Syntheses and structures of transition metal thiolate complexes containing the new bis(tetramethylguanidine) ligand btmgp

Article abstract of DOI:10.1016/S0020-1693(00)00310-8

The syntheses, spectroscopic and structural characterizations of the first iron and copper thiolate guanidine complexes are described. Reactions of the neutral complexes [CuI(btmgp)] and [FeI₂(btmgp)] [btmgp = 1,3-bis(N,N,N′,N′-tetramethylguanidino)propane] with different uni- and bi-dentate thiolate ions yield the three-coordinate complex [Cu(S-2,4,6-^tBu₃C₆H₂)(btmgp)] (1) and the four-coordinate complexes [Fe(S-2,4,6-ⁱPr₃C₆ H₂)₂(btmgp)] (2) and [Fe(SiMe₂(C₆H₄S)₂)(btmgp)] (3) respectively. Starting with [Fe(N(SiMe₃)₂)₂], btmgp and the dithiol SiMe₂(C₆H₄SH)₂, an alternative procedure for the preparation of 3 is reported, demonstrating a useful synthetic approach towards neutral, N/S mixed coordinated Fe(II) complexes. The X-ray structure analyses of 1-3 reveal trigonal planar (2N/1S) (1) and tetrahedral (2N/2S) (2, 3) coordination environments around the metal centers.

Full text of DOI:10.1016/S0020-1693(00)00310-8

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Inorganica Chimica Acta 311 (2000) 106–112
Syntheses and structures of transition metal thiolate complexes
containing the new bis(tetramethylguanidine) ligand btmgp
Siegfried Pohl a,1, Michael Harmjanz b,*, Jo¨rg Schneider c, Wolfgang Saak a,
Gerald Henkel c
a Fachbereich Chemie, Carl 6on Ossietzky Uni6ersita¨t Oldenburg, Carl 6on Ossietzky Str., 26111 Oldenburg, Germany
b Department of Chemistry, Inorganic Di6ision, PO Box 117200, Gaines6ille, FL 32611-7200, USA
c Institut fu¨r Synthesechemie, Gerhard-Mercator-Uni6ersita¨t Duisburg, Lotharstr., 47048 Duisburg, Germany
Received 24 February 2000; accepted 8 September 2000
Abstract
The syntheses, spectroscopic and structural characterizations of the first iron and copper thiolate guanidine complexes are
described. Reactions of the neutral complexes [CuI(btmgp)] and [FeI2(btmgp)] [btmgp=1,3-bis(N,N,N%,N%-tetramethyl-
guanidino)propane] with different uni- and bi-dentate thiolate ions yield the three-coordinate complex [Cu(S-2,4,6-
tBu3C6H2)(btmgp)] (1) and the four-coordinate complexes [Fe(S-2,4,6-iPr3C6H2)2(btmgp)] (2) and [Fe(SiMe2(C6H4S)2)(btmgp)] (3)
respectively. Starting with [Fe(N(SiMe3)2)2], btmgp and the dithiol SiMe2(C6H4SH)2, an alternative procedure for the preparation
of 3 is reported, demonstrating a useful synthetic approach towards neutral, N/S mixed coordinated Fe(II) complexes. The X-ray
structure analyses of 1–3 reveal trigonal planar (2N/1S) (1) and tetrahedral (2N/2S) (2, 3) coordination environments around the
metal centers. © 2000 Elsevier Science B.V. All rights reserved.
Keywords: Iron complexes; Copper complexes; Thiolate complexes; Guanidino complexes; Crystal structures
halides, the ligand readily forms neutral mononuclear
complexes with the favorable formation of six-membered
chelate rings. Depending on the metal and its oxidation
state, structural characterizations of the respective com-
plexes show that the ligand is able to stabilize either a
trigonal planar, a square planar, or a tetrahedral coordi-
nation environment. Taking into account the high solu-
bility of this ligand in most common aprotic solvents, its
steric demands, and its high basicity, this ligand perfectly
meets our requirements. In particular, the high basicity
should be useful to allow for a wide range of metal
oxidation states in a variety of complexes and clusters
containing this ligand, as well as other donor functions.
