New crystal packing arrangements in radical cation salts of BEDT-TTF with [Cr(NCS)6]3- and [Cr(NCS)5(NH3)]2-

Article abstract of DOI:10.1016/j.poly.2015.07.013

BEDT-TTF forms three packing arrangement styles in its radical cation salts with [Cr(NCS)₆]^3- in two of which two trans-oriented isothiocyanate ligands penetrate the BEDT-TTF layers either at the point where a solvent (nit

Full text of DOI:10.1016/j.poly.2015.07.013

Polyhedron 102 (2015) 75–81
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
New crystal packing arrangements in radical cation salts of BEDT-TTF
3
ꢀ
2ꢀ
with [Cr(NCS)6] and [Cr(NCS) (NH )]
5
3
Andrew C. Brooks a,b, Lee Martin , Peter Day , William Clegg , Ross W. Harrington , John D. Wallis
a
b
c
c
a,
⇑
a
School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK
Department of Chemistry, University College London, Gower Street, London WC1H 0AJ, UK
School of Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
b
c
a r t i c l e i n f o
a b s t r a c t
BEDT-TTF forms three packing arrangement styles in its radical cation salts with [Cr(NCS)6]3ꢀ in two of
which two trans-oriented isothiocyanate ligands penetrate the BEDT-TTF layers either at the point where
a solvent (nitrobenzene) is incorporated in a stack of donors or by four donor molecules forming a ‘‘tube’’
motif to accept a ligand at each end along with a small solvent molecule in between (acetonitrile). The
Article history:
Received 30 April 2015
Accepted 7 July 2015
Available online 31 July 2015
2ꢀ
[Cr(NCS)
5
NH
3
]
ion forms a related crystal packing arrangement with BEDT-TTF with a reduction in
Keywords:
BEDT-TTF
Chromium complexes
Crystal packing
Radical cation salts
Electrocrystallisation
the number of ‘‘tube’’ motifs needed to accept an isothiocyanate ligand.
Ó 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://
creativecommons.org/licenses/by/4.0/).
1
. Introduction
Radical cation salts provide the opportunity to combine
honeycomb arrangement in the anion layer which is capable of
including a guest molecule within the honeycomb [10–14].
together in the same crystal lattice multiple physical properties
which may not usually be found together. The organic donor mole-
cule BEDT-TTF 1 has provided a large number of such salts, usually
in the form of segregated stacks of donor and anion molecules.
ꢀ
ꢀ
ꢀ
4
Typically a simple anion such as Cl , linear I
3
, tetrahedral BF
, or
ꢀ
octahedral PF
6
produce an array of packing arrangements of the
donor molecules which leads to a variety of conducting properties
such as metals, semiconductors, and superconductors [1–4]. The
inclusion of a layer of anions introduces the possibility of multi-
functionality. One of the main areas of focus has been the use of
magnetic anions to introduce localised magnetic moments into
The influence of chirality on the electromagnetic properties of rad-
ical cation salts is also very topical [15–18], and electrocrystallisa-
3
ꢀ
tion of BEDT-TTF with the racemic [Cr(C
chiral electrolyte has produced a family of semiconducting salts of
the formula (BEDT-TTF) AM(C .Guest (A = Na, NH ; M = Cr, Al)
containing a single enantiomer of [M(C [19–22]. Although
other chiral anions have been used with BEDT-TTF, e.g.,
2
4
O )
3
]
trianion from a
these materials. Halogenometallate anions of the type MX
M = Fe, Mn, Co, Zn; X = Cl, Br) [5–7] and MCl (M = Re and Ir) [8]
4
3
2
4
O )
3
4
(
6
3ꢀ
2 4 3
O ) ]
have produced a number of paramagnetic semiconducting salts
with BEDT-TTF while a number of salts have been obtained
3
ꢀ
0
ꢀ
ꢀ
[
Fe(croconate)
3
]
, [Cr(2,2 -bipy)(oxalate)
-tartrate)
2
] and TRISPHAT , most
from octahedral anions of type M(CN)
6
(M = Fe, Co, Cr) [9].
2ꢀ
are racemic and only the salt with [Sb
2
(
L
2
]
has an enan-
The most extensive family of BEDT-TTF salts containing
tiopure anion [23–25], and none has produced a family as extensive
magnetic anions are those containing tris(oxalato)metallate,
3
+
+
+
+
+
+
as that from tris(oxalate)metallate.
