Co(II), Ni(II), Cu(II) and Zn(II) complexes of tetraphenylazadipyrromethene

Article abstract of DOI:10.1039/b811764k

The synthesis, crystallographic and spectroscopic properties of four divalent isomorphous metal complexes of tetraphenylazadipyrromethene are described.

Full text of DOI:10.1039/b811764k

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PAPER
www.rsc.org/dalton | Dalton Transactions
Co(II), Ni(II), Cu(II) and Zn(II) complexes of tetraphenylazadipyrromethene†
Aniello Palma,a John F. Gallagher,b Helge Mu¨ller-Bunz,a Joanna Wolowska,c Eric J.L. McInnesc and
Donal F. O’Shea*a
Received 10th July 2008, Accepted 12th September 2008
First published as an Advance Article on the web 5th November 2008
DOI: 10.1039/b811764k
The synthesis, crystallographic and spectroscopic properties of four divalent isomorphous metal
complexes of tetraphenylazadipyrromethene are described.
Introduction
The development of new chromophores with spectral properties in
the near-infrared (NIR) and visible red spectral regions is an area
of expanding research interest. The synthesis and photophysical
characteristics of the BF2 chelated tetraarylazadipyrromethanes
1 (Fig. 1) have been recently reported from our laboratory
as having high extinction coefficients and substituent variable
fluorescence quantum yields in the 650–750 nm spectral region.1
To date, these favourable spectroscopic parameters have indicated
potential applications in photodynamic therapy,1a–d as fluorescent
Fig. 2 Tetraarylazadipyrromethenes and dipyrrin metal complexes.
chemosensors1f–h,2 and as in vitro fluorophores.1i
envisaged that this preliminary investigation of metal complexes
may form the basis for future designed uses in catalysis, metal–
organic frameworks, optical data storage and electrochromic
devices to list but a few.
Related metal complexes 3 with the dipyrrin ligand have been
reported for these metals in which a 1 : 2 metal–ligand complex
was formed.6 In several examples, it was shown that it was optimal
to have the C-1 and C-9 positions unsubstituted to ensure metal
complex formation as the introduction of substituents at these
Fig. 1 BF2-chelated tetraarylazadipyrromethenes.
positions could lead to unfavourable steric interactions.6c As such,
The penultimate step in the synthesis of these compounds is the
in the case of compounds 2, it was of particular interest to assess
formation of the BF2 chelate, which provides sufficient structural
the impact of the potential inter-ligand and metal–ligand steric
rigidity thereby limiting radiation-less transitions and allowing the
interactions of the aryl rings ortho to the pyrrole nitrogen atoms.
exploitation of their excited states. The compound class 2 was first
Possible influences would be to prevent formation of the chelate
reported sixty-five years ago but remained virtually unexploited
or have a pronounced effect on the stereochemistry of the ligands
until it attracted our interest (Fig. 2).3 In this original article it
around the metal centre and as a consequence have an impact
was reported that transition metal complexes could be formed
upon the spectroscopic properties. Herein, we have synthesised
but owing to the early date of this work no analytical data was
and characterised four divalent Co, Ni, Cu and Zn complexes
recorded. Recently, the synthesis and properties of tricoordinate
of tetraphenylazadipyrromethene 2a (Ar = Ph) as representative
AgI, AuI and CuI complexes of 2 (Ar = Ph) have been described.4
examples of this ligand class.
Herein, we describe the synthesis and characteristics of three
divalent transition metal derivatives CoII, NiII, CuII and ZnII
and compare their structural and spectroscopic properties.5 It is
Results and discussion
Synthesis
aCentre for Synthesis and Chemical Biology, School of Chemistry and
Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland.
