Synthesis, structure and reactivity of sulfur-rich [Fe(L1)(L2)('tpS4')] complexes with rigid [Fe('tpS4'] cores and σ-π co-ligands ('tpS4'2- = 1,2-bis(2-mercaptophenylthio)phenylene(2-); L1 L2 = CO, PR3, NO)

Article abstract of DOI:10.1002/ejic.200390058

Optimisation of synthesis and purification steps has made the new ligand 'tpS₄^2- available in preparative amounts. Treatment of FeC1₂.4H₂O with 'tpS₄-Li₂ or 'tpS₄'-Na₂ yielded [Fe('tpS₄')] (1), which in the solid state and in the absence of co-ligands probably trimerises to give paramagnetic [Fe('tpS₄')]₃. The [Fe('tpS₄')] fragment displays helical coordination of the 'tpS₄'² -ligand and binds σ-π ligands such as CO, NO and phosphanes to give diamagnetic 18-valence-electron complexes of general formula [Fe(L¹)(L²) ('tpS₄')]. The cis-dicarbonyl complex [Fe(CO)₂('tpS₄')] (2) is labile and readily dissociates CO to give dinuclear [Fe(CO)('tpS₄')]₂ (3). Simultaneous coordination of CO and phosphanes yielded [Fe(CO)(PR₃)('tpS₄')] with R = Me (4), Et (5), Pr (6) and Bu (7), but it proved impossible to obtain analogous complexes with bulky PPh₃ or PCy₃ ligands. Bis(phosphane) complexes could be obtained only with PMe₃ and the bidentate dppe, which yielded [Fe(PMe₃)₂('tpS₄')] (8) and [Fe(dppe)('tpS₄')] (11). Alkylphosphanes with longer alkyl substituents, such as PnPr₃ and PnBu₃, gave the labile derivatives [Fe(PR₃)₂-('tpS₄')] with R = nPr (9) and nBu (10). Complexes 9 and 10 reversibly dissociate one PR3 ligand, yielding diamagnetic [Fe(PR₃)('tpS₄')] fragments. These findings explain the decisive and hitherto inexplicable influence of PPr₃ and PBu₃ ligands upon the stabilisation of N2H2 in the diazene complexes [μ-N₂H₂{Fe(PR₃) ('tpS₄')}₂] with R = Pr, Bu. Treatment of [Fe('tpS₄')] (1) or [Fe(CO)('tpS₄')]₂ (3) with NO or NO⁺ yielded [Fe(NO)₂('tpS₄')] (12). The molecular structures of 3, 4, 7 and 8 were determined by X-ray structure analysis. Spectroscopic and structural results indicate that the differences in reactivity between [Fe(L¹)(L²)('tpS₄')] and homologous [Fe(L¹)(L²) ('S₄')] complexes can be traced back to subtle electronic and structural effects. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).

Full text of DOI:10.1002/ejic.200390058

FULL PAPER
Synthesis, Structure and Reactivity of Sulfur-Rich [Fe(L1)(L2)(‘tpS4’)]
Complexes with Rigid [Fe(‘tpS4’] Cores and σ؊π Co-Ligands (‘tpS4’2؊
؍
1,2-Bis(2-mercaptophenylthio)phenylene(2؊); L1, L2 ؍ CO, PR3, NO)[‡]
Dieter Sellmann,*[a] David C. F. Blum,[a] Frank W. Heinemann,[a] and Jörg Sutter[a]
Dedicated to Professor Gottfried Huttner on the occasion of his 65th birthday
Keywords: Helical structures / Iron / S ligands
Optimisation of synthesis and purification steps has made the
(11). Alkylphosphanes with longer alkyl substituents, such as
new ligand ‘tpS4’2− available in preparative amounts. Treat- PnPr3 and PnBu3, gave the labile derivatives [Fe(PR3)2-
ment of FeCl2·4H2O with ‘tpS4’-Li2 or ‘tpS4’-Na2 yielded
[Fe(‘tpS4’)] (1), which in the solid state and in the absence of
(‘tpS4’)] with R = nPr (9) and nBu (10). Complexes 9 and 10
reversibly dissociate one PR3 ligand, yielding diamagnetic
co-ligands probably trimerises to give paramagnetic [Fe(PR3)(‘tpS4’)] fragments. These findings explain the de-
[Fe(‘tpS4’)]3. The [Fe(‘tpS4’)] fragment displays helical coor-
dination of the ‘tpS4’2− ligand and binds σ−π ligands such as
CO, NO and phosphanes to give diamagnetic 18-valence-
electron complexes of general formula [Fe(L1)(L2)(‘tpS4’)].
The cis-dicarbonyl complex [Fe(CO)2(‘tpS4’)] (2) is labile and
readily dissociates CO to give dinuclear [Fe(CO)(‘tpS4’)]2 (3).
Simultaneous coordination of CO and phosphanes yielded
[Fe(CO)(PR3)(‘tpS4’)] with R = Me (4), Et (5), Pr (6) and Bu
(7), but it proved impossible to obtain analogous complexes
with bulky PPh3 or PCy3 ligands. Bis(phosphane) complexes
could be obtained only with PMe3 and the bidentate dppe,
which yielded [Fe(PMe3)2(‘tpS4’)] (8) and [Fe(dppe)(‘tpS4’)]
cisive and hitherto inexplicable influence of PPr3 and PBu3
ligands upon the stabilisation of N2H2 in the diazene com-
plexes [µ-N2H2{Fe(PR3)(‘tpS4’)}2] with R = Pr, Bu. Treatment
of [Fe(‘tpS4’)] (1) or [Fe(CO)(‘tpS4’)]2 (3) with NO or NO+
yielded [Fe(NO)2(‘tpS4’)] (12). The molecular structures of 3,
4, 7 and 8 were determined by X-ray structure analysis.
Spectroscopic and structural results indicate that the differ-
ences in reactivity between [Fe(L1)(L2)(‘tpS4’)] and homolog-
ous [Fe(L1)(L2)(‘S4’)] complexes can be traced back to subtle
electronic and structural effects.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2003)
Introduction
ligands, under photolytic and/or strongly reducing reaction
conditions.[4] These findings and the well-known fact that
The goal of modelling and understanding the activation steric constraints exerted by ligands can have a marked in-
and turnover of small molecules at the metal/sulfur sites fluence upon the reactivity of otherwise identical complexes
of nitrogenases and hydrogenases accounts for much of the prompted us to synthesise ‘tpS4’-H2 ϭ 1,2-bis(2-mercapto-
interest in low-molecular-weight iron complexes with sul- phenylthio)phenylene (Scheme 1).[5]
fur-dominated coordination spheres that are able to bind
molecules relevant to enzyme activity.[1,2] In the search for
such complexes we have found that iron complexes with the
[Fe(‘S4’)] fragment (Scheme 1) are capable in particular of
binding CO, NO, N2H2, N2H4 and NH3, though not yet
N2.[3] It was also found that the ‘S4’2Ϫ ligand in the re-
sulting [Fe(‘S4’)] complexes exhibits a pronounced tendency
to release the C2H4 bridge, yielding 1,2-benzenedithiolate
[‡]
Transition Metal Complexes with Sulfur Ligands, 156. Part
155: Ref.[6]
[a]
Institut für Anorganische Chemie der Universität Erlangen-
Nürnberg,
Egerlandstraße 1, 91058 Erlangen, Germany
Fax: (internat.) ϩ 49-9131/852-7367
Scheme 1. Ligands and iron complex fragments with S4 donor
atom sets
E-mail: sellmann@anorganik.chemie.uni-erlangen.de
418
 2003 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim 1434Ϫ1948/03/0203Ϫ0418 $ 20.00ϩ.50/0 Eur. J. Inorg. Chem. 2003, 418Ϫ426

Synthesis, Structure and Reactivity of Sulfur-Rich [Fe(L1)(L2)(‘tpS4’)] Complexes
FULL PAPER
The ‘tpS4’2Ϫ anion is analogous to the ‘S4’2Ϫ anion, but H2 or ‘tpS4’-Li2 were obtained only in 100 mg amounts and
has a rigid o-phenylene group in place of the flexible C2H4 yields that rarely exceeded 20%.[6]
bridge and exclusively aromatic CϪS bonds, which are sig-
nificantly more stable towards CϪS cleavage.