(
M
BEDT-TTF)
x
[(A)M (C
2 4 3 3 4
O ) ].Guest (A = K , H O , Li , Na , NH ;
3
ꢀ
3
+
6
Here we report some new salts of BEDT-TTF with [Cr(NCS) ]
= Fe, Cr Ga, Al, Co, Ru, Cu, Ge) in which the tris(oxalato)
2
ꢀ
and [Cr(NCS)
5
NH
3
]
obtained serendipitously in work aimed at
metallate anions along with the counter cation (A) produce a
combining BEDT-TTF with chiral metal complexes of chromium.
A few salts of BEDT-TTF with anions containing isothiocyanate
⇑
Corresponding author.
E-mail address: john.wallis@ntu.ac.uk (J.D. Wallis).
are known: the salt
behaviour down to a metal–insulator transition at 20 K, though
2 4
a-(BEDT-TTF) Cs[Co(NCS) ] shows metallic
http://dx.doi.org/10.1016/j.poly.2015.07.013
277-5387/Ó 2015 The Authors. Published by Elsevier Ltd.
This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
0

7
6
A.C. Brooks et al. / Polyhedron 102 (2015) 75–81
this salt has no close BEDT-TTF sulfur. . .SCN contacts [26] and
penetrate into the adjacent BEDT-TTF/nitrobenzene layers towards
nitrobenzene molecules. The corresponding solvate with benzoni-
trile rather than nitrobenzene has been reported [29]. Phase B,
+
ꢀ
(
2 2
BEDT-TTF) Cu(NCS) [27,28], in which the Cu and SCN ions form
a layer structure, shows superconductivity below ca. 10 K. Our
results will be set in the context of several known phases contain-
4 6 3
(BEDT-TTF) [Cr(NCS) ](CH CN), is totally different, and does not
3ꢀ
ing BEDT-TTF and [Cr(NCS)
a phase containing [Cr(NCS)
cated [32] to the Cambridge Structural Database [33].
6
]
[29–31], and the reinterpretation of
involve stack formation but involves four BEDT-TTF units forming
the sides of a long rectangular ‘‘tube’’ motif, and these ‘‘tubes’’
are then packed against each other to form layers. These layers
2ꢀ
5
NH
3
]
which had been communi-
3ꢀ
are separated by layers of [Cr(NCS)
6
]
anions, and a pair of
trans-oriented NCS ligands are inserted into ‘‘tube’’ units to either
side. Thus, each ‘‘tube’’ unit has a NCS ligand inserted at each end
and an acetonitrile molecule is trapped in the centre of the ‘‘tube’’.
A further phase, phase C, has been reported in the literature with
2
. Discussion
During work directed at preparing radical cation salts of BEDT-
TTF with chiral anions of type Cr(NCS)
4
L where L was a single
formula (BEDT-TTF)
5
[Cr(NCS)
6
]X where layers of stacked BEDT-
0
3ꢀ
enantiomer of (+)-BINOL or 4S-4-isopropyl-2-(2 -pyridyl)-1,3-oxa-
zoline, electrocrystallisation of BEDT-TTF with the ammonium
salts of these two chiral anions in nitrobenzene/acetonitrile led
to growth of two quite different phases, A and B respectively.
TTF units are separated by layers composed of [Cr(NCS)
and X, where
(X = 0.5(BEDT-TTF)) [30,31] or tetrabutylammonium cations and
6
]
anions
X
is either neutral BEDT-TTF molecules
+
4 9 4
THF molecules (X = (N(C H ) ).THF) [31]. In these cases, the addi-
3
ꢀ
These contain BEDT-TTF with [Cr(NCS)
6
]
with either nitroben-
tional components in the anion layers increase the thickness of
these layers, so that there is no need for BEDT-TTF stacks to be pen-
etrated by the NCS ligands. No coordinates were reported for either
of the two examples of phase C.
zene or acetonitrile, but no chiral components. Two examples of
a third phase, C, have been reported briefly in the literature
2ꢀ
[
5 3
30,31]. We also report a salt containing the [Cr(NCS) (NH )]
dianion, which was produced by a similar experiment to that
which produced phase B but using chlorobenzene/ethanol rather
than acetonitrile/nitrobenzene as solvent.