Heating
(3,5-diphenyl-1H-pyrrol-2-yl)-(3,5-diphenylpyrrol-2-
E-mail: donal.f.oshea@ucd.ie; Tel: +353 (0)1 7162425
bSchool of Chemical Sciences, Dublin City University, Dublin 9, Ireland
cSchool of Chemistry, The University of Manchester, Oxford Road,
Manchester, UK M13 9PL
† Electronic supplementary information (ESI) available: ORTEP diagrams
for 4a, 4c and 4d. zqTOCSY spectrum of 4b. UV-vis spectra of 4a–d
in EtOH and toluene. EPR hyperfine coupling of 4c. CCDC reference
numbers 668337–668340. For ESI and crystallographic data in CIF or
other electronic format see DOI: 10.1039/b811764k
ylidene)amine 2a with CoCl2/NH4OAc, Ni(OAc)2, Cu(OAc)2 or
Zn(OAc)2 for 1 h in butanol at reflux gave a clean conversion
to the corresponding metal complexes 4a–d as assessed by TLC
analysis (Scheme 1).
In each case, the products 4a–d precipitated directly from the
reaction mixture and were isolated as brown/black powders in
high yields. Mass spectrometry confirmed a 1 : 2 stoichiometry
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Scheme 1
of M–2a (M = Co, Ni, Cu, Zn) for each complex. Crystals, suitable
for X-ray diffraction, were obtained by the slow evaporation of
either chlorobenzene or DMF solutions.
X-Ray crystallography
The structural studies of the four metal complexes 4a–d reported
herein are important in order to analyse their molecular conforma-
tions and the effects that subtle differences on metal complexation
between the parent ligand and metallo-derivatives can have
on a variety of physico-chemical properties. The examination
of the molecular structures of the four metal complexes 4a–d
revealed that they are isomorphous in the orthorhombic system,
space group Fdd2 (no. 43) with the metal centre residing on a
crystallographic two-fold axis (and with one half of the molecule
residing in the asymmetric unit). The bidentate and sterically bulky
ligand enforces a distorted tetrahedral geometry at the metal centre
that is remarkably invariant between the four metal complexes.
The metal geometry is best described as a distorted tetrahedron
with angles at the metal centre M falling into the ranges from 93–
95◦, 102–106◦ and 130–138◦ for the various groupings of N–M–N
angles (from an idealized tetrahedral 109.5 ◦) (Table 1, Fig. 3 and
ESI†).
The more ‘open’ and distorted geometry about the metal centres
also facilitates two contacts (per ligand) involving the ortho-H
atoms of the flanking phenyl groups with H5/H32 ◊ ◊ ◊ M of
◦
◦
˚
˚
ca. 2.68 A/2.77 A and C–H ◊ ◊ ◊ M angles of 118 /116 (Fig. 3,
bottom).
There are also subtle differences between the four metal
complexes in terms of the M–N bond lengths with Cu < Ni <
Co/Zn. In the Ni complex 4b, the average Ni–N bond length of
˚
1.97 A is intermediate between an ideal low-spin square planar
II
II
˚
˚
Ni –N bond length of 1.89 A and a high spin Ni –N of 2.10 A
for 4-coordinate Ni complexes. In a related bis[meso-phenyl-4,6-
dipyrrinato]NiII structure 3b (R¢ = Ph, R = H), the four Ni–N
Table 1 Selected geometric data for metal complexes 4a–d
Fig. 3 View of the Ni derivative 4b with displacement ellipsoids depicted
at the 30% probability level (top). Atoms with a suffix ‘a’ are related
through the 2-fold axis at the Ni atom. View of the metal core and the N4
geometry about the Ni atom (middle). View of 4b along the N2–Ni1 axis
and showing the H5/H32 ◊ ◊ ◊ Ni contacts with bond length and angle data
included for this 4b structure (bottom).
N1–M–N3/N3–M–N3/◦
a
˚
˚
M ◊ ◊ ◊ N2/A
Metal
M–N1/N3/A
4a, Co
4b, Ni
4c, Cu
4d, Zn
1.984(3)/1.974(3) 3.295(3)
1.971(3)/1.965(3) 3.322(3)
1.958(2)/1.949(2) 3.306(2)
1.992(2)/1.983(2) 3.290(2)
94.22(11)/130.92(16)
92.81(14)/131.8(2)
93.31(8)/137.86(13)
94.66(8)/130.07(12)
˚
˚
bond lengths are 1.879(2) A and almost 0.1 A shorter than in
a Symmetry operator 1/2 - x, 1/2 - y, z (for convenience in Fig. 3 the
symmetry equivalents are labelled with the suffix ‘a’).
