Dithiocarbamate derivatives of μ-thiocarbyne complexes: Synthesis and X-ray molecular structure of [Fe2(μ-CS)(μ-CSMe) (μ-S2CNMe2)Cp2]

Article abstract of DOI:10.1016/S0022-328X(02)01652-2

Reaction of [Fe₂(μ-CS)(μ-CSMe)Cp₂(CO)₂]⁺ (1) with sodium N,N-dimethyldithiocarbamate [Me₂dtc]Na affords a mixture of the dithiocarbene [FeFe(μ-CS){μ-C(SMe)SC(S)NMe₂}Cp(CO)] (2) and the thiocarbyne [Fe₂(μ-CS)(μ-CSMe)(μ-S₂CNMe₂)Cp₂] (3). Complex 2 is quantitatively converted into 3 by photochemical irradiation. The X-ray molecular structure of 3 demonstrates the presence of three bridging ligands and exhibits the shortest Fe-Fe interaction found in similar systems [2.453(1) A?]. Complex 3 can also be obtained by reacting [Me₂dtc]^- with the di-solvento thiocarbyne [Fe₂(μ-CS)(μ-CSMe)(NCMe)₂Cp₂]⁺ (1a). By contrast no stable addition product has been isolated in analogous reactions involving the thiocarbyne [Fe₂(μ-CO)(μ-CSMe)Cp₂(CO)₂]⁺ (1b). The [Me₂dtc]^- nucleophilic addition at the μ-C to form [Fe₂(μ-CO){μ-C(CN)SC(S)NMe₂}Cp₂(CO)₂] (4a) is obtained starting from [Fe₂(μ-CO){μ-C(CN)(SMe₂)}Cp₂(CO)₂]SO₃CF₃ (1d). Photochemical reaction of the cyanocarbene 4a causes intramolecular ring closure affording [FeFe(μ-CO){μ-C(CN)SC(S)NMe₂}Cp₂(CO)] (5a).

Full text of DOI:10.1016/S0022-328X(02)01652-2

Journal of Organometallic Chemistry 659 (2002) 15ꢃ21
/
www.elsevier.com/locate/jorganchem
Dithiocarbamate derivatives of m-thiocarbyne complexes: synthesis
and X-ray molecular structure of [Fe2(m-CS)(m-CSMe)(m-
S2CNMe2)Cp2]
Vincenzo G. Albano b, Silvia Bordoni a,*, Luigi Busetto a, Antonio Palazzi a,
Piera Sabatino b, Valerio Zanotti a
a Dipartimento di Chimica Fisica ed Inorganica, Facolta’ di Chimica Industriale, Viale Risorgimento 4, Bologna I-40136, Italy
b Dipartimento di Chimica ‘Ciamician’, Via Selmi 2, Bologna I-40124, Italy
Received 20 May 2002; received in revised form 18 June 2002; accepted 18 June 2002
Abstract
Reaction of [Fe2(m-CS)(m-CSMe)Cp2(CO)2]ꢀ (1) with sodium N,N-dimethyldithiocarbamate [Me2dtc]Na affords a mixture of the
ꢀ
ꢁ
dithiocarbene [Fe
/
Fe(m-CS){m-C(SMe)S//C(S)NMe2}Cp(CO)] (2) and the thiocarbyne [Fe2(m-CS)(m-CSMe)(m-S2CNMe2)Cp2] (3).
Complex 2 is quantitatively converted into 3 by photochemical irradiation. The X-ray molecular structure of 3 demonstrates the
˚
Fe interaction found in similar systems [2.453(1) A]. Complex 3 can
presence of three bridging ligands and exhibits the shortest FeÃ
/
also be obtained by reacting [Me2dtc]ꢁ with the di-solvento thiocarbyne [Fe2(m-CS)(m-CSMe)(NCMe)2Cp2]ꢀ (1a). By contrast no
stable addition product has been isolated in analogous reactions involving the thiocarbyne [Fe2(m-CO)(m-CSMe)Cp2(CO)2]ꢀ (1b).
The [Me2dtc]ꢁ nucleophilic addition at the m-C to form [Fe2(m-CO){m-C(CN)SC(S)NMe2}Cp2(CO)2] (4a) is obtained starting from
[Fe2(m-CO){m-C(CN)(SMe2)}Cp2(CO)2]SO3CF3 (1d). Photochemical reaction of the cyanocarbene 4a causes intramolecular ring
ꢀ
ꢁ
closure affording [Fe
/
Fe(m-CO){m-C(CN)S//C(S)NMe2}Cp2(CO)] (5a). # 2002 Elsevier Science B.V. All rights reserved.