Finally, we report
a
salt containing the related dianion
)]2 which contains layers composed of ‘‘tube’’ units
ꢀ
[Cr(NCS)
5
(NH
3
(as described for phase B), with a pair of donors and a single donor
To pack layers of octahedral anions containing six projecting
ligands with layers of BEDT-TTF donors requires that two of the
ligands must penetrate the donor layers. The packing arrange-
ments of the BEDT-TTF units for phases A and B are shown in
all packed together. The ‘‘tube’’ unit contains solvent, and the layers
are separated by layers of [Cr(NCS) (NH )] anions and solvent. In
5 3
2ꢀ
our example the solvent is ethanol, and a very similar phase [32],
briefly communicated in the Cambridge Structural Database [33],
is reinterpreted here as the corresponding phase with dichloro-
methane as the solvent. Only the NCS ligand trans to the ammo-
nium ligand penetrates the ‘‘tube’’, hence the need for fewer
‘‘tube’’ motifs in the packing arrangement than in phase B.
4 6 2
Fig. 1. Thus, A has the composition (BEDT-TTF) [Cr(NCS) ].PhNO
in which the nitrobenzene and BEDT-TTF units are stacked
together, and layers composed of these stacks are separated by lay-
3ꢀ
ers of [Cr(NCS)
6
]
anions, two of whose trans oriented NCS groups
]3 trianion and (c) the phase formed with the [Cr(NCS)
ꢀ
2ꢀ
Fig. 1. Crystal packing arrangements of BEDT-TTF units in (a) phase A and (b) phase B containing the [Cr(NCS) NH ]
6
5
3
dianion. Solvents included in the ‘‘tube’’ units in (b) and (c) have been omitted for clarity.

A.C. Brooks et al. / Polyhedron 102 (2015) 75–81
77
4 6 2
2.1. (BEDT-TTF) [Cr(NCS) ].PhNO , phase A
X-ray diffraction data for the nitrobenzene solvate, phase A,
were collected using synchrotron radiation (k = 0.6942 Å) at
20 K. Crystals are monoclinic and in space group P2 with four
BEDT-TTF donor molecules, one Cr(NCS) anion and a nitrobenzene
1
1
6
molecule in the asymmetric unit. The crystal packing arrangement
is shown in Figs. 1(a), 2 and 3. The four crystallographically inde-
pendent donor molecules are aligned with their main axes roughly
parallel and organised in two pairs which pack along with the
nitrobenzene molecules in the ab plane (Fig. 1(a)). Adjacent planes
3
ꢀ
are separated by planes of [Cr(NCS)
6
]
counterions which insert
an isothiocyanate group into the spaces near the nitrobenzene
molecules in the two neighbouring planes (Fig. 2). The relative
3
ꢀ
arrangement of the planes of [Cr(NCS)
6
]
anions and planes of
BEDT-TTF and nitrobenzene molecules is shown in Fig. 3.
The four donors lie in two pairs (Fig. 1). One pair of donors lies
with the planes defined by their sulfur atoms nearly parallel (at
Fig. 3. View of the crystal packing of (BEDT-TTF)
4
[Cr(NCS)
6
].C
6
H
5
NO
2
viewed
approximately along the c axis with the b axis vertical, showing the layer of
3
ꢀ
[
Cr(NCS)
6
]
anions lying over the BEDT-TTF/nitrobenzene layer. The nitrobenzene
] anions.
2
.4°) and approximately face-to-face with four short Sꢁ ꢁ ꢁS contacts
between their TTF sulfur atoms in the range 3.4405(16)–
.6112(17) Å. This pair is sandwiched between nitro groups of
molecules lie directly behind the [Cr(NCS)
6
3
two solvent molecules. Calculations of the charges on these donors
from their molecular geometry following the procedure of
Guionneau et al. [34] gives values of +1.01 and +1.00, suggesting
they are a pair of monocations. The second pair of donors lies to
one side of the first pair and more distant from the solvent’s nitro
groups. The donors are almost parallel (at 0.61°) but there is a sig-
nificant sideways offset between the donors such that there are
only two short Sꢁ ꢁ ꢁS contacts between the TTF sulfur atoms of
method of Wang et al. [35] which are consistent with the oxidation
states for the donor molecules calculated from the X-ray crystal
structure.
