A strategy for the build-up of transition-metal complexes containing tripodal [ArPOS2]2- and [ArPS3]2- ligands (Ar = 4-anisyl)

Article abstract of DOI:10.1039/b509117a

The investigation presents new synthetic methods for the generation of tripodal P/S ligands by reactions of metal alkoxides and carboxylates with the organoperthiophosphinic acid anhydride Lawesson's reagent. Four new transition-metal complexes containing various tripodal ligand sets were synthesised and characterised. The Royal Society of Chemistry 2005.

Full text of DOI:10.1039/b509117a

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F U L L P A P E R
A strategy for the build-up of transition-metal complexes containing
tripodal [ArPOS2]2− and [ArPS3]2− ligands (Ar = 4-anisyl)
Weifeng Shi,a Maryam Shafaei-Fallah,a Christopher E. Ansona and Alexander Rothenberger*a,b
a Institut fu¨r Anorganische Chemie der Universita¨t Karlsruhe, Geb. 30.45, Engesserstr. 15a,
D-76131, Karlsruhe, Germany. E-mail: ar252@chemie.uni-karlsruhe.de
b Institut fu¨r Nanotechnologie, Forschungszentrum Karlsruhe GmbH, Postfach 3640, D-76021,
Karlsruhe, Germany
Received 28th June 2005, Accepted 2nd September 2005
First published as an Advance Article on the web 14th September 2005
The investigation presents new synthetic methods for the generation of tripodal P/S ligands by reactions of metal
alkoxides and carboxylates with the organoperthiophosphinic acid anhydride Lawesson’s reagent. Four new
transition-metal complexes containing various tripodal ligand sets were synthesised and characterised.
(Scheme 1), the outcome of the reaction is markedly different
Introduction
when ethereal solvents are used. In the presence of DME
[Cu4(l4-ArPS3)2(PPh3)4] (1) is formed by asymmetric cleav-
age of Lawesson’s reagent together with tris-1,3,5-aryl-2,4,6-
trioxatriphosphinane-2,4,6-trisulfide [ArP(S)O]3 (Scheme 2).
The generation of metal complexes with phosphorus- and
sulfur- or selenium-containing ligands is a very active area
of research and it is hoped that as a result of these efforts,
materials with novel features will emerge.1,2 Stimulated by the
enormous progress made on the synthesis and application
of metal phosphonates,3 a wide variety of complexes has
been reported, where oxygen atoms of [RPO3]2− anions were
formally replaced with other functional groups e.g., RO, RS, S,
etc. The coordination chemistry of resulting sulfur-analogs to
known [P/O]-anions has been investigated intensively and some
recent work is now directed towards the development of metal
complexes containing [P/Se]-anions.4–8
The synthetic effort, usually involved in the generation of
a particular P/S ligand set is high and if materials based
on complexes with these ligands are to be discovered and
developed it is desirable to further explore the simple access
to these species. One easy synthetic approach to this type of
compounds involves the reaction of alkaline metal alkoxides
with the commercially available organoperthiophosphinic acid
anhydride Lawesson’s reagent [ArP(S)(l-S)]2 (Ar = 4-anisyl).9
The [ArPS2(OR)]− anions generated in the reaction commonly
act as bidentate chelate ligands and a range of metal complexes,
in which metal atoms are solely coordinated by S atoms of the
ligand, are reported.10 As part of a wider study of the reactivity of
copper(I) alkoxides we have shown that the reaction of CuOtBu
with Lawesson’s reagent produces a Cu(I) complex with the novel
ligand [ArS2P–O–PS2Ar]2− in high yield via ether elimination
(Scheme 1).11
Scheme
2
Synthesis of [Cu2(l4-ArPS3)(PPh3)2]2 (1) (DME
=
1,2-dimethoxyethane).
