Synthesis and characterization of tetraphenylporphyrin iron(III) complexes with substituted phenylcyanamide ligands

Article abstract of DOI:10.1016/j.ica.2006.01.015

Several five coordinate complexes of [(TPP)Fe^III(L)] in which TPP is the dianion of tetraphenylporphyrin and L is the monoanion of phenylcyanamide (pcyd) (1), 2,5-dichlorophenylcyanamide (2,5-Cl₂pcyd) (2), 2,6-dichlorophenylcyanamide (2,6-Cl₂pcyd) (3), and 2,3,4,6-tetrachlorophenylcyanamide (2,3,4,6-Cl₄pcyd) (4) have been prepared by the reaction of [(TPP)Fe^IIICl] with appropriate thallium salt of phenylcyanamide. Each of the complexes has been characterized by IR, UV-Vis and ¹H NMR spectroscopic data. Dark red-brown needles of [(TPP)Fe^III(2,6-Cl₂pcyd)] (C₅₁H₃₁Cl₂FeN₆ · CHCl₃) crystallize in the triclinic system. The crystal structure of Fe(III) compound shows a slight distortion from square pyramidal coordination with the 2,6-dichlorophenylcyanamide anion in the axial position through nitrile nitrogen atom. Iron atom is 0.47(1) A? out of plane of the porphyrin toward phenylcyanamide ligand. In non-coordinating solvents, such as benzene or chloroform, these complexes exhibit ¹H NMR spectra that are characteristic of high-spin (S = 5/2) species. The X-ray crystal structure parameters are also consistent with high-spin iron(III) complexes. The iron(III) phenylcyanamide complexes are not reactive toward molecular oxygen; however, these complexes react with HCl and produce TPPFe^IIICl.

Full text of DOI:10.1016/j.ica.2006.01.015

Inorganica Chimica Acta 359 (2006) 2101–2106
www.elsevier.com/locate/ica
Synthesis and characterization of tetraphenylporphyrin
iron(III) complexes with substituted phenylcyanamide ligands
a
a,
a
Hossein Chiniforoshan , Nasser Safari *, Jafar Mohammad Nezhad ,
b
c
Hassan Hadadzadeh , Amir H. Mahmoudkhani
a
Department of Chemistry, Shahid Beheshti University, 1983963113, Evin, Tehran, Iran
Department of Chemistry, Sistan and Baluchestan University, 98135674, Zahedan, Iran
b
c
Department of Chemistry, University of Calgary, Alta., Canada T2N 1N4
Received 4 October 2005; received in revised form 1 January 2006; accepted 15 January 2006
Available online 3 March 2006
Abstract
Several five coordinate complexes of [(TPP)FeIII(L)] in which TPP is the dianion of tetraphenylporphyrin and L is the monoanion of
phenylcyanamide (pcyd) (1), 2,5-dichlorophenylcyanamide (2,5-Cl2pcyd) (2), 2,6-dichlorophenylcyanamide (2,6-Cl2pcyd) (3), and
2,3,4,6-tetrachlorophenylcyanamide (2,3,4,6-Cl4pcyd) (4) have been prepared by the reaction of [(TPP)FeIIICl] with appropriate thallium
1
salt of phenylcyanamide. Each of the complexes has been characterized by IR, UV–Vis and H NMR spectroscopic data. Dark red-
brown needles of [(TPP)FeIII(2,6-Cl2pcyd)] (C51H31Cl2FeN6 Æ CHCl3) crystallize in the triclinic system. The crystal structure of Fe(III)
compound shows a slight distortion from square pyramidal coordination with the 2,6-dichlorophenylcyanamide anion in the axial posi-
˚
tion through nitrile nitrogen atom. Iron atom is 0.47(1) A out of plane of the porphyrin toward phenylcyanamide ligand. In non-coor-
dinating solvents, such as benzene or chloroform, these complexes exhibit 1H NMR spectra that are characteristic of high-spin (S = 5/2)
species. The X-ray crystal structure parameters are also consistent with high-spin iron(III) complexes. The iron(III) phenylcyanamide
complexes are not reactive toward molecular oxygen; however, these complexes react with HCl and produce TPPFeIIICl.
Ó 2006 Elsevier B.V. All rights reserved.
Keywords: Iron(III)phenylcyanamide; Tetraphenylporphyrin; X-ray; Paramagnetic 1H NMR
1. Introduction
both neutral and anionic forms with metals, such as AgI,
CuI, CuII, NiII, PdII, RuII, CoII, WIII and MnII.