In optimisation of the reaction conditions we have now
found that the steps A and B of Scheme 1 can be scaled up
In our recent first paper on [Fe(‘tpS4’)] complexes we re- and improved such that the intermediates ‘tpS2(NO2)2’ and
ported the diazene complexes [µ-N2H2{Fe(PR3)(‘tpS4’)}2] ‘tpS2(NH2)2’ are obtained in nearly quantitative yields. The
with R ϭ Pr, Bu.[6] A strange and previously inexplicable steps leading to ‘tpS4’-H2 can also be scaled up, and the
result was that these complexes were accessible only with resulting crude product is obtained in a form that directly
PPr3 and PBu3, but not with smaller or larger phosphanes gives white ‘tpS4’-Na2 in yields of ca. 70% and in gram
such as PMe3 or PPh3. Another characteristic feature of amounts upon treatment with NaOH. The procedure de-
these diazene complexes is their tendency to form hydrogen- scribed here (cf. Exp. Sect.) now makes ‘tpS4’-H2 readily
bridge diastereomers, and [µ-N2H2{Fe(PPr3)(‘tpS4’)}2] is available in preparative amounts for the synthesis of metal
the first example for which these diastereomers have been complexes.
characterised by X-ray structure analysis.
In this paper we report an optimised synthesis of ‘tpS4’-
Syntheses of [Fe(‘tpS4’)] Complexes
H2 and give an account of the general reactivity of
Scheme 3 summarises the syntheses of [Fe(‘tpS4’] com-
[Fe(‘tpS4’)] complex fragments with CO and phosphanes, plexes.
emphasizing the similarities as well as the differences be-
Coordination of anionic ‘tpS4’2Ϫ to FeII centres was read-
tween [Fe(‘S4’)] and [Fe(‘tpS4’)] complexes.
ily achieved by treating methanolic solutions of ‘tpS4’-Li2
(or ‘tpS4’-Na2) with FeCl2·4H2O. Light brown [Fe(‘tpS4’)]
(1) was obtained. This is soluble in coordinating solvents
such as THF or MeOH, but also in noncoordinating
CH2Cl2. In this regard, [Fe(‘tpS4’)] (1) differs remarkably
from tetranuclear [Fe(‘S4’)]4, which is practically insoluble
in all common organic solvents.[7] This solubility in THF,
MeOH and CH2Cl2 made [Fe(‘tpS4’)] (1) the best-suited
precursor for [Fe(L1)(L2)(‘tpS4’)] complexes.
The nuclearity of [Fe(‘tpS4’)] (1) remained undetermined.
FD mass spectra of 1 showed peaks at m/z ϭ 412, 824 and
1236, assignable to mono-, di- and trinuclear [Fe(‘tpS4’)]
species. The mass peak at m/z ϭ 1236 is compatible with
the assumption that in the solid state and in the absence of
co-ligands, [Fe(‘tpS4’)] (1) trimerises through thiolate
bridges in such a way that coordinatively saturated hexaco-
ordinate iron centres result. All X-ray structure determina-
tions of [Fe(L1)(L2)(‘tpS4’)] complexes established a helical
coordination of ‘tpS4’2Ϫ to the Fe centre (vide infra). Such
a coordination can also be assumed for [Fe(‘tpS4’)] (1), the
fifth and sixth coordination sites of which may be occupied
by solvent molecules in solution. In the solid state, complex
1 is paramagnetic and exhibits µeff ϭ 3.13 µB at room tem-
perature.
Results and Discussion
Optimisation of the Synthesis of ‘tpS4’-H2
The synthesis of ‘tpS4’-H2 is a multistep procedure com-
prising aromatic substitution, reduction, diazotisation and
diazonium salt substitution reactions, as shown in
Scheme 2.[5]
Treatment of 1 in THF solution with an excess of CO
yielded the cis-dicarbonyl complex [Fe(CO)2(‘tpS4’)] (2), as
indicated by two ν(CO) bands at 2047 and 2004 cmϪ1 in
the IR spectrum. In stark contrast to the analogous
[Fe(CO)2(‘S4’)],[8] which is stable in solution and in the solid
state, [Fe(CO)2(‘tpS4’)] (2) is highly labile and could not be
Scheme 2. Synthesis of crude ‘tpS4’-H2: (A) ϩ 2 NaOMe, MeOH,
12 h reflux; (B) Zn, NH4Cl, THF, 3 h reflux; (C) (a) H2SO4,
NaNO2, H2O, 0 °C; (b) ϩ KSC(S)OEt, H2O, 85 °C; (c) ϩ KOH,
EtOH, 19 h reflux; (d) ϩ HCl, H2O
Polyfunctional species are involved in all these steps, and isolated in the solid state. Attempts to separate 2 from solu-
the final crude product was usually heavily contaminated tion always yielded red-brown powders with IR spectra ex-
by side-products. Removal of these side-products had previ- hibiting strong ν(CO) bands at 1979 cmϪ1, indicating that
ously been achievable only in a very laborious way that in- complex 2 had dissociated one CO ligand and that the re-
cluded treatment of the crude ‘tpS4’-H2 with LiOMe to give sulting complex fragments had dimerised to give [Fe(CO)-
crude ‘tpS4’-Li2, and the synthesis of the nickel complex (‘tpS4’)]2 (3).
[Ni(‘tpS4’)]2. Recrystallisation of this nickel complex was
This indication could be corroborated by independent ex-
the essential purification step. Acidolysis of [Ni(‘tpS4’)]2 fi- periments. Treatment of an MeOH solution of 1 with ex-
nally yielded pure ‘tpS4’-H2, which could be converted into actly 1 equiv. of CO directly gave [Fe(CO)(‘tpS4’)]2 (3).
pure ‘tpS4’-Li2 as a storable form. In the end, pure ‘tpS4’- Complex 3 is sparingly soluble in all common solvents and
Eur. J. Inorg. Chem. 2003, 418Ϫ426
419

D. Sellmann, D. C. F. Blum, F. W. Heinemann, J. Sutter
FULL PAPER
Scheme 3. Synthesis of [Fe(‘tpS4’)] complexes
precipitated from solution. Its dinuclear structure was es- the PR3 moiety for coordination of phosphanes to
tablished by X-ray crystallography. [Fe(‘tpS4’)] fragments became even more apparent with bis-
The dissociation of CO from [Fe(CO)2(‘tpS4’)] (2) is re- (phosphane) complexes [Fe(PR3)2(‘tpS4’)]. Isolable com-
versible. Treatment of an MeOH or THF suspension of 3 plexes could be obtained only with PMe3 and the chelating
with an excess of CO gave a clear solution of [Fe(CO)2- dppe. Treatment of 1 with an excess of PMe3 or equivalent
(‘tpS4’)] (2), from which 3 precipitated again when the at- amounts of dppe gave [Fe(PMe3)2(‘tpS4’)] (8) and
mosphere of CO was replaced by N2. These observations [Fe(dppe)(‘tpS4’)] (11), respectively, which could be com-
enabled us to conclude that an equilibrium exists between pletely characterised. Treatment of [Fe(‘tpS4’)] (1) with PPr3
2, 3 and CO. This is driven in the direction of 3 by that or PBu3, however, yielded very labile [Fe(PR3)2(‘tpS4’)] with
compound’s low solubility when the partial pressure of CO R ϭ Pr (9) or Bu (10), which could be identified only by
is decreased.
their molecular ions in their FD mass spectra and by 31P
One more possible reason for the labile bonding of CO NMR spectroscopy in solution in the presence of excess
in [Fe(CO)2(‘tpS4’)] (2) could be the electron density at the phosphane. Attempts to isolate 9 or 10 in the solid state
iron centre. Comparison of the ν(CO) bands (in KBr) of resulted in phosphane dissociation and products that gave
[Fe(CO)2(‘tpS4’)] and [Fe(CO)2(‘S4’)] (2048/2002 cmϪ1 vs. unsatisfactory elemental analyses. The lability of the bis-
2036/1992 cmϪ1) and [Fe(CO)(‘tpS4’)]2 and [Fe(CO)(‘S4’)]2 (phosphane) complexes [Fe(PR3)2(‘tpS4’)] 9 (Pr) and 10
(1979 vs. 1965 cmϪ1 [9]
)
shows that the iron centres have a (Bu), which prevents their isolation in the solid state, how-
lower electron density in the [Fe(‘tpS4’)] species than in ever, has considerable synthetic value and explains the hith-
[Fe(‘S4’)], disfavouring the bonding of the π-acceptor CO. erto unexplained decisive influence of the R substituents for
Dinuclear [Fe(CO)(‘tpS4’)]2 (3) could also be cleaved by trapping diazene, N2H2, from solution and the stabilisation
PMe3 to give mononuclear [Fe(CO)(PMe3)(‘tpS4’)] (4). of the diazene complexes [µ-N2H2{Fe(PR3)(‘tpS4’)}2] with
Complex 4 and the homologous compounds [Fe(CO)- R ϭ Pr, Bu.