Keywords: Dithiocarbamate; Thiocarbyne; Dithiocarbene; Bridging; Dinuclear; Iron
1. Introduction
BH3CN [4] (dppmꢂ
/
PPh2CH2PPh2, RꢂEt, Me,
/
CH2Ph) [Au2{(m-CH2)2PPh2}(m-R2dtc)] and [Au2(m-
R2dtc)2] [5], and, more recently, the [Rh2(CO)2(NBD)-
Dithiocarbamates are the subject of current research
due to their potential applications and interesting
coordination behaviour. They easily form chelate rings
with virtually all transition elements affording a
plethora of monomeric complexes [1,2]. However, bi-
nuclear species, containing these bidentate ligands
symmetrically bridging two metal centres, are relatively
rare [2]. To our knowledge few examples of discrete
molecules have so far been reported: [Ru2(Et2dtc)5]BF4
[3], binuclear diauracycles as [Au2(m-R2dtc)dppm]-
(RR?dtc)2] (Rꢂ
/
Me, R?ꢂ
/
Ph) [6] (NBDꢂnorborna-
/
diene).
During our investigations on the chemistry of diiron-
thiocarbyne complexes of the type [Fe2(m-CX)(m-
CSMe)Cp2(CO)2]OSO2CF3 [Xꢂ
/S
(1a);
O
(1b)],
7a[7b,7c] we have observed that substitution of the
bridging carbonyl by a thiocarbonyl ligand confers
different reactivity trends, likely arising from the higher
Fe2Ã
/
(m-CS) bond order, compared with Fe2Ã(m-CO) [8].
/
This property is here evidenced by the ability, shown by
[Me2dtc] anion, to differently react and/or coordinate
Abbreviations: dppm, Ph2P(CH2)PPh2; [Me2dtc]ꢁ ꢂ[Me2NCS2]ꢁ
,
dithiocarbamate; NBD, norbornadiene or bicyclo[2.2.1]hepta-
/
the dimetalꢃ
XꢂS we have succeeded in isolating the air stable
complex [Fe2(m-CS)(m-CSMe)(m-S2CNMe2)Cp2] (3), via
/
carbyne complexes of type 1. In fact when
i
2,5octene; Pr, isopropyl.
/
* Corresponding author. Tel.: ꢀ
209-3600
E-mail address: bordoni@ms.fci.unibo.it (S. Bordoni).
/
39-051-209-3694; fax: ꢀ39-051-
/
ꢀ
ꢁ
the unstable species [Fe
/
Fe(m-CS)[m-C(SMe)SC(S//
)
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 6 5 2 - 2

16
V.G. Albano et al. / Journal of Organometallic Chemistry 659 (2002) 15ꢃ21
/
NMe2(Cp)(CO)] (2), whereas, in the case of the carbonyl
analogues (Xꢂ
O), the reaction with [Me2dtc]ꢁ results
in a progressive degradation to the thiocarbonyl species
[Fe2(m-CO)(m-CS)Cp2(CO)2]. The X-ray molecular
structure of 3 provides a further report of a two-
metal-centres symmetrical bridging dithiocarbamate
[7c,8]. Finally, the diasterotopicity of the NÃ
/
Me groups
/
is evidenced by distinct 13C signals (at 47.6 and 43.4
ppm), while a broad resonance at 3.1 ppm is observed in
the 1H-NMR. The first eluted fraction has been
identified as [Fe2(m-CS)(m-CSMe)(m-S2CNMe2)Cp2], (3)
(10% yield), in which both the CO ligands of 1a have
been substituted by the bidentate dithiocarbamate
ligand. An exiguous third purple fraction, containing
traces of the known Fe(Me2dtc)3 (less than 3%), has
been characterised by literature data comparison [9].
Further experiments, run at low temperatures with
prolonged reaction times give similar products distribu-
tion.
complex [3ꢃ5].
/
2. Results and discussion
2.1. Reactions of m-carbyne complexes with
dithiocarbamate
The reaction depicted in Scheme 1 presumably takes
place by nucleophilic addition of [Me2dtc]ꢁ to the
electrophilic bridging carbon atom m-CSMe. Then, the
supposed dithiocarbene intermediate evolves with for-
When an equimolar amount of sodium dimethyl-
dithiocarbamate is added at room temperature to a
bright green solution of the cationic derivative cis-
[Fe2(CO)2Cp2(m-CS)(m-CSMe)]ꢀ (1a) in acetone, a
brown cloudy mixture is rapidly formed. Chromatogra-
phy on alumina column yields two main products
(Scheme 1). The solvent-freed second fraction shows
only a single sharp IR carbonyl absorption at 1956
mation of the s FeÃ/S bond, affording complex 2.