In continuation of our previous work, we thus prepared
a series of novel neutral thiolate complexes with 1,3-bis-
(tetramethylguanidino)propane as co-ligand, which
might be suitable for further controlled reactions with
sulfur and oxygen [5]. All thiolate complexes have been
characterized by X-ray structure analysis, IR and ele-
mental analysis. In addition, the diamagnetic complex
1. Introduction
Neutral mixed coordinated thiolate complexes play an
important role in the preparation of model compounds
for various biologically active metal sites [1,2]. In many
of these compounds aryl- or alkyl-thiolate ligands mimic
the cysteine residue, whereas imidazole or amine ligands
are used to mimic the histidine residue. In our attempts
to prepare asymmetrically functionalized iron–sulfur or
N/S functionalized heterometal clusters the synthetic
strategies often required neutral nitrogen donor ligands
with a higher basicity. Recently, we were able to prepare
a bidentate guanidine-based ligand on a multigram scale
[3]. In this new compound [1,3-bis(N,N,N%,N%-tetra-
methylguanidino)propane, (btmgp)],
a trimethylene
bridge links two tetramethylguanidine units. This ligand
is related to bidentate imidazoline systems developed by
Kuhn et al. [4]. Upon reaction with transition metal
* Corresponding author. Fax: +1-352-392 3255.
E-mail address: mharm@chem.ufl.edu (M. Harmjanz).
1 Deceased.
1
[Cu(S-2,4,6-tBu3C6H2)(btmgp)] (1) was examined by H
NMR spectroscopy.
0020-1693/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(00)00310-8

S. Pohl et al. / Inorganica Chimica Acta 311 (2000) 106–112
107
2. Experimental
CꢀCH2ꢀC], 2.58 [s, 12H, N(CH3)2], 2.70 [s, 12H,
3
N(CH3)2], 3.11 (‘t’, J=5.4, 4H, ꢀCH2ꢀN), 7.27 (s, 2H,
CArꢀH).
2.1. General remarks
2.3.2. [Fe(S-2,4,6-iPr3C6H2)2(btmgp)] (2)
The 1,3-bis(N,N,N%,N%-tetramethylguanidino)propane
was prepared by using Schlenk techniques following the
procedure previously described [3]. Further operations
were performed under an inert atmosphere, using glove-
box techniques. The complexes [FeI2(btmgp)] and
[CuI(btmgp)] were prepared according to the literature
procedure [3].
The solvents THF and toluene were distilled from
Na–K–benzophenone and Na under a nitrogen atmo-
sphere after being refluxed for 6 h. 2,4,6-Triisopropyl-
benzenethiol was prepared by reduction of commercial
(Lancaster) 2,4,6-triisopropylbenzenesulfonylchloride
with LiAlH4 in dry THF [6]. Bis(2-mercaptoben-
zene)dimethylsilane [7], 2,4,6-tri-tert-butyl-benzenethiol
[8] and [Fe(N(SiMe3)2)2]·THF [9] were prepared by
published methods.
Potassium (0.67 g, 17.2 mmol) was added to a solu-
tion of 2,4,6-triisopropylbenzenethiol (4.07 g, 17.2
mmol) in 80 ml of THF and the resulting reaction
mixture was heated to reflux for 12 h. The mixture was
treated with [FeI2(btmgp)] (4.97 g, 8.6 mmol) and
refluxed for a further 2 h. The mixture was cooled to
room temperature, filtered and concentrated to one-
third of its volume. The precipitating pale yellow crys-
tals were collected after 1 day and dried in vacuo. Two
more crops of crystals were obtained by concentration
of the mother liquor. Yield 2.90 g (42%). Anal. Calc. for
C43H76N6FeS2: C, 64.80; H, 9.61; N, 10.54%. Found: C,
64.64; H, 9.60; N, 10.44%. IR (KBr, cm−1): 2957(vs),
2922(vs), 2891(s), 2863(s), 1559(vs), 1532(vs), 1462(s),
1420(s), 1393(vs), 1354(m), 1296(m), 1235(m), 1161(m),
1142(m), 1101(w), 1059(m), 1032(m), 941(m), 912(w),
872(m), 833(vw), 772(m), 756(m), 646(w), 577(w),
502(w), 397(w).
2.2. Physical measurements
All measurements were performed under strictly
anaerobic conditions. IR spectra were obtained using a
Bio-Rad FTS-7 (2, 3) and a Bruker IFS 66v (1) spec-
2.3.3. [Fe(SiMe2(C6H4S)2)(btmgp)] (3)
I.
1,3-Bis(N,N,N%,N%-tetrametylguanidino)propane
(1.20 g, 4.4 mmol) was added to a stirred solution of
[Fe(N(Si(Me3)2)2]·THF (2.00 g, 4.4 mmol) in 30 ml of
toluene. A solution of bis(2-mercaptobenzene)dimethyl-
silane (1.23 g, 4.4 mmol) in 20 ml of toluene was added
dropwise to the stirred reaction mixture. After 24 h the
resulting pale yellow precipitate was collected, washed
with toluene and dried in vacuo. Yield 2.24 g (85%).
