Cyclopalladation of thiophene-substituted thiosemicarbazones

Article abstract of DOI:10.1016/j.jorganchem.2011.06.021

The thiosemicarbazones obtained from the condensation of thiosemicarbazide or 4,4′-dimethylthiosemicarbazide with 2-acetylthiophene react with K ₂PdCl₄ in the presence of a base to give dark, poorly soluble materials in high yields.

Full text of DOI:10.1016/j.jorganchem.2011.06.021

Journal of Organometallic Chemistry 696 (2011) 3150e3154
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Cyclopalladation of thiophene-substituted thiosemicarbazones
*
Henning Weiss, Fabian Mohr
Fachbereich CeAnorganische Chemie, Bergische Universität Wuppertal, 42119 Wuppertal, Germany
a r t i c l e i n f o
a b s t r a c t
The thiosemicarbazones obtained from the condensation of thiosemicarbazide or 4,40-dimethylth-
iosemicarbazide with 2-acetylthiophene react with K2PdCl4 in the presence of a base to give dark, poorly
soluble materials in high yields. Treatment of these oligomeric compounds with Ph3P, dppe or dppf gives
monomeric palladium(II) phosphine complexes in which the deprotonated thiosemicarbazones coordi-
nate to the metal in a tridentate fashion through the C3-cyclometallated thiophene ring, the imine
nitrogen atom and the sulphur atom. This coordination mode was confirmed by X-ray structure analysis
of several derivatives.
Article history:
Received 11 May 2011
Received in revised form
12 June 2011
Accepted 16 June 2011
Keywords:
Cyclometallation
Thiosemicarbazone
Tridentate ligands
Palladium
Ó 2011 Elsevier B.V. All rights reserved.
X-ray structure
1. Introduction
Curiously, there appear to be no reports of cyclopalladation
of thiosemicarbazones containing other five-membered
Thiosemicarbazones are versatile, multidentate ligands which
can be functionalised in many different ways. Their coordination
behaviour with transition- and main-group metals has recently
heterocyclic ring substituents including thiophene. Indeed,
recent results from Lobana demonstrated that thiophene-2-
carbaldehyde thiosemicarbazone acts as
a
monoanionic,
been summarised in
a
comprehensive review [1]. Cyclo-
bidentate [N,S]ꢀ donor ligand in a series of Pd(II) complexes
(Chart 2); the heterocycle itself does not interact with the metal
centre [13]. The same group reported cyclometallation of
thiophene-2-carbaldehyde thiosemicarbazone in a ruthenium
complex [14].
metallation i.e. the metal mediated activation of a CeH bond
leading to a cyclic structure, has been known for many years
[2e9]. This process occurs quite readily with palladium(II)
species and the resulting palladacycles can be utilised in the
synthesis of heterocycles, display liquid crystalline behaviour
and are very active catalysts in CeC coupling reactions [10].
There are also reports of cyclopalladation of phenyl- and
ferrocenyl-substituted thiosemicarbazones which result in the
formation of complexes containing tridentate, dianionic [C,N,S]2ꢀ
ligands (Chart 1) [11,12].
Given our interest in cyclometallation and the coordination
chemistry of sulfur containing multidentate ligands [15e18], we
embarked on an investigation of the cyclopalladation of some
thiophene-substituted thiosemicarbazones, the results of which
are reported herein.
L
N
Pd
L
R
N
Pd
N
S
R
N
S
NH2
S
Fe
N
S
Ph3P
R
NH2
N
N
S
Pd
R
N
S
N
Pd
Cl
N
N
S
Chart 1.
S
N
H2N
* Corresponding author.
E-mail address: fmohr@uni-wuppertal.de (F. Mohr).
Chart 2.
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.06.021

H. Weiss, F. Mohr / Journal of Organometallic Chemistry 696 (2011) 3150e3154
3151
2. Results and discussion
The thiosemicarbazones HL1 and HL2 obtained from the reac-
tion of thiosemicarbazide or 4,40-dimethylthiosemicarbazide with
2-acetylthiophene, respectively react with K2PdCl4 in the presence
of a base to give dark, poorly soluble materials 1 and 2 in high yields
(Scheme 1).