Material engineering adopted to generate new electronic,
magnetic and photonic devices is an active field [1–6]. To
obtain high conductivity as well as strong effective magnetic
coupling, expansion of the p-electronic molecular structure
is one of the most important and promising approaches [7–
9]. For example, [TPPMn][tetracyanoethylene] Æ 2PhMe has
shown to act as molecule-based magnet [10–13] and (2,5-
dimethyl-N,N0-dicyanoquinone diimine)2Cu (DCNQI) has
shown to exhibit extremely high conductivity of
500000 S cmꢀ1 at 3.5 K [14]. Crutchley [15] has investigated
phenylcyanamide (ligands as analogue of DCNQI’s) in
Moreover, the biological and chemical importance of
iron porphyrins make the nature of the metals–ligand
linkage in these complexes of considerable interest [16–
19]. Numerous structural and physical characterizations
of iron porphyrin with different axial groups have been
reported during the last decades. One of the aims of these
investigations is to couple large p-conjugated system of
porphyrins into a large p-conjugate system in phenylcya-
namide via bridged iron metals, which hybrid coordinate
with organic p-stack systems, to produce building blocks
for molecular materials. So, we here wish to report the
first example of preparation and characterization of
phenylcyanamide-ligated tetraphenylporphyrin iron(III)
*
Corresponding author. Tel.: +98 21 2401765; fax: +98 21 2403041.
1
(L) complexes (1–4). It has become clear that H NMR
E-mail address: n-safari@cc.sbu.ac.ir (N. Safari).
0020-1693/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2006.01.015

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H. Chiniforoshan et al. / Inorganica Chimica Acta 359 (2006) 2101–2106
Table 1
spectroscopy in paramagnetic iron porphyrin species is a
valuable tool [20–25] for studying the electronic and mag-
netic properties of these compounds. In this report, we
have shown, by using NMR spectroscopy, that phenylcya-
namides are capable of long electron/spin transfer. These
complexes were also characterized by electronic and IR
spectroscopy. The structure of 2,6-dichlorophenylcyana-
midotetraphenylporphyrin iron(III) was determined by
single-crystal X-ray diffraction technique.
Crystal data for [TPPFe(2,6-Cl2pcyd)] Æ CHCl3 (3)
Empirical formula
Formula weight
Crystal system
Space group
C51H31Cl2FeN6 Æ CHCl3
973.94
triclinic
ꢀ
P1
˚
a (A)
10.985(1)
11.350(1)
18.824(2)
95.834(6)
100.852(6)
101.253(5)
2237.2(5)
2
1.446
123(2)
0.71073
0.482 and ꢀ0.558
0.056
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
3
˚
2. Experimental
V (A )
Z
Dcalc (Mg mꢀ3
)
2.1. Reagents and materials
T (K)
k (Mo Ka) (A)
Maximum and minimum transmission
R factora
Rw factorb
˚
Caution: Thallium is toxic. Dichloromethane, N,N-
dimethylformamide, methanol, p-chloranil, benzene, n-hex-
ane, benzaldehyde, benzophenone, I2, Na and Mg were all
of reagent grade and purchased from Merck. Pyrrole was
purchased from Fluka. Prior to use, dichloromethane and
methanol were distilled over P2O5 and Mg + I2, respec-
tively. n-Hexane and benzene were distilled over Na and
benzophenone, respectively. All reactions involving phe-
nylcyanamide coordination to iron(III)porphyrin were car-
ried out under nitrogen using standard schlenk technique.
Tetraphenylporphyrin (TPPH2) and TPPFeCl were synthe-
sized according to Lindsey’s [26] and Adler’s methods [27],
respectively. Extra care was necessary to exclude traces of
impurity of l-oxo dimer from TPPFeIIICl by pre-treatment
of TPPFeCl with HCl. Thallium salts of phenylcyanamide
ligands (pcydꢀTl+) were prepared following the previously
reported procedure [28].
0.141
P
P
a
R = ||Fo| ꢀ |Fc||/ |Fo|.
P
P
b
Rw = ( w(|Fo| ꢀ |Fc|)2/ w|Fo|2)1/2
.
700 Cryostream low-temperature device with graphite
monochromated Mo Ka radiation (k = 0.71073 A). Total
˚
number of 114 frames were collected with two oscillation
modes (u + x) at 1.7° oscillation angle and exposure time
of 200 s per frame, affording a selected redundancy of 2.