II. Potassium (0.14 g, 3.6 mmol) was added to a
1
trometer. H NMR spectra for 1 were obtained with a
Bruker Avance DRX 500 spectrometer and solvent
signals were used as an internal standard [calibrated on
7.240(1H)]. Elemental analysis for 1 was performed at
the Universita¨t Duisburg. Microanalyses for 2 and 3
were performed at the Mikroanalytisches Labor, Beller,
Go¨ttingen, Germany.
solution
of
bis(2-mercaptobenzene)dimethylsilane
2.3. Synthesis
(0.50 g, 1.8 mmol) in THF. The mixture was refluxed
for 12 h and [FeI2(btmgp)] (1.05 g, 1.8 mmol) was
added to the hot suspension. The reaction mixture was
refluxed for a further 4 h, cooled to room temperature
and filtered. The volume of the filtrate was gradually
reduced and the precipitated pale yellow crystals were
collected after 1 day and dried in vacuo. Yield 0.43 g
(40%). Anal. Calc. for C27H44FeN6S2Si: C, 53.98; H,
7.38; N, 13.99%. Found: C, 53.85; H, 7.34; N, 14.02%.
IR (KBr, cm−1): 3044(m), 3005(w), 2930(s), 2893(s),
2851(s), 2799(m), 1545(vs), 1528(vs), 1474(s), 1454(s),
1424(vs), 1408(s), 1393(vs), 1352(m), 1327(s), 1240(s),
1155(s), 1125(m), 1099(m), 1080(m), 1063(m), 1046(m),
1030(s), 951(m), 905(m), 868(w), 818(vs), 748(vs),
714(s), 664(m), 629(m), 600(m), 575(m), 484(w), 444(m),
409(m), 355(m), 314(m), 274(s).
2.3.1. [Cu(S-2,4,6-tBu3C6H2)(btmgp)] (1)
To [CuI(btmgp)] (461 mg, 1 mmol), dissolved in
15 ml of THF, btmgp (270 mg, 1 mmol) and K[2,4,6-
tBu3C6H2S] (317 mg, 1 mmol) suspended in 10 ml of
THF were added. The reaction mixture was stirred for
8 h at room temperature and then filtered. The yellow-
ish filtrate was dried in vacuo. Recrystallization of the
crude product from hot acetonitrile (8 ml) yielded col-
orless crystals suitable for X-ray diffraction. Yield:
368 mg (60%).
Anal. Calc. for C31H59N6CuS: C, 60.89; H, 9.73; N,
13,74; S, 5.24%. Found: C, 60.81; H, 9.72; N, 13.60; S,
5.45%. IR (KBr, cm−1): 3084(w), 2934(vs), 1594(s),
1565(vs), 1521(s), 1477(m), 1424(m), 1392(s), 1375(s),
1333(m), 1282(w), 1241(m), 1184(w), 1149(m), 1082(m),
1064(m), 1040(m), 1026(m), 990(m), 951(m), 924(m),
906(m), 876(m), 802(w), 755(m), 745(m), 702(w),
2.4. X-ray crystallography
1
644(w), 575(w). H NMR (500 MHz, CDCl3): l 1.26 [s,
The molecular structure of 1 was determined at
9H, p-C(CH3)3CAr], 1.74 [‘s’, 20H, o-C(CH3)3CAr and
150 K, using a Siemens P4RA four-circle diffractometer

108
S. Pohl et al. / Inorganica Chimica Acta 311 (2000) 106–112
[graphite monochromatized Mo Ka radiation (u=
mononuclear, mixed coordinated iron(II) or copper(I)
thiolate complexes is outlined by the following equa-
tions [2]:
,
0.710 73 A)]. An empirical absorption correction was
applied. Data collection gave 7577 independent reflec-
tions (qmax 27.06). The structure was solved by direct
methods and the initial structural model expanded by
full-matrix least-squares refinement (on F2) and differ-
ence Fourier techniques [10]. Anisotropic displace-
ment parameters were used for all non-hydrogen
atoms. Hydrogen atoms were included in calculated
positions.
MXn+mL“[MXnLm]
(1)
[X=I, Br, Cl; n=1, 2; L=neutral ligand (bidentate:
m=1; monodentate: m=2), M=Cu(I), Fe(II)] [11].