The 1H NMR spectrum ofcompound 1 (2wasinsoluble incommon
solvents) in dmso reveals that one signal of the thiophene ring (the
proton at position 3) as well as that of the NH proton have dis-
appeared. This suggests, that metallation at the 3 position of the
thiophene ring has occurred, accompanied by deprotonation of the
NH unit. We thus propose that the deprotonated thiophene thio-
semicarbazones act as dianionic [C,N,S]2ꢀ ligands in complexes 1 and
2. The palladation of the thiophene ring was further confirmed by 13C
NMR spectroscopy, which shows a downfield shift of the carbon
signal for C3 as well as a reduction of its intensity as expected for
a quaternary carbon atom. In addition, the signal of the CeS carbon
atom experiences an upfield shift compared to that of the free ligand
upon coordination to the Pd centre, consistent with a change of bond
order. Given the poor solubility of the material we believe complexes
1 and 2 to have oligomeric structures. Work by Vila has shown that
structurally similar compounds exist as tetramers through secondary
intermolecular S$$$Pd interactions [19e21]; the tetrameric structure
has been confirmed by X-ray crystallography [19]. It is entirely
possiblethatcomplexes 1and2arealsotetrameric,butapartfromthe
MALDI mass spectrum of complex 2, which shows a signal corre-
sponding tothe silveradduct (from theMALDImatrix)ofthetetramer
[Pd(L2)]4, we have no further evidence to substantiate this.
Fig. 1. Molecular structure of one of the two independent molecules of complex 3.
Ellipsoids show 50% probability levels. Hydrogen atoms have been omitted for clarity.
Selected bond distances [Å]: Pd(1)eC(1) 2.053(6), Pd(1)eN(1) 2.047(5), Pd(1)eS(1)
2.3206(17), Pd(1)eP(1) 2.2358(19). Selected angles [ꢁ]: C(1)ePd(1)eN(1) 81.3(2), C(1)e
Pd(1)eP(1) 96.1(2), C(1)ePd(1)eS(1) 163.7(2), N(1)ePd(1)eP(1) 177.28(16), N(1)e
Pd(1)eS(1) 82.39(15), P(1)ePd(1)eS(1) 100.19(6).
complexes are very similar, we shall discuss them together in the
following section.
The oligomeric complexes 1 and 2 react with Ph3P or the
diphosphines dppe and dppf to give mono- or dinuclear palladiu-
m(II) phosphine complexes of the type [Pd(L)(PPh3)] (3e4) and
The molecules consist of a palladium atom to which the
deprotonated thiophene thiosemicarbazone ligands are bound to
via the C-3 metallated thiophene ring, the imine nitrogen atom and
the sulfur atom of the thiosemicarbazone. The fourth coordination
site of the palladium atom is occupied by the phosphorus atom of
the phosphine ligand. Overall the coordination geometry about the
palladium atom is square planar. The PdeC bond lengths in the
complexes reported here (ca. 2.02e2.05 Å) are slightly longer than
those observed in the cyclopalladated N,N-dimethylthiophene
carboselenoamide complex (Chart 2) [PdeC ¼ 1.979(6) Å] [22] and
[Pd2(L)2(
yields as shown in Scheme 1. The spectroscopic data is again
consistent with the presence of cyclometallated, NH-
m-PP)] (PP ¼ dppe, dppf) (5e8), respectively in low to good
a
deprotonated thiosemicarbazone coordinating to the palladium
atom. In addition, the 31P NMR data (singlet resonances) of
compounds 3e8 are consistent with the presence of a P-coordi-
nated phosphine at the Pd centre. We managed to obtain X-ray
quality crystals of complexes 3, 4, 6 and 8, which allowed us to
unambiguously confirm the proposed structures. The molecular
structures are shown in Figs. 1e4. Since the structural features of all
also longer than that reported for
a
cyclopalladated
R
N
S
R
H
R
N
N
S
S
HN
PPh3
H
3
H
K2PdCl4
NaOAc
Ph3P
Pd
4
5
N
Pd
N
N
N
2
N
S
S
HL1
R = H (
S
)
n
R = Me (HL2)
3
R = H ( )
R = Me (4)
1
R = H ( )
R = Me (2)
P
P
R
S
P-P = dppe
N
R = H (5)
N
S
H
6
R = Me ( )
N
P
Pd
P
N
Pd
S
P-P = dppf
H
N
R = H (7)
S
N
R
8
R = Me ( )
Scheme 1.

