Preparation of monometallic complexes of non-macrocyclic ligands

Article abstract of DOI:10.1246/bcsj.78.1047

Dicompartmental non-macrocyclic ligands containing six (N₄O ₂) and four (N₂O₂) coordination atoms were prepared. The ligands were constructed in order to investigate the effect of an opened four-coordination site (non-marcocyclic effect) on the geometrical structure of a complex in a six-coordination site with a labile metal. In this regard, monometallic non-macrocyclic complexes of Zn(II), Co(II), and Co(III) were prepared and characterized. The preparation of a Co(III) complex through two different routes, and also the X-ray crystal structure of a Zn(II) complex demonstrated that the structures of the complexes were intact even in the presence of two bulky phenyl groups in four-coordination site. The characterization of the prepared complexes confirmed the presence of two protons in the four-coordination site of diimine complexes and a lack of them in diamine complexes.

Full text of DOI:10.1246/bcsj.78.1047

ꢀ 2005 The Chemical Society of Japan
Bull. Chem. Soc. Jpn., 78, 1047–1053 (2005) 1047
Preparation of Monometallic Complexes of Non-Macrocyclic Ligands
ꢀ
Ahmad Niazi Rahnama, Hamid Golchoubian, and Robin Pritchard1
Department of Chemistry, University of Mazandaran, P.O. Box 453, Babol-sar, Iran
1Department of Chemistry, University of Umist, Manchester, UK, M601QD
Received November 4, 2004; E-mail: h.golchobian@umz.ac.ir
Dicompartmental non-macrocyclic ligands containing six (N4O2) and four (N2O2) coordination atoms were pre-
pared. The ligands were constructed in order to investigate the effect of an opened four-coordination site (non-marco-
cyclic effect) on the geometrical structure of a complex in a six-coordination site with a labile metal. In this regard, mono-
metallic non-macrocyclic complexes of Zn(II), Co(II), and Co(III) were prepared and characterized. The preparation of
a Co(III) complex through two different routes, and also the X-ray crystal structure of a Zn(II) complex demonstrated
that the structures of the complexes were intact even in the presence of two bulky phenyl groups in four-coordination
site. The characterization of the prepared complexes confirmed the presence of two protons in the four-coordination site
of diimine complexes and a lack of them in diamine complexes.
The chemistry of metal complexes with dicompartmental li-
gands has become a rapidly growing area of research, because
of their importance in biomimetic studies of binuclear metallo-
N
N
N
N
N
N
N
N
N
N
N
N
proteins, their interesting catalytic properties, their ability to
stabilize unusual oxidation states and mixed-valance com-
pounds, and possibilities for a magnetic interaction between
the two metal ions, leading to the design of molecular magnet-
ic materials.1–4 Mono- and bimetallic complexes of macrocy-
clic ligands of type 1 have been prepared, and their structures
and reactivities investigated by Bosnich,5–10 Busch,11 and
us.12,13 Such ligands contain two compartments: one includes
six coordination atoms (N4O2), and the other has a tetradentate
N2O2 donor set. The two metals are bridged by phenolic oxy-
gen ligands, and the two compartments are completed by two
links, a close-site link and an open-site link (Chart 1). The
effect of an open-site link on the geometry of the metal on
the 6-coordinate site of macrocyclic complexes was investigat-
ed, and showed that an open-site linkage influences the struc-
tural geometry of metal in a 6-coordinate site.14 Based on our
knowledge, such investigations have not been employed on
any non-macrocyclic ligand. The propose of this work was
to investigate the stereochemistry of metal in a 6-coordinate
site of a non-macrocyclic system. The ligands chosen for this
O
O
O
O
O
O
N
N
Ph
Ph
O
O
HN Ph
HN Ph
L1
L2
L3
Scheme 1. Non-macrocyclic dicompartmental ligands.
investigation were L2 and L3, which can be prepared from
monometallic complexes of ligand L1. These ligands are
shown in Scheme 1.
Results and Discussion
Synthesis. Monometallic zinc(II) and cobalt(II) complexes
were prepared by the methods outlined in Fig. 1. Compounds
Li2L17 and ML110 were prepared by published procedures and
used as starting materials to prepare monometallic complexes
ML2 and ML3. The reaction of ML1 with two equivalents of
aniline under acid catalysis10 resulted in monometallic diproto-
nated ML2 complexes that were separated as solids from solu-
tion by the addition of saturated NH4PF6. The solid spin-free
CoIIL2 complex was indefinitely stable in air, but slowly oxi-
dized in air when dissolved in CH3CN solution (Fig. 1).