[MXnLm]+nKSR“[M(SR)nLm]+nKX
(2)
In some cases the complex [FeX2Lm] does not have to
be isolated, and the reaction with the appropriate thio-
late (Eq. (2)) can be carried out in situ [12]. However,
the high solubility of KX, in a variety of polar solvents,
often leads to purification problems. Furthermore, if
dithiolate ions (according to Eq. (2)) are considered
instead of monofunctional ones, their use is limited,
owing to the reduced solubility of the required dipotas-
sium salts. Therefore, a synthetic procedure that avoids
these problems is desirable. As previously reported,
neutral iron thiolate complexes with thiourea deriva-
tives can also be obtained by a one-step procedure
following Eq. (3) (L=thiourea) [1]:
The X-ray measurements for 2 and 3 were carried
out on an AED2 Siemens four-circle diffractometer.
During the data collection the intensities of three
check reflections indicated stable crystal settings. Data
collection using (graphite monochromatized) Mo Ka
,
radiation (u=0.710 73 A) gave: 2, 5924 independent
reflections (qmax 21.99°); 3, 2595 independent reflec-
tions (qmax 23.99°), of which 2347 with I\2|(I) were
used in all calculations. The structures were solved as
described for 1. The para-iPr moieties in 2 were
found to be disordered and were refined in two dif-
ferent positions (0.5 occupancy). Further relevant
crystallographic data are listed in Table 1.
[Fe(N(SiMe3)2)2]+mL+2RSH
“[Fe(SR)2Lm]+2HN(SiMe3)2
(3)
3. Results and discussion
The free amine HN(SiMe3)2 does not react with the
resulting complex and can easily be removed by
washing the product with n-hexane. In general, this
reaction should be suitable for the generation of
3.1. Syntheses and reactions
A possible pathway for the preparation of neutral,
Table 1
Structure determination summary for 1–3
1
2
3
Formula
C31H59N6SCu
611.44
0.70×0.22×0.26
monoclinic
P21/c
C43H76N6S2Fe
797.07
0.68×0.34×0.17
monoclinic
P21/c
C27H44N6S2SiFe
600.74
0.91×0.76×0.68
orthorhombic
Aba2
Formula weight
Crystal dimensions (mm)
Crystal system
Space group
,
a (A)
18.107(3)
9.916(2)
19.596(4)
99.58(1)
3469(1)
4
9.664(1)
25.906(2)
19.381(2)
90.68(1)
4852(1)
4
20.091(1)
19.457(1)
16.306(1)
,
b (A)
,
c (A)
i (°)
V (A )
3
,
6374(1)
8
1.252
Z
Dcalc (g cm−3
)
1.171
1.091
Temperature (K)
150
7.17
296
4.30
296
6.68
v (cm−1
)
,
u Mo Ka (A)
0.710 73
54.1
0.710 73
44.0
0.710 73
48.0
2qmax (°)
Independent reflections
Data/restraints/parameters
Reflections with [I\2|(I)]
R1, wR2 [I\2|(I)]a
All data
7577
7577/0/345
6109
0.0337, 0.0784
0.0498, 0.0854
1.055
5924
5922/0/463
3059
0.0761, 0.1484
0.1649, 0.1911
1.012
2595
2592/0/333
2347
0.0296, 0.0674
0.0360, 0.0714
1.029
GOFb
a wR2={S[w(Fo2–Fc2)2]/S[w(Fo2)2]}1/2; R1=SꢀꢀFoꢀ−ꢀFcꢀꢀ/SꢀFoꢀ.
b GOF=S={S[w(Fo2–Fc2)2]/(n–p)}1/2
.

S. Pohl et al. / Inorganica Chimica Acta 311 (2000) 106–112
109
Fig. 1. The IR spectra of btmgp, [CuI(btmgp)] and 1.
1
mixed iron(II) complexes with uni- or bi-dentate neutral
3.2. Infrared and H NMR spectra
ligands and uni- or bi-dentate thiolates of various steric
demands.
The w(NꢁC) IR pattern of the coordinated guanidine
ligand is quite similar to those found in the respective
halide complexes [3]. As expected [13,14], the w(NꢁC)
band of the free ligand (1621 cm−1) shifted to lower
wave numbers upon coordination, accompanied by a
splitting into a triplet (1) (1594, 1565, 1521 cm−1) or a
doublet (2, 3) [1559, 1532 (2), 1545, 1528 cm−1 (3)]
(Fig. 1).