The formation of [ArP(S)O]3, which could be regarded
as a decomposition product of a hypothetical intermediate
[ArP(S)(OtBu)2], was confirmed by 31P NMR (dP 75 ppm, lit.,12
72 ppm). In the solid state 1 exists as a crystallographically-
centrosymmetric dimer of two [Cu2(ArPS3)(PPh3)2] units. The
Cu atoms exhibit tetrahedral coordination environments and
are coordinated by S atoms of [ArPS3]2− and P atoms of PPh3
ligands (Fig. 1).
Scheme 1 Reaction of CuOtBu with Lawesson’s reagent in toluene.
This somewhat surprising result prompted us to further in-
vestigate the ‘break-up’ of Lawesson’s reagent by late transition-
metal salts. Here we report results of these efforts and demon-
strate how metal alkoxides and carboxylates can be used for
the build-up of transition-metal complexes containing tripodal
[ArPOS2]2− and [ArPS3]2− ligands.
Fig. 1 Molecular structure of 1 in the solid-state. Atoms labelled
“A” are inversion-related equivalents at {1 − x, 2 − y, −z}. Selected
◦
˚
bond lengths (A) and angles ( ): Cu(1)–P(2) 2.2369(8), Cu(2)–P(3)
2.2257(9), Cu(1)–S(1) 2.3958(9), Cu(1)–S(2) 2.5585(13), Cu(1)–S(3)
2.2990(9), Cu(2)–S(2) 2.2672(8), Cu(2)–S(1A) 2.3465(9), Cu(2)–S(3)
2.7115(14), P(1)–S(1) 2.0450(13), P(1)–S(2) 2.0345(10), P(1)–S(3A)
2.0328(10); P–Cu–S 110.74(3)–116.96(4), S–Cu–S 82.56(3)–119.17(3),
S(3A)–P(1)–S(2) 116.92(5), S(3A)–P(1)–S(1) 110.38(4), S(2)–P(1)–S(1)
109.04(5), P–S–Cu 78.39(3)–115.38(4), Cu(2A)–S(1)–Cu(1) 109.84(3),
Cu(2)–S(2)–Cu(1) 69.47(2), Cu(1)–S(3)–Cu(2) 66.26(2).
Results and discussion
Whilst the nucleophilic attack of Lawesson’s reagent by
CuOtBu in toluene gave rise to the ligand [ArS2P–O–PS2Ar]2−
T h i s j o u r n a l i s
T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 5
D a l t o n T r a n s . , 2 0 0 5 , 3 9 0 9 – 3 9 1 2
3 9 0 9
©

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Bond lengths and angles within the tetranuclear cage complex
1 are similar to those observed in [Cu4(PhPS3)2(PMe3)5].6
The study of the nucleophilic ring-opening of Lawesson’s
reagent with CuOtBu under different conditions showed that
Cu(I) complexes containing the dianionic ligands [ArS2P–O–
PS2Ar]2− or [ArPS3]2− can be produced selectively by careful
selection of the reaction conditions. This limited study pointed
towards a more general approach, in which metal salts with
oxygen-containing anions could be used for similar ring-opening
reactions. This is in the following illustrated by the reactions
of CuOAc, Fe(OAc)2 and [Ni(OAc)2·4H2O] with Lawesson’s
reagent.
When CuOAc is reacted with Lawesson’s reagent (and PPh3)
in DME or toluene at elevated temperatures (reflux 4 h),
[Cu2(l2-ArS2P–O–PS2Ar)(PPh3)4] (Scheme 1) is formed in yields
of 68% together with acetic anhydride (dC 167, 22 ppm,
lit.,13 166, 21 ppm). At room temperature, however, [Cu14(l6-
ArP(O)S2)6(l3-ArP(O)(OAc)S)2(PPh3)6] (2) was isolated in good
yield (Scheme 3).
Fig. 2 Molecular structure of 2 in the solid-state (Ph groups at
P5,6,7 and symmetry-equivalent P atoms have been omitted); atoms
labeled with a prime are symmetry-equivalents at {1 − x, 1 − y, −z}.