˚
4b (though the 1.879(2) A is regarded as unusually short for
complexes of this type and due to the reduced ionic radius of
274 | Dalton Trans., 2009, 273–279
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the d8 low spin and reduced inter-ligand steric interactions).6c In
4b, these inter-ligand steric interactions are considerably increased
due to the four flanking phenyl groups at C7 and C26 (and their
symmetry equivalents) and resulting H5/H32 ◊ ◊ ◊ M contacts. In a
Cambridge Structural Database study of Ni tetraza macrocycles,
Donnelly and Zimmer have examined 150 such structures and
and negative peaks shifts (see ESI for Co spectra†).8 Specifically,
the spectrum of the Ni complex 4b was recorded between -1.2 to
61.6 ppm at room temperature (Fig. 4). In the NiII derivative,
the electronic magnetic field is less effective at shortening the
nuclear longitudinal relaxation times (T1) of the observed nuclei
usually associated with paramagnetic complexes. Four-coordinate
NiII complexes preferably adopt a planar geometry, but with 2a
as the ligand this is sterically impossible and a pseudo-tetrahedral
geometry results (Table 1 and Fig. 3). Nickel complexes of this
geometry, which have short electron-spin lifetimes can allow
well-resolved NMR signals to be obtained. Chemical shifts and
integrated intensities observed for 4b were as follows; -1.2 ppm
(2H), 0.4 ppm (1H), 7.2 ppm (1H), 7.4 ppm (2H), 8.6 ppm (2H),
34.6 ppm (2H), and 61.7 ppm (1H) (Fig. 4). The D2 symmetry
of 4b makes the two ligands equivalent and provides a C2-axis
through the bridging nitrogen atoms and the central metal. This
is confirmed by the chemical equivalence of both ligands and of
opposing phenyl rings within each ligand. Resonance assignments
are proposed based upon chemical shift, correlation spectra and on
the measured T1 values (Table 3). zqTOCSY experiments revealed
a correlation between the protons at -1.2, 0.4, and 7.4 ppm
indicating that they belong to the same spin system (ESI†). These
signals had measured T1 values of 64.5, 300 and 565 ms and
are assigned to Ho¢, Hm¢ and Hp¢, respectively, on the phenyl ring
furthest from the metal centre (Table 3). The protons for the
phenyl ring closer to the metal centre are assigned as the signals
at 34.6, 8.6 and 7.2 ppm with measured T1 values of 2.2, 31.8
and 97.8 ms, respectively. A cross peak between the resonances at
correlated Ni–N distances revealing two distinct sets of low-spin
7
˚
˚
(Ni–N < 2.02 A) and high-spin (Ni–N > 2.05 A) bond lengths.
In complexes 4a–d, differences of up to 7◦ are evident in some
of the N–M–N bond angles◦(Table 1). For example, the N1–
M–N1$ angles are 131.25(16) (Co), 134.3(2)◦ (Ni), 135.41(13)◦
(Cu) and 129.76(12)◦ (Zn) and with the analogous N3–M–N3$
angles listed in Table 3 for comparisons (where symmetry operator
$ = 1/2 - x, 1/2 - y, z). The interactions in 4a–d comprise
two intramolecular aromatic C–H ◊ ◊ ◊ N hydrogen bonds, with two
longer and weaker C–H ◊ ◊ ◊ p(arene) intermolecular interactions
of note (Table 2). These four interactions are invariant across
the four metal complexes. There are also several p ◊ ◊ ◊ p stacking
˚
interactions with perpendicular ring to ring distances of ca. 3.5 A
to complete the myriad of weaker intermolecular interactions.