The complexes containing monofunctional thiolates
[Cu(S-2,4,6-tBu3C6H2)(btmgp)] (1) and [Fe(S-2,4,6-
iPr3C6H2)2(btmgp)] (2) have been prepared according to
Eqs. (1) and (2) in 60% and 42% yields respectively. In
order to examine the modified procedure for L=btmgp
and the bifunctional thiol SiMe2(C6H4SH)2, [Fe(SiMe2-
(C6H4S)2)(btmgp)] (3) was prepared following both
pathways. Starting with [Fe(N(SiMe3)2)2] in toluene,
analytically pure 3 could be obtained directly in 85%
yield without further purification. In contrast, 3 was
obtained in only 40% yield, following the two-step
procedure described by Eqs. (1) and (2).
1
The H NMR of the diamagnetic copper complex 1
shows two chemically different dimethylamino groups,
one of which adopts the cis- and the other the trans-po-
sition of the imine double bond (with respect to the
trimethylene bridge). In comparison with the uncom-

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S. Pohl et al. / Inorganica Chimica Acta 311 (2000) 106–112
plexed (0.09 ppm) and the diprotonated ligands
(0.08 ppm), the sterically crowded thiolate ligand causes
Fig. 4. ORTEP drawing of [Fe(SiMe2(C6H4S)2)(btmgp)] (3). Thermal
ellipsoids have been drawn at the 50% probability level, and hydrogen
atoms have been omitted for clarity.
Fig. 2. ORTEP drawing of [Cu(S-2,4,6-tBu3C6H2)(btmgp)] (1). Thermal
ellipsoids have been drawn at the 50% probability level, and hydrogen
atoms have been omitted for clarity.
only a slightly increased shift difference (0.12 ppm) for
these two methyl groups. Furthermore, the electron-
rich metal center gives rise to only a minor deshielding
of the nitrogen atoms within the guanidine units. This
is evident in the negligible small low field shifts of the
signals for the peripheral methyl substituents upon
coordination [btmgp: 2.56, 2.65; (1): 2.58, 2.70 ppm].
3.3. Crystal structures
Figs. 2–4 show the molecular structures of 1–3, with
selected bond parameters given in Table 2. Crystals of
1–3 consist of discrete neutral complex molecules with
a trigonal planar (1) or distorted tetrahedral (2, 3)
coordination geometries. In all three cases, 1,3-bis(tetra-
methylguanidino)propane acts as a bidentate ligand
with the imino nitrogen as the donor site and NꢀMꢀN
angles ranging from 90.5(1) (3) to 93.3(3)° (2).
According to the literature, structurally characterized
neutral mononuclear Cu(I) thiolate complexes with
mixed 2N/1S ligand spheres are rare; the only examples
are [Cu(SDpp)(tmphen)] [15], [Cu(SMes)(tmphen)] [15],
and [Cu(SSi(OtBu)3)(phen)] [16]. All these phenanthro-
line-based thiolate complexes exhibit a highly dissym-
metric chelate coordination of the N-donor ligands with
significantly different Cu-N separations and varying
obtuse angles (NꢀCuꢀS). The observed dissymmetry
can be mainly attributed to the strong s- and p-donat-
ing ligands forcing the electron-rich Cu(I) into a 2+1
coordination environment [15]. Unsurprisingly, a simi-
lar T-shaped coordination arrangement is also found in
Fig. 3. ORTEP drawing of [Fe(S-2,4,6-iPr3C6H2)2(btmgp)] (2). Thermal
ellipsoids have been drawn at the 30% probability level, and hydrogen
atoms have been omitted for clarity.

