Donor atom set and spin state of iron(II). Bis(ligand)iron(II) and bis(ligand)nickel(II) complexes of 2,2′-bipyridine-6-carbothioamide and 2,2′-bipyridine-6-carboxamide

Article abstract of DOI:10.1071/C97071

2,2′-Bipyridine-6-carbothioamide (bpytm) and 2,2′-bipyridine-6-carboxamide (bpyam) are NNS and NNO donors, respectively, in their cationic bis(ligand)iron(II) and bis(ligand)nickel(II) complexes. The former ligand provides the stronger field and salts of [Fe(bpytm)₂]²⁺ have a singlet ground state, while those of [Fe(bpyam)₂]²⁺ have a quintet ground state. The magnetism and the electronic and Moessbauer spectra of salts of these cations have been measured. The low-temperature Moessbauer spectra of iron(II) complex salts of the carboxamide indicate, for the perchlorate and triflate salts, but not for the fluoroborate salt, a partial transition to singlet-state species. The mode of coordination of the ligands is indicated by infrared spectral data and has been confirmed by determination of the structures of [Ni(bpytm)₂] Cl₂.4H₂O, [Ni(bpyam)₂] [BF₄]₂.H₂O and [Fe(bpyam)₂] [BF₄]₂. In addition, the structures of the free ligands have been determined. Hydrogen bonding is present in the free ligands and their complexes. 2,2′-Bipyridine-6-carbothioamide: monoclinic, space group p2₁/c, a 8.265(3), b 11.175(2), c 11.114(4) A, β 94.47(2)°, Z 4. 2,2′-Bipyridine-6-carboxamide: monoclinic, space group P2₁/c, a 13.581(2), b 9.926(1), c 16.824(3) A, β 116.481(7)°, Z 8. [Ni(bpytm)₂] Cl₂.4H₂O: triclinic, space group P1, a 9.291(5), b 12.426(7), c 13.425(7) A, α 113.54(3), β 95.63(3)°, γ 94.43(3)°, Z 2. [Ni(bpyam)₂][BF₄]₂.H₂O: triclinic, space group P1, a 10.663(5), b 10.861(6), c 12.799(6) A, α 68.70(4), β 77.84(4), γ 78.47(4)°, Z 2. [Fe(bpyam)₂] [BF₄]₂: orthorhombic, space group P bcn, a 12.317(6), b 12.609(4), c 16.644(8) A, Z 4.

Full text of DOI:10.1071/C97071

C S I R O P U B L I S H I N G
Australian Journal
of Chemistry
Volume 51, 1998
© CSIRO Australia 1998
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Aust. J. Chem., 1998, 51, 273–284
.
Donor Atom Set and Spin State of Iron(II).
Bis(ligand)iron(II) and Bis(ligand)nickel(II)
Complexes of 2,20-Bipyridine-6-carbothioamide
and 2,20-Bipyridine-6-carboxamide
Bradley J. Childs,A John M. Cadogan,B Donald C. Craig,A
Marcia L. Scudder A and Harold A. Goodwin A
A
School of Chemistry, University of New South Wales, Sydney, N.S.W. 2052.
School of Physics, University of New South Wales, Sydney, N.S.W. 2052.
B
2,20-Bipyridine-6-carbothioamide (bpytm) and 2,20-bipyridine-6-carboxamide (bpyam) are NNS and
NNO donors, respectively, in their cationic bis(ligand)iron(II) and bis(ligand)nickel(II) complexes. The
former ligand provides the stronger eld and salts of [Fe(bpytm)2]2+ have a singlet ground state,
while those of [Fe(bpyam)2]2+ have a quintet ground state. The magnetism and the electronic and
Mossbauer spectra of salts of these cations have been measured. The low-temperature Mossbauer
spectra of iron(II) complex salts of the carboxamide indicate, for the perchlorate and tri ate salts, but
not for the uoroborate salt, a partial transition to singlet-state species. The mode of coordination
of the ligands is indicated by infrared spectral data and has been con rmed by determination of the
structures of [Ni(bpytm)2] Cl2.4H2O, [Ni(bpyam)2] [BF4]2.H2O and [Fe(bpyam)2] [BF4]2. In addition,
the structures of the free ligands have been determined. Hydrogen bonding is present in the free ligands
and their complexes. 2,20-Bipyridine-6-carbothioamide: monoclinic, space group P 21/c, a 8 265(3), b
11 175(2), c 11 114(4) A,
P 21/c, a 13 581(2), b 9 926(1), c 16 824(3) A, 116 481(7) , Z 8. [Ni(bpytm)2] Cl2.4H2O: triclinic,
space group P 1, a 9 291(5), b 12 426(7), c 13 425(7) A, 113 54(3), 95 63(3), 94 43(3) , Z
2. [Ni(bpyam)2][BF4]2.H2O: triclinic, space group P 1, a 10 663(5), b 10 861(6), c 12 799(6) A,
68 70(4), 77 84(4), 78 47(4) , Z 2. [Fe(bpyam)2] [BF4]2: orthorhombic, space group P bcn, a
12 317(6), b 12 609(4), c 16 644(8) A, Z 4.
94 47(2) , Z 4. 2,20-Bipyridine-6-carboxamide: monoclinic, space group
Introduction
phenanthroline-2-carbothioamide produces purely sin-
glet state bis(ligand)iron(II) complexes with an N4S2
donor atom set, while the corresponding complex of
the amide (N4O2 donor atom set) has a quintet
ground state.2,3 The corresponding complex from 1,10-
phenanthroline-2-carboxylate, which also contains an
N4O2 set, similarly is high spin.4 Coordination of the
thioamide sulfur or amide oxygen atom was estab-
lished from infrared spectral data, though no crystal
structure data were obtained. The change in spin
state with change in donor atom sequence from N4S2
to N4O2 can be associated with the relatively high
polarizability and nephelauxetic e ect of coordinated
sulfur, together with its -acceptor character, all of
which will tend to favour spin-pairing in iron(II).5
In coordinated bidentate systems a consistent, though
less marked, trend has been observed. Thus the
tris(ligand)iron(II) complex of pyridine-2-carboxamide
(N3O3 set) is high spin,2 while for the correspond-
The spin state of iron(II) in [FeIIN6] systems can
be controlled with considerable con dence by the
incorporation of appropriate electronic or steric in u-
ences into the ligand system. Variation of the donor
atom set may also e ect a spin state change, but
for a particular set, change in spin state is less
readily achieved than for [FeIIN6] species. Thus the
[FeIIN4O2] system, for example, has been found to
be almost invariably high spin. A notable recent
exception is the complex containing an N4O2 sexaden-
tate group derived from 5-nitrosalicylaldehyde and
triethylenetetramine.1 In previous studies of tridentate
chelating systems containing an open-chain coordinat-
ing substituent in the 2-position of 1,10-phenanthroline
it was found that the spin state of iron(II) in the
bis(ligand) complexes was strongly dependent on the
nature of the donor atom in the substituent. Thus
Manuscript received 12 May 1997
᭧ CSIRO Australia 1998
0004-9425/98/040273$ 05.00

274
B. J. Childs et al.
ing complex of pyridine-2-carbothioamide (N3S3 set)
5
a temperature-induced singlet (1A1)
quintet ( T2)
→
transition has been reported.6
In the present work the comparison of amide/
thioamide coordination has been extended to the
bipyridine-based
systems
2,20-bipyridine-6-carbo-
thioamide (1) (bpytm) and 2,20-bipyridine-6-carbox-
amide (2) (bpyam). These represent tridentate exten-
sions of the pyridine systems mentioned above and are
obviously closely related to the previously described
phenanthroline derivatives. Replacement of the phenan-
throline moiety by the bipyridine should result in
greater structural exibility and this may be expected
to accommodate the steric constraints of tridentate
coordination more readily. The work is thus concerned
primarily with a comparison of the eld produced by
the phenanthroline and bipyridine systems and the
structural characterization of the mode of bonding of
the substituent groups in six-coordinate iron(II) and
nickel(II) complexes.
N
N
N
N
Fig. 1. Mossbauer spectrum at 298 K of: (a) [Fe(bpytm)2]-
[BF4]2; (b) [Fe(bpyam)2] [BF4]2.
S
O
H2N
H2N
(1)
(2)
1
Table 1. Mossbauer spectral parameters (mm s
)
Results and Discussion
Complex
T (K)
EQ
Spin state
i.s.