Nevertheless, the latter is still a rather unstable species
and, on standing for a few hours in dichloromethane
solution, partially turns into the thiocarbyne derivative
[Fe2(m-CS)(m-CSMe)(m-S2CNMe2)Cp2] (3). The latter
exhibits IR bands attributed to the m-CS bridging group
(1116 cmꢁ1) and CN stretching (1492 cmꢁ1) but no CO
cmꢁ1 and the n(CN) stretching band at 1506 cmꢁ1
,
ꢁ
ꢀ
1
suggesting its formulation as [Fe
/
Fe(m-CS){m-C(SMe)S//
absorption. Single H-NMR resonances both for cyclo-
C(S)NMe2}Cp2(CO)] (2). The observation, in the
NMR spectra, of signals corresponding to nonequiva-
lent Cp ligands together with the bridging m-C dithio-
carbene and thiocarbonyl carbons, at 170.6 and 393.4
ppm, respectively, agrees with the proposed structure.
Moreover, the 1H-NMR chemical shift at 2.98 ppm
attributable to the SMe substituent, rules out the
pentadienyl (d 4.77) and NÃ
/
Me groups (d 3.2) and the
presence, as peculiar spectroscopic feature, of signals at
d 3.52 (1H-NMR) and 408 (13C-NMR) relative to m-
CSMe moiety, point to a symmetrically bridging dithio-
carbamate coordination, as shown by the X-ray diffrac-
tion structural study (see later).
The unusual 2 to 3 transformation, which quantita-
tively occurs under photochemical conditions (Scheme
ꢀ
ꢁ
possible structure [Fe
/
Fe(m-CS){m-C(S//Me)SC(S)N-
1), is likely driven by the formation of a strong ironꢃ
iron interaction, due to the simultaneous presence of
three bridging ligands, and by the favourable entropic
/
Me2}Cp2(CO)], which would exhibit a more upshifted
signal, as already found for compounds in which the S-
atom of the thioalkoxy group is metal coordinated
Scheme 1.

V.G. Albano et al. / Journal of Organometallic Chemistry 659 (2002) 15ꢃ
/
21
17
balance of the CO elimination. In addition, it should be
pointed out that an analogous thiocarbene-thiocarbyne
ture, facilitated by the presence of the m-CO instead of
the more stabilising m-CS group.
In line with our previous findings, testifying the
general approach of the bridging carbene diiron com-
plexes bearing heteroatom substituent [15], we have
rearrangement with CÃ
/
S bond breaking and migration
of the thioalkoxy group, has already been observed for
[Fe2(m-CO){m-C(SMe)SPh}Cp2(CO)2], which affords
the carbonyl-substituted derivative [Fe2(m-CO){m-
C(SMe)}Cp2(CO)(SPh)] in refluxing CH2Cl2 [10].
It is worth noting that the 13C-NMR set of signals of
the neutral m-carbyne 3 are only slightly upfield shifted
with respect to the cationic precursor 1a, in line with
what reported for similar compounds [10]. This obser-
vation supports the idea that a certain charge separation
persists in 3, according to the ylide resonance formula
(Fig. 1). An analysis of the bond distances agrees with
this consideration (see later).
ꢀ
ꢁ
obtained [F
[RꢂR?ꢂMe (4a); Rꢂ
the dithiocarbamate anion with the pseudoꢃ
byne complex
[Fe2(m-CO){m-C(CN)(SMe2)}Cp2-
(CO)2]OSO2CF3 (1d), as a result of SMe2 displacement.
The broad 1H-NMR signal attributed to the NÃ
Me
/
e2(m-CO){m-C(CN)SC(S//)NRR?}Cp2(CO)2]
H, R?ꢂi
Pr (4b)] by reacting
cyanocar-
/
/
/
/
/
/
groups, due to hindered rotation around the CN bond,
becomes a single sharp singlet as the temperature raises
to 46 8C. The cis stereogeometry of 4 (nCO 2011vs,
1982m) is confirmed by a single cyclopentadienyl
resonance (d 4.7 in the case of 4b). The stability of
these species further confirms that the electron with-
drawing effect of the cyano group [15] results in a neat
stabilisation of the thiocarbene derivatives. Therefore, it
has been necessary UV irradiation of type 4 complexes
Complex 3 has also been prepared from the solvento
complex [Fe2(m-CS)(m-CSMe)Cp2(NCMe)2]ꢀ (1c). This
novel acetonitrile derivative has been obtained as brown
powder by replacing both the CO groups of 1a in MeCN
solvent in the presence of Me3NO (Scheme 1). Single
13C-NMR resonances at d 87.3 (Cp) and 126.3 (NCMe)
for terminal ligands suggest the retention of cis stereo-
geometry, while the dinuclear structure is confirmed by
the observation of both the bridging thiocarbonyl (d
388.3) and thiocarbyne m-C (d 413.3) signals. Addition
of a slight excess of dithiocarbamate to an acetone
solution of the solvento complex (1c) promptly affords
the [Fe2(m-CS)(m-CSMe)(m-S2CNMe2)Cp2] (3) in 59%
yield (Scheme 1) together with the formation of the
known Fe(Me2dtc)3 (30%), which has been separated by
column chromatography.