1H NMR spectra
The paramagnetic copper complex 4c gave, as might be expected,
no recordable 1H NMR spectra whereas the diamagnetic Zn
complex 4d gave a well resolved spectrum in the typical 0–10 ppm
spectral region. Of more interest was the 1H NMR of the Ni and
Co complexes 4a and 4b, which displayed considerable positive
Table 2 H-bond interactions (bond lengths, A; bond angles, ◦) in the metal complexes 4a–d
˚
Metal, (M)
C15–H15 ◊ ◊ ◊ N2
C20–H20 ◊ ◊ ◊ N2
C12–H12 ◊ ◊ ◊ Cg1a
C31–H31 ◊ ◊ ◊ Cg2b
4a
4b
4c
4d
Co
Ni
Cu
Zn
3.043(4)/116
3.053(5)/116
3.058(3)/115
3.043(3)/116
3.029(4)/126
3.026(5)/126
3.029(3)/126
3.037(3)/126
3.548(3)/137
3.548(6)/136
3.560(3)/138
3.547(3)/136
3.606(3)/141
3.577(6)/142
3.602(3)/143
3.604(3)/141
a Cg1 is the five-membered ring centroid of {C17, C18, C25, C26, N3} at symmetry site -x, 1/2 - y, 1/2 + z. b Cg2 is the ring centroid of phenyl ring
{C10 ◊ ◊ ◊ C15} at symmetry position 1/2 + x, y, -1/2 + z.
Table 3 1H NMR data for 4ba
Resonance
d/ppm
T1/ms
Resonance
d/ppm
T1/ms
H◦
Hm
Hp
Hb
34.6
8.6
7.2
2.2
31.8
97.8
21.2
Ho¢
Hm¢
Hp¢
-1.2
7.4
0.4
64.5
300
565
61.6
a Room temperature.
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Fig. 4 600 MHz 1H NMR of 4b. Inset shows an expansion between -2 to 9 ppm.
8.6 and 7.2 ppm was observed in the zqTOCSY but not for the EPR spectra
34.6 ppm resonance potentially due to the broad nature of this
signal, Dn1/2 > 170 Hz, (ESI†). Despite this, the signal at 34.6 ppm
does show a relative integral for 2H, implying it must be either
the ortho or meta protons. The T1 value of 2.2 ms for this signal
was the shortest of any resonance in 4b and an examination of the
crystal structure shows that the ortho protons (Ho) are the closest
In D2 symmetry, the degeneracy of all five d orbitals is, in principle,
lifted. However, if we consider the geometry as a distortion
from “tetrahedral” (actually D2d ) via twisting of the two ligand
planes, then we might reasonably expect a (z2)(x2 - y2)(xz, yz)(xy)
ordering, where z is the bisector of the normals to the ligand planes.
On this basis, the CoII d7 compound 4a has S = 3/2 [(z2)2(x2 -
y2)2(xz, yz)2(xy)1] and EPR spectra should be observable because
of its orbital singlet nature.
˚
to the metal (2.67/2.78 A) and as such would be expected to have
the shortest T1 (Fig. 3 bottom and Table 1).9 Accordingly, the 8.6
and 7.2 ppm resonances are assigned as Hm and Hp, respectively.
The signal at 61.6 ppm (T1 = 21.2 ms) is assigned to the b-proton
on the pyrrole ring.
Indeed, as the temperature is decreased below ca. 40 K, intense
EPR transitions grow in at 0.94, 6.6 and 8.0 kG at X-band
(Fig. 5; at lower temperatures a further feature grows in at 3.3 kG,
we are unsure of its origin). These can be read as effective g
values (geff = 7.4, 1.1 and 0.87) due to transitions within the
Absorbance spectra
ground Kramers doublet (MS
=
1/2 or 3/2), which must be
well separated from the upper doublet by 2D >> hn, where D
is the axial zero-field splitting (ZFS) parameter defined in spin
Hamiltonian (eqn (1)).10 This situation is common for pseudo-
tetrahedral CoII species, and similar spectra have been observed
for [{H2B(pz)2}2Co] (H2B(pz)2 = dihydrobis(1-pyrazolyl)borate),
which also has a CoN4 coordination sphere.11
The UV-vis spectra for the complexes 4a, 4b and 4d display
similar spectral characteristics with the lmax values between 593–
603 nm in CH2Cl2 and extinction coefficients varying from 65 000–
142 000 M-1cm-1 (Table 4). Uniquely, the copper complex 4c
showed a clear splitting of the longest wavelength band with l
values of 566–640 nm, which may be indicative of the strain within
the ligand while the other complexes exhibited distinct red-shifted
shoulders of the main absorption band. Minor hypsochromic
shifts in ethanol and bathochromic shifts in toluene were observed
in each case. The similarity of the metal chelates with the free
ligand 2a (lmax 593 nm in CH2Cl2) suggests the absorption
is primarily ligand centred with band broadening and minor
hypsochromic shifts observed upon metal chelation. In contrast
to the BF2 chelated derivatives 1, each of the complexes 4a–d were
non-fluorescent.