[Fe(bpytm)2] [BF4]2.2H2O
298
80
298
80
298
80
80
298
80
80
298
0 39
0 36
1 80
2 73
2 04
2 68
0 78
2 26
2 73
0 65
2 22
0 24
0 31
0 95
1 08
0 95
1 06
0 43
0 95
1 06
0 46
1 04
1A1g
1A1g
5T2g
5T2g
5T2g
5T2g
1A1g
5T2g
5T2g
1A1g
5T2g
The ligands (1) and (2) were both obtained from
2,20-bipyridine-6-carbonitrile, the former by reaction
with ammonium sul de7 and the latter by copper(II)-
catalysed hydrolysis.8 Bis(ligand) complexes of (1)
and (2) with iron(II) and nickel(II) were prepared.
The electronic properties of the iron(II) complexes of
the two ligands are quite di erent, as was observed
for the corresponding phenanthroline systems. Thus
salts of [Fe(bpytm)2]2+ are low spin while those
of [Fe(bpyam)2]2+ are high spin at room tempera-
ture. This di erence in spin state is revealed in the
room-temperature Mossbauer spectra of [FeL2] [BF4]2
[L = (1), (2)] shown in Fig. 1. The low values for the
isomer shift and quadrupole splitting for the thioamide
derivative are indicative of singlet-state iron(II) while
the greater values for both parameters for the amide
complex are normal for quintet-state iron(II) (Table 1).
Comparison with the parameters for the correspond-
ing phenanthroline-based systems reveals very minor
di erences only (the parameters for the corresponding
phenanthroline thioamide complex have been previously
reported,2 while those for the 1,10-phenanthroline-2-
carboxamide system [Fe(phenam)2] [ClO4]2 were mea-
sured in the present work (Table 1)).
[Fe(bpyam)2] [BF4]2
[Fe(bpyam)2] [CF3SO3]2.H2O
[Fe(bpyam)2] [ClO4]2.H2O
[Fe(phenam)2] [ClO4]2
of the perchlorate and tri ate salts at 80 K (their
room-temperature spectra are very similar to that of
the uoroborate salt shown in Fig. 1). There is thus
in these two salts the onset of a quintet → singlet
transition at low temperature. There is an obvious
in uence of the anion on the manifestation of the
transition as there is no evidence for this transition in
the low-temperature spectrum of the uoroborate salt.
The magnetic data for the complexes are summarized
in Table 2 and do not give any distinct indication
of the onset of the transition. Mossbauer spectra
are, however, more diagnostic of the presence of a
low-spin fraction and it should also be noted that the
spectra were measured at a temperature lower than
the experimental limit available for the measurement
of magnetism.
The low-temperature Mossbauer spectra of
[Fe(bpyam)2] [ClO4]2.H2O
and
[Fe(bpyam)2]-
The partial transition to singlet state species observed
in salts of [Fe(bpyam)2]2+ is indicative of a somewhat
stronger eld than that in the corresponding phenan-
throline system. This is con rmed by the ligand eld
[CF3SO3]2.H2O, but not the spectrum of [Fe(bpyam)2]
[BF4]2, reveal a contribution from a small fraction
of singlet-state species. Fig. 2 shows the spectra

Donor Atom Set and Spin State of Iron(II)
275
3
spectrum of [Ni(bpyam)2]2+
,
1 (the 3A2g → T2g tran-
The electronic spectrum of [Fe(bpytm)2]2+ shows
intense charge-transfer absorption that is split into
sition) being observed at a frequency, 11100 cm 1, con-
siderably higher than that reported for [Ni(phenam)2]2+
(10500 cm 1)3 and certainly consistent with the appear-
ance of singlet-state species in the iron system. The
greater eld of a bipyridine-derived tridentate com-
pared to that of an analogous phenanthroline-based
system has been noted earlier.9 In the spectra of
both [Ni(bpytm)2]2+ and the previously described10
1
two components at 15600 and 16950 cm
(
6230
and 6450 l. mol cm 1, respectively), with the posi-
tions and intensities being indicative of singlet-state
FeII. This absorption obscures the singlet → singlet
ligand eld bands. A single, broad charge-transfer
1
1
band of relatively low intensity, centred at 19840 cm
1
(
1260 l. mol cm 1), is seen in the spectrum of
[Ni(phentm)2]2+
is observed at 12300 cm 1, some-
what lower than in the bis(terpyridine)nickel(II) ion
(12600 cm 1),11 but su ciently high to account for
the absence of quintet-state species in [Fe(bpytm)2]2+
[Fe(bpyam)2]2+. The marked di erence in the intensity
of the charge transfer in the two systems is a consequence
of the di erence in spin states which persists in solution,
as indicated also by the magnetic data in Table 2. It
is noted that within the accessible temperature range
there is a small decrease in the magnetic moment for a
solution of [Fe(bpyam)2] [BF4]2; this may indicate the
onset of a transition to singlet-state species, as occurs
in certain of the solid complexes at lower temperatures.
This is supported by the visual thermochromism of the
solution—at very low temperatures the colour becomes
more intense and the initially red solution becomes
red-violet. The ligand eld spectrum of [Fe(bpyam)2]2+
1
or [Fe(phentm)2]2+
.
2
at 298 K (10 M CH3CN solution) shows two well
1
resolved peaks of low intensity at 8850 and 12300 cm
1
(
18 and 22 l. mol cm 1, respectively). These are
characteristic of quintet-state FeII and their origin
5
5
presumably lies in the T2g → Eg transition, the
splitting being associated with low symmetry and/or
Jahn Teller e ects. They are at somewhat higher
frequencies than those reported3 for [Fe(phenam)2]2+
again indicative of the weaker eld in this complex.
,
As for the corresponding phenanthroline-based sys-
tems, the di erent spin states of [Fe(bpytm)2]2+ and
[Fe(bpyam)2]2+ suggest di erent donor atom sequences
and thus the thioamide and amide groups are expected
to coordinate through the sulfur and oxygen atoms,
respectively. This is normal for such groups and is
supported by infrared spectral data. In the spectrum
1
of the free thioamide a strong absorption at 1430 cm
is assigned to the C–N stretch, while an absorption at
1
835 cm is thought to arise from a composite vibration
with a contribution from the C=S stretch.12 In the
spectra of [Fe(bpytm)2] [BF4]2 and [Ni(bpytm)2] [BF4]2
the former band moves to higher frequencies (1456
and 1458 cm 1, respectively) while the latter moves
to lower (810 and 808 cm 1, respectively), as observed
for the corresponding phenanthroline-based system2
and consistent with S bonding. For the amide system
infrared spectral data are not so diagnostic. The
Fig. 2. Mossbauer spectrum at 80 K of: (a) [Fe(bpyam)2]-
[ClO4]2.H2O; (b) [Fe(bpyam)2] [CF3SO3]2.H2O.
Table 2. Summary of magnetic data for the complexes
Com-
plex
T
(K)
T
(K)
eff
(BM)
eff
(BM)
frequency of the C=O stretch is virtually constant at
1
1670 cm
in the free ligand and in the complexes,
[Fe(bpytm)2] [BF4]2.2H2O
[Fe(bpytm)2] [BF4]2
[Fe(bpyam)2] [BF4]2
353
383
303
303
303
299
299
303
303
0 95
0 90
5 04
5 00
4 95
1 5
4 89
2 95
2 97
303
303
89
89
89
0 90
0 76
5 01
5 03
4 74
while the shifts in the C–N stretch are in accord with
1
oxygen coordination (1393 cm
and 1408–1410 cm
in the free ligand
[Fe(bpyam)2] [CF3SO3]2.H2O
[Fe(bpyam)2] [ClO4]2.H2O
1
in the complexes). Hydrogen
A
[Fe(bpytm)2] [BF4]2 A
bonding involving the oxygen atom in the free ligand,
revealed in the structural studies discussed below, could
account for the lack of sensitivity of the C–O stretch
to coordination of the group.
[Fe(bpyam)2] [BF4]2
184
94
94
4 68
2 89
3 00
[Ni(bpytm)2] [BF4]2.H2O
[Ni(bpyam)2] [BF4]2.H2O
A
In solution.

276
B. J. Childs et al.
Structural Studies
rotation about the C–C inter-ring bond. The crystal
structure of 2,20-bipyridine alone contains molecules
in the planar trans con guration;13,14 however, when
crystallized in the presence of I2, the molecule (still in
an approximately trans con guration) becomes twisted,
with the angle between the normals to the planes of
the aromatic rings being 49 .15 In the presence of
KAu(CN)2, 2,20-bipyridine adopts an approximately
cis con guration with the angle between the normals
to the aromatic ring planes being 25 .16
The bridging C(5)–C(6) distances in (1) and (2) and in
free bipyridine14 are virtually identical. The dimensions
of both the thioamide and amide groups are consistent
with those reported for the corresponding pyridine-2-
carbothioamide17 and pyridine-2-carboxamide.18
The structures of both free ligands (1) and
(2) and of the complexes [Ni(bpytm)2] Cl2.4H2O,
[Ni(bpyam)2] [BF4]2.H2O and [Fe(bpyam)2] [BF4]2 have
been determined.
