 1.58 (br.
s, 24 H, PCH3), 1.70 (br. s, 12 H, CH2), 1.75 (br. s, 8 H, PCH2),
1.82 (br. s, 12 H, CH2), 1.89 (br. s, 6 H, CH) ppm. 13C{1H,31P}
NMR ([D8]THF): δ = 17.7 (PCH3), 31.5 (CH), 32.9 (PCH2), 34.1
(C-CϵC), 39.3 (CH2), 48.4 (CH2), 112.4 (Fe–CϵC), 123.0 (Fe–
CϵC) ppm. MS (CI): m/z (%) = 675 (100) [M + 1], 515 (21).
C36H62FeP4·C7H8 (766.72): calcd. C 67.36, H 9.20; found C 67.01,
H 9.44.
2
2
2
tone): δ = 48.9 (ddd, JP1P2 = 41, JP1P3 = 29, JP1P4 = 29 Hz, 1 P,
2
2
P1), 55.7 (ddd, JP2P3 = 35, JP2P4 = 169 Hz, 1 P, P2), 60.0 (ddd,
2JP3P4 = 46 Hz, 1 P, P3), 63.9 (ddd, 1 P, P4) ppm. H{31P} NMR
1
([D6]acetone): δ = 0.76 (s, 3 H, PCH3), 0.84 (s, 3 H, PCH3), 1.40
(s, 3 H, PCH3), 1.44 (s, 3 H, PCH3), 1.57 (s, 3 H, PCH3), 1.80–2.40
(m, 8 H, PCH2), 1.83 (s, 3 H, PCH3), 1.96 (s, 3 H, PCH3), 2.18 (s,
3 H, PCH3), 7.87 (s, 2 H, ArH), 8.07 (s, 2 H, ArH), 8.14 (s, 1 H,
C=CH), 8.48 (s, 2 H, ArH) ppm. 13C{1H,31P} NMR ([D8]THF): δ
= 9.7 (PCH3), 11.2 (PCH3), 15.7 (PCH3), 17.8 (PCH3), 19.9
(PCH3), 20.0 (PCH3), 20.3 (PCH3), 23.1 (PCH3), 27.0 (PCH2), 28.2
(PCH2), 33.1 (PCH2), 33.2 (PCH2), 61.0 (ArCϵC), 115.4
cis-[Fe{C(CϵC–C6H4-4-OMe)=C(H)C6H4-4-OMe}(dmpe)2]PF6 (2a):
Trifluoroacetic acid (approx. 8 drops, 200 µL) was added to a THF
solution of trans-Fe(CϵCC6H4-4-OMe)2(dmpe)2 (1a) (0.200 g,
0.324 mmol) in THF (20 mL). A colour change from yellow to red
via green and orange occurred over 2 h. Potassium hexafluorophos-
phate (0.11 g, 0.60 mmol) was added to precipitate the product,
which was recrystallised from acetone/pentane and dried in vacuo.