(PR3)(‘tpS4’)] with R ϭ Et (5), Pr (6) and Bu (7) were sim-
As evidenced by the diamagnetism of complexes 4Ϫ8 or
ilarly accessible directly from [Fe(‘tpS4’)] (1) and equivalent 11, binding of σϪπ ligands to [Fe(‘tpS4’)] fragments pro-
amounts of CO and the corresponding PR3. The series of duces a low-spin state in the FeII centres. The NMR spectra
complexes 4Ϫ7 revealed another difference between and chemical behaviour of 9 and 10, on the other hand,
[Fe(‘tpS4’)] and [Fe(‘S4’)] complexes. While [Fe(CO)- indicate that their lability is due to an equilibrium accord-
(PR3)(‘S4’)] species could be obtained with practically every ing to Equation (1).
phosphane, ranging from PMe3 over PBu3 up to bulky PPh3
and PCy3,[10] [Fe(CO)(PR3)(‘tpS4’)] complexes were access-
(1)
ible only with alkylphosphanes with relatively small cone
angles.[11] No evidence could be found for the coordination
of PPh3 or PCy3 to [Fe(CO)(‘tpS4’)] fragments.
The resulting five-coordinate [Fe(PR3)(‘tpS4’)] fragment
As judged by their NMR spectra, all complexes 4Ϫ7 are has a vacant coordination site and a low-spin (diamagnetic)
diamagnetic. They each show a characteristic ν(CO) band FeII centre, both of which are necessary to enable the coor-
in the 1959Ϫ1955 cmϪ1 range. The influence of the size of dination and stabilisation of N2H2. (In molecular orbital
420
Eur. J. Inorg. Chem. 2003, 418Ϫ426

Synthesis, Structure and Reactivity of Sulfur-Rich [Fe(L1)(L2)(‘tpS4’)] Complexes
FULL PAPER
theory terms, the diamagnetism of [Fe(PR3)(‘tpS4’)] means [Fe(‘tpS4’)] complexes with σϪπ co-ligands obey the 18-val-
that no electrons occupy antibonding orbitals.) ence-electron rule and the other data are compatible with
In concluding experiments, the coordination of NO and the alternative structures I and II.
NOϩ to [Fe(‘tpS4’)] fragments was examined. The same
complex was formed in all cases, its elemental analysis and
spectroscopic data being compatible with the formula
[Fe(NO)2(‘tpS4’)] (12). In CH2Cl2 solution, complex 12
shows two strong ν(NO) bands at 1779 and 1750 cmϪ1
,
indicative of a cis-Fe(NO)2 entity. The strong tendency to-
wards the formation of 12 became evident from the various
reactions in which it was formed. For example, complex 12
was produced when [Fe(‘tpS4’)] (1) in CH2Cl2 was treated
with 2 equiv. of NO gas. The two ν(NO) bands of 12 be-
came visible in the IR spectrum of the solution even after
injection of only the first equivalent. Injection of the second
equivalent increased the ν(NO) band intensity. Likewise,
successive treatment of [Fe(CO)(‘tpS4’)]2 (3) in CH2Cl2 with
2 equiv. of NO gas instantaneously gave rise to the forma-
tion of [Fe(NO)2(‘tpS4’)] (12). No intermediates such as the
19-VE species [Fe(CO)(NO)(‘tpS4’)] or [Fe(NO)(‘tpS4’)]2
could be observed by IR spectroscopy. That 19-VE com-
plexes such as [Fe(CO)(NO)(‘tpS4’)], which may be ex-
pected to be labile, may occur can be concluded from the
fact that [Fe(CO)2(‘tpS4’)] was formed as the second prod-
uct in the reaction between [Fe(CO)(‘tpS4’)]2 (3) and NO
gas (Figure 1).
In formula I, the two [FeNO] groups are linear and one
sulfur donor atom of ‘tpS4’2Ϫ is decoordinated. In formula
II, the ‘tpS4’2Ϫ ligand stays tetradentate, but one NO ligand
acts as a 1eϪ donor, the other one as a 3eϪ donor, and both
types of NO possibly isomerise quickly as in, for example,
[Ru(NO)2Cl(PPh3)2]ϩ.[12]
In order to examine the stability of [Fe(‘tpS4’)] fragments
towards photolysis, solutions of [Fe(CO)(‘tpS4’)]2 (3), [Fe(P-
Me3)2(‘tpS4’)] (8) and [Fe(CO)(PMe3)(‘tpS4’)] (4) were UV-
irradiated for prolonged periods of time. The CO ligands of
3 and 4 dissociated, but in no case could decomposition of
Figure 1. ν(CO)/ν(NO) region of the reaction solution (CH2Cl2)
when [Fe(CO)(‘tpS4’)]2 (3) is treated with 2 equiv. of NO gas {ϫ ؍
[Fe(CO)2(‘tpS4’)] (2), o ؍ [Fe(NO)2(‘tpS4’)] (12)}
The formation of [Fe(CO)2(‘tpS4’)] can be explained by
CO dissociation and transfer reactions between the labile
[Fe(CO)(NO)(‘tpS4’)] and dinuclear 3. Treatment of 1 or 3
with NOBF4 also yielded [Fe(NO)2(‘tpS4’)]. No other nitro-
syl complexes were observed, and the reducing agent neces-
sary for the NOϩ Ǟ NO conversion was not identified.
1
The H NMR spectrum of 12 shows only a multiplet for
the aromatic protons of the [Fe(‘tpS4’)] fragment and indic-
ates diamagnetism of 12, but is inconclusive in any other
respect. The insufficient solubility of 12 prevented the re-
cording of 13C NMR spectra. The FD mass spectra showed
a minor peak for the molecular ion at m/z ϭ 472 and strong
peaks at m/z ϭ 442 as well as at 412, 824 and 1236, assign-
able to [Fe(NO)(‘tpS4’)] and [Fe(‘tpS4’)]x species with x ϭ
Figure 2. Molecular structures of a) [Fe(CO)(‘tpS4’)]2·MeOH
(3·MeOH), b) [Fe(CO)(PMe3)(‘tpS4’)] (4), c) [Fe(CO)(PBu3)(‘tpS4’)]
(7) and d) [Fe(PMe3)2(‘tpS4’)] (8) (H atoms and solvent molecules
1, 2 and 3. The diamagnetism of 12, the fact that all omitted)
Eur. J. Inorg. Chem. 2003, 418Ϫ426
421

D. Sellmann, D. C. F. Blum, F. W. Heinemann, J. Sutter
FULL PAPER
Table 1. Selected distances [pm] and angles [°] of [Fe(CO)(‘tpS4’)]2·MeOH (3·MeOH), [Fe(CO)(PMe3)(‘tpS4’)] (4), [Fe(CO)(PBu3)(‘tpS4’)]
(7) and [Fe(PMe3)2(‘tpS4’)] (8)
3·MeOH
4
7
8
Fe1ϪS1
Fe1ϪS2
Fe1ϪS3
Fe1ϪS4
Fe1ϪS4A
Fe1ϪC1
C1ϪO1
Fe1ϪFe1A
S1ϪFe1ϪS4
S2ϪFe1ϪS4A
S3ϪFe1ϪC1
S1ϪFe1ϪS4A
S1ϪFe1ϪC1
C1ϪFe1ϪS4A
Fe1ϪC1ϪO1
228.9(3)
224.1(3)
228.5(3)
228.5(3)
234.5(3)
176.4(9)
113.2(9)
341.0(2)
174.6(2)
174.0(2)
174.7(4)
93.6(2)
Fe1ϪS1
Fe1ϪS2
Fe1ϪS3
Fe1ϪS4
Fe1ϪP1
Fe1ϪC1
C1ϪO1
230.9(2)
227.6(3)
226.2(3)
229.8(3)
225.0(3)
177(1)
230.5(2)
225.7(2)
227.1(2)
231.0(2)
225.2(2)
175.2(6)
114.8(7)
Fe1ϪS1
Fe1ϪS2
Fe1ϪS3
Fe1ϪS4
Fe1ϪP1
Fe1ϪP2
231.7(2)
224.9(2)
224.8(2)
230.3(2)
225.1(2)
224.7(2)
113(2)
S1ϪFe1ϪS4
S2ϪFe1ϪP1
S3ϪFe1ϪC1
S1ϪFe1ϪP1
S1ϪFe1ϪC1
P1ϪFe1ϪC1
Fe1ϪC1ϪO1
175.5(2)
176.0(1)
178.5(4)
89.6(1)
90.4(3)
89.6(4)
177(1)
173.71(7)
177.38(6)
177.8(2)
91.54(6)
90.1(2)
89.2(2)
178.1(5)
S1ϪFe1ϪS4
S2ϪFe1ϪP1
S3ϪFe1ϪP2
S1ϪFe1ϪP1
S1ϪFe1ϪP2
P1ϪFe1ϪP2
174.94(9)
173.81(8)
174.71(8)
87.60(7)
95.56(8)
93.15(8)
87.9(4)
87.1(3)
172(2)
the [Fe(‘tpS4’)] fragments by CϪS cleavage reactions be ob-
served.