Suitable crystals of a salt of
[Fe(bpytm)2]2+ could not be grown.
Uncoordinated Ligands
A representation of the structure of (1) and the
atom numbering scheme are shown in Fig. 3. The
numbering scheme for the amide (2) is the same as
that for (1), except that S is replaced by O. Bond
distances and angles for both structures are listed in
Tables 3 and 4, respectively. In both the thioamide
(1) and the amide (2), the two pyridine rings adopt
a trans con guration and, in both structures, the
molecules are approximately planar. Previous studies
have shown that the uncoordinated bipyridyl moiety
can exist in either the cis or trans con guration
or in some non-planar intermediate, by virtue of
Table 4. Bond angles (degrees) in (1) and (2)
Atoms
Angle
in (1)
Angle in (2)
Molecule A
Molecule B
C(1)–N(1)–C(5)
C(6)–N(2)–C(10)
N(1)–C(1)–C(2)
C(1)–C(2)–C(3)
C(2)–C(3)–C(4)
C(3)–C(4)–C(5)
N(1)–C(5)–C(4)
N(1)–C(5)–C(6)
C(4)–C(5)–C(6)
N(2)–C(6)–C(5)
N(2)–C(6)–C(7)
C(5)–C(6)–C(7)
C(6)–C(7)–C(8)
C(7)–C(8)–C(9)
C(8)–C(9)–C(10)
N(2)–C(10)–C(9)
N(2)–C(10)–C(11)
C(9)–C(10)–C(11)
N(3)–C(11)–C(10)
S–C(11)–N(3)
116 8(3)
117 7(2)
124 4(3)
117 9(3)
119 1(3)
119 0(3)
122 6(3)
116 2(2)
121 1(2)
115 8(2)
122 3(2)
121 9(2)
119 0(2)
119 3(3)
118 3(2)
123 3(2)
114 0(2)
122 7(2)
114 4(2)
123 8(2)
121 7(2)
117 4(2)
117 4(2)
124 1(2)
118 1(2)
119 0(2)
119 4(2)
121 9(2)
117 0(2)
121 2(2)
116 7(2)
122 2(2)
121 1(2)
119 1(2)
119 5(2)
118 0(2)
123 9(2)
117 0(2)
119 1(2)
116 4(2)
116 5(2)
117 9(2)
124 9(3)
118 3(3)
118 1(3)
119 9(2)
122 4(2)
115 9(2)
121 7(2)
116 2(2)
121 9(2)
121 9(2)
119 0(2)
119 4(2)
118 1(2)
123 7(2)
117 0(2)
119 3(2)
117 3(2)
N(3)
S
C(11)
N(2)
C(10)
C(3)
C(4)
C(5)
C(9)
C(8)
C(6)
C(7)
C(2)
N(1)
C(1)
Fig. 3. Structure of bpytm (1).
S–C(11)–C(10)
O–C(11)–N(3)
O–C(11)–C(10)
123 6(2)
119 9(2)
122 7(2)
120 0(2)
Table 3. Bond lengths (A) in (1) and (2)
In Tables 3–8 and 10–14 estimated standard deviations are
given in parentheses
Atoms
Distance
in (1)
Distance in (2)
Molecule A
Molecule B
S–C(11)
O–C(11)
1 666(3)
1 234(2)
1 341(2)
1 341(2)
1 344(2)
1 344(2)
1 325(2)
1 369(3)
1 377(3)
1 378(3)
1 385(3)
1 489(2)
1 389(3)
1 381(3)
1 376(3)
1 381(3)
1 505(3)
1 236(2)
1 330(4)
1 341(3)
1 338(3)
1 337(2)
1 322(2)
1 372(4)
1 371(4)
1 381(3)
1 376(3)
1 489(3)
1 393(3)
1 376(4)
1 377(4)
1 375(3)
1 495(3)
N(1)–C(1)
N(1)–C(5)
N(2)–C(6)
N(2)–C(10)
N(3)–C(11)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
C(6)–C(7)
C(7)–C(8)
C(8)–C(9)
C(9)–C(10)
C(10)–C(11)
1 345(4)
1 336(3)
1 343(3)
1 344(3)
1 312(3)
1 368(5)
1 379(4)
1 379(4)
1 385(4)
1 490(4)
1 383(4)
1 380(4)
1 377(4)
1 379(4)
1 508(4)
Fig. 4. The hydrogen bonding in (2) showing a chain of dimers
(along b) of B molecules bridged by pairs of A molecules. The
additional hydrogen bonding from the amide of molecules A
to the pyridine of molecules A is not shown.

Donor Atom Set and Spin State of Iron(II)
277
As was expected from infrared spectral data in
particular, in the free amide (2) there is an extensive
network of hydrogen bonding within the structure.
The nature of the hydrogen bonding is represented
in Fig. 4. Pairs of molecules B form dimers through
scheme. Bond lengths and selected bond angles are
listed in Tables 5 and 6. The two bpytm molecules
are tridentate and their coordination planes are nearly
orthogonal with the angle between the normals to the
two planes being 88 8 . Coordination occurs through
the two nitrogen atoms of the pyridine rings and the sul-
fur atom of the thioamide group, as was expected. The
environment about the Ni atom is considerably distorted
from regular octahedral, as evidenced, for example,
by the disparity in the metal-to-donor atom distances.
Average values for Ni–Ndistal, Ni–Ncentral and Ni–S are
2 090(3), 2 034(3) and 2 419(1) A, severally. The Ni–S
distances are consistent with those reported for other
systems.19 The Ni–Ndistal and Ni–Ncentral distances are
two O
NH2 linkages, the NH
O distance being
2 02 A. There is a centre of inversion that relates the
two molecules involved. Molecule A is approximately
orthogonal to molecule B; however, it is involved in a
hydrogen-bonding pattern that is di erent to that for
molecule B. Dimers of molecule B are linked in chains
by pairs of amide groups of molecules of A through
hydrogen bonding of the type:
• • •
• • •
N
H
O
C
N
H
O
similar to those for [Ni(terpy)2]2+ 20
and for the struct-
,
B
A
B
urally related complex [Ni(bph)2]2+, where bph is 2,20-
bipyridine-6-carbaldehyde phenylhydrazone,10 though
the Ni–Ncentral distance in [Ni(bpytm)2] Cl2.4H2O is
somewhat longer than in these two related complexes.
This relatively long distance in the thioamide complex
may be imposed by the large sulfur atom in an adjacent
chelate ring. It is primarily the size of this atom
which leads to important di erences in the geometry
of the two chelate rings associated with each ligand
molecule. Thus the greater C(11)–S distance compared
with the C(5)–N(1) distance places the S atom in a
more favourable coordination site, as re ected in the
values for the S–Ni–N(2) (81 8 ) and N(1)–Ni–N(2)
(78 9 ) bite angles, the former being closer to the
normal octahedral angle. The bite angle N(1)–Ni–N(2)
is similar to the average value of the bite angle in
[Ni(terpy)2]2+ (77 9 ) and also the analogous angle in
[Ni(bph)2]2+ (78 3 ).
The crystal structure consists of discrete layers per-
pendicular to b (Fig. 6). Cation layers are separated
by layers of water molecules and chloride ions which
are extensively hydrogen-bonded. The amine hydrogen
atoms also take part in the hydrogen bonding and
form the only interactions between the cation and
anion (chloride) layers. Each amine nitrogen atom
hydrogen-bonds to one water molecule and one chlorine
atom, and hence is a donor to two hydrogen bonds. The
water molecules form an additional hydrogen-bonded
network and are also found to hydrogen-bond to the
chlorine atoms. There are two types of chlorine atoms
with respect to the nature of hydrogen bonding. One
dimer 1
amide
dimer 2
Molecule A is also involved in a second type of
hydrogen-bonding interaction. This involves the amide
group hydrogen atom, which is not involved in linking
B dimers, hydrogen-bonding to the N(1) atom of the
pyridine ring of a symmetry-related A molecule. The
hydrogen bonding results in layers in the yz-plane from
which B molecules protrude on both sides. Layers pack
by interspersing protruding B molecules. There are
both edge-to-face and face-to-face aromatic interactions
between molecules. The pyridine rings of molecule B
are not involved in any hydrogen bonding.