The data were integrated using DENZO SMN [29] and
processed using DENZOX. Absorption effects were cor-
rected by Gaussian quadrature. Full-matrix least-squares
refinement on F2 was carried out using SHELXL97 [30] with
no applied constraints applied. All calculations were car-
ried out using the WINGX software package [31]. The results
are summarized in Table 1.
2.2. Physical measurements
2.3. Preparation of [TPPFeIII(2,6-Cl2pcyd)] (3)
2.2.1. Spectroscopy
TPPFeCl powder (50.0 mg, 0.071 mmol) and thallium
salt of 2,6-Cl2pcyd (83.0 mg, 0.213 mmol) were placed in
a two-neck round-bottomed flask. After 30 min under vac-
uum, the flask was placed under N2 atmosphere (schlenk
technique). Dichloromethane was transferred to the reac-
tion flask and stirred for 24 h at room temperature. Then,
the mixture was filtered and the volume of the filtrate was
reduced to approximately 10 ml. Then, dried n-hexane
(50 ml) was added slowly to the reaction flask while stir-
ring. The precipitate was removed by filtration and dried
while standing in air. Other compounds (2) and (4) were
prepared by the same procedure, except that 2,6-Cl2pcyd
was replaced by appropriate phenylcyanamide derivatives.
Compound 1 was prepared by the above procedure, except
that dry dichloromethane and 2,6-Cl2pcyd were replaced
by dry benzene and phenylcyanamide, respectively.
UV–Vis spectra were obtained on a shimadzu 2100 spec-
trometer in benzene at room temperature. Infrared spectra
(4000–600 cmꢀ1) of solid samples were taken as 1% disper-
sion in KBr pellet using a Shimadzu-470 spectrophotometer.
1H NMR spectra were recorded on a Bruker AC-300 MHz
spectrometer operating in the quadrature mode. The
spectra were collected over a 50-kHz bandwidth with 16 K
data points and a 5-ls 45° pulse. For a typical spectrum,
between 1000 and 5000 transients were accumulated with a
50-ms delay time. The signal-to-noise ratio was improved
by apodization of the free inducting decay. Elemental
analysis was performed using a Heraeus CHN–O rapid
analyzer.
2.2.2. X-ray structural determination of [TPPFeIII(2,6-
Cl2pcyd)] Æ CHCl3 (3)
Needle-like dark red-brown crystals of [TPPFeIII(2,6-
Cl2pcyd)] Æ CHCl3 (3) were grown by slow evaporation of
CHCl3 solution in a temperature range of 20–25 °C under
N2 atmosphere. Crystal data are shown in Table 1. Sin-
gle-crystal diffractions were collected on a Nonius Kappa
CCD instrument fitted with an Oxford Cryosystems Series
IR, UV–Vis data and yields of products are summarized
in Table 2. Anal. Calc. for 1, C51H33FeN6 (785.718): C,
77.9; H, 4.2; N, 10.7. Found: C, 76.5; H, 4.1; N, 10.2%.
Anal. Calc. for 3, C51H31Cl2FeN6 (854.602): C, 71.6; H,
3.6; N, 9.8. Found: C, 71.0; H, 3.8; N, 9.0%. Anal. Calc.
for 4, C51H29Cl4FeN6 (923.492): C, 66.3; H, 3.2; N, 9.1.

H. Chiniforoshan et al. / Inorganica Chimica Acta 359 (2006) 2101–2106
2103
Table 2
desired compound and thus we are not reporting the results
in this paper. The reaction yields for compounds 1–4 were
quantitative, although during the process of precipitation
and isolation 20–30% of the products were lost. These
products are less sensitive to moisture or molecular oxygen
after formation. So, no effort was made to exclude air or
moisture for spectroscopic studies; however, crystals of 3
were grown under dry N2 atmosphere at room tempera-
ture. All compounds are fairly soluble in non-coordinating
solvents, except saturated hydrocarbons. Phenylcyanamide
derivative complexes readily react with HCl and result in
the formation of starting TPPFeCl.