2
2
2
ˆ
ˆ
ˆ
ˆ
H = mBBgS + D[Sz - S(S + 1)/3] + E(Sx - Sy )
(1)
The assignment is confirmed by W-band (94 GHz) spectra at
10 K, where now only one transition is observed, with geff = 7.2,
the low geff features being beyond the 6 T limit of the magnet.
Pilbrow has considered the geff values that arise for large positive
and negative D as a function of the rhombic ZFS parameter E
(eqn (1)).10 It is clear from his results that geff < 1 can only easily
arise within the MS
=
3/2 doublet: assuming g = 2.0, values
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Table 4 Comparative UV-vis spectra of 2a and 4a–da,b
Compound
CH2Cl2 lmax/nm
EtOH lmax/nm
Toluene lmax/nm
e/M-1cm-1c,d
2a (green)
4a (black)
4b (red)
4c (blue)
4d (brown)
596
602
603
640/567
593
592
599
599
639/562
590
601
607
606
642/567
596
52.4
94
142
65.7/62.8
78.6
a Shown in CH2Cl2. b (8.7–9.1 ¥ 10-6 M). c CH2Cl2. d ¥ 10-3.
geff = 1.1 and 0.87 resonances is found for |E/D| = 0.16 (Fig. 5);
further refinement to fit gezff gives gz = 2.3. Although this procedure
does not define the magnitude of |D|, from systematic variations
it must be greater than ca. 15 cm-1, since for values below this we
should observe transitions within the excited MS = 1/2 doublet
(the 3.3 kG feature is not consistent with such transitions). Note
the ZFS is much more sensitive than the g values to deviations of
the symmetry from axial.
The NiII d8 complex 4b is EPR silent at all frequencies (X-
and W-band) and temperatures (300–4.2 K) studied, despite its
paramagnetism. Adopting the same d orbital ordering we have
(z2)2(x2 - y2)2(xz, yz)3(xy)1, hence the ground term is a spin triplet
but an orbital doublet. The orbital moment gives rise to rapid
electronic relaxation, which can broaden EPR spectra beyond
detection. A further consequence is that relatively sharp NMR
spectra are observed, see above, in contrast with the orbital singlet
CoII species.
Powder EPR spectra of the CuII, d9 complex 4c appear axial at
X-band but are in fact slightly rhombic as resolved at K-band
(24 GHz) frequency (g = 2.25, 2.08, 2.06, Fig. 6). In frozen
solution, the spectra are axial within the resolution of K-band,
implying that the structure relaxes slightly in solution, consistent
with the NMR spectra of the nickel analogue (see above). The
X-band frozen solution spectra show hyperfine coupling to both
63,65Cu and to 14N nuclei, which can be simulated with the (S = 1/2)
spin-Hamiltonian parameters: gz = 2.248, gx,y = 2.065, Az(Cu) =
115 G, Ax,y(Cu) = 16 G, Ax,y(4 ¥ N) = 9.0 G and an arbitrarily
small Az(N) (see, ESI†).
Note the near-axial g values imply the xz, yz pair are near-
degenerate [(z2)2(x2 - y2)2(xz, yz)4(xy)1] although this is not
imposed in D2 (indeed in the solid state we observe gx π gy). D2
does require that the principal axes of the g and A(Cu) matrices
are coincident and that they are co-parallel with the three two-fold
Fig. 5 X-band EPR spectrum of a powder of 4a at 10 K (black) and
simulation (red) with the parameters: S = 3/2, gz = 2.3, gx,y = 2.0, E/D =
-0.16 where D is negative and |D| > ca. 15 cm-1.
eff
z,x,y
of g
= 6, 0, 0 or 5.464, 2.0, 1.464 are derived for the limiting
cases of |E/D| = 0 (axial symmetry) and 1/3 (rhombic limit),
respectively, (E/D > 1/3 implies a redefinition of axes). Although
non-coincidence between the principal axes of the g matrix and D
tensor can give rise to unusual geff within MS = 1/2,12 this is not
allowed in the D2 symmetric 4a. Hence, the ground state doublet
in 4a is MS = 3/2 (i.e. D is negative). We can simulate the spectra
(X- and W-band) using spin Hamiltonian (eqn (1)) with S = 3/2.