Hydrogen bonding in (1) is restricted to that which
occurs between pairs of molecules through S NH2
linkages, the N–H S hydrogen bond distances being
2 48 A. This results in the formation of centrosymmet-
ric planar dimeric units analogous to those described
above for (1). There is face-to-face aromatic stacking
of the dimeric units. The pyridine ring pyridine
ring distances of the adjacent ‘stacked’ molecules are
approximately 3 4 A. The question arises as to why
these two very similar molecules pack so di erently
in the solid state. The di erences between the two
molecules are the C=S distance, which is some 0 4 A
longer than the C=O distance, and the di erence in
the propensity for hydrogen bonding to O as against
S. It is likely that the rst of these di erences could
easily be accommodated if (2) adopted the packing
of (1) by a small change in unit cell dimensions. It
seems, therefore, that it is the more extensive hydrogen
bonding which dictates the molecular packing of (2)
and the concomitant incorporation of a second molecule
into the asymmetric unit. It is noteworthy that in
the corresponding pyridine systems the packing and
the hydrogen-bonding pattern is essentially the same
for the amide and thioamide17,18 and includes the
formation of dimers analogous to those observed in
the present work.
is an acceptor for four hydrogen bonds, the Cl
H
distances being 2 18, 2 23, 2 29 and 2 33 A. The
second type is an acceptor for two hydrogen bonds
with Cl H bond distances of 2 22 and 2 28 A.
In each of these cases the longest hydrogen bond
is associated with an amide hydrogen atom. These
distances are within the normal ranges observed for
such interactions, and correspond closely to those in,
for example, bis[2,20-iminobis(acetamidoxime)]nickel(II)
chloride dihydrate.21
Metal Complexes
Fig. 7 shows the structure of the complex cation in
[Fe(bpyam)2] [BF4]2 and the atom numbering scheme.
Fig. 5 shows the structure of the complex cation
in [Ni(bpytm)2] Cl2.4H2O and the atom numbering

278
B. J. Childs et al.
Table 6. Bond angles (degrees) for [Ni(bpytm)2] Cl2.4H2O
N(3)
Atoms
Angle
S
C(11)
SA–Ni–N(1)A
SA–Ni–N(2)A
SA–Ni–N(1)B
SA–Ni–N(2)B
N(1)A–Ni–N(2)A
N(1)A–Ni–N(1)B
N(1)A–Ni–N(2)B
SA–Ni–SB
SB–Ni–N(1)B
SB–Ni–N(2)B
N(1)A–Ni–SB
N(2)A–Ni–SB
N(1)B–Ni–N(2)B
N(2)A–Ni–N(2)B
N(2)A–Ni–N(1)B
160 0(1)
81 8(1)
89 7(1)
103 9(1)
78 9(1)
91 0(1)
95 8(1)
92 6(0)
161 1(1)
82 5(1)
93 2(1)
92 0(1)
78 8(1)
172 2(1)
106 8(1)
C(10)
C(9)
N(1)
S
N(2)
Ni
N(2)
C(8)
N(3)
C(6)
C(7)
N(1)
C(5)
C(1)
C(4)
C(2)
C(3)
Ligand A
Ligand B
Ni–S–C(11)
Ni–N(1)–C(1)
Ni–N(1)–C(5)
C(1)–N(1)–C(5)
Ni–N(2)–C(6)
97 2(1)
127 5(3)
114 2(2)
118 3(3)
116 1(2)
123 2(2)
119 6(3)
122 5(4)
118 6(4)
119 9(4)
118 9(4)
121 8(4)
114 5(3)
123 7(4)
115 6(3)
121 6(4)
122 7(4)
118 1(4)
120 2(4)
118 9(4)
121 5(3)
115 2(3)
123 3(3)
121 1(3)
121 1(3)
117 8(3)
98 4(1)
126 3(3)
114 5(2)
119 3(3)
116 3(3)
123 1(2)
120 3(3)
121 9(4)
118 7(4)
120 3(4)
118 4(4)
121 4(4)
115 3(3)
123 4(4)
114 8(3)
120 6(4)
124 6(3)
119 2(4)
120 3(4)
118 6(4)
121 0(3)
115 3(3)
123 6(4)
121 4(3)
120 7(3)
117 9(3)
Fig. 5. Structure of the complex cation [Ni(bpytm)2]2+. In
this diagram ligand A is vertical.
Table 5. Bond distances (A) for
[Ni(bpytm)2] Cl2.4H2O
Ni–N(2)–C(10)
C(6)–N(2)–C(10)
N(1)–C(1)–C(2)
C(1)–C(2)–C(3)
C(2)–C(3)–C(4)
C(3)–C(4)–C(5)
N(1)–C(5)–C(4)
N(1)–C(5)–C(6)
C(4)–C(5)–C(6)
N(2)–C(6)–C(5)
N(2)–C(6)–C(7)
C(5)–C(6)–C(7)
C(6)–C(7)–C(8)
C(7)–C(8)–C(9)
C(8)–C(9)–C(10)
N(2)–C(10)–C(9)
N(2)–C(10)–C(11)
C(9)–C(10)–C(11)
S–C(11)–N(3)
Atoms
Ni–S
Ni–N(1)
Ni–N(2)
S–C(11)
Ligand A
Ligand B
2 441(1)
2 095(3)
2 031(3)
1 685(4)
1 341(5)
1 354(5)
1 338(5)
1 346(4)
1 324(5)
1 377(6)
1 367(6)
1 378(6)
1 373(5)
1 476(5)
1 392(5)
1 384(6)
1 369(6)
1 382(5)
1 483(5)
2 397(1)
2 084(3)
2 036(3)
1 674(4)
1 340(5)
1 352(4)
1 351(5)
1 345(5)
1 305(5)
1 386(6)
1 365(6)
1 383(6)
1 389(5)
1 472(5)
1 391(5)
1 357(6)
1 393(6)
1 378(5)
1 496(5)
N(1)–C(1)
N(1)–C(5)
N(2)–C(6)
N(2)–C(10)
N(3)–C(11)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
C(6)–C(7)
C(7)–C(8)
C(8)–C(9)
C(9)–C(10)
C(10)–C(11)
S–C(11)–C(10)
N(3)–C(11)–C(10)
Fig. 6. Hydrogen bonding in [Ni(bpytm)2] Cl2.4H2O.
In the hydrogen-bonded layers the oxygen atoms
are represented as lled circles while the chlorine
atoms are diagonally hatched.

Donor Atom Set and Spin State of Iron(II)
279
The structure of the cation in [Ni(bpyam)2] [BF4]2.H2O
is essentially the same and the same numbering scheme
applies, though for this complex there are two indepen-
dent ligand molecules, A and B. Bond distances and
selected bond angles for both complexes are listed in
Tables 7 and 8, respectively. The coordination about
each metal atom is distorted octahedral with the two
bpyam molecules coordinating meridionally through the
two pyridine nitrogens and the amide oxygen atoms.
In the iron complex the two ligands are related by
a twofold axis of symmetry that runs through the iron
atom. The angle between the normals to the two ligand
planes is 76 9 . Iron–donor atom distances are normal
for high-spin iron(II). Distortion of the coordination
sphere shows up markedly in the angles about the
metal atom; bite angles of 74 1 and 73 7 were found
for the NN and NO chelate rings, respectively. The
overall bite angle (147 6 ) is comparable to that in the
high-spin complex of the NNN donor 2,6-bis(triazol-
3-yl)pyridine22 but considerably less than that in the
low-spin terpy complex (161 0(3) ),23 and the di erence
arises from the di erent radii of high-spin and low-
spin iron(II). The structure of the low-spin [FeIIN6]
derivative of the tridentate N -pyridin-2-ylcarbonyl-
pyridine-2-carboximinate ion24 is of relevance here
since it also involves the coordination of two pyridine
nitrogens and an amide group. The ligand system
di ers importantly from bpyam, however, in that the
amide group is anked by the two pyridine rings and
thus it coordinates through the nitrogen atom, oxygen
coordination being sterically unfavourable for triden-
tate function in this instance. A further signi cant
di erence is that the amide group is deprotonated,
again favouring nitrogen coordination in this instance.