cis-[Fe{C(CϵC–C6H4-4-OMe)=C(H)C6H4-4-OMe}(dmpe)2]PF6 (2a)
was obtained as a red crystalline solid, suitable for X-ray crystal-
lography; yield 0.205 g (83%). 31P{1H} NMR ([D6]acetone): δ =
1
(ArCϵC), 119.7 (ArCH), 122.1 (ArCH), 123.8 (q, JCF = 272 Hz,
1
CF3), 124.4 (q, JCF = 272 Hz, CF3), 126.0 (ArCH), 128.9 (ArC),
130.4 (ArCH), 130.9 (=CH), 132.4 (q, 2JCF = 32 Hz, C-CF3), 132.8
(q, 2JCF = 32 Hz, C-CF3), 140.6 (ArC), 162.1 (FeC) ppm. MS (ES):
m/z (%) = 831 (100) [M+], 682 (12); m.p. 277 °C (dec). The BPh4
2
2
2
50.9 (ddd, JP1P2 = 40, JP1P3 = 28, JP1P4 = 21 Hz, 1 P, P1), 56.7
2
2
2
(ddd, JP2P3 = 179, JP2P4 = 47 Hz, 1 P, P2), 63.4 (ddd, JP3P4
=
salt of this complex was synthesised as follows: A mixture of cis-
48.5 Hz, 1 P, P3), 63.5 (ddd, 1 P, P4) ppm. 1H{31P} NMR ([D6]-
acetone): δ = 0.80 (s, 3 H, PCH3), 0.92 (s, 3 H, PCH3), 1.40 (br. s,
6 H, 2ϫ PCH3), 1.52 (s, 3 H, PCH3), 1.55 (s, 3 H, PCH3), 1.65–
1.85 (m, 4 H, PCH2), 1.71 (s, 3 H, PCH3), 1.98 (s, 3 H, PCH3),
2.10–2.25 (m, 4 H, PCH2), 3.79 (s, 3 H, OCH3), 3.87 (s, 3 H,
OCH3), 6.92 (AAЈ of AAЈXXЈ, 2 H, ArH), 7.04 (AAЈЈ of
AAЈЈXXЈЈЈ, 2 H, ArH), 7.40 (ArH, 2 H, XXЈ of AAЈXXЈ), 7.73
(XXЈЈ of AAЈЈXXЈЈЈ, 2 H, ArH), 7.35 (s, 1 H, =CH) ppm.
13C{1H,31P} NMR ([D6]acetone): δ = 8.5 (PCH3), 9.1 (PCH3), 15.2
(PCH3), 16.8 (PCH3), 18.5 (PCH3), 19.1 (2ϫ PCH3), 20.0 (PCH3),
26.3 (PCH2), 27.6 (PCH2), 31.7 (PCH2), 32.6 (PCH2), 48.0
(PhCϵC), 54.3 (OCH3), 54.6 (OCH3), 104.6 (CϵCPh), 113.7
(ArCH), 114.6 (ArCH), 120.1 (ArC), 126.4 (ArCH), 131.1 (ArCH),
131.5 (ArC), 131.7 (=CH), 150.1 (FeC), 159.5 (COCH3), 160.7
(COCH3) ppm. MS (ES): m/z (%) = 619 (29) [M+], 489 (34); m.p.
[14]
[FeH(H2)(dmpe)2]BPh4
(0.1069 g, 0.158 mmol) and 1,4-bis[3,5-
bis(trifluoromethyl)phenyl]butadiyne[36] (0.0915 g, 0.193 mmol)
was suspended in acetone (2.5 mL), sonicated for 40 min, and the
solvent removed in vacuo. The residual solid was washed with pen-
tane (3ϫ 10 mL) and recrystallised from acetone/diethyl ether;
yield 0.0893 g (49%). The NMR spectra were identical those pre-
viously described. C56H59BF12FeP4 (1150.572): calcd. C 58.46, H
5.17; found C 58.80, H 5.68.
cis-[Fe{C(CϵC–C10H15)=C(H)C10H15}(dmpe)2]PF6 (2d): Prepared
as described for 2a from trans-Fe(CϵCC10H15)2(dmpe)2 (1d). cis-
[Fe{C(ϵCC10H15)C=C(H)C10H15}(dmpe)2]PF6 (2d) was obtained
as a red crystalline solid; yield 0.022 g (86%). 31P{1H} NMR ([D7]-
2
2
2
DMF): δ = 51.4 (ddd, JP1P2 = 39, JP1P3 = 29, JP1P4 = 20 Hz, 1
P, P1), 53.4 (ddd, 2JP2P3 = 161, JP2P4 = 37 Hz, 1 P, P2), 60.8 (ddd,
2
2JP3P4 = 49 Hz, 1 P, P3), 63.3 (ddd, 1 P, P4) ppm. H NMR ([D6]-
1
257 °C (dec). C30H47F6FeO2P5·(CH3)2CO (822.454): calcd.
C
2
2
acetone): δ = 0.67 (d, JPH = 9.0 Hz, 3 H, PCH3), 0.81 (d, JPH
=
48.19, H 6.50; found C 48.11, H 6.55.