UV–Vis electronic absorptiona and IR datab for TPPFe-L complexes and
thallium salts of phenylcyanamide
Complex
UV–Visc
m(NCN)d,e
Yield
(%)
Soret Q bands Thallium Complex
band
salt
TPPFeCl
TPPFe(pcyd)
TPPFe(2,5-Cl2pcyd)
TPPFe(2,6-Cl2pcyd)
TPPFe(2,3,4,6-Cl4pcyd) 414.5 512, 654 2090
416.5 509, 657
417.5 509, 572 2050
416 503, 632 2105
415.5 512, 648 2050
2080
2115
2065
2125
65
76
68
73
a
In nm.
b
In cmꢀ1
.
c
d
e
In benzene.
KBr disk.
Strong.
4. Spectroscopic characterization
1
4.1. H NMR studies
Found: C, 67.7; H, 3.6; N, 8.7% (while %C is not very sat-
isfactory, fractional solvent could improve the fit and H
1
1
The H NMR spectra of chloro substituted phenylcya-
NMR support the purity of the compounds).
namide complexes are shown in Fig. 1 and full assignments
of signals for compounds 1–4 are shown in Table 3. Reso-
nance assignments have been made on the basis of relative
intensity, line width, previous assignments of TPPFe-X
moiety in high-spin Fe(III)complexes and direct compari-
son of signals in compounds 1–4.
For example, trace of 4 in Fig. 1 shows two signals at
75.9 and 25 ppm, which are assigned, respectively, to the
b-pyrrole hydrogens and the only hydrogen present in meta
position of phenylcyanamide ligands. Trace of 3 in Fig. 1
has shown a new signal high field region at ꢀ47 ppm with
half intensities of signal in 30 ppm. So this signal in
ꢀ47 ppm has been assigned to 4-H for compound 3. These
assignments were reconfirmed with the traces of 2 and 1. In
3. Results and discussion
Until the present work, to the best of our knowledge, no
studies of phenylcyanamide derivatives of iron were
reported in the literature, where we described the first syn-
thesis, spectroscopic and X-ray characterization of iron(III)
porphyrin phenylcyanamide derivatives.
The FeIIIporphyrin complexes of phenylcyanamide
derivatives were synthesized in generally good yields by fol-
lowing metathesis reaction in refluxing dry benzene or
dichloromethane. This reaction was very sensitive to mois-
ture and a lesser extent to molecular O2. Exposure of traces
of water resulted in the formation of l-oxo dimer, TPPFe-
O-FeTP. l-Oxo dimer impurity is hard to remove, since
chromatography on silica gel or aluminum oxide may lead
to its additional formation. The reaction yields were quan-
titative for phenylcyanamide and chloro substituted phe-
nylcyanamides (1–4).
C 6 H 6
TPPFeL + TlCl
TPPFeCl + TlL
r.t
5
3
6
2
4
N
C N
L
=
1
(1)
(2)
(3)
(4)
2,3,4,5,6 H
3,4,6 H
3,4,5 H
5 H
2,5 Cl
2,6 Cl
2,3,4,6 Cl
A different mixture of TPPFe-Cl, TPPFe-O-FeTPP and
TPPFe(phenylcyanamide) was obtained in each prepara-
tion, when an electron donating substituent, such as methyl
or mesithyl substituted phenylcyanamide was employed. In
such cases, we were not able to separate and isolate a pure
Fig. 1. 1H NMR spectra of iron(III)porphyrin complexes: TPPFepcyd (1),
TPPFe(2,5-Cl2pcyd) (2), TPPFe(2,6-pcyd) (3), and TPPFe(2,3,4,6-
Cl4pcyd) (4), in C6D6 at 300 K.

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H. Chiniforoshan et al. / Inorganica Chimica Acta 359 (2006) 2101–2106
Table 3
1H NMR spectral data of TPPFe-L complexesa
Complex
pyrr-H
m-H
o-H
p-H
H2
H3
H4
H5
36
H6
TPPFeCl
TPPFe(pcyd)
80
12.1, 13.5
12.4, 11.4
12.7, 11.7
12.4, 11.4
12.7, 11.7
8.0
8.2
8.3
8.1
8.1
6.5
6.5
6.6
6.4
6.4
77.4
75.5
77.2
75.9
ꢀ58
36
32
30
ꢀ54
ꢀ45
ꢀ47
ꢀ58
ꢀ54
TPPFe(2,5-Cl2pcyd)
TPPFe(2,6-Cl2pcyd)
TPPFe(2,3,4,6-Cl4pcyd)
a
30
25
In C6D6, data in ppm vs. TMS reference at 0.00 ppm at 300 K.
addition, new broad signals around ꢀ58 ppm in com-
pounds 1 and 2 were assigned to the only hydrogens left
to be assigned in 2 and 6 positions (ortho) of coordinated
phenylcyanamides. Signals of phenyl of tetraphenyl por-
phyrins have been seen in almost the same place for TPP-
these compounds have an admixed spin state with a fairly
high degree of S = 5/2 character.