Table 8. Bond angles (degrees) in
[M(bpyam)2] [BF4]2 (M = Ni, Fe)
i
1
2
Symmetry transformation:
1
x, y,
z
Atoms
M = Ni
M = Fe
C(2)
C(3)
OA–Ni–OB
87 9(2)
92 8(2)
176 4(2)
94 5(2)
99 9(2)
94 3(2)
100 0(2)
103 9(2)
103 5(2)
N(1)A–Ni–N(1)B
N(2)A–Ni–N(2)B
OA–Ni–N(1)B
OA–Ni–N(2)B
N(1)A–Ni–OB
N(2)A–Ni–OB
N(1)A–Ni–N(2)B
N(2)A–Ni–N(1)B
O–Fe–Oi
C(1)
C(4)
C(5)
N(1)
C(6)
C(7)
C(8)
Fe
N(2)
90 3(3)
87 0(3)
176 2(3)
100 3(2)
103 5(2)
108 8(2)
N(1)–Fe–N(1)i
N(2)–Fe–N(2)i
O–Fe–N(1)i
C(9)
O
C(10)
C(11)
N(3)
O–Fe–N(2)i
N(1)–Fe–N(2)i
Ligand A
Ligand B
156 4(2) 147 6(2)
O–M–N(1)
O–M–N(2)
N(1)–M–N(2)
M–O–C(11)
M–N(1)–C(1)
M–N(1)–C(5)
C(1)–N(1)–C(5)
M–N(2)–C(6)
156 0(2)
77 5(2)
78 6(2)
Fig. 7. Structure of the complex cation in [Fe(bpyam)2] [BF4]2.
The structure of the cation in [Ni(bpyam)2] [BF4]2.H2O is
essentially the same but with two independent ligands, A and B.
77 3(2)
79 1(2)
73 7(2)
74 1(2)
113 5(5)
127 1(5)
113 5(5)
119 3(7)
118 6(5)
119 9(5)
121 4(6)
122 8(8)
117 6(8)
120 6(8)
118 0(8)
121 7(8)
115 8(6)
122 5(7)
113 4(6)
119 4(8)
127 2(7)
119 2(8)
120 5(7)
117 2(8)
122 4(7)
114 8(5) 117 3(5)
128 1(5) 123 6(5)
113 6(5) 117 2(5)
118 3(6) 118 5(7)
118 2(5) 120 0(5)
119 5(5) 120 2(5)
122 3(6) 119 5(6)
123 2(8) 121 5(8)
118 8(9) 119 1(8)
120 3(8) 119 7(8)
117 1(8) 118 3(7)
122 3(8) 122 8(7)
115 4(6) 113 7(6)
122 3(7) 123 5(7)
113 6(6) 114 1(6)
119 3(7) 120 8(7)
127 1(7) 125 1(7)
118 3(8) 119 5(8)
121 1(7) 119 4(7)
117 9(8) 117 1(7)
121 1(7) 123 7(7)
111 2(6) 110 7(6)
127 7(7) 125 6(7)
123 2(7) 123 2(7)
116 9(6) 117 7(7)
119 9(7) 119 1(7)
Table 7. Bond lengths (A) in
[M(bpyam)2] [BF4]2 (M = Ni, Fe)
Symmetry transformation: i1 x, y,
z
1
2
Atoms
M = Ni
M = Fe
M–N(2)–C(10)
C(6)–N(2)–C(10)
N(1)–C(1)–C(2)
C(1)–C(2)–C(3)
C(2)–C(3)–C(4)
C(3)–C(4)–C(5)
N(1)–C(5)–C(4)
N(1)–C(5)–C(6)
C(4)–C(5)–C(6)
N(2)–C(6)–C(5)
N(2)–C(6)–C(7)
C(5)–C(6)–C(7)
C(6)–C(7)–C(8)
C(7)–C(8)–C(9)
C(8)–C(9)–C(10)
N(2)–C(10)–C(9)
Ligand A
Ligand B
M–O
M–N(1)
M–N(2)
O–C(11)
2 136(5)
2 095(6)
1 982(6)
1 245(9)
1 324(10)
1 341(9)
1 344(9)
1 323(9)
1 325(10)
1 381(11)
1 385(12)
1 369(13)
1 393(10)
1 464(11)
1 394(10)
1 369(13)
1 398(12)
1 371(10)
1 520(11)
2 110(5)
2 084(6)
1 988(5)
1 248(8)
1 321(9)
1 346(9)
1 338(9)
1 321(9)
1 302(9)
1 369(12)
1 351(13)
1 395(13)
1 388(11)
1 479(10)
1 402(10)
1 370(12)
1 378(12)
1 377(10)
1 515(10)
2 174(5)
2 180(6)
2 096(5)
1 247(9)
1 334(9)
1 336(8)
1 335(9)
1 342(9)
1 316(9)
1 414(11)
1 348(12)
1 387(11)
1 384(10)
1 484(10)
1 384(10)
1 384(11)
1 405(11)
1 362(10)
1 503(10)
N(1)–C(1)
N(1)–C(5)
N(2)–C(6)
N(2)–C(10)
N(3)–C(11)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
C(6)–C(7)
C(7)–C(8)
C(8)–C(9)
C(9)–C(10)
C(10)–C(11)
N(2)–C(10)–C(11) 110 8(6)
C(9)–C(10)–C(11) 126 9(8)
123 0(7)
118 1(7)
N(3)–C(11)–C(10) 118 8(7)
O–C(11)–N(3)
O–C(11)–C(10)

280
B. J. Childs et al.
The environment about the Ni atom in
signi cant. The S–C(11) and N(3)–C(11) distances
appear longer and shorter, respectively, in the Ni
complex compared to the distances in the free ligand,
and this is as expected for sulfur coordination. The
only signi cant geometrical change in the pyridine rings
on coordination would seem to be the greater C–N–C
angles (i.e. 116 8 and 117 7 for the uncoordinated
ligand; cf. average values of 118 8 and 120 0 for the
coordinated ligand). The same trends are observed
in (2). In all three metal complexes, the ligands are
approximately planar.
[Ni(bpyam)2]2+ shows considerable distortion from
octahedral symmetry. The average Ni–Ndistal distance
is 2 090 A while the average Ni–Ncentral distance is
1 985 A. These distances are comparable to those
reported for [Ni(bph)2]2+ 10
those of [Ni(terpy)2]2+ 20
,
but are slightly less than
.
Despite this, the ligand eld
of bpyam is weaker than that of terpyridine. This
highlights the importance of the actual donor-atom set
in determining the overall eld strength. The aver-
age Ni–O distance is 2 123 A, somewhat longer than
that found in the diaqua-bis(pyridine-2-carboxamide)-
nickel(II) cation (2 045 A), where the constraints of
tridentate coordination do not apply.25 The metal-to-
donor atom distances in the NiII complex of bpyam are
signi cantly shorter than those of the FeII complex.
This is also re ected in the greater bite angles of the
NiII complex (average 78 9 for the NN chelate loop
and 77 4 for the NO loop) and is expected to be a
result of the smaller ionic radius of NiII, compared
to that of high-spin iron(II). The average overall bite
angle is 156 2 which is in good agreement with those
of the [Ni(bph)2]2+ and [Ni(terpy)2]2+ systems.10,20
The lattice water in [Ni(bpyam)2] [BF4]2.H2O is
involved in hydrogen bonding within the structure.
The cations are linked in pairs by hydrogen-bonding to
two water molecules. Such hydrogen bonding occurs
through linkages of the type:
Concluding Comments
Infrared spectral data, in particular those relating
to
and C=O, seem to o er a reliable guide to the
C=S
coordination mode of the thioamide or amide group
in the present systems. However, the shifts observed
in frequencies relating to these vibrations in the com-
plexes are not re ected in any major observed changes
in the bond distances within the functional groups
on coordination. The changes which are observed,
though generally in the directions expected, cannot be
considered signi cant in view of the degree of precision
of the measured distances.
Comparison of the geometry of the free ligand
with that of the coordinated ligand reveals that for
the thioamide group there is little change in the
C(10)–C(11)–S angle on coordination, whereas the
C(10)–C(11)–O angle in the coordinated amide group
is signi cantly smaller than that in the free amide. The
sulfur atom is thus better positioned for coordination
in the tridentate system. This is also evident from
the angles about the metal atom in the chelate rings.
Whereas in the nickel thioamide complex the deviation
from the ideal angle of 90 is less for the S–Ni–N angle
than for the N–Ni–N angle, for both the nickel and
iron complexes of the amide the deviation is greater for
the O–M–N angles than for the N–M–N angles. This
more favourable geometry of the coordinated thioamide
group may contribute to its observed stronger ligand
eld and hence the fundamental di erence in the
ground state for the bis(ligand)iron(II) complexes.