2
8.8 Hz, 3 H, PCH3), 1.25 (d, JPH = 8.1 Hz, 3 H, PCH3), 1.36 (d,
2
cis-[Fe{C(CϵC–C6H4-4-Me)=C(H)C6H4-4-Me}(dmpe)2]PF6 (2b):
Prepared as described for 2a from trans-Fe(CϵCC6H4CH3)2-
(dmpe)2 (1b). cis-[Fe{C(ϵCC6H4CH3)C=C(H)C6H4CH3}(dmpe)2]-
PF6 (2b) was obtained as a red crystalline solid after recrystalli-
sation from ethanol. These crystals were suitable for X-ray crystal-
lography; yield 0.227 g (91%). 31P{1H} NMR ([D6]acetone): δ =
2JPH = 7.7 Hz, 3 H, PCH3), 1.44 (d, JPH = 7.7 Hz, 3 H, PCH3),
1.6–1.7 (m, 4 H, PCH2), 1.70 (d, 2JPH = 7.1 Hz, 3 H, PCH3), 1.72–
2
1.97 (br. m, 30 H, adamantyl-H), 1.83 (d, JPH = 9.0 Hz, 3 H,
PCH3), 2.0–2.1 (m, 4 H, PCH2), 2.33 (d, JPH = 7.7 Hz, 3 H,
2
PCH3), 6.11 (apparent p, splitting = 2.0 Hz, 1 H, =CH) ppm.
1
13C{1H} NMR ([D6]acetone): δ = 8.43 (d, JPC = 22.6 Hz, PCH3),
2
2
2
1
1
49.8 (ddd, JP1P2 = 40, JP1P3 = 22, JP1P4 = 29 Hz, 1 P, P1), 56.6 9.53 (d, JPC = 20.1 Hz, PCH3), 15.2 (d, JPC = 23.5 Hz, PCH3),
2
2
2
1
(ddd, JP2P3 = 49, JP2P4 = 182 Hz, 1 P, P2), 63.0 (ddd, JP3P4
49 Hz, 1 P, P3), 63.4 (ddd, 1 P, P4) ppm. 1H{31P} NMR ([D6]- 21.0 (d, JPC = 20.1 Hz, PCH3), 26.6 (dd, JPC = 28.0, JPC
acetone): δ = 0.65 (s, 3 H, PCH3), 0.77 (s, 3 H, PCH3), 1.24 (s, 6 12.0 Hz, PCH2), 28.6 (dd, 1JPC = 26.4, 2JPC = 10.7 Hz, PCH2), 28.7
=
18.8 (m, PCH3), 19.2 (m, PCH3), 19.6 (d, JPC = 19.3 Hz, PCH3),
1
1
2
=
Eur. J. Inorg. Chem. 2010, 2406–2414
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
2411

L. D. Field et al.
FULL PAPER
2
2
(AdCH), 29.0 (AdCH), 29.1 (PCH3) 32.5–33.4 (m, 2ϫ PCH2), 35.2 2JP1P4 = 21.0 Hz, 1 P, P1), 54.23 (ddd, JP2P3 = 159.5, JP2P4
=
(AdC), 36.0 (AdCH2), 36.8 (AdCH2), 38.6 (AdC), 43.1 (AdCH2), 35.4 Hz, 1 P, P2), 61.47 (ddd, 2JP3P4 = 49.2 Hz, 1 P, P3), 63.33 (ddd,
1
44.4 (AdCH2), 47.0 (AdCϵC), 114.3 (m, AdCϵC), 143.3 (br. m,
FeC), 143.4 (C=CH) ppm. MS (ES): m/z (%) = 675 (22) [M+], 515
(32); m.p. 300 °C (dec.). HRMS (LSIMS): 675.3225. Req. for
C36H63P456Fe: 675.3230.