The characterization results of the diamagnetic ZnL2 com-
plex by 1H NMR indicated the presence of two protons in
the N2O2 cavity, as was observed for its analogous macrocy-
clic complexes.9 The corresponding amine complexes were
N
N
N
N
O
O
N
N
close-site link
open-site link
ꢁ
prepared by BH4 reduction of the imine compounds. In this
1
way, ZnL3 and CoL3 were prepared as solids. Unlike the cor-
responding imine complexes, the presence of the protons was
Chart 1.
Published on the web June 6, 2005; DOI 10.1246/bcsj.78.1047

1048 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Preparation of Non-Macrocyclic Complexes
N
N
O
O
N
N
LiO
LiO
Route B
Route A
M = Co, Zn
a'
a
N
N
N
O
N
O
O
O
O
O
CoII
M
N
N
O
O
N
N
b'
M = Co, Zn
b
+
+2
N
N
N
O
O
N
O
H+
H+
O
O
N
N
CoIII
M
N
N
O
Ph
N
N
M = Co, Zn
c
d
c'
+3
N
N
N
O
N
O
H+
H+
HN
N
N
CoIII
M
N
N
H
O
O
N
Ph
Ph
N
N
e
d'
M = Co
N
+
N
O
O
HN
CoIII
N
H
N
Ph
N
Fig. 1. Synthetic transformations. The following reagents/solvents were used. Reaction a, a0, and b0: see Ref. 10. Reaction b:
PhNH2 and HOAc; MeOH. Reaction c: NaBH4; CH3CN. Reaction d and e: ferrocenium ion; CH3CN. Reaction c0: PhNH2 and
HOAc; CH3CN. Reaction d0: NaBH4; CH3CN.
not observed in the N2O2 cavity of the amine complexes and
complexes were neutral and almost insoluble in common sol-
vents. The 1H NMR spectrum of the diamagnetic complex
[CoIIIL3]þ indicated that the structure possesses C2 symmetry
in solution. There are three possible topological isomers for
complexes type ML2 and ML3,8 as shown in Scheme 2. Two
of these possess C2 symmetry, whereas the third is an unsym-
metrical C1 isomer with cis-disposed pyridines and cis-pheno-
lates. C2 symmetrical isomers correspond to either cis-pyri-
dines and trans-phenolates or trans-pyridines and cis-phe-
nolates. To investigate the structures of ML2 and ML3 in solu-
tion, two different routes to prepare [CoIIIL3]þ were carried
out. In route A (Fig. 1), first the dialdehyde complex [CoIIL1]
was prepared,10 which was then converted to the diimine
compound [CoIIL2(Hþ)2]2þ by two equivalents of aniline.
In the next step, the [CoIIL2(Hþ)2]2þ was oxidized to

A. Niazi Rahnama et al.
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1049
H
N
N
O
Co
O
N
N
N
N
N
N
O
O
N
O
N
HN
HN
Co
Co
HN
N
N
O
N
HN
HN
C
C
C
1
2
2
Scheme 2. Different possible topological isomers for [CoL3]þ.
[CoIIIL2(Hþ)2]3þ by ferrocenium ions (Fcþ). Finally, the re-
sulting diimine complex was reduced to its diamine counter-
part, [CoIIIL3]þ, by a reducing agent of NaBH4ꢁ. Alternative-
ly, in route B (Fig. 1) the prepared CoIIL1 was oxidized to
[CoIIIL1]þ by Fcþ. This compound was then reacted with
two equivalents of aniline to obtain [CoIIIL2(Hþ)2]3þ as a
dark-green solid upon the addition NH4PF6. Finally, the di-
imine cobalt(III) complex was reduced to its diamine counter-
part by NaBH4. Since [CoIIIL1]þ was proved to be stable
against isomerization, and also its structure was determined
to have a C2 symmetry structure with trans-pyridines and
cis-phenolates,10 it was used as a starting material to prepare
of [CoIIIL2(Hþ)2]3 and [CoL3]þ. The identification of
[CoL3]þ, obtained through the two routes, implies that isomer-
ization is less likely to occur under the condition used to
perpare of ML2 and ML3, and confirmed that presence of
two bulky phenyl groups in the open-site dose not influence
the structural geometry of metal in the close-sit, even with a
labile metal, such as Co(II) and Zn(II). As a result, these com-
plexes have structures with trans-pyridines and cis-phenolates.