S. Pohl et al. / Inorganica Chimica Acta 311 (2000) 106–112
111
Table 2
,
Selected interatomic distances (A) and angles (°)
[Cu(S-2,4,6-tBu3C6H2)(btmgp)] (1)
Distances
Cu(1)ꢀN(1)
S(1)ꢀC(14)
N(2)ꢀC(4)
N(3)ꢀC(4)
N(4)ꢀC(3)
N(5)ꢀC(10)
N(6)ꢀC(13)
2.156(1)
1.795(1)
1.381(2)
1.383(2)
1.471(2)
1.448(2)
1.449(2)
Cu(1)ꢀN(4)
N(1)ꢀC(1)
N(2)ꢀC(5)
N(3)ꢀC(7)
N(4)ꢀC(9)
N(5)ꢀC(11)
N(6)ꢀC(12)
1.983(2)
1.459(2)
1.462(3)
1.454(3)
1.308(2)
1.454(2)
1.449(3)
Cu(1)ꢀS(1)
N(1)ꢀC(4)
N(2)ꢀC(6)
N(3)ꢀC(8)
N(5)ꢀC(9)
N(6)ꢀC(9)
2.1743(6)
1.289(2)
1.456(3)
1.449(3)
1.358(2)
1.377(2)
Angles
N(4)ꢀCu(1)ꢀN(1)
C(14)ꢀS(1)ꢀCu(1)
C(3)ꢀN(4)ꢀCu(1)
C(4)ꢀN(2)ꢀC(6)
C(4)ꢀN(3)ꢀC(7)
C(9)ꢀN(4)ꢀC(3)
C(10)ꢀN(5)ꢀC(11)
C(13)ꢀN(6)ꢀC(12)
N(2)ꢀC(4)ꢀN(3)
N(5)ꢀC(9)ꢀN(6)
91.18(6)
104.46(4)
111.1(1)
118.4(2)
120.7(2)
118.3(2)
114.5(2)
116.2(1)
115.1(2)
116.5(2)
N(4)ꢀCu(1)ꢀS(1)
C(4)ꢀN(1)ꢀCu(1)
C(9)ꢀN(4)ꢀCu(1)
C(4)ꢀN(2)ꢀC(5)
C(6)ꢀN(2)ꢀC(5)
C(9)ꢀN(5)ꢀC(10)
C(9)ꢀN(6)ꢀC(13)
N(1)ꢀC(4)ꢀN(2)
N(4)ꢀC(9)ꢀN(5)
C(3)ꢀC(2)ꢀC(1)
151.46(5)
122.3(1)
127.2(1)
118.6(2)
112.9(2)
120.6(2)
123.2(1)
120.2(2)
120.4(2)
115.0(2)
N(1)ꢀCu(1)ꢀS(1)
C(1)ꢀN(1)ꢀCu(1)
C(4)ꢀN(1)ꢀC(1)
C(4)ꢀN(3)ꢀC(8)
C(8)ꢀN(3)ꢀC(7)
C(9)ꢀN(5)ꢀC(11)
C(9)ꢀN(6)ꢀC(12)
N(1)ꢀC(4)ꢀN(3)
N(4)ꢀC(9)ꢀN(6)
117.15(4)
106.8(1)
119.8(2)
122.6(2)
115.6(2)
122.8(2)
120.6(2)
124.6(2)
123.1(2)
[Fe(S-2,4,6-iPr3C6H2)2(btmgp)] (2)
Distances
Fe(1)ꢀN(1)
Fe(1)ꢀS(1)
N(1)ꢀC(4)
N(2)ꢀC(6)
N(3)ꢀC(8)
N(4)ꢀC(3)
N(5)ꢀC(11)
N(6)ꢀC(12)
2.082(7)
Fe(1)ꢀN(4)
S(1)ꢀC(14)
N(1)ꢀC(1)
N(2)ꢀC(5)
N(3)ꢀC(7)
N(5)ꢀC(9)
N(6)ꢀC(9)
2.079(7)
1.770(8)
1.52(1)
1.53(1)
1.51(1)
1.35(1)
1.37(1)
Fe(1)ꢀS(2)
S(2)ꢀC(29)
N(2)ꢀC(4)
N(3)ꢀC(4)
N(4)ꢀC(9)
N(5)ꢀC(10)
N(6)ꢀC(13)
2.345(2)
1.777(8)
1.35(1)
1.38(1)
1.29(1)
1.47(1)
1.46(1)
2.362(2)
1.27(1)
1.41(1)
1.46(1)
1.53(1)
1.49(1)
1.49(1)
Angles
N(1)ꢀFe(1)ꢀN(4)
N(4)ꢀFe(1)ꢀS(1)
C(14)ꢀS(1)ꢀFe(1)
C(4)ꢀN(1)ꢀFe(1)
C(4)ꢀN(2)ꢀC(5)
C(4)ꢀN(3)ꢀC(7)
C(9)ꢀN(4)ꢀFe(1)
C(9)ꢀN(5)ꢀC(11)
C(9)ꢀN(6)ꢀC(12)
N(1)ꢀC(4)ꢀN(3)
N(4)ꢀC(9)ꢀN(6)
93.3(3)
99.1(2)
N(4)ꢀFe(1)ꢀS(2)
N(1)ꢀFe(1)ꢀS(1)
C(29)ꢀS(2)ꢀFe(1)
C(1)ꢀN(1)ꢀC(4)
C(6)ꢀN(2)ꢀC(5)
C(7)ꢀN(3)ꢀC(8)
C(3)ꢀN(4)ꢀFe(1)
C(10)ꢀN(5)ꢀC(11)
C(13)ꢀN(6)ꢀC(12)