to promote SÃ
[FeFe(m-CO){m-C(CN)SC(S)NRR?}Cp2(CO)]
R?ꢂMe (5a); Rꢂ Pr (5b)]. The IR stretching
H, R?ꢂi
/
Fe bond formation and to obtain
[Rꢂ
/
/
/
/
of the remaining carbonyl ligand in type 5 complexes
sensibly moves to lower wavenumbers [1957 cmꢁ1 for
5b]. The intramolecular cyclization gives rise to distinct
1H-NMR signals (d 3.2 and 3.1) for the NÃ
/
Me
diasteroisomeric groups arising from the hindered rota-
tion around the dithiocarbamate CN bond. Sulphur
coordination, enhancing the electron density onto the
metal skeleton, is responsible for the marked upfield
shift of the 13C-NMR carbene resonance from d 128.8
(in 4a) to 105.7 ppm (in 5a) (Scheme 2).
The observation that the thiocarbyne complex [Fe2(m-
CO)(m-CSMe)Cp2 (CO)2]OSO2CF3 (1b) undergoes ad-
dition to m-CSR by a variety of nucleophiles including
SRꢁ [10ꢃ
12] to give the corresponding thiocarbene
/
2.2. The X-ray molecular structure of [Fe2(m-CS)(m-
CSMe){m-S2CNMe2}Cp2] (3)
derivatives, has prompted us to extend the reactivity
investigation to dithiocarbamates. In this case, however,
we have been unable to isolate stable addition products.
In fact, the reaction of 1b with [Me2dtc]ꢁ even at 0 8C
leads to the formation of the mononuclear [Fe(h2-
S2CNMe2)Cp(CO)] [13] together with the thiocarbonyl
dimeric complex [Fe2(m-CO)(m-CS)Cp2(CO)2] [14]. Our
inability to isolate addition products of ꢁ[SC(S)NMe2]
to m-C probably arises from the ease with which these
An ORTEP drawing of 3 is shown in Fig. 2 and
relevant bond parameters are reported in Table 1. The
molecule contains a diiron unit coordinated by the C5H5
ligands in the expected cis configuration and three
bridging ligands. The thiocarbonyl and thiomethoxy
groups are positioned almost opposite to each other
(dihedral angle 15.088) and the dithiocarbamate, acting
as bidentate, is almost orthogonal to the other bridging
ligands. The latter ligand occupies the sites of the
species undergo decomposition, via CÃ
/
SR bond rup-
terminal CO groups in the precursor cation 1. The
˚
Fe distance [2.453(1) A] is quite short in comparison
FeÃ
/
with the numerous experimental values reported for this
family of compounds. The actual value falls at the lower
limit of the following trend: [Fe2(m-CO)2(CO)2(Cp)2]
2.531(2)
2.510(2)
[16a],
[16b],
[Fe2(m-CO)(m-CSEt)(CO)2(Cp)2)]ꢀ
[Fe2(m-CS)(m-CSMe)(CO)2(Cp)(h4-
C5H5th)] 2.508(1) 8b, [Fe2(m-CO)(m-CS)(CO)2(Cp)2]
2.505 (3) [16c], [Fe2(m-CS)2(CO)2(Cp)2] 2.482(1) A
Fig. 1. Ylidic resonance form of [Fe2(m-CS)(m-CSMe)(m-
S2CNMe2)(Cp)2].
˚

18
V.G. Albano et al. / Journal of Organometallic Chemistry 659 (2002) 15ꢃ21
/
Scheme 2.
of the different balance of s and p components of the
bonds for the two ligands. This effect, although small, is
significant also because the SÁ Á ÁS bite distance in the
˚
dithiocarbamate [3.02 A] would better fit a longer
metalꢃ
/
metal bond. A database search [17] of the
metal distances spanned by bridging dithiocar-
metalꢃ
/
bamate ligands confirms that the present FeÃ
action is the shortest ever found.
It is noteworthy the presence in this molecule of four
types of sulphurꢃcarbon bonds ranging from the multi-
/
Fe inter-
/
ple bond of the bridging thiocarbonyl [S(3)Ã
/
C(2)
˚
1.616(3) A] to the pure single bond [S(4)Ã
/
C(16)(methyl)
˚
1.811(4) A]. The former is a pure double bond because
an analysis of the R2CÄS distances found in thioketones
reveals values in the range 1.61ꢃ
bond in the thiocarbyne ligand [1.676(3) A], being closer
to the distance in the thiocarbonyl than the SÃC(alkyl),
/
Fig. 2. Molecular structure of 3 showing the atomic numbering
(thermal ellipsoids at 50% probability level).