1 P, P4) ppm. H{31P} NMR ([D8]THF): δ = 0.53 (s, 3 H, PCH3),
0.65 (s, 3 H, PCH3), 1.21 (s, 3 H, PCH3), 1.32 (s, 3 H, PCH3), 1.42
(s, 3 H, PCH3), 1.46 [s, 9 H, C(CH3)3], 1.60–1.70 (m, 4 H, PCH2),
1.69 (s, 3 H, PCH3), 1.85–2.10 (m, 4 H, PCH2), 1.86 (s, 3 H, PCH3),
2.20 (s, 3 H, PCH3), 3.73 (s, 3 H, OCH3), 6.85 (AAЈ of AAЈXXЈ,
2 H, ArH), 7.65 (XXЈ of AAЈXXЈ, 2 H, ArH), 7.07 (s, 1 H, C=CH)
ppm. 13C{1H,31P} NMR ([D8]THF): δ = 9.6 (PCH3), 10.5 (PCH3),
16.2 (PCH3), 19.1 (PCH3), 20.0 (PCH3), 20.2 (PCH3), 21.2 (PCH3),
27.4 (PCH2), 28.4 (PCH3), 29.3 (PCH2), 33.0 [C(CH3)3], 33.6
(PCH2), 33.9 (PCH2), 48.2 [C(CH3)3], 55.4 (OCH3), 114.5 (ArCH),
119.3 [(CH3)3CCϵC], 127.2 (ArCH), 131.8 (ArC), 132.0 (C=CH),
144.4 [(CH3)3CCϵC], 151.2 (FeC), 159.4 (ArCO) ppm.
cis-[Fe{C(CϵCtBu)=C(H)Ph}(dmpe)2]PF6 (2e) and cis-[Fe{C(Cϵ
CPh)=C(H)tBu}(dmpe)2]PF6 (2eЈ): Ammonium hexafluorophos-
phate (0.030 g, 0.186 mmol) was added to a THF solution of trans-
[Fe(CϵCtBu)(CϵCC6H5)(dmpe)2] (1e) (100 mg, 186 µmol). The
colour of the solution immediately changed from yellow to green
then slowly over 2 h at 65 °C to dark brown. The solvent was re-
moved and the residue found to contain a 55:45 mixture of 3a and
3b, which were recrystallised from THF (0.5 mL) as red cubes and
yellow needles, (112 mg, 88%). MS (E.S.): m/z (%) = 539 (8) [M +
1]+, 389 (100) [(M + 1) – dmpe]+, 237 [(M + 1) – 2 dmpe]+.
C26H47F6FeP5 (684.336): calcd. C 45.60, H 6.93; found C 45.9, H
7.2.
cis-[Fe(η3-C{CϵCSi(CH3)3}=C(H)C6H5)(dmpe)2][PF6] (2 g) and
cis-[Fe(η3-C(CϵCC6H5)=CH2)(dmpe)2][PF6] (2gЈ): Ammonium
hexafluorophosphate (6.0 mg, 0.037 mmol) was added to an ace-
tone solution (0.5 mL) of trans-[Fe(CϵCPh)(CϵCSi(CH3)3)-
(dmpe)2] (1g) (19.5 mg, 0.035 mmol). The solution was heated at
65 °C for 1.5 h during which time it changed colour from green to
orange to red. The solvent was removed and the brown residue
recrystallised from ethanol to give a red/brown crystalline solid
containing 23% cis-[Fe(η3-C{CϵCSi(CH3)3}=C(H)C6H5)(dmpe)2]-
[PF6] (2g) and 77% cis-[Fe(η3-C(CϵCC6H5)=CH2)(dmpe)2][PF6]
(2gЈ); yield 24 mg (92%).