◦
˚
Selected ranges of bond lengths (A) and angles ( ): Cu–O 2.020(6)–
2.153(5), Cu–P 2.218(2)–2.229(2), Cu–S 2.2287(18)–2.4144(18), P–O
1.497(5)–1.505(5), P(4)–O(9) 1.642(8), P–S 2.076(2)–2.090(2), P(4)–S(7)
1.982(3); S–Cu–S (Cu coordination number three) 110.55(7)–128.56(7),
S–Cu–S (Cu coordination number four) 100.04(8)–132.05(7),
O–Cu–P 97.88(15)–113.3(2), O–Cu–S 95.29(16)–123.26(16), P–Cu–S
104.28(8)–126.00(9), O(7)–P(4)–O(9) 102.3(5), O(7)–P(4)–S(7) 120.1(3),
O(9)–P(4)–S(7) 107.7(3).
Scheme 3 Synthesis of 2.
the general applicability of this synthetic route for the synthesis
of tripodal P/S ligands. In the case of Fe(OAc)2 these efforts
resulted in the formation of [Fe2(l-ArPS3)(thf)4] (3) (Scheme 4,
Fig. 3).
Although NMR investigations of 2 were precluded by
its poor solubility, the compound could be unequivocally
characterised by IR spectroscopy in combination with X-ray
analysis and elemental analysis. The formation of 2 could be
rationalised by the nucleophilic addition of four equivalents
of CuOAc to Lawesson’s reagent, followed by the elimination
of acetic anhydride (verified by 13C NMR of the mother-
liquor) and copper(I) thioacetate [Cu(I)SOCCH3]. The latter
elimination product, however, is formed in low yield and it
was impossible to obtain direct evidence for its formation
by IR or NMR studies. In the solid state 2 consists of a
crystallographically-centrosymmetric arrangement of fourteen
Cu+ ions, six [ArP(O)S2]2−, two [ArP(O)(OAc)S]− anions and six
PPh3 ligands (Fig. 2).
Scheme 4 Synthesis of 3.
Above the six faces of the central distorted cubic arrangement
(indicated by open dashed connections between Cu atoms in
Fig. 2) six [ArP(O)S2]2− anions are located. The S atoms of
each [ArP(O)S2]2− ligand coordinate four Cu atoms of one of
the cubic faces in l2-mode. One of the S atoms is coordinated
to an additional Cu atom (located to the right and left of the
central cubic [Cu8] arrangement). In Fig. 2 the coordination of
the [ArP(O)S2]2− anions can best be rationalised by looking at
P(2) or P(3). In the periphery of 2, two [ArP(O)(OAc)S]− anions
are coordinated to three Cu atoms. In contrast to the inner eight
three-coordinate Cu atoms the outer Cu atoms Cu(4,6,7) and
symmetry equivalents are tetrahedrally surrounded by O and
S atoms and additional PPh3 ligands. Bond lengths and angles
found in 2 are not unusual and can be compared with those
reported for other metal complexes containing P/S ligands.5
A remarkable feature of 2, however, is the formation of the
[ArP(O)(OAc)S]− anion. It is to the best of our knowledge
the first time that such a substitution pattern is observed for
P atoms in an anionic fragment. The long P(4)–O(9) distance of
Fig. 3 Molecular structure of 3 in the solid-state. Atoms labelled
with A are symmetry-equivalents at {−x, −y, −z}. Selected bond
◦
˚
lengths (A) and angles ( ): P(1)–S(1) 2.015(3), P(1)–S(3A) 2.024(3),
P(1)–S(2) 2.047(3), Fe(1)–O(2) 2.138(6), Fe(1)–O(3) 2.145(7), Fe(1)–S(3)
2.512(3), Fe(1)–S(1) 2.524(3), Fe(1)–S(2) 2.584(2), Fe(1)–S(2A) 2.599(2);
O(2)–Fe(1)–O(3) 87.3(3), O(2)–Fe(1)–S(3) 95.91(19), O(2)–Fe(1)–S(2A)
91.1(2), O(2)–Fe(1)–S(2) 170.23(19), S(3)–Fe(1)–S(1) 172.75(10),
S(3)–Fe(1)–S(2A) 79.83(8), S(1)–P(1)–S(3A) 115.65(13), S(1)–P(1)–S(2)
107.03(14), S(3A)–P(1)–S(2) 107.34(14).