All attempts to accommodate metal into the N2O2 cavity of
monometallic complexes ML2 and ML3 were not successful,
but resulted in a recovery of the starting materials. The major
factor in our inability to form bimetallic complexes may be
due to a steric-repulsion of the N-Ph groups so that the N-Ph
moieties are tilted above and below the mean molecular plane
and the bite angles associated with the N2 (imine or amine) are
expanded. As a result the second metal can not bind to the
N2O2 coordinating atoms. This conclusion was confirmed by
the crystal structure of ZnL2, which we now discuss.
Table 1. Electrospray Mass Spectral Data for Monometallic
Complexes of ML2 and ML3
Compound
½ZnL2(Hþ)2](PF6)2
Ions (ESMS) (m=z)aÞ
{[ZnL2(Hþ)2]2þ ꢁ Hþ}þ, (751)
[ZnL2(Hþ)2]2þ, (376)
½CoIIIL2(Hþ)2](PF6)3 {[CoL2(Hþ)2]3þ ꢁ 2Hþ}þ, (745)
{[CoL2(Hþ)2]3þ ꢁ Phþ-(Hþ)}þ, (670)
{[CoL2(Hþ)2]3þ ꢁ Phþ}2þ, (336)
½CoL3]PF6
[CoL3]þ, (749)
{[CoL3]þ ꢁ Py}þ, (670)
{[CoL3]þ ꢁ PhNHꢁ}2þ, (329)
a) Most intense peak of isotopic mass distribution.
ity of the ML3 complexes could be due to a greater flexibility
of the amine compounds compared with their imine counter-
parts, which result in more twisting of the phenyl groups and
the amine nitrogens, so that hydrogen bonding might not be
achieved between the oxygens of the phenolic groups and
the nitrogens of the amine groups.
The resulting monometallic complexes were characterized
by elemental analysis, molar conductance, ESMS, 1H NMR,
UV–vis, and IR spectroscopy.
IR Spectra. The infrared spectra of the diimine and di-
amine monometallic complexes are very similar. Significant
differences between the diimines and diamines in the spectra
are the emergence of a sharp, but weak, band at about 3370
cmꢁ1, which is attributed to the N–H stretch of the quaternized
amine, and the disappearance of a strong band at about 1650
cmꢁ1, corresponding to the C=N stretch of the imine groups.17
Electrospray Mass Spectra. Electrospray mass spectrom-
etry is proving to be a very powerful analytical tool for the
characterization of macromolecule complexes in the liquid
phase, because it allows for the transfer of preexisting ions
from solution to the gas phase with minimal fragmenta-
tion.18,19 All major signals for the complexes, including the as-
signments, are listed in Table 1. Particularly noteworthy is that
the presence of a given metal centre is accompanied by a set of
signals for each m=z due to the relative isotope abundance. The
number and relative intensities of these peaks are unique for
each monometallic complex.
Physical Characterization.
All imine complexes of
[MIIL2(Hþ)2]2þ are soluble in polar solvents, such as acetoni-
trile and acetone, and show 2:1 electrolytes in an acetonitrile
solution. However, bivalent metal complexes of type ML3
are insoluble in all common solvents. The characterization of
these complexes reveals a lack of protons in the N2O2 cavity
of the ML3 complexes, whereas the ML2 complexes do show
the presence of two protons in the N2O2 cavity. The protonated
monometallic complexes of the macrocyclic binucleating li-
gand have previously been reported.15 Bosnich and co-workers
reported that each proton in the N2O2 cavity interacts with
oxygen of the phenolate and the nitrogen of the imine or amine
moieties.9 As a result, the absence of protons in the N2O2 cav-
Electronic Absorption Spectroscopy. The electronic ab-
sorption spectra of the diimine and diamine complexes were

1050 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Preparation of Non-Macrocyclic Complexes
Table 2. Electronic Absorption Maxima and Intensities of the Charge Transfer
Complex
½ZnL2(Hþ)2](PF6)2
ꢀmax (ꢁ, l molꢁ1 cmꢁ1
)
209(16352)
196(49100)
235(25800)
235(38240)
261(48000)
252(21470)
325(18432)
320(23632)
369(22300)
436(14080)
444(14496)
435(7752)bÞ
426(3584)bÞ
aÞ
½CoIIL2(Hþ)2](PF6)2
½CoIIIL2(Hþ)2](PF6)3
½CoIIIL3]PF6
205(29360)
a) Spectrum run in deaerated condition. b) Tail into NIR region.
measured in acetonitrile solutions over the range of 190–800
nm. The absorption peaks and their corresponding extinction
coefficient are given in Table 2. All of the diimine complexes
show an intense absorption band at between about 325 and 369
nm, which is ascribed to the transitions of the azomethine
chromophores.20 The d–d transitions of the Co(II) and Co(III)
complexes were not seen, and seemed to be obscured under
charge-transfer bands, which was tailed to NIR region.