cis-[Fe{η3-C(CϵCtBu)=C(H)Ph}(dmpe)2][PF6] (2e): 31P{1H} NMR
([D8]THF): δ = 49.89 (ddd, 2JP1P2 = 42, 2JP1P3 = 30, 2JP1P4 = 20 Hz,
2
2
1 P, P1), 54.23 (ddd, JP2P3 = 158, JP2P4 = 36 Hz, 1 P, P2), 61.68
2
1
(ddd, JP3P4 = 50 Hz, 1 P, P3), 63.26 (ddd, 1 P, P4) ppm. H{31P}
NMR ([D8]THF): δ = 0.59 (s, 3 H, PCH3), 0.74 (s, 3 H, PCH3),
1.26 (s, 3 H, PCH3), 1.36 (s, 3 H, PCH3), 1.43 (s, 3 H, PCH3), 1.51
(s, 9 H, C(CH3)3), 1.60–1.80 (m, 4 H, PCH2), 1.71 (s, 3 H, PCH3),
1.90–2.20 (m, 4 H, PCH2), 1.91 (s, 3 H, PCH3), 2.24 (s, 3 H, PCH3),
7.20 (s, 1 H, =CH), 7.13 (m, 1 H, ArH), 7.30 (m, 2 H, ArH),
7.75 (m, 2 H, ArH) ppm. 13C{1H,31P} NMR ([D6]acetone): δ = 9.8
(PCH3), 10.7 (PCH3), 16.2 (PCH3), 19.2 (2ϫ PCH3), 20.15 (PCH3),
20.19 (PCH3), 21.4 (PCH3), 27.4 (PCH2), 29.3 (PCH2), 32.9
[C(CH3)3], 33.5 [C(CH3)3], 33.6 (PCH2), 33.9 (PCH2), 48.1
(CϵCtBu), 120.0 (ArC), 126.3 (ArCH), 126.8 (ArCH), 129.3
(ArCH), 132.6 (=CH), 139.5 (CϵCtBu), 154.8 (FeC) ppm.
cis-[Fe(η3-C{CϵCSi(CH3)3}=CHC6H5)(dmpe)2]PF6 (2g): 31P{1H}
NMR ([D6]acetone): δ = 54.2 (ddd, 2JP1P2 = 37, JP1P3 = 44, 2JP1P4
2
= 14 Hz, 1 P, P1), 57.0 (ddd, 2JP2P3 = 161, 2JP2P4 = 40 Hz, 1 P, P2),
2
62.1 (ddd, JP3P4 = 46 Hz, 1 P, P3), 64.9 (ddd, 1 P, P4) ppm.
1H{31P} NMR ([D6]acetone): δ = 0.46 (s, 3 H, PCH3), 0.57 (s, 3
H, PCH3), 1.34 (s, 3 H, PCH3), 1.36 (s, 3 H, PCH3), 1.52 (s, 3 H,
PCH3), 1.60–1.77 (m, 4 H, PCH2), 1.81 (s, 3 H, PCH3), 1.95–2.20
(m, 4 H, PCH2), 2.01 (s, 3 H, PCH3), 2.28 (s, 3 H, PCH3), 6.82 (s,
1 H, =CH), 7.21 (m, 1 H, ArH), 7.36–7.39 (m, 2 H, ArH), 7.79 (m,
2 H, ArH) ppm. 13C{1H,31P} NMR ([D6]acetone): δ = 1.6 (SiCH3),
9.3 (PCH3), 10.0 (PCH3), 15.8 (PCH3), 18.3 (PCH3), 19.7 (PCH3),
20.1 (PCH3), 20.3 (PCH3), 27.1 (PCH2), 29.0 (PCH2), 29.4 (PCH3),
33.2 (PCH2), 33.6 (PCH2), 55.7 (Si-CϵC), 103.6 (Si-CϵC), 126.5
(ArCH), 127.2 (ArCH), 129.3 (ArCH), 130.0 (ArC), 134.1 (=CH),
155.5 (FeC) ppm.
cis-[Fe{η3-C(CϵCPh)=C(H)tBu}(dmpe)2][PF6]
NMR ([D8]THF): δ = 49.89 (ddd, JP1P2 = 39, JP1P3 = 22, JP1P4
(2eЈ):
31P{1H}
2
2
2
2
2
= 29 Hz, 1 P, P1), 54.87 (ddd, JP2P3 = 37, JP2P4 = 170 Hz, 1 P,
P2), 61.87 (ddd, 2JP3P4 = 49 Hz, 1 P, P3), 61.97 (ddd, 1 P, P4) ppm.