As the limiting values above suggest, gexff and gyeff are very sensitive
to the ratio E/D. We initially fixed an isotropic g = 2.0 and varied
E/D for an arbitrarily large, negative value of D. The best fit to the
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cooled to room temperature and the precipitate◦ filtered as a
1
red/brown powder (0.261 g, 82%), mp: 326–327 C. H NMR
(CDCl3, 600 MHz) d/ppm: -1.22 (d, 8H, J = 7.38 Hz), 0.38 (t,
4H, J = 6.90 Hz), 7.17 (bs, 4H), 7.38 (t, 8H, J = 7.02 Hz), 8.65
(bs, 8H), 34.62 (bs, 8H), 61.67 (s, 4H). 13C NMR (CDCl3, 151
MHz) d/ppm: 21.5, 85.1, 107.2, 126.4, 129.1, 155.6, 159.3, 193.6,
201.3, 225.2, 499.3, 500.4, 751.0. UV-vis (CH2Cl2) lmax/nm: 603.
ES-MS (m/z): [M + H]+ 955.2. HRMS: calcd for C64H45N6Ni:
[M + H]+ 955.3059, found: 955.3087. IR (KBr disc) n/cm-1: 1260,
1447, 1519, 2922. Crystals were grown by the slow evaporation of
a DMF solution.
Bis[(3,5-diphenyl-1H-pyrrol-2-yl)(3,5-diphenylpyrrol-2-
ylidene)amine]CuII (4c)
Compound 2a (0.30 g, 0.668 mmol) and copperII acetate (0.150 g,
0.8228 mmol) in n-butanol (15 mL) was stirred for 1 h at reflux,
cooled to room temperature and the precipitate filtered as a
black powder, (0.240 g, 75%), mp: >300 ◦C (decomposition).
UV-vis (CH2Cl2) lmax/nm: 566, 640. ES-MS (m/z): [M + H]+
960.3. HRMS calcd for C64H45N6Cu: [M + H]+ 960.3002, found:
960.3033. IR (KBr disc) n/cm-1: 1365, 1447, 1519, 2918. Crystals
were grown by the slow evaporation of a DMF solution.
Fig. 6 K-band (ca. 24 GHz) EPR spectra of a powder (top) and a frozen
CH2Cl2–toluene (10 : 1 v/v) solution (bottom) of 4c.
symmetry axes of the molecule. Since we expect the largest g and
A to be normal to the xy magnetic orbital we assign these as z.
This assignment is also consistent with the observation of the large
component of the (four equivalent) 14N hyperfine in the xy plane
(see, ESI†).
Bis[(3,5-diphenyl-1H-pyrrol-2-yl)(3,5-diphenylpyrrol-2-
ylidene)amine]ZnII (4d)
Conclusion
Compound 2a (0.30 g, 0.668 mmol) and zincII acetate (0.1586 g,
0.869 mmol) in n-butanol (15 mL) was stirred for 1 h at reflux,
cooled to room temperature and the precipitate◦ filtered as a
The synthesis, solution and solid state spectral properties of four
divalent metal complexes of the tetraphenylazadipyrromethene
ligand are described, which should facilitate future designed
studies and applications.
1
dark green powder (0.273 g, 85%), mp: 312–313 C. H NMR
(400 MHz, CDCl3) d/ppm: 6.71 (s, 4H), 7.09 (m, 12H), 7.40 (m,
12H), 7.49 (m, 8H) 7.85 (m, Hz, 8H). 13C NMR (CDCl3, 101 MHz)
d/ppm: 117.05, 126.82, 127.55, 127.99, 128.04, 129.12, 129.70,
133.24, 134.35, 145.25, 147.88, 160.43. UV-vis (CH2Cl2) lmax/nm:
593. ES-MS (m/z): [M + H]+ 961.6. HRMS calcd for C64H45N6Zn:
[M + H]+ 961.3022, found: 961.2997. IR (KBr disc) n/cm-1: 1246,
1542, 2922. Crystals were grown by the slow evaporation of a
DMF solution.