Crutchley has suggested that phenylcyanamides are
expected to be the same as pseudo halide [15]. Pyrrole posi-
tion of phenylcyanamide derivatives here confirms that the
strength of phenylcyanamide is slightly weaker than halides
and psuedo halide ligands [33,34].
1
FeCl, Table 3. The effect of temperature on the H NMR
spectrum of hydrogens of phenylcyanamide for 3 in chloro-
form solution is shown in Fig. 2, where the chemical shifts
for the pyrrole protons, 3,5-H and 4-H, are plotted versus
1/T (Kꢀ1). Each resonance shows linear behavior. This is
consistent with the presence of a monomeric paramagnetic
complex.
4.2. IR and UV–Vis studies
Cyanamide group, a three atom p-system, is a poor p-
acceptor system but it is a good p-donor of nitrile ligands.
Three modes of coordination have been recognized for
phenylcyanamide metal complexes, A, B and C [35–38].
1H NMR spectroscopy has been uniquely shown to be a
definitive method for detecting and characterizing iron por-
N
C
N
H
N
C
N
N
C
N
A
B
C
phyrins. The hyperfine shift patterns are sensitive to the
iron oxidation, spin and ligation state. Particularly, pyrrole
protons provide a direct probe of the porphyrins macrocy-
cle [32]. Magneto chemical series proposed by Reed et al. is
based on the degree of S = 5/2, 3/2 spin state admixture
engaged by axial ligands in TPPFe-X type complexes
IR spectroscopy can be used to identify which coordina-
tion mode of phenylcyanamide binds to the metal com-
plexes. It can differentiate nitrile versus amide
coordination in both anionic and neutral form of phenylc-
yanamides [39]. Neutral phenylcyanamide, A, has shown
m(C„N) around 2225–2250 cmꢀ1 [20,24] and coordinated
nitrile in FeIII–CN complexes was reported at 2129 cmꢀ1
[23]. The Coordination of anionic phenylcyanamide ligand
via nitrile nitrogen produced a characteristic strong bond
in the frequency lower than 2150 cmꢀ1 in both thallium
salts and compounds (1–4), Table 2. In each case, the
1
[33,34]. H NMR b-pyrrole shift with the given range of
ꢀ62 ppm for pure intermediate spin state, S = 3/2, to
+80 ppm for high spin, S = 5/2, species at 25 °C was used
as an indicator of the degree of admixture. The pyrrole
chemical shift for 1–4 around 77–75 ppm indicates that
m
CN absorption is consistent with the presence of resonance
form of C. The m(N@C@N) in iron(III) phenylcyanamide
complexes has consistently shifted around 5–35 cmꢀ1 to
higher frequency relative to the thallium salts. The same
trend was observed for tetraphenylporphyrin mangan-
ase(III) complexes of phenylcyanamides [40].
Differentiation of the nature of axial ligands of iron(III)
porphyrin is often possible by UV–Vis spectra [41]. Fig. 3
shows UV–Vis spectra of compounds 1 and 4 in benzene
in comparison to TPPFeCl. These spectra and the results
for other compounds in Table 2 indicate similarity of elec-
tronic spectra of prepared compounds. The kmax values of
the phenylcyanamide-ligated species are in the same range
V.T.
a
80
40
b
0
-40
c
-80
3
3.4
3.8
4.2
1/T x 10-3
Fig. 2. Plot of the chemical shift vs. 1/T (K) for the pyrrole (a), 3,5-H; (b)
and 4-H (c) resonances of 3 in chloroform solution.

H. Chiniforoshan et al. / Inorganica Chimica Acta 359 (2006) 2101–2106
2105
Fig. 3. UV–Vis spectra of TPPFeCl (––), TPPFe-pcyd (---) (1) and
TPPFe-(2,3,4,6-Cl4pcyd) (. . .) (4), 10ꢀ6 M in benzene.
to those of the Clꢀ, N3 and NCSꢀ iron porphyrin species
ꢀ
in the soret region. These data confirm the existence of
high-spin iron(III) oxidation and spin states, since the
UV–Vis spectra of metalloporphyrins are sensitive to the
oxidation and spin state of metals [42]. Fig. 3 also shows
higher absorption coefficients of 1 and 4 due to coordina-
tion of longer p-conjugated axial ligand.