1H{31P} NMR ([D8]THF): δ = 0.75 (s, 3 H, PCH3), 0.88 (s, 3 H,
PCH3), 1.26 (s, 3 H, PCH3), 1.27 (s, 3 H, PCH3), 1.28 (s, 3 H,
PCH3), 1.43 (s, 3 H, PCH3), 1.48 [s, 9 H, C(CH3)3], 1.60 (s, 3 H,
PCH3), 1.60–1.80 (m, 4 H, PCH2), 1.87 (s, 3 H, PCH3), 1.90–2.20
(m, 4 H, PCH2), 6.37 (s, 1 H, =CH), 7.28–7.39 (m, 5 H, ArH) ppm.
13C{1H,31P} NMR ([D6]acetone): δ = 9.2 (PCH3), 10.0 (PCH3),
16.2 (PCH3), 18.1 (PCH3), 20.0 (PCH3), 20.4 (PCH3), 20.5 (PCH3),
21.2 (PCH3), 27.5 (PCH2), 28.8 (PCH2), 30.4 [C(CH3)3], 32.9
(PCH2), 33.8 (PCH2), 37.9 [C(CH3)3], 52.4 (CϵCPh), 103.7
(CϵCPh), 128.8 (ArCH), 130.0 (ArCH), 130.4 (ArCH), 131.5
(ArC), 145.0 (FeC), 145.2 [=C(H)Ph] ppm.
cis-[Fe(η3-C(CϵCC6H5)=CH2)(dmpe)2]PF6 (2gЈ): 31P{1H} NMR
2
2
([D6]acetone): δ = (AAЈBC) 48.20 (ddd, JP1P2 = 40, JP1P3 = 29,
2
2
2JP1P4 = 21 Hz, 1 P, P1), 54.29 (ddd, JP2P3 = 161, JP2P4 = 37 Hz,
2
1 P, P2), 62.08 (ddd, JP3P4 = 49 Hz, 1 P, P3), 63.17 (ddd, 1 P, P4)
ppm. H{31P} NMR ([D6]acetone): δ = 0.95 (s, PCH3), 1.09 (s, 3
1
H, PCH3), 1.38 (s, 3 H, PCH3), 1.39 (s, 3 H, PCH3), 1.47 (s, 3 H,
PCH3), 1.48 (s, 3 H, PCH3), 1.60–1.77 (m, 4 H, PCH2), 1.66 (s, 3
H, PCH3), 1.93 (s, 3 H, PCH3), 1.95–2.20 (m, 4 H, PCH2), 6.23 (s,
1 H, =CHH), 6.79 (s, 1 H, =CHH), 7.42–7.46 (m, 5 H, ArH) ppm.
cis-[Fe{C(CϵCC6H4OCH3)=C(H)tBu}(dmpe)2]PF6 (2f) and cis-[Fe-
{C(CϵCtBu)=C(H)C6H4OCH3}(dmpe)2]PF6 (2fЈ): Prepared as de-
scribed for 2a from trans-[Fe(CϵCtBu)(CϵCC6H4OCH3)(dmpe)2]
(1f) (0.020 g, 0.035 mmol) and trifluoroacetic acid (2.7 µL). The
solution was allowed to stand at room temperature for 16 h in
which time it changed colour from yellow to green to dark orange.
Potassium hexafluorophosphate (20 mg) was added, the solvent
was removed and the residue recrystallised from ethanol to give an
orange-brown solid containing 98% 2f and 2% 2fЈ, (12 mg, 41%).
MS (LSIMS) m/z (%): 569.2 (50), 519.2 (78), 465.1 (47), 419.2 (73),
369.2 (100), 287.1 (63). HRMS (LSIMS): 569.20879. Required for
C27H4956FeOP4: 569.2083.