˚
/
1.64 A. The S(4)Ã
/
C(1)
˚
/
indicates substantial multiple bond explainable in terms
of donation from a sulphur lone pair to the empty p-
orbital of the formally positive C(1) carbon. This p
interaction significantly extends to the iron atoms, as
Table 1
˚
Relevant bond distances (A) and angles (8) for [Fe2(m-CS)(m-CSMe){m-
S2CNMe2)(Cp)2] (3)
Bond lengths
shown by the shorter FeÃ
/
C(1)(carbyne) average dis-
Fe(1)ÃFe(2)
Fe(1)ÃC(1)
Fe(1)ÃC(2)
Fe(1)ÃS(1)
Fe(2)ÃC(1)
Fe(2)ÃC(2)
Fe(2)ÃS(2)
Fe(1)ÃC(Cp)
Fe(2)ÃC(Cp)
2.453(1)
1.806(3)
1.881(3)
2.259(1)
1.813(3)
1.865(3)
2.265(1)
S(1)ÃC(3)
S(2)ÃC(3)
S(3)ÃC(2)
S(4)ÃC(1)
S(4)ÃC(16)
NÃC(3)
1.716(3)
1.712(3)
1.616(3)
1.676(3)
1.811(4)
1.340(4)
1.454(5)
1.455(5)
˚
tance [1.809(3) A] in comparison to FeÃC(2)(thiocarbo-
/
˚
nyl) [1.873(4) A].
The dimethyldithiocarbamate ligand exhibits a reg-
ular geometry with significant multiple bond character
˚
˚
N [1.340(4) A]
interactions, as one can infer from a comparison with
of the SÃ
/
C [average 1.714(3) A] and CÃ
/
NÃC(4)
2.14(1) av NÃC(5)
2.12(2) av
the genuine single bonds S(4)Ã
/
C(16)(methyl) [1.811(4)
˚
C(4,5)(methyl) [1.454(5) A]. These distances
˚
Bond angles
A] and NÃ
/
C(1)ÃFe(1)ÃC(2)
C(1)ÃFe(1)ÃS(1)
C(2)ÃFe(1)ÃS(1)
S(1)ÃFe(1)ÃFe(2)
C(1)ÃFe(2)ÃC(2)
C(1)ÃFe(2)ÃS(2)
C(2)ÃFe(2)ÃS(2)
S(3)ÃC(2)ÃFe(2)
Fe(1)ÃC(2)ÃFe(2)
NÃC(3)ÃS(1)
95.2(1)
89.5(1)
88.3(1)
96.58(3)
95.5(1)
90.3(1)
89.1(1)
140.2(2)
81.8(1)
117.8(2)
118.5(2)
S(2)ÃFe(2)ÃFe(1)
97.85(3)
111.5(1)
110.4(1)
143.2(2)
131.4(2)
85.4 (1)
138.0(2)
123.6(2)
122.1(3)
122.4(3)
115.4(3)
are well within the range of values reported in the
copious structural reports of the dithiocarbamate li-
gands in a variety of bonding modes.
C(3)ÃS(1)ÃFe(1)
C(3)ÃS(2)ÃFe(2)
S(4)ÃC(1)ÃFe(1)
S(4)ÃC(1)ÃFe(2)
Fe(1)ÃC(1)ÃFe(2)
S(3)ÃC(2)ÃFe(1)
S(1)ÃC(3)ÃS(2)
C(3)ÃNÃC(4)
3. Experimental
3.1. General methods
C(3)ÃNÃC(5)
C(4)ÃNÃC(5)
NÃC(3)ÃS(2)
Standard inert-atmosphere techniques have been used
in the execution of the experiments. The solvents
[16d]. As one can infer from the figures above, m-CS
Fe
interaction. Substitution of the bidentate dithiocarba-
methylene chloride (CaH2), tetrahydrofuran (Naꢃ
/
ben-
replacing m-CO has a shortening effect on the FeÃ
/
zophenone), and petroleum ether 40ꢃ70 8C were dis-
/
tilled immediately before use under nitrogen from the
appropriate drying agents. Complex 1a was prepared as
previously reported [7,14]. [Me2NCS2]Na was obtained
mate for two terminal COs produces a further strengh-
tening of the FeÃ/Fe interaction, very probably because

V.G. Albano et al. / Journal of Organometallic Chemistry 659 (2002) 15ꢃ
/
21
19
from commercial sources and dried under vacuum for 2
h at 100 8C. Instruments employed: IR, FT Perkinꢃ
Elmer Spectrum 2000, NMR Varian Gemini 200
MHz. Spectra were registered at room temperature
(r.t.), solvent peaks were used as internal reference, the
chemical shifts are reported in d (ppm) relative to TMS.
yellow to brown. The solvent-freed residue was then
chromatographed on alumina column (8ꢄ2 cm) eluting
with CH2Cl2ꢃpetroleum ether (30ꢃ40 8C) (2:1ꢂv:v).