• • •
• • • O Hwater
O
amide
NHamide
The hydrogen bonding involving the NH group appears
to be slightly stronger than that involving the O atom
of the amide group, the distances being 2 921 and
2 959 A, respectively. A similar type of hydrogen
bonding, which would strengthen the -bonding capac-
ity of the amide group, may also occur in the hydrated
perchlorate and tri ate salts of the bis(ligand)FeII
complexes, accounting for the occurrence of a small
low-spin fraction in these salts at low temperature,
in contrast to the purely high-spin nature of the
uoroborate salt which was obtained anhydrous.
In [Fe(bpyam)2] [BF4]2 the only hydrogen bonding
involves interactions of the type NH F which link the
complex cation to the counter anion. The same kind of
interaction is also present in [Ni(bpyam)2] [BF4]2.H2O.
There are two distinct distances for these interactions
in each complex, these being 1 90 and 1 92 A for the
iron(II) complex and 1 96 and 2 00 A for the nickel(II)
complex.
Comparison of the dimensions of the free ligands (1)
and (2) with those of the coordinated ligands reveals
small changes in the directions which would be expected
for coordination. However, the standard deviations
for the measured S–C(11), O–C(11) and N(3)–C(11)
distances in both the iron and nickel complexes are
relatively large and hence the small changes in these
distances resulting from coordination might not be
Experimental
Preparations
2,20-Bipyridine-6-carbothioamide (1) was prepared from 2,20-
bipyridine-6-carbonitrile according to the procedure reported
by Antonini et al.,7 m.p. 176–177 C (lit.7 177–178 C). The fol-
lowing synthesis of 2,20-bipyridine-6-carboxamide (2) was based
upon the method of Breslow et al.8 for the metal ion catalysed
hydrolysis of 1,10-phenanthroline-2-carbonitrile to the corre-
sponding amide. To a solution of 2,20-bipyridine-6-carbonitrile
(1 0 g, 5 5 mmol) in H2O (60 ml) was added CuCl2.2H2O
(0 94 g, 5 53 mmol) and the resultant green/blue solution was
titrated with NaOH (0 5 M) to pH 11. At this pH a pale blue
solid had formed and ethylenediaminetetraacetic acid (4 12 g,
11 1 mmol) in H2O (15 ml) was then added, a process resulting
in a clear blue solution of pH 5. The solution was adjusted to
pH 7 with NaOH (0 5 M) at which point a white precipitate
formed. The solid was collected by ltration, washed with

Donor Atom Set and Spin State of Iron(II)
281
cold H2O and suction-dried. The solid was recrystallized from
ethanol/diethyl ether to yield white needles (0 83 g, 75 5%),
m.p. 151–153 C (Found: C, 66 4; H, 4 5; N, 21 2. C11H9N3O
requires C, 66 3; H, 4 5; N, 21 1%).
For bpyam. Crystals were grown from ethanol/diethyl
ether. C11H9N3O, M 199 2, monoclinic, space group P 21/c,
a 13 581(2), b 9 926(1), c 16 824(3) A, 116 481(7) , V
2030 0(6) A3, Dc 1 30 g cm 3, Z 8, 6 79 cm 1. Crystal
Cu
All iron complexes were prepared under a nitrogen atmo-
sphere. The following procedure was used for the preparation
of both iron and nickel complexes. The solid ligand (2 mmol)
was added to a warm aqueous (20%) ethanol solution (10 ml)
of the metal chloride (1 mmol). The solution was warmed until
the ligand had reacted and was then ltered. To the ltrate
an excess of an aqueous solution of the appropriate sodium or
ammonium salt was added and the complex salt crystallized
on cooling. This was washed with cold water and dried in a
vacuum desiccator over phosphorus pentoxide. Analytical data
for the complexes are listed in Table 9.
size 0 10 by 0 18 by 0 43 mm, 2
140 , min. and max.
max
transmission factors 0 81 and 0 94. The number of re ections
was 2544 considered observed out of 4236 unique data, with
Rmerge 0 011 for 95 pairs of equivalent re ections. Final
residuals R, Rw were 0 045, 0 055 for the observed data.
For [Ni(bpytm)2] Cl2.4H2O. Crystals were grown from ace-
tonitrile solution. C22H18N6NiS2.2Cl.4H2O, M 632 2, triclinic,
space group P 1, a 9 291(5), b 12 426(7), c 13 425(7) A,
113 54(3), 95 63(3), 94 43(3) , V 1403(1) A3, Dc 1 50 g
1
cm 3, Z 2,
0 20 mm, 2
10 67 cm
. Crystal size 0 03 by 0 20 by
Mo
50 , min. and max. transmission factors 0 81
max
and 0 97. The number of re ections was 3399 considered
observed out of 5247 unique data, with Rmerge 0 026 for 242
pairs of equivalent re ections. Final residuals R, Rw were
0 038, 0 046 for the observed data.
Table 9. Analytical data for the complexes
Com-
plex
L
Found (%)
H
Requires (%)
H
C
N
M
C
N
M
For [Ni(bpyam)2] [BF4]2.H2O. Crystals were grown from
acetone solution into which low-boiling petroleum was allowed
to di use slowly. C22H18N6NiO2.2BF4.H2O, M 648 8, triclinic,
space group P 1, a 10 663(5), b 10 861(6), c 12 799(6) A,
[FeL2] [BF4]2.2H2O
[NiL2] [BF4]2.H2O
[FeL2] [BF4]2
[FeL2] [ClO4]2.H2O
[FeL2] [CF3SO3]2.H2O (2) 37 4 2 9 10 8 7 4 37 4 2 6 10 9 7 3
(1) 38 1 3 0 12 0 7 8 38 0 3 2 12 1 8 0
(1) 39 2 3 3 12 2 8 5 38 8 2 9 12 4 8 6
(2) 41 9 3 2 13 5 8 9 42 1 2 9 13 4 8 9
(2) 39 5 3 2 12 6 8 5 39 4 3 0 12 5 8 3
68 70(4),
cm 3, Z 2,
0 15 mm, 2
77 84(4),
8 17 cm
78 47(4) , V 1338(1) A3, Dc 1 61 g
1
[FeL2] I2.3H2O
[NiL2] [BF4]2.H2O
(2) 35 2 3 2 10 9 7 2 34 7 3 2 11 0 7 3
(2) 41 1 3 4 13 0 8 9 40 7 3 1 13 0 9 1
. Crystal size 0 07 by 0 15 by
Mo
45 , min. and max. transmission factors 0 93
max
and 0 95. The number of re ections was 2619 considered
observed out of 3678 unique data, with Rmerge 0 022 for 142
pairs of equivalent re ections. Final residuals R, Rw were
0 065, 0 087 for the observed data.
Physical Measurements
Magnetism
For [Fe(bpyam)2] [BF4]2. Crystals were grown as for
The magnetic data for solid samples were obtained by using
a Newport variable temperature Gouy balance calibrated with
CoHg(NCS)4. Magnetic data for samples in methanol solution
were obtained by the Evans26 method with a BRUKER AM-500
n.m.r. spectrometer. The method was modi ed according to
the description of Baker, Field and Hambley27 for application
with a superconducting magnet. The sample temperature was
calibrated by using the known temperature-dependence of the
spectrum of methanol as a reference standard. Correction for
the temperature-dependence of the density of the solvent28 has
been made. All data have been corrected for diamagnetism
calculated by using Pascal’s constants.29
[Ni(bpyam)2] [BF4]2.H2O. C22H18FeN6 O2 .2BF4,
M
627 9,
orthorhombic, space group P bcn, a 12 317(6), b 12 609(4),
c 16 644(8) A, V 2585(2) A3, Dc 1 61 g cm 3, Z 4,
Mo
1
6 70 cm
. Crystal size 0 10 by 0 10 by 0 15 mm, 2
max
50 , min. and max. transmission factors 0 91 and 0 95. The
number of re ections was 1223 considered observed out of 2595
unique data. Final residuals R, Rw were 0 069, 0 078 for the
observed data.
Structure Determinations
Re ection data for each structure were measured at 21(1) C
with an Enraf–Nonius CAD-4 di ractometer in /2 scan
mode. Data were corrected for absorption by using the ana-
lytical method of de Meulenaer and Tompa.30 Re ections with
I > 3 (I ) were considered observed. The structures were
determined by direct phasing (MULTAN8031) and Fourier meth-
ods. Hydrogen atoms were included in calculated positions
and were assigned thermal parameters equal to those of the
atom to which they were bonded. Positional and anisotropic
thermal parameters for the non-hydrogen atoms were re ned
by using full-matrix least-squares (BLOCKLS, a local version of
ORFLS32).