Despite the presence of the nitrobenzene molecules in the donor
layers there is an extensive network of more than twenty short Sꢁ ꢁ ꢁS
contacts <3.6 Å between the pairs of donor molecules, with nine in
the range 3.3086(17)–3.3993(17) Å providing potential conduction
pathways in the ab plane. The pair of trans-oriented isothiocyanate
ligands which are directed towards nitrobenzene molecules are dis-
placed from the normal reasonably linear geometry at nitrogen by
angles of 27.1° and 17.3°. The isothiocyanate sulfur atoms make
Sꢁ ꢁ ꢁS contacts with donor molecules; the four ligands which do
not penetrate the donor stacks each make one (or, in one case,
two) Sꢁ ꢁ ꢁS contacts in the range 3.4870(17)–3.5961(16) Å, while
the other two ligands make longer Sꢁ ꢁ ꢁS contacts in the range
3
.6136(16) and 3.6390(16) Å. The calculated charges on these
donors are +1.13 and +0.24, i.e., one donor carries much less charge
than the other three. The sum of charges over the four donors is
+3.38, which, bearing in mind an error of ca. 0.1 in each calculation,
is similar to the anticipated total charge of +3. Confirmation of the
charge distribution was sought from Raman spectroscopic mea-
surements, which identified two peaks in the region in which the
active symmetric stretch for the central C@C occur. One broad peak
3
9
.6652(19)–3.7657(17) Å. Conductivity measurements in the range
6–298 K showed the crystal to be a semiconductor with a room
ꢀ1
was exhibited at
m
m
= 1430–1465 cm
and a minor peak at
= 1493–1497 cm , indicating the presence of BEDT-TTF mole-
cules in oxidation states +0.6–1.0 and +0.1–0.2 according to the
ꢀ
1
ꢀ3
ꢀ1
ꢀ5
temperature conductivity of 6.4 x 10 S cm falling to 2.6 x 10
at 100 K. The activation energy is estimated as 0.11 eV in the range
50–298 K, but at lower temperatures falls to 0.04 eV. The structure
is isomorphous with the (BEDT-TTF) Cr(NCS) .C CN structure
1
4
6
6 5
H
reported by Thétiot et al. [29] with just a change of included solvent.
The same pattern of charge distribution between the donor mole-
cules is also observed in this structure which shows a slightly higher
ꢀ2
ꢀ1
room temperature conductivity of 1.4 ꢂ 10 S cm with activa-
tion energy 0.24 eV.
4 6 3
2.2. (BEDT-TTF) [Cr(NCS) ](CH CN), phase B
The crystals of this acetonitrile solvate were triclinic in space
ꢀ
group P1. The unit cell comprises four BEDT-TTF donors, a
3
ꢀ
Cr(NCS)
6
anion and a molecule of acetonitrile, with two donors
crystallographically unique and the anion and solvent lying on
crystallographic centres of symmetry. Four parallel donor mole-
cules form the walls of a long ‘‘tube’’ oriented along the c axis of
the unit cell (Figs. 1(a) and 4). The angles between the planes of
the donors, defined by their eight sulfur atoms, are 69° and 111°.
3
ꢀ
Cr(NCS)
6
anions lie at each end of the ‘‘tube’’ and one isothio-
cyanate ligand from each of these anions is inserted into each
end of the ‘‘tube’’ (Figs. 4 and 5). An acetonitrile molecule is
trapped between the two terminal ligand sulfur atoms at the cen-
tre of the ‘‘tube’’, and is disordered across a centre of symmetry.
The Sꢁ ꢁ ꢁS contacts between the donor molecules forming the
‘‘walls’’ of the tube lie in the range 3.523(4)–4.147(4) Å, with the
Fig. 2. View of the crystal packing of (BEDT-TTF)
4 6 6 5 2
[Cr(NCS) ].C H NO viewed along
the axis with the axis vertical, showing how the anions direct two
a
b
isothiocyanate ligands towards the nitrobenzene molecules lying within the donor
stacks.

7
8
A.C. Brooks et al. / Polyhedron 102 (2015) 75–81
Fig. 4. The ‘‘tube’’-like packing motif in (BEDT-TTF)
left) and along ‘‘tube’’ axis (right).
CN), formed by four BEDT-TTF units capped by two Cr(NCS)3
ꢀ
4 6 3 6
[Cr(NCS) ](CH anions viewed perpendicular to ‘‘tube’’ axis
(
4 6 3
Fig. 5. Crystal packing arrangement for (BEDT-TTF) [Cr(NCS) ](CH CN).
shortest contacts involving at least one dithiin sulfur atom. ‘‘Tube’’
motifs lie side by side to complete the donor packing in the ab
plane. Two donors from the ‘‘walls’’ of the ‘‘tube’’ each make
face-to-face contacts with a donor of a neighbouring ‘‘tube’’ with
Sꢁ ꢁ ꢁS contacts of 3.765(3) and 3.769(3) Å between dithiol S atoms.