In [Fe(L1)(L2)(‘S4’)] complexes, the FeϪS(thioether) and
FeϪS(thiolate) distances tend to be equivalent, frequently
identical.[3] In [Fe(L1)(L2)(‘tpS4’)] complexes, however, the
FeϪS(thioether) distances are usually distinctly shorter
than the FeϪS(thiolate) distances. This is certainly not due
to a better donor capability of the thioether donors but
rather results from the bite angle of the o-phenylenebis(thi-
oether) entity, which is smaller than that of the [SC2H4S]
bridge in the ‘S4’2Ϫ ligand. Another major difference is the
conformation of the central five-membered chelate ring in
[Fe(‘S4’)] and [Fe(‘tpS4’)] fragments. Figure 3 shows that
this [FeS(2)S(3)] ring adopts a puckered (envelope) con-
formation in [Fe(‘S4’)], whereas the chelate ring is virtually
planar (coplanar to within 20 pm with the benzene ring)
in [Fe(‘tpS4’)].
X-ray Structure Analyses
The molecular structures of [Fe(CO)(‘tpS4’)]2·MeOH
(3·MeOH),
[Fe(CO)(PMe3)(‘tpS4’)]
(4),
[Fe(CO)(P-
Bu3)(‘tpS4’)] (7) and [Fe(PMe3)2(‘tpS4’)] (8) were deter-
mined by X-ray crystallography and are shown in Figure 2.
Table 1 lists selected distances and angles.
All complexes exhibit six-coordinate Fe centres and hel-
ical coordination of the ‘tpS4’2Ϫ ligands, resulting in chiral
[Fe(‘tpS4’)] fragments with trans-thiolate and cis-thioether
donors. Figure 1 shows the respective (R) enantiomers of 4,
7 and 8. In [Fe(CO)(‘tpS4’)]2 (3), two such homochiral (R)-
[Fe(‘tpS4’)] fragments are bridged through thiolate donors
to give C2-symmetrical 3. The structure of 3 is noteworthy
because it appears to be favoured in spite of the strikingly
different spatial filling of the coordination sphere and the
evident resulting steric strain. While the top ‘‘half’’ of 3 is
heavily overloaded, the bottom ‘‘half’’ is occupied only by
the two CO ligands. The electronic inequivalence of the thi-
olate donors in C1-symmetrical [Fe(CO)(‘tpS4’)] fragments
is a potential factor in favour of this type of structure. A
precedent has been observed with [Fe(CO)(‘S4’)][9] and, ac-
cording to the classification introduced then, the structure
shown in Figure 1 (part a) is the αα-Z(RR) isomer of 3.
The bond lengths of all four compounds lie in the ranges
characteristic for this type of diamagnetic FeII com-
plexes.[10] For example, terminal FeϪS distances are found
in the 224Ϫ230 pm range, and FeϪSϪFe bridging distances
can be elongated up to 234 pm, indicating the tendency of
dinuclear complexes to dissociate into mononuclear species.
As also observed for [Fe(‘S4’)] complexes, no marked trans
influence of such different donors as S(thiolate), CO or PR3
upon the respective trans bonds can be recognised in any of
the [Fe(‘tpS4’)] complexes. The following structural differ-
ences between [Fe(L1)(L2)(‘tpS4’)] and the corresponding
[Fe(L1)(L2)(‘S4’)] complexes are to be noted.
Figure 3. Comparison of the central five-membered [FeS2C2] rings
in a) [Fe(‘S4’)] and b) [Fe(‘tpS4’)] complexes
Thus, the small but significantly different reactivities of
[Fe(‘S4’)] and [Fe(‘tpS4’)] fragments with regard to the coor-
dination of co-ligands such as CO and phosphanes can be
traced back to slightly different electron densities at the Fe
centres [cf. the ν(CO) frequencies] as well as to the struc-
tural flexibility or rigidity of the central [FeS2C2] chelate
rings in these complexes.
Conclusion
Optimised synthesis and purification steps have now
made ‘tpS4’-H2 available in the preparative amounts needed
422
Eur. J. Inorg. Chem. 2003, 418Ϫ426

Synthesis, Structure and Reactivity of Sulfur-Rich [Fe(L1)(L2)(‘tpS4’)] Complexes
FULL PAPER
vacuo. Yield: 39.64 g (95%). The product was identified by 1H
NMR spectroscopy and mass spectrometry.
for thorough investigation of its coordination properties.
Comparison of the [Fe(L1)(L2)(‘tpS4’)] complexes described
in this work with the [Fe(L1)(L2)(‘S4’)] complexes obtained
in previous studies shows that [Fe(‘tpS4’)] and [Fe(‘S4’)]
complex fragments exhibit both close similarities and dis-
tinctive differences. While the similarities can be traced
‘tpS2(NH2)2’: Zinc powder (67.4 g, 1.031 mol) and NH4Cl (55.2 g,
1.031 mol) were added to a yellow suspension of ‘tpS2(NO2)2’
(39.64 g, 103.1 mmol) in THF (600 mL). The resulting grey suspen-
sion was heated to reflux for 3 h and filtered while hot. The solid
back to the identical coordination of FeII centres by two residue was thoroughly extracted with hot THF (400 mL). The fil-
trate and combined THF washing solutions were concentrated un-
der reduced pressure, yielding a colourless oily residue. This residue
was treated with hot EtOH (50 mL) to give a white powder, which
was separated, washed with EtOH (50 mL) and dried in vacuo.
Additional product precipitated from the combined EtOH filtrates
overnight. Yield: 32.79 g (98%). The product was identified by IR
trans-thiolate and two cis-thioether donors, the differences
result from a slightly lower electron density at the Fe centres
and the more rigid core structure of [Fe(‘tpS4’)] vs. [Fe(‘S4’)]
fragments. These differences are illustrated by, for example,
the [Fe(CO)(PR3)(‘tpS4’)] and [Fe(CO)(PR3)(‘S4’)] com-
plexes. While the [Fe(CO)(‘tpS4’)] fragment binds only small
alkylphosphanes, the [Fe(CO)(‘S4’)] fragment can also co-
ordinate bulky phosphanes such as PPh3 and PCy3. The
lability of [Fe(PR3)2(‘tpS4’)] with R ϭ Pr (9), Bu (10), re-
sulting in the reversible dissociation of one PR3 ligand, ex-
plains the decisive influence of PPr3 and PBu3 ligands for
the stabilisation of N2H2 in the diazene complexes [µ-
N2H2{Fe(PR3)(‘tpS4’)}2] with R ϭ Pr, Bu. While PMe3
gives stable [Fe(PMe3)2(‘tpS4’)] (8) and PPh3 or PCy3 do
not coordinate at all to [Fe(‘tpS4’)] fragments, the medium-
sized phosphanes PPr3 and PBu3 in solution give rise to
1
and H NMR spectroscopy and mass spectrometry.