It was clear that for [Ni(bpyam)2] [BF4]2.H2O one of the
BF4 anions was disordered, so re nement was completed
(RAELS33) with each BF4 ion being included in the re ne-
ment as a rigid group with exact Td symmetry. A global
B–F distance was re ned for this structure, the nal value
being 1 340(3) A. The two disorder components of the group
labelled B were included, with their occupancies re ned, but
the sum maintained at 1. The nal values of the occupancies
were 0 527(6) and 0 473. Two TLX thermal groups (where T
Spectra
Mossbauer spectra were recorded with a constant accelera-
tion spectrometer in transmission mode. The source was 57Co
in a rhodium matrix. The temperature was controlled by an
Oxford Instruments CF506 continuous- ow cryostat together
with an ITC-4 temperature control unit. The isomer shift
values quoted are relative to the midpoint of the iron spectrum
at room temperature. The spectral parameters were extracted
from a least-squares t of the data to Lorentzian line shapes.
Electronic spectra were recorded for acetonitrile solutions on
a Cary 17 spectrophotometer. Infrared spectra were measured
on an ATI Mattson Genesis Fourier-transform spectrometer for
samples prepared as compressed CsI disks.
Crystallography
Crystal Data
For bpytm. Crystals were grown from ethanol. C11H9N3S,
M
215 3, monoclinic, space group P 21/c,
a
8 265(3),
94 47(2) , V 1023 4(5) A3, Dc
2 70 cm 1. Crystal size 0 09 by 0 13
b
is the translational tensor, L is the librational tensor, and
X
11 175(2), c 11 114(4) A,
1 40 g cm 3, Z 4,
by 0 13 mm, 2
is the origin of libration) were used to describe the thermal
motion of the two anions.
Mo
50 , min. and max. transmission factors
max
For all structures, re ection weights used were 1/ 2(Fo),
0 96 and 0 98. The number of re ections was 1133 considered
observed out of 2005 unique data, with Rmerge 0 028 for 54
pairs of equivalent hk0 re ections. Final residuals R, Rw were
0 038, 0 044 for the observed data.
with (Fo) being derived from (I o) = [ 2(I o)+(0 04I o)2]1/2
.
The weighted residual was de ned as Rw = [ w(Fo Fc)2/
2 1/2
wFo
]
.
Atomic scattering factors and anomalous

282
B. J. Childs et al.
Table 10. Atomic parameters for bpytm (1)
Atom
x
y
z
Beq
Atom
x
y
z
Beq
S
0 0257(1)
0 4885(3)
0 2461(3)
0 1200(3)
0 5967(4)
0 6417(4)
0 5672(4)
0 4545(3)
0 6283(1)
0 2955(2)
0 4163(2)
0 4192(2)
0 2068(3)
0 1266(3)
0 1343(3)
0 2233(2)
0 1556(1)
0 6250(2)
0 3714(2)
0 1499(2)
0 6479(3)
0 5638(3)
0 4487(3)
0 4224(2)
4 44(2)
4 48(8)
3 08(6)
4 84(8)
5 30(11)
4 85(10)
4 45(9)
3 56(8)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
0 4207(3)
0 3115(3)
0 2829(3)
0 1869(3)
0 1204(3)
0 1524(3)
0 0846(3)
0 3034(2)
0 4079(2)
0 4921(3)
0 5899(3)
0 6004(2)
0 5119(2)
0 5139(3)
0 5122(2)
0 4856(2)
0 5726(2)
0 5407(3)
0 4237(3)
0 3424(2)
0 2125(2)
3 12(7)
3 02(7)
3 49(7)
3 67(8)
3 63(8)
3 10(7)
3 49(8)
N(1)
N(2)
N(3)
C(1)
C(2)
C(3)
C(4)
Table 11. Atomic parameters for bpyam (2)
Atom
x
y
z
Beq
Atom
x
y
z
Beq
OA
0 1024(1)
0 1723(1)
0 1450(1)
0 1336(2)
0 1942(2)
0 2198(2)
0 2266(2)
0 2055(2)
0 1767(1)
0 1457(1)
0 1162(2)
0 0860(2)
0 0870(2)
0 1164(1)
0 1160(2)
1 0755(1)
0 5595(2)
0 7839(1)
0 8602(2)
0 4293(2)
0 3375(2)
0 3820(2)
0 5156(2)
0 6015(2)
0 7442(2)
0 8300(2)
0 9608(2)
1 0038(2)
0 9122(2)
0 9557(2)
0 4718(1)
0 2115(1)
0 3694(1)
0 5196(1)
0 2051(1)
0 2721(2)
0 3520(2)
0 3606(1)
0 2888(1)
0 2932(1)
0 2210(1)
0 2276(2)
0 3056(1)
0 3742(1)
0 4597(1)
5 10(6)
4 08(6)
3 49(5)
4 73(7)
4 90(8)
5 49(9)
6 13(10)
5 08(8)
3 54(6)
3 53(6)
4 76(8)
5 22(8)
4 27(7)
3 44(6)
3 80(7)
OB
0 1338(1)
0 5735(2)
0 3236(1)
0 1043(1)
0 6040(2)
0 5332(3)
0 4226(2)
0 3886(2)
0 4650(2)
0 4318(2)
0 5091(2)
0 4729(2)
0 3616(2)
0 2907(2)
0 1694(2)
0 5749(1)
0 1232(2)
0 3091(2)
0 3531(1)
0 0015(4)
0 1075(3)
0 0846(3)
0 0442(2)
0 1451(2)
0 2857(2)
0 3871(3)
0 5153(3)
0 5403(2)
0 4348(2)
0 4592(2)
0 5485(1)
0 6482(2)
0 5892(1)
0 5233(1)
0 6406(2)
0 6038(3)
0 5719(2)
0 5787(2)
0 6161(2)
0 6234(1)
0 6639(2)
0 6680(2)
0 6322(2)
0 5932(1)
0 5529(1)
4 96(6)
7 23(9)
4 13(6)
4 53(6)
8 59(15)
8 41(14)
7 79(13)
6 32(10)
5 39(9)
4 87(8)
6 86(11)
7 61(12)
6 04(10)
4 07(7)
3 85(7)
N(1)A
N(2)A
N(3)A
C(1)A
C(2)A
C(3)A
C(4)A
C(5)A
C(6)A
C(7)A
C(8)A
C(9)A
C(10)A
C(11)A
N(1)B
N(2)B
N(3)B
C(1)B
C(2)B
C(3)B
C(4)B
C(5)B
C(6)B
C(7)B
C(8)B
C(9)B
C(10)B
C(11)B
Table 12. Atomic parameters for [Ni(bpytm)2] Cl2.4H2O
Atom
x
y
z
Beq
Atom
x
y
z
Beq
Ni
SA
0 2240(1)
0 1254(1)
0 2875(3)
0 1173(3)
0 0451(4)
0 3799(5)
0 4161(5)
0 3567(6)
0 2618(5)
0 2278(4)
0 1240(4)
0 0346(5)
0 0649(5)
0 0708(5)
0 0233(4)
0 0294(4)
0 0172(1)
0 4309(3)
0 3199(3)
0 4541(1)
0 3167(1)
0 5193(3)
0 3273(2)
0 1195(3)
0 6165(4)
0 6497(4)
0 5800(4)
0 4796(4)
0 4521(3)
0 3491(3)
0 2810(4)
0 1906(4)
0 1676(4)
0 2367(3)
0 2170(3)
0 5612(1)
0 4062(3)
0 5974(3)
0 2485(1)
0 3210(1)
0 1355(2)
0 1053(2)
0 1979(3)
0 1561(3)
0 0745(4)
0 0316(4)
0 0546(3)
0 0304(3)
0 0160(3)
0 0826(3)
0 0855(4)
0 0057(3)
0 1003(3)
0 2025(3)
0 2801(1)
0 2705(2)
0 3848(2)
2 71(1)
3 45(3)
3 25(10)
2 81(9)
N(3)B
C(1)B
C(2)B
C(3)B
C(4)B
C(5)B
C(6)B
C(7)B
C(8)B