3152
H. Weiss, F. Mohr / Journal of Organometallic Chemistry 696 (2011) 3150e3154
acetylthiophene imine compound [PdeC ¼ 1.990(2) Å] [23]. The
CeS and CeN bond distances in the ligand backbone are consistent
with the presence of a conjugated system. The other bond distances
and angles are unexceptional und typical for Pd coordination
compounds.
These complexes are amongst the first examples of palladium
complexes containing a metallated thiophene-substituted thio-
semicarbazone ligand. To the best of our knowledge, the only other
examples of palladated thiophene groups are found in the cyclo-
palladated N,N-dimethylthiophene carbothio- and selenoamides
(Chart 3) reported by Nonoyama [22,24] and, more recently, in
some azido derivatives containing metallated 2-pyridylthiophene
(Chart 3) [25].
NMe2
E
S
S
N
Pd
Pd
N3
Cl
L
P
E = S, Se
Fig. 2. Molecularstructure ofcomplex 4. Ellipsoidsshow 50%probabilitylevels. Hydrogen
atoms have been omitted for clarity. Selected bond distances [Å]: Pd(1)eC(1) 2.033(2),
Pd(1)eN(1) 2.0374(19), Pd(1)eS(1) 2.2383(6), Pd(1)eP(1) 2.351(6). Selected angles [ꢁ]:
C(1)ePd(1)eN(1) 81.56(9), C(1)ePd(1)eP(1) 94.56(7), C(1)ePd(1)eS(1) 163.96(7), N(1)e
Pd(1)eP(1) 173.72(6), N(1)ePd(1)eS(1) 82.42(6), P(1)ePd(1)eS(1) 101.46(2).
P = phosphine
L = N or P donor ligand
Chart 3.
In conclusion, we report here the facile cyclopalladation of some
2-acetylthiophene thiosemicarbazone ligands to give oligomeric
species, which react with mono- or dinuclear phosphines resulting
in monomeric Pd(II) phosphine complexes containing dianionic
[C,N,S]2ꢀ ligands. We are currently further examining the reactivity
of this type of complexes, focussing in particular on establishing the
exact structure of the oligomeric products and also investigating
the reactivity of the palladiumecarbon bond.
3. Experimental
3.1. General
1H, 13C, and 31P {1H} NMR spectra were recorded on a 400 MHz
Bruker Avance or 600 MHz Bruker Avance II spectrometer. Chem-
ical shifts are quoted relative to external SiMe4 (1H, 13C) and 85%
H3PO4 (
31P). Elemental analyses were performed by staff of the
Fig. 3. Molecular structure of complex 6. Ellipsoids show 50% probability levels.
Hydrogen atoms have been omitted for clarity. Only the ipso carbon atoms of the Ph2P
groups are shown. Selected bond distances [Å]: Pd(1)eC(1) 2.024(5), Pd(1)eN(1)
2.036(5), Pd(1)eS(1) 2.3094(15), Pd(1)eP(1) 2.2330(15). Selected angles [ꢁ]: C(1)e
Pd(1)eN(1) 82.0(2), C(1)ePd(1)eP(1) 97.12(18), C(1)ePd(1)eS(1) 164.58(18), N(1)e
Pd(1)eP(1) 174.79(12), N(1)ePd(1)eS(1) 82.92(13), P(1)ePd(1)eS(1) 97.67(6).
microanalytical laboratory of the University of Wuppertal. MALDI
mass spectra (AgOTf matrix) were run in the department of
analytical chemistry at the University of Wuppertal. All reactions
were carried out under aerobic conditions unless stated otherwise.