The other two donors from the ‘‘tube walls’’ each make side-to-side
contacts with two other donors with Sꢁ ꢁ ꢁS contacts between dithiin
sulfurs of 3.372(4) and 3.566(3) Å, and are oriented edge-to-face
with two further donor molecules with Sꢁ ꢁ ꢁS separations between
7 5 3 2
2.3. (BEDT-TTF) [Cr(NCS) (NH )] (solvent)
This phase, in space group P 1ꢀ , and with the modified anion
where one isothiocyanate is replaced by ammonia shows yet
another packing mode for the BEDT-TTF donors. The donors and
anions pack in parallel layers perpendicular to the c axis with sol-
vent included in both. The packing of the donors contains the
‘‘tube’’ motif which is provided by two pairs of centrosymmetri-
cally related donor molecules, along with a face-to-face cen-
trosymmetric dimer of donors and a single donor which lies
across another centre of symmetry, and is shown in
Figs. 1(c) and 6. ‘‘Tube’’ units are packed in lines in one direction,
but separated in the second direction by the centrosymmetric
donor, with the extra donor pair lying to either side of the latter
donor. Ethanol lies in the ‘‘tube’’ and is disordered across a centre
of symmetry at the middle of the tube, and a complex anion at each
end of the tube inserts an isothiocyanate ligand into the ‘‘tube’’.
The ammonia ligand lies trans to this isothiocyanate and adjacent
to the ends of the face-to-face donor pair in the next donor layer.
In the complex anion layer there are cavities located near the
ammonia ligands which are occupied by disordered solvent, etha-
nol and water. The nearest contacts to the ammonia hydrogen
dithiin sulfurs of 3.443(4) and 3.632(5) Å to one donor and
ꢀ
4
.161(5) and 4.199(5) Å to the other. The Cr(NCS)3
6
units lie in
the ab plane to either side of the donor plane, and the angles at
nitrogen on the complex anion lie in the range 168–172°. The
charges on the two crystallographically independent donors are
estimated from their molecular geometries to be +0.6 and +0.8,
so that for four donors the total charge is ca. +2.8, which counter-
balances the ꢀ3 charge of the anion. Stretches in the Raman spec-
ꢀ1
trum at 1416 and 1460 cm indicate charge states of +0.8 to +1.0
and +0.6 to +0.7, respectively, consistent with the results based on
molecular geometry. No resistivity measurements could be made
due the small size and fragile nature of the crystals. This type of
packing also occurs in two related materials: (BEDT-
TTF)
37], in both of which a disordered dichloromethane molecule is
located at the centre of the ‘‘tube’’.
4
[Fe(NCS)
6
].CH
2
Cl
2
[36] and (BEDT-TTF)
4
[Cr(NCSe)
6
].CH
2
Cl
2
atom are
a
Sꢁ ꢁ ꢁH contact (2.65 Å) to
a
neighbouring
2ꢀ
[
[Cr(NCS) NH ] ion, and a hydrogen bond to a partially occupied
5
3
water. The crystals were too fragile for conductivity measurements

A.C. Brooks et al. / Polyhedron 102 (2015) 75–81
79
7 5 3 2
Fig. 6. Left: packing arrangement of BEDT-TTF molecules in (BEDT-TTF) [Cr(NCS) NH ] .solvent, showing the ‘‘tube’’ motif (yellow and red donors), a pair of donors (blue)
and a single one lying on a centre of symmetry (pink), viewed down the c axis with the b axis vertical. The solvent in the ‘‘tubes’’ is omitted for clarity. Right: packing
arrangement showing how the complex anion layer directs a ligand alternately into opposite layers, and the positions of the ethanol molecules within the BEDT-TTF layer and
among the complex anions, viewed down the a axis with the b axis vertical (right). (Colour online.)
to be made. A further structure [32] communicated to the
Cambridge Structural Database, has been re-examined and found
to be the dichloromethane solvate analogue of this structure, con-
taining ordered dichloromethane in the solvent layer, and a further
dichloromethane molecule at the centre of the tube, and disor-
dered across a centre of symmetry. These are the first two exam-
ples of compounds containing this anion. The assignment of the
sixth ligand as ammonia in both structures is supported by the
under a nitrogen atmosphere for 12 h. Over the course of the reac-
tion, a colour change from pink to purple was observed. The reac-
tion mixture was cooled to room temperature, and evaporated
under reduced pressure to around 5 mL. Standing in the fridge
overnight afforded a precipitate, which was isolated by filtration
and dried in vacuo at room temperature to afford 2 (1.80 g, 97%)
as a purple solid, m.p. 188 °C (Found: C, 48.7; H, 3.5; N, 12.0.