1
1H NMR. The H NMR spectra of the diamagnetic ZnII
and CoIII complexes of ligands L2 and L3, obtained in CD3CN
ꢂ
solution at 25 C, confirmed the existence of a single isomer
with a C2 symmetric structure, where the two pyridine ligands
are trans disposed. The 1H NMR spectra in CD3CN reveal
broad signals constituting two protons at 15.13 and 15.40
ppm for [ZnL2(Hþ)2](PF6)2 and two protons at 15.00 ppm
for [CoIIIL2(Hþ)2](PF6)3. These signals are assigned to the
protons in the N2O2 cavity. These signals were not observed
in [CoIIIL3]PF6. Upon the addition of a drop of D2O, rapid pro-
ton exchange occurred, and these proton signals disappeared.
Crystal Structure.
The X-ray diffraction structure of
[ZnL2(Hþ)2](PF6)2 was determined. Two views of this cation
are shown in Fig. 2, and selected bond distances and angles are
given in Table 3. The data collection and refinement parame-
ters are collected in Table 4. Since the molecule has a two-fold
symmetry, half of the atoms are numbered, and other half of
atoms with identical location properties with the first half are
shown with superscripts 2. All bond lengths are unexceptional
but certain metal donor atom angles require comment. The Zn
donor atom bond lengths (Table 3) are longer to those formed
previously for a similar complex,9 although the Zn–N(1) bonds
are slightly shorter. The N(2)–Zn–N(22) (the bite angle of the
five-membered chelate ring) is rather small (81.7(3)ꢂ) and the
opposite O(1)–Zn–O(12) angle is relatively large (103.3(7)ꢂ);
they are compressed and broadened, respectively, compared
with the analogous Zn complex.9 The Zn(II) ion is in the six-
coordination site and pseudo octahedrally coordinated to two
amine nitrogen donors, two phenolic oxygen donors, and two
trans-pyridine nitrogens; its structure is C2 symmetric. The
absolute configuration about Zn(II) is ꢀ, ꢀ, ꢁ, and the config-
uration about the nitrogen atoms of the amine group are R, R.
Fig. 2. Two views of the molecular structure of the cation
of [ZnL2(Hþ)2](PF6)2 drawn with 30% probability ellip-
soids. The hydrogen atoms have been omitted for clarity.
ꢂ
Table 3. Selected Bond Lengths (A) and Angles (deg) for
[ZnL2(Hþ)2]2þ
ꢂ
Bond distances/A
ꢂ
Zn–O(1)
Zn–N(1)
Zn–N(2)
2.059 (5)
2.133 (6)
2.241 (6)
N(3)–C(16)
N(3)–C(17)
N(2)–C(7)
1.321 (10)
1.407 (10)
1.476 (10)
The imine groups are tilted 0.681 A above and below of the
plane defined by N(2), N(22), O(1), O(12); the Zn(II) ion is
located in this plane. The open-site cavity defined by two phe-
nolic oxygen atoms and the two imine nitrogen atoms is large.
The four potential donor atoms (N(3), N(32), O(1), O(12)) can
not lie in the one plane; the diagonal distances O(1)–N(32) and
ꢂ
O(1 )–N(3) are the same (4.493 A) and too large to accommo-
date a metal ion of the first transition series. Hydrogen bonding
is believed to exist across the O(1) and N(3) and O(12) and
ꢂ
N(3 ); these distances are identical (2.593 A).