Fig. 4. Molecular structure of complex 8. Ellipsoids show 50% probability levels. Hydrogen atoms as well as the CHCl3 of solvation have been omitted for clarity. Only the ipso carbon
atoms of the Ph2P groups are shown. Selected bond distances [Å]: Pd(1)eC(1) 2.041(3), Pd(1)eN(1) 2.041(3), Pd(1)eS(1) 2.3303(10), Pd(1)eP(1) 2.2430(11). Selected angles [ꢁ]:
C(1)ePd(1)eN(1) 81.48(14), C(1)ePd(1)eP(1) 94.98(11), C(1)ePd(1)eS(1) 162.53(11), N(1)ePd(1)eP(1) 175.80(9), N(1)ePd(1)eS(1) 81.49(9), P(1)ePd(1)eS(1) 102.19(3).

H. Weiss, F. Mohr / Journal of Organometallic Chemistry 696 (2011) 3150e3154
3153
All chemicals and solvents (HPLC grade) were sourced commer-
cially and used as received.
the filtrate precipitated the product, which was isolated by filtra-
tion, washed with hexanes and dried in air.
3.2. General procedure for the preparation of the acetylthiophene
thiosemicarbazones
3.9. [Pd(L1) (PPh3)] (3)
0.022 g (40%) red solid. 31P {1H} NMR (162 MHz, CDCl3, 25 ꢁC):
A mixture of the appropriate thiosemicarbazide (2.00 g) and 2-
acetylthiophene (1 equivalent) in EtOH (80 mL) was heated to
reflux until all solids had dissolved. The solution was cooled to
room temperature and concentrated H2SO4 (0.1 ml) was added,
causing precipitation of the product. The mixture was left to stir
over night at room temperature before the solid was isolated by
filtration, washed with some cold EtOH and dried in air.
d
¼ 36.2. 1H NMR (400 MHz, CDCl3, 25 ꢁC):
¼ 7.56e7.66 (m, 6 H, o-
d
Ph3P), 7.44e7.50 (m, 3 H, p-Ph3P), 7.38e7.44 (m, 4 H, m-Ph3P), 6.83
(dd, J ¼ 4.8, 0.8 Hz, 1 H, H5), 5.80 (dd, J ¼ 4.8, 0.6 Hz, 1 H, H4), 5.13
(br. s, 2 H, NH2), 2.35 (s, 3 H, Me). Anal. calc. for C25H22N3S2PPd: C,
53.05; H, 3.92; N, 7.42. Found: C, 52.95; H, 3.86; N, 7.51%. X-ray
quality crystals were obtained by slow diffusion of hexane into the
CDCl3 NMR sample solution of the compound.
3.3. Acetylthiophene thiosemicarbazone (HL1)
3.10. [Pd(L2) (PPh3)] (4)
31
2.53 g (57%) pale yellow needles. 1H NMR (600 MHz, CDCl3,
0.021 g (38%) red solid. P {1H} NMR (162 MHz, CDCl3, 25 ꢁC):
25 ꢁC):
d
¼ 8.93 (br. s, 1 H, NH), 7.35 (d, J ¼ 5.0 Hz, 1 H, H5), 7.32 (d,
d
¼ 36.3. 1H NMR (400 MHz, CDCl3, 25 ꢁC):
¼ 7.55e7.66 (m, 6 H, o-
d
J ¼ 3.5 Hz, 1 H, H3), 7.31 (br. s, 1 H, NH2), 7.04 (dd, J ¼ 5.0/3.9 Hz, 1 H,
Ph3P), 7.36e7.51 (m, 7 H, p-Ph3P, m-Ph3P), 6.80 (dd, J ¼ 4.8, 0.8 Hz,
1 H, H5), 5.80 (dd, J ¼ 4.8, 0.6 Hz, 1 H, H4), 4.95 (br. s, 1 H, NH), 2.93
(d, J ¼ 5.0 Hz, 3 H, NHMe), 2.37 (s, 3 H, Me). Anal. calc. for
C26H24N3S2PPd: C, 53.84; H, 4.17; N, 7.24. Found: C, 54.03; H, 4.12;
N, 7.33%. X-ray quality crystals were obtained by slow diffusion of
hexane into the CDCl3 NMR sample solution of the compound.