4 14 2 4 max
[Cr(NCS) (C20H O )][NH ] requires: C, 49.0; H, 3.1; N, 11.9%); m
ꢀ1
Cr–NH
similar to that observed in (BEDT-TTF)
38] and other cases [39].
3
bond lengths (2.056(5) and 2.057(9) Å) which are very
(ATR)/cm 3509, 3432, 3153, 2077, 1617, 1595, 1511, 1383, 1318,
2
[Cr(NCS) (NH ] (2.07 Å)
4
3 2
)
1272, 1257, 1219, 1181, 1148, 1024, 823, 814, 748, 564.
[
3
. Conclusion
The need to accommodate an octahedral ion with side arms
0
4
.2. (S)-4-Isopropyl-2-(2 -pyridyl)-1,3-oxazoline [42]
L
-Valinol (0.7 g,
6.78 mmol), 2-cyanopyridine (0.71 g,
3
ꢀ
three atoms long in salts of BEDT-TTF with [Cr(NCS)
6
]
can be
6
.78 mmol) and a few crystals of 4-toluenesulfonic acid were
solved in several ways. Either two ligand side arms are inserted
into BEDT-TTF/aromatic solvent stacks at the points where the
smaller solvent molecules occur, or four BEDT-TTF molecules form
a channel to incorporate the side arms at either end, with the cen-
tral space filled by solvent. Alternatively, the anion layer is bulked
out with other molecules so that there are no protruding side arms
heated together in a conventional 800 W microwave oven for
min. The crude material was allowed to cool, and purified by
chromatography over silica eluting with ethyl acetate/methanol
15:1), affording the pyridyl oxazoline derivative (0.26 g, 20%) as
a colourless oil; d (400 MHz, CDCl ) 8.71 (1H, ddd, J = 4.9, 1.9,
.8 Hz, 6-H), 8.07 (1H, d, J = 7.9 Hz, 3-H), 7.78 (1H, dt, J = 7.8,
.8 Hz, 4-H), 7.39 (1H, ddd, J = 7.8, 4.9, 1.1 Hz, 5-H), 4.52 (1H, m,
2
(
H
3
0
1
4
5 3
to be accommodated. The novel [Cr(NCS) NH ] anion can be
accommodated by the donor layers which have adapted to contain
enough channels formed by four BEDT-TTF molecules to receive
the isothiocyanate ligand trans to the ammonia ligand.
Chromium(III) complexes are regarded to be kinetically very slow
to undergo substitution reactions, nevertheless this type of
behaviour has been observed before under electrocrystallisation
conditions where the cells are left for a week or more [40]. It is also
notable that enantiopure Cr(III)tris(oxalate) racemises during
electrocrystallisation [41]. Furthermore, the nature of electrocrys-
tallisation is that most stable arrangement of donor cations with
one of the anionic species are present in solution will be formed,
and the anions with the smaller ligands have been incorporated
more easily into the crystal structures.
0
0
0
-H), 4.22 (1H, dd, J = 8.2, 7.8 Hz, 5 -H
a b
), 4.17 (1H, m, 5 -H ), 1.90
(
1H, m, CHMe
2
), 1.06 (3H, d, J = 6.9 Hz, CH
(100 MHz, CDCl
46.9 (2 -C), 136.6 (4 -C), 125.4 (3 -C), 123.9 (5 -C), 72.9 (4-C),
3
), 0.95 (3H, d,
0
J = 6.9 Hz, CH
1
7
3
); d
C
3
) 162.5 (2-C), 149.7 (6 -C),
0
0
0
0
0.7 (5-C), 32.7 (CHMe
2
), 19.0 (CH
3
), 18.4 (CH
3
).
0
4
.3. Ammonium [chromium ((S)-4-isopropyl-2-(2 -pyridyl)-1,3-
oxazoline)tetra-thiocyanate], 3
0
(
S)-4-Isopropyl-2-(2 -pyridyl)-1,3-oxazoline (1.0 g, 5.3 mmol)
and Reinecke’s salt (1.77 g, 5.3 mmol) were heated to reflux in
acetonitrile (60 mL) under an atmosphere of nitrogen overnight.