Bond angles/deg
O(1)–Zn–O(12)
O(1)–Zn–N(22)
O(12)–Zn–N(22)
O(1)–Zn–N(1)
N(2)–Zn–N(12)
103.0 (3)
167.2 (2)
88.1 (2)
93.8 (2)
92.0 (2)
N(2)–Zn–N(22)
N(1)–Zn–N(12)
N(2)–Zn–O(12)
N(1)–Zn–N(2)
N(1)–Zn–O(12)
81.7 (3)
168.9 (4)
167.2 (2)
79.6 (2)
93.1 (2)
2
2

A. Niazi Rahnama et al.
Table 4. Crystal Data for [ZnL2(Hþ)2](PF6)2
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1051
Compound
[ZnL2(Hþ)2](PF6)2
Empirical formula
Formula weight
Temperature
C44H44F12N6O2P2Zn
1044.16
150(2) K
ꢂ
0.71073 A
Wavelength
Crystal system
Space group
Unit cell dimensions
Monoclinic
C2=c
ꢂ ¼ 90:000ð8Þꢂ
ꢃ ¼ 106:334ð6Þꢂ
ꢄ ¼ 90:000ð15Þꢂ
ꢂ
a ¼ 10:3420ð18Þ A
ꢂ
b ¼ 31:324ð7Þ A
ꢂ
c ¼ 14:163ð2Þ A
ꢂ 3
Volume
Z
4402.9(15) A
4
Density (calculated)
Absorption coefficient
F(000)
Crystal size
Theta range for data collection
Index ranges
Reflections collected
Independent reflections
Completeness to theta = 24.99ꢂ
Absorption correction
Max. and min. transmission
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2sigmaðIÞ]
R indices (all data)
Extinction coefficient
Largest diff. peak and hole
1.575 mg mꢁ3
0.728 mmꢁ1
2136
0:20 ꢃ 0:20 ꢃ 0:15 mm3
1.30 to 24.99ꢂ
ꢁ12 5 h 5 12, ꢁ33 5 k 5 37, ꢁ16 5 l 5 16
12031
3591 [RðintÞ ¼ 0:1464]
92.5%
Semiempirical from equivalents
0.8986 and 0.8681
Full-matrix least-squares on F2
3591/21/402
1.132
R1 ¼ 0:0940, wR2 ¼ 0:1404
R1 ¼ 0:1850, wR2 ¼ 0:1764
0.00027(9)
ꢂ 3
ꢁ
0.548 and ꢁ0:401 e A
corded using a Bruker FT-IR instrument; only strong peaks are
given. The electronic absorption spectra were measured by using
a Cecil 5000 model UV–vis spectrophotometer using spectral-
grade CH3CN. Elemental analyses were performed on a LECO
600 CHN elemental analyzer. Absolute metal percentages were
determined by an atomic absorption-flame spectrometer. The
1H NMR spectra were recorded on a Bruker 500 Fourier transform
spectrometer. Electrospray mass studies were conducted on a VG
Quattro II (Fision) triple-quadruple electrospray mass spectrome-
ter with methanol and as the mobile phase. The compound was
dissolved in a mixture of acetonitrile and methanol (1:1), and
was injected directly into the spectrometer via a Rheodyne injec-
tor using a Fision LC syringe pump to deliver the solution at a
flow rate of 20 mL sꢁ1. Nitrogen was used for nebulization and
as a drying gas with flow rates of approximately 20 and 250
L hꢁ1, respectively. All samples were dried to constant weight
under high vacuum prior to analysis.
Conclusion
This work served to illustrate the preparation and physical
propertied of monometallic complexes the binucleating non-
macrocyclic ligands, which are diimine and diamine, and are
attached to phenyl groups. The characterization of the prepared
complexes demonstrated the presence of two protons in the
four-coordination site of the diimine complexes of ML2,
whereas, a lack of protons occurred in the diamine ML3 com-
plexes. This could be due to more flexibility provided in the
amine compounds compared with their imine counterparts
which, results in more twisting of the phenyl groups and the
amine nitrogens, so that hydrogen bonding might not be
achieved between the oxygens of the phenolic groups and
the nitrogens of the amines groups. The preparation of the
monometallic complexes of ML3 from two different routes im-
plies that the structures of the complexes are intact even in the
present of a labile metal in the six-coordination site. The X-ray
crystal structure of ZnL2 showed that two phenyl groups are
tilted above and below the mean molecular plane due to the
steric repulsion of two phenyl groups, and is perhaps the major
factor for the inability to accommodate the second metal in the
N2O2 site.
Materials. Acetonitrile used was distillated over CaH2. All
preparations of Co(II) complexes were conducted under argon
using deaerated solvents. The compounds Li2L1,7 CoIIL1,
10
[CoIIIL1]PF6, and ZnL1 were prepared by standard methods
found in the literature.