C(9)B
C(10)B
C(11)B
Cl(1)
0 0222(4)
0 4766(4)
0 6181(5)
0 7137(4)
0 6689(4)
0 5248(4)
0 4627(4)
0 5402(4)
0 4704(5)
0 3235(5)
0 2511(4)
0 0950(4)
0 2833(1)
0 2828(1)
0 0611(3)
0 2109(4)
0 4207(5)
0 4383(5)
0 7693(3)
0 3031(4)
0 2807(4)
0 3674(4)
0 4746(4)
0 4908(3)
0 5988(3)
0 6966(4)
0 7907(4)
0 7899(3)
0 6914(3)
0 6815(3)
0 0712(1)
0 7972(1)
0 0230(2)
0 0015(3)
0 0899(4)
0 0231(5)
0 4384(3)
0 2108(3)
0 2303(4)
0 3117(4)
0 3742(4)
0 3527(3)
0 4167(3)
0 5042(3)
0 5576(3)
0 5239(3)
0 4364(3)
0 3903(3)
0 0234(1)
0 3283(1)
0 3571(2)
0 4290(3)
0 3082(3)
0 1411(4)
4 64(12)
3 66(14)
4 30(16)
4 58(17)
4 05(15)
3 09(13)
2 91(12)
3 75(14)
4 34(14)
3 97(13)
2 93(12)
3 15(12)
6 27(5)
N(1)A
N(2)A
N(3)A
C(1)A
C(2)A
C(3)A
C(4)A
C(5)A
C(6)A
C(7)A
C(8)A
C(9)A
C(10)A
C(11)A
SB
4 11(12)
4 05(14)
5 10(18)
5 15(18)
4 56(16)
3 27(12)
3 23(12)
4 52(15)
5 18(17)
4 25(14)
2 98(12)
3 02(12)
3 70(3)
Cl(2)
5 46(4)
Ow(1)
Ow(2)
Ow(3)
Ow(4)
4 77(10)
7 32(15)
8 07(17)
10 56(25)
N(1)B
N(2)B
3 00(10)
2 84(10)
Table 13. Atomic parameters for [Fe(bpyam)2] [BF4]2
Atom
x
y
z
Beq
Atom
x
y
z
Beq
Fe
O
0 5000
0 1273(1)
0 0058(4)
0 2528(5)
0 1219(4)
0 0916(5)
0 3224(7)
0 4109(7)
0 4272(7)
0 3546(6)
0 2690(6)
0 1872(6)
0 2500
3 24(4)
C(7)
C(8)
C(9)
C(10)
C(11)
B
F(1)
F(2)
F(3)
F(4)
0 1676(6)
0 1484(7)
0 2334(7)
0 3314(6)
0 4323(6)
0 1412(9)
0 0809(4)
0 1006(5)
0 1208(5)
0 2467(4)
0 1777(7)
0 1006(7)
0 0331(7)
0 0476(6)
0 0160(6)
0 1934(8)
0 1168(4)
0 1973(5)
0 2913(4)
0 1704(4)
0 1792(6)
0 1218(6)
0 0981(5)
0 1344(5)
0 1183(5)
0 0407(8)
0 0012(3)
0 1178(4)
0 0081(4)
0 0419(4)
4 39(25)
5 53(29)
4 71(26)
3 05(20)
3 36(22)
4 52(33)
5 15(14)
8 27(22)
8 29(22)
6 65(18)
0 5152(4)
0 4015(5)
0 3502(4)
0 4293(5)
0 4394(7)
0 3772(8)
0 2790(7)
0 2387(7)
0 3031(6)
0 2702(6)
0 1581(3)
0 3030(4)
0 1904(3)
0 0639(4)
0 3565(5)
0 3811(6)
0 3475(6)
0 2924(5)
0 2716(4)
0 2123(5)
4 34(16)
3 41(18)
2 65(15)
4 45(20)
4 49(25)
5 34(30)
4 76(27)
3 73(22)
2 95(21)
3 06(20)
N(1)
N(2)
N(3)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)

Donor Atom Set and Spin State of Iron(II)
283
Table 14. Atomic parameters for [Ni(bpyam)2] [BF4]2.H2O
Primes indicate disorder of the BF4 ion. The occupancies of the unprimed and primed disorder components are 0 527(6) and
0 473, respectively
Atom
x
y
z
Beq
Atom
x
y
z
Beq
Ni
OA
0 24679(8)
0 1275(5)
0 4148(5)
0 3665(5)
0 1229(7)
0 4299(7)
0 5440(9)
0 6466(8)
0 6334(7)
0 5140(7)
0 4891(7)
0 5760(7)
0 5349(9)
0 4070(9)
0 3264(7)
0 1835(8)
0 1566(5)
0 2774(6)
0 1184(5)
0 0194(6)
0 3639(8)
0 3819(10)
0 3070(11)
0 2133(10)
0 44579(9)
0 2902(5)
0 5345(6)
0 2946(6)
0 0809(7)
0 6605(9)
0 7105(9)
0 6227(11)
0 4918(10)
0 4504(8)
0 3130(8)
0 2063(10)
0 0844(10)
0 0673(8)
0 1771(8)
0 1844(9)
0 5232(5)
0 4291(6)
0 5944(6)
0 6928(7)
0 3449(9)
0 3487(11)
0 4420(11)
0 5325(9)
0 26029(8)
0 3222(4)
0 1799(5)
0 2280(5)
0 3276(7)
0 1557(7)
0 0992(7)
0 0698(7)
0 0949(6)
0 1499(5)
0 1797(6)
0 1607(7)
0 1930(9)
0 2438(8)
0 2581(6)
0 3075(7)
0 1135(4)
0 4207(5)
0 2890(5)
0 0197(6)
0 4818(7)
0 5833(8)
0 6243(8)
0 5637(7)
3 28(5)
4 00(8)
3 68(12)
3 44(7)
C(5)B
C(6)B
C(7)B
C(8)B
C(9)B
C(10)B
C(11)B
Ow
0 2024(7)
0 1083(7)
0 0166(8)
0 0604(8)
0 0468(7)
0 0441(6)
0 0763(7)
0 0894(5)
0 2638(4)
0 3097(6)
0 3144(6)
0 2967(7)
0 1345(4)
0 2317(7)
0 2049(10)
0 1925(12)
0 3597(8)
0 1699(11)
0 1947(8)
0 0693(9)
0 2603(12)
0 2066(15)
0 2424(11)
0 5222(7)
0 6138(7)
0 7161(8)
0 7924(8)
0 7713(8)
0 6683(7)
0 6252(8)
0 3717(6)
0 1403(4)
0 2401(6)
0 1643(6)
0 0253(6)
0 1317(7)
1 0254(7)
1 0913(13)
1 0876(15)
1 0224(10)
0 9004(9)
1 0214(9)
0 9731(13)
0 9233(13)
1 1186(16)
1 0707(14)
0 4611(6)
0 3881(6)
0 4113(7)
0 3312(8)
0 2293(8)
0 2119(6)
0 1082(6)
0 1895(5)
0 4378(4)
0 3507(5)
0 5348(4)
0 4426(7)
0 4231(6)
0 0721(7)
0 1835(8)
0 0139(14)
0 0428(9)
0 0482(12)
0 0651(9)
0 0839(12)
0 0077(11)
0 0211(17)
0 1633(10)
3 92(11)
3 60(13)
4 72(14)
5 13(15)
4 73(14)
3 77(11)
3 75(12)
6 33(15)
7 14(24)
11 8(2)
12 6(2)
15 8(4)
13 0(3)
7 0(2)
7 7(2)
11 1(3)
8 5(3)
13 9(4)
7 4(2)
10 8(3)
13 4(5)
11 4(3)
7 5(2)
N(1)A
N(2)A
N(3)A
C(1)A
C(2)A
C(3)A
C(4)A
C(5)A
C(6)A
C(7)A
C(8)A
C(9)A
C(10)A
C(11)A
OB
N(1)B
N(2)B
N(3)B
C(1)B
C(2)B
C(3)B
C(4)B
6 02(13)
4 56(14)
5 36(11)
5 52(20)
4 81(12)
3 67(12)
3 76(10)
5 11(14)
6 16(23)
5 25(13)
3 85(10)
4 30(10)
4 22(8)
BA
F(1)A
F(2)A
F(3)A
F(4)A
BB
F(1)B
F(2)B
F(3)B
F(4)B
BB0
3 77(14)
3 36(7)
5 44(15)
4 81(13)
6 80(20)
6 88(21)
5 76(22)
F(1)B 0
F(2)B0
F(3)B0
F(4)B0
11
dispersion parameters were from International Tables for X-Ray
Crystallography.34 ORTEP-II35 running on a Macintosh IIcx
was used for the molecular diagrams, and a DEC Alpha-AXP
workstation was used for calculations.
Atomic parameters for the structures are listed in Tables
10–14. Material deposited comprises all atom and thermal
parameters, interatomic distances, angles and torsional angles
and observed and calculated structure factors.
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Acknowledgment
We gratefully acknowledge support for this work
from the Australian Research Council.
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