M. Khorasani-Motlagh et al. / Inorganica Chimica Acta 362 (2009) 1260–1266
1261
2.1. Synthesis of [OEPFe(L]) (L = pcyd (2), 2-Clpcyd (3), 2-Mepcyd (4),
3. Results and discussion
2,4-Me2pcyd (5))
3.1. Formation of [OEPFe(L]) (L = pcyd (2), 2-Clpcyd (3), 2-Mepcyd (4),
2,4-Me2pcyd (5))
The four compounds were prepared as following procedure:
Thallium phenylcyanamide salt (0.80 mmol) was added to dichlo-
romethane solution of [OEPFeCl] (1) (25 mg, 0.04 mmol) under N2
atmosphere. The reaction mixture was stirred for 1 h to produce
brown-red solution. The mixture was filtered and the resulting
clear solution was evaporated to dryness under vacuum to give a
brown-red residue. The resulting solid was recrystallized by dis-
solving it in a minimum volume of dichloromethane and slowly
adding n-hexane to precipitate the product as dark red crystals.
Yields for the five compounds are around 85%. Elemental Anal. Calc.
for C43H49N6Fe (2): C, 73.17; H, 6.99; N, 11.91. Found: C, 73.02; H,
The results presented here show that phenylcyanamide anions
react with heme, [OEPFeIIICl] (1), in air to produce five-coordinate
products, [OEPFe(L)] (L = pcyd (2), 2-Clpcyd (3), 2-Mepcyd (4), 2,4-
Me2pcyd (5)) (Scheme 1). The solutions and solids of 2–5 com-
plexes are air stable, and these complexes react with HCl and pro-
duce [OEPFeCl] (1).
[OEPFe(L)] (L = pcyd (2), 2-Clpcyd (3), 2-Mepcyd (4), 2,4-Me2p-
cyd (5)) are soluble in a the range of solvents: chloroform, dichlo-
romethane, hexane, pyridine. Their behavior in non-coordinating
solvents, particularly dichloromethane and chloroform, are similar.
The UV–Vis spectra of dichloromethane solutions of 2–5 show typ-
ical heme features [13,14] with intense Soret bands in the range of
370–397 nm and Q-bands, low energy absorption, in the range of
505–640 nm. The electronic absorption spectra obtained from
6.85; N, 11.79%. UV–Vis absorption: kmax, nm (e
, cmꢀ1 Mꢀ1), 373
(5.4 ꢁ 104), 397 (6.2 ꢁ 104), 509 (7.1 ꢁ 103), 538 (7.3 ꢁ 103), 634
(5.3 ꢁ 103). IR (KBr):
m
(NCN) = 2195 cmꢀ1. Elemental Anal. Calc.
for C43H48N6FeCl (3): C, 69.76; H, 6.53; N, 11.35. Found: C, 69.63;
H, 6.42; N, 11.27%. UV–Vis absorption: kmax, nm (e
, cmꢀ1Mꢀ1),
375 (5.6 ꢁ 104), 396 (6.3 ꢁ 104), 507(7.1 ꢁ 103), 540 (7.1 ꢁ 103),
629 (5.4 ꢁ 103). IR (KBr):
m
(NCN) = 2114 cmꢀ1. Elemental Anal.
Calc. for C44H51N6Fe (4): C, 73.41; H, 7.14; N, 11.67. Found: C,
Et
Et
Et
73.34; H, 7.07; N, 11.54%. UV–Vis absorption: kmax
,
nm
(
e
,
Et
cmꢀ1 Mꢀ1), 371 (5.6 ꢁ 104), 397 (6.4 ꢁ 104), 505 (7.2 ꢁ 103), 537
Et
Et
Et
Et
Et
Et
Et
Et
Cl
Fe
L
N
N
N
(7.3 ꢁ 103), 639 (5.3 ꢁ 103). IR (KBr):
m
(NCN) = 2106 cmꢀ1. Elemen-
N
N
N
CH2Cl2
Tl L
Fe
tal Anal. Calc. for C45H53N6Fe (5): C, 73.64; H, 7.27; N, 11.45. Found:
N
N
C, 73.47; H, 7.09; N, 11.32%. UV–Vis absorption: kmax, nm (e,
cmꢀ1 Mꢀ1), 373 (5.5 ꢁ 104), 397 (6.1 ꢁ 104), 509 (7.1 ꢁ 103), 540
Et
Et
Et
(7.2 ꢁ 103), 636 (5.2 ꢁ 103). IR (KBr):
m
(NCN) = 2090 cmꢀ1
.
Et
[(OEP) Fe III Cl]
[(OEP) Fe III L]
2.2. Crystallography
(1)
Me
NCN
Crystallization of [OEPFe(pcyd)] (2) at room temperature by dif-
fusion of n-hexane into its saturated dichloromethane solutions
yielded black, tablet-shaped crystals. Measurements were made
on a Bruker X8 APEX diffractometer with graphite monochromated
(5)
Me
Me
Mo K
a radiation (k = 0.71073). The data were collected at a tem-
(4)
NCN
perature of ꢀ100 0.1 °C to a maximum 2h value of 55.7°. The
structures were solved by direct methods [11] and expanded using
Fourier techniques [12]. The non-H-atoms were refined anisotrop-
ically. All hydrogen atoms were included in calculated positions
but were not refined. The standard deviation of an observation of
unit weight was 1.00. The weighting scheme was based on count-
ing statistics. The maximum and minimum peaks on the final dif-
ference Fourier map corresponded to 0.37 and ꢀ0.32 e/Å3,
respectively.
L =
Cl
(3)
(2)
NCN
NCN
Scheme 1.
A perspective view of complex 2 is shown in Fig. 3. Some details
of the collection are given in Table 2. Selected interaction distances
and angles are given in Table 3.
2.3. Electrochemical measurement
Cyclic voltammograms were recorded on a Electroanalyzer sys-
tem Model Sama 500 (Sama research center, Esfahan, Iran) in a
three electrode cell. The working electrode was a platinum disk
with a diameter of 2 mm. Before each experiment the electrode
was polished with fine carborundum paper and 0.5 mm alumina
slurry in sequence. The electrode was then sonicated in order to re-
move the trace of alumina from the surface, washed with water
and dried. A SCE served as the reference electrode. The auxiliary
electrode was a platinum electrode. An initial background scan
was run to check the purity of the reagents and to establish the sol-
vent anodic potential range. The electrochemical measurements
were carried out at a thermostated temperature of 25.0 0.1 °C.
Tetrabutylammonium perchlorate was used as supporting
electrolyte.
300
400
500
600
700
800
Wavelength/nm
Fig. 1. The UV–Vis absorption spectra of a dichloromethane solution of [OEPFeIIICl]
(blue line) and [OEPFe(2,4-Me2pcyd)] (5) (purple line). (For interpretation of the
references to color in this figure legend, the reader is referred to the web version of
this article.)