In the solid state 3 exists as a centrosymmetric dimer (Fig. 3).
1.642(8) A is typical for P–O(carboxylate) bonds [lit.,14 1.643(5)
All the sulfur atoms are involved in metal bonding. The P–S
˚
˚
˚
and 1.662(7) A] and indicates the lability of this bond. Other
bond to S(2) is slightly longer [P(1)–S(2) 2.047(3) A] than P–S
˚
P–O distances in 2 are considerably shorter (ca. 1.5 A).
bonds to non-bridging S atoms [P(1)–S(1) 2.015(3), P(1)–S(3A)
2.024(3)]. The geometry at iron is distorted octahedral, with Fe–
Further reactions with other transition-metal carboxylates
and Lawesson’s reagent were carried out in order to demonstrate
˚
S bond lengths of 2.512(3)–2.599(2) A and Fe–O bond distances
3 9 1 0
D a l t o n T r a n s . , 2 0 0 5 , 3 9 0 9 – 3 9 1 2

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˚
Conclusion
to the cis THFs of 2.138(6) and 2.145(7) A. The generation of
the [ArPS3]2− anion follows the reaction mechanism outlined for
1 with the only difference being the formation of the leaving
group Ac2O instead of tBu2O.
The study shows that the late transition-metal alkoxide CuOtBu
can be employed in nucleophilic ring-opening reactions of
Lawesson’s reagent providing selective access to the tripodal
ligands [ArS2P–O–PS2Ar]2− and [ArPS3]2−. The use of transition-
metal carboxylates in analogous reactions for the first time has
proven to be an interesting alternative allowing the synthesis of
metal complexes containing [ArPOS2]2− or [ArPS3]2− anions. By
a combination of NMR and X-ray crystallographic studies a
first insight into the reaction mechanisms was gained. Work in
progress focuses on the synthesis of further examples of metal
complexes containing [ArPOS2]2− anions and the determination
of their physical properties, e.g., magnetic behaviour and thermal
decomposition.
For future work it was important to probe the sen-
sitivity of the reactions to water by employing hydrated
metal carboxylates as starting materials in ring-opening re-
actions of Lawesson’s reagent. As a first result of these
efforts [Ni2{ArP(O)S2}2(thf)2(H2O)2]2 (4) was obtained using
[Ni(OAc)2·4H2O] as starting material. Although crystals of 4
were generally twinned and of poor quality, it was possible
to establish the basic connectivity by X-ray crystallographic
analysis (Scheme 5, Fig. 4).
Experimental
Scheme 5 Synthesis of 4.
All operations were carried out in an atmosphere of purified
dinitrogen. All solvents were dried over the appropriate drying
agent and freshly distilled prior to use. Lawesson’s reagent,
dppm, PPh3, Fe(OAc)2 and [Ni(OAc)2·4H2O] were purchased
from Aldrich and used without further purification. CuOtBu and
CuOAc were prepared according to published procedures.19,20
Crystals were dried under reduced pressure prior to analysis.
Yields given are optimized by fractionated crystallisation.
1: A mixture of Lawesson’s reagent 202 mg (0.50 mmol) and
CuOtBu 136 mg (1.00 mmol) was dissolved in 15 mL DME. The
yellow–brown solution was heated to reflux for 4 h during
which time the formation of a yellow precipitate was observed.