H4), 6.52 (br. s, 1 H, NH2), 2.32 (s, 3 H, Me). 13C NMR (150 MHz,
CDCl3, 25 ꢁC):
d
¼ 178.4 (C]S), 144.2 (C]N), 142.4 (C2), 128.6 (C4),
127.9 (C5), 127.7 (C3), 14.1 (Me). Anal. calc. for C7H9N3S2 (199.30): C,
42.19; H, 4.55; N, 21.08. Found: C, 42.34; H, 4.29; N, 21.05%.
3.4. Acetylthiophene 4-methylthiosemicarbazone (HL2)
3.11. [Pd2(L1)2(m-dppe)] (5)
1.65 g (41%) pale yellow needles. 1H NMR (600 MHz, CDCl3,
25 ꢁC):
d
¼ 8.64 (s,1 H, NH), 7.47 (s,1 H, NHMe), 7.30 (d, J ¼ 5.0 Hz,1 H,
0.006 g (12%) red solid. 31P {1H} NMR (162 MHz, dmso-d6,
H5), 7.25 (d, J ¼ 3.6 Hz,1 H, H3), 7.00 (dd, J ¼ 4.8/4.0 Hz,1 H, H4), 3.22
25 ꢁC):
d
¼ 32.3. 1H NMR (400 MHz, dmso-d6, 25 ꢁC):
¼ 7.38e7.59
d
(s, 3 H, NMe), 2.24 (s, 3 H, Me). 13C NMR (150 MHz, CDCl3, 25 ꢁC):
(m, 20 H, Ph2P), 7.05 (d, J ¼ 4.8 Hz, 2 H, H5), 6.69 (br. s, 4 H, NH2),
5.74 (d, J ¼ 5.0 Hz, 2 H, H5), 2.62 (br. m, 4 H, PCH2CH2P), 2.21 (s, 6 H,
Me). Anal. calc. for C40H38N6S4P2Pd2: C, 47.76; H, 3.81; N, 8.36.
Found: C, 47.84; H, 3.96; N, 8.45%.
d
¼ 178.2 (C]S),142.7 (C]N),142.5 (C2),128.1 (C4),127.6 (C5),127.4
(C3), 31.4 (NMe), 13.8 (Me). Anal. calc. for C8H11N3S2 (213.32): C,
45.04; H, 5.20; N, 19.70. Found: C, 44.92; H, 5.29; N, 20.01%.
3.5. Preparation of the oligomeric cyclometallated Pd complexes
3.12. [Pd2(L2)2(m-dppe)] (6)
To a solution of K2PdCl4 (0.200 g, 0.613 mmol) in water (10 mL)
containing NaOAc (0.127 g, 1.55 mmol) was added the appropriate
acetylthiophene thiosemicarbazone (1 equivalent) in EtOH (40 mL)
and the mixture was stirred at room temperature for ca. 18e24 h.
The resulting dark precipitate was isolated by filtration, washed
with water, EtOH and Et2O and subsequently dried in air.
0.028 g (46%) orange solid. 31P {1H} NMR (162 MHz, dmso-d6,
25 ꢁC):
d
¼ 32.5. 1H NMR (400 MHz, dmso-d6, 25 ꢁC):
¼ 7.38e7.59
d
(m, 20 H, Ph2P), 7.04 (d, J ¼ 4.7 Hz, 2 H, H5), 6.95 (br. s, 2 H, NHMe),
5.72 (d, J ¼ 4.7 Hz, 2 H, H5), 2.79 (d, J ¼ 4.3 Hz, 6 H, NHMe), 2.59 (br.
m,
4 H, PCH2CH2P), 2.25 (s, 6 H, Me). Anal. calc. for
C42H42N6S4P2Pd2: C, 48.79; H, 4.09; N, 8.13. Found: C, 48.55; H,
4.21; N, 8.07%. X-ray quality crystals were obtained by slow evap-
oration of a dmso solution of the compound.