Two fractions, showing no carbonyl bands in their IR
spectrum, were collected. The first brown band, gave by
/
/
/
/
/
crystallisation from CH2Cl2ꢃ
20 8C (102 mg 0.218 mmol, 59% yield) of 3. M.p.
(dec.) 188ꢃ192 8C. Elemental Analysis: C, 41.3(41.8);
/hexane at low temperature
ꢁ
/
3.2. Reaction with [Fe2(m-CS)(m-CSMe)Cp2(CO)2]
(2)
/
H, 4.1 (4.3); S, 27.7(27.9)%. IR (CH2Cl2 in cmꢁ1): 1116s
(CS), 1491m, 1374s (CN); (KBr): 1118 (CS), 1058m
(CSMe), 1492m, 1370m, 1004s (NCS). 1H-NMR
(CDCl3, d in ppm): 3.52 (s, 3H, CSMe), 4.77(s, 10H,
Cp), 3.19 (s, 6H, NMe2). 13C{1H} (CD2Cl2): 393.7 (m-
CS), 408.0 (m-CSMe), 201.9 (CN), 91.8 (Cp), 47.6
(NMe2), 31.3 (SMe). Crystallisation of the second
purple band yielded 46 mg (0.111 mmol, 30%yield) of
the known Fe(S2CNMe2)3 (A).
To a solution of cis-1a (0.230 g, 0.418 mmol) in
acetone (10 ml) an equimolar amount of [Me2dtc]Na×
/
2H2O (0.076 g,0.42 mmol) was added. The initially
bright green solution in 15 min changed into deep
brown. The solvent was removed under reduced pres-
sure, the residue extracted and chromatographed on an
alumina column (8ꢄ
nechloride and petroleum ether (40ꢃ
A minor brownꢃyellow fraction (20 mg, 10% yield of 3)
/2 cm) with a mixture of methyle-
/
70 8C) (2:1ꢂv:v).
/
/
3.4. Preparation of Fe2(m-CO){m-
and a second deep orange one (2) were collected and
dried under vacuum. Traces of the known Fe3(Me2dtc)3
(A) were obtained from the third purple band collected.
C(CN)(SC(S)NRR?)}(Cp)2(CO)2] [R, R?ꢂ
/Me
(4a); Rꢂi
/
Pr, R?ꢂH (4b)]
/
Crystallisation from methylene chlorideꢃ
ether at ꢁ20 8C gave brown needles of 2 (0.072 g,
0.15 mmol 35% yield). Melting point (m.p.) 162ꢃ
/
petroleum
[Fe2(m-CO){m-C(CN)(SMe2)}Cp2(CO)2]SO3CF3 (1d)
(80 mg, 0.135 mmol) dissolved in acetonitrile (5 ml)
/
/
were stirred at r.t. with a slight excess of Na[Me2NCS2]×
/
165 8C. Elemental Analysis: C, 41.4(42.3); H, 3.9(4.5);
S, 25.9(25.6)%. IR (in CH2Cl2): 1956s (CO), 1506m,
1391m (NCS), 1112s (CS); (in KBr): 1956vs (CO),
1503m, 1385m, 1003w (NCS), 1107s (CS), 1051m
(CSMe). 1H-NMR (CDCl3) d (ppm): 2.98(s, 3H
CSMe), 4.89, 4.69 (s, 10H, Cp), 3.10 (br, 6H, NMe2);
13C{1H} (CDCl3): 393.4 (m-CS), 214.7 (CO), 92.3, 90.9
(Cp), 170.6 (m-C), 35.8 (SMe), 205.6 (CN), 47.6, 43.4
(NMe2).
2H2O (40 mg). The reaction was monitored by IR
spectroscopy. After 30 min the solvent was extracted
under reduced pressure and the residue filtered on
alumina pad by using dichloromethane as eluant.
Crystallisation from CH2Cl2ꢃpetroleum ether gave 72
/
mg of bright red crystals (0.128 mmol, 95%) of 4a, m.p.
144 8C. IR (CH2Cl2 cmꢁ1): 2163w (CN),
(dec.) 141ꢃ
/
1
2005vs, 1972m, 1807s (CO), 1495 (CNR2 in KBr). H-
NMR (CDCl3, d in ppm): 5.05 (s, 10H, Cp), 3.55, 3.30
(d, br, 6H, NMe2). 13C{1H} (CD2Cl2): 262.6 (m-CO),
209.1 (CO), 200.0 (CS2), 128.8 (CN), 91.8 (Cp), 47.6
3.3. Preparation of [Fe2(m-CS)(m-CSMe){m-
S2CNMe2}Cp2] (3)
(NMe2); 4b, m.p. 143ꢃ
144 8C. IR (CH2Cl2 cmꢁ1):
/
2011vs, 1982m (CO), 1815s (m-CO), 2158w (CN), 1492
(CNR2 in KBr). 1H-NMR (CDCl3, d in ppm): 6.9 (s, br,
1H, NH), 4.6 (m, 1H, CH), 4.7 (s, 10H, Cp), 1.2 (m, br,
6H, NMe2).