N(2)ꢀC(4)ꢀN(3)
N(5)ꢀC(9)ꢀN(6)
124.2(2)
105.2(2)
116.6(3)
116.0(7)
116.4(9)
117.2(8)
111.8(5)
117.4(8)
119.0(9)
113.1(9)
116.1(9)
N(1)ꢀFe(1)ꢀS(2)
S(2)ꢀFe(1)ꢀS(1)
C(1)ꢀN(1)ꢀFe(1)
C(4)ꢀN(2)ꢀC(6)
C(4)ꢀN(3)ꢀC(8)
C(3)ꢀN(4)ꢀC(9)
C(9)ꢀN(5)ꢀC(10)
C(9)ꢀN(6)ꢀC(13)
N(1)ꢀC(4)ꢀN(2)
N(4)ꢀC(9)ꢀN(5)
114.6(2)
116.68(9)
112.7(5)
127.3(9)
121.7(8)
115.1(7)
120.0(8)
118.6(8)
121.9(9)
126.6(9)
115.1(3)
128.2(6)
115.6(8)
121.1(9)
126.7(6)
122.6(9)
120.9(9)
125.0(9)
117.2(9)
[Fe(SiMe2(C6H4S)2)(btmgp)] (3)
Distances
Fe(1)ꢀN(1)
Fe(1)ꢀS(1)
N(1)ꢀC(4)
N(2)ꢀC(6)
N(3)ꢀC(8)
N(4)ꢀC(3)
N(5)ꢀC(11)
N(6)ꢀC(12)
2.095(3)
Fe(1)ꢀN(4)
S(1)ꢀC(14)
N(1)ꢀC(1)
N(2)ꢀC(5)
N(3)ꢀC(7)
N(5)ꢀC(9)
N(6)ꢀC(9)
2.105(3)
1.781(4)
1.457(5)
1.461(6)
1.470(5)
1.355(5)
1.368(5)
Fe(1)ꢀS(2)
S(2)ꢀC(20)
N(2)ꢀC(4)
N(3)ꢀC(4)
N(4)ꢀC(9)
N(5)ꢀC(10)
N(6)ꢀC(13)
2.317(1)
1.772(4)
1.345(5)
1.371(6)
1.311(5)
1.445(6)
1.452(6)
2.320(1)
1.315(5)
1.454(7)
1.445(6)
1.481(5)
1.468(6)
1.458(5)
Angles
N(1)ꢀFe(1)ꢀN(4)
N(4)ꢀFe(1)ꢀS(1)
C(25)ꢀSi(1)ꢀC(19)
C(4)ꢀN(1)ꢀFe(1)
C(3)ꢀN(4)ꢀFe(1)
C(4)ꢀN(2)ꢀC(5)
C(4)ꢀN(3)ꢀC(7)
C(9)ꢀN(5)ꢀC(10)
C(9)ꢀN(6)ꢀC(13)
N(1)ꢀC(4)ꢀN(2)
N(4)ꢀC(9)ꢀN(5)
90.5(1)
119.62(9)
126.0(2)
126.5(2)
108.8(2)
122.3(4)
122.9(4)
121.3(3)
120.7(4)
119.9(4)
120.3(4)
N(1)ꢀFe(1)ꢀS(1)
N(4)ꢀFe(1)ꢀS(2)
C(14)ꢀS(1)ꢀFe(1)
C(1)ꢀN(1)ꢀFe(1)
C(4)ꢀN(1)ꢀC(1)
C(6)ꢀN(2)ꢀC(5)
C(8)ꢀN(3)ꢀC(7)
C(9)ꢀN(5)ꢀC(11)
C(9)ꢀN(6)ꢀC(12)
N(1)ꢀC(4)ꢀN(3)
N(4)ꢀC(9)ꢀN(6)
105.5(1)
109.8(1)
100.8(1)
109.2(2)
119.5(3)
114.3(4)
114.4(4)
122.4(4)
123.8(4)
123.4(3)
123.4(4)
N(1)ꢀFe(1)ꢀS(2)
S(2)ꢀFe(1)ꢀS(1)
C(20)ꢀS(2)ꢀFe(1)
C(9)ꢀN(4)ꢀFe(1)
C(4)ꢀN(2)ꢀC(6)
C(4)ꢀN(3)ꢀC(8)
C(9)ꢀN(4)ꢀC(3)
C(10)ꢀN(5)ꢀC(11)
C(13)ꢀN(6)ꢀC(12)
N(2)ꢀC(4)ꢀN(3)
N(5)ꢀC(9)ꢀN(6)
122.24(9)
109.01(4)
97.4(1)
129.5(2)
121.6(4)
122.1(4)
118.3(3)
114.7(4)
115.4(4)
116.6(4)
116.3(4)

112
S. Pohl et al. / Inorganica Chimica Acta 311 (2000) 106–112
[Cu(S-2,4,6-tBu3C6H2)(btmgp)] (1) with very different
NꢀCu(1)ꢀS(1) angles [117.15(4), 151.46(5)°] and Cu(1)ꢀN
complexes potential starting materials for the preparation
of homo- and heterodinuclear compounds. Investigations
examining these aspects are in progress.