3.6. [Pd(L1)]n (1)
0.180 g (97%) of a black solid was obtained. 1H NMR (600 MHz,
3.13. [Pd2(L1)2(m-dppf)] (7)
dmso-d6, 25 ꢁC):
d
¼ 7.24 (d, J ¼ 4.7 Hz, 1 H, H5), 6.97 (d, J ¼ 4.7 Hz,
1 H, H4), 6.56 (br. s, 2 H, NH2), 1.78 (s, 3 H, Me). 13C NMR (150 MHz,
dmso-d6, 25 ꢁC):
0.051 g (89%) orange solid. 31P {1H} NMR (162 MHz, CDCl3,
d
¼ 166.9 (CeS), 150.1 (C]N), 141.5 (CePd), 131.9
25 ꢁC):
d
¼ 27.8. 1H NMR (400 MHz, CDCl3, 25 ꢁC):
¼ 7.48e7.54 (m,
d
(C4), 127.6 (C2), 123.8 (C5), 14.0 (Me). Anal. calc. for [C7H7N3S2Pd]n:
C, 27.68; H, 2.32; N, 13.84. Found: C, 27.99; H, 2.87; N, 13.68%.
8 H, o-Ph2P), 7.38e7.44 (m, 4 H, p-Ph2P), 7.29e7.34 (m, 8 H, m-
Ph2P), 6.81 (d, J ¼ 4.6 Hz, 2 H, H5), 5.66 (d, J ¼ 4.7 Hz, 2 H, H4), 5.13
(s, 4 H, Fc), 4.25 (s, 4 H, Fc), 2.98 (d, J ¼ 5.0 Hz, 6 H, NHMe), 2.36 (s,
6 H, Me). The NHMe proton was not observed. Anal. calc. for
C48H42N6S4P2FePd2: C, 49.62; H, 3.64; N, 7.23. Found: C, 49.30; H,
3.65; N, 7.26%.
3.7. [Pd(L2)]n (2)
0.154 g (79%) of a brownish solid which was insoluble in
common solvents was obtained. MALDI-MS (m/z): 1378.7
[{Pd(L2)}4 þ Ag]þ. Anal. calc. for [C8H9N3S2Pd]n: C, 30.24; H, 2.86; N,
13.23. Found: C, 29.98; H, 3.16; N, 13.62%.
3.14. [Pd2(L2)2(m-dppf)] (8)
0.040 g (72%) orange solid. 31P {1H} NMR (162 MHz, CDCl3,
3.8. Preparation of the cyclometallated phosphine complexes
25 ꢁC):
d
¼ 27.8. 1H NMR (400 MHz, CDCl3, 25 ꢁC):
¼ 7.48e7.54 (m,
d
8 H, o-Ph2P), 7.38e7.44 (m, 4 H, p-Ph2P), 7.29e7.34 (m, 8 H, m-
Ph2P), 6.81 (d, J ¼ 4.6 Hz, 2 H, H5), 5.66 (d, J ¼ 4.7 Hz, 2 H, H4), 5.13
(s, 4 H, Fc), 4.25 (s, 4 H, Fc), 2.98 (d, J ¼ 5.0 Hz, 6 H, NHMe), 2.36 (s,
6 H, Me). The NHMe proton was not observed. Anal. calc. for
C50H46N6S4P2FePd2: C, 50.47; H, 3.90; N, 7.06. Found: C, 50.30; H,
To a suspension of the Pd-oligomers (0.03 g) in CH2Cl2 (10 mL)
was added the appropriate phosphine and the mixture was left to
stir at room temperature for 18e24 h. The resulting redeorange
solution was filtered through a pad of Celite. Addition of hexanes to

3154
H. Weiss, F. Mohr / Journal of Organometallic Chemistry 696 (2011) 3150e3154
Table 1
Crystal data and refinement details of compounds 3, 4, 6 and 8.