To a stirring solution of 1a (200 mg, 0.364 mmol) in
acetonitrile (20 ml) were added two equivalents of
Me3NO (55 mg, 0.73 mmol). The initially deep green
solution immediately changed to brownꢃyellow. After
/
ꢀ
ꢁ
15 min, when IR detection revealed loss of both the
carbonyl groups, the solvent was removed under re-
duced pressure. The residue was then extracted with
CH2Cl2 and immediate filtration on celite pad was
necessary to prevent considerable decomposition.
3.5. Preparation of [Fe
NRR?)}Cp2(CO)] [R, R?ꢂ
(5b)]
/
Fe(m-CO{[m-C(CN)SC(S//
)
/
Me (5a); Rꢂi
/
Pr, R?ꢂH
/
THF solutions (5 ml) of 5a,b (100 mg, 0.18 mmol for
5a) were irradiated under UV lamp following the
reaction trend by IR spectroscopy. After 20 min the
solvent was evaporated and the residue, dissolved in
dichloromethane and chromatographed on alumina
2 cm.) using CH2Cl2ꢃpetroleum ether
(1:2ꢂv:v) as eluant. The first brown fraction collected
was recognised as the known [Fe(m-S2CNMe2)Cp(CO)]
(IR n 1940 CO); the second brown fraction was collected
and crystallised at low temperature (ꢁ20 8C) giving 53
Washing with Et2O (2ꢄ
/
5 ml) gave a brownꢃyellow
/
powder (189 mg, 0.327 mmol, 90% yield) of 1c. IR
(CH2Cl2): 1031 (s, CSMe); 13C{1H} (CDCl3): 388.3 (m-
CS), 87.3 (Cp), 413.3 (m-C), 40.7 (SMe), 126.3 (CNMe).
A slight excess of a solution of Me2NCS2Na×
/2H2O (107
column (8ꢄ
/
/
mg, 0.6 mmol) in acetone (5 ml) was added to [Fe2(m-
CS)(m-CSMe)Cp2(NCMe)2]OSO2CF3 (1c) (0.52 mmol
300 mg) dissolved in the same solvent and stirred at r.t.
for 30 min, until the reaction mixture turned from
/
/

20
V.G. Albano et al. / Journal of Organometallic Chemistry 659 (2002) 15ꢃ21
/
Table 2
Crystal data and details of structure refinement for complex 3
4. Supplementary material
Crystallographic data (excluding structure factors) for
the reported structure have been deposited with the
Cambridge Crystallographic Data Centre as supplemen-
tary publication CCDC 168588. Copies of data
can be obtained free of charge on application to The
Director, CCDC, 12 Union Road, Cambridge CB2
Empirical formula
Formula weight
Temperature (K)
C16H19Fe2NS4
465.26
293
˚
Wavelength (A)
0.71069
Monoclinic
P21/n
Crystal system
Space group
Unit cell dimensions (A)
˚
1EZ, UK (Fax: ꢀ44-1223-336093; e-mail: deposit@
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
/
a
b
c
8.674(2)
16.827(3)
12.638(3)
93.12(3)
1841.9
4
b (8)
Volume (A )
3
˚
Acknowledgements
Z
F(000)
Crystal size (mm)
952
0.25ꢄ0.13ꢄ0.32
25
3392
We acknowledge the University of Bologna and
MIUR for financial support.
Max u for data collection (8)
Number of reflections collected
Number of observed independent reflections 3222
Number of parameters
Goodness-of-fit on F2
Final R indices [I ꢀ2s(I)]
322
1.03
References
0.0335 (R) 0.089 (wR2)
ꢁ3
˚
Largest difference peak and hole (e A
)
0.26, ꢁ0.15
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(b) M. Bond, R.L. Martin, Coord. Chem. Rev. 54 (1984) 23;
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Comprehensive Coordination Chemistry, vol. 2, Pergamon,
Oxford, UK, 1987, p. 585;
mg (0.10 mmol, 51% yield). Complex 5a, IR (CH2Cl2 in
cmꢁ1): 1955 (CO), 1776 (m-CO), 2163 (CN), 1526 (CN
(d) R.P. Burns, F.P. McCullough, C.A. McAuliffe, Adv. Inorg.
Chem. Adv. Radioch. 23 (1980) 211.
1
in KBr). H-NMR (CDCl3 in cmꢁ1, d in ppm): 4.7, 4.5
[2] (a) D.D. Heinrich, J.-C. Wang, J.P. Fackler, Jr., Acta Crystallogr.