4.3. X-ray diffraction studies
The structure of TPPFe(2,6-Cl2pcyd) (3) has been stud-
ied by X-ray diffraction. Two views of 3 with heavy atom
numbering are shown in Fig. 4. Selected bond lengths
and angles are presented in Table 4. Iron is five-coordinate
in slightly distorted square pyramidal environment with the
2,6-dichlorophenylcyanamide in the axial position. The
˚
bond distances for Fe–Neq are 2.063(5) A and the displace-
Fig. 4. (a) Atom-numbering scheme and (b) molecular structure of
TPPFe(2,6-Cl2pcyd) (3). Displacement ellipsoids at 50% for (a) and 30%
for (b) probability level.
ment of iron from the plane of core porphyrin 24 atoms is
0.47(1) A. These parameters are consistent with the param-
˚
eter observed for high-spin five-coordinated iron(III) por-
phyrins [43]. For example, bond length Fe–Neq and
displacement of iron(III) for TPPFeI and TPPFeNCS are
Table 4
a
˚
Selected bond lengths (A) and angles (°) for [TPPFe(2,6-Cl2pcyd)] Æ CHCl3
(3)
˚
˚
2.060, 0.53 A and 2.065, 0.49 A, respectively [44].
There are many crystal structures of monodentate phe-
nylcyanamide ligands showing coordination through the
cyano-nitrogen, but there are no examples of amide–nitro-
gen coordination [15]. The anionic cyanamide group of
the ligand cyanamide is shown to be planar with the phe-
nyl group due to strong p-coupling between them. A sig-
nificant degree of p bonding between the cyanamide
group and Fe(III) d-orbital is indicated with the angle
of 154° observed in the iron with axial NC and short
Bond lengths
Fe–N(1)
Fe–N(2)
Fe–N(3)
Fe–N(4)
Bond angles
2.071(6)
2.057(5)
2.066(6)
2.059(5)
1.905(6)
1.183(9)
1.269(10)
1.398(9)
1.395(11)
1.400(10)
Fe–N(5)–C(57)
N(5)–C(57)–N(6)
C(57)–N(6)–C(51)
N(1)–Fe–N(2)
N(2)–Fe–N(4)
N(4)–Fe–N(3)
N(3)–Fe–N(1)
N(2)–Fe–N(3)
N(1)–Fe–N(4)
N(1)–Fe–N(5)
N(3)–Fe–N(5)
N(4)–Fe–N(5)
N(2)–Fe–N(5)
154.2(6)
171.1(7)
129.3(7)
87.1(2)
155.9(2)
87.0(2)
151.4(2)
87.4(2)
86.7(2)
106.8(2)
101.8(2)
103.8(2)
100.2(2)
Fe–N(5)
N(5)–C(57)
C(57)–N(6)
N(6)–C(51)
C(51)–C(52)
C(51)–C(56)
˚
bond length of Fe–N5 (1.905 A). For the TPPMn(4-Mep-
cyd), the Mn–NC axial angle of 135.8° and the metal
˚
axial ligand distance of 2.075 A have been reported [40].
NCN moiety is almost linear with the N(5)–C(57)–N(6)
angle of 171.1°.
a
Estimated SDs are in parentheses. Torsion angle C(57)–N(6)–C(51)–
C(56), 29.41(2).
Fe–axial ligand distances in high-spin 5-coordinated
˚
iron porphyrins range from 1.957 A in TPPFeNCS to
TPPFe(OClO3) of Fe–O = 2.029, TPPFe(SbF5) of Fe–
F = 2.105 and TPPFe(B11CH12) of H–Fe = 1.82 were
observed. A relatively short distance of Fe–Nax in the iron
˚
2.554 A in TPPFeI. Shorter distances between iron and
axial ligands for intermediate spin complexes such as

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H. Chiniforoshan et al. / Inorganica Chimica Acta 359 (2006) 2101–2106
[19] I. Bertini, A. Rosato, Turano, Pure Appl. Chem. 71 (1999) 1717.
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[22] J. Wojaczynski, L. Latos-Grazynski, J. Chmielewski, Van Calcar,
A.L. Balch, Inorg. Chem. 38 (1999) 3040.
phenylcyanamide complex in 2 may be an indication for
small population of intermediate spin in these systems.
Acknowledgement
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Committee Grant No. 31-959.
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