The precipitate dissolved upon addition of a solution of PPh3
(524 mg, 2.00 mmol) in 8 mL DME. The solvent was removed
under reduced pressure. Addition of CH2Cl2 (3 mL) and pentane
(4 mL) and storage of the solution at RT for 2 days produced
colorless crystals of 1. 0.35 g, yield 72%. Mp 197 ◦C. Found:
C, 53.8; H, 3.9. C88H78Cl4Cu4P6S6O2 requires C, 54.4; H, 4.0%;
mmax/cm−1 (KBr) 3051 w, 1589 s, 1430 s (P–C), 1246 s, 689 s (P S);
=
dH (400 MHz, CDCl3, 25 ◦C) 8.0–7.9 (4H, dd, J = 7.6 Hz, aryl
H), 7.4–7.3 (60H, m, aryl H), 6.7 (4H, d, J = 7.6 Hz, aryl H), 3.8
◦
(3H, s, OCH3); dC (100 MHz, CDCl3, 25 C) 161.6–113.0 (8C,
◦
aryl C), 55.3 (1C, s, OCH3); dP (162 MHz, CDCl3, 25 C, 65%
H3PO4) 91.0 (s, ArPS3), −3.37 (s, PPh3).
Fig. 4 Molecula◦r structure of 4 in the solid-state. Selected bond lengths
˚
2: A mixture of Lawesson’s reagent 202 mg (0.50 mmol) and
CuOAc 246 mg (2.00 mmol) was dissolved in 8 mL THF. The
mixture was stirred for about 2 h at room temperature, during
which time the formation of a yellow precipitate was observed.
The mixture was filtered and the residue dissolved by addition
of a solution of PPh3 (0.4 M in thf, 2.50 mL). Solvent diffusion
(A) and angles ( ): Ni–S 2.213(5)–2.269(4), Ni–O(ligand) 1.993(13)–
2.086(14), Ni–O(H2O) 2.036(15)–2.103(12), Ni–O(thf) 2.093(14)–
2.115(12), P–S 2.037(6)–2.096(6), P–O 1.482(12)–1.556(12), S · · · H
[H2O ligands O(13)–O(16)] ca. 2.5; S(3)–Ni(1)–S(2) 176.6(2),
S(3)–Ni(1)–S(1) 93.39(17), S(1)–Ni(1)–S(4) 177.5(2), S(8)–Ni(2)–S(6)
92.07(18), S(8)–Ni(2)–S(5) 179.4(2), S(6)–Ni(2)–S(7) 177.3(2), O(5)–
Ni(3)–O(1) 177.7(5), O(13)–Ni(3)–O(10) 177.0(6), O(14)–Ni(3)–O(9)
177.0(6), O(7)–Ni(4)–O(3) 179.0(5), O(15)–Ni(4)–O(12) 179.3(6),
O(16)–Ni(4)–O(11) 176.8(5), O–P–S 114.0(5)–117.5(6), S–P–S
96.7(3)–97.7(2).
◦
within a double-Schlenk tube of Et2O (0 C) into the reaction
mixture (RT) produced light yellow crystals of 2 after 4 days.
0.32 g, yield 60%. Mp 193 ◦C (decomp.). Found: C, 47.1; H, 3.6.
C168H152Cu14O20P14S14 requires C, 47.3; H, 3.6%; mmax/cm−1 (KBr)
=
In the solid state 4 exists as a dimer of a square-planar
and an octahedrally coordinated Ni2+ ion held together by two
[ArP(O)S2]− ions. Inside the cyclic arrangement four molecules
of water are located, coordinating the octahedral Ni2+-centres.
3047 w, 1755 m (C O), 1591 s, 1433 s (P–C), 1173 s, 1094 br s,
=
691 s (P S).