‘tpS4’-H2 (Crude Product): Whilst stirring, a white suspension of
powdered ‘tpS2(NH2)2’ (21.64 g, 66.7 mmol) in H2O (200 mL) was
cooled to 0 °C. In order to keep the suspension at 0 °C, ice (90 g)
was added. After addition of a solution of H2SO4 (15.9 g,
161.9 mmol) in H2O (100 mL), an aqueous solution of NaNO2
(9.67 g, 140.1 mmol, 100 mL) was added dropwise. The resulting
yellow orange suspension was stirred at 0 °C for another hour and
subsequently added dropwise to a hot solution (85 °C) of potas-
sium O-ethylxanthogenate (86.5 g, 539.9 mmol) in H2O (200 mL),
yielding a red-brown oil. The reaction mixture was stirred for an-
five-coordinate [Fe(PR3)(‘tpS4’)] species that are diamag- other 30 min at 85 °C, cooled to room temperature and extracted
with CH2Cl2 (600 mL). The combined CH2Cl2 extracts were dried
with Na2SO4 and filtered, and the solvents were evaporated to give
a dark red oil as residue. EtOH (250 mL) and powdered KOH
(42.9 g, 764.6 mmol) were added, and the resulting suspension was
heated to reflux for 19 h to give a dark red solution. EtOH was
removed in vacuo, the remaining orange-brown residue was dis-
solved in H2O (250 mL), and the resulting aqueous solution was
extracted with CH2Cl2 (300 mL) in a separating funnel. The aque-
ous solution was separated and acidified with concentrated hydro-
chloric acid to pH ϭ 0.5, whereupon a red oil separated. The oil/
water mixture was extracted several times with CH2Cl2 (400 mL),
the combined CH2Cl2 extracts were dried with Na2SO4 and filtered,
and the solvents were evaporated to yield an orange-red oily res-
idue, which was dried in vacuo for 12 h. Yield: 18.5 g (77%) of
crude product, which contained approximately 62% of ‘tpS4’-H2
netic and have a vacant site. Diamagnetism and a vacant
site are both necessary requirements for the binding and
stabilisation of unstable N2H2 to [Fe(PR3)(‘tpS4’)] frag-
ments. The previously inexplicable stabilisation effect of
PPr3 and PBu3 in the iron diazene complexes is thus in the
end due neither to pronounced electronic nor steric effects,
but to
a
simple dissociation equilibrium between
[Fe(PR3)2(‘tpS4’)], [Fe(PR3)(‘tpS4’)] and PR3.
Experimental Section
General Methods: Unless noted otherwise, all reactions and opera-
tions were carried out at room temperature under nitrogen by use
of standard Schlenk techniques. Solvents were dried and distilled
before use. As far as possible, reactions were monitored by IR or
NMR spectroscopy. Spectra were recorded with the following in-
struments: IR (KBr disks or CaF2 cuvettes, solvent bands were
compensated): PerkinϪElmer 16 PC FT-IR; NMR: Jeol FT-JNM-
GX 270, EX 270 and Lambda LA 400, with the protio solvent
signals used as a reference, chemical shifts are quoted on the δ scale
(downfield shifts are positive) relative to tetramethylsilane (1H,
13C{1H} NMR) or 85% H3PO4 (31P{1H} NMR). Spectra were re-
corded at 25 °C; MS: JEOL MSTATION 700 spectrometer; ele-
mental analyses: Carlo Erba EA 1106 and 1108 analyser. Magnetic
1
according to the H NMR spectrum in CD2Cl2.
‘tpS4’-Na2: A dark red solution of the crude product [12.33 g, con-
taining ca. 62% (21 mmol) of ‘tpS4’-H2] in THF (50 mL) was com-
bined with an MeOH solution (80 mL) of NaOMe (2.30 g,
42.6 mmol). Volatile components were removed, and the brown-red
residue was dried in vacuo for 12 h and subsequently suspended in
THF (200 mL). Stirring of the suspension for 1 h resulted in a
white solid, which was separated, washed with THF (120 mL) and
dried in vacuo for 12 h. Yield: 6.39 g (74%, referred to ‘tpS4’-H2
contained in the crude product). The product contained traces of
1
THF, which could not be removed by drying in vacuo for 48 h. H
moments were determined with a JohnsonϪMatthey susceptibility
[13]
balance. ‘tpS4’-Li2,[5] PMe3, PEt3, PnPr3 and PnBu3
were pre-
NMR ([D4]MeOH, 269.72 MHz): δ ϭ 7.52Ϫ7.40 (m, 2 H),
7.30Ϫ7.18 (m, 2 H), 7.14Ϫ7.03 (m, 2 H), 6.82Ϫ6.57 (m, 6 H,
C6H4), 3.70 (m, 4 H), 1.84 (m, 4 H, THF) ppm. 13C{1H} NMR
([D4]MeOH, 100.40 MHz): δ ϭ 149.25, 139.63, 137.98, 134.05,
132.91, 128.42, 126.82, 124.69, 120.90 [C (aryl)], 67.52, 25.16
(THF) ppm. IR (KBr): ν˜ ϭ 1565 m, 1437 s, 1422 s [ν(CϭC)], 739
cmϪ1 vs [δ(CϪH)].
pared as described in the literature, dppe was purchased from Ald-
rich.
‘tpS2(NO2)2’: o-C6H4(SH)2 (15.1 mL, 118.8 mmol) and 2-fluoro-
nitrobenzene (35.1 mL, 332.6 mmol) were added to a solution of
NaOMe (13.16 g, 243.6 mmol) in MeOH (400 mL). The solution
was heated to reflux for 12 h, in the course of which a bright yellow
precipitate formed. After the suspension had cooled to room tem-
[Fe(‘tpS4’)] (1): FeCl2·4H2O (68 mg, 0.34 mmol) was added to a
perature, the precipitate was separated, washed with MeOH light yellow solution of ‘tpS4’-Li2 (126 mg, 0.34 mmol) in MeOH
(80 mL), H2O (120 mL), and again MeOH (30 mL) and dried in (30 mL). After stirring for 1 h, the reaction mixture was filtered
Eur. J. Inorg. Chem. 2003, 418Ϫ426
423

D. Sellmann, D. C. F. Blum, F. W. Heinemann, J. Sutter
FULL PAPER
and concentrated to dryness. The resulting yellow-brown residue
vs [ν(CO)]. IR (THF): ν˜ ϭ 1955 cmϪ1 vs [ν(CO)]. MS (FD, THF,
was dried in vacuo overnight and redissolved in CH2Cl2 (25 mL) 56Fe): m/z: 558 [Fe(CO)(PEt3)(‘tpS4’)]ϩ, 412 [Fe(‘tpS4’)]ϩ, 824
to remove LiCl. The resulting suspension was filtered and the
brown-red filtrate was evaporated to dryness. Stirring of the residue
with Et2O (20 mL) yielded brown microcrystals, which were separ-
ated, washed with Et2O (30 mL) and dried in vacuo. Yield: 102 mg
(1·0.25 CH2Cl2) (69%). IR (KBr): ν˜ ϭ 1566 m [ν(CϭC)], 746 cmϪ1
vs [δ(CϪH)]. MS (FD, THF, 56Fe): m/z: 412 [Fe(‘tpS4’)]ϩ, 824
[Fe(‘tpS4’)]2ϩ, 1236 [Fe(‘tpS4’)]3ϩ. C25H27FeOPS4 (558.57): calcd.
C 53.76, H 4.87, S 22.96; found C 53.62, H 5.14, S 22.93.
[Fe(CO)(PnPr3)(‘tpS4’)] (6): FeCl2·4H2O (157 mg, 0.79 mmol) and
PnPr3 (158 µL, 0.79 mmol) were added to a light yellow solution
of ‘tpS4’-Li2 (292 mg, 0.79 mmol) in THF (25 mL) and MeOH
(10 mL). CO gas (17.7 mL, 0.79 mmol) was injected by syringe into
the olive-green mixture, which turned into a dark-red solution
within 3 h. The solution was filtered, reduced in volume to 5 mL
and combined with MeOH (20 mL). Grey microcrystals formed,
and were separated, washed with MeOH (30 mL) and Et2O
(20 mL) and dried in vacuo. Yield: 314 mg (6·MeOH) (63%). 1H
NMR (CD2Cl2, 269.72 MHz): δ ϭ 8.08Ϫ7.69 (m, 4 H), 7.46Ϫ7.23
(m, 4 H), 7.02Ϫ6.79 (m, 4 H, C6H4), 1.88Ϫ1.42 (m, 12 H), 1.01 [t,
9 H, P(C3H7)3] ppm. 13C{1H} NMR (CD2Cl2, 100.40 MHz): δ ϭ
217.78 (d, JPC ϭ 30.2 Hz, CO), 158.01, 156.81 (d, JPC ϭ 7.3 Hz),
ϩ
ϩ
[Fe(‘tpS4’)]2
, 1236 [Fe(‘tpS4’)]3 ; µeff (295 K) ϭ 3.13 µB.