[ZnL2(Hþ)2](PF6)2. To a stirred suspension of ZnL1 (0.5 g,
0.81 mmol) in methanol (20 mL) was added dropwise over 1 h
a solution of aniline (150 mL, 1.62 mmol) and acetic acid (95
mL, 1.66 mmol) in ethanol (10 mL). After the addition was com-
pleted, all starting materials were dissolved. The yellow solution
was stirred for 3 h. A yellow solid precipitated almost immediate-
ly after the addition of a filtered solution of NH4PF6 (0.37 g, 2.30
Experimental
ꢂ
Apparatus. Conductance measurements were made at 25 C
with a Jenway 400 conductance meter on 1:00 ꢃ 10ꢁ3 M samples
in CH3CN. Infrared spectra (potassium bromide disk) were re-

1052 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Preparation of Non-Macrocyclic Complexes
mmol) in ethanol (10 mL). The solid was collected and was wash-
ed with ethanol (2 ꢃ 10 mL), Et2O (2 ꢃ 10 mL), hexane (2 ꢃ 10
mL). The crude compound was recrystallized, which yielded
[ZnL2(Hþ)2](PF6)2 as yellow needles (77%). A crystal suitable
for X-ray crystal structure determination was grown by vapor dif-
fusion of ethanol into a CH3CN: ethanol solution of the complex.
ꢁm ¼ 273 ꢃꢁ1 molꢁ1 cm2. Anal. Found: C, 50.43; H, 4.08; N,
8.26; Zn, 6.33%. Calcd for C44H44N6O2P2F12Zn: C, 50.61; H,
4.25; N, 8.05; Zn, 6.26%. FT-IR (KBr disk) 1645 (C=N), 2940
solid precipitated almost immediately. After precipitation was
completed deaerated acetic acid (342.4 mL, 6 mmol) was added
to the reaction mixture, which produced a small amount of gas
evolution. The solid was then collected and washed with water
(3 ꢃ 5 mL), ethanol (3 ꢃ 5 mL), Et2O (3 ꢃ 5 mL), and hexane
(2 ꢃ 5 mL), and dried under high a vacuum (54%). The resulting
product was stable as a solid in air. Anal. Found: C, 70.12; H,
6.20; N, 11.48; Co, 7.56%. Calcd for C44H46N6O2Co: C, 70.48;
H, 6.18; N, 11.21; Co, 7.68%. FT-IR (KBr disk) 1604 (N–H
bend), 2938 (N–CH2), 1451 (aromatic skeleton), 3368 (N–H
(N–CH2), 1450 (aromatic skeleton) cmꢁ1 1H NMR (500.13
.
MHz, CD3CN): ꢅ 2.26 (s, 6H), 3.05, 3.15 (sys AB, JAB ¼ 10:3
Hz, 4H), 3.60 (d, J ¼ 13:0 Hz, 2H), 4.10–4.40 (m, 6H), 7.00–
7.50 (m, 20H), 7.82 (t, J ¼ 7:9 Hz, 2H), 8.63 (d, J ¼ 10:4 Hz,
1H), 8.79 (d, J ¼ 5:1 Hz 1H), 15.13 (br s, 1H), 15.40 (br s, 1H).
[CoL2(Hþ)2](PF6)2. This compound was prepared by the
general procedure described for [ZnL2(Hþ)2](PF6)2. Fine orange
needles were obtained after recrystallization (90%). ꢁm ¼ 283
stretch) cmꢁ1
[CoIIIL3]PF6.
[CoIIIL2(Hþ)2](PF6)3 (0.5 g, 0.423 mmol) in CH3CN (10 mL) at
ꢂC was added dropwise over 15 min a solution of NaBH4
.
Methode 1: To
a stirred solution of
0
(0.32 g, 0.85 mmol) in deaerated ethanol (10 mL). The resultant
dark solution was stirred for 30 min at 0 ꢂC, and was then warmed
to 25 ꢂC over 15 min. Acetic acid (342.4 mL, 6 mmol) was added
to the reaction mixture and a small amount of gas evolution was
observed. The solution was heated to 90 ꢂC and water (5 mL)
was added. The solvents were slowly distilled off over 30 min un-
til a dark solid precipitated. After cooling the suspension to room
temperature, the solid was collected, washed with warm water
(3 ꢃ 5 mL), ethanol (3 ꢃ 5 mL), Et2O (3 ꢃ 5 mL), and hexane
(2 ꢃ 5 mL), and dried under vacuum. The crude product was re-
crystallized (60%). ꢁm ¼ 151 ꢃꢁ1 molꢁ1 cm2. Anal. Found: C,
58.79; H, 5.02; N, 9.55; Co, 6.44%. Calcd for C44H46N6O2PF6Co:
C, 59.06; H, 5.18; N, 9.39; Co, 6.59%. FT-IR (KBr) 1602 (N–H
bend), 2940 (N–CH2), 1455 (aromatic skeleton), 3360 (N–H
ꢃ
ꢁ1 molꢁ1 cm2 (taken under deaerated condition). Anal. Found:
C, 50.67; H, 4.48; N, 8.26; Co, 5.51%. Calcd for
C44H44N6O2P2F12Co: C, 50.93; H, 4.27; N, 8.10; Co, 5.68%.