3: A mixture of Lawesson’s reagent 202 mg (0.50 mmol)
and anhydrous Fe(OAc)2 174 mg (1.00 mmol) was dissolved
in 10 mL THF. The brown solution was stirred for 5 h at room
temperature. The slightly cloudy solution was filtered and the
filtrate layered with 15 mL Et2O. Storage of the solution at RT
for 4 days produced yellow crystals of 3. 0.18 g, yield 83%. Mp
>300 ◦C. Found: C, 39.5; H, 4.0. C30H46Fe2O6P2S6 (–C4H8O)
requires C, 39.2; H, 4.8%; mmax/cm−1 (KBr) 2936 w, 1597 s, 1439 s
˚
Similar Ni–O(P) bond distances of ca. 2.0 A to the ones found
in 4 have been observed in related methyldiphosphonato and
organophosphato Ni-complexes.15 Weak hydrogen bonds to all
16
˚
S atoms are observed with H · · · S distances of ca. 2.5 A.
Remarkably, 4 is not sensitive to HOAc formed in the course
of the reaction (dC 172, 20 ppm, lit.,17 175, 20 ppm) and
water. Complex 4 represents the first example of a mixed high-
spin/low-spin d8-Ni2+ complex stabilised by a tripodal P/S-
ligand. The formation of such a high-spin/low-spin complex
has been favoured by the hybrid nature of the ligand, with
both hard and soft functionalities. Similar arrangements of
tetranuclear square-planar/octahedral Ni2+ complexes have so
far only proved accessible by ligand design involving multiple
reaction steps.18
=
(P–C), 1258 s, 915 br s, 658 s (P S).
4: A mixture of Lawesson’s reagent 202 mg (0.50 mmol) and
[Ni(OAc)2·4H2O] 250 mg (1.00 mmol) was dissolved in 8 mL
THF. The resulting purple solution was stirred for about 5 h at
room temperature. The solution was layered with 15 mL Et2O
and stored at RT for 3 days producing purple crystals of 4.
0.20 g, yield 54%. Mp >300 ◦C (decomp.). Found: C, 35.9;
H, 4.5%. C44H68Ni4O16P4S8 requires C, 36.0; H, 4.7; UV (Nujol
D a l t o n T r a n s . , 2 0 0 5 , 3 9 0 9 – 3 9 1 2
3 9 1 1

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Table 1 Details of the X-ray data collection and refinements
Compound
1
2
3
4
Formula
Formula weight
T/K
C86H74Cu4O2P6S6·2CH2Cl2
C168H152Cu14O20P14S14·8thf
C30H46Fe2O6P2S6
868.67
205(2)
Monoclinic
P21/c
10.760(1)
17.020(2)
11.300(1)
90
109.91(1)
90
1945.7(1)
2
C44H68Ni4O16P4S8
1468.18
120(2)
Orthorhombic
Pna21
26.921(5)
13.001(3)
18.206(4)
90
90
90
6372(2)
4
1.585
1941.64
173(2)
Monoclinic
P21/c
4839.71
120(2)
Crystal system
Space group
Triclinic
¯
P1
˚
a/A
12.960(3)
22.853(5)
15.976(3)
90
113.02(3)
90
4354.9(15)
2
1.387
17.1353(9)
19.6186(10)
20.0847(11)
95.756(4)
111.961(4)
113.646(4)
5481.6(5)
1
˚
b/A
˚
c/A
a/◦
b/◦
c /◦
3
˚
V/A
Z
l/mm−1
1.625
1.188
F(000)
1984
28160
10288
0.0364
506
0.1555
0.0437
2480
42933
21979
0.0589
1098
0.2526
0.0799
904
8829
3680
0.1237
208
0.2225
0.0687
3040
35061
13469
0.1692
657
0.3167
0.1262
Reflections collected
Unique data
Rint
Parameters
wR2 (all data)
R1 [I > 2r(I)]
mull) kmax/nm 253, 340, 652; mmax/cm−1 (KBr) 3374 br s (H2O),
G. Yucesan, V. Golub, C. J. O’Connor and J. Zubieta, Dalton Trans.,
2005, 2241; S. Langley, M. Helliwell, J. Raftery, E. I. Tolis and R. E. P.