C18.25H12.5Cl0.5FeS4 (1·0.25CH2Cl2) (433.63): calcd. C 50.55, H
2.91, S 29.58; found C 50.52, H 3.06, S 29.68.
[Fe(CO)(‘tpS4’)]2 (3): FeCl2·4H2O (126 mg, 0.64 mmol) was added
to a light yellow solution of ‘tpS4’-Li2 (236 mg, 0.64 mmol) in
MeOH (50 mL). The orange-red reaction mixture was stirred for
1 h and filtered, and CO gas (14.3 mL, 0.64 mmol) was injected
into the filtrate by syringe. A brick-red precipitate formed; after
6 h this was separated, washed with MeOH (45 mL) and Et2O
(30 mL), and dried in vacuo. Yield: 234 mg (3·MeOH) (81%). IR 139.15, 138.98, 138.84 (d, JPC ϭ 0.9 Hz), 137.02, 136.43, 132.24,
(KBr): ν˜ ϭ 1979 cmϪ1 vs [ν(CO)]. MS (FD, THF, 56Fe): m/z: 412 131.98, 131.13, 130.91, 130.64, 130.59, 130.22, 129.70, 129.62,
[Fe(‘tpS4’)]ϩ, 824 [Fe(‘tpS4’)]2ϩ, 1236 [Fe(‘tpS4’)]3ϩ. C39H28Fe2O3S8 129.48, 122.49 [C (aryl)], 27.98 (d, JPC ϭ 23.8 Hz), 17.52 (d, JPC ϭ
(3·MeOH) (912.87): calcd. C 51.32, H 3.09, S 28.10; found C 51.13,
H 3.08, S 28.13. Because of the low solubility of 3, no NMR spec-
tra could be recorded.
2.0 Hz), 15.99 [d, JPC ϭ 12.9 Hz, P(C3H7)3] ppm. 31P{1H} NMR
(CD2Cl2, 161.70 MHz): δ ϭ 35.88 (s, PnPr3) ppm. IR (KBr): ν˜ ϭ
1957, 1953 cmϪ1 vs [ν(CO)]. IR (THF): ν˜ ϭ 1955 cmϪ1 vs [ν(CO)].
MS (FD, THF, 56Fe): m/z: 600 [Fe(CO)(PnPr3)(‘tpS4’)]ϩ,
[Fe(CO)(PMe3)(‘tpS4’)] (4): FeCl2·4H2O (59 mg, 0.30 mmol) and
PMe3 (59 µL, 0.30 mmol) were added to a light yellow solution of
‘tpS4’-Li2 (110 mg, 0.30 mmol) in THF (20 mL) and MeOH
(10 mL) to give an olive-green reaction mixture, into which CO
gas (16.8 mL, 0.30 mmol) was injected by syringe. A red solution
resulted, and this was filtered, reduced in volume to 2 mL and com-
ϩ
ϩ
412 [Fe(‘tpS4’)]ϩ, 824 [Fe(‘tpS4’)]2
,
1236 [Fe(‘tpS4’)]3 .
C29H37FeO2PS4 (6·MeOH) (632.69): calcd. C 55.05, H 5.89, S
20.27; found C 54.56, H 5.78, S 20.57.
[Fe(CO)(PnBu3)(‘tpS4’)] (7): FeCl2·4H2O (257 mg, 1.29 mmol) and
PnBu3 (257 µL, 1.29 mmol) were added to a light yellow solution
bined with MeOH (20 mL). A light green precipitate formed and of ‘tpS4’-Li2 (479 mg, 1.29 mmol) in THF (45 mL) and MeOH
was separated, washed with MeOH (20 mL) and Et2O (20 mL) and
dried in vacuo. Yield: 80 mg (4·0.5MeOH) (51%). 1H NMR
(CD2Cl2, 269.72 MHz): δ ϭ 8.25Ϫ6.70 (m, 12 H, C6H4), 1.44 (br.
(20 mL). CO gas (28.9 mL, 1.29 mmol) was injected into the re-
sulting olive-green solution by syringe. The reaction mixture was
stirred for 3 h and filtered, and the dark red filtrate was reduced in
s, 9 H, CH3) ppm. 13C{1H} NMR (CD2Cl2, 100.40 MHz): δ ϭ volume to 5 mL. After addition of MeOH (20 mL), grey-brown
217.25 (d, JPC ϭ 31.1 Hz, CO), 157.59, 156.44 (d, JPC ϭ 2.7 Hz),
microcrystals precipitated and were separated, washed with MeOH
139.13, 138.97, 137.57, 136.01, 132.23, 132.11, 131.18, 131.04, (45 mL) and Et2O (20 mL) and dried in vacuo. Yield: 482 mg
1
130.74, 130.69, 130.33, 129.78, 129.67, 129.40, 122.60, 122.53 [C
(aryl)], 16.44 (d, JPC ϭ 29.2 Hz, CH3) ppm. 31P{1H} NMR
(58%). H NMR (CD2Cl2, 269.72 MHz): δ ϭ 8.08Ϫ7.68 (m, 4 H),
7.47Ϫ7.20 (m, 4 H), 7.03Ϫ6.79 (m, 4 H, C6H4), 1.89Ϫ1.31 (m, 18
(CD2Cl2, 161.70 MHz): δ ϭ 21.50 (s, PMe3) ppm. IR (KBr): ν˜ ϭ H), 0.94 [t, 9 H, P(C4H9)3] ppm. 13C{1H} NMR (CD2Cl2,
1966, 1957 vs [ν(CO)], 952 cmϪ1 m [δ(PCH)]. IR (THF): ν˜ ϭ 1959
cmϪ1 vs [ν(CO)]. MS (FD, THF, 56Fe): m/z: 516 (d, JPC ϭ 7.5 Hz), 138.87, 138.75, 138.56, 136.74, 136.17, 131.93,
[Fe(CO)(PMe3)(‘tpS4’)]ϩ, 412 [Fe(‘tpS4’)]ϩ, 824 [Fe(‘tpS4’)]2ϩ, 1236
131.67, 130.78, 130.58, 130.29, 130.26, 129.89, 129.40, 129.29,
[Fe(‘tpS4’)]3ϩ. C22.5H23FeO1.5PS4 (4·0.5MeOH) (532.51): calcd. C 129.13, 122.14 [C (aryl)], 25.45 (d, JPC ϭ 3.7 Hz), 25.14 (d, JPC
67.83 MHz): δ ϭ 217.49 (d, JPC ϭ 30.5 Hz, CO), 157.78, 156.59
ϭ
50.75, H 4.35, S 24.09; found C 50.76, H 4.43, S 23.92.
23.6 Hz), 24.38 (d, JPC ϭ 12.4 Hz), 13.51 [s, P(C4H9)3] ppm.
31P{1H} NMR (CD2Cl2, 161.70 MHz): δ ϭ 34.80 (s, PnBu3) ppm.
IR (KBr): ν˜ ϭ 1956, 1953 cmϪ1 vs [ν(CO)]. IR (THF): ν˜ ϭ 1955
[Fe(CO)(PEt3)(‘tpS4’)] (5): FeCl2·4H2O (99 mg, 0.50 mmol) and
PEt3 (158 µL, 0.50 mmol) were added to a light yellow solution of
‘tpS4’-Na2 (200 mg, 0.50 mmol) in MeOH (10 mL) and THF
(20 mL). An olive-green solution resulted, into which CO gas
(11.2 mL, 0.50 mmol) was injected by syringe. The reaction mixture
was stirred for 2.5 h and filtered, and the dark red filtrate was re-
cmϪ1 vs [ν(CO)]. MS (FD, THF, 56Fe): m/z
ϭ
642
ϩ
[Fe(CO)(PnBu3)(‘tpS4’)]ϩ, 412 [Fe(‘tpS4’)]ϩ, 824 [Fe(‘tpS4’)]2
,
1236 [Fe(‘tpS4’)]3ϩ. C31H39FeOPS4 (642.73): calcd. C 57.93, H 6.12,
S 19.96; found C 57.90, H 6.34, S 19.84.