The reaction was allowed to cool to room temperature, and the sol-
vent evaporated. Drying under high vacuum at room temperature
afforded 3 (2.58 g, 99%) as a purple gum (Found C, 36.5; H, 3.7; N,
4
. Experimental
4.1. NH [((+)BINOL)Cr(NCS) ], 2
4
4
1
9.9. C15
H
18CrN
7
OS
3151, 2964, 2053, 1651, 1593, 1526, 1414, 1392,
1256, 1166, 923, 749, 668, 480.
4 max
requires: C, 36.6; H, 3.7; N, 19.9%); m
ꢀ
1
Reinecke’s salt (1.0 g, 2.97 mmol) and (R)-(+)-2,2-bi(naphthol)
0.85 g, 2.97 mmol) in acetonitrile (40 mL) were heated to reflux
(ATR)/cm
(

8
0
A.C. Brooks et al. / Polyhedron 102 (2015) 75–81
4
.4. (BEDT-TTF)
4
[Cr(NCS)
6
].C
6
H
5
NO
2
of solvent in each compartment was allowed to equilibrate, and to
each side was inserted a platinum-tipped electrode. A constant
current of 1.0 A was applied across the cell for 11 days, affording
To the anodic side of an H-shaped electrochemical cell fitted
l
with a glass frit was placed BEDT-TTF (10 mg, 0.02 mmol), and to
dark blocks on the anode.
the cathodic side of the cell was added a solution of 2 (40 mg,
0
.07 mmol) in nitrobenzene/acetonitrile (50:50 v/v, 25 mL). The
4.9. X-ray crystallography for (BEDT-
level of solvent in each compartment was allowed to equilibrate,
and to each side was inserted a platinum-tipped electrode. A con-
7 5 3
TTF) [Cr(NCS) (NH )]
2 2
.2.74C H
5 2
OH.0.26H O
stant current of 0.2
lA was applied across the cell for 2 weeks,
Crystal data for 7(C10
H S
8 8
).2(Cr(NCS) (NH )).2.74(C H OH).
5 3 2 5
affording black blocks on the anode. These were harvested, washed
0.26(H
2
O): M = 3542.72, dark brown slab, 0.11 ꢂ 0.08 ꢂ
ꢀ1
3
with acetone and dried. m.p. 208 °C; Raman/cm
m
4
= 1430–1465
0.04 mm , triclinic, space group P 1ꢀ (No. 2), a = 12.5356(3),
ꢀ1
(
broad);
m
3
= 1493–1497 cm
.
b = 14.7829(4),
c = 19.3336(4) Å,
= 86.8200(10)°,
a
= 73.3040(10)°,
b =
Z = 1,
3
7
6.6790(10)°,
c
V = 3339.17(14) Å ,
3
4 6 6
4.5. X-ray crystallography for (BEDT-TTF) [Cr(NCS) ].C H
5
NO
2
c
D = 1.762 g/cm , F000 = 1804, Bruker-Nonius APEX II CCD diffrac-
tometer with Bruker-Nonius FR591 rotating anode and 10 cm con-
focal mirrors, = 0.71073 Å, T = 120(2) K, 2hmax = 55.5°, 98658
reflections collected, 15210 unique. Final GoF = 1.12, R = 0.069,
wR = 0.14, R indices based on 12333 reflections with F > 2
Synchrotron diffraction data were measured at the Daresbury
SRS station 9.8. Crystal data for 4(C10 ).Cr(NCS) .C NO
r
H
8
S
8
6
H
6 5
2
:
1
3
2
M = 2062.17, black block, 0.20 ꢂ 0.20 ꢂ 0.10 mm , monoclinic,
2
r
2
space group P2
1
(No. 4), a = 11.795(2), b = 20.144(4),
(refinement on F ), 737 parameters, 6 restraints. Semi-empirical
3
ꢀ1
c = 16.395(3) Å,
b = 101.03(3)°,
V = 3823.5(13) Å ,
Z = 2,
absorption corrections applied,
merohedral twin (3:1).