3
4
6
8
Empirical formula
Colour
C50H44N6Pd2S4P2
Orange
1131.93
Triclinic
P-1
10.8151 (7)
13.5873 (9)
17.2165 (10)
95.070 (5)
97.432 (5)
107.612 (6)
2369.2 (3)
2
C26H24N3PdS2P
Orange
579.97
Triclinic
P-1
9.6012 (3)
9.8939 (3)
14.1739 (4)
75.862 (3)
77.441 (3)
71.267 (3)
1222.23 (7)
2
C21H21N3PdS2P
Orange
516.90
Triclinic
P-1
11.1120 (7)
12.1946 (9)
12.2405 (8)
115.192 (7)
102.082 (6)
102.923 (6)
1372.94 (16)
2
C27H25N3Cl6Fe0.5PdS2P
Orange
833.61
Triclinic
P-1
10.6414 (6)
11.2504 (7)
14.4648 (7)
72.003 (5)
88.990 (4)
78.606 (5)
1612.78 (15)
2
Mr, g molꢀ1
Crystal system
Space group
a, Å
b, Å
c, Å
ꢁ
ꢁ
ꢁ
a
,
b
,
g
,
V, Å3
Z
D
m
calc., g cmꢀ3
, mmꢀ1
1.587
1.046
2.364
1.523
1.250
0.896
1.717
1.492
F(000)
1144
882
522
832
Crystal size, mm3
0.08 ꢂ 0.03 ꢂ 0.01
2.87e29.66ꢁ
20108
0.16 ꢂ 0.14 ꢂ 0.10
3.37e29.50ꢁ
17047
0.05 ꢂ 0.03 ꢂ 0.02
3.17e29.43ꢁ
7881
0.08 ꢂ 0.04 ꢂ 0.01
2.96e29.32ꢁ
12973
q
range for data collection
Refl. collected
Independent refl.
Parameters
11127
579
5825
300
5304
255
7479
369
Goodness-of-fit
R1 (all data)
0.778
0.1657
0.1084
1.010/ꢀ1.030
0.744
0.0362
0.0952
1.257/ꢀ0.809
1.051
0.0780
0.1537
1.100/ꢀ0.689
0.820
0.0788
0.0731
0.892/ꢀ0.679
wR2 (all data)
Largest diff. peak/hole, e Åꢀ3
3.91; N, 7.14%. X-ray quality crystals were obtained by slow diffu-
sion of hexane into the CDCl3 NMR sample solution of the
compound.
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Diffraction data were collected at 150 K using an Oxford
Diffraction Gemini E Ultra diffractometer, equipped with an EOS
CCD area detector and a four-circle kappa goniometer. For the
data
collection
the
Mo
source
emitting
graphite-
monochromated Mo-K
a
radiation (
l
¼ 0.71073 Å) was used.
Data integration, scaling and empirical absorption correction
was carried out using the CrysAlis Pro program package [26]. The
structure was solved using Direct Methods or Patterson Methods
and refined by Full-Matrix-Least-Squares against F2. The non-
hydrogen atoms were refined anisotropically and hydrogen
atoms were placed at idealised positions and refined using the
riding model. All calculations were carried out using the
program Olex2 [27]. Important crystallographic data and
refinement details are summarised in Table 1. The asymmetric
unit of complex 6 contained severely disordered solvent mole-
cules, after several unsuccessful attempts to model this disorder,
the SQUEEZE routine was applied [28].
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F.M. gratefully acknowledges support from the Fonds der
Chemischen Industrie. We also thank the DFG for a grant to
purchase the diffractometer.
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Appendix. Supplementary material
CCDC 824982e824985 (compounds 3, 4, 6 and 8); contains the
supplementary crystallographic data for this paper. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
[28] A.L. Spek, Acta Cyst. A46 (1990) C34.