duced in volume to 2 mL. Upon addition of MeOH (20 mL), light [Fe(PMe3)2(‘tpS4’)] (8): FeCl2·4H2O (62 mg, 0.31 mmol) and PMe3
brown microcrystals formed, and were separated, washed with (0.65 mL, 6.21 mmol) were added to a light yellow solution of
MeOH (20 mL) and dried in vacuo. Yield: 53 mg (19%). H NMR ‘tpS4’-Li2 (115 mg, 0.31 mmol) in THF (30 mL) and MeOH
1
(CD2Cl2, 269.72 MHz): δ ϭ 8.07Ϫ7.73 (m, 4 H), 7.44Ϫ7.25 (m, 4
H), 7.00Ϫ6.81 (m, 4 H, C6H4), 1.96Ϫ1.63 (m, 6 H), 1.28Ϫ1.10 [m,
(5 mL). The resulting dark green solution was stirred for 17 h, fil-
tered and reduced in volume nearly to dryness. Upon addition of
9 H, P(C2H5)3] ppm. 13C{1H} NMR (CD2Cl2, 67.83 MHz): δ ϭ MeOH (20 mL), olive-green microcrystals precipitated, and were
217.79 (d, JPC ϭ 30.1 Hz, CO), 157.73, 156.83 (d, JPC ϭ 7.3 Hz),
139.11 (d, JPC ϭ 11.9 Hz), 137.11, 136.29, 132.27, 131.97, 131.07, dried in vacuo. Yield: 108 mg (62%). 1H NMR (CD2Cl2,
130.90, 130.66, 130.63, 130.19, 129.74, 129.64, 129.42, 122.48 [C 269.72 MHz): δ ϭ 7.99Ϫ7.93 (m, 2 H), 7.86Ϫ7.81 (vdd, 2 H),
(aryl), partly superimposed], 17.83 (d, JPC ϭ 24.9 Hz), 7.99 [d, 7.31Ϫ7.24 (m, 4 H), 6.88Ϫ6.77 (m, 4 H, C6H4), 1.38 (vt, 18 H,
JPC
4.7 Hz, P(C2H5)3] ppm. 31P{1H} NMR (CD2Cl2, P(CH3)3] ppm. 13C{1H} NMR (CD2Cl2, 100.40 MHz): δ ϭ 160.17,
161.70 MHz): δ ϭ 42.56 (s, PEt3) ppm. IR (KBr): ν˜ ϭ 1951 cmϪ1 140.85, 138.74, 131.22, 130.82, 129.87, 129.65, 128.58, 121.49 [C
separated, washed with MeOH (30 mL) and Et2O (12 mL) and
ϭ
424
Eur. J. Inorg. Chem. 2003, 418Ϫ426

Synthesis, Structure and Reactivity of Sulfur-Rich [Fe(L1)(L2)(‘tpS4’)] Complexes
(aryl)], 18.14 (t, JPC ϭ 12.0 Hz, P(CH3)3] ppm. 31P{1H} NMR Li2 (183 mg, 0.49 mmol) in THF (20 mL) and MeOH (8 mL). The
FULL PAPER
(CD2Cl2, 161.70 MHz): δ ϭ 22.09 (s, PMe3) ppm. IR (KBr): ν˜ ϭ
resulting dark green solution was stirred for 90 min, filtered, re-
956, 944 cmϪ1 vs [δ(PCH)]. MS (FD, CH2Cl2, 56Fe): m/z: 564 duced in volume to 5 mL and combined with MeOH (30 mL). A
[Fe(PMe3)2(‘tpS4’)]ϩ, 412 [Fe(‘tpS4’)]ϩ, 824 [Fe(‘tpS4’)]2ϩ, 1236 light green precipitate formed, and this was separated, washed with
[Fe(‘tpS4’)]3ϩ. C24H30FeP2S4 (564.56): calcd. C 51.06, H 5.36, S
22.72; found C 50.51, H 5.64, S 22.96.
MeOH (30 mL) and Et2O (10 mL) and dried in vacuo. Yield:
274 mg (11·2MeOH) (63%). 1H NMR (CD2Cl2, 269.72 MHz): δ ϭ
8.15Ϫ7.97 (m, 6 H), 7.61Ϫ7.43 (m, 8 H), 7.34Ϫ7.23 (m, 2 H), 7.05
(vt, 4 H), 6.89Ϫ6.66 (m, 6 H), 6.59Ϫ6.43 (m, 4 H), 6.30 (vdt, 2 H,
C6H4, C6H5), 3.27Ϫ2.76 (m, 4 H, Ph2PC2H4PPh2) ppm. 13C{1H}
NMR (CD2Cl2, 100.40 MHz): δ ϭ 157.90 (t, JPC ϭ 4.1 Hz), 140.79
(t, JPC ϭ 6.0 Hz), 138.41, 134.33, 134.15, 134.13, 134.00, 133.97,
133.83, 133.36 (t, JPC ϭ 4.2 Hz), 131.70 (t, JPC ϭ 4.1 Hz), 131.24,
130.42, 130.17, 130.02, 129.70, 128.43 (t, JPC ϭ 3.6 Hz), 127.95,
126.50 (t, JPC ϭ 4.6 Hz), 121.10 (C6H4, C6H5, partly covered),
26.23 (t, JPC ϭ 21.0 Hz, Ph2PC2H4PPh2) ppm. 31P{1H} NMR
(CD2Cl2, 161.70 MHz): δ ϭ 74.01 (s, Ph2PC2H4PPh2) ppm. IR
(KBr): ν˜ ϭ 735, 695 cmϪ1 vs [δ(PCH)]. MS (FD, CH2Cl2, 56Fe):
m/z: 810 [Fe(dppe)(‘tpS4’)]3ϩ. C46H44FeO2P2S4 (11·2MeOH) (874.91):
calcd. C 63.15, H 5.07, S 14.66; found C 63.39, H 4.87, S 14.65.
[Fe(PnPr3)2(‘tpS4’)] (9): FeCl2·4H2O (17 mg, 0.08 mmol) and PnPr3
(0.17 mL, 0.8 mmol) were added to a light yellow solution of ‘tpS4’-
Li2 (31 mg, 0.08 mmol) in THF (6 mL) and MeOH (1 mL). The
resulting solution was stirred for 14 h and concentrated to dryness.
A dark green residue resulted, and was dried in vacuo for 20 min
and dissolved in CD2Cl2 (0.7 mL) to which a few drops of PnPr3
had been added, in order to record NMR spectra. 31P{1H} NMR
(CD2Cl2, 161.70 MHz): δ ϭ 29.1 (s, PnPr3), Ϫ33.4 (s, exc. PnPr3)
ppm. MS (FD, CH2Cl2, 56Fe): m/z: 732 [Fe(PnPr3)2(‘tpS4’)]ϩ, 412
[Fe(‘tpS4’)]ϩ, 824 [Fe(‘tpS4’)]2ϩ, 1236 [Fe(‘tpS4’)]3
.
ϩ
[Fe(PnBu3)2(‘tpS4’)] (10): FeCl2·4H2O (23 mg, 0.12 mmol) and
PnBu3 (0.23 mL, 1.2 mmol) were added to a light yellow solution
of ‘tpS4’-Li2 (43 mg, 0.12 mmol) in THF (10 mL) and MeOH
(2 mL). The resulting solution was stirred for 15 h and concen-
trated to dryness. The resulting dark green residue was dried in
vacuo for 15 min and dissolved in CD2Cl2 (0.7 mL) to which a few
drops of PnBu3 had been added in order to record NMR spectra.
31P{1H} NMR (CD2Cl2, 161.70 MHz): δ ϭ 30.3 (s, PnBu3), Ϫ30.2
(s, exc. PnBu3) ppm. MS (FD, CH2Cl2, 56Fe): m/z: 816
[Fe(NO)2(‘tpS4’)] (12): FeCl2·4H2O (52 mg, 0.25 mmol) was added
to a light yellow solution of ‘tpS4’-Li2 (93 mg, 0.25 mmol) in
CH2Cl2 (30 mL) and MeOH (10 mL). The reaction mixture was
filtered, and NO gas (11.4 mL, 0.50 mmol) was injected into the
dark orange filtrate by syringe. After stirring for 1 h, the solution
was reduced in volume to 4 mL. A red-brown solid precipitated,
and this was separated, washed with MeOH (20 mL) and Et2O
(20 mL) and dried in vacuo. Yield: 50 mg (12·1.5MeOH) (38%). 1H
NMR (CD2Cl2, 269.72 MHz): δ ϭ 7.85Ϫ6.45 (m, C6H4) ppm. MS
[Fe(PnBu3)2(‘tpS4’)]ϩ, 412 [Fe(‘tpS4’)]ϩ, 824 [Fe(‘tpS4’)]2ϩ, 1236
ϩ
[Fe(‘tpS4’)]3
.