l
= 1.247 mm , refined as a non-
3
Dcalc = 1.791 g/cm , F000 = 2092, Bruker SMART APEX2 CCD diffrac-
tometer, synchrotron radiation, k = 0.6942 Å, T = 120(2) K,
max = 59.5°, 39216 reflections collected, 20865 unique
int = 0.0356). Final GOF = 1.119, = 0.0510, wR = 0.150,
indices based on 19698 reflections with F > 2 (refinement on
F ), 902 parameters, 2 restraints. Semi-empirical absorption cor-
2
h
7 5 3 2 2 2
4.10. X-ray crystallography for (BEDT-TTF) [Cr(NCS) (NH )] .3CH Cl
(R
R
1
2
R
2
r
The original data [32] were used for refinement of a model
which included a disordered dichloromethane molecule at the cen-
2
ꢀ1
rections applied,
l
= 1.142 mm . Refined as racemic twin (54:46).
tre of the ‘‘tube’’ motif. Crystal data: 7(C10
H
8
S
8
).2(Cr(NCS)
5
(NH
3
)).
ꢀ
All crystal structures were solved with SHELXS-86 [43] and
refined with SHELXL-97 [43], using the X-SEED interface [44].
Geometric analysis was made with PLATON [45], and illustrations
were made with MERCURY [46].
3(CH Cl ),
2
2
M
r
= 3666.16, triclinic, space group P1 (No. 2),
a = 12.553(3),
b = 14.766(3),
= 87.28(3)°,
c = 19.682(4) Å,
V = 3367.4(13) Å ,
a
= 71.61(3),
Z = 1,
= 0.043,
3
b = 76.67(3),
c
c
D =
3
1.808 g/cm , F000 = 1856, k = 0.71073 Å, T = 293(2) K, R
1
2
2
wR = 0.075, R indices based on 2544 reflections with F > 2r
2
(
refinement on F ).
4.6. (BEDT-TTF)
4 6 3
[Cr(NCS) ].CH CN
Acknowledgements
To the anodic side of an H-shaped electrochemical cell fitted
with a glass frit was placed BEDT-TTF (10 mg, 0.02 mmol), and to
the cathodic side of the cell was added a solution of 3 (40 mg,
We thank the EPSRC for a studentship (A.C.B.), the EPSRC
National Crystallography Service for datasets [47], STFC for access
to synchrotron facilities, and the EPSRC Mass Spectrometry
Service for measurements. We acknowledge the use of the
Chemical Database Service supported by the Royal Society of
Chemistry and EPSRC. J.W. thanks Profs E.C. Constable and C.
0
.07 mmol) in nitrobenzene/acetonitrile (50:50 v/v, 25 mL). The
level of solvent in each compartment was allowed to equilibrate,
and to each side was inserted a platinum-tipped electrode. A con-
stant current of 1.0
lA was applied across the cell for 1 week,
affording black needles on the anode. These were harvested,
ꢀ1
Housecroft for a study period at the University of Basel,
washed with acetone and dried, m.p. 211 °C; Raman/cm
ꢀ1
Switzerland. The work has benefited from support from ESF COST
action D35. We thank Mr Brian O’Neill for construction of constant
current sources.
m
4
= 1416,
3
m = 1460 cm .
4.7. X-ray crystallography for (BEDT-TTF) [Cr(NCS) ].CH CN
4 6 3
Appendix A.
Crystal data for 4(C10
H
8
S
8
).Cr(NCS)
6
.CH
3
CN: M = 1980.12, black
3
ꢀ
plate, 0.20 ꢂ 0.04 ꢂ 0.01 mm , triclinic, space group P1 (No. 2),
CCDC 1062492–1062494 contains the supplementary
crystallographic data for the three BEDT-TTF salts whose structures
are reported. These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: +44 1223 336 033; or e-mail: deposit@ccdc.cam.ac.uk.
a = 10.291(2),
b = 84.07(3)°,
b = 11.825(2),
= 67.26(3)°,
c = 16.738(3) Å,
a
= 86.55(3)°,
Z = 1,
3
c
V = 1868.1(7) Å ,
3
D
calc = 1.760 g/cm , F000 = 1974, Bruker-Nonius APEX II CCD diffrac-
tometer with Bruker-Nonius FR591 rotating anode and 10 cm con-
focal mirrors, k = 0.71073 Å, T = 120(2) K, 2hmax = 55.5°, 34511
reflections collected, 8565 unique (Rint = 0.074). Final GOF = 1.109,
2
R1 = 0.116, wR = 0.198, R indices based on 5822 reflections with
2
2
References
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ꢀ
1
pirical absorption corrections applied,
l
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.
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