3
Selected 1H NMR ([D6]acetone): δ = 6.23 (p, JPH = 2.0 Hz,
=CHH), 6.79 (p, JPH = 3.0 Hz, =CHH) ppm. 13C{1H,31P} NMR
3
([D6]acetone): δ = 9.1 (PCH3), 9.7 (PCH3), 16.0 (PCH3), 17.9
(PCH3), 19.7 (PCH3), 20.0 (PCH3), 20.2 (PCH3), 21.1 (PCH3), 27.4
(PCH2), 28.7 (PCH2), 32.6 (PCH2), 33.7 (PCH2), 50.6 (PhCϵC),
82.6 (PhCϵC), 119.5 (=CH2), 129.4 (ArCH), 130.1 (ArCH), 130.6
(ArCH), 139.5 (ArC), 166.1 (FeC) ppm.
CCDC-768332 to 768336 (see Table 4) contain the supplementary
crystallographic data for this paper. These data can be obtained
cis-[Fe{η3-C(CϵCtBu)=C(H)C6H4OCH3}(dmpe)2][PF6] (2f): 31P{1H} free of charge from The Cambridge Crystallographic Data Centre
2
2
NMR ([D8]THF): δ = 50.55 (ddd, JP1P2 = 40.3, JP1P3 = 29.2,
via www.ccdc.cam.ac.uk/data_request/cif.
2412
www.eurjic.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2010, 2406–2414

Unsymmetrically Substituted Butenynyl Iron(II) Complexes
Table 4. Crystallographic and structure refinement data for 1a, 1b, 1c, 2a, 2b, 2e and 2eЈ.
1a
1b
1c
2a
2b
2e
2eЈ
Chemical formula
Formula mass
C30H46FeO2P4
618.43
C30H46FeP4
586.44
C32H38F12Fe1P4 C33H53F6FeO3P5 C30H47F6FeP5 C26H47F6FeP5 C26H47F6FeP5
830.36
822.45
732.41
684.34
684.34
Crystal system
a [Å]
b [Å]
c [Å]
monoclinic
9.416(3)
12.313(4)
13.988(5)
monoclinic
9.0517(1)
18.2658(4)
9.5129(2)
monoclinic
12.7683(11)
12.5370(11)
13.4907(13)
triclinic
monoclinic
10.7074(3)
23.5921(5)
14.0345(3)
monoclinic
9.3617(17)
19.4957(17)
18.0126(11)
monoclinic
9.7692(16)
18.966(4)
18.393(4)
12.934(3)
12.974(3)
13.818(3)
101.713(5)
105.265(5)
113.250(5)
1928.1(7)
173(2)
α [°]
β [°]
γ [°]
90.22(3)
90.0265(13)
117.013(4)
91.3765(14)
91.922(9)
102.182(15)
Unit cell volume/Å3
Temperature [K]
Space group
1621.81(3)
294(2)
P21/c
2
1572.83(5)
200
P21/a
2
1923.9(3)
273(2)
P21/n
4
3544.23(14)
200
P21/c
3285.7(7)
293(2)
P21/c
3331.3(11)
294(2)
P21/c
¯
P1
2
Z
4
4
4
Reflections measured
Independent reflections
Rint
25322
6026
0.0277
0.0211
27967
3608
25482
2761
11328
8235
54324
6248
0.062
0.0364
0.0810
0.0722
0.1052
768336
6147
5764
6372
6001
0.035
0.0280
0.0687
0.0339
0.0743
768333
0.0376
0.0765
0.1954
0.0900
0.2093
768334
0.0165
0.0300
0.0840
0.0370
0.0862
768335
0.0964
0.0595
0.1484
0.2452
0.2052
768337
0.0489
0.0530
0.1367
0.2264
0.1879
768338
Final R1 values [IϾ2σ(I)]
Final wR(F2) values [IϾ2σ(I)] 0.0504
Final R1 values (all data)
Final wR(F2) values (all data)
CCDC number
0.0227
0.0512
768332
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Received: March 12, 2010
Published Online: April 26, 2010
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© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2010, 2406–2414