[Fe(dppe)(‘tpS4’)] (11): FeCl2·4H2O (98 mg, 0.49 mmol) and dppe
(196 mg, 0.49 mmol) were added to a light yellow solution of ‘tpS4’-
(FD, CH2Cl2, 56Fe): m/z: 472 [Fe(NO)2(‘tpS4’)]ϩ, 442
ϩ
[Fe(NO)(‘tpS4’)]ϩ, 412 [Fe(‘tpS4’)]ϩ, 824 [Fe(‘tpS4’)]2
, 1236
Table 2. Selected crystallographic data of [Fe(CO)(‘tpS4’)]2·MeOH (3·MeOH), [Fe(CO)(PMe3)(‘tpS4’)] (4), [Fe(CO)(PBu3)(‘tpS4’)] (7) and
[Fe(PMe3)2(‘tpS4’)] (8)
3·MeOH
4
7
8
Empirical formula
C39H28Fe2O3S8
912.79
298
C22H21FeOPS4
516.45
294
C31H39FeOPS4
642.68
200
C24H30FeP2S4
564.51
298
Mr [g molϪ1
T [K]
]
Crystal size [mm]
Crystal system
Space group
F(000)
a [pm]
b [pm]
0.30 ϫ 0.18 ϫ 0.12
tetragonal
I41/a
3728
1484.7(2)
1484.7(2)
3551.0(10)
90
7.83(1)
8
1.549
1.206
0.62 ϫ 0.40 ϫ 0.04
monoclinic
C2/c
0.50 ϫ 0.42 ϫ 0.30
monoclinic
P21/c
0.55 ϫ 0.45 ϫ 0.18
monoclinic
Cc
2128
1352
2352
2979.0(7)
1128.1(6)
1419.0(4)
106.88(1)
4.563(3)
8
2081.8(5)
1109.5(3)
1435.2(3)
108.86(1)
3.137(2)
4
1993.1(7)
1895.6(6)
1505.0(6)
110.17(3)
5.34(1)
c [pm]
β [°]
V [nm3]
Z
8
ρcalcd. [g cmϪ3
]
1.503
1.109
1.361
0.821
1.405
1.009
µ [mmϪ1
]
Diffractometer
Radiation [pm]
Scan technique
2Θ range [°]
Scan speed [° minϪ1
Measured refl.
Unique refl.
Rint [%]
Nicolet R3m/V
Mo-Kα (λ ϭ 71.073)
ω-scan
4.4Ϫ54.0
5
5503
4284
8.39
764
Siemens P4
Mo-Kα (λ ϭ 71.073)
ω-scan
3.8Ϫ50.0
2
4959
3805
8.35
1973
Fo Ն 4.0σ(F)
265
Siemens P4
Mo-Kα (λ ϭ 71.073)
ω-scan
4.0Ϫ54.0
8
8456
6839
5.28
4403
Fo Ն 4.0σ(F)
431
Nicolet R3m/V
Mo-Kα (λ ϭ 71.073)
ω-scan
3.6Ϫ54.0
5
7285
6498
2.75
3795
Fo Ն 4.0σ(F)
559
]
Observed refl.
σ criterion
Parameters
Fo Ն 4.0σ(F)
240
R1; wR2 [%]
Abs. structure parameter
4.80; 9.62
Ϫ
6.90; 15.71
Ϫ
7.18; 17.86
Ϫ
3.78; 7.13
Ϫ0.02(2)
Eur. J. Inorg. Chem. 2003, 418Ϫ426
425

D. Sellmann, D. C. F. Blum, F. W. Heinemann, J. Sutter
FULL PAPER
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[Fe(‘tpS4’)]3ϩ. IR (KBr): ν˜ ϭ 1812 w, 1779 vs, 1750 cmϪ1 vs
M. Y. Darensbourg, E. J. Lyon, J. J. Smee, Coord. Chem. Rev.
2000, 206/207, 533Ϫ561.
D. Sellmann, J. Sutter, Acc. Chem. Res. 1997, 30, 460Ϫ469 and
literature cited there.
D. Sellmann, J. Reißer, J. Organomet. Chem. 1985, 294,
333Ϫ346.
D. Sellmann, K. Engl, T. Gottschalk-Gaudig, F. W. Heine-
mann, Eur. J. Inorg. Chem. 1999, 333Ϫ339.
D. Sellmann, D. C. F. Blum, F. W. Heinemann, Inorg. Chim.
Acta, 2002, 337, 1Ϫ10.
[ν(NO)]. IR (CH2Cl2): ν˜ ϭ 1814 w, 1784 vs, 1756 cmϪ1 vs [ν(NO)].
C19.5H18FeN2O3.5S4 (12·1.5MeOH) (520.48): calcd. C 45.00, H
3.49, N 5.38, S 24.64; found C 44.09, H 2.95, N 5.23, S 24.71.
X-ray Structure Analyses of [Fe(CO)(‘tpS4’)]2·MeOH (3·MeOH),
[Fe(CO)(PMe3)(‘tpS4’)] (4), [Fe(CO)(PBu3)(‘tpS4’)] (7) and [Fe(P-
Me3)2(‘tpS4’)] (8): Dark red single crystals of 3·MeOH were formed
by layering a saturated THF solution of 3 with MeOH. Green
platelets of 4 and brown crystals of 7 were grown by layering satur-
ated CH2Cl2 solutions of 4 and 7 with MeOH. Black single crystals
of 8 were obtained by layering a saturated THF solution of 8 with
Et2O. Suitable single crystals were either embedded in protective
perfluoro polyalkyl ether oil or sealed in a glass capillary under N2.
The structures were solved by direct methods, and full-matrix, le-
ast-squares refinement was carried out on F2 values.[14] All non-
hydrogen atoms were refined anisotropically. All hydrogen atoms
are geometrically positioned. The MeOH solvate molecule in
3·MeOH is disordered on a crystallographic 41 axis, no hydrogen
atoms have been taken into account for this molecule. The PBu3
ligand in 7 is strongly disordered. Selected crystallographic data are
summarised in Table 2.[15]
D. Sellmann, H. F. Friedrich, F. Knoch, Z. Naturforsch., Teil
B 1993, 48, 1675Ϫ1680.
D. Sellmann, H. E. Jonk, H. R. Pfeil, G. Huttner, J. von Seyerl,
J. Organomet. Chem. 1980, 191, 171Ϫ179.
[9] [9a]
D. Sellmann, R. Weiß, F. Knoch, Angew. Chem. 1989, 101,
1719Ϫ1721; Angew. Chem. Int., Ed. Engl. 1989, 28, 1703Ϫ1705.
[9b]
D. Sellmann, R. Weiß, F. Knoch, G. Ritter, J. Dengler, In-
org. Chem. 1990, 29, 4107Ϫ4114.
D. Sellmann, A. Hennige, F. W. Heinemann, Inorg. Chim. Acta
1998, 280, 39Ϫ49.
C. A. McAuliffe, in Comprehensive Coordination Chemistry
(Eds.: G. Wilkinson, R. D. Gillard, J. A. McCleverty), Perga-
mon Press, Oxford, 1987, 2, p. 1015.
L. K. Bell, J. Mason, D. M. P. Mingos, D. G. Tew, Inorg. Chem.
1983, 22, 3497Ϫ3502.
[10]
[11]
[12]
[13]
W. Wolfsberger, H. Schmidbaur, Syn. Reactiv. Inorg. Metal-
Org. Chem. 1974, 4, 149Ϫ156.
[14]
[15]
Acknowledgments
SHELXTL NT 5.10, Bruker AXS, Inc., Madison, WI, 1998.
CCDC-187351 (3·MeOH), -187352 (4), -187353 (7), and
-187354 (8) contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge at
www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cam-
bridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK [Fax: (internat.) ϩ 44-1223/336-033;
E-mail: deposit@ccdc.cam.ac.uk].
Financial support of this work by the Deutsche Forschungsgemein-
schaft, SFB 583 ‘‘Redoxaktive Metallkomplexe Ϫ Reaktivitätssteu-
erung durch molekulare Architekturen’’, and the Fonds der
Chemischen Industrie is gratefully acknowledged.
[1]
[1a] B. K. Burgess, D. J. Lowe, Chem. Rev. 1996, 96, 2983Ϫ3011.
Received June 19, 2002
[1b]
R. R. Eady, Chem. Rev. 1996, 96, 2965Ϫ2982.
[I02323]
426
Eur. J. Inorg. Chem. 2003, 418Ϫ426