Experimental
General
Compound 2a was synthesised as described in ref. 1b. The
complexes’ formation reactions were carried out exposed to air.
Bis[(3,5-diphenyl-1H-pyrrol-2-yl)(3,5-diphenylpyrrol-2-
X-Ray data collection, structure solution and refinement
ylidene)amine]CoII (4a)
Data were collected on a Bruker SMART APEX CCD diffrac-
tometer for 1a at room temperature (293 K) and for 4a–d at
100 K. Data were collected on a hemisphere of reciprocal space
using f–w scans with an empirical absorption correction applied
using SADABS.13 All four Co, Ni, Cu and Zn metal complexes
4a–d are isomorphous structures in the space group (Fdd2, no.
43). Solution and refinement was undertaken using SHELXS-97
and SHELXL-9714 and the graphics generated with PLATON.15
Hydrogen atoms were included as riding atoms in 4a–d with the
SHELXL-97 defaults at the appropriate temperatures. Pertinent
geometric data for structures 4a–d are included in Table 1–3.
Crystallographic data for 4b (representative of 4a–d). 4b,
chemical formula C64H44N6Ni, black blocks, molecular weight =
Compound 2a (0.20 g, 0.445 mmol) and ammonium acetate
(0.20 g, 2.6 mmol) in n-butanol (7 mL) were added to a solution of
cobaltII chloride hexahydrate (0.130 g, 0.548 mmol) in n-butanol
(3 mL). The mixture was stirred for 1 h at reflux, cooled to room
temperature and the prec◦ipitate filtered as a dark brown powder
(0.15 g, 70%), mp: >300 C (decomposition). 1H NMR (CDCl3,
600 MHz) d/ppm: 64.38 (m, 4H), 16.14 (m, 8H), 14.40 (m, 8H),
8.98 (m, 8H), 6.20 (m, 4H), 4.60 (m, 4H), -13.52 (m, 8H). UV-vis
(CH2Cl2) lmax/nm: 602. ES-MS (m/z): [M + H]+ 956.2. HRMS:
calcd for C64H45N6Co: [M + H]+ 956.3038, found: 956.3063. IR
(KBr disc) n/cm-1: 1519, 2920. Crystals were grown by the slow
evaporation of a chlorobenzene solution.
955.76 g mol-1, orthorhombic, space group Fdd2 (no. 43), a =
Bis[(3,5-diphenyl-1H-pyrrol-2-yl)(3,5-diphenylpyrrol-2-
3
˚
˚
19.842(3), b = 44.333(5), c = 10.7588(14) A, V = 9464(2) A ,
Z = 8, T = 100(2) K, Dcalcd = 1.342 g cm-3, F(000) = 3984,
m = 0.461 mm-1, 9708 reflections to q = 24.2◦, 3176 unique (with
2642 I > 2s(I)), 322 parameters, R factor is 0.047, wR2 = 0.087
ylidene)amine]NiII (4b)
Compound 2a (0.30 g, 0.668 mmol) and nickelII acetate (0.160 g,
0.904 mmol) in n-butanol (15 mL) was stirred for 1 h at reflux,
278 | Dalton Trans., 2009, 273–279
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(based on F2 for with I > 2s(I)) using SHELXL-97 as the
refinement program, GOf = 1.03, density range in final D map
3 M. A. T. Rogers, J. Chem. Soc., 1943, 590.
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5 During the completion of this manuscript, the ZnII complex appeared
in the literature: T. S. Teets, D. V. Partyka, J. B. Updegraff III and T. J.
Gray, Inorg. Chem., 2008, 47, 2338.
-3
˚
is -0.58 to +0.40 e A .
Acknowledgements
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AO and DOS acknowledge funding support from the Program
for Research in Third-Level Institutions administered by the
HEA. Thanks to Dr D. Rai of the CSCB Mass Spectrometry
Centre and Dr J. Muldoon and Dr Y. Ortin of the CSCB NMR
facility. JW and EJMI thank EPSRC (UK) for funding and Prof.
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