Winpenny, Chem. Commun., 2004, 142.
=
2962 w, 1594 s, 1440 s (P–C), 878 br w, 654 s (P S); dH (400 MHz,
d6-DMSO, 25 ◦C) 8.3 (8H, s, br, aryl H), 6.9 (8H, s, br, aryl H),
3.8 (12H, s, OCH3), 3.6 (16H, s, THF), 2.5 (16H, s, THF), 1.7
(8H, s, H2O); dP(162 MHz, d6-DMSO, 25 ◦C, 65% H3PO4) 56.1
(s, ArPS2O).
4 I. Haiduc, J. Organomet. Chem., 2001, 623, 29.
5 G. A. Zank and T. B. Rauchfuss, Organometallics, 1984, 3, 1191;
M. C. Aragoni, M. Arca, F. Demartin, F. A. Demillanova, F.
Isaia, V. Lippolis and G. Verani, Inorg. Chim. Acta, 2005, 358, 213;
Z. Weng, W. K. Leong, J. J. Vittal, J. Jagadese and L. Y. Goh,
Organometallics, 2003, 22, 1645; V. G. Albano, M. C. Aragoni, M.
Arca, C. Castellari, F. Demartin, F. A. Devillanova, F. Isaia, V.
Lippolis, L. Loddo and G. Verani, Chem. Commun., 2002, 1170; W. E.
Van Zyl, R. J. Staples and J. P. Fackler, Inorg. Chem. Commun, 1998, 1,
51.
6 D. Fenske, A. Rothenberger and M. Shafaei-Fallah, Z. Anorg. Allg.
Chem., 2004, 630, 943.
7 M. Shafaei-Fallah, C. E. Anson, D. Fenske and A. Rothenberger,
Dalton Trans., 2005, 2300, and references therein.
Crystallography
Data were measured on STOE K4MCCD/SAPPHIRE (1), IPDS I
(3) and IPDS II (2, 4) diffractometers, using Mo-Ka radiation.
The structures were solved by direct methods, and refined
by full-matrix least-squares against F2 using all data (see
Table 1 for details).21 Organic hydrogen atoms were placed in
idealized positions. Most ordered non-H atoms were refined with
anisotropic thermal parameters; the disordered methyl carbon
atoms C7 and C7A in 1 and disordered atoms of lattice solvent
molecules were refined isotropically. In 2, the final Fourier map
indicated the presence of an additional solvent molecule which
appeared to be badly disordered diethyl ether. Attempts to refine
various restrained versions of it failed and it was finally omitted.
The larger than expected final difference peaks in the structure
refer to partial atoms from this solvent molecule. Crystals of
4 are of poor quality and twinned to varying extents. Despite
many attempts to synthesize single crystals of 4 from a variety
of solvents, it was not possible to obtain a dataset of better
quality than that used here. A consequence of this twinning is
the presence of peaks in the final difference map corresponding
to “ghosts” of the Ni atoms.
8 I. P. Gray, A. M. Z. Slawin and J. D. Woollins, Dalton Trans., 2005,
2188.
9 B. S. Pedersen, S. Scheibye, K. Clausen and S. O. Lawesson, Bull.
Soc. Chim. Belg., 1978, 87, 293.
10 I. P. Gray, A. M. Z. Slawin and J. D. Woollins, Dalton Trans., 2004,
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CCDC reference numbers 276586–276589.
See http://dx.doi.org/10.1039/b509117a for crystallographic
data in CIF or other electronic format.
Acknowledgements
We thank the DFG Center for Functional Nanostructures
(W. S.) and the Forschungszentrum Karlsruhe (A. R.) for
financial support. A. R. thanks Prof. D. Fenske for his support.
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3 9 1 2
D a l t o n T r a n s . , 2 0 0 5 , 3 9 0 9 – 3 9 1 2