46 (1990) 1444;
(s, 10H, Cp), 3.1, 3.2 (s, br, 6H NMe2).13C{1H} 273.3
(m-CO), 213.3 (CO), 207.8 (CS2), 134.4 (CN), 105.7 (m-
C), 89.1, 87.0 (Cp), 75.2, 75.6 (NMe2). Complex 5b, IR
(CH2Cl2 in cmꢁ1): 1957 (CO), 1777(m-CO), 1528 (CN in
KBr). 1H-NMR (CDCl3, d in ppm): 6.7 (s, br, 1H, NH),
4.7 4.6 (Cp), 3.6 (m, br, 1H, CH), 1.1 (m, br, 6H, NMe2).
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564.
[4] M. Nazrul, I. Khan, C. King, D.D. Heinrich, J.P. Fackler, Jr.,
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3.6. X-ray crystallography
(b) P. Jennische, H. Anacker-Eickhoff, A. Wahlberg, Acta
Crystallogr. Sez. A 31 (1975) S143;
Crystals of 3 suitable for the X-ray single crystal
diffraction studies were grown from CH2Cl2ꢃ
low temperature (ꢁ20 8C). Diffraction intensities were
collected at r.t. on an EnrafꢃNonius CAD-4 diffract-
ometer using graphite monochromated MoꢃKa radia-
tion. Data were collected using v scanning mode and
corrected for absorption empirically. Crystal data and
details of structure refinement are reported in Table 2.
Structure was solved by direct methods and refined on
F2 by full-matrix least-squares calculations using the
SHELXTL/PC package 17b. Thermal vibrations were
/
hexane at
(c) R. Hesse, P. Jennische, Acta Chem. Scand. 26 (1972) 3855.
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1224;
/
/
/
(b) V.G. Albano, S. Bordoni, L. Busetto, C. Camilletti, M.
Monari, A. Palazzi, F. Prestopino, V.J. Zanotti, Chem. Soc.
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(c) M.H. Quick, R.J. Angelici, Inorg. Chem. 20 (1981) 1123.
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Monari, F. Prestopino, V. Zanotti, J. Chem. Soc. Dalton Trans.
(1996) 3693;
treated anisotropically for all non-H atoms; cyclopenta-
˚
C 1.42 A]. H
diene rings were refined as rigid groups [CÃ
/
atoms were located in the final difference Fourier maps
and refined riding on their corresponding carbon atoms
(c) J.R. Matachek, R. Angelici, K. Schugart, K.J. Aller, R.F.
Fenske, Organometallurgy 3 (1984) 1038.
[9] A. White, H. Kokot, E. Roper, R. Waterman, R.L. Martin, Aust.
J. Chem. 17 (1964) 294.
˚
˚
[CÃ
converged at a final Rꢂ
were prepared using ORTEP3 for WINDOWS NT [17c].
/
H 0.96 A for CH3 and 0.93 A for C5H5]. Refinement
/
0.0335. Molecular graphics
[10] N.C. Schroeder, R. Funchess, R.A. Jacobson, R.J. Angelici,
Organometallurgy 8 (1989) 521.

V.G. Albano et al. / Journal of Organometallic Chemistry 659 (2002) 15ꢃ
/
21
21
[11] L. Busetto, S. Bordoni, V. Zanotti, V.G. Albano, D. Braga, Gazz.
Chim. Ital. 118 (1988) 667.
[16b] R.E. Wagner, R.J. Jacobson, R.J. Angelici, M.H. Quick, J.
Organomet. Chem. 148 (1978) C35.
[16c] D.E. Beckman, R.A. Jacobson, J. Organomet. Chem. 179 (1979)
187.
[12] L. Busetto, L. Carlucci, V. Zanotti, V.G. Albano, D. Braga, J.
Chem. Soc. Dalton Trans. (1990) 243.
[16d] J.W. Dunker, J.S. Finez, J. Clordy, R.J. Angelici, J. Organomet.
Chem. 114 (1976) C49.
[13] E.W. Abel, M.O. Dunster, J. Chem. Soc. Dalton Trans. (1973) 98.
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(b) J.R. Matachek, R.J. Angelici, Inorg. Chem. 25 (1986) 2877.
[15] V.G. Albano, S. Bordoni, D. Braga, L. Busetto, A. Palazzi, V.
Zanotti, Angew. Chem. Int. Ed. Engl. 30 (1991) 847.
[17] (a) Cambridge Structural Database, Version 5.22, October 2001;
(b) Siemens SHELXTLPLUS Version 5.1 (WINDOWS NT version)
Structure Determination Package, Siemens Analytical X-Ray
Instruments Inc., Madison, WI, 1998;
[16a] R.F. Bryan, P.T. Green, J. Chem. Soc. A (1970) 3068
(c) L.J. Farrugia, J. Appl. Crystallogr. (1997) 565.