,
distances [2.156(1), 1.983(2) A].
The two iron complexes exhibit significantly distorted
tetrahedral coordination spheres (Figs. 3 and 4). This is
mainly due to the unsymmetrical coordination environ-
ment, which is defined by the six-membered chelate ring
and the mono- (2) and bi-dentate (3) thiolate ligands of
different steric demands. The degree of distortion in these
pseudotetrahedral complexes can be seen in the deviations
ofthedihedralanglesfrom90°, definedbytheplanesN(1),
N(4), Fe(1) and S(1), S(2), Fe(1) [79.4° (3) to 84.7° (2)].
The sterically and electronically different ligand prop-
erties of the thiolates used result not only in significantly
different S(1)ꢀFeꢀS(2) angles [116.68(9) (2); 109.01(4)
(3)°], but also in significantly different FeꢀS separations
5. Supplementary information
Crystallographic data (excluding structure factors) for
the structure(s) reported in this paper have been deposited
with the Cambridge Crystallographic Data Centre as
supplementary publication no. CCDC-153142(1)–
153144(3). Copies of the data can be obtained free of
charge on application to CCDC, 12 Union Road, Cam-
bridge CB2 1EZ, UK [fax: +44(1223)336033; e-mail:
deposit@ccdc.cam.ac.uk].
,
[mean: 2.354 (2); 2.319 A (3)]. A comparison with previ-
Acknowledgements
ously characterized neutral four-coordinate iron thiolate
complexes containing thiolate ligands with almost similar
steric and electronic properties {[Fe(S-2,4,6-iPr3C6H3)2-
This work was supported by the Deutsche Forschungs-
gemeinschaft and by the Fonds der Chemischen Industrie.
J. S. thanks the Stiftung Stipendienfonds des Verbandes
der Chemischen Industrie for granting a Kekule´ fellow-
ship.
(tmtu)2], 2.315(1) A; [Fe(S-2,6-iPr2C6H3)2(1-MeIm)2],
,
,
2.317(2) A} [2,12] shows an elongated FeꢀS bond for
2, which presumably arises from the strong donor ability
of the bidentate nitrogen ligand.
In all three complexes, the mean Me2NꢀC and (CH2/
M)NꢀC separations within the guanidine fragments vary
References
,
in a wide range [1.30–1.37 (1); 1.28–1.36 (2); 1.31–1.36 A
(3)], which indicates that the delocalization of the CꢁN
double bond is restricted. This is probably due to the steric
demands of the NMe2 fragments. Consequently, the
planes defined by the dimethylamino groups and the
alkylimino group are twisted against the central guanidine
plane (CN3). This twisting ranges from 34.2° (32.7–36.3°)
in 2 to 38.5° (27.0–43.1°) in 1 for the respective dimethyl-
amino groups.
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4. Conclusion
This investigation provides the first example of iron and
copper thiolate guanidine complexes. We have reported
the straightforward synthesis of three complexes, two of
which contain Fe(II) and one contains Cu(I), bearing the
new 1,3-bis(tetramethylguanidino)propane ligand. The
previously introduced alternative route (Eq. 3), using
[Fe(N(SiMe3)2)2] to prepare neutral, mixed coordinated
thiolate/thiourea iron complexes, is also applicable for the
preparation of iron complexes with mixed S/N coordina-
tion environments. This synthetic pathway is the method
of choice if a bidentate thiolate ligand is introduced.
The structural analyses show significantly distorted
tetrahedral geometries for the iron complexes and, as a
result of the basicity of the bisguanidine ligand, a strong
dissymmetric ligand arrangement around the copper
center is evident. The strong basicity of the bisguanidine
ligand combined with its flexible backbone make these