FT-IR (KBr disk) 1650 (C=N), 2942 (N–CH2), 1447 (aromatic
skeleton) cmꢁ1
.
[CoIIIL2(Hþ)2](PF6)3. Method 1: To a stirred solution of the
[CoL2(Hþ)2](PF6)2 (0.25 g, 0.24 mmol) in deaerated CH3CN (5
mL) under argon was added [Cp2Fe]PF6 (0.80 g, 0.24 mmol) in
deaerated CH3CN (5 mL). The resultant dark solution was stirred
under argon for 30 min, and was then opened to the air and con-
centrated to dryness. The residue was triturated with Et2O (3 ꢃ 5
mL) in order to remove Cp2Fe. The residue was collected, washed
with ethanol (2 ꢃ 5 mL), Et2O (2 ꢃ 5 mL), and hexane (2 ꢃ 5
mL) and dried under a vacuum. The dark solid was recrystallized,
which yielded 90%. ꢁm ¼ 378 ꢃꢁ1 molꢁ1 cm2. Anal. Found:
C, 44.32; H, 3.77; N, 7.39; Co, 4.80%. Calcd for
C44H44N6O2P3F18Co: C, 44.68; H, 3.75; N, 7.11; Co, 4.98%.
FT-IR (KBr) 1642 (C=N), 2943 (N–CH2), 1452 (aromatic skele-
stretch) cmꢁ1 1H NMR (500.13 MHz, CD3CN) ꢅ 2.79 (s, 6H),
.
3.00–5.00 (m, 16H), 5.07 (m, 2H), 6.00–8.20 (m, 22H).
Method 2: To a stirred suspension of the CoIIL3 (0.20 g, 0.27
mmol) in deaerated CH3CN (5 mL) under argon was added
[Cp2Fe]PF6 (0.72 g, 0.27 mmol) in deaerated CH3CN (5 mL).
The initial light-brown suspension slowly turned black upon the
addition of [Cp2Fe]PF6. The reaction mixture was stirred for 1
h, and was then filtered through Celite. The filtrate was concen-
trated to dryness. The product was triturated with Et2O (3 ꢃ 10
mL) in order to remove Cp2Fe. The residue was collected and
washed with ethanol (2 ꢃ 3 mL), Et2O (3 ꢃ 5 mL), and hexane
(2 ꢃ 5 mL), and dried under a vacuum. The crude product was re-
crystallized (47%). Anal. Found: C, 59.37; H, 4.93; N, 9.35; Co,
6.70%. Calcd for C44H46N6O2PF6Co: C, 59.06; H, 5.18; N,
9.39; Co, 6.59%. The identity of the obtained compound was con-
firmed by 1H NMR, UV–vis, and IR spectra, whose characteristics
compared well with those prepared by method 1.
1
ton) cmꢁ1. H NMR (500.13 MHz, CD3CN): ꢅ 2.35 (s, 6H), 3.12
(m, 2H), 3.50–4.00 (m, 6H), 4.50–5.00 (m, 4H), 7.00–8.10 (m,
20H), 9.05 (m, 2H), 10.04 (s, 2H), 15.00 (br s, 2H). When one
1
drop of D2O was added to the H NMR sample, the broad signal
at 15.00 ppm disappeared.
Method 2: To a stirred solution of [CoIIIL1]PF6 (0.30 g, 0.5
mmol) in CH3CN (10 mL) was added dropwise over 1 h a solution
of aniline (92 mL, 1 mmol) and acetic acid (115 mL, 2 mmol) in
ethanol (10 mL). The dark solution was stirred for 3 h. A filtered
solution of NH4PF6 (0.08 g, 0.5 mmol) in ethanol (2 mL) then
added to the solution, and the resultant dark solution was taken
to dryness. The residue was collected, washed with ethanol
(2 ꢃ 5 mL), Et2O (2 ꢃ 5 mL), and hexane (2 ꢃ 5 mL) and dried
under a vacuum. The yield of the reaction after purification was
60%. Anal. Found: C, 44.54; H, 3.99; N, 7.21; Co, 4.82%. Calcd
for C44H44N6O2P3F18Co: C, 44.68; H, 3.75; N, 7.11; Co, 4.98%.
The identity of the compound obtained was confirmed by
1H NMR, UV–vis, and IR spectra, whose characteristics compared
well with those prepared by method 1.
ZnL3. This compound was prepared by the method used to
prepare CoIIL3. ZnL3 was obtained as a white solid (59%). This
compound was almost insoluble in common solvents. Anal.
Found: C, 69.98; H, 5.81; N, 11.02; Zn, 8.60%. Calcd for
C44H46N6O2Zn: C, 69.88; H, 6.13; N, 11.11; Zn, 8.65%. FT-IR
(KBr disk) 1610 (N–H bend), 2943 (N–CH2), 1452 (aromatic
skeleton), 3370 (N–H stretch) cmꢁ1
Crystallographic Structural Determination.
.
The single-
crystal X-ray diffraction structure of [ZnL2(Hþ)2](PF6)2 was de-
termined at 150(2) K. The crystallographic data are summarized
in Table 4. The data were measured on a Nonius Kappa CCD dif-
fractometer using graphite-monochromated radiation. The struc-
ture was solved by direct methods using SHELXS, and subjected
to full-matrix leastsquares using SHELXL. Non-hydrogen atoms
were refined anisotropically, and hydrogen atoms were subjected
to isotropic refinement. The zinc atom was located on a crystallo-
graphic two-fold axis, so that the asymmetric unit only contained
Preparation Amine Complexes. The amine complexes are
air stable as solids. These complexes were purified by recrystalli-
zation from CH3CN–C2H5OH by the same procedure as described
for the imine complexes.
CoIIL3. To a stirred solution of [CoL2(Hþ)2](PF6)2 (0.30 g,
0.29 mmol) in CH3CN (10 mL) under a argon atmosphere and
at 0 ꢂC was added dropwise over 15 min a solution of NaBH4
(0.22 g, 0.58 mmol) in deaerated ethanol (5 mL). A light-brown

A. Niazi Rahnama et al.
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1053
half of the ligand system, and other half was generated by a sym-
metry operation. One of the PF6 anions was disordered and some
of its fluorine atoms were distributed over two, semipopulated
sites.
5
24 (2003).
A. L. Casvrilova and B. Bosnich, Inorg. Chim. Acta, 325,
6 D. G. McCollum, G. P. A. Yap, L. Liable-Sands, A. L.
Rheingold, and B. Bosnich, Inorg. Chem., 36, 2230 (1997).
Crystallographic data have been deposited with Cambridge
Crystallographic Data Centre: Deposition number CCDC-CCDC
262374 for compound ZnL3. Copies of the data can be obtained
free of charge via http//www.ccdc.cam.ac.uk/conts/retrieving.html
(or from the Cambridge Crystallographic Data Centre, 12, Union
Road, Cambridge, CB2 1EZ, UK; Fax: +44 1223 336033; e-mail:
deposit@ccdc.cam.ac.uk).
7
D. G. McCollum, G. P. A. Yap, A. L. Rheingold, and B.
Bosnich, J. Am. Chem. Soc., 118, 1365 (1996).
D. G. McCollum, L. Hall, C. White, R. Ostrander, A. L.
8
Rheingold, J. Whelan, and B. Bosnich, Inorg. Chem., 33, 924
(1994).
9
Bosnich, Inorg. Chem., 33, 324 (1994).
C. Fraser, R. Ostrander, A. L. Rheingold, C. White, and B.
10 C. Fraser, L. Johnston, A. L. Rheingold, B. S. Haggerty,
G. K. Williams, J. Whelan, and B. Bosnich, Inorg. Chem., 31,
1835 (1992).
11 E. V. Rybak-Akimova, N. W. Alcock, and D. H. Busch,
Inorg. Chem., 37, 1563 (1998).
We express our appreciation to the University of Mazandar-
an of Islamic Republic of Iran for financial support. We also
thank Dr. Amiri for performing the electospray mass analysis
of the samples.
12 H. Golchoubian, W. L. Waltz, and J. W. Quail, Can. J.
Chem., 37, 77 (1999).
13 H. Golchoubian and W. L. Waltz, Synth. Commun., 28,